JP5797229B2 - Seat belt device - Google Patents

Description

  The present invention relates to a seat belt device.

  For example, Patent Literature 1 discloses a technique for appropriately performing belt tension according to movement of an occupant's body. According to Patent Document 1, the motor control unit changes the motor drive current in an increasing direction when the acceleration detected by the sensor is equal to or less than a predetermined value and when the webbing pull-out amount is detected. Let On the other hand, when the acceleration detected by the sensor is equal to or less than the predetermined value and the amount of winding is detected, the motor drive current is controlled to change in the decreasing direction. This eliminates the uncomfortable feeling given to the passengers.

JP 2012-96685 A

  However, according to the technique disclosed in Patent Document 1, in order to reflect the movement of the occupant's body in the control of the belt tension, it is necessary to detect the pull-out amount in addition to the webbing winding amount. Therefore, the algorithm for controlling the tension of the seat belt is complicated, and there is a problem that the processing load is large in an inexpensive CPU.

  Further, according to the technique disclosed in Patent Document 1, the driving current is increased as the occupant moving speed is increased. Therefore, the seat belt is unnecessarily wound when the occupant is held, and as a result, the passenger feels uncomfortable or uncomfortable. There was a fear of giving.

  The present invention has been made in order to solve the above-described problems, and it is possible to reflect the movement of the occupant's body in the tension control of the seat belt with a simple algorithm without detecting the amount of withdrawal, and to give the passenger a sense of incongruity or discomfort An object of the present invention is to provide a seat belt device that eliminates the problem.

  According to the first aspect of the present invention, at least one of the forward acceleration, the leftward acceleration, and the rightward acceleration of the vehicle is detected by the acceleration detection unit that detects the acceleration of the vehicle, the motor that winds up the seat belt, and the acceleration detection unit. A control unit that controls the motor so as to generate a winding tension of the seat belt only when the first combined acceleration by the two is greater than or equal to a first predetermined value, and the control unit includes: The seat belt device is characterized in that the motor is controlled so that the winding tension of the seat belt is reduced as the first combined acceleration that is equal to or greater than a first predetermined value is greater.

According to a second aspect of the present invention, in the seat belt device according to the first aspect, the control unit causes the acceleration detection unit to perform the front acceleration, the rear acceleration, the left acceleration, and the right acceleration of the vehicle. The control of the motor is stopped when the second combined acceleration by at least one of the following is less than a second predetermined value smaller than the first predetermined value.

  According to the present invention, it is possible to provide a seatbelt device that eliminates discomfort and discomfort given to the occupant by reflecting the movement of the occupant's body in the control of the belt tension with a simple algorithm without detecting the amount of withdrawal. .

It is a side view which shows the mounting state of the seatbelt apparatus in a vehicle. It is a figure which shows the principal part structure of the retractor of the seatbelt apparatus which concerns on embodiment of this invention. It is a disassembled perspective view which shows an example of a concrete mechanical structure of a retractor provided with a locking mechanism. It is a block diagram which shows the structure of the control system of the seatbelt apparatus which concerns on embodiment of this invention. It is the figure which mapped and showed on the acceleration coordinate space the action | operation and non-operation area | region of the seatbelt apparatus which concerns on embodiment of this invention. It is the figure quoted in order to demonstrate a passenger | crew's movement at the time of sudden braking. It is the figure which displayed the winding driving | running | working data on the graph. It is a flowchart which shows operation | movement of the seatbelt apparatus which concerns on embodiment of this invention.

  Hereinafter, a seat belt device according to an embodiment of the present invention (hereinafter simply referred to as the present embodiment) will be described in detail with reference to the drawings.

(Configuration of the embodiment)
In FIG. 1, a seat belt device 10 includes a belt (webbing) 13 that restrains the body of an occupant 11 to a seat 12. The belt 13 includes a belt portion 13 a that restrains the upper body of the occupant 11 and a belt portion 13 b that restrains the waist of the occupant 11. One end of the belt portion 13b is fixed to the vehicle body portion at the lower part of the passenger compartment by an anchor plate 14. The belt portion 13 a is folded back by a through anchor 15 provided at a location near the shoulder of the occupant 11, and an end portion thereof is connected to a belt reel of the retractor 16. A tongue plate 17 is attached to the other common end (folded portion) of the belt 13. The tongue plate 17 is detachably attached to a buckle 18 fixed to the lower edge of the seat 12. The buckle 18 is provided with a buckle switch 19 that detects the connection of the tongue plate 17.

