KIM, YeonMi (501 DawonGreenVil, 685-154 Guro-don, Guro-gu Seoul 152-050, KR)
Claims
[1] An apparatus for compensating for a gas- volume error caused by temperature and pressure difference in a volumetric gas meter, the apparatus comprising: a temperature-measuring device for measuring gas-temperature inside a volumetric gas meter or inside a gas pipe near the gas meter and converting the measured temperature value into an electrical signal corresponding thereto; a pressure-measuring device for measuring gas-pressure inside the gas meter or the gas pipe and converting the measured pressure value into an electrical signal corresponding thereto; and a temperature and pressure compensation unit for receiving the electrical signals from the temperature-measuring device and the pressure-measuring device to acquire instantaneous gas temperature and pressure and, using the instantaneous gas temperature and pressure, calculating at least one of an instantaneous temperature and pressure compensation coefficient K , a daily temperature and pressure compensation coefficient and a monthly temperature and pressure compensation coefficient, the electrical signals being received at first time intervals or when consumed amount of the gas reaches a certain pre-determined value, wherein the compensation coefficient is used for compensating for a gas volume error that may be involved in a read value of the gas meter due to differences between the instantaneous temperature and pressure and a reference temperature and pressure at a reference position of gas-supplying.
[2] The apparatus as claimed in claim 1, wherein the instantaneous temperature and pressure compensation coefficient K is computed according to following equation in which P and T denote the instantaneous temperature and pressure values respectively.
Px 273.15
Ώ 1013 X073.15 + 0
[3] The apparatus as claimed in claim 1, wherein the daily temperature and pressure compensation coefficient is determined by averaging the entire instantaneous temperature and pressure coefficients computed during the day, and the monthly temperature and pressure compensation coefficient is determined by averaging the entire instantaneous temperature and pressure compensation coefficients or the entire daily temperature and pressure coefficient computed during the month.
[4] The apparatus as claimed in any one of claims 1 to 3, wherein the compensation of the daily temperature and pressure compensation coefficient or the monthly temperature and pressure compensation coefficient considers a weighted value according to whether or not gas is consumed or the amount of consumed gas when temperature and pressure are measured or during the measuring-time interval.
[5] The apparatus as claimed in claim 4, wherein the temperature and pressure compensation unit further receives digitized daily or monthly read value from an automatic reading unit automatically reading indication value of the gas meter, computes a compensated daily gas consumption by multiplying the daily read value by the daily temperature and pressure compensation coefficient of the day, and computes a compensated monthly consumption by accumulating the daily consumptions during the month or multiplying the monthly read value by the monthly temperature and pressure compensation coefficient of the month.
[6] The apparatus as claimed in claim 4, wherein the temperature and pressure compensation unit analyzes variation-pattern with time in the temperature and pressure values being acquired from the temperature-measuring device and the pressure-measuring device respectively to determine whether or not the gas is currently being consumed, and, if the gas is being consumed, the first time interval is made shorter than a case of not being consumed, thereby the weighted value being automatically reflected.
[7] The apparatus as claimed in claim 4, wherein the temperature and pressure compensation unit further includes a gas-flow detector, which detects whether or not a certain number wheel or rotation needle of the gas meter is being rotated and determine whether or not the gas is currently being consumed, and, using information on the detection of the gas-flow detector, the temperature and pressure unit determines a time period for completion of a certain number of rotations of the number wheel or rotation needle, which is then used as the first time interval, thereby the weighted value is being automatically reflected.
[8] The apparatus as claimed in claim 4, wherein the temperature and pressure compensation unit further includes a gas-flow detector having an orifice installed inside the gas meter or the gas pipe and a differential pressure sensor detecting a difference in pressure before and after the orifice, and the temperature and pressure compensation unit analyzes information on the detection of the gas -flow detector to determine whether the gas is currently being consumed, and, if the gas is being consumed, the first time interval is made shorter than a case of not being consumed, thereby the weighted value being automatically reflected.
[9] The apparatus as claimed in claim 1, wherein the pressure-measuring device includes a pipe member connected between the gas supply pipe and the gas meter and constituting part of the gas supply pipe; a body fixed to the pipe member and having a pressure pipe path formed inside thereof, one end of the pressure pipe path being fluid-communicated with the pipe member and the other end thereof being ended with a closed receiving cavity; a pressure sensor disposed inside of the receiving cavity of the body and generating an electrical signal corresponding to ambient pressure; an isolation means disposed at the intermediate of the pressure pipe path within the body, the isolation means allowing the gas pressure inside of the pipe member to be transmitted to the pressure sensor and preventing the gas from contacting directly the pressure sensor; and a pressure signal processing unit disposed outside of the body and electrically connected with output terminal of the pressure sensor, the pressure signal processing unit processing the output electrical signal to convert into a digital signal corresponding the gas pressure.
[10] The apparatus as claimed in claim 9, wherein the isolation means is at least one of at least one membrane disposed at a desired position in a way to cross the pipe member and a liquid material filled in a U-shaped or V-shaped pipe path to a desired height thereof.
[11] The apparatus as claimed in claim 9, wherein the temperature-measuring device includes a temperature sensor installed inside or outside of the pipe member and converting into an electrical signal corresponding to ambient temperature, and a temperature signal processing unit electrically connected with output terminal of the temperature sensor and processing the output electrical signal from the temperature sensor and converting into a digital signal corresponding to the ambient temperature.
[12] The apparatus as claimed in claim 1, wherein the pressure-measuring device includes a pipe member connected between the gas supply pipe and the gas meter and constituting part of the gas supply pipe; a body fixed to the pipe member and having a pressure pipe path formed inside thereof, one end of the pressure pipe path being fluid-communicated with the pipe member and the other end thereof being closed, part of the pressure pipe path being upright; a liquid material filled in the upright portion of the pressure pipe path to a desired level thereof, the column height of the liquid material changing in response to changes in the gas pressure inside of the pressure pipe path; a pressure sensor generating an electrical signal corresponding to the magnitude of gas pressure, the pressure sensor including a permanent magnet rested on a float floating in the liquid material and a magnetic field sensor disposed outside of the body to output an electrical signal corresponding to the intensity of magnetic field formed by the permanent magnet, the magnetic field sensor being placed approximately at the intermediate of the range of level change of the liquid material corresponding to an expected range of pressure fluctuation inside the pipe member; and a pressure signal processing unit converting the output electrical signal from the pressure sensor into a digital signal corresponding to the gas pressure.
[13] The apparatus as claimed in claim 4, wherein the temperature and pressure compensation unit includes a central processing unit performing computations required for calculation of the temperature and pressure compensation coefficient and the temperature and pressure compensated gas consumption using the compensation coefficient, a memory connected to the central processing unit to provide a storage space for data related to the computation, and a time-measuring unit connected to the central processing unit to count current time and provide information on the current time to the central processing unit.
[14] The apparatus as claimed in claim 13, wherein the temperature and pressure compensation unit further includes a display unit connected to the central processing unit to display information acquired or calculated by the central processing unit.
