GB1560226A

GB1560226A - Belt winders for vehicle safety belts

Info

Publication number: GB1560226A
Application number: GB788277A
Authority: GB
Original assignee: Klippan NV SA
Current assignee: Klippan NV SA
Priority date: 1976-03-15
Filing date: 1977-02-24
Publication date: 1980-01-30
Also published as: ES456477A1; FR2344300A1; IT1072478B; DE2610870A1; JPS52111122A

Description

(54) BELT WINDERS FOR VEHICLE SAFETY BELTS (71) We, N.V. KLIPPAN S.A., a Belgian Body corporate, of Groenstraat 1, B-3044 Haasrode, Belgium, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to belt winders for vehicle safety belts.

Various belt winders are known which enable the safety belt or restraint strap to be drawn off the reel and over the user while the vehicle in which they are fitted is moving. When the belt has been fastened, tension is exerted on it by the winder, causing it to lie closely against the body. It is necessary for the shaft of the winder to be locked in the event of an accident, so that the belt cannot then be drawn out.

One known type of locking mechanism, hereinafter referred to as a vehicle-sensitive mechanism, is dependent on deceleration of the vehicle. A sensing member such as a pendulum, sphere or other inertia member is displaced when the vehicle is violently decelerated, and causes the shaft to be locked.

In another type of locking mechanism, hereinafter referred to as a belt-sensitive mechanism, locking of the winding shaft depends on the speed at which it revolves when the belt is drawn out, i.e. it depends on acceleration in drawing out the belt or on centrifugal force.

A proposed belt winder disclosed in German Patent Application No. P 24 35 050.3 has a special quick-locking action. When the belt is jerked out, a locking member which responds only to angular acceleration - i.e. jerking of the belt - is sure to engage a retaining member fixed to the casing immediately after the acceleration is imparted.

In one embodiment of the proposed winder an inertia ring is provided with two diametrically mounted pins on a side thereof and a locking member arranged between said side of the inertia member and the shaft has an edge arranged to engage the pin of the inertia member. The inertia member is a type of fly-wheel which, when the belt is drawn slowly out of the winder, has the same angular speed as the shaft which has an end of the belt fixed to it and the belt wound round it. The locking member-or in another embodiment two locking members-are also mounted on the above-mentioned pin in such a way, relative to the centrifugal forces at the shaft, that instead of turning about the said pin when the belt is drawn out they remain stationary relative to the shaft and inertia member and similarly assume the said angular speed.

Provided that a certain acceleration, of adjustable value, is not exceeded, the angular speed could theoretically assume larger and larger values without locking taking place. This means, advantageously, that the belt winder does not respond to centrifugal forces and certainly not so as to produce a locking action.

When there is angular acceleration, on the other hand, i.e. when the belt is drawn out abruptly, e.g. in the event of an accident, locking takes place immediately.

This effect is produced by the inertial member, which does not follow the abrupt increase in the angular speed of the shaft; there is therefore relative movement between the inertia member and the shaft, and the locking member mounted rotatably on the shaft is turned positively relative to the shaft. An end of the locking member then comes into engagement with a locking ring provided with internal teeth. The belt winder described is blocked immediately.

In an improved embodiment of the prior proposal locking is guaranteed whatever the momentary relative positions of two interengaging teeth, without any danger of the tips of the teeth breaking off or of the teeth jumping over one another.

This is achieved by using only one locking member, displaceable transversely to the belt winding shaft and provided with an internal cam follower surface opposite a curved surface. One cam surface is arranged opposite the shaft in such a way that the locking member can move in the opposite direction to the rotary movement of the shaft, before the completely locked position is reached. A control member which is rotatable about the axis of the shaft but immobilised in a radial direction is in engagement with the locking member through an aperture. Tests have shown this arrangement to have the advantage of preventing any breaking of the tips of the teeth or any jumping from tooth to tooth without any locking action.

