JP6718268B2 - Vehicle occupant protection device - Google Patents

Description

The present invention relates to an occupant protection device for a vehicle such as an automobile.

Patent Documents 1 to 3 disclose a pre-tension mechanism that winds a strap that is stretched in front of an occupant sitting on a seat of an automobile before or during a collision. By the pre-tension operation, the back surface of the occupant seated on the seat is pressed against the backrest of the seat before or during the collision, and the occupant's posture can be corrected when the occupant moves forward due to the collision. As a result, the impact load at the time of a collision is likely to act on the occupant appropriately restrained by the straps, and it is expected that the occupant's protection performance at the time of a collision can be obtained.

JP, 10-167,000, A JP, 2000-142321, A JP, 2011-152837, A

However, in the pre-tension mechanism, the body is pressed against the seat by winding the strap to correct the posture of the occupant. Therefore, depending on the posture and body shape before the collision, the strap cannot be appropriately stretched over a desired part of the body, and the collision load may directly act on the body. For example, if you are better than normal, the straps may hang around your abdomen rather than in front of your chest. In addition, when the body size is small, the strap may pass in front of a part closer to the neck than the clavicle, not in front of the clavicle.

As described above, in the vehicle occupant protection device, it is required to increase the possibility that the collision load acts on the body of the occupant while the strap is appropriately stretched.

Occupant protection apparatus for a vehicle according to the present invention, a strap passed over before the body of the occupant seated on the seat of the vehicle, the pretensioner for winding the strap winding of the strap by said pretensioner before collision the has a control unit for starting the occupant condition sensor for detecting a constrained state of the occupant, wherein the control unit, after starting the winding of the strap, before the collision is detected by the occupant state sensor and so that a proper position in accordance with the restraint state of the occupant, to repeat the winding and loosening of the straps by the pretensioner, by the pretensioner in the event of a collision winding the strap.

Preferably, the occupant state sensor includes a belt tension sensor that detects a tension acting on the strap, and a belt winding sensor that detects a winding amount of the strap, and the control unit includes the belt tension sensor. The detection value of the sensor and the detection value of the belt winding sensor are set in a target range or a range of the target value based on the correspondence relationship between the belt winding amount corresponding to the chest displacement of the occupant and the belt tension. The winding and loosening of the strap with a tensioner may be repeated.

Preferably, the control unit controls the pretensioner so that the inclination of change in the detection value calculated from the detection value of the belt tension sensor and the detection value of the belt winding sensor is along a target inclination. The winding and loosening of the strap may be repeated.

Preferably, the control unit may repeat the winding and loosening of the strap by the pretensioner so that the detection value of the belt tension sensor does not exceed the steady maximum allowable belt tension.

Preferably, the control unit controls the winding and loosening of the strap by the pretensioner so that the detection value of the belt tension sensor does not exceed an instantaneous maximum allowable belt tension that is larger than the steady maximum allowable belt tension. Good to repeat.

Preferably, the controller winds and loosens the strap by the pretensioner so that the detection value of the belt tension sensor is maintained between a steady maximum allowable belt tension and a steady minimum allowable belt tension. Repeat and.

Preferably, the target range or the target value is set according to the body shape of the occupant.

Preferably, it has a traveling condition sensor for detecting the traveling condition of the vehicle, the control unit predicts the collision of the vehicle before the collision based on the detection of the traveling condition sensor, before the collision, The winding and loosening of the strap with a pretensioner may be repeated.

Suitably, it has a timer for measuring time, or an impact sensor for detecting the collision of the vehicle or the movement of the body due to the collision, and the control unit has an estimated time until the collision measured by the timer. Then, or when a collision is detected by the impact sensor, it is preferable to finish repeating the winding and loosening of the strap, and then wind the strap.

Preferably, the control unit sends out the strap so as to release the restraint state of the body with respect to the seat in the repeated control of winding and loosening the strap.

In the present invention, the strap is wound by the pretensioner before or at the time of collision. By pretensioning the occupant's body, the body can be supported by the impact load at the time of a collision. Moreover, in the present invention, after the strap is started to be wound, the strap is repeatedly wound and loosened before the collision. Therefore, the strap can be stretched around the body of the occupant who has been corrected in an appropriate position. Depending on the body shape and posture of the occupant, even if the strap cannot be wound at a proper position by winding the strap once, it can be solved. It is possible to increase the possibility that the collision load acts on the body of the occupant while the strap is appropriately stretched.
Further, in the present invention, by repeating the winding and loosening of the strap before the collision, even if the compression pressure acts on the body by the pre-tension operation before the collision, it can be reset and reduced before the collision. it can. The pressing pressure by the pre-tension and the pressing load by the deployed airbag are added to the contact portion of the strap as they are, and it becomes difficult to act. Moreover, even if an impact load due to a collision is applied thereafter, it is difficult to apply a force obtained by adding the compression pressure due to the pretension and the impact load at the time of collision to the contact portion of the strap.

