Brake circuit discharge system

Abstract

An object of the present invention is to provide a brake circuit discharge system capable of rapidly and reliably stopping a power source. The brake circuit discharge system (100) involved in the present invention comprises: a motor drive circuit (101) that drives a motor (M); a brake drive circuit (102) that drives a brake (B) that decelerates and stops the drive of the motor (M), and activates the brake when the power is cut off; a control unit (103) that controls the operation of the motor drive circuit (101) and the brake drive circuit (102); a capacitor (106) that is connected to the power line of the brake drive circuit (102); a discharge resistor (108) that is connected to the power line of the brake drive circuit (102) in parallel with the capacitor (106) to discharge the charge accumulated in the capacitor (106); a discharge switching switch (109) that is connected in series with the discharge resistor (108); and a discharge instruction generation circuit (110) that is connected to the discharge switching switch (109) and generates a switching instruction signal for switching the discharge switching switch (109) on and off.

Description

Technical Field

[0001] The present invention relates to a brake circuit discharge system, and more particularly to a brake circuit discharge system including a power source such as a motor, a brake for decelerating and stopping the drive of the power source, and a control unit for controlling the operations of the brake circuit discharge system. Background Art

[0002] Conventionally, a motor or a robot equipped with a motor as a power source has a separate control board, and a driver in the control board adjusts the power supplied to the motor to control the rotation of the motor. However, in recent years, devices in which the driver is built into the motor or robot have been introduced.

[0003] When receiving a command from a control panel or the like through communication, such a built-in driver motor adjusts the power supplied to the motor to control the rotation speed of the motor or activates the brake. In particular, the deceleration stop uses the following methods: (1) the driver activates the brake drive system to activate the brake to stop the rotation of the motor; (2) the driver adjusts the power supplied to the motor to apply a force opposite to the rotation direction to stop the rotation of the motor; or (3) the driver makes the power supplied to the motor zero to stop the rotation of the motor.

[0004] For example, Patent Document 1 describes a control device having a power cut-off function, in which the power of the servo motor drive system is cut off by operating an emergency stop switch in an emergency, and the brake drive system is actuated to stop the robot arm of the multi-axis robot. In this way, the drive motor of the multi-axis robot can be stopped safely and reliably.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 5552564 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] However, in a motor with a built-in driver, when considering the situation where the driver fails or the communication line used for communication is disconnected, there is a possibility that the brake is not activated and the motor continues to rotate in the above situation (1). In addition, there is a possibility that the power supply is not properly adjusted in the form of applying force in the direction of rotation or insufficient power is supplied by applying force opposite to the direction of rotation, making the motor uncontrollable. In the above situation (3), there is a possibility that the power to the motor cannot be cut off and the power supply continues. As a result, it is considered that the robot is in a dangerous state such as losing control of the arm falling without initiating an emergency stop.

[0010] In order to solve this problem, it is recommended that when the motor is stopped, the above-mentioned deceleration stop is performed, and the power of the built-in driver motor is cut off in the same manner as the power cut-off device of Patent Document 1, thereby making the power supply to the motor completely 0. However, even if the power is cut off, unlike the power cut-off device of Patent Document 1, there is residual charge in the capacitor in the built-in driver, so although it exists for a short time, it forms a state of residual power in the built-in driver motor, and the motor cannot be stopped reliably.

[0011] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a brake circuit discharge system capable of stopping a power source quickly and reliably.

[0012] Solutions for solving problems

[0013] In order to solve the above-mentioned problems, the brake circuit discharge system involved in the present invention comprises: a motor drive circuit, which drives a motor; a brake drive circuit, which drives a brake that decelerates and stops the drive of the motor, and activates the brake when the power is cut off; a control unit, which controls the operation of the motor drive circuit and the brake drive circuit, and continuously sends a brake release signal to the brake drive circuit; a capacitor, which is connected to the power line of the brake drive circuit and the power line of at least one of the control unit; a discharge resistor, which is connected to the power line connected to the capacitor, and discharges the charge accumulated in the capacitor; a discharge switching switch, which is connected in series with the discharge resistor; and a discharge instruction generating circuit, which is connected to the discharge switching switch, and generates a switching instruction signal for switching the discharge switching switch on and off.

[0014] Effects of the Invention

[0015] According to the brake circuit discharge system of the present invention, the charge accumulated in the circuit driving the brake is discharged, and the power source can be stopped quickly and reliably. In addition, the effect described here is not necessarily limited, and it can also be any effect described in the present technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a block diagram showing the configuration of a brake circuit discharge system according to the first embodiment of the present invention.

[0017] Figure 2 This is a graph for explaining the operation of the brake circuit discharge system according to the first embodiment of the present invention during emergency stop.

[0018] Figure 3 This is a graph for explaining the operation of the brake circuit discharge system according to the first embodiment of the present invention during emergency stop.

[0019] Figure 4 1 is a block diagram showing the configuration of a conventional brake circuit discharge system.

[0020] Figure 5 This is a graph for explaining the operation of a conventional brake circuit discharge system during an emergency stop.

[0021] Figure 6 It is a block diagram showing the configuration of a brake circuit discharge system according to a second embodiment of the present invention.

[0022] Figure 7 This is a graph for explaining the operation of the brake circuit discharge system according to the second embodiment of the present invention during emergency stop.

[0023] Figure 8 It is a block diagram showing the configuration of a brake circuit discharge system according to a third embodiment of the present invention.

[0024] Fig. 9 It is a block diagram showing the configuration of a brake circuit discharge system according to a fourth embodiment of the present invention.

[0025] Fig.10 This is a graph for explaining the operation of the brake circuit discharge system according to the fourth embodiment of the present invention during emergency stop.

[0026] Fig.11 It is a block diagram showing the configuration of a brake circuit discharge system according to a fifth embodiment of the present invention.

[0027] Fig.12 This is a graph for explaining the operation of the brake circuit discharge system according to the sixth embodiment of the present invention during emergency stop. DETAILED DESCRIPTION

[0028] Below, while referring to the attached Figure 1 The embodiment described below is an example of a representative embodiment of the present invention, and the scope of the present invention is not to be interpreted narrowly.

