JP2000085530A - Retractor for seat belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a required winding/drawing-out force independently of a dimension or the like of each winding spring, by obtaining the appropriate winding/drawing-out force at a set winding amount by pre-winding the winding spring with a torque measured. SOLUTION: An outer end of a winding spring 30 is fixed to an upper case 7 so as not to be rotated, and then, the upper case 7 is fixed into a wall member 20 so as not to be rotated. Next, a lower cover 5 is built in the upper case 7, while a retainer 6 is built in so as to lock an inner end of the winding spring 30. Then, a shaft 22 is engaged with the retainer 6. When a motor 21 rotates the shaft 22 so as to pre-wind the winding spring 30, a torque is detected by a torque sensor 23 provided between the motor 21 and the retainer 6. The motor 21 is driven as an adjusting device 25 adjusts such that the detected torque gets equal to a target torque. At the same time, the motor 21 rotates the shaft 22 so as to pre-wind the winding spring 30 through the retainer 6. Accordingly, a feedback operation is performed wholly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seat belt retractor provided with a winding spring device for urging a winding shaft in a webbing winding direction.

[0002]

2. Description of the Related Art Conventionally, a seatbelt for holding a vehicle occupant or the like safely in a seat includes a webbing, a buckle, a mounting device, and a retractor (winding device). The retractor is a device that automatically retracts the webbing when the seatbelt is not used, and is a winding device that prevents damage to the webbing and that can freely change the length of the webbing when the seatbelt is used.

[0003] Such retractors include an automatic locking retractor and an emergency locking retractor, all of which are rotatably bridged through a pair of through holes formed in opposing side plates of a base. The webbing is wound up by a spring force of a winding spring that urges the winding shaft in a webbing winding direction.

[0004] As this seat belt take-up spring,
For example, as shown in FIG. 7, an S-shaped thin plate spring is used. The take-up spring 30 has an outer end 30b fixed to an inner wall of a spring case fixed to a side plate of the base, and an inner end 30a.
Are locked by a retainer fitted to one end of the winding shaft. Therefore, the inner end 30a side is pre-wound several turns and is connected to one end of the seat belt winding shaft to apply a rotational torque to the seat belt winding shaft.

As a method of applying a rotational torque to the take-up spring, there is, for example, the following method. In order to store the take-up spring in the spring case in a state where the outer end is locked to the spring case, and to pre-wind the inner end side of the take-up spring through the retainer by a predetermined number of revolutions, to maintain the pre-wound state. A method of attaching a stop jig to the retainer so that the retainer cannot rotate, connecting the seat belt winding shaft with the webbing to the retainer, removing the stop jig, and applying a rotational torque to the seat belt winding shaft. After attaching the webbing to the seat belt winding shaft,
A method in which the inner end of the take-up spring is connected to the seat belt take-up shaft via a retainer, and the outer end of the take-up spring is pre-wound by a predetermined number of revolutions to apply a rotational torque to the take-up spring. That is, in each case, the winding torque is applied to the seat belt winding shaft by pre-winding the winding spring by the specified number of rotations.

[0006]

By the way, in the case of the above-mentioned method, since the rotation torque of the winding spring is given on the basis of the pre-winding rotation speed, the thickness, hardness, If the width, length, and the like are different, the rotational torque may vary even at the same pre-winding rotational speed. For this reason, occupants using retractors for seat belts that have a take-up spring that is not given the appropriate torque will feel the spring force strongly and their shoulders will stiffen. There was a risk that the belt could not be completely wound and wound.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a seat belt retractor to which a proper take-out and pull-out force is applied without depending on the dimensions of each take-up spring.

[0008]

According to a first aspect of the present invention, a seat belt retractor is characterized in that a pre-winding operation is performed while measuring a torque value so that a desired winding pull-out force can be obtained at a set winding amount. And A retractor for a seat belt according to a second aspect of the present invention is the retractor for a seat belt according to the first aspect, wherein the winding spring of the winding spring device is pre-wound with a target torque value.

According to the seat belt retractor of the present invention, the desired retracting force can be obtained by controlling the torque value. According to the seat belt retractor of the present invention, the pre-winding of the winding spring is configured to be managed by measuring a torque value, not a rotation speed. Therefore, even when the dimensions and the like of the winding springs vary, it is possible to apply an appropriate winding and pulling force to the seat belt retractor.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a side view of a seat belt retractor 10 according to one embodiment of the present invention.

As shown in FIG. 1, a retractor base 1 of a seat belt retractor 10 according to an embodiment of the present invention has a substantially U-shaped cross section, and is provided on opposed side plates 1a and 1b. Are respectively formed with through-holes facing each other, and a winding shaft 4 on which a take-up reel 2 is fixed is provided in the through-holes.
Is rotatably bridged. At one end of the winding shaft 4,
A retainer in which the inner end of the take-up spring is locked is arranged,
The outer end of the winding spring is connected to the base 1 together with the lower cover 5.
Is fixed to the inner wall of the upper cover 7 fixed to the side plate 1a. Thus, a take-up spring device 14 that constantly urges the webbing 3 in the take-up direction is disposed on the take-up shaft 4.

On the other hand, at the other end of the winding shaft 4, a known emergency lock mechanism 15 for preventing the webbing 3 from being pulled out in an emergency is arranged. This emergency lock mechanism 15
By appropriately engaging a pawl attached to the outside of the side plate 1b with a ratchet wheel fixed to the other end of the winding shaft 4, the rotation of the winding shaft 4 in the webbing withdrawing direction in an emergency is locked, and This is to prevent withdrawal.
A sensor cover 12 is provided outside the side plate 1a that covers the emergency lock mechanism 15.

