Brake control circuit, electromagnetic brake control device, electromagnetic brake control system, electromagnetic brake, and electromagnetic brake control method

Abstract

To provide a brake control circuit that can eliminate a time lag from the start of power supply to the start of voltage application to a coil of a non-excitation actuated electromagnetic brake even though it is possible to reduce the power consumption when the electromagnetic brake is in the released state.SOLUTION: When power supply to a brake control circuit 4 is started, the brake control circuit 4 applies, to a coil 3, a first voltage which is a DC voltage that releases an electromagnetic brake and is an input voltage to the brake control circuit 4 for a predetermined time, and then applies, to the coil 3, a second voltage which is a DC voltage that maintains the released state of the electromagnetic brake, and starts the application of the first voltage to the coil 3 in synchronization with the start of power supply. Further, the brake control circuit 4 stops a first drive signal for generating the first voltage when a predetermined time elapses after the start of power supply, and starts to generate a second drive signal to generate the second voltage before the first drive signal is stopped.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a brake control circuit for controlling an electromagnetic brake of non-excitation operation type and a control device for an electromagnetic brake. Further, the present invention relates to a control system for an electromagnetic brake including a control device for an electromagnetic brake. Furthermore, the present invention relates to an electromagnetic brake including a coil to which a DC voltage is applied by a brake control circuit. Also, the present invention relates to a control method for an electromagnetic brake for controlling an electromagnetic brake of non-excitation operation type.

Background Art

[0002] Conventionally, a motor with a brake having an electromagnetic brake of non-excitation operation type is known (see, for example, Patent Document 1). The motor with a brake described in Patent Document 1 includes a DC voltage control circuit electrically connected to a brake coil of the electromagnetic brake. A DC voltage source is electrically connected to the input side of the DC voltage control circuit. Power is supplied from the DC voltage source to the DC voltage control circuit when the relay is opened. On the other hand, when the relay is cut off, the supply of power from the DC voltage source to the DC voltage control circuit stops.

[0003] The DC voltage control circuit includes a reference voltage generation circuit, a switching signal generator, a gate drive circuit, and a switching element. The reference voltage generation circuit generates a reference voltage for controlling the DC voltage actually applied to the brake coil. The switching signal generator generates a switching signal using the output of the reference voltage generation circuit. The switching element performs an on / off operation based on the switching signal input via the gate drive circuit.

[0004] In the motor with a brake described in Patent Document 1, when the electromagnetic brake switches from the braking state in which the braking force of the electromagnetic brake acts to the released state in which the braking force of the electromagnetic brake does not act, power is supplied to the DC voltage control circuit. When power is supplied to the DC voltage control circuit, the DC voltage control circuit applies a first effective voltage to the brake coil in a first voltage pattern of a fixed level in a first period starting from the start of power supply, and releases the electromagnetic brake. Thereafter, the DC voltage control circuit applies a second effective voltage to the brake coil in a second voltage pattern in which rectangular pulses are repeated in a second period following the first period, and maintains the released state of the electromagnetic brake.

[0005] The reference voltage generation circuit generates a first reference voltage for generating the first voltage pattern in the first period and generates a second reference voltage for generating the second voltage pattern in the second period. The second reference voltage is a voltage that can maintain the released state of the electromagnetic brake and is smaller than the first reference voltage. The switching signal generator generates a first switching signal fixed in the on state according to the first reference voltage in the first period and generates a second switching signal that repeats on and off according to the second reference voltage in the second period. The switching element maintains the on state by being driven by the gate drive circuit according to the first switching signal in the first period and performs an on / off operation by being driven by the gate drive circuit according to the second switching signal in the second period.

[0006] In the motor with a brake described in Patent Document 1, since the second effective voltage is lower than the first effective voltage, it is possible to reduce the power consumption of the electromagnetic brake when it is in the released state. Also, in the motor with a brake described in Patent Document 1, when the electromagnetic brake switches from the released state to the braking state, the supply of power to the DC voltage control circuit stops. When the supply of power to the DC voltage control circuit stops, the current flowing through the brake coil rapidly becomes 0, and the electromagnetic brake enters the braking state.

Prior Art Documents

Patent Documents

[0007] [Patent Document 1] Japanese Patent No. 5911639 [Summary of the Invention] [Problems to be Solved by the Invention]

[0008] In the braked motor described in Patent Document 1, as described above, it is possible to reduce the power consumption of the electromagnetic brake when it is in the released state. On the other hand, in the case of this braked motor, generally, since the reference voltage generation circuit is composed of a logic circuit, it has been clarified by the study of the inventor of the present application that a time lag occurs until a voltage is applied to the brake coil after the power supply to the DC voltage control circuit is started. Specifically, after the power supply to the DC voltage control circuit is started, until the input voltage of the DC voltage control circuit reaches a predetermined value and stabilizes, the reference voltage generation circuit is not reset, and the reference voltage generation circuit does not generate the first reference voltage Vf1 (that is, when the input voltage of the DC voltage control circuit stabilizes, the reference voltage generation circuit starts generating the first reference voltage Vf1). Therefore, it has been clarified by the study of the inventor of the present application that an unresponsive time occurs during which the reference voltage generation circuit does not generate the first reference voltage Vf1 after the power supply to the DC voltage control circuit is started (see Fig. 9).

[0009] Also, during the unresponsive time, since the reference voltage generation circuit does not generate the first reference voltage Vf1, the switching signal generator also does not generate the first switching signal (see Fig. 9). As a result, it has been clarified by the study of the inventor of the present application that the switching element also does not operate. Also, during the unresponsive time, since the switching element does not operate, it has been clarified by the study of the inventor of the present application that a time lag corresponding to the unresponsive time occurs until a voltage is applied to the brake coil after the power supply to the DC voltage control circuit is started (see Fig. 9).

[0010] After power supply to the DC voltage control circuit starts, if a time lag occurs until voltage starts to be applied to the brake coil, the time from the start of power supply to the DC voltage control circuit until the electromagnetic brake in the braking state is released becomes long, and it becomes impossible to accurately control the motor with brake at high speed response.

