Brake drive device for driving mechanical brake device

Abstract

The brake drive device is provided with: a switch that releases the braking of the mechanical brake device by performing an ON operation so as to cause current to flow to the mechanical brake device, and that causes the braking of the mechanical brake device by performing an OFF operation so as not to cause current to flow to the mechanical brake device; and an energy storage circuit that is electrically connected to the mechanical brake device, stores energy, and supplies energy from the energy storage circuit to the mechanical brake device, said energy suppressing a change in current when the braking of the mechanical brake device is released.

Description

Technical Field

[0001] The present disclosure relates to a brake drive device for driving a mechanical brake device. Background Art

[0002] In a motor drive device that drives 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 fix a stopped motor so as not to rotate. A switch is connected between the brake coil of the mechanical brake device and a power source. By turning on the switch, current flows from the power source into the brake coil, and the brake of the mechanical brake device is released. In addition, by turning off the switch, current does not flow from the power source into the brake coil, and thus, the brake of the mechanical brake device operates.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-248946

[0006] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2011-195287

[0007] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2020-029877 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] During the period when the mechanical brake device is in the brake released state, in order to monitor whether there is a failure in the switch between the brake coil and the power source, a test pulse for instantaneously turning off the switch is periodically applied. If a test pulse is applied to the switch in the brake released state, a period during which current does not flow through the brake coil is temporarily generated, and thus, the brake may malfunction. Therefore, a brake drive device that can avoid a brake malfunction in the brake released state is desired.

[0010] Means for Solving the Problems

[0011] According to one aspect of the present disclosure, a brake drive device includes: a switch that releases the brake of the mechanical brake device by turning on so as to allow current to flow to the mechanical brake device, and operates the brake of the mechanical brake device by turning off so as not to allow current to flow to the mechanical brake device; and an energy storage circuit that is electrically connected to the mechanical brake device, stores energy, and supplies energy that suppresses a change in current when the brake of the mechanical brake device is released from the energy storage circuit to the mechanical brake device. Brief Description of the Drawings

[0012] Figure 1This is a circuit diagram showing a brake drive device according to a first embodiment of the present disclosure.

[0013] Figure 2 This 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 braking is applied to the motor.

[0014] Figure 3 This 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 braking on the motor is released.

[0015] Figure 4 This is a circuit diagram showing a brake drive device according to a second embodiment of the present disclosure.

[0016] Figure 5 This is a timing chart illustrating waveforms in the brake drive devices according to the first and second embodiments of the present disclosure.

[0017] Figure 6 This is a timing chart showing waveforms when the brake drive devices according to the first and second embodiments of the present disclosure are actually operating.

[0018] Figure 7 This is a timing chart showing waveforms when a brake drive device of a conventional example without an energy storage circuit is actually operating. DETAILED DESCRIPTION

[0019] Hereinafter, a brake drive device for driving a mechanical brake device according to an embodiment will be described with reference to the drawings. In the following description, components having the same or similar functions are denoted by the same reference numerals. Also, repeated descriptions of these components may be omitted. Here, "turning on" of a switch means closing of the circuit in which the switch is provided, that is, performing a turning-on operation of the switch, and the circuit in which the switch is provided is connected to become a closed state. In addition, "turning off" of a switch means opening of the circuit in which the switch is provided, that is, performing a turning-off operation of the switch, and the circuit in which the switch is provided is cut off to become an open state.

[0020] <Structure of the Brake Drive Device of the First Embodiment>

[0021] Figure 1 This is a circuit diagram showing a brake drive device according to a first embodiment of the present disclosure.

[0022] The mechanical brake device 2 controlled by the brake drive device 1 of the first embodiment of the present disclosure is a non-excitation 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.

[0023] Before describing the brake drive device 1 according to the first embodiment of the present disclosure, Figure 2 as well as Figure 3 The structure of the mechanical brake device 2 will be described. Figure 2 It is a cross-sectional view showing the structure of a mechanical brake device controlled by the brake drive device according to the first embodiment and the second embodiment of the present disclosure, and shows a state in which the brake is actuated with respect to the motor. Figure 3 It is a cross-sectional view showing the structure of a mechanical brake device controlled by the brake drive device according to the first embodiment and the second embodiment of the present disclosure, and shows a state in which the brake on the motor is released. Figure 2 as well as Figure 3 The mechanical brake device 2 shown can be applied to the first embodiment as well as the second embodiment.

