GB2357030A

GB2357030A - Anti submarining seat

Info

Publication number: GB2357030A
Application number: GB9929162A
Authority: GB
Inventors: Yousuf Shaheen
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1999-12-09
Filing date: 1999-12-09
Publication date: 2001-06-13
Anticipated expiration: 2019-12-09
Also published as: WO2001041525A1; GB2357030B; GB9929162D0; WO2001041525A8; GB2357030A8

Abstract

A vehicle seat has a squab (3) and a back-rest (4). The squab comprises a framework (7) supporting a yieldable spring frame (11) to support the posterior of the occupant of the seat. A transversely extending strap (14) extends across the squab within a cushion (12). The ends of the strap are connected to the framework by connectors (15), at least one connector is adapted to extend in length, whilst providing a resistive force, when subjected to a predetermined substantial downward force. Thus, if the posterior of the occupant of the seat is driven downwardly during a forward impact, whilst limited downward movement is permitted, extensive downward movement will initially be retarded as the connector extends and will then be terminated. This minimises the risk of the occupant of the seat "submarining" beneath a seat-belt.

Description

2357030 PATENTS ACT 1977 P13856G13-NF/ec

DESCRIPTION OF INVENTION

IMPROVEMENTS IN RELATING TO A VEHICLE SEAT The present invention relates to a vehicle seat and more particularly relates to a vehicle seat suitable for use in a motor vehicle such as a motor car or automobile.

When a motor vehicle is involved in a frontal impact, the motor vehicle can decelerate extremely rapidly. The occupants of the vehicle may be held in position, in their seats, by means of a seat belt, but nevertheless there is still a tendency for the occupants of the seat to "submarine" beneath the seat belts.

Thus the legs and lower part of the torso of the occupant of the seat may move forwardly, sliding under a lap belt that forms part of the seat belt. This is disadvantageous. Various proposals have been made to overcome this problem.

For example US-A-4623192 shows a vehicle seat which incorporates, within the squab of the seat, a push-up member which moves upwards within a seat cushion during an accident situation. The push-up member forms a protuberance at the ftont pail of the seat cushion to limit the movement of the pelvis of the occupant of the seat towards the front of the vehicle. DE-A 4032385 shows a similar arrangement.

2 Arrangements of this type may give rise to difficulties in that the front part of the squab of the seat may be relatively hard, due to the presence of the push-up member, and this may lead to blood circulation problems in the legs of an occupant of the seat.

The present invention seeks to provide an improved vehicle seat.

According to this invention there is provided a vehicle seat, the seat comprising a squab and a back rest, the squab comprising a framework supporting resiliently yieldable means to support the posterior of the occupant of the seat, the squab being provided with a transversely extending strap element having opposed ends each connected to the framework by a respective connector, at least one connector being adapted to extend m length, whilst providing a resistive force, when subjected to a predetermined substantial force.

Preferably the squab is formed by springing supporting a resilient cushion, said belt extending through the cushion.

Conveniently the belt extends through a sleeve formed in the cushion, the belt being freely movable within the sleeve.

Advantageously the or each connector comprises an oval ring which is adapted to deform when subjected to said predetermined substantial force.

In one embodiment the belt is directly connected to the connectors.

In an alternative embodiment at least one end of the belt is connected to a said connector by a spring arrangement.

3 Conveniently the spring arrangement comprises an element secured to the end of the belt, the element being associated with resilient means which bias said element away from part of the connector connected to the framework.

Advantageously the spring arrangement is associated with means responsive to a predetermined deceleration of the vehicle to clamp the belt directly to the connector.

Preferably the means responsive to deceleration comprise an inertia member, the inertia member having an initial position in which part of the inertia member engages part of a spring biased wedge member to retain the wedge member in a predetermined position in which the belt is free to move, the inertia member being adapted to move to a second position in response to a predetermined deceleration of the vehicle, the second position of the inertia member being such that the wedge member may move to a clamping position in which the belt is clamped.

Advantageously the wedge member is received within a housing defining a through passage, the walls of the through passage converging, the belt extends through the passage between the wedge member and one of the converging walls of the passage, the inertia member being pivotally mounted on the housing and carrying an abutment engageable with a co-operating abutment formed on the wedge member.

