192 clutches and power-stop control – Transmission and brake – Torque-responsive brake
Reexamination Certificate
1999-10-12
2001-05-15
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Transmission and brake
Torque-responsive brake
C192S015000, C192S019000
Reexamination Certificate
active
06230867
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a seat adjuster, for example, for adjusting the height of a seat or the tilting of the backrest of the seat in a motor vehicle.
Known are seat adjusters with a locking mechanism through which the adjustable part of the seat can be tightly locked onto a stationary part. If the user desires to adjust the seating position, the locking mechanism has to, first, be unlocked before the adjustable part of the seat can be adjusted either through direct bodily influence on the adjustable part or, however, with the aid of an adjusting device such as a hand wheel or lever or the like. When the desired new position is reached, the locking mechanism is allowed to reengage in this position.
Seat adjusters of this type, however, have the disadvantage that only a stepwise adjustment, according to measure of the discrete engagement positions of the locking mechanism, is possible. Besides this, convenience of operation is impaired because the locking mechanism is difficult to release especially while under a load and can easily get stuck or jammed during re-engagement in the new position and/or abruptly falls into the engagement position accompanied by an unpleasant noise. Further, such a locking mechanism is difficult to combine with a drive which increases the operational force exerted by hand onto the adjusting device.
On the other hand, known are seat adjusters which, instead of a locking mechanism, have brake acting between the adjustable part and the stationary part with which the adjustable part can be steplessly blocked at selected positions in both directions. To release the brake, a releasing device which is coupled to the adjusting device is provided such that the brake is released automatically when the adjusting device is operated and the force is transferred from the adjusting device to the adjustable part, while, if the adjusting device is not operated and there is a flow of force in the opposite direction, the brake is automatically blocked.
Seat adjusters of this type make possible a stepless adjustment of the seat and are excellent in operational convenience since the release of the brake during operation of the adjusting device as well as the gripping of the brake after reaching the desired position of engagement occur automatically and in a manner hardly noticeable by the user.
In seat adjusters of this latter type, a load acting in the same direction over a longer period of time can lead to a crawling of the brake and thus to a gradual, undesirable adjustment of the seat, especially when, in addition to the continuously acting force, there is a vibration such as is regularly the case in motor vehicles during driving. For example, in seat height adjusters, there is often a strong spring which places an upward pressure on the seat and thus partially balances out the body weight of the user, such that the force required for an adjustment process is reduced. If the seat is occupied, the downwardly acting force of the weight outweigh, such that the seat gradually slopes downward due to the crawling effect of the brake. If the seat has no load, however, the upwardly directed force of the spring outweighs, such that the seat moves gradually upward. In both cases, from time to time, a readjustment of the seating position is needed.
It is an object of the invention to provide a stepless seat adjuster in which the seat remains reliably in the set position even under a load.
SUMMARY OF THE INVENTION
This problem is solved in a seat adjuster according to the invention by means of an additional locking mechanism which automatically engages when the adjusting device is not in operation and disengages when the adjusting device is in operation.
Since the seat is kept in the set position primarily through the braking force of the brake, the additional locking mechanism has to absorb only apart of the acting forces. It can therefore be very small, easy to operate and for short lifting motion such that the engagement and disengagement of the additional locking mechanism is hardly noticeable for the user and thus does not impair convenience of use. Nevertheless, the crawling effect of the brake under a load can be effectively subdued, so that the seat remains reliably in the set position.
In seats of motor vehicles, in which the belt lock for the safety belt is mounted directly at the seat, the additional locking mechanism according to the invention contributes additionally to the increase in accident safety. Thus, in such a seat, the seat height adjuster must be capable, at impact, of absorbing the forces of inertia transferred through the safety belt, so that the seat does not give in. One part of these forces is absorbed, according to the invention, by the additional locking mechanism, so that the brake is less burdened by the load at impact.
The adjustable part can refer to the seat in its entirety or to a part of the seat, for example, the backrest; it can, however, also refer to a gear element of a gear reduction mechanism via which the adjusting device effects the seat adjustment.
Advantageous embodiments of the invention result from the sub-claims.
The additional locking mechanism can be in effect between the stationary part and the adjustable part. In this case, provided are a multitude of notches, either on the stationary part or on the adjustable part, into which a suitable locking mechanism grips as is generally the case in mechanical locking arrangements such as arm locks, ratchet couplings or the like. Since the additional locking mechanism needs to have only a relatively small holding power, the notches can be formed at very small intervals, so that a very large number of notched positions can be realized. After an adjustment process, the adjustable part is held in position, at first, merely through the brake, and it is not necessary that the additional locking mechanism engages immediately after that. Only when the adjustable part changes its position somewhat based on the crawling effect of the brake does the additional locking mechanism engage very slowly and in a manner hardly noticeable by the user; and the adjustable part is finally locked in the position reached.
Seat adjusters without gear mechanisms often have, as an adjusting device, a lever with a telescope-like extendable handle. Prior to the operation of the adjusting device, the handle is extended to elongate the lever arm. In this case, for the release of the additional locking mechanism, also the relative movement between the extendable handle and the rest of the part of the lever can be used.
The brake of the seat adjuster can also, for example, be a coiled spring brake or a freewheeling brake. In these cases, the releasing device serves, at the same time, as a drive element with which the operational force of t
4
e adjusting device is transferred to the adjustable part. Since, in such brakes, the releasing element is mechanical coupled to the adjustable part, a crawling or running of the brake inevitably also leads to a movement of the releasing element. In seat adjusters with such a brake it is therefore also possible to allow the additional locking mechanism to be in effect between the stationary part and the releasing element in order to eliminate the crawling of the brake.
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Bonck Rodney H.
Burns Doane , Swecker, Mathis LLP
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