[0024] like Figure 2 as well as Figure 3 As shown, in the mechanical brake device 2, the friction plate 21 is arranged between the armature 22 and the end plate 23. The hub 32 is spline-keyed to the friction plate 21. The hub 32 and the motor shaft 31 are integrated, for example, by heat press fitting, so that the friction plate 21 also 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 in a manner that it can move toward the direction of approaching the friction plate 21 and away from the friction plate 21. The spring 24 and the brake coil 25 are arranged in the iron core 26. As shown in FIG. Figure 2 As shown in FIG. 1 , in the de-excitation 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 clamped by the armature 22 and the end plate 23 and cannot rotate. As a result, the shaft 31 of the motor coupled to the friction plate 21 cannot rotate either, and the motor is in a state of braking (braking operation state). On the other hand, Figure 3 As shown, in the excited state where the braking current flows through the brake coil 25, an electromagnetic force is generated in the iron core 26 to overcome the elastic force of the spring 24 pressing the armature 22 against the friction plate 21, whereby the armature 22 is attracted by the iron core 26, and the friction plate 21 is released from the contact with the armature 22 and the end plate 23. As a result, the friction plate 21 and the shaft 31 of the motor can rotate freely, and the brake on the motor is released (brake release state).

[0025] In this way, the hub 32 of the mechanical braking device 2 and the shaft 31 of the motor are fixed. The motor to which the mechanical braking device 2 is installed can be an AC motor or a DC motor. Examples of the machinery where the motor is provided include industrial robots, machine tools, etc.

[0026] The mechanical braking device 2 is controlled by the braking drive device 1. As Figure 1 shown, the braking drive device 1 of the first embodiment of the present disclosure has: 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 Figure 1 it, only the braking coil 25 of the mechanical braking device 2 is illustrated.

[0027] The power supply 16 outputs a DC voltage. The power supply 16 is constituted by, for example, a rectifier that converts an AC voltage into a DC voltage, a switching regulator, or a battery. As an example, the power supply 16 outputs a DC voltage with a voltage value of 24V, but it can also be a power supply that outputs a DC voltage with other voltage values (for example, 15V, 12V, 5V, etc.).

[0028] The switches 11-1 and 11-2 are respectively connected in series with the braking coil 25 of the mechanical braking device 2. In Figure 1 the example shown, a switch 11-1 (hereinafter, sometimes referred to as the "upper side switch") that opens and closes the circuit between the positive terminal of the power supply 16 and the positive terminal of the braking coil 25, and a switch 11-2 (hereinafter, sometimes referred to as the "lower side switch") that opens and closes the circuit between the negative terminal of the power supply 16 and the negative terminal of the braking coil 25 are provided. In addition, in Figure 1 the example shown, one upper side switch and one lower side switch are respectively provided, but as a modified example thereof, two or more can be respectively 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 do not limit this embodiment, and other switch elements than those illustrated can also be used.

[0029] When switches 11-1 and 11-2 receive an on signal from the switch control unit 13, they perform an on operation to 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 thus, the braking of the mechanical braking device 2 is released (braking release state). In addition, when switches 11-1 and 11-2 receive an off signal from the switch control unit 13, they perform an off operation to open the circuit between the power supply 16 and the brake coil 25. As a result, the current flowing from the power supply 16 to the brake coil 25 is cut off, and thus, the braking operation of the mechanical braking device 2 (braking operation state). Further, during the period when the mechanical braking device 2 is in the braking release state, in order to monitor whether switches 11-1 and 11-2 are faulty, the switch control unit 13 periodically applies a test pulse in which an off signal is instantaneously input during the output of the on signal to switches 11-1 and 11-2. If switches 11-1 and 11-2 are not faulty, switches 11-1 and 11-2 perform an off operation in a short time according to the test pulse.