FIG. 1 is an explanatory diagram of an automobile according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram of an example of a vehicle occupant protection device provided on the vehicle body of FIG. 1. FIG. 3 is an explanatory diagram of an example of an occupant protection operation performed by a general occupant protection device. FIG. 4 is a characteristic diagram showing an example of the correspondence between the belt tension and the belt winding amount corresponding to the chest displacement. FIG. 5 is a block diagram of a control system of the occupant protection system of FIG. FIG. 6 is a flowchart of occupant protection control by the control unit of FIG. FIG. 7 is an explanatory diagram of an example of an occupant protection operation under the control of FIG. FIG. 8 is a timing chart showing an example of strap winding control for fitting the strap to an occupant. FIG. 9 is a flowchart of occupant protection control according to the second embodiment. FIG. 10 is a flowchart of occupant protection control according to the third embodiment.

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

[First Embodiment]
FIG. 1 is an explanatory diagram of an automobile 1 according to a first embodiment of the present invention. The automobile 1 is an example of a vehicle. In addition to this, FIG. 1 shows another vehicle 1 traveling in front of the vehicle 1.

The automobile 1 in FIG. 1 has a vehicle body including a front compartment 2, a passenger compartment 3, and a rear compartment 4. A power unit such as an engine and an electric motor is arranged in the front chamber 2. A luggage space is provided in the rear chamber 4. The occupant room 3 is provided with a seat 5 on which an occupant who sits is seated. Further, operation members such as an accelerator pedal, a brake pedal, and a steering wheel are provided in front of the driver's seat 5 in the passenger compartment 3. The automobile 1 travels, stops, and makes a right/left turn based on a driver's operation.

FIG. 2 is an explanatory diagram of an example of a vehicle occupant protection device provided on the vehicle body of FIG. 1.

FIG. 2 shows a three-point seat belt device 10. The seat belt device 10 includes a strap 11, an anchor 12, a tongue plate 13, a buckle 14, a retractor device 15, and a holder 16.
The strap 11 is a belt that is laid around in front of the body of an occupant sitting on the seat 5.
The anchor 12 fixes the tip of the strap 11 at a position outside the seat surface of the seat 5.
The strap 11 is passed through the tongue plate 13.
The buckle 14 is fixed to a position inside the seat surface of the seat 5. The tongue plate 13 is detachably attached to the buckle 14.
The retractor device 15 includes a reel 17 that winds the strap 11, a motor 18 that drives the reel 17 to rotate forward and backward with an arbitrary torque, and a gas generator (not shown) that instantly rotates the reel 17 in the winding direction. Have. The motor 18 and the gas generator can function as a pretensioner that winds the strap 11 before the collision.
The retractor device 15 is provided at a position outside and below the seat 5, for example, below the B pillar.
The holder 16 is provided at a position outside and above the seat 5, such as an upper portion of the B pillar. The strap 11 is passed through the holder 16.
Then, the occupant seated on the seat 5 pulls the tongue plate 13 to pull out the strap 11 from the retractor device 15, and attaches the tongue plate 13 to the buckle 14. As a result, the strap 11 extends from the holder 16 toward the buckle 14, further extends from the buckle 14 toward the anchor 12, and is stretched around the waist and chest of the occupant seated on the seat 5.

FIG. 3 is an explanatory diagram of an example of an occupant protection operation performed by a general occupant protection device.
Before the collision, as shown in FIG. 3(A), the strap 11 of the seat belt device 10 is stretched around the occupant seated on the seat 5. At this point, the strap 11 may be loose and not constraining the occupant's body against the seat 5.
Next, for example, when a collision is expected, the pretensioner of the retractor device 15 is actuated and the strap 11 is wound up, as shown in FIG. 3(B). Thereby, the body of the occupant can be restrained so as to be pressed against the seat 5. Further, the retractor device 15 holds the strap 11 so as not to be drawn out with a torque equal to or lower than a predetermined value.
Next, when the vehicle body actually collides with another vehicle 1 shown in FIG. 1, for example, the body of the occupant seated on the seat 5 tries to move forward from the seat 5 as shown in FIG. 3(C). To do.