The basic idea of this previous proposal is that it enables the locking member to move against the rotary direction of the shaft. In this way the tip of the locking member or a locking stop arranged at the tip or a projection has enough time to move into the base of the opposed tooth on a locking ring and to come into contact with the opposed stop. Experiments have shown that even the provision of one tooth or locking stop on the locking member is sufficient to ensure that a reliable locking action is always obtained. It is particularly preferable to provide the projection with the locking stop at the rear side as viewed in the direction of rotation of the locking member.

According to the invention, there is provided a belt winder for a vehicle safety belt, the winder comprising a rotatable shaft for winding up and extending the belt, a substantially U-shaped frame having side walls, a locking means constituted by a toothed rim of an aperture in one of the side walls, a locking member rotatable with the shaft and having an external surface including at least on locking stop, a plastics bearing mounted on the inside of said one wall to substantially close said aperture and to support the shaft, and acceleration responsive means responsive to an angular acceleration of more than a predetermined value being imparted to the shaft by extension of the belt to cause the locking member to move with respect to the shaft into locking engagement with the locking means to lock the shaft against rotation to prevent further extension of the belt.

Preferred belt winders in accordance with the invention and described in more detail below are intended to improve the abovedescribed proposed belt winder by making it more economic to produce, by giving the same or improved safety with reliable locking engagement, and by changing the locking time from the moment of initiating an accident until there is locking engagement.

In the proposed winder described above the locking means is a locking ring provided with internal teeth and welded or screwed onto the outside of a corresponding side wall of a corresponding frame. Considerable simplification and thus a more economic production method is obtained with the present invention by omitting the extra toothed ring and in its place using the toothed rim of the aperture in said one side wall of the frame, which arrangement is strong and rigid.

In the two proposed belt winders discussed at the beginning, with the toothed locking ring attached, an aperture of appropriate size in the side wall acted as a bearing. Since, in the present invention, this aperture is extended to form the toothed rim as mentioned above, the abovementioned plastics bearing is mounted on the inside of said one side wall of the frame.

The bearing may simply comprise a plate containing a hole of suitable size, the diameter of the hole being such that it can surround and centrally mount the outer circumference of the belt winding shaft.

Two embodiments of the present invention described in detail hereinbelow correspond approximately to the embodiments of the prior proposal mentioned above. In one embodiment of the invention two rotatable locking members are provided, while in the second embodiment there is only one locking member, which is arranged for sliding movement to engage the teeth on the rim of the aperture in the side wall of the frame.

Advantages obtained with the invention apply to both embodiments.

The bearing mounted inside said one side wall of the frame keeps the belt winding shaft centred and can provide the advantage that if a very heavy load is applied to the belt and thus to the belt winder in the event of an accident, the bearing may twist, yield to one side under the heavy load and become deformed, producing the locking action described above, where the locking stop or stops of the locking member come into engagement with the toothed rim of the aperture in said one side wall of the frame.

A second locking action can be produced under the same circumstances, according to embodiments of the invention described below. In the second locking action a radial outward movement of the bearing and thus of the appropriate end of the shaft, with a disc preferably attached to that end of the shaft, towards the toothed rim results in locking by virtue of frictional force between the disc and the toothed rim.

The acceleration responsive means preferably comprises an annular inertia member, a spring coupling the inertia member and the shaft whereby the inertia member is rotatable with the shaft, and at least one pin on a side of the inertia member facing towards the locking member, whereby upon an angular acceleration of more than the predetermined value being imparted to the shaft the spring permits the inertia member to rotate with respect to the shaft and the pin moves the locking member into locking engagement with the locking means.

The spring can preferably be exchanged for a different spring with a different spring constant. In this way the manufacturer can adiust the response time of the belt winder in a simple way, particularly so as to come closer to meeting the different requirements of various countries. An increase in the spring constant lengthens e.g. the time taken for the inertia member to make the locking member move to effect locking if the belt is suddenly pulled out. Thus, the time required for locking engagement between the locking member and the toothed rim is increased. Locking sensitivity can therefore be controlled by varying the spring constant and advantageously prevents premature locking of the winding means.

