Hydro-pneumatic system with pressure limiting valve
AssigneeActuant Corporation
InventorsFrantz D. Stanford, Bruce E. Knuth, Kay Lap Gilbert Chan
Life of this patent
Estimating the term…
Abstract
A hydro-pneumatic system has an air powered motor driving a hydraulic pump with a pressure limiting valve that turns off air flow to the air motor when a hydraulic pressure output by the pump at a sense port of the valve reaches a certain limit. A valve element of the valve has spring, hydraulic and pneumatic sections, with an unbalanced area of the hydraulic section in a sealed pressure chamber of a cartridge that is part of the valve housing. The pneumatic section extends out one end of the cartridge to fill a bore between the air inlet and outlet ports when the pneumatic section is extended, and allow air to pass when it is retracted.
Claims20
A method of operating a hydraulic system, the hydraulic system including a hydraulic pump in communication with a source of hydraulic fluid and operable to draw fluid from the source of hydraulic fluid and deliver the fluid under a supply pressure, an air motor in communication with and powered by a source of compressed air and operable to drive the hydraulic pump, and a pressure limiting valve including a valve housing having an air inlet port in communication with the source of compressed air, an air outlet port and a hydraulic fluid sense port, and a valve element movably supported in the housing and having a hydraulic section in fluid communication with the hydraulic fluid sense port and a pneumatic section in fluid communication with the air inlet port and the air outlet port, the method comprising:
- applying a pressure from the hydraulic pump to the hydraulic fluid sense port;
- when the pressure is below a pressure limit, positioning the valve element in an open position to provide fluid communication between the air inlet port and the air outlet port;
- and
- when the pressure is at the pressure limit, moving the valve element toward a closed position to close fluid communication between the air inlet port and the air outlet port.
A method of operating a hydraulic system, the hydraulic system including a hydraulic pump in communication with a source of hydraulic fluid and operable to draw fluid from the source of hydraulic fluid and deliver the fluid under a supply pressure, an air motor in communication with and powered by a source of compressed air and operable to drive the hydraulic pump, and a pressure limiting valve including a valve housing having an air inlet port in communication with the source of compressed air, an air outlet port and a hydraulic fluid sense port, and a valve element movably supported in the housing and having a hydraulic section in fluid communication with the hydraulic fluid sense port and a pneumatic section in fluid communication with the air inlet port and the air outlet port, the method comprising:
- applying the supply pressure from the hydraulic pump to the hydraulic fluid sense port;
- when the pressure is below a pressure limit, positioning the valve element in an open position to provide fluid communication between the air inlet port and the air outlet port;
- and
- when the pressure is at the pressure limit, moving the valve element toward a closed position to close fluid communication between the air inlet port and the art outlet port.
A method of operating a hydraulic system, the hydraulic system including a hydraulic pump in communication with a source of hydraulic fluid and operable to draw fluid from the source of hydraulic fluid and deliver the fluid under a supply pressure, an air motor in communication with and powered by a source of compressed air and operable to drive the hydraulic pump, and a pressure limiting valve including a valve housing having an air inlet port in communication with the source of compressed air, an air outlet port and a hydraulic fluid sense port, a valve element movably supported in the housing and having a hydraulic section in fluid communication with the hydraulic fluid sense port and a pneumatic section in fluid communication with the air inlet port and the air outlet port, and a spring, the method comprising:
- applying the supply pressure from the hydraulic pump to the hydraulic fluid sense port;
- when the pressure is below a pressure limit, positioning the valve element in an open position to provide fluid communication between the air inlet port and the air outlet port, positioning including urging the valve element toward the open position with the spring;
- when the pressure is at the pressure limit, moving the valve element toward a closed position to close fluid communication between the air inlet port and the air outlet port, moving including overcoming a force applied by the spring;
- and
- adjusting a force applied by the spring to the valve element to adjust a value of the pressure limit.
Dependencies are inferred from the claim text.