In this way, by the pre-tension operation before the collision, the back surface of the occupant seated on the seat 5 is pressed against the backrest of the seat 5 before or at the time of the collision. The posture of the occupant can be corrected when the occupant moves forward due to the collision. The impact load at the time of a collision is likely to act on the occupant appropriately restrained by the strap 11, and it can be expected that the occupant protection performance at the time of a collision can be obtained.
However, in the pretension mechanism, the body is pressed against the seat 5 by winding the strap 11 to correct the posture of the occupant. Therefore, depending on the posture and body shape before the collision, the strap 11 cannot be appropriately stretched over a desired part of the body, and the collision load may directly act on the body.
As described above, in the vehicle occupant protection device, it is required to increase the possibility that the collision load acts on the body of the occupant while the strap 11 is appropriately stretched.

FIG. 4 is a characteristic diagram showing an example of the correspondence between the belt tension and the belt winding amount.
The horizontal axis represents the belt tension, and the vertical axis represents the belt winding amount.
FIG. 4 shows a solid line showing a good relationship in which the strap 11 is stretched around the occupant at an appropriate position, and a broken line showing a bad relationship.
When the strap 11 is stretched around the occupant at an appropriate position, initially, the belt tension becomes large enough to wind the strap 11. When a proper restraining force is exerted on the occupant, the belt tension increases while the winding amount of the strap 11 remains unchanged.
On the other hand, in the case where the strap 11 is stretched around the abdomen, for example, even if the strap 11 is wound up, the belt tension tends not to change and the inclination in the figure becomes large.
In addition to this, for example, when the strap 11 is not properly stretched so as to pass through the shoulder, for example, the winding amount of the strap 11 continues to change forever.
Thus, the restraint state of the occupant by the strap 11 can be grasped to some extent by the correspondence between the belt tension and the belt winding amount.

FIG. 5 is a block diagram of a control system of the occupant protection system of FIG.

The control system of FIG. 5 includes an imaging device 21, a vehicle acceleration sensor 22, a vehicle speed sensor 23, a brake operation sensor 24, a vehicle angular velocity sensor 25, a belt tension sensor 26, a belt winding amount sensor 27, a seating sensor 28, a timer 29, and And a control unit 30 to which these are connected. Further, in FIG. 5, the seatbelt device 10 and the airbag device 35, which are connected to the control unit 30 and are control targets, are shown together.

The image pickup device 21 is, for example, a pair of image pickup elements, is provided on the roof of the passenger compartment 3 facing forward as shown in FIG. 1, and observes the surrounding situation in front of the vehicle by image pickup. The control unit 30 can identify an obstacle such as another automobile 1 in front of the vehicle as a surrounding condition of the vehicle from the captured image and determine the possibility of collision of the obstacle. Thereby, the traveling condition of the vehicle before the collision can be detected.

The vehicle acceleration sensor 22 is fixedly provided on the vehicle body and detects an acceleration acting on the vehicle as a running condition of the vehicle. Thereby, the deceleration of the vehicle before the collision can be detected. Further, since a large deceleration occurs at the time of a collision, a vehicle collision can be detected.

The vehicle speed sensor 23 is provided so as to be fixed to the vehicle body, and detects the speed of the vehicle as the traveling state of the vehicle.

The brake operation sensor 24 is provided in the passenger compartment 3 and detects the operation of depressing the brake pedal by the passenger. Thereby, the deceleration operation of the vehicle before the collision can be detected.

The vehicle angular velocity sensor 25 is provided so as to be fixed to the vehicle body, and detects the vehicle speed as the traveling state of the vehicle.

The belt tension sensor 26 is provided, for example, in the retractor device 15 and detects the tension acting on the strap 11. From this, it is possible to detect the movement of the body of the occupant who moves relatively forward during a rear-end collision, or the tension acting on the strap 11 due to the movement of the body.

The belt winding amount sensor 27 is provided, for example, in the retractor device 15 and detects the winding amount of the strap 11.

The seating sensor 28 is provided, for example, on the seating surface of the seat 5 and detects the seating of the occupant on the seat 5 and the seating position.

The timer 29 measures time.

The control unit 30 controls the occupant protection operation by the seat belt device 10 based on the detection signals of these sensors. For example, the control unit 30 performs the pre-collision control based on the collision prediction and the collision control based on the collision detection.

