GB2222068A

GB2222068A - Belt tightener

Info

Publication number: GB2222068A
Application number: GB8919236A
Authority: GB
Inventors: Michael Grabinski
Original assignee: Autoflug GmbH
Current assignee: Autoflug GmbH
Priority date: 1988-08-24
Filing date: 1989-08-24
Publication date: 1990-02-28
Also published as: GB8919236D0; IT8921548A0; DE3828637C2; DE3828637A1; FR2636025A1; SE8902724D0; IT1231507B; SE8902724L

Description

1 54581.503 Belt tightener 2" 220 68 It- The invention relates to a

tightener for safety belt reeling means.

It is known to provide such a tightener having a cable drive which can be actuated in the event of a crash, the cable being wound round a cable reel connectible in form-locking manner to the belt winding shaft of the belt reeling means via a locking member mounted on the cable reel. The locking member is radially movable in order to engage in coupling teeth provided on the belt winding shaft.

A tightening device of this kind is known from DE-OS 34 07 378; on the cable reel is provided an eccentrically mounted locking member which, in the event of actuation, is capable of being pivoted radially outwards counter to the force of a spring which biases the locking member in its resting position, and when the locking member is pivoted out it engages in the teeth coupled to the winding shaft of the belt reeling means and thus produces a form-locking connection between the cable reel and the belt winding shaft of the belt reeling means. The conditions of mounting and mass of the locking member are designed so that in the event of actuation the locking member will lag behind the rotation of the cable reel because of its inherent inertia and as a result of its eccentric mounting will be pivoted radially outwards.

Such an arrangement of the coupling connection between the belt tightener and the belt reeling means has the disadvantage that the response threshold of the locking member is difficult to determine, since initially the cable reel has to undergo a certain rotational acceleration before the response threshold of the locking member is reached with respect to the pivoting out of said locking member; consequently, some 2 of the limited drive movement for the cable reel cannot be converted into a winding movement for the belt winding shaft.

According to the invention there is provided a tightener for safety belt reeling means, comprising a cable arranged to be actuated in the event of a crash to turn a cable reel, a locking member mounted on the cable reel and movable to a position locking the cable reel to a belt winding shaft of the belt reeling means, and a control element movable relative to the cable reel to cause the locking member to move to its locking position, said control element being arranged to be acted upon by a portion of the cable which extends away from the cable reel.

With such an arrangement the locking operation of the locking member can be initiated in defined manner independently of the rotational acceleration of the cable reel. The movement of the locking member to the locking position may for example be a radial movement in which the locking member engages in coupling teeth provided on the belt winding shaft.

The portion of the cable extending away from the cable reel is preferably guided in a bent configuration over an abutment of the control element in such a way that the start of the tightening movement initially causes the drive cable to be pulled straight, eliminating the bent configuration, as a result of which the drive cable moves the control element relative to the cable reel, so that the control element in turn, by its action on the locking member, deflects said locking member into the locking position.

This has the particular advantage that the control process for the locking member is shifted forwards to before the start of the rotation of the cable reel, so that the reaction times are advantageously shortened. A further advantage which arises is that the cable reel and the locking member mounted on it are not subject to 11 3 any working load during the movement of the locking member into the locking position. Only when the locking member is ready for engagement in the coupling teeth is there a rotary movement of the cable reel, because of the unwinding of the cable from the cable reel, with the result that the cable reel is immediately coupled to the belt winding shaft.

According to one embodiment of the invention, between the control element and locking member there is a bell crank lever, on one arm of which the control element acts as it is shifted under the effect of the drive cable, whilst the other arm of the lever, during the resulting pivoting of the bell crank lever, then moves the locking member into its locking position.

A particularly advantageous effect is obtained when the corresponding projection of the control element cooperating with the bell crank lever and the bell crank lever itself are made of resilient material. If the locking teeth of the locking member and the coupling teeth of the belt winding shaft are not congruent at the moment of deflection of the locking member, the locking member is subjected to bias, as a result of the resilient action of its actuating members in the form of the bell crank lever and the projection of the control element, so that immediately as the cable reel begins to rotate and consequently the position of the teeth relative to each other is corrected, the locking member is moved into the locking position.