[0011] Therefore, a first problem of the present invention is to provide a brake control circuit and a control method for an electromagnetic brake that can eliminate the time lag until voltage starts to be applied to the coil of the electromagnetic brake after the start of power supply to the brake control circuit that applies DC voltage to the coil of the electromagnetic brake, even if it is possible to reduce the power consumption when the non-excitation operation type electromagnetic brake is in the released state. Further, a first problem of the present invention is to provide an electromagnetic brake including a coil to which a DC voltage is applied by this brake control circuit.

[0012] Also, the motor with brake described in Patent Document 1 may be used, for example, as a drive source for driving the arm of an industrial robot. In this case, the motor with brake is connected to the arm via a speed reducer, for example. When an emergency such as a power failure occurs during the operation of the industrial robot, it is necessary to immediately stop the motor with brake to ensure safety and stop the industrial robot. When immediately stopping the motor with brake described in Patent Document 1, the power supplied to the DC voltage control circuit may be immediately cut off to quickly stop the motor with brake.

[0013] However, when the motor with brake described in Patent Document 1 is connected to the arm via a speed reducer, for example, if the power supplied to the DC voltage control circuit is immediately cut off to quickly stop the motor with brake, an excessive load may act on the speed reducer due to the influence of the inertia moment of the operating arm, and the speed reducer may be damaged.

[0014] Therefore, a second object of the present invention is to provide a control device and a control method for an electromagnetic brake that can suppress an excessive load from acting on a speed reducer or the like connected to a motor even when the motor to which the electromagnetic brake is attached is emergently stopped. Another second object of the present invention is to provide a brake control system including the control device for the electromagnetic brake. Still another second object of the present invention is to provide an electromagnetic brake including a coil to which a DC voltage is applied by a brake control circuit included in the brake control system.

Means for Solving the Problems

[0015] To solve the above-described first problem, a brake control circuit according to the present invention is a brake control circuit for controlling a non-excitation operation type electromagnetic brake that becomes a braking state in which a braking force acts when the coil is in a non-excited state and becomes a released state in which no braking force acts when the coil is in an excited state. When power supply to the brake control circuit is started, a first voltage, which is a DC voltage for releasing the electromagnetic brake and is an input voltage to the brake control circuit, is applied to the coil for a predetermined time, and then a second voltage, which is a DC voltage for maintaining the released state of the electromagnetic brake, is applied to the coil. At the same time, application of the first voltage to the coil is started in synchronization with the start of power supply to the brake control circuit. Further, after a predetermined time has elapsed since the start of power supply to the brake control circuit, a first drive signal stop circuit that stops a first drive signal for generating the first voltage and a second drive signal generation circuit that generates a second drive signal for generating the second voltage are provided. The second drive signal generation circuit is characterized in that it starts generating the second drive signal before the first drive signal stops.

[0016] Also, to solve the above-mentioned first problem, the electromagnetic brake control method of the present invention is an electromagnetic brake control method for controlling a non-excitation operation type electromagnetic brake in which a braking force acts in a braking state when the coil is in a non-excited state and a release state in which the braking force does not act when the coil is in an excited state. When power supply to a brake control circuit that applies a DC voltage to the coil is started, a first voltage, which is a DC voltage for releasing the electromagnetic brake for a predetermined time and is the input voltage to the brake control circuit, is applied to the coil. Thereafter, a second voltage, which is a DC voltage for maintaining the release state of the electromagnetic brake, is applied to the coil. At the same time, the application of the first voltage to the coil is started in synchronization with the start of power supply to the brake control circuit. And after the start of power supply to the brake control circuit, when a predetermined time has elapsed, the first drive signal for generating the first voltage is stopped, and before the first drive signal stops, the second drive signal for generating the second voltage is started to be generated.

[0017] In the present invention, when power supply to the brake control circuit is started, a first voltage, which is a DC voltage for releasing the electromagnetic brake for a predetermined time, is applied to the coil, and thereafter, a second voltage, which is a DC voltage for maintaining the release state of the electromagnetic brake, is applied to the coil. Therefore, in the present invention, it is possible to reduce the power consumption when the non-excitation operation type electromagnetic brake is in the release state. Also, in the present invention, since the application of the first voltage to the coil is started in synchronization with the start of power supply to the brake control circuit, it is possible to eliminate the time lag until a voltage starts to be applied to the coil of the electromagnetic brake after the start of power supply to the brake control circuit. That is, in the present invention, even though it is possible to reduce the power consumption when the non-excitation operation type electromagnetic brake is in the release state, it is possible to eliminate the time lag until a voltage starts to be applied to the coil of the electromagnetic brake after the start of power supply to the brake control circuit.

[0018] In addition, after the start of power supply to the brake control circuit, when a predetermined time has elapsed, the brake control circuit of the present invention includes a first drive signal stop circuit that stops a first drive signal for generating a first voltage, and a second drive signal generation circuit that generates a second drive signal for generating a second voltage. The second drive signal generation circuit starts generating the second drive signal before the first drive signal stops. Further, in the method for controlling an electromagnetic brake of the present invention, after the start of power supply to the brake control circuit, when a predetermined time has elapsed, the first drive signal for generating the first voltage is stopped, and the second drive signal for generating the second voltage is started to be generated before the first drive signal stops. Therefore, in the present invention, it is possible to prevent a situation where no voltage is applied to the coil immediately after the application of the first voltage to the coil. As a result, it is possible to prevent malfunction of the electromagnetic brake.

[0019] In the present invention, for example, the brake control circuit includes a semiconductor switch that performs an on-off operation based on the first drive signal. When the semiconductor switch is in the on state, a voltage is applied to the coil, and the first drive signal is directly generated from the input voltage to the brake control circuit.

[0020] In the present invention, it is preferable that the semiconductor switch performs an on-off operation based on the first drive signal and the second drive signal. With this configuration, as a semiconductor switch that applies a voltage to the coil when in the on state, compared with the case where a semiconductor switch that performs an on-off operation based on the first drive signal and a semiconductor switch that performs an on-off operation based on the second drive signal are provided separately, the configuration of the brake control circuit can be simplified and the cost of the brake control circuit can be reduced.

