GB2271378A - A safety belt buckle - Google Patents

Abstract

A safety belt buckle for receiving and retaining a tongue (15) mounted on the safety belt comprises a housing (1) defining a path to receive the tongue (15); a main tongue-engaging locking element (11); a second locking element (20) of pin-like form which engages the main locking element (11) to prevent movement thereof to the release position; and a push button (29) adapted to move the second locking element (20), the push button (29) and the second locking element (20) moving in opposite directions (considered axially of the buckle) when the main locking element (11) is to be released, part of the second locking element (20) being received in an aperture (5) in part of the buckle housing (1) to transmit any release forces on the main locking element (11) to the housing (1). As shown the second element (20) is pivotably mounted but it can be mounted for sliding movement (fig 6, not shown). <IMAGE>

Description

DESCRIPTION OF INVENTION A Safety Belt Buckle.

THE PRESENT INVENTION relates to a safety belt buckle.

It is well known to provide a safety belt buckle which receives a tongue connected to part of a safety belt and retains the tongue within the buckle. The buckle usually has a push button which can be manually operated in order to release the tongue from the buckle.

The tongue is usually retained within the buckle by means of a latch or locking element which is movable between a latching position and a release position. This invention relates to a particular type of buckle known as a "servo buckle" in which the latch or locking element will tend to move to the release position when the tongue is moved in a direction tending to withdraw it from the buckle i.e. when tension is applied to the safety belt. In this type of buckle a second locking element is provided in order to retain the latch or main locking element in the locking position, the second locking element being movable by way of the push button so as to permit the latch or main locking element to move to the release position.

One prior art buckle of this type is shown in European Patent No. 0 060 254. In this document the second locking element is constituted by a pin which is constrained to move along a path defined by L-shaped apertures formed in the housing of the buckle. One limb of each L-shaped aperture extends horizontally whilst the other extends vertically. The vertically extending limb extends upwardly from the rearmost end of the horizontally extending limb. When the second locking element is received within the horizontally extending limb of each aperture the main locking element or latch is held in the locking position. In order to move the latch to the release position the second locking element must be moved to the rearmost end of the horizontal limb of each L-shaped aperture before it can move upwardly and permit upwards movement of the latch to the release position.Rearwards movement of the second locking element is effected by rearwards movement of the push button which is used to release the tongue from the buckle. Thus, the second locking element moves in the same direction as the push button used to release the tongue from the buckle and the buckle is therefore not "g-safe", that is to say the buckle could be moved to the release position as a result of g forces exerted on the components of the buckle in an accident situation. Clearly this is most undesirable. In addition the arrangement of EP 0 060 254 requires that the second locking element be moved over a significant distance before the latch or main locking element can move to the release position.

Another buckle of this general type is disclosed in EP-A-0 052 160. In this document the second locking element is constituted by a pivoting lever, the lower end of which engages the upper surface of the latch or main locking element. The lever is pivotally mounted approximately about its mid-point and the upper end of the lever is engaged by the push button when the push button is moved rearwardly, thereby causing rotation of the lever about its mid-point so that the lower end of the lever is disengaged from the latch or main locking element.Whilst in this arrangement the lower end of the lever which engages the latch or main locking element moves in the opposite direction to the push button when the push button is moved so as to release the tongue from the buckle (and thus the arrangement may be considered to be g-safe), the forces which tend to move the latch or main locking element to the release position have to be transmitted over a significant distance from the point of contact of the lower end of the pivoting lever with the latch to the pivot axis of the lever where the lever engages the housing of the buckle. This means that the lever must be of significant strength and will therefore usually have to be formed of metal and will be relatively heavy.

The present invention seeks to provide an improved safety belt buckle of the general type discussed above.

According to the present invention there is provided a safety belt buckle for receiving and retaining a tongue mounted on the safety belt comprises a housing defining a path to receive the tongue; a main locking element movable between a release position in which it does not engage the tongue and a locking position in which it engages the tongue to retain the tongue in the buckle; a second locking element of pin-like form which engages the main locking element when in the locking position and prevents movement of the main locking element to the release position, the second locking element being movable to a position in which the main locking element is freed so as to be movable to the release position; and a push button adapted to move the second locking element, the push button and the second locking element moving in opposite directions (considered axially of the buckle) when the main locking element is to be released, part of the second locking element being received in an aperture in part of the buckle housing, with any forces which tend to urge the main locking element to the release position being transmitted to the housing via the second locking element.