[0029] <First Embodiment>

[0030] First, a brake circuit discharge system 100 according to a first embodiment of the present invention will be described. Figure 1 is a block diagram showing the structure of the brake circuit discharge system 100 according to the present embodiment. Figure 1 The circuit structure in each frame is simplified for illustration. Figure 1 In the figure, only the blocks related to the present invention are illustrated, and the blocks required for other systems are omitted.

[0031] like Figure 1 As shown in the example, the actuator for which the brake circuit discharge system 100 is a target includes at least: a motor drive circuit 101 for controlling the operation of the motor M and the motor M to drive them; a brake drive circuit 102 for controlling the operation of the brake B and the brake B; and a control unit 103 for controlling the operation of the motor drive circuit 101 and the brake drive circuit 102. The motor drive circuit 101 has an inverter 104 for converting direct current into alternating current. In addition, the motor drive circuit 101, the brake drive circuit 102, and the control unit 103 are collectively referred to as a driver unit. In addition, in each of the motor drive circuit 101, the brake drive circuit 102, and the control unit 103, there is an electrostatic capacitor such as a capacitor or a circuit pattern installed to stabilize the operation, and each electrostatic capacitor is respectively referred to as a motor drive circuit capacitor 105, a brake drive circuit capacitor 106, and a control unit capacitor 107. The motor drive circuit capacitor 105 , the brake drive circuit capacitor 106 , and the control unit capacitor 107 are connected to power lines of the motor drive circuit 101 , the brake drive circuit 102 , and the control unit 103 , respectively.

[0032] With respect to such an actuator, the brake circuit discharge system 100 according to the present embodiment includes a discharge resistor 108 for discharging the charge accumulated in each capacitor 105 to 107, a discharge switching switch 109, and a discharge command generation circuit 110, which are inserted in parallel with the brake drive circuit capacitor 106. The discharge resistor 108 of the present embodiment is connected in parallel with the brake drive circuit capacitor 106 to the power line to which the brake drive circuit capacitor 106 is connected.

[0033] In addition, Figure 1In the present embodiment, although it is not an essential element of the present invention, the following elements are generally included as elements of the actuator. The brake circuit discharge system 100 involved in the present embodiment includes: a driver for receiving a user's command to control the operation of the actuator or control the power supply as instructed; a power cut-off switch 113 for opening and closing the power supply from the power supply 112; converters 114, 115, and 116, which convert the power supply voltage into appropriate voltages that correspond to the motor drive circuit 101, the brake drive circuit 102, and the control unit 103, respectively; and a diode unit 117, which prevents the regenerative power from the motor M from flowing back to the converter 114 or the power supply 112 and causing a circuit failure. In addition, generally speaking, a capacitor for stabilizing the output voltage and a capacitor for stabilizing the input voltage are connected to the converters 114, 115, and 116, but for the sake of simplicity of explanation, it is assumed that the capacitors are included in the motor drive circuit capacitor 105, the brake drive circuit capacitor 106, and the control unit capacitor 107, and the explanation is separately provided as needed.

[0034] Next, the components of the brake circuit discharge system 100 according to the present embodiment will be described in more detail below.

[0035] The motor M converts electric power into mechanical energy, and its principle and structure are not particularly limited. For example, it is a motor called a rotary motor such as a DC motor or an AC motor, or a motor called a direct-acting motor using a solenoid coil.

[0036] The motor drive circuit 101 is not particularly limited as long as it has a function of adjusting the rotation amount or rotation speed of the motor M based on the signal of the control unit 103. In addition, the method of adjusting the rotation amount or rotation speed of the motor M may be a method of changing the voltage or current supplied to the motor M, or a method of changing the period of a short pulse such as PWM. Furthermore, in particular, when it is not necessary to adjust the rotation amount or rotation speed of the motor M, the motor drive circuit 101 may not be used.

[0037] The brake B is used to apply a load to the motor M or a movable part connected to the motor M to stop the rotation of the motor M and decelerate and stop the drive of the motor M. The principle and shape thereof are not particularly limited. For example, a brake using electromagnetic force such as an electromagnetic brake, or a brake using friction force such as a disc brake or a drum brake can be used.

[0038] The brake drive circuit 102 is used to operate whether to apply the brake B to drive the brake based on a signal from the control unit 103. As a simple drive circuit, a switch for switching the power supply to the brake B may also be used.

[0039] However, the brake B and the brake driving circuit 102 must activate the brake B when the power is cut off and enter the brake release state when the power is supplied. For example, if it is a disc brake, the motor M or the movable part connected to the motor M is clamped by the disc brake when the power is cut off to enter the brake activation state, and the disc brake is released when the power is supplied to enter the brake release state.

[0040] The control unit 103 may be a module that controls the motor M or the brake B by sending a signal to the motor drive circuit 101 or the brake drive circuit 102 based on a signal received from the controller 111, and its principle or structure is not particularly limited. In addition, the controller 111 may be a controller that includes the functions of the control unit 103, or may be included in the motor drive circuit 101 or the brake drive circuit 102. However, it is desirable that the signal from the control unit 103 to the brake drive circuit 102 activates the brake B when the power supply to the control unit 103 is cut off.

[0041] As an example, the discharge resistor 108 is connected in parallel with the brake drive circuit capacitor 106 between the brake drive circuit capacitor 106 and the converter 115. Such a discharge resistor 108 is a resistor commonly used in circuits, which limits the current and causes a voltage drop according to the applied voltage, and consumes energy corresponding to the current and voltage drop. Its shape or material is not particularly limited. However, in order to discharge the charge accumulated in the brake drive circuit capacitor 106 as the purpose of the discharge resistor 108, it can also be a resistor with a resistance value as small as possible, preferably more than 1Ω and less than 1000Ω. Specifically, the resistance value is designed so that the product of the discharge resistor 108 and the brake drive capacitor 106 is less than the time required for the discharge to be completed. For example, when the time required for the discharge to be completed is 1 millisecond and the electrostatic capacitance of the brake drive capacitor 106 is 10 microfarads (μF), the resistance value of the discharge resistor 108 is less than 10Ω. In addition, since a large current flows instantaneously when the charge is discharged, a resistor with impact resistance is preferred. Although detailed description is omitted in this specification, the discharge resistor 108 is not limited to a resistor, and may be any element that consumes electric power and converts it into other energy. For example, an LED may be used to convert electric power into light energy.

