Fluid controller and fluid meter bypass arrangement

Details Fluid controller and fluid meter bypass arrangement Fluid controller and fluid meter bypass arrangement

2000-05-12

2001-11-20

Look, Edward K. (Department: 3745)

Power plants

Pressure fluid source and motor

Expansible chamber type volumetric responsive measuring...

C060S494000

Reexamination Certificate

active

06318078

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
MICROFICHE APPENDIX
Not Applicable
BACKGROUND OF THE DISCLOSURE
The present invention relates to fluid controllers of the type used to control the flow of fluid from a source of pressurized fluid to a fluid pressure actuated device, such as a steering cylinder for steering a vehicle. More particularly, the present invention relates to such a fluid controller having at least two different modes of operation, in terms of the relationship between the manual input to the fluid controller and the rate of fluid flow out of the controller.
Although the present invention may be used in connection with fluid controllers of many types, and having various constructions and applications, it is especially advantageous when used in conjunction with a full-fluid-linked steering controller, for use on a vehicle of primarily the “off highway” type, and will be described in connection therewith.
A conventional fluid controller of the type to which the present invention relates includes a housing which defines various fluid ports, and further includes a fluid meter, a valve means defining a main fluid path, and an arrangement for imparting follow-up movement to the valve means, in response to the flow of fluid through the fluid meter. The flow through the controller valve means is directly proportional to the areas of the variable flow control orifices in the main fluid path. As is well know to those skilled in the art, the area of each flow control orifice is, in turn, typically proportional to the rate at which the steering wheel is rotated.
A typical application for a full-fluid-linked steering controller of the type to which the present invention relates would be a vehicle such as is used on a work site, and such a vehicle would be used in one of two operating modes. First, the vehicle may be operated in a “roading” mode, i.e., it is driven on the road, at normal roading speeds, in order to reach a work site. Second, the vehicle may be operated in a “working” mode, at the work site and is performing work related operations, such as moving a pile of dirt, etc., during which the vehicle is moving at relatively slow speeds.
The roading and working modes of operation described above present very different steering requirements, as is now well know to those skilled in the art. When roading the vehicle, a relatively low gain rate would be desirable, whereas, when operating in the working mode, a relatively high gain rate would be desirable. As used herein, the term “gain rate” refers to the rate of change of steered wheel position for a given amount of steering input (such as, but not limited to, rotation of a vehicle steering wheel). With a conventional full-fluid-linked steering controller, however, the gain rate is actually a constant, and as a result, the amount of steering motion by the vehicle operator while roading is typically acceptable, but the amount of steering motion required at the work site, over the course of a typical workday, can cause excessive operator fatigue.
One approach to providing a steering system which gives the operator separate reading and working modes of operation has been to provide the vehicle operator with a steering wheel for use when the vehicle needs to be in the roading mode, and with a joy stick for use when the vehicle needs to be in the working mode. The steering wheel gives the operator somewhat the same feel as driving an automobile, which is desirable for the roading mode, while the joy stick may be used to provide relatively large steering changes with relatively little operator input (a large gain rate), which is desirable for use in the working mode.
Unfortunately, the provision of a steering wheel/joy stick system adds substantially to the overall expense and complication of the system, in terms of the hardware involved, and also results in substantial complication and expense in order to coordinate the portion of the system operated by the steering wheel with the portion of the system operated by the joy stick.
BRIEF SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an improved fluid controller for use in a vehicle steering system which can provide both a roading mode and a working mode of operation, but which overcomes the disadvantages of the prior art described above.
It is a more specific object of the present invention to provide such an improved fluid controller which can accomplish the above-stated object, while requiring only a single steering input device, thus overcoming the prior art disadvantage of the need to coordinate between two different steering inputs.
It is still another object of the present invention to provide an improved steering system for a vehicle wherein both the roading mode and the working mode may be accomplished in a single fluid controller, thus overcoming the prior art disadvantage of excessive and complicated hardware.
It is still a further object of the present invention to provide an improved fluid controller for use in a vehicle steering system, which greatly reduces the amount of operator steering motion when operating in the working mode.
The above and other objects of the 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 includes housing means defining an inlet port for connection to the source of fluid, and first and second control fluid ports for connection to the fluid pressure operated device. Controller valve means is disposed in the housing means and defines a neutral position, and at least one operating position in which the housing means and the controller valve means cooperate to define a main fluid path providing fluid communication from the inlet port to the first control fluid port and including a fluid actuated means for imparting follow-up movement to the controller valve means generally proportional to the volume of fluid flow through the main fluid path when the controller valve means is in the operating position. The fluid actuated means includes a rotatable measuring member providing the follow-up movement.
The improved fluid controller is characterized by selector valve means disposed in series flow relationship in the main fluid path, between the fluid inlet port and the fluid actuated means and operable, in a first position to permit normal flow through the main fluid path. The selector valve means is operable in a second position to block fluid flow through the fluid actuated means while bypassing the fluid actuated means, thus permitting flow through the main fluid path, but preventing the follow-up movement to the controller valve means.


REFERENCES:
patent: 3249174 (1966-05-01), Orwig
patent: 4759182 (1988-07-01), Haarstad
patent: 5080135 (1992-01-01), Stephenson

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