WO2008036005A1

WO2008036005A1 - Headrest system for vehicle seat

Info

Publication number: WO2008036005A1
Application number: PCT/SE2006/001063
Authority: WO
Inventors: Lennart Simonsson
Original assignee: Autoliv Development Ab
Priority date: 2006-09-19
Filing date: 2006-09-19
Publication date: 2008-03-27
Also published as: DE112006004014T5

Abstract

An anti-whiplash headrest system for a vehicle seat wherein only the headrest is activated in less severe impacts whilst in sever impacts both the headrest and the backrest is activated. The backrest has a first moveable threshold device (7, 8, 9) to be activated and moved rearwards by a first threshold force of a seat occupant. The rearward movement is transferred by a first linkage (14) between the first device (7, 8, 9) and the headrest for moving the headrest to a first head-supporting position . An anti-whiplash recliner mechanism (6) may be activated by a second threshold force which mechanism permits a rearward movement of a lower part of the backrest. The backrest movement is transferred by a second linkage (17) between the first device (7 , 8, 9) and the squab (5) whereby the headrest (3) is being further moved to a second head-supporting position.

Description

HEADREST SYSTEM FOR VEHICLE SEAT

Technical area

The present invention relates to a headrest system for vehicle seats for preventing whiplash injuries in rear impact situations.

Technical background

In a rear impact situation, neck injuries can be imparted to a seat occupant. The buttocks and the torso of the occupant, which are generally in close contact with the backrest, may be given a rapid acceleration. The head of the occupant, which is normally not in contact with any part of the seat may be given, during the first moments no acceleration at all. Consequently, the buttocks and the torso of the seat occupant may move forwardly, whilst the head due to the inertia remains stationary. This causes the neck of the occupant to bend, until the head makes contact with the headrest, or until the neck itself applies a forward force to the head of the occupant, which may initially tend to rotate the head about a horizontal axis, and then flick the head forwardly. Such movements of the neck and the head can cause injuries known as "whiplash" injuries.

It is known from WO9710117 that whiplash injuries can be reduced if the back of the seat is mounted so that the headrest moves forwardly to support the head of the occupant and that the back of the seat can move in a predetermined manner such that the torso of the occupant will accelerate more gradually.

However, some aspects of prior proposed arrangements might be further improved, such as an arrangement which is flexible in different situation and which posses an improved security level for a seat occupant. Further the arrangement should be reliable but not too complex. Summary of the invention

An object of the present invention is to provide an improved headrest system, which at least partly reduces the above-mentioned aspects. This and other objects are achieved in accordance with the teachings of the present invention, wherein the head rest for a vehicle seat comprises a squab, a backrest and a headrest wherein the backrest being arranged with at least a first moveable threshold device to be activated and moved in a rearward direction by a first threshold force of a seat occupant. A first mechanical connection between the first device and the headrest is adapted to move the headrest in a forward direction to a first head supporting position by a transfer of said first device movement. The squab and the backrest comprise a second movable threshold device to be activated by a second threshold force of a seat occupant to permit a movement of a lower part of the backrest in a rearward direction in relation to the squab. A second mechanical connection, at least between the first moveable threshold device and the squab, is connected in such a way that the headrest is being moved in a forward direction to a second head supporting position in response to said movement of the lower part of the backrest. The second threshold force exceeds the first threshold force.

Thus by mechanical interaction between the moveable threshold devices, the movements of a seat occupant due to a rear impact may be transferred for achieving at least two safety levels and thereby two safety positions of the seat. In less severe impacts corresponding to the first threshold force only a part of the system is activated wherein the headrest is moved to a first head supporting position. In more severe impacts corresponding to the second threshold force both the headrest and the backrest is activated wherein a second headrest position is achieved. A movement of the first moveable threshold devices as in the first position mechanically interacts with the movement of the lower part of the backrest to the second head supporting position. In more severe impacts, pulling forces in the first and second mechanical connection may be transferred to the headrest for achieving the second head supporting position. Consequently by mechanical interaction in such a system, it may take care of different rear impact situations with an improved flexibility and adapted safety. The first and second mechanical connection may define a path to mechanically transfer movements of said first and second moveable threshold device to said headrest. Thus the force transferring connection to the headrest may be mutual and the complexity of system may be reduced. By the word path is meant a force- transferring path or line for mechanical interaction. The path/line preferably extends from the headrest to the squab or an element connected to the squab.