[0021] In the present invention, the semiconductor switch is a transistor, and it is preferable that a resistor and a capacitor are connected in parallel to the base of the transistor. With this configuration, even if the second drive signal is a PWM (Pulse Width Modulation) signal, it is possible to improve the responsiveness of the transistor.

[0022] Also, in order to solve the above-described second problem, a control device for an electromagnetic brake according to the present invention is a control device for an electromagnetic brake for controlling a non-excitation operation type electromagnetic brake that enters a braking state in which a braking force acts when the coil is in a non-excited state and enters a released state in which no braking force acts when the coil is in an excited state. The control device includes a power source that supplies power for applying a DC voltage to the coil, and when at least the motor to which the electromagnetic brake is attached is to be emergently stopped, the power supply from the power source and the power supply stop that temporarily stops the power supply from the power source are alternately repeated so that the braking state of the electromagnetic brake and the released state of the electromagnetic brake are alternately repeated, and then the power supply from the power source is stopped.

[0023] Also, in order to solve the above-described second problem, an electromagnetic brake control method according to the present invention is an electromagnetic brake control method for controlling a non-excitation operation type electromagnetic brake that enters a braking state in which a braking force acts when the coil is in a non-excited state and enters a released state in which no braking force acts when the coil is in an excited state. When at least the motor to which the electromagnetic brake is attached is to be emergently stopped, the power supply from the power source that supplies power for applying a DC voltage to the coil and the power supply stop that temporarily stops the power supply from the power source are alternately repeated so that the braking state of the electromagnetic brake and the released state of the electromagnetic brake are alternately repeated, and then the power supply from the power source is stopped.

[0024] In the present invention, when at least the motor to which the electromagnetic brake is attached is to be emergently stopped, the power supply from the power source and the power supply stop that temporarily stops the power supply from the power source are alternately repeated so that the braking state of the electromagnetic brake and the released state of the electromagnetic brake are alternately repeated, and then the power supply from the power source is stopped. Therefore, in the present invention, even when the motor is emergently stopped, it becomes possible to stop the motor while gradually decreasing the rotational speed of the motor, and as a result, it becomes possible to prevent the motor from suddenly stopping. Therefore, in the present invention, even when the motor is emergently stopped, it becomes possible to suppress an excessive load from acting on a speed reducer or the like connected to the motor.

[0025] In the present invention, it is preferable that a power supply time, which is the time during which power is supplied from a power source when at least the motor is emergently stopped, and a power supply stop time, which is the time during which the power supply from the power source is temporarily stopped when at least the motor is emergently stopped, can be arbitrarily set. With such a configuration, it becomes possible to set the power supply time and the power supply stop time according to the use and usage environment of the motor to which the electromagnetic brake is attached. Further, for example, when a motor is used as a drive source for an arm of an industrial robot, it becomes possible to adjust the power supply time and the power supply stop time while operating the arm.

[0026] In the present invention, the control device of the electromagnetic brake includes, for example, a second semiconductor switch that performs an on / off operation of the power supply from the power source.

[0027] In the present invention, it is preferable that the power source includes a storage battery in which at least one of the regenerative power of the motor and the power supplied from the original power source to which the power source is connected is stored. With such a configuration, for example, even when a power failure occurs and the motor is emergently stopped, it becomes possible to alternately repeat power supply and power supply stop so that the braking state and the released state of the electromagnetic brake are alternately repeated using the power supplied from the storage battery.

[0028] The control device of the electromagnetic brake of the present invention can be used in a control system of an electromagnetic brake including a brake control circuit that is supplied with power from a power source and applies a DC voltage to a coil. In this control system of the electromagnetic brake, it is preferable that the brake control circuit starts applying a voltage to the coil in synchronization with the start of power supply from the power source to the brake control circuit. With such a configuration, even when power supply and power supply stop are alternately repeated when the motor is emergently stopped, it is possible to eliminate the time lag until a voltage starts to be applied to the coil of the electromagnetic brake after the start of power supply. Therefore, even when the time from the power supply state to the power supply stop state is short when the motor is emergently stopped, it is possible to release the electromagnetic brake, and as a result, it is possible to alternately repeat the braking state and the released state of the electromagnetic brake.

[0029] In the present invention, for example, the brake control circuit includes a semiconductor switch that performs an on-off operation based on a first drive signal for generating a first voltage that is a DC voltage for releasing the electromagnetic brake and is an input voltage from the power source to the brake control circuit. When the semiconductor switch is in the on state, a voltage is applied to the coil, and the first drive signal is directly generated from the input voltage from the power source to the brake control circuit.

[0030] The electromagnetic brake including a coil to which a DC voltage is applied by the brake control circuit of the present invention includes, for example, a control board on which the brake control circuit is mounted. In this case, it is possible to increase the added value of the electromagnetic brake as compared with the case where a control board on which the brake control circuit is mounted is separately provided.

Effect of the Invention

[0031] As described above, in the present invention, even if it is possible to reduce the power consumption when the non-excitation operation type electromagnetic brake is in the released state, it is possible to eliminate the time lag until a voltage starts to be applied to the coil of the electromagnetic brake after the start of power supply to the brake control circuit that applies a DC voltage to the coil of the electromagnetic brake. Further, in the present invention, even when the motor to which the electromagnetic brake is attached is suddenly stopped, it is possible to suppress an excessive load from acting on a speed reducer or the like connected to the motor.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0033] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0034] (Schematic Configuration of Electromagnetic Brake Control System and Configuration of Electromagnetic Brake) FIG. 1 is a block diagram for explaining the schematic configuration of an electromagnetic brake control system 6 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view for explaining the configuration of an electromagnetic brake 2 controlled by a brake control device 1 and a brake control circuit 4 shown in FIG. 1. FIG. 3 is a schematic view for explaining an example of use of the electromagnetic brake 2 shown in FIG. 2.