  FIG. 2 schematically shows a main configuration of the seat belt retractor 16. The retractor 16 includes a belt reel (spindle) 22 that is rotatably provided in the housing 21 and a motor 23 that rotationally drives the belt reel 22. The belt reel 22 is coupled to the end of the belt portion 13 a of the belt 13, and the belt portion 13 a is wound around the belt reel 22. A winding spring 202 is attached to the left end of the shaft 22a of the belt reel 22 in FIG. The internal structure of the winding spring portion 202 will be described in detail later. Further, the shaft 22 a of the belt reel 22 is connected to the drive shaft 23 a of the motor 23 via a power transmission mechanism (gear mechanism) 24. The belt reel 22 is rotationally driven by a motor 23 via a power transmission mechanism 24. The retractor 16 includes a winding position detector 25 connected to the shaft 22a of the belt reel 22.

  The winding position detection unit 25 is preferably configured using a rotation angle sensor. For example, a magnetic sensor formed by combining a magnetic disk and two Hall ICs is used as the rotation angle sensor. The minimum resolution angle of the rotation angle sensor is, for example, 4 °, and is about 1.3 to 1.6 mm when converted into the belt length. As the winding position detection unit 25, a belt length sensor can be used instead of the rotation angle sensor.

  The winding position detection unit 25 detects the belt winding position by the belt reel 22 by detecting the rotation angle of the belt reel 22 with a rotation angle sensor. A detection signal output from the winding position detection unit 25 is input to the control device 30. In order to finally extract the winding position data using the winding position detection information given from the winding position detection unit 25, a calculation process in the control device 30 is required. The operation of the retractor 16 is controlled by the control device 30. The control device 30 controls the operation of the retractor 16 by controlling the energization amount of the drive current I <b> 1 supplied from the power source 27 to the motor 23 by the energization amount adjustment unit 28. The retractor 16 controlled by the control device 30 is configured as an electric pretensioner for maintaining the posture of the occupant 11. The occupant 11 who gets on the seat 12 is protected and restrained by the belt 13 in the event of an emergency of the vehicle or when the running state is unstable, and changes in posture and position are suppressed, and the desired safe state is maintained.

  Further, in the retractor 16 for the seat belt, the other end portion (the right end portion in FIG. 2) opposite to the shaft 22a of the belt reel 22 has an abrupt portion of the belt portion 13a of the belt 13 when an emergency of vehicle traveling occurs. A lock mechanism 100 is attached to prevent the pull out. The case where an emergency situation of vehicle travel occurs is a case where a predetermined inclination acts on the vehicle body or a predetermined acceleration (deceleration acceleration) acts on the vehicle body due to a collision or sudden braking. . The locking mechanism 100 is a well-known device. The lock mechanism 100 is generally composed of a mechanism main body 101 and a vehicle sensor (V / S) 102.

  The mechanism main body 101 includes a ratchet wheel that is coupled to the shaft 22a and is rotatable in conjunction with the shaft 22a, a frame gear fixed to the housing frame, and a change in position. And a locking element that engages or disengages from the frame gear.

  The vehicle sensor 102 includes a ball element (weight) and a lever element (lock arm) in a sensor frame (sensor case). When acceleration occurs in the vehicle body, the ball element changes its position in response to the acceleration and operates the lever element. The lever element has a function of making an engagement state with the outer claw of the ratchet wheel.

  In the lock mechanism 100 described above, the locking element and the frame gear are not engaged in a normal state, and both are engaged in a locked state. Similarly, the outer peripheral claw of the ratchet wheel and the lever element of the vehicle sensor 102 are not engaged in the normal state, and both are engaged in the locked state.

  In the locking mechanism 100, the locking condition (in accordance with the regulations) by the vehicle sensor 102 is, for example, “locking at 50 mm or less or an arbitrary two-direction 27 ° inclination” at 0.45 G, and “25 mm or less at 0.7 G”. To lock in. " In addition, due to the variation in the mechanism, the conditions under which the vehicle sensor 102 can be unlocked have individual differences of about ± 5 mm in terms of the belt winding amount.

  FIG. 3 shows an example of a specific mechanical structure of the retractor 16 including the lock mechanism 100. The retractor 16 that winds up the belt 13 (belt portion 13a in FIG. 3) includes a winding mechanism 201 that adjusts the length of the belt 13 according to the physique of the occupant 11, and a winding that is attached to the left side of the winding mechanism 201. The spring part 202 and the locking mechanism 100 described above are provided.

