FIELD OF THE INVENTION

The present invention relates to cleanliness determination for an air conditioner, and more particularly, to a system for determining cleanliness of an outdoor unit of an air conditioner and a method therefor.

BACKGROUND OF THE INVENTION

In general, an air conditioner has an indoor unit that is installed in an interior space of a building, and an outdoor unit that is installed outside of the building. As the outdoor unit is exposed to outdoor environment all the time, its internal part, for example the outdoor heat exchanger, is easy to get dirty by surrounding dirt and dust particles. User may not be able to notice the outdoor unit is getting dirty and would continue to operate the air conditioner under such condition. This may result the air conditioner to run less efficiently, consuming more electricity than it would if it was clean. Therefore, it is important to detect cleanliness of the outdoor unit so that the user could arrange maintenance or cleaning schedule on time to avoid sudden malfunctioning of the air conditioner.

There are a number of examples over the prior art aiming to determine cleanliness of the outdoor unit of the air conditioner without requiring user to be on site. One of the prior art documents is US10816286B2 that provides a system and method for signalling a need to clean condenser coils of an appliance when the coils were detected to be dirty. In detail, a temperature monitor is directly connected to the condenser coils and there will be signals indicating the condenser coils are dirty when the temperature monitor detects that there is a predetermined rise in temperature occurred from a baseline temperature that exists when the condenser coils are clean. It is mentioned in the prior art that the ambient temperature of the appliance is considered in setting the baseline temperature, however it seems that the ambient temperature of the appliance is not playing a substantial role in determining the baseline temperature as there is not much information provided on impact or effect of the ambient temperature of the appliance on the baseline temperature. Also, reliability of the system and method may not be convincing as the baseline temperature is set solely depending on the normal operating temperature range of the clean condenser coils.

There is another prior art document CN10889561 1 B discloses a method and device for determining whether the condenser of an air conditioner is dirty and clogged. Three parameters including high-pressure value, exhaust temperature and ambient temperature of the air conditioner during operation are acquired to determine whether the condenser is in a dirty condition. In detail, the high-pressure value is taken to determine an actual saturation temperature and an exhaust temperature reference value, while the ambient temperature of the air conditioner is taken to determine a saturation temperature reference value. Then, difference between the actual saturation temperature and the saturation temperature reference value, and difference between the actual exhaust temperature and the exhaust temperature reference value are calculated and compared with a preset threshold for determination of cleanliness of the condenser. Nevertheless, the actual saturation temperature is not directly measured from the condenser as it is obtained based on the acquired high- pressure value and a pre-established pressure-temperature comparison table, which may involve additional step and time to obtain the actual saturation temperature from the acquired pressure value. Also, the saturation temperature reference value is determined solely based on the ambient temperature of the air conditioner that is taken near the outdoor heat exchanger, without further considering other factors. Furthermore, the prior art requires additional sensor at the exhaust area to acquire the exhaust temperature.

Accordingly, it can be seen in the prior art documents that there exists a need to provide a system or method for determining the cleanliness of the air conditioner outdoor unit with improved reliability, accuracy and convenience. SUMMARY OF THE INVENTION

An object of the present invention is to provide a system that is capable of determining abnormality in performance of an air conditioner caused by cleanliness of an outdoor unit of the air conditioner.

It is also an object of the present invention to provide a system for determining cleanliness of an outdoor unit of an air conditioner with a higher accuracy by acquiring indoor temperature, outdoor temperature and condensing temperature of an outdoor heat exchanger for determination of cleanliness of the outdoor unit.

Another object of the present invention is to provide a system that determines a condensing temperature based on indoor wet bulb temperature and outdoor ambient temperature as a reference point for determining cleanliness of an outdoor unit of an air conditioner.

A further object of the present invention is to provide a system that determines a condensing temperature based on indoor wet bulb temperature, outdoor ambient temperature and length of a connecting pipe between an outdoor unit and an indoor unit of an air conditioner as a reference point for determining cleanliness of the outdoor unit of the air conditioner.