[0030] The surge absorber 17 is connected between the positive terminal and the negative terminal of the brake coil 25 in a manner of being connected in parallel with the mechanical braking device 2. The surge absorber 17 removes instantaneous high voltages such as opening and closing surges and noise of switches 11-1 and 11-2.

[0031] The energy storage circuit 12 is electrically connected to the mechanical braking device 2 to store 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 braking device 2. Further, when switches 11-1 and 11-2 perform an on operation, 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 supply 16, and thus, 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 with the capacitor 12-1. In addition, the capacitance C of the capacitor 12-1 should be set to a size that does not cause a malfunction of the braking due to the test pulse in the braking release state. For example, by simulating to reproduce the braking drive device 1 or actually operating the braking drive device 1, the size of the capacitance C can be determined.

[0032] While the mechanical brake device 2 is in the brake release state, test pulses are periodically applied to 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 (charge) that suppresses the current change when the mechanical brake device 2 is released from braking to the brake coil 25 of the mechanical brake device 2. In the brake release state, even if test pulses are applied to switches 11-1 and 11-2 to reduce the current supplied from the power source 16 to the brake coil 25, since current is supplied to the brake coil 25 according to the energy (charge) stored in the capacitor 12-1 in the energy storage circuit 12, the current change of the brake coil 25 can be suppressed.

[0033] The switch control unit 13 outputs an on signal for causing switches 11-1 and 11-2 to perform an on operation and an off signal for causing switches 11-1 and 11-2 to perform an off operation. In addition, while the mechanical brake device 2 is in the brake release state when the switch control unit 13 causes switches 11-1 and 11-2 to perform an on operation, it is controlled to cause switches 11-1 or 11-2 to perform an off operation for a constant time. That is, in the brake release state, the switch control unit 13 alternately outputs test pulses in which an off signal is instantaneously and periodically input during the output of the on signal to switches 11-1 and 11-2.

[0034] When the switch control unit 13 outputs a test pulse while causing switches 11-1 and 11-2 to perform an on operation and the mechanical brake device 2 is in the brake release state, the detection unit 14 detects the potential of the power line connecting switches 11-1 and 11-2 to the mechanical brake device 2. The detection result of the potential by the detection unit 14 is transmitted to the diagnosis unit 15.

[0035] The diagnosis unit 15 diagnoses whether switches 11-1 and 11-2 are faulty based on the detection result of the potential by the detection unit 14.

[0036] The diagnosis result of the diagnosis unit 15 can also be displayed on, for example, a display device (not shown). Examples of the display device include a single display device, a display device attached to the brake drive device 1 or a motor drive device having the brake drive device 1, and a display device attached to a personal computer and a portable terminal. For example, the display device displays, for example, "switch normal" or "switch faulty". The above display example of the display device is just an example, and "switch normal" and "switch faulty" can also be displayed according to other expressions and depictions.

[0037] The diagnostic results of the diagnostic unit 15 can also be output using a sounding device (not shown) that emits sounds, such as a voice, a speaker, a buzzer, or a ringtone. For example, the tone color, scale, rhythm, or melody can be set in a manner that can distinguish the difference between "switch normal" and "switch failure". In addition, the sounding device can be set to be silent when the "switch is normal" and only make a sound when the "switch fails".

[0038] It is also possible to use a printer to print the diagnostic results of the diagnostic unit 15 on paper or the like for display.

[0039] As described above, examples of notifying the operator of the diagnostic results of the diagnostic unit 15 have been described, but they can also be implemented by appropriately combining them. In addition, each time the diagnostic results of the diagnostic unit 15 are obtained, they can be stored and accumulated in a memory, and by creating a database, it is possible to contribute to failure prediction and preventive maintenance.

[0040] The operator can quickly and reliably grasp the states of the switches 11-1 and 11-2 of the brake drive device 1 based on the notified diagnostic results of the diagnostic unit 15. Therefore, when the operator can confirm that a failure has occurred in the switch 11-1 or 11-2 based on the diagnostic results of the diagnostic unit 15, for example, the operator can take measures such as replacing or repairing the switch 11-1 or 11-2.