[0035] The electromagnetic brake control system 6 (hereinafter referred to as "control system 6") of this embodiment is a system for controlling the electromagnetic brake 2, and as a configuration for controlling the electromagnetic brake 2, it includes a brake control device 1 (hereinafter referred to as "control device 1") for the electromagnetic brake and a brake control circuit 4. The electromagnetic brake 2 is a non-excitation operation type electromagnetic brake. When the coil 3 of the electromagnetic brake 2 is in a non-excited state, a braking state in which a braking force acts, and when the coil 3 is in an excited state, a released state in which no braking force acts.

[0036] The electromagnetic brake 2 is attached to and used with a motor 7. The motor 7 is used, for example, as a drive source for driving an arm 8 of an industrial robot. A speed reducer 9 is attached to the output shaft of the motor 7, and the motor 7 is connected to the arm 8 via the speed reducer 9. The electromagnetic brake 2 includes a rotating plate 12 fixed to the rotating shaft of the motor 7 via a boss 11, a brake plate 13 and an armature 14 disposed with the rotating plate 12 interposed therebetween, a compression coil spring 15 that biases the armature 14 toward the rotating plate 12, and a yoke 16 around which the coil 3 is wound.

[0037] When the coil 3 is in a non-excited state, as shown in Fig. 2(A), the rotating plate 12 is sandwiched between the brake plate 13 and the armature 14 by the biasing force of the compression coil spring 15, and the electromagnetic brake 2 is in a braking state. On the other hand, when the coil 3 becomes excited, as shown in Fig. 2(B), the armature 14 is attracted to the yoke 16 against the biasing force of the compression coil spring 15, and the rotating plate 12 becomes rotatable. That is, the electromagnetic brake 2 is in a released state. In this embodiment, the control board 17 on which the brake control circuit 4 is mounted is built into the electromagnetic brake 2. That is, the electromagnetic brake 2 includes the control board 17 on which the brake control circuit 4 is mounted. The control board 17 is, for example, a rigid board such as a glass epoxy board.

[0038] For example, when a motor 7 is used as a drive source for driving the arm 8 of an industrial robot, the control device 1 is included in the control system of the industrial robot and forms a part of the control system of the industrial robot. The control device 1 includes a power supply 5 for supplying power to apply a DC voltage to the coil 3. The power supply 5 supplies power to the brake control circuit 4. Specifically, the power supply 5 is a DC power supply and supplies DC power to the brake control circuit 4. The brake control circuit 4 applies a DC voltage to the coil 3.

[0039] The power supply 5 includes a storage battery 19 used in an emergency such as a power failure. The regenerative power of the motor 7 is stored in the storage battery 19. For example, the regenerative power of the motor 7 when the motor 7 is emergently stopped as described later is stored in the storage battery 19. Or, the power supplied from the original power source to which the power supply 5 is connected is stored in the storage battery 19. Alternatively, the regenerative power of the motor 7 and the power supplied from the original power source are stored in the storage battery 19.

[0040] When releasing the electromagnetic brake 2 in the braking state to the released state, power is supplied from the power source 5 to the brake control circuit 4. That is, the control device 1 supplies power from the power source 5 to the brake control circuit 4. When the power supply from the power source 5 to the brake control circuit 4 is started, the brake control circuit 4 applies a first voltage, which is a DC voltage for releasing the electromagnetic brake 2 and is the input voltage from the power source 5 to the brake control circuit 4, to the coil 3 for a predetermined time T1 (see FIG. 6(A)), and then applies a second voltage, which is a DC voltage for maintaining the released state of the electromagnetic brake 2, to the coil 3. The effective value of the second voltage is lower than the effective value of the first voltage. Hereinafter, the specific configuration and operation of the brake control circuit 4 and the operation of the control system 6 will be described.

[0041] (Configuration and Operation of Brake Control Circuit and Operation of Control System for Electromagnetic Brake) FIG. 4 is a circuit diagram of an example of the brake control circuit 4 shown in FIG. 1. FIG. 5 is a diagram for explaining the function of the brake control circuit 4 shown in FIG. 1. FIG. 6(A) is a waveform diagram for explaining the operation of the brake control circuit 4 during normal use of the motor 7 shown in FIG. 3, and FIG. 6(B) is a waveform diagram for explaining the operation of the control system 6 during emergency stop of the motor 7 shown in FIG. 3.

[0042] The brake control circuit 4 includes a semiconductor switch 23 that performs an on-off operation based on a first drive signal for generating the first voltage and a second drive signal for generating the second voltage, a first drive signal stop circuit 24 that stops the first drive signal when a predetermined time T1 has elapsed after the start of power supply from the power source 5 to the brake control circuit 4, and a second drive signal generation circuit 25 that generates the second drive signal. The semiconductor switch 23 of this embodiment is a transistor. Therefore, hereinafter, the semiconductor switch 23 will be referred to as "transistor 23".

[0043] Transistor 23 is a PNP type transistor. The emitter of transistor 23 is connected to power supply 5, and the collector of transistor 23 is connected to one end of coil 3. No electronic components such as resistors are arranged between the emitter of transistor 23 and power supply 5, and between the collector of transistor 23 and coil 3. The other end of coil 3 is directly grounded. When transistor 23 is turned on, a voltage is applied to coil 3 (that is, a current flows from power supply 5 to coil 3), and when transistor 23 is turned off, the voltage applied to coil 3 disappears. A resistor 27 and a capacitor 28 are connected in parallel to the base of transistor 23. That is, the brake control circuit 4 includes a capacitor 28 connected to the base of transistor 23 in parallel with a resistor 27 connected to the base of transistor 23.

[0044] The first drive signal stop circuit 24 includes a capacitor 30. A transistor 31 is connected to the first drive signal stop circuit 24. Transistor 31 is an NPN type transistor. The collector of transistor 31 is connected to the base of transistor 23 via resistor 27 and capacitor 28. The emitter of transistor 31 is grounded. The base of transistor 31 is connected to power supply 5 via capacitor 30, variable resistor 32 and diode 33.