According to an aspect of the present invention, the above objects can be accomplished by the provision of a system for determining cleanliness of an outdoor unit of an air conditioner. The system comprising a first detection means for obtaining an indoor wet bulb temperature, a second detection means for obtaining an outdoor ambient temperature, a third detection means for obtaining a condensing temperature and a controller having a computing module for computing a reference condensing temperature based on the indoor wet bulb temperature and the outdoor ambient temperature as obtained by the first and second detection means. The controller further comprising a determining module for determining the cleanliness of the outdoor unit. The cleanliness of the outdoor unit is determined as dirty when the condensing temperature is higher than the reference condensing temperature.

In a preferred embodiment of the present invention, the computing module computes the reference condensing temperature by using the equation of:

T _c = a (T _in ) + b (T _in ) ² + c (T _out ) + d (T _out ) ² + ^e (T _in )(T _0Ut ') + f where

T _c denotes the reference condensing temperature; Tin denotes the indoor wet bulb temperature; Tout denotes the outdoor ambient temperature; and a, b, c, d, e and f are constant values. The condensing temperature is preferably a condensing temperature of an outdoor heat exchanger in the outdoor unit.

In a further embodiment of the present invention, the computing module may further include a length of a connecting pipe between the outdoor unit and an indoor unit of the air conditioner in computing the reference condensing temperature.

Preferably, the first detection means comprises a temperature sensor and a humidity sensor disposed in an area where an indoor unit of the air conditioner is installed for obtaining the indoor wet bulb temperature. Alternatively, the first detection means could be a single wet bulb temperature sensor for obtaining the indoor wet bulb temperature.

The second detection means is a temperature sensor preferably disposed near the outdoor unit of the air conditioner, preferably an air inlet of the outdoor unit, while the third detection means is a temperature sensor which is placed at a position on the outdoor heat exchanger. The system of the present invention further comprises a database for storing a set of pre-computed reference condensing temperatures based on a plurality of indoor wet bulb temperatures and outdoor ambient temperatures. Also, the system comprises an indicator for providing an indication of the cleanliness status of the outdoor unit.

It is preferred that the cleanliness of the outdoor unit is determined when the operation of the air conditioner is in a predefined condition for a predetermined operating duration of the air conditioner. The predefined condition of the operation of the air conditioner includes having any one or a combination of compressor frequency, indoor unit fan speed and outdoor unit fan speed to be operated within a manufacturer’s predefined operating range. Further, the predetermined operating duration is preferably in a range of 10 to 90 minutes.

The system of the present invention is configured to determine cleanliness of the outdoor heat exchanger in the outdoor unit.

According to another aspect of the present invention, there is provided a method for determining cleanliness of the outdoor unit of the air conditioner, wherein the method comprises obtaining an indoor wet bulb temperature via a first detection means, obtaining an outdoor ambient temperature via a second detection means, obtaining a condensing temperature via a third detection means, computing a reference condensing temperature using the indoor wet bulb temperature and the outdoor ambient temperature as obtained via a computing module of a controller, and determining the cleanliness of the outdoor unit by a determining module of the controller. The cleanliness of the outdoor unit is determined as dirty when the condensing temperature is higher than the reference condensing temperature.

BRIEF DESCIRPTION OF THE ACCOMPANYING DRAWINGS

The features of the invention will be readily understood and appreciated from the following detailed description when read in conjunction with the accompanying drawings of the preferred embodiments of the present invention, in which:

Figure 1 illustrates a system for determining cleanliness of an outdoor unit of an air conditioner according to a preferred embodiment of the present invention

Figure 2 is a flow chart illustrating steps executed by a system for determining cleanliness of an outdoor unit of an air conditioner according to a preferred embodiment of the present invention.

Figure 3(a) is a line chart illustrating relationship between condensing temperature of an outdoor heat exchanger and indoor wet bulb temperature, while Figure 3(b) is a line chart illustrating relationship between condensing temperature of an outdoor heat exchanger and indoor ambient temperature.

