EP1578638A1

EP1578638A1 - Active headrest for a vehicle seat

Info

Publication number: EP1578638A1
Application number: EP03775241A
Authority: EP
Inventors: Dante Libanore
Original assignee: Compas Srl
Current assignee: Compas Srl
Priority date: 2002-10-29
Filing date: 2003-10-28
Publication date: 2005-09-28
Also published as: WO2004039626A1; AU2003283309A1; ITTO20020190U1

Abstract

The control device comprises a support structure (18) adapted to be mounted on top of the backrest of a vehicle seat and a quadrilateral linkage (15, 16) interposed between the support structure (18) and a headrest body (11) and operable by a. pyrotechnic actuator (17) for moving the body (11), in the event of a collision, from a rest position to an active position advanced and/or raised towards the head of the occupant of the seat. The support structure (18), the linkage (15, 16) and the actuator (17) are arranged so as to be received inside the headrest body (11). The control device further comprises a plate-like attachment member (19) connected to the linkage (15, 16) and provided with fastening means (29, 31) for connection to the headrest body (11), whereby that the body (11) can be connected to the linkage (15, 16) by means of the attachment member (19). The support structure (18), the linkage (15, 16) and the platelike attachment member (19) are manufactured by plastics moulding (10). The support structure (18) is formed as a single shaped body (18), having a central portion (18a) to which the swivelling levers (15, 16) and the actuator (17) are articulated and a pair of side portions (18b) intended to be mounted on a pair of mounting bars (14) which can be inserted into respective holes in the seat backrest.

Description

Active headrest for a vehicle seat

The present invention relates to an active headrest for a vehicle seat, and more particularly to a control device for a headrest of this type.

In order to limit, in the event of a collision of the vehicle, in particular in the event of a rear-end collision, injuries to the cervical region of the vertebral column of the occupants produced by the so-called whiplash effect, that is to say, the effect of the abrupt backward movement of the head relative to the trunk owing to the inertial effects, it is known the use of active headrests which can move forwards and/or upwards relative to the backrest of the seat in order to occupy the gap normally existing between the head of the occupant and the front abutment surface of the headrest, so as to oppose the backward movement of the head.

An active headrest for a vehicle seat of the above- identified type is known from the non-published international patent application PCT/IT02/00531 in the name of the present applicant. According to this known arrangement, the headrest comprises a frame structure adapted to be mounted on top of the backrest of the vehicle seat, a body supported by the frame structure and having a front surface for supporting the head of the occupant of the seat, and a control device arranged to move the headrest body, in the event of a collision of the vehicle, from a rest position to an active position which is advanced and/or raised towards the head of the occupant of the seat . This control device includes a linkage operable by a pyrotechnic actuator and is entirely received inside the headrest body, whereby the headrest forms an absolutely separate component from the seat . Accordingly, the headrest can be manufactured independently of the seat and then mounted thereon.

The above-cited patent application describes a first preferred embodiment in which the linkage of the control device comprises a pair of swivelling levers, articulated at a first end thereof to the frame structure of the headrest and at the opposite end to respective support members attached to an inner side of the shell of the headrest body, in such a manner as to form a quadrilateral linkage mechanism. The frame structure which supports to rotation both the swivelling levers and the pyrotechnic actuator of the control device is formed by a set of metal tubular elements suitably bent and connected to each other.

It is the object of the present invention to provide an improved control device for an active headrest of the type discussed above, which enables to reduce the costs of manufacture and to ease the installation, servicing and replacement operations on the headrest, and which has a lighter and more compact structure.

This object is fully achieved according to the invention by virtue of a control device for an active headrest for a vehicle seat having the characteristics defined in Claim 1.

Further advantageous characteristics of the invention are defined in the dependent claims.

The characteristics and advantages of the invention will appear from the detailed description which follows, given purely by way of non-limiting example with reference to the appended drawings, in which: Figure 1 is a perspective view of a control device for an active headrest of a vehicle seat according to a first embodiment of the invention;

Figure 2 is a side elevation view of the control device of Figure 1;

Figure 3 is another perspective view of the control device of Figure 1;

Figure 4 is a further perspective view of the control device of Figure 1, in which the plate for attachment of the inner shell of the headrest body has been removed;

Figure 5 is a back elevation view of the active headrest of Figure 1, in which there is shown in particular the arrangement for fastening the inner shell of the headrest body to the attachment plate of the control device; and

Figure 6 is a perspective view of a control device according to a further embodiment of the present invention.

In the description and claims which follow, terms such as "longitudinal" and "transverse", "front" and "rear", "lower" and "upper" are to be understood as referred to the mounted condition on the vehicle.

Referring first to Figures 1 to 5, which relate to a first preferred embodiment of the invention, an active headrest 10 for a vehicle seat basically includes :

a body 11 adapted to be moved, in the event of a collision, from a rest position, in which it provides a surface for supporting the head of the occupant of the seat, to an active position which is advanced and/or raised with respect to the rest positio ;

a control device, generally indicated 13, for moving the body 11 from the rest position to the active position; and

a pair of vertical bars 14 intended to be inserted into corresponding holes provided in the upper part of the seat backrest (not illustrated) , on which bars the control device 13 is mounted.

