Motor drive unit

Abstract

To prevent an increase in the number of components and to avoid extra power consumption when a limit switch is used to detect a travel limit position of a sheet.SOLUTION: A motor drive device 100 includes limit switches 101 and 102 and a drive circuit 105. The limit switches 101 and 102 are configured to detect the travel limit position of a sheet. The drive circuit 105 is configured to use a control signal CS as a power source to drive a motor 30 according to the control signal CS. The drive circuit 105 stops the motor 30 when limit positions LM1 and LM2 are detected by the limit switches 101 and 102. On the other hand, the drive circuit 105 drives the motor 30 when the limit positions LM1 and LM2 are not detected by the limit switches 101 and 102.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a motor drive device, and more particularly to a motor drive device that drives a motor for moving a seat. [Background technology]

[0002] When an object is moved by a motor, limit switches are sometimes used instead of mechanical stoppers to detect the limit positions of the object's movement range due to structural constraints.

[0003] Japanese Patent Laid-Open Publication No. 9-182473 (Patent Document 1) discloses a motor control device. This motor control device has a drive device, a control device, and a limit switch. The drive device drives a motor for changing the position of an object. The control device controls the motor by controlling the drive device. The limit switch is connected directly to the drive device without going through the control device. When the limit switch detects that the object has reached its movable end (movement limit position), it stops the motor directly without going through the control device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-182473 Summary of the Invention [Problem to be solved by the invention]

[0005] When a motor is used to move a seat as an object, a limit switch detects the limit positions of the seat.

[0006] In a case where a generator (e.g., a control device) of a control signal for controlling the rotation direction of a motor and a drive device are provided separately, the drive device drives the motor according to the control signal. According to the configuration described in Patent Document 1, the drive device requires a dedicated power supply that is different from the power supply of the generator. As a result, a power line is required to connect the dedicated power supply to the drive device. The addition of this power line increases the number of components in the drive device. In addition, in the above case, when an instruction to stop the motor is issued, the drive device may need to receive standby power from the dedicated power supply to wait while the motor is stopped. This standby power results in excess power consumption.

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to provide a motor drive device that can prevent an increase in the number of parts and avoid excess power consumption when a limit switch is used to detect the limit position of seat movement. [Means for solving the problem]

[0008] The motor drive device of the present disclosure is configured to be connected between a motor and a signal generating device. The motor is used to move a seat. The signal generating device generates a control signal to control the rotation direction of the motor when instructed to drive the motor. The motor drive device includes a limit switch and a drive circuit. The limit switch is configured to detect a travel limit position of the seat. The drive circuit is configured to use the control signal as a power source and drive the motor in accordance with the control signal. The drive circuit stops the motor when the travel limit position is detected by the limit switch, and drives the motor when the travel limit position is not detected by the limit switch.

[0009] With the above configuration, the control signal from the signal generating device is used as the power supply for the motor drive device (drive circuit). This allows the motor drive device to drive the motor without requiring a dedicated power supply. As a result, a power line connecting this dedicated power supply to the motor drive device is not required. This prevents an increase in the number of parts in the motor drive device. In addition, when an instruction to stop the motor is issued, no control signal is generated, so the drive circuit does not receive the control signal as a power supply. As a result, the drive circuit stops. Therefore, the drive circuit does not require standby power while the motor is stopped. As a result, it is possible to prevent an increase in the number of parts in the motor drive device and avoid excess power consumption.

[0010] Preferably, the drive circuit includes a reactor and a contact relay. The contact relay switches between driving and stopping the motor by switching between an open state and an closed state depending on whether or not a current flows through the reactor. The limit switch is configured to open when it detects a travel limit position. The motor drive device further includes an intervening circuit interposed between the reactor and the limit switch.

[0011] If an intervening circuit were not provided, the limit switch would be directly connected to the reactor. As a result, when the limit switch opens, arc discharge may occur in the limit switch due to the electromotive force of the reactor. This arc discharge may damage the limit switch. With the above configuration, the intervening circuit functions as a buffer to reduce the effect of the electromotive force of the reactor on the limit switch. This reduces the amount of arc discharge compared to when the intervening circuit is not provided. As a result, the limit switch can be protected.

[0012] Preferably, the intervening circuit is an amplifier circuit configured to amplify a signal indicating the detection result of the limit switch and supply the amplified signal to the reactor.

[0013] With the above configuration, the specifications of the limit switch (e.g., rated voltage and rated current) are related to the specifications of the reactor through the signal amplification factor of the amplifier circuit, and as a result, the specifications of the limit switch can be appropriately determined by appropriately adjusting this signal amplification factor.