According to one embodiment of the invention, there is also a spring which biases the locking member into its resting position, so that under the effect of this spring the locking member is returned to its starting position after the tightening operation has ended. This is to meet the requirement that the mechanics of the belt reeling means as such should not be affected by the tightening means after the tightening operation has ended.

4 Finally, in a preferred embodiment, there is provided a viewing window in the housing of the tightening device and a function indicator on the control element, to enable the condition of the tightening device to be determined from outside, because after the actuation of the tightening device and the resulting movement of the control element, the function indicator provided on the control element comes to rest in the region of the viewing window in the housing.

A preferred embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which:- Fig. 1 is a diagrammatic sectional view of the coupling components of a belt tightening device with the locking member in the unlocked position; Fig. 2 shows the device of Figure 1 in an intermediate stage after actuation of the tightening device; Fig. 3 shows the device of Figure 1 with the locking member locked; and Fig. 4 shows the device of Figure 1 after the tightening movement has ended.

Mounted on a projection 10 of the belt winding shaft of belt reeling means (not shown in detail) is a cable reel 11 which is surrounded on its outer circumference by coupling teeth 12 formed on the belt winding shaft in the plane of the cable reel 11. The belt tightening device including the cable reel 11 is enclosed by a housing 13.

A drive cable 14 is wound several turns around the cable reel 11 and from here it is guided, in a bent configuration, through an opening 16 formed in a control element 15 which is mounted on the housing 13 and movable relative to the cable reel 11, which is stationary in the resting position, to a housing exit 17, from where it is attached to a drive means (not shown in detail) which can be actuated in the event of a ZI i crash. The opening 16 in the control element 15 forms a rounded abutment 18 for the drive cable 14 which is passed around it in a bent configuration.

In the cable reel 11, in an opening 19, there is provided a locking member 20 which is movable radially outwards to a position protruding beyond the circumference of the cable reel 11, and this locking member 20 engages around the shaft projection 10 which acts as a guide therefor. Between a projection 21 of the locking member 20 and the cable reel body 11 there is supported a spring 22 which is arranged in a slot 23 extending longitudinally of the locking member 20, the projection 21 of the locking member extending into said slot 23. The spring 22 biases the locking member 20 into its unlocked resting position. At one end, the locking member 20 has locking teeth 24 which are arranged for engagement in the coupling teeth 12 of the - belt winding shaft, and at its other end the locking member 12 is acted upon by a bell crank lever 25 arranged on the cable reel 11, one arm 26 of which, being suitably shaped, abuts on the locking member 20, whilst the other arm 27, projecting beyond the circumference of the cable reel 11, extends into the path of movement of the control element 15. For cooperation with the arm 27 of the bell crank lever 25 the control element 15 has an arm-like projection 28.

The control element 15 is fixed to the housing 13 via a shear pin 29, whilst the cable-reel 11 is also connected to the housing 13, secured in its resting position, by means of two shear pins 30 of its own.

Finally, the housing 13 also has a viewing window 31 and the control element 15 has a function indicator 32, the function indicator 32 being arranged on the control element 15 so that after the movement of displacement of the control element 15 has ended (Figures 2 to 4), the function indicator 32 comes to rest in front of the viewing window 31.

6 The belt tightener operates as follows. Starting with the component parts of the tightener in the resting position shown in Figure 1, the actuation of the drive means in the event of an accident produces a tensile force acting on the drive cable 14 in the direction of the arrow 33. Since initially the cable reel 11 is secured motionless, the tensile force acting on the drive cable leads to stretching of the cable, straightening out its bent path through the control element 15. As a result of the force component thus acting in the direction of displacement of the control element, the control element 15 is moved in the direction of the arrow 34 and the shear pin 29 is broken and as shown in Figure 2 the control element presses with its projection 28 on the arm 27 of the bell crank lever 25.

