Brake drive unit that drives the mechanical brake system

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

Technical Field

[0001] This disclosure relates to a brake drive device for driving a mechanical brake device.

Background Art

[0002] In a motor drive device for driving a motor in a machine such as an industrial robot or a machine tool, a mechanical brake device is widely used to apply a brake to a rotating motor or to fix a stopped motor so that it does 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 into the brake coil, and the brake by the mechanical brake device is released. Also, when the switch is turned off, current is prevented from flowing from the power supply into the brake coil, and the brake of the mechanical brake device is actuated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] While a mechanical brake system is in the brake release state, a test pulse is periodically applied to momentarily switch off the switch between the brake coil and the power supply to monitor for any malfunctions. Applying a test pulse to the switch while the brake is released can cause a temporary period during which no current flows to the brake coil, potentially leading to brake malfunction. Therefore, a brake drive system that can prevent brake malfunction while the brake is released is desired. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, the brake drive device includes a switch that, when turned ON to supply current to the mechanical brake device, releases the brake by the mechanical brake device, and when turned OFF to stop current from flowing to the mechanical brake device, activates the brake by the mechanical brake device, and an energy storage circuit that is electrically connected to the mechanical brake device and stores energy. A switch control unit controls the switch to remain in the OFF position for a certain period of time while the brake is released by the mechanical brake device when the switch is turned ON, The system is equipped with an energy storage circuit that supplies energy to the mechanical brake device to suppress current changes when the brakes are released by the mechanical brake device. [Brief explanation of the drawing]

[0006] [Figure 1] This is a circuit diagram showing a brake drive device according to the first embodiment of the present disclosure. [Figure 2] This is a cross-sectional view showing the structure of a mechanical brake device controlled by a brake drive device according to the first and second embodiments of the present disclosure, showing the state in which the brake is applied to the motor. [Figure 3] This is a cross-sectional view showing the structure of a mechanical brake device controlled by a brake drive device according to the first and second embodiments of the present disclosure, showing a state in which the brake on the motor is released. [Figure 4] This is a circuit diagram showing a brake drive device according to a second embodiment of the present disclosure. [Figure 5]This is a timing chart illustrating the waveforms in the brake drive system according to the first and second embodiments of this disclosure. [Figure 6] This is a timing chart showing the waveforms when the brake drive system according to the first and second embodiments of this disclosure is actually operated. [Figure 7] This timing chart shows the waveforms when a conventional brake drive system without an energy storage circuit is actually operated. [Modes for carrying out the invention]

[0007] The brake drive device that drives the mechanical brake device of the embodiment will be described below with reference to the drawings. In the following description, components having the same or similar functions will be denoted by the same reference numerals. Duplication of the description of these components may be omitted. Here, "on" of the switch means that the circuit to which the switch is provided is closed; that is, when the switch is turned on, the circuit to which the switch is provided is connected and becomes closed. Conversely, "off" of the switch means that the circuit to which the switch is provided is open; that is, when the switch is turned off, the circuit to which the switch is provided is interrupted and becomes open.

[0008] <Configuration of the brake drive device according to the first embodiment> Figure 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 this disclosure is an unexcited type brake device that operates the brake when no voltage is applied to the brake coil 25 and releases the brake when voltage is applied to the brake coil 25.

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

[0011] As shown in Figures 2 and 3, in the mechanical brake device 2, a friction plate 21 is positioned between the armature 22 and the end plate 23. A hub 32 is spline-coupled to the friction plate 21. The hub 32 and the motor shaft 31 are integrated, for example, by shrink-fitting, so the friction plate 21 rotates in conjunction with the rotation of the motor shaft 31. The end plate 23 and the spacer 27 are connected by bolts 28, and the armature 22 is connected to the spacer 27 so that it can move toward and away from the friction plate 21. A spring 24 and a brake coil 25 are provided inside the core 26. As shown in Figure 2, in the unexcited state where no voltage is applied to the brake coil 25, the armature 22 is strongly pressed against the friction plate 21 by the elastic force of the spring 24, and the friction plate 21 is trapped between the armature 22 and the end plate 23 and cannot rotate. As a result, the motor shaft 31 coupled to the friction plate 21 also becomes unable to rotate, and the brake is applied to the motor (brake applied state). On the other hand, as shown in Figure 3, in the excitation 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. As a result, the armature 22 is attracted to the core 26, and the friction plate 21 is released from contact with the armature 22 and the end plate 23. Consequently, the friction plate 21 and, by extension, the motor shaft 31 can rotate freely, and the brake on the motor is released (brake release state).

