JP4512443B2 - Seat belt device and seat belt tension control method. - Google Patents

Description

  The present invention relates to a seat belt device, and in particular, restrains the occupant by preventing the seat belt (webbing) from being pulled out in the event of a vehicle emergency, and pulls out the seat belt when a load greater than a set load acts on the occupant. The present invention relates to a vehicle seat belt device that absorbs impact energy and a seat belt tension control method.

  In general, a seat belt device is used to effectively protect passengers in a vehicle in the event of a vehicle emergency. A seat belt device usually has a retractor (Emergency Locking) that winds a seat belt around a take-up shaft by a spring force and restrains the occupant by preventing the withdrawal of the seat belt by locking the withdrawal of the seat belt in a vehicle emergency. Retractor: hereinafter referred to as ELR).

  The seat belt device is provided with a pretensioner mechanism and a force limiter mechanism (Patent Document 1). The pretensioner mechanism includes a cylinder and a piston provided in the cylinder. In the event of a vehicle emergency, the gas is supplied into the cylinder so that the piston is raised by the gas pressure and the take-up shaft is moved in the seat belt winding direction. Rotate to The force limiter mechanism is equipped with a deformable energy absorbing member. When an occupant's load higher than the set load is applied to the seat belt in the event of a vehicle emergency, the energy absorbing member is deformed to lower the piston and pull out the seat belt. Rotate the take-up shaft.

According to this seat belt device, when the pretensioner mechanism is activated in the event of a vehicle emergency and the seat belt is wound up to eliminate the looseness of the seat belt, when the seat belt is locked by ELR and the withdrawal of the seat belt is prevented, The forward movement of the occupant is abruptly restricted. If a load greater than the set load is applied to the seat belt after the seat belt is locked by ELR, the energy absorbing member of the force limiter mechanism is deformed and the seat belt is pulled out while maintaining a predetermined belt tension. And the impact energy acting on the occupant is absorbed. The relationship between the belt tension and the seat belt withdrawal amount at this time is as shown by the line “With PT” in FIG. 3. The belt tension increases to the maximum value until the predetermined belt withdrawal amount, and then the force limiter mechanism As a result, the seat belt is pulled out, so that the belt tension is maintained at the maximum value.
JP 2000-159059 A

  However, in the conventional seat belt device, since the pretensioner mechanism and the force limiter mechanism are provided separately, the pretensioner mechanism is activated in the event of a vehicle emergency and the seat belt is locked by ELR to prevent the seat belt from being pulled out. Even so, the contact load (occupant contact load) to the occupant at the shoulder portion of the seat belt decreases immediately after the pretensioner mechanism is actuated (around 30 ms) as shown by the curve “With PT” in FIG. Restraint force may be temporarily reduced.

  It is an object of the present invention to provide a seat belt device and a seat belt tension control method that can smoothly raise an occupant restraint force without decreasing at an early stage of vehicle emergency.

In order to achieve the above object, the seat belt device for restraining an occupant in the event of a vehicle emergency according to the present invention is detected by a pull-out amount detecting means for detecting a pull-out amount of the seat belt pulled out by a take-up shaft that winds the seat belt. Based on the belt belt tension detected by the tension detecting means for detecting the belt belt pulling amount and the belt tension acting on the seat belt, the tension of the seat belt at the time of the vehicle emergency becomes a preset maximum tension. A winding shaft that winds up the seat belt so that it substantially monotonously increases with time, decreases from the maximum tension according to the amount of belt withdrawal, and maintains a constant value even after time elapses. The rotation is controlled in the seat belt retracting direction and the seat belt withdrawing direction by the rotating means.

The seat belt tension control method for restraining an occupant in the event of a vehicle emergency according to the present invention provides a seat belt detected by a pull-out amount detecting means for detecting a pull-out amount of the seat belt pulled out by a winding shaft that winds up the seat belt. Based on the pull-out amount and the belt tension detected by the tension detecting means for detecting the belt tension acting on the seat belt, the time elapses until the tension of the seat belt in the emergency of the vehicle reaches a preset maximum tension. The winding shaft that winds up the seat belt is rotated by the rotating means so that it substantially monotonically increases in response, decreases from the maximum tension in accordance with the belt withdrawal amount, and maintains a constant value even after a lapse of time thereafter. The rotation control is performed in the belt winding direction and the seat belt drawing direction.

The present invention provides a winding shaft for winding a seat belt, rotating means for rotating the winding shaft in a seat belt winding direction and a seat belt pulling direction, and the amount of seat belt pulled out from the winding shaft. A pull-out amount detecting means for detecting, a tension detecting means for detecting a belt tension acting on the seat belt, a pull-out amount of the seat belt detected by the pull-out amount detecting means, and a belt tension detected by the tension detecting means. Based on this, the belt tension in the event of a vehicle emergency increases according to the belt withdrawal amount until reaching a preset maximum tension, decreases from the maximum tension according to the belt withdrawal amount, and then the belt withdrawal amount increases. And a control means for controlling the rotation of the take-up shaft by the rotating means so as to maintain a constant value.