[15] An apparatus for compensating for a gas-volume error caused by temperature and pressure difference in a volumetric gas meter having automatic-reading function, the apparatus comprising: an automatic reading unit for automatically converting into a digital read value an indication value indicated by a number wheel or a scale plate of a volumetric gas meter; a temperature-measuring device for measuring gas-temperature inside the gas meter or inside a gas pipe near the gas meter and converting the measured temperature value into an electrical signal corresponding thereto; a pressure-measuring device for measuring gas-pressure inside the gas meter or the gas pipe and converting the measured pressure value into an electrical signal corresponding thereto; and a temperature and pressure compensation unit for receiving the electrical signals from the temperature-measuring device and the pressure-measuring device at first time intervals or when consumed amount of the gas reaches a certain predetermined value and then acquiring instantaneous gas temperature and pressure, calculating at least one of an instantaneous temperature and pressure compensation coefficient K , a daily temperature and pressure compensation coefficient and a monthly temperature and pressure compensation coefficient by using the instantaneous gas temperature and pressure, and receiving a daily or monthly read value from the automatic reading unit and calculating a compensated daily or monthly gas consumption by multiplying the daily or monthly read value by the daily temperature and pressure compensation coefficient or by multiplying the monthly read value by the monthly temperature and pressure compensation coefficient, thereby compensating for a gas-volume error that may be involved in the read value of the gas meter due to differences between the instantaneous temperature and pressure and a reference temperature and pressure at a reference position of gas-supplying.
[16] The apparatus as claimed in claim 15, wherein the instantaneous temperature and pressure compensation coefficient K is computed according to following equation in which P and T denote the instantaneous temperature and pressure values respectively, the daily temperature and pressure compensation coefficient is determined by averaging the entire instantaneous temperature and pressure coefficients computed during the day, and the monthly temperature and pressure compensation coefficient is determined by averaging the entire instantaneous temperature and pressure compensation coefficients or the entire daily temperature and pressure coefficient computed during the month.
Px 273.15
V 1013 x073.15 + D
[17] The apparatus as claimed in claim 15, wherein the temperature and pressure compensation unit considers a weighted value according to whether or not gas is consumed or the amount of consumed gas when temperature and pressure are measured or during the measuring-time interval, when calculating the daily temperature and pressure compensation coefficient or the monthly temperature and pressure compensation coefficient considers.
[18] The apparatus as claimed in anyone of claims 15 to 17, wherein the automatic reading unit includes: one or more light-emitting device radiating light towards rotation area of a particular number wheel or rotation needle corresponding to lower than a read-effective number place of the gas meter; one or more light- receiving device receiving light reflected from the rotation area and converting into a corresponding electrical signal, and a rotation number counter unit for counting rotation numbers of the particular number wheel or rotation needle in such a way to analyze changing behavior with time of the electrical signal provided by the light-receiving device and determine whether or not the number wheel or rotation needle has finished one rotation.
[19] The apparatus as claimed anyone of claims 15 to 17, wherein the automatic reading unit includes: a magnet installed in a particular number wheel or rotation needle corresponding to lower than a read-effective number place of the gas meter, a magnetic sensor disposed in a specific position on rotation path of the magnet to output electrical signals of different levels when the magnet approach es within a predetermine distance and moves away from the predetermined distance, and a rotation number counter unit for counting rotation numbers of the particular number wheel or rotation needle in such a way to analyze changing behavior with time of the electrical signal provided by the magnetic sensor and determine whether or not the number wheel or rotation needle has finished one rotation.
[20] The apparatus as claimed in anyone of claims 15 to 17, wherein the automatic reading unit includes: a sound maker generating a specific sound every time when a particular number wheel or rotation needle corresponding to lower than a read-effective number place of the gas meter finishes one rotation thereof; and a rotation number counter means for counting rotation numbers of the particular number wheel or rotation needle in such a way to detect the sound generated by the sound maker and determine whether or not the number wheel or rotation needle has finished one rotation.
[21] The apparatus as claimed in anyone of claims 15 to 17, further comprising a communications unit for receiving information on the compensated gas consumption from the temperature and pressure compensation unit and transmitting the information to a desired receiver, together with information on the consumer where the gas meter is installed.
[22] The apparatus as claimed in claim 15, wherein the temperature-measuring device includes a pipe member connected between the gas supply pipe and the gas meter and constituting part of the gas supply pipe; a body fixed to the pipe member and having a pressure pipe path formed inside thereof, one end of the pressure pipe path being fluid-communicated with the pipe member and the other end thereof being ended with a closed receiving cavity; a pressure sensor disposed inside of the receiving cavity of the body and generating an electrical signal corresponding to ambient pressure; an isolation means disposed at the intermediate of the pressure pipe path within the body, the isolation means allowing the gas pressure inside of the pipe member to be transmitted to the pressure sensor and preventing the gas from contacting directly the pressure sensor; and a pressure signal processing unit disposed outside of the body and electrically connected with output terminal of the pressure sensor, the pressure signal processing unit processing the output electrical signal to convert into a digital signal corresponding the gas pressure.
[23] The apparatus as claimed in claim 22, wherein the isolation means is at least one of at least one membrane disposed at a desired position in a way to cross the pipe member and a liquid material filled in a U-shaped or V-shaped pipe path to a desired height thereof. [24] The apparatus as claimed in claim 22, wherein the temperature-measuring device includes a temperature sensor installed inside or outside of the pipe member and converting into an electrical signal corresponding to ambient temperature, and a temperature signal processing unit electrically connected with output terminal of the temperature sensor and processing the output electrical signal from the temperature sensor and converting into a digital signal corresponding to the ambient temperature.
[25] The apparatus as claimed in claim 15, wherein the pressure-measuring device includes a pipe member connected between the gas supply pipe and the gas meter and constituting part of the gas supply pipe; a body fixed to the pipe member and having a pressure pipe path formed inside thereof, one end of the pressure pipe path being fluid-communicated with the pipe member and the other end thereof being closed, part of the pressure pipe path being upright; a liquid material filled in the upright portion of the pressure pipe path to a desired level thereof, the column height of the liquid material changing in response to changes in the gas pressure inside of the pressure pipe path; a pressure sensor generating an electrical signal corresponding to the magnitude of gas pressure, the pressure sensor including a permanent magnet rested on a float floating in the liquid material and a magnetic field sensor disposed outside of the body to output an electrical signal corresponding to the intensity of magnetic field formed by the permanent magnet, the magnetic field sensor being placed approximately at the intermediate of the range of level change of the liquid material corresponding to an expected range of pressure fluctuation inside the pipe member; and a pressure signal processing unit converting the output electrical signal from the pressure sensor into a digital signal corresponding to the gas pressure. |
Description
AN APPARATUS FOR CORRECTING GAS-VOLUME ERROR
CAUSED BY TEMPERATURE-PRESSURE DIFFERENCE FOR
A VOLUME-MEASURING TYPE GAS METER HAVING AN
AUTOMATIC METER READING FUNCTION Technical Field
[1] The present invention relates to an automatic meter reading technology applied to gas meters, more specifically, to such technologies, in which gas-volume change due to differences in the pressure and temperature between a gas-supplying reference position and a volumetric gas meter can be compensated such that consumed amount of gas can be precisely and automatically measured when the volumetric gas meter is read. Background Art
[2] In general, a supply and charge system of household and industrial gases is determined, between wholesalers and retailers, based on the gas weight. Between the retailers and individual consumers, however, it is determined based on the gas volume. For example, in Korea, the gas transaction between each local gas company (retailer selling gas directly to consumers) and the Korea Gas Corporation (wholesaler supplying gas to the retailers) is made in the state of liquefied gas and the gas charge is calculated based on the gas weight. Conversely, when each local gas company sells gas to consumers, the gas is supplied in gaseous state through a gas pipe. Thus, the amount of supplied gas is measured in the unit of volume. Accordingly, general gas consumers such as houses, stores and factories have volumetric gas meters (hereinafter, referred to as a "gas meter"), which measure the consumed gas based on the gas volume. Here, it has been found out that there is a significant difference between the gas amount purchased by each local gas company (retailer) from the Korean Gas Corporation (wholesaler) and the gas amount sold to the entire consumers by the retailer. According to the inventor's analysis, the reasons therefor are that there is a difference between the reference temperature and pressure at a gas-supplying position established by the gas company and the real temperature and pressure at the gas meter of each consumer, leading to a difference in the gas volume in-between. This difference is referred to as a "temperature and pressure error" throughout the description and claims of this application. Inherently, gas volume per unit weight varies with the temperature and pressure thereof. The gas supplier (retailer) supplies gas through a gas pipe to each individual consumer from the gas-supplying position, where a pressure regulator is
installed, with a reference temperature and pressure (e.g., O 0 C and 1 ATM). Here, the gas temperature and pressure at the position of each consumer's gas meter is not always identical to the reference temperature and pressure. In this way, in case where the gas temperature and pressures at both positions are not identical, the gas volume, corresponding to a gas weight supplied from the gas-supplying position, comes to be different from the gas volume measured at each consumer's gas meter.