The first moveable threshold device may comprise a movable element, such as a movable plate, a flexible element or a yieldable element which moveable element may be connected to said first mechanical connection. The movable element is preferably adapted to transfer the movements to the first mechanical connection. The rearward movement of the movable element is preferably transferred in a transversal direction.

The second movable threshold device is preferably an anti-whiplash recliner mechanism. Thus, the movement in the rearward direction of such a known mechanism may be used and transferred to the headrest for achieving a reliable system. In such a situation the moveable element may be moved in a direction downwards in relation to the squab .

A first restraint element may be arranged in connection with said first mechanical connection. The threshold activation, which at least initially is the first head supporting position, may easily be achieved. Additionally, the headrest may effectively be kept in its desired position during normal use. The first restraint element may be one of a breaking element, a spring element, a friction element or an electro magnetic element. The breakable element may be a pin or a bolt. Also the restraint element may be a rubber element or a polymeric element, such as a plastic element.

An additional and second restraint element may be arranged in the system. The restraint element may be arranged in connection with said second mechanical connection. The second restraint element may be activated by the first and/or the second threshold force. Thus the movable element may effectively be held in its desired position during normal use at least below the first threshold force. Correspondingly, the second restraint element is one of a breaking element, a spring element, a friction element or an electro magnetic element.

Preferably a first linkage defines the first mechanical connection. A second linkage may define the second mechanical connection. An essentially direct force transfer may efficiently be achieved to form the force- transferring path or extension.

The headrest may be pivotally movable about an axis for supporting a head of a seat occupant. The axis may be arranged at the backrest. Alternatively or additionally the headrest may be slidingly moveable along a track for supporting a head of a seat occupant.

Brief description of the drawings The present invention will now be described in more detail with reference to the accompanying drawings which show preferred embodiments of the invention.

Fig. Ia is a schematic side-view of a headrest system for a vehicle seat according to an embodiment of the invention in a normal-use position.

Fig. Ib shows the system in fig Ia in a first head supporting position. Fig. 2a shows the system in fig Ia in the normal-use position.

Fig. 2b shows the system in fig Ia in a second head supporting position. Fig. 2c shows the system in fig Ia when the upper part of the backrest being in rearward tilted position.

Fig. 3a is a schematic perspective view of a headrest system for a vehicle seat according to another embodiment of the invention in a normal-use position. Fig. 3b shows the system in fig 3a in a second head supporting position.

Fig. 3c shows the system in fig 3a when the upper part of the backrest being in rearward tilted position.

Detailed description of the invention

Fig. Ia schematically shows a headrest system 1 for a vehicle seat 2 according to an embodiment of the invention. A headrest 3 is movingly arranged to the backrest 4. The lower part of the backrest 4 is connected to a squab or cushion 5 via an anti-whiplash recliner mechanism 6. Anti-whiplash recliner mechanisms are well known in the art and therefore will not be described in detail. As an example, reference can made to the Autoliv patent No GB2316442. The backrest 4 comprises a movable element 7 adapted to flex in a direction rearwards in response to forces applied by a seat occupant. The moveable element may according to this embodiment be an area extensive element 7, which preferably extends at least one fifth of the backrest area, more preferably at least one fourth and most preferably at least one third of the area that faces the torso of the occupant. The moveable element may be in a form of a web-shaped element but is preferably a flexible carpet 7. Alternatively the moveable element may be a movable plate connected to a transmission means for transferring the force to the headrest. The carpet 7 is arranged at an upper attachment portion 8 and may also have a lower attachment portion 9. The carpet is at least restrained by an upper restrain element such as a breakable element, which may be arranged at or in connection with the upper attachment portion 8. The lower attachment portion 9 may also comprise a restrain element. The upper attachment portion 8 is connected to a first wire 10 for transferring forces from the carpet 7 when the restrain element is subjected to forces above a first threshold force. However, the carpet or web-shaped element 7 may be adapted to flex in a rearward direction to a limited extent below a first threshold force, preferably without moving the headrest. The headrest 3 is preferably pivotally arranged about an axis 11. Additionally or alternatively the headrest may be slidingly arranged along a track. The headrest has a headrest shaft portion 12 and a lever portion 13, which portions may form a letter L which portions are connected at the axis 11. As shown in fig. Ia, the first wire 10 is connected to the lever portion