[0041] At least one processor as an arithmetic processing device is provided in the brake drive device 1 or in the motor drive device having the brake drive device 1. Examples of the arithmetic processing device include an IC, an LSI, a CPU, an MPU, a DSP, etc. The arithmetic processing device has a switch control unit 13, a detection unit 14, a diagnostic unit 15, and other processing circuits. These units of the arithmetic processing device are, for example, functional modules realized by programs executed on the processor. For example, in the case where the switch control unit 13, the detection unit 14, the diagnostic unit 15, and other processing circuits are constructed in the form of programs, the functions of each unit can be realized by causing the arithmetic processing device to operate according to the program. The programs for executing the respective processes of the switch control unit 13, the detection unit 14, the diagnostic unit 15, and other processing circuits can also be provided in the form of being 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 diagnostic unit 15, and other processing circuits can be realized as a semiconductor integrated circuit in which programs for realizing the functions of each unit are written.

[0042] In addition, at least one memory as a storage device is provided in the brake drive device 1 or in the motor drive device having the brake drive device 1. As the memory, for example, there are non-volatile memories such as EEPROM (registered trademark) that can be electrically erased / recorded, or random access memories such as DRAM and SRAM that can perform high-speed reading and writing. In addition, the storage device may have a structure such as HDD, SSD, etc. Programs for operating the switch control unit 13, the detection unit 14, the diagnosis unit 15, and other processing circuits may also be stored in the memory. In addition, the potential detection results obtained by the detection unit 14 are stored in the memory. In addition, the diagnosis results of the diagnosis unit 15 are stored in the memory. In addition, various data related to the brake drive device 1 or the motor drive device having the brake drive device 1 are stored in the memory.

[0043] <Structure of the Brake Drive Device of the Second Embodiment>

[0044] Figure 4 It is a circuit diagram showing the brake drive device of the second embodiment of the present disclosure.

[0045] Regarding the second embodiment of the present disclosure, instead of the energy storage circuit 12 having the capacitor 12-1 in the above first embodiment, an energy storage circuit 12 having an inductor 12-2 is provided.

[0046] The brake drive device 1 of the second embodiment of the present disclosure also controls the mechanical brake device 2 in the same manner as the above first embodiment. Regarding the mechanical brake device 2, as described with reference to Figure 2 and Figure 3 as follows.

[0047] As Figure 4 shown, the brake drive device 1 of 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 Figure 4 only the brake coil 25 of the mechanical brake device 2 is illustrated.

[0048] The switches 11-1 and 11-2, the switch control unit 13, the detection unit 14, the diagnosis unit 15, the power supply 16, and the surge absorber 17 are as described with reference to Figure 1 in the first embodiment.

[0049] The energy storage circuit 12 is electrically connected to the mechanical braking device 2 to store 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 braking coil 25 of the mechanical braking device 2. In addition, the inductance L of the inductor 12 should be set to a magnitude that does not cause a malfunction of the brake due to a test pulse in the brake released state. For example, by simulating to reproduce the braking drive device 1 or actually operating the braking drive device 1, the magnitude of the inductance L can be determined accordingly.

[0050] During the period when the mechanical braking device 2 is in the brake released state, test pulses are periodically applied to the switches 11-1 and 11-2, whereby the current flowing through the braking coil 25 temporarily decreases. The inductor 12-2 in the energy storage circuit 12 supplies energy to suppress the current change when the brake of the mechanical braking device 2 is released to the braking coil 25 of the mechanical braking device 2. In the brake released state, even if test pulses are applied to the switches 11-1 and 11-2 to reduce the current supplied from the power source 16 to the braking coil 25, since the current is supplied to the braking coil 25 according to the magnetic energy stored in the inductor 12-2 in the energy storage circuit 12, the current change of the braking coil 25 can be suppressed.