  Further, when the tension is controlled as described above in the present invention, the contact load on the seat belt occupant in the emergency of the vehicle increases to the maximum contact load, decreases from the maximum contact load, and then reaches a substantially constant value. Can be held.

  Therefore, in the seat belt device for restraining an occupant in the event of a vehicle emergency according to the present invention, the contact load on the occupant of the shoulder portion of the seat belt at the time of the vehicle emergency increases to a preset maximum contact load and decreases from the maximum contact load. Then, a substantially constant value may be held thereafter.

The present invention also provides a take-up shaft for taking up a seat belt, rotation means for rotating the take-up shaft in a seat belt take-up direction and a seat belt take-out direction, and a withdrawal of the seat belt drawn from the take-up shaft. Pull-out amount detection means for detecting the amount, tension detection means for detecting the belt tension acting on the seat belt, the amount of seat belt withdrawn detected by the pull-out amount detection means and the belt detected by the tension detection means Based on the tension, the contact load on the occupant of the seat belt shoulder in the event of a vehicle emergency increases to a preset maximum contact load, decreases from the maximum contact load, and then maintains a substantially constant value. And a control means for controlling the rotation of the winding shaft by the rotating means.

  In the present invention, the tension of the seat belt in the event of a vehicle emergency increases according to the belt withdrawal amount until reaching a preset maximum tension with the passage of time, and decreases from the maximum tension according to the belt withdrawal amount. Then, by controlling so that a constant value is maintained even if the belt withdrawal amount increases thereafter, the contact load on the seat belt occupant in the emergency of the vehicle increases to the maximum contact load. After that, it is possible to maintain a substantially constant value.

  That is, in the present invention, since the function of the conventional pretensioner and the function of the force limiter are functioned integrally without being separated, the occupant restraint force is smoothly raised without being lowered at the early stage of the vehicle emergency. be able to. Further, since the occupant restraining force is reduced from the time when it reaches the maximum value, the time during which the maximum restraining force acts on the occupant can be reduced.

The control means in the seat belt device of the present invention can control the belt tension to be forcibly applied by winding the belt until reaching a preset maximum tension before the belt is pulled out in a vehicle emergency. it can. As a result, the belt is wound up at the initial stage of the vehicle emergency, and the belt tension is increased until reaching the preset maximum tension, and the occupant restraint force is positively increased at the initial stage of the vehicle emergency. be able to.
The control means can control the rotation of the take-up shaft by the rotation means using a lookup table that defines the relationship between the belt tension and the belt withdrawal amount. It may be determined according to the pedal depression force, the brake pedal depression amount, or the vehicle deceleration.

  As described above, according to the present invention, the tension of the seat belt at the time of vehicle emergency increases according to the elapsed time until reaching the maximum tension, decreases according to the elapsed time from the maximum tension, and then the time elapses. However, by controlling so as to maintain a constant value, the restraining force on the occupant of the shoulder portion of the seat belt in a vehicle emergency increases to the maximum value, decreases from the maximum value, and then maintains a substantially constant value. As a result, it is possible to raise the occupant restraint force smoothly without lowering the occupant restraint force at the initial stage of the vehicle emergency and to reduce the time during which the maximum restraint force acts on the occupant. .

  A seat belt device according to an embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the seat belt device includes a seat belt (webbing) 16 for protecting an occupant 14 seated on the seat 12. A tongue plate is attached to the tip of the seat belt 16.

  The seat belt 16 extends through the shoulder portion 14a of the occupant 14 via a shoulder anchor 20 that is pulled out from the ELR 18 and is swingably attached to the inner wall surface of the vehicle body. When the belt is attached, the seat belt 16 is pulled out from the ELR 18, and the tongue plate is engaged with and attached to the buckle 22 fixed to the seat cushion portion side of the seat 12. Further, by releasing the engagement between the tongue plate and the buckle, the wearing state of the belt is released. A steering wheel 24 incorporating an air bag is provided in front of an occupant 14 as a driver.

  The ELR 18 includes a retractor base fixed to the inner wall surface of the vehicle body. A retractable shaft 26 around which the seat belt 16 is wound is rotatably supported by the retractor base. The winding shaft 26 is provided with a winding spring that urges the winding shaft 26 in the seat belt winding direction. The winding shaft 26 is connected to an output shaft of a motor 28 as tension control means for controlling the belt tension by rotating the winding shaft 26 in the seat belt winding direction and the seat belt pulling direction.

  As the tension control means, a hydraulic device or the like can be used instead of the motor.