[0014] Preferably, the motor is a DC motor. The drive circuit includes a reactor and a contact relay. The contact relay switches between driving and stopping the DC motor by switching between an open and closed state depending on whether or not a current flows through the reactor. When an instruction to stop the DC motor is given, the contact relay switches between an open and closed state so that both ends of the DC motor are short-circuited and the DC motor stops.

[0015] With the above configuration, both ends of the DC motor are short-circuited when a command to stop the motor is issued. This allows the motor to regeneratively brake even when an unintended external force is applied to the seat, thereby preventing unintended movement of the seat.

[0016] Preferably, the drive circuit includes a reactor and a contact relay. The contact relay switches between driving and stopping the motor by switching between an open state and an closed state depending on whether or not a current flows through the reactor. When the limit switch detects the travel limit position, the contact relay switches between an open state and an closed state so that the motor stops while being electrically disconnected from the signal generating device.

[0017] After the limit switch detects the seat's travel limit position, the motor is stopped and the supply of the control signal to the drive circuit is stopped. The control signal may then be supplied again to the drive circuit to instruct the motor to operate. In this case, depending on the configuration of the motor drive circuit, the control signal current may not be immediately supplied to the reactor of the relay due to its induced electromotive force. This current may be temporarily supplied to the motor before it begins to be supplied to the reactor. As a result, the motor may rotate even though the limit switch detects the seat's travel limit position, causing the seat to temporarily move beyond the travel limit position. Therefore, such current supply to the motor is unintended and undesirable. With the above configuration, the motor is electrically disconnected from the control device when the limit switch detects the travel limit position. As a result, unintended current supply to the motor can be prevented when the control signal supply to the motor drive device is stopped and then resumed. As a result, the seat can be prevented from temporarily moving beyond the travel limit position. [Effects of the Invention]

[0018] According to the present disclosure, when a limit switch is used to detect the movement limit position of the seat, it is possible to prevent an increase in the number of parts and avoid excess power consumption. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a diagram schematically showing a seat to which a motor drive device according to an embodiment of the present invention is attached; [Figure 2] FIG. 1 is a diagram illustrating a configuration of a control system for controlling a motor. [Figure 3] FIG. 2 is a diagram showing detailed configurations of a driver of an ECU, a relay section, a relay driving section, and a signal conversion section of a motor driving device. [Figure 4] 10 is a diagram illustrating the flow of current in the motor drive device when the ECU generates a control signal CS having a positive voltage. FIG. [Figure 5]10A and 10B are diagrams illustrating the flow of current in the motor drive device when the ECU generates a control signal having a negative voltage. [Figure 6] 10A and 10B are diagrams illustrating the flow of current in the motor drive device when the limit switch detects a limit position LM1. [Figure 7] 10 is a diagram illustrating a state of the motor drive device when a user operates the operation unit to instruct the motor to stop via the ECU. FIG. [Figure 8] FIG. 10 is a diagram showing a detailed configuration of a motor drive device according to a first modification. [Figure 9] 10 is a diagram illustrating a current flow in the motor drive device when the ECU generates a control signal having a positive voltage. FIG. [Figure 10] 10 is a diagram showing the state of the motor drive device when the limit switch detects a limit position LM1. FIG. [Figure 11] FIG. 10 is a diagram showing the configuration of a motor control system according to a second modification. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0021] 1 is a diagram schematically showing a seat to which a motor drive device according to the present embodiment is attached, the seat being used in a vehicle, an office, a general home, or other places.

[0022] Referring to FIG. 1, a seat 1 includes an ottoman 5, a seat cushion 10, a seat back 15, a headrest 20, a seat adjuster 25, and an operating unit .

[0023] The ottoman 5 is connected to a seat cushion 10. The seat cushion 10 is connected to a seat back 15. The seat back 15 is connected to a headrest 20. The ottoman 5, the seat cushion 10, the seat back 15, and the headrest 20 form the main body of the seat 1.

[0024] The seat adjuster 25 is used to adjust the position of the main body of the seat 1 and includes a motor 30. The motor 30 is, for example, a DC motor and is provided to move the seat 1. In this example, the motor 30 is configured to operate the seat back 15 in the forward direction F or the rearward direction R. A control system for controlling the motor 30 will be described in detail later. The movement limit positions (operation limit positions) of the seat back 15 in the forward direction F and the rearward direction R are also referred to as limit positions LM1 and LM2, respectively. Each of the limit positions LM1 and LM2 is determined by a limit switch (described later). A reference position RP of the seat back 15 is predetermined as a default position in the forward direction F and the rearward direction R.

