JP2018034617A - Seat belt retractor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seat belt retractor control device capable of preventing taking-up of a seat belt, which an occupant does not intend when locking the seat belt with an ALR lock mechanism, while suppressing battery consumption.SOLUTION: A seat belt retractor control device includes an ALR lock mechanism 205 which makes drawing of a seat belt mechanically impossible until the belt draw-out amount of a seat belt 301 is above a first threshold level, and then the belt draw-out amount becomes below a second threshold level smaller than the first threshold level. When the belt draw-out amount of the seat belt is below a third threshold level which is set to be smaller than the first threshold level and larger than the second threshold level, in a state that the drawing of the seat belt becomes impossible by the ALR lock mechanism, a motor 202 is driven for a fixed amount so as to couple a clutch provided between a gear of a spool 201 and a gear of the motor, and make the load of the motor act on the spool.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a seat belt retractor control device that controls a seat belt retractor including an electric winding device and an automatic lock type retractor mechanism.

  2. Description of the Related Art Conventionally, as a seat belt retractor, there is known a seat belt retractor including an electric winding device that winds a seat belt by driving a motor. According to this electric take-up device, the motor is controlled so as to apply tension to the seat belt when there is a possibility of colliding with the preceding vehicle during a vehicle operation or when sudden braking is applied, and the occupant is restrained. Thus, the effect of an airbag or the like at the time of a collision can be enhanced. The electric winding device is also used for removing the slack of the seat belt when the seat belt is mounted, maintaining the posture of the occupant during acceleration / deceleration of the vehicle, and storing the seat belt when the seat belt is removed.

  In addition, as a seat belt retractor, one having an automatic lock type retractor (ALR) mechanism is known. According to this ALR mechanism, when the seat belt is pulled out to the maximum, thereafter, the withdrawal of the seat belt is prohibited until the seat belt is completely wound.

  By the way, with regard to the seat belt retractor equipped with the ALR mechanism, when the child is playing, the seat belt is pulled out to the maximum and the lock function is activated, and the withdrawal of the seat belt is prohibited. Has been reported to be tightened.

  In Patent Document 1, as a countermeasure, in a seat belt retractor provided with an electric winding device and an ALR mechanism, a belt drawing limit position is set on the winding direction side of the lock position by the ALR mechanism, and this drawing A method for conducting energization control that resists the pulling of the belt in the pulling direction side from the limit position is proposed.

JP2013-1323A

  Conventionally, a control device (ECU) that controls a motor of a seat belt retractor consumes less power when a seat belt attachment / detachment operation is not performed for a certain period of time when an ignition switch is OFF in order to suppress battery consumption. It is configured to transition to a standby state (a state in which energization control of the motor is impossible).

  On the other hand, in the method of Patent Document 1, since it is necessary to monitor the belt withdrawal amount by the ECU so that the seat belt is not pulled out beyond the pull-out limit position, when the seat belt is wound or pulled out. Has to start the ECU. For this reason, there is a possibility that the battery consumption may increase due to an increase in the frequency at which the ECU is activated while the ignition switch is OFF.

  The present invention has been made in view of the above problems, and an object thereof is to prevent the seat belt from being unintentionally taken up by the occupant when the seat belt is locked by the ALR lock mechanism while suppressing battery consumption. A seat belt retractor control device is provided.

  To achieve the above object, the present invention provides a spool that winds up a seat belt, a spring that urges the spool to rotate in the winding direction, a motor that generates a driving torque that rotates the spool, A clutch provided between the spool gear and the motor gear, a motor drive circuit for driving the motor, a belt withdrawal amount detection circuit for detecting a belt withdrawal amount of the seat belt, and the belt withdrawal amount An ALR lock mechanism that mechanically disables the withdrawal of the seat belt until the belt withdrawal amount falls below a second threshold value that is smaller than the first threshold value after the first threshold value is exceeded. In the seat belt retractor control device for controlling the retractor, the ALR lock mechanism disables the seat belt from being pulled out. In a state, when the belt withdrawal amount falls below a third threshold value set to a value smaller than the first threshold value and larger than the second threshold value, the motor is driven by a certain amount A clutch is fastened and the load of the motor is applied to the spool.

  According to the present invention configured as described above, when the seat belt is wound by a certain amount by the spring force in a state where the seat belt is locked by the ALR lock mechanism, the clutch between the spool gear and the motor gear is released. Fastened and the motor load acts on the spool against the spring force. As a result, the seat belt cannot be wound unless the motor 202 is driven by an occupant's intentional operation, and therefore it is possible to prevent the seat belt 301 from being unwound by the occupant.