[3] More specifically, in case of Korea, the gas is supplied from the pressure regulator with a gauge pressure of about 20~25mbar, considering reduction in the gas pressure between the pressure regulator and each consumer's gas meter. During the course of transportation of gas to the consumers through a gas pipe, the gas density varies with ambient temperature and pressure, and thus the read value from the gas meters continue to change according to the seasons, day time and night time. In a volumetric gas meter, the volume-measuring container is formed of a membrane having flexibility, which causes fluctuations in the read value by the changes in the ambient temperature and pressure. As described above, the reference temperature and pressure at the pressure regulator of the local gas company is not the same as the ambient temperature and pressure at the consumer's gas meter when it is read, thereby causing difference and fluctuation in the consumed gas volumes measured from the gas meter. Because of this, there is a difficulty in charging a precise and consistent gas price between the gas supplier and the consumers. For instance, unreasonably consumers in hot areas or highlands may pay the same gas fees as those in cold areas or lowland, in spite where they consumes less calories (the calories are in proportion with the mole numbers of gas, not the gas volume.). It has been confirmed by an analysis that this unreasonable gas fees have been charged to consumers in real life.
[4] The inventor has found causes for the temperature and pressure error and filed a patent application for some solutions (refer to Korean Patent Application No. 10-2003-0053627 entitled "Remote reading apparatus of gas meters having temperature and pressure compensation function"). In the temperature and pressure compensator disclosed in the above application, each gas meter is equipped with one temperature-measuring device. For example, a temperature sensor is attached inside of the gas pipe or on the surface thereof, or attached to the inner side or surface of the gas meter or near the gas meter. With respect to pressure, however, a single pressure- measuring device is installed with respect to multiple gas meters installed in a unit area and measures the atmospheric pressure, not the gas pressure. Then, measured information on the atmospheric pressure is transmitted to and shared with multiple gas meters through a wireless network (for remote reading).
[5] In general, however, the temperature and pressure at a metering point of consumed gas, i.e., at a point where the gas meter is installed, is not the same, but different for the
respective consumers. In addition, the gas temperature and pressure at the individual consumer's gas meter are also different from the reference temperature and pressure at the gas-supplying position. Therefore, in order to minimize the temperature and pressure error, the best information is the instantaneous temperature and pressure values of gas passing through positions where each consumer's gas meter is installed. Further, in order to precisely compensate for the pressure difference or fluctuation, pressure values of gas itself is more useful, rather than the atmospheric pressure information.
[6] In the above conventional technologies, however, atmospheric pressure information, not the pressure value of gas itself, is used for compensating the pressure difference. Furthermore, the atmospheric pressure value is measured at a certain point within a unit area, not from each consumer's gas meter, and then the measured pressure value is applied to all the gas meters within the unit area, thereby resulting in insufficient compensation for the pressure differences. That is, precise compensation for the pressure difference requires information on the difference between the gas pressure at each consumer's gas meter and the reference pressure at the gas-supplying point. However, this information cannot be acquired through conventional technologies. In addition, according to the conventional technique, a pressure-measuring unit (a unit for measuring atmospheric pressure) and a temperature-measuring unit are installed at different places. Accordingly, these units must be separately made and installed.
[7] On the other hand, in order to compensate the above temperature and pressure error, read values of a gas meter (typically, in case of a membrane gas meter, number values indicated by number wheels or rotation needles) must be converted into digital values. Digitalization of the read values can be carried out using an AMR device. Well-known automatic reading techniques, which can be combined with the present invention, include an optical automatic reading, magnetic automatic reading, acoustic automatic reading, image-recognition automatic reading, and the like. In case of the optical automatic reading, an optical sensor is used for converting rotation number of the number wheels or the rotation needles into electrical signals and then counting as a digitalized value. In the magnetic automatic reading technique, a magnetic sensor is used for the same purposes. The acoustic reading technique generates a unique mechanical sound every time when a certain number wheel or rotation needle rotates and detects the sound to count the rotation number of the number wheel or rotation needle. In addition, the image-recognition automatic reading method takes a picture of the values indicated by the number wheels and these images are counted as a digital value using an optical character recognition technique. Disclosure of Invention
Technical Problem
[8] Accordingly, the present invention has been made in order to solve the above problems in the prior art. It is an object of the invention to provide an apparatus for compensating for temperature and pressure errors occurring in a volumetric gas meter due to difference between the temperature and pressure of the gas meter and a reference temperature and pressure of gas-supplying point, thereby precisely compensating for gas volume errors caused by the temperature and pressure errors.
[9] Another object of the invention is to provide an apparatus for compensating for the temperature and pressure error and having an automatic reading function, thereby providing a precise read value of the gas meter where the temperature and pressure error are automatically compensated.
Technical Solution
[10] In order to accomplish the above objects, according to one aspect of the invention, there is provided an apparatus for compensating for a gas-volume error caused by temperature and pressure difference in a volumetric gas meter, the apparatus comprising: a temperature-measuring device for measuring gas-temperature inside a volumetric gas meter or inside a gas pipe near the gas meter and converting the measured temperature value into an electrical signal corresponding thereto; a pressure- measuring device for measuring gas-pressure inside the gas meter or the gas pipe and converting the measured pressure value into an electrical signal corresponding thereto; and a temperature and pressure compensation unit for receiving the electrical signals from the temperature-measuring device and the pressure-measuring device to acquire instantaneous gas temperature and pressure and, using the instantaneous gas temperature and pressure, calculating at least one of an instantaneous temperature and pressure compensation coefficient K , a daily temperature and pressure compensation coefficient and a monthly temperature and pressure compensation coefficient, the electrical signals being received at first time intervals or when consumed amount of the gas reaches a certain pre-determined value, wherein the compensation coefficient is used for compensating for a gas volume error that may be involved in a read value of the gas meter due to differences between the instantaneous temperature and pressure and a reference temperature and pressure at a reference position of gas-supplying.
[11] In the apparatus, the daily temperature and pressure compensation coefficient is determined by averaging the entire instantaneous temperature and pressure coefficients computed during the day, and the monthly temperature and pressure compensation coefficient is determined by averaging the entire instantaneous temperature and pressure compensation coefficients or the entire daily temperature and pressure coefficient computed during the month. Also, the compensation of the daily temperature and
pressure compensation coefficient or the monthly temperature and pressure compensation coefficient considers a weighted value according to whether or not gas is consumed or the amount of consumed gas when temperature and pressure are measured or during the measuring-time interval. If the weighted value is applied on this wise, the gas-volume error due to temperature and pressure differences can be corrected very accurately.
[12] In the apparatus, the temperature and pressure compensation unit further receives digitized daily or monthly read value from an automatic reading unit automatically reading indication value of the gas meter, computes a compensated daily gas consumption by multiplying the daily read value by the daily temperature and pressure compensation coefficient of the day, and computes a compensated monthly consumption by accumulating the daily consumptions during the month or multiplying the monthly read value by the monthly temperature and pressure compensation coefficient of the month.
