Brake drive device for driving mechanical brake device

Abstract

This brake drive device comprises: a switch that releases a brake by means of a mechanical brake device by performing an on-operation for causing a current to flow to the mechanical brake device, and actuates the brake by means of the mechanical brake device by performing an off-operation for causing a current not to flow to the mechanical brake device; and an energy storage circuit that is electrically connected to the mechanical brake device and stores energy. The energy for restricting a current change when the brake is released by means of the mechanical brake device is supplied to the mechanical brake device from the energy storage circuit.

Description

Brake drive device that drives a mechanical brake device

[0001] The present disclosure relates to a brake driving device that drives a mechanical brake device.

[0002] Mechanical brake devices are widely used in motor drive devices that drive motors in machines such as industrial robots and machine tools to brake rotating motors or to fix stopped motors so that they do not rotate. A switch is connected between the brake coil of the mechanical brake device and the power supply. When the switch is turned on, current flows from the power supply to the brake coil, releasing the brake applied by the mechanical brake device. When the switch is turned off, current is prevented from flowing from the power supply to the brake coil, thereby applying the brake to the mechanical brake device.

[0003] JP 2013-248946 A JP 2011-195287 A JP 2020-029877 A

[0004] While a mechanical brake device is in a brake-released state, a test pulse is periodically applied to momentarily turn off the switch between the brake coil and the power source in order to monitor whether there is a fault in the switch. When a test pulse is applied to the switch in the brake-released state, a period occurs in which no current flows through the brake coil, which can cause the brake to malfunction. Therefore, a brake drive device that can prevent the brake from malfunctioning in the brake-released state is desired.

[0005] According to one aspect of the present disclosure, the brake drive device includes a switch that releases the brake provided by the mechanical brake device by turning on the switch to allow current to flow to the mechanical brake device, and activates the brake provided by the mechanical brake device by turning off the switch to prevent current from flowing to the mechanical brake device, and an energy storage circuit that is electrically connected to the mechanical brake device and stores energy, and supplies energy from the energy storage circuit to the mechanical brake device to suppress changes in current when the brake provided by the mechanical brake device is released.

[0006] FIG. 1 is a circuit diagram showing a brake drive device according to a first embodiment of the present disclosure. FIG. 2 is a cross-sectional view showing the structure of a mechanical brake device controlled by the brake drive devices according to the first and second embodiments of the present disclosure, showing a state in which a brake is applied to a motor. FIG. 3 is a cross-sectional view showing the structure of a mechanical brake device controlled by the brake drive devices according to the first and second embodiments of the present disclosure, showing a state in which a brake is released from the motor. FIG. 4 is a circuit diagram showing a brake drive device according to a second embodiment of the present disclosure. FIG. 5 is a timing chart illustrating waveforms in the brake drive devices according to the first and second embodiments of the present disclosure. FIG. 6 is a timing chart showing waveforms when the brake drive devices according to the first and second embodiments of the present disclosure are actually operated. FIG. 7 is a timing chart showing waveforms when a conventional brake drive device without an energy storage circuit is actually operated.

[0007] A brake drive device that drives a mechanical brake device according to an embodiment will be described below with reference to the drawings. In the following description, components having the same or similar functions will be assigned the same reference numerals. Duplicate descriptions of these components may be omitted. Here, "on" of a switch means that the electrical circuit in which the switch is provided is closed; that is, when a switch is turned on, the electrical circuit in which the switch is provided is connected and placed in a closed state. Furthermore, "off" of a switch means that the electrical circuit in which the switch is provided is opened; that is, when a switch is turned off, the electrical circuit in which the switch is provided is interrupted and placed in an open state.

[0008] <Configuration of Brake Drive Device According to First Embodiment> FIG. 1 is a circuit diagram showing a brake drive device according to a first embodiment of the present disclosure.

[0009] The mechanical brake device 2 controlled by the brake drive device 1 according to the first embodiment of the present disclosure is a non-excitation operated brake device that activates the brake when the brake coil 25 is not excited and no voltage is applied to it, and releases the brake when the brake coil 25 is excited and voltage is applied to it.