[0025] The seat adjuster 25 further includes a motor (not shown) different from the motor 30. This motor is configured to move the main body portion of the seat 1 in the X-axis direction along a slide rail 27 arranged on the floor 26. The seat adjuster 25 may further include a motor for moving the main body portion of the seat 1 in the Y-axis direction. The seat adjuster 25 may further include a motor (not shown) for raising or lowering the main body portion of the seat 1 in the Z-axis direction. The seat adjuster 25 may further include a motor for operating the ottoman 5 in the direction DR1 or the direction DR2. The seat adjuster 25 may further include a motor for operating the headrest 20.

[0026] The operating unit 28 is operated by the user to achieve the reclining function of the seat back 15. Specifically, the operating unit 28 is operated by the user to drive and stop the motor 30 and, when the motor 30 is driven, to specify the angle θ. The angle θ is the angle by which the seat back 15 is tilted from the reference position RP in the forward direction F or the rearward direction R. The angle θ may take any value as long as the position of the seat back 15 does not exceed the limit position LM1 or the limit position LM2. The operating unit 28 may be attached to the seat 1, or a terminal device (e.g., a smartphone) owned by the user may be used as the operating unit 28.

[0027] Fig. 2 is a diagram showing the configuration of a control system for controlling motor 30. Referring to Fig. 2, motor control system 50 includes, in addition to operation unit 28 and motor 30, an ECU (Electronic Control Unit) 200, a power supply 400, and a motor drive device 100.

[0028] The operation unit 28 is connected to a power source (not shown) and includes switches 305 and 310. The switch 305 is turned on when the user commands the seat back 15 to move forward in the F direction, and is turned off otherwise. Similarly, the switch 310 is turned on when the user commands the seat back 15 to move backward in the R direction, and is turned off otherwise.

[0029] ECU 200 (motor control device) is attached to seat adjuster 25, and includes interfaces (I / F) 205 and 210, a microcomputer 220, a driver 215, and terminals T01 and T02.

[0030] The interfaces 205 and 210 are connected to switches 305 and 310, respectively. These connections are wired in this example, but may also be wireless.

[0031] The microcomputer 220 includes a processor such as a CPU (Central Processing Unit) and a memory (neither of which is shown). The memory stores programs executed by the processor.

[0032] Driver 215 is configured to drive motor drive device 100. Terminals T01 and T02 are connected to power line pair PL0. Control of motor 30 by ECU 200 is achieved by control of motor drive device 100 by microcomputer 220 using driver 215.

[0033] When an instruction to drive the motor 30 is issued, the ECU 200 generates a control signal CS and outputs the signal to the motor drive device 100 via the power line pair PL0. The ECU 200 is an example of a "signal generating device" in the present disclosure. The control signal CS is a signal for controlling the rotation direction of the motor 30. This rotation direction corresponds to either a direction for moving the seat back 15 forward in the F direction or a direction for moving the seat back 15 backward in the R direction. The ECU 200 determines whether an instruction to drive the motor 30 has been issued in response to an operation performed by a user using the operating unit 28. This operation indicates whether an instruction to move the seat back 15 has been issued, and, if such an operation has been issued, whether the movement direction is the forward direction F or the backward direction R.

[0034] The control signal CS has a positive voltage when an instruction is given to move the seat back 15 in the forward direction F. In this case, the potential of the terminal T01 is higher than the potential of the terminal T02. On the other hand, the control signal CS has a negative voltage when an instruction is given to move the seat back 15 in the backward direction R. In this case, the potential of the terminal T01 is lower than the potential of the terminal T02. Note that when the user does not instruct the motor 30 to be driven using the operation unit 28 (for example, when an instruction is given to stop the motor 30), the ECU 200 does not generate the control signal CS. The power supply 400 is used as a power supply for the ECU 200.

[0035] The motor drive device 100 is configured to be connected between the ECU 200 and the motor 30, and is attached to the seat adjuster 25. The motor drive device 100 includes limit switches 101 and 102 and a device 103.

[0036] Each of the limit switches 101 and 102 detects a movement limit position of the seat 1. In this example, the limit switches 101 and 102 detect limit positions LM1 and LM2 (FIG. 1) of the seat back 15, respectively.

[0037] The device 103 includes a drive circuit 105 , a signal conversion circuit 130 , connection terminals 140 and 150 , an input terminal 160 , and an output terminal 170 .

[0038] The drive circuit 105 includes a relay unit 110 and a relay drive unit 120. The relay unit 110 is connected to the power line pair PL1 and is configured to switch in accordance with the detection results of the limit switches 101 and 102. The relay drive unit 120 is connected to the relay unit 110 and is configured to switch the relay unit 110 in accordance with a signal supplied from the signal conversion circuit 130.