Preferably the buckle incorporates a pivoting lever, the second locking element being mounted adjacent one end of the lever, movement of the push button being transmitted to the second locking element via the lever.

Conveniently any forces which tend to urge the main locking element to the release position are transmitted into the housing of the buckle at a position offset from the point where the lever is pivotally mounted in the housing, said forces being transmitted into the housing through the second locking element and an edge of the aperture in which part of the second locking element is received.

The pin-like second locking element may be formed integrally with the lever, or alternatively it may be formed separately from the lever and be received within a recess defined by the lever.

In an alternative embodiment the buckle may incorporate a flexible element extending between the push button and the second locking element, the flexible element transmitting movement of the push button in one direction to the second locking element such that the second locking element is caused to move in the opposite direction to the push button.

Preferably the buckle incorporates a tongue ejector which acts to urge a tongue present in the buckle out of the buckle, the ejector being biassed by means of a spring which extends between part of the ejector and the second locking element.

Conveniently the push button and the second locking element are "mass-balanced" such that the second locking element will not be moved to enable the main locking element to move to the release position under the action of g-forces in either direction axially of the buckle.

In order that the present invention may be more readily understood and so that further features thereof may be appreciated, the invention will now be described by way of example, with reference to the accompanying drawings in which: FIGURE 1 is an exploded perspective view showing some of the parts of a buckle in accordance with this invention; FIGURE 2 is a longitudinal cross-sectional view through a buckle in accordance with this invention showing the buckle in the released position; FIGURE 3 is a cross-sectional view corresponding to Figure 2 but showing the buckle in the locked position in which a safety belt tongue is retained therein; FIGURE 4 is a side view of a lever forming part of the buckle; FIGURE 5 is an end view of the lever of Figure 4; and FIGURE 6 is a schematic cross-sectional view showing some of the parts of an alternative embodiment of a buckle in accordance with this invention.

Referring initially to the buckle illustrated in Figures 1 to 5 of the accompanying drawings, this buckle comprises a channel-shaped housing 1 having a base 2 and upstanding opposed side walls 3. The side walls stand at right angles to the base and are both of the same form, each defining a number of apertures which serve to receive other parts of the buckle.

Thus each side wall 3 defines a circular aperture 4 adjacent its upper edge at approximately the mid-point along its length and an arcuate slot 5 which extends around the aperture 4 from the upper edge of the side wall through an angle of approximately 90". In addition each side wall defines, to the rear of the aperture 4 and slot 5, an opening 6 having a first vertical portion 7 which extends downwardly from the upper edge of the side wall and a second, parallel vertical portion disposed to the rear of the first portion, the second portion 8 extending upwardly and terminating at a position spaced from the upper edge of the side wall. Between the first and second portions 7, 8 of the opening 6 each side wall 3 defines a slightly resilient depending limb 9.

The base of the buckle is generally rectangular and the side walls 3 extend upwardly from the longer opposed edges of the base. Part of a central region of the base 2 is deflected upwardly into the channel to form a projection 10 which serves to locate other components within the channel.

It should be appreciated that Figure 1 is only a schematic illustration and, in practice, the housing 1 would look somewhat different. Thus the housing would have outwardly directed flanges extending laterally from the top of each side wall 3, as well as other features not specifically illustrated or described here.

It is to be understood that when reference is made to the front and rear of the buckle in this description, the front of the buckle is the left hand end of the buckle whilst the rear of the buckle is the right hand end of the buckle as seen in Figures 1, 2 and 3 of the drawings.

The buckle has a main locking element in the form of a latching member 11 which extends across the width of the channel. The latching member 11 has a main body defining a substantially rectangular aperture 12. The front end of the latching member defines a downwardly deflected portion 13 which forms the locking catch of the latching member. The latching member is mounted within the channel housing 1 so that the upstanding protection 10 in the base 2 passes through the aperture 12 adjacent the rear of latching member and so that rearwardly directed lugs 14 formed on the latching member pass into the openings 6 formed in the side walls 3.The latching member is actually introduced into the channel by passing the lugs 14 into the openings 6 via the open upper end of the first portion 7 and sliding the lugs downwardly which eventually causes the resilient limbs 9 to flex rearwardly so that the lugs 14 snap into position at the base of the openings 6 and are then held in place. The latching member is now rotatably mounted within the channel and may pivot about an axis extending transversely across the channel at the rear of the latching member. Thus the front end of the latching member which carries the locking catch 13 may be moved between raised and lowered positions corresponding to the released and locking positions of the buckle.

