Elevator safety system and method for testing an elevator car braking

Abstract

The present invention relates to an elevator safety system (1) of an elevator (2). This invention further relates to a method for testing an elevator car (5) braking. This invention relates also to an elevator (2) comprising such an elevator safety system (1) or being able to be tested through a said method. The safety system (1) comprises a camera (7) and a controller (8) being able to communicate wired or wirelessly with the camera (7) in this manner that the controller (8) detects a sliding motion of an elevator car (5) during the elevator car (5) braking along a guide rail (9), the controller (8) receives a first image captured by the camera (7) upon the detection of the sliding motion, wherein the first image indicates a reference object (10) in a shaft (6) of the elevator (2), and receives a second image of the reference object (10) captured by the camera (7) when the elevator car (5) is stopped, the controller (8) determines a slide distance of the elevator car (5) based on the reference object (10) captured in the first and the second image.

Description

[0001] ELEVATOR SAFETY SYSTEM AND METHOD FOR TESTING AN ELEVATOR CAR BRAKING

[0002] The present invention relates to an elevator safety system of an elevator. This invention further relates to a method for testing an elevator car braking. This invention relates also to an elevator comprising such an elevator safety system or being able to be monitored or tested through a said method.

[0003] An elevator transports passengers with an elevator car which is arranged to be moved along at least one guide rail in an elevator shaft. The elevator car has a safety brake, also known as a safety gear, capable of braking movement of the car intensely by gripping the guide rail in case of emergency, particularly activation of an overspeed governor in the case of car overspeed when a predefined car speed is exceeded. When braking takes place, the brake is brought into frictional contact with the guide rail and the car is thereby sliding along the guide rail. When the elevator car braking, different slide distances will occur depending on the surface wear of the guide rails and brakes and contact conditions of them.

[0004] Every elevator has to go through periodic testing in the field and one such test is, for example, safety brake where the loaded car accelerates until the overspeed governor activates and triggers the safety brake to hold the car to the guide rails and start to decelerate until it stops.

[0005] A braking distance should not become too large during the operation of the elevator to prevent a danger. Accordingly, setting and checking of the safety brake and the guide rail is usually required for reliable operation of the elevator, for example, in the event of a change occurred in the brake or in its working condition. Determination of braking slide in a test is of essential for such setting and checking. In such a test, for example, a specific load and speed of the elevator car can be determined in advance. By pressing the safety brake against the guide rail, it is principle possible to measure the resulting stress trajectory on the guide rail. However, the exact start position and the end position of the slide as well as its length are often difficult and complex to determine and measure. Normally, it is required that a technician has to enter the shaft and physically measure the slide distance on the guide rail and record measurement results on site.

[0006] An object of the invention is therefore to test or monitor a safety braking of an elevator car in an easy way, in particular, makes it possible to overcome the above-mentioned disadvantages. This object is solved by the features indicated in independent claims. Advantageous embodiments and further developments of the invention are given in dependent claims.

[0007] According to the first aspect of the present invention, an elevator safety system of an elevator comprises at least one camera and a controller, wherein the controller is capable of communicating wired or wirelessly with the camera, so that the controller may detect a sliding motion of an elevator car when the elevator car is braked along a guide rail, receive a first image captured by the camera upon the detection of the sliding motion, wherein the first image is indicative of a reference object in a shaft of the elevator, and receive a second image of the reference object captured by the camera when the elevator car is stopped. The controller may also determine a slide distance of the elevator car based on the reference object captured in the first and the second image. The camera may be a 3D-camera, depth camera, or a range camera, for example, a ToF-camera (time-of-flight). The camera and the reference object are installed opposite each other so that the camera may observe and take photo or video of the reference object. All the components of the elevator safety system can either be integrated in a single device or connected as separate units to create an arrangement of the elevator.

[0008] According to an embodiment in respect of the first aspect of the invention, the size of the reference object is pre-set or known for the controller. Thus, the controller may calculate the slide distance based on the size of the reference object, even if the camera is a normal camera having only one lens.