[0045] When the power supply to the brake control circuit 4 from the power supply 5 is started, for a predetermined time T1 until the capacitor 30 is charged, the current supplied from the power supply 5 to the brake control circuit 4 and flowing through the diode 33, variable resistor 32 and capacitor 30 is input to the base of transistor 31. In this embodiment, the current supplied from the power supply 5 to the brake control circuit 4 and flowing through the diode 33, variable resistor 32 and capacitor 30 becomes the first drive signal for generating the first voltage, and this first drive signal is input to the base of transistor 31.

[0046] Thus, the first drive signal is not a signal output from an integrated circuit or a logic circuit, but a signal directly generated from the input voltage from the power supply 5 to the brake control circuit 4. That is, the first drive signal is directly generated from the input voltage from the power supply 5 to the brake control circuit 4. Therefore, the first drive signal starts to be generated almost simultaneously with the start of power supply from the power supply 5 to the brake control circuit 4. More specifically, the first drive signal starts to be generated immediately when the power supply from the power supply 5 to the brake control circuit 4 is started. That is, the first drive signal starts to be generated in synchronization with the start of power supply from the power supply 5 to the brake control circuit 4. The first drive signal is a continuous signal (analog signal) without on / off.

[0047] After the start of power supply from the power supply 5 to the brake control circuit 4, when a predetermined time T1 has elapsed and the capacitor 30 is charged with electric charge, no current flows into the base of the transistor 31. That is, after the start of power supply from the power supply 5 to the brake control circuit 4, when a predetermined time T1 has elapsed and the capacitor 30 is charged with electric charge, the first drive signal stops (that is, the first drive signal stop circuit 24 stops the first drive signal), and the first drive signal is no longer input to the base of the transistor 31.

[0048] The second drive signal generation circuit 25 includes an oscillation circuit 35. A transistor 36 is connected to the second drive signal generation circuit 25. The transistor 36 is an NPN-type transistor. The collector of the transistor 36 is connected to the base of the transistor 23 via a resistor 27 and a capacitor 28, and the transistor 31 and the transistor 36 are connected in parallel to the base of the transistor 23 via the resistor 27 and the capacitor 28. The emitter of the transistor 36 is grounded. The base of the transistor 36 is connected to the oscillation circuit 35 via a resistor 37.

[0049] The oscillation circuit 35 is a timer IC. When power is supplied from the power source 5 to the brake control circuit 4, the oscillation circuit 35 generates and outputs a second drive signal for generating a second voltage. The second drive signal is a PWM signal that repeats ON and OFF at a predetermined period. The second drive signal is input to the base of the transistor 36. After the power supply from the power source 5 to the brake control circuit 4 is started, when the input voltage of the brake control circuit 4 reaches a predetermined value and a reset is applied to the oscillation circuit 35, the oscillation circuit 35 generates and outputs the second drive signal (see Fig. 6(A)).

[0050] After the start of power supply from the power source 5 to the brake control circuit 4, the oscillation circuit 35 starts generating and outputting the second drive signal before a predetermined time T1 elapses (that is, before the first drive signal stops) (see Fig. 6(A)). That is, the second drive signal generation circuit 25 starts generating the second drive signal before the first drive signal stops. Also, the oscillation circuit 35 generates and outputs the second drive signal until the power supply from the power source 5 to the brake control circuit 4 stops.

[0051] To release the electromagnetic brake 2 in the braking state to the released state, when the power supply from the power source 5 to the brake control circuit 4 is started, the first drive signal is input to the base of the transistor 31 for a predetermined time T1, and the transistor 31 becomes ON. When the transistor 31 becomes ON, a current flows from the emitter of the transistor 23 to the base of the transistor 23, and the transistor 23 becomes ON. Also, since a current flows from the base of the transistor 23 to the transistor 31, the first voltage is applied to the coil 3. That is, the input voltage to the brake control circuit 4 is directly applied to the coil 3. When the first voltage is applied to the coil 3, as shown in Fig. 6(A), the voltage is continuously applied to the coil 3, and the electromagnetic brake 2 becomes the released state.

[0052] As described above, since the first drive signal starts being generated immediately when the power supply from the power source 5 to the brake control circuit 4 is started, when the power supply from the power source 5 to the brake control circuit 4 is started, the transistors 23 and 31 immediately turn on, and immediately after the power supply from the power source 5 to the brake control circuit 4 is started, the application of voltage to the coil 3 is started. That is, the brake control circuit 4 starts applying voltage to the coil 3 in synchronization with the start of the power supply from the power source 5 to the brake control circuit 4. Specifically, the brake control circuit 4 starts applying the first voltage to the coil 3 in synchronization with the start of the power supply from the power source 5 to the brake control circuit 4.

[0053] After the start of the power supply from the power source 5 to the brake control circuit 4, when a predetermined time T1 has elapsed, the first drive signal input to the base of the transistor 31 stops, and the transistor 31 turns off. As described above, since the oscillation circuit 35 generates and outputs the second drive signal before the first drive signal stops, the second drive signal is input to the base of the transistor 36 before the predetermined time T1 has elapsed, and the transistor 36 is in the on state. Therefore, even when the predetermined time T1 has elapsed and the transistor 31 turns off, the on state of the transistor 23 continues.

[0054] Also, after the start of power supply from the power source 5 to the brake control circuit 4, when a predetermined time T1 has elapsed, current flows from the base of the transistor 23 to the transistor 36 without flowing from the base of the transistor 23 to the transistor 31, so that a second voltage is applied to the coil 3. When the second voltage is applied to the coil 3, as shown in FIG. 6(A), the voltage is intermittently applied to the coil 3, and the released state of the electromagnetic brake 2 is maintained. Thus, the transistor 23 is turned on when at least one of the first drive signal and the second drive signal is output, and is turned off when neither the first drive signal nor the second drive signal is output. That is, functionally, in the brake control circuit 4, as shown in FIG. 5, the transistor 23 performs an on / off operation based on the first drive signal and the second drive signal input in parallel. When the electromagnetic brake 2 in the released state is to be brought into the braking state, the control device 1 stops the power supply from the power source 5 to the brake control circuit 4.

