A SAFETY BELT BUCKLE

Abstract: A buckle for use with a safety belt system has a locking mechanism to receive and retain a tongue (51) which is mounted on a safety belt. The buckle is provided with means (19) to release the locking mechanism to permit the tongue (51) to be withdrawn from the buckle. The buckle has means (45, 50) which are responsive to accleration in at least one direction relative to the buckle which are operative to prevent the locking mechanism from moving to a re­ lease condition.

Description: THE PRESENT INVENTION relates to a safety belt buckle and more particularly to a safety belt buckle intended for use in a motor vehicle such as motor car. Many types of buckle have been proposed for use with a safety belt in a motor vehicle such a motor car. A conventional buckle of this type defines a housing containing a locking mechanism which is adapted to engage and retain a tongue inserted into the housing. The tongue is connected to a portion of a safety belt. The tongue is released from the buckle by depressing a push-button or slider which releases the locking mechanism contained within the housing. The tongue is then ejected from the housing by an ejector. It has been proposed to provide safety belt arrangements for use in motor vehicles, such as motor cars, with a mechanism which applies a tension to the belt in the event that an accident arises. Such a device may effectively comprise a very powerful spring which moves the buckle downwardly when a sensor senses an accident situation. Alternatively a pyrotechnic device may be used to accelerate the buckle downwardly. In either event, when an accident situation is sensed, the buckle is subjected to a severe downward acceleration, and is then subjected to an equally rapid deceleration as the buckle reaches the end of its permitted travel. The components of the locking mechanism within the housing of a conventional buckle each, of course, have inertia, and may thus move relative to the housing either during the acceleration or during the deceleration of the buckle, depending upon the freedom of movement available to each component of the locking mechanism. Even though, in a conventional locking mechanism, the components are retained in the locking condition by a spring bias, it is possible, due to the significant acceleration and deceleration involved, that the inertia of the components may overcome the spring bias, and consequently parts of the locking mechanism may be moved, and the locking mechanism may enter the unlocking condition. Thus the buckle may inadvertently release the tongue as a consequence of the operation of the pre-tensioner. This is clearly undesirable since, should such a release occur, the person intended to be restrained by the safety belt is not restrained at all at the instant that an accident has been sensed. EP-A-0212507 discloses a buckle for use with a safety belt system. The buckle has a locking mechanism adapted to receive and retain a tongue mounted on a safety belt. The mechanism incorporates a manually operated slider member which is operable to release the locking mechanism to permit the tongue to be withdrawn from the buckle. The buckle comprises an inertia element in the form of a pivotally mounted weight which is responsive to acceleration in one direction relative to the buckle to prevent the locking mechanism from moving to the release condition. The pivotally mounted weight is provided with part thereof which, in an initial condition, lies adjacent part of the slider so that the slider can move freely but which, when the weight is moved pivotally as a consequence of the sensed acceleration, engages the slider when the slider starts to move towards the release position, thus preventing the slider from moving to the release position. Thus the arrangement of EP-A-0212507 serves to prevent the slider from moving to the release position when the buckle is subjected to acceleration in one direction, that is to say the direction sensed by the weight. However, when a buckle is used with a pre-tensioner, as described above, the buckle is provided with a first acceleration and then rapidly decelerates. The deceleration can be considered to be an acceleration in the opposite sense to the first acceleration. Thus, whilst the mechanism of EP-A-0212507 may serve to lock the buckle during one of these two accelerations, the buckle may be released during the other acceleration. Thus, even using the buckle of EP-A-0212507 an inadvertent release of the tongue may occur. The present invention seeks to provide an improved buckle. According to this invention there is provided a buckle for use with a safety belt system, said buckle comprising a locking mechanism adapted to receive and retain the tongue mounted on a safety belt, said mechanism incorporating a manually operable slider element operable to release the locking mechanism to permit the tongue to be withdrawn from the buckle, the buckle comprising an inertia element in the form of a pivotally mounted weight responsive to acceleration in at least one direction relative to the buckle to prevent said locking mechanism from moving to a release condition, wherein the pivotally mounted weight is provided with part thereof which, in an initial condition, lies adjacent part of the slider so that the slider can move freely but which, when the weight has moved pivotally as a consequence of the sensed acceleration, engages the slider when the slider starts to move towards the release position, thus preventing the slider from moving to the release position and wherein a second pivotally mounted weight is provided, the second weight being dimensioned and positioned so that when subjected to an acceleration in a