[0042] The discharge switching switch 109 is connected in series between the discharge resistor 108 and the ground. The discharge switching switch 109 is used to switch whether to form a closed circuit through the discharge switching switch discharge resistor 108 and the brake drive circuit capacitor 106, and its shape, material, and principle are not particularly limited. For example, a semiconductor switch such as a transistor or an electromagnetic relay is cited, but in order to discharge the charge accumulated in the brake drive circuit capacitor 106 as early as possible at the necessary moment, a semiconductor switch with a fast response speed from receiving the discharge switching instruction to switching the switch is desired. In addition, the drive circuit required for the switch switching is not shown in the figure but is included in the discharge switching switch 109 as needed.

[0043] The output side of the discharge instruction generation circuit 110 is connected to the discharge switching switch 109, and the discharge instruction generation circuit 110 generates a switching instruction signal for switching the discharge switching switch 109 on and off. The discharge instruction generation circuit 110 is used to determine the moment when the discharge switching switch 109 switches the open and closed state, thereby performing the switching, and its shape, material, and principle are not particularly limited. For example, it can also be implemented by using a logic IC, a logic circuit of a diode, or a comparison circuit using a comparator, or by software processing included in the above-mentioned controller, control unit, external microcomputer, etc. The input side of the discharge instruction generation circuit 110 can be connected to the reaction part after issuing an instruction (emergency stop or stop command) when the user wants to stop. For example, in Figure 1 In the embodiment, the input side of the discharge instruction generating circuit 110 can be connected to the instruction, the controller 111, the input side of the power cut-off switch 113, the auxiliary contact of the power cut-off switch 113, the output side of the power cut-off switch 113, the control unit 103 or the input side of the brake drive circuit 102.

[0044] The controller 111 is used to control each part based on the instructions from the user. Generally speaking, it has the function of opening and closing the power cut-off switch 113 and converting the instructions from the user into the instruction value of the control unit 103. The controller 111 is connected to the control unit 103 and the power cut-off switch 113. The control signal from the controller 111 to each part can use any signal such as a logic signal or a communication signal. In this embodiment, for the purpose of explanation, the dotted line is set as a logic signal, and the square arrow is set as a communication signal. In addition, the bold lines are the power lines.

[0045] The power cut-off switch 113 is used to receive a signal from the controller and switch the power supplied from the power supply 112 to the subsequent stage on and off according to the signal. Generally speaking, a switch having a mechanical contact such as a circuit breaker, a relay, an electromagnetic switch or an electromagnetic switch, or a semiconductor switch such as a FET or an IGBT can be used, but it is not limited to these, and any switch can be used as long as it can be switched. In addition, for the sake of convenience of explanation, the power cut-off switch 113 is set to receive a signal from the controller 111 to switch, but it can also be a structure that can be directly operated by the user, or it can be operated by a signal from the control unit 103. In addition, although the drive circuit required for the switch switching is not shown in the figure, it is set to be included in the power cut-off switch 113. In addition, it is expected that there is a component called an auxiliary contact in the electromagnetic switch, etc. that changes the open and closed state in accordance with the state of the switch.

[0046] The converters 114 to 116 are modules for converting input voltage into any output voltage, and also realize functions such as converting AC into DC. The converters 114 to 116 of this embodiment are used to convert the voltage supplied from the power supply 112 into the voltages existing in the motor drive circuit 101, the brake drive circuit 102, and the control unit 103. In addition, the converters 114 to 116 are respectively called the motor drive circuit converter 114 connected in series to the power line of the motor drive circuit 101, the brake drive circuit converter 115 connected in series to the power line of the brake drive circuit 102, and the control unit converter 116 connected in series to the power line of the control unit 103. If the voltage of the power supply 112 meets the rated input voltage of each part, the converters 114 to 116 are not required, and the components with the same rated input voltage in the motor drive circuit 101, the brake drive circuit 102, and the control unit 103 can be put together. Furthermore, a multi-stage connection structure may be adopted in which the output of the motor drive circuit converter 114 is used as the input of the brake drive circuit converter 115 .

[0047] The diode unit 117 is a rectifying element for protecting the regenerative power generated in the motor M from flowing back and damaging the power supply 112 or the converter 114 when the motor M stops or decelerates. The diode unit is not particularly necessary as long as the regenerative power is small enough to cause no problem.

[0048] Next, the timing at which the discharge switching switch switches the open and closed states will be described below.

[0049] The object of the present invention is to drive the brake of the actuator quickly and reliably. To this end, the discharge instruction generation circuit 110 needs to output the discharge instruction to the discharge switching switch 109 in accordance with the moment when the brake B is to be driven. In the driving of the brake B, there is first a control stop performed in normal times. In the present embodiment, after receiving the instruction to start the brake B from the user, the controller 111 sends a brake start instruction to the control unit 103 to drive the brake B. Then, the control unit 103 controls the brake drive circuit 102, so that the brake B is started. In this case, any one of the instructions from the user to the controller 111, the instructions from the controller 111 to the control unit 103, and the instructions from the control unit 103 to the brake drive circuit 102 can be used as the input of the discharge instruction generation circuit 110. This is because: since the instructions are sent to each part from the time when the brake B is to be started to the time when the brake B is started, the above instructions can be monitored in order to know the moment when the brake B is to be started.

[0050] Next, the emergency stop performed in an emergency is described. The emergency stop is an action that gives priority to stopping all actuators when the actuator cannot be controlled or when there is a possibility of harm to people. It is basically the same as the above-mentioned control stop action, but the biggest difference is that the controller 111 sends a power cut-off command to the power cut-off switch 113 to cut off the power supply 112. In addition, there is also an action of cutting off the power supply 112 and performing a control stop at the same time depending on the product, but the brake circuit discharge system 100 is also effective in this case. In this embodiment, a case where a control stop is also performed during an emergency stop is described.

