Method for brake reconditioning for a friction brake of a drive system having an electronically commutated electric motor with integrated control

Abstract

The present invention relates to a method for brake reconditioning for a friction brake of a drive system having an electronically commutated electric motor, which comprises a rotor and a stator, wherein the friction brake is coupled to the rotor for braking the rotor, wherein the method involves a brake reconditioning of the friction brake and a testing of the braking function of the friction brake for determining a current braking force of the friction brake, wherein the brake reconditioning and the testing are controlled by a controller of the drive system, which is configured for open-loop and closed-loop control of the movement of the rotor and the friction brake. According to the invention, the electronically commutated electric motor comprises the controller as an integrated controller, and the brake reconditioning and the testing of the brake function are carried out together at regular intervals, wherein the testing is carried out after the brake reconditioning in order to verify that the current braking force is above a predefined minimum braking force.

Description

[0001] Method for brake reconditioning of a friction brake of a drive system with electronically commutated electric motor with integrated control

[0002] The present invention relates to a method for refreshing the brakes of a friction brake of a drive system with an electronically commutated electric motor comprising a rotor and a stator, wherein the friction brake is coupled to the rotor for braking the rotor, according to the preamble of claim 1.

[0003] A generic method comprises a brake refresh of the friction brake and a test of the braking function of the friction brake to determine an instantaneous braking force of the friction brake, wherein the brake refresh and the testing are controlled by a control of the drive system which is set up to control and regulate the movement of the rotor and the friction brake.

[0004] Such procedures may be necessary because the braking performance can be impaired depending on the operating conditions and the age of the friction brake. Brake refurbishment can then increase the braking performance again, for example by removing linings or contaminants from the friction surface of the friction brake.

[0005] Such methods are known in the prior art. For example, industrial drive controllers are used for control purposes, which are then coupled to the electronically commutated electric motor and the friction brake via signal lines, controlling and regulating them. The corresponding drive systems designed for this generic method require a relatively large amount of installation space in the respective systems in which the drive system is integrated.

[0006] In addition, the degree of automation of the known methods is low.

[0007] The object of the present invention is to provide an improved method of the generic type that solves the problems mentioned above.

[0008] The problem is solved by the features of independent claim 1. Accordingly, a solution to the problem according to the invention exists if the electronically commutated electric motor comprises the control unit as an integrated control unit, and if the brake refresh and the testing of the brake function are performed together at regular intervals, wherein the testing is carried out after the brake refresh to verify that the instantaneous braking force after the brake refresh is above a predetermined minimum braking force. According to the invention, the fact that the electronically commutated electric motor comprises an integrated control unit means that the integrated control unit is permanently installed in or permanently connected to the electronically commutated electric motor and is thus part of the electric motor.For example, the integrated control unit can be located in the electric motor housing or in an additional housing adjacent to and firmly connected to the electric motor housing. In this way, the electric motor not only generates the mechanical movement but also controls and regulates this movement. Furthermore, according to the invention, this integrated control unit is configured to control the method according to the invention.

[0009] According to the invention, a brake refresh of the friction brake comprises at least a defined closing of the friction brake while the rotor is driven, thereby removing deposits or contaminants from the friction surface. The method is carried out outside of normal operation of the drive system.

[0010] By designing the control system as an integrated control system for the electronically commutated electric motor, the method according to the invention is suitable for very compact drive systems.

[0011] In addition, the process can be automated by regularly performing brake refreshes and brake function tests. For example, the process can be carried out automatically outside of normal operation of the drive system.

[0012] Advantageous embodiments of the present invention are the subject of the dependent claims.

[0013] In a preferred embodiment of the present invention, the friction brake is a holding brake. Holding brakes require more frequent brake reconditioning due to the lower number of frictional braking operations. The method for reconditioning the friction brake is therefore advantageous for a holding brake as a friction brake.

[0014] In a further preferred embodiment of the present invention, the regular interval is a time interval, wherein the time interval is preferably between one and six weeks, particularly preferably between three and five, and more preferably four weeks. Surprisingly, it has been found that such regular time intervals are particularly suitable for the brake refreshing method.