A locking tongue 15 (see Figures 2 and 3) which is connected to a safety belt, such as a vehicle seat belt, may be retained in the buckle by means of the latching member 11, the locking catch 13 of which passes into an aperture 16 defined by the locking tongue when in the lowered position with the tongue received in the buckle.

The tongue 15 is inserted into the buckle along the upper surface of the base 2 which effectively defines a path to receive the tongue. When the tongue is received in the buckle and retained in position by the locking catch 13 of the latching member 11, the latching member engages the tongue at a position just above the upper surface of the base 2. As can be seen best from Figure 3, the pivot axis of the latching member is located above the level of the tongue 15 and above the level of the point of engagement between the locking catch 13 and the tongue and thus forces exerted on the latching member by the tongue due to tension in the safety belt result in a torque on the latching member which acts to rotate it in a clockwise direction about its pivot axis. Thus such forces act to raise the locking catch 13 and move the latching member to the release position.

A spring-biased tongue ejector 17 is located on the base of the channel housing beneath the latching member 11 and serves to bias the tongue 15 out of the buckle in a known manner. Thus, even when there is little or no tension in the safety belt to which the tongue 15 is connected, the ejector 17 exerts a force on the locking catch 13 through the tongue 15 which gives rise to a torque acting to rotate the latching member to the release position.

The ejector has a pair of upwardly and rearwardly extending arms 18 which pass up through the aperture 12 in the main body of the latching member and which are interconnected by a rod or pin 19 which extends transversely of the buckle between the two arms 18.

In order to prevent the latching member 11 from moving to the release position a second locking element in the form of a circular-section pin 20 is provided, the pin 20 extending transversely across the buckle and engaging the upper surface of the latching member at a position towards the front of the member. The pin 20 is received in the end of a lever 21 which is pivotally supported within the channel housing 1 of the buckle by way of journals 22 which extend into the circular apertures 4 in the side walls 3. Thus the lever 21 extends transversely across the channel housing, as does the pin 20 which forms the second locking element. The pin 20 is received with an appropriately configured recess 23 formed at the lower end of the lever 21.The pivot axis of the lever is disposed between the upper and lower ends thereof at a position just above the middle of the lever as seen in side view in Figures 2 and 3.

The ends of the pin 20 project beyond the lever 21 and are received within the arcuate slots 5 formed in the side walls 3. Thus, the slots 5 define a predetermined path of movement for the pin 20 as the lever 21 rotates about its pivot axis defined by the journals 22 and the apertures 4 in the housing.

When the lever 21 is mounted in the buckle housing it is positioned in front of the pin or rod 19 on the ejector 17 and a tension spring 24 extends from the pin 20 which constitutes the second locking element to the pin 19 on the ejector 17, the spring 24 acting to draw the two pins 19, 20 together. Thus, the spring acts to bias the ejector 17 towards the front of the buckle and to pull the pin 20 towards the rear of the buckle, thereby rotating the lever 21 in an anti-clockwise direction about its pivot axis.

As can clearly be seen in Figure 4 of the drawings the lever 21 comprises two upstanding lever portions 25 which are interconnected by a transverse element 26 which is aligned with the journals 22. It is in fact the lower region of the two lever portions 25 which define the recess 23 within which the pin 20 is accommodated. The upper region of each lever portion 25 is of hook-like form, defining a hook-like projection 27 which is directed towards the front of the buckle. This forwardly directed hook-like projection is positioned just above the level of the upper edges of the side walls 3 of the buckle housing when the buckle is in the locked position as shown in Figure 3. The transverse portion 26 of the lever defines a rearwardly directed lip or ridge 28.

A push button 29 is mounted upon the buckle housing for axial sliding motion relative thereto, in a conventional manner. The push button 29 is used in order to release the tongue 15 from the buckle. Part of the push button 29 extends transversely across the top of the channel housing, resting upon the upper edges of the side walls 3. This part of the button defines a rearwardly facing surface 30 designed to engage and cooperate with the forwardly directed hook-like projection 27 defined by the lever 21. In addition the push button 29 has a portion which extends further rearwardly and downwardly as shown by the reference numeral 31, the rearmost portion of the push button carrying a forwardly directed foot 32 which is designed to be received beneath the rearwardly directed lip or ridge 28 of the lever 21 when the buckle is in the locked position, as shown in Figure 3.The push button 29 is biassed towards the left in Figures 2 and 3 by means of a spring or the like which is not illustrated in the drawings. Thus the push button would not normally remain in the position shown in Figure 2 but would be urged to the left.