[0051] The purpose of cutting off the power supply 112 in this way is that even if any of the elements related to the brake operation, such as the control unit 103 or the brake drive circuit 102, fails, the power supply to the motor M is stopped and the motor M does not move, and the power supply to the brake drive circuit 102 is stopped so that the brake release state cannot be maintained, thereby actuating the brake B.

[0052] However, even if the power supply is stopped, when the charge is accumulated in the brake drive circuit capacitor 106 as described above, the charge accumulated in the brake drive circuit capacitor 106 is supplied to the brake drive circuit 102 during this period, and the brake release state can be maintained. Therefore, as long as the discharge switching switch 109 is immediately closed to discharge the charge accumulated in the brake drive circuit capacitor 106, the power used to operate the brake drive circuit 102 disappears quickly, and the time before the brake B is activated can be shortened.

[0053] That is, except for the case of control stop, as the input of the discharge instruction generation circuit 110, a power cut-off instruction from the controller 111 to the power cut-off switch 113 or a voltage drop on the output side of the power cut-off switch 113 may be used as a trigger. However, since electric charge is accumulated in the electrostatic capacitance component of the input stage of the converter 114, etc., the output voltage of the power cut-off switch 113 does not drop instantaneously even after the power is cut off. Therefore, when the drop in the output voltage of the power cut-off switch 113 is used as a trigger, it takes time to reach the threshold voltage value that is judged as a voltage drop. That is, there are problems such as a delay relative to the time when the emergency stop is actually desired, or there are problems such as a voltage drop that would not have been caused in the case of a failure of the power cut-off switch 113. Therefore, it is desirable to use the power cut-off instruction of the controller 111 or the stop instruction from the user.

[0054] Furthermore, when the power cut-off switch 113 fails, even if the discharge switching switch 109 is closed, the power supplied from the converter 115 is consumed only by the discharge resistor 108, thereby a state where sufficient power is supplied to release the brake can be achieved. In this case, it is desirable to use the output of the discharge command generation circuit 110 to stop the operation of the converter 115, etc., and to add a switch that cuts off the power to the brake B differently from the power cut-off switch 113 to enable power cut-off. In addition, in the above description, although power cut-off is cited as the difference between control stop and emergency stop, it is not necessarily necessary to distinguish them, and power cut-off can also be performed during control stop.

[0055] Therefore, the brake circuit discharge system will be described below by taking the operation during emergency stop in the present embodiment as an example.

[0056] First, in Figure 2 ] shows the state at each point after time t from the generation of the emergency stop signal in a normal state where there is no fault anywhere. Figure 2 This is a graph for explaining the operation of the brake circuit discharge system 100 involved in this embodiment during emergency stop. However, the delay amount caused by the communication time or the operation time varies depending on the components or control method used. Therefore, although it may not be the timing as described in this specification and there may be some deviation, the effect of this embodiment will not be damaged due to this deviation.

[0057] First, an emergency stop signal is generated at time t0. Then, at time t1, the controller 111 that receives the emergency stop signal sends a discharge signal to the discharge instruction generation circuit 110, sends a brake start command to the control unit 103, and sends a power cut-off signal to the power cut-off switch 113. At this time, the discharge instruction generation circuit 110 that receives the discharge signal closes the discharge switching switch 109 to form a state in which current flows to the discharge resistor 108. Then, the input voltage of the brake drive circuit 102 begins to drop, but since power is supplied from the converter for the brake drive circuit, the voltage drops slowly. Here, the power cut-off signal and the discharge signal are described as logic signals, and the brake start command is described as a communication signal, but the effect of the present invention is not impaired by the type of signal as described above.

[0058] Next, at time t2 , the control unit, having received the brake start command, sends a brake signal to the brake drive circuit 102 to activate the brake B.

[0059] Furthermore, at time t3, the brake driving circuit 102 receives the brake signal and releases the brake to activate the brake B, and the motor M starts to decelerate.

[0060] Then, at time t4, the power cut-off switch 113, which has received the power cut-off signal, cuts off the power supply to each converter 114 to 116. Then, the power supply from the brake drive circuit converter 115, which has been supplying the energy consumed by the discharge resistor 108, is lost, and the charge accumulated in the brake drive circuit capacitor 106 is consumed by the discharge resistor 108. As a result, the input voltage of the brake drive circuit 102 drops sharply.

[0061] Furthermore, at time t5, the input voltage of the brake drive circuit 102 decreases to the point where the brake release state cannot be maintained. However, since the brake has already been applied at time t3, the state does not change particularly.

[0062] Furthermore, at time t6, the charge of the capacitor of the brake drive circuit disappears and the input voltage of the brake drive circuit 102 becomes 0, but the state does not change in particular.

[0063] Finally, at time t7, the rotation speed of the motor M is 0, and the actuator is in a completely stopped state.

[0064] In addition, in this example, the case where brake B is started based on a brake start signal is described. However, the input voltage of the brake drive circuit 102 is lower than the voltage required to release brake B due to the delay before the brake start signal reaches the brake drive circuit 102, the speed of voltage drop of the input voltage of the brake drive circuit 102, and the delay of the power cut-off switch 109. As a result, there is a case where the brake is started. However, the present invention is also effective in such a case.

[0065] Next, in order to explain the effects of the present invention, a state in which a failure occurs in the control unit 103 in the present embodiment will be described. Figure 3 This is a graph for explaining the operation at the time of emergency stop in the brake circuit discharge system 100 according to the present embodiment. Figure 3 The status at each point after time t from the generation of the emergency stop signal is shown.

[0066] First, an emergency stop signal is generated at time t0. Then, at time t1, the controller 111 that receives the emergency stop signal sends a brake start command to the control unit 103, sends a power cutoff signal to the power cutoff switch 113, and sends a discharge signal to the discharge instruction generation circuit 110. At this time, the discharge instruction generation circuit 110 that receives the discharge signal closes the discharge switching switch 109 so that current flows to the discharge resistor 108. Then, the input voltage of the brake drive circuit 102 begins to drop, but since power is supplied from the brake drive circuit converter 115, the voltage drops slowly.

[0067] Next, at time t2, the control unit 103 receiving the brake start command should send a brake signal to the brake drive circuit 102 to activate the brake B. However, since a failure occurs in the control unit 103, the brake signal is not sent.