[0010] Prior to describing the brake drive device 1 according to the first embodiment of the present disclosure, the structure of a mechanical brake device 2 will be described with reference to Figures 2 and 3. Figure 2 is a cross-sectional view showing the structure of a mechanical brake device controlled by the brake drive devices according to the first and second embodiments of the present disclosure, illustrating a state in which a brake is applied to a motor. Figure 3 is a cross-sectional view showing the structure of a mechanical brake device controlled by the brake drive devices according to the first and second embodiments of the present disclosure, illustrating a state in which the brake is released from the motor. The mechanical brake device 2 shown in Figures 2 and 3 is applicable to the first and second embodiments.

[0011] As shown in FIGS. 2 and 3 , in the mechanical brake device 2, a friction plate 21 is disposed between an armature 22 and an end plate 23. A hub 32 is spline-connected to the friction plate 21. The hub 32 and the motor shaft 31 are integrated, for example, by shrink fitting, so that the friction plate 21 rotates in conjunction with the rotation of the motor shaft 31. The end plate 23 and a spacer 27 are connected with bolts 28, and the armature 22 is connected to the spacer 27 so as to be movable toward and away from the friction plate 21. A spring 24 and a brake coil 25 are provided within a core 26. As shown in FIG. 2 , in a non-excited state in which no voltage is applied to the brake coil 25, the armature 22 is pressed firmly against the friction plate 21 by the elastic force of the spring 24, and the friction plate 21 is sandwiched between the armature 22 and the end plate 23 and cannot rotate. As a result, the motor shaft 31 connected to the friction plate 21 also cannot rotate, and a brake is applied to the motor (brake activated state). 3, in an excited state where a brake current flows through the brake coil 25, an electromagnetic force is generated in the core 26 that overcomes the elastic force of the spring 24 that was pressing the armature 22 against the friction plate 21, thereby attracting the armature 22 to the core 26 and releasing the friction plate 21 from contact with the armature 22 and the end plate 23. As a result, the friction plate 21 and therefore the motor shaft 31 can rotate freely, and the brake on the motor is released (brake released state).

[0012] In this way, the hub 32 of the mechanical brake device 2 and the motor shaft 31 are fixed. The motor to which the mechanical brake device 2 is attached may be either an AC motor or a DC motor. Machines to which motors are attached include, for example, industrial robots and machine tools.

[0013] The mechanical brake device 2 is controlled by a brake drive device 1. As shown in Fig. 1, the brake drive device 1 according to the first embodiment of the present disclosure includes switches 11-1 and 11-2, an energy storage circuit 12, a switch control unit 13, a detection unit 14, a diagnosis unit 15, a power supply 16, and a surge absorber 17. In Fig. 1, only a brake coil 25 of the mechanical brake device 2 is shown.

[0014] The power supply 16 outputs a DC voltage. The power supply 16 is composed of, for example, a rectifier that converts an AC voltage into a DC voltage, a switching regulator, a battery, or the like. As an example, the power supply 16 outputs a DC voltage of 24 V, but may also be a power supply that outputs a DC voltage of another voltage value (for example, 15 V, 12 V, 5 V, etc.).

[0015] The switches 11-1 and 11-2 are each connected in series to the brake coil 25 of the mechanical brake device 2. In the example shown in FIG. 1 , a switch 11-1 (hereinafter sometimes referred to as the "upper switch") that opens and closes the electrical path between the positive terminal of the power source 16 and the positive terminal of the brake coil 25, and a switch 11-2 (hereinafter sometimes referred to as the "lower switch") that opens and closes the electrical path between the negative terminal of the power source 16 and the negative terminal of the brake coil 25 are provided. Note that, although one upper switch and one lower switch are provided in the example shown in FIG. 1 , as a modification, two or more of each may be provided. Examples of the switches 11-1 and 11-2 include FETs, IGBTs, thyristors, GTOs, transistors, and relays. The types of the switches 11-1 and 11-2 themselves do not limit the present embodiment, and switching elements other than those illustrated may also be used.