direction opposite to the sense of said one direction the second weight engages part of the first weight and moves the first weight against the effect of its own inertia to a position in which the said part of the first weight prevents operation of the locking mechanism. Advantageously the first weight is provided with an extending arm portion positioned to be engaged by said second weight when the second weight is subjected to said acceleration in the direction opposite to the said one direction. Preferably the first weight is provided with a protruding arm comprising the said part thereof to engage the slider, the end of the arm being adapted to engage the slider. Advandageously said pivotally mounted weights are mounted for pivotal movement about which are substantially lying in the plan along which the slider element moves. In order that the invention may be more readily understood, and that further features thereof may be appreciated, the invention will now be described, by way of examples, with reference to the accompanying drawings in which FIGURE 1 is an exploded view of the main operative parts of a buckle in accordance with the invention, FIGURE 2 is a side view of the buckle partly in section, and with certain components removed, in the unlocked condition, FIGURE 3 is a view corresponding to Figure 2 illustrating the buckle in the locked condition, FIGURE 4 is a sectional view of the buckle showing the buckle in the unlocked condition, FIGURE 5 is a sectional view corresponding to Figure 4 showing the buckle in the locked condition, FIGURE 6 is a side view of certain components of the buckle in a rest condition, FIGURE 7 is a corresponding view showing the same components when subjected to an acceleration in one direction, FIGURE 8 is a further corresponding view showing the same components of the buckle when subjected to an acceleration in the opposite direction, and FIGURE 9 is a perspective view of one embodiment of the invention as proposed to be manufactured. Referring initially to Figure 1 a buckle in accordance with the present invention comprises a channel member 1 having a base 2 and two up-standing side wall 3,4. The base of the channel is provided, adjacent one end, with an up-standing rivet 5 which is surrounded by a shaped guide washer 6. A steel wire 7 is wound around the guide washer and passes through a tubular sleeve 8 to an anchoring point, for example on the body of a motor vehicle such as a car, so that the channel 1 is securely mounted in position. The base 2 of the channel is provided with two elongate apertures 9 adjacent the lower edges of the side walls 3,4 each terminating, at a transverse forward edge 10. Each side wall 3,4 is provided with a substantially "L"-shaped aperture 11, each such aperture having a forwardly extending portion 12 and an upwardly extending portion 13. Towards the rear of the channel, that is to say the end provided with the rivet 5, each side wall 3,4 is provided with an outwardly extending tab 15 and two further apertures 16,17 which are of circular form. The upper parts of the sides walls 3,4 are recessed, 18 towards the rear of the channel member. A slider 19 is provided which is slidingly mounted upon the channel. The slider 19 has an operative front face 20 and two rearwardly extending arms 21 located on each side of the slider. Each arm terminates with an inwardly directed protrusion 22 adapted to be received in the recess 18 on the side wall of the channel. The inner face of each arm 21 is provided with a recess 23 of triangular configuration. Slidably mounted on the base of the channel is an ejector 24. The ejector 24 has a cut-away region 25 on its front face provided for a purpose which will be described hereinafter and has a further horizontal cut-away region 26 on its rear face. The slider is also provided with a vertically cut-away portion 27 which forms a recess in the rear face of the slider. Part of the slider is slidably retained in an elongate axially extending aperture 28 formes in the base 2 of the channel 1. A substantially planar elongate locking member 29 is provided which is mounted on the channel member, the locking member having, towards its rear end, an aperture 30 which is received over the rivet 5, so that the rivet 5 forms a pivot point for the locking member. The central region of the locking member is provided with an aperture 31 which has, projecting into it from its rearward edge, a tongue 32, which is cranked slightly upwardly, and which receives one end of a spring 33. The front end of the locking member is bifurcated and forms two downardly extending locking claws 34, which extend perpendicularly to the main part of the locking member and which are dimensioned to be inserted into the forward ends of the apertures 9, thus engaging the front surfaces 10 of those apertures. Between the locking claws 34, a forwardly extending projection 35 is provided adapted to engage one end of the spring 36. The other end of the spring 36 engages a rear face of the slide 19. The spring 36 biasses the slider forwardly. A rocker member 37 is provided having, at its lower end, projecting trunions 38 dimensioned to be received within the horizontal cut-away region 26 of the ejector 24. The base of the rocker member 37 is received in the cut-away portion 27 of the ejector 24. Thus the base of the rocker moves axially with the ejector, but can pivot relative to the ejector. The rocker member 37, has at its upper end, a hook-shaped portion 39 which defines a recess 40. A projection 41 is provided on the rear face of the rocker member. The recess 40 of the rocker member is adapted to engage a secondary locking element 42 in the form of an elongate rod, the ends of the rod being