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Title:
METHOD FOR MONITORING THE RIDE QUALITY OF AN ELEVATOR SYSTEM
Document Type and Number:
WIPO Patent Application WO/2017/178495
Kind Code:
A1
Abstract:
A method for the detection of the ride quality of an elevator system (1) comprising an elevator cabin (3) movably arranged in an hoistway (2) by means of suspension means (5) and a drive (8), the elevator system further comprising a load sensor (11) for detecting the load (L) of the elevator cabin (3) connected to a control unit (10) including the following steps: generating a load characteristic signal (LCS) of the elevator cabin (3) after a predetermined standstill time without opening/closing of the elevator cabin doors, communicating the load characteristic signal (LCS) to the control unit (10), determining a maximal and minimal load characteristic signal (LCSmax, LCSmin) and a variation of the load characteristic signal (ALCS=LCSmax-LCSmin) over a time interval (t) which started after said predetermined standstill time without opening/closing of the elevator cabin doors.

Inventors:
MAURY JULIEN (CH)
VILLA VALERIO (IT)
Application Number:
PCT/EP2017/058698
Publication Date:
October 19, 2017
Filing Date:
April 11, 2017
Export Citation:
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Assignee:
INVENTIO AG (CH)
International Classes:
B66B5/00
Foreign References:
JP2006264853A2006-10-05
JP2004018246A2004-01-22
EP1958911A12008-08-20
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Claims:
Claims

1. Method for monitoring the ride quality of an elevator system (1) comprising an elevator cabin (3) movably arranged in an hoistway (2) by means of suspension means (5) and a drive (8), the elevator system further comprising a load sensor

(11) for detecting the load (L) of the elevator cabin (3) connected to a control unit (10), including the following steps:

a) generating a load characteristic signal (LCS) of the elevator cabin (3) by the load sensor (11) after a predetermined standstill time without opening/closing of the elevator cabin doors,

b) communicating the load characteristic signal (LCS) to the control unit (10), c) determining characteristic features of the load characteristic signal (LCS) over a time interval (t) which started after said predetermined standstill time without opening/closing of the elevator cabin doors,

d) determining a variation of the characteristic features over the time interval (t).

2. Method according to claim 1, characterized in that step c) is determining a maximal and minimal load characteristic signal (LCSmax, LCSmm) over the time interval (t) and in that step d) is determining a variation of the load characteristic signal over the time interval (t)

3. Method according to claim 1 or 2, characterized in that the method comprises a further step of

e) determining the ride quality of the elevator system (3) during the time interval (t) based on the determined variation of the load characteristic signal (ALCS).

4. Method according to claim 3, characterized in that step e) is performed by comparing the determined variation of the load characteristic signal (ALCS) with a characteristic pattern, a value or a given threshold (TV) value.

5. Method according to one of the preceding claims, characterized in that also an average load characteristic signal (LCSavg) is determined in step c). Method according to claim 5, characterized in that the determined load average characteristic signal (LCSavg) is taken into account when determining the ride quality of the elevator system (1) in step e).

Method according to claim 1 , characterized in that the determined data in step c) and/or d) are stored in storage means (16), in particular storage means (16) of the control unit (10).

Method according to one of the preceding claims, comprising the further step of transmitting the determined data to a further remote unit.

Method according to one of the preceding claims, characterized in that the method is performed with the elevator cabin (3) moving at a nominal given speed, the nominal given speed being lower than the normal operational speed of the elevator cabin (3).

Method according to one of the preceding claims, characterized in that a movement situation of the elevator cabin (3) is taken into account when performing the method.

11. Method according to one of the preceding claims, characterized in that the time interval (t) corresponds to time (tnde) of a ride of the elevator cabin (3) between two stops.

Description:
Method for monitoring the ride quality of an elevator system

The invention relates to a method for monitoring the ride quality of an elevator system according to the independent claim.

In elevator systems it is important to reliably monitor the state of the system, which may decrease the ride quality of the elevator due as an example to noise and/or vibrations of parts of the system, which are perceived as uncomfortable by a passenger.

Acoustic detection systems are used for monitoring the noise in a hoistway of an elevator system and compare it with a given noise pattern for monitoring the state of the system and to early detect malfunctions. Differences or irregularities in the noise pattern are generally linked to a possible malfunction of the elevator system, e.g. slipping of the suspen- sion means, low lubrication of parts of the elevator system etc. Disadvantage of such a detection system is that noise sensors, which are normally not present in an elevator system, must be arranged within the hoistway and connected to a control unit. Such a detection system is therefore expensive and must be maintained in order to work properly.