It is particularly desirable for the inter changeable springs to be of the same shape.

Since these are compact, mass-produced articles, the dealer need only stock different boxes, containing springs with different spring constants, for the various countries, according to their regulations. No other parts of the belt winder need be changed; only springs with different spring constants need be used to obtain the advantageous effects mentioned.

The invention will become more fully apparent from the following description, given by way of example, of two preferred embodiments thereof shown in the accompanying drawings, in which: Figure 1 is a perspective view of a frame of a first belt winder embodying the invention, the frame being shown provided with internally toothed locking means; Figure 2 is a perspective view of a winding shaft of the first belt winder with a disc fixed to it; Figure 3 is a perspective view showing the relative arrangement in space of two locking members of the first belt winder; Figure 4 shows an annular inertia member of the first belt winder; Figure 5 shows a strip-form leaf spring of the first belt winder; Figure 6 is a side elevation of the inertia member and spring of Figures 4 and 5; Figure 7 is a plan view of one of the locking members of Figure 3; Figure 8 is a side elevation of the winding shaft and disc of Figure 2; Figure 9 is a schematic view of the assembled first belt winder embodying the invention, in an unlocked condition; Figure 10 corresponds to Figure 9 but shows pins on the inertia member in engagement with the locking members; Figure 11 is a perspective view of a frame of a second belt winder embodying the invention, the frame being shown provided with internally toothed locking means; Figure 12 is a perspective view of a winding shaft of the second belt winder with a segmental disc fixed to it; Figure 13 is a perspective view showing the relative position in space of a locking member of the second belt winder, Figure 14 shows a disc-shaped inertia member of the second belt winder; Figure 15 shows a biassing spring of the second belt winder; Figure 16 shows a locking wheel of the second belt winder; Figure 17 is a perspective view of a holding ring of the second belt winder; and Figure 18 is a sectional view through the second belt winder with the segmental disc partly broken away and with the locking member in engagement with the teeth of the internally-toothed locking means fixed with respect to the frame.

Figures 1 to 5 constitute an exploded perspective view of a belt-sensitive locking mechanism of a first belt winder embodying the invention. The belt, winding spring and other parts of the belt winder well known in the art and not directly relevant to the invention are not shown.

The illustrated belt winder comprises a substantially U-shaped frame 1 as shown in Figure 1. One side wall of the frame 1 constituted by one of the limbs of the U is provided with internally-toothed locking or abutment means constituted by a toothed rim 3 of an aperture therein. The toothed rim 3 is therefore fixed with respect to the frame 1 and with respect to a casing (not shown) of the belt winder. A bearing constituted by a plate 2 having a hole therein is positioned on the inside of the side wall of the frame I having the abutment means 3. A side wall of the frame 1 constituted by the other limb of the U is provided with a hole (not referenced).

When the belt winder is assembled a winding shaft 4, having a disc 5 mounted at one of its ends, is inserted in the two abovementioned holes in the direction of the axis shown by a chain-dotted line. The disc 5 carries a slotted cylindrical member 7 at the centre of its face remote from the shaft 4, and two pins 6 diametrically on opposite sides of the member 7.

A respective one of a pair of locking members 9 is engaged with each of the pins 6 by virtue of each pin 6 extending through a hole 9c in the associated locking member whereby the locking members are pivoted to the disc 5 and are positioned as shown in Figure 9. As can be seen from Figure 7 each hole 9c, being the pivot point, is provided centrally and at the centre of gravity of the associated locking member 9, and a hole 9b is provided in the left half of the member 9 as shown in Figure 7 deliberately to destroy its equilibrium relative to the pivot point. Each locking member 9 has an appropriate arcuate shape to fit the diameter of the disc 5, and its curved outer edge has at its left hand end as shown in Figure 7 a plurality of locking teeth constituting locking stops.

An edge 9d to engage a pin 12 on an annular inertia member 10 is provided on the left hand part of the inner edge of each locking member 9 as shown in Figure 7.

