PRESSURE CONTROL SYSTEM FOR A HYDRAULIC LIFT AND FLOTATION SYSTEM
First Claim
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1. A hydraulic lift and flotation system comprising:
- a hydraulic cylinder to provide lift and flotation functionality for a machine;
a pump to circulate a hydraulic fluid in the hydraulic lift and flotation system;
a relief valve in fluid communication with the pump, the relief valve providing general pressure regulation in the hydraulic lift and flotation system;
an unload valve in fluid communication with the pump and a controller, the unload valve controlling pressurization in the hydraulic lift and flotation system;
a solenoid configured and positioned to control opening and closing of the unload valve;
the controller being configured to execute a control algorithm to provide control instructions to the solenoid to control the unload valve; and
the control instructions operating the solenoid to close the unload valve over a period of time to control a rate of pressure rise in the hydraulic lift and flotation system until a predetermined pressure is obtained.
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Abstract
A control system is provided to control the rate of pressure rise in a hydraulic lift and flotation system. When a hydraulic cylinder of the hydraulic lift and flotation system is to be adjusted, the pressure in the hydraulic lift and flotation system has to be increased to a predetermined pressure controlled by a relief valve before the hydraulic cylinder can be operated. The unload valve of the hydraulic lift and flotation system can be closed in a controlled or regulated manner in order to control the rate at which pressure rises in the hydraulic lift and flotation system.
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Citations
20 Claims
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1. A hydraulic lift and flotation system comprising:
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a hydraulic cylinder to provide lift and flotation functionality for a machine; a pump to circulate a hydraulic fluid in the hydraulic lift and flotation system; a relief valve in fluid communication with the pump, the relief valve providing general pressure regulation in the hydraulic lift and flotation system; an unload valve in fluid communication with the pump and a controller, the unload valve controlling pressurization in the hydraulic lift and flotation system; a solenoid configured and positioned to control opening and closing of the unload valve; the controller being configured to execute a control algorithm to provide control instructions to the solenoid to control the unload valve; and the control instructions operating the solenoid to close the unload valve over a period of time to control a rate of pressure rise in the hydraulic lift and flotation system until a predetermined pressure is obtained. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of controlling pressure rise rates in a hydraulic lift and flotation system comprising:
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providing a hydraulic lift and flotation system comprising a pump, a hydraulic cylinder, a first valve, a second valve and a fluid reservoir, the first valve being positioned to control fluid flow at the hydraulic cylinder; operating the hydraulic lift and flotation system with the second valve in an open position to permit fluid to flow from the reservoir to the pump through the second valve and back to the reservoir; receiving a command to operate the hydraulic cylinder; selecting a control algorithm configured to close the second valve, wherein closing the second valve prevents return flow of fluid to the reservoir and builds pressure in the hydraulic lift and flotation system; applying control signals to the second valve with the control algorithm until the second valve is in a closed position, wherein each control signal is configured to close the second valve a predetermined amount and the closing of the second valve by a predetermined amount controls the rate of pressure rise in the hydraulic lift and flotation system. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A harvesting machine comprising:
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a tractor adapted for movement over the ground, the tractor comprising a frame having a front end and an opposing rear end; an elongate header having a first end and a second opposing end, the first and second ends defining a length of the elongate header, the header being supported at the front end of the frame by first and second support points located intermediate the first and second ends; a header lift and flotation system interconnecting the header and the frame for selectively raising and lowering the header relative to the ground and setting flotation parameters, the header lift and flotation system including; left and right hand hydraulic cylinders interconnecting the frame and the header adjacent the respective first and second support points; a hydraulic fluid reservoir; substantially independent left and right hand electro-hydraulic circuits, each electro-hydraulic circuit interconnecting the hydraulic fluid reservoir and the corresponding hydraulic cylinder, each electro-hydraulic circuit comprising; a hydraulic pump; a valve in fluid communication with the hydraulic pump, the valve being adjustable between a closed position and an open position; a controller, the controller being configured to execute a control algorithm to provide control instructions to the valve to adjust the position of the valve; and the control instructions provided to the valve operating to close the valve over a period of time to control a rate of pressure rise in the header lift and flotation system. - View Dependent Claims (20)
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Specification