Belt retractor

Abstract

A belt retractor for a vehicle safety belt with a frame has a belt reel (10) rotatably mounted in the frame, a coupling disk (14) rotatably mounted relative to the belt reel (10), and a clip spring (16) which is attached to the belt reel (10) and to the coupling disk (14).

Description

TECHNICAL FIELD

The invention relates to a belt retractor for a vehicle safety belt.

BACKGROUND OF THE INVENTION

The belt retractor serves to make the vehicle safety belt available to a vehicle occupant. In the normal operating state the vehicle safety belt may be unwound from a belt reel or wound up again on the same. There is provided a locking mechanism which is capable of blocking the belt reel in a manner sensitive to the belt webbing or in a vehicle-sensitive manner, hence dependent on parameters such as the belt webbing or vehicle acceleration. For the vehicle or belt webbing sensitive blocking of the belt reel modern belt retractors have a coupling disk which rotates along with the belt reel in the normal operating state. For the vehicle-sensitive activation of the locking mechanism the coupling disk is provided with a toothing, a locking element of a vehicle-sensitive sensor being able to engage in the toothing. An inertial element is connected to the coupling disk for the belt webbing-sensitive activation of the locking mechanism. If the coupling disk remains behind the rotation of the belt reel on account of the mass inertia, it causes a locking pawl to pivot into a locking toothing of the frame by means of an actuating element.

DE 102 13 248 A1 shows a coupling disk whose basic position with respect to the belt reel is determined by a spiral spring. The production of such spiral springs is complicated and therefore expensive.

It is the object of the invention to provide a belt retractor that can readily and cost-effectively be manufactured.

BRIEF SUMMARY OF THE INVENTION

According to the invention, a belt retractor for a vehicle safety belt with a frame has a belt reel rotatably mounted in the frame, a coupling disk rotatably mounted relative to the belt reel, and a clip spring which is attached to the belt reel and to the coupling disk.

According to the invention there is used a clip spring which determines the basic position of the coupling disk with respect to the belt reel. The clip spring is distinguished by a plurality of advantages. The production of clip springs is simple, since among other things the spring force of the clip springs is solely adjusted by their tensioning, whilst in the case of spiral springs the spring force depends on the number of the spirals, the diameter thereof, etc. The material usage with clip springs is small, which is why clip springs are low-priced. Besides, the transport of clip springs is simple, since they cannot interlock. Therefore, no blister packages are required. When clip springs are used in belt retractors, the moment when the locking pawl is caused to engage is determined by the torque caused by the clip spring and the contact friction of the coupling disk on the reel axle. In the belt retractor in, accordance with the invention this frictional force is adjustable more variably than in the prior art. Depending on the forceless geometry of the clip spring (production state) a torque and a force between the coupling disk and the reel axle may be applied by the systematic tensioning in the state of installation. In the belt retractor in accordance with the invention the contact point of the clip spring to the coupling disk lies opposite the contact point of the locking pawl and is mounted rotatably. The radial component of the tensioning force may, for example, be used to change the amount and the direction of the frictional force caused by the weight of the locking pawl such that the frictional force depends less on the position of the locking pawl. A frictional force whose amount is more constant than in the prior art therefore results in a more defined breakaway in all positions of the locking pawl. Besides, in spiral springs used in the prior art disturbing noises occurred on account of the spirals striking against one another, which is known as “spring whizzing” and which is absent in clip springs. Furthermore, clip springs may be simulated more easily. It is, moreover, advantageous that clip springs have a higher resistance to the action of a tensioner, since they do not become entangled in a higher acceleration.

Preferably, the clip spring is configured symmetrically and therefore does not have to be oriented relative to the reel axle prior to the installation, i.e., it does not have to be rotated. Therefore, the installation is simple.

