METHOD FOR CHECKING A PRESENT FUNCTIONAL STATE OF A BRAKE OF AN ELEVATOR INSTALLATION AND CORRESPONDINGLY CONFIGURED ELEVATOR INSTALLATION

Abstract

A method and brake monitoring device check a current functional state of a brake for an elevator installation traction sheave. The brake has a stationary part and a rotatable part rotationally fixedly coupled to the sheave. A braking mechanism has a displaceable braking element, a biasing mechanism and a release mechanism arranged on the stationary part. The biasing mechanism mechanically biases the braking element with an elastic biasing force toward a braking configuration. The release mechanism has an electrical actuator producing a force acting on the braking element and counteracting the elastic biasing force. The method includes: varying electrical power to the actuator; measuring a release power value that, when exceeded, causes the braking element to switch between the braking configuration and a released configuration; comparing the release power value with a predetermined reference power value; and determining the current functional state of the brake based the comparison result.

Claims

1-15. (canceled)

16. A method for checking a current functional state of a brake of an elevator installation, wherein the elevator installation includes a driving machine driving a traction sheave in rotation, wherein the traction sheave during rotation displaces a cable-type suspension means holding an elevator car, wherein the brake has a stationary part and a rotatable part that is rotationally fixedly coupled to the traction sheave, wherein a braking mechanism is arranged on the stationary part, wherein the braking mechanism has a displaceable braking element, a biasing mechanism and a release mechanism, wherein the braking element is displaceable between a braking configuration, in which the braking element frictionally interacts with the rotatable part of the brake, and a released configuration, in which the braking element does not frictionally interact with the rotatable part of the brake, wherein the biasing mechanism mechanically biases the braking element with an elastic biasing force toward the braking configuration, wherein the release mechanism has an electrical actuator that, depending on an electrical power supplied to the actuator, produces a force that acts on the braking element and counteracts the elastic biasing force produced by the biasing mechanism, the method comprising the steps of: varying the electrical power supplied to the actuator of the release mechanism and measuring a release power value that, when exceeded, causes the braking element to switch between the braking configuration and the released configuration; performing a comparison between the release power value and a predetermined reference power value; and determining a current functional state of the brake based on a result of the performed comparison.

17. The method according to claim 16 including determining the reference power value by at least one of: before the elevator installation is constructed; immediately before the elevator installation is put into operation; specifically for the elevator installation; by a technician on a site where the elevator installation is installed; and as part of a teach-in operation of the elevator installation.

18. The method according to claim 16 wherein the reference power value is a measured power value, the measured power value being determined after construction of the elevator installation by varying the electrical power supplied to the actuator of the release mechanism and determining the measured power value as a power value that, when exceeded, causes the braking element to switch between the braking configuration and the released configuration.

19. The method according to claim 16 including performing the comparison as a comparison between the release power value and a minimum permissible reference power value, and when the release power value is less than the minimum permissible reference power value, determining as the current functional state of the brake that the biasing force generated by the biasing mechanism is less than a minimum permissible biasing force.

20. The method according to claim 16 including performing the comparison as comparison between the release power value and a maximum permissible reference power value, and when the release power value is greater than the maximum permissible reference power value, determining as the current functional state of the brake that the biasing force generated by the biasing mechanism is greater than a maximum permissible biasing force.

21. The method according to claim 16 including initiating the method by an authorized technician during at least one of an installation, a commissioning and a maintenance of the elevator installation.

22. The method according to claim 16 including automatically repeating the method steps at predetermined time intervals.

23. The method according to claim 16 wherein the brake has two braking mechanisms that can be activated separately from one another, and wherein the varying the electrical power supplied to the actuator of the release mechanism is performed on each of the two braking mechanisms at different times.

24. An elevator installation comprising: an elevator car; a driving machine driving a traction sheave in rotation, wherein the traction sheave during the rotation displaces a cable-type suspension means holding the elevator car; a brake having a stationary part and a rotatable part, the rotatable part being rotationally fixedly coupled to the traction sheave; a brake monitoring device; a braking mechanism arranged on the stationary part of the brake, the braking mechanism having a displaceable braking element, a biasing mechanism and a release mechanism; wherein the braking element is displaceable between a braking configuration, in which the braking element frictionally interacts with the rotatable part of the brake, and a released configuration, in which the braking element does not frictionally interact with the rotatable part of the brake; wherein the biasing mechanism mechanically biases the braking element with an elastic biasing force toward the braking configuration; wherein the release mechanism has an electrical actuator that generates a force depending on an electrical power supplied to the actuator, the force acting on the braking element to counteract the elastic biasing force generated by the biasing mechanism; and wherein the brake monitoring device is adapted to carry out or control the method according to claim 16.