[0051] In addition, the first embodiment and the second embodiment of the present disclosure can be implemented in combination. In this case, the energy storage circuit 12 has a capacitor 12-1 connected in parallel with the braking coil 25 of the mechanical braking device 2 and an inductor 12-2 connected in series with the braking coil 25 of the mechanical braking device 2.

[0052] <Operation of the Braking Drive Device in the First and Second Embodiments>

[0053] Figure 5 It is a timing chart showing each waveform in the braking drive device of the first embodiment and the second embodiment of the present disclosure.

[0054] Here, the switch 11-1 that opens and closes the circuit between the positive terminal of the power source 16 and the positive terminal of the braking coil 25 is called the "upper side switch", and the switch 11-2 that opens and closes the circuit between the negative terminal of the power source 16 and the negative terminal of the braking coil 25 is called the "lower side switch". In addition, the potential of the power line connecting the upper side switch (switch 11-1) and the positive side terminal of the braking coil 25 detected by the detection unit 14 is called the "upper side detection signal". In addition, the potential of the power line connecting the lower side switch (switch 11-2) and the negative side terminal of the braking coil 25 detected by the detection unit 14 is called the "lower side detection signal". In Figure 5In [the figure], as time passes, the switching signals for turning on and off the upper switch applied by the switch control unit 13, the switching signals for turning on and off the lower switch applied 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 in order from above.

[0055] In Figure 5 , in the initial state from time 0 to time t 1 , the switch control unit 13 outputs a disconnection signal to the upper switch and the lower switch. Therefore, the upper switch and the lower switch perform a disconnection operation to open the circuit between the power supply 16 and the brake coil 25. During the disconnection operation of the upper switch and the lower switch, the current flowing from the power supply 16 toward the brake coil 25 is cut off. Therefore, the braking operation (braking operation state) of the mechanical brake device 2.

[0056] At time t 1 , the switch control unit 13 outputs an on signal to the upper switch and the lower switch. As a result, the upper switch and the lower switch perform an on operation to open the circuit between the power supply 16 and the brake coil 25. During the on operation of the upper switch and the lower switch, current flows from the power supply 16 to the brake coil 25. Therefore, the braking of the mechanical brake device 2 is released (braking release state).

[0057] At time t 1 and later, the mechanical brake device 2 is in a braking release state. During this period, the switch control unit 13 periodically and alternately applies test pulses in which a disconnection signal is instantaneously input during the output of the on signal to the switches 11-1 and 11-2. For example, the switch control unit 13 applies a test pulse in which a disconnection signal TP1 is instantaneously and periodically input during the output of the on signal to the upper switch at times t 3 , t 5 and t 7 . For example, the switch control unit 13 applies a test pulse in which a disconnection signal TP2 is instantaneously and periodically input during the output of the on signal to the lower switch at times t 2 , t 4 and t 6 .

[0058] At time t 1 and later, when the mechanical brake device 2 is in a braking release state, if the upper switch is normal, the upper switch performs a disconnection operation in response to the periodically applied disconnection signal TP1 during the on operation in response to the on signal. As a result, at times t 3 , t 5 and t 7 when the disconnection signal TP1 is applied to the upper switchAt the time point, the potential of the power line connected to the positive terminal of the brake coil 25 changes. The detection unit 14 detects this as the upper detection signal. If the upper switch is normal, the upper detection signal corresponding to the test pulse applied to the upper switch is output from the detection unit 14. Therefore, when the upper detection signal corresponding to the test pulse applied to the upper switch is output, the diagnosis unit 15 determines that the upper switch is normal. On the other hand, when the upper switch fails, the upper switch does not operate normally, so the upper detection signal corresponding to the test pulse applied to the upper switch is not output. Therefore, when the upper detection signal corresponding to the test pulse applied to the upper switch is not output, the diagnosis unit 15 determines that the upper switch has a fault.

