Safety belt clamping device

Abstract

The invention relates to a device for clamping a safety belt to prevent it being unwound from a belt reel, the device consisting of a housing in which is provided a lever, one end of the lever being pivotably mounted in the housing, a clamping surface being provided on the lever intermediate its ends which co-operates with a clamping surface provided on the housing, the lever being resiliently urged to move about its pivot in a direction to separate the clamping surfaces. The belt is guided around the pivoted end of the lever, extends between the clamping surfaces and is guided around the free end of the lever, the resilient means applying a tension force to the belt. Movement of the lever against the force of the resilient means moving the clamping surface on the lever towards the clamping surface on the housing to clamp the belt therebetween.

Description

This is a continuation of application Ser. No. 593,710 filed July 7, 1975, abandoned.

BACKGROUND OF THE INVENTION

A 3-point automatic safety belt used at the present time is shown installed in an automobile in FIG. 1 of the accompanying drawings.

Automatic belt winding devices--hereinafter referred to as "automatic devices"--such as are used nowadays in 3-point automatic safety belts for automobile passengers, exert a constant retractive force F_w on the belt between the belt anchorage points and belt guide points D, A, B and C (FIG. 1), pulling it around the passenger and drawing it back to the take-up reel (at point D), with the result that the shoulder belt between point A and point B constantly rests on the upper part of the passenger's body, although the passenger can bend forward against this retractive force F_w and can move freely.

According to the known requirements which automatic devices must fulfil, the retractive force F_w should be between 0.2 and 0.5 kp. In addition, the belting should "lock" under the following conditions:

1. if F..μ_λ ≦F₅ F₈.μ_K ≦F₅

or for the above example this means that with the existing leverage of .Badd.1:4, μ_K must be greater than 0.25 for a satisfactory locking to take place.

FIG. 4 illustrates an example of arresting the winding reel 2 for locking to take place at a vehicle deceleration of 0.4 g in any arbitrary direction. A small pendulum 9 with a link 9a urges a catch 10 with a pawl 10a against a toothed wheel 11 mounted axially on the winding reel 2, and stops the axle 13 of the said winding reel 2. All the actuating elements for this action may be small and light since they only have to exert slight retaining forces to overcome the elasticity of the retaining springs 6 of the locking lever 4 so that the said locking lever 4 comes into the locking position. Following this force F₈ increases constantly with increasing F₅ and ensures locking of the belt, whereupon the arresting device is momentarily not subject to any forces.

FIG. 2 illustrates the locking procedure for a belt acceleration greater than 0.5 g. The retaining spring 6 of the locking lever 4 should so be arranged with regard to its characteristic and initial tension force that as a result of the friction at the guide means 3 and 5, the refractive retractive force F_W (FIG. 1) and the inertia of the winding reel 2 produce a tilting of the locking lever 4 against the elastic force of the spring 6 in the locking position.

If the locking device 23 (FIG. 5) is not provided with a winding reel 2 which is in a separate housing 21 (FIG. 5), there is the possibility of having the locking device 25 23 at any desired position on the vehicle door pillar, and in the most favourable case of mounting it in conjunction with the guide fitment A. In this way the length of the expandable part of the belt 1 can be altered so that the maximum possible pre-displacement of the passenger can be utilised in the event of an accident.

All the above-described advantages can thus be achieved by subsequent installation in conjunction with automatic belt roll-up devices of known construction.

Claims

1. A vehicle safety belt retractor, comprising:

a. a housing;

b. a winding drum being rotatably mounted on said housing;

c. belt means attached to said winding drum for protraction and retraction with respect thereto;

d. clamp means for clamping said belt to prevent sudden protraction thereof, said clamp means including:

(i) a first fixed planar clamping surface;