Conveniently the abutment on the inertia member comprises a finger extending in to an aperture formed in the inertia member, the abutment carried by the wedge comprising one of two upstanding fingers, the second upstanding finger provided on the wedge being adapted to be in engagement with one side 4 wall of the aperture formed in the inertia member when the abutment member on the inertia member is engaging the abutment member formed on the wedge.

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 example, with reference to the accompanying drawings in which:

FIGURE 1 is a perspective view of a vehicle seat incorporating one embodiment of the invention, FIGURE 2 is a perspective view of the seat of figure 1 with parts thereof cut away for the sake of illustration, FIGURE 3 is a side view of the seat of figures 1 and 2 showing the occupant of the seat in a normal condition, FIGURE 4 is a view corresponding to figure 3 showing the occupant of the seat in an impact situation, FIGURE 5 is a view showing a connector for the belt before an impact, FIGURE 6 is a view corresponding to Figure 5 showing the connector after an impact, FIGURE 7 is a front view, partly in section, of the seat before an impact, FIGURE 8 is a view corresponding to figure 9 showing the seat after an impact, FIGURE 9 is a diagrammatic sectional view taken generally on the line of the plane IX as shown in Figure 3, with part of the cushioning of the seat being cut away showing a modified embodiment of the invention, FIGURE 10 is a detailed perspective view of a belt and associated connectors fonning part of the embodiment of the seat shown in Figure 9 before an impact, FIGURE 11 is a perspective view of a connector and shock absorber assembly forming part of the embodiment of the invention shown in Figures 9 and 10, FIGURE 12 is a sectional view of the shock absorber assembly, FIGURE 13 is an exploded view of the connector and shock absorber assembly, FIGURE 14 is a top view of the connector and shock absorber assembly in an ordinary situation, and FIGURE 15 is a view corresponding to Figure 14 illustrating connector and the shock absorber assembly in an impact situation.

Figure 1 illustrates a vehicle seat 1 occupied by an occupant 2. The vehicle seat incorporates a squab 3 and a back rest 4 which carries a head rest 5. A safety belt 6 of a conventional lap -and- diagonal forin is provided for use by the occupant 2 of the seat.

6 As shown more clearly in Figure 2 the squab 3 of the seat comprises a framework 7 constituted by side members, such as the side member 8 and transverse frame members, such as the transverse front bar 9 and the transverse rear bar 10. The framework 7 supports springs 11 which lie underneath a padded cushion 12 that forms the squab 3 of the seat. Contained within the cushion 12 is a sleeve 13 which extends transversely of the seat at a substantially central location. The sleeve 13 accommodates a belt 14, the ends of which are connected to the side members, such as the side member 8, of the framework 7 by means of respective connectors 15. The sleeve 13 and the belt 14 are such that the belt 14 may slide freely within the sleeve 13.

Figure 3 illustrates the occupant 2 of the seat in a normal condition. The posterior of the occupant of the seat is supported by the squab of the seat. The squab yields in a resilient way due to the cushioning effect of the cushion 12 and the resilient effect of the springs 11. There is sufficient slack in the belt 14 for the belt to remain untensioned during such "normal" yielding of the squab.

Thus the belt cannot be felt or detected by the occupant of the seat.

If the vehicle in which the seat is mounted is involved in a frontal impact, such that the vehicle decelerates extremely suddenly, the occupant 2 of the scat 1 will be thrown forwardly and also downwardly as the lower part of the torso of the occupant 2 commences a "submanning" action. In this situation the posterior of the occupant exerts a substantial downward force on the cushion 12 that forms part of the squab 3 of the seat. This downward force transmitted to the belt 14. The belt thus becomes tensioned. To prevent the belt suddenly becoming tight (thus suddenly arresting the movement of the posterior of the occupant of the seat which might cause injuries) the connectors 15, as will become clearer from the following description, are designed to extend in length whilst providing a resilient force when subjected to a predetermined 7 substantial force. The connectors act as force limiters. Thus, as can be seen from Figure 4, the connectors pay out an extra length of belt permitting the posterior of the occupant of the seat to sink downwardly into the squab of the seat, against a resistive force. The belt will thus gradually decelerate and limit downward movement of the posterior of the occupant of the seat. Thus, without the risk of injury that might arise if the belt suddenly tightened, the probability of submarining occurring is reduced.