  The winding mechanism 201 includes the belt reel 22 as a core member and a base frame 203 that rotatably supports the belt reel 22. The belt portion 13 a (belt 13) is wound around the belt reel 22.

  The lock mechanism 100 performs a lock operation when a predetermined acceleration (deceleration acceleration) is applied to the vehicle or when the drawing speed of the belt 13 exceeds a predetermined value. The lock mechanism 100 includes two lock operation mechanisms 100A and 100B that generate a lock state. The lock operating mechanism 100A is a mechanism that senses a predetermined acceleration. The lock actuating mechanism 100B is a mechanism that senses belt withdrawal due to a withdrawal speed exceeding a predetermined value. Reference numeral 204 denotes a retainer that is attached in a fixed state and forms an outer case.

  As described above, in FIG. 2, the lock mechanism 100 includes the mechanism main body 101 and the vehicle sensor 102. The two lock operating mechanisms 100 </ b> A and 100 </ b> B are mechanisms provided inside the mechanism main body 101. Furthermore, the lock operation mechanism 100A is a mechanism that operates based on the sensitive operation of the vehicle sensor 102. The lock operating mechanism 100B is a mechanism that is incorporated in advance in the mechanism main body 101.

  The winding spring portion 202 includes a spiral spring 211 for winding the belt 13, a bush 212 to which the inner end of the spiral spring 211 is attached and connected to the winding mechanism, and the spiral spring 211 and the spiral spring. A spring case 213 to which the outer end portion 211 is attached and a cover 214 that covers the spring case 213 are configured. The bush 212 has a square hole 212 a of the shaft 22 a of the belt reel 22 of the winding mechanism 201.

  The lock operation mechanism 100A that performs a lock operation by sensing acceleration is a lock operation mechanism that operates when the acceleration of the vehicle exceeds a set value. The lock operation mechanism 100A includes a vehicle sensor (acceleration detection means) 102 that operates when the vehicle acceleration exceeds a set value, and a ratchet wheel (lock gear) that is rotatably provided in conjunction with the shaft 22a of the belt reel 22. 222. When the vehicle sensor 102 senses acceleration and operates, the lock arm 221 operates and engages with the outer peripheral claw 222 a of the ratchet wheel 222. When the lock arm 221 is locked to the ratchet wheel 222, the lock arm 221 is locked, and the belt reel 22 is prevented from rotating in the belt drawing direction.

  The vehicle sensor 102 is rotatable via a pin 234 to a sensor frame 231 attached to the right side portion of the base frame 203 of the winding mechanism 201, a weight 232 disposed on the sensor frame 231, and a column 233 of the sensor frame 231. The lock arm 221 is attached. When acceleration occurs in the vehicle body, the weight 232 changes its position in response to the acceleration and operates the lock arm 221. The lock arm 221 is engaged with the outer peripheral claw 222 a of the ratchet wheel 222.

  The lock actuating mechanism 100B that operates by sensing belt withdrawal includes a drawer sensing means 241 that operates when the withdrawal speed of the belt portion 13a in the withdrawal direction (arrow direction) exceeds a predetermined value. The drawer sensing means 241 has an inertial body (flywheel) 242. When the drawer sensing means 241 performs an operation of sensing belt withdrawal exceeding a predetermined value, the lock claw 243 of the inertial body 242 is moved to an inner circumferential claw (not shown in FIG. 3) formed on the inner circumferential surface of the retainer 204. Locked. When the lock claw 243 of the inertial body 242 is engaged with the inner circumferential claw of the retainer 204, the lock reel 243 is locked, and the belt reel 22 is prevented from rotating in the belt drawing direction.

  The drawer sensing means 241 includes the inertia body 242 that is rotatably attached to an eccentric shaft 244 that is offset from the center of the ratchet wheel 222, a lock claw 243 formed at one end of the inertia body 242, and an upper side of the lock claw 243. An upper stopper 245 and a lower stopper 246 provided on the ratchet wheel 222 disposed on the lower side, a stopper 247 provided in the ratchet wheel 222 below the inertial body 242, and between the stopper 247 and the inertial body 242 And a coil spring 248 that pushes the inertial body 242 disposed in the counterclockwise direction.

