Patent ID: 7866149
Filing Date: 2011-01-11
Classification: E02F,F15B

Abstract:
1. A fluid system for use with a machine that employs an actuator for moving an implement and which provides for rapid movement of the implement, the fluid system comprising: a tank for storing fluid; a load sense pump fluidly connected to the tank for drawing fluid from the tank and providing fluid flow in the system; a first valve fluidly connected between the pump and the actuator and between the tank and the actuator, the first valve configured to move between a plurality of open positions for directing fluid from the pump to the actuator and from the actuator to the tank, and a closed position that blocks fluid from flowing from the pump to the actuator and from the actuator to the tank; a load sense line connected to the pump, wherein the pressure indicated by the load sense line represents the magnitude of a load acting on the implement; a supply line fluidly connected between the pump and the first valve in which the rate of fluid flow is varied by the pump so as to maintain a constant pressure differential between the pressure in the supply line and the pressure indicated by the load sense line; a second valve fluidly connected to the supply line for selectively permitting fluid to bypass the first valve and flow back to the tank; an operator input device for enabling an operator to control the movement of the implement by inputting a plurality of commands that specify movement of the first valve between the positions for directing fluid; and a controller configured to monitor the commands received from the operator input device and selectively activate a mode that provides for rapid movement of the implement when the controller detects rapid variations in the commands from the operator input device; wherein the controller operating in the mode that provides for rapid movement of the implement activates the second valve based on a status of the first valve, the activation of the second valve including proportionately opening the second valve when the first valve moves to the closed position and proportionately closing the second valve when the first valve moves to an open position, wherein the activation of the second valve causes the pump to increase or maintain the rate of fluid flow in the supply line so as to maintain the constant pressure differential between the supply line and the load sense line.