25. The elevator installation according to claim 24 wherein the brake has two braking mechanisms that can be activated separately from one another.

26. The elevator installation according to claim 24 wherein the brake includes a brake contact switch that detects a switching of the braking element between the braking configuration and the released configuration.

27. The elevator installation according to claim 24 wherein the actuator of the release mechanism includes an electromagnet that responds to the supplied electrical power to generate the force that acts on the braking element and counteracts the elastic biasing force generated by the biasing mechanism.

28. A brake monitoring device for an elevator installation adapted to carry out or control the method according to claim 16.

29. A computer program product comprising a computer program means including computer readable instructions for performing the method according to claim 16 when the instructions are executed by a programmable brake monitoring device of an elevator installation.

30. A non-transitory computer-readable medium having the computer program product according to claim 29 stored thereon.

Description

DESCRIPTION OF THE DRAWINGS

[0078] FIG. 1 is a sectional view through an elevator installation according to an embodiment of the present invention.

[0079] FIG. 2 is a front view of a brake of an elevator installation according to one embodiment of the present invention.

[0080] The drawings are merely schematic and not to scale. Like reference signs denote like or equivalent features in the various drawings.

DETAILED DESCRIPTION

[0081] FIG. 1 shows an elevator installation 1 which is configured to carry out a method for checking a current functional state of a brake of the elevator installation 1 according to one embodiment of the present invention.

[0082] The elevator installation 1 comprises an elevator car 3, which can be displaced within an elevator shaft 5 using a driving machine 11. For this purpose, the elevator car 3 is held by cable-type suspension means 9 which run over a traction sheave 13 driven by the driving machine 11 and which also hold a counterweight 7.

[0083] A brake 15 is provided on the driving machine 11. The brake 15 is designed to brake a rotation of the traction sheave 13 of the driving machine 11 or to prevent the traction sheave 13 from such a rotation. For this purpose, the brake 15, like the driving machine 11, is controlled by an elevator control 17. In addition, a brake monitoring device 19 is integrated in the elevator control 17, with the aid of which device the current functional state of the brake 15 can be monitored.

[0084] One possible embodiment of a brake 15 to be used in the elevator installation 1 is shown in FIG. 2.

[0085] The brake 15 has a rotatable part 45 and a stationary part 47.

[0086] The rotatable part 45 is rotationally fixedly coupled to the traction sheave 13 to be driven in rotation by the driving machine 11. For example, the rotatable part 45 can be designed as a brake drum 23 which is rotationally fixedly coupled to a drive shaft 21 via which the driving machine 11 drives the traction sheave 13.

[0087] In contrast to the rotatable part 45, the stationary part 47 of the brake 15 cannot rotate together with the traction sheave 13 or with components coupled thereto. Instead, the stationary part 47 is fixed in place, for example on the driving machine 11 or on a part of the elevator installation 1 or of the building that houses the elevator installation 1.

[0088] In the example shown, the stationary part 47 has a braking mechanism 65 which is composed of a displaceable braking element 27, a biasing mechanism 39 and a release mechanism 59.

[0089] In this case, the displaceable braking element 27 is designed as a brake lining 25 which is attached to a brake lever 29. The braking element 27 can be switched between a braking configuration, in which the braking element 27 bears with one surface against the rotatable part 45 of the brake 15 and thus interacts frictionally with it, and a released configuration shown in the drawing, in which configuration the braking element 27 does not interact with the rotating part 45 of the brake 15. For this purpose, the brake lever 29 can be pivoted about a pivot bearing 33 to which one end of this brake lever 29 is attached. In the released configuration, the braking element 27 is spaced apart by a gap 31 from a peripheral surface of the brake drum 23 that forms the rotatable part 45.

[0090] In fact, the brake 15 in the example shown has two displaceable braking elements 27 in the form of two brake linings 25 which are each arranged symmetrically to the drive shaft 21 on a respective brake lever 29. The brake levers 29 and their respective brake linings 25 partially surround the brake drum 23 from opposite sides.

[0091] The biasing mechanism 39 of the brake 15 or the braking mechanism 65 is designed to act on the brake levers 29 with a biasing force 43 directed toward the other brake lever 29. For this purpose, a stationary counter bearing 41 is connected via a rod to a spiral spring 35 acting as an elastic element 37. The spiral spring 35 is supported on an upper part of the associated brake lever 29 and is biased in such a way that the brake lever 29 together with the brake lining 25 provided thereon is acted upon by the biasing force 43 in a direction toward the outer surface of the brake drum 23. Thus, the braking element 27 is pressed with the biasing force 43 toward its braking configuration.

[0092] In order to be able to release the brake 15, i.e., to be able to displace the braking element 27 from its braking configuration to its released configuration, the braking mechanism 65 also has the release mechanism 59.

