Elevator system and method for operating elevator system

Abstract

The invention relates to an elevator system comprising an elevator car (10), a hoist (6) that moves the elevator car in a hoistway, and a hoist brake (1) having one or more brake pads (3) that move to a braking position at which the one or more brake pads (3) contact a braking surface (4) to reduce the speed of the elevator car (10) when activated for braking. In order to provide a solution to ensure reliable operation of the brake, the elevator system comprises a temperature sensor (18) providing a signal indicative of the temperature of the brake surface (4), and a monitoring unit (13) monitoring the operation of the hoist brake (1), the monitoring unit receiving a signal indicative of the temperature, and is configured to indicate a brake failure when the indicated temperature has reached an upper limit value or increased beyond a limit value during operation of the elevator.

Description

Technical Field

[0001] The present invention relates to an elevator system and more particularly to a solution for ensuring reliable operation of a brake. Background Art

[0002] An elevator is previously known which has a traction machine that moves the elevator car. In order to ensure that the elevator car can stop and remain stationary when required, the traction machine is provided with a traction machine brake. The traction machine brake has one or more brake pads that contact a braking surface to reduce the speed of the elevator car when activated to brake.

[0003] A challenge with known elevators is to ensure that the traction machine brake works as expected. Preferably, there is minimal manual inspection to save costs. To achieve this, previously known elevators are provided with a brake switch that changes state when the brake is open.

[0004] However, a problem with the known solution is that the brake switch does not always operate in a reliable manner. For example, when the brake is turned on to allow the elevator car to move, the brake pads may move sufficiently to cause the brake switch to change state, although the brakes are not yet fully turned on. Due to this, the brake switch may be in a state indicating that the brakes are released, but in reality, the brake pads still contact the braking surface to a certain extent, so that braking forces still occur during elevator operation. This undesired braking force is sometimes called brake drag, and it increases the risk of failure in the brake. Summary of the invention

[0005] The object of the present invention is to solve the above mentioned drawbacks and to provide a solution which ensures reliable operation of the brake. This object can be achieved by an elevator system according to independent claim 1 and a method according to independent claim 11.

[0006] By utilizing a temperature sensor providing a signal indicative of the temperature of a braking surface which is in contact with one or more brake pads of the brake during braking, information about a braking malfunction of the brake can be obtained quickly and reliably. In particular, if a braking force is present during elevator operation, the temperature of the braking surface will change rapidly.

[0007] Preferred embodiments of the invention are disclosed in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In the following, the present invention will be described in more detail by way of examples and with reference to the accompanying drawings, in which:

[0009] Figure 1 shows the traction machine brake, and

[0010] Figure 2 An elevator system is shown. DETAILED DESCRIPTION

[0011] exist Figure 1 In the example shown, the traction machine brake 1 is provided with a disc brake, but the present invention can also be used in combination with other types of brakes.

[0012] The traction machine brake 1 comprises two brake units 2 with corresponding brake pads 3, which are moved to a braking position in which the brake pads 3 contact a braking surface 4 to reduce the speed of the elevator car when activated for braking. In addition, the brake unit can be used to keep the elevator car stationary. In this example, the braking surface is the surface of a disk that rotates with a traction sheave 5 during elevator operation. The elevator car is suspended by ropes that contact the traction sheave 5 so that when the traction sheave 5 rotates, the ropes and the elevator car move in the hoistway. Therefore, when the brake pads 3 contact the braking surface 4, the rotation speed of the braking surface 4 and the traction sheave is slowed down. The brake pads 3 can be arranged on both sides of the disk, in which case the disk has two braking surfaces.

[0013] exist Figure 1 In the example of , the hoisting machine brake 1 has been integrated with the hoisting machine 6, although this is not necessary in all embodiments. The housing 7 of the hoisting machine 6 contains the stator of the motor included in the hoisting machine to rotate the traction sheave 5 during the operation of the elevator. With this solution, the hoisting machine 6 and the hoisting machine brake 1 can be implemented as a single compact device. However, optionally, the motor of the hoisting machine is connected to a traction sheave with a relatively long shaft, and the hoisting machine brake is implemented as a separate component between the motor and the traction sheave. In this case, the outer surface of the shaft can be used as a braking surface so that the brake pad directly contacts the surface of the shaft during braking. Alternatively, a brake disc can be attached to rotate with the shaft so that the surface of the brake disc is used as a braking surface, which is in contact with the brake pad during braking. Therefore, for example, there are several different solutions to implement a hoisting machine brake with a disc brake or a shoe brake.

