Power plants – Pressure fluid source and motor – Condition responsive control of or by input to input pump...
Reexamination Certificate
1999-10-25
2001-11-13
Ryznic, John E. (Department: 3745)
Power plants
Pressure fluid source and motor
Condition responsive control of or by input to input pump...
C074S068000
Reexamination Certificate
active
06314727
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to an electro-hydraulic fluid system, and more particularly, to a method and apparatus for controlling an electro-hydraulic fluid system.
BACKGROUND ART
Earth moving machines such as a wheel loader, may include an elector-hydraulic system having several fluid systems, such as the transmission, implement, and steering fluid systems. The engine, and associated pump(s), of the earth moving machine deliver the desired power, or desired fluid flow to these systems in order to provide the desired system responsiveness to the operator. However, there are times during operation of the vehicle, when the needs of the various fluid systems exceed what the engine may provide. For example, when the load of the hydraulic system exceeds the capability of the pump and engine, the engine may begin to lug. When the engine is unable to provide the desired power to the fluid systems, i.e., the electro-hydraulic system is saturated, the responsiveness of the electro-hydraulic system is undesirably reduced. Using algorithms to prioritize how the available power is distributed among the fluid systems helps allocate the available power, however the electro-hydraulic system is still unable to deliver the desired responsiveness to the operator for the fluid systems.
The present invention is directed to overcoming one or more of the problems identified above.
DISCLOSURE OF THE INVENTION
In one aspect of the present invention, a method for controlling an electro-hydraulic fluid system of an earthmoving machine is provided. The electro-hydraulic fluid system includes a pump providing fluid to at least one fluid system, an engine connected to the pump, the engine providing power to the pump, and a controller for providing a command to the engine. The method includes the steps of determining a desired characteristic of the fluid system, comparing the desired characteristic with a deliverable characteristic, and generating a power boost in response to said desired characteristic and said deliverable characteristic.
In another aspect of the present invention, an apparatus adapted to control an electro-hydraulic system of an earthmoving machine, the electro-hydraulic system including a pump providing fluid to at least one fluid system, an engine connected to the pump, the engine providing power to the pump, and a controller for providing a command to the engine. The apparatus comprises a pump adapted to provide fluid to at least one of the fluid systems, an engine mechanically connected to the pump, and a controller adapted to determining a desired characteristic of the electro-hydraulic system, comparing said desired characteristic with a deliverable characteristic of the electro-hydraulic system, and generating a power boost in response to the comparison; thereby controlling the electro-hydraulic system.
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Prabhu Sameer M.
Singh Satyendra
Taggart Brian F.
Caterpillar Inc.
McPherson III W. Bryan
Ryznic John E.
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