[0016] When the switches 11-1 and 11-2 receive an ON signal from the switch control unit 13, they are turned ON to close the electrical path between the power source 16 and the brake coil 25. As a result, current flows from the power source 16 to the brake coil 25, and the brake applied by the mechanical brake device 2 is released (brake released state). When the switches 11-1 and 11-2 receive an OFF signal from the switch control unit 13, they are turned OFF to open the electrical path between the power source 16 and the brake coil 25. As a result, the current flowing from the power source 16 to the brake coil 25 is interrupted, and the brake applied by the mechanical brake device 2 is activated (brake activated state). Note that while the mechanical brake device 2 is in the brake released state, the switch control unit 13 periodically applies test pulses to the switches 11-1 and 11-2, in which an OFF signal is momentarily inserted while an ON signal is being output, in order to monitor whether there is a failure in the switches 11-1 and 11-2. If the switches 11-1 and 11-2 are not faulty, the switches 11-1 and 11-2 are turned off for a short time in response to the test pulse.

[0017] The surge absorber 17 is connected between the positive and negative terminals of the brake coil 25 so as to be connected in parallel to the mechanical brake device 2. The surge absorber 17 removes momentary high voltages such as opening and closing surges and noise of the switches 11-1 and 11-2.

[0018] The energy storage circuit 12 is electrically connected to the mechanical brake device 2 and stores energy. In the first embodiment of the present disclosure, the energy storage circuit 12 has a capacitor 12-1 connected in parallel to the brake coil 25 of the mechanical brake device 2. Note that when the switches 11-1 and 11-2 are turned on, the capacitor 12-1 is charged in a short time. When the capacitor 12-1 is charged, a large current flows from the power supply 16, which may damage the switches 11-1 and 11-2. Therefore, in order to suppress such a large current, it is preferable to connect a current-limiting resistor 12-3 in series with the capacitor 12-1. Note that the capacitance C of the capacitor 12-1 should be set to a value that does not cause malfunction of the brake due to the test pulse in the brake release state. The value of the capacitance C can be determined, for example, by reproducing the brake drive device 1 through simulation or by actually operating the brake drive device 1.

[0019] While the mechanical brake device 2 is in the brake release state, test pulses are periodically applied to the switches 11-1 and 11-2, which temporarily reduces the current flowing through the brake coil 25. The capacitor 12-1 in the energy storage circuit 12 supplies the brake coil 25 of the mechanical brake device 2 with energy (electric charge) that suppresses changes in current when the brake applied by the mechanical brake device 2 is released. Even if the test pulses are applied to the switches 11-1 and 11-2 in the brake release state, causing a decrease in the current supplied from the power supply 16 to the brake coil 25, current is supplied to the brake coil 25 based on the energy (electric charge) stored in the capacitor 12 in the energy storage circuit 12, so changes in current in the brake coil 25 can be suppressed.

[0020] The switch control unit 13 outputs an ON signal for turning on the switches 11-1 and 11-2 and an OFF signal for turning off the switches 11-1 and 11-2. Furthermore, the switch control unit 13 controls the switches 11-1 and 11-2 to turn off for a certain period of time while the mechanical brake device 2 is in a brake release state by turning on the switches 11-1 and 11-2. That is, in the brake release state, the switch control unit 13 alternately outputs to the switches 11-1 and 11-2 a test pulse in which an OFF signal is momentarily and periodically inserted while an ON signal is being output.

[0021] When the switch control unit 13 outputs a test pulse while the mechanical brake device 2 is in a brake release state by turning on the switches 11-1 and 11-2 under the control of the switch control unit 13, the detection unit 14 detects the potential of the power lines connecting the switches 11-1 and 11-2 and the mechanical brake device 2. The potential detection result by the detection unit 14 is sent to the diagnosis unit 15.

[0022] The diagnosis unit 15 diagnoses whether or not there is a fault with the switches 11-1 and 11-2 based on the potential detection result by the detection unit 14.

[0023] The diagnosis results by the diagnosing unit 15 may be displayed on, for example, a display device (not shown). Examples of the display device include a standalone display device, a display device attached to the brake drive device 1 or a motor drive device including the same, and a display device attached to a personal computer or a mobile terminal. For example, the display device displays, for example, "The switch is normal" or "The switch is faulty." The above-mentioned display example by the display device is merely an example, and "The switch is normal" and "The switch is faulty" may be displayed using other expressions or pictures.

