Caterpillar Inc.

Catepillar Inc.

James E Schimpf

Javad Hosseini

Nathan T Schenkel

Cynthia M Gardner

William E Allen

Randall M Mitchell

Tony L Marcott

Weldon L Phelps

Hong-Chin Lin

Michael Angel Cobo

Robert E Stone

Eric A Hutchison

John D Duffy

James Thomas Ferrier

Apparatus and methods are provided for controlling a double-acting hydraulic cylinder during a load-induced rod-extending operation. The apparatus includes a activation circuit and valve for providing a flow path from a pump to the cylinder head end; a flow regeneration circuit and valve fluidly connecting the cylinder rod end and the cylinder head end and configured for providing flow from the rod end to the head end during rod extension; and a controller responsive to rod-extending rate demands and rod-position sensor signals, and operatively connected to the regeneration flow valve and the activation valve. The activation valve also includes a return valve part to control flow from the rod end to the fluid reservoir during rod extension. Both the activation valve and the return valve part are controllable by the controller independently from the regeneration flow valve.

Hydraulic flow control system and method

An apparatus for controllably moving a work implement. The implement is connected to a work machine and is moveable in response to the operation of a hydraulic cylinder. The apparatus includes an operator controlled joystick that generates an operator command signal, which is indicative of a desired velocity of the work implement movement. Cylinder position sensors produce cylinder position signals in response to the position of lift and tilt cylinders. A valve assembly receives an electrical valve signal, and controllably provides hydraulic fluid flow to the respective hydraulic cylinders to move the cylinders in accordance with the operator command signal. A controller receives the operator command and cylinder position signals, and responsively produces a pump command signal to change the displacement of a variable displacement pump to regulate the movement of the hydraulic cylinders.

Method and apparatus for controlling an implement of a work machine

A variable displacement pump has a discharge passage and a displacement controller disposed to decrease pump displacement in response to an increasing pressure signal and to increase pump displacement in response to a decreasing pressure signal. A load sensing pump control for the pump includes a displacement control valve having an input port connected to the discharge passage and a signal port connected to the displacement controller. A valve spool controls communication between the input and signal ports and is biased in a direction to block the inlet port from the signal port by a spring. The spool has a differential area for exerting a force against the spool in opposition to the spring force proportional to the pump discharge pressure entering the valve through the input port. A variable force can be selectively exerted against the spool in opposition to the spring force to change the displacement of the pump.

Load sensing pump control for a variable displacement pump

An apparatus for controllably moving an implement is provided. The implement is connected to a work machine and is movable between first and second implement positions in response to operation of a hydraulic actuator. The apparatus includes a joystick with first and second positions and a neutral position. The joystick is normally biased in a neutral position and is movable between the first and second positions. The apparatus senses the position of the joystick and responsively generates a joystick position signal. The joystick maintained at the first and second detent positions in response to manual movement of the joystick to the respective first and second detent positions. The joystick is released from the detent position in response to receiving a release detent signal. The apparatus senses the position of the work implement with respect to the work machine. The apparatus provides hydraulic fluid flow to the hydraulic actuator in response to a magnitude of an electrical valve signal. The apparatus receives the joystick position signal, responsively delivers the electrical valve signal. The magnitude of the electrical valve signal is proportional to the joystick position signal. The apparatus compares the implement position signal with a first detent position and a second detent position and responsively produces the release detent signal.

Apparatus for controlling an implement of a work machine

An apparatus for controllably moving a work implement is disclosed. The implement is connected to a work machine and is moveable in response to operation of a hydraulic cylinder. The apparatus includes an operator controlled joystick. A joystick position sensor senses the position of the joystick and responsively generates an operator command signal. An implement position sensor senses the position of the work implement and responsively produces an implement position signal. A microprocessor based controller receives the implement position and operator command signals, modifies the operator command signal, and produces an electrical valve signal in response to the modified operator command signal. An electrohydraulic valve receives the electrical valve signal, and controllably provides hydraulic fluid flow to the hydraulic cylinder in response to a magnitude of the electrical valve signal.

A method for controlling an apparatus (100) for controllably moving an implement (102) is provided. The implement (102) is connected to a work machine (104) and is movable between first and second implement positions in response to operation of a hydraulic actuator (106). The apparatus (100) includes a joystick (306) with first and second positions and a neutral position. The joystick (306) is normally biased in a neutral position and is movable between the first and second positions. The apparatus senses the position of the joystick (306) and responsively generates a joystick position signal. The joystick (306) maintained at the first and second detent positions in response to manual movement of the joystick to the respective first and second detent positions. The joystick (306) is released from the detent position in response to receiving a release detent signal. The apparatus (100) senses the position of the work implement (102) with respect to the work machine (104). The apparatus (100) provides hydraulic fluid flow to the hydraulic actuator (106) in response to a magnitude of an electrical valve signal. The apparatus (100) receives the joystick position signal, responsively delivers the electrical valve signal. The magnitude of the electrical valve signal is proportional to the joystick position signal. The apparatus (100) compares the implement position signal with a first detent position and a second detent position and responsively produces the release detent signal.

Method for controlling an implement of a work machine

A method for controllably moving an implement is provided. The implement is connected to a work machine and is movable between first and second implement positions in response to operation of a hydraulic actuator. The method includes a joystick with first and second positions and a neutral position. The joystick is normally biased in a neutral position and is movable between the first and second positions. The method senses the position of the joystick and responsively generates a joystick position signals The joystick maintained at the first and second detent positions in response to manual movement of the joystick to the respective first and second detent positions. The joystick is released from the detent position in response to receiving a release detent signal. The method senses the position of the work implement with respect to the work machine. The method provides hydraulic fluid flow to the hydraulic actuator in response to a magnitude of an electrical valve signal. The method receives the joystick position signal, responsively delivers the electrical valve signal. The magnitude of the electrical valve signal is proportional to the joystick position signal. The method compares the implement position signal with a first detent position and a second detent position and responsively produces the release detent signal.

Vehicles having implements are typically used to perform repetitive functions in work cycles. An implement control system raises and lowers an implement relative to the vehicle and reduces the stresses applied to the vehicle from abruptly stopping the motion of the implement. A lever pilot signal is produced in response to the pivotal position of a control lever. An electrohydraulic pilot signal is also produced. The pilot signal having the greater pressure is directed to a main valve for controlling the position of the implement. The method and apparatus of the instant invention are applicable to a number of vehicles having a hydraulically operated implement.

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Plainfield, IL, United States of America

James E Schimpf