[0009] According to a further embodiment in respect of the first aspect of the invention, the camera is installed on the roof or under the bottom of the elevator car, while the reference object is located under the ceiling or in the pit of the shaft accordingly. Such an arrangement may ensure that the reference object remains in front of the camera when the elevator car moves.

[0010] According to a further embodiment in respect of the first aspect of the invention, the controller is able to communicate wired or wirelessly with an elevator moving safety assembly for monitoring the sliding motion of the elevator car. Such an elevator moving safety assembly may comprise, for example, a speed governor and a safety brake so that it is possible to determine the slide distance based on speed, deacceleration of the elevator car detected by the speed governor and / or on friction due to contact of the guide rail and the safety brake. According to a further embodiment in respect of the first aspect of the invention, the controller is also able to evaluate the determined slide distance for checking the contact of the guide rail and the elevator safety assembly, for example, the safety brake. If the slide distance is greater than an allowable maximal distance, for example, an alarm is issued to instruct that the guide rail and / or the safety brake should be maintained or replaced. Since the current load of the elevator, for instance, how many peoples in the car, may affect the slide distance, so the evaluation of the slide distance should be taken with reference to a load measurement of the elevator car.

[0011] For this invention it is to use a camera to measure a slide distance of an elevator car in real time for testing a brake of an elevator car, so that it is possible to check whether the safety assembly and the guide rail are in good condition. So such a test or check can be performed remotely and faster, and it can avoid that a technician must enter the elevator shaft for carrying out a test or having a check. Using a camera in this way may also monitor the guide rail and help on ensuring the guide rail is clean before testing.

[0012] According to the second aspect of the present invention, a method for monitoring or testing an elevator car braking of an elevator comprises following steps:

[0013] - detecting a sliding motion during the elevator car braking along a guide rail;

[0014] - capturing a first image by at least one camera upon the detection of the sliding motion, wherein the first image indicates a reference object in a shaft of the elevator;

[0015] - capturing a second image of the reference object by the camera when the elevator car is stopped;

[0016] - determining a slide distance of the elevator car based on the reference object captured in the first and the second image.

[0017] According to an embodiment in respect of the second aspect of the invention, the size of the reference object is pre-set or known to determine the slide distance of the elevator car.

[0018] According to a further embodiment in respect of the second aspect of the invention, the camera is installed on the roof or under the bottom of the elevator car, and the reference object is located under the ceiling or in the pit of the shaft accordingly. For example, an accessory component of the elevator or a replaceable foreign object can be set as the reference object. An accessory component of the elevator, for example, can be an elevator buffer in a pit or a drive machine under the celling of the shaft. An elevator buffer is a safety device which is required to be mounted at the base of an elevator shaft. According to a further embodiment in respect of the second aspect of the invention, an elevator moving safety assembly comprises a speed governor and a safety brake, so that the determination of the slide distance of the elevator car is based on speed, deacceleration of the elevator car detected by the speed governor and / or on friction due to contact of the guide rail and the safety brake.

[0019] According to a further embodiment in respect of the second aspect of the invention, the determination of the slide distance is evaluated to check whether the contact of the guide rail and of the safety brake is safe, wherein the slide distance can be additionally evaluated with reference to a load measurement of the elevator car.

[0020] According to a further embodiment in respect of the second aspect of the invention, a notification signal will be generated if slide distance is greater than a pre-set value of distance. Such a notification signal can be an optical and / or acoustic signal and generated in the shaft and / or in the car. Such a notification signal can also be sent to a remote center of the elevator or to a mobile device like smart phone of a technician.

[0021] According to the third aspect of the present invention, an elevator is provided that comprises an aforesaid elevator safety system or is able to be tested through a method described above.

[0022] Further advantageous features of the invention can be seen from the following exemplary explanation thereof with reference to the drawings. However, neither the drawings nor the description shall be interpreted as limiting the invention.