  Further, since it is not necessary to monitor the amount of belt withdrawal before the seat belt is locked by the ALR lock mechanism, it is possible to suppress battery consumption when the ignition switch is OFF.

  According to the present invention, it is possible to prevent the seat belt from being unintentionally taken up by the occupant when the seat belt is locked by the ALR lock mechanism while suppressing battery consumption by the seat belt retractor control device.

1 is a block diagram illustrating a configuration of a seat belt retractor control device according to an embodiment of the present invention and a seat belt retractor that is a control target thereof. It is a state transition diagram of the seatbelt retractor control device according to one embodiment of the present invention. FIG. 3 is a diagram showing a correspondence between a time-series change in a belt withdrawal amount detected by a belt withdrawal amount detection circuit shown in FIG. 1 and each operation state shown in FIG. 2.

  Embodiments of the present invention will be described below with reference to the drawings.

  In this embodiment, the present invention is applied to a seat belt retractor control device that controls a seat belt retractor mounted on a vehicle (particularly an automobile).

  FIG. 1 is a block diagram illustrating a configuration of a seat belt retractor control device according to the present embodiment and a seat belt retractor that is a control target thereof.

  As shown in FIG. 1, the seat belt retractor 200 rotates the spool 201, a spool 201 that winds up the seat belt 301, a spring (not shown) that urges the spool 201 to rotate in the winding direction, and the spool 201. A motor 202 as an electric winding device that generates driving torque, a clutch (not shown) provided between the gear of the spool 201 and the gear of the motor 202, and a motor driving circuit 203 that drives the motor 202 And a belt withdrawal amount detection circuit 204 that detects the length of the portion of the seat belt 301 that is pulled out from the spool 201 (hereinafter referred to as “belt withdrawal amount”), and the withdrawal of the seat belt 301 is mechanically disabled. ALR lock mechanism 205 capable of

  In the seat belt retractor 200 including the motor 202 as such an electric winding device, the clutch between the gear of the motor 202 and the gear of the spool 201 is engaged by rotating the motor 202 forward or backward by a certain amount. It can be fastened (ON) or shut off (OFF). In a normal state where the clutch is disengaged, the seat belt 301 can be pulled out manually. On the other hand, in a state where the clutch is engaged, the load of the motor 202 is applied to the spool 201, so that it is difficult to manually pull out the seat belt 301 and wind the seat belt 301 by a spring force.

  When the clutch is disengaged, the spool 201 rotates in the winding direction by a spring force, and when the clutch is engaged, the spool 201 rotates or pulls out by the driving torque of the motor 202 transmitted through the clutch. Rotate in the direction. With such a configuration, the seat belt retractor 200 can wind up the seat belt 301 using both the spring force and the driving torque of the motor 202.

  The ALR lock mechanism 205 operates when the seat belt 301 is pulled out to the maximum, and locks the seat belt 301. While the seat belt 301 is locked, only the winding of the seat belt 301 is allowed, and the seat belt 301 cannot be pulled out. When the seat belt 301 is completely wound, the lock is released and the seat belt 301 can be pulled out again.

  The motor drive circuit 203 operates in accordance with a control signal input from the seat belt retractor control device 100 and drives the motor 202.

  The belt withdrawal amount detection circuit 204 includes a rotation angle sensor (not shown) that detects the rotation angle of the spool 201, and calculates the belt withdrawal amount based on the rotation angle of the spool 201 detected by the rotation angle sensor. It is configured. The configuration of the belt withdrawal amount detection circuit 204 is not limited to this, and includes a spool sensor (not shown) that detects the rotational speed of the spool 201, and the belt withdrawal amount detection circuit 204 is based on the rotational speed of the spool 201 detected by the spool sensor. You may comprise so that quantity may be calculated.

  The seat belt retractor control device 100 that controls the seat belt retractor 200 configured as described above includes an MPU (Micro-Processing Unit) 101, an input circuit 103, and an output circuit 104.