Figure 4 is a line chart illustrating relationship between condensing temperature of an indoor heat exchanger and outdoor ambient temperature.

Figure 5 is a dotted chart illustrating relationship between condensing temperature of an outdoor heat exchanger and length of a connecting pipe between an outdoor unit and an indoor unit of an air conditioner.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The abovementioned and other features and objects of this invention will become more apparent and better understood by reference to the following detailed description. It should be understood that the detailed description made known below is not intended to be exhaustive or limit the invention to the precise form disclosed as the invention may assume various alternative forms. All the relevant modifications and alterations made to the present invention as covered in the detailed description should be construed to fall within the scope of the appended claims. Therefore, the configuration of the invention is not limited to the configuration mentioned in the following description. The present invention relates to a system (200) for determining cleanliness of an outdoor unit of an air conditioner that could affect operation and performance of the air conditioner. The system (200) is adapted to assist user to detect poor cleanliness of the outdoor unit in order to prevent such condition from prolonged, so that the air conditioner could maintain its operation and performance without being affected by such issue. In particular, the system (200) is aimed to detect cleanliness of an outdoor heat exchanger in the outdoor unit that would become dirty after certain duration of operation. Further, the system (200) allows the outdoor unit to perform self-diagnosis on its cleanliness without requiring user to be on site and to notify the user the need of having cleaning and maintenance service so as to prevent operation and performance of the air conditioner from being affected or even degraded due to poor cleanliness of the outdoor unit.

With reference to Figure 1 , the system (200) of the present invention comprising a first detection means (210) for obtaining an indoor wet bulb temperature, a second detection means (212) for obtaining an outdoor ambient temperature, a third detection means (214) for obtaining a condensing temperature and a controller (220) that is configured to receive and process information as obtained by the above-mentioned detection means so as to determine the cleanliness of the outdoor unit.

The controller (220) of the present invention is provided with a computing module (222) for computing a reference condensing temperature based on the indoor wet bulb temperature and the outdoor ambient temperature as obtained by the first and second detection means (210, 212). The controller (220) further comprises a determining module (224) for determining the cleanliness of the outdoor unit, in which the cleanliness of the outdoor unit is determined as dirty when the condensing temperature as detected is higher than the reference condensing temperature. On the other hand, if the condensing temperature as detected is lower or is not higher than the reference condensing temperature, the cleanliness of the outdoor unit is determined as acceptable. In a preferred embodiment of the present invention, the computing module (222) is configured for computing the reference condensing temperature using the equation of: where T _c denotes the reference condensing temperature; Tin denotes the indoor wet bulb temperature; Tout denotes the outdoor ambient temperature; and a, b, c, d, e and f are constant values. The constant values could be determined via multiple regression analysis using a plurality of indoor wet bulb temperature data and a plurality of outdoor ambient temperature data as input variables, and a plurality of reference condensing temperature data as output variable. These temperature data may be obtained under different operating conditions.

In another preferred embodiment of the present invention, the computing module (222) of the present invention may further include a length of a connecting pipe between the outdoor unit and an indoor unit of the air conditioner when computing the reference condensing temperature. The length of the connecting pipe may be varied depending on each installation site of the air conditioner. In this preferred embodiment, the computing module (222) may be configured for computing the reference condensing temperature using the equation of:

T _c = PL [a (Tin) + b (T _in ) ² + ^c Tout) + d (T _out ) ² + e (T _in )(T _0Ut ) + f] where T _c denotes the reference condensing temperature; Tin denotes the indoor wet bulb temperature; Tout denotes the outdoor ambient temperature; a, b, c, d, e and f are constants, and PL is a correction factor according to the length of the connecting pipe. Furthermore, the correction factor could be determined using the equation of:

PL = g(Pipe length) + h where PL is the correction factor according to the length of the connecting pipe; g is gradient of equation; and h is constant value. The gradient and the constant value of the equation could be determined via linear regression using different lengths of the connecting pipe as input variable and its corresponding correction factors as output variable. In detail, each of the correction factors serving as the output variable could be determined by division of a condensing temperature as detected by a reference condensing temperature. The condensing temperature as detected may be obtained under a predetermined operating condition that applies a specific length of the connecting pipe between the indoor unit and the outdoor unit.