Figure 2 shows the arrangement of the buckle when it is not in use and it is in the released position. As mentioned above the push button 29 would normally be displaced slightly further to the left. The latching member is in the raised position with a front edge of the ejector 17 located beneath and in engagement with the locking catch 13 thereof. The lever 21 has been rotated in an anti-clockwise direction so that the pin 20 is positioned approximately mid-way around the arcuate slot 5 and the spring 23 has contracted and is in a relaxed or only very slightly tensioned condition. It is, of course, the contraction of the spring 24 which has drawn the ejector 17 forwards within the buckle.

Upon insertion of the tongue 15 into the buckle the ejector 17 is pushed rearwardly, thereby causing the spring 24 to be extended. This tensioning of the spring draws the pin 20 back along the arcuate slot 5, with the lever 21 rotating in an anti-clockwise direction. The engagement of the pin 20 with the upper surface of the latching member 11 causes the front end of the latch carrying the downwardly depending locking catch 13 to be moved in a downwards direction so that the locking catch passes into the aperture 16 formed in the tongue.

When tension is applied to the safety belt, tending to pull the tongue 15 out of the buckle, the rear edge of the locking catch 13 engages the edge of the aperture 16 and prevents the tongue from being withdrawn from the buckle. As the lever 21 is rotated in an anti-clockwise direction upon insertion of the tongue 15 the forwardly directed hook-like projection 27 at the top of the lever engages the rearwardly directed surface 30 of the push button 29 and urges the push button to the left (as seen in Figures 2 and 3). Simultaneously the foot 32 on the rearward extension of the push button 29 is drawn forwardly until it is engaged beneath the lip or ridge 28 defined by the lever, thereby preventing clockwise rotation of the lever.As can be seen from Figure 3 of the drawings there is a small clearance between the rearwardly directed surface 30 of the push button and the forwardly directed hook-like projection 27 on the lever when the buckle is in the locked position.

When the tongue 15 is to be released from the buckle the push button 29 is moved rearwardly of the buckle i.e. to the right in Figures 2 and 3. The clearance between the rearwardly directed surface 30 and the forwardly directed hook-like projection 27 on the lever 21 enables the foot 32 to be released from beneath the lip or ridge 28 before the surface 30 actually engages the top edge of the lever and starts to rotate the lever 21 in a clockwise direction. This rotation of the lever causes the spring 24 to be extended as the pin 20 moves around the arcuate slot 5. The extension of the spring 24 results in the ejector 17 being drawn to the front of the buckle.As explained above the latching member 11 will normally move to the release position if it is not held in the locking position by the pin 20 and thus the latching member moves upwardly as the ejector ejects the tongue 15 from the buckle and holds the latching member in the raised or release position.

It will be appreciated from the above description that if the tongue 15 is to be released from the buckle the push button 29 must move towards the back of the buckle whilst the pin 20 must move towards the front of the buckle, i.e. the lever 21 must rotate in a clockwise direction. The centre of gravity of the lever 21 and pin 20 is located beneath the pivot axis defined by the journals 22. By appropriate design of the push button 29 and the lever 21 and pin 20 and their positioning relative to each other within the buckle, the buckle is "g-safe", that is to say the buckle will not move to the released position under the action of g-forces in either direction axially of the buckle.If one initially considers the situation in which the buckle is subjected to a high acceleration acting axially towards the rear of the buckle this would tend to cause the lever 21 to rotate in a clockwise direction which might result in the tongue being released from the buckle. However, the rearwardly directed lip 28 engages the forwardly directed foot 32 on the push button so that clockwise rotation of the lever 21 is prevented. Simultaneously the inertia of the push button 29 would cause it to move towards the front of the buckle so that the foot 32 is positively retained beneath the rearwardly directed lip 28 of the lever.

In an accident situation where the buckle is subjected to a high acceleration acting in the opposite axial direction i.e. towards the front of the buckle, the push button would be urged rearwardly whilst the lever 21 would tend to rotate in an anti-clockwise direction. As mentioned above, however, the push button and the lever and pin are so designed that in this situation there will be no resultant torque acting on the lever to move it towards the release position of the buckle and any torque applied to the lever by the push button is counteracted by the torque resulting from the centre of gravity of the lever being offset from its pivot axis. Thus the push button and the second locking element may be considered to be "mass-balanced".