[0039] The drive circuit 105 is configured to drive the motor 30 in accordance with the control signal CS. Specifically, when the control signal CS has a positive voltage, the drive circuit 105 drives the motor 30 so that the seat back 15 moves in the forward direction F. On the other hand, when the control signal CS has a negative voltage, the drive circuit 105 drives the motor 30 so that the seat back 15 moves in the backward direction R.

[0040] The drive circuit 105 stops the motor 30 when the limit switch 101 detects the limit position LM1 while the seat back 15 is in operation. On the other hand, the drive circuit 105 is configured to drive the motor 30 when it receives a control signal CS from the ECU 200 and the limit position LM1 is not detected by the limit switch 101.

[0041] Similarly, the drive circuit 105 stops the motor 30 when the limit switch 102 detects the limit position LM2 during operation of the seat back 15. On the other hand, the drive circuit 105 is configured to drive the motor 30 when it receives a control signal CS from the ECU 200 and the limit position LM2 is not detected by the limit switch 102.

[0042] The signal conversion circuit 130 is a signal amplification circuit connected to the power line pair PL2 branching off from the power line pair PL1. The signal conversion circuit 130 includes signal conversion units 131 and 132. The signal conversion units 131 and 132 function as amplification units configured to convert and amplify signals indicating the detection results of the limit switches 101 and 102, respectively. The detailed configurations of the drive circuit 105 and the signal conversion circuit 130 will be described later.

[0043] The connection terminals 140 and 150 are configured to be connected to the limit switches 101 and 102, respectively.

[0044] Input terminal 160 is provided between the pair of power lines PL0 and PL1 and receives an input of a control signal CS. Input terminal 160 includes terminals T1 and T2. Terminals T1 and T2 are connected to terminals T01 and T02 of ECU 200, respectively.

[0045] The output terminal 170 is provided between the drive circuit 105 and the motor 30. The output terminal 170 includes terminals T11 and T12. When the motor 30 is driven, the voltage between the terminals T11 and T12 is applied to the motor 30 as the drive voltage of the motor 30.

[0046] In cases where the ECU 200 and the motor drive device are provided separately, the motor drive device may require a dedicated power supply that is different from the power supply of the ECU 200. As a result, a power line (e.g., a wire harness) is required to connect this dedicated power supply to the motor drive device. The addition of this power line increases the number of parts in the motor drive device. In addition, in the above case, when an instruction to stop the motor 30 is issued, the motor drive device may need to receive standby power from the dedicated power supply in order to wait while the motor 30 is stopped. This standby power results in excess power consumption.

[0047] Motor driving device 100 according to the present embodiment has a configuration for dealing with such problems. Specifically, drive circuit 105 of motor driving device 100 uses control signal CS as a power source and drives motor 30 in accordance with control signal CS.

[0048] With this configuration, the control signal CS from the ECU 200 is used as the power source for the drive circuit 105 (motor drive device 100). This allows the motor drive device 100 to drive the motor 30 without requiring a dedicated power supply. As a result, a power line connecting the dedicated power supply and the motor drive device 100 is not required. This prevents an increase in the number of components in the motor drive device 100. In addition, when an instruction to stop the motor 30 is given (for example, by a user using the operation unit 28), the control signal CS is not generated, and the drive circuit 105 does not receive the control signal CS as a power source. As a result, the drive circuit 105 stops. Therefore, the drive circuit 105 does not require standby power while the motor 30 is stopped. From the above, it is possible to prevent an increase in the number of components in the motor drive device 100 and avoid excess power consumption.

[0049] 3 is a diagram showing detailed configurations of driver 215 of ECU 200, relay unit 110, relay driver 120, and signal converters 131 and 132 of motor drive device 100. In this example, limit switches 101 and 102 are configured to open when limit positions LM1 and LM2 are detected, respectively (normally closed type).

[0050] 3, driver 215 of ECU 200 includes contact relays 217 and 219. Contact relay 217 includes contacts P01 to P03. Contact relay 219 includes contacts P04 to P06. ECU 200 appropriately switches contact relays 217 and 219 depending on whether to generate a control signal CS having a positive voltage or a negative voltage, or whether to stop motor 30 (not generate a control signal CS). Power supply 400 is used as the power source for driver 215.

[0051] The relay unit 110 of the motor drive device 100 includes reactors L1 and L2 and contact relays 111 and 112. The contact relay 111 includes contacts P1 to P3. The contact relay 111 switches between driving and stopping the motor 30 by switching its open / closed state depending on whether or not a current is flowing through the reactor L1. Similarly, the contact relay 112 includes contacts P5 to P7. The contact relay 112 switches between driving and stopping the motor 30 by switching its open / closed state depending on whether or not a current is flowing through the reactor L2. Each of the contact relays 111 and 112 is a b-contact relay. Specifically, the contact relays 111 and 112 are turned off when a current is flowing through the reactors L1 and L2, respectively, and are turned on otherwise.