  When the drawing speed of the belt 13 in the drawing direction exceeds a predetermined value, the ratchet wheel 222 interlocked with the shaft 22a of the belt reel 22 suddenly rotates counterclockwise around the rotating shaft 222b. At this time, the inertial body 242 causes inertial delay and swings relative to the ratchet wheel 222 about the shaft 244. When the ratchet wheel 222 further rotates in this state, the upper stopper 245 hits the lock claw 243 of the inertial body 242 and the inertial body 242 rotates. When the ratchet wheel 222 continues to rotate, the lock claw 243 of the inertial body 242 hits the inner peripheral claw of the retainer 203, and the ratchet wheel 222 is locked.

  The seat belt device 10 and the retractor 16 and the like having the above configuration are devices on the driver's seat side, but the same seat belt device and retractor are also provided on the passenger seat side.

  FIG. 4 shows the internal configuration of the electrical system of the seat belt device 1 including the control device 30 according to the present embodiment. As shown in FIG. 2, the seat belt device 1 according to the present embodiment includes a control device 30 and an acceleration detection unit 40, and these blocks are connected to the control device 30 via a CAN (Controller Area Network) bus 50. Connected.

  The acceleration detection unit 40 includes a front / rear G detection unit 41 and a lateral G detection unit 42. The front / rear G detection unit 41 detects acceleration generated during acceleration and braking of the vehicle, and the lateral G detection unit 42 detects acceleration generated during left turn and right turn, and outputs the detected acceleration to the control device 30.

  The control device 30 includes a control unit 31 and a motor drive control unit 32. The control part 31 has memorize | stored the acceleration coordinate space threshold value map 33 which prescribes | regulates the operation | movement for tension | tensile_strength provision. The acceleration coordinate space threshold map 33 is made up of an acceleration coordinate space, for example, as shown in FIGS. In this acceleration coordinate space, the longitudinal acceleration (Y axis) is set in the longitudinal direction of the vehicle, and the horizontal axis (X axis) is set in the lateral direction of the vehicle. The upward direction (+ Y direction) of the vertical axis is the deceleration (negative acceleration) generated when the vehicle is braked (decelerated), and conversely, the downward direction (−Y direction) of the vertical axis is the acceleration generated when the vehicle is accelerated. And Further, the right direction of the horizontal axis (+ X direction) is the acceleration generated when the vehicle turns left, that is, the right acceleration of the vehicle, and conversely, the left direction of the horizontal axis (−X direction) occurs when the vehicle turns left. The acceleration, that is, the vehicle left acceleration.

  On this acceleration coordinate space, a threshold value for defining an operation region in which tension is applied to the belt 13 and a non-operation region in which tension is not applied to the belt 13 without being operated is indicated by a circle. In addition, in the first quadrant and the second quadrant, the region outside the circle is the operation region. Note that. The hatched area in FIG. 5 (a) is the combined acceleration operating area (threshold is 0.35G or more) when tension is applied, and the hatched area in FIG. 5 (b) is the combined acceleration operating when the motor 23 is stopped. Region (threshold is less than 0.25G).

  The control unit 31 is constituted by, for example, a microprocessor (CPU) including a memory, and is based on a program recorded in a built-in or external memory and an acceleration space threshold map 33 via the motor drive control unit 32. Thus, the motor 23 of the retractor 16 is controlled. In other words, the control unit 31 uses the acceleration coordinate space threshold map 33 (FIG. 5A) to cause the acceleration detection unit 40 to perform the first operation based on at least one of the forward acceleration, the leftward acceleration, and the rightward acceleration of the vehicle. When the combined acceleration is equal to or higher than a first predetermined value (3.5 G described later), the motor 23 is controlled so as to generate the tension of the belt 13. At this time, the control unit 31 is configured to control the motor 23 so that the tension of the belt 13 is reduced as the combined G that is equal to or greater than the predetermined value is larger.

  In addition, the control unit 31 uses the acceleration detection unit 40 according to the acceleration coordinate space threshold map 33 (FIG. 5B) to determine at least one of the vehicle front acceleration, the rear acceleration, the left acceleration, and the right acceleration. When the second combined acceleration is less than a second predetermined value (0.25 G described later), the control of the motor 23 is stopped.

  When the motor drive control unit 32 receives a motor drive request, a motor reverse rotation request, or a motor stop request from the control unit 31, the motor drive control unit 32 controls to drive the motor 23 of the seat belt retractor 16 to reversely rotate or stop. The motor drive control unit 32 is configured by, for example, a three-phase bridge circuit.