It will also be appreciated from the above description that any forces tending to urge the latching member to the raised or release position are transmitted to the buckle housing 1 via the pin 20. Thus any such forces would be transmitted from the latching member through the pin 20 and into the housing via the edges of the arcuate slots 5 and not via the main body of the lever 21. This means that the lever 21 need not be made very strong and may, therefore, be formed from a plastics material. This results in a lever which is significantly lighter than would be the case if it were necessary to make a stronger lever of metal.It is envisaged that the pin 20 will itself be formed of metal and whilst an arrangement has been described in which the pin is formed separately to the lever 21, the lever and pin could be formed integrally of metal with the main part of the lever being relatively thin since it does not have to convey any significant forces to the buckle housing. In any event it will be appreciated that forces tending to move the latching member to the released position are transmitted into the buckle housing by the pin 20 at a position offset from the journals 22 which define the pivot axis of the lever.

Figure 6 is a diagrammatic longitudinal cross-sectional view showing the main components of an alternative embodiment. For ease of description the same reference numerals are used to identify parts corresponding with parts described in relation to Figures 1 to 5. In this modified arrangement a tongue 15 is again retained within the buckle by means of a main latching member 11 which has a downwardly directed locking catch 13 which passes into an aperture 16 formed in the tongue. The main locking member is pivotally mounted at the rear of the buckle housing so as to movable between raised and lowered positions corresponding to the release and locking positions.

In this modified embodiment the second locking element which serves to retain the main latching member 11 in the locking position again comprises a pin 20, the ends of the pin being received within slots 33 defined by the side walls of the buckle housing. The slots 33 extend axially of the buckle in a direction parallel to the base of the buckle housing. The tongue 15 may be released from the buckle by means of a push button 29. The push button 29 carries a flexible "push element" 34 which extends rearwardly of the main body of the push button before being guided through an arc of 1800 by an abutment 35 defined by part of the buckle housing. The free end of the flexible push element 34 engages the rear of the pin 20.

It will be appreciated that pressing the push button 29 to the right in Figure 6 of the drawings will cause the free end of the push element 34 to move the pin 20 to the left thereby freeing the latching member 11 so that it can move to the release position.

Claims (11)

1. A safety belt buckle for receiving and retaining a tongue mounted on the safety belt comprises a housing defining a path to receive the tongue; a main locking element movable between a release position in which it does not engage the tongue and a locking position in which it engages the tongue to retain the tongue in the buckle; a second locking element of pin-like form which engages the main locking element when in the locking position and prevents movement of the main locking element to the release position, the second locking element being movable to a position in which the main locking element is freed so as to be movable to the release position; and a push button adapted to move the second locking element, the push button and the second locking element moving in opposite directions (considered axially of the buckle) when the main locking element is to be released, part of the second locking element being received in an aperture in part of the buckle housing, with any forces which tend to urge the main locking element to the release position being transmitted to the housing via the second locking element.

2. A safety belt buckle according to Claim 1 wherein the buckle incorporates a pivoting lever, the second locking element being mounted adjacent one end of the lever, movement of the push button being transmitted to the second locking element via the lever.

3. A safety belt buckle according to Claim 2 wherein any forces which tend to urge the main locking element to the release position are transmitted into the housing of the buckle at a position offset from the point where the lever is pivotally mounted in the housing, said forces being transmitted into the housing through the second locking element and an edge of the aperture in which part of the second locking element is received.

4. A safety belt buckle according to Claim 2 or Claim 3 wherein the pin-like second locking element is formed integrally with the lever.

5. A safety belt buckle according to Claim 2 or Claim 3 wherein the pin-like second locking element is formed separately from the lever and is received within a recess defined by the lever.

6. A safety belt buckle according to Claim 1 wherein the buckle incorporates a flexible element extending between the push button and the second locking element, the flexible element transmitting movement of the push button in one direction to the second locking element such that the second locking element is caused to move in the opposite direction to the push button.

7. A safety belt buckle according to any one of the preceding claims wherein the buckle incorporates a tongue ejector which acts to urge a tongue present in the buckle out of the buckle, the ejector being biassed by means of a spring which extends between part of the ejector and the second locking element.

8. A safety belt buckle according to any one of the preceding claims wherein the push button and the second locking element are "mass-balanced" such that the second locking element will not be moved to enable the main locking element to move to the release position under the action of g-forces in either direction axially of the buckle.

9. A safety belt buckle substantially as herein described with reference to and as shown in Figures 1 to 5 of the accompanying drawings.

10. A safety belt buckle substantially as herein described with reference to and as shown in Figure 6 of the accompanying drawings.

11. Any novel feature or combination of features disclosed herein.