It is therefore aim of the present invention to provide a method for monitoring the ride quality of an elevator system with accurate predictions, which also can be implemented in existing elevator systems and is therefore less cost intensive.

This problem is solved with a method according to claim 1. The method for monitoring the ride quality of an elevator system comprising an elevator cabin movably arranged in an hoistway by means of suspension means and a drive, the elevator system further comprising a load sensor for detecting the load (L) of the elevator cabin connected to a control unit, includes the following steps: First, generating a load characteristic signal (LCS) of the elevator cabin by the load sensor after a predetermined standstill time without opening/closing of the elevator cabin doors. Then, communicating the load characteristic signal to the control unit. Then, determining characteristic features of the load characteristic signal over a time interval which started after said predetermined standstill time without opening/closing of the elevator cabin doors. And finally, determining a variation of the characteristic features over the time interval. The data be gathered only during selected rides of the elevator cabin after a predetermined standstill time without opening/closing of the elevator cabin doors where it can be assumed that the elevator cabin is empty. The data gathered is therefore equivalent and well comparable. Preferably, the determined data according to the method of the present invention is gathered at a nominal given speed and/or at a pre-established time in order to further exclude any possible human interactions due, as an example, to passengers moving during a ride. The nominal speed is preferably lower than the normal operational speed of the elevator cabin.

The method preferably comprises a further step of determining the ride quality of the elevator system during the time interval based on the determined variation of the load characteristic signal. A further advantage is that it can be implemented in existing elevator systems.

It has been surprisingly found out that, regardless of the load of the cabin and, in case of movement of the elevator cabin, as well as the direction of travel of the elevator cabin (upward or downward), the variation of the load characteristic signal is constant in a given elevator system. However, if a decrease of the ride quality is present in the elevator system, additional vibrations are transmitted to the elevator cabin, thus changing the maximal and minimal load characteristic signal and thus the variation of the load characteristic signal.

Preferably, when determining the maximal and minimal load characteristic signal, also an average load characteristic signal is detected. The advantages of determining an average value are that a drift of the measured load characteristic signal may be determined by monitoring the average load characteristic signal and determining if the average load characteristic signal, compared to predefined criteria, has changed or the rate of changing is too fast.

The average load characteristic signal may also be be taken into consideration when determining the ride quality of the elevator system. In a preferred, additional step, the variation of the load characteristic signal is compared with a characteristic pattern, a value or a given threshold value. As cited above, the variation of the load characteristic signal is not varying much in an elevator system, irrespective of the load in the cabin. If the variation of the load characteristic signal is above a given threshold value, it is probable that a malfunction is present in the elevator system.

Preferably, the threshold value is a predetermined value which is determined when installing the elevator system. However, the elevator threshold value may change over time and may be updated by a technician, a remote maintenance centre or changed automati- cally by the system.

Preferably, the data determined according to the steps cited above are stored in storage means, e.g. of the control unit. The storage means is preferably a non- volatile storage means such as a hard disk, a solid state drive, a flash memory etc. The storage means must not necessarily be a storage means of the control unit. It is possible that the storage means is located remote of the elevator system, e.g. at a maintenance centre, and communicate with the control unit over a data connection. Another alternative is that the storage means is integrated into the load sensor.

The storage means can be remotely accessible. That means that the storage means can be accessed with a remote device such as a computer from a remote location, e.g. a maintenance centre. It is therefore possible for a technician to log in and analyse the determined data in order to detect malfunctions and/or check the ride quality of the elevator system. It is also conceivable, that the data is recorded locally and then read out by a technician if he is on site at the location of the elevator system.

The data is preferably further processed by the control unit or other suitable means in order to create a history of the collected and determined data and/or a history graph for a maintenance technician or the like.

It is therefore possible for a maintenance technician to monitor the changes in the ride quality of an elevator system without the need of inspecting the elevator system. Preferably, if the determined variation of the load characteristic signal is above a given threshold value, an alarm signal is generated by the control unit or other suitable means, e.g. an alarm message is sent to a maintenance technician and/or to a maintenance centre. Alternatively or additionally, the trend of the determined variation of the load characteris- tic signal over time may be monitored and an alarm signal generated if the load variation frequency difference changes too fast.