[0055] Here, in this embodiment, when an emergency such as a power failure occurs while the electromagnetic brake 2 is in the released state and the motor 7 is rotating (i.e., when the arm 8 is being driven), and the rotating motor 7 is to be stopped immediately, as shown in FIG. 6(B), the control device 1 alternately repeats the power supply from the power source 5 to the brake control circuit 4 and the power supply stop that temporarily stops the power supply from the power source 5 to the brake control circuit 4 so that the braking state and the released state of the electromagnetic brake 2 are alternately repeated, and then stops the power supply from the power source 5 to the brake control circuit 4. When the power supply and the power supply stop are alternately repeated, the voltage is intermittently applied to the coil 3, and when the power supply from the power source 5 to the brake control circuit 4 is stopped, the application of the voltage to the coil 3 is stopped.

[0056] In the control device 1, the power supply time T2, which is the time during which power is supplied from the power supply 5 to the brake control circuit 4 when the motor 7 is emergently stopped, and the power supply stop time T3, which is the time during which the power supply from the power supply 5 to the brake control circuit 4 is temporarily stopped when the motor 7 is emergently stopped, can be arbitrarily set. Further, in the control device 1, the number of times power is supplied to the brake control circuit 4 can also be arbitrarily set before the power supply from the power supply 5 to the brake control circuit 4 is completely stopped. These settings are manually performed by, for example, an operator of an industrial robot in the control device 1.

[0057] In the example shown in FIG. 6(B), power is supplied to the brake control circuit 4 three times before the power supply from the power supply 5 to the brake control circuit 4 is completely stopped. Also, in the example shown in FIG. 6(B), after the start of the emergency stop of the motor 7, the power supply time T2 and the power supply stop time T3 gradually increase. When a power failure occurs and the motor 7 is emergently stopped, power is supplied from the storage battery 19 to the brake control circuit 4.

[0058] (Main effects of this embodiment) As described above, in this embodiment, when the electromagnetic brake 2 in the braking state is released, when the power supply from the power supply 5 to the brake control circuit 4 is started, the brake control circuit 4 applies a first voltage to the coil 3 for a predetermined time T1 to release the electromagnetic brake 2, and then applies a second voltage having an effective value lower than the first voltage to the coil 3 to maintain the released state of the electromagnetic brake 2. Therefore, in this embodiment, it is possible to reduce the power consumption when the electromagnetic brake 2 is in the released state.

[0059] In addition, in this embodiment, since the brake control circuit 4 starts applying the first voltage to the coil 3 in synchronization with the start of power supply from the power supply 5 to the brake control circuit 4, as shown in FIG. 6(A), it is possible to eliminate the time lag from the start of power supply from the power supply 5 until the voltage starts being applied to the coil 3. That is, in this embodiment, even if it is possible to reduce the power consumption when the electromagnetic brake 2 is in the released state, it is possible to eliminate the time lag from the start of power supply from the power supply 5 to the brake control circuit 4 until the voltage starts being applied to the coil 3.

[0060] In this embodiment, the second drive signal generation circuit 25 starts generating the second drive signal before the first drive signal stops. Therefore, in this embodiment, it is possible to prevent a situation where the voltage is not applied to the coil 3 immediately after the application of the first voltage to the coil 3 has ended. Thus, in this embodiment, it is possible to prevent malfunction of the electromagnetic brake 2. Also, in this embodiment, since the capacitor 28 is connected in parallel with the resistor 27 connected to the base of the transistor 23, it is possible to improve the responsiveness of the transistor 23 even if the second drive signal is a PWM signal.

[0061] In this embodiment, when the motor 7 is emergently stopped, the control device 1 alternately repeats the power supply from the power supply 5 to the brake control circuit 4 and the power supply stop that temporarily stops the power supply from the power supply 5 to the brake control circuit 4 so that the braking state and the released state of the electromagnetic brake 2 are alternately repeated, and then stops the power supply from the power supply 5 to the brake control circuit 4. Therefore, in this embodiment, even when the motor 7 is emergently stopped, it is possible to stop the motor 7 while gradually decreasing the rotational speed of the motor 7, and as a result, it is possible to prevent the motor 7 from stopping suddenly. Thus, in this embodiment, even when the motor 7 is emergently stopped, it is possible to suppress the excessive load caused by the inertia moment of the arm 8 from acting on the speed reducer 9.

[0062] Also, in this embodiment, when the motor 7 is emergently stopped, power supply from the power source 5 to the brake control circuit 4 and power supply stop where the power supply from the power source 5 to the brake control circuit 4 is temporarily stopped are alternately repeated. However, in this embodiment, since it becomes possible to eliminate the time lag until the voltage starts to be applied to the coil 3 after the start of power supply from the power source 5 to the brake control circuit 4, when the motor 7 is emergently stopped, even if the power supply time T2 is short, it becomes possible to release the electromagnetic brake 2. As a result, it becomes possible to alternately repeat the braking state and the released state of the electromagnetic brake 2 as linear braking control with an increased operating frequency of 1 / (T2 + T3).

[0063] In this embodiment, the power supply time T2 and the power supply stop time T3 can be arbitrarily set. Therefore, in this embodiment, it becomes possible to set the power supply time T2 and the power supply stop time T3 according to the usage environment of the motor 7 and the like. Also, in this embodiment, it becomes possible to adjust the power supply time T2 and the power supply stop time T3 while operating the arm 8.

[0064] In this embodiment, when a power failure occurs and the motor 7 is emergently stopped, power is supplied from the storage battery 19 to the brake control circuit 4. Therefore, in this embodiment, even when a power failure occurs and the motor 7 is emergently stopped, it becomes possible to intermittently apply a voltage to the coil 3 so that the braking state and the released state of the electromagnetic brake 2 are alternately repeated. Also, in this embodiment, since the control board 17 on which the brake control circuit 4 is mounted is built into the electromagnetic brake 2, it becomes possible to increase the added value of the electromagnetic brake 2 as compared with the case where a control board on which the brake control circuit 4 is mounted is separately provided.

