GB2298677A - Buckle button - Google Patents

Description

BUCKLE BUTTON DESCRIPTION The present invention relates to a buckle button and especially to a ramp profile for a buckle button. The ramp profile described is particularly applicable to a buckle for fastening an automobile safety restraint and most particularly for a buckle as described in EP 0 559 403.

It is an object of the present invention to reduce friction in such a buckle mechanism and to induce an early release of such buttons with reduced release loads.

According to the present invention there is provided a buckling arrangement for an automobile safety restraint comprising: a receiving portion and a co-operating tongue portion, the receiving portion comprising a tongue receiving channel, a latching member having a flange extending generally perpendicular to the plane of the tongue receiving channel in a tongue engagement position, an overlocker member arrangement to move between an overlocking position in which it prevents movement of the latching member out of tongue engagement and a release position in which it allows release of the latching member, a pivotable rocker member operatively coupled to the overlocker member, a button member movable in a direction generally parallel to the plane of the tongue receiving channel to pivot the rocker member t allow movement of the overlocker member to a release position to enable release of the latching member from engagement with the tongue, the button member having a ramp which engages the rocker member to pivot the rocker member, wherein the ramp has a length and angle sufficient to pivot the rocker member to a position at which there is clearance between the rocker and the overlocker member.

Such a clearance was not present in the arrangement described in EP 0 559 403. In this way the button member continues to lift the rocker member until the tongue is disengaged and the buckle is released.

Preferably the buckling arrangement ramp has at least a portion making an angle of around 50 with respect to the plane of the tongue channel. This produces advantageously quick release times.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made to the accompanying drawings, in which: Fig. 1 is a schematic cross-section of a prior art buckle.

Fig. 2 is a schematic cross-section of one embodiment of a buckle according to the present invention; Figs. 3a and 3b are schematic cross-sections of another embodiment of a buckle according to the invention.

Figs. 4a and 4b are graphs of load versus distance for buckles of Figs. 1 and 2.

The arrangement of Fig. 1 corresponds generally to that which is described in European publication 0 384 703.

In Fig. 1 a pivoted latching member 1 engages in an aperture in a tongue 2 to maintain the buckle in a closed and latched state. In the latched position the latching member 1 is held by pin 3 and acted on by a leaf spring 4.

In the fastened buckle this pin 3 is restrained in a recess 5 in a rocker 6 which pivots about axis 7 against the force of leaf spring 8 (which may be integral with the leaf spring 4 or may be a separate leaf spring).

To release the buckle, a button 13 is depressed in a direction to the right of the figure generally parallel to the plane of the tongue receiving channel. The button has an extended portion within the buckle with ramp surfaces 14 located on each side. When the button is depressed the ramp surfaces of the extended portion engage a forward lip of the rocker 6 and lift the rocker member 6 against the force of leaf spring 8 about pivot 7. As the rocker member 6 lifts, the pin 3 is released from recess 5. An abutment on the button simultaneously engages the pin and drives it to the right guided in the longitudinal arm of an L-shaped recess 9 in the buckle frame. When the pin reaches the lateral arm of the L-shaped recess 9, then the latching member 1 is free to pivot out of engagement with the tongue 2, releasing the seat belt.

In Fig. 2, like parts are denoted by like reference numbers. Fig. 2 illustrates an identical buckle mechanism except for the profile and size of the button ramp. The ramp on the extended button portion is significantly longer and higher than in the known mechanism of Fig. 1. Also, the profile is such as to present to the rocker member 6, first a portion 10 steeper than the ramp of the known button of Fig. l and subsequently an adjacent portion 11 of lesser gradient. Alternatively to this two-stage ramp profile, a single ramp angle may be used of equal height, also to very good effect and this is shown in Figures 3a and 3b. An angle of around 50 is found to have optimum effect, giving quick release times for reduced release loads.This longer ramp continues to lift the rocker member 6 away from the latching member 1, for a greater time than does the known profile. The additional lift imparted to the rocker member 6 lifts it clear of the pin 3 allowing free movement of the pin and thus reducing friction on the pin and substantially removing the wedge effect which occurs in the known mechanism and which causes impairment of performance.

Release of the tongue 2 is effected more easily and more quickly since the clearance 12 between the pin and the rocker member6 causes a spring bias to be effective on the latching member in the release direction. This spring bias results from the latching member, the overlocker pin and the rocker all being operatively coupled via the leaf spring.

The leaf spring has its base connected, for example crimped around, the part of the latching member which forms the line of pivot and has arms 4 extending over the overlocker pin 3 and arms 8 extending over the rocker 6. Thus these three elements are effectively held together by resilient forces and so when rocker 6 is lifted the force on leaf spring arm 8 tends to pull the latching member out of the latched position. However when the rocker is in the down position then the latching member experiences a bias to the latching position.

In Fig. 3a a single stage ramp surface is shown, of the same overall height as the ramp of Fig. 2. This ramp is of approximately 50 . The elements of Fig. 3a are shown schematically in Fig. 3b for clarity.

Figs. 4a and 4b are graphs of respective experimental trials and plot load versus distance. In each Figure line A represents the results for the known button of Fig. 1 and line B represents results for a button according to the invention (Fig. 2). The improvement can clearly be seen representing an earlier release of up to 2mm in this example and lower overall loads.

Claims (6)

1. A buckling arrangement for an automobile safety restraint comprising: a receiving portion and a co-operating tongue portion, the receiving portion comprising a tongue receiving channel, a latching member having a flange extending generally perpendicular to the plane of the tongue receiving channel in a tongue engagement position, an overlocker member arrangement to move between an overlocking position in which it prevents movement of the latching member out of tongue engagement and a release position in which it allows release of the latching member, a pivotable rocker member operatively coupled to the overlocker member, a button member movable in a direction generally parallel to the plane of the tongue receiving channel to pivot the rocker member to allow movement of the overlocker member to a release position to enable release of the latching member from engagement with the tongue, the button member having a ramp which engages the rocker member to pivot the rocker member, wherein the ramp has a length and angle sufficient to pivot the rocker member to a position at which there is clearance between the rocker and the overlocker member.

2. A buckling arrangement according to claim 1, wherein the ramp has at least a portion making an angle of 50O with respect to the plane of the tongue channel.

3. A buckling arrangement according to claim 1 or claim 2 wherein the ramp has two portions of which a leading portion has a steeper cross-sectional profile than an adjacent trailing portion, in the direction of movement of the button to release the tongue.

4. A buckling arrangement according to claim 3, wherein the ramp has a further portion ahead of the leading portion which has a less steep cross-sectional profile than the leading portion.

5. A buckling arrangement according to any preceding claim further comprising means for biasing the latching member to a tongue disengagement position.

6. A buckling arrangement substantially as hereinbefore described with reference to Fig. 2 or Figs. 3a and 3b of the accompanying drawings.