Turning now to Figure 5 it can be seen that the connector 15 is constituted by a oval metal ring. An upper horizontal limb 16 of the ring is provided with two protrusions 17, 18 which are directed towards the interior of the ring. These protrusions act as locating means which locate the part of the belt 14 which passes through the ring. A lower horizontal limb 19 of the ring is provided with an enlarged central region 20 provided with a through bore 21 adapted to receive a bolt or the like to fasten the connector 15 to the side member 8 of the framework forming the squab 3 of the seat.

The horizontal limbs 16, 19 are interconnected by arcuate end portions 22, 23 of the oval ring, which are formed of a malleable material.

Figure 6 illustrates the connector 15 of Figure 5 after an impact situation has arisen. It is to be appreciated that during an impact situation a very substantial tension or force is applied to the oval ling by the belt 14 such that the arcuate end portions 22, 23, and also the terminal pails of the upper limb 16 and the lower limb 19 become substantially straightened. The effect is that the parts of the upper limb 16 between the protrusions 17 and 18 moves away from the aperture 21 formed in the enlarged portion 20 of the lower limb 19. Thus, effectively, the belt 14 is "paid ouf' thus permitting the posterior of the 8 occupant 2 of the seat to sink downwardly into the squab against a resistive force. The oval ring thus acts as a force limiter.

Figures 9 to 15 illustrate a modified embodiment of the invention in which one connector which connects one end of the belt to the framework of the seat is provided with a spring arrangement. The connector provided with the spring arrangement is shown as the connector 30 in Figures 9 and 10. It is to be appreciated that the remaining components of the vehicle seat, in this embodiment, will be as described above with reference to Figures I to 8 and the same reference numerals will be used for like parts which will not be re described.

The spring arrangement, which is shown in greater detail in Figures I I to 13, is provided so that both ends of the belt 14 are not held absolutely rigidly by the connectors 15, but instead the belt is provided with a certain amount of "give" or ability to yield against a spring force, without any deformable element being deferred. Thus, at all times the belt may be relatively "fight", with no slack, while yielding against the gentle spring bias provided by the spring aff angenient during "normal" yielding of the squab so that the belt cannot be felt or detected by an occupant of the seat. However, in response to sever deceleration of the vehicle, the belt is clamped to a force limiter in the form of an oval ring similar to that described above. Thus, in an accident, the posterior of the occupant moves down and immediately encounters the resistive force and does not, in contrast to the embodiment of Figures I to 7, move downwardly relatively freely until the belt 14 is tightened.

Referring to Figures I I to 13 the spring arrangement is illustrated in combination with the connector 30. The connector 30 is constituted by a plate 3 1. The plate 31 is of complex form and defines, at one end, an oval 9 aperture 32, and thus this lower end of the plate 31 can be considered to be formed by an oval ring 33. The major axis of the oval ring extends transversely of the axis of the plate 3 1. A transverse lower limb 34 of the ring 33 is provided with an enlarged central portion which defines a central aperture 35. A rivet (not shown) may pass through the aperture 35 to connect the plate 31 to a side-frame of a seat. The lower limb 34 is connected by arcuate connecting portions 36 to an upper transverse limb 37. The central region of the upper transverse limb 37 is connected by an axially extending connecting portion 38 (extending axially of the plate 31) provided with a central aperture 39 to a terminal region 40 of planar form which is provided, at the edge thereof remote from the connecting portion 3 8, with a downwardly directed lip 4 1.

The shock absorber 30 includes a housing element 42. The housing element 42 comprises a base plate 43 with two upstanding side walls 44, 45 and an upper wall 46. A through-passage is defined between the base plate 43 the side walls 45 and the upper wall 46. However, as can be seen from Figure 12, the under surface 47 of the upper wall 46 is inclined downwardly relative to the upper surface of the base plate 43 so that the through passage is of tapering form with opposed converging walls. The upper wall 46 defines on its upper surface an upstanding boss 48 which is centrally located and also defines, adjacent one corner of the upper surface, an upstanding lug 49 provided with an inwardly directed protrusion 50 adapted to receive one end of a helical compression spring 5 1.

The base plate 43 of the housing element 42 is provided with a centrally located axial projecting lug 52 extending away from the end of the through passage of largest cross-sectional area. The lug 52 is provided with an aperture 53. The terminal region 40 of the plate 31 may be passed through the through passage of the housing 42 with the lip 41 adjacent one edge of the base plate 43, and with the aperture 53 in the protruding lug 52 then being aligned with the aperture 39 formed in the connecting portion 38 of the metal plate 31. A rivet, such as the rivet 54 as shown in Figure 12 may pass through the co aligned apertures to connect the housing 42 to the plate 3 1.

