192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
2002-02-21
2004-04-13
Rodriguez, Saul (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C192S090000, C192S098000, C192S115000, C092S128000, C092S161000, C092S169100
Reexamination Certificate
active
06719115
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to improvements in hydraulic operating arrangements, particularly to operating arrangements for clutches in the power trains of motor vehicles. More particularly, the present invention relates to improvements in hydraulic operating arrangements which can be utilized with advantage in or in combination with so-called master and slave cylinders to actuate friction clutches between the prime movers (such as internal combustion engines) and the change-speed transmissions in the power trains of motor vehicles.
Published German patent application No. 197 42 468 discloses a clutch operating arrangement wherein the housing or casing of the slave cylinder consists, at least in part, of a plastic material. Such slave cylinders are known as central clutch release devices and their casings are normally affixed to the transmission housing or case by threaded fasteners. At least a part of the casing of the slave cylinder is mounted in such a way that it surrounds the input shaft of the change-speed transmission. Securing of the casing of the slave cylinder to the transmission case by threaded fasteners during assembly of the power train is time consuming and hence expensive.
Presently known seals, such as lip seals, which serve to seal the internal chamber of the casing of the slave cylinder from the atmosphere when such chamber is to receive hydraulic fluid from the master cylinder are normally mounted on the reciprocable piston in the slave cylinder of a brake actuator. Such seals share the axial movements of the piston and are called upon to move along inner and outer sealing surfaces which are respectively provided on a metallic and on a plastic material. The sealing surface which is provided on a plastic material normally offers a greater frictional resistance to axial movements of the piston and is likely to generate noise while guiding a piston during actuation (such as disengagement) of the friction clutch.
It is also known to provide the slave cylinder in the hydraulic clutch actuating system of the power train in a motor vehicle with an internal sleeve which serves to guide the piston of the slave cylinder and is made of steel or an equivalent material. A drawback of such slave cylinders is that adequate sealing of the contact surface(s) between the guide sleeve of steel and the plastic casing of the slave cylinder can create serious problems. In order to avoid such problems (including high cost or an unsatisfactory seal), the casings or cylinders of many presently known slave cylinders do not employ separately produced guide sleeves for the piston, i.e., the guide sleeve is part of the plastic casing. A drawback of such proposals is that the making of a slave cylinder casing without a separately produced guide sleeve for the piston but with an adequate guide surface for the piston (i.e., with a guide surface provided on a part made of a plastic material) cannot be made at a reasonable cost in available machines, e.g., in standard injection molding machines for the making of articles from plastic material. As a rule, an injection molding machine which is to turn out such plastic slave cylinder casings must be equipped with highly complex parts such as shifting or pushing arrangements and the like.
OBJECTS OF THE INVENTION
An object of the present invention is to provide a slave cylinder, especially a slave cylinder which can be used as a friction clutch release unit in the power train of a motor vehicle, which does not exhibit the aforediscussed drawbacks of conventional slave cylinders and which exhibits numerous important advantages over such conventional parts or groups of parts.
Another object of our invention is to provide a slave cylinder which can be turned out in large numbers in conventional injection molding and other available machines.
A further object of the invention is to provide a slave cylinder which can be integrated into existing types of power trains without any or without appreciable modifications of such power trains.
An additional object of the invention is to provide a slave cylinder which can be installed within the clutch bell under the hood of a motor vehicle.
An additional object of the invention is to provide a slave cylinder which requires a minimum of maintenance, no inspection or infrequent inspection, and whose useful life is longer than that of presently known slave cylinders for use as a means for actuating friction clutches in the power trains of motor vehicles.
Still another object of the instant invention is to provide a hydraulic clutch actuating system the condition and mode of operation of which can be expected to remain unchanged during the useful life of the motor vehicle.
A further object of the invention is to provide a slave cylinder which can be readily sealed where necessary, wherein the casing is in optimal frictional engagement with the piston, which is not subject to excessive wear, the material of which is not likely to exhibit pronounced fatigue after relatively short periods of use, and which can be made of a wide variety of readily available materials.
Another object of the invention is to provide a hydraulic operating arrangement which employs the above outlined slave cylinder.
A further object of the present invention is to provide novel and improved adapter means for use in the connection between a master cylinder and a slave cylinder in the power train of a motor vehicle.
An additional object of the invention is to provide novel and improved methods of making various component parts of the means for actuating the friction clutch in the power train of a motor vehicle.
Still another object of the invention is to provide novel and improved materials and/or combinations of materials for the making of casings which are to form part of slave cylinders in the power trains of motor vehicles.
A further object of the invention is to provide novel and improved means for ventilating the chambers of cylinders or casings forming part of slave cylinders.
SUMMARY OF THE INVENTION
One feature of the present invention resides in the provision of a system for altering the bias of a clutch spring (such as a diaphragm spring) in and for thus changing the condition of an engageable and disengageable friction clutch between a rotary output element (such as a crankshaft or a camshaft) of a prime mover (such as an internal combustion engine) and a rotary input element of a change-speed transmission preferably having a composite housing or case and being disposed in the power train of a motor vehicle. The improved system includes a primary unit (such as a master cylinder) having an output, means (such as a clutch pedal or an electronic actuator) for actuating the primary unit to thus transmit a pulse by way of the output of the primary unit, a clutch release device having an at least partially plastic composite casing and a mobile bearing coaxial with the input element of the transmission and arranged to alter the bias of the clutch spring in response to movement axially of the input element, means for operatively connecting the output of the primary unit with the clutch release device to move the bearing axially of the input element in response to actuation of the primary unit to transmit a pulse by way of the output, and means for coupling the clutch release device to a component of the transmission housing which is preferably located opposite the bearing.
The means for actuating the primary unit (such as the aforementioned master cylinder) can comprise a driver-operated pedal (clutch pedal) in the motor vehicle.
The coupling means which connects the clutch release device with a component of the transmission housing can include a self-locking arrangement.
The aforementioned master cylinder can constitute a first hydraulic cylinder and piston unit of the improved system, and the aforementioned output can constitute an outlet of the cylinder of the first unit. The casing of the clutch release device can include or constitute the cylinder of a second hydraulic cylinder and piston unit having a mobil
Abraham Uwe
Adler Dieter
Almeida Ernani
Fugel Wolfgang
Giese Peter
Darby & Darby
LuK Lamellen und Kupplungsbau Beteiligungs KG
Rodriguez Saul
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