Chairs and seats – Headrest – Adjustable rectilinearly vertically
Patent
1999-04-09
2000-10-03
Barfield, Anthony D.
Chairs and seats
Headrest
Adjustable rectilinearly vertically
29721612, 24829731, A47C 1036
Patent
active
061262382
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a head rest for a vehicle seat, which head rest is fixed on supporting rods, at least one of the supporting rods being configured as a clamping element which cooperates with a locking element arranged in a fixed reception for the supporting rod in a back rest of the vehicle seat.
STATE OF THE ART
In a locking device for vertically adjustable head rests known from DE 33 01 073 C2, the supporting rails which are slidably guided in a guide sleeve comprise at least in their end region, a catch recess into which a deformable leg spring engages. In this way, the head rest along with the supporting rods is intended to be prevented from being pulled fully out of the back rest of the vehicle seat.
In other known devices for the height adjustment of head rests of vehicle seats, the supporting rods comprise uniformly spaced catch recesses into which a spring-loaded catch engages. An adjustment of the head rest therefore requires a force large enough to undo the locking of the head rest. The occupants are thus able to adjust the position of the back rests to suit their individual statures. Unfortunately, such adjusting devices do not offer adequate safety in the case of an accident. During an accident involving a rear-end collision of the vehicle, the head of the occupant is hurled backwards towards the head rest. In such a situation, especially if the head rest is adjusted at a too low position, there is the danger that the head rest which is anchored in the vehicle seat be pushed in and thus cause an overstretching of the cervical spine, that is to say, a trauma. In more modern automobiles, it is, in particular, a forward movement of the head of a vehicle occupant that is stopped and cushioned by air bags, but no equally suitable safety device has been developed thus far for a backward movement of the head of a vehicle occupant.
The other document, U.S. Pat. No. 4,411,470 A, cited in the International Preliminary Examination Report discloses a locking device in which the head rest is held in place by frictional engagement means. These frictional engagement means consist, among other things, as shown in FIGS. 9, 10a and 10b, of a compression spring radially surrounding the supporting rod concerned which is biased radially inwards by an inclined surface during locking. This is meant to hold the supporting rod in the respective position by frictional engagement. On the one hand, such a head rest locking arrangement does not offer adequate protection during an accident against the inward movement of the supporting rods described above, and on the other hand, this type of locking is also extremely uncomfortable because, depending on the position of the head rest, not enough space is available for a manual turning of the element used for clamping.
THE INVENTION
The object of the invention is to obviate the aforesaid problems and thus create an individually adjustable head rest which is reliably prevented from being pushed into the back rest of the vehicle seat during an accident.
This object is achieved with the characterizing features of claim 1 according to which the locking element is configured as an overrunning clutch acting in a linear direction of movement which, in a locked position, prevents the supporting rod from being pushed into the reception and which can be unlocked by an actuating element. Consequently, in an unlocked position of the locking element, the head rest can be individually adjusted without any problem to the height of the driver or of the passenger. In the locked position of the locking element, however, the head rest is locked in such a manner that it cannot be displaced towards the back rest even during an accident.
According to a further proposition of the invention, a displacement barrier for the clamping element extending through a switching ring and a clamping body support is created by a suitable configuration of the clamping body support and the switching ring, with spring-loaded clamping bodies arranged therebetween. By a controlled turning of the switching
REFERENCES:
patent: 4411470 (1983-10-01), Nishimura et al.
patent: 4568123 (1986-02-01), Yasui et al.
patent: 4577904 (1986-03-01), Wiese et al.
Barfield Anthony D.
Ina Walzlager Schaeffler OHG
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