GB2354936A - Vehicle seat for reducing whiplash - Google Patents

Abstract

A vehicle seat 1 is adapted to pivot rearwardly about an axis close to the rear seat mounting 6 in the event of a rear impact. Energy absorbing means are provided so that, as the seat pivots rearwardly, energy is absorbed and whiplash injuries are reduced. A catch (33, Fig. 5) is also provided to prevent the pivotal movement of the seat, the catch being released by means responsive to a rear impact. The catch release means preferably comprises an inertia weight 20, which may be pivotally mounted 22, and means to transfer the movement of the inertia weight, relative to the seat, to the catch to release it. The energy absorbing means preferably comprises a deformable tab (13, Figs 2-5), one end of which is secured to the front of the seat 8, and the catch is adapted to overlie the tab to prevent movement of the tab.

Description

2354936 PATENTS ACT 1977 P1370IGB-NF/isd DESCRIPTION OF INVENTION

"IMPROVEMENTS IN OR RELATING TO A VEHICLE SEAT ARRANGEMENT 99 THE PRESENT INVENTION relates to a vehicle seat arrangement.

It has been proposed previously (see, for example, GB-A-2,330,068) to provide a vehicle seat which is adapted, in the event that a rear impact should arise, to move rearwardly pivotally about an axis substantially coincident with the rear legs of the seat, with the rearward pivotal movement of the seat being damped by an appropriate energy-absorbing element. It is believed that a seat which performs in this way may reduce the risk of whiplash injury to the occupant of the seat during a rear impact.

In the arrangement disclosed in GB-A-2,330,068 the front part of the vehicle seat is provided with legs which are connected to the floor of the motor vehicle by means of an energy-absorbing element, the energyabsorbing element incorporating a tab defined in a plate of appropriate material by means of lines of mechanical weakness, one part of the tab being secured to the leg of the seat so that, when the seat moves pivotally about a point in the region of the rear legs of the seat, the tab is deformed, absorbing energy.

I 2 It has been found that an arrangement of this type will work in a satisfactory manner, but there is a risk that the seat may pivot rearwardly if, during ordinary driving of the vehicle, the driver applies the brakes in a very 44strong" manner. The reason for this is that if a driver applies the brakes in a very "strong" manner, the back of the driver applies a very strong rearwardly directed force to the tipper pail of the back of the seat in which the driver is sitting. This tends to rotate or pivot the seat about an axis in the region of the rear legs of the seat. Consequently, there is a tendency for the seat to pivot rearwardly about this axis, and if the force applied by the back of the driver to the back of the seat exceeds a predetermined threshold, the energy-absorbing element, such as the tab described above, will yield permitting the seat to pivot rearwardly. This is clearly undesirable, since not only is the position of the seat altered whilst the driver is braking in a "strong" manner, but also the energy- absorbing device may have to be replaced, depending upon the design of the energy-absorbing device.

The present invention seeks to provide an improved vehicle seat arrangement.

According to this invention there is provided a vehicle seat arrangement, wherein the vehicle seat is adapted to pivot rearwardly about an axis adjacent rear legs supporting the squab of the seat in the event that a rear impact should occur, the vehicle seat arrangement incorporating energy-absorbing means adapted to absorb energy as the seat executes the said rearward pivoting motion, a catch being provided adapted to engage part of the vehicle seat arrangement to prevent the pivotal movement of the seat, means being provided to release the catch in response to a sensed rear impact.

I 3 Preferably the means to release the catch comprise an inertia weight, and means responsive to movement of the inertia weight relative to the vehicle seat to release the catch.

Conveniently the inertia weight is mounted on a pivotally mounted arm, said arm being adapted to pivot in response to movement of the inertia weight relative to the seat, means being provided to transfer the pivotal movement of the arm to the catch to release the catch.

Advantageously the arm is adapted to rotate a pivot rod on rotation of the arm, movement of the pivot rod causing movement of a transfer element, the transfer element being adapted to disengage the catch.

Preferably the means adapted to absorb energy comprise a deformable tab, one end of the tab being secured to a front leg structure of the seat, the catch being adapted to over-lie a portion of the tab to prevent movement of the tab.

Conveniently the catch is constituted by a retainer plate, the retainer plate being movable against a spring bias by the transfer element.

