WO2020095709A1 - Seatbelt retractor and seatbelt device - Google Patents

Seatbelt retractor and seatbelt device Download PDF

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Publication number
WO2020095709A1
WO2020095709A1 PCT/JP2019/041823 JP2019041823W WO2020095709A1 WO 2020095709 A1 WO2020095709 A1 WO 2020095709A1 JP 2019041823 W JP2019041823 W JP 2019041823W WO 2020095709 A1 WO2020095709 A1 WO 2020095709A1
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WO
WIPO (PCT)
Prior art keywords
current
control circuit
seat belt
motor
switching element
Prior art date
Application number
PCT/JP2019/041823
Other languages
French (fr)
Japanese (ja)
Inventor
雅人 高尾
Original Assignee
Ｊｏｙｓｏｎ Ｓａｆｅｔｙ Ｓｙｓｔｅｍｓ Ｊａｐａｎ株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by Ｊｏｙｓｏｎ Ｓａｆｅｔｙ Ｓｙｓｔｅｍｓ Ｊａｐａｎ株式会社 filed Critical Ｊｏｙｓｏｎ Ｓａｆｅｔｙ Ｓｙｓｔｅｍｓ Ｊａｐａｎ株式会社
Publication of WO2020095709A1 publication Critical patent/WO2020095709A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R22/00—Safety belts or body harnesses in vehicles
    • B60R22/34—Belt retractors, e.g. reels
    • B60R22/46—Reels with means to tension the belt in an emergency by forced winding up
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R22/00—Safety belts or body harnesses in vehicles
    • B60R22/48—Control systems, alarms, or interlock systems, for the correct application of the belt or harness
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P7/00—Arrangements for regulating or controlling the speed or torque of electric DC motors
    • H02P7/06—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current
    • H02P7/18—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power
    • H02P7/24—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices
    • H02P7/28—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices
    • H02P7/285—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature supply only
    • H02P7/29—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature supply only using pulse modulation

Definitions

  • the present invention relates to a seat belt retractor and a seat belt device.
  • a motor drive circuit in which, when a counter electromotive force is generated in a motor by an external force applied to a spool that winds up a seat belt, the FET is turned on to cause a current to flow back to the motor through the FET (for example, a patent). Reference 1).
  • the energy absorption load (the load acting on the seat belt) can be adjusted accurately. difficult.
  • the energy absorption load is also referred to as “EA load”.
  • the present disclosure provides a seatbelt retractor and a seatbelt device capable of accurately adjusting the EA load.
  • This disclosure is Spool, A motor for rotating the spool, A switching element connected to the motor, A control circuit for switching the switching element by PWM control so that the motor rotates in a direction in which the seat belt is wound around the spool; A return path that is connected to the switching element and returns a current generated by a back electromotive force of the motor to the motor;
  • a seatbelt retractor and a seatbelt device comprising: a current control circuit that controls the magnitude of the current flowing through the return path.
  • FIG. 6 is a diagram showing an example of a relationship between a rotation speed of a motor when a seat belt is pulled out and a current flowing through a bypass due to a back electromotive force of the motor when the current control circuit shown in FIGS. 3 and 4 is used. It is a figure which shows the 3rd structural example of a current control circuit.
  • FIG. 8 is a diagram showing an example of a relationship between a rotation speed of a motor when a seat belt is pulled out and a current flowing through a bypass due to a back electromotive force of the motor when the current control circuit shown in FIGS. 6 and 7 is used. It is a figure which shows the 5th example of a structure of a current control circuit. It is a figure which shows the 6th example of a structure of a current control circuit.
  • FIG. 11 is a diagram showing an example of the relationship between the rotational speed of the motor when the seat belt is pulled out and the current flowing in the bypass due to the back electromotive force of the motor when the current control circuit shown in FIGS.
  • FIG. 1 is a configuration diagram schematically showing an example of a seat belt device 100.
  • the seat belt device 100 is mounted on a vehicle 13 such as an automobile.
  • the seat belt device 100 includes, for example, a seat belt 2, a shoulder anchor 3, a tongue 4, a buckle 5, and a seat belt retractor (hereinafter, also simply referred to as “retractor”) 10.
  • the retractor 10 includes a seat belt retracting mechanism (hereinafter, also simply referred to as “retracting mechanism”) 6 and a control device 1.
  • the seat belt 2 is an example of a belt-shaped member that restrains the occupant 9 sitting on the seat 11 of the vehicle 13, and is wound around the winding mechanism 6 so as to be pulled out from the winding mechanism 6.
  • One end of the seat belt 2 is connected to the winding mechanism 6, and the other end of the seat belt 2 is fixed to the vehicle body, the pretensioner device, the seat 11, or the like.
  • the seat belt is also called webbing.
  • the shoulder anchor 3 is a guide member that guides the seat belt 2 pulled out from the winding mechanism 6 toward the shoulder of the occupant 9, and is fixed to, for example, the side wall of the passenger compartment or the seat 11.
  • the tongue 4 is a member slidably attached to the seat belt 2 guided by the shoulder anchor 3.
  • the buckle 5 is an example of a member to which the tongue 4 is detachably engaged, and is fixed to, for example, the floor of the vehicle body or the seat 11.
  • the retractor 10 is fixed to, for example, the vehicle body near the seat 11 or the seat 11 itself.
  • the retractor 10 includes a winding mechanism 6 that allows the seat belt 2 to be wound or pulled out, and a control device 1 that controls the operation of the winding mechanism 6.
  • the winding mechanism 6 includes a spool 8 for winding the seat belt 2, a motor 7 for rotating the spool 8, and a power transmission mechanism 17 for transmitting power between the motor 7 and the spool 8.
  • One end of the seat belt 2 is fixed to the spool 8.
  • the motor 7 generates a driving force that rotates the spool 8.
  • the rotation shaft of the motor 7 is connected to the rotation shaft of the spool 8 via the power transmission mechanism 17.
  • the control device 1 controls the winding operation (or both the winding operation and the withdrawing operation) of the seat belt 2 by the winding mechanism 6 by driving the motor 7.
  • the control device 1 includes a drive circuit 14 that drives the motor 7, and a control circuit 15 that controls the drive operation of the drive circuit 14.
  • the drive circuit 14 supplies a drive current for driving the motor 7 to the motor 7 according to at least one control signal (for example, a PWM (pulse width modulation) control signal) supplied from the control circuit 15.
  • a PWM (pulse width modulation) control signal supplied from the control circuit 15.
  • the drive circuit 14 include an H-bridge drive circuit that drives the motor 7 with four switching elements, and a half-bridge drive circuit that drives the motor 7 with two switching elements on the high side and the low side.
  • the drive circuit 14 may be a high-side drive circuit that drives the motor 7 with a high-side switching element, or a low-side drive circuit that drives the motor 7 with a low-side switching element.
  • the form of the drive circuit 14 is not limited to these, but is determined according to the required specifications.
  • the control circuit 15 outputs to the drive circuit 14 at least one control signal (for example, a PWM control signal) that controls the magnitude of the drive current (or the magnitude and direction of the drive current) that drives the motor 7. To do.
  • a control signal for example, a PWM control signal
  • Each function of the control circuit 15 is realized by operating a CPU (Central Processing Unit) according to a program stored in the memory.
  • a specific example of the control circuit 15 is a microcomputer including a CPU and a memory.
  • FIG. 2 is a diagram showing a first configuration example of the drive circuit 14.
  • the drive circuit 14A shown in FIG. 2 is an H-bridge drive circuit that has four switching elements 21, 22, 23, and 24 and is capable of switching the direction of the drive current supplied to the motor 7.
  • the motor 7 contains a coil connected between the first terminal 7a and the second terminal 7b.
  • the drive circuit 14A has a first connection point 18 connected to the first terminal 7a of the motor 7 and a second connection point 12 connected to the second terminal 7b of the motor 7, Drive current is passed through the first connection point 18 and the second connection point 12.
  • the first connection point 18 is an intermediate node where the switching element 21 and the switching element 22 are connected
  • the second connection point 12 is an intermediate node where the switching element 23 and the switching element 24 are connected.
  • the drive circuit 14A is connected between the power supply VB and the ground (GND), and the high-side switching elements 21 and 23 connected to the power supply VB side with respect to the motor 7 and the ground side with respect to the motor 7. And low side switching elements 22 and 24 connected to.
  • the switching elements 21, 22, 23, and 24 are semiconductor elements that perform on / off operations, and may be voltage-controlled transistors or current-controlled bipolar transistors. Voltage-controlled transistors include IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal Oxide Semiconductor Field Effect Transistors).
  • FIG. 2 illustrates a mode in which the switching elements 21, 22, 23 and 24 are N-channel type MOSFETs.
  • the switching element 21 is an example of a first high side switching element connected to the first terminal 7a.
  • the switching element 21 includes an electrode (drain or collector) connected to the power supply VB side, an electrode (source or emitter) connected to the first terminal 7a via the first connection point 18, and a control circuit 15. It is a high side arm having an electrode (gate or base) connected thereto.
  • the switching element 22 is an example of a first low-side switching element connected to the first terminal 7a.
  • the switching element 22 is connected to the electrode (source or emitter) connected to the ground side, the electrode (drain or collector) connected to the first terminal 7 a via the first connection point 18, and the control circuit 15. And a low side arm having an electrode (gate or base) to be driven.
  • the switching element 23 is an example of a second high side switching element connected to the second terminal 7b.
  • the switching element 23 includes an electrode (drain or collector) connected to the power supply VB side, an electrode (source or emitter) connected to the second terminal 7b through the second connection point 12, and a control circuit 15. It is a high side arm having an electrode (gate or base) connected thereto.
  • the switching element 24 is an example of a second low side switching element connected to the second terminal 7b.
  • the switching element 24 is connected to the electrode (source or emitter) connected to the ground side, the electrode (drain or collector) connected to the second terminal 7b through the second connection point 12, and the control circuit 15.
  • the diodes 31, 32, 33, 34 may be body diodes of the corresponding switching elements 21, 22, 23, 24, or are additionally connected in parallel to the corresponding switching elements 21, 22, 23, 24.
  • a rectifying element may be used.
  • the current measuring circuit 16 is a current measuring unit that measures the current flowing through the drive circuit 14A and outputs the measurement result to the control circuit 15.
  • the current measuring circuit 16 measures the magnitude of the current flowing through the drive circuit 14A by, for example, a resistor inserted in series in the current path between the low-side switching elements 22 and 24 of the drive circuit 14A and the ground.
  • the current path between the switching elements 22 and 24 and the ground is a current path that connects electrodes (sources or emitters) connected to the ground side of the switching elements 22 and 24 (specifically, returns to the motor 7).
  • the meaning of a path through which a current I EA described later passes) is included.
  • the current measuring circuit 16 determines the magnitude of the current flowing through the drive circuit 14A by, for example, a resistor inserted in series in the current path between the high-side switching elements 21 and 23 of the drive circuit 14A and the power supply VB. You may measure.
  • the current measurement method is not limited to these.
  • the control circuit 15 is a drive control unit that drives the four switching elements 21, 22, 23, 24 forming the drive circuit 14A by using the current measurement result of the current measurement circuit 16 and the like.
  • the control circuit 15 drives the motor 7 to rotate (forward rotation) in the forward rotation direction corresponding to the winding direction of the seat belt 2. It controls each switching element of the circuit 14A. For example, in the winding mode in which the motor 7 rotates forward, the control circuit 15 turns on / off (switches) the switching element 22 by PWM control with a predetermined duty ratio, constantly turns off the switching elements 21 and 24, and switches the switching element. 23 is always turned on. At this time, the control circuit 15 may turn on the switching element 21 when the switching element 22 is off, in order to suppress heat generation due to the return current when the switching element 22 is off.
  • the drive circuit 14A can rotate the motor 7 (normal rotation) in the direction of rotating the spool 8 in the winding direction of the seat belt 2 (normal rotation direction). it can.
  • the rotation shaft of the motor 7 rotates in the forward direction
  • the drive force of the forward rotation is transmitted to the spool 8 by the power transmission mechanism 17.
  • the spool 8 rotates in the direction in which the seat belt 2 is wound, so that the seat belt 2 is wound around the spool 8.
  • the control circuit 15 drives the drive circuit 14A so that the motor 7 rotates in the reverse direction corresponding to the pull-out direction of the seat belt 2 (reverse rotation).
  • the control circuit 15 turns on / off (switches) the switching element 24 by PWM control with a predetermined duty ratio to constantly turn off the switching elements 22 and 23, and the switching element 21. Is always on.
  • the control circuit 15 may turn on the switching element 23 when the switching element 24 is off in order to suppress heat generation due to the return current when the switching element 24 is off.
  • the drive circuit 14A can rotate the motor 7 (reverse rotation) in the direction of rotating the spool 8 in the direction of withdrawing the seat belt 2 (reverse rotation).
  • the rotation shaft of the motor 7 rotates in the reverse direction
  • the driving force of the reverse rotation is transmitted to the spool 8 by the power transmission mechanism 17.
  • the spool 8 rotates in the direction in which the seat belt 2 is pulled out, so that the seat belt 2 is pulled out from the spool 8.
  • the drive circuit 14A includes a current adjustment circuit 44 connected in parallel with the switching element 22.
  • a current adjustment circuit 44 When the rotating shaft of the motor 7 and the rotating shaft of the spool 8 are connected by the power transmission mechanism 17, when the motor 7 is rotated by an external force applied to the spool 8, a counter electromotive force is generated in the motor 7.
  • the current adjusting circuit 44 causes the current I EA generated by this back electromotive force to flow back to the motor 7, thereby suppressing the rotation of the motor 7 and applying the brake.
  • the vehicle-mounted computer outside the retractor 10 transmits a command signal for starting the restraint force control of the seat belt 2 on the occupant 9.
  • the control circuit 15 receives a command signal from an in-vehicle computer outside the retractor 10 and the like, and the seat belt 2 The restraint force control for the occupant 9 is started.
  • the control circuit 15 prepares for an impact at the time of a collision, so that the motor 7 rotates (normal rotation) in the normal rotation direction corresponding to the winding direction of the seat belt 2 so that the drive circuit 14A operates. Control each switching element.
  • the rotation shaft of the motor 7 rotates in the forward direction
  • the drive force of the forward rotation is transmitted to the spool 8 by the power transmission mechanism 17.
  • the spool 8 rotates in the direction in which the seat belt 2 is wound, so that the seat belt 2 is wound around the spool 8.
  • the restraint force on the occupant 9 by the seat belt 2 increases.
  • the seat belt 2 is pulled out from the spool 8 by the inertial force of the occupant 9 toward the front of the vehicle.
  • the rotational force is transmitted to the rotation shaft of the motor 7 by the power transmission mechanism 17.
  • the rotating shaft of the motor 7 is rotated in the reverse direction, so that a counter electromotive force is generated in the motor 7. Due to the generation of this counter electromotive force, the potential of the first terminal 7a becomes relatively higher than the potential of the second terminal 7b (in other words, the potential of the second terminal 7b is higher than the potential of the first terminal 7a. Is also relatively low).
  • the control circuit 15 when the control circuit 15 receives the command signal indicating that the collision of the vehicle 13 is detected, the control circuit 15 rotates the motor 7 in the forward rotation direction in which the spool 8 is rotated in the winding direction of the seat belt 2, and then, The bypass 45 is switched from the disconnected state to the connected state.
  • the bypass 45 is a current path that is connected in parallel to both ends of the switching element 22 and causes the current I EA generated by the back electromotive force of the motor 7 to flow back to the motor 7.
  • the bypass 45 is a part of a return path for returning the current I EA to the motor 7.
  • the control circuit 15 may turn on the switching element 24 so that the current I EA flows through the switching element 24 instead of the diode 34.
  • control circuit 15 causes the current I EA generated by the back electromotive force to flow back to the motor 7 via the bypass 45, so that the motor 7 rotates in the reverse direction in which the spool 8 is rotated in the pulling direction of the seat belt 2. Can be suppressed. As a result, it becomes possible to absorb the collision energy that acts on the occupant 9 during a vehicle collision.