[0059] Similarly, at time t 1 After that, when the mechanical brake device 2 is in the brake release state, if the lower switch is normal, the lower switch performs an opening operation in response to the periodically applied opening signal TP2 during the period of the closing operation in response to the closing signal. As a result, at the time t 2 、t 4 And t 6 At the time point, the potential of the power line connected to the negative terminal of the brake coil 25 changes. The detection unit 14 detects this as the lower detection signal. If the lower switch is normal, the lower detection signal corresponding to the test pulse applied to the lower switch is output from the detection unit 14. Therefore, when the lower detection signal corresponding to the test pulse applied to the lower switch is output, the diagnosis unit 15 determines that the lower switch is normal. On the other hand, when the lower switch has a fault, the lower switch does not operate normally, so the lower detection signal corresponding to the test pulse applied to the lower switch is not output. Therefore, when the lower detection signal corresponding to the test pulse applied to the lower switch is not output, the diagnosis unit 15 determines that the lower switch has a fault.

[0060] In this way, when the mechanical brake device 2 is in the brake release state, the switch control unit 13 periodically applies test pulses in which the opening signal is instantaneously input during the output of the closing signal to the switches 11-1 and 11-2 alternately. When the switches 11-1 and 11-2 are normal, at the times t 2 、t 3 、t 4 、t 5 、t 6 And t 7At the time point, the upper switch and the lower switch instantaneously perform a disconnection operation respectively. As a result, the current flowing through the brake coil 25 decreases. When the degree of change (current decrease) of the current in the brake coil 25 is large, the current flowing through the brake coil 25 becomes small, and the electromagnetic force generated in the iron core 26 becomes weak. When the elastic force of the spring 24 overcomes the electromagnetic force generated in the iron core 26, the armature 22 is strongly pressed against the friction plate 21, and the shaft 31 of the motor combined with the friction plate 21 cannot rotate, and the brake malfunctions with respect to the motor. The smaller and lighter the mechanical brake device 2 is, the smaller the energy stored in the brake coil 25 is. Therefore, it is easy to cause a malfunction of the brake of the mechanical brake device 2 caused by the test pulse. Therefore, in the brake drive device 1 of the first embodiment and the second embodiment of the present disclosure, according to the energy stored in the energy storage circuit 12, a current for compensating the current reduction amount of the brake coil 25 is supplied. That is, in the brake release state, even if a test pulse that instantaneously inputs a disconnection signal TP1 in the output of the on-signal is applied to the upper switch 11-1 and the lower switch 11-2, causing the current supplied from the power supply 16 to the brake coil 25 to decrease, since the energy (charge) stored in the energy storage circuit 12 is used to supply current to the brake coil 25, the current change of the brake coil 25 can be suppressed. Thereby, it is 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.

[0061] Figure 6 is a timing chart showing each waveform when the brake drive devices of the first embodiment and the second embodiment of the present disclosure actually operate. In Figure 6 it, the on-off switch signal applied to the upper switch by the switch control unit 13 is represented by a solid line, the voltage applied to the brake coil 25 of the mechanical brake device 2 is represented by a dotted line, and the current flowing through the brake coil 25 of the mechanical brake device 2 is represented by a dashed line.

[0062] As Figure 6 shown, when the mechanical brake device 2 is in the brake release state, at the time point 1 millisecond after the start, the switch control unit 13 applies a test pulse that instantaneously and periodically inputs a disconnection signal TP1 in the output of the on-signal to the upper switch. As a result, the voltage applied to the brake coil 25 temporarily decreases, and accordingly, 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 slow, and then the voltage turns to rise. Accordingly, the current flowing through the brake coil 25 also slowly decreases and then turns to rise. Therefore, the current flowing through the brake coil 25 does not decrease below the malfunction level. Therefore, it is possible to avoid a malfunction of the brake in the brake release state.

[0063] Figure 7It is a timing chart showing waveforms in the case where an existing braking drive device without an energy storage circuit actually operates. In Figure 7 it, the solid line indicates the switching signal for turning on and off the upper switch applied by the switch control unit 13, the dashed line indicates the voltage applied to the brake coil 25 of the mechanical braking device 2, and the dotted line indicates the current flowing through the brake coil 25 of the mechanical braking device 2.