  A signal indicating the operation state (ON / OFF) of the ignition switch 302 is input from the ignition switch 302 to the input circuit 103, and a signal indicating the operation state (ON / OFF) of the buckle switch 303 is input from the buckle switch 303 to the input circuit 103. A signal indicating the operation state (ON / OFF) of the ALR lock mechanism 205 (hereinafter referred to as “ALR lock mechanism operation signal”) is input from the ALR lock mechanism 205, and a signal indicating the belt extraction amount is output from the belt extraction amount detection circuit 204. A signal indicating the driving state of the motor 202 is input from the motor 202, and various signals are input from the vehicle ECU 304 via a communication network provided in the vehicle. Various signals input from the vehicle ECU 304 include vehicle information such as vehicle speed and steering angle, as well as operation information of various switches provided around the driver's seat.

  The input circuit 103 transmits a signal input from each device to the MPU 101. Further, the input circuit 103 changes the seat belt retractor control device 100 from the standby state to the operating state in response to an input signal from the ignition switch 302, an input signal from the buckle switch 303, and an input signal from the ALR lock mechanism 205 (or It has a function to make a transition from an operating state to a standby state. Here, the standby state is a state in which the MPU 101 is not activated and the motor drive circuit 203 cannot be controlled, and the operating state is a state in which the MPU 101 is activated and the motor drive circuit 203 can be controlled.

  The MPU 101 calculates a control amount for controlling the motor drive circuit 203 based on each signal input from the input circuit 103 when the seatbelt retractor control device 100 is in an operating state, and outputs the result to the output circuit 104. Send to.

  The output circuit 104 converts the control amount received from the MPU 101 into a control signal for the motor drive circuit 203 and outputs the control signal to the motor drive circuit 203.

  The MPU 101 realizes the functions described below by executing a program stored in the ROM 102 when the seatbelt retractor control device 100 is in an operating state.

  FIG. 2 is a state transition diagram of the seat belt retractor control device 100.

  As shown in FIG. 2, the seat belt retractor control device 100 in the standby state X transitions to a different operation state (an operation state A or B described later) according to the activation condition of the MPU 101.

  In the standby state X, when the MPU 101 is triggered by the switching of the ignition switch 302 or the switching of the buckle switch 303, a transition is made to the operating state A (path 401). At this time, since the ALR lock mechanism 205 is not operated, the seat belt 301 can be pulled out as usual. Further, since the clutch between the gear of the spool 201 and the gear of the motor 202 is not fastened, the seat belt 301 can be wound by the spring force. In the operation state A, the MPU 101 recognizes that the seat belt 301 can be pulled out (ALR function is OFF) and the seat belt 301 can be wound up (clutch is OFF). When it is necessary to store the seat belt 301 or remove slack, the seat belt 301 is wound up by driving the motor 202 in the operating state A.

  In the operation state A, when the belt withdrawal amount is equal to or greater than the ALR function ON threshold value or when the ALR lock mechanism operation signal is turned ON, the state is changed to the operation state B (path 402). Here, the ALR function ON threshold value is a value stored in advance in the ROM 102, and is set to a value approximately equal to the belt withdrawal amount when the ALR lock mechanism 205 operates. In the operation state B, the MPU 101 recognizes that the seat belt 301 cannot be pulled out (ALR function is ON) and that the seat belt 301 can be wound up (clutch is OFF).

  In the operation state B, when the belt withdrawal amount falls below the clutch ON threshold, the operation state C is changed (path 404). Here, the clutch ON threshold value (third threshold value) is a value stored in advance in the ROM 102, and is a value (first threshold value) corresponding to the belt pull-out amount when the seat belt 301 is completely pulled out. And a value larger than a value (second threshold) corresponding to the belt withdrawal amount in a state where the seat belt 301 is completely wound (desirably, an occupant can easily get through the seat belt 301 easily). It is set to a value corresponding to the possible belt withdrawal amount). When the seat belt 301 is retracted by a certain amount in a state where the seat belt 301 is locked (when the ALR function is ON) (when the belt withdrawal amount falls below the clutch ON threshold), the seat belt retractor control device 100 Is rotated for a predetermined time, and the clutch between the gear of the spool 201 and the gear of the motor 202 is engaged. Thereby, the rotation of the spool 201 in the winding direction due to the spring force is prevented by the load of the motor 202, and the winding of the seat belt 301 is restricted. In the operation state C, the MPU 101 recognizes that the seat belt 301 cannot be pulled out (ALR function is ON) and that the seat belt 301 is restricted to be retracted (the clutch is ON).

