GB2057853A - Safety belt reeling device - Google Patents

Abstract

A safety belt reeling device comprises a winding reel (3) spooling a withdrawable belt, the reel being mounted on a rotatable shaft and being lockable against unreeling rotation by means of a blocking device, thereby to prevent further withdrawal of the belt, on sudden acceleration of the belt withdrawal. The locking takes place through at least one locking body mounted on an axle of the reel (3), the reel being so displaceably mounted in a housing (6) that the axle of the reel is displaced out of a normal position and into a locking position against the force of a spring on sudden acceleration of the belt withdrawal. The locking body comprises at least one locking part (4) which comes into engagement with a counterlocking part (6b) on the housing (6) in the locking position. The locking part (4) and the counterlocking part (6b) are constructed in such a manner that the contact region between them in the locking state is disposed at the belt withdrawal side of the reel (3) in the region of the tangent (21) from the belt withdrawal point ofthe reel as seen in the withdrawal direction of the belt. <IMAGE>

Description

SPECIFICATION Safety belt reeling device The present invention relates to a safety belt reeling device, in particular a device of the kind described in the specification of United Kingdom patent application No. 42504/77.

Reels for vehicle safety belts are known (United Kingdom patent specification No. 1 428111 in which the axle of the reel winding body is mounted to be displaceable against the force of a spring in such a manner that free rotation and thereby free withdrawal ofthe safety belt is possible during a normal operation, while the axle is displaced iaterally on abrupt acceleration of the withdrawal movement in such a manner that a locking part arranged on the winding body so engages a counterlocking part arranged on a housing that further rotation of the reel and thereby further withdrawal of the belt is prevented.

It is disadvantageous in known constructions of that kind that substantial lateral forces act on the reel axle during the locking and must be absorbed by the axle and corresponding guide parts of the housing.

This has the consequence that the axle and its bearings must be relatively large in size, which not only increases the overall size of the reeling device but also increases the mass to be moved and thereby reduces response sensitivity.

In the specification of the afore-mentioned United Kingdom patent application it is taught to so arrange the locking part at the reel and the counterlocking part at the housing for relief of the force transmission between the axle of the reel and the housing that the locking engagement occurs on the belt withdrawal side ofthe reel in an angular region (8) of about 120 starting about 10 before the belt withdrawal point as seen in the withdrawal direction.

Through this measure, it is achieved in particular cases that the entire locking forces are absorbed solely by the locking and counterlocking parts without lateral forces acting on the axle of the reel when displaced out of its normal position againstthe spring forces, the reel being virtually able to freely float in its retaining part.

It is the task of the present invention to further develop the teaching of the aforesaid patent application and to provide a reeling device in which the afore-mentioned effect is realised over the entire angular region. The present invention is based on recognition of the fact that through different choice of the circumference of the locking parts on the reel and the circumference ofthe reel itself, differences can exist, which in the locked state influence the disposition of the contact range of the locking and counterlocking parts. The present invention thus has the object of providing a reeling device with the facility of transferring the tension force in the locked state free of tilt through the locking and counterlocking parts thereby to relieve the axle and the bearing ofthe reel itself.

According to the present invention therefore, there is provided a safety belt reeling device comprising a housing and a safety belt reel provided with a belt, the reel being mounted in the housing to be rotatable relative thereto for reeling the belt onto or unreeling the belt from the reel and constrained to be so displaced against a resilient bias in a predetermined direction on unreeling ofthe belt from the reel at a rate of acceleration exceeding a predetermined value that the axis of the reel moves relative to the housing and the reel being provided with first and second engaging means, respectively, which are stationary relative to the housing and reel, respectively, and which are so interengaged on said displacement of the reel as to arrest rotation of the reel relative to the housing thereby to prevent further unreeling of the belt, the first and second engaging means being so arranged as to interengage in the region of that portion of the tangent to the point of departure of the belt from the reel that extends in the direction if withdrawal of the belt from the reel.

This arrangement ensures that the force, which is transmitted through the belt to be withdrawn and which in the locked state can assume substantial values, is fully absorbed by the first and second engaging means, while tilting or lever forces do not arise since the force is coincident with the pulling direction ofthe belt (tangent). An axle of the reel can therefore be guided free of force with the exception of small forces arising through the friction.

Preferably, the first engaging means comprises a single tooth disposed in said region and the second engaging means comprises a plurality of teeth arranged along a circular path for selective engagement with said single tooth. Expediently, that flank of said single tooth of the first engaging means which is engaged by a tooth of the second engaging means is so arranged as to define a positive angle with the radius of the addendum circle of the single tooth.

