Patent ID: 8532892

Claim:
A system comprising: a hydraulic fluid pump providing hydraulic fluid at line pressure to a fluid pressure powered component; a piston having a seal; a hydraulic accumulator in fluid communication with the hydraulic fluid pump and the fluid pressure powered component, and containing the piston and the seal, wherein the hydraulic fluid pump is configured to selectively feed some of the hydraulic fluid to the hydraulic accumulator to thereby charge the hydraulic accumulator; a pressure sensor positioned with respect to the hydraulic accumulator that measures the line pressure; and a controller in electrical communication with the pressure sensor, wherein the controller is configured to: calculate respective slopes of a first set and a second set of measured pressure values as communicated to the controller by the pressure sensor; calculate a ratio of the respective slopes; compare the calculated ratio of the respective slopes to a ratio threshold; record a pre-charge pressure as a pressure value corresponding to a point of intersection of a pair of lines representing the respective slopes when the calculated ratio exceeds the ratio threshold, wherein the recorded pre-charge pressure corresponds to a point of inflection of the piston within the hydraulic accumulator at which drag from the seal is first overcome when none of the hydraulic fluid is contained in the hydraulic accumulator; and execute a control action with respect to at least one of the hydraulic fluid pump and the hydraulic accumulator when the recorded pre-charge pressure is less than a calibrated minimum threshold.