[0024] The diagnosis result by the diagnosing unit 15 may be output by an audio device (not shown) that emits sounds such as voice, a speaker, a buzzer, a chime, etc. For example, a tone, a scale, a rhythm, or a melody may be set so that the difference between "the switch is normal" and "the switch is faulty" can be distinguished. Also, the audio device may be silent when "the switch is normal" and emit a sound only when "the switch is faulty."

[0025] The diagnosis results from the diagnosis unit 15 may be printed out on paper or the like using a printer and displayed.

[0026] Although examples of notifying the operator of the diagnosis results by the diagnosing unit 15 have been described above, these may be realized by appropriately combining them. Furthermore, each time a diagnosis result is obtained by the diagnosing unit 15, it may be stored and accumulated in memory, and by creating a database, it may be used for failure prediction and preventive maintenance.

[0027] Based on the notified diagnosis result by the diagnosing unit 15, the worker can quickly and reliably grasp the state of the switches 11-1 and 11-2 of the brake drive device 1. Therefore, if the worker finds that the switch 11-1 or 11-2 is faulty based on the diagnosis result by the diagnosing unit 15, the worker can take action such as replacing or repairing the switch 11-1 or 11-2, for example.

[0028] The brake drive device 1 or a motor drive device including the same includes at least one processor, which is an arithmetic processing device. Examples of the arithmetic processing device include an IC, an LSI, a CPU, an MPU, and a DSP. The arithmetic processing device includes a switch control unit 13, a detection unit 14, a diagnosis unit 15, and other processing circuits. Each of these units included in the arithmetic processing device is a functional module implemented by a program executed on the processor. For example, if the switch control unit 13, the detection unit 14, the diagnosis unit 15, and other processing circuits are implemented in a program format, the functions of each unit can be realized by operating the arithmetic processing device in accordance with the program. The programs for executing the processes of the switch control unit 13, the detection unit 14, the diagnosis unit 15, and other processing circuits may be provided in a form recorded on a computer-readable recording medium such as a semiconductor memory, a magnetic recording medium, or an optical recording medium. Alternatively, the switch control unit 13, the detection unit 14, the diagnosis unit 15, and other processing circuits may be implemented as a semiconductor integrated circuit onto which programs for implementing the functions of each unit are written.

[0029] The brake drive device 1 or a motor drive device including the same is provided with at least one memory serving as a storage device. Examples of the memory include electrically erasable and recordable nonvolatile memories such as EEPROM (registered trademark), or high-speed read / write random access memories such as DRAM and SRAM. The storage device may also have a configuration such as an HDD or SSD. The memory may store programs for operating the switch control unit 13, the detection unit 14, the diagnosis unit 15, and other processing circuits. The memory also stores potential detection results acquired by the detection unit 14. The memory also stores diagnosis results obtained by the diagnosis unit 15. Various data related to the brake drive device 1 or a motor drive device including the same is also stored in the memory.

[0030] <Configuration of Brake Driving Device According to Second Embodiment> FIG. 4 is a circuit diagram showing a brake driving device according to a second embodiment of the present disclosure.

[0031] In the second embodiment of the present disclosure, an energy storage circuit 12 having an inductor 12-2 is provided instead of the energy storage circuit 12 having the capacitor 12-1 in the first embodiment described above.

[0032] Similar to the first embodiment described above, the brake driving device 1 according to the second embodiment of the present disclosure also controls the mechanical brake device 2. The mechanical brake device 2 has been described with reference to FIGS. 2 and 3 .

[0033] 4, the brake driving device 1 according to the first embodiment of the present disclosure includes switches 11-1 and 11-2, an energy storage circuit 12, a switch control unit 13, a detection unit 14, a diagnosis unit 15, a power supply 16, and a surge absorber 17. In FIG. 4, only the brake coil 25 of the mechanical brake device 2 is shown.