[0015] In a further preferred embodiment of the present invention, the specified minimum braking force is 40 to 90%, preferably 50 to 75%, and more preferably 60% of the nominal braking force of the friction brake. The nominal braking force of the friction brake is the braking force of a new, functionally sound friction brake during testing.

[0016] In a further preferred embodiment of the present invention, the brake refreshing process comprises a brake refreshing sequence consisting of the following steps: a1. Deactivation of the friction brake and acceleration of the rotor to a predetermined rotational speed, b1. Activation of the friction brake by means of a braking operation while maintaining rotation and applying a first predetermined torque, c1. Measurement of a brake friction distance and comparison of the brake friction distance with a predetermined minimum brake friction distance, wherein steps a1 to c1 are repeated until a predetermined maximum number of iterations is reached in which the brake friction distance is greater than the predetermined minimum brake friction distance. The brake refreshing sequence provides an efficient means of removing deposits or contaminants from the friction surface of the friction brake.The brake friction distance can be measured, for example, as the rotation angle of the rotor between the start and end points of the braking process. Specifying a minimum brake friction distance ensures that any deposits or contaminants on the friction surface of the friction brake are adequately removed.

[0017] Preferably, the specified rotational speed is less than or equal to 1500 rpm, and more preferably less than or equal to 500 rpm. Such specified rotational speeds have surprisingly proven to be advantageous.

[0018] Preferably, the specified maximum number of cycles in which the braking friction distance exceeds the specified minimum braking friction distance is three to ten, more preferably four to six, and particularly preferably five. The time span of a cycle is preferably less than 0.7 s, and particularly preferably less than 0.5 s.

[0019] In a further preferred embodiment of the present invention, testing the braking function comprises a sequence for testing the braking function, which includes the following steps: a2. Activation of the friction brake, b2. Application of a second predetermined torque to the rotor for a predetermined time period, c2. Measurement of a rotational distance of the rotor and comparison of the rotational distance with a predetermined rotational distance corresponding to the rotational distance at the predetermined minimum braking force.

[0020] The brake function test sequence is an efficient way to verify the brake function and determine whether a brake refresh was successful or if an additional brake refresh is required. The rotation distance can be measured, for example, as the rotor's angle of rotation between a position before step b2 and after step b2.

[0021] In a particularly preferred embodiment, the rotational distance corresponding to the specified minimum braking force is zero or nearly zero. In this case, the test is successful if the brake holds the rotor at minimum braking force. If the minimum braking force is insufficient to hold the rotor, rotation occurs and a rotational distance is measured. In this case, the test is unsuccessful.

[0022] Preferably, the specified time period is five to fifteen seconds.

[0023] In a preferred embodiment of the invention, a response time for activating the friction brake is tested. This ensures that the friction brake can be activated within a predetermined time. After the response time has elapsed, a predetermined minimum braking force must be applied to the rotor.

[0024] It is also preferable to abort step b2 if the rotational distance exceeds the specified rotational distance during the specified time period. This prevents excessive rotation of the rotor if the friction brake force is insufficient.

[0025] In a preferred embodiment of the present invention, the brake reconditioning and testing are repeated until the instantaneous braking force exceeds the predetermined braking force during testing or a maximum number of repetitions of the entire brake reconditioning process is reached, the maximum number of repetitions preferably being five and particularly preferably three. This allows for improved automation of the brake reconditioning process. The invention also presents a drive system with a friction brake and an electronically commutated electric motor comprising a rotor, a stator, and an integrated control unit, wherein the friction brake is coupled to the rotor for braking the rotor, and wherein the drive system is configured to carry out the brake reconditioning process according to one of the embodiments described above.

[0026] In a preferred embodiment of the drive system, the rotor, the stator, and the integrated control unit are arranged in a common housing. This simplifies the integration of the drive system into the system to be driven.

[0027] In another preferred embodiment of the drive system, the integrated control is arranged within a region which has a maximum extent extending from an axial end of the electric motor, which includes rotor and stator, to a maximum of 2.5 times, preferably 2 times, the axial length of the electric motor.