13. Thus, the carpet 7 is connected to the headrest via a first mechanical connection preferably as a first linkage 14.

The lower attachment portion 9 for the carpet is connected to a second wire 15. The second wire 15 is guided through the recliner unit 6 for mechanical interaction. The second wire 15 may be attached to the squab 5 or a support plate 18 for the squab or a similar attachment part at a fixation portion 16. Thus, the carpet is connected to the squab via a second mechanical connection preferably as a second linkage 17. Alternatively the second mechanical connection may extend from the squab to the headrest via a movable element or a threshold device. As seen in fig. Ia, the second wire 15 may be guided by guiding means 19 which means is integrated in the recliner mechanism 6. The second wire 15 may be guided with additional guiding means, such as rollers 20.

The mechanism 6 comprises a energy absorbing element (not shown) wherein the backrest may be moved relatively the squab in response to a second threshold force applied to a lower part of the backrest by a seat occupant, see fig. 2b. Thus, the mechanism 6 defines a second movable threshold device.

With reference to fig. Ia, Ib a first head supporting position of the headrest is described. When the seat occupant is pressed rearwards in a rear impact situation or a similar demanding situation exceeding a first threshold force the carpet moves, flexes or yields at least at one attachment portions 8, 9 connected to a restraint element, see fig. Ia. The first wire 10 starts pulling the lever portion 13 for rotational movement at the axle 11 to move the headrest shaft portion 12 and thereby moving the head-supporting portion of the headrest 3 in a direction forward. The headrest is tilted in a direction forwardly to a first head supporting position.

With reference to fig. 2a, 2b a second head supporting position of the headrest is described. When the occupant is pressed rearwards in a rear impact situation or a similar demanding situation exceeding a second threshold force, the lower part of the backrest moves in a direction rearwards. It should be noted that the impact is more severe that corresponds to the second threshold force than the impact that corresponds to the first threshold force. Thus, the movement of the headrest to the first head supporting position may at such a state already be initiated. The lower part of the backrest 4 is moved in a direction rearwards relatively the squab 5 by the anti-whiplash recliner mechanism 6 above the second threshold force. The upper part of the backrest 4 is moved in a direction forwards relatively the squab by the anti-whiplash recliner mechanism 6 wherein the backrest being in an essential upright position.

The movement rearwards of the lower part of the backrest relatively the squab at the shaft 19, pulls the carpet 7 in a direction downwards and thereby may further move the headrest to a second head supporting position as shown in fig. 2b.

Preferably the backrest has a back-tilted position wherein the upper part of the backrest 4 is moved in a direction rearwards relatively the squab 5 by the anti- whiplash recliner mechanism 6, see fig. 2c. The headrest is preferably in a head supporting position at the back- tilted position of the backrest. The angle between the headrest and the backrest may be essentially equal or less than the angle in the second head supporting position .

Fig. 3a-3c shows another embodiment of a headrest system having corresponding reference numbers. Similar features may have corresponding advantages and function. Hence, the carpet is indicated with number 7 which carpet is connected to the first linkage 14. Headrest movements are restricted by the upper attachment portion 8 below the first threshold force. In accordance with the previous embodiment, the headrest may be moved to the first head supporting position above a first threshold force, not shown. The upper attachment portion 8 is preferably in connection with a restraint element for delimiting the headrest movement. The system according to this embodiment may be arranged without a lower restraint element as the recliner mechanism β may act as a threshold device to hold the lower part of the carpet in its desired position.

The second linkage 17 in fig. 3a mechanically connects the squab 5 and backrest 4. According to this embodiment the headrest is connected with a mutual connection defined by the first linkage 14 forming a force transferring line 14, 17. Alternatively the second linkage may extend from the squab or recliner mechanism to the headrest. Preferably in such a case there may be a mechanical interaction between the first linkage and the second linkage, for instance at the movable element 7 or at a restraint element. Thus, the headrest has at least a first and a second head-supporting position.