[0052] The relay driving unit 120 includes modules 121 and 122. The module 121 is connected to the reactor L1 and includes diodes D1 and D3 and a resistor R1. The module 122 is connected to the reactor L2 and includes diodes D2 and D4 and a resistor R2. Each of the modules 121 and 122 is provided to drive the relay unit 110.

[0053] The signal conversion unit 131 performs signal conversion using the voltage of a control signal CS provided via the pair of power lines PL1 and PL2 as an operating voltage. The signal conversion unit 131 includes transistors TR1 and TR3, resistors R3, R4, R7, and R8, and diodes D5 and D8. The transistors TR1 and TR3 are a PNP transistor and an NPN transistor, respectively.

[0054] The signal conversion unit 131 functions as an amplifier circuit configured to amplify a signal indicating the detection result of the limit switch 101 and supply the amplified signal to the reactor L1. When the limit switch 101 is not activated (closed), the transistors TR3 and TR1 are in the off state, and no current flows through the reactor L1. On the other hand, when the limit switch 101 is activated (open), current flows through the base of the transistor TR3, turning the transistor TR3 on. This turns on the transistor TR1, and current flows through the reactor L1. As a result, the contact relay 111 is turned off.

[0055] The signal conversion unit 131 also functions as an intervening circuit between the reactor L1 and the limit switch 101. If the signal conversion unit 131 and the module 121 were not provided, the limit switch 101 would be directly connected to the reactor L1. As a result, when the limit switch 101 opens, an arc discharge may occur in the limit switch 101 due to the electromotive force of the reactor L1. This arc discharge may damage the limit switch 101. On the other hand, in the embodiment, the signal conversion unit 131 functions as the above-mentioned intervening circuit, and therefore functions as a buffer that reduces the effect of the electromotive force of the reactor L1 on the limit switch 101. This reduces the amount of arc discharge compared to when the signal conversion unit 131 is not provided. As a result, the limit switch 101 can be protected.

[0056] The specifications of the limit switch 101 (e.g., its rated voltage and rated current) are related to the specifications of the reactor L1 through the signal amplification factor of the signal conversion unit 131. As a result, the specifications of the limit switch 101 can be appropriately determined by appropriately adjusting this signal amplification factor (the current flowing through the limit switch 101 can be appropriately adjusted). This eliminates the need to increase the size of the limit switch 101 to further reduce the effects of the arc discharge. As a result, the scope for selecting the specifications of the limit switch 101 can be increased (e.g., the limit switch 101 can be made more compact). The signal amplification factor is adjusted depending on the specifications of the transistors TR1 and TR3, the resistors R3, R4, R7, and R8, and the diodes D5 and D8.

[0057] Similar to the signal conversion unit 131, the signal conversion unit 132 performs signal conversion using the voltage of the control signal CS provided via the pair of power lines PL1 and PL2 as its operating voltage. The signal conversion unit 132 includes transistors TR2 and TR4, resistors R5, R6, R9, and R10, and diodes D6 and D7. The transistors TR2 and TR4 are a PNP transistor and an NPN transistor, respectively.

[0058] The signal conversion unit 132 functions as an amplifier circuit configured to amplify a signal indicating the detection result of the limit switch 102 and supply the amplified signal to the reactor L2. The signal conversion unit 132 also functions as an intervening circuit interposed between the reactor L2 and the limit switch 102.

[0059] The signal conversion unit 132 functions to protect the limit switch 102 from arc discharge when it is opened, in the same way that the signal conversion unit 131 functions to protect the limit switch 101 from arc discharge when it is opened. The signal conversion unit 132 can increase the scope of options for the specifications of the limit switch 102, in the same way that the signal conversion unit 131 can increase the scope of options for the specifications of the limit switch 101.

[0060] 4 is a diagram illustrating the flow of current in the motor drive device 100 when the ECU 200 generates a control signal CS having a positive voltage. In this example, the position of the seat back 15 does not exceed the limit position LM1 or the limit position LM2, so the limit switches 101 and 102 are closed.

[0061] 4, ECU 200 controls contact relays 217 and 219 so that contacts P01 and P02 are connected and contacts P04 and P06 are connected, thereby making the potential of terminal T1 higher than the potential of terminal T2.

[0062] The current (thick arrow) supplied from the power supply 400 to the motor drive device 100 through the contact relay 217 and terminal T1 is divided into a first current (two-dot chain arrow) that flows through the relay unit 110 and a second current (dashed arrow) that is different from the first current. In this example, the first current flows to the motor 30 through the contact relay 111 before flowing into terminal T2. As a result, the motor 30 is driven and the seat back 15 moves forward in the F direction. The second current flows into terminal T2 through the limit switch 101.

