GB2247154A - Safety belt retractor for a vehicle - Google Patents

Abstract

A retractor for a vehicle safety belt in which the reel is provided with end discs (12, Figs. 3 and 5) having external ratchet teeth (14) engageable in locking elements (19) in openings (16) formed in side plates 18 of the frame of the retractor. The reel is mounted for rotation and limited transverse motion by means of a cantilevered spring at each of its ends, this spring including a first radial arm 22 which is passed around an anchoring pin 24 and is integrally formed with a second arm 26 and a third arm 28. The free end of the third arm 28 is inturned and is anchored at 30 in the frame. The inturned end of the first arm 22 is engaged in an aperture in a plastics material button (34) engaged in an aperture in the discs at the associated end. <IMAGE>

Description

SAFETY BELT RETRACTOR FOR A VEHICLE The present invention relates to a safety belt retractor for a vehicle, and in particular to a so-called frame-locking safety belt retractor.

There are many known forms of such retractor, for example as disclosed in GB-A-1592713, EP-A-112032 and 112033 and these essentially comprise a frame having two parallel spaced apart frame plates, each provided with an opening, the openings each having inwardly directed locking elements thereon, a reel mounted for rotation in said frame about an axis normal to said parallel frame plates, said reel being spring-urged in one rotational sense to reel a safety belt thereon and being rotatable in the opposite sense to unwind the belt therefrom by the belt being pulled, arresting means to arrest rotation of the reel in said opposite direction, when the acceleration/deceleration of the vehicle or the rate of unwinding of the belt, exceed predetermined values, discs mounted on said reel, one in each of said openings, tooth formations on the peripheries of the discs and means for mounting the reel for rotation and for movement between a disengaged position, in which the discs are free to rotate, and an engaged position in which the teeth on the discs engage the locking elements on the openings, upon the arresting means being actuated and the belt tension pulling the reel against a resilient force from the disengaged position.

When the reel has thus been pulled to one side, the teeth on the discs engage against the locking means, which again are often in the form of teeth, and this completely arrests movement of the reel, thereby restraining movement of a passenger in the vehicle.

In the known arrangements there are many different forms of mounting the reel which permits both its rotation and its sliding motion perpendicular to the axis of rotation to the locked position. GB-A-1592713 shows an arrangement in which a bearing block is slidable against the action of a coil tension spring and EP-A-112032/3 have a rather complex arrangement involving a bearing boss which is urged against a "coathanger" shaped spring. Other structures involve the use of a bearing which is actually destroyed during the lateral movement of the reel.

None of these structures is entirely satisfactory insofar as they tend to be rather expensive and are certainly not reusable in the case of the last described construction.

It is now proposed, according to the present invention, for the means for mounting the reel to comprise two cantilevered spring mountings, one at each end of the reel, each spring mounting comprising a first arm engaged at a point on the frame and extending radially inwardly therefrom and an inturned end portion which provides the bearing permitting rotation.

Such a structure can be made relatively inexpensively and can, nonetheless, work very satisfactorily.

Preferably the inturned portion engages in a plastic "button" which is itself engaged in an aperture in its associated disc on the reel. If the button is made of material such as PTFE, the bearing can operate very satisfactorily.

The two cantilevers each preferably comprise second and third arms formed integrally with the first arm, the second arm extending generally parallel to the first arm and he third arm extending along a different radius, for example, approximately perpendicular to the radius of the first and second arms, the third arm having, at its free end, a further inturned portion engageable at a second location on the housing.

Preferably, at the point where the first and second arms meet, they pass round a pin on the frame forming said point on the frame.

The means for arresting the rotation of the reel may comprise a steering disc rotatable with the reel, a ratchet wheel mounted for limited rotation with respect to said steering disc and acceleration/deceleration sensitive member such as a ball and pivotal lever engageable with the teeth of the ratchet wheel on acceleration, internal ratchet teeth on said steering disc, a spring-urged pawl normally out of engagement with said internal ratchet teeth and an abutment on said ratchet wheel engageable with said pawl to urge it into engagement with the internal ratchet teeth on the steering disc to prevent rotation of said steering disc upon stopping of rotation of said ratchet wheel.

Additionally the ratchet wheel may have associated therewith an inertia weight so that, upon the unwinding of the reel exceeding a certain rotational speed, the ratchet wheel is rotationally displaced relative to the steering disc whereby the abutment again engages the pawl.

The steering disc preferably has a sliding anchor pin engageable in a radial slot in the frame, whereby permitting translational movement of the steering disc and ratchet wheel with the reel upon arresting of rotation of the reel.

In order that the present invention may more readily be understood, the following description is given, merely by way of example, reference being made to the accompanying drawings in which: Figure 1 is an end elevation of part of the ratchet wheel broken away showing the arrangement in the unlocked position; Figure 2 is a similar view showing the arrangement in the locked position; Figure 3 is a similar view to Figure 1 but showing the ratchet wheel and steering disc broken away; Figure 4 is a view similar to Figure 3 in the locked position; and Figure 5 is an enlarged cross-section through the assembly of Figures 1 to 4.

If reference is now made to Figures 1 and 5, a presently preferred embodiment of retractor of the invention is illustrated. Figure 5 illustrates the reel 10 having conventional end discs 12, each provided with external ratchet teeth 14 for engagement in a locking element(s) 19 in an opening 16 formed in side plates 18 of the frame of the retractor. According to the invention, as particularly seen in Figure 1 and Figure 2, the reel 10 is mounted for rotation and for limited transverse motion by means of a cantilevered spring indicated by the general reference numeral 20. This spring includes a first radial arm 22 which is passed around an anchoring pin 24 and is integrally formed with a second arm 26 and a third arm 28, the arms 22 and 26 normally running adjacent and parallel to one another and the arm 28 at an angle somewhat less than 900 relative to the arm 26.