[0028] In an alternative embodiment, the integrated control unit is arranged within a region whose maximum extent, extending from an outer surface of the electric motor, is at most twice, preferably 1.5 times, the radius of the outer surface of the electric motor. This results in a particularly compact electronically commutated electric motor.

[0029] In another preferred embodiment, the drive system additionally includes a gearbox.

[0030] Furthermore, the invention includes the use of the drive system according to one of the previously described embodiments as a wheel drive. Since the installation space and accessibility of wheel drives are often very limited, the drive system according to the invention is particularly suitable for use as a wheel drive.

[0031] Preferably, the invention includes using the drive system according to one of the previously described embodiments as a drive for applications with a vertical direction of movement, in particular lifting drives for or along a vertical axis. The use of the drive system according to the invention is particularly advantageous for drives for or along vertical axes that have a vertical, gravity-loaded direction of movement and therefore require a holding brake. The drive system can be designed as a wheel or gear drive.

[0032] Furthermore, the invention encompasses the use of the drive system according to one of the previously described embodiments as an articulated drive in robotics. Since the installation space and accessibility of articulated drives in robotics are often very limited, the drive system is particularly suitable for use as an articulated drive in robotics.

[0033] An embodiment of the method according to the invention and an exemplary embodiment of a drive system according to the invention are explained in more detail below with reference to drawings.

[0034] The drawings show:

[0035] Figure 1 shows a schematic of an embodiment of the brake reconditioning method according to the invention,

[0036] Figure 2 shows a diagram of the brake refresh sequence.

[0037] Figure 3 shows a diagram of the sequence for testing the brake function, and

[0038] Figure 4 shows a schematic sketch of an embodiment of a drive system according to the invention, which is set up to carry out the embodiment of the brake refreshing method according to the invention.

[0039] Figure 5 shows a schematic sketch of a second embodiment of a drive system according to the invention, which is set up to carry out the embodiment of the brake refreshing method according to the invention.

[0040] Figure 6 shows a graph of the response behavior of the friction brake.

[0041] In the following explanations, identical parts are designated by the same reference numerals. If a figure contains reference numerals that are not further explained in the corresponding figure description, reference is made to preceding or subsequent figure descriptions.

[0042] Figure 1 shows a schematic of an embodiment of a method according to the invention for reconditioning a friction brake 5 of a drive system 1 with an electronically commutated electric motor 2, which comprises a rotor and a stator, wherein the friction brake 5 is coupled to the rotor for braking the rotor. The method comprises a brake reconditioning of the friction brake, which includes a brake reconditioning sequence BA, and a testing of the braking function of the friction brake, which includes a braking function test sequence T, to determine an instantaneous braking force of the friction brake. The testing and the brake reconditioning are controlled by a control unit of the drive system, which is configured to control and regulate the movement of the rotor and the friction brake. It is provided that the electronically commutated electric motor 2 includes the control unit as an integrated controller 4.Furthermore, brake refresh and testing are performed automatically at regular intervals. Brake refresh can occur, for example, at a certain time interval since the last brake refresh. Brake refresh can also occur, for example, after a certain number of braking cycles or after a reduction in braking performance is detected, such as after falling below a minimum braking force. Accordingly, the schematic of the embodiment of the method shown in Figure 1 is executed again after the regular time interval. Testing is then performed using the test sequence T after the brake refresh, followed by the brake refresh sequence BA, to verify that the current braking force is above a predefined minimum braking force.As shown in Figure 1, the brake refresh and testing is repeated until the instantaneous braking force is above the specified braking force during testing or a maximum number of brake refresh repetitions is reached, the maximum number of repetitions preferably being 3.