Preferably, a movement situation (movement up/down, acceleration/deceleration, standstill) of the elevator cabin is taken into account when performing the method. This may be preferably done by taking into consideration data from other sensors such as an acceleration sensor of the elevator cabin, incremental counter of a pulley etc. As cited above, knowledge of the movement situation of the elevator cabin is relevant to discriminate between a ride situation where the load of the elevator cabin is normally constant but acceleration changes and a standstill situation where acceleration is constant (correspond- ing to gravity) but the load of the elevator cabin may change due to loading/unloading of the elevator cabin.

The advantages described above regarding the method according to the present invention may also apply to an elevator system. The elevator system according to the present invention comprises an elevator cabin movably arranged in a hoistway by means of suspension means and a drive. The elevator system further comprises a load sensor being able to generate a load characteristic signal of the elevator cabin connected to a control unit. The control unit is able to determine a maximal and minimal load characteristic signal and a variation of the load characteristic signal.

The control unit is able to determine a ride quality of the elevator based on the determined variation of the load characteristic signal.

The control unit may be integrally implemented in the actual control unit of the elevator system or, in the case of a modernization of an older elevator system, can be incorporated in a separate unit. Preferably, the elevator system further comprises storage means for storing data of the load sensor and/or control unit. Therefore, it is possible to store data of a subsequent analysis or diagnosis.

Preferably, the elevator system further comprises a data communication interface. It is therefore possible to send and/or receive data from/to the elevator system to/from a remote unit such as a maintenance system. This allows a remote inspection of the data stored in the storage means, in order to perform a remote diagnosis of the elevator system.

The elevator system comprises an elevator cabin movably arranged in a hoistway by means of suspension means and a drive. The elevator system further comprises a load sensor for detecting the load of the elevator cabin connected to a control unit.

The load sensor may be a load cell arranged between the suspension means and the elevator cabin. An alternative are sensors arranged below the elevator cabin floor, sensors arranged at a drive sheave or suspension pulleys, sensors arranged or integrated on or in a top yoke or bottom yoke or sensors arranged at a fixation point of the suspension means of the elevator system.

The load sensor generates a load characteristic signal. The signal is dependent on the load sensor installed in the elevator system and may be a wave signal which may is preferably modulated in amplitude and/or frequency. The signal generated by the load sensor may reflect a voltage or a current intensity. Said signal may be a digital or analog signal.

The load sensor is used in elevator systems to detect the load of the elevator cabin in order to avoid overload of the elevator cabin. By measuring the load of the cabin, unnecessary empty rides may also be avoided. The load of the cabin can be monitored continuously during the operation of the elevator system, irrespective if the elevator cabin is standing still at a stop position for loading/unloading or the elevator cabin is traveling along the hoistway.

The load characteristic signal is then transmitted to a control unit. The control unit is preferably adapted to perform different tasks of the elevator control such as controlling a ride, open and close doors, control brakes etc. The control unit may also be integrated in the load sensor.

The control unit then determines a maximal and a minimal load characteristic signal and a variation of the load characteristic signal corresponding to the difference between the maximal load characteristic time and the minimal load characteristic time over a time interval. Instead of the maximal and the minimal load characteristic signal the control unit may determine other characteristic features of the load characteristic signal such as oscillations and frequencies thereof. The time interval may be a discreet time as the time for a ride between two stops. The time interval may alternatively start when the elevator system is taken into operation, wherein the load characteristic signal is processed continuously over the whole life of the elevator system, thus the time interval being indefinite with only a known start point. It is clear that the time interval may also be chosen in order to avoid data which may affect the correct determination of the load characteristic signal, e.g. the maximal and a minimal load characteristic signal are determined in a time interval starting shortly after a ride start and ending shortly before a ride stop in order to avoid peaks of the load characteristic signal. The load characteristic signal may also be processed by the control unit, e.g filtered, smoothened etc., prior to the determination of the maximal and a minimal load characteristic signal in order to minimise data peaks and the like.

The load characteristic signal is mainly influenced by two parameters: the acceleration the elevator cabin is subjected to (including gravity) and the load present in the elevator cabin. The equation

LCS(t)= m(t, a(t)) + F

gives a simplified idea on how the load characteristic signal is influenced, wherein LCS(t) is the load characteristic signal at a given time t. F is a factor which may take other influences into consideration, but is not relevant for the understanding of the present invention. The load characteristic signal is influenced by the acceleration a of the elevator cabin is subjected to either during a ride or in a standstill position and by the mass m of the elevator cabin including the load of the cabin. Since it can be assumed that the load of the cabin and thus the elevator cabin mass m do not vary during a ride, while the acceleration the elevator cabin is subjected to varying only during a ride (when accelerating and decelerating), a variation of the load characteristic signal is therefore only influenced by the acceleration a or the mass m depending on the movement state (ride or standstill) of the elevator cabin.