The body 11 of the headrest is a hollow member having a generally bell-like shape which is open downwards. The body basically consists of an inner shell 12 covered by a padding of a soft material . The shell 12 comprises a front wall 12a intended to provide a surface for supporting the head of the occupant of the seat, a rear wall 12b intended to be connected with the control device of the headrest, and a bent upper portion 12c which connects the two front and rear walls, closing the shell 12 from above.

The control device 13 of the headrest comprises:

a pair of lower swivelling levers 15 and an upper swivelling lever 16 (Figure 4) which define a quadrilateral linkage mechanism for moving the body 11 of the headrest forwards and upwards from the rest position (in which position the control is illustrated in all the figures) to the active positio ;

an actuator 17 (Figure 4) , preferably a pyrotechnic actuator, for setting to rotation the quadrilateral linkage in order to move the body 11 to the active position in a very short time (advantageously less than 20 ms, whereby the operation of the headrest anticipates the inertial effects produced by the collision of the head of the occupant of the seat) ;

a support member 18 which is mounted on the pair of mounting bars 14 and to which the front ends of the swivelling levers 15, 16 and the lower end of the pyrotechnic actuator 17 are articulated; and

an attachment plate 19 which is articulated to the rear ends of the swivelling levers 15, 16 and to which the rear wall 12b of the inner shell 12 of the headrest body is fastened.

The two lower swivelling levers 15 of the quadrilateral linkage are articulated at their front ends to the support member 18 by means of respective articulation pins 20 (Figure 1 and 2) which define a fixed axis of rotation orientated in a transverse horizontal direction, and at their rear ends to the attachment plate 19 by means of respective articulation pins 21 which engage respective lower projections 22 of the plate 19 (Figure 4) . The upper swivelling lever 16 of the quadrilateral linkage is articulated at its front end to the support member 18 by means of an articulation pin 23 which defines a fixed axis of rotation parallel to that of the articulation pins 20, and at its rear end to the attachment plate 19 by means of an articulation pin 24 which engages an upper projection 25' of the plate 19 (Figures 1 and 4) . The upper lever 16 also forms an intermediate portion 16a which projects downwards and engages a pin 26 (Figure 3 and 4) for articulation of the upper end of the actuator 17.

Preferably, the swivelling levers 15, 16 are manufactured by plastics moulding so as to reduce the overall weight of the headrest and the inertia of the control device, thereby enabling to speed up the response of the headrest upon actuation.

The pyrotechnic actuator 17 is of per-se-known type and therefore will not be illustrated in detail in the present description. It suffices to note, referring to Figure 4, that the cylinder of the actuator is secured at its bottom onto a base portion 27 supported to rotation by the support member 18 by means of a pair of articulation pins 28 which define an axis of rotation parallel to those of the swivelling levers 15, 16. At its top, the actuator 17 is articulated with its rod (not visible in the figures) to the downward-projecting portion 16a of the upper swivelling lever 16, as already explained above.

Thus, when the pyrotechnic charge contained in the actuator 17 is caused to burst, the rod of the actuator is pushed out of the cylinder and, acting upon the upper lever 16 through the articulation pin 26, sets to anticlockwise rotation the quadrilateral linkage, thereby moving the headrest body 11 forwards and upwards from the rest position to the active position specified above.

Preferably, the burst of the pyrotechnic charge contained in the actuator 17 is primed by a control signal provided by an electronic control unit (per se known and not illustrated) which receives the information coming from at least one crash sensor (also not illustrated) , such as for example a longitudinal accelerometer, and evaluates the direction and intensity of the collision in order to determine whether the headrest must be actuated or not.

As is apparent in the light of the previous description, the support member 18 serves to provide the points of articulation of the levers 15, 16 of the quadrilateral linkage and of the cylinder of the pyrotechnic actuator 17. In order to simplify the structure of the control device and reduce the overall weight of the headrest, according to the invention the support member 18 is advantageously formed as a single shaped body, which is manufactured by plastics moulding. This shaped body forms a central portion 18a on which the above-listed components are articulated, and a pair of side portions 18b provided with seats for installation of the body 18 at the top of the mounting bars 14.

Also the attachment plate 19 is advantageously manufactured by plastics moulding. The plate 19 comprises (Figure 3 and 5) a central portion 19a forming on its front side the upper projection 25 to which the swivelling lever 16 is articulated, and a pair of side portions 19b preferably integral with the central portion 19a and forming on their front faces the lower projections 22 to which the swivelling levers 15 are articulated. In order to enable the inner shell 12 of the headrest to be fastened to the plate 19, each side portion 19b of the plate forms on its rear side a seat 29 for releasably restraining a corresponding engagement member 30 formed by the rear wall 12b of the shell 12.