[0065] (Modification example of the electromagnetic brake control device) FIG. 7 is a circuit diagram for explaining the configuration of the control device 1 according to another embodiment of the present invention, and is a diagram in the case where a power on / off circuit 41 for accelerating the on / off of the power supply from the power supply 5 to the brake control circuit 4 is provided. FIG. 8 is a waveform diagram for explaining the operation of the control system 6 when the motor 7 is emergently stopped when the power on / off circuit 41 shown in FIG. 7 is used.

[0066] In the above-described embodiment, the control device 1 may include a power on / off circuit 41 that performs on / off control of the power supply from the power supply 5 to the brake control circuit 4. The power on / off circuit 41 is disposed between the power supply 5 and the brake control circuit 4. The power on / off circuit 41 includes two transistors 42 and 43. The transistor 42 is a PNP-type transistor. The emitter of the transistor 42 is connected to the power supply 5, and the collector of the transistor 42 is connected to the brake control circuit 4. When the transistor 42 is in the on state, power is supplied to the brake control circuit 4, and when the transistor 42 is in the off state, the power supply to the brake control circuit 4 is stopped.

[0067] The transistor 43 is an NPN-type transistor. The collector of the transistor 43 is connected to the base of the transistor 42 via a resistor 44 and a capacitor 45. The emitter of the transistor 43 is grounded. A drive signal is input to the base of the transistor 43. The drive signal is, for example, a rectangular wave on / off signal. The transistor 42 performs an on / off operation of the power supply from the power supply 5 to the brake control circuit 4 in accordance with the drive signal input to the base of the transistor 43. The transistor 42 in this modification is a second semiconductor switch.

[0068] When the control device 1 includes the power on / off circuit 41, the waveform of the input voltage etc. of the brake control circuit 4 when the motor 7 is emergently stopped becomes a waveform as shown in FIG. 8. The power supply time T2 and the power supply stop time T3 when the motor 7 is emergently stopped are determined according to the drive signal input to the base of the transistor 43. When the control device 1 includes the power on / off circuit 41, after the start of power supply from the power supply 5 to the brake control circuit 4, the input voltage of the brake control circuit 4 can be rapidly raised more than when the control device 1 does not include the power on / off circuit 41. Therefore, the voltage applied to the coil 3 can be rapidly raised, and the electromagnetic brake 2 in the braking state can be made into the released state at an earlier time. Thus, in this modification example, even if the power supply time T2 becomes shorter, the electromagnetic brake 2 can be made into the released state. As a result, it becomes possible to realize linear braking control with a further increased operating frequency of 1 / (T2+T3).

[0069] (Other embodiments) In the above-described embodiment, the transistor 23 may be an NPN-type transistor. In this case, for example, the collector of the transistor 23 is connected to one end of the coil 3, and the emitter of the transistor 23 is grounded. Also, the power supply 5 is connected to the other end of the coil 3. For example, the emitters of the transistor 31 and the transistor 36 are connected to the base of the transistor 23. Also, when the transistor 23 is an NPN-type transistor, the first drive signal and the second drive signal may be directly input to the base of the transistor 23.

[0070] In the above-described embodiment, the brake control circuit 4 may be configured such that a time lag occurs after the start of power supply from the power source 5 to the brake control circuit 4 until a voltage starts to be applied to the coil 3. For example, the brake control circuit 4 may be configured like the DC voltage control circuit of Patent Document 1 described above. Even in this case, if the power supply time T2 is long, when the motor 7 is emergently stopped, it becomes possible to release the electromagnetic brake 2, and as a result, it becomes possible to alternately repeat the braking state and the released state of the electromagnetic brake 2.

[0071] In the above-described embodiment, when the motor 7 is emergently stopped, after the start of power supply from the power source 5 to the brake control circuit 4 and after a predetermined time T1 has elapsed, the brake control circuit 4 may be configured to continue applying the first voltage to the coil 3 to maintain the released state of the electromagnetic brake 2.

[0072] In the above-described embodiment, the control system 6 may not include the brake control circuit 4. In this case, a voltage is directly applied from the control device 1 to the coil 3. Even in this case, when the motor 7 is emergently stopped, the control device 1 alternately repeats power supply from the power source 5 to the coil 3 and power supply stop that temporarily stops the power supply from the power source 5 to the coil 3 so that the braking state and the released state of the electromagnetic brake 2 are alternately repeated, and then stops the power supply from the power source 5 to the coil 3. Thus, even when the motor 7 is emergently stopped as in the above-described embodiment, it is possible to suppress an excessive load caused by the inertia moment of the arm 8 from acting on the speed reducer 9.

[0073] In the above-described embodiment, if there is no risk of the speed reducer 9 being damaged even when the motor 7 is suddenly stopped, when the motor 7 is emergently stopped, the power supply to the brake control circuit 4 may be immediately and completely stopped without alternately repeating power supply and power supply stop. In this case, the power supply 5 may not include the storage battery 19. Also, in the above-described embodiment, the semiconductor switch 23 may be other than a transistor. For example, the semiconductor switch 23 may be a MOS-FET or a thyristor having excellent high-speed responsiveness. Further, in the above-described embodiment, if there is no risk of the electromagnetic brake 2 malfunctioning, the oscillation circuit 35 may start generating and outputting the second drive signal at the timing when the first drive signal stops.

[0074] In the above-described embodiment, instead of the transistor 23, the brake control circuit 4 may separately include a transistor that performs an on / off operation based on the first drive signal and a transistor that performs an on / off operation based on the second drive signal. That is, the brake control circuit 4 may separately include a semiconductor switch that performs an on / off operation based on the first drive signal and a semiconductor switch that performs an on / off operation based on the second drive signal as semiconductor switches connected to the coil 3. Also, in the above-described embodiment, the control board on which the brake control circuit 4 is mounted may be installed outside the electromagnetic brake 2. That is, the electromagnetic brake 2 may not include the control board on which the brake control circuit 4 is mounted. Furthermore, in the above-described embodiment, the motor 7 may be used as a drive source for driving something other than the arm 8.