[0068] That is, even at time t3 , the brake drive circuit 102 does not receive the brake signal, and therefore the brake release state continues, the brake B is not actuated, and the motor M does not decelerate.

[0069] On the other hand, at time t4, the power cut-off switch 113, which has received the power cut-off signal, cuts off the power supply to each converter 114 to 116. Then, the power supply from the brake drive circuit converter 115, which has been supplying the energy consumed by the discharge resistor 108, is lost, and the charge accumulated in the brake drive circuit capacitor 106 is consumed by the discharge resistor 108. As a result, the input voltage of the brake drive circuit 102 begins to drop sharply.

[0070] Furthermore, at time t5, the brake drive circuit input voltage drops to a level that makes it impossible to maintain the brake release state. As a result, the brake release is cancelled and the brake B is activated, and the motor M starts to decelerate.

[0071] At time t6, the charge of the brake drive circuit capacitor 106 disappears, and the input voltage of the brake drive circuit 102 becomes 0, but there is no particular change in this state.

[0072] Finally, when time t7 elapses and time t8 comes, the rotation speed of the motor becomes 0, and the actuator is in a completely stopped state.

[0073] As described above, although it takes time compared to a normal state, the brake circuit discharge system 100 can completely stop the actuator.

[0074] <Previous example>

[0075] In order to make the effects of the present invention more clearly understood, conventional examples will be described below. Figure 4 is a block diagram showing the structure of a conventional brake circuit discharge system. Figure 4 In the figure, the circuit structure in each frame is simplified for illustration.

[0076] The actuator to which the brake circuit discharge system 400 is applied is similar to the brake circuit discharge system 100 of the first embodiment, and is composed of a motor M, a motor drive circuit 401, a brake B, a brake drive circuit 402, and a control unit 403. The motor drive circuit 401 includes an inverter 404. In addition, a motor drive circuit capacitor 405, a brake drive circuit capacitor 406, and a control unit capacitor 407 are installed in the motor drive circuit 401, the brake drive circuit 402, and the control unit 403, respectively.

[0077] In addition, the brake circuit discharge system 400 involved in the previous example includes: a controller 411; a power cut-off switch 413, which is used to open and close the power supply from the power supply 412; converters 414, 415, 416, which convert the power supply voltage into appropriate voltages that are respectively consistent with the motor drive circuit 401, the brake drive circuit 402 and the control unit 403; and a diode unit 417, which is used to prevent the regenerative power from the motor M from flowing back to the converter 414 or the power supply 412 and causing circuit failure.

[0078] That is, the brake circuit discharge system 400 of the conventional example is a system obtained by removing the discharge resistor 108 , the discharge switching switch 109 , and the discharge command generation circuit 110 from the brake circuit discharge system 100 of the first embodiment.

[0079] Next, a state in which a failure occurs in the control unit 403 in the conventional example will be described. Figure 5 This is a graph for explaining the operation at the time of emergency stop in the brake circuit discharge system 400 according to the conventional example. Figure 5 The status at each point after time t from the generation of the emergency stop signal is shown.

[0080] First, an emergency stop signal is generated at time t0. Then, at time t1, the controller 411 that receives the emergency stop signal sends a power cutoff signal to the power cutoff switch 413 and sends a brake start command to the control unit 403. Here, the conventional brake circuit discharge system 400 does not have a discharge resistor, so the input voltage of the brake drive circuit 402 does not drop due to the flow of current to the discharge resistor.

[0081] Next, at time t2, the control unit 403, which has received the brake start command, should have sent a brake signal to the brake drive circuit 402 to apply the brakes. However, since a failure occurred in the control unit 403, the brake signal was not sent.

[0082] That is, even at time t3, the brake drive circuit 402 does not receive the brake signal, and therefore the brake release state continues, the brake B is not actuated, and the motor M does not decelerate.

[0083] Then, at time t4, the power cut-off switch 413 receiving the power cut-off signal cuts off the power supply to each converter 414 to 416. As a result, the power supply from the brake drive circuit converter 415 disappears, but the charge accumulated in the brake drive circuit capacitor 406 is not consumed by the discharge resistor, so the input voltage of the brake drive circuit 402 does not drop sharply. However, although the description in the first embodiment is omitted, there is power consumption of the brake drive circuit 402 or natural discharge of the capacitor 406, so the input voltage of the brake drive circuit 402 sometimes slowly drops. This situation is described below.

[0084] Even if time passes from time t5 to time t8, the input voltage of the brake drive circuit 402 does not drop to the point where the brake release state cannot be maintained, and therefore, the brake release state continues, and the state does not change in particular. In addition, since the brake B is not activated, the motor speed reduction caused by the brake B is not found, but the power supply to the motor drive circuit 402 is also cut off by the power cut-off switch 413 at time t4, so the speed of the motor M cannot be maintained and slow deceleration is performed. However, regarding this phenomenon, due to the influence of the charge accumulated in the capacitor 405 for the motor drive circuit or the friction of the motor M, etc., the explanation becomes complicated and it is difficult to understand the effect of the previous example, so it is assumed that it is not explained.

[0085] Finally, at time t9, the input voltage of the brake drive circuit 402 decreases to a level that makes it impossible to maintain the brake release state. As a result, the brake release is cancelled and the brake B is applied, and the motor M starts to decelerate.

[0086] As described above, when the first embodiment is compared with the conventional example, it is found that the brake circuit discharge system 100 of the first embodiment can activate the brake B earlier.

[0087] <Second Embodiment>

[0088] Figure 6 2 is a block diagram showing the structure of the brake circuit discharge system 600 according to the second embodiment of the present invention. In addition, the circuit structure in each block of the brake circuit discharge system 600 is simplified for illustration. Figure 6 In the figure, only the blocks related to the present embodiment are illustrated, and the blocks required for other systems are omitted.

[0089] The first difference between this embodiment and the first embodiment is that the signal from the controller 111 to the power cutoff switch 113 is used as an example of a discharge command generation circuit. The second difference is that the motor drive circuit converter 114 is a structure that shares the brake drive circuit converter 115. Hereinafter, the motor drive circuit converter 114 and the brake drive circuit converter 115 are collectively referred to as the drive circuit converter 114, and the motor drive circuit input voltage and the brake drive circuit input voltage are collectively referred to as the drive circuit input voltage.