(Operation of the embodiment)
Hereinafter, the operation of the seat belt device 1 according to the present embodiment will be described in detail. For example, as shown in FIG. 6, the seatbelt device 1 according to the present embodiment suppresses the winding of the belt 13 by the motor 23 in an area where acceleration of a certain level or more is applied during braking. The occupant who is seated and tightened the belt 13 is moved forward and left and right as the steering direction to intentionally lean on the belt 13, and the slack of the belt 13 is removed using the force. .

  As described above, when the occupant performs the movement indicated by the arrow in the drawing as a result of winding, the belt 13 gradually disappears and the belt 13 is wound and restrained as shown in FIG. . In FIG. 7, the time axis [s] is plotted on the horizontal axis, and the generated G is scaled on the vertical axis, and the movements of the front and rear, right and left G and the belt 13 are indicated by numerals. For example, the front, rear, left, and right G are generated G when x0.01 is performed on the vertical axis. According to FIG. 7, it can be understood that the belt 13 is tightened by about 15 [mm] as indicated by the number of pulses of the movement of the belt 13.

  Hereinafter, the operation of the seat belt device 1 of FIG. 4 will be described in detail with reference to the flowchart of FIG.

  The control device 30 (control unit 31) starts operation when an ignition switch (not shown) is turned on. First, in the acceleration detection unit 40, the front-rear G detection unit 41 detects the acceleration in the front-rear direction of the vehicle (front-rear G), and the lateral G detection unit 42 detects the left-right acceleration (lateral G) that is the steering direction. Next, the control unit 31 acquires the vehicle front-rear G and lateral G detected by the acceleration detection unit 40 via the CAN bus 20. Subsequently, the control unit 31 obtains the composite G by calculation, and compares it with the threshold according to the acceleration space threshold map 33 shown in FIG.

  Specifically, the control unit 31 first obtains a combined G (first combined acceleration) of the front G and the lateral G of the vehicle, which is acquired from the acceleration detection unit 40 via the CAN bus 50 during the deceleration and obtained by calculation. , 0.35 or more and less than 0.45 (0.35 to 0.45) is determined (step S101). Here, if the composite G is included in 0.35 to 0.45 (step S101 “YES”), the control unit 31 sends 4 [A] to the motor 23 of the retractor 16 with respect to the motor drive control unit 32. A winding tension application control is performed to instruct the flow of a relatively high drive current and to remove the slack of the belt 13 (step S102). This operation is repeatedly executed until the vehicle G becomes less than 0.25 (step S108 “YES”), whereby the belt 13 can be brought into close contact with the occupant, and the occupant can be held and controlled.

  It is assumed that when the vehicle G is 0.4, the lock mechanism 100 shown in FIG. 2 or FIG. 3 automatically operates, and there is no offset, and the vehicle G is released at 0.4. Since the lock mechanism 100 operates mechanically, it operates asynchronously with the control unit 31. Thereby, a passenger | crew can be protected from a sudden braking, a collision, etc.

  On the other hand, when the vehicle G is not in 0.35 to 0.4 (step S101 “NO”), the control unit 31 further determines whether or not the composite G is included in 0.45 to 0.55. (Step S103). Here, if the composite G is included in 0.45 to 0.55 (step S103 “YES”), the control unit 31 sends 2 [A] to the motor 23 of the retractor 16 with respect to the motor drive control unit 32. The belt 13 is instructed to pass the drive current to control the tension of the belt 13 (step S104). This operation is repeatedly executed until the vehicle G decreases to less than 0.25 (step S108 “YES”). In this way, for example, as shown in FIG. 6, the occupant can move back and forth, and right and left, so that the drawn belt 13 can be gradually loosened.

  On the other hand, when the vehicle G is not in the range of 0.45 to 0.55 (step S103 “NO”), the control unit 31 further determines whether or not the combined G is 0.55 or more (step S105). Here, when the composite G is 0.55 or more (step S105 “YES”), the occupant moves further back and forth and right and left and leans against the belt 13 as compared with the case where the composite G is 0.45 to 0.55. Therefore, the slack is eliminated by winding the belt 13 using this force. That is, in this region, in order to intentionally suppress the winding of the belt 13, the drive current output to the motor 23 is controlled to 1 [A] with respect to the motor drive circuit 12 (step S106). This operation is repeatedly executed until the vehicle G decreases to less than 0.25 (step S108 “YES”). As a matter of course, the lock mechanism 100 shown in FIG.