A wedge member 60 is provided having a lower face 61 with a high friction configuration, such as a serrated configuration. The wedge member 60 has an upper face 62 which is inclined relative to the plane of the lower face 61. Projecting upwardly from a rearward part of the wedge member 60 is a stop assembly 63. The stop assembly 63 comprises two upstanding fingers 64, which are slightly spaced apart.

From the rear face of the wedge member 60 parallel spaced arms 66, 67 project axially. The arms 66, 67 are associated with a spring element 68 which comprises two parallel, spaced apart helical compression spring portions 69, 70 which are interconnected by means of a transverse bar 71. The spring portion 69 extends around the arm 66 and the spring portion 70 extends around the arm 67. The ends of the spring portions 69, 70 abut the rear face of the wedge member 60. The bar 71 thus "floats" against the spring bias provided by the spring portions 69, 70.

One end of the belt 14 is passed around the transverse bar 71 of the spring element 68 and stitched as at 72, so that the end of the belt 14 is securely connected to the transverse bar 7 1.

The wedge member 60 is located within the housing element 42 with the inclined upper face 62 of the wedge 60 abutting the lower inclined face 47 of the upper wall 46 of the housing 42. The belt 14 passes through the through- 11 passage formed in the housing between the serrated under face 61 of the wedge and the upper surface of the plate 3 1.

An inertia member 75 is provided which is pivotally mounted on the boss 48 provided on the upper wall 46 of the housing 42. The inertia member is provided with an inertia mass 76 at one end. The mass is connected to a central substantially planar region 77 which defines an arcuate aperture 78 having a finger 79 directed axially into the aperture 78. Adjacent to the base of finger 79 a circular aperture 80 is provided dimension to receive the boss 48.

On the side of the aperture 80 remote from the mass 76 is a lug 8 1 carrying a protrusion 82. When the inertia member 75 has been mounted on the boss 48 it can be maintained in position by a locking washer 83. The inertia member 75 is thus mounted for pivotal movement about the axis of the boss 48. The protrusion 82 on the lug 81 is then engaged with the free end of the compression spring 5 1.

The spring arrangement 30 is ordinarily in the condition illustrated in Figures 11 and 14. The spring 5 1 has the respective ends thereof engaged with the protrusion 50 provided on the lug 49 on the upper wall 46 of the housing element 42 and the protrusion 82 fonned on the lug 81 carded by the inertia member. The spring 51 serves to bias the inertia member to the position illustrated in Figures 11 and 14.

When the inertia member is in the position illustrated in Figures 11 and 14 the finger 79 that extends into the arcuate aperture 78 engages one of the fingers 64 of the stop assembly 63. The stop assembly 63) is received within the arcuate aperture 78. When the inertia member 75 is in the position illustrated in Figures 11 and 14 the second upstanding finger 65 of the stop assembly 63 engages one side wall of the oval aperture 78 thus preventing the 12 inertia member 75 moving beyond the position in which the finger 79 engages the finger 64. Thus the spring 51 moves the element 75 to a position in which the finger 65 engages the side wall of the aperture 78, this automatically being the position in which the finger 79 engages the finger 64. The engagement between the finger 79 provided on the inertia member 75 and the finger 64 of the stop assembly 63 prevents the wedge member 60 from moving through the housing element 42. The wedge member 60 is biased towards the housing by the effect of the force applied to the rear face of the wedge member 60 by the spring portions 69, 70.

The wedge member 60 is so located within the housing that there is sufficient space between the lower face 61 of the wedge member 60 and the upper face of the plate 3 1 for the belt 14 to slide freely through the housing.

Thus the belt 14 can slide freely through the housing and the belt can move in and out against a gentle resistive force provided by the helical compression spring portions 69, 70 as the bar 7 1, which is connected to the end of the belt 14, moves towards and away from the wedge member 62.

Thus an occupant of the seat will not be able to detect the presence of the belt as the squab of the seat yields in a "normal" way.