FIG. 6 is a flowchart of occupant protection control by the control unit 30 of FIG. The control unit 30 repeatedly executes the processing of FIG. 6 to control the winding of the strap 11 by the pretensioner.
FIG. 7 is an explanatory diagram of an example of an occupant protection operation under the control of FIG. Time flows in the order from FIG. 7(A) to FIG. 7(E). Then, the automobile 1 collides with another automobile 1 at the timing of FIG.

As shown in FIG. 6, the control unit 30 periodically determines the possibility of collision (step ST1). The control unit 30 may determine the possibility of a collision that is not easy to avoid.
For example, the control unit 30 identifies an obstacle such as another automobile 1 in front of the vehicle from the image in front of the vehicle captured by the image capturing device 21. When an obstacle is specified, the possibility of collision is determined. If there is a possibility of collision, predict the time until collision. For example, the images of a pair of image pickup devices arranged in the vehicle width direction have different appearances of nearby obstacles. Therefore, an obstacle in the vicinity can be identified based on the difference between the obstacles in the pair of images. Further, the direction and distance of the obstacle can be calculated by trigonometry from the arrangement of the pair of image pickup devices and the image pickup position of the obstacle in the pair of images. From this distance and the vehicle speed measured by the vehicle speed sensor 23, the time required for the vehicle to reach the obstacle and collide can be calculated. Further, the control unit 30 predicts the moving direction and the distance of the obstacle from the information of the direction and the distance of the plurality of sets of obstacles which are further temporally before and after, and predicts the collision with the obstacle based on the prediction result. You may.
In addition to this, for example, the control unit 30 is based on rapid deceleration of the vehicle for collision avoidance detected by the vehicle acceleration sensor 22 and rapid deceleration operation for collision avoidance detected by the brake operation sensor 24. Therefore, the possibility of collision may be determined.

Then, when the possibility of collision is predicted, the control unit 30 starts the winding of the strap 11 by the pretensioner before the collision (step ST2). In this case, the control unit 30 may drive the motor 18 in the winding direction. As a result, before the collision, the strap 11 hung around the front of the body of the occupant is started to be wound up. The body of the occupant is restrained by the strap 11 and pressed against the seat 5. The body of the occupant is corrected to a correct posture in which the seat 5 touches the back. For example, as shown in FIG. 7(A), the upper body of the occupant, which is separated from the seat 5 in the front, is constrained by the strap 11 and pressed against the seat 5 before the collision, as shown in FIG. 7(B).
On the contrary, when the possibility of collision is not expected, the control unit 30 ends the process of FIG.

After starting to wind the strap 11, the control unit 30 sets the target according to the state of the occupant detected by the occupant state sensor before the collision, as shown in FIGS. 7(C) and 7(D). The winding and loosening of the strap 11 by the pretensioner are repeated according to the value of (step ST3).
Specifically, the control unit 30 determines that the detection value of the belt tension sensor 26 and the detection value of the belt winding amount sensor 27 are based on the correspondence relationship between the belt winding amount and the belt tension when the occupant is appropriately restrained. Winding and loosening of the strap 11 by the pretensioner are repeated so as to be within the target value or within the range.
Then, when the strap 11 is loosened, the control unit 30 may not only reduce the torque for winding the strap 11 but also send out the strap 11 so as to release the restraint state of the body on the seat 5.
Further, the target range or target value may be set according to the body shape of the occupant.
By loosening the strap 11 or rewinding the strap 11 in this manner, the position at which the strap 11 is stretched around the body of the occupant can be shifted vertically depending on the body shape of the occupant. Then, as shown in FIG. 7(B), for the occupant whose posture is corrected so as to be properly seated, for example, the strap 11 is placed on the chest instead of the abdomen, and passes over the shoulder. It can be changed so that it is slanted over. The strapping position of the strap 11 can be changed from the abdomen of FIG. 7(B) to the chest of FIG. 7(D).

Further, in this repetitive control, the control unit 30 repeats the winding and loosening of the strap 11 by the pretensioner so that the detection value of the belt tension sensor 26 does not exceed the value of the steady maximum allowable belt tension.
Further, the control unit 30 repeats the winding and loosening of the strap 11 by the pretensioner so that the detected value of the belt tension sensor 26 does not exceed the value of the instantaneous maximum allowable belt tension that is larger than the steady maximum allowable belt tension.
The control unit 30 also winds the strap 11 by the pretensioner so that the detection value of the belt tension sensor 26 is maintained between the steady maximum allowable belt tension value and the steady minimum allowable belt tension value. Repeat with loosening.
By these controls, it is possible to prevent the belt tension from constantly or instantaneously exceeding the target value even during the repeated control.