[0012] In this manner, the hub 32 of the mechanical brake device 2 and the motor shaft 31 are fixed together. The motor to which the mechanical brake device 2 is attached may be an AC motor or a DC motor. Examples of machines to which the motor is installed include industrial robots and machine tools.

[0013] The mechanical brake device 2 is controlled by the brake drive device 1. As shown in Figure 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 diagnostic unit 15, a power supply 16, and a surge absorber 17. In Figure 1, only the brake coil 25 of the mechanical brake device 2 is shown.

[0014] Power supply 16 outputs a DC voltage. Power supply 16 consists of, for example, a rectifier that converts AC voltage to DC voltage, a switching regulator, or a battery. For example, power supply 16 outputs a DC voltage with a voltage value of 24V, but it may also be a power supply that outputs DC voltages of other values ​​(for example, 15V, 12V, 5V, etc.).

[0015] 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 Figure 1, there is a switch 11-1 (hereinafter sometimes referred to as the "upper switch") that opens and closes the circuit between the positive terminal of the power supply 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 circuit between the negative terminal of the power supply 16 and the negative terminal of the brake coil 25. In the example shown in Figure 1, there is one upper switch and one lower switch, but in a variation, two or more of each may be provided. Examples of switches 11-1 and 11-2 include FETs, IGBTs, thyristors, GTOs, transistors, relays, etc. The types of switches 11-1 and 11-2 themselves are not limited to this embodiment, and other switching elements may be used besides those exemplified.

[0016] When switches 11-1 and 11-2 receive an on signal from the switch control unit 13, they turn on and close the circuit between the power supply 16 and the brake coil 25. As a result, current flows from the power supply 16 to the brake coil 25, and the brake by the mechanical brake device 2 is released (brake release state). Also, when switches 11-1 and 11-2 receive an off signal from the switch control unit 13, they turn off and open the circuit between the power supply 16 and the brake coil 25. Thereby, the current flowing from the power supply 16 to the brake coil 25 is cut off, and the brake by the mechanical brake device 2 operates (brake operation state). While the mechanical brake device 2 is in the brake release state, in order to monitor whether there is a failure in switches 11-1 and 11-2, the switch control unit 13 periodically applies a test pulse in which an off signal instantaneously enters during the output of the on signal to switches 11-1 and 11-2. If there is no failure in switches 11-1 and 11-2, switches 11-1 and 11-2 perform an off operation for a short time in response to the test pulse.

[0017] The surge absorber 17 is connected between the positive terminal and the negative terminal of the brake coil 25 so as to be connected in parallel to the mechanical brake device 2. The surge absorber 17 removes instantaneous high voltages such as opening / closing surges and noise of 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 with the brake coil 25 of the mechanical brake device 2. 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 out from the power source 16, so the switches 11-1 and 11-2 may be damaged. Therefore, in order to suppress such a large current, it is preferable that a current limiting resistor 12-3 is connected in series to the capacitor 12-1. The capacitance C of the capacitor 12-1 should be set to a value such that malfunction of the brake due to test pulses does not occur in the brake release state. For example, the magnitude of the capacitance C can be determined by reproducing the brake drive device 1 by simulation or 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, whereby the current flowing through the brake coil 25 temporarily decreases. The capacitor 12-1 in the energy storage circuit 12 supplies energy (electric charge) that suppresses current changes when the brake by the mechanical brake device 2 is released to the brake coil 25 of the mechanical brake device 2. In the brake release state, even when a test pulse is applied to the switches 11-1 and 11-2 and the current supplied from the power source 16 to the brake coil 25 decreases, a current is supplied to the brake coil 25 based on the energy (electric charge) stored in the capacitor 12-1 in the energy storage circuit 12, so that the current change of the brake coil 25 can be suppressed.

[0020] The switch control unit 13 outputs an ON signal to turn on switches 11-1 and 11-2, and an OFF signal to turn off switches 11-1 and 11-2. The switch control unit 13 also controls switches 11-1 or 11-2 to be turned OFF for a certain period of time while switches 11-1 and 11-2 are turned ON and the mechanical brake device 2 is in the brake release state. In other words, in the brake release state, the switch control unit 13 alternately outputs test pulses to switches 11-1 and 11-2 in which an OFF signal is instantaneously and periodically inserted while an ON signal is output.

