Method and system for determining an accumulator pre-charge pressure in a fluid circuit

• Main Authors: NASSOURI CRYSTAL, SCHANG MARK A, PUDVAY STEPHEN LEWIS
• Format: Patent
• Language: English
• Published: 10.09.2013
• Subjects: ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; BLASTING; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR; ENGINEERING ELEMENTS AND UNITS; FLUID-PRESSURE ACTUATORS; FLUID-PRESSURE ACTUATORS, e.g. SERVO-MOTORS; GEARING; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; HEATING; HYDRAULICS OR PNEUMATICS IN GENERAL; LIGHTING; MECHANICAL ENGINEERING; PERFORMING OPERATIONS; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OFVEHICLES; SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; THERMAL INSULATION IN GENERAL; TRANSPORTING; VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES; VEHICLES IN GENERAL; WEAPONS

A system includes a pump, accumulator, a sensor which measures line pressure in a fluid circuit, and a controller. The controller plots and calculates respective slopes of first and second sets of measured pressure values from the sensor, calculates a slope ratio, and compares the slope ratio to a threshold. The controller also records the pre-charge pressure as the point of intersection of lines representing the slopes when the ratio exceeds the threshold. A control action is executed when the pre-charge pressure drops below a calibrated minimum threshold. A method includes measuring the pressure values, calculating the respective slopes and the slope ratio, comparing the slope ratio to a ratio threshold, recording the point of intersection of lines representing the slopes as an interpolated pre-charge pressure value when the ratio exceeds the threshold, and executing the control action.