[0063] 5 is a diagram illustrating the flow of current in the motor drive device 100 when the ECU 200 generates a control signal CS having a negative voltage. In this example, the position of the seat back 15 does not exceed the limit position LM1 or the limit position LM2, so the limit switches 101 and 102 are closed.

[0064] 5, ECU 200 controls contact relays 217 and 219 so that contacts P01 and P03 are connected and contacts P04 and P05 are connected, thereby making the potential of terminal T2 higher than the potential of terminal T1.

[0065] The current (thick arrow) supplied from the power supply 400 to the motor drive device 100 through terminal T2 is divided into a first current (two-dot chain arrow) and a second current (dashed arrow). In this example, the first current flows to the motor 30 through the contact relay 112 before flowing into terminal T1. As a result, the motor 30 is driven and the seat back 15 moves in the rearward direction R. The second current flows into terminal T1 through the limit switch 102.

[0066] 6 is a diagram illustrating the flow of current in the motor drive device 100 when the limit switch 101 detects the limit position LM1. In this example, a control signal CS having a positive voltage is generated.

[0067] Referring to FIG. 6, when the limit switch 101 opens due to the detection of the limit position LM1, the second current flows to the base of the transistor TR3 without flowing through the limit switch 101. This turns on the transistor TR3. As a result, the transistor TR1 turns on, and the first current flows to the reactor L1 of the relay unit 110. This connects the contacts P1 and P3 (the contact relay 111 switches from on to off). As a result, the current supply to the motor 30 stops. This stops the motor 30, and the operation of the seat back 15 stops. The second current flows into the signal conversion unit 131 and then flows into the terminal T2 via the signal conversion unit 132.

[0068] In this example, the second current is a signal indicating the detection result of the limit switch 101. This signal is amplified by the signal conversion unit 131 and then supplied to the reactor L1 as a signal of the first current.

[0069] In the above, when the limit switch 101 detects the limit position LM1 while the seat back 15 is in operation, a current flows in the motor drive device 100 to stop the motor 30. On the other hand, when the limit switch 102 detects the limit position LM2 while the seat back 15 is in operation, a current also flows in the motor drive device 100 (not shown) to stop the motor 30.

[0070] In this way, motor drive device 100 can switch between driving and stopping motor 30 in accordance with the detection results of limit switches 101 and 102. Therefore, ECU 200 does not need to have a function for determining these detection results (specifically, a component such as a dedicated circuit or module for performing that function). In other words, a general-purpose control device can be used as ECU 200, rather than a dedicated control device having such a function.

[0071] 7 is a diagram showing the state of motor drive device 100 when a command to stop motor 30 is issued via ECU 200 by a user operation using operation unit 28. In this example, a command to stop motor 30 is issued when limit position LM1 is detected by limit switch 101, but the user may also issue a command to stop motor 30 when limit position LM1 has not been detected.

[0072] 7, ECU 200 controls contact relays 217 and 219 so that contacts P01 and P03 are connected and contacts P04 and P06 are connected. As a result, the potential of terminal T1 and the potential of terminal T2 both become equal to the ground potential. As a result, the difference between these potentials becomes zero, and therefore control signal CS is no longer generated (electrical connection between driver 215 and power supply 400 is cut off). Therefore, motor 30 stops.

[0073] In this example, each of the contact relays 111, 112 is in an open / closed state so that the motor 30 stops with both ends of the motor 30 shorted. In this way, when an instruction to stop the motor 30 is given, both ends of the motor 30 are shorted. This allows the regenerative braking of the motor 30 to operate even if an unintended external force is applied to the seat 1 (more specifically, the seat back 15) while the motor 30 is stopped, causing a rotational force to be applied to the motor 30 and causing the motor 30 to move. As a result, unintended movement of the seat 1 can be prevented.

[0074] As described above, drive circuit 105 of motor drive device 100 according to this embodiment stops motor 30 when limit switch 101 (102) detects limit position LM1 (LM2). On the other hand, drive circuit 105 is configured to drive motor 30 using control signal CS as a power source when limit switch 101 (102) has not detected limit position LM1 (LM2). This makes it possible to prevent an increase in the number of parts in motor drive device 100 and avoid excess power consumption.

[0075] [Variation 1] Fig. 8 is a diagram showing a detailed configuration of a motor drive device according to Modification 1. Referring to Fig. 8, motor drive device 100A differs from motor drive device 100 according to the above-described embodiment (Figs. 2 to 7) in that it includes device 103A instead of device 103.