FIG. 8 is a timing chart showing an example of winding control of the strap 11 for fitting the strap 11 to an occupant.
The horizontal axis represents time and the vertical axis represents belt tension.
In the case of FIG. 8, in the first winding, the strap 11 is stretched around the abdomen, for example, and the belt tension does not change greatly even when the strap 11 is wound.
In the second winding, the change in belt tension is larger than in the first winding, and the slope of the characteristic line is larger than in the first winding.
In the third winding, the change in belt tension is larger than in the second winding, and the slope of the characteristic line is larger than in the second winding and is appropriate. The inclination corresponds to the appropriate case shown in FIG. In this case, it is considered that the strap 11 is stretched around the occupant at an appropriate position.
The control unit 30 may end the repetition of the winding and loosening of the strap 11 when properly stretched in this way.

The control unit 30 also detects a collision (step ST4).
Then, when a collision is detected, the control unit 30 ends the control of repeating the winding and loosening of the strap 11 that has not ended (step ST5), and then winds the strap 11 (step ST6). ).
The body of the occupant properly restrained by the strap 11 as shown in FIG. 7D after the correction can be properly restrained and supported by the wound-up strap 11 at the time of the collision of FIG. 7E.

As described above, in the present embodiment, the pretensioner starts winding the strap 11 before or at the time of collision. By pretensioning the occupant's body, the body can be supported by the impact load at the time of a collision. Moreover, in the present invention, after starting the winding of the strap 11, the winding and the loosening of the strap 11 are repeated before the collision. Therefore, the strap 11 can be stretched around the body of the occupant who has been corrected at an appropriate position. Depending on the body shape and posture of the occupant, even if it is not possible to wind the strap 11 once at a proper position, it is possible to eliminate it. It is possible to increase the possibility that the collision load acts on the body of the occupant while the strap 11 is appropriately stretched.
Further, in the present embodiment, by repeating the winding and loosening of the strap 11 before the collision, even if the compression pressure acts on the body by the pre-tension operation before the collision, it is reset and reduced before the collision. be able to. The compression pressure by the pre-tension and the compression load by the expanded airbag 37 are added to the contact portion of the strap 11 as they are, and it becomes difficult to act. Moreover, even if an impact load due to a collision is applied thereafter, it becomes difficult to apply a force obtained by adding the compression pressure due to the pre-tension and the impact load at the time of collision to the contact portion of the strap 11 as it is.

[Second Embodiment]
The second embodiment of the present invention differs from the first embodiment in passenger protection control. Hereinafter, differences from the first embodiment will be mainly described, and description of configurations and operations common to the first embodiment will be omitted.

FIG. 9 is a flowchart of occupant protection control according to the second embodiment.

As shown in FIG. 9, the control unit 30 periodically determines the possibility of collision before the collision (step ST11). The control unit 30 may determine the possibility of a collision that is not easy to avoid.
When predicting the possibility of collision, the control unit 30 starts winding the strap 11 by the pretensioner before the collision (step ST12). In this case, the control unit 30 may drive the motor 18 in the winding direction.
On the contrary, when the possibility of collision is not expected, the control unit 30 ends the process of FIG.

After starting to wind the strap 11, the control unit 30 winds and loosens the strap 11 by the pretensioner along the target inclination according to the state of the occupant detected by the occupant state sensor before the collision. And are repeated (step ST13).
Here, the control unit 30 uses the strap by the pretensioner so that the inclination of the change in the detection value calculated from the detection value of the belt tension sensor 26 and the detection value of the belt winding amount sensor 27 follows the target inclination. Repeat 11 winding and loosening.

Further, the control unit 30 detects a collision (step ST14).
Then, when a collision is detected, the control unit 30 ends the control of rewinding and loosening the strap 11 that has not been finished (step ST15), and then winds the strap 11 (step ST16). ).
This makes it possible to support the occupant with the strap 11 that can be corrected to an appropriate position when the vehicle collides before or after the predicted time.

[Third Embodiment]
The third embodiment of the present invention differs from the first embodiment in passenger protection control. Hereinafter, differences from the first embodiment will be mainly described, and description of configurations and operations common to the first embodiment will be omitted.

FIG. 10 is a flowchart of occupant protection control according to the third embodiment.

As shown in FIG. 10, the control unit 30 periodically determines the possibility of a collision before the collision (step ST21). The control unit 30 may determine the possibility of a collision that is not easy to avoid.
When predicting the possibility of collision, the control unit 30 starts winding the strap 11 with the pretensioner before the collision (step ST22). In this case, the control unit 30 may drive the motor 18 in the winding direction.
On the contrary, when the possibility of collision is not expected, the control unit 30 ends the process of FIG.