  In the operation state C, the seat belt 301 is wound only when the passenger intends to do so. When the seat belt 301 is wound up, the occupant operates, for example, a switch provided around the driver's seat (for example, an instrument panel). When the MPU 101 detects the operation of the switch via the vehicle ECU 304 and the input circuit 103, the MPU 101 controls the motor 202 via the motor drive circuit 203, rotates the spool 201 in the winding direction, and winds up the seat belt 301.

  In the operation state B, when the belt pull-out amount is smaller than the ALR function ON threshold and the seat belt 301 is pulled out, the operation state A is changed. Originally, the seat belt 301 cannot be pulled out while the ALR lock mechanism 205 is operating. However, it is also assumed that the ALR lock mechanism 205 is not operating in the operating state B (the ALR function is not ON). The transition from the operation state B to the operation state A enables the MPU 101 to correctly recognize the operation state of the ALR lock mechanism 205.

  In the operating state C, when the belt withdrawal amount falls below the ALR function OFF threshold, the state transits to the operating state A. Here, the ALR function OFF threshold value is a value stored in advance in the ROM 102, and is set to a value corresponding to the belt withdrawal amount when the seat belt 301 is completely wound. When the seat belt 301 is completely wound by driving the motor, the lock by the ALR lock mechanism 205 is released (the ALR function is turned off), and the seat belt 301 can be pulled out. Further, by disengaging (OFF) the clutch between the gear of the spool 201 and the gear of the motor 202, the seat belt 301 can be wound by the spring force.

  On the other hand, in the standby state X, when the MPU 101 is triggered by the switching of the ALR lock mechanism operation signal from OFF to ON, the state transitions to the operation state B (path 406). At this time, the MPU 101 recognizes that the seat belt 301 can be pulled out (ALR function is OFF) and the seat belt 301 can be wound up (clutch is OFF). Since the transition from the operating state B to the operating states A and C or the standby state X is as described above, the description thereof is omitted here.

  In each of the operation states A to C, when the ignition switch 302 is OFF and the seat belt 301 attachment / detachment operation (switching operation of the buckle switch 303) is not performed for a certain period of time, the state transits to the standby state X. Thereby, battery consumption can be suppressed.

  FIG. 3 is a diagram showing the correspondence between the time-series change of the belt withdrawal amount detected by the belt withdrawal amount detection circuit 204 shown in FIG. 1 and each operation state shown in FIG.

  In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates the amount by which the seat belt 301 is pulled out. Note that the origin of the time axis is the time when the MPU 101 is activated (transition from the standby state X to the operating state A) triggered by the switching of the ignition switch 302 or the switching of the buckle switch 303.

  In the operating state A (section 501) immediately after the MPU 101 is activated, the MPU 101 recognizes that the seat belt 301 can be pulled out (ALR function is OFF) and that the seat belt 301 can be taken up (clutch is OFF). .

  In the section 501 (operation state A), when the seat belt 301 is pulled out and the belt withdrawal amount becomes equal to or greater than the ALR function ON threshold, the state transitions to the operation state B (section 502) (path 402 in FIG. 2). In the section 502 (operation state B), the MPU 101 recognizes that the seat belt 301 cannot be pulled out (ALR function is ON) and that the seat belt 301 can be wound up (clutch is OFF). In the example shown in FIG. 3, since the ALR function ON threshold is set to a value smaller than the value (first threshold) corresponding to the belt withdrawal amount when the ALR function is ON, the section 502 (operation state B) Then, the ALR lock mechanism 205 is not actually operated, and the seat belt 301 can be pulled out continuously.

  When the seat belt 301 is pulled out in the section 502 (operation state B), the state transitions to the operation state A (section 503) (path 403 in FIG. 2). In the section 503 (operation state A), the MPU 101 recognizes that the seat belt 301 can be pulled out (ALR function is OFF) and the seat belt 301 can be wound up (clutch is OFF).

  In the section 503 (operating state A), the seat belt 301 is pulled out again, and when the belt withdrawing amount exceeds the ALR function ON threshold, the state transitions to the operating state B (section 504) (path 402 in FIG. 2). In the section 504 (operation state B), the MPU 101 recognizes that the seat belt 301 cannot be pulled out (ALR function is ON) and that the seat belt 301 can be wound up (clutch is OFF).

  In the section 504 (operation state B), the seat belt 301 is continuously pulled out, and if the belt pull-out amount exceeds the belt pull-out amount when the ALR mechanism is ON, the ALR lock mechanism 205 actually operates and the seat belt 301 cannot be pulled out. (Section 505).