[0014] In order to ensure reliable operation of the elevator system, the traction machine brake 1 is provided with temperature sensors 8, 18 which provide a signal indicative of the temperature of the braking surface 4. Figure 1 In the embodiment shown, two alternative positions of such a temperature sensor have been shown. However, in many embodiments, it is sufficient to provide a temperature sensor at only one of the positions shown.

[0015] A first location for the temperature sensor 8 is on the front side of the braking surface 4. In this respect, the front side is the same side of the braking surface where the traction sheave 5 is located. A second possible location for the temperature sensor 18 is on the back side of the braking surface 4, in other words, on the opposite side compared to the traction sheave 5. In this case, the temperature sensor 18 can be attached to Figure 1 The stator or housing 7 of the traction machine 6 in the embodiment.

[0016] In some embodiments, the brake pad 3 may be provided on only one side of the disc with the braking surface 4, with the sensors 8, 18 being located on the opposite side of the disc compared to the brake pad. Also in this case, the sensor may provide a signal indicative of the braking surface temperature by measuring the temperature of the entire disc from the sensor side.

[0017] Wherever the temperature sensors 8, 18 are located, the temperature sensors are preferably implemented as non-contact sensors, such as infrared sensors directly facing the braking surface 4. In this way, a more reliable temperature measurement can be obtained, since there is no need to attach the sensors directly to the parts that generate heat and vibrations during braking, and where the stress on the sensors over time due to this would be significant. Instead, the sensors can be located at a small distance from these parts, which reduces the risk of failure due to stress. Such non-contact sensors can also be retrofitted to old elevator systems without requiring significant changes to the existing traction machine or traction machine brake.

[0018] It is also advantageous that the sensors 8, 18 provide a signal indicative of the temperature of the braking surface 4 in particular, since friction during braking directly increases the temperature of the braking surface. Thus, temperature changes indicative of a possible malfunction of the brake can be most quickly and reliably detected directly from the braking surface.

[0019] Figure 2 An elevator system is shown in which a combination of Figure 1 An elevator brake is described and in which the method according to the invention can be implemented.

[0020] Figure 2 Ropes 9 are shown which move the elevator car 10 and the counterweight 11 in the hoistway 12. The hoisting machine 6 and the hoisting machine brake 1 are fixedly suspended in the hoistway 12, regardless of whether they are realized as a single component or as separate components. The ropes 9 extend around the traction sheave 5.

[0021] The monitoring unit 13 monitors the operation of the traction machine brake 1 by receiving a signal indicating the temperature of the brake surface from the temperature sensor 18. The monitoring unit 13 can be implemented by means of a circuit or by means of a combination of circuits and software, such as by means of a processor running a program code stored in a memory. In the example shown, it is assumed, as an example, that the monitoring unit 13 is part of an elevator controller 14, which controls the operation of one or more elevator cars installed, for example, in a building.

[0022] The monitoring unit 13 is configured to indicate a brake failure if the signal provided by the temperature sensors 8, 18 indicates that the temperature has reached an upper limit value or has increased beyond a limit value during the elevator operation of the elevator car 10. An alternative is that the monitoring unit monitors the temperature, in particular immediately after the start of the elevator operation or within a predetermined time period, for example during the acceleration phase of the elevator car. At this stage, the traction machine brake 1 should have been released so that practically no braking force remains. However, in the event of a failure, all brake pads 3 may not have moved a sufficient distance from the braking surface 4. If so, this will cause friction and the temperature of the braking surface 4 will increase during the elevator operation. The monitoring unit 13 can quickly detect this increase in temperature and can indicate a brake failure as soon as the upper limit is reached or the temperature increases beyond the limit.

[0023] A brake fault may be indicated locally at the elevator installation site by the monitoring unit 13. However, in the example shown, it is assumed by way of example that the monitoring unit 13 comprises an interface 16 provided by the elevator controller 14 to the communication system 15.