After starting to wind the strap 11, the control unit 30 winds and loosens the strap 11 by the pretensioner according to the target value according to the state of the occupant detected by the occupant state sensor before the collision. And are repeated (step ST23).
In addition, the control unit 30 may repeat the winding and loosening of the strap 11 by the pretensioner along the target inclination or both of them.

Further, the control unit 30 calculates the predicted time until the collision (step ST24), and causes the timer 29 to measure it.
Then, when the predicted time has elapsed (step ST25), the control unit 30 finishes repeating the winding and loosening of the strap 11 (step ST26), and winds the strap 11 (step ST27).
This makes it possible to support the occupant with the strap 11 that can be corrected to an appropriate position when the vehicle collides before or after the predicted time.

The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications or changes can be made without departing from the gist of the invention.

1...Car (vehicle)
2... Front room 3... Crew room 4... Rear room 5... Seat 10... Seat belt device 11... Strap 12... Anchor 13... Tongue plate 14... Buckle 15... Retractor device 16... Holder 17... Reel 18... Motor 21... Imaging device 22... Vehicle acceleration sensor 23... Vehicle speed sensor 24... Brake operation sensor 25... Vehicle angular velocity sensor 26... Belt tension sensor 27... Belt winding amount sensor 28... Seating sensor 29... Timer 30... Control section 35... Air bag device

Claims (10)

A strap that is hung in front of the body of an occupant seated on a vehicle seat,
A pretensioner that winds up the strap,
A control unit for starting the winding of the strap by said pretensioner before collision,
An occupant state sensor that detects the restrained state of the occupant,
Have
The control unit is
After the strap is started to be wound up, before the collision, the pretensioner winds and loosens the strap so that the strap is in an appropriate position according to the restraint state of the occupant detected by the occupant state sensor. return to, winding the strap by the pretensioner in the event of a collision,
Vehicle occupant protection device. As the occupant status sensor,
A belt tension sensor for detecting tension acting on the strap,
A belt winding sensor for detecting the winding amount of the strap,
The control unit is
The detection value of the belt tension sensor and the detection value of the belt winding sensor are set within a target range or a target value based on the correspondence relationship between the belt winding amount and the belt tension corresponding to the chest displacement of the occupant. , Repeating the winding and loosening of the strap by the pretensioner,
The vehicle occupant protection device according to claim 1 . The control unit is
Take up and loosen the strap by the pretensioner so that the inclination of the change in the detection value calculated from the detection value of the belt tension sensor and the detection value of the belt winding sensor is along the target inclination. repeat,
The vehicle occupant protection device according to claim 2 . The control unit is
The detection value of the belt tension sensor repeats winding and loosening of the strap by the pretensioner so as not to exceed the steady maximum allowable belt tension.
The vehicle occupant protection device according to claim 2 or 3 . The control unit is
The detection value of the belt tension sensor repeats winding and loosening of the strap by the pretensioner so as not to exceed an instantaneous maximum allowable belt tension larger than the steady maximum allowable belt tension.
The vehicle occupant protection device according to claim 4 . The control unit is
Winding and loosening of the strap by the pretensioner are repeated so that the detection value of the belt tension sensor is maintained between the steady maximum allowable belt tension and the steady minimum allowable belt tension.
The occupant protection device for a vehicle according to any one of claims 2 to 5 . The target range or the target value is set according to the body shape of the occupant,
The vehicle occupant protection device according to any one of claims 2 to 6 . A traveling condition sensor for detecting a traveling condition of the vehicle,
The control unit is
When the collision of the vehicle is predicted before the collision based on the detection of the traveling condition sensor, the winding and loosening of the strap by the pretensioner are repeated before the collision,
An occupant protection device for a vehicle according to any one of claims 1 to 7 . A timer that measures time, or an impact sensor that detects the collision of the vehicle or the movement of the body due to the collision,
The control unit is
When the estimated time until the collision measured by the timer elapses, or when the collision is detected by the impact sensor, the repetition of winding and loosening the strap is completed,
After that, wind up the strap,
Occupant protection apparatus for a vehicle of any one of claims 1 8. The control section sends out the strap so as to release the restraint state of the body with respect to the seat in the repeated control of winding and loosening the strap,
The occupant protection device for a vehicle according to any one of claims 1 to 9 .

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