[13] There may be several ways for applying the weighted value. As one way of applying the weighted value, the temperature and pressure compensation unit analyzes variation-pattern with time in the temperature and pressure values being acquired from the temperature-measuring device and the pressure-measuring device respectively to determine whether or not the gas is currently being consumed, and, if the gas is being consumed, the first time interval is made shorter than a case of not being consumed, thereby the weighted value being automatically reflected.
[14] As a second way of applying the weighted value, the temperature and pressure compensation unit further includes a gas-flow detector, which detects whether or not a certain number wheel or rotation needle of the gas meter is being rotated and determine whether or not the gas is currently being consumed, and, using information on the detection of the gas-flow detector, the temperature and pressure unit determines a time period for completion of a certain number of rotations of the number wheel or rotation needle, which is then used as the first time interval, thereby the weighted value is being automatically reflected.
[15] As a third way of applying the weighted value, the temperature and pressure compensation unit further includes a gas-flow detector having an orifice installed inside the gas meter or the gas pipe and a differential pressure sensor detecting a difference in pressure before and after the orifice, and the temperature and pressure compensation unit analyzes information on the detection of the gas -flow detector to determine whether the gas is currently being consumed, and, if the gas is being consumed, the first time interval is made shorter than a case of not being consumed, thereby the weighted value being automatically reflected.
[16] According to a constitutional embodiment of the pressure-measuring device of the
apparatus, the pressure-measuring device includes a pipe member connected between the gas supply pipe and the gas meter and constituting part of the gas supply pipe; a body fixed to the pipe member and having a pressure pipe path formed inside thereof, one end of the pressure pipe path being fluid-communicated with the pipe member and the other end thereof being ended with a closed receiving cavity; a pressure sensor disposed inside of the receiving cavity of the body and generating an electrical signal corresponding to ambient pressure; an isolation means disposed at the intermediate of the pressure pipe path within the body, the isolation means allowing the gas pressure inside of the pipe member to be transmitted to the pressure sensor and preventing the gas from contacting directly the pressure sensor; and a pressure signal processing unit disposed outside of the body and electrically connected with output terminal of the pressure sensor, the pressure signal processing unit processing the output electrical signal to convert into a digital signal corresponding the gas pressure. In the pressure- measuring device, the isolation means is at least one of at least one membrane disposed at a desired position in a way to cross the pipe member and a liquid material filled in a U-shaped or V-shaped pipe path to a desired height thereof.
[17] According to a constitutional embodiment of the temperature-measuring device of the apparatus, the temperature-measuring device includes a temperature sensor installed inside or outside of the pipe member and converting into an electrical signal corresponding to ambient temperature, and a temperature signal processing unit electrically connected with output terminal of the temperature sensor and processing the output electrical signal from the temperature sensor and converting into a digital signal corresponding to the ambient temperature.
[18] According to another constitutional embodiment of pressure-measuring device of the apparatus, the pressure-measuring device includes a pipe member connected between the gas supply pipe and the gas meter and constituting part of the gas supply pipe; a body fixed to the pipe member and having a pressure pipe path formed inside thereof, one end of the pressure pipe path being fluid-communicated with the pipe member and the other end thereof being closed, part of the pressure pipe path being upright; a liquid material filled in the upright portion of the pressure pipe path to a desired level thereof, the column height of the liquid material changing in response to changes in the gas pressure inside of the pressure pipe path; a pressure sensor generating an electrical signal corresponding to the magnitude of gas pressure, the pressure sensor including a permanent magnet rested on a float floating in the liquid material and a magnetic field sensor disposed outside of the body to output an electrical signal corresponding to the intensity of magnetic field formed by the permanent magnet, the magnetic field sensor being placed approximately at the intermediate of the range of level change of the liquid material corresponding to an
expected range of pressure fluctuation inside the pipe member; and a pressure signal processing unit converting the output electrical signal from the pressure sensor into a digital signal corresponding to the gas pressure.
[19] In the apparatus, the temperature and pressure compensation unit includes a central processing unit performing computations required for calculation of the temperature and pressure compensation coefficient and the temperature and pressure compensated gas consumption using the compensation coefficient, a memory connected to the central processing unit to provide a storage space for data related to the computation, and a time-measuring unit connected to the central processing unit to count current time and provide information on the current time to the central processing unit.
[20] According to another aspect of the invention, there is provided an apparatus for compensating for a temperature and pressure error in a volumetric gas meter having automatic-reading function, the apparatus comprising: an automatic reading unit for automatically converting into a digital read value an indication value indicated by a number wheel or a scale plate of a volumetric gas meter; a temperature-measuring device for measuring gas-temperature inside the gas meter or inside a gas pipe near the gas meter and converting the measured temperature value into an electrical signal corresponding thereto; a pressure-measuring device for measuring gas-pressure inside the gas meter or the gas pipe and converting the measured pressure value into an electrical signal corresponding thereto; and a temperature and pressure compensation unit for receiving the electrical signals from the temperature-measuring device and the pressure-measuring device at first time intervals or when consumed amount of the gas reaches a certain pre-determined value and then acquiring instantaneous gas temperature and pressure, calculating at least one of an instantaneous temperature and pressure compensation coefficient K , a daily temperature and pressure compensation coefficient and a monthly temperature and pressure compensation coefficient by using the instantaneous gas temperature and pressure, and receiving a daily or monthly read value from the automatic reading unit and calculating a compensated daily or monthly gas consumption by multiplying the daily or monthly read value by the daily temperature and pressure compensation coefficient or by multiplying the monthly read value by the monthly temperature and pressure compensation coefficient, thereby compensating for an error that may be involved in the read value of the gas meter due to differences between the instantaneous temperature and pressure and a reference temperature and pressure at a reference position of gas-supplying.
[21] The automatic reading unit can be constituted by using a photo sensing method with a photo sensor. The automatic reading unit using the photo sensing method includes: one or more light-emitting device radiating light towards rotation area of a particular number wheel or rotation needle corresponding to lower than a read-effective number
place of the gas meter; one or more light-receiving device receiving light reflected from the rotation area and converting into a corresponding electrical signal, and a rotation number counter unit for counting rotation numbers of the particular number wheel or rotation needle in such a way to analyze changing behavior with time of the electrical signal provided by the light-receiving device and determine whether or not the number wheel or rotation needle has finished one rotation.
[22] The automatic reading unit may be constituted by using a magnetic sensing method with a magnetic sensor. The automatic reading unit using the magnetic sending method includes: a magnet installed in a particular number wheel or rotation needle corresponding to lower than a read-effective number place of the gas meter, a magnetic sensor disposed in a specific position on rotation path of the magnet to output electrical signals of different levels when the magnet approaches within a predetermine distance and moves away from the predetermined distance, and a rotation number counter unit for counting rotation numbers of the particular number wheel or rotation needle in such a way to analyze changing behavior with time of the electrical signal provided by the magnetic sensor and determine whether or not the number wheel or rotation needle has finished one rotation.
[23] The automatic reading unit may be constituted by using a sound sensing method with a sound maker and a sound sensor. The automatic reading unit using the sound maker and a sound sensor includes: a sound maker generating a specific sound every time when a particular number wheel or rotation needle corresponding to lower than a read-effective number place of the gas meter finishes one rotation thereof; and a rotation number counter means for counting rotation numbers of the particular number wheel or rotation needle in such a way to detect the sound generated by the sound maker and determine whether or not the number wheel or rotation needle has finished one rotation.