FIG. 2 is a partially exploded view showing a state in which the winding spring 30 is locked. As shown in FIG.
Has a U-shaped outer end 30b. The U-shaped portion of the outer end 30b is locked by a protrusion 7a provided on the inner wall of the upper case 7, and the tip of the outer end 30b is locked by the protrusion 7b. Also, take-up spring 3
The inner end 30a of the retainer 6 is engaged with the groove 6a of the retainer 6 fitted to one end of the winding shaft 4.

Next, a method of applying a rotational torque to the winding spring 30 of the present invention will be described with reference to FIG. First, the outer end 30b of the winding spring 30 is non-rotatably attached to the upper case 7, and the upper case 7 is non-rotatably fixed to the wall member 20. Thereafter, the lower cover 5 is assembled, and the retainer 6 is assembled so that the inner end 30a of the winding spring 30 can be locked. Then, the shaft 2 is attached to the retainer 6.
2 and the shaft 22 is rotated by the motor 21 to pre-wind the winding spring 30. At this time, the torque value is detected by providing the torque sensor 23 between the motor 21 and the retainer 6. That is, a comparison is made so that the torque value measured by the torque sensor 23 (detection unit) becomes the target torque value, and the adjustment device 25 (adjustment unit) is adjusted to drive the motor 21 (operation unit). By rotating the shaft 22 by 21 and pre-winding the take-up spring 30 (control target) via the retainer 6, a feedback operation is performed as a whole.

Also, by a method as shown in FIG.
It is possible to apply a rotational torque to the winding spring 30. That is, the outer end 30b of the winding spring 30 is non-rotatably attached to the upper case 7, and the upper case 7 is non-rotatably fixed to the rotating member 31. Thereafter, the lower cover 5 is assembled, and the retainer 6 is assembled so that the inner end 30a of the winding spring 30 can be locked. Thereafter, the shaft 22 is fitted to the retainer 6, and the rotating member 31 is rotated by the motor 21 via the shaft 21, so that the winding spring 30 is rotated.
Pre-winding. At this time, the shaft 2 fitted with the retainer 6
A torque value is detected by providing a torque sensor 23 at one end of 2. That is, a comparison is made so that the torque value measured by the torque sensor 23 (detection unit) becomes the target torque value, and the adjustment device 25 (adjustment unit) is adjusted to drive the motor 21 (operation unit). By rotating the rotating member 31 by 21 and pre-winding the winding spring 30 (control target), a feedback operation can be performed as a whole.

Here, as shown in FIG. 5, as the torque sensor 23, for example, a needle 35 is attached to one end of a torsion bar 33 fixed to a wall 41, and the needle 35 rotates to contact the limit switch 37. A configuration in which the torque value is detected by contact is provided. However, the present invention is not limited to the torque sensor of FIG. 5, and various changes and improvements can be made.

When the torque value reaches the target torque value, as shown in FIG. 6A, the position of the stop groove 6b of the retainer 6 and the position of the stop groove 5a of the lower cover 5 are set within 1/2 rotation. At the same time, as shown in FIG. 6B, the stop jig 27 is
Then, the take-up spring 30 is inserted into the retainer 6 to maintain the pre-wound state. Here, when the target torque value of the winding spring 30 is set, the motor 21 may be stopped when the target torque value is reached, or may be stopped after n rotations from reaching the predetermined torque and set to the target torque value. It is also possible to set the target torque value by returning by m rotations after reaching the predetermined torque.

The take-up spring device in this state is connected to the retainer 6.
By incorporating the emergency lock mechanism 15 so that the winding shaft 4 fits with the emergency lock mechanism 15 and pulling out the stop jig 27, an appropriate winding and pulling force is set for the seat belt retractor 10 of the present invention, and The take-up spring device 14 keeps the take-up shaft 4 constantly urged in the webbing take-up direction.

[0019]

As described above, in the seat belt retractor of the present invention, the desired winding and pulling force can be obtained at the set winding amount by performing the pre-winding while measuring the torque value. It is possible to provide a seat belt retractor to which a proper take-out and pull-out force is applied, without depending on the dimensions of the respective take-up springs.

[Brief description of the drawings]

FIG. 1 is a side view of a seat belt retractor 10 according to an embodiment of the present invention.

FIG. 2 is a partially exploded view showing a locked state of a winding spring.

FIG. 3 is an explanatory diagram of a method of applying a rotational torque to a winding spring.

FIG. 4 is an explanatory diagram of another method of applying a rotational torque to a winding spring.

FIG. 5 is an example of a torque sensor.

FIG. 6A is a view before inserting a stop jig into a stop groove, and FIG. 6B is a view showing a state where a stop jig is inserted into the stop groove and a pre-wound state is maintained. .

FIG. 7 is a plan view of an S-shaped thin plate spring.

[Explanation of symbols]

 Reference Signs List 10 retractor for seat belt 14 take-up spring device 30 take-up spring

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuichi Takimizu 12 Kirihara-cho, Fujisawa-shi, Kanagawa F-term in NSK Ltd. 3D018 LA01

Claims (2)

[Claims] 1. A retractor for a seat belt, wherein a pre-winding operation is performed while measuring a torque value so as to obtain a desired take-out pull-out force at a set winding amount. 2. The retractor for a seat belt according to claim 1, wherein the winding spring of the winding spring device is pre-wound with a target torque value.