In the event that the vehicle in which the described arrangement is mounted is involved in an impact, the vehicle will decelerate. The spring arrangement is mounted so that in response to such deceleration there will be a tendency for the inertia mass 76 of the inertia member 75 to move in the direction indicated by arrow 83 in Figure 14. The inertia member 75 thus moves against a resistive spring force provided by the spring 51 and moves to the position shown in Figure 15. As the inertia member 75 moves to the 13 position shown in Figure 15 the finger 79 on the inertia member becomes disengaged from the upstanding finger 64 of the stop assembly 63 provided on the wedge member 60, and is aligned with a space between the fingers 64 and of the stop assembly. The wedge member 60 may thus move forwardly towards the housing element 42. The wedge member will move in this direction since it is envisaged that, in any situation where sufficient deceleration is present to move the inertia member from the position shown in Figure 14 to the position shown in Figure 15, the occupant of the seat will be bearing downwardly upon the squab of the seat, thus tending to apply tension to the belt 14. The wedge member 60 will thus be moved immediately to a clamping position in which the belt 14 is clamped between the serrated lower face 61 of the wedge member 60 and the upper surface of the plate 3 1. The belt is thus fast with the housing element 42. Tension applied to the belt is thus transferred to the housing element 42 and that tension is thus applied to the oval ring 33.

The oval ring 33 will deform in the same way as the previously described oval ring 15, thus providing a movement of the housing element 42 against a resistive force. Thus, again, a force limiter effect is provided.

In both of the above described embodiments of the invention a safety device is provided which, in normal use of the vehicle seat, is undetectable or virtually undetectable by the occupant of the seat. However, in an impact situation, in which there is a tendency for the occupant of the seat to C'submarine", downward movement of the posterior of the occupant of the seat on the squab of the seat is resisted by a strap element which, in use, acts as a force limiter since it permits downward movement of the posterior of the occupant of the seat over a limited distance against a predetermined resisting force. Thus the posterior of the occupant of the seat may move downwardly only to a limited extent, and the downward movement of the posterior of the seat is effected against a resistive force meaning that the posterior of the 14 occupant of the seat does not suddenly encounter an immovable barrier, such as a pre-tensioned belt, which could impart injuries to the occupant of the seat.

Whilst, in the described embodiments, separate force limiters have been provided at each end of the belt 14, in the modified embodiment a force limiter may only be provided at one end of the belt.

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

CLAIMS:

1. A vehicle seat, the seat comprising a squab and a back rest, the squab comprising a framework supporting resiliently yieldable means to support the posterior of the occupant of the seat, the squab being provided with a transversely extending strap element having opposed ends each connected to the framework by a respective connector, at least one connector being adapted to extend in length, whilst providing a resistive force, when subjected to a predetermined substantial force.

2. A seat according to Claim 1 wherein the squab is formed by springing supporting a resilient cushion, said belt extending through the cushion.

3. A seat according to Claim 2 wherein the belt extends through a sleeve formed in the cushion, the belt being freely movable within the sleeve.

4. A seat according to any one of the preceding Claims wherein the or each connector comprises an oval ring which is adapted to deform when subjected to said predetermined substantial force.

5. The seat according to any one of the preceding Claims wherein the belt is directly connected to the connectors.

6. A seat according to any one of Claims 1 to 4 wherein at least one end of the belt is connected to a said connector by a spring arrangement.

7. A seat according to Claim 6 wherem the spring arrangement comprises an element secured to the end of the belt, the element being associated 16 with resilient means which bias said element away from part of the connector connected to the framework.

8. A seat according to Claim 6 or 7 wherein the spring arrangement is associated with means responsive to a predetermined deceleration of the vehicle to clamp the belt directly to the connector.

9. A seat according to Claim 8 wherein the means responsive to deceleration comprise an inertia member, the inertia member having an initial position in which part of the inertia member engages part of the spring biased wedge member to retain the wedge member in a predetermined position in which the belt is free to move, the inertia member being adapted to move to a second position in response to a predetermined deceleration of the vehicle, the second position of the inertia member being such that the wedge member may move to a clamping position in which the belt is clamped.

10. A seat according to Claim 9 wherein the wedge member is received within a housing defining a through passage, the walls of the through passage converging, the belt extends through the passage between the wedge member and one of the converging walls of the passage, the inertia member being pivotally mounted on the housing and carrying an abutment engageable with a co-operating abutment formed on the Wedge member.

11. A seat according to Claim 10 wherein the abutment on the inertia member comprises a finger extending in to an aperture formed in the inertia member, the abutment carried by the wedge comprising one of two upstanding fingers, the second upstanding finger provided on the 17 wedge being adapted to be in engagement with one side wall of the aperture formed in the inertia member when the abutment member on the inertia member is engaging the abutment member formed on the wedge.

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

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