[0034] The switches 11-1 and 11-2, the switch control section 13, the detection section 14, the diagnosis section 15, the power supply 16, and the surge absorber 17 are as described in the first embodiment with reference to FIG.

[0035] The energy storage circuit 12 is electrically connected to the mechanical brake device 2 and stores energy. In the second embodiment of the present disclosure, the energy storage circuit 12 has an inductor (coil) 12-2 connected in series with the brake coil 25 of the mechanical brake device 2. Note that the inductance L of the inductor 12-2 should be set to a value that does not cause malfunction of the brake due to the test pulse in the brake release state, and the value of the inductance L can be determined, for example, by reproducing the brake drive device 1 through simulation or by actually operating the brake drive device 1.

[0036] While the mechanical brake device 2 is in the brake release state, test pulses are periodically applied to the switches 11-1 and 11-2, which temporarily reduces the current flowing through the brake coil 25. The inductor 12-2 in the energy storage circuit 12 supplies energy to the brake coil 25 of the mechanical brake device 2 to suppress changes in current when the brake applied by the mechanical brake device 2 is released. Even if the test pulses are applied to the switches 11-1 and 11-2 in the brake release state, causing a reduction in the current supplied from the power supply 16 to the brake coil 25, current is supplied to the brake coil 25 based on the magnetic energy stored in the inductor 12-2 in the energy storage circuit 12, so changes in current in the brake coil 25 can be suppressed.

[0037] The first and second embodiments of the present disclosure may be combined and implemented. In this case, the energy storage circuit 12 has a capacitor 12-1 connected in parallel to the brake coil 25 of the mechanical brake device 2, and an inductor 12-2 connected in series to the brake coil 25 of the mechanical brake device 2.

[0038] <Operation of the Brake Driving Device According to the First and Second Embodiments> FIG. 5 is a timing chart illustrating waveforms in the brake driving device according to the first and second embodiments of the present disclosure.

[0039] Here, switch 11-1, which opens and closes the electrical path between the positive terminal of power supply 16 and the positive terminal of brake coil 25, is referred to as the "upper switch," and switch 11-2, which opens and closes the electrical path between the negative terminal of power supply 16 and the negative terminal of brake coil 25, is referred to as the "lower switch." Furthermore, the potential of the power line connecting the upper switch (switch 11-1) and the positive terminal of brake coil 25, which is detected by detection unit 14, is referred to as the "upper detection signal." Furthermore, the potential of the power line connecting the lower switch (switch 11-2) and the negative terminal of brake coil 25, which is detected by detection unit 14, is referred to as the "lower detection signal." In Figure 5, from top to bottom, the on / off switch signal applied to the upper switch by the switch control unit 13, the on / off switch signal applied to the lower switch by the switch control unit 13, the upper detection signal detected by the detection unit 14, the lower detection signal detected by the detection unit 14, and the current flowing through the brake coil 25 of the mechanical brake device 2 are illustrated over time.

[0040] 5, in the initial state from time 0 to time t1, the switch control unit 13 outputs an OFF signal to the upper switch and the lower switch, and therefore the upper switch and the lower switch are turned OFF to open the electrical path between the power supply 16 and the brake coil 25. While the upper switch and the lower switch are turned OFF, the current flowing from the power supply 16 to the brake coil 25 is interrupted, and the brake is applied by the mechanical brake device 2 (brake applied state).

[0041] At time t1, an ON signal is output from the switch control unit 13 to the upper switch and the lower switch, which turns on the upper switch and the lower switch to open the electrical path between the power supply 16 and the brake coil 25. While the upper switch and the lower switch are in the ON state, current flows from the power supply 16 to the brake coil 25, and the brake applied by the mechanical brake device 2 is released (brake released state).

[0042] From time t1 onwards, the mechanical brake device 2 is in a brake release state. During this time, the switch control unit 13 periodically alternately applies to the switches 11-1 and 11-2 test pulses, in which an off signal is momentarily inserted while an on signal is being output. For example, the switch control unit 13 applies to the upper switch a test pulse in which an off signal TP1 is momentarily and periodically inserted while an on signal is being output, at times t3, t5, and t7. For example, the switch control unit 13 applies to the lower switch a test pulse in which an off signal TP2 is momentarily and periodically inserted while an on signal is being output, at times t2, t4, and t6.