[0023] Figure 1 an elevator installation with an elevator safety system according to the first and the third aspect of the invention,

[0024] Figure 2 a flowchart of a method for testing an elevator car braking according to the second aspect of the invention.

[0025] Fig. l shows an elevator 2 with an elevator safety system 1 according to the above-said invention. The elevator safety system 1 can be constructed as a single device or as an arrangement containing discrete separate units or components. The elevator safety system 1 comprises a camera 7, for example, a 3D- camera, and a controller 8 to communicate wired or wirelessly with the camera 7. Furthermore, the elevator 2 comprises an elevator car 5 which is guided by means of one or two guide rails 9 in a shaft 6 for transporting passengers between different floors 4 in a building. When the elevator car 5 braking along the guide rails 9 for landing at the respective floors 4, sometimes the car 5 could slide a short distance on the guide rails 9 until the car 5 finally stops in its defined landing position.

[0026] An elevator moving safety assembly 3 is arranged, which comprises, for example, an electronic speed governor and a safety brake (not shown). The controller 8 can communicate wired or wirelessly with this elevator moving safety assembly 3 for monitoring the sliding motion of the elevator car 5. So, the slide distance can be determined based on speed, deacceleration of the elevator car 5, and / or friction due to contact of the guide rail 9 and the safety brake of the elevator moving safety assembly 3. Then the controller 8 will receive a first image captured by the camera 7, wherein the first image indicates a reference object 10 in a shaft 6, wherein the size of the reference object 10 is pre-set or known for the controller 8 in advance.

[0027] The reference object 10 is located opposite to the camera 7 so that the camera 7 may capture photos or video of the reference object 10. That means when the camera 7 is installed on the roof of the elevator car 5, the reference object 10 should be under the celling of the shaft 6. Alternatively, the reference object should be located in the pit of the shaft 6 if the camera 7 is under the bottom of the car 5. The embodiment illustrated in Fig. 1 refers the latter case so that, for example, an elevator buffer can be set as the reference object 10. Alternatively or additionally, a foreign object like a glove or a tool can be temporally placed in the pit as a reference object 10 too.

[0028] Then the controller 8 may evaluate the determined slide distance for checking the contact of the guide rail 9 and of the safety brake, by the way the degree of wear of the slide rail 9 and the safety brake can also be tested, wherein the controller 8 calculates the slide distance in relation to the size of the reference object 10. Advantageously, the controller 8 may also refer to the current load measurement of the elevator car 5 when evaluating the slide distance. If the slide distance is too long, this means that the guide rail 9 or the safety brake is probably worn so much that they can no longer effectively contact each other. Consequently, it should be to maintain or replace them. For this case, a notification signal will be generated, which can be an optical and / or acoustic signal and generated in the shaft 6 and / or in the elevator car 5. This notification signal can also be sent to a remote centre 11 of the elevator 2 or to a mobile device (not shown) like smart phone of a technician. A flowchart in Fig.2 illustrates a method for testing an elevator car braking according to the said invention. For example, the method may comprise following steps:

[0029] S 1 : detecting a sliding motion of the elevator car 5 during the elevator car 5 braking along a guide rail 9 of an elevator 2;

[0030] S2: capturing a first image by a camera 7 upon the detection of the sliding motion, wherein the first image indicates a reference object 10 whose size is pre-set or known to determine the slide distance of the elevator car 5, wherein the camera 7 may be arranged on the roof or under the bottom of the elevator car 5, while the reference object 10 can be located under the ceiling or in the pit of the shaft 6 accordingly;

[0031] S3: capturing a second image of the reference object 10 by the camera 7 when the elevator car 5 is stopped;

[0032] S4: determining a slide distance of the elevator car 5 based on the reference object 10 captured in the first and the second image. The slide distance of the elevator car 5 is determined with help of an elevator moving safety assembly 3 and particularly based on speed, deacceleration of the elevator car 5 detected by a safety brake and / or friction due to contact of the guide rail 9 and a safety brake of the elevator moving safety assembly 3;

[0033] S5: evaluating the determined slide distance to check a contact of the guide rail 9 and of the safety brake;

[0034] S6: evaluating the slide distance meanwhile with reference to a load measurement of the elevator car 5;

[0035] S7: comparing the determined slide distance with a pre-set value of distance;

[0036] S8: generating a notification signal if slide distance is greater than a pre-set distance.