  In a section 505 (operation state B), when the seat belt 301 is wound by a certain amount by the spring force, a clutch between the gear of the spool 201 and the gear of the motor 202 is engaged, and the winding of the seat belt 301 is restricted. The The seat belt retractor control device 100 transitions to the operation state C (section 506) when the belt withdrawal amount falls below the clutch ON threshold (path 404 in FIG. 2). In the section 506 (operation state C), the MPU 101 recognizes that the seat belt 301 cannot be pulled out (ALR function is ON) and that the seat belt 301 is restricted from being wound (the clutch is ON).

  In the section 506 (operation state C), when the seat belt 301 is completely wound by the motor drive, the lock by the ALR lock mechanism 205 is released and the clutch is disengaged. The seat belt retractor control device 100 transitions to the operation state A (section 507) when the belt withdrawal amount falls below the ALR function OFF threshold (path 405 in FIG. 2). In the section 507 (operation state A), the MPU 101 recognizes that the seat belt 301 can be pulled out (ALR function is OFF) and the seat belt 301 can be wound up (clutch is OFF).

  According to the seat belt retractor control device 100 according to the present embodiment, when the seat belt 301 is wound by a certain amount by the spring force in a state where the seat belt 301 is locked by the ALR lock mechanism 205 (the belt withdrawal amount is the clutch ON). When the value falls below the threshold value, the clutch between the gear of the spool 201 and the gear of the motor 202 is engaged, and the load of the motor 202 acts on the spool 201 against the spring force. As a result, the seat belt 301 cannot be wound unless the motor 202 is driven by an occupant's intentional operation, and therefore it is possible to prevent the seat belt 301 from being unwound by the occupant.

  Since the MPU 101 does not need to monitor the amount of belt withdrawal before the seat belt 301 is locked by the ALR lock mechanism 205, the seat belt 301 can be attached / detached (the switching operation of the buckle switch 303) with the ignition switch 302 turned off. ) Is not performed for a certain period of time, the MPU 101 is stopped (transition from the operation state A to C to the standby state X), the ignition switch 302 is switched, the buckle switch 303 is switched, or the ALR lock mechanism activation signal is turned OFF to ON. It becomes possible to start the MPU 101 (transition from the standby state X to the operating state A or B) using the switching to the trigger. As a result, the frequency with which the MPU 101 is activated in a state where the ignition switch is OFF can be suppressed, so that battery consumption can be suppressed.

  As mentioned above, although one Example of this invention was explained in full detail, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

  DESCRIPTION OF SYMBOLS 100 ... Seat belt retractor control apparatus, 101 ... MPU, 102 ... ROM, 103 ... Input circuit, 104 ... Output circuit, 200 ... Seat belt retractor, 201 ... Spool, 202 ... Motor, 203 ... Motor drive circuit, 204 ... Belt withdrawal Quantity detection circuit, 205 ... ALR lock mechanism, 301 ... Seat belt, 302 ... Ignition switch, 303 ... Buckle switch, 304 ... Vehicle ECU.

Claims (2)

A spool that winds up the seat belt;
A spring that biases the spool to rotate in the winding direction;
A motor for generating a driving torque for rotating the spool;
A clutch provided between the spool gear and the motor gear;
A motor drive circuit for driving the motor;
A belt withdrawal amount detection circuit for detecting a belt withdrawal amount of the seat belt;
An ALR lock mechanism that mechanically disables the withdrawal of the seat belt until the belt withdrawal amount falls below a second threshold value that is smaller than the first threshold value after the belt withdrawal amount exceeds a first threshold value. In a seat belt retractor control device for controlling a seat belt retractor provided,
In a state in which the seat belt cannot be pulled out by the ALR lock mechanism, a third threshold value in which the belt pull-out amount is set to a value smaller than the first threshold value and larger than the second threshold value is set. The seatbelt retractor control device according to claim 1, wherein the clutch is engaged by driving a constant amount of the motor when the speed falls below, and a load of the motor is applied to the spool. In the seatbelt retractor control device according to claim 1,
The motor drive circuit is configured to be able to transition between an operation state in which the motor drive circuit can be controlled and a standby state in which the motor drive circuit cannot be controlled,
The seat belt retractor control device according to claim 1, wherein when the operation of the ALR lock mechanism is detected, the operation state is changed from the standby state to the operation state.

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