[0076] The device 103A includes a relay unit 110A, modules 121A and 122A, signal conversion units 131A and 132A, and a bridge circuit 180.

[0077] The relay unit 110A includes reactors L11 and L12 and contact relays 111A and 112A. The contact relay 111A switches between driving and stopping the motor 30 by switching its open / close state depending on whether or not a current is flowing through the reactor L11. Similarly, the contact relay 112A switches between driving and stopping the motor 30 by switching its open / close state depending on whether or not a current is flowing through the reactor L12. Each of the contact relays 111A and 112A is an a-contact relay. Specifically, the contact relays 111A and 112A are turned on when a current is flowing through the reactors L11 and L12, respectively, and turned off otherwise.

[0078] Module 121A includes diodes D11 and D13. Module 122A includes diodes D12 and D14. The functions of modules 121A and 122A are basically the same as the functions of modules 121 and 122 (FIGS. 3 to 7), respectively.

[0079] The signal conversion unit 131A includes transistors TR11 and TR13, resistors R12 to R15, and diodes D13, D15, and D17. The signal conversion unit 132A includes transistors TR12 and TR14, resistors R16 to R20, and diodes D16 and D18. The functions of the signal conversion units 131A and 132A are basically the same as the functions of the signal conversion units 131 and 132 (FIGS. 3 to 7), respectively.

[0080] Bridge circuit 180 includes diodes D21 to D24, a resistor R11, and a capacitor C1. Bridge circuit 180 is provided to enable motor driving device 100A to drive motor 30 regardless of whether the potential difference between terminals T1 and T2 (the voltage of control signal CS) is positive or negative.

[0081] 9 is a diagram illustrating the current flow in the motor drive device 100A when the control signal CS having a positive voltage is generated by the ECU 200. Because the position of the seat back 15 does not exceed the limit position LM1 or the limit position LM2, the limit switches 101 and 102 are closed (not activated).

[0082] In this example, the current (two-dot chain arrow) flowing through the contact relay 111A of the relay unit 110A is represented as a first current, the current (dashed arrow) flowing through the reactor L11 of the relay unit 110A is represented as a second current (dashed arrow), and the current (thick dashed arrow) flowing through the signal conversion unit 131A is represented as a third current.

[0083] 9, in this example, because the limit switch 101 is closed, a third current (indicated by a thick dashed-dotted arrow) flows through the base of the transistor TR11, turning the transistor TR11 on. This causes a second current (indicated by a dashed-dotted arrow) to flow through the reactor L11 of the relay unit 110A. As a result, the contacts P11 and P13 are connected, turning the contact relay 111A on. Similarly, the transistor TR12 is turned on, causing a current to flow through the reactor L12 of the relay unit 110A (not shown). This causes the contacts P15 and P17 to be connected, turning the contact relay 112A on. As a result, the first current (indicated by a two-dot dashed-dotted arrow) is supplied to the motor 30 through the capacitor C1 and diode D22 of the bridge circuit 180 and the contact relay 111A of the relay unit 110, driving the motor 30.

[0084] When the limit switch 101 detects the limit position LM1, the contact relay 111A switches from on to off. Specifically, the contact connected to the contact P11 switches from contact P13 to contact P12. As a result, the current supply to the motor 30 is cut off, and the motor 30 stops.

[0085] Similarly, when the limit switch 102 detects the limit position LM2, the contact relay 112A switches from on to off. Specifically, the contact connected to the contact P15 switches from the contact P17 to the contact P16. As a result, the current supply to the motor 30 is cut off, and the motor 30 stops.

[0086] When the motor 30 is stopped due to the detection of the limit position LM1 (LM2) by the limit switch 101 (102), the supply of the control signal CS to the motor drive device may be stopped. When the control signal CS is subsequently supplied again to the motor drive device to instruct the motor 30 to operate, depending on the configuration of the motor drive device, the current of the control signal CS may not be immediately supplied to the reactor of the relay due to its induced electromotive force. This current may be temporarily supplied to the motor 30 before it begins to be supplied to the reactor. As a result, even though the limit switch 101 (102) detects the limit position LM1 (LM2), the motor 30 may operate, causing the seat 1 to temporarily move beyond the limit position LM1 (LM2). Therefore, the above-described current supply to the motor 30 is unintended and undesirable.

[0087] 10 is a diagram showing the state of motor driving device 100A when limit switch 101 detects limit position LM1. For ease of explanation, the flow of current in motor driving device 100A is not shown.

[0088] 10, when the limit switch 101 detects the limit position LM1, it opens, turning off the transistor TR11 and preventing current from flowing through the reactor L11. As a result, the contact relay 111A switches between open and closed states (turns off) so that the motor 30 stops in a state electrically disconnected from the ECU 200.