Advantageous Effects
[24] According to the apparatus of the invention, errors in the gas sales due to temperature and pressure errors can be minimized to thereby provide appropriate and reasonable charge for consumed gas. In particular, the gas temperature and pressure are measured at nearest position to the gas meter to enable to achieve precise compensation for the temperature and pressure errors. The temperature and pressure compensation considers a weighted value according to whether the gas is currently being consumed, or the amount of consumed gas, leading to more precise compensation. Therefore, users 'reliability on gas bills can be improved. Brief Description of the Drawings
[25] Further objects and advantages of the invention can be more fully understood from
the following detailed description taken in conjunction with the accompanying drawings in which:
[26] Fig. 1 is a block diagram illustrating an automatic reading apparatus having a temperature and pressure compensation unit;
[27] Figs. 2 and 3 illustrate an automatic reading apparatus having a function of compensating for temperature and pressure errors, along with optical automatic reading function, according to an embodiment of the invention;
[28] Fig. 4 is a sectional view taken along the line B-B in Fig. 3 and showing the automatic reading unit adopting an optical sensing technique according to an embodiment of the invention;
[29] Fig. 5 is a sectional view taken along the line B-B in Fig. 3 and showing the automatic reading unit adopting an acoustic sensing technique according to an embodiment of the invention;
[30] Figs. 6 to 9 are sectional views taken along the line A-A in Fig. 3 and showing various embodiments of the temperature and pressure devices according to the invention; and
[31] Fig. 10 explains gas-flow detection using a differential pressure sensor.
Mode for the Invention
[32] Exemplary embodiments of the present invention will be hereafter described in detail with reference to the accompanying drawings. Fig. 1 is a block diagram illustrating an automatic reading apparatus 100 having a temperature and pressure compensation unit. The automatic reading apparatus 100 includes, in general, an automatic reading unit 60 automatically reading indication values of a gas meter 4, a temperature and pressure compensation unit 10 for compensating temperature and pressure errors involved in the automatic read values and calculating a compensated gas consumption, a display unit 70 connected to a central processing unit 32 inside of the temperature and pressure compensation unit 10 and for displaying various information acquired and calculated by the central processing unit 32, a user operation unit 80 for a user to input various instruction required for automatic reading and temperature and pressure compensation, a communications unit 90 for receiving information on the compensated gas consumption calculated by the temperature and pressure compensation unit 30 and transmitting the information to a desired receiver along with information on a consumer associated with the gas meter, and the like.
[33] The above automatic reading apparatus 100 is installed at each gas consumer. A gas supply company divides its own gas-supplying region into several unit areas and installs a local wireless communications relay 92 for every unit area. The local wireless communication relays 92 installed in each unit area are connected to a computer 96 of
the gas supply company (gas supplier) via a wired communications network or wireless communications network (e.g., data communications using a mobile phone communications network) or the like. For example, each unit area includes tens to thousands of household gas consumers. The automatic reading apparatus 100 installed for each consumer transmits to the local wireless communications relay 92 the consumed gas amount compensated for the temperature and pressure errors, which is finally transmitted to the computer 96 of the gas supply company.
[34] The temperature and pressure compensation unit 10 includes a temperature- measuring device 20 and a pressure-measuring device 25 for measuring the temperature and pressure of gas passing through the volumetric gas meter 4, and a temperature and pressure compensation unit 30 for calculating a temperature and pressure compensation coefficient using the measure temperature and pressure values. Preferably, the temperature and pressure compensation unit 10 includes a time- measuring device 40 for counting current-time and providing the time information to the temperature and pressure compensation unit 30. The temperature-measuring device 20 measures gas -temperature of the gas meter 4 or inside a gas pipe 2 near the gas meter and converts it into an electrical signal. Here, the gas meter 4 includes a volumetric gas meter that measures consumed gas in a unit of volume. The pressure- measuring device 25 measures gas-pressure inside the gas meter 4 or the gas pipe 2 and converts the measure pressure value into an electrical signal corresponding to it.
[35] The temperature and pressure compensation unit 30 acquires information on instantaneous temperature and pressure from the temperature-measuring device 20 and the pressure-measuring device 25 and, using the information, calculates a temperature and pressure compensation coefficient, which can be used to compensate for temperature and pressure errors that may be involved in automatic read values. This temperature and pressure compensation coefficient is used to calculate a compensated amount of consumed gas. For the purpose of this computation processing, the temperature and pressure compensation unit 30 includes at least a central processing unit (CPU) 32 and a memory 34 connected thereto. The CPU 32 performs computations required for determining a temperature and pressure compensation coefficient and a compensated gas consumption using the coefficient. The memory 34 provides a data storage space required for these computations and for storing data. Specifically, the temperature and pressure compensation unit 30 regularly or non- regularly receives electrical signals corresponding to the temperature and pressure measured from the temperature-measuring device 20 and the pressure-measuring device 25. The electrical signals are used to acquire instantaneous temperature and pressure of the gas, which are stored in the memory 34. In addition, these instantaneous temperature and pressure values are used to calculate at least one of an in-
stantaneous temperature and pressure compensation coefficient K , a daily temperature and pressure compensation coefficient and a monthly temperature and pressure compensation coefficient, which are stored in the memory 34, along with date and month information. The computed temperature and pressure compensation coefficients are reflected on read values of the gas meter to compensate for the temperature and pressure errors, which may be included in the read values of gas meter due to differences between the instantaneous temperature and pressure values and the reference temperature and pressure values applied when the gas is supplied.
[36] The instantaneous temperature and pressure compensation coefficient K is calculated through the following equation (1). In the equation (1), P and T denote instantaneous pressure and temperature values respectively.
[37]
Px 273.15 I? " l013 x(273.15 + D (i)
[38] The equation (1) is determined using the Boyle-Charles's law. More specifically, gas volume is expressed by the following equation (2) according to temperature and pressure.
[39] P-V = Z-n-R-T (2)
[40] Here, P and V denote absolute pressure and volume of gas respectively. Z denotes compressibility factor being affected by pressure. T and N denote mole number of gas and absolute temperature of gas ( 0 K). Pressure and temperature of the gas passing through a gas meter 4 are relatively low, i.e., about 1013~1300hPa in absolute pressure and near room temperature. Thus, Z=I make no significant different. Using the equation (2), gas volume at an arbitrary temperature T and pressure P can be expressed by the following equation (3), in which T and P are reference temperature and pressure at the gas-supplying location of a gas-supply company (in case of Korea, usually 0°C(273°K) and 1 ATM (1013hPa)), and V is gas volume at the T and P .
[41]
T T 0 (3)
[42] The equation (3) is well-known as Boyle-Charles's Law clearly defining gas behavior. The gas volume V at the reference temperature T and pressure P can be derived from the equation (3), using the gas volume V measured at the arbitrary temperature T and pressure P, as expressed by the equation (4).
[43]
T P n (4)
[44] The consumed gas amount V at the arbitrary temperature and pressure can be measured from the gas meter 4. Thus, the consumed gas amount V at the reference temperature and pressure (e.g., at T = O 0 C = 273°K and P =1013hPa) can be calculated by measuring the instantaneous gas temperature T and pressure P at the gas meter 4 or inside a gas pipe 2 near the gas meter and using the following equation (5). In the right side of the equation (5), the remainder except for V is the instantaneous temperature and pressure compensation coefficient K expressed by the equation (1).
