[0001] 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.
[0002] Many types of buckle have been proposed for use with a safety 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.
[0003] 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.
[0004] 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 per mitted travel.
[0005] 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 pretensioner. 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 instance that an accident has been sensed.
[0006] The present invention seeks to provide an improved buckle in which the above-described
disadvantage of the existing buckles, is obviated.
[0007] 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,
characterised in that 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 toward the
release position, thus preventing the slider from moving to the release position.
[0008] Preferably 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.
[0009] 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.
[0010] 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.
[0011] Advantageously said pivotally mounted weight is mounted for pivotal movement about
an axis which is substantially lying in the plan along which the slider element moves.
[0012] In order that the invention may be more readily understood and so 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 locked condition,
FIGURE 3 is a view corresponding to Figure 2 illustrating the buckle in the unlocked
condition,
FIGURE 4 is a sectional view of the buckle showing the buckle in the locked condition,
FIGURE 5 is a sectional view corresponding to Figure 4 showing the buckle in the unlocked
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.
[0013] 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 walls 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.
[0014] The base 2 of the channel is provided with two elongate apertures 9 adjacent the
lower edges of the side wall 3,4 each terminating, at a transverse forward edge 10.
[0015] 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 is provided with an outwardly extending tab 15 and two further
apertures 16,17 which are of circular form.
[0016] The upper parts of the sides walls 3,4 are recessed, 18 toward the rear of the channel
member.
[0017] 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 the 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.
[0018] 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 formed in the base 2 of the channel 1.
[0019] 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 rivit 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 downwardly 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 surface 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.
[0020] 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 rocket 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.
[0021] 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 push-button 19.
[0022] 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 50 is provided which extends between a part of the portion 46 and
an outwardly directed tab 5 provided on the side wall of the channel.
[0023] The second axle 44 carries secondary locking weights 50 each of which comprise a
relatively large mass located below the pivot axis defined by the axle 44.
[0024] The described components, when assembled, form a buckle which defines an entry path
for a tongue 51 as conventionally found on a safety 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.
[0025] The operative components of the buckle, as described above will, of course, be surrounded
by an appro priate housing 56, shown in phantom in Figures 4 and 5.
[0026] Referring now to Figures 2 and 4 it is to be seen that the slider 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 slider 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 defined by the rivet 5 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 slider 24. Thus the slider 24 is biassed forwardly.
[0027] 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.
[0028] When the tongue 51 is inserted into the buckle the curve end 24 of the tongue engages
the recess 25 provided in the slider 24 and the slider 24 then moves rearwardly, thus
also moving rearwardly the lower part of the rocket 37. The lower part of the rocker
37 thus moves rearwardly and the rocket 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.
[0029] 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 push-button 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 reawardly, thus causing the rocking member to
commence rotation in an anti-clockwise direction. Also the spring 28 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 lock ing 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.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] If the buckle is subjected to an accelerational force towards the right, as indicated
by the arrow 53 in Figure 7, the moment if 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 pos ition 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
54.
[0034] However, if the buckle is subjected to an acceleration in the direction illustrated
by the arrow 55, 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
56 in Figure 8, as a consequence of the acceleration in the direction of the arrow
55, the secondary weight 50 engages the downwardly extending arm 48 causing the locking
member 45 to rotate in the clockwise direction, compressing the spring 49 so that
the member 45 again enters the position illustrated in Figure 8 in which it prevents
rearward movement of the slider.
[0035] 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 moment of inertia of the other,
the member having 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.
[0036] Figure 9 is a rear prospective 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.
[0037] It is to be 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.
[0038] 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 is diverse forms thereof.
1. 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, characterised in that 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 toward the release position, thus preventing the slider from
moving to the release position.
2. A buckle according to Claim 1 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.
3. A buckle according to Claim 2 wherein 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.
4. A buckle according to any one of the preceding Claims wherein the first weight
is provided with a protruding arm comprising the first part thereof to engage the
slider, the end of the arm being adapted to engage the slider.
5. A buckle according to any one of the preceding Claims wherein the said pivotally
mounted weight is mounted for pivotal movement about an axis which is substantially
lying in the plane along which the slider element moves.