Continuously variable manual drive

192 clutches and power-stop control – Transmission and brake – Torque-responsive brake

Reexamination Certificate

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Details

C192S015000

Reexamination Certificate

active

06543598

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATION
This application claims priority of International Application No. PCT/DE99/01857, filed Jun. 23, 1999, which in turn claims priority to German patent Application No. 19831205.9, filed on Jul. 1, 1998.
FIELD OF THE INVENTION
The invention relates to continuously variable manual drives for seat adjusters and the use of such drives for longitudinal seat adjusters in motor vehicles.
BACKGROUND OF THE INVENTION
A drive is known from EP 0 549 082 A1 which describes a continuously variable linear drive for a rail guide system for motor vehicle seats having two rails connected together and displaceable longitudinally relative to each other. The rails include, between them, a hollow cavity in which an adjusting element is mounted which is connected to one of the rails. The adjusting element engages teeth connected to or provided on the other rail and running in the longitudinal direction of the rail. With the known linear drive, the drive action is motorized for which a drive motor and a corresponding control and power supply are required.
Another drive is known from WO 98/25791 A1 in which seat adjustment is carried out by using a step switch mechanism which transfers a drive force to a gear element on the output side. A locking device is mounted in the power flow between the step switch mechanism and the output-side gear element to block torque transfer on the output side and enable torque transfer however on the drive side. In addition, in one embodiment there is a transmission between the drive and output sides of the step switch mechanism through which the drive force or adjusting path can be adjusted.
A manual drive operating on both sides, for seat adjusters in motor vehicles using a step-switch mechanism, is furthermore known from DE 195 27 912 A1 in which a drive lever is mounted on a drive axis and supports swivel locking elements whose free ends, which are provided with toothed elements, can be brought into engagement with teeth provided on the circumference of a drive wheel for the purpose of transferring force.
From DE 41 20 617 C2 a connection is known between a drive and an output having a locking coupling in which torque on the drive side is transferred in both directions of rotation to an output element while torque on the output side is blocked in both rotary directions by the locking coupling and is consequently not transferred to the drive element.
The known step switch mechanisms are used in particular in the motor vehicle field for devices for adjusting the height or incline of a seat. For this purpose they are set up to transfer a large force over a short path to an adjusting gear, such as is required in particular for moving a seat upwards on which the user of the vehicle seat is actually located.
SUMMARY
The invention is concerned with the problem of providing a drive for longitudinal seat adjusters which enables a continuously variable adjustment of a vehicle seat, thereby always ensuring a crash-safe connection between the two rail devices of the vehicle seat and which is characterized by a simple cost-effective construction and a maximum individual flexibility for adjusting the seat on. In addition, a continuously variable manual drive for seat adjusters is to be provided which can be used universally and which enables a drive movement to be converted into an adjustment movement adapted to the events on the seat and in dependence on the requirements of any adjustment to be carried out.
These problems are solved according to the current invention. Advantageous and preferred developments of the inventions are given below.
A drive according to one embodiment of the invention is characterized in that the drive has a manual step switch mechanism which can be driven through a drive lever. In addition, a locking device is provided which blocks torque transfer on the output side but allows torque transfer on the drive side, and a transmission step is also provided which is coupled to the step switch mechanism on the drive side or on the output side.
With the drive according to the invention having a step switch mechanism for a longitudinal seat adjustment, the transmission ratio of the transmission step is selected so that the speed of the output element is faster than the speed of the drive shaft so that even with a drive lever, which can be operated on both sides as was hitherto used only for adjusting seat heights and inclines, an effective longitudinal adjustment of the seat can now be carried out.
Since the output-side gear element is always in engagement with the one rail device and is moved by manually operating the drive lever continuously in the one or other direction along the rail device, the solution produces a continuously variable drive which allows a precise adjustment of the longitudinal position of the seat even if it involves only small adjustment paths.
A further advantage of the drive according to the invention for the longitudinal seat adjustment lies in the fact that even during an adjustment process there is a high degree of security in the event of a crash since the gear element on the output side is always in engagement with the one rail mechanism and a displacement of the seat as a result of external forces is reliably prevented through the brake device. Using an active manually operable step switch mechanism instead of a motorized adjustment provides an additional simple and cost-effective solution.
Rail friction and rail pitch angles are insignificant in the case of an active longitudinal adjustment and do not prevent a precise length adjustment. This makes it possible, when necessary, to make the pitch angle of the rails so big that a separate seat adjustment can be eliminated. Thus longitudinal and height adjustment are coupled through the pitch angle of the seat rails.
The transmission step proposed according to the invention can be provided at several points of the drive. In a first preferred embodiment the transmission step is formed between a drive lever and the step switch mechanism. By way of example, force is transferred from the drive lever to the step switch mechanism through a toothed segment which is mounted on the rotary axis of the drive lever and engages in a positive locking element, more particularly a pinion, mounted on the drive axis of the step switch mechanism.
The drive axis of the step switch mechanism and the rotary axis of the drive lever thereby run parallel.
In another preferred embodiment, the transmission step is formed between the step switch mechanism and the locking device. For this embodiment, a transmission element is again preferred which is coupled both to the step switch mechanism and to the brake device and which engages, in particular, in a positive locking element mounted on the axis of the brake device. The transmission element is thereby preferably formed by the external teeth of a drive wheel normally provided in the case of a step switch mechanism.
In another embodiment the transmission step is formed between the locking device and the gear element on the output side. Force is transferred from the locking device to the gear element on the output side by means of a transmission element which is coupled on one side to the locking device and on the other to the gear element on the output side. The transmission element is preferably formed as a pinion which is mounted on the drive axis of the step switch mechanism and meshes with the gear element on the output side. The axes of the transmission element and the gear element on the output side thereby run parallel.
The locking device is any device which has the capacity to block forces which are introduced on the output side. A locking device of this kind is, in a preferred embodiment, a brake device as known from DE 41 20 617 AI.
However, the locking device according to the invention may also be a self-blocking gear which blocks forces introduced on the output side. A self-blocking gear of this kind is, for example, a tumbler gear which is known to one skilled in the art.
The step switch mechanism may be any d

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