Spring devices – Vehicle – Leaf
Reexamination Certificate
1999-10-13
2001-08-28
Oberleitner, Robert J. (Department: 3613)
Spring devices
Vehicle
Leaf
C074S513000, C074S560000
Reexamination Certificate
active
06279883
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a bearing module for an actuating element which can be displaced counter to the force of at least one return spring, a force hysteresis produced by friction arising when the actuating element is actuated.
Modules of this kind are used, for example, with motor-vehicle accelerator pedals, the position of which is detected by an electronic sensor, the data from which are transmitted electronically to the engine control system. Here, the module produces a force hysteresis which, as the accelerator pedal is actuated, produces an actuating characteristic based on cable transmission systems, a characteristic to which car drivers are used to and which has proven itself on grounds of comfort.
The previously known modules, such as those from DE 195 17 172 A1 and from Patent Application DE 197 37 289.9, require a large number of components and are accordingly expensive to produce and assemble.
SUMMARY OF THE INVENTION
It is the object of the invention to produce a module for actuating elements which can produce the desired force hysteresis with a reduced number of components.
According to the invention, the object is achieved by virtue of the fact that force is transmitted between the return spring and the actuating element via a friction element which slides on a friction surface assigned to the free end of the return spring as the actuating element is displaced, the return spring either being tensioned by it as a function of the direction of displacement or being returnable by the restoring force of the return spring.
The solution according to the invention thus produces the desired force hysteresis directly in the return mechanism of the return spring without the need for additional supported components such as rockers, which are expensive and prone to faults. At the same time, integrating the production of friction into the return mechanism reduces the number of components necessary and leads to a module which is of simpler construction and is cheaper to produce.
In a preferred embodiment of the invention, two return springs are arranged in a redundant manner. On the one hand, doubling the number of return springs makes possible a higher restoring force, allowing the pedal resistance to be varied within a wide range. If one of the return springs breaks, it is also possible for the second to provide return properties that are still adequate and hence, although the car driver detects the breakage of one return spring from the reduced pedal resistance, he can still drive to the nearest garage without problems. Sticking of the accelerator pedal is reliably avoided.
In a further preferred embodiment of the invention, the return springs are leaf springs which are clamped at one end and the flanks of which form the friction surfaces at their free ends.
Leaf springs allow a particularly simple module design since, on the one hand, they can be clamped easily in corresponding housing apertures and, on the other hand, their smooth-surface flanks make them suitable to form direct components of the friction pair. Other spring elements, such as coil springs, are likewise conceivable in principle, but suitable friction surfaces should be provided at the free end of the spring elements.
The leaf springs are preferably curved by about 90° between their clamping locations and the friction surfaces. This makes it possible, despite the compact dimensions of the housing, to produce leaf springs which are capable of producing the desired friction forces between the flanks and the friction elements over the displacement range of the actuating element.
In another preferred embodiment of the invention, the actuating element is coupled to a rotary member with a number of lever arms which corresponds to the number of return springs and at the ends of which the friction elements are arranged.
The friction elements arranged at the ends of the lever arms consequently lead to a movement along a circular path when the actuating element is actuated, and, on the one hand, they bend open the leaf springs and simultaneously perform a sliding movement on their flank. The rotary member itself is here of simple construction and can be arranged easily on the bearing shaft of the actuating element.
The angle of rotation of the rotary member is preferably limited between two end positions by stops. This prevents the return springs from being damaged or the friction elements sliding off the friction surfaces if the rotary member is rotated by an excessive amount. In the case of an accelerator pedal, for example, a pivoting angle of about 20° is customary, the pivoting range being limited by the idling position and the full-throttle position (kick-down position if required).
It is furthermore expedient if the friction elements are mounted in an articulated manner on the ends of the lever arms. Since the ends of the lever arms of the rotary member perform a rotary motion relative to the flanks of the leaf springs when the actuating element is actuated, uniform contact is achieved in all angular positions with the friction elements resting flat against the leaf springs. The uniform contact and the resulting uniform wear of the friction elements ensures that the friction elements have a longer life overall than would be the case if the friction elements made only point or line contact with the flanks of the leaf spring.
REFERENCES:
patent: 5408899 (1995-04-01), Stewart
patent: 5529296 (1996-06-01), Kato et al.
patent: 5934152 (1999-08-01), Aschoff et el.
patent: 6003404 (1999-12-01), Hannewald
patent: 8915641 (1990-12-01), None
patent: 4300096 (1994-07-01), None
patent: 4426549 (1996-02-01), None
patent: 19517172 (1996-11-01), None
patent: 19536699 (1997-04-01), None
patent: 19737289 (1999-03-01), None
Farber Martin A.
Mannesmann VDO AG
Oberleitner Robert J.
Rodriguez Pamela M.
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