[0064] As Figure 7 shown, when the mechanical braking device 2 is in the brake release state, at the time point 1 millisecond after the start, the switch control unit 13 applies a test pulse in which a disconnection signal TP1 is instantaneously and periodically input during the output of the on-signal to the upper switch. As a result, the voltage applied to the brake coil 25 decreases, and accordingly, the current flowing through the brake coil 25 also decreases. The voltage applied to the brake coil 25 continues to decrease from the start until the time point 3 milliseconds later, and then finally turns to increase. The voltage applied to the brake coil 25 remains in the decreased state for about 2 milliseconds, so the current flowing through the brake coil 25 decreases significantly. The current flowing through the brake coil 25 is lower than the malfunction level at the time point about 1.7 milliseconds after the start, and decreases to around 0 A (zero amperes) at the time point 3 milliseconds after the start. This is because an energy storage circuit is not provided in the braking drive device of the existing example. Since the current flowing through the brake coil 25 is lower than the malfunction level, in the braking drive device of the existing example, a malfunction of the braking of the mechanical braking device 2 caused by the test pulse occurs during the brake release state.

[0065] Comparing Figure 6 and Figure 7 it can be seen that according to the first embodiment and the second embodiment of the present disclosure, by providing the energy storage circuit 12 in the braking drive device 1, it is possible to effectively suppress the current change (current decrease) in the brake coil 25 when the mechanical braking device 2 is released from braking. Therefore, according to the first embodiment and the second embodiment of the present disclosure, it is possible to avoid a braking malfunction in the brake release state.

[0066] The smaller and lighter the mechanical braking device 2 is, the smaller the energy accumulated in the brake coil 25 is, and thus the suppression effect of the current change (current decrease) in the brake coil 25 based on the energy storage circuit 12 becomes greater.

[0067] In addition, for example, in a machine tool, sometimes a motor for mounting a tool is rotated smoothly to machine a workpiece. During the rotation of the motor, the brake is released, and during this period, a failure diagnosis of a switch using a test pulse is performed in the brake drive device. When the brake temporarily malfunctions due to the test pulse although the brake is released, sometimes the rotational speed of the motor decreases, which affects the machining accuracy. In addition, the malfunction of the brake causes excessive wear of the friction plate of the mechanical brake device. According to the first embodiment and the second embodiment of the present disclosure, it is possible to avoid the malfunction of the brake in the brake release state. Therefore, the machining accuracy of the machine tool is not reduced, and the wear of the friction plate can also be suppressed.

[0068] As described above, the present disclosure has been described in detail, but the present disclosure is not limited to the above-described respective embodiments. These embodiments can be variously added, replaced, changed, partially deleted, etc. within the scope not departing from the gist of the present disclosure, or within the scope not departing from the gist of the present disclosure derived from the content described in the scope of the claimed patent and its equivalents. In addition, 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 an example and are not limited thereto. In addition, the same applies to the case where numerical values or mathematical formulas are used in the description of the above-described embodiments.

[0069] <Supplementary Note>

[0070] Regarding the above-described embodiments and modification examples, the following supplementary notes are further disclosed.

[0071] (Supplementary Note 1)

[0072] A brake drive device 1, comprising:

[0073] Switches 11-1 and 11-2, which perform a closing operation to release the brake of the mechanical brake device 2 by allowing current to flow to the mechanical brake device 2, and perform an opening operation to actuate the brake of the mechanical brake device 2 by not allowing current to flow to the mechanical brake device 2; and

[0074] An energy storage circuit 12, which is electrically connected to the mechanical brake device 2 and stores energy,

[0075] Supplies energy for suppressing current changes when the brake of the mechanical brake device 2 is released from the energy storage circuit 12 to the mechanical brake device 2.

[0076] (Supplementary Note 2)

[0077] The brake drive device 1 according to Supplementary Note 1, wherein

[0078] The braking drive device 1 has: a switch control unit 13 that controls the switches 11-1 and 11-2 to perform a disconnection operation for a constant time during the period when the switches 11-1 and 11-2 are turned on to release the braking of the mechanical braking device 2.