  On the other hand, when the composite G is not 0.55 or more (step S105 “NO”), the control unit 31 controls the motor drive circuit 12 so that the drive current output to the motor 23 is 0 [A]. Returning to the execution of the composite G determination process in step S101.

  After the winding tension control of the belt 13 by the driving current described above (steps S102, S104, S106, S107), the control unit 31 detects the acceleration by referring to the acceleration space threshold map 33 shown in FIG. It is determined whether the combined acceleration of the vertical G0 and the horizontal G detected by the unit 40 is less than 0.25 (step S108). Here, if it is less than 0.25 (step S108 “YES”), the control unit 31 outputs a reverse rotation operation request to the motor drive control unit 32, and the motor drive control unit 32 receiving the request outputs the reverse rotation operation request. The belt 13 is pulled out by controlling reverse rotation of the motor 23 of the retractor 16 (step S109), and the motor 23 is stopped when a predetermined amount is pulled out (step S110). If the composite G is 0.25 or more in step S108 (step S105 “YES”), the process returns to the vehicle G determination process in step S101, and the operations in steps S101 to S107 are repeated.

(Effect of embodiment)
As described above, the seat belt device 1 according to the present embodiment, for example, restrains the occupant in the forward direction and the occupant by restraining the winding of the belt 13 by the motor 23 intentionally in a region where acceleration of a certain level or more is applied during braking. The belt 13 is moved to the left and right to lean against the belt 13, and the slackness of the belt 13 is removed using the force. For this reason, the control unit 31 uses the acceleration detection unit 40 to set the first combined acceleration based on at least one of the forward acceleration, the leftward acceleration, and the rightward acceleration of the vehicle to the first predetermined value (for example, 0.35). In this case, the motor 23 is controlled so as to generate a winding tension on the belt 13. At this time, the motor 23 is controlled so as to reduce the winding tension of the seat belt as the first combined acceleration that is equal to or greater than the first predetermined value increases.

  For this reason, it is possible to reflect the movement of the occupant's body in the tension control of the seat belt with a simple algorithm without detecting the pull-out amount of the belt 13. Further, since the motor 23 is controlled so as to reduce the winding tension of the belt 13 as the resultant acceleration increases, the belt 13 is not unnecessarily wound up when holding the occupant. Restraint performance can be improved. Further, since the algorithm is simple, the control device 30 (the control unit 31) can be realized by an inexpensive CPU.

  Further, according to the seatbelt device 1 according to the present embodiment, the control unit 31 uses the acceleration detection unit 40 to perform the second operation based on at least one of the forward acceleration, the backward acceleration, the leftward acceleration, and the rightward acceleration of the vehicle. When the resultant acceleration is less than a second predetermined value (for example, 0.25), the control of the motor 23 is stopped. For this reason, the belt 13 is stopped when the belt 13 is pulled out by the reverse rotation of the motor 23 so that the belt 13 is not excessively tightened, the passenger is not discomforted, and the restraining performance of the belt 13 is improved. Can be made.

  DESCRIPTION OF SYMBOLS 1 ... Seat belt apparatus, 13 ... Belt, 16 ... Retractor, 23 ... Motor, 23 ... Control apparatus (31 ... Control part, 32 ... Motor drive control part, 33 ... Acceleration coordinate space threshold map), 40 ... Acceleration detection part ( 41... Front / rear G detection section, 42... Horizontal G detection section), 50... CAN bus, 100.

Claims (2)

An acceleration detector for detecting the acceleration of the vehicle;
A motor for winding the belt;
The belt detecting tension is generated by the acceleration detecting unit only when the first combined acceleration by at least one of the forward acceleration, the leftward acceleration, and the rightward acceleration of the vehicle is equal to or greater than a first predetermined value. A control unit for controlling the motor so as to
The controller is
The seat belt device according to claim 1, wherein the motor is controlled so that the winding tension of the belt decreases as the first combined acceleration that is equal to or greater than the first predetermined value increases. The controller is
A second predetermined acceleration by at least one of the forward acceleration, the backward acceleration, the leftward acceleration, and the rightward acceleration of the vehicle is less than the first predetermined value by the acceleration detection unit. 2. The seat belt device according to claim 1, wherein control of the motor is stopped when the value is less than the value .

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