[0093] In the example shown, the release mechanism 59 has an actuator 55 in the form of an electromagnet 49. The electromagnet 49 comprises a coil 51 and a piston 53 that is displaceable relative to the coil 51. The coil 51 can be supplied with electrical power from a power source 57. Depending on the supplied electrical power, the coil 51 generates a magnetic field which seeks to displace the piston 53. Because on the one hand a housing of the electromagnet 49 holding the coil 51 and on the other hand a push rod connected to the piston 53 interact with respective ends of the two brake levers 29, a suitable power supply to the coil 51 can produce a force 61 which counteracts the biasing force 43.

[0094] Accordingly, the brake 15 can be released by suitably energizing the actuator 55 because its braking elements 27 are removed from the brake drum 23 by pressing the brake levers 29 apart. A brake contact switch 63 can in this case detect a switching of the braking mechanism 65 between the braking configuration and the released configuration.

[0095] On the one hand, the brake monitoring device 19 can determine how much power is currently being supplied by the power source 57 to the actuator 55. On the other hand, the brake monitoring device 19 can exchange signals with the brake contact switch 63 in order to detect the configuration in which the braking elements 27 are currently located.

[0096] In order to obtain information about the current functional state of the brake 15, the electrical power supplied to the actuator 55 of the release mechanism 59 can now be varied in a targeted manner. The electrical power currently supplied is measured, and that power which is measured when the braking elements 27 switch from their braking configuration to their released configuration, or vice versa, is defined as the release power value and stored. See step 100 in FIG. 2.

[0097] The release power value measured in this way is then compared to a predetermined reference power value. It is possible for the reference power value to have been determined beforehand, for example, by preliminary tests or as part of a teach-in operation. See step 101 in FIG. 2. The desired information about the current functional state of the brake 15 can then be derived based on the result of this comparison. See step 102 in FIG. 2.

[0098] In other words, one idea can be seen in measuring the mechanical braking force exerted by the coil springs 35 on the brake 15 by testing or measuring the electric current required either to open the brake or to keep the brake in the open state. In the event that the brake 15 has two braking mechanisms 65, this can be carried out individually for both braking mechanisms 65, because their two channels can be controlled independently of one another. If this is done individually, the test can be performed while one of the braking mechanisms 65 remains closed. Therefore, there is at most a very small risk that the elevator car 3 could move while the method is being carried out.

[0099] A specific design of the test procedure can be implemented as follows: as a precondition it is assumed that a safety circuit within the elevator installation is closed, i.e., all doors are closed. The elevator control then initiates what is known as a dummy trip and activates the inverter, which supplies the driving machine 11 with power. The inverter then starts and possibly biases an electric motor of the driving machine 11 with a torque (this is actually not absolutely necessary for the test, but may be necessary so that the brake can be opened). The electrical voltage applied to the brake 15, and thus also the electrical current, is then gradually increased. When the brake 15 opens, which is signaled in this case, for example, by the brake contact switch 63 changing state, an electrical current supplied to the brake is measured and stored or logged. The brake is then held open for a few seconds by applying the voltage for holding the brake. The voltage applied to the brake is then gradually reduced again. When the brake closes (again detectable based on a state change at the brake contact switch 63), the measured electrical current to the brake is again stored or logged. Finally, the brake is deactivated and the inverter switched off. The stored or logged electrical currents supplied to the brake can then be compared to reference values from which the current functional state of the brake can be derived, and finally the test process can be ended.

[0100] If the test is performed during a commissioning, the measured electrical current needed to open or hold open each brake can be stored as a reference. This reference value can then be used later, for example during maintenance of the elevator installation, as a reference power value for a comparison.

[0101] The test can be initiated manually, for example by man-machine interface activation by an authorized technician. Alternatively or additionally, the test can be carried out automatically, for example during maintenance, and/or repeated automatically at specific time intervals.

[0102] With the test procedure presented here, it can advantageously be found out, for example, whether the elastic element 37, i.e., the spiral spring 35, of the biasing mechanism 39 on the brake 15 is set too soft or too weak. Preferably, this can be detected before the brake fails completely. It can also be determined whether the elastic element 37 or the spiral spring 35 is too firm or strong, or whether the biasing force thereof degrades over time. Furthermore, with the aid of the test procedure proposed here, a commissioning of the elevator installation can be supported, for example in that mechanical adjustment or tightening of the spiral spring 35 is supported or is made verifiable. Overall, the safety of the elevator installation 1 can be improved as a result.

[0103] Finally, it should be noted that terms such as “comprising”, “having”, etc. do not exclude other elements or steps, and terms such as “a” or “an” do not exclude a plurality. Furthermore, it should be noted that features or steps which have been described with reference to one of the above embodiments may also be used in combination with other features or steps of other embodiments described above.

[0104] In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.