The anti-whiplash recliner mechanism 6 shown in fig. 3a has an opening 30 which receives a pivot pin 33 achieve different positions for the backrest in a rear impact situation corresponding to the second threshold force, see fig. 3b and 3c. The opening 30 may be triangular shaped. Alternatively the anti-whiplash recliner mechanism may be arranged with an L-shaped recess, a so called inverted L-shaped recess as known in the art, for achieving different positions of the backrest in a rear impact situation.

The recliner mechanism 6 may comprise a planet wheel gear 31, which in normal operation may be used by a seat occupant for adjusting the angle of the backrest 4. The carpet 7 contacts a periphery of a shaft 32 of the recliner mechanism. Alternatively the carpet or another part of second linkage 17 may contact or abut a movable part of the recliner mechanism 6 for mechanical interaction. Fig. 3b shows when the pivot pin 33 of the mechanism 6 and thereby the shaft 32 is moved in a direction rearwards due to a second threshold force applied by a seat occupant in a rear impact situation. The lower part of the carpet 7 is being angled and transfers a pulling force in a direction rearward in the carpet and the first wire 10. The head-supporting portion of the headrest 3 is moved in a direction forwards to a second head-supporting position .

Fig. 3c shows when the upper part of the backrest being in a rearward tilted position by the anti-whiplash mechanism 6. The pivot pin 33 is being moved in a direction upwards. The headrest may be less tilted forwards than in the second head supporting position. However, the opening 30 may be modified to achieve adapted movements of the backrest and/or headrest.

It should be noted that different modifications of the above-described embodiments of the invention are feasible within the scope of the invention, as it is defined by the following claims. For example different movable elements 7 may be used for transferring a movement rearwards of a seat occupant. The moveable element should transfer the force transversely the movement of the seat occupant. An example of such an element may be a movable plate mechanically linked to the headrest for different head supporting positions. Also, the system may be arranged with several restraint elements for achieving a plurality of seat positions for both the headrest and the backrest.

Claims

PATENT CLAIMS

1. A headrest system for a vehicle seat comprising a squab (5) , a backrest (4) and a headrest (3) wherein the backrest being arranged with at least a first moveable threshold device (7, 8, 9) to be activated and moved in a rearward direction by a first threshold force of a seat occupant, wherein a first mechanical connection (14) between the first device (7, 8, 9) and the headrest is adapted to move the headrest in a forward direction to a first head supporting position by a transfer of said first device movement, wherein the squab (5) and the backrest (4) comprises a second movable threshold device (6) to be activated by a second threshold force of a seat occupant to permit a movement of a lower part of the backrest in a rearward direction in relation to the squab (5) , wherein a second mechanical connection (17) between the first moveable threshold device (7, 8, 9) and the squab (5) is connected in such a way that the headrest (3) is being further moved in a forward direction to a second head supporting position in response to said movement of the lower part of the backrest (4), wherein the second threshold force exceeds the first threshold force.

2. The system according to claim 1 wherein said first and second mechanical connection (14, 17) defines a path to mechanically transfer movements of said first and second moveable threshold device to said headrest (3) .

3. The system according to claim 1 or 2, wherein said first moveable threshold device (7, 8, 9) comprises a movable element (7), such as a movable plate, a flexible element or a yieldable element which moveable element being connected to said first mechanical connection (14) .

4. The system according to any one of claims 1-3, wherein said second movable threshold device is an anti- whiplash recliner mechanism (6) .

5. The system according to any one of claims 1-4, wherein a first restraint element (8) is arranged in connection with said first mechanical connection (14) .

6. The system according to claim 5, wherein said first restraint element (8) is one of a breaking element, a spring element, a friction element or an electro magnetic element.

7. The system according to any one of claims 1-6, wherein a second restraint element (9; 6) is arranged in connection with said second mechanical connection (17) .

8. The system according to claim 7, wherein said second restraint element (9; 6) is one of a breaking element, a spring element, a friction element or an electro magnetic element.

9. The system according to any one of claims 1-8, wherein a first linkage (14) defines said first mechanical connection.

10. The system according to any one of claims 1-9, wherein a second linkage (17) defines said second mechanical connection.

11. The system according to any one of claims 1-10, wherein said headrest (3) is pivotally movable about an axis (11) for supporting a head of a seat occupant.

12. The system according to any one of claims 1-11, wherein said headrest (3) is slidingly moveable along a track for supporting a head of a seat occupant.