Preferably the retainer plate is retained between an inverted "U"-shaped member and an upper part of a carriage upon which the seat is mounted, and is spring-biased by a helical spring, one end of the spring being retained by the inverted "U"-shaped member and the other end of the spring being connected to the said plate.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be 4 described, by way of example, with reference to the accompanying drawings in which FIGURE I is a side view of part of a vehicle seat incorporating an arrangement in accordance with the invention in an initial condition, FIGURE 2 is a view Corresponding to Figure 1 showing the same components in the position that they may adopt following a rear impact, FIGURE 3 is a partial exploded view of the arrangement of Figures I and 2 in an initial condition of the seat, FIGURE 4 is a view Corresponding to Figure 3 showing the situation that exists following a rear impact, and FIGURE 5 is an exploded view illustrating essential components of the invention.

Referring initially to Figure 1, a seat in a vehicle comprises a squab I and a back-rest 2. The squab I of the seat is connected by means of rear legs 3 to the upper parts of carriages 4 which are movably mounted on parallel rails 5. Only one carriage 4 and rail 5 is shown in the drawings. The rail 5 is provided with bolts 6 and 7 to secure the rail to the floor of the motor vehicle. The squab I of the seat is provided with a front leg assembly 8 which is secured to a forward part of the carriage 5.

As can be seen more clearly in Figure 3, the upper part of the carriage 4 is defined by a plate 10 which has two parallel lines of weakness 11, 12 formed therein which define a deformable tab I'). The forward part of the deformable tab 13 defines an aperture and a bolt 14 passes through that aperture to secure the forward end of the defon-nable tab 13 to the front leg assembly 8 of the seat.

The seat arrangement is provided with a catch mechanism which, in an initial position, ensures that the deformable tab 13 is not deformed, thus retaining the seat in its initial position. However, the catch can be moved to a release position, in response to a rear impact being sensed, to enable the seat to pivot about an axis in the region of the rear legs of the seat, with a consequent energy-absorbing deformation of the tab 13.

The catch arrangement incorporates an inertia mass 20 mounted at the lower end of an aim 21 which is pivotally mounted by means of a rod 22 on the carriage 4. A pin 23 provided on the arm is connected by means of a spring 24 to a further pin 25 provided on a first upstanding plate 26 mounted on the carriage. The spring tends to keep the arm 21 in an initial vertical position as shown in Figure 1.

The rod 22, on which the arm 21 is fixedly mounted, is supported at one end by the first upstanding support plates 26, and a second corresponding support plate 27 provided on the upper part of the carriage 4, as can be seen most clearly in Figure 5. The other end of the rod is associated with an equivalent arrangement provided on the other carriage 4 on the other rail 5. The said one end of the rod 22 is provided with a radially extending finger 29 provided in the region of the upstanding plates 26, 27. The finger 29 engaging one end 30 of a generally rectangular loop 31 formed of a rigid wire. The loop 31 forms a transfer element to transfer movement of the rod 22 to a catch to disengage the catch.

6 The loop 31 extends forwardly from the rod 22, the wire of the loop 31 passing to either side of the fi-ont leg assembly 8 of the seat as can be seen most clearly in Figure 5. The forward end 32 of the loop 31 is engaged by two claws 33 which extend arcuately upwardly from the rearward end of a planar retainer plate 34. The retainer plate 34 has a forwardly extending arm 35 which extends away from the claws 33 and which passes through a first washer 36, through the centre of a helical compression spring 37 and through a second washer 38. At the far side of the second washer 38 a locking pin 39 extends through an aperture 40 formed at the forward end of the arm 35.

The retainer plate 34 is provided, on its upper and lower surfaces, with grooves 42 which extend generally parallel with the arm 35. The retainer plate 34 is spaced from the upper surface of the terminal part of the carriage 4 by means of four ball bearings 43) which are received within grooves 42 provided on the under-surface of the plate 34. Located immediately above the plate 34 are four more ball bearings 44, received in the grooves 42 on the upper surface of the plate. Mounted above the ball bearings 44 is a plate 45 which is separated by means of a resilient washer46 from an inverted "U"-shaped saddle member 47 which has a screwthreaded aperture 48 formed in the base thereof The free ends of the arms of the "U"-shaped saddle member are welded or otherwise secured to the carriage. A bolt 49 is provided adapted to screw-threadedly engage the aperture 48 in the saddle member 47. The bolt passes through the washer46, to engage a central part of the plate 45. The plate 45 is thus pressed down towards the retainer plate 34 and the associated ball bearings 43, 44.