Description of Reference Numerals

[0075] 1 Control device (control device for electromagnetic brake) 2 Electromagnetic brake 3 Coil 4 Brake control circuit 5 Power supply 6 Control system (control system for electromagnetic brake) 17 Control board 19 Storage battery 23 Transistor (semiconductor switch) 24 First drive signal stop circuit 25 Second drive signal generation circuit 27 Resistor 28 Capacitor 42 Transistor (second semiconductor switch) T1 Predetermined time T2 Power supply time T3 Power supply stop time

Claims

1. In a brake control circuit for controlling an electromagnetic brake of the non-excitation operation type, which becomes a braking state in which a braking force acts when the coil is in a non-excited state and becomes a released state in which no braking force acts when the coil is in an excited state, when power supply to the brake control circuit is started, a first voltage, which is a DC voltage for setting the electromagnetic brake to the released state and is an input voltage to the brake control circuit, is applied to the coil for a predetermined time, and then a second voltage, which is a DC voltage for maintaining the released state of the electromagnetic brake, is applied to the coil. In addition, application of the first voltage to the coil is started in synchronization with the start of power supply to the brake control circuit, furthermore, after a predetermined time has elapsed since the start of power supply to the brake control circuit, a first drive signal stop circuit for stopping a first drive signal for generating the first voltage and a second drive signal generation circuit for generating a second drive signal for generating the second voltage are provided, the brake control circuit, wherein the second drive signal generation circuit starts generating the second drive signal before the first drive signal stops.

2. comprising a semiconductor switch that performs an on / off operation based on the first drive signal, when the semiconductor switch is turned on, a voltage is applied to the coil, The brake control circuit according to claim 1, wherein the first drive signal is directly generated from an input voltage to the brake control circuit.

3. The brake control circuit according to claim 1 or 2, wherein the semiconductor switch performs an on / off operation based on the first drive signal and the second drive signal.

4. the semiconductor switch is a transistor, The brake control circuit according to claim 3, wherein a resistor and a capacitor are connected in parallel to the base of the transistor.

5. In a control device for an electromagnetic brake for controlling an electromagnetic brake of the non-excitation operation type, which becomes a braking state in which a braking force acts when the coil is in a non-excited state and becomes a released state in which no braking force acts when the coil is in an excited state, A control device for an electromagnetic brake, comprising a power source that supplies power for applying a DC voltage to the coil, and when at least emergency stopping the motor to which the electromagnetic brake is attached, power supply from the power source and power supply stop for temporarily stopping the power supply from the power source are alternately repeated so that the braking state and the release state of the electromagnetic brake are alternately repeated, and then the power supply from the power source is stopped.

6. The control device for an electromagnetic brake according to claim 5, wherein a power supply time, which is the time during which power is supplied from the power source when at least emergency stopping the motor, and a power supply stop time, which is the time during which the power supply from the power source is temporarily stopped when at least emergency stopping the motor, can be arbitrarily set.

7. The control device for an electromagnetic brake according to claim 5 or 6, comprising a second semiconductor switch that performs an on / off operation of the power supply from the power source.

8. The control device for an electromagnetic brake according to any one of claims 5 to 7, wherein the power source includes a storage battery that stores at least one of the regenerative power of the motor and the power supplied from the original power source to which the power source is connected.

9. A control system for an electromagnetic brake, comprising the control device for an electromagnetic brake according to any one of claims 5 to 8, and a brake control circuit that is supplied with power from the power source and applies a DC voltage to the coil. The brake control circuit starts applying a voltage to the coil in synchronization with the start of power supply from the power source to the brake control circuit.

10. The brake control circuit includes a semiconductor switch that performs an on / off operation based on a first drive signal for generating a first voltage, which is a DC voltage for setting the electromagnetic brake in the release state and is an input voltage from the power source to the brake control circuit. When the semiconductor switch is in the on state, a voltage is applied to the coil. The control system for an electromagnetic brake according to claim 9, wherein the first drive signal is directly generated from the input voltage from the power source to the brake control circuit.

11. An electromagnetic brake comprising a coil to which a DC voltage is applied by the brake control circuit according to any one of claims 1 to 4, or the brake control circuit according to claim 9 or 10. An electromagnetic brake, characterized in that a control board on which the brake control circuit is mounted is built in.

12. In a method for controlling an electromagnetic brake for controlling a non-excitation operation type electromagnetic brake in which a braking force acts in a braking state when the coil is in a non-excited state and the braking force does not act in a released state when the coil is in an excited state, when power supply to a brake control circuit for applying a DC voltage to the coil is started, a first voltage, which is a DC voltage for setting the electromagnetic brake in the released state and is an input voltage to the brake control circuit, is applied to the coil for a predetermined time, and then a second voltage, which is a DC voltage for maintaining the released state of the electromagnetic brake, is applied to the coil. At the same time, application of the first voltage to the coil is started in synchronization with the start of power supply to the brake control circuit, and when a predetermined time has elapsed after the start of power supply to the brake control circuit, the first drive signal for generating the first voltage is stopped, and starting from before the first drive signal stops, a second drive signal for generating the second voltage is started to be generated. A method for controlling an electromagnetic brake, characterized by this.

13. In a method for controlling an electromagnetic brake for controlling a non-excitation operation type electromagnetic brake in which a braking force acts in a braking state when the coil is in a non-excited state and the braking force does not act in a released state when the coil is in an excited state, when at least the motor to which the electromagnetic brake is attached is to be emergently stopped, power supply from a power source for supplying power for applying a DC voltage to the coil and power supply stop for temporarily stopping the power supply from the power source are alternately repeated so that the braking state of the electromagnetic brake and the released state of the electromagnetic brake are alternately repeated, and then the power supply from the power source is stopped. A method for controlling an electromagnetic brake, characterized by this.

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