  • the control circuit 15 when the control circuit 15 receives a command signal indicating that the collision of the vehicle 13 is detected, the control circuit 15 operates the changeover switch 40 that is inserted in series with the detour 45 to remove the detour 45 from the cutoff state. Switch to the connected state.
  • the changeover switch 40 is, for example, a switching element such as a MOSFET.
  • the current adjustment circuit 44 inserted in series in the bypass circuit 45 has, for example, a configuration in which the changeover switch 40 and the current control circuit 41 are connected in series.
  • the changeover switch 40 and the current control circuit 41 are inserted in the detour 45 in series.
  • the positions where the changeover switch 40 and the current control circuit 41 are inserted in series in the bypass 45 may be replaced with each other.
  • the current control circuit 41 controls the magnitude of the current I EA flowing through the bypass 45.
  • the force that suppresses the rotation of the motor 7 in the reverse rotation direction that rotates the spool 8 in the pull-out direction of the seat belt 2 changes, so the EA load (the load acting on the seat belt 2 is changed. ) Also changes.
  • the EA load increases as the current I EA increases. Therefore, the current control circuit 41 controls the magnitude of the current I EA , whereby the EA load can be adjusted with high accuracy.
  • the current control circuit 41 may have a configuration in which the magnitude of the current I EA flowing through the detour 45 is limited so as not to exceed a predetermined upper limit value (hereinafter, also referred to as upper limit current I U ). With such a configuration, the EA load can be limited to the upper limit load F U or less corresponding to the upper limit current I U , so that the EA load can be prevented from becoming too large.
  • a predetermined upper limit value hereinafter, also referred to as upper limit current I U .
  • the current control circuit 41 may have a configuration for adjusting the upper limit current I U according to an adjustment signal supplied from the outside.
  • the upper limit load F U can be adjusted by adjusting the upper limit current I U.
  • the control circuit 15 supplies the current control circuit 41 with an adjustment signal for adjusting the upper limit current I U based on the physique information such as the weight of the occupant 9. Accordingly, the upper limit current I U and the upper limit load F U suitable for the physique of the occupant 9 can be set. For example, as the weight of the occupant 9 becomes heavier, the upper limit current I U and the upper limit load F U are set higher.
  • FIG. 3 is a diagram showing a first configuration example of the current control circuit 41.
  • the current control circuit 41A shown in FIG. 3 is connected in series between the first node 42 and the second node 43 on the bypass 45.
  • the current control circuit 41A is a current limiting circuit that limits the magnitude of the current I EA flowing in the bypass 45 so as not to exceed a predetermined upper limit current I U.
  • the current control circuit 41A has resistors 51, 52, 53, npn-type bipolar transistors 54, 55, and zener diodes 56, 57.
  • the base current flowing from the power supply VB to the base of the bipolar transistor 54 via the resistor 51 causes the current I EA to flow from the collector of the bipolar transistor 54 to the emitter.
  • the resistor 53 is connected to the emitter of the bipolar transistor 54 so as to be inserted in the detour 45 in series.
  • the collector current of the bipolar transistor 55 flows.
  • the base current flowing from the power supply VB to the base of the bipolar transistor 54 via the resistor 51 decreases.
  • the current I EA is limited so as not to exceed the upper limit current I U.
  • the upper limit current I U is set by “(R53 / (R52 + R53)) ⁇ V BE55 ”.
  • R52 and R53 represent resistance values of the resistors 52 and 53, respectively.
  • V BE55 represents the base-emitter voltage of the bipolar transistor 55, with an upper limit of approximately 0.6 volts.
  • the current control circuit 41A detects the magnitude of the current I EA flowing through the bypass 45 by using the resistor 53, and controls the magnitude of the current I EA flowing through the bypass 45 based on the detection result. To do. By feeding back the detection result, the current control circuit 41A limits the magnitude of the current I EA flowing through the bypass 45 so as not to exceed the upper limit current I U.
  • the Zener diode 56 is an element that protects the base-emitter of the bipolar transistor 54 from overvoltage.
  • the Zener diode 57 is an element that protects the base-emitter of the bipolar transistor 55 from overvoltage.
  • FIG. 4 is a diagram showing a second configuration example of the current control circuit 41.
  • the current control circuit 41B shown in FIG. 4 is connected in series between the first node 42 and the second node 43 on the bypass 45.
  • the current control circuit 41B is a current limiting circuit that limits the magnitude of the current I EA flowing through the bypass 45 so as not to exceed a predetermined upper limit current I U.
  • the current control circuit 41B also has a configuration of adjusting the upper limit current I U according to an adjustment signal S U supplied from the outside.
  • the current control circuit 41B includes resistors 61 to 65, an npn-type bipolar transistor 66, a Zener diode 67, and a comparator 68.
  • the bypass circuit 45 When the bypass circuit 45 is switched from the cut-off state to the connection state, the base current flowing from the power supply VB to the base of the bipolar transistor 66 via the resistor 63 causes the current I EA to flow from the collector of the bipolar transistor 66 to the emitter.
  • the resistor 65 is connected to the emitter of the bipolar transistor 66 so as to be inserted in series with the bypass 45.
  • the comparator 68 sinks current from its output terminal.
  • the current is absorbed in the output terminal of the comparator 68, the base current flowing from the power supply VB to the base of the bipolar transistor 66 via the resistor 63 decreases.
  • the current I EA is limited so as not to exceed the upper limit current I U.
  • Adjustment signal S U to adjust the upper limit current I U, via a resistor 61, is input to the non-inverting input terminal of the comparator 68.
  • the voltage of the non-inverting input terminal of the comparator 68 changes according to the analog voltage value of the adjustment signal S U. Therefore, the upper limit current I U is adjusted to a current value according to the analog voltage value of the adjustment signal S U.
  • the adjustment signal S U may be supplied from the control circuit 15 or may be supplied from a circuit or a device different from the control circuit 15.
  • the current control circuit 41B detects the magnitude of the current I EA flowing in the bypass 45 by using the resistor 65, and controls the magnitude of the current I EA flowing in the bypass 45 based on the detection result. To do.
  • the current control circuit 41B limits the magnitude of the current I EA flowing through the bypass 45 so as not to exceed the upper limit current I U by feeding back the detection result.
  • the Zener diode 67 is an element that protects the base-emitter of the bipolar transistor 66 from overvoltage.
  • FIG. 5 shows the rotation speed of the motor 7 when the seat belt 2 is pulled out and the current flowing through the bypass 45 due to the counter electromotive force of the motor 7 when the current control circuits 41A and 41B shown in FIGS. It is a figure which shows an example of the relationship of.
  • the detour 45 When the detour 45 is in the cutoff state (open state), the current I EA does not flow in the detour 45.
  • the detour 45 is in the connected state (short-circuited state)
  • the higher the speed at which the motor 7 rotates in the reverse rotation direction corresponding to the direction in which the seat belt 2 is pulled out the larger the current I EA flowing through the detour 45 becomes. , EA load also increases.
  • the current I EA larger than the predetermined upper limit current I U does not flow like the current limits a and b shown in FIG.
  • the EA load can be limited to the upper limit load F U or less corresponding to U.
  • the upper limit current I U can be adjusted to a desired current value according to the adjustment signal S U.
  • the current control circuit 41 shown in FIG. 2 prevents the current I EA from flowing into the bypass 45 until the counter electromotive force of the motor 7 exceeds a predetermined lower limit value (hereinafter, also referred to as lower limit voltage VL ).
  • the configuration may be limited to. With such a configuration, the efficiency of the current I EA flowing back to the motor 7 decreases with respect to the rotation speed of the motor 7, so that the relationship between the rotation speed of the motor 7 and the EA load (more specifically, the motor 7 The inclination characteristic of the EA load with respect to the rotation speed) can be adjusted as shown in FIG. That is, the inclination characteristic of the EA load with respect to the rotation speed of the motor 7 can be made gentle.
  • the current control circuit 41 may have a configuration of adjusting the lower limit voltage VL according to an adjustment signal supplied from the outside.
  • the control circuit 15 supplies the current control circuit 41 with an adjustment signal for adjusting the lower limit voltage VL based on the physique information such as the weight of the occupant 9.
  • the relationship between the rotation speed of the motor 7 and the EA load can be set to a characteristic suitable for the physique of the occupant 9. For example, the lower the weight of the occupant 9, the higher the lower limit voltage VL is set.
  • FIG. 6 is a diagram showing a third configuration example of the current control circuit 41.
  • the current control circuit 41C shown in FIG. 6 is connected in series between the first node 42 and the second node 43 on the bypass 45.
  • the current control circuit 41C is a current limiting circuit that limits the current I EA from flowing into the bypass 45 until the counter electromotive force generated in the motor 7 exceeds a predetermined lower limit voltage V L.
  • the current control circuit 41C has resistors 71 and 72, an npn-type bipolar transistor 73, and a Zener diode 74.
  • the bipolar transistor 73 When the counter electromotive force of the motor 7 rises and the base-emitter voltage of the bipolar transistor 73 becomes larger than about 0.6 volt, the bipolar transistor 73 is turned on. As a result, the current I EA flowing between the collector and the emitter of the bipolar transistor 73 rapidly increases from substantially zero. That is, the current I EA is limited so as not to flow to the bypass 45 until the counter electromotive force generated in the motor 7 exceeds the predetermined lower limit voltage V L.
  • the current control circuit 41C detects the magnitude of the back electromotive force of the motor 7 using the resistors 71 and 72, and controls the magnitude of the current I EA flowing through the bypass 45 based on the detection result. To do.
  • the Zener diode 74 is an element that protects the base-emitter of the bipolar transistor 73 from overvoltage.
  • FIG. 7 is a diagram showing a fourth configuration example of the current control circuit 41.
  • the current control circuit 41D shown in FIG. 7 is connected in series between the first node 42 and the second node 43 on the bypass 45.
  • the current control circuit 41D is a current limiting circuit that limits the current I EA from flowing into the bypass 45 until the counter electromotive force generated in the motor 7 exceeds a predetermined lower limit voltage V L.
  • the current control circuit 41D also has a configuration of adjusting the lower limit voltage V L according to an adjustment signal S L supplied from the outside.
  • the current control circuit 41D has resistors 81 to 85, an npn-type bipolar transistor 86, a Zener diode 87, and a comparator 88.
  • Adjustment signal S L to adjust the lower limit voltage V L, via a resistor 81, it is input to the inverting input terminal of the comparator 88.
  • the voltage at the inverting input terminal of the comparator 88 changes according to the analog voltage value of the adjustment signal S L. Therefore, the lower limit voltage V L is adjusted to a voltage value according to the analog voltage value of the adjustment signal S L.
  • the adjustment signal S L may be supplied from the control circuit 15 or may be supplied from a circuit or a device different from the control circuit 15.
  • the current control circuit 41D detects the magnitude of the back electromotive force of the motor 7 by using the resistors 84 and 85, and controls the magnitude of the current I EA flowing through the bypass 45 based on the detection result. To do.
  • the Zener diode 87 is an element that protects the base-emitter of the bipolar transistor 86 from overvoltage.
  • FIG. 8 shows the rotation speed of the motor 7 when the seat belt 2 is pulled out and the current flowing in the bypass 45 by the counter electromotive force of the motor 7 when the current control circuits 41C and 41D shown in FIGS. It is a figure which shows an example of the relationship of.
  • the current control circuits 41C and 41D shown in FIGS. 6 and 7 even when the rotation speed of the motor 7 increases, the counter electromotive force exceeds the lower limit voltage V L, as in the current limits c and d shown in FIG. , The current I EA hardly flows. Therefore, the relationship between the rotation speed of the motor 7 and the EA load (the inclination characteristic of the EA load with respect to the rotation speed of the motor 7) can be adjusted to a gentle characteristic. Further, according to the current control circuit 41D shown in FIG. 7, the lower limit voltage V L can be adjusted to a desired voltage value according to the adjustment signal S L.
  • FIG. 9 is a diagram showing a fifth configuration example of the current control circuit 41.
  • the current control circuit 41E shown in FIG. 9 is a circuit in which the current control circuit 41A shown in FIG. 3 and the current control circuit 41C shown in FIG. 6 are combined, and the upper limit current limiting function and the current control circuit 41C of the current control circuit 41A are included. Has a lower limit voltage limiting function. Therefore, the current control circuit 41E detects the magnitude of the current I EA flowing in the bypass 45 by using the resistor 53, the magnitude of the counter electromotive force of the motor 7 by using the resistors 71 and 72, and The magnitude of the current I EA flowing through the bypass 45 is controlled based on the detection result.
  • FIG. 10 is a diagram showing a sixth configuration example of the current control circuit 41.
  • the current control circuit 41F shown in FIG. 10 is a circuit in which the current control circuit 41B shown in FIG. 4 and the current control circuit 41D shown in FIG. 7 are combined, and the upper limit current adjustment function and the current control circuit 41D of the current control circuit 41B are included. Has a lower limit voltage adjusting function. Therefore, the current control circuit 41F detects the magnitude of the current I EA flowing in the bypass 45 by using the resistor 65 and the magnitude of the counter electromotive force of the motor 7 by using the resistors 84 and 85, and detects those magnitudes. The magnitude of the current I EA flowing through the bypass 45 is controlled based on the detection result. Then, the current control circuit 41F adjusts the upper limit current I U according to the adjustment signal S U , and adjusts the lower limit voltage V L according to the adjustment signal S L.
  • FIG. 11 shows the rotation speed of the motor 7 when the seat belt 2 is pulled out and the current flowing in the bypass 45 due to the counter electromotive force of the motor 7 when the current control circuits 41E and 41F shown in FIGS.
  • It is a figure which shows an example of the relationship of. 9 and 10 shows a current control circuit 41E, according to 41F, as current limiting e, f shown in FIG. 11, since not flow a large current I EA than a predetermined upper limit current I U, the upper limit current I U
  • the EA load can be limited below the corresponding upper limit load F U. Further, according to the current control circuits 41E and 41F shown in FIGS.
  • the relationship between the rotation speed of the motor 7 and the EA load (the inclination characteristic of the EA load with respect to the rotation speed of the motor 7) can be adjusted to a gentle characteristic.
  • the upper limit current I U can be adjusted to a desired current value according to the adjustment signal S U
  • the lower limit voltage V L can be adjusted to a desired voltage value according to the adjustment signal S L. Can be adjusted to.
  • FIG. 12 is a diagram showing a second configuration example of the drive circuit 14. The description of the same points as the first configuration example will be omitted.
  • the drive circuit 14B shown in FIG. 12 is a low-side drive circuit that has a low-side switching element 25 and can supply a drive current to the motor 7 in only one direction.
  • the drive circuit 14B is used, for example, when it is not necessary to rotate the motor 7 in the reverse rotation direction corresponding to the withdrawal direction of the seat belt 2, and rotates the motor 7 in the normal rotation direction corresponding to the winding direction of the seat belt 2.
  • the drive current to be supplied can be supplied to the motor 7.
  • the drive circuit 14B is connected between the power supply VB and the ground (GND), and includes a low-side switching element 25 connected to the ground side with respect to the motor 7.
  • the switching element 25 includes an electrode (drain or collector) connected to the first terminal 7a, an electrode (source or emitter) connected to the ground side, and an electrode (gate or base) connected to the control circuit 15. It is a low side arm having.
  • the second terminal 7b is connected to the power supply VB.
  • the diode 35 may be a body diode of the switching element 25 or a rectifying element additionally connected in parallel with the switching element 25.
  • the control circuit 15 drives the motor 7 to rotate (forward rotation) in the forward rotation direction corresponding to the winding direction of the seat belt 2. It controls the switching element 25 of the circuit 14B. For example, the control circuit 15 turns on / off (switches) the switching element 25 by PWM control with a predetermined duty ratio in the winding mode in which the motor 7 rotates forward.