Although the illustrated arrangement with two locking members 9, as shown in Figures 1 to 10, is preferable for the present embodiment, it should be appreciated that, instead, three, four or more locking members could be employed.

A strip-form leaf spring 8 having a spring constant selected in accordance with the desired sensitivity of the belt winder and its capacity to respond to a desired acceleration imparted to the belt is inserted into a desired pair of opposed slots 11 inside the annular inertia member 10. The end of the inertia member 10 facing the disc 5 carries two said pins 12 arranged diametrically of one another relative to the centre of the member 10. When the locking mechanism shown in Figures 1 to 5 is assembled, the pins 12 engage through the space between the two locking members 9 as shown in Figure 9, there being no contact between the locking members 9 and the pins 12; and the spring 8 enters the slot in the cylindrical member 7 whereby the inertia member 10 is rotatable with the shaft 4.

The desirability of having a relatively massive inertia member 10 should be pointed out. In view of the property of the spring material constituting the spring 8 and the arrangement of the spring, a relatively heavy inertia member 10, which also acts as a fly-wheel, is desirable. The locking members 9 too, which may take up nearly half the circular area of the disc 5, may be stable and strong as compared with known apparatus.

The manner of operation of the belt winder described above will now be explained. Assume that the belt is abruptly pulled from the winder, for instance due to the inertia of the wearer acting on the belt consequent to an abrupt deceleration of the vehicle. Provided the angular acceleration thereby imparted to the shaft 4 is greater than a predetermined value determined by the spring constant of the spring 8, the spring 8 permits rotation of the inertia member 10 with respect to the shaft 4, as a result of which the pins 12 engage the locking members 9 as shown in Figure 10.

The line joining the pins 12 is then inclined to the horizontal orientation of the line joining them in their prior condition shown in Figure 9. The pins 12 pivot the locking members 9 about the pins 6 relative to the shaft 4 to an extent sufficient that their teeth engage with and fit into the teeth 3. The shaft 4 is therefore locked against further rotation whereby the belt cannot be further extended from the winder.

The bearing 2 is shown in Figures 9 and 10 as being screwed onto the inside of the side wall of the U-shaped frame 1. A circular line drawn inside the toothed rim 3 in Figures 9 and 10 indicates the rim of the disc 5 mounted to the shaft 4.

By using plastics as the material for the bearing 2, the hole therein (see Figure 1) accommodating the shaft 4 may buckle if there is an accident. The rim of the disc 5 will then also come into frictional engagement with the toothed rim 3, producing a further locking action in addition to the described locking action between the teeth of the locking members 9 and the toothed rim 3.

Figures 11 to 18 constitute an exploded perspective view of the locking mechanism of a second belt winder embodying the invention. As will be more fully explained below, the locking mechanism in this case is both belt-sensitive and vehicle-sensitive.

Components in Figures 11 to 18 which are identical or similar to corresponding components in Figures 1 to 10 are identified by the same references and will only be further described in so far as they differ from the corresponding components in Figures 1 to 10.

The disc 5 is segmental and carries the slotted cylindrical member 7 at the centre of its face remote from the winding shaft 4.

The disc comprises in its lower half as shown in Figure 12 a more than semicircular extension or a thick segment 13, the top of which forms a cam surface 20.

In this embodiment there is only one locking member 9, the member being slidable transversely of the shaft 4. Figure 13 shows the locking member 9. The locking member 9 is given an appropriate arcuate shape to fit the diameter of the segmental disc 5 or the internal radius of the locking rim 3 fixed with respect to the frame and therefore with respect to a casing (not shown) of the belt winder; i.e. it has an external curved surface 14. A projection 9k is provided at the right hand end of the locking member 9 as shown in Figure 13 and carries the engaging tooth 9g which constitutes a locking stop. A rest stop 9h is arranged at the left hand end of the locking member 9 as seen in Figure 13g, i.e. in front as seen in the direction of rotation.