[45]
273 P
V 0 = - Y.. V 7 1013 (5)
[46] Hereinafter, for the convenience of explanation of the invention, the temperature and pressure errors may be referred to as a "T&P error", and the temperature and pressure compensation coefficient may be referred to as a "T&P compensation coefficient". The instantaneous T&P compensation coefficient is computed in certain intervals of time. Thus, one method for compensate for T&P error using the instantaneous T&P compensation coefficients K may be carried out through multiplication of an instantaneous T&P compensation coefficient at a certain particular time point by the read value of gas amount consumed during the time interval. As an alternative, a daily T&P compensation coefficient is computed by averaging the entire instantaneous T&P compensation coefficients being calculated during a day. The daily T&P compensation coefficient is multiplied by the read value of gas amount consumed during the day, thereby calculating a compensated daily amount of consumed gas (referred to as a "compensated daily consumption"). The compensated daily amounts of consumed gas are accumulated monthly to determine a compensated monthly amount of consumed gas (referred to as a "compensated monthly consumption"). Otherwise, a monthly T&P compensation coefficient is determined by averaging the entire instantaneous T&P compensation coefficients or the entire daily T&P compensation coefficients being computed during one month. Then, a compensated monthly consumption can be determined by multiplying the monthly T&P compensation coefficient by the read value of consumed gas for the month. Here, the automatic read value for consumed gas to be compensated can be acquired from an automatic reading unit 60. The automatic reading unit 60 automatically reads indication value of the gas meter 4 and converts it into a digitized signal corresponding
to the consumed amount of gas. The digitized signal is provided to the temperature and pressure compensation unit 30.
[47] On the other hand, in order to more precisely compensate for T&P errors using the above T&P compensation coefficients, it is preferable to check whether gas is consumed or not at the time of measuring the temperature and pressure or during the measuring time interval. It is also preferable to apply a weighted value depending upon the amount of gas consumption. As one method of applying the weighted value, the time intervals of measuring the temperatures and pressures, in other words, the time intervals of calculating instantaneous T&P compensation coefficients are to be related with and thus variably adjusted according to whether or not gas is consumed or the amount of consumed gas. In one embodiment for the application of a weighted value, the temperature and pressure compensation unit 30 analyzes the fluctuation pattern with time for temperature values being acquired from the temperature-measuring device 20 and for pressure values being acquired from the pressure-measuring device 25, to thereby determine whether gas is currently being consumed. In case where the gas is currently being consumed, the T&P compensation coefficient is calculated at short time intervals, relative to the case where the gas is not currently being consumed. Thus, in order to obtain daily or monthly T&P compensation coefficients, these instantaneous T&P compensation coefficients calculated as above can be simply arithmetic-averaged to thereby automatically reflect a weighted value according to whether or not gas is being consumed or the consumed amount of gas.
[48] In an alternative embodiment, the temperature and pressure compensation unit 10 further includes a gas-flow detector 50, which detects whether or not a certain number wheel or rotation needle is being rotated to thereby determine whether the gas is currently being consumed. Then, the temperature and pressure compensation unit 30 uses information on the detection provided by the gas-flow detector 50 to be able to obtain a time-interval when the certain number wheel or rotation needle completes a certain number of rotations, and computes instantaneous T&P compensation coefficients according to the above time-intervals. The computed instantaneous T&P compensation coefficients can be simply arithmetic-averaged to calculate a daily or monthly T&P compensation coefficient, on which a weighted value according to the consumed amount of gas is automatically reflected.
[49] As another alternative, the temperature and pressure compensator 10 includes a gas- flow detector 50 having an orifice 252 installed inside of the gas meter 4 or gas pipe 2 and a differential pressure sensor 250 for detecting a difference in the pressures before and after the orifice 252 and generating an electrical signal corresponding to the pressure difference (the differential pressure sensor is conceptually presented in Fig. 10). The temperature and pressure compensation unit 30 analyzes information on the
detection of the gas-flow detector 50 to determine whether or not the gas is currently being consumed. If being consumed, the instantaneous T&P compensation coefficients are acquired at shorter time intervals, relative to the case of not being consumed, such that a weighted value can be automatically considered.
[50] Other various ways can be used for determining whether the gas is currently being consumed and applying a weighted value. In the first example, one pressure sensor is used to detect variations in the pressure inside the gas pipe 2 to determine whether the gas is flowing or not. This method employs the principle that flowing-fluid causes dynamic pressure and thus static pressure decreases. In order to further decrease the static pressure, preferably the gas pipe has a narrower diameter at the position of measuring the pressure. The pressure-measuring device 25 may be used, without installing a separate pressure sensor. The second example uses a temperature sensor, utilizing the fact that the temperature of gas stagnant inside the gas meter 4 or the gas pipe 2 when the gas is not being consumed is different from the temperature of gas flowing up from the buried underground pipe. This method may use the temperature- measuring device 20 without adopting a separate temperature sensor. The third method uses an inhibitor plate (not shown) installed inside the gas pipe 2. The inhibitor plate is designed such that its oriented angle varies with the flow rate of a gas and the orientation angle thereof is measured. The fourth method detects whether a certain number wheel or rotation needle is being rotated to thereby determine whether the gas is currently consumed or not, in case of gas meters 4 where indication values are indicated by the numbers of a number wheel train or by a combination of scale values pointed by multiple rotation needles. A light emitter and a light receiver are installed so as to be oriented towards a certain particular number wheel or rotation needle. When the number wheel or rotation needle rotates, the intensity of reflected light varies according to the differences in the shape of the numbers. This intensity can be sensed to determine whether the gas is currently being consumed or not. Besides this optical sensing method, a magnetic sensing technique may be used.
[51] On the other hand, as described above, the automatic reading apparatus 100, in addition to the temperature and pressure compensation apparatus 10, includes an automatic reading unit 60 for automatically reading indication-value of the gas meter 4 and converting the read value into a digitized read value. This automatic reading unit 60 has a signal processing function such as to sense indication- value of the gas meter 4 and converts it into a digitized read value (non-compensated value for temperature and pressure variations), and the like. Any types of automatic reading techniques can be adopted as long as they have the above functions. The sensing of indication- value can be carried out, using any one of well-known methods, such as an optical automatic reading technique using an optical sensor, magnetic automatic reading using a
magnetic sensor, acoustic automatic reading using a unique mechanical sound of materials, and image-recognition automatic reading taking a picture of the number values indicated and recognizing these images as a number. For example, in case of adopting the optical or magnetic type automatic reading technique, it requires a sensing device for detecting rotations of a particular number wheel or rotation needle, an A/D converter for converting an analog signal from the sensing device into a digital value, a computation unit for acquiring the digitized value and analyzing the variation pattern thereof with time to thereby count the rotation numbers of the particular number wheel or rotation needle, and the like. In case where the CPU 32 of the temperature and pressure compensation unit 30 performs functions of the computation unit, the automatic reading unit 60 only has to include a sensing device and an A/D converter for converting an output signal from the sensing device into a digital signal.
[52] Figs. 2 and 3 illustrate an automatic reading apparatus having a function of compensating for T&P errors, along with optical automatic reading function, according to an embodiment of the invention. Fig. 4 is a sectional view taken along the line B-B in Fig. 3. The illustrated gas meter 4 is a membrane type gas meter, which measures consumed gas as a unit of volume. The amount of consumed gas is indicated by number values on a number wheel train 110. The temperature-measuring device 20 and the pressure-measuring device 25 are assembled integrally with a gas pipe 2. The gas pipe 2 is coupled and sealed between the existing gas pipe 8 and the gas meter 4 using couplings 6a and 6b.