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

[0022] The diagnostic unit 15 diagnoses whether there is a malfunction in switches 11-1 and 11-2 based on the potential detection results from the detection unit 14.

[0023] The diagnostic results from the diagnostic unit 15 may be displayed on a display device (not shown), for example. Examples of display devices include a standalone display device, a display device attached to the brake drive device 1 or the motor drive device equipped therewith, and a display device attached to a personal computer or mobile terminal. For example, the display device may display "Switch is normal" or "Switch is faulty." The above-mentioned examples of displays by the display device are merely examples, and "Switch is normal" and "Switch is faulty" may be displayed based on other expressions or images.

[0024] The diagnostic results from the diagnostic unit 15 may be output by an acoustic device (not shown) that emits sound, such as a voice, speaker, buzzer, or chime. For example, the tone, pitch, rhythm, or melody can be set so that the difference between "the switch is normal" and "the switch is faulty" can be distinguished. Alternatively, the acoustic device may be silent when "the switch is normal" and emit sound only when "the switch is faulty".

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

[0026] The above describes examples of how the diagnostic unit 15 notifies the operator of the diagnostic results, but these can be combined as appropriate. Furthermore, the diagnostic results from the diagnostic unit 15 can be stored in memory each time they are obtained and accumulated to create a database, which can be used for fault prediction and preventive maintenance.

[0027] Based on the diagnostic results from the diagnostic unit 15, the operator can quickly and reliably determine the status of switches 11-1 and 11-2 of the brake drive unit 1. Therefore, if the diagnostic results from the diagnostic unit 15 confirm that switch 11-1 or 11-2 is malfunctioning, the operator can take appropriate action, such as replacing or repairing switch 11-1 or 11-2.

[0028] The brake drive unit 1 or the motor drive unit equipped therewith is provided with at least one processor, which is an arithmetic processing unit. Examples of arithmetic processing units include ICs, LSIs, CPUs, MPUs, and DSPs. The arithmetic processing unit has a switch control unit 13, a detection unit 14, a diagnostic unit 15, and other processing circuits. Each of these parts of the arithmetic processing unit is a functional module realized by a program executed on the processor. For example, if the switch control unit 13, the detection unit 14, the diagnostic unit 15, and other processing circuits are constructed in program form, the functions of each part can be realized by operating the arithmetic processing unit according to this program. The programs for executing each of the processes of the switch control unit 13, the detection unit 14, the diagnostic unit 15, and other processing circuits may be provided in the form of a recording 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 diagnostic unit 15, and other processing circuits may be realized as semiconductor integrated circuits on which programs realizing the functions of each part are written.

[0029] Furthermore, at least one memory, which is a storage device, is provided within the brake drive unit 1 or the motor drive unit equipped therewith. The memory may be an electrically erasable and recordable non-volatile memory such as EEPROM (registered trademark), or a high-speed read / write random access memory such as DRAM or 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 diagnostic unit 15, and other processing circuits. The memory also stores the potential detection results acquired by the detection unit 14. The memory also stores the diagnostic results from the diagnostic unit 15. The memory also stores various data related to the brake drive unit 1 or the motor drive unit equipped therewith.

[0030] <Configuration of the brake drive device according to the second embodiment> Figure 4 is a circuit diagram showing a brake drive device according to a second embodiment of the present disclosure.

[0031] A second embodiment of this disclosure is provided in which an energy storage circuit 12 having an inductor 12-2 is provided instead of the energy storage circuit 12 having a capacitor 12-1 in the first embodiment described above.

[0032] The brake drive device 1 according to the second embodiment of this disclosure also controls the mechanical brake device 2, similar to the first embodiment described above. The mechanical brake device 2 has been described with reference to Figures 2 and 3.

[0033] As shown in Figure 4, the brake drive device 1 according to the first embodiment of the present disclosure comprises switches 11-1 and 11-2, an energy storage circuit 12, a switch control unit 13, a detection unit 14, a diagnostic unit 15, a power supply 16, and a surge absorber 17. In Figure 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 unit 13, the detection unit 14, the diagnostic unit 15, the power supply 16, and the surge absorber 17 are as described in the first embodiment with reference to Figure 1.