For preference, the housing is provided with a cover comprising mounting means mounting the reel, the mounting means comprising means defining an elongate recess and the reel being provided with bearing means engaged in the recess, the recess being defined in part by a guide surface cooperable with the bearing means to guide displace mentofthe reel.

Embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a schematic view of co-operating locking means provided on a reel and a housing in a reeling device according to one embodiment of the invention; and Fig. 2 is a view, similarto Fig. 1, of co-operating locking means in a reeling device according to another embodiment ofthe invention.

To facilitate understanding of the invention, the disclosure ofthe specification of United Kingdom patent application No. 42504/77 is hereby incorpo The drawing(s) originally filed was/were informal and the print here reproduced is taken from a later filed formal copy.

rated by reference and the reference numerals emp loyed in the description and drawings of the embod iments ofthe said application are used to designate corresponding features in the description and draw ings of the embodiments of the present invention.

Referring now in detail to the drawings of the embodiments ofthe present invention, there is shown partofa belt reeling device in which a belt 1 can be withdrawn upwardly from a reel 3. The reel is mounted on an axle (not shown) to be displaceable upwardly against the force of springs (not shown).

A locking part 4 in the form of a toothed rim is fastened laterally, preferably at both sides, to the reel 3. Atooth 6b is provided as a counterlocking part on a housing 6 provided with a corresponding recess forthe reel. Further constructional and operational details ofthe reeling device are provided by the specification ofthe said application.

As can be clearly recognised from Fig. 1 the tooth 6b acting as the counterlocking part lies exactly in the withdrawal direction 21 of the belt 1, which is coincident with the tangent to the point of departure of the belt from the reel as seen in the belt withdrawal direction. Itwill also be recognised that the entire force exerted on the belt 1 will be absorbed by the flank 6c of the tooth 6b and the corresponding flank of a tooth of the locking part 4 on the reel 3.

In order to spread the force transmission as far as possible over the entire surface and to obtain a secure detent locking, the tooth flank 6c is inclined through the positive flans angle a relative to a radius R emanating from the centre point of the reel and extending through the tip of the tooth 6b. By this measures it is achieved that, as already explained, tilting forces do not act on the reel itself even with the strongest pull on the belt 1 in direction of the arrow 21, so that the axle of the reel 3 can float freely without any guidance and without being exposed to lateral forces.

Fig. 1 also shows, by way of contrast, the angular 1200 region A-E (p) in which the counterlocking part can be disposed on the housing in accordance with the teaching of the said application No.42504,77.

The Fig. 2 shows a further form oftoothing forthe toothed rim 4, acting as the locking part, on the reel 3. The single counterlocking part on the housing is in the form of a tooth 6a, the toothed rim 4 and the housing 6 being only shown in part.

Claims (5)

1. A safety belt reeling device comprising a housing and a safety belt reel provided with a belt, the reel being mounted in the housing to be rotatable relative thereto for reeling the belt onto or unreeling the belt from the reel and constrained to be so displaced against a resilient bias in a predetermined direction on unreeling of the belt from the reel art a rate of acceleration exceeding a predetermined vaiue that the axis of the reel moves relative to the housing, the housing and the reel being provided with first and second engaging means, respectively, which are stationary relative to the housing and reel, respectively, and which are so interengaged on said displacement ofthe reel as to arrest rotation of the reel relative to the housing thereby to prevent further unreeling of the belt, the first and second engaging means being so arranged as to interengage in the region of that portion of the tangent to the point of departure of the belt from the reel that extends in the direction of withdrawal of the belt from the reel.

2. A device as claimed in claim 1, wherein the first engaging means comprises a single tooth disposed in said region and the second engaging means comprises a plurality of teeth arranged along a circular path for selective engagement with said single tooth.

3. A device as claimed in claim 2, wherein that flank of said single tooth of the first engaging means which is engaged by a tooth of the second engaging means is so arranged as to define a positive angle with the radius of the addendum circle of the single tooth.

4. A device as claimed in any one of the preceding claims, wherein the housing is provided with a cover comprising mounting means mounting the reel, the mounting means comprising means defining an elongate recess and the reel being provided with bearing means engaged in the recess, the recess being defined in part by a guide surface cooperable with the bearing means to guide displacement of the reel.

5. A safety belt reeling device substantially as hereinbefore described with reference to Fig. 1 or Fig. 2 ofthe accompanying drawings.