[0090] The discharge instruction generation circuit in this embodiment is a NOT circuit 601, and the NOT circuit 601 includes a circuit for inverting the logic of the input signal and a circuit for operating the discharge switching switch 109. The signal line connected from the controller 111 to the power cut-off switch 113 is also connected to the input of the NOT circuit 601, and the output of the NOT circuit 601 is connected to the signal input terminal of the discharge switching switch 109. Here, the input of the power cut-off switch 113 is closed at a high level and disconnected at a low level. In addition, the input of the discharge switching switch 109 is also closed at a high level and disconnected at a low level. That is, the power cut-off switch 113 and the discharge switching switch 109 have the same logic, because the power supply is performed when the actuator is in motion without discharging, and the action of not supplying power and discharging is realized when the actuator stops. Therefore, if the logic of the power cut-off switch 113 is opposite to that of the discharge switching switch 109, the circuit for reversing the logic in the NOT circuit 601 is not required. In addition, in this embodiment, a signal line is used to connect the controller 111 to the power cut-off switch 113. However, if the power cut-off switch is an electromagnetic switch, the input of the non-circuit 601 may be connected to an auxiliary contact. However, in this case, there is a possibility that the auxiliary contact will not operate when the electromagnetic switch fails. Therefore, it is more desirable to directly use the signal from the controller 111 as in this embodiment.

[0091] The converter 114 in this embodiment supplies power to the motor M and the brake B respectively. This assumes that the rated input voltages of the motor drive circuit 101 and the brake drive circuit 102 are equal to the allowable level as described above. In the case of such a structure, as a point of attention, it is necessary to connect the discharge resistor 108 and the discharge switching switch 108 to the motor M or brake B side than the diode unit 117. This is because: when the discharge resistor 108 and the discharge switching switch 108 are connected to the converter 114 side than the diode unit 117, the charge accumulated in the motor drive circuit capacitor 105 or the brake drive circuit capacitor 106 will not flow into the discharge resistor 108 due to the rectification effect of the diode unit 117 according to the diode unit 117, and the effect of this embodiment will not occur.

[0092] Next, in the state where the control unit 103 of the present embodiment fails, the Figure 7 The status at each point after time t from the generation of the emergency stop signal will be described. Figure 7 This is a graph for explaining the operation of the brake circuit discharge system 600 according to the present embodiment during an emergency stop.

[0093] First, an emergency stop signal is generated at time t0. Then, at time t1, the controller 111 that receives the emergency stop signal sends a power cut-off signal to the power cut-off switch 113, sends a discharge signal to the discharge instruction generation circuit, and sends a brake start command to the control unit 103. At this time, the discharge instruction generation circuit that receives the discharge signal closes the discharge switching switch 109 to form a state in which current flows to the discharge resistor 108. Then, the input voltage of the motor drive circuit 101 begins to drop, but since power is supplied from the motor drive circuit converter 114, the voltage drops slowly. Here, since the input voltage of the motor drive circuit 101 drops in voltage, the power supplied to the motor M decreases and the rotation speed cannot be maintained, so the motor M starts to decelerate.

[0094] Next, at time t2, the control unit 103 receiving the brake start command should send a brake signal to the brake drive circuit 102 to activate the brake B. However, since a failure occurs in the control unit 103, the brake signal is not sent.

[0095] That is, even at time t3 , the brake drive circuit 102 does not receive the brake signal, and therefore the brake release state continues, the brake B is not actuated, and the motor M does not decelerate.

[0096] On the other hand, at time t4, the power cut-off switch 113, which has received the power cut-off signal, cuts off the power supply to each converter 114, 116. Then, the power supply from the drive circuit converter 114, which has been supplying the energy consumed by the discharge resistor 108, is lost, and therefore, the charge accumulated in the motor drive circuit capacitor 105 and the brake drive circuit capacitor 106 is consumed by the discharge resistor 108. As a result, the drive circuit input voltage starts to drop sharply.

[0097] Furthermore, at time t5, the drive circuit input voltage drops to a level that makes it impossible to maintain the brake release state. As a result, the brake release is cancelled and the brake B is activated, and the motor M is further decelerated.

[0098] Meanwhile, at time t6, the charge of the brake drive circuit capacitor 106 disappears and the brake drive circuit input voltage becomes 0, but the state does not change in particular.

[0099] Finally, at time t7.5, the rotation speed of the motor is 0, and the actuator is in a completely stopped state.

[0100] As described above, when the brake circuit discharge system 600 involved in this embodiment is compared with the brake circuit discharge system 100 involved in the first embodiment, it is known that the brake circuit discharge system 600 can start the brake B earlier because the rotation of the motor M itself can be suppressed by the voltage drop of the driving circuit input voltage.

[0101] <Third Embodiment>

[0102] Figure 8 1 is a block diagram showing the structure of a brake circuit discharge system 800 according to a third embodiment of the present invention. In addition, the circuit structure in each block of the brake circuit discharge system 800 is simplified for illustration. Figure 8 Only blocks related to this embodiment are shown in the figure, and blocks required for other systems are omitted.

[0103] The brake circuit discharge system 800 according to the present embodiment is also similar to the brake circuit discharge system 600 according to the second embodiment, and the signal line connected from the controller 111 to the power cut-off switch 113 is branched and connected to the NOT circuit 801. The difference between the present embodiment and the second embodiment is that the overvoltage detection circuit 802 is added, and the OR circuit 803 is added to output the logical OR of the output signal of the overvoltage detection circuit 802 and the above-mentioned switching command signal (discharge signal command) to the discharge switching switch 109. Here, the component including the NOT circuit 801, the overvoltage detection circuit 802, and the OR circuit 803 is the discharge command generation circuit in the present embodiment. In addition, the overvoltage detection circuit 802 is connected between the diode unit 117 and the motor drive circuit 101. That is, the overvoltage detection circuit 802 is connected between the power line of the motor drive circuit 101 to which the motor drive circuit capacitor 105 is connected and the discharge resistor 108. In addition, the OR circuit 803 is connected to the output of the NOT circuit 801 and the output of the overvoltage detection circuit 802.

