Hydraulic coupling for vehicle drivetrain

Details Hydraulic coupling for vehicle drivetrain Hydraulic coupling for vehicle drivetrain

1999-12-16

2001-05-29

Marmor, Charles A. (Department: 3681)

Planetary gear transmission systems or components

Fluid drive or control of planetary gearing

Control of differential planetary gearing

C192S1030FA, C137S512150, C137S856000

Reexamination Certificate

active

06238315

ABSTRACT:

BACKGROUND OF THE INVENTION
a) Field of the Invention
This invention relates to a hydraulic coupling for use with a vehicle drivetrain within a housing containing hydraulic fluid to rotatively couple a pair of rotary members about a rotational axis; for example, a speed sensitive limited slip differential.
b) Background of Related Art
Many types of hydraulic devices have utilized internal gear sets which are often called gerotors or rotors. Such devices can be used as pumps where shaft work is converted to hydraulic work and as motors where hydraulic work is converted to shaft work. In an internal gear pump or motor, an inner gear having outwardly directed teeth cooperates with an external gear having inwardly directed teeth so that fluid chambers therebetween increase and decrease in volume as the inner and outer gears rotate in a housing. By connecting the inlet and outlet of the device to the proper location along the sides of the gear set, the variable displacement chambers receive and discharge hydraulic fluid so that the device can function as a pump or motor. A shaft or other mechanical device can be connected to either the inner or outer gear depending upon the type of device.
Many of the internal gear pumps and motors of the prior art utilize a housing having a fixed inlet and outlet valve port. In other gerotor pumps and motors, a rotary valve plate or disc is used.
The gerotor pump has previously been utilized to couple rotary members of a vehicle drivetrain, particularly a limited slip differential mechanism. However, prior art gerotor pump devices suffer from inadequate or inefficient control valve systems. Conventional check valves and other control valve systems found in the prior art are difficult to handle and assemble and require expensive machining in the differential case.
The need therefore exists for an improved and efficient control valve system to replace the conventional check valve system while providing an effective hydraulic flow path.
SUMMARY OF THE INVENTION
The present invention provides an improved control valve for use in controlling rotative coupling of a pair of rotary members of a vehicle drivetrain.
In carrying out the above object, the control valve of this invention includes a valve system through which pressurized hydraulic fluid selectively flows to control the coupling of the pair of rotary members. The instant invention provides a thin-plate check valve and pressure port stack which creates a hydraulic flow path for a gerotor pump and maintains pressure equalization about the gerotor pump. The thin-plate check valve and pressure port stack comprises a series of relatively thin circular plates assembled in a stacked arrangement, including a spring plate and a seal plate which interface to create a check valve assembly. A port plate provides a pocket to equalize pressure in different areas of the gerotor pump, and a limiter plate prevents the spring arm from being damages by a vacuum and the limiter plate prevents the spring arm from over-travel and deformation. The number and/or thickness of the port plates determine how far the spring arm can travel under pressure.
The plates forming the stack of this invention are relatively large when compared to prior known check valve components and, therefore, are easy to handle and assemble. The plates also provide pressure equalization about the gerotor pump while eliminating relatively expensive machining in the differential case required for conventional valve arrangements.
The objects, features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.


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