  • the drive circuit 14B can rotate the motor 7 (normal rotation) in the direction in which the spool 8 is rotated in the winding direction of the seat belt 2 (normal rotation direction). it can.
  • the rotation shaft of the motor 7 rotates in the forward direction
  • the drive force of the forward rotation is transmitted to the spool 8 by the power transmission mechanism 17.
  • the spool 8 rotates in the direction in which the seat belt 2 is wound, so that the seat belt 2 is wound around the spool 8.
  • the drive circuit 14B includes a current adjustment circuit 44 connected in parallel with the switching element 25.
  • the potential of the first terminal 7a becomes relatively higher than the potential of the second terminal 7b due to the generation of the counter electromotive force (in other words, the potential of the second terminal 7b becomes the first potential). It becomes relatively lower than the potential of the terminal 7a).
  • the control circuit 15 when the control circuit 15 receives the command signal indicating that the collision of the vehicle 13 is detected, the control circuit 15 rotates the motor 7 in the forward rotation direction in which the spool 8 is rotated in the winding direction of the seat belt 2, and then, The bypass 45 is switched from the disconnected state to the connected state.
  • the bypass 45 is a current path that is connected in parallel to both ends of the switching element 25 and causes the current I EA generated by the back electromotive force of the motor 7 to flow back to the motor 7.
  • the bypass 45 is a part of a return path for returning the current I EA to the motor 7.
  • the current I EA generated by the counter electromotive force flows back in the normal path of the first terminal 7a, the bypass circuit 45, the ground GND, the power supply VB, and the second terminal 7b. At this time, the current I EA is limited by the current control circuit 41 so as not to exceed the upper limit current I U.
  • control circuit 15 causes the current I EA generated by the back electromotive force to flow back to the motor 7 via the bypass 45, so that the motor 7 rotates in the reverse direction in which the spool 8 is rotated in the pulling direction of the seat belt 2. Can be suppressed. As a result, it becomes possible to absorb the collision energy that acts on the occupant 9 during a vehicle collision. Further, the current control circuit 41 controls the magnitude of the current I EA , so that the EA load can be adjusted with high accuracy.
  • FIG. 13 is a diagram showing a third configuration example of the drive circuit 14. The description of the same points as those of the above configuration example will be omitted.
  • the drive circuit 14C shown in FIG. 13 is an H-bridge drive circuit that has four switching elements 21, 22, 23, and 24 and is capable of switching the direction of the drive current supplied to the motor 7.
  • the drive circuit 14C has a configuration in which the current control circuit 41G is integrated with the switching element 22.
  • the current control circuit 41G is an example of the current control circuit 41 described above.
  • the current control circuit 41G controls the magnitude of the current I EA flowing through the return path 46 by repeating switching (on / off) of the switching element 22 in accordance with the control signal A supplied from the control circuit 15.
  • the return path 46 is a current path that is connected to the switching element 22 and causes the current I EA generated by the counter electromotive force of the motor 7 to return to the motor 7.
  • the current control circuit 41G controls the magnitude of the current I EA , whereby the EA load can be adjusted with high accuracy.
  • control circuit 15 when the control circuit 15 receives a command signal indicating that a collision of the vehicle 13 has been detected, the control circuit 15 controls the magnitude of the current I EA flowing through the return path 46 (for example, a PWM control signal). Is output.
  • the current control circuit 41G may have the above-described configuration that controls the magnitude of the current I EA by using at least one of the upper limit current I U and the lower limit voltage V L. Further, the current control circuit 41G may have the above-described configuration that adjusts at least one of the upper limit current I U and the lower limit voltage V L according to the adjustment signal supplied from the outside.
  • FIG. 14 is a diagram showing a configuration example of the current control circuit 41G.
  • the current control circuit 41G is connected in series between the first node 42 and the second node 43 on the return path 46.
  • the current control circuit 41G is a current limiting circuit that limits the magnitude of the current I EA flowing in the return path 46 so as not to exceed a predetermined upper limit current I U.
  • the current control circuit 41G also has a configuration of adjusting the upper limit current I U according to an adjustment signal S U supplied from the outside.
  • the current control circuit 41G includes resistors 61 to 65, a low side switching element 22, a Zener diode 67, and a comparator 68.
  • the current control circuit 41G repeats switching (ON / OFF) of the switching element 22 according to the control signal A supplied from the control circuit 15 when the collision of the vehicle 13 is detected.
  • the current I EA flows through the return path 46 while the flow of the switching element 22 is limited by the current control circuit 41G being repeated, so that the magnitude of the current I EA flowing through the return path 46 can be controlled. ..
  • the control signal A is supplied to the gate of the switching element 22 via the resistor 63.
  • the switching element 22 is repeatedly turned on and off by the control signal A, so that the current I EA flows from the drain to the source of the switching element 22.
  • the resistor 65 is connected to the source of the switching element 22 so as to be inserted in the return path 46 in series. When the current I EA rises, the voltage across the resistor 65 rises.
  • the comparator 68 sinks current from its output terminal.
  • the gate voltage of the switching element 22 drops.
  • the current I EA is limited so as not to exceed the upper limit current I U.
  • the control circuit 15 turns on / off the switching element 23 by PWM control with a predetermined duty ratio in the winding mode in which the motor 7 rotates in the forward direction, constantly turns off the switching elements 21 and 24, and performs switching.
  • the element 22 may be always turned on.
  • the control circuit 15 may turn on the switching element 24 when the switching element 23 is turned off in order to suppress heat generation due to the return current when the switching element 23 is turned off.
  • the bypass 45 in which the current adjusting circuit 44 is inserted in series is connected in parallel to the switching element 23.
  • Control Device 2 Seat Belt 6 Seat Belt Winding Mechanism 7 Motor 8 Spool 10 Seat Belt Retractor 14, 14A, 14B, 14C Drive Circuit 15 Control Circuit 17 Power Transmission Mechanism 21-25 Switching Element 40 Changeover Switch 41, 41A-41G Current Control circuit 44 Current adjusting circuit 45 Detour 46 Return path 100 Seat belt device

Abstract

Provided are a seat belt retractor and a seat belt device. The present invention comprises: a spool; a motor for rotating the spool; a switching element connected to the motor; a control circuit that switches the switching element via PWM control such that the motor rotates in a direction in which a seat belt is wound around the spool; a recirculation path for recirculating, to the motor, a current produced by counter electromotive force of the motor; and a current control circuit for controlling the magnitude of the current flowing to the recirculation path.

Description

シートベルトリトラクタ及びシートベルト装置Seat belt retractor and seat belt device
　本発明は、シートベルトリトラクタ及びシートベルト装置に関する。 The present invention relates to a seat belt retractor and a seat belt device.
　シートベルトを巻き取るスプールに加えられる外力によってモータに逆起電力が発生したとき、ＦＥＴがオンすることにより、電流をＦＥＴを介してモータに還流させるモータ駆動回路が知られている（例えば、特許文献１参照）。 A motor drive circuit is known in which, when a counter electromotive force is generated in a motor by an external force applied to a spool that winds up a seat belt, the FET is turned on to cause a current to flow back to the motor through the FET (for example, a patent). Reference 1).
特開２０１１－１１１０３５号公報JP, 2011-111035, A
　しかしながら、従来の技術では、ＦＥＴがオンした後にモータに還流する電流の大きさは、成り行きに任せて自ずと決まってしまうので、エネルギー吸収荷重（シートベルトに作用する荷重）を精度良く調整することが難しい。以下、エネルギー吸収荷重を“ＥＡ荷重”とも称する。 However, in the conventional technique, the magnitude of the current flowing back to the motor after the FET is turned on is automatically determined by the event, so that the energy absorption load (the load acting on the seat belt) can be adjusted accurately. difficult. Hereinafter, the energy absorption load is also referred to as “EA load”.
　そこで、本開示は、ＥＡ荷重を精度良く調整できるシートベルトリトラクタ及びシートベルト装置を提供する。 Therefore, the present disclosure provides a seatbelt retractor and a seatbelt device capable of accurately adjusting the EA load.
　本開示は、
　スプールと、
　前記スプールを回転させるモータと、
　前記モータに接続されるスイッチング素子と、
　シートベルトを前記スプールに巻き取らせる方向に前記モータが回転するように前記スイッチング素子をＰＷＭ制御でスイッチングさせる制御回路と、
　前記スイッチング素子に接続され、前記モータの逆起電力によって生ずる電流を前記モータに還流させる還流路と、
　前記還流路に流れる前記電流の大きさを制御する電流制御回路とを備える、シートベルトリトラクタ及びシートベルト装置を提供する。 This disclosure is
Spool,
A motor for rotating the spool,
A switching element connected to the motor,
A control circuit for switching the switching element by PWM control so that the motor rotates in a direction in which the seat belt is wound around the spool;
A return path that is connected to the switching element and returns a current generated by a back electromotive force of the motor to the motor;
There is provided a seatbelt retractor and a seatbelt device, comprising: a current control circuit that controls the magnitude of the current flowing through the return path.
　本開示の技術によれば、ＥＡ荷重を精度良く調整できるシートベルトリトラクタ及びシートベルト装置を提供できる。 According to the technology of the present disclosure, it is possible to provide a seatbelt retractor and a seatbelt device capable of accurately adjusting the EA load.
シートベルト装置及びシートベルトリトラクタの構成の一例を示す図である。It is a figure showing an example of composition of a seat belt device and a seat belt retractor. シートベルトリトラクタに備えられる駆動回路の第１の構成例を示す図である。It is a figure which shows the 1st structural example of the drive circuit with which a seatbelt retractor is equipped. 電流制御回路の第１の構成例を示す図である。It is a figure which shows the 1st structural example of a current control circuit. 電流制御回路の第２の構成例を示す図である。It is a figure which shows the 2nd structural example of a current control circuit. 図３，４に示す電流制御回路を使用した場合に、シートベルトが引き出される時のモータの回転速度とそのモータの逆起電力によって迂回路に流れる電流との関係の一例を示す図である。FIG. 6 is a diagram showing an example of a relationship between a rotation speed of a motor when a seat belt is pulled out and a current flowing through a bypass due to a back electromotive force of the motor when the current control circuit shown in FIGS. 3 and 4 is used. 電流制御回路の第３の構成例を示す図である。It is a figure which shows the 3rd structural example of a current control circuit. 電流制御回路の第４の構成例を示す図である。It is a figure which shows the 4th example of a structure of a current control circuit. 図６，７に示す電流制御回路を使用した場合に、シートベルトが引き出される時のモータの回転速度とそのモータの逆起電力によって迂回路に流れる電流との関係の一例を示す図である。FIG. 8 is a diagram showing an example of a relationship between a rotation speed of a motor when a seat belt is pulled out and a current flowing through a bypass due to a back electromotive force of the motor when the current control circuit shown in FIGS. 6 and 7 is used. 電流制御回路の第５の構成例を示す図である。It is a figure which shows the 5th example of a structure of a current control circuit. 電流制御回路の第６の構成例を示す図である。It is a figure which shows the 6th example of a structure of a current control circuit. 図９，１０に示す電流制御回路を使用した場合に、シートベルトが引き出される時のモータの回転速度とそのモータの逆起電力によって迂回路に流れる電流との関係の一例を示す図である。FIG. 11 is a diagram showing an example of the relationship between the rotational speed of the motor when the seat belt is pulled out and the current flowing in the bypass due to the back electromotive force of the motor when the current control circuit shown in FIGS. 9 and 10 is used. シートベルトリトラクタに備えられる駆動回路の第２の構成例を示す図である。It is a figure which shows the 2nd structural example of the drive circuit with which a seatbelt retractor is equipped. シートベルトリトラクタに備えられる駆動回路の第３の構成例を示す図である。It is a figure which shows the 3rd structural example of the drive circuit with which a seatbelt retractor is equipped. 電流制御回路の第７の構成例を示す図である。It is a figure which shows the 7th example of a structure of a current control circuit.
　以下、本開示に係る実施形態を図面を参照して説明する。 Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings.
　図１は、シートベルト装置１００の一例を模式的に示す構成図である。シートベルト装置１００は、自動車等の車両１３に搭載される。シートベルト装置１００は、例えば、シートベルト２と、ショルダーアンカー３と、タング４と、バックル５と、シートベルトリトラクタ（以下、単に「リトラクタ」とも称する）１０とを備える。リトラクタ１０は、シートベルト巻き取り機構（以下、単に「巻き取り機構」とも称する）６と、制御装置１とを備える。 FIG. 1 is a configuration diagram schematically showing an example of a seat belt device 100. The seat belt device 100 is mounted on a vehicle 13 such as an automobile. The seat belt device 100 includes, for example, a seat belt 2, a shoulder anchor 3, a tongue 4, a buckle 5, and a seat belt retractor (hereinafter, also simply referred to as “retractor”) 10. The retractor 10 includes a seat belt retracting mechanism (hereinafter, also simply referred to as “retracting mechanism”) 6 and a control device 1.
　シートベルト２は、車両１３のシート１１に座る乗員９を拘束する帯状部材の一例であり、巻き取り機構６から引き出し可能に巻き取り機構６に巻き取られる。シートベルト２の一方の端部は、巻き取り機構６に接続され、シートベルト２のもう一方の端部は、車体、プリテンショナ装置又はシート１１などに固定される。シートベルトは、ウェビングとも称される。 The seat belt 2 is an example of a belt-shaped member that restrains the occupant 9 sitting on the seat 11 of the vehicle 13, and is wound around the winding mechanism 6 so as to be pulled out from the winding mechanism 6. One end of the seat belt 2 is connected to the winding mechanism 6, and the other end of the seat belt 2 is fixed to the vehicle body, the pretensioner device, the seat 11, or the like. The seat belt is also called webbing.
　ショルダーアンカー３は、巻き取り機構６から引き出されたシートベルト２を乗員９の肩部の方へガイドするガイド部材であり、例えば、車室の側壁又はシート１１に固定される。 The shoulder anchor 3 is a guide member that guides the seat belt 2 pulled out from the winding mechanism 6 toward the shoulder of the occupant 9, and is fixed to, for example, the side wall of the passenger compartment or the seat 11.
　タング４は、ショルダーアンカー３によりガイドされたシートベルト２にスライド可能に取り付けられる部材である。 The tongue 4 is a member slidably attached to the seat belt 2 guided by the shoulder anchor 3.
　バックル５は、タング４が着脱可能に係合される部材の一例であり、例えば、車体の床又はシート１１に固定される。 The buckle 5 is an example of a member to which the tongue 4 is detachably engaged, and is fixed to, for example, the floor of the vehicle body or the seat 11.
　リトラクタ１０は、例えば、シート１１の近傍の車体又はシート１１自体に固定される。リトラクタ１０は、シートベルト２の巻き取り又は引き出しを可能にする巻き取り機構６と、巻き取り機構６の動作を制御する制御装置１とを備える。 The retractor 10 is fixed to, for example, the vehicle body near the seat 11 or the seat 11 itself. The retractor 10 includes a winding mechanism 6 that allows the seat belt 2 to be wound or pulled out, and a control device 1 that controls the operation of the winding mechanism 6.
　巻き取り機構６は、シートベルト２を巻き取るためのスプール８と、スプール８を回転させるモータ７と、モータ７とスプール８との間で動力を伝達する動力伝達機構１７とを備える。スプール８には、シートベルト２の一端が固定される。モータ７は、スプール８を回転させる駆動力を発生する。モータ７の回転軸は、動力伝達機構１７を介して、スプール８の回転軸と連結する。 The winding mechanism 6 includes a spool 8 for winding the seat belt 2, a motor 7 for rotating the spool 8, and a power transmission mechanism 17 for transmitting power between the motor 7 and the spool 8. One end of the seat belt 2 is fixed to the spool 8. The motor 7 generates a driving force that rotates the spool 8. The rotation shaft of the motor 7 is connected to the rotation shaft of the spool 8 via the power transmission mechanism 17.