[0079] (Supplementary Note 3)

[0080] The braking drive device according to Supplementary Note 2, wherein

[0081] the braking drive device has:

[0082] a detection unit 14 that detects the potential of the power line connecting the switches 11-1 and 11-2 to the mechanical braking device 2 when the switches 11-1 and 11-2 perform a disconnection operation for a constant time during the period when the switches 11-1 and 11-2 are turned on by the control of the switch control unit 13 to release the braking of the mechanical braking device 2; and

[0083] a diagnosis unit 15 that diagnoses whether the switches 11-1 and 11-2 are faulty based on the detection result of the potential by the detection unit 14.

[0084] (Supplementary Note 4)

[0085] The braking drive device 1 according to any one of Supplementary Notes 1 to 3, wherein

[0086] the energy storage circuit 12 has: a capacitor 12-1 that is connected in parallel with the braking coil 25 of the mechanical braking device 2.

[0087] (Supplementary Note 5)

[0088] The braking drive device 1 according to any one of Supplementary Notes 1 to 4, wherein

[0089] the energy storage circuit 12 has: an inductor 12-2 that is connected in series with the braking coil 25 of the mechanical braking device 2.

[0090] (Supplementary Note 6)

[0091] The braking drive device 1 according to any one of Supplementary Notes 1 to 5, wherein

[0092] The mechanical braking device 2 presses the armature 22 against the friction plate 21 coupled to the shaft 31 of the motor by the elastic force of the spring 24, thereby applying braking to the motor, and uses the electromagnetic force generated by the current flowing through the braking coil 25 to pull the armature 22 away from the friction plate 21 to release the braking of the motor.

[0093] Symbol Explanation

[0094] 1 Braking drive device

[0095] 2 Mechanical braking device

[0096] 11-1, 11-2 switches

[0097] 12 Energy storage circuit

[0098] 12-1 Capacitor

[0099] 12-2 Inductor

[0100] 12-3 Current limiting resistor

[0101] 13 Switch control unit

[0102] 14 Detection unit

[0103] 15 Diagnosis unit

[0104] 16 Power supply

[0105] 17 Surge absorber

[0106] 21 Friction plate

[0107] 22 Armature

[0108] 23 End plate

[0109] 24 Spring

[0110] 25 Brake coil

[0111] 26 Iron core

[0112] 27 Spacer

[0113] 28 Bolt

[0114] 31 Shaft

[0115] 32 Hub.

Claims

1. A braking drive device, characterized in that, the braking drive device has: a switch that performs a closing operation to release the braking of the mechanical braking device by allowing current to flow to the mechanical braking device, and performs an opening operation to cause the braking operation of the mechanical braking device by not allowing current to flow to the mechanical braking device; and an energy storage circuit that is electrically connected to the mechanical braking device, stores energy, and supplies energy that suppresses current changes when the braking of the mechanical braking device is released from the energy storage circuit to the mechanical braking device.

2. The braking drive device according to claim 1, characterized in that, the braking drive device has: a switch control unit that controls the switch to perform an opening operation for a constant time during the period when the switch performs a closing operation to release the braking of the mechanical braking device.

3. The braking drive device according to claim 2, characterized in that, the braking drive device has: a detection unit that detects the potential of the power line connecting the switch and the mechanical braking device when the switch performs an opening operation for a constant time during the period when the switch performs a closing operation to release the braking of the mechanical braking device under the control of the switch control unit; and a diagnosis unit that diagnoses whether the switch has a fault based on the detection result of the potential by the detection unit.

4. The braking drive device according to any one of claims 1 to 3, characterized in that, the energy storage circuit has: a capacitor that is connected in parallel with the braking coil of the mechanical braking device.

5. The braking drive device according to any one of claims 1 to 4, characterized in that, the energy storage circuit has: an inductor that is connected in series with the braking coil of the mechanical braking device.

6. The braking drive device according to any one of claims 1 to 5, characterized in that, the mechanical braking device presses an armature against a friction plate coupled to the shaft of a motor by the elastic force of a spring, thereby applying braking to the motor, and pulls the armature away from the friction plate by the electromagnetic force generated when current flows through the braking coil, releasing the braking of the motor.

Images