[0089] Similarly, when the limit switch 102 detects the limit position LM2, the transistor TR12 is turned off, and no current flows through the reactor L12 any more. As a result, the contact relay 112A switches between an open and closed state (is turned off) so that the motor 30 stops in a state electrically disconnected from the ECU 200.

[0090] In this modification, when the limit switch 101 (102) detects the limit position LM1 (LM2), the motor 30 is electrically disconnected from the ECU 200 (control signal CS). As a result, when the supply of the control signal CS to the motor drive device 100A is stopped and then the supply of the control signal CS to the motor drive device 100A is resumed, it is possible to prevent the unintended supply of current to the motor 30 as described above. As a result, it is possible to prevent the seat 1 from temporarily moving beyond the limit position LM1 (LM2).

[0091] [Variation 2] Figure 11 is a diagram showing the configuration of a motor control system according to Modification 2. Referring to Figure 11, motor control system 50A differs from motor control system 50 (Figure 2) in that ECU 200 and power supply 400 are omitted.

[0092] Like the control signal CS, the control signal CS1 is a signal for controlling the rotation direction of the motor 30, and is generated by the operation unit 28. Specifically, the control signal CS1 indicates whether or not the operation of the seat back 15 has been instructed by the user using the operation unit 28, and if so, whether the operation direction is the forward direction F or the rearward direction R. The motor drive device 100 (drive circuit 105) is configured to use the control signal CS1 as a power source and drive the motor 30 in accordance with the control signal CS1.

[0093] In this manner, motor drive device 100 may be directly connected to operation unit 28. This allows the configuration of motor control system 50A to be simpler than the configuration of motor control system 50. In this modification, operation unit 28 is an example of the "signal generating device" of the present disclosure.

[0094] [Other variations] The operation unit 28, the ECU 200, and the motor drive device 100 (100A) may be used to drive a motor for moving the main body of the seat 1 (FIG. 1) in the X-axis direction or the Y-axis direction, or for raising or lowering the main body in the Z-axis direction. In this case, the movement limit position of the seat 1 is, for example, the movement limit position of the seat cushion 10 in the X-axis direction, the Y-axis direction, or the Z-axis direction (FIG. 1).

[0095] The operation unit 28, the ECU 200, and the motor drive device 100 (100A) may be used to drive a motor for operating the ottoman 5. In this case, the movement limit position of the seat 1 is the movement limit position (operation limit position) of the ottoman 5 in the direction DR1 or the direction DR2. Alternatively, the operation unit 28, the ECU 200, and the motor drive device 100 (100A) may be used to drive a motor for moving the headrest 20.

[0096] The logical configuration of each of the signal conversion units 131, 132 (FIGS. 3 to 7) may be inverted. In this case, normally open limit switches are used as the limit switches 101, 102. Similarly, when the logical configuration of each of the signal conversion units 131A, 132A (FIGS. 8 to 10) is inverted, normally open limit switches are used.

[0097] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0098] 1 seat, 28 operation unit, 30 motor, 50,50A motor control system, 100,100A motor drive device, 101,102 limit switch, 103,103A equipment, 105 drive circuit, 110,110A relay unit, 111,111A,112,112A,217,219 contact relay, 120 relay drive unit, 130 signal conversion circuit, 131,131A,132,132A signal conversion unit, 400 power supply, CS,CS1 control signal, L1,L2,L11,L12 reactor.

Claims

1. A motor drive device configured to be connected between a motor for moving a seat and a signal generator that generates a control signal for controlling a rotation direction of the motor when a command to drive the motor is issued, a limit switch configured to detect a limit position of the seat; a drive circuit configured to use the control signal as a power source and drive the motor in accordance with the control signal; The drive circuit stopping the motor when the limit switch detects the movement limit position; driving the motor when the limit switch does not detect the movement limit position; The drive circuit A reactor, a contact relay that switches between driving and stopping the motor by switching an open / closed state according to the presence or absence of a current flowing through the reactor, The limit switch is configured to open when the limit switch detects the travel limit position, The motor drive device further includes an intervening circuit connected between the reactor and the limit switch, The motor drive device, wherein the intervening circuit is an amplifier circuit configured to amplify a signal indicating a detection result of the limit switch and supply the amplified signal to the reactor.

2. the motor is a DC motor, 2. The motor drive device according to claim 1, wherein when an instruction to stop the DC motor is given, the contact relay takes the open / closed state so that both ends of the DC motor are short-circuited and the DC motor stops.

3. A motor driving device as described in claim 1, wherein when the limit switch detects the limit of travel, the contact relay switches the open / closed state so that the motor stops in a state electrically disconnected from the signal generating device.

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