[0035] The energy storage circuit 12 is electrically connected to the mechanical brake device 2 and stores energy. In the second embodiment of this 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. The inductance L of the inductor 12-2 should be set to a size that does not cause brake malfunction due to test pulses when the brake is released. For example, the size of the inductance L can be determined 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 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 the current change when the brake by the mechanical brake device 2 is released. Even when the brake is released and test pulses are applied to switches 11-1 and 11-2, reducing the current supplied to the brake coil 25 from the power supply 16, the current change in the brake coil 25 can be suppressed because 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.

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

[0038] <Operation of the brake drive device according to the first and second embodiments> Figure 5 is a timing chart illustrating the waveforms in the brake drive system according to the first and second embodiments of this disclosure.

[0039] Here, switch 11-1, which opens and closes the circuit between the positive terminal of the power supply 16 and the positive terminal of the brake coil 25, is referred to as the "upper switch," and switch 11-2, which opens and closes the circuit between the negative terminal of the power supply 16 and the negative terminal of the brake coil 25, is referred to as the "lower switch." Furthermore, the potential of the power line connecting the upper switch (switch 11-1), detected by the detection unit 14, and the positive terminal of the brake coil 25 is referred to as the "upper detection signal." Furthermore, the potential of the power line connecting the lower switch (switch 11-2), detected by the detection unit 14, and the negative terminal of the brake coil 25 is referred to as the "lower detection signal." Figure 5 illustrates, from top to bottom, the on / off switch signals applied to the upper switch by the switch control unit 13, the on / off switch signals 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, as time progresses.

[0040] In Figure 5, during the initial state from time 0 to time t1, the switch control unit 13 outputs an off signal to the upper and lower switches. Therefore, the upper and lower switches are turned off, opening the circuit between the power supply 16 and the brake coil 25. While the upper and lower switches are turned off, the current from the power supply 16 to the brake coil 25 is interrupted, and the brakes of the mechanical brake device 2 are activated (brake activated state).

[0041] At time t1, the switch control unit 13 outputs an ON signal to the upper and lower switches, causing the upper and lower switches to turn ON and open the circuit between the power supply 16 and the brake coil 25. While the upper and lower switches are ON, current flows from the power supply 16 to the brake coil 25, releasing the brakes of the mechanical brake device 2 (brake release state).

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

[0043] When the mechanical brake device 2 is in the brake release state after time t1, if the upper switch is functioning correctly, the upper switch will turn on in response to an ON signal and then turn off in response to a periodically applied OFF signal TP1. As a result, at times t3, t5, and t7, when the OFF signal TP1 is applied to the upper switch, the potential of the power line connecting the upper switch to the positive terminal of the brake coil 25 changes. The detection unit 14 detects this as an upper detection signal. If the upper switch is functioning correctly, the detection unit 14 outputs an upper detection signal corresponding to the test pulse applied to the upper switch. Therefore, the diagnostic unit 15 determines that the upper switch is functioning correctly if an upper detection signal corresponding to the test pulse applied to the upper switch is output. On the other hand, if the upper switch is faulty, it will not function correctly, and therefore no upper detection signal corresponding to the test pulse applied to the upper switch will be output. Therefore, if the diagnostic unit 15 does not output an upper detection signal corresponding to the test pulse applied to the upper switch, it 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 functioning correctly, the lower switch will turn on in response to an ON signal and then turn off in response to a periodically applied OFF signal TP2. 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 detection signal. If the lower switch is functioning correctly, the detection unit 14 outputs a lower detection signal corresponding to the test pulse applied to the lower switch. Therefore, the diagnostic unit 15 determines that the lower switch is functioning correctly if a lower detection signal corresponding to the test pulse applied to the lower switch is output. On the other hand, if the lower switch is faulty, it will not function correctly, and therefore no lower detection signal corresponding to the test pulse applied to the lower switch will be output. Therefore, if the diagnostic unit 15 does not output a lower detection signal corresponding to the test pulse applied to the lower switch, it determines that the lower switch is faulty.