With reference in particular to Figure 5, the seats 29 are formed as vertical guides into which the engagement member 30 of the shell 12 is inserted from above sliding downwards. Moreover, the seats 29 are each provided with a plurality of pairs of elastic latching devices 31 (also, preferably integral with the plate 19) adapted to lock the respective engagement member 30 against the bottom of the guides 29. In the illustrated example of construction, each engagement member 30 is formed integrally with the shell 12 as a vertical channel-like element which projects from the rear wall 12b of the shell towards the centre of the headrest body. Each engagement member forms also a pair of vertical openings 32 adjacent to its side edges, into which openings the latching devices 31 associated to the guides 29 can be inserted.

The provision of an attachment plate interposed between the swivelling levers and the shell of the headrest offers the advantage of enabling the same control device to be used together with different bodies of different and the headrest body to be disassembled (by means of an appropriate tool, not illustrated) from the device, even after the headrest has been installed of the vehicle seat, in order to allow the inspection of the mechanism and the replacement of the pyrotechnic charge after the operation of the system.

By virtue of its extreme compactness, the control device can be installed also inside headrest bodies of small size, such as those normally used in motor vehicles of medium and low category. Moreover, by virtue of its reduced weight, the device fully meets the current actual requirements of the automotive industry for a reduction in the weight of the components installed on board of the vehicles.

A second embodiment of an active headrest according to the present invention is illustrated in Figure 6, where parts and elements identical or similar to those of the previous figures have been given the same reference numerals. This variant of construction differs from the first embodiment purely in that the support member 18 is articulated, instead of securely fixed, to the mounting bars 14, by means of a pair of articulation pins 33 which define a transverse, horizontal axis of rotation, in order to enable the adjustment also of the inclination of the headrest, beyond the adjustment of the height which is normally provided for. Naturally, the principle of the invention remaining unchanged, embodiments and manufacturing details may vary widely from those described and illustrated purely by way of non-limiting example.

In particular, even though the present invention has been illustrated with reference to a preferred embodiment thereof which provides for a specific arrangement of the driving mechanism (that is, of the linkage and of the associated actuator) , other embodiments differing from that illustrated only as to the arrangement of the driving mechanism are to be considered as equivalent embodiments. For instance, the two lower swivelling levers 15 may be replaced by one swivelling lever only, as well as the upper swivelling lever 16 may be replaced by a pair of levers both connected to the rod of the pyrotechnic actuator. Moreover, the actuator 17 may be of any suitable type, not necessarily a pyrotechnic actuator.

Claims

1. A control device for an active headrest (10) of a vehicle seat, intended to move, in the event of a collision, a body (11) of the headrest (10) from a rest position to an active position advanced and/or raised towards the head of the occupant of the seat; the device comprising a support structure (18) adapted to be installed on top of the seat backrest and a quadrilateral linkage (15, 16) interposed between the support structure (18) and the headrest body

(11) and operable by an actuator (17) for moving the body (11) to the said active position; the support structure (18) , the linkage (15, 16) and the actuator (17) being arranged so as to be received inside the headrest body (11) ; characterised in that it further comprises an attachment member (19) separate from the linkage (15, 16) and the headrest body (11) , which member is connected to the linkage and is provided with fastening means (29, 31) for connection to the headrest body.

2. Control device according to Claim 1, characterised in that the attachment member (19) is a plate element.

3. Control device according to Claim 1 or 2, characterised in that the said fastening means (29, 31) of the attachment member (19) are releasable fastening means.

4. Control device according to Claim 3 , characterised in that the said fastening means (29, 31) comprise a pair of seats (29) which define vertical guides parallel to each other, into which respective engagement members (30) provided on a wall (12b) of an inner shell (12) of the headrest body (11) can be inserted, each of the said seats

(29) being also provided with elastic latching means (31) for locking the respective engagement member (30) of the headrest body (11) against the bottom of the seats (29) .

5. Control device according to Claim 4, characterised in that the seats (29) and the latching means (31) are formed integrally with the plate (19) .

6. Control device according to Claim 1 or 2 , characterised in that the linkage (15, 16) comprises at least one lower lever (15) and at least one upper lever (16) , which are articulated at a first end to the support structure (18) for rotation (20, 23) about respective transverse, horizontal axes of rotation parallel to each other and are articulated (21, 24) at a second end to the attachment member (19) .

7. Control device according to Claim 6, characterised in that the linkage (15, 16) comprises a pair of lower levers (15) and an upper lever (16) .

8. Control device according to Claim 6 or 7, characterised in that the at least one upper lever (16) is connected to a movable 'rod of the actuator (17).

9. Control device according to Claim 1, characterised in that the actuator (17) is articulated to the support structure (18) .

10. Control device according to Claim 1, characterised in that the support structure (18) is formed as a single shaped body (18) .

11. Control device according to Claims 6, 9 and 10, characterised in that the support body (18) forms a central portion (18a) to which the swivelling levers (15, 16) and the actuator (17) are articulated and a pair of side portions (18b) intended to be mounted on a pair of mounting bars (14) which can be inserted into respective holes in the seat backrest.

12. Control device according to any of the preceding claims, characterised in that the support structure (18) , the linkage (15, 16) and the attachment member (19) are manufactured by plastics moulding.

13. Active headrest (10) for a vehicle seat, characterised in that it comprises a control device according to any of Claims 1 to 12.