The washer 36 is biased firmly against the saddle member 47 by the spring 37. The described alTanoement serves to retain the plate 34 in position C, whilst permitting axial movement of the retainer plate 34 against a bias 7 provided by the spring 37. Trapped beneath the forward end of the plate 34 and the carriage 4 is a resilient plate 5 1 to minimise or prevent rattle.

It is to be appreciated that when the seat is in the initial position, as shown in Figure 1, the arrn 21 is in a vertical position and the forward part of the retainer plate 34 is positioned partly above the forward-most end of the tab 13 provided on the carriage 4. Should the occupant of the vehicle apply a substantial real-ward force to the back of the seat, for example if the occupant of the vehicle is the driver of the vehicle and the driver "strongly" applies the brakes, the retainer plate 34 will prevent the forward-most end of the tab 13 from being deformed upwardly, and thus the seat will be retained in the initial position.

In the event that a rear impact should occur, however, the seat will, together with the rest of the vehicle, move forwardly. As the seat moves forwardly the inertia mass 20 will retain its position and thus the arm 21 will pivot, in a clockwise sense as illustrated, about the axis defined by the rod 22.

As this happens the spring 24 will be extended, and the rod 22 will rotate, thus moving the wire loop 31 forwardly. As the wire loop 31 moves forwardly so the plate 34 will move forwardly as a consequence of a spring bias applied to the plate by the spring 3) 7.

As the retainer plate 34 moves forwardly, it moves to a position in which the forward end of the tab 13 is unobstructed.

Should a rearward force be applied to the back of the seat as a consequence of the inertia of the occupant of the seat, during the rear impact, then, if the force exceeds a predetermined threshold, the tab 13 will be deformed out of the plane defined by the plate 10 forming the upper part of the 8 carriage 4, with a consequent absorption of energy. The seat will thus pivot rearwardly about an axis in the region of the rear leg 4 of the seat, and the tab 13 will occupy a more elevated position as shown, for example, in Figure 2 and in Figure 4.

As the seat pivots energy will be absorbed, and it is believed that this will minimise the risk of whiplash injury being experienced by the occupant of the seat.

It is to be appreciated that the rod 20, which extends transversely across the lower part of the seat, will be associated with an equivalent arrangement provided on the other carriage supporting the other side of the vehicle seat.

In the present specification "comprise" means "includes or consists of' and "comprising" means "Including or consisting of'.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof

Claims (1)

1. 9 CLAIMS:

   1. A vehicle seat arrangement, wherein the vehicle seat is adapted to pivot rearwardly about an axis adjacent rear legs supporting the squab of the seat in the event that a rear impact should occur, the vehicle seat arrangement incorporating energy- absorbing means adapted to absorb energy as the seat executes the said rearward pivoting motion, a catch being provided adapted to engage part of the vehicle seat arrangement to prevent the pivotal movement of the seat, means being provided to release the catch in response to a sensed rear impact.

   2. A vehicle seat arrangement according to Claim I wherein the means to release the catch comprise an inertia weight, and means responsive to movement of the inertia weight relative to the vehicle seat to release the catch.

   3. An arrangement according to Claim 2 wherein the inertia weight is mounted on a pivotally mounted arm, said arm being adapted to pivot in response to movement of the inertia weight relative to the seat, means being provided to transfer the pivotal movement of the arm to the catch to release the catch.

   4. An arrangement according to Claim 3 wherein the arm is adapted to rotate a pivot rod on rotation of the arm, movement of the pivot rod causing movement of a transfer element, the transfer element being adapted to disengage the catch.

   5. An arrangement according to any one of the preceding Claims wherein the means adapted to absorb energy comprise a deformable tab, one end of the tab being secured to a front leg structure of the seat, the catch being adapted to over-lie a portion of the tab to prevent movement of the tab.

   6. An arrangement according to Claim 5 wherein the catch is constituted by a retainer plate, the retainer plate being movable against a spring bias by the transfer element.

   7. An arrangement according to Claim 6 wherein the retainer plate is retained between an inverted "U"-shaped member and an upper part of a carnage upon which the seat is mounted, and is spring-biased by a helical spring, one end of the spring being retained by the inverted "U"-shaped member and the other end of the spring being connected to the said plate.

   8. A vehicle seat arrangement substantially as herein described with reference to and as shown in the accompanying drawings.

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