Preferably, the belt reel includes a reel axle, and the coupling disk is mounted on the reel axle, the clip spring being attached to the belt reel and to the coupling disk such that it does not engage the reel axle. Since the clip spring does not engage the reel axle, the latter is not stressed, and disturbing noises are avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exploded view of a part of a belt retractor in accordance with the invention,

FIG. 2 shows a perspective side view of a part of the belt retractor of FIG. 1, and

FIG. 3 shows a side view of a part of the belt retractor of FIG. 1.

FIGS. 1 to 3 show a part of a belt retractor including a belt reel 10. The belt reel 10 is rotatably mounted about a reel axle 12 in a frame (not shown).

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT

There is provided a coupling disk 14 which is coaxially connected to the belt reel 10. The basic position of the coupling disk 14 with respect to the belt reel 10 is determined by a clip spring 16, the first end of the clip spring 16 being attached to the coupling disk 14 and its second end being attached to the belt reel 10 (FIGS. 2 and 3), in particular, in such a manner that the clip spring 16 does not engage the reel axle 12 and such that it is tensioned. The clip spring 16 is directly attached to the coupling disc 14. For the attachment to the coupling disk 14 and to the belt reel 10, the ends of the clip spring 16 are bent in the shape of hooks (the hooks 17). The clip spring 16 is eccentrically attached to the belt reel 10 and to the coupling disk 14 (with respect to the reel axle 12) and rotatably supported on the coupling disk 14.

On its outer periphery the coupling disk 14 is provided with a toothing 18 which may cooperate with a vehicle-sensitive sensor element (not shown).

The coupling disk 14 is integrally connected to an inertial element (not shown). Along with the inertial element the coupling disk 14 forms the sensor element that is sensitive to the belt webbing and that will be described in more detail hereinafter.

An actuating element 22 (FIGS. 2 and 3) is connected to the coupling disk 14 via a connecting arm. The actuating element 22 engages a locking pawl 20, in particular into a control contour 24 which is situated within the locking pawl 20. The locking pawl 20, which is disposed in a recessed pocket of the belt reel 10, is configured such that it may be caused to engage in a locking toothing (not shown) which is provided on the frame. In so doing, the bearing point of the locking pawl 20 substantially lies opposite (with regard to the axis of rotation of the belt reel 10 and the coupling disk 14) the bearing point of the clip spring 16 on the coupling disk 14.

Along with the inertial element the coupling disk 14 forms the sensor element that is sensitive to the belt webbing. In a sudden rotation of the belt reel 10 the coupling disk 14 stops or trails behind the rotation of the belt reel 10. On account of the relative rotation between the belt reel 10 and the coupling disk 14 the actuating element 22, which is connected to the coupling disk 14 via the connecting arm, shifts such that because of the engagement in the control contour 24 of the locking pawl 20 it pivots the locking pawl 20 in such a manner that the same is caused to engage in the locking toothing of the frame.

The radial component of the tensioning force of the clip spring 16 is used to change the amount and the direction of the frictional force caused by the weight of the locking pawl 20 such that the same depends less on the position of the locking pawl 20. A frictional force whose amount is more constant than in the prior art therefore results in a more defined breakaway in all positions of the locking pawl 20.

Claims

1. A belt retractor for a vehicle safety belt with a frame, said belt retractor including a belt reel (10) rotatably mounted in said frame,a coupling disk (14) rotatably mounted relative to said belt reel (10), anda clip spring (16) which is attached to said belt reel (10) and to said coupling disk (14).

2. The belt retractor according to claim 1, wherein said clip spring (16) is configured symmetrically.

3. The belt retractor according to claim 1, wherein said belt reel (10) includes a reel axle (12), and said coupling disk (14) is mounted on said reel axle (12), said clip spring (16) being attached to said belt reel (10) and to said coupling disk (14) such that it does not engage said reel axle (12).

4. The belt retractor according to claim 1, wherein said clip spring (16) is eccentrically attached to at least one of said belt reel (10) and said coupling disk (14).

5. The belt retractor according to claim 1, wherein said coupling disk (14) includes an actuating element (22), and in that a locking pawl (20) is provided, said actuating element (22) being adapted to engage said locking pawl (20).