　制御装置１は、モータ７を駆動することによって、巻き取り機構６によるシートベルト２の巻き取り動作（又は、巻き取り動作と引き出し動作の両方）を制御する。制御装置１は、モータ７を駆動する駆動回路１４と、駆動回路１４の駆動動作を制御する制御回路１５とを備える。 The control device 1 controls the winding operation (or both the winding operation and the withdrawing operation) of the seat belt 2 by the winding mechanism 6 by driving the motor 7. The control device 1 includes a drive circuit 14 that drives the motor 7, and a control circuit 15 that controls the drive operation of the drive circuit 14.
　駆動回路１４は、制御回路１５から供給される少なくとも一つの制御信号（例えば、ＰＷＭ（パルス幅変調）の制御信号）に従って、モータ７を駆動する駆動電流をモータ７に流す。駆動回路１４の具体例として、４つのスイッチング素子によってモータ７を駆動するＨブリッジ駆動回路、ハイサイドとローサイドの２つのスイッチング素子によってモータ７を駆動するハーフブリッジ駆動回路などが挙げられる。あるいは、駆動回路１４は、ハイサイドのスイッチング素子によってモータ７を駆動するハイサイド駆動回路でもよいし、ローサイドのスイッチング素子によってモータ７を駆動するローサイド駆動回路でもよい。駆動回路１４の形態は、これらに限られず、要求される仕様に応じて、決められる。 The drive circuit 14 supplies a drive current for driving the motor 7 to the motor 7 according to at least one control signal (for example, a PWM (pulse width modulation) control signal) supplied from the control circuit 15. Specific examples of the drive circuit 14 include an H-bridge drive circuit that drives the motor 7 with four switching elements, and a half-bridge drive circuit that drives the motor 7 with two switching elements on the high side and the low side. Alternatively, the drive circuit 14 may be a high-side drive circuit that drives the motor 7 with a high-side switching element, or a low-side drive circuit that drives the motor 7 with a low-side switching element. The form of the drive circuit 14 is not limited to these, but is determined according to the required specifications.
　制御回路１５は、モータ７を駆動する駆動電流の大きさ（又は、駆動電流の大きさと向き）を制御する少なくとも一つの制御信号（例えば、ＰＷＭの制御信号）を、駆動回路１４に対して出力する。制御回路１５の各機能は、メモリに記憶されたプログラムに従ってＣＰＵ（Central Processing Unit）が動作することにより実現される。制御回路１５の具体例として、ＣＰＵとメモリとを備えるマイクロコンピュータなどが挙げられる。 The control circuit 15 outputs to the drive circuit 14 at least one control signal (for example, a PWM control signal) that controls the magnitude of the drive current (or the magnitude and direction of the drive current) that drives the motor 7. To do. Each function of the control circuit 15 is realized by operating a CPU (Central Processing Unit) according to a program stored in the memory. A specific example of the control circuit 15 is a microcomputer including a CPU and a memory.
　図２は、駆動回路１４の第１の構成例を示す図である。図２に示される駆動回路１４Ａは、４つのスイッチング素子２１，２２，２３，２４を有し、モータ７に流す駆動電流の方向を切り替え可能なＨブリッジ駆動回路である。モータ７は、第１の端子７ａと第２の端子７ｂとの間に接続されるコイルを内蔵する。 FIG. 2 is a diagram showing a first configuration example of the drive circuit 14. The drive circuit 14A shown in FIG. 2 is an H-bridge drive circuit that has four switching elements 21, 22, 23, and 24 and is capable of switching the direction of the drive current supplied to the motor 7. The motor 7 contains a coil connected between the first terminal 7a and the second terminal 7b.
　駆動回路１４Ａは、モータ７の第１の端子７ａに接続される第１の接続点１８と、モータ７の第２の端子７ｂに接続される第２の接続点１２とを有し、モータ７に第１の接続点１８及び第２の接続点１２を介して駆動電流を流す。第１の接続点１８は、スイッチング素子２１とスイッチング素子２２とが接続される中間ノードであり、第２の接続点１２は、スイッチング素子２３とスイッチング素子２４とが接続される中間ノードである。 The drive circuit 14A has a first connection point 18 connected to the first terminal 7a of the motor 7 and a second connection point 12 connected to the second terminal 7b of the motor 7, Drive current is passed through the first connection point 18 and the second connection point 12. The first connection point 18 is an intermediate node where the switching element 21 and the switching element 22 are connected, and the second connection point 12 is an intermediate node where the switching element 23 and the switching element 24 are connected.
　駆動回路１４Ａは、電源ＶＢとグランド（ＧＮＤ）との間に接続されており、モータ７に対して電源ＶＢ側に接続されるハイサイドのスイッチング素子２１，２３と、モータ７に対してグランド側に接続されるローサイドのスイッチング素子２２，２４とを備える。スイッチング素子２１，２２，２３，２４は、オン／オフ動作する半導体素子であり、電圧制御型のトランジスタでも、電流制御型のバイポーラトランジスタでもよい。電圧制御型のトランジスタには、ＩＧＢＴ（Insulated Gate Bipolar Transistor）やＭＯＳＦＥＴ（Metal Oxide Semiconductor Field Effect Transistor）などがある。図２には、スイッチング素子２１，２２，２３，２４がＮチャネル型のＭＯＳＦＥＴである形態が例示されている。 The drive circuit 14A is connected between the power supply VB and the ground (GND), and the high- side switching elements 21 and 23 connected to the power supply VB side with respect to the motor 7 and the ground side with respect to the motor 7. And low side switching elements 22 and 24 connected to. The switching elements 21, 22, 23, and 24 are semiconductor elements that perform on / off operations, and may be voltage-controlled transistors or current-controlled bipolar transistors. Voltage-controlled transistors include IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). FIG. 2 illustrates a mode in which the switching elements 21, 22, 23 and 24 are N-channel type MOSFETs.
　スイッチング素子２１は、第１の端子７ａに接続される第１のハイサイドスイッチング素子の一例である。スイッチング素子２１は、電源ＶＢ側に接続される電極（ドレイン又はコレクタ）と、第１の端子７ａに第１の接続点１８を介して接続される電極（ソース又はエミッタ）と、制御回路１５に接続される電極（ゲート又はベース）とを有するハイサイドアームである。 The switching element 21 is an example of a first high side switching element connected to the first terminal 7a. The switching element 21 includes an electrode (drain or collector) connected to the power supply VB side, an electrode (source or emitter) connected to the first terminal 7a via the first connection point 18, and a control circuit 15. It is a high side arm having an electrode (gate or base) connected thereto.
　スイッチング素子２２は、第１の端子７ａに接続される第１のローサイドスイッチング素子の一例である。スイッチング素子２２は、グランド側に接続される電極（ソース又はエミッタ）と、第１の端子７ａに第１の接続点１８を介して接続される電極（ドレイン又はコレクタ）と、制御回路１５に接続される電極（ゲート又はベース）とを有するローサイドアームである。 The switching element 22 is an example of a first low-side switching element connected to the first terminal 7a. The switching element 22 is connected to the electrode (source or emitter) connected to the ground side, the electrode (drain or collector) connected to the first terminal 7 a via the first connection point 18, and the control circuit 15. And a low side arm having an electrode (gate or base) to be driven.
　スイッチング素子２３は、第２の端子７ｂに接続される第２のハイサイドスイッチング素子の一例である。スイッチング素子２３は、電源ＶＢ側に接続される電極（ドレイン又はコレクタ）と、第２の端子７ｂに第２の接続点１２を介して接続される電極（ソース又はエミッタ）と、制御回路１５に接続される電極（ゲート又はベース）とを有するハイサイドアームである。 The switching element 23 is an example of a second high side switching element connected to the second terminal 7b. The switching element 23 includes an electrode (drain or collector) connected to the power supply VB side, an electrode (source or emitter) connected to the second terminal 7b through the second connection point 12, and a control circuit 15. It is a high side arm having an electrode (gate or base) connected thereto.
　スイッチング素子２４は、第２の端子７ｂに接続される第２のローサイドスイッチング素子の一例である。スイッチング素子２４は、グランド側に接続される電極（ソース又はエミッタ）と、第２の端子７ｂに第２の接続点１２を介して接続される電極（ドレイン又はコレクタ）と、制御回路１５に接続される電極（ゲート又はソース）とを有するローサイドアームである。 The switching element 24 is an example of a second low side switching element connected to the second terminal 7b. The switching element 24 is connected to the electrode (source or emitter) connected to the ground side, the electrode (drain or collector) connected to the second terminal 7b through the second connection point 12, and the control circuit 15. A low side arm having an electrode (gate or source) to be formed.
　ダイオード３１，３２，３３，３４は、それぞれに対応するスイッチング素子２１，２２，２３，２４のボディダイオードでもよいし、それぞれに対応するスイッチング素子２１，２２，２３，２４に並列に追加接続された整流素子でもよい。 The diodes 31, 32, 33, 34 may be body diodes of the corresponding switching elements 21, 22, 23, 24, or are additionally connected in parallel to the corresponding switching elements 21, 22, 23, 24. A rectifying element may be used.
　電流測定回路１６は、駆動回路１４Ａに流れる電流を測定し、その測定結果を制御回路１５に対して出力する電流測定部である。電流測定回路１６は、例えば、駆動回路１４Ａのローサイドのスイッチング素子２２，２４とグランドとの間の電流経路に直列に挿入された抵抗によって、駆動回路１４Ａに流れる電流の大きさを測定する。スイッチング素子２２，２４とグランドとの間の電流経路には、スイッチング素子２２，２４のグランド側に接続される電極（ソース又はエミッタ）同士を結ぶ電流経路（具体的には、モータ７に還流する後述の電流ＩＥＡが通る経路）の意味が含まれている。 The current measuring circuit 16 is a current measuring unit that measures the current flowing through the drive circuit 14A and outputs the measurement result to the control circuit 15. The current measuring circuit 16 measures the magnitude of the current flowing through the drive circuit 14A by, for example, a resistor inserted in series in the current path between the low- side switching elements 22 and 24 of the drive circuit 14A and the ground. The current path between the switching elements 22 and 24 and the ground is a current path that connects electrodes (sources or emitters) connected to the ground side of the switching elements 22 and 24 (specifically, returns to the motor 7). The meaning of a path through which a current I EA described later passes) is included.
　なお、電流測定回路１６は、例えば、駆動回路１４Ａのハイサイドのスイッチング素子２１，２３と電源ＶＢとの間の電流経路に直列に挿入された抵抗によって、駆動回路１４Ａに流れる電流の大きさを測定してもよい。電流測定方式は、これらに限られない。 The current measuring circuit 16 determines the magnitude of the current flowing through the drive circuit 14A by, for example, a resistor inserted in series in the current path between the high- side switching elements 21 and 23 of the drive circuit 14A and the power supply VB. You may measure. The current measurement method is not limited to these.
　制御回路１５は、電流測定回路１６による電流測定結果等を用いて、駆動回路１４Ａを構成する４つのスイッチング素子２１，２２，２３，２４を駆動する駆動制御部である。 The control circuit 15 is a drive control unit that drives the four switching elements 21, 22, 23, 24 forming the drive circuit 14A by using the current measurement result of the current measurement circuit 16 and the like.
　制御回路１５は、シートベルト２をスプール８に巻き取らせるモード（巻き取りモード）では、シートベルト２の巻き取り方向に対応する正転方向にモータ７が回転（正回転）するように、駆動回路１４Ａの各スイッチング素子を制御する。例えば、制御回路１５は、モータ７を正回転させる巻き取りモードでは、スイッチング素子２２を所定のデューティ比のＰＷＭ制御でオン／オフ（スイッチング）させ、スイッチング素子２１，２４を常時オフさせ、スイッチング素子２３を常時オンさせる。このとき、スイッチング素子２２のオフ時の還流電流による発熱を抑えるため、制御回路１５は、スイッチング素子２２のオフ時にスイッチング素子２１をオンさせてもよい。 In the mode in which the seat belt 2 is wound around the spool 8 (winding mode), the control circuit 15 drives the motor 7 to rotate (forward rotation) in the forward rotation direction corresponding to the winding direction of the seat belt 2. It controls each switching element of the circuit 14A. For example, in the winding mode in which the motor 7 rotates forward, the control circuit 15 turns on / off (switches) the switching element 22 by PWM control with a predetermined duty ratio, constantly turns off the switching elements 21 and 24, and switches the switching element. 23 is always turned on. At this time, the control circuit 15 may turn on the switching element 21 when the switching element 22 is off, in order to suppress heat generation due to the return current when the switching element 22 is off.
　各スイッチング素子がこのように制御されることにより、駆動回路１４Ａは、シートベルト２の巻き取り方向にスプール８を回転させる方向（正転方向）に、モータ７を回転（正回転）させることができる。モータ７の回転軸が正回転すると、その正回転の駆動力は、動力伝達機構１７によって、スプール８に伝達される。これにより、スプール８は、シートベルト２を巻き取る方向に回転するので、シートベルト２はスプール８に巻き取られる。 By controlling each switching element in this way, the drive circuit 14A can rotate the motor 7 (normal rotation) in the direction of rotating the spool 8 in the winding direction of the seat belt 2 (normal rotation direction). it can. When the rotation shaft of the motor 7 rotates in the forward direction, the drive force of the forward rotation is transmitted to the spool 8 by the power transmission mechanism 17. As a result, the spool 8 rotates in the direction in which the seat belt 2 is wound, so that the seat belt 2 is wound around the spool 8.
　一方、制御回路１５は、シートベルト２をスプール８から引き出させるモード（引き出しモード）では、シートベルト２の引き出し方向に対応する逆転方向にモータ７が回転（逆回転）するように、駆動回路１４Ａの各スイッチング素子を制御する。例えば、制御回路１５は、モータ７を逆回転させる引き出しモードでは、スイッチング素子２４を所定のデューティ比のＰＷＭ制御でオン／オフ（スイッチング）させ、スイッチング素子２２，２３を常時オフさせ、スイッチング素子２１を常時オンさせる。このとき、スイッチング素子２４のオフ時の還流電流による発熱を抑えるため、制御回路１５は、スイッチング素子２４のオフ時にスイッチング素子２３をオンさせてもよい。 On the other hand, in the mode in which the seat belt 2 is pulled out from the spool 8 (pull-out mode), the control circuit 15 drives the drive circuit 14A so that the motor 7 rotates in the reverse direction corresponding to the pull-out direction of the seat belt 2 (reverse rotation). To control each switching element. For example, in the pull-out mode in which the motor 7 is rotated in the reverse direction, the control circuit 15 turns on / off (switches) the switching element 24 by PWM control with a predetermined duty ratio to constantly turn off the switching elements 22 and 23, and the switching element 21. Is always on. At this time, the control circuit 15 may turn on the switching element 23 when the switching element 24 is off in order to suppress heat generation due to the return current when the switching element 24 is off.
　各スイッチング素子がこのように制御されることにより、駆動回路１４Ａは、シートベルト２の引き出し方向にスプール８を回転させる方向（逆転方向）に、モータ７を回転（逆回転）させることができる。モータ７の回転軸が逆回転すると、その逆回転の駆動力は、動力伝達機構１７によって、スプール８に伝達される。これにより、スプール８は、シートベルト２を引き出す方向に回転するので、シートベルト２はスプール８から引き出される。 By controlling each switching element in this way, the drive circuit 14A can rotate the motor 7 (reverse rotation) in the direction of rotating the spool 8 in the direction of withdrawing the seat belt 2 (reverse rotation). When the rotation shaft of the motor 7 rotates in the reverse direction, the driving force of the reverse rotation is transmitted to the spool 8 by the power transmission mechanism 17. As a result, the spool 8 rotates in the direction in which the seat belt 2 is pulled out, so that the seat belt 2 is pulled out from the spool 8.