  Further, the ELR 18 is provided with a displacement sensor (length sensor) 30 for detecting the amount by which the seat belt 16 is pulled out. The displacement sensor 30 can be constituted by, for example, a capacitance type sensor that obtains a displacement amount of the moving electrode from a change in capacitance due to displacement of the moving electrode that moves together with the seat belt.

  The motor 28 and the displacement sensor 30 are connected to a control circuit 32 constituted by a microcomputer. In the memory of the control circuit 32, a program of a control routine described below is stored, and a look-up table that defines the relationship between the belt tension and the belt withdrawal amount indicated by the “No PT” line in FIG. It is remembered. As shown in FIG. 3, the belt tension of this lookup table increases in proportion to the belt withdrawal amount until reaching the maximum tension (for example, 4000 N to 6000 N), and slightly increases in proportion to the belt withdrawal amount from the maximum tension. Time (for example, about 10 to 30 ms (depending on vehicle deceleration)) gradually decreases to a value about 1/2 of the maximum tension (for example, 2000 N to 3000 N), and then the belt withdrawal amount increases. It is determined to hold a constant value of about 1/2 of the maximum tension. Further, the look-up table that defines the relationship between the belt tension and the belt withdrawal amount may be prepared according to the depression force of the brake pedal, the depression amount of the brake pedal, or the deceleration of the vehicle.

  The control circuit 32 is connected to a deceleration sensor 34 that detects vehicle deceleration and a tension sensor 36 that detects the tension of the seat belt. The tension sensor 36 includes a load cell that detects the tension of the seat belt interposed between the fixing portion of the buckle 22 on the seat cushion portion side and the buckle 22. A sensor for detecting the tension of the seat belt may be provided in the shoulder anchor 20 as a tension sensor instead of the load cell.

  Next, a control routine for controlling the belt tension by controlling the rotation of the motor according to the present embodiment will be described. In step 100, it is determined whether or not the vehicle is in a sudden deceleration state where the deceleration is equal to or greater than a predetermined value based on the deceleration detected by the deceleration sensor, that is, whether or not the vehicle is in an emergency. When it is determined that the vehicle is in an emergency, in step 102, the motor starts to rotate in the seat belt winding direction to remove the looseness of the seat belt so that the initial tension acts on the seat belt.

  In the next step 104, the belt tension data detected by the tension sensor 36 and the belt withdrawal amount data detected by the displacement sensor 30 are fetched, and in step 106, each value of the belt withdrawal amount is obtained by referring to the lookup table. The belt tension value is calculated as the target belt tension and the target belt withdrawal amount.

  In step 108, the motor is gradually rotated in the belt withdrawing direction so that the current belt tension and the belt withdrawal amount taken in in step 104 respectively match the calculated target belt tension and the target belt withdrawal amount. .

  As a result, when the withdrawal of the seat belt is locked and the withdrawal of the seat belt is prevented in the event of a vehicle emergency, the forward movement of the occupant is abruptly restrained and the belt tension tends to rise suddenly. It is controlled so that the tension of the seat belt increases in proportion to the amount of belt withdrawal until the seat belt is withdrawn by being gradually rotated in the belt withdrawal direction and reaches the maximum tension.

  After the belt tension reaches the maximum tension, the motor is gradually rotated in the seat belt pull-out direction so that the belt tension decreases from the maximum tension according to the belt pull-out amount. Then, when the belt tension decreases to a value of about 1/2 of the maximum tension, the belt withdrawal amount is gradually increased so that the belt tension is maintained at a value of about 1/2 of the maximum tension.

  As a result, the occupant contact load on the shoulder portion of the seat belt monotonously increases up to the maximum contact load, gradually decreases from the maximum contact load, as shown by the curve of “No PT” in FIG. It changes to hold the contact load. Further, as shown by the curve of “No PT” in FIG. 5, the belt tension substantially monotonically increases to the maximum value according to the elapsed time, gradually decreases from the maximum value, and then the time elapses. Also, it changes so as to maintain a substantially constant tension. Note that the curve “with PT” in FIG. 5 shows the change over time of the belt tension when the pretensioner mechanism is activated. As a result, the occupant contact load does not decrease and the occupant restraint force does not decrease at the initial stage of the vehicle emergency, and the maximum contact load is also a seat belt device using the function of the conventional pretensioner and the force limiter. It is lower.

  In the above embodiment, the example in which the belt tension is controlled according to the belt drawing amount has been described. However, the belt tension may be controlled according to the elapsed time or the belt winding amount.