The locking member 9 rests on the cam surface 20 of the segmental disc 5 shown in Figure 12 and can move freely in the plane of the disc 5 in a slidable, non-pivoting sense.

Figure 14 shows a disc-shaped inertia member 10, which is constructed as a flywheel and provided with a pin 15 which is designed to engage in a cutout 22 in an edge of the locking member 9. On the opposite side of the inertia member 10 to the projection 15 are provided a small pinshaped lug 16 and a slot 17. The slot 17 is defined between two small raised portions and is offset diametrically from the lug 16 by about 1200.

Figure 15 shows a spring 8 specially designed for this embodiment of the invention. A projecting angular portion 8' and a loop 8 are provided at one end of the spring 8. When assembled, the loop 8" is placed around the lug 16.

Figure 16 shows a locking wheel 11 in perspective. The locking wheel 11 is coupled to the inertia member 10 by a detent or friction coupling by means of the spring 8. Figure 17 shows a holding ring 12 having adjusting cylinders 18 arranged in it on opposite sides, the cylinders containing small inert members or sensors in the form of spheres 19.

The exact shape of the locking member 9 will now be more fully explained with reference to Figure 13. Opposite the outer curved surface 14, which is interrupted in the centre at the centre of gravity of the locking member 9 by the cutout 22, is a cam follower surface 9 which, in this case, is straight. A projection 9k is provided at the right hand end of the locking member 9, i.e.

at the rear of locking member as seen in the direction of rotation. The tooth 9g constituting the locking stop is arranged on the smaller, front side of the projection 9k and a locking surface 91 on the larger, rear side. At the opposite end of the locking member 9, i.e. at the front end, is a projecting lug 91, a front surface of which forms the rest stop 9h and a rear surface of which forms an auxiliary locking stop 9m.

The shape of the spring 8 can be seen clearly from Figure 15. One end of the spring 8 lies in the slot in the cylindrical member 7 and is then wound around the cylindrical part 7 in a spiral until the other end passes laterally through the slot 17 in the attached inertia member 10, after which it is bent twice at about 90 , forming the angular portion 8' at the other extreme end, and fixed by the loop 8" to the lug 16 on the inertia member 10. The same advantageous effect could be otained with an evenly curved or harmonically bent spring, instead of using the above-mentioned angle of 90".

The angular portion 8' of the spring 8 is latched in and locked between internal teeth 11' of the locking wheel 11, which carries additional teeth 11" on the outside.

When the arrangement is assembled the holding ring 12 is pushed over the locking wheel 11 so that the sensors 19 are opposite the teeth 11".

A holder for the locking wheel 11, which is rotatable about the axis of the shaft 4 and the segmental disc 5 and radially immobilised, i.e. of fixed length and radius, is formed by the inertia member 10 with projection 15.

When the arrangement is assembled, the locking member 9 slides over an annular surface 21 inside the rim of locking teeth 3 fixed with respect to the casing. A thin plastics disc may be provided here to reduce friction or to avoid metal to metal contact.

The belt winder of Figures 11 to 18 is responsive to an abrupt extension of the belt to lock the belt against further extension in substantially the same manner as the belt of Figures 1 to 10, except that the single locking member is caused to slide by the pin 15 to engage the teeth 3.

As described above for the belt winder of Figures 1 to 10, for the belt winder of Figures 11 to 18 also an increase in the spring constant of the spring 8 lengthens the time taken by inertia member 10 to stop its movement relative to the disc 5 when the belt has been pulled out suddenly; the result is that more time is required to move the locking member 9 into engagement with the teeth 3. The spring constant of the spring 8 can thus easily be adjusted to control the locking sensitivity and to prevent premature locking of the belt winder.

As mentioned above, the belt winder of Figures 11 to 18 is also vehicle-sensitive. In response to a blow to the vehicle, e.g. an impact or over-turning of the vehicle, a locking action determined by the movement of the vehicle (as distinct from movement of the belt) takes place by means of the sensors 19 in the holding ring 12. The locking action takes place as follows. A sensor 19 in the holding ring 12 moves out of the associated adjusting cylinder 18 and inwardly onto the external teeth 11" of the locking wheel 11.