In one embodiment of the present invention, the first detection means (210) is preferably comprising a temperature sensor and a humidity sensor disposed in an area where an indoor unit of the air conditioner is installed for obtaining the indoor wet bulb temperature. In another embodiment of the present invention, the first detection means (210) could be a wet bulb temperature sensor for obtaining the indoor wet bulb temperature. Further, the second detection means (212) is a temperature sensor disposed near the outdoor unit of the air conditioner for obtaining the outdoor ambient temperature. The second detection means (212) is preferably disposed at a position at the air inlet area before air passing the outdoor heat exchanger of the outdoor unit.

The condensing temperature of the present invention is a condensing temperature of the outdoor heat exchanger. The condensing temperature is obtained by the third detection means (214) which is preferably a temperature sensor disposed at a position on the outdoor heat exchanger. The third detection means (214) may be disposed at any position on the outdoor heat exchanger where the temperature of the outdoor heat exchanger is detectable. Preferably, it may be disposed at a position near the middle part of the outdoor heat exchanger.

According to a preferred embodiment of the present invention, the system (200) may further comprise a database (230) for storing a set of pre-computed reference condensing temperature based on a plurality of indoor wet bulb temperatures and outdoor ambient temperatures in order to provide quick and accurate result of the reference condensing temperature. Preferably, the set of pre-computed reference condensing temperatures are determined based on the plurality of indoor wet bulb temperatures and outdoor ambient temperatures that are obtained under different conditions where the outdoor unit is clean. When the computing module (222) receives information of the indoor wet bulb temperature and the outdoor ambient temperature from the first and second detection means (210, 212), the reference condensing temperature corresponding to the indoor wet bulb temperature and the outdoor ambient temperature could be found and retrieved from the set of pre-computed reference condensing temperatures in the database (230). Storing of the set of pre-computed reference condensing temperatures in the database (230) could allow a particular reference condensing temperature that corresponds to particular indoor wet bulb temperature and outdoor ambient temperature to be quickly retrieved by the system (200).

According to another preferred embodiment of the present invention, the system (200) may further comprise an indicator (240) for providing an indication of the cleanliness status of the outdoor unit. The indicator (240) may show the cleanliness status in a form that is visually and/or audibly noticeable by the user of the system (200). The indicator (240) may be a LED light which will blink in certain manner to indicate the cleanliness status. It is possible that the indicator (240) to be disposed on a display of the air conditioner unit or a display of a separate remote controller.

Alternatively, the indicator (240) could be a software or an application installed in a mobile device which forms a wireless connection with the system (200) and users are able to receive any notification on the cleanliness via the software or application after the system (200) performing determination of cleanliness of the outdoor unit. On the other hand, the same software or application could be used by the users for the purpose of initiating or/and interrupting the process of determination of cleanliness of the outdoor unit. In another preferred embodiment of the present invention, the system (200) is configured to be initiated automatically once the air conditioner starts to run its operation without any initiation from the user.

In a preferred embodiment of the present invention, the cleanliness of the outdoor unit is determined when the operation of the air conditioner is in a predefined condition for a predetermined operating duration of the air conditioner. The predefined condition of the operation of the air conditioner preferably includes having any one or a combination of compressor frequency, indoor unit fan speed and outdoor unit fan speed to be operated within a manufacturer’s predefined operating range. It is important to ensure that the performance of the compressor, the indoor unit fan and/or the outdoor unit fan is in stable and normal state so as to eliminate other possibilities that could affect operation of the outdoor unit before determining cleanliness of the outdoor unit. Furthermore, the predetermined operating duration is preferably in a range of 10 to 90 minutes, more preferably in a range of 15 to 60 minutes. However, it is not limited to such setting as the predefined condition and/or predetermined operating duration could be varied to suit different specification of air conditioner.