(ii) a lever pivotally mounted at one end thereof; and

(iii) a second displaceable planar clamping surface carried by the intermediate portion of said lever for movement from a rest position toward said fixed clamping surface to clamp the belt therebetween;

e. resilient means coupled to said lever for biasing said lever for movement about its pivot in a direction to urge the second clamping surface carried by said lever away from said first clamping surface;

f. first guide means mounted adjacent said one end of said lever for guiding said belt means;

g. second, displaceable, guide means carried by the other end of said lever for entrainment of said belt means thereabout, and operating in response to preselected abnormal tension of said belt to pivot said lever and thereby move said second clamping surface toward said first clamping surface;

said belt means normally extending off said winding drum to said first guide means, past said pivot, thence between said clamping surfaces without contact therewith and thence over said second guide means whereby in normal operation the retractor allows always free winding and unwinding of the belt between said clamping surfaces without contact therewith, but where a predetermined abnormal tension on the belt applies a force to said lever via the second guide means to actuate said lever into its clamping position against the bias of said resilient means in a substantially normal direction with no wedging action, said planar clamping surfaces being substantially parallel to the plane of the web at the point of contact therewith.

2. Apparatus according to claim 1 wherein at least one of said clamping surfaces is pivotally mounted.

3. A vehicle safety belt retractor, comprising:

a. a housing;

b. a winding drum being rotatably mounted on said housing;

c. belt means attached to said winding drum for protraction and retraction with respect thereto;

d. clamp means for clamping said belt to prevent sudden protraction thereof, said clamp means including

(i) a first fixed planar clamping surface carried by said housing;

(ii) a lever pivotally mounted at one end thereof on said housing; and

(iii) a second displaceable planar clamping surface carried by the intermediate portion of said lever for movement from a rest position toward said fixed clamping surface to clamp the belt therebetween;

e. resilient means coupled to said lever for biasing said lever for movement about its pivot in a direction to move the second clamping surface carried by said lever away from said first clamping surface;

f. first guide means carried by said housing for guiding said belt means;

g. second, displaceable, guide means carried by the other end of said lever for entrainment of said belt means thereabout, and operating in response to preselected abnormal tension of said belt to pivot said lever and thereby move said second clamping surface toward said first clamping surface;

said belt means normally extending off said winding drum to said first guide means, past said pivot thence between said clamping surfaces without contacting same and thence over said second guide means whereby in normal operation the retractor allows always free winding and unwinding of the belt between said clamping surfaces without contact therewith, but where a predetermined abnormal tension on the belt applies a force substantially perpendicular to said lever to actuate said lever into its clamping position against the bias of said resilient means in a substantially normal direction with no wedging action, said planar clamping surfaces being substantially parallel to the plane of the web at the point of contact therewith;

said belt in its operative condition extending away fronm from said second guide means in a direction substantially perpendicular to its path as it approaches said guide means.

4. Apparatus according to claim 3 wherein said clamping surfaces are both pivotally mounted.

5. A seat belt clamp apparatus comprising:

a housing;

a lever pivotably mounted in said housing, said lever having a clamping position and a non-clamping position with respect to a seat belt which is movable through said clamp apparatus;

means biasing said lever to its non-clamping position;

means responsive to a force above a predetermined amounted applied to said belt in a first direction to move said lever toward said belt to its clamping position against the force of said biasing means;

clamping means provided on said lever for clamping said belt to resist movement of said belt in said first direction in response to said force above a predetermined amount;

first and second opposite surfaces on said clamping means;

means on said first surface of said clamping means defining a planar contact area for contacting said belt, said first surface normally being out of contact with said belt; and

means for pivotably mounting said second surface of said clamping means on said lever, said second surface of said clamping means being pivotable with respect to said lever about a pivot axis directly opposite to said contact area, whereby said contact area is moved into substantially parallel engagement with the major plane of said seat belt in response to said force above a predetermined amount, thereby resisting movement of said belt in said first direction.

6. The seat belt clamp apparatus of claim 5 including a planar clamping surface on said housing, said planar clamping surface on said housing cooperating with said planar contact area of said clamping means to provide clamping of said belt without any wedging action.

7. The seat belt clamp apparatus of claim 6 wherein said planar clamping surface is pivotally mounted on said housing.

8. The seat belt clamp apparatus of claim 5 wherein said clamping means is located adjacent to one end of said lever.