Steering controller with integral parallel control

Reference Number: N 02-03

Inventors: Stephenson, Dwight B.

Owner: NISTAC

USPTO Link: 5016672

Invention Summary

Accordingly, it is an object of the present invention to provide an improved steering control system including both a conventional rotary input controller and a parallel control capability, and which is simpler, less expensive, and requires substantially less plumbing than the prior art systems which have been proposed.

It is a more specific object of the present invention to provide an improved fluid control system which achieves the above-stated object by providing the parallel fluid path within the fluid controller.

It is another object of the present invention to provide an improved fluid controller of the spool-sleeve valve type which is operable to control fluid flow in response to either conventional rotary input to the spool-sleeve valving, or in response to some other form of control input.

It is still another object of the present invention to provide an improved fluid controller which is operable to define a main fluid path, including the fluid meter, in response to the conventional rotary input, or to define a parallel fluid path which excludes the fluid meter.

It is a related object of the present invention to provide an improved fluid controller of the spool-sleeve type having an improved valving architecture which makes it possible to define a parallel fluid path which excludes the fluid meter, while at the same time, defining a main fluid path which includes the fluid meter to facilitate emergency manual steering.

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 a housing defining an inlet port for connection to the source of pressurized fluid, a return port for connection to a reservoir, and first and second control fluid ports for connection to the fluid pressure operator device. Valve means is disposed in the housing and comprises a primary, rotatable valve member and a cooperating, relatively rotatable follow-up valve member, the valve members defining a neutral rotary position and a first 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 primary valve member defines first and second fluid passages, and the follow-up valve member defines a first fluid port in continuous fluid communication with the inlet port and a second fluid port in continuous fluid communication with the first control fluid port. The first and second fluid ports are blocked from fluid communication with the first and second fluid passages, respectively when the valve members are in the neutral rotary position. The first fluid port is in communication with the first fluid passage to define a first variable flow control orifice and the second fluid port is in communication with the second fluid passage, to define a second variable flow control orifice, when the valve members are in the first rotary operating position. The housing means and the valve members cooperate to define a first main fluid path providing communication between the first and second variable flow control orifices.

The improved controller is characterized by the primary and follow-up valve members defining a neutral axial position and a first 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 first 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 communication with the inlet port, and a second axial fluid port in continuous communication with the first control fluid port. The first axial fluid port is blocked from fluid communication with the first axial fluid passage, and the second axial fluid port is blocked from communication with the second axial fluid passage, when the valve members are in the neutral axial position. The first axial fluid port is in communication with the first axial fluid passage to define a first variable axial flow control orifice, and the second axial fluid port is in communication with the second axial fluid passage to define a second variable axial flow control orifice when the valve members are in the first axial operating position. The valve members cooperate to define a first parallel fluid path providing fluid communication between the first and second variable axial flow control orifices when the valve members are in the first axial operating position.

In accordance with another aspect of the present invention, the fluid controller includes a fluid actuated means for imparting follow-up movement to the follow-up valve member proportional to the volume of fluid flow through the first main fluid path when the valve members are in the first rotary operating position. When the valve members are in the first axial operating position, the first parallel fluid path excludes the fluid actuated means.