dimensioned to pass through the "L"-shaped apertures 11 in the side walls 3 and 4 and into the triangular recesses 23 formed on the arms 21 of the slider 19. Two mounting axles 43,44 are provided which extend through the aligned apertures 16,17 formed in the side walls 3,4 of the channel. Mounted on the ends of the first axle 43 are locking weights 45. Each locking weight 45 comprises a portion 46 located above the centre of rotation thereof having significant mass. The locking weight 45 is also provided with a forwardly extending arm 47 and a secondary downwardly extending arm 48. A spring 49 is provided which extends between a part of the portion 46 and an outwardly directed tab 15 provided on the side wall of the channel. The second axle 44 carries secondary locking weights 50 each which comprise a relatively large mass located below the pivot axis defined by the axle 44. The described components, when assembled, form a buckle which defines an entry path for a tongue 51 as conventionally found on a satefy belt. The tongue 51 has an enlarged head 52 joined to the main body of the tongue by relatively narrow shank 53. The head has a curved front face 54 and defines rearwardly facing abutment surfaces 55. The operative components of the buckle, as described above will, of course, be surrounded by an appropriate housing 56, shown in phantom in Figures 4 and 5. Referring now to Figures 2 and 4 it is to be seen that the ejector 24 is engaged with an aperture formed in the base of the channel and is slidable along the channel. The recess 25 formed in the forward face of the ejector has a configuration corresponding to that of the curved portion 54 provided on the tongue 51. The spring 33 extends from the boss 41 provided on the rocker 37 to the tongue 32 provided on the locking element 29. The spring serves both to bias the locking member pivotally upwardly about a pivoting point and also serves to force the lower end of the rocker forwardly, thus forcing the trunions 38 into the recess 26 provided on the rear of the ejector 24. Thus the ejector 24 is biassed forwardly. The recess 40 defined by the rocker securely engages the secondary locking member 42. The ends of the secondary locking member 42 pass through the apertures 11, and in the described condition of the buckle, the ends of the secondary locking member 42 pass through the upper ends of the vertically extending portions 13 of the L-shaped apertures 11 to be received within the triangular recesses 23 defined on the slider. When the tongue 51 is inserted into the buckle the curved end 54 of the tongue engages the recess 25 provided in the ejector 24 and the ejector 24 then moves rearwardly, thus also moving rearwardly the lower part of the rocker 37. The lower part of the rocker 37 thus moves rearwardly and the rocker starts to tilt, the effect being that a downward force is applied to the secondary locking member 42. The force increases and the secondary locking member 42 starts to move vertically downwardly, since it is constrained to follow such a path because the ends of the secondary locking member are received within the vertically extending portions 13 of the L-shaped apertures 11. The locking member thus also moves pivotally in a downward sense against the upward bias provided by the springs 33 and 36. When the secondary locking member has been moved to such a point that it is aligned with the horizontally extending portion 12 of the L-shaped apertures 11 the secondary locking member is caused to move forwardly to the forward end of the horizontal portions 12 of the L-shaped apertures. The springs 33 and 36 pass through a "dead centre" condition and then bias the locking member downwardly into the locking condition. Whilst this movement is being completed the locking member 29 moves in a pivotal manner, the locking claws 34, passing behind the rearwardly facing abutment surfaces 55 defined on the tongue 51 and passing through the forward-most ends of the apertures 9. Thus, if there is any force tending to withdraw the tongue from the buckle even if the locking claws 34, are deformed slightly they will engage the front edges 10 of the apertures 9 and will thus retain the tongue in the buckle. As can be seen from Figure 3, the locking claws 34 do pass right through the apertures 9 to project beneath the base 2 of the channel 1. It will be appreciated that the secondary locking member 42 prevents upward movement of the locking member to a release position and thus the tongue is retained within the buckle. If the slider 19 is subsequently pushed inwardly, by virtue of the engagement of the ends of the secondary locking member 42 within the apertures 23, the secondary locking member is moved rearwardly, thus causing the rocking member to commence rotation in a clockwise direction. Also the spring 33 becomes compressed, thus applying a force to the locking member tending to rotate the locking member to the release position. As soon as the secondary locking member 42 is aligned with the vertical portions 13 of the L-shaped apertures 11 the secondary locking member moves vertically, and the locking member 29 moves to the release position. The spring 33 then applies a force to the rocking member 37 causing the ejector 24 to move forwardly, thus ejecting the tongue from the buckle. Both the springs 33 and 36 again pass through a "dead centre" condition during this cycle of events. It will be appreciated that if the slider 19 moves rearwardly at any time, the buckle may be moved to the release condition. A similar situation will arise if the secondary locking element 42 moves rearwardly. The present invention provides means, as illustrated in Figures 6 to 8, which serve to prevent the slider 