　駆動回路１４Ａは、スイッチング素子２２に並列に接続される電流調整回路４４を備える。モータ７の回転軸とスプール８の回転軸とが動力伝達機構１７によって連結されている状態において、スプール８に加えられる外力によってモータ７が回されると、モータ７に逆起電力が発生する。電流調整回路４４は、この逆起電力によって生ずる電流ＩＥＡをモータ７に還流させることで、モータ７の回転を抑制しブレーキをかける。 The drive circuit 14A includes a current adjustment circuit 44 connected in parallel with the switching element 22. When the rotating shaft of the motor 7 and the rotating shaft of the spool 8 are connected by the power transmission mechanism 17, when the motor 7 is rotated by an external force applied to the spool 8, a counter electromotive force is generated in the motor 7. The current adjusting circuit 44 causes the current I EA generated by this back electromotive force to flow back to the motor 7, thereby suppressing the rotation of the motor 7 and applying the brake.
　電流調整回路４４がモータ７の回転を抑制することで、例えば、車両衝突時に乗員９に作用する衝突エネルギーを吸収することが可能となる。 By suppressing the rotation of the motor 7 by the current adjusting circuit 44, it becomes possible to absorb the collision energy that acts on the occupant 9 during a vehicle collision, for example.
　例えば、リトラクタ１０外部の車載コンピュータは、車両１３の衝突が検知又は予測された場合、シートベルト２の乗員９に対する拘束力制御を開始するための指令信号を送信する。 For example, when the collision of the vehicle 13 is detected or predicted, the vehicle-mounted computer outside the retractor 10 transmits a command signal for starting the restraint force control of the seat belt 2 on the occupant 9.
　制御回路１５は、タング４がバックル５に係合されシートベルト２が乗員９に装着された状態において、リトラクタ１０外部の車載コンピュータからの指令信号を受信する等の条件が成立すると、シートベルト２の乗員９に対する拘束力制御を開始する。 When the tongue 4 is engaged with the buckle 5 and the seat belt 2 is attached to the occupant 9, the control circuit 15 receives a command signal from an in-vehicle computer outside the retractor 10 and the like, and the seat belt 2 The restraint force control for the occupant 9 is started.
　制御回路１５は、当該条件が成立すると、衝突時の衝撃に準備するため、シートベルト２の巻き取り方向に対応する正転方向にモータ７が回転（正回転）するように、駆動回路１４Ａの各スイッチング素子を制御する。モータ７の回転軸が正回転すると、その正回転の駆動力は、動力伝達機構１７によって、スプール８に伝達される。これにより、スプール８は、シートベルト２を巻き取る方向に回転するので、シートベルト２はスプール８に巻き取られる。その結果、シートベルト２による乗員９に対する拘束力は上がる。 When the condition is satisfied, the control circuit 15 prepares for an impact at the time of a collision, so that the motor 7 rotates (normal rotation) in the normal rotation direction corresponding to the winding direction of the seat belt 2 so that the drive circuit 14A operates. Control each switching element. When the rotation shaft of the motor 7 rotates in the forward direction, the drive force of the forward rotation is transmitted to the spool 8 by the power transmission mechanism 17. As a result, the spool 8 rotates in the direction in which the seat belt 2 is wound, so that the seat belt 2 is wound around the spool 8. As a result, the restraint force on the occupant 9 by the seat belt 2 increases.
　その後、乗員９が衝突時の慣性により車両前方に移動すると、乗員９の車両前方への慣性力により、シートベルト２がスプール８から引き出される。シートベルト２がスプール８から引き出される方向にスプール８が回転すると、その回転力は、動力伝達機構１７によって、モータ７の回転軸に伝達される。これにより、モータ７の回転軸は、逆転方向に回されるので、モータ７に逆起電力が発生する。この逆起電力の発生によって、第１の端子７ａの電位が第２の端子７ｂの電位よりも相対的に高くなる（言い換えれば、第２の端子７ｂの電位が第１の端子７ａの電位よりも相対的に低くなる）。 After that, when the occupant 9 moves to the front of the vehicle due to the inertia at the time of the collision, the seat belt 2 is pulled out from the spool 8 by the inertial force of the occupant 9 toward the front of the vehicle. When the spool 8 rotates in the direction in which the seat belt 2 is pulled out from the spool 8, the rotational force is transmitted to the rotation shaft of the motor 7 by the power transmission mechanism 17. As a result, the rotating shaft of the motor 7 is rotated in the reverse direction, so that a counter electromotive force is generated in the motor 7. Due to the generation of this counter electromotive force, the potential of the first terminal 7a becomes relatively higher than the potential of the second terminal 7b (in other words, the potential of the second terminal 7b is higher than the potential of the first terminal 7a. Is also relatively low).
　そこで、制御回路１５は、車両１３の衝突が検知されたことを表す指令信号を受信した場合、シートベルト２の巻き取り方向にスプール８を回転させる正転方向にモータ７を回転させてから、迂回路４５を遮断状態から接続状態に切り替える。迂回路４５は、スイッチング素子２２の両端に並列に接続され、モータ７の逆起電力によって生ずる電流ＩＥＡをモータ７に還流させる電流経路である。迂回路４５は、電流ＩＥＡをモータ７に還流させる還流路の一部である。迂回路４５が遮断状態から接続状態に切り替わると、逆起電力によって生ずる電流ＩＥＡは、第１の端子７ａ、迂回路４５、ダイオード３４、第２の端子７ｂの順路で還流する。制御回路１５は、電流ＩＥＡをモータ７に還流させる場合、スイッチング素子２４をオンにすることによって、ダイオード３４ではなくスイッチング素子２４に電流ＩＥＡを流すようにしてもよい。 Therefore, when the control circuit 15 receives the command signal indicating that the collision of the vehicle 13 is detected, the control circuit 15 rotates the motor 7 in the forward rotation direction in which the spool 8 is rotated in the winding direction of the seat belt 2, and then, The bypass 45 is switched from the disconnected state to the connected state. The bypass 45 is a current path that is connected in parallel to both ends of the switching element 22 and causes the current I EA generated by the back electromotive force of the motor 7 to flow back to the motor 7. The bypass 45 is a part of a return path for returning the current I EA to the motor 7. When the bypass circuit 45 is switched from the cutoff state to the connection state, the current I EA generated by the counter electromotive force flows back in the normal path of the first terminal 7a, the bypass circuit 45, the diode 34, and the second terminal 7b. When the current I EA is returned to the motor 7, the control circuit 15 may turn on the switching element 24 so that the current I EA flows through the switching element 24 instead of the diode 34.
　このように、制御回路１５は、逆起電力によって生ずる電流ＩＥＡをモータ７に迂回路４５経由で還流させることで、シートベルト２の引き出し方向にスプール８を回転させる逆転方向にモータ７が回転することを抑制できる。その結果、車両衝突時に乗員９に作用する衝突エネルギーを吸収することが可能となる。 In this way, the control circuit 15 causes the current I EA generated by the back electromotive force to flow back to the motor 7 via the bypass 45, so that the motor 7 rotates in the reverse direction in which the spool 8 is rotated in the pulling direction of the seat belt 2. Can be suppressed. As a result, it becomes possible to absorb the collision energy that acts on the occupant 9 during a vehicle collision.
　制御回路１５は、例えば、車両１３の衝突が検知されたことを表す指令信号を受信した場合、迂回路４５に直列に挿入される切り替えスイッチ４０を作動させることによって、迂回路４５を遮断状態から接続状態に切り替える。切り替えスイッチ４０は、例えば、ＭＯＳＦＥＴ等のスイッチング素子である。 For example, when the control circuit 15 receives a command signal indicating that the collision of the vehicle 13 is detected, the control circuit 15 operates the changeover switch 40 that is inserted in series with the detour 45 to remove the detour 45 from the cutoff state. Switch to the connected state. The changeover switch 40 is, for example, a switching element such as a MOSFET.
　迂回路４５に直列に挿入される電流調整回路４４は、例えば、切り替えスイッチ４０と電流制御回路４１とが直列に接続される構成を有する。切り替えスイッチ４０及び電流制御回路４１は、迂回路４５に直列に挿入されている。切り替えスイッチ４０及び電流制御回路４１が迂回路４５に直列に挿入されている位置は、互いに置換されてもよい。 The current adjustment circuit 44 inserted in series in the bypass circuit 45 has, for example, a configuration in which the changeover switch 40 and the current control circuit 41 are connected in series. The changeover switch 40 and the current control circuit 41 are inserted in the detour 45 in series. The positions where the changeover switch 40 and the current control circuit 41 are inserted in series in the bypass 45 may be replaced with each other.
　電流制御回路４１は、迂回路４５に流れる電流ＩＥＡの大きさを制御する。電流ＩＥＡの大きさが変化すると、シートベルト２の引き出し方向にスプール８を回転させる逆転方向にモータ７が回転することを抑制する力が変化するので、ＥＡ荷重（シートベルト２に作用する荷重）も変化する。ＥＡ荷重は、電流ＩＥＡが大きくなるほど大きくなる。したがって、電流制御回路４１が電流ＩＥＡの大きさを制御することによって、ＥＡ荷重を精度良く調整できる。 The current control circuit 41 controls the magnitude of the current I EA flowing through the bypass 45. When the magnitude of the current I EA changes, the force that suppresses the rotation of the motor 7 in the reverse rotation direction that rotates the spool 8 in the pull-out direction of the seat belt 2 changes, so the EA load (the load acting on the seat belt 2 is changed. ) Also changes. The EA load increases as the current I EA increases. Therefore, the current control circuit 41 controls the magnitude of the current I EA , whereby the EA load can be adjusted with high accuracy.
　電流制御回路４１は、例えば、迂回路４５に流れる電流ＩＥＡの大きさが所定の上限値（以下、上限電流ＩＵとも称する）を超えないように制限する構成を有してもよい。このような構成によって、上限電流ＩＵに対応する上限荷重ＦＵ以下にＥＡ荷重を制限できるので、ＥＡ荷重が大きくなりすぎることを防止できる。 The current control circuit 41 may have a configuration in which the magnitude of the current I EA flowing through the detour 45 is limited so as not to exceed a predetermined upper limit value (hereinafter, also referred to as upper limit current I U ). With such a configuration, the EA load can be limited to the upper limit load F U or less corresponding to the upper limit current I U , so that the EA load can be prevented from becoming too large.
　また、電流制御回路４１は、外部から供給される調整信号に応じて上限電流ＩＵを調整する構成を有してもよい。上限電流ＩＵの調整によって、上限荷重ＦＵを調整できる。例えば、制御回路１５は、乗員９の体重等の体格情報に基づいて、上限電流ＩＵを調整する調整信号を電流制御回路４１に供給する。これにより、乗員９の体格に適した上限電流ＩＵ及び上限荷重ＦＵを設定できる。例えば、乗員９の体重が重くなるほど、上限電流ＩＵ及び上限荷重ＦＵが高く設定される。 Further, the current control circuit 41 may have a configuration for adjusting the upper limit current I U according to an adjustment signal supplied from the outside. The upper limit load F U can be adjusted by adjusting the upper limit current I U. For example, the control circuit 15 supplies the current control circuit 41 with an adjustment signal for adjusting the upper limit current I U based on the physique information such as the weight of the occupant 9. Accordingly, the upper limit current I U and the upper limit load F U suitable for the physique of the occupant 9 can be set. For example, as the weight of the occupant 9 becomes heavier, the upper limit current I U and the upper limit load F U are set higher.
　図３は、電流制御回路４１の第１の構成例を示す図である。図３に示す電流制御回路４１Ａは、迂回路４５上の第１のノード４２と第２のノード４３との間に直列に接続される。電流制御回路４１Ａは、迂回路４５に流れる電流ＩＥＡの大きさが所定の上限電流ＩＵを超えないように制限する電流制限回路である。電流制御回路４１Ａは、抵抗５１，５２，５３、ｎｐｎ型のバイポーラトランジスタ５４，５５及びツェナーダイオード５６，５７を有する。 FIG. 3 is a diagram showing a first configuration example of the current control circuit 41. The current control circuit 41A shown in FIG. 3 is connected in series between the first node 42 and the second node 43 on the bypass 45. The current control circuit 41A is a current limiting circuit that limits the magnitude of the current I EA flowing in the bypass 45 so as not to exceed a predetermined upper limit current I U. The current control circuit 41A has resistors 51, 52, 53, npn-type bipolar transistors 54, 55, and zener diodes 56, 57.
　迂回路４５が遮断状態から接続状態に切り替わると、電源ＶＢから抵抗５１経由でバイポーラトランジスタ５４のベースに流れるベース電流によって、電流ＩＥＡがバイポーラトランジスタ５４のコレクタからエミッタに流れる。抵抗５３は、迂回路４５に直列に挿入されるように、バイポーラトランジスタ５４のエミッタに接続されている。 When the detour 45 is switched from the cutoff state to the connection state, the base current flowing from the power supply VB to the base of the bipolar transistor 54 via the resistor 51 causes the current I EA to flow from the collector of the bipolar transistor 54 to the emitter. The resistor 53 is connected to the emitter of the bipolar transistor 54 so as to be inserted in the detour 45 in series.
　電流ＩＥＡが上昇して、バイポーラトランジスタ５５のベース‐エミッタ間の電圧が約０．６ボルトよりも大きくなると、バイポーラトランジスタ５５のコレクタ電流が流れる。バイポーラトランジスタ５５のコレクタ電流が流れると、電源ＶＢから抵抗５１経由でバイポーラトランジスタ５４のベースに流れるベース電流が減少する。その結果、電流ＩＥＡは上限電流ＩＵを超えないように制限される。 When the current I EA rises and the base-emitter voltage of the bipolar transistor 55 becomes larger than about 0.6 volt, the collector current of the bipolar transistor 55 flows. When the collector current of the bipolar transistor 55 flows, the base current flowing from the power supply VB to the base of the bipolar transistor 54 via the resistor 51 decreases. As a result, the current I EA is limited so as not to exceed the upper limit current I U.
　上限電流ＩＵは、「（Ｒ５３／（Ｒ５２＋Ｒ５３））×ＶＢＥ５５」によって設定される。Ｒ５２，Ｒ５３は、それぞれ、抵抗５２，５３の抵抗値を表す。ＶＢＥ５５は、バイポーラトランジスタ５５のベース‐エミッタ間の電圧を表し、約０．６ボルトを上限とする。 The upper limit current I U is set by “(R53 / (R52 + R53)) × V BE55 ”. R52 and R53 represent resistance values of the resistors 52 and 53, respectively. V BE55 represents the base-emitter voltage of the bipolar transistor 55, with an upper limit of approximately 0.6 volts.
　このように、電流制御回路４１Ａは、迂回路４５に流れる電流ＩＥＡの大きさを抵抗５３を用いて検知し、その検知結果に基づいて、迂回路４５に流れる電流ＩＥＡの大きさを制御する。電流制御回路４１Ａは、その検知結果をフィードバックすることによって、迂回路４５に流れる電流ＩＥＡの大きさが上限電流ＩＵを超えないように制限する。 In this way, the current control circuit 41A detects the magnitude of the current I EA flowing through the bypass 45 by using the resistor 53, and controls the magnitude of the current I EA flowing through the bypass 45 based on the detection result. To do. By feeding back the detection result, the current control circuit 41A limits the magnitude of the current I EA flowing through the bypass 45 so as not to exceed the upper limit current I U.
　なお、ツェナーダイオード５６は、バイポーラトランジスタ５４のベース‐エミッタ間を過電圧から保護する素子である。ツェナーダイオード５７は、バイポーラトランジスタ５５のベース‐エミッタ間を過電圧から保護する素子である。 The Zener diode 56 is an element that protects the base-emitter of the bipolar transistor 54 from overvoltage. The Zener diode 57 is an element that protects the base-emitter of the bipolar transistor 55 from overvoltage.