[0043] After time t1, when the mechanical brake device 2 is in the brake release state, if the upper switch is normal, the upper switch turns off in response to the periodically applied off signal TP1 while turning on in response to the on signal. As a result, the potential of the power line connecting the upper switch to the positive terminal of the brake coil 25 changes at times t3, t5, and t7 when the off signal TP1 is applied to the upper switch. The detection unit 14 detects this as an upper detection signal. If the upper switch is normal, the detection unit 14 outputs an upper detection signal corresponding to the test pulse applied to the upper switch. Therefore, the diagnosis unit 15 determines that the upper switch is normal when an upper detection signal corresponding to the test pulse applied to the upper switch is output. On the other hand, if there is a fault in the upper switch, the upper switch does not operate normally, and therefore no upper detection signal corresponding to the test pulse applied to the upper switch is output. Therefore, if an upper detection signal corresponding to the test pulse applied to the upper switch is not output, the diagnostic unit 15 determines that the upper switch is faulty.

[0044] Similarly, when the mechanical brake device 2 is in the brake release state after time t1, if the lower switch is normal, the lower switch turns off in response to the periodically applied off signal TP2 while turning on in response to the on signal. As a result, the potential of the power line connecting the lower switch to the negative terminal of the brake coil 25 changes at times t2, t4, and t6 when the off signal TP2 is applied to the lower switch. The detection unit 14 detects this as a lower-side detection signal. If the lower switch is normal, the detection unit 14 outputs a lower-side detection signal corresponding to the test pulse applied to the lower switch. Therefore, the diagnosis unit 15 determines that the lower switch is normal when a lower-side detection signal corresponding to the test pulse applied to the lower switch is output. On the other hand, if there is a fault in the lower switch, the lower switch does not operate normally, and therefore a lower-side detection signal corresponding to the test pulse applied to the lower switch is not output. Therefore, if a lower detection signal corresponding to the test pulse applied to the lower switch is not output, the diagnostic unit 15 determines that the lower switch is faulty.

[0045] Thus, when the mechanical brake device 2 is in the brake-released state, the switch control unit 13 periodically applies test pulses, each consisting of an ON signal and an OFF signal momentarily inserted therein, to the switches 11-1 and 11-2 alternately. When the switches 11-1 and 11-2 are normal, the upper and lower switches are momentarily turned OFF at times t2, t3, t4, t5, t6, and t7, when the switch control unit 13 outputs an OFF signal TP1 for the upper switch and an OFF signal TP2 for the lower switch. As a result, the current flowing through the brake coil 25 decreases. If the degree of current change (current decrease) in the brake coil 25 is large, the current flowing through the brake coil 25 decreases, weakening the electromagnetic force generated in the core 26. If the elastic force of the spring 24 overcomes the electromagnetic force generated in the core 26, the armature 22 is pressed strongly against the friction plate 21, preventing the motor shaft 31 connected to the friction plate 21 from rotating and causing the brake to malfunction. The smaller and lighter the mechanical brake device 2, the smaller the energy stored in the brake coil 25, making it more likely that a malfunction of the brake of the mechanical brake device 2 will occur due to the test pulse. Therefore, in the brake drive device 1 according to the first and second embodiments of the present disclosure, a current is supplied to the brake coil 25 based on the energy stored in the energy storage circuit 12 to compensate for the decrease in current. That is, even if a test pulse is applied to the switches 11-1 and 11-2 in the brake release state, causing a decrease in the current supplied to the brake coil 25 from the power supply 16, the energy (charge) stored in the energy storage circuit 12 supplies current to the brake coil 25, thereby suppressing a change in the current in the brake coil 25. This makes it possible to avoid a malfunction of the brake caused by a decrease in the current flowing through the brake coil 25 in the brake release state.

[0046] 6 is a timing chart showing waveforms when the brake drive devices according to the first and second embodiments of the present disclosure are actually operated. In Fig. 6, a solid line indicates an on / off switch signal applied to the upper switch by the switch control unit 13, a dashed line indicates a voltage applied to the brake coil 25 of the mechanical brake device 2, and a dashed line indicates a current flowing through the brake coil 25 of the mechanical brake device 2.