  In order to reduce the injury of the passenger chest due to a vehicle accident, it is effective to reduce the deflection of the chest. In particular, in the case of a frontal collision, from the viewpoint of occupant protection, it is effective to bring the occupant deceleration closer to the deceleration generated in the vehicle at an early stage immediately after the collision. In the present embodiment, the occupant restraining force of the shoulder portion of the seat belt at the time of the vehicle collision can be substantially monotonously increased to the maximum value, so that the occupant restraining force is prevented from being reduced at the initial stage of the vehicle collision. Thus, the occupant's deceleration can be made closer to the deceleration generated in the vehicle at an early stage, and the amount by which the occupant's head moves forward can be reduced. In addition, after the occupant restraint force monotonously increases to the maximum value, the occupant restraint force gradually decreases from the maximum value in a short time, and then holds a substantially constant restraint force, so that the maximum restraint force acts on the occupant. Time can be reduced to reduce the chest deflection of the occupant.

It is the schematic which shows embodiment of this invention. It is a flowchart which shows the tension control routine of embodiment of this invention. It is a diagram showing the relationship between the belt tension and the belt withdrawal amount stored in the look-up table of this embodiment, and the change in the belt tension with respect to the belt withdrawal amount when the conventional pretensioner mechanism is operated. The diagram which shows the time series change of the passenger | crew contact load of the shoulder part of the seatbelt of a present Example, and the time series change of the passenger | crew contact load of the shoulder part of a seatbelt when operating the conventional pretensioner and the force limiter mechanism It is. It is a diagram which shows the time series change of the belt tension of a present Example, and the time series change of the belt tension of a seatbelt when operating the conventional pretensioner and the force limiter mechanism.

Explanation of symbols

12 Seat 14a Shoulder part 14 Crew 16 Seat belt 18 ELR
20 Shoulder anchor 22 Buckle 24 Steering 26 Winding shaft 28 Motor 30 Displacement sensor 32 Control circuit 34 Deceleration sensor 36 Tension sensor

Claims (5)

A seat belt device for restraining an occupant in a vehicle emergency,
A tension detection means for detecting the amount of seat belt withdrawal detected by a withdrawal amount detection means for detecting the amount of withdrawal of the seat belt drawn by the take-up shaft for winding the seat belt and the belt tension acting on the seat belt; Based on the detected belt tension, the tension of the seat belt in the event of a vehicle emergency substantially monotonically increases with time until reaching the preset maximum tension, and from the maximum tension according to the belt withdrawal amount. reduced, then to maintain a constant value over time, the seat belt device for controlling the rotation in the seat belt winding direction and the belt withdrawing direction by the rotating means the take-up shaft. A seat belt tension control method for restraining an occupant in a vehicle emergency,
A tension detection means for detecting the amount of seat belt withdrawal detected by a withdrawal amount detection means for detecting the amount of withdrawal of the seat belt drawn by the take-up shaft for winding the seat belt and the belt tension acting on the seat belt; Based on the detected belt tension, the tension of the seat belt in the event of a vehicle emergency substantially monotonically increases with time until reaching the preset maximum tension, and from the maximum tension according to the belt withdrawal amount. reduced, so that subsequent time to maintain a constant value even after elapse, the seat belt tension control method for controlling rotation in the seat belt winding direction and the belt withdrawing direction by the rotating means the take-up shaft. A take-up shaft that winds up the seat belt;
Rotating means for rotating the winding shaft in the seat belt winding direction and the seat belt pulling direction;
A drawing amount detection means for detecting a drawing amount of the seat belt drawn by the winding shaft;
Tension detecting means for detecting belt tension acting on the seat belt;
Based on the seat belt pull-out amount detected by the pull-out amount detecting means and the belt tension detected by the tension detecting means, the belt pull-out amount is adjusted until the belt tension in the vehicle emergency reaches a preset maximum tension. Control means for controlling the rotation of the winding shaft by the rotating means so as to maintain a constant value even if the belt pulling amount increases after that, and increases according to the belt pulling amount. ,
Including seat belt device. A take-up shaft that winds up the seat belt;
Rotating means for rotating the winding shaft in the seat belt winding direction and the seat belt pulling direction;
A drawing amount detection means for detecting a drawing amount of the seat belt drawn by the winding shaft;
Tension detecting means for detecting belt tension acting on the seat belt;
The belt is wound until the belt tension in the emergency of the vehicle reaches a preset maximum tension based on the pull-out amount of the seat belt detected by the pull-out amount detection means and the belt tension detected by the tension detection means. The belt tension is forcibly applied, the belt tension decreases from the maximum tension according to the belt withdrawal amount, and then the rotation means keeps a constant value even if the belt withdrawal amount increases. Control means for controlling the rotation of the winding shaft;
Including seat belt device.   The control means uses the look-up table that defines the relationship between the belt tension and the belt withdrawal amount in accordance with the depression force of the brake pedal, the depression amount of the brake pedal, or the deceleration of the vehicle. The seat belt device according to claim 3 or 4, wherein the rotation of the spindle is controlled.

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