19 from moving rearwardly under any accelerational forces applied to the buckle. The means comprise the pivotally mounted locking weights 45 and the secondary weights 50. The locking weight 45, as appearing on each side of the buckle, is ordinarily spring biassed, by means of the spring 49, to the position illustrated in Figure 6. It can be seen that the great proportion of the mass of the weight 45 is located above the axis defined by the axle 43. The forwardly extending arm 47 is so positioned, with regard to the slider 19, with the arm 47 located under the rearwardly extending arm 21 on the slider 19 so that the slider may move rearwardly. The secondary arm 48 is adjacent the second mass 50. If the buckle is subjected to an accelerational force towards the right, as indicated by the arrow 59 in Figure 7, the moment of inertia of the mass 45 about its pivoting axis is such that the mass will rotate, compressing the spring 49, but moving the mass 45 to a position such that the horizontally extending arm 47 is located adjacent a rear face of one of the side arms 21 provided on the slider 19, thus preventing the slider 19 from moving towards the rear. Simultaneously the second counter-weight 50 will tend to move towards the right, in the direction illustrated by the arrow 58. However, if the buckle is subjected to an acceleration in the direction illustrated by the arrow 59, as shown in Figure 8, (which may be a deceleration following the acceleration described with reference to Figure 7) the secondary weight 50, rotates in a clockwise sense. The moment of inertia of the secondary weight 50 is selected to be greater than the moment of inertia of the weight 45 by such a degree that as the secondary weight 50 rotates in a clockwise direction as indicated by the arrow 60 in Figure 8, as a consequence of the acceleration in the direction of the arrow 59, the secondary weight 50 engages the downwardly extending arm 48 causing the locking weight 45 to rotate in the clockwise direction, compressing the spring 49 so that the weight 45 again enters the position illustrated in Figure 8 in which it prevents rearward movement of the slider. It will thus be appreciated that the present invention provides two co-operating rotating weights each with a predetermined moment of inertia, the moment of inertia of one weight being significantly greater than the lesser moment of inertia being adapted to rotate, under its inertia, to a position in which it prevents inadvertent opening of the buckle when subjected to acceleration in one sense, and the member having the greater moment of inertia rotating to drive the first member to the said position when the buckle is subjected to acceleration in the opposite sense. Figure 9 is a rear perspective view of a buckle, as proposed to be manufactured, incorporating the invention. The various components of the buckle are identified using reference numbers as utilised above. It is to understood that whilst the invention has been described with reference to one particular example of a buckle, the invention may be applied to any buckle in which a slider is moved to actuate a locking mechanism and move the locking mechanism to a release condition. The features disclosed in the foregoing description, in the claims and/or in the accompanying drawings may, both, separately and in any combination thereof, be material for realising the invention in diverse forms thereof.

Claims: A buckle for use with a safety belt system, said buckle comprising a locking mechanism(34) adapted to receive and retain the tongue(51) mounted on a safety belt, said mechanism incorporating a manually operable slider(19) element operable to release the locking mechanism(34) to permit the tongue to be withdrawn from the buckle, the buckle comprising an inertia element in the form of a pivotally mounted weight(45) responsive to acceleration in at least one direction relative to the buckle to prevent said locking mechanism from moving to a release condition, the pivotally mounted weight is provided with part thereof(47) which, in an initial condition, lies adjacent part(21) of the slider(19) so that the slider can move freely but which, when the weight has moved pivotally as a consequence of the sensed acceleration, engages the slider when the slider starts to move towards the release position, thus preventing the slider from moving to the release position, characterised in that a second pivotally mounted weight(50) is provided, the second weight being dimensioned and positioned so that when subjected to an acceleration in a direction opposite to the sense of said one direction the second weight(50) engages part(48) of the first weight(45) and moves the first weight against the effect of its own inertia to a position in which the said part(47) of the first weight prevents operation of the locking mechanism. A buckle according to Claim 1 wherein the first weight(45) is provided with an extending arm portion(48) positioned to be engaged by said second weight(50) when the second weight is subjected to said acceleration in the direction opposite to the said one direction. A buckle according to any one of the preceding Claims wherein the first weight(45) is provided with a protruding arm(47) comprising the said part thereof to engage the slider, the end of the arm being adapted to engage the slider. A buckle according to any one of the preceding Claims wherein the said pivotally mounted weights(45,50) are mounted for pivotal movement about axes(43,44) substantially lying in the plane along which the tongue (5) moves.

Inventors: AUBRY, CLAUDE BERNARD
Applicants: GENERAL ENGINEERING (NETHERLANDS) B.V.
Application year: 1989
Main classification: A44B11
IPC codes: A44B11