[0047] As shown in Figure 6, when the mechanical brake device 2 is in the brake-released state, one millisecond after the start, the switch control unit 13 applies a test pulse to the upper switch, in which an off signal TP1 is momentarily and periodically inserted while an on signal is being output. This causes a temporary drop in the voltage applied to the brake coil 25, and accordingly, a temporary drop in the current flowing through the brake coil 25 of the mechanical brake device 2. However, because energy stored in the energy storage circuit 12 is supplied to the brake coil 25, the drop in the voltage applied to the brake coil 25 becomes gradual and then begins to increase. Accordingly, the current flowing through the brake coil 25 also gradually decreases and then begins to increase, so that the current flowing through the brake coil 25 does not drop below the malfunction level. This makes it possible to avoid malfunctioning of the brake in the brake-released state.

[0048] 7 is a timing chart showing waveforms observed when a conventional brake drive device without an energy storage circuit is actually operated. In FIG. 7, a solid line indicates an on / off switch signal applied to the upper switch by the switch control unit 13, a dashed line indicates a voltage applied to the brake coil 25 of the mechanical brake device 2, and a dashed line indicates a current flowing through the brake coil 25 of the mechanical brake device 2.

[0049] As shown in FIG. 7 , when the mechanical brake device 2 is in the brake-released state, the switch control unit 13 applies a test pulse to the upper switch 1 millisecond after the start of the test. The test pulse includes an OFF signal TP1 momentarily and periodically inserted during the ON signal output. This reduces the voltage applied to the brake coil 25, and the current flowing through the brake coil 25 also decreases accordingly. The voltage applied to the brake coil 25 remains reduced until 3 milliseconds after the start of the test, and then finally begins to increase. Because the voltage applied to the brake coil 25 remains reduced for approximately 2 milliseconds, the current flowing through the brake coil 25 decreases significantly. The current flowing through the brake coil 25 falls below the malfunction level approximately 1.7 milliseconds after the start of the test, and further decreases to nearly 0 A (zero amperes) 3 milliseconds after the start of the test. This is because the conventional brake drive device does not include an energy storage circuit. Since the current flowing through the brake coil 25 is below the malfunction level, in the conventional brake driving device, the test pulse causes malfunction of the brake of the mechanical brake device 2 while the brake is released.

[0050] 6 and 7, according to the first and second embodiments of the present disclosure, by providing the energy storage circuit 12 in the brake drive device 1, it is possible to effectively suppress a change in current (a decrease in current) in the brake coil 25 when the brake applied by the mechanical brake device 2 is released. Therefore, according to the first and second embodiments of the present disclosure, it is possible to avoid malfunction of the brake when the brake is released.

[0051] The smaller and lighter the mechanical brake device 2 is, the smaller the energy stored in the brake coil 25 is, and therefore the greater the effect of the energy storage circuit 12 in suppressing the current change (current drop) in the brake coil 25 .

[0052] Furthermore, for example, in machine tools, a workpiece may be machined by smoothly rotating a motor to which a tool is attached. While the motor is rotating, the brake is released, and during this time, a fault diagnosis of a switch is performed in a brake drive device using a test pulse. If the brake temporarily malfunctions due to the test pulse even when the brake is released, the motor rotation speed may decrease, affecting machining accuracy. Furthermore, brake malfunction may cause unnecessary wear on the friction plates of a mechanical brake device. According to the first and second embodiments of the present disclosure, it is possible to avoid brake malfunction in the brake released state, thereby suppressing wear on the friction plates without reducing the machining accuracy of the machine tool.

[0053] Although the present disclosure has been described in detail above, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0054] <Supplementary Notes> The following supplementary notes are further disclosed regarding the above-described embodiment and modifications.