[0043] Figure 2 shows a schematic of the brake refresh sequence BA. The brake refresh sequence BA comprises the following steps: a1. Deactivation of the friction brake 5 and acceleration of the rotor to a predetermined rotational speed, b1. Activation of the friction brake 5 by means of a braking process while maintaining rotation and applying a first predetermined torque, c1. Measurement of a brake friction distance and comparison of the brake friction distance with a predetermined minimum brake friction distance, whereby steps a1. to c1. are repeated until a predetermined maximum number of iterations is reached in which the brake friction distance is greater than the predetermined minimum brake friction distance. The brake friction distance can, for example, be measured as the rotation angle of the rotor between a start time and an end time of the braking process.By specifying a minimum braking friction distance, it is ensured that any deposits or contaminants on the friction surface of the friction brake are adequately removed. According to this embodiment, the specified rotational speed is less than 1500 rpm, and the specified maximum number of cycles in which the braking friction distance exceeds the specified minimum braking friction distance is 4 to 6. The duration of a cycle is less than 0.5 s. Figure 3 shows a schematic of the sequence for testing the braking function T of the friction brake 5.

[0044] The sequence for testing the braking function T comprises the following steps: a2. Activation of the friction brake 5, b2. Application of a second predetermined torque to the rotor for a predetermined time period, c2. Measurement of a rotational distance of the rotor and comparison of the rotational distance with a predetermined rotational distance that corresponds to the rotational distance at the predetermined minimum braking force.

[0045] This allows for an efficient determination, through testing the braking function using the test sequence T, of whether the friction brake requires a brake refresh or whether a brake refresh was successful, as it is determined whether the instantaneous braking force is below or above the predefined minimum braking force. According to the embodiment, the predefined minimum braking force is 60% of the nominal braking force of the friction brake. Preferably, rotation of the rotor occurs only when a predefined minimum braking force is undershot, and a rotational distance is measured. Thus, by simply detecting rotation and measuring the corresponding rotational distance, it can be determined whether the test was successful or not. The test is successful if the brake essentially holds the rotor stationary at the predefined minimum braking force, and consequently, no or a very small rotational distance is measured.

[0046] Figures 4 and 5 show schematic sketches of two embodiments of a drive system 1 according to the invention, which is configured to carry out the embodiment of the brake reconditioning method described above. The drive system 1 comprises an electronically commutated electric motor 2, which includes a component 3 consisting of a rotor and a stator. The component 3 can, for example, drive a shaft 6. The drive system also includes a friction brake 5, which is coupled to the rotor for braking. Furthermore, the electronically commutated electric motor includes an integrated controller 4. This integrated controller 4 is configured to control and regulate the movement of the rotor and the friction brake 5. According to the embodiments shown in Figures 4 and 5, the friction brake 5 can be configured as a holding brake.Furthermore, component 3 and the integrated control unit 4 can be arranged in a common housing. The integrated control unit 4 can be located in a housing part 8 that is directly adjacent to and connected with the electric motor housing 7. Figure 6 shows a graph of the response behavior of the friction brake 5. The braking force curve, represented as a solid line, begins near zero on the Y-axis on the left side of the graph at t=0, while the voltage, represented as a dotted line, starts at a high level on the Y-axis. Thus, a voltage Ubvent is initially applied to the friction brake 5, and the friction brake 5 is released. The rotor travels a rotational distance, which can be measured as an angle of rotation (p). The angle of rotation (p) is represented by the rising, dashed curve. When the voltage Ubvent drops, the friction brake 5 closes, and the rotor comes to a standstill.The response time tbcon (Brake connect) of the friction brake 5 is an important parameter, especially in safety-relevant drive systems 1, to prevent damage to equipment or persons. A good response time for the friction brake 5 is less than 100 ms, preferably less than 75 ms.

[0047] It is also possible, for example, with a holding brake that is not rotating at the start of the test, to allow the voltage Ubvent to drop and thus activate the friction brake 5. After the response time has elapsed, a torque is applied to the rotor to check whether it can be rotated; the rotation angle (p) of the rotor can then be evaluated.

[0048] Figure 6 also shows the reaction time when releasing the friction brake 5 tbvent (brake ventilation, brake open). A good reaction time for releasing the friction brake 5 is also less than 100 ms, preferably less than 75 ms.