Figure 2 shows a method for determining cleanliness of the outdoor unit of the air conditioner via the aforedescribed system (200). The steps of the method have been primarily described and illustrated in the preceding paragraphs. At step 310, the operation of the air conditioner is checked to confirm that it is in a predefined condition for a predetermined operation duration before initiating the system (200) to undergo determination of cleanliness of the outdoor unit at step 320. The predefined condition includes having compressor frequency, indoor unit fan speed and outdoor unit fan speed operated within a manufacturer’s predefined operating range for the predetermined operating duration. The step 310 is to ensure the overall operation of the air conditioner is stable and normal before proceed to step 320.

When the system (200) initiates the method of determination of cleanliness of the outdoor unit, it will proceed to steps 330 and 340, in which the system (200) is configured for obtaining an indoor wet bulb temperature, an outdoor ambient temperature and a condensing temperature of the air conditioner via the first, second and third detection means (210, 212, 214), and subsequently computing a reference condensing temperature using the indoor wet bulb temperature and the outdoor ambient temperature as detected via the computing module (222) in the controller (220) of the present invention. The computing module (222) may further include a length of a connecting pipe between the outdoor unit and the indoor unit of the air conditioner for computing the reference condensing temperature. Then, the cleanliness of the outdoor unit will be determined by the determining module (224) in the controller (220) at step 350. When the condensing temperature as detected is higher than the reference condensing temperature, the cleanliness of the outdoor unit will be determined as dirty. The system (200) will then provide an indication of the cleanliness status of the outdoor unit to user via the indicator (240) of the present invention at step 360.

Figure 3(a) shows the effect of indoor wet bulb temperature on the condensing temperature of the outdoor heat exchanger, while Figure 3(b) shows the effect of indoor ambient temperature, which is also known as indoor dry bulb temperature, on the condensing temperature of the outdoor heat exchanger. It can be seen from these two figures that the indoor wet bulb temperature has significant impact on the condensing temperature, whereas the indoor ambient temperature shows no significant impact on the condensing temperature. In detail, an increase in the indoor wet bulb temperature corresponds to an increase in the condensing temperature. On the other hand, the condensing temperature does not have much changes when the indoor ambient temperature increases.

Figure 4 shows the effect of outdoor ambient temperature, which is also known as outdoor dry bulb temperature, on the condensing temperature of the outdoor heat exchanger. As the outdoor dry bulb temperature increases, the condensing temperature becomes higher. It can be seen that the outdoor ambient temperature has a significant impact on the condensing temperature. Thus, by taking both the indoor wet bulb temperature and the outdoor ambient temperature into determination of the reference condensing temperature, this could greatly improve accuracy of determination of cleanliness of the outdoor unit without causing false positive errors as compared to those prior arts that only consider either indoor ambient temperature or outdoor ambient temperature in their determination.

Figure 5 shows the effect of the length of a pipe connecting the outdoor unit and the indoor unit of the air conditioner on the condensing temperature of the outdoor heat exchanger. It is shown that the changes in the length of the connecting pipe give a great impact on the condensing temperature. As the length of the connecting pipe gets shorter, the higher the condensing temperature becomes, which could be possibly due to a higher refrigerant volume. By considering the length of the connecting pipe into determination of the reference condensing temperature, the accuracy and reliability of the system (200) and method of the present invention could be greatly improved.

Various modifications to these embodiments are apparent to those skilled in the art from the description and the accompanying drawings. The principles associated with the various embodiments described herein may be applied to other embodiments. Therefore, the description is not intended to be limited to the embodiments shown along with the accompanying drawings but is to be providing broadest scope of consistent with the principles and the novel features disclosed or suggested herein. Accordingly, the invention is anticipated to hold on to all other such alternatives, modifications, and variations that fall within the scope of the present invention and appended claims.