Claims

CLAIMS:

1. An elevator safety system (1) of an elevator (2) comprising: a camera (7), and a controller (8) being capable of communicating wired or wirelessly with the camera (7) in this manner that the controller (8)- detects a sliding motion of an elevator car (5) during the elevator car (5) braking along a guide rail (9);- receives a first image captured by the camera (7) upon the detection of the sliding motion, wherein the first image indicates a reference object (10) in a shaft (6) of the elevator (2);- receives a second image of the reference object (10) captured by the camera (7) when the elevator car (5) is stopped; and- determines a slide distance of the elevator car (5) based on the reference object (10) captured in the first and the second image.

2. The elevator safety system (1) according to claim 1, wherein the size of the reference object (10) is pre-set or known for the controller (8).

3. The elevator safety system (1) according to claim 1 or 2, wherein the camera (7) is installed on the roof or under the bottom of the car (5), and the reference object (10) is located under the ceiling or in the pit of the shaft (6) accordingly.

4. The elevator safety system (1) according to any of the preceding claims, wherein the controller (8) is able to communicate wired or wirelessly with an elevator moving safety assembly (3) for monitoring the sliding motion of the elevator car (5).

5. The elevator safety system (1) according to claim 4, wherein the determination of the slide distance is based on speed, deacceleration of the elevator car (5), and / or friction due to contact of the guide rail (9) and the elevator moving safety assembly (3).

6. The elevator safety system (1) according to claim 4 or 5, comprising: the controller (8) being able to evaluate the determined slide distance for checking the contact of the guide rail (9) and of the elevator moving safety assembly (3).

7. The elevator safety system (1) according to claim 6, wherein the evaluation of the slide distance references to a load measurement of the elevator car (5).

8. Method for testing an elevator car (5) braking, comprising following steps:- detecting a sliding motion of the elevator car (5) during the elevator car (5) braking along a guide rail (9) of an elevator (2);- capturing a first image by a camera (7) upon the detection of the sliding motion, wherein the first image indicates a reference object (10) in a shaft (6) of the elevator (2);- capturing a second image of the reference object (10) by the camera (7) when the elevator car (5) is stopped;- determining a slide distance of the elevator car (5) based on the reference object (10) captured in the first and the second image.

9. Method according to claim 8, wherein the size of the reference object (10) is pre-set or known to determine the slide distance of the elevator car (5).

10. Method according to claim 8 or 9, wherein the camera (7) is installed on the roof or under the bottom of the elevator car (5), and the reference object (10) is located under the ceiling or in the pit of the shaft (6) accordingly.

11. Method according to any of claims 8 to 10, wherein the determination of the slide distance of the elevator car (5) is based on speed, deacceleration of the elevator car (5) detected by an elevator moving safety assembly (3), and / or friction due to contact of the guide rail (9) and the elevator moving safety assembly (3).

12. Method according to claim 11, wherein the determination of the slide distance is evaluated to check a contact of the guide rail (9) and of the elevator moving safety assembly (3).

13. Method according to claim 12, wherein the slide distance is evaluated with reference to a load measurement of the elevator car (5).

14. Method according to any of claims 8 to 13, wherein a notification signal is generated if slide distance is greater than a pre-set value.

15. An elevator (2) comprising an elevator safety system (1) according to any of claims 1 to 7 or configured for carrying a method out according to any of claims 8 to 14.

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