This stops the locking wheel 11, which is preferably made of plastics. As a result of its engagement with the angular portion 8' of the spring and slot 17, the wheel 11 stops rotation of the inertia member 10, which immediately moves the locking member 9 into the locking position described above, by means of the pin 15 and cut-out 22. A force is now exerted from the stationary locking member 9 through the inertia member 10 and back to the locking wheel 11. The external teeth 11' of wheel 11 could in this event be broken off because of the engagement with the sensor 19, were it not for elastic bending back of the angular portion 8' of the spring 8, which interacts with the internal surface of the locking wheel 11 or, in a modification of the second embodiment constituted like the first embodiment, with arresting grooves 1 Ia, 1 Ib. In this way the angular portion 8' of the spring 8 can jump from one tooth or groove 1 lea to the next tooth or groove 1 lb, thereby synchronising the locking of the vehiclesensitive mechanism with the belt-sensitive mechanism. Accordingly, the locking wheel 11 continues to be turned like a ratchet relative to the now stationary inertia disc 10.

WHAT WE CLAIM IS: 1. A belt winder for a vehicle safety belt, the winder comprising a rotatable shaft for winding up and extending the belt, a substantially U-shaped frame having side walls, a locking means constituted by a toothed rim of an aperture in one of the side walls, a locking member rotatable with the shaft and having an external surface including at least one locking stop, a plastics bearing mounted on the inside of said one wall to substantially close said aperture and to support the shaft, and acceleration responsive means responsive to an angular acceleration of more than a predetermined value being imparted to the shaft by extension of the belt to cause the locking member to move with respect to the shaft into locking engagement with the locking means to lock the shaft against rotation to prevent further extension of the belt.

2. A belt winder according to claim 1, wherein the acceleration responsive means comprises an annular inertia member, a spring coupling the inertia member and the shaft whereby the inertia member is rotatable with the shaft, and at least one pin on a side of the inertia member facing towards the locking member, whereby upon an angular acceleration of more than the predetermined value being imparted to the shaft the spring permits the inertia member to rotate with respect to the shaft and the pin moves the locking member into locking engagement with the locking means.

3. A belt winder according to claim 2, wherein the spring is coupled to the shaft by way of a cylindrical member fixed with respect to the shaft.

4. A belt winder according to claim 2 or claim 3, wherein the spring is removably fitted in the winder whereby it can be replaced by a different spring with a different spring constant.

5. A belt winder according to any one of claims 1 to 4, wherein said external surface of the locking member is curved.

6. A belt winder substantially as herein described with reference to Figures 1 to 10 of the accompanying drawings.

7. A belt winder substantially as herein described with reference to Figures 11 to 18 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. portion 8' of the spring 8, which interacts with the internal surface of the locking wheel 11 or, in a modification of the second embodiment constituted like the first embodiment, with arresting grooves 1 Ia, 1 Ib. In this way the angular portion 8' of the spring 8 can jump from one tooth or groove 1 lea to the next tooth or groove 1 lb, thereby synchronising the locking of the vehiclesensitive mechanism with the belt-sensitive mechanism. Accordingly, the locking wheel 11 continues to be turned like a ratchet relative to the now stationary inertia disc 10. WHAT WE CLAIM IS:

1. A belt winder for a vehicle safety belt, the winder comprising a rotatable shaft for winding up and extending the belt, a substantially U-shaped frame having side walls, a locking means constituted by a toothed rim of an aperture in one of the side walls, a locking member rotatable with the shaft and having an external surface including at least one locking stop, a plastics bearing mounted on the inside of said one wall to substantially close said aperture and to support the shaft, and acceleration responsive means responsive to an angular acceleration of more than a predetermined value being imparted to the shaft by extension of the belt to cause the locking member to move with respect to the shaft into locking engagement with the locking means to lock the shaft against rotation to prevent further extension of the belt.