[0049] In exemplary embodiments, the response time for activating the friction brake 5 can thus be tested. The response time of the friction brake 5 can be recorded, measured, and processed. By processing the response time and comparing it with a predefined maximum response time, conclusions can be drawn about the functionality of the friction brake 5. It is also possible, however, to wait for the response time after activating the friction brake 5, then apply a torque and test the braking force of the friction brake 5. This allows verification of whether the friction brake 5 applies the predefined minimum braking force after the response time has elapsed.

Claims

Claims 1. A method for reconditioning the friction brake (5) of a drive system (1) with an electronically commutated electric motor (2) comprising a rotor and a stator, wherein the friction brake (5) is coupled to the rotor for braking the rotor, the method comprising reconditioning the friction brake (5) and testing the braking function of the friction brake (5) to determine an instantaneous braking force of the friction brake (5), wherein the reconditioning and testing are controlled by a control unit of the drive system (1) configured to control and regulate the movement of the rotor and the friction brake (5), characterized in that the electronically commutated electric motor (2) includes the control unit as an integrated control unit (4) and the reconditioning and testing of the braking function are performed together at regular intervals, wherein the testing is carried out after the reconditioning.to verify that the current braking force after brake regeneration is above a predetermined minimum braking force.

2. Method according to claim 1, wherein the friction brake (5) is a holding brake.

3. Method according to claim 1 or 2, wherein the regular interval is a time interval, wherein the time interval is preferably between one and six weeks, particularly preferably between three and five, and more preferably four weeks.

4. Method according to any one of claims 1 to 3, wherein the specified minimum braking force is 40 to 90%, preferably 50 to 75%, more preferably 60%, of a nominal braking force of the friction brake (5).

5. A method according to any one of claims 1 to 4, wherein the brake refresh comprises a brake refresh sequence (BFS) comprising the following steps: a1. Deactivation of the friction brake (5) and acceleration of the rotor to a predetermined rotational speed, b1. Activation of the friction brake (5) by means of a braking process while maintaining rotation and applying a first predetermined torque, c1. Measurement of a brake friction distance and comparison of the brake friction distance with a predetermined minimum brake friction distance. where steps a1 to c1 are repeated until a predetermined maximum number of trials is reached in which the braking friction distance is greater than the predetermined minimum braking friction distance.

6. Method according to claim 5, wherein the predetermined rotational speed is less than or equal to 1500 rpm, preferably less than or equal to 500 rpm.

7. Method according to claim 5 or 6, wherein the predetermined maximum number of cycles in which the braking friction distance is greater than the predetermined minimum braking friction distance is three to ten, preferably four to six, more preferably five.

8. Method according to any one of claims 1 to 7, wherein the testing of the braking function comprises a sequence for testing the braking function (T) comprising the following steps: a2. Activation of the friction brake (5), b2. Application of a second predetermined torque to the rotor for a predetermined time period, c2. Measurement of a rotational distance of the rotor and comparison of the rotational distance with a predetermined rotational distance corresponding to the rotational distance at the predetermined minimum braking force.

9. The method according to claim 8, wherein the specified time interval is from 5 to 15 seconds.

10. Method according to claims 8 or 9, wherein a response time for activating the friction brake (5) is tested.

11. Method according to claims 8 to 10, wherein step b2. is aborted if the rotation distance exceeds the predetermined rotation distance during the predetermined time period.

12. Method according to any one of claims 1 to 4, wherein the brake refresh and testing are repeated until the instantaneous braking force is above the predetermined braking force during testing or a maximum number of repetitions of the brake refresh is reached, wherein the maximum number of repetitions is preferably three.

13. Drive system (1) with a friction brake (5) and an electronically commutated electric motor (2) comprising a rotor, a stator and an integrated control (4), wherein the friction brake (5) is coupled to the rotor for braking the rotor, characterized in that the drive system (1) is configured to carry out the method according to claims 1 to 12.

14. Use of the drive system (1) according to claim 13 as a wheel drive.

15. Use of the drive system (1) according to claim 13 as a drive for applications with a vertical direction of movement, in particular lifting drives for or along a vertical axis.

16. Use of the drive system (1) according to claim 13 as a joint drive in robotics.

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