　図４は、電流制御回路４１の第２の構成例を示す図である。図４に示す電流制御回路４１Ｂは、迂回路４５上の第１のノード４２と第２のノード４３との間に直列に接続される。電流制御回路４１Ｂは、迂回路４５に流れる電流ＩＥＡの大きさが所定の上限電流ＩＵを超えないように制限する電流制限回路である。電流制御回路４１Ｂは、外部から供給される調整信号ＳＵに応じて上限電流ＩＵを調整する構成も有する。電流制御回路４１Ｂは、抵抗６１～６５、ｎｐｎ型のバイポーラトランジスタ６６、ツェナーダイオード６７及びコンパレータ６８を有する。 FIG. 4 is a diagram showing a second configuration example of the current control circuit 41. The current control circuit 41B shown in FIG. 4 is connected in series between the first node 42 and the second node 43 on the bypass 45. The current control circuit 41B is a current limiting circuit that limits the magnitude of the current I EA flowing through the bypass 45 so as not to exceed a predetermined upper limit current I U. The current control circuit 41B also has a configuration of adjusting the upper limit current I U according to an adjustment signal S U supplied from the outside. The current control circuit 41B includes resistors 61 to 65, an npn-type bipolar transistor 66, a Zener diode 67, and a comparator 68.
　迂回路４５が遮断状態から接続状態に切り替わると、電源ＶＢから抵抗６３経由でバイポーラトランジスタ６６のベースに流れるベース電流によって、電流ＩＥＡがバイポーラトランジスタ６６のコレクタからエミッタに流れる。抵抗６５は、迂回路４５に直列に挿入されるように、バイポーラトランジスタ６６のエミッタに接続されている。 When the bypass circuit 45 is switched from the cut-off state to the connection state, the base current flowing from the power supply VB to the base of the bipolar transistor 66 via the resistor 63 causes the current I EA to flow from the collector of the bipolar transistor 66 to the emitter. The resistor 65 is connected to the emitter of the bipolar transistor 66 so as to be inserted in series with the bypass 45.
　電流ＩＥＡが上昇して、コンパレータ６８の反転入力端子の電圧がコンパレータ６８の非反転入力端子の電圧よりも大きくなると、コンパレータ６８はその出力端子から電流を吸い込む。コンパレータ６８の出力端子に電流が吸い込まれると、電源ＶＢから抵抗６３経由でバイポーラトランジスタ６６のベースに流れるベース電流が減少する。その結果、電流ＩＥＡは上限電流ＩＵを超えないように制限される。 When the current I EA rises and the voltage at the inverting input terminal of the comparator 68 becomes greater than the voltage at the non-inverting input terminal of the comparator 68, the comparator 68 sinks current from its output terminal. When the current is absorbed in the output terminal of the comparator 68, the base current flowing from the power supply VB to the base of the bipolar transistor 66 via the resistor 63 decreases. As a result, the current I EA is limited so as not to exceed the upper limit current I U.
　上限電流ＩＵを調整する調整信号ＳＵは、抵抗６１を介して、コンパレータ６８の非反転入力端子に入力される。調整信号ＳＵのアナログ電圧値に応じて、コンパレータ６８の非反転入力端子の電圧は変化する。したがって、上限電流ＩＵは、調整信号ＳＵのアナログ電圧値に応じた電流値に調整される。調整信号ＳＵは、制御回路１５から供給されてもよいし、制御回路１５とは異なる回路又は装置から供給されてもよい。 Adjustment signal S U to adjust the upper limit current I U, via a resistor 61, is input to the non-inverting input terminal of the comparator 68. The voltage of the non-inverting input terminal of the comparator 68 changes according to the analog voltage value of the adjustment signal S U. Therefore, the upper limit current I U is adjusted to a current value according to the analog voltage value of the adjustment signal S U. The adjustment signal S U may be supplied from the control circuit 15 or may be supplied from a circuit or a device different from the control circuit 15.
　このように、電流制御回路４１Ｂは、迂回路４５に流れる電流ＩＥＡの大きさを抵抗６５を用いて検知し、その検知結果に基づいて、迂回路４５に流れる電流ＩＥＡの大きさを制御する。電流制御回路４１Ｂは、その検知結果をフィードバックすることによって、迂回路４５に流れる電流ＩＥＡの大きさが上限電流ＩＵを超えないように制限する。 As described above, the current control circuit 41B detects the magnitude of the current I EA flowing in the bypass 45 by using the resistor 65, and controls the magnitude of the current I EA flowing in the bypass 45 based on the detection result. To do. The current control circuit 41B limits the magnitude of the current I EA flowing through the bypass 45 so as not to exceed the upper limit current I U by feeding back the detection result.
　なお、ツェナーダイオード６７は、バイポーラトランジスタ６６のベース‐エミッタ間を過電圧から保護する素子である。 The Zener diode 67 is an element that protects the base-emitter of the bipolar transistor 66 from overvoltage.
　図５は、図３，４に示す電流制御回路４１Ａ，４１Ｂを使用した場合に、シートベルト２が引き出される時のモータ７の回転速度とモータ７の逆起電力によって迂回路４５に流れる電流との関係の一例を示す図である。迂回路４５が遮断状態（開放状態）のときは、電流ＩＥＡは迂回路４５には流れない。一方、迂回路４５が接続状態（短絡状態）のときは、シートベルト２の引き出し方向に対応する逆転方向にモータ７が回転する速度が速くなるほど、迂回路４５に流れる電流ＩＥＡは大きくなるので、ＥＡ荷重も大きくなる。しかしながら、図３，４示す電流制御回路４１Ａ，４１Ｂによれば、図５に示す電流制限ａ，ｂのように、所定の上限電流ＩＵよりも大きな電流ＩＥＡが流れなくなるので、上限電流ＩＵに対応する上限荷重ＦＵ以下にＥＡ荷重を制限できる。また、図４に示す電流制御回路４１Ｂによれば、調整信号ＳＵに応じて上限電流ＩＵを所望の電流値に調整できる。 FIG. 5 shows the rotation speed of the motor 7 when the seat belt 2 is pulled out and the current flowing through the bypass 45 due to the counter electromotive force of the motor 7 when the current control circuits 41A and 41B shown in FIGS. It is a figure which shows an example of the relationship of. When the detour 45 is in the cutoff state (open state), the current I EA does not flow in the detour 45. On the other hand, when the detour 45 is in the connected state (short-circuited state), the higher the speed at which the motor 7 rotates in the reverse rotation direction corresponding to the direction in which the seat belt 2 is pulled out, the larger the current I EA flowing through the detour 45 becomes. , EA load also increases. However, according to the current control circuits 41A and 41B shown in FIGS. 3 and 4, the current I EA larger than the predetermined upper limit current I U does not flow like the current limits a and b shown in FIG. The EA load can be limited to the upper limit load F U or less corresponding to U. Further, according to the current control circuit 41B shown in FIG. 4, the upper limit current I U can be adjusted to a desired current value according to the adjustment signal S U.
　ところで、図２に示す電流制御回路４１は、例えば、モータ７の逆起電力が所定の下限値（以下、下限電圧ＶＬとも称する）を超えるまで、電流ＩＥＡが迂回路４５に流れないように制限する構成を有してもよい。このような構成によって、モータ７に還流する電流ＩＥＡの効率がモータ７の回転速度に対して低下するため、モータ７の回転速度とＥＡ荷重との関係（より具体的には、モータ７の回転速度に対するＥＡ荷重の傾き特性）を後述の図８のように調整できる。つまり、モータ７の回転速度に対するＥＡ荷重の傾き特性を緩やかにできる。 By the way, the current control circuit 41 shown in FIG. 2 prevents the current I EA from flowing into the bypass 45 until the counter electromotive force of the motor 7 exceeds a predetermined lower limit value (hereinafter, also referred to as lower limit voltage VL ). The configuration may be limited to. With such a configuration, the efficiency of the current I EA flowing back to the motor 7 decreases with respect to the rotation speed of the motor 7, so that the relationship between the rotation speed of the motor 7 and the EA load (more specifically, the motor 7 The inclination characteristic of the EA load with respect to the rotation speed) can be adjusted as shown in FIG. That is, the inclination characteristic of the EA load with respect to the rotation speed of the motor 7 can be made gentle.
　また、電流制御回路４１は、外部からの供給される調整信号に応じて下限電圧ＶＬを調整する構成を有してもよい。下限電圧ＶＬの調整によって、モータ７の回転速度とＥＡ荷重との関係を外部から調整できる。例えば、制御回路１５は、乗員９の体重等の体格情報に基づいて、下限電圧ＶＬを調整する調整信号を電流制御回路４１に供給する。これにより、モータ７の回転速度とＥＡ荷重との関係を乗員９の体格に適した特性に設定できる。例えば、乗員９の体重が重くなるほど、下限電圧ＶＬが高く設定される。 Further, the current control circuit 41 may have a configuration of adjusting the lower limit voltage VL according to an adjustment signal supplied from the outside. By adjusting the lower limit voltage V L , the relationship between the rotation speed of the motor 7 and the EA load can be adjusted from the outside. For example, the control circuit 15 supplies the current control circuit 41 with an adjustment signal for adjusting the lower limit voltage VL based on the physique information such as the weight of the occupant 9. Accordingly, the relationship between the rotation speed of the motor 7 and the EA load can be set to a characteristic suitable for the physique of the occupant 9. For example, the lower the weight of the occupant 9, the higher the lower limit voltage VL is set.
　図６は、電流制御回路４１の第３の構成例を示す図である。図６に示す電流制御回路４１Ｃは、迂回路４５上の第１のノード４２と第２のノード４３との間に直列に接続される。電流制御回路４１Ｃは、モータ７に発生する逆起電力が所定の下限電圧ＶＬを超えるまで、電流ＩＥＡが迂回路４５に流れないように制限する電流制限回路である。電流制御回路４１Ｃは、抵抗７１，７２、ｎｐｎ型のバイポーラトランジスタ７３及びツェナーダイオード７４を有する。 FIG. 6 is a diagram showing a third configuration example of the current control circuit 41. The current control circuit 41C shown in FIG. 6 is connected in series between the first node 42 and the second node 43 on the bypass 45. The current control circuit 41C is a current limiting circuit that limits the current I EA from flowing into the bypass 45 until the counter electromotive force generated in the motor 7 exceeds a predetermined lower limit voltage V L. The current control circuit 41C has resistors 71 and 72, an npn-type bipolar transistor 73, and a Zener diode 74.
　迂回路４５が遮断状態から接続状態に切り替わると、モータ７の逆起電力が第１のノード４２と第２のノード４３との間に印加される。抵抗７１と抵抗７２との間の接続点は、バイポーラトランジスタ７３のベースに接続されている。 When the bypass 45 switches from the disconnected state to the connected state, the counter electromotive force of the motor 7 is applied between the first node 42 and the second node 43. The connection point between the resistors 71 and 72 is connected to the base of the bipolar transistor 73.
　モータ７の逆起電力が上昇して、バイポーラトランジスタ７３のベース‐エミッタ間の電圧が約０．６ボルトよりも大きくなると、バイポーラトランジスタ７３がオンする。これにより、バイポーラトランジスタ７３のコレクタ‐エミッタ間を流れる電流ＩＥＡが略零から急増する。つまり、モータ７に発生する逆起電力が所定の下限電圧ＶＬを超えるまで、電流ＩＥＡは、迂回路４５に流れないように制限される。 When the counter electromotive force of the motor 7 rises and the base-emitter voltage of the bipolar transistor 73 becomes larger than about 0.6 volt, the bipolar transistor 73 is turned on. As a result, the current I EA flowing between the collector and the emitter of the bipolar transistor 73 rapidly increases from substantially zero. That is, the current I EA is limited so as not to flow to the bypass 45 until the counter electromotive force generated in the motor 7 exceeds the predetermined lower limit voltage V L.
　このように、電流制御回路４１Ｃは、モータ７の逆起電力の大きさを抵抗７１，７２を用いて検知し、その検知結果に基づいて、迂回路４５に流れる電流ＩＥＡの大きさを制御する。 As described above, the current control circuit 41C detects the magnitude of the back electromotive force of the motor 7 using the resistors 71 and 72, and controls the magnitude of the current I EA flowing through the bypass 45 based on the detection result. To do.
　なお、ツェナーダイオード７４は、バイポーラトランジスタ７３のベース‐エミッタ間を過電圧から保護する素子である。 The Zener diode 74 is an element that protects the base-emitter of the bipolar transistor 73 from overvoltage.
　図７は、電流制御回路４１の第４の構成例を示す図である。図７に示す電流制御回路４１Ｄは、迂回路４５上の第１のノード４２と第２のノード４３との間に直列に接続される。電流制御回路４１Ｄは、モータ７に発生する逆起電力が所定の下限電圧ＶＬを超えるまで、電流ＩＥＡが迂回路４５に流れないように制限する電流制限回路である。電流制御回路４１Ｄは、外部から供給される調整信号ＳＬに応じて下限電圧ＶＬを調整する構成も有する。電流制御回路４１Ｄは、抵抗８１～８５、ｎｐｎ型のバイポーラトランジスタ８６、ツェナーダイオード８７及びコンパレータ８８を有する。 FIG. 7 is a diagram showing a fourth configuration example of the current control circuit 41. The current control circuit 41D shown in FIG. 7 is connected in series between the first node 42 and the second node 43 on the bypass 45. The current control circuit 41D is a current limiting circuit that limits the current I EA from flowing into the bypass 45 until the counter electromotive force generated in the motor 7 exceeds a predetermined lower limit voltage V L. The current control circuit 41D also has a configuration of adjusting the lower limit voltage V L according to an adjustment signal S L supplied from the outside. The current control circuit 41D has resistors 81 to 85, an npn-type bipolar transistor 86, a Zener diode 87, and a comparator 88.
　迂回路４５が遮断状態から接続状態に切り替わると、モータ７の逆起電力が第１のノード４２と第２のノード４３との間に印加される。抵抗８４と抵抗８５との間の接続点は、コンパレータ８８の非反転入力端子に接続されている。 When the bypass 45 switches from the disconnected state to the connected state, the counter electromotive force of the motor 7 is applied between the first node 42 and the second node 43. The connection point between the resistor 84 and the resistor 85 is connected to the non-inverting input terminal of the comparator 88.
　モータ７の逆起電力が上昇して、コンパレータ８８の非反転入力端子の電圧がコンパレータ８８の反転入力端子の電圧よりも大きくなると、コンパレータ８８の出力端子に吸い込まれる電流が減少する。コンパレータ８８の出力端子に吸い込まれる電流が減少すると、電源ＶＢから抵抗８３経由でバイポーラトランジスタ８６のベースに流れるベース電流が増加するので、バイポーラトランジスタ８６がオンする。これにより、バイポーラトランジスタ８６のコレクタ‐エミッタ間を流れる電流ＩＥＡが略零から急増する。つまり、モータ７に発生する逆起電力が所定の下限電圧ＶＬを超えるまで、電流ＩＥＡは、迂回路４５に流れないように制限される。 When the counter electromotive force of the motor 7 rises and the voltage at the non-inverting input terminal of the comparator 88 becomes higher than the voltage at the inverting input terminal of the comparator 88, the current drawn into the output terminal of the comparator 88 decreases. When the current drawn into the output terminal of the comparator 88 decreases, the base current flowing from the power supply VB to the base of the bipolar transistor 86 via the resistor 83 increases, so that the bipolar transistor 86 turns on. As a result, the current IEA flowing between the collector and the emitter of the bipolar transistor 86 rapidly increases from substantially zero. That is, the current I EA is limited so as not to flow to the bypass 45 until the counter electromotive force generated in the motor 7 exceeds the predetermined lower limit voltage V L.