The load characteristic signal can therefore be used to monitor the ride quality of an elevator system, if the movement state of the cabin is known.

Further advantages of the invention will be better understood with the aid of the following description together with the figures. It is shown in

Fig. 1 a schematical view of an elevator system, and

Fig. 2 a graph that represents the historical variations of a load characteristic signal at constant speed in various days.

In Fig. 1 an elevator system 1 with a hoistway 2 is shown. An elevator cabin 3 and a counterweight 4 are movably arranged in the hoistway 2 and connected to each other by means of a suspension means, in this case, for example, a steel rope 5. The steel rope 5 is conducted over a pulley 6 and a traction sheave 9 connected to an electric motor 8. The traction sheave 9 has an incremental rotary encoder 12 connected to it in order to detect movement of the traction sheave 9 and therefore movement and direction of travel of the elevator cabin 3.

Each floor 7, 7' and 7" of the hoistway 2 has a building floor 18, which corresponds to a stopping position of the elevator cabin 3. Accordingly, a cabin floor 3.1 of the elevator cabin 3 is aligned with the respective building floor 18 when the elevator cabin 3 is standing still at a floor 7, 7' or 7". In Fig. 1, the elevator cabin 3 has stopped at floor 7'.

A control unit 10 including storage means 16 is further connected to the electric motor 8 and a load sensor 11 arranged between the steel rope 5 and the elevator cabin 3. The load measurement can be made by other means. For example, the load sensor could be integrated in the cabin floor or in a yoke at the bottom of the cabin. The control unit 10 is further connected over a data connection 17 with a remote maintenance centre (not shown). In this case the monitoring method is performed on a daily basis when the elevator system 1 is subject to a long standstill period and no ride of the elevator cabin 3 and no opening/closing of the doors has taken place, so that it can therefore be assumed that the elevator cabin is empty. The elevator cabin 3 is brought to the lowest floor of the building and a measuring ride at a given speed is performed. In this example, the elevator cabin 3 is brought to the upmost floor of the building and stopped there. Successively, the elevator cabin 3 is brought from the upmost floor of the building to the lowest floor again at the same speed. The speed is in this case lower than the normal operational speed of the elevator cabin.

The monitoring method may be performed in other ways such as, in order not to disturb the customers, the above mentioned ride can be the first trip of the day or the last trip of the night (parking) or a night ride when the elevator system is not used (e.g. in an office building).

During the rides of the elevator cabin 3, the load L of the elevator cabin 3 is determined by the load sensor 11 and transmitted to the control unit 10 over a data connection (not shown). The load sensor 11 generates a load characteristic signal, in this case an electrical signal with a frequency corresponding to a load of the elevator cabin. In this case, due to the arrangement of the load sensor 11 , the frequency decreases with increasing load of the elevator cabin. The generated frequency signal is transmitted to the control unit 10 for further processing.

The control unit 10 determines the maximal and minimal frequency f ma x and f m m and a variation of the frequency Δί, corresponding to the difference between the maximal an minimal frequency (fmax-fnm), during the measuring ride.

The maximal and minimal frequency f ma x and f m m as well as the variation of the frequency Δί are stored in the storage means 16.

In Fig. 2, an example of a graph that represents the historical variations of the frequency Δί at constant speed in various days is shown. The variation of the frequency Δί history graph for an upward ride is concretely shown. Such a graph is generated by the control unit and can be remotely accessed by a maintenance technician over the data connection 17. The graph shows the trend of the variation of the frequency in Hz over a period of time, wherein the variation of the frequency Δί is measured and determined on a daily basis, as cited above.

It can be seen that over a long period of time, the variation of the frequency Δί has been in the range of about 50 Hz until day 100, where a sudden increase of the variation of the frequency Δί up to about twice the initial value was determined. In this case, since Δί is above a given elevator system specific threshold TV of 55 Hz, an alarm message is sent over the data connection 17 to the remote maintenance centre of the elevator maintenance company, where a technician is informed of a possible malfunction of the elevator system 1. The maintenance technician has then the possibility of accessing the storage means 16 and analysing the data stored therein in order to determine if the alarm message is justified, if it is only a temporary disturbance of the elevator system 1 , e.g. due to human interactions, or it is even a false alarm and can then decide if inspection of the elevator system 1 is necessary. In this case, the elevator system 1 can be remotely locked in order to avoid its use before the cause of the malfunction has been identified.