[0045] Thus, when the mechanical brake device 2 is in the brake release state, the switch control unit 13 periodically applies test pulses to switches 11-1 and 11-2 alternately, in which an off signal is momentarily inserted while an on signal is output. If switches 11-1 and 11-2 are functioning correctly, the upper and lower switches will momentarily turn 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, respectively. As a result, the current flowing through the brake coil 25 decreases. If the degree of change in the current of the brake coil 25 (current decrease) is large, the current flowing through the brake coil 25 decreases, and the electromagnetic force generated in the core 26 weakens. If the elastic force of the spring 24 overcomes the electromagnetic force generated in the core 26, the armature 22 is strongly pressed against the friction plate 21, preventing the motor shaft 31 coupled to the friction plate 21 from rotating, and causing the brake to malfunction on the motor. The smaller and lighter the mechanical brake device 2, the less energy is stored in the brake coil 25, making it easier for the brakes of the mechanical brake device 2 to malfunction due to test pulses. Therefore, in the brake drive device 1 according to the first and second embodiments of this disclosure, a current is supplied to compensate for the decrease in current to the brake coil 25 based on the energy stored in the energy storage circuit 12. That is, even if a test pulse is applied to switches 11-1 and 11-2 in the brake release state and the current supplied from the power supply 16 to the brake coil 25 decreases, the energy (charge) stored in the energy storage circuit 12 supplies current to the brake coil 25, thereby suppressing the change in current to the brake coil 25. This makes it possible to avoid the brakes malfunctioning due to a decrease in the current flowing to the brake coil 25 in the brake release state.

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

[0047] As shown in Figure 6, when the mechanical brake device 2 is in the brake release state, 1 millisecond after the start, the switch control unit 13 applies a test pulse to the upper switch in which the off signal TP1 is instantaneously and periodically included during the output of the on signal. This temporarily reduces the voltage applied to the brake coil 25, and consequently, the current flowing through the brake coil 25 of the mechanical brake device 2 also temporarily decreases. However, since the energy stored in the energy storage circuit 12 is supplied to the brake coil 25, the decrease in the voltage applied to the brake coil 25 becomes gradual, and then the voltage begins to rise. Consequently, the current flowing through the brake coil 25 also decreases gradually and then begins to rise, so the current flowing through the brake coil 25 does not fall below the malfunction level. Therefore, malfunction of the brake in the brake release state can be avoided.

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

[0049] As shown in Figure 7, when the mechanical brake device 2 is in the brake release state, 1 millisecond after the start, the switch control unit 13 applies a test pulse to the upper switch in which an off signal TP1 is instantaneously and periodically included during the output of an on signal. This reduces the voltage applied to the brake coil 25, and consequently, the current flowing through the brake coil 25 also decreases. The voltage applied to the brake coil 25 remains low until 3 milliseconds after the start, and only then does it begin to rise. Since the voltage applied to the brake coil 25 remains low for about 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 at approximately 1.7 milliseconds after the start, and further decreases to near 0 A (zero amperes) at 3 milliseconds after the start. This is because conventional brake drive devices do not have an energy storage circuit. Because the current flowing through the brake coil 25 falls below the malfunction level, in conventional brake drive systems, a malfunction of the mechanical brake device 2 occurs during the brake release state due to the test pulse.

[0050] As can be seen by comparing Figure 6 and Figure 7, according to the first and second embodiments of this disclosure, by providing an energy storage circuit 12 in the brake drive device 1, current changes (current drops) in the brake coil 25 when the brake by the mechanical brake device 2 is released can be effectively suppressed. Therefore, according to the first and second embodiments of this 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, the less energy is stored in the brake coil 25, and therefore the greater the effect of the energy storage circuit 12 in suppressing current changes (current drop) in the brake coil 25.

[0052] Furthermore, in machine tools, for example, a motor to which a tool is attached is rotated smoothly to process a workpiece. While the motor is rotating, the brake is released, and during this time, the brake drive unit performs fault diagnosis of the switch using a test pulse. If the brake malfunctions temporarily due to a test pulse despite the brake being released, the motor's rotation speed will decrease, which may affect the machining accuracy. In addition, the brake malfunction can cause excessive wear on the friction plates of the mechanical brake device. According to the first and second embodiments of this disclosure, it is possible to avoid brake malfunctions when the brake is released, thus preventing a decrease in the machining accuracy of the machine tool and suppressing wear on the friction plates.