　下限電圧ＶＬを調整する調整信号ＳＬは、抵抗８１を介して、コンパレータ８８の反転入力端子に入力される。調整信号ＳＬのアナログ電圧値に応じて、コンパレータ８８の反転入力端子の電圧は変化する。したがって、下限電圧ＶＬは、調整信号ＳＬのアナログ電圧値に応じた電圧値に調整される。調整信号ＳＬは、制御回路１５から供給されてもよいし、制御回路１５とは異なる回路又は装置から供給されてもよい。 Adjustment signal S L to adjust the lower limit voltage V L, via a resistor 81, it is input to the inverting input terminal of the comparator 88. The voltage at the inverting input terminal of the comparator 88 changes according to the analog voltage value of the adjustment signal S L. Therefore, the lower limit voltage V L is adjusted to a voltage value according to the analog voltage value of the adjustment signal S L. The adjustment signal S L may be supplied from the control circuit 15 or may be supplied from a circuit or a device different from the control circuit 15.
　このように、電流制御回路４１Ｄは、モータ７の逆起電力の大きさを抵抗８４，８５を用いて検知し、その検知結果に基づいて、迂回路４５に流れる電流ＩＥＡの大きさを制御する。 As described above, the current control circuit 41D detects the magnitude of the back electromotive force of the motor 7 by using the resistors 84 and 85, and controls the magnitude of the current I EA flowing through the bypass 45 based on the detection result. To do.
　なお、ツェナーダイオード８７は、バイポーラトランジスタ８６のベース‐エミッタ間を過電圧から保護する素子である。 The Zener diode 87 is an element that protects the base-emitter of the bipolar transistor 86 from overvoltage.
　図８は、図６，７に示す電流制御回路４１Ｃ，４１Ｄを使用した場合に、シートベルト２が引き出される時のモータ７の回転速度とモータ７の逆起電力によって迂回路４５に流れる電流との関係の一例を示す図である。図６，７示す電流制御回路４１Ｃ，４１Ｄによれば、図８に示す電流制限ｃ，ｄのように、モータ７の回転速度が上昇しても、逆起電力が下限電圧ＶＬを超えるまで、電流ＩＥＡはほとんど流れない。よって、モータ７の回転速度とＥＡ荷重との関係（モータ７の回転速度に対するＥＡ荷重の傾き特性）を緩やかな特性に調整できる。また、図７に示す電流制御回路４１Ｄによれば、調整信号ＳＬに応じて下限電圧ＶＬを所望の電圧値に調整できる。 FIG. 8 shows the rotation speed of the motor 7 when the seat belt 2 is pulled out and the current flowing in the bypass 45 by the counter electromotive force of the motor 7 when the current control circuits 41C and 41D shown in FIGS. It is a figure which shows an example of the relationship of. According to the current control circuits 41C and 41D shown in FIGS. 6 and 7, even when the rotation speed of the motor 7 increases, the counter electromotive force exceeds the lower limit voltage V L, as in the current limits c and d shown in FIG. , The current I EA hardly flows. Therefore, the relationship between the rotation speed of the motor 7 and the EA load (the inclination characteristic of the EA load with respect to the rotation speed of the motor 7) can be adjusted to a gentle characteristic. Further, according to the current control circuit 41D shown in FIG. 7, the lower limit voltage V L can be adjusted to a desired voltage value according to the adjustment signal S L.
　図９は、電流制御回路４１の第５の構成例を示す図である。図９に示す電流制御回路４１Ｅは、図３に示す電流制御回路４１Ａと図６に示す電流制御回路４１Ｃとを合成した回路であり、電流制御回路４１Ａが有する上限電流制限機能と電流制御回路４１Ｃが有する下限電圧制限機能とを有する。したがって、電流制御回路４１Ｅは、迂回路４５に流れる電流ＩＥＡの大きさを抵抗５３を用いて検知し、モータ７の逆起電力の大きさを抵抗７１，７２を用いて検知し、それらの検知結果に基づいて、迂回路４５に流れる電流ＩＥＡの大きさを制御する。 FIG. 9 is a diagram showing a fifth configuration example of the current control circuit 41. The current control circuit 41E shown in FIG. 9 is a circuit in which the current control circuit 41A shown in FIG. 3 and the current control circuit 41C shown in FIG. 6 are combined, and the upper limit current limiting function and the current control circuit 41C of the current control circuit 41A are included. Has a lower limit voltage limiting function. Therefore, the current control circuit 41E detects the magnitude of the current I EA flowing in the bypass 45 by using the resistor 53, the magnitude of the counter electromotive force of the motor 7 by using the resistors 71 and 72, and The magnitude of the current I EA flowing through the bypass 45 is controlled based on the detection result.
　図１０は、電流制御回路４１の第６の構成例を示す図である。図１０に示す電流制御回路４１Ｆは、図４に示す電流制御回路４１Ｂと図７に示す電流制御回路４１Ｄとを合成した回路であり、電流制御回路４１Ｂが有する上限電流調整機能と電流制御回路４１Ｄが有する下限電圧調整機能とを有する。したがって、電流制御回路４１Ｆは、迂回路４５に流れる電流ＩＥＡの大きさを抵抗６５を用いて検知し、モータ７の逆起電力の大きさを抵抗８４，８５を用いて検知し、それらの検知結果に基づいて、迂回路４５に流れる電流ＩＥＡの大きさを制御する。そして、電流制御回路４１Ｆは、調整信号ＳＵに応じて上限電流ＩＵを調整し、調整信号ＳＬに応じて下限電圧ＶＬを調整する。 FIG. 10 is a diagram showing a sixth configuration example of the current control circuit 41. The current control circuit 41F shown in FIG. 10 is a circuit in which the current control circuit 41B shown in FIG. 4 and the current control circuit 41D shown in FIG. 7 are combined, and the upper limit current adjustment function and the current control circuit 41D of the current control circuit 41B are included. Has a lower limit voltage adjusting function. Therefore, the current control circuit 41F detects the magnitude of the current I EA flowing in the bypass 45 by using the resistor 65 and the magnitude of the counter electromotive force of the motor 7 by using the resistors 84 and 85, and detects those magnitudes. The magnitude of the current I EA flowing through the bypass 45 is controlled based on the detection result. Then, the current control circuit 41F adjusts the upper limit current I U according to the adjustment signal S U , and adjusts the lower limit voltage V L according to the adjustment signal S L.
　図１１は、図９，１０に示す電流制御回路４１Ｅ，４１Ｆを使用した場合に、シートベルト２が引き出される時のモータ７の回転速度とモータ７の逆起電力によって迂回路４５に流れる電流との関係の一例を示す図である。図９，１０示す電流制御回路４１Ｅ，４１Ｆによれば、図１１に示す電流制限ｅ，ｆのように、所定の上限電流ＩＵよりも大きな電流ＩＥＡが流れなくなるので、上限電流ＩＵに対応する上限荷重ＦＵ以下にＥＡ荷重を制限できる。また、図９，１０示す電流制御回路４１Ｅ，４１Ｆによれば、図８に示す電流制限ｃ，ｄのように、モータ７の回転速度が上昇しても、逆起電力が下限電圧ＶＬを超えるまで、電流ＩＥＡはほとんど流れない。よって、モータ７の回転速度とＥＡ荷重との関係（モータ７の回転速度に対するＥＡ荷重の傾き特性）を緩やかな特性に調整できる。さらに、図１０に示す電流制御回路４１Ｆによれば、調整信号ＳＵに応じて上限電流ＩＵを所望の電流値に調整でき、調整信号ＳＬに応じて下限電圧ＶＬを所望の電圧値に調整できる。 FIG. 11 shows the rotation speed of the motor 7 when the seat belt 2 is pulled out and the current flowing in the bypass 45 due to the counter electromotive force of the motor 7 when the current control circuits 41E and 41F shown in FIGS. It is a figure which shows an example of the relationship of. 9 and 10 shows a current control circuit 41E, according to 41F, as current limiting e, f shown in FIG. 11, since not flow a large current I EA than a predetermined upper limit current I U, the upper limit current I U The EA load can be limited below the corresponding upper limit load F U. Further, according to the current control circuits 41E and 41F shown in FIGS. 9 and 10, even when the rotation speed of the motor 7 increases, the counter electromotive force causes the lower limit voltage V L to fall below the lower limit voltage V L , like the current limits c and d shown in FIG. Little current I EA flows until it is exceeded. Therefore, the relationship between the rotation speed of the motor 7 and the EA load (the inclination characteristic of the EA load with respect to the rotation speed of the motor 7) can be adjusted to a gentle characteristic. Further, according to the current control circuit 41F shown in FIG. 10, the upper limit current I U can be adjusted to a desired current value according to the adjustment signal S U , and the lower limit voltage V L can be adjusted to a desired voltage value according to the adjustment signal S L. Can be adjusted to.
　図１２は、駆動回路１４の第２の構成例を示す図である。第１の構成例と同様の点については、その説明を省略する。図１２に示す駆動回路１４Ｂは、ローサイドのスイッチング素子２５を有し、モータ７に一方向のみの駆動電流を供給可能なローサイド駆動回路である。駆動回路１４Ｂは、例えば、シートベルト２の引き出し方向に対応する逆転方向にモータ７を回転させる必要がない場合に使用され、シートベルト２の巻き取り方向に対応する正転方向にモータ７を回転させる駆動電流をモータ７に供給できる。 FIG. 12 is a diagram showing a second configuration example of the drive circuit 14. The description of the same points as the first configuration example will be omitted. The drive circuit 14B shown in FIG. 12 is a low-side drive circuit that has a low-side switching element 25 and can supply a drive current to the motor 7 in only one direction. The drive circuit 14B is used, for example, when it is not necessary to rotate the motor 7 in the reverse rotation direction corresponding to the withdrawal direction of the seat belt 2, and rotates the motor 7 in the normal rotation direction corresponding to the winding direction of the seat belt 2. The drive current to be supplied can be supplied to the motor 7.
　駆動回路１４Ｂは、電源ＶＢとグランド（ＧＮＤ）との間に接続されており、モータ７に対してグランド側に接続されるローサイドのスイッチング素子２５を備える。スイッチング素子２５は、第１の端子７ａに接続される電極（ドレイン又はコレクタ）と、グランド側に接続される電極（ソース又はエミッタ）と、制御回路１５に接続される電極（ゲート又はベース）とを有するローサイドアームである。第２の端子７ｂは、電源ＶＢに接続される。ダイオード３５は、スイッチング素子２５のボディダイオードでもよいし、スイッチング素子２５に並列に追加接続された整流素子でもよい。 The drive circuit 14B is connected between the power supply VB and the ground (GND), and includes a low-side switching element 25 connected to the ground side with respect to the motor 7. The switching element 25 includes an electrode (drain or collector) connected to the first terminal 7a, an electrode (source or emitter) connected to the ground side, and an electrode (gate or base) connected to the control circuit 15. It is a low side arm having. The second terminal 7b is connected to the power supply VB. The diode 35 may be a body diode of the switching element 25 or a rectifying element additionally connected in parallel with the switching element 25.
　制御回路１５は、シートベルト２をスプール８に巻き取らせるモード（巻き取りモード）では、シートベルト２の巻き取り方向に対応する正転方向にモータ７が回転（正回転）するように、駆動回路１４Ｂのスイッチング素子２５を制御する。例えば、制御回路１５は、モータ７を正回転させる巻き取りモードでは、スイッチング素子２５を所定のデューティ比のＰＷＭ制御でオン／オフ（スイッチング）させる。 In the mode in which the seat belt 2 is wound around the spool 8 (winding mode), the control circuit 15 drives the motor 7 to rotate (forward rotation) in the forward rotation direction corresponding to the winding direction of the seat belt 2. It controls the switching element 25 of the circuit 14B. For example, the control circuit 15 turns on / off (switches) the switching element 25 by PWM control with a predetermined duty ratio in the winding mode in which the motor 7 rotates forward.
　スイッチング素子２５がこのように制御されることにより、駆動回路１４Ｂは、シートベルト２の巻き取り方向にスプール８を回転させる方向（正転方向）に、モータ７を回転（正回転）させることができる。モータ７の回転軸が正回転すると、その正回転の駆動力は、動力伝達機構１７によって、スプール８に伝達される。これにより、スプール８は、シートベルト２を巻き取る方向に回転するので、シートベルト２はスプール８に巻き取られる。 By controlling the switching element 25 in this way, the drive circuit 14B can rotate the motor 7 (normal rotation) in the direction in which the spool 8 is rotated in the winding direction of the seat belt 2 (normal rotation direction). it can. When the rotation shaft of the motor 7 rotates in the forward direction, the drive force of the forward rotation is transmitted to the spool 8 by the power transmission mechanism 17. As a result, the spool 8 rotates in the direction in which the seat belt 2 is wound, so that the seat belt 2 is wound around the spool 8.
　駆動回路１４Ｂは、スイッチング素子２５に並列に接続される電流調整回路４４を備える。図１２の構成では、逆起電力の発生によって、第１の端子７ａの電位が第２の端子７ｂの電位よりも相対的に高くなる（言い換えれば、第２の端子７ｂの電位が第１の端子７ａの電位よりも相対的に低くなる）。 The drive circuit 14B includes a current adjustment circuit 44 connected in parallel with the switching element 25. In the configuration of FIG. 12, the potential of the first terminal 7a becomes relatively higher than the potential of the second terminal 7b due to the generation of the counter electromotive force (in other words, the potential of the second terminal 7b becomes the first potential). It becomes relatively lower than the potential of the terminal 7a).
　そこで、制御回路１５は、車両１３の衝突が検知されたことを表す指令信号を受信した場合、シートベルト２の巻き取り方向にスプール８を回転させる正転方向にモータ７を回転させてから、迂回路４５を遮断状態から接続状態に切り替える。迂回路４５は、スイッチング素子２５の両端に並列に接続され、モータ７の逆起電力によって生ずる電流ＩＥＡをモータ７に還流させる電流経路である。迂回路４５は、電流ＩＥＡをモータ７に還流させる還流路の一部である。迂回路４５が遮断状態から接続状態に切り替わると、逆起電力によって生ずる電流ＩＥＡは、第１の端子７ａ、迂回路４５、グランドＧＮＤ、電源ＶＢ、第２の端子７ｂの順路で還流する。この際、電流ＩＥＡは、電流制御回路４１によって上限電流ＩＵを超えないように制限される。 Therefore, when the control circuit 15 receives the command signal indicating that the collision of the vehicle 13 is detected, the control circuit 15 rotates the motor 7 in the forward rotation direction in which the spool 8 is rotated in the winding direction of the seat belt 2, and then, The bypass 45 is switched from the disconnected state to the connected state. The bypass 45 is a current path that is connected in parallel to both ends of the switching element 25 and causes the current I EA generated by the back electromotive force of the motor 7 to flow back to the motor 7. The bypass 45 is a part of a return path for returning the current I EA to the motor 7. When the bypass circuit 45 is switched from the cut-off state to the connection state, the current I EA generated by the counter electromotive force flows back in the normal path of the first terminal 7a, the bypass circuit 45, the ground GND, the power supply VB, and the second terminal 7b. At this time, the current I EA is limited by the current control circuit 41 so as not to exceed the upper limit current I U.
　このように、制御回路１５は、逆起電力によって生ずる電流ＩＥＡをモータ７に迂回路４５経由で還流させることで、シートベルト２の引き出し方向にスプール８を回転させる逆転方向にモータ７が回転することを抑制できる。その結果、車両衝突時に乗員９に作用する衝突エネルギーを吸収することが可能となる。また、電流制御回路４１が電流ＩＥＡの大きさを制御することによって、ＥＡ荷重を精度良く調整できる。 In this way, the control circuit 15 causes the current I EA generated by the back electromotive force to flow back to the motor 7 via the bypass 45, so that the motor 7 rotates in the reverse direction in which the spool 8 is rotated in the pulling direction of the seat belt 2. Can be suppressed. As a result, it becomes possible to absorb the collision energy that acts on the occupant 9 during a vehicle collision. Further, the current control circuit 41 controls the magnitude of the current I EA , so that the EA load can be adjusted with high accuracy.