[0055] (Supplementary Note 1) A brake drive device 1 comprising switches 11-1 and 11-2 that release the brake provided by the mechanical brake device 2 by performing an on operation to allow current to flow to the mechanical brake device 2, and that activate the brake provided by the mechanical brake device 2 by performing an off operation to prevent current from flowing to the mechanical brake device 2, and an energy storage circuit 12 that is electrically connected to the mechanical brake device 2 and stores energy, and supplies energy from the energy storage circuit 12 to the mechanical brake device 2 to suppress changes in current when the brake provided by the mechanical brake device 2 is released. (Supplementary Note 2) The brake drive device 1 according to Supplementary Note 1, further comprising a switch control unit 13 that controls the switches 11-1 and 11-2 to be turned on to keep the switches 11-1 and 11-2 turned off for a fixed time while the brake provided by the mechanical brake device 2 is released. (Supplementary Note 3) The brake drive device according to Supplementary Note 2, comprising: a detection unit 14 that detects a potential of a power line connecting the switches 11-1 and 11-2 and the mechanical brake device 2 when the switches 11-1 and 11-2 are turned on and turned off for a certain period of time while the brake by the mechanical brake device 2 is released by the control of the switch control unit 13, and a diagnosis unit 15 that diagnoses the presence or absence of a failure in the switches 11-1 and 11-2 based on the detection result of the potential by the detection unit 14. (Supplementary Note 4) The brake drive device 1 according to any one of Supplements 1 to 3, wherein the energy storage circuit 12 has a capacitor 12-1 connected in parallel to the brake coil 25 of the mechanical brake device 2. (Supplementary Note 5) The brake drive device 1 according to any one of claims 1 to 4, wherein the energy storage circuit 12 has an inductor 12-2 connected in series to the brake coil 25 of the mechanical brake device 2. (Appendix 6) The brake drive device 1 according to any one of claims 1 to 5, wherein the mechanical brake device 2 applies a brake to the motor by using the elastic force of the spring 24 to press the armature 22 against the friction plate 21 to which the motor shaft 31 is connected, and releases the brake on the motor by pulling the armature 22 away from the friction plate 21 with an electromagnetic force generated by current flowing through the brake coil 25.

[0056] REFERENCE SIGNS LIST 1 Brake drive device 2 Mechanical brake device 11-1, 11-2 Switch 12 Energy storage circuit 12-1 Capacitor 12-2 Inductor 12-3 Current limiting resistor 13 Switch control section 14 Detection section 15 Diagnostic section 16 Power supply 17 Surge absorber 21 Friction plate 22 Armature 23 End plate 24 Spring 25 Brake coil 26 Core 27 Spacer 28 Bolt 31 Shaft 32 Hub

Claims

1. A switch that operates in an on state to allow current to flow through a mechanical brake device to release the brake applied by the mechanical brake device, and operates in an off state to prevent current from flowing through the mechanical brake device to actuate the brake applied by the mechanical brake device; An energy storage circuit that is electrically connected to the mechanical brake device and stores energy; Comprising: A brake drive device that supplies energy for suppressing current changes when the brake applied by the mechanical brake device is released from the energy storage circuit to the mechanical brake device.

2. The brake drive device according to claim 1, further comprising a switch control unit that controls the switch to operate in an off state for a certain period while the switch is operating in an on state and the brake applied by the mechanical brake device is released.

3. A detection unit that detects the potential of a power line connecting the switch and the mechanical brake device when the switch is operated in an off state for a certain period while the switch is operated in an on state and the brake applied by the mechanical brake device is released under the control of the switch control unit; A diagnosis unit that diagnoses the presence or absence of a failure of the switch based on the potential detection result by the detection unit; The brake drive device according to claim 2, comprising:

4. The brake drive device according to any one of claims 1 to 3, wherein the energy storage circuit has a capacitor connected in parallel with a brake coil of the mechanical brake device.

5. The brake drive device according to any one of claims 1 to 3, wherein the energy storage circuit has an inductor connected in series with a brake coil of the mechanical brake device.

6. The brake drive device according to any one of claims 1 to 3, wherein the mechanical brake device applies a brake to the motor by pressing an armature against a friction plate coupled to a shaft of the motor with an elastic force of a spring, and releases the brake on the motor by separating the armature from the friction plate with an electromagnetic force generated when current flows through a brake coil.