The free lower end of the third arm 28 is inturned and is anchored at 30 to the frame 18. Similarly the inturned end 32 of the first arm 22 is engaged in an aperture in a plastics material button 34 engaged in an aperture in the discs 14 at each end. Mounted for rotation about the same axis is a steering disc 36 having an annular flange 37 provided, on its inner surface, with ratchet teeth 38. These ratchet teeth are engageable by a pawl when the pawl is rotated against the action of a pawl return spring (not shown) to the position in Figure 2.

Mounted outside and beyond the steering disc 36 is a ratchet wheel 40 having ratchet teeth 42 on the exterior surface, these being engageable by a conventional inertia ball arrangement 44 including a movable ball 46 and a pivoted lever 48 engageable with the ratchet teeth 42 upon a sharp deceleration or acceleration being detected. Mounted on the interior surface of the ratchet wheel 40 is an inertia weight (not shown) having associated therewith an abutment member 50 engageable with the pawl 39.

Figure 2 shows a circumstance in which the reel has been unwound very quickly, thereby leaving the inertia member "behind" as the reel and with it the ratchet wheel 40 rotate.

This causes the abutment member 50 to urge the pawl 39 to the position illustrated in Figure 2, thereby arresting motion of the steering disc 36.

The steering disc is also provided with an axially extending pin 52 engageable in a slot 54 in the frame. Upon arresting rotation of the steering disc 36, the reel continues to try to rotate but is stopped from doing so by the pin 52 being engaged in the slot 54. The tension in the belt (not shown) thereby causes the whole assembly to move upwardly and to the left slightly as shown in Figure 2 along a direction determined by the angle of the slot 54. It will be seen that the first arm 22 of the spring 20 at this stage separates from the second arm 26.

If reference is now made to Figures 3 and 4, the ratchet teeth 14 on the end disc 12 can be seen as spaced from further female ratchet teeth 19 extending into the opening at 16 in the frame 18. As shown in Figure 4 because the whole assembly has moved upwardly and to the left as determined by the slot 54, the teeth 14 engage in the teeth 19 thereby preventing any rotation of the reel.

Claims (9)

1. A safety belt retractor for a vehicle, comprising a frame having two parallel spaced apart frame plates, each provided with an opening, the openings each having inwardly directed locking elements thereon, a reel mounted for rotation in said frame about an axis normal to said parallel frame plates, said reel being spring-urged in one rotational sense to reel a safety belt thereon and being rotatable in the opposite sense to unwind the belt therefrom by the belt being pulled, arresting means to arrest rotation of the reel in said opposite direction, when the acceleration/deceleration of the vehicle or the rate of unwinding of the belt, exceed predetermined values, discs mounted on said reel, one in each of said openings, tooth formations on the peripheries of the discs and means for mounting the reel for rotation and for movement between a disengaged position, in which the discs are free to rotate, and an engaged position in which the teeth on the discs engage the locking elements on the openings, upon the arresting means being actuated and the belt tension pulling the reel against a resilient force from the disengaged position, said means for mounting the reel comprising two cantilevered spring mountings, one at each end of the reel, each spring mounting comprising a first arm engaged at a point on the frame and extending radially inwardly therefrom and an inturned end portion which provides the bearing permitting rotation.

2. A retractor according to claim 1, wherein each inturned portion engages in a plastic button which is itself engaged in an aperture in its associated disc on the reel.

3. A retractor according to claim 2, wherein the plastic button is made from PTFE.

4. A retractor according to claim 1, 2 or 3, wherein the cantilevered spring mountings each comprise a second and a third arm formed integrally with the first arm, the second arm extending generally parallel to the first arm and the third arm extending along a different radius from the first and second arms, the third arm having, at its free end, a further inturned portion engageable at a second location on the housing.

5. A retractor according to claim 4, wherein a pin is provided on the frame at the point where the first and second arms meet, the arms passing around the pin which forms said point on the frame.

6. A retractor according to any preceding claim, wherein the means for arresting the rotation of the reel comprise a steering disc rotatable with the reel, a ratchet wheel mounted for limited rotation with respect to said steering disc and acceleration/deceleration sensitive means, such as a ball and pivotal lever, engageable with the teeth of the ratchet wheel on acceleration, internal ratchet teeth on said steering disc, a spring-urged pawl normally out of engagement with said internal ratchet wheel and an abutment on said ratchet wheel engageable with said pawl to urge it into engagement with the internal ratchet wheel on the steering disc, to prevent rotation of said steering disc upon stopping of rotation of said ratchet wheel.

7. A retractor according to claim 6, wherein the ratchet wheel has associated therewith an inertia weight so that, upon unwinding of the reel exceeding a certain rotational speed, the ratchet wheel is rotationally displaced relative to the steering disc whereby the abutment again engages the pawl.

8. A retractor according to claim 6 or 7, wherein the steering disc has a sliding anchor pin engageable in a radial slot in the frame, thereby permitting translational movement of the steering disc and ratchet wheel with the reel upon arresting of rotation of the reel.

9. A safety belt retractor for a vehicle, said retractor being substantially as hereinbefore described, with reference to, and as illustrated in the accompanying drawings.