[0024] exist Figure 2 In the example of , it is assumed that the interface 16 provides a connection to a base station 17 of a cellular communication system 15, in other words, as a wireless interface, although in other embodiments, a wired solution is possible. Via this interface 16, a message indicating a brake fault can be sent to a predetermined receiver at a remote location. The term remote location refers to another location other than the installation site of the elevator car 10. The receiver can be implemented as a server computer 19 having a memory and running software, which receives the brake fault indication and stores it in a memory for access by maintenance personnel. An alternative is also to use a cloud service, which may be common to several elevators arranged in different geographical locations. The stored fault indication can be accessed by maintenance personnel via a wireless terminal 20 or a wired terminal 21. Alternatively or additionally, the monitoring unit 13 can be configured to trigger the fault indication to be transmitted directly to one or more terminals 20, 21.

[0025] When an indication of a brake failure has been made, the elevator controller 14 of the elevator system may be configured to prevent further operation of the elevator car 10 in question. In this case, further elevator operation may be allowed only after maintenance personnel have visited the installation site of the elevator car 10. Alternatively, the elevator controller 14 may obtain a temperature indication from the monitoring unit 13 and once the indicated temperature has returned to the permitted range (e.g. reached a lower limit value), the elevator controller 14 again allows the use of the elevator car 10 in question, since the traction machine brake has cooled down.

[0026] It should be understood that the above description and the accompanying drawings are only intended to illustrate the present invention. It is obvious to those skilled in the art that the present invention can be changed and modified without departing from the scope of the present invention.

Claims

1. An elevator system, include: Elevator car (10), a traction machine (6) which moves the elevator car in the hoistway, and A hoisting machine brake (1) having one or more brake pads (3) which are moved into a braking position in which the one or more brake pads (3) contact a braking surface (4) to reduce the speed of the elevator car (10) or to keep the elevator car (10) stationary when activated for braking, Characterized in that the elevator system comprises: a temperature sensor (8, 18) providing a signal indicative of the temperature of the braking surface (4), and A monitoring unit (13) monitors the operation of the traction machine brake (1), the monitoring unit receiving a signal indicative of the temperature and configured to indicate a brake failure when the indicated temperature has reached an upper limit value or increased beyond a limit value during elevator operation.

2. The elevator system according to claim 1, in, The monitoring unit (13) is configured to indicate the brake failure when the indicated temperature has reached the upper limit value or increases beyond the limit value immediately after the elevator operation has started or within a predetermined time period.

3. Elevator system according to claim 1 or 2, wherein the temperature sensor (8, 18) is a non-contact sensor.

4. The elevator system according to claim 1 or 2, wherein the temperature sensor (8, 18) is an infrared sensor.

5. The elevator system according to any one of claims 1 to 4, in, The temperature sensor (8) is attached to a stationary part of the hoisting machine or traction machine brake (1) to provide an indication of the temperature of a braking surface (4) rotating relative to the stationary part during elevator operation.

6. The elevator system according to any one of claims 1 to 5, in, The temperature sensor (18) is arranged on the stator or the housing (7) of the traction machine (6).

7. The elevator system according to any one of claims 1 to 6, in, The monitoring unit (13) comprises an interface (16) to a communication system (15) and indicates the brake fault by sending a message to a predetermined receiver (19, 20, 21) via the communication system (15).

8. An elevator system according to any one of claims 1 to 7, wherein the elevator system is configured to prevent further elevator operation of the elevator car (10) in response to an indication of a brake failure from the monitoring unit (13).

9. The elevator system of claim 8, wherein the elevator system is configured to resume elevator operation when the indicated temperature has returned to an allowable range.

10. An elevator system according to any one of claims 1 to 8, wherein the elevator system is configured to prevent further elevator operation of the elevator car (10) in response to an indication of a brake failure from the monitoring unit (13) until the indicated temperature has reached a lower limit value.

11. A method of operating an elevator, It is characterized in that The method comprises: obtaining a signal from a temperature sensor (8, 18) which provides an indication of the temperature of a braking surface (4) of a traction machine brake (1), and When the indicated temperature has reached an upper limit value or increases beyond a limit value during elevator operation, a brake failure is detected.

12. The method according to claim 11, include: Use of the elevator is prevented until a signal obtained from the temperature sensor (8, 18) indicates that the temperature has reached a lower limit value.

13. The method according to claim 11 or 12, include: A message indicating the brake fault is sent via a communication system (15) to a predetermined receiver (19, 20, 21).

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