[0104] In addition, in this embodiment, the actuator 810 and the control board 81 including elements other than the actuator 810 are respectively accommodated in different frames, and each signal line or power line is connected by a cable between the frames. The actuator 810 includes a motor drive circuit 101, a brake drive circuit 102, a control unit 103, and a driver 811 including capacitors 105 to 107. The brake circuit discharge system 800 involved in this embodiment can be applied to a robot with a built-in actuator 810 as an example, and the brake 810 includes a driver 811.

[0105] Here, the overvoltage detection circuit 802 has only to have a function of generating an output such as closing the discharge switching switch 109 when the voltage of the connection portion between the diode portion 117 and the motor drive circuit 101 exceeds a certain threshold value, and its principle or structure is not particularly limited. For example, it may be a comparator and a comparison circuit using a reference voltage, or a component using a Zener diode. Furthermore, the value obtained by digitally converting the voltage value by an A / D converter may be imported into a microcomputer or the like and compared in software.

[0106] The overvoltage detection circuit 802 is used to detect overvoltage caused by regenerative power generated when the motor M is decelerated by the brake B or when the motor M is accelerated by an external force. When such an overvoltage is detected, the overvoltage state is suppressed by closing the discharge switching switch 109 to consume the regenerative power in the discharge resistor 108, thereby preventing circuit failure.

[0107] <Fourth Embodiment>

[0108] Fig. 9 1 is a block diagram showing the structure of a brake circuit discharge system 900 according to a fourth embodiment of the present invention. In addition, the circuit structure in each block of the brake circuit discharge system 900 is simplified for illustration. Fig. 9 Only the blocks related to this embodiment are shown in the figure, and the blocks required for other systems are omitted. The difference between this embodiment and the first embodiment is that the discharge resistor 108 and the control unit capacitor 107 are connected in parallel to the output of the control unit converter 116 instead of being connected in parallel to the brake drive circuit converter 115.

[0109] Here, a signal is sent from the control unit 103 to the brake drive circuit 102 so that the brake B is activated when the control unit 103 stops due to insufficient power. Specifically, the brake B can be released when the above signal is at a high level, and it is preferred that the signal line used to transmit the above signal is pulled down. Alternatively, the control unit 103 and the brake drive circuit 102 are connected by communication, and if the brake release signal is sent within a certain period, the brake B is activated.

[0110] According to this structure, even if the control unit 103 loses control or fails, the power supply to the control unit converter 116 is cut off by the power cut-off switch 113 and the charge accumulated in the control unit capacitor 107 is discharged through the discharge resistor 108, thereby causing the control unit 103 to stop due to insufficient power and the brake B to be activated, thereby preventing the actuator from malfunctioning.

[0111] Then, in Fig.102 shows the state at each point after time t from the generation of the emergency stop signal in a state where a failure has occurred in the control unit 103 of the present embodiment. Fig.10 This is a graph for explaining the operation of the brake circuit discharge system according to the fourth embodiment of the present invention during emergency stop.

[0112] First, an emergency stop signal is generated at time t0. Then, at time t1, the controller 111 that receives the emergency stop signal sends a power cutoff signal to the power cutoff switch 113, sends a discharge signal to the discharge command generation circuit 110, and sends a brake start command to the control unit 103. At this time, the discharge command generation circuit 110 that receives the discharge signal 108 closes the discharge switching switch 109 so that current flows to the discharge resistor 108. Then, the control unit input voltage starts to drop, but since power is supplied from the control unit converter 116, the voltage drops slowly.

[0113] First, an emergency stop signal is generated at time t0. Then, at time t1, the controller 111 that receives the emergency stop signal sends a power cut-off signal to the power cut-off switch 113, sends a discharge signal to the discharge command generation circuit 110, and sends a brake start command to the control unit 103. At this time, the discharge command generation circuit 110 that receives the discharge signal closes the discharge switching switch 109 to form a state where current flows to the discharge resistor 108. As a result, the control unit input voltage starts to drop, but this is a curve diagram that illustrates the action of the brake circuit discharge system involved in the fourth embodiment of the present invention during emergency stop. Since power is supplied from the control unit converter 116, the voltage drops slowly.

[0114] Next, at time t2, the control unit 103, which has received the brake start command, should send a brake signal to the brake drive circuit 102 to activate the brake B. However, since a failure occurs in the control unit, the brake signal is not sent.

[0115] That is, even at time t3, the brake drive circuit 102 does not receive the brake signal, and therefore the brake release state continues, the brake B is not actuated, and the motor M does not decelerate.

[0116] On the other hand, at time t4, the power cut-off switch 113, which has received the power cut-off signal, cuts off the power supply to each converter 114 to 116. Then, the power supply from the control unit converter 116, which has been supplying the energy consumed by the discharge resistor 108, is lost, and the charge accumulated in the control unit capacitor 107 is consumed by the discharge resistor 108. As a result, the input voltage of the control unit 103 begins to drop sharply.

[0117] However, even at time t5, the input voltage of the brake drive circuit 102 does not drop, and therefore the brake released state is maintained.

[0118] At time t6, the charge of the control unit capacitor 107 disappears, the input voltage of the control unit 103 becomes 0, and the control unit 103 stops. Here, since the control unit 103 stops due to power shortage, a signal for commanding the brake B to be activated is sent from the control unit 103 to the brake drive circuit 102 as described above.

[0119] Then, at time t7, the brake release is cancelled and the motor M starts to decelerate.

[0120] Finally, when time t8 elapses and time t9 comes, the rotation speed of the motor M becomes 0, and the actuator is in a completely stopped state.

[0121] As described above, when the brake circuit discharge system 900 according to the present embodiment is compared with the brake circuit discharge system 100 according to the first embodiment, it is known that the brake circuit discharge system 900 can activate the brake B earlier because the rotation of the motor M itself can be suppressed by the voltage drop of the drive circuit input voltage. In addition, the brake circuit discharge system 900 can quickly and reliably stop the control unit 103 that fails and cannot be controlled, thereby preventing malfunction caused by the control unit 103 sending an erroneous signal.