[53] A photo-sensing unit 130 is provided for sensing rotation of a particular number wheel in the number wheel train 110 of the gas meter 4. The photo-sensing unit 130 includes one or more light-emitting devices 132 and one or more light-receiving devices 134. The light-emitting device 132 radiates light towards a specific area on rotation path of a particular number wheel or rotation needle, which corresponds to lower than a read-effective number place. The light-receiving device 134 receives light reflected from the specific area and converts it into a corresponding electrical signal. The output signal of the light-receiving device 134 is A/D-con verted through an A/D converter of the automatic reading unit 60, and then provided to the CPU 32. According to the embodiments illustrated in Figs. 2 to 4, the light-emitting device 132 and the light-receiving device 134 are mounted on a block body 135 having a rectangular shape for example. Formed in the front portion of the block body 135 are at least two grooves 138a and 138b having openings formed towards the specific area on rotation path of the particular number wheel 112. The light-emitting device 132 and the light-receiving device 134 are installed in the grooves 138a and 138b respectively. The block body 135 is installed in a housing 140 in such a way that it can be fitted into a holder 148 of the inner wall of an installation space 142. At this state, the housing 140
covers the meter indicator 114 and simultaneously a latch 146 is latched with a flange 116. The portion in the housing corresponding to the meter indicator 114 is formed of a transparent window 144 to be able to see the indication values. When the housing 140 is mounted in the gas meter 4, the light-emitting device 132 and the light-receiving device 134 of the photo-sensing unit 130 are directed towards a specific area on rotation path of a particular number wheel 112, which is corresponding to lower than a read-effective number place, among the number wheels of the number wheel train 110. In case of a typical gas meter, white numbers of 0 to 9 are expressed in the black outer surface of the particular number wheel 112. Since different numbers provide different reflection patterns of light, which has been radiated by the light-emitting device 132, the output signal pattern from the light-receiving device 134 during one rotation of the particular number wheel 112 changes correspondingly. Thus, the output signal from the light-receiving device 134 is converted into digital signals and then provided to the CPU 32. The CPU 32 analyzes behavior of level changes in the output signal to determine whether the particular number wheel has finished one rotation. Alternatively, the particular number wheel 112 is provided at its outer surface with a light reflector 120 having good reflection efficiency and it is determined whether or not the light reflector has passed under the light-receiving device 134, to thereby enable to recognize one rotation of the number wheel 112. That is, the particular number wheel 112 has a difference in the light reflection efficiencies between the light reflector 120 and the remaining portion. During rotation of the particular number wheel 112, when the light-emitting device 132 radiates light towards the particular number wheel 112, the intensity of reflected light by the light reflector 120 is noticeably stronger than the intensity by the other remaining portion. Thus, the output signal from the light- receiving device 134, which corresponds to the intensity of the reflected light, is A/ D-converted and provided to the CPU 32. The CPU 32 analyzes behavior of level change with time in the output signal to count the rotation numbers of the particular number wheel 112, for example, by determining whether the level change matches with the pattern corresponding to one rotation of the particular number wheel 112. Details on the above techniques may refer to Korean Patent Application Publication No. 10-2005-0015110 entitled "Remote reading apparatus for gas meter having temperature and pressure compensation function", and PCT international publication no. WO 2005/064563 Al entitled "Automatic meter reading method and apparatus using pattern analysis for levels of output signals from multiple photoelectric sensors". The entire teachings of the above applications are hereby incorporated by reference as though fully set forth herein. [54] Fig. 5 shows an example of the automatic reading unit 60 adopting an acoustic sensing technique. As shown in Fig. 5, the acoustic automatic reading unit includes a
sound maker 160a, 160b fixed to a particular number wheel 112, which corresponds to lower than a read-effective number place, and a latch 162 hitting the sound maker while the particular number wheel rotates. The sound maker and the latch are configured such that the sound maker is elastically bent and restored by the latch and at the same time the sound maker produces a sound by means of its elastic vibration. The sound maker 160a, 160b and the latch 162 define a sound generating unit. The automatic reading unit includes a microphone 165a, 165b for converting the sound generated by the sound maker 160a, 160b into an electrical signal, and an A/D converter (not shown) for converting the analog electrical signal from the microphone into a digital signal and providing it to the CPU 32.
[55] As another example, an automatic reading unit 60 of magnetic type includes a magnet (not shown) disposed on a particular number wheel 112 or rotation needle corresponding to lower than a read-effective number place, similar to the sound maker 160a of Fig. 5. A magnetic sensor (not shown) is disposed in a specific position on rotation path of the magnet to output electrical signals of different levels when the magnet moves towards and far away from the magnetic sensor within a predetermined distance, similar to the microphone 165a, 165b of Fig. 5. The magnetic sensor generates an analog electrical signal, which is then converted into a digital signal and provided to the CPU 32 by means of an A/D converter (not shown).
[56] Regardless of adopting any type of the above modes, in order to determine whether or not the particular number wheel 112 or rotation needle has completed one rotation, it is required a process for analyzing changing behavior of the digital signal with time. For this purpose, a separate signal processing unit may be adopted, but it is preferable that the CPU 32 of the temperature and pressure compensation unit 30 takes the role.
[57] On the other hand, Figs. 6 to 9 are sectional views taken along the line A-A in Fig.
3 and showing a temperature and pressure compensation apparatus 10 according to embodiments of the invention. The temperature and pressure compensation apparatus 10 includes a temperature-measuring device 20 and a pressure-measuring device 25. In order to measure pressure, the temperature and pressure-measuring devices illustrated in Fig. 6 includes a pipe member 2 connected between a gas supply pipe 6a and a gas meter 4 and constituting part of the gas supply pipe. A body 240, 244, 248 is fixed to the pipe member 2 by means of screws 246a and 246b. Formed inside of the body is a pressure pipe path 242, one end of which is fluid-communicated with the pipe member and the other end of which is connected to a sealed receiving cavity. A pressure sensor 220 is disposed inside of the receiving cavity of the body 240 and generates an electrical signal corresponding to the magnitude of ambient pressure. An isolation means such as a membrane 224 is disposed intermediate of the pressure pipe path 242 inside the body 240 in a way to transverse the pressure pipe path 242. The membrane
224 allows the gas pressure to be transmitted to the pressure sensor 220, but shields the gas from contacting directly the pressure sensor 220. A pressure signal processing unit 230 is disposed outside of the body 240 and connected with the output terminal of the pressure sensor 220 through an electric wire 222. The pressure signal processing unit 230 processes the output electrical signal from the pressure sensor 220 and converts it into a digital signal corresponding to the gas pressure. As long as it can measure pressure and convert the measured pressure value into an electrical signal in the form of a digital value, the pressure sensor may employs various types such as a capacitor pressure sensor, a strain gauge pressure sensor, a semiconductor pressure sensor, a piezoelectric pressure sensor, and the like. Furthermore, for temperature measurement, the temperature and pressure-measuring devices include a temperature sensor 210 installed inside or outside of the pipe member 2. The temperature sensor 210 measures ambient temperature and converts into an electrical signal corresponding to it. A temperature signal processing unit 230 is connected to the output terminal of the temperature sensor 210 through an electric wire 212. The temperature signal processing unit 230 processes the output electrical signal from the temperature sensor 210 and converts into a digital signal corresponding to the ambient temperature. The figures illustrate the pressure signal processing unit 230 and the temperature signal processing unit 230 as being implemented on a same printed circuit board. An O-ring 250, 252 is mounted around the membrane 224 and the pressure sensor 220 to thereby prevent the gas from leaking to the outside. The gap occurred for installing the pressure sensor 220 is finished with a sealant 228. As long as it can measure ambient temperature and convert into an output electrical signal, the temperature sensor may employ various types such as a metallic thermistor such as thermocouples or platinum, a non-metallic thermistor, a semiconductor temperature sensor, a radiation temperature sensor, a metal-core type temperature sensor, or the like.