If the locking teeth 24 of the locking member 20 on the one hand and the coupling teeth 12 of the belt winding shaft on the other hand are in a corresponding position, the pivoting of the lever 25 leads directly to the locking member 20 being moved into the coupling teeth 12. In Figure 2, however, the starting point is that no such corresponding position of the teeth 12, 24 has been achieved and in this case, because of the resilience of the bell crank lever 25 and of the projection 28 of the control element 15, a bias is produced acting on the locking member 20 and directed in the direction of movement of the locking member. 30 As soon as slight displacement of the teeth 24, 12 relative to each other takes place as a result of the rotary movement of the cable reel 11 which occurs after the stretching of the drive cable 14, the bell crank lever 25 pushes the locking member 20 outwards, counter to the action of the spring 22, into the locking position shown in Figure 3. As a result of the construction of the teeth 24, 12 as well, the locking 7 member is pulled so far into the locking position that the bell crank lever 25 pivots fully into the contour of the cable reel 11, so that after the tightening movement has ended, the cable reel is freely rotatable on the shaft projection 10, without the bell crank lever 25 again coming into any inhibiting contact with the control element 15.

After the tightening movement has ended, the spring 22 biased by the deflection of the locking member 20 causes the locking member 20 to return into the contour of the cable reel 11, so that the coupling connection of the cable reel to the belt winding spindle is released and consequently the normal functional behaviour of the belt reeling means can take effect.

To enable the user to be sure that the tightening device has been used without any problem, the movement of the control element causes a function indicator formed thereon to come to rest in front of a viewing window arranged in the housing of the tightening means, so that it is thus possible to check the functional position.

It is to be clearly understood that there are no particular features of the foregoing specification, or of any claims appended hereto, which are at present regarded as being essential to the performance of the present invention, and that any one or more of such features or combinations thereof may therefore be included in, added to, omitted from or deleted from-any of such claims if and when amended during the prosecution of this application or in the filing or prosecution of any divisional application based thereon. Furthermore the manner in which any of such features of the specification or claims are described or defined may be amended, broadened or otherwise modified in any manner which falls within the knowledge of a person skilled in the relevant art, for example so as to encompass, either implicitly or explicitly, equivalents

8 or generalisations thereof.

^1 9

Claims

Clains is 1. A tightener for safety belt reeling means, comprising a cable

arranged to be actuated in the event of a crash to turn a cable reel, a locking member mounted on the cable reel and movable to a position locking the cable reel to a belt winding shaft of the belt reeling means, and a control element movable relative to the cable reel to cause the locking member to move to its locking position, said control element being arranged to be acted upon by a portion of the cable which extends away from the cable reel.
2. A tightener as claimed in claim 1, wherein the portion of the cable extending away from the cable reel is guided in a bent configuration over an abutment formed on the control element.
3. A tightener as claimed in claim 2, wherein the cable passes through an opening formed in the control element.
4. A tightener as claimed in claim 1, 2 or 3, wherein the control element has a projection arranged to act on the locking member.
5. A tightener as claimed in any preceding claim, wherein between the locking member and the control element, a bell crank lever is pivotally mounted on the cable reel, the bell cra nk lever having one arm arranged to be acted upon by the control element and another arm arranged to act on the locking member.
6. A tightener as claimed in claims 4 and 5, wherein the projection of the control element and the bell crank lever are resiliently deformable.
7. A tightener as claimed in any preceding claim, wherein the locking member arranged on the cable reel is spring-loaded in its resting position.
8. A tightener as claimed in any preceding claim, wherein the control element is fixed to the housing of the tightener by means of a shear element.
9. A tightener as claimed in any preceding claim, wherein the cable reel is fixed to the housing of the tightener by means of one or more shear elements.
10. A tightener as claimed in any preceding claim, wherein the housing of the tightener has a viewing window and the control element has a function indicator capable of being viewed through the window.
11. A tightener for safety belt reeling means, substantially as hereinbefore described with reference to the accompanying drawings.

Published 1990 &tThePatentOffice. State House. 613!7 t Righ Holburn. London WC1R 4TP.Furthercoplas Maybe obtAIn9dftTft The Patent Mee' Sales Branch, St Mary Cray, Orpulgwn. Kgp.t IBRS 3RD. Printed by Multiplex techniques ltd. St Mary Cray, KOM Con- 1187