　図１３は、駆動回路１４の第３の構成例を示す図である。上述の構成例と同様の点については、その説明を省略する。図１３に示す駆動回路１４Ｃは、４つのスイッチング素子２１，２２，２３，２４を有し、モータ７に流す駆動電流の方向を切り替え可能なＨブリッジ駆動回路である。駆動回路１４Ｃは、電流制御回路４１Ｇがスイッチング素子２２と一体化された構成を有する。電流制御回路４１Ｇは、上述の電流制御回路４１の一例である。 FIG. 13 is a diagram showing a third configuration example of the drive circuit 14. The description of the same points as those of the above configuration example will be omitted. The drive circuit 14C shown in FIG. 13 is an H-bridge drive circuit that has four switching elements 21, 22, 23, and 24 and is capable of switching the direction of the drive current supplied to the motor 7. The drive circuit 14C has a configuration in which the current control circuit 41G is integrated with the switching element 22. The current control circuit 41G is an example of the current control circuit 41 described above.
　電流制御回路４１Ｇは、還流路４６に流れる電流ＩＥＡの大きさを、制御回路１５から供給される制御信号Ａに従ってスイッチング素子２２のスイッチング（オンオフ）を繰り返すことにより制御する。還流路４６は、スイッチング素子２２に接続され、モータ７の逆起電力によって生ずる電流ＩＥＡをモータ７に還流させる電流経路である。電流制御回路４１Ｇが電流ＩＥＡの大きさを制御することによって、ＥＡ荷重を精度良く調整できる。 The current control circuit 41G controls the magnitude of the current I EA flowing through the return path 46 by repeating switching (on / off) of the switching element 22 in accordance with the control signal A supplied from the control circuit 15. The return path 46 is a current path that is connected to the switching element 22 and causes the current I EA generated by the counter electromotive force of the motor 7 to return to the motor 7. The current control circuit 41G controls the magnitude of the current I EA , whereby the EA load can be adjusted with high accuracy.
　制御回路１５は、例えば、車両１３の衝突が検知されたことを表す指令信号を受信した場合、還流路４６に流れる電流ＩＥＡの大きさを制御する制御信号Ａ（例えば、ＰＷＭの制御信号）を出力する。 For example, when the control circuit 15 receives a command signal indicating that a collision of the vehicle 13 has been detected, the control circuit 15 controls the magnitude of the current I EA flowing through the return path 46 (for example, a PWM control signal). Is output.
　電流制御回路４１Ｇは、上限電流ＩＵと下限電圧ＶＬとの少なくとも一方を用いて電流ＩＥＡの大きさを制御する上述の構成を有してもよい。また、電流制御回路４１Ｇは、外部から供給される調整信号に応じて上限電流ＩＵと下限電圧ＶＬとの少なくとも一方を調整する上述の構成を有してもよい。 The current control circuit 41G may have the above-described configuration that controls the magnitude of the current I EA by using at least one of the upper limit current I U and the lower limit voltage V L. Further, the current control circuit 41G may have the above-described configuration that adjusts at least one of the upper limit current I U and the lower limit voltage V L according to the adjustment signal supplied from the outside.
　図１４は、電流制御回路４１Ｇの構成例を示す図である。電流制御回路４１Ｇは、還流路４６上の第１のノード４２と第２のノード４３との間に直列に接続される。電流制御回路４１Ｇは、還流路４６に流れる電流ＩＥＡの大きさが所定の上限電流ＩＵを超えないように制限する電流制限回路である。電流制御回路４１Ｇは、外部から供給される調整信号ＳＵに応じて上限電流ＩＵを調整する構成も有する。電流制御回路４１Ｇは、抵抗６１～６５、ローサイドのスイッチング素子２２、ツェナーダイオード６７及びコンパレータ６８を有する。 FIG. 14 is a diagram showing a configuration example of the current control circuit 41G. The current control circuit 41G is connected in series between the first node 42 and the second node 43 on the return path 46. The current control circuit 41G is a current limiting circuit that limits the magnitude of the current I EA flowing in the return path 46 so as not to exceed a predetermined upper limit current I U. The current control circuit 41G also has a configuration of adjusting the upper limit current I U according to an adjustment signal S U supplied from the outside. The current control circuit 41G includes resistors 61 to 65, a low side switching element 22, a Zener diode 67, and a comparator 68.
　電流制御回路４１Ｇは、車両１３の衝突が検知された場合に制御回路１５から供給される制御信号Ａに従って、スイッチング素子２２のスイッチング（オンオフ）を繰り返す。スイッチング素子２２のオンオフが電流制御回路４１Ｇにより繰り返されることによって、電流ＩＥＡはその流れが制限されながら還流路４６に流れるので、還流路４６に流れる電流ＩＥＡの大きさの制御が可能となる。 The current control circuit 41G repeats switching (ON / OFF) of the switching element 22 according to the control signal A supplied from the control circuit 15 when the collision of the vehicle 13 is detected. The current I EA flows through the return path 46 while the flow of the switching element 22 is limited by the current control circuit 41G being repeated, so that the magnitude of the current I EA flowing through the return path 46 can be controlled. ..
　制御信号Ａは、抵抗６３を介して、スイッチング素子２２のゲートに供給される。制御信号Ａによってスイッチング素子２２のオンオフが繰り返されることにより、電流ＩＥＡがスイッチング素子２２のドレインからソースに流れる。抵抗６５は、還流路４６に直列に挿入されるように、スイッチング素子２２のソースに接続されている。電流ＩＥＡが上昇すると、抵抗６５の両端電圧が上昇する。 The control signal A is supplied to the gate of the switching element 22 via the resistor 63. The switching element 22 is repeatedly turned on and off by the control signal A, so that the current I EA flows from the drain to the source of the switching element 22. The resistor 65 is connected to the source of the switching element 22 so as to be inserted in the return path 46 in series. When the current I EA rises, the voltage across the resistor 65 rises.
　電流ＩＥＡが上昇して、コンパレータ６８の反転入力端子の電圧がコンパレータ６８の非反転入力端子の電圧よりも大きくなると、コンパレータ６８はその出力端子から電流を吸い込む。コンパレータ６８の出力端子に電流が吸い込まれると、スイッチング素子２２のゲート電圧が低下する。その結果、電流ＩＥＡは上限電流ＩＵを超えないように制限される。 When the current I EA rises and the voltage at the inverting input terminal of the comparator 68 becomes greater than the voltage at the non-inverting input terminal of the comparator 68, the comparator 68 sinks current from its output terminal. When the current is drawn into the output terminal of the comparator 68, the gate voltage of the switching element 22 drops. As a result, the current I EA is limited so as not to exceed the upper limit current I U.
　以上、シートベルトリトラクタを実施形態により説明したが、本発明は上記実施形態に限定されるものではない。他の実施形態の一部又は全部との組み合わせや置換などの種々の変形及び改良が、本発明の範囲内で可能である。 Although the seatbelt retractor has been described above with reference to the embodiment, the present invention is not limited to the above embodiment. Various modifications and improvements, such as combination with some or all of the other embodiments and substitution, are possible within the scope of the present invention.
　例えば、図２において、制御回路１５は、モータ７を正回転させる巻き取りモードでは、スイッチング素子２３を所定のデューティ比のＰＷＭ制御でオン／オフさせ、スイッチング素子２１，２４を常時オフさせ、スイッチング素子２２を常時オンさせてもよい。このとき、スイッチング素子２３のオフ時の還流電流による発熱を抑えるため、制御回路１５は、スイッチング素子２３のオフ時にスイッチング素子２４をオンさせてもよい。この場合、電流調整回路４４が直列に挿入される迂回路４５は、スイッチング素子２３に並列に接続される。 For example, in FIG. 2, the control circuit 15 turns on / off the switching element 23 by PWM control with a predetermined duty ratio in the winding mode in which the motor 7 rotates in the forward direction, constantly turns off the switching elements 21 and 24, and performs switching. The element 22 may be always turned on. At this time, the control circuit 15 may turn on the switching element 24 when the switching element 23 is turned off in order to suppress heat generation due to the return current when the switching element 23 is turned off. In this case, the bypass 45 in which the current adjusting circuit 44 is inserted in series is connected in parallel to the switching element 23.
　本国際出願は、２０１８年１１月７日に出願した日本国特許出願第２０１８－２０９９７２号に基づく優先権を主張するものであり、日本国特許出願第２０１８－２０９９７２号の全内容を本国際出願に援用する。 This international application claims priority based on Japanese Patent Application No. 2018-2091972 filed on November 7, 2018, and the entire content of Japanese Patent Application No. 2018-2091972 is applied to the present international application. Be used for.
１　制御装置
２　シートベルト
６　シートベルト巻き取り機構
７　モータ
８　スプール
１０　シートベルトリトラクタ
１４，１４Ａ，１４Ｂ，１４Ｃ　駆動回路
１５　制御回路
１７　動力伝達機構
２１～２５　スイッチング素子
４０　切り替えスイッチ
４１，４１Ａ～４１Ｇ　電流制御回路
４４　電流調整回路
４５　迂回路
４６　還流路
１００　シートベルト装置 1 Control Device 2 Seat Belt 6 Seat Belt Winding Mechanism 7 Motor 8 Spool 10 Seat Belt Retractor 14, 14A, 14B, 14C Drive Circuit 15 Control Circuit 17 Power Transmission Mechanism 21-25 Switching Element 40 Changeover Switch 41, 41A-41G Current Control circuit 44 Current adjusting circuit 45 Detour 46 Return path 100 Seat belt device

Claims (17)

  1. 　スプールと、
    　前記スプールを回転させるモータと、
    　前記モータに接続されるスイッチング素子と、
    　シートベルトを前記スプールに巻き取らせる方向に前記モータが回転するように前記スイッチング素子をＰＷＭ制御でスイッチングさせる制御回路と、
    　前記スイッチング素子に接続され、前記モータの逆起電力によって生ずる電流を前記モータに還流させる還流路と、
    　前記還流路に流れる前記電流の大きさを制御する電流制御回路とを備える、シートベルトリトラクタ。     Spool,
    A motor for rotating the spool,
    A switching element connected to the motor,
    A control circuit for switching the switching element by PWM control so that the motor rotates in a direction in which the seat belt is wound around the spool;
    A return path that is connected to the switching element and returns a current generated by a back electromotive force of the motor to the motor;
    A seat belt retractor, comprising: a current control circuit that controls the magnitude of the current flowing through the return path.
  2. 　前記電流制御回路は、前記還流路に流れる前記電流の大きさが所定の上限値を超えないように制限する、請求項１に記載のシートベルトリトラクタ。 The seatbelt retractor according to claim 1, wherein the current control circuit limits the magnitude of the current flowing in the return path so as not to exceed a predetermined upper limit value.
  3. 　前記電流制御回路は、外部から供給される信号に応じて前記上限値を調整する、請求項２に記載のシートベルトリトラクタ。 The seat belt retractor according to claim 2, wherein the current control circuit adjusts the upper limit value according to a signal supplied from the outside.
  4. 　前記電流制御回路は、前記逆起電力が所定の下限値を超えるまで、前記電流が前記還流路に流れないように制限する、請求項１に記載のシートベルトリトラクタ。 The seat belt retractor according to claim 1, wherein the current control circuit limits the current so that the current does not flow into the return path until the counter electromotive force exceeds a predetermined lower limit value.
  5. 　前記電流制御回路は、外部からの供給される信号に応じて前記下限値を調整する、請求項４に記載のシートベルトリトラクタ。 The seat belt retractor according to claim 4, wherein the current control circuit adjusts the lower limit value according to a signal supplied from the outside.
  6. 　前記信号は、乗員の体格情報に基づき供給される、請求項３に記載のシートベルトリトラクタ。 The seatbelt retractor according to claim 3, wherein the signal is supplied based on physique information of an occupant.
  7. 　前記電流制御回路は、前記逆起電力と前記還流路に流れる前記電流との少なくとも一方を検知し、その検知結果に基づいて、前記還流路に流れる前記電流の大きさを制御する、請求項１に記載のシートベルトリトラクタ。 The current control circuit detects at least one of the back electromotive force and the current flowing in the return path, and controls the magnitude of the current flowing in the return path based on the detection result. Seat belt retractor described in.
  8. 　前記電流制御回路は、前記還流路に直列に挿入される、請求項１記載のシートベルトリトラクタ。 The seat belt retractor according to claim 1, wherein the current control circuit is inserted in series in the return path.
  9. 　前記スイッチング素子は、前記モータを駆動するＨブリッジ駆動回路に含まれる第１のローサイドスイッチング素子である、請求項１に記載のシートベルトリトラクタ。 The seat belt retractor according to claim 1, wherein the switching element is a first low-side switching element included in an H-bridge drive circuit that drives the motor.
  10. 　前記還流路に流れる前記電流は、前記Ｈブリッジ駆動回路に含まれる第２のローサイドスイッチング素子又は前記第２のローサイドスイッチング素子におけるダイオードを経由する、請求項９に記載のシートベルトリトラクタ。 The seatbelt retractor according to claim 9, wherein the current flowing through the return path passes through a second low-side switching element included in the H-bridge drive circuit or a diode in the second low-side switching element.
  11. 　前記電流制御回路は、前記還流路に流れる前記電流の大きさを、前記スイッチング素子をスイッチングさせることにより制御する、請求項１に記載のシートベルトリトラクタ。 The seat belt retractor according to claim 1, wherein the current control circuit controls the magnitude of the current flowing through the return path by switching the switching element.
  12. 　前記電流制御回路は、車両の衝突が検知された場合、前記還流路に流れる前記電流の大きさを制御する、請求項１に記載のシートベルトリトラクタ。 The seat belt retractor according to claim 1, wherein the current control circuit controls the magnitude of the current flowing through the return path when a vehicle collision is detected.
  13. 　前記還流路は、前記スイッチング素子に並列に接続される迂回路を含む、請求項１に記載のシートベルトリトラクタ。 The seat belt retractor according to claim 1, wherein the return path includes a detour that is connected in parallel to the switching element.
  14. 　前記制御回路は、車両の衝突が検知された場合、前記迂回路を遮断状態から接続状態に切り替える、請求項１３に記載のシートベルトリトラクタ。 The seat belt retractor according to claim 13, wherein the control circuit switches the detour from the disconnected state to the connected state when a vehicle collision is detected.
  15. 　前記制御回路は、前記迂回路に直列に挿入されるスイッチを作動させることによって、前記迂回路を遮断状態から接続状態に切り替える、請求項１４に記載のシートベルトリトラクタ。 The seatbelt retractor according to claim 14, wherein the control circuit switches the detour from the disconnected state to the connected state by operating a switch that is inserted in series into the detour.
  16. 　前記電流制御回路は、前記迂回路に流れる前記電流の大きさを制御する、請求項１３に記載のシートベルトリトラクタ。 The seat belt retractor according to claim 13, wherein the current control circuit controls the magnitude of the current flowing through the bypass.
  17. 　請求項１に記載のシートベルトリトラクタと、前記シートベルトと、前記シートベルトに取り付けられるタングと、前記タングが着脱可能に係合されるバックルとを備える、シートベルト装置。 A seat belt device comprising: the seat belt retractor according to claim 1; the seat belt; a tongue attached to the seat belt; and a buckle to which the tongue is detachably engaged.
PCT/JP2019/041823 2018-11-07 2019-10-25 Seatbelt retractor and seatbelt device WO2020095709A1 (en)

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JP2018-209972 2018-11-07

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009262811A (en) * 2008-04-25 2009-11-12 Tokai Rika Co Ltd Webbing retracting device
JP2011111035A (en) * 2009-11-26 2011-06-09 Denso Corp Motor driving circuit
JP2011183873A (en) * 2010-03-05 2011-09-22 Tokai Rika Co Ltd Webbing winding device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009262811A (en) * 2008-04-25 2009-11-12 Tokai Rika Co Ltd Webbing retracting device
JP2011111035A (en) * 2009-11-26 2011-06-09 Denso Corp Motor driving circuit
JP2011183873A (en) * 2010-03-05 2011-09-22 Tokai Rika Co Ltd Webbing winding device

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