Fluid controller and logic control system for use therewith

Reference Number: N 02-03

Inventors: Stephenson, Dwight B.; Hastreiter, James J.

USPTO Link: 5115640

Invention Summary

Accordingly, it is an object of the present invention to provide an improved fluid controller and a parallel electro-hydraulic control valve without the need for separate, expensive valves, external to the fluid controller, while maintaining the capability of manually steering, or having the fluid controller override the operation of the electro-hydraulic valve, especially in the event of a malfunction in the electronic controls.

It is a more specific object of the present invention to provide an improved fluid controller which achieves the above-stated object by providing the parallel, electro-hydraulic valve within the fluid controller.

It is another object of the present invention to provide an improved fluid controller and logic control system for controlling the parallel, electro-hydraulic valve which satisfies various performance criteria such as those set forth above.

The above and other objects of the present invention are accomplished by the provision of an improved fluid controller operable to control the flow of fluid from a source of pressurized fluid to a fluid pressure operated device. The controller is of the type including housing means defining an inlet port for connection to the source of pressurized fluid, a return port for connection with the system reservoir, and first and second control fluid ports for connection to the fluid pressure operated device. Valve means is disposed in the housing means, and comprises a primary, rotatable valve member and a cooperating, relatively rotatable follow-up valve member, the primary and follow-up valve members defining a neutral rotary position and a rotary operating position in which the primary valve member is rotatably displaced from the neutral rotary position relative to the follow-up valve member. The housing means and the valve members cooperate to define a main fluid path providing fluid communication from the inlet port to the first control fluid port, and from the second control fluid port to the return port, when the valve members are in the rotary operating position. The primary and follow-up valve members define a neutral axial position and an axial operating position. The controller includes means operable to bias the valve members toward the neutral axial position and means operable to displace the valve members to the axial operating position.

The primary valve member defines first and second axial fluid passages, and the follow-up valve member defines a first axial fluid port in continuous fluid communication with the inlet port, and a second axial fluid port in continuous fluid communication with the first control fluid port. The first and second axial fluid ports are blocked from fluid communication with the first and second axial fluid passages, respectively, where the valve members are in the neutral axial position. The first and second axial fluid ports are in fluid communication with the first and second axial fluid passages, respectively, when the valve members are in the axial operating position to thereby define a portion of a parallel fluid path. The axial fluid ports and the axial fluid passages are configured such that when the primary and follow-up valve members are simultaneously defining the rotary operating position and the axial operating position, the valve members and the housing means cooperate to define the main fluid path and the parallel fluid path, simultaneously, whereby the total flow to the fluid pressure operated device is approximately the sum of the flows in the main and parallel fluid paths.

In accordance with another aspect of the present invention, there is provided an improved method of controlling the flow of fluid from a source of pressurized fluid through a fluid controller in response to the position and movement of an input device, to cause the position of a steering cylinder to conform to the position of the input device. The method comprises the steps of providing the fluid controller with main valving operable to define a main fluid path, and control fluid flow therethrough, in response to the movement of the input device, and auxiliary valving operable to define an auxiliary fluid path, and control the flow of fluid therethrough, in response to changes in a command signal. The method further comprises the steps of sensing the position of the input device and generating an input position signal, sensing the position of the steering cylinder and generating an output position signal, and comparing the output position signal to the input position signal and generating the command signal. The method includes the final step of transmitting a signal representative of the command signal to the auxiliary valving and modulating the auxiliary valving to drive the output position signal toward the input position signal.