Expansible chamber devices – With inspection window in expansible chamber wall portion – With lock
Reexamination Certificate
1999-06-04
2001-06-26
Ryznic, John E. (Department: 3745)
Expansible chamber devices
With inspection window in expansible chamber wall portion
With lock
Reexamination Certificate
active
06250203
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an operating device for motor vehicles.
2. Discussion of the Prior Art
Friction clutches are subjected to constant wear which makes it necessary to replace the clutch disks at the right time, it generally being desirable to render the wear visible without dismantling the entire clutch. Lever-operated clutches, in which the lever is mechanically joined to the coupling disk, permit direct measurement of the wear at the lever. In the case of actuating a clutch via a hydraulic cylinder, it is no longer the lever position for clutch operation but the position of the hydraulic piston which is a measure of the rate of wear on the clutch disk.
A device is described in German reference DE 41 20 643 A1 which displays the wear by means of an electric contact on the hydraulic cylinder, and thus displays the position of the hydraulic piston. The display is installed in the form of a warning lamp which informs the user of the motor vehicle about the state of the clutch.
SUMMARY OF THE INVENTION
The present invention proposes, by contrast, not only to install an end position for displaying a limiting value, but also to track the piston position at the start and at the end of the operation and to evaluate this via an electronic system. Moreover, it is proposed in addition to provide a plurality of intermediate positions in the hydraulic cylinder through which the hydraulic piston passes with a contact element, and to connect the contact element to a switch. The switches are connected to a switch unit which picks up the pulses of the switches and relays then to a display via an electronic computer. Such an integrated positional interrogation makes it possible to provide information not only on the state of the clutch but also on the correct functioning of the hydraulic system. In particular, the initial position of the hydraulic piston and the end position thereof are particularly desirable parameters. It is possible for an intermediate position of the hydraulic piston in the cylinder to provide information, depending on the position of said piston with reference to the piston travel, on the function features occurring during operation of the vehicle clutch.
The object of the invention which emerges from the possibilities outlined is to integrate into an input and/or output cylinder positional interrogation for a piston with regard to its two end positions, it being desirable if the position can additionally be interrogated at at least one position between the two end positions.
Pursuant to this object, and others which will become apparent hereafter, one aspect of the present invention resides in an operating device having a housing, a cylinder arranged in the housing, a piston arranged in the cylinder so as to be movable back and forth between a rest dead point and an operating dead point, and switch means for outputting signals which indicate a position of the piston and the cylinder, the switch means including at least one switch.
In another embodiment of the invention the switch is arranged in either the housing or a guide sleeve which is arranged in the housing for the purpose of guiding the piston.
In still another embodiment of the invention the switch means includes a plurality of switches and contact elements arranged so that the switches and contact elements relay signals to a switch unit for detecting different positions of the piston.
Electronic computer means are provided in yet another embodiment of the invention for conditioning signals relayed to the switch unit by the switches and for passing the signals to a display.
The plurality of drawings and sketches illustrates the proposed integrated positional interrogation for the piston in an input and/or output cylinder.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
REFERENCES:
patent: 4140045 (1979-02-01), Hardwick et al.
patent: 4742794 (1988-05-01), agstrom
patent: 5031504 (1991-07-01), Gratzmuller
patent: 5299489 (1994-04-01), Obrecht et al.
patent: 5758758 (1998-06-01), Friedrich
patent: 5899225 (1999-05-01), Yokogi
patent: 1601763 (1970-03-01), None
patent: 41 20 643 (1992-12-01), None
Herbst Rudiger
Mischler Manfred
Cohen, Pontani, Liebermann & Pavane
Mannesmann Sachs AG
Ryznic John E.
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