[58] Figs. 7 and 8 shows a temperature and pressure measuring unit further modified to prevent direct contact between the pressure sensor 220 and the gas inside the pipe member 2. In case of Fig. 7, two membranes 224a and 224b sealed with O-rings 250a and 250b are dispose in a pressure pipe path 242- 1 formed inside the body 240. A U- shaped pressure tube is formed between the two membranes 224a and 224b and a liquid material 226 is filled inside the U-shaped pressure tube. In order to fill the liquid material 225, the body 240 is provided at its side with a groove formed to be connected with the U-shaped pressure tube. After the liquid material is injected through the groove, the groove is closed with a plug 244 sealed with an O-ring 254. Fig. 8 illustrates a pressure pipe path 242-2 having a V-shape. In Figs. 7 and 8, either one of the membranes 224a and 224b or the liquid material 226 may be adopted.
[59] Fig. 9 shows a temperature and pressure measuring unit having a different mode of
temperature-measuring device. Specifically, a pressure pipe path 242-3 is formed inside of the body 240, 244, 248. Part of the pressure pipe path 242-3 is formed in vertical direction. One end of the pressure pipe path 242-3 is fluid-communicated with the pipe member 2 and the other end thereof is closed. The vertical section of the pressure pipe path is filled with a liquid material 254 up to a desired level. A permanent magnet 249 is rested on a float, which is to be floated in the liquid material 254. The liquid material 254 changes the height of liquid column, in response to change in the pressure inside of the pipe member 2. In addition, a magnetic field sensor 252 is disposed outside of the body 240 so as to be placed approximately at the intermediate of the level-fluctuation range of the liquid material 254, which corresponds to the expected range of pressure fluctuation inside of the pipe member 2. The magnetic field sensor 252 outputs an electrical signal corresponding to the intensity of magnetic field of the permanent magnet 249. The electrical signal output from the magnetic field sensor 252 is transmitted to a pressure signal processing unit 230 and converted into a digital signal corresponding to the gas pressure. The liquid material 254 is sealed with a plug 244 and an O-ring 254. [60] Hereafter, T&P compensated gas consumption is calculated according to the following procedures. First, a basic mode will be explained. The CPU 32 acquires an instantaneous temperature T and an instantaneous pressure P from the temperature- measuring device 20 and the pressure-measuring device 25, for example every 10 minutes from 0:00AM in real time. A T&P compensation coefficient K is calculated using the above equation (1). Tnstant_T/P/K (instantaneous T&P compensation coefficient )' is stored in the memory 34. At 24:00PM, the CPU 32 averages Tnstant_T/P/K of 24 hours to calculate a 'daily_T/P/K ', which is stored in the
TP TP memory 34 together with the date information. In addition, a 'monthly_T/P/K up to
TP that date is calculated and stored. Everyday, a 'monthly_T/P/K up to that date is
TP stored. Then, at the end of the month, a 'monthly_T/P/K up to that date is copied and
TP stored as a 'monthly_T/P/K of that month separately in the memory 34. However, the
TP
'monthly_T/P/K for each date is updated everyday. Here, the 'monthly_T/P/K is an average from the current time (24:00PM) to the last one month. At this time, the days of that month is calculated according to the month to which the current date belongs. That is, in case of the average to 24:00PM on February 3, the days of the month is 28 days and thus 'daily_T/P/K 's for 28 days from January 7 to February 3 are arithmetic- averaged to calculate the 'monthly_T/P/K for February 3. The above procedures are repeated. In case where a user inputs an instruction through the operation unit 80, the following special modes are performed according to the user's instruction. [61] In a special mode, whether or not the gas is currently being consumed is confirmed.
In this mode, first, the CPU 32 operates the gas flow detector 50 to confirm whether
the gas is being consumed, for example every 30 seconds from 0:00AM in real time. In case where the output signal value from the gas flow detector 50 has a predetermined difference from the previous one, for example more than three times, it is determined as a 'gas being consumed' state. At a 'gas not being consumed' state, the CPU 32 acquires the temperature and pressure from the temperature-measuring device 20 and the pressure-measuring device 25, for example every 60 minutes from 0:00AM in real time, to store an 'instant_T/P/K in the memory 34. At a 'gas being consumed' state, the CPU 32 acquires the temperature and pressure from the temperature-measuring device 20 and the pressure-measuring device 25, for example every 6 minutes from 0:00AM in real time, to store an 'instant_T/P/K in the memory 34. By repeating the above procedures, at 24:00PM the 'instant_T/P/K s for 24 hours are averaged to
TP calculate a 'daily_T/P/K ' In calculating the average value, all the data of that day is arithmetic-averaged, regardless of the state of 'gas being consumed' or 'gas not being consumed'. The number of data varies, but not exceed 240(=10 x 24) at maximum. Since the sampling period is 60 minutes or 6 minutes, the weighted value will be automatically reflected as much. Even in the state of 'gas not being consumed', the weighted value is reflected as much as 1/10, to thereby enable to respond to mal- operation of the function of confirming whether or not the gas is currently being consumed. Consecutively, as in the basic mode, the CPU 32 stores the 'daily_T/P/K in the memory 34 along with the date information, and then calculates a 'monthly_T/P/K up to that date and stores it in the memory 34. Everyday, a 'monthly_T/P/K up to that date is stored. Then, at the end of the month, a
TP
'monthly_/P/K up to that date is copied and stored as a 'monthly_T/P/K of that month separately in the memory 34. However, the 'monthly_T/P/K ' for each date is updated everyday.
[62] An alternative special mode confirms the amount of consumed gas. In this mode, first, the CPU 32 operates the gas flow detector 50 to confirm whether the gas is being consumed, for example every 2 seconds from 0:00AM in real time. In case where the gas flow detector 50 confirms using a photo-sensing mode whether gas is being consumed, it is confirmed whether one rotation of a particular number wheel is completed. The CPU 32 acquires the temperature T and pressure P from the temperature-measuring device 20 and the pressure-measuring device 25 to calculate and store an 'instant_T/P/K ', for example every one, two, four or eight rotations of the particular number wheel. Consecutively, the CPU 32 averages the 'instant_T/P/K 's of 24 hours at 24:00PM to calculate and store a 'daily_T/P/K and a 'daily consumption'. All the data of that date is arithmetic- averaged. The 'daily consumption' is used as a weighted value when calculating a monthly average value. The CPU 32 stores the 'daily_T/P/K in the memory 34 with the date information and then calculates a
'monthly_T/P/K up to that date and stores it in the memory 34. The 'monthly_T/P/K up to that date continues to be updated every day.
[63] The T&P compensation coefficient obtained through the above modes is reflected on the automatic reading values provided by the automatic reading unit 60 to thereby enable to calculate a T&P compensated gas consumption. These operational modes are programmed to the temperature and pressure compensation unit 30. Information on the T&P compensated gas consumption (automatic reading value before compensation, T &P compensation coefficient, T&P compensated consumption) is transmitted, together with user's information, to the local wireless communications relay 92 through the communications unit 90. The local wireless communications relay 92 collects information from gas consumers within a predetermined area, and transmits the collected information through the communications network 94 to the computer 96 of the gas supplier. Industrial Applicability
[64] As described above, the temperature and pressure compensation apparatus of this invention can be installed in each gas consumer's gas meter. This apparatus can precisely compensate for the temperature and pressure errors involved in read values (gas volume) of the gas meter, in cooperation with conventional digital gas meters.
[65] In addition, this apparatus of the invention can be installed in combination with an automatic reading device for volumetric gas meters. That is, from the combined construction, an automatic reading of gas consumption can be achieved, with the temperature and pressure error compensated.
[66] Although the present invention has been described with reference to several preferred embodiments, the description is illustrative of the invention and not to be construed as limiting the invention. Various modifications and variations may occur to those skilled in the art without departing from the scope and spirit of the invention, as defined by the appended claims.