[0053] Although the present disclosure has been described in detail above, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of the present disclosure or from the spirit of the present disclosure derived from the claims and their equivalents. Furthermore, these embodiments can be implemented in combination. For example, the order of operations and processes in the embodiments described above are shown as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above.

[0054] <Note> The following additional information is disclosed regarding the above embodiments and modifications.

[0055] (Note 1) Switches 11-1 and 11-2 release the brakes by the mechanical brake device 2 when they are turned ON to supply current to the mechanical brake device 2, and activate the brakes by the mechanical brake device 2 when they are turned OFF to stop current from flowing to the mechanical brake device 2. An energy storage circuit 12 is electrically connected to the mechanical brake device 2 and stores energy, Equipped with, A brake drive device 1 supplies energy from an energy storage circuit 12 to the mechanical brake device 2 to suppress current changes when the brake by the mechanical brake device 2 is released. (Note 2) The brake drive device 1 as described in Appendix 1, further comprising a switch control unit 13 that controls switches 11-1 and 11-2 to be in the off position for a certain period of time while the brakes by the mechanical brake device 2 are released by turning on switches 11-1 and 11-2. (Note 3) When switches 11-1 and 11-2 are turned ON by the control of the switch control unit 13, thereby releasing the brakes by the mechanical brake device 2, and switches 11-1 and 11-2 are turned OFF for a certain period of time, a detection unit 14 detects the potential of the power line connecting switches 11-1 and 11-2 and the mechanical brake device 2, Based on the potential detection results by the detection unit 14, the diagnostic unit 15 diagnoses whether or not switches 11-1 and 11-2 are faulty, A brake drive device as described in Appendix 2, comprising the above. (Note 4) The brake drive device 1 according to any one of the appendices 1 to 3, wherein the energy storage circuit 12 has a capacitor 12-1 connected in parallel with the brake coil 25 of the mechanical brake device 2. (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 with the brake coil 25 of the mechanical brake device 2. (Note 6) The mechanical brake device 2 applies a brake to the motor by using the elastic force of a spring 24 to press the armature 22 against a friction plate 21 to which the motor shaft 31 is connected, and releases the brake to the motor by using the electromagnetic force generated when current flows through the brake coil 25 to pull the armature 22 away from the friction plate 21. This is the brake drive device 1 according to any one of claims 1 to 5. [Explanation of symbols]

[0056] 1. Brake drive system 2. Mechanical braking system 11-1, 11-2 switch 12 Energy Storage Circuits 12-1 Capacitor 12-2 Inductor 12-3 Current Limiting Resistor 13 Switch control unit 14 Detection unit 15. Diagnostic Department 16 Power supply 17 Surge Absorber 21 Friction plate 22 Amateur 23 End plate 24 springs 25 Brake coil 26 cores 27 Spacers 28 volts 31 shafts 32 hubs

Claims

1. A switch that, when turned ON to supply current to the mechanical brake device, releases the brake by the mechanical brake device, and when turned OFF to stop current from flowing to the mechanical brake device, activates the brake by the mechanical brake device. An energy storage circuit electrically connected to the aforementioned mechanical brake device and storing energy, A switch control unit controls the switch to be turned on and the brake by the mechanical brake device released while the switch is turned on, to keep the switch off for a certain period of time. Equipped with, A brake drive device that supplies energy from an energy storage circuit to the mechanical brake device to suppress current changes when the brake by the mechanical brake device is released.

2. A detection unit detects the potential of the power line connecting the switch and the mechanical brake device when the switch is turned ON by the control of the switch control unit, thereby releasing the brake by the mechanical brake device, and the switch is turned OFF for a certain period of time. A diagnostic unit diagnoses whether or not the switch is faulty based on the detection result of the detection unit, The brake drive device according to claim 1, comprising:

3. The brake drive device according to claim 1 or 2, wherein the energy storage circuit has a capacitor connected in parallel with the brake coil of the mechanical brake device.

4. The brake drive device according to claim 1 or 2, wherein the energy storage circuit has an inductor connected in series with the brake coil of the mechanical brake device.

5. The brake drive device according to claim 1 or 2, wherein the mechanical brake device applies a brake to the motor by pressing the armature against a friction plate connected to the motor shaft using the elastic force of a spring, and releases the brake to the motor by pulling the armature away from the friction plate using the electromagnetic force generated when current flows through the brake coil.

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