[0122] <Fifth Embodiment>

[0123] Fig.11 1 is a block diagram showing the structure of a brake circuit discharge system 1100 according to a fifth embodiment of the present invention. In addition, the circuit structure in each block of the brake circuit discharge system 1100 is simplified for illustration. Fig.11 Only blocks related to this embodiment are shown in the figure, and blocks required for other systems are omitted. The difference between this embodiment and the first embodiment is that the discharge resistor 108 is connected to the input stage of each of the converters 114 to 116.

[0124] According to the structure of the brake circuit discharge system 1100 involved in this embodiment, the electric charge accumulated in the capacitors included in the converters 114 to 116 of the motor drive circuit 101, the brake drive circuit 102, and the control unit 10 is discharged at the same time, thereby stopping the rotation and control of the actuator at the same time. However, in the case where the circuit after the converters 114 to 116 includes a backflow prevention circuit, it is necessary to pay attention because the discharge effect of the capacitors 105 to 107 of the motor drive circuit 101, the brake drive circuit 102, and the control unit 103 cannot be obtained.

[0125] <Sixth Implementation Method>

[0126] Next, the sixth embodiment of the present invention will be described with respect to the influence of the resistance value of the discharge resistor 108 and the difference in various delay amounts. The difference between this embodiment and the first embodiment is that the resistance value of the discharge resistor 108 is made as small as possible. In this embodiment, a 10Ω discharge resistor 108 is used. For the brake circuit discharge system of this embodiment having the same structure as the brake circuit discharge system 100 of the first embodiment, a 10Ω discharge resistor 108 is used. Fig.12 The state at each point after time t from the generation of the emergency stop signal in a normal state with no failure at all will be described. Fig.12 This is a graph for explaining the operation of the brake circuit discharge system according to the present embodiment during emergency stop.

[0127] First, an emergency stop signal is generated at time t0. Then, at time t1, the controller 111 that receives the emergency stop signal sends a power cut-off signal to the power cut-off switch 113, sends a discharge signal to the discharge instruction generation circuit 110, and sends a brake start command to the control unit 103. At this time, the discharge instruction generation circuit 110 that receives the discharge signal closes the discharge switching switch 109 to form a state in which current flows to the discharge resistor 108. As a result, the input voltage of the brake drive circuit 102 begins to drop, but the resistance value of the discharge resistor 108 is as small as possible, and the current flowing is close to the current when the power line is short-circuited to GND. Therefore, although power is supplied from the brake drive circuit converter 115, the supply cannot keep up and the voltage drops sharply.

[0128] Next, at time t1.5, the input voltage of the brake drive circuit 102 decreases to a level that makes it impossible to maintain the brake released state. As a result, the brake release is cancelled, the brake B is actuated, and the motor M starts to decelerate.

[0129] Here, according to the brake circuit discharge system 100 involved in the first embodiment, the control unit 103 receives the brake start command at time t2, and the brake B is started at time t3. In the brake circuit discharge system involved in this embodiment, the brake B can be started before the control unit 103 receives the brake start command.

[0130] Industrial Applicability

[0131] The present invention relates to a brake circuit discharge system including a brake drive circuit and has industrial applicability.

[0132] Description of Reference Numerals

[0133] 100, 400, 600, 800, 900, 1100: brake circuit discharge system; 101, 401: motor drive circuit; 102, 402: brake drive circuit; 103, 403: control unit; 104, 404: inverter; 105-107, 405-407: capacitor; 108: discharge resistor; 109: discharge switching switch; 110: discharge instruction generating circuit; 111, 411: controller; 112, 412: power supply; 113, 413: power cut-off switch; 114-116, 414-416: converter; 117, 417: diode unit; 601, 801: non-circuit; 802: overvoltage detection circuit; 803: or circuit; 810: actuator; 811: driver; 812: control board; M: motor; B: brake.

Claims

1. A brake circuit discharge system, comprising: a motor drive circuit that drives the motor; a brake drive circuit that drives a brake that decelerates and stops the drive of the motor, the brake being activated when power is cut off; a control unit that controls the actions of the motor drive circuit and the brake drive circuit and continuously sends a brake release signal to the brake drive circuit; a capacitor having one end connected to at least one of a power line of the brake drive circuit and a power line of the control unit, and having the other end connected to ground; a discharge resistor connected to a power line connected to the capacitor to discharge the charge accumulated in the capacitor; a discharge switching switch connected in series with the discharge resistor; and The discharge instruction generation circuit is connected to the discharge switching switch and generates a switching instruction signal for switching the discharge switching switch on and off.

2. The brake circuit discharge system according to claim 1, wherein: The capacitor is a brake drive circuit capacitor connected to a power line of the brake drive circuit. The discharge resistor is connected to a power line of the brake drive circuit in parallel with the brake drive circuit capacitor.

3. The brake circuit discharge system according to claim 1, wherein: The capacitor is a control unit capacitor connected to a power line of the control unit. The discharge resistor and the control unit capacitor are connected in parallel to a power line of the control unit.

4. The brake circuit discharge system according to any one of claims 1 to 3, wherein: The discharge instruction generating circuit is a NOT circuit.

5. The brake circuit discharge system according to claim 4, wherein: The discharge instruction generating circuit comprises: an overvoltage detection circuit connected between the power line connected to the capacitor and the discharge resistor; and an OR circuit connected to the overvoltage detection circuit and the NOT circuit. The OR circuit outputs a logical OR of the output signal of the overvoltage detection circuit and the switching instruction signal to the discharge switching switch.

6. The brake circuit discharge system according to claim 1, wherein: Also available: a converter for a motor drive circuit, which is connected in series to a power line of the motor drive circuit; a converter for a brake drive circuit, which is connected in series to a power line of the brake drive circuit; and a converter for a control unit, which is connected in series to a power line of the control unit, The discharge resistor is connected to the input stages of the motor drive circuit converter, the brake drive circuit converter, and the control unit converter.

7. The brake circuit discharge system according to any one of claims 1 to 3, wherein: The resistance value of the discharge resistor is greater than or equal to 1Ω and less than or equal to 1000Ω.

8. The brake circuit discharge system according to any one of claims 1 to 3, wherein: The motor drive circuit, the brake drive circuit, the control unit, and the capacitor are built in a robot.

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