Caterpillar Inc.

Douglas W Koehler

James Alvin Aardema

John James Krone

Michael Angel Cobo

Jiao Zhang

Thomas J Hajek

Edward William Mate

Michael Todd Verkuilen

Hyppolite Kuissi

Bradford Jay Holt

Dennis J Hausman

Michael Schwab

Balbahadur Singh

Vincent Triffaux

Chris J Scolton

John D Duffy

Sandeep John Verghese

R Carl Wilbur

A hydraulic system is disclosed having at least two hydraulic circuits. The disclosed system apportions flow between the two hydraulic circuits based on an assumed flow rate that is held constant in both power-limited and non-power-limited conditions.

Hydraulic system and method for control

A coolant flow control system includes a fluid cooling device, a coolant bypass circuit, and a controller. The controller is configured to generate a control signal indicative of a desired flow of coolant through the coolant bypass circuit as a function of the projected rate of change in the cooling device temperature gradient.

Coolant flow control system and method

A transmission for use with a machine is disclosed. The transmission may have a pump, a motor fluidly connected to receive pressurized fluid from the pump and propel the machine, and an operator input device configured to generate a signal indicative of an operator desired gear ratio of the transmission. The transmission may also have a controller in communication with the pump, the motor, and the operator input device. The controller may be configured to determine an desired gear ratio of the transmission as a function of the signal, and determine an efficiency loss of the transmission at the desired gear ratio. The controller may also be configured to select a known setting of at least one of the pump and motor that provides the desired gear ratio and accounts for the efficiency loss.

Hystat transmission having pressure override control

A pressure compensator for use in a control system for an electro hydraulic-implemented work element being operated through the use of operator input control mechanisms generating operator input signals upon the application thereof, the control system including an actuator coupled thereto for controlling the operation thereof, the pressure compensator determining a pressure compensator coefficient to be applied to an operator input signal to compensate for changes of pressure drop across a valve in communication with the actuator. The pressure compensator coefficient is used to produce an input flow control signal for inputting to the valve to control the amount of hydraulic fluid that flows therethrough to the actuator so that a desired velocity of the actuator is achieved.

System and method of pressure compensation for electro hydraulic control systems

A hydraulic control system having a pump for delivering fluid under pressure from a fluid reservoir, a hydraulic actuator selectively driven by the fluid, the system comprises a main flow control valve connected between the pump and the actuator for selectively providing the fluid to and from the actuator, and a control unit connected to the main flow control valve for controlling operation of the main flow control valve to control the rate of change of the area of the main flow control valve relative to the delivery of fluid from the pump, and the control unit connected to the pump to increase or decrease the actual pump command proportional to the inverse of the pump command.

Hydraulic control system for improving pump response and dynamic matching of pump and valve

A system for controlling an independent metering valve having a pair of independently controlled electrohydraulic displacement controlled spool valves for controlling pump-to-cylinder communication between an inlet port and a pair of control ports and another pair of independently controlled electrohydraulic displacement controlled spool valves for controlling cylinder-to-tank fluid flow between the control ports and an outlet port. The spool valves of the independent metering valve are calibrated to provide the required fluid flow.

System and method for calibrating a independent metering valve

An apparatus controllably moves a moveable element within a hydraulic motor. A lever device establishes an operator command signal indicative of a desired velocity and direction of movement of the moveable element. A position sensor senses the position of the moveable element and produce a position signal. An electronic controller receives the operator command signal and position signal, determines the actual velocity of the moveable element, and determines a limit value in response to the actual velocity of the moveable element. Additionally, the controller compares the operator signal magnitude to the limit value and produces a flow control signal in response to the comparison. An electrohydraulic controller receives the flow control signal and responsively controls the movement of the moveable element.

Method and apparatus for controlling the actuation of a hydraulic cylinder

A control arrangement operates in conjunction with a control scheme to control the maximum pressure level within a conduit network of a fluid system without the need to have high flow pressure relief valves. The control arrangement provides a low flow pressure relief valve connected in parallel with an electrically actuated valve mechanism to trim any over-pressure conditions so that the control scheme has more time to move the electrically actuated valve mechanism to a flow bypassing, pressure relieving position.

Off-setting rate of pressure rise in a fluid system

The present invention provides a method and apparatus for controlling the fluid flow in a fluid circuit,. The fluid circuit,includes a pump,driven by an engine,. The pump,delivers fluid to at least one actuator,through a control valve assembly,. In addition, the pump is connected to a bypass control valve, which is connected to a fluid tank. The method includes the steps of establishing a desired fluid flow to be delivered by the pump, determining an expected fluid flow to be delivered by the pump in response to the desired fluid flow, and determining a position of the bypass control valve in response to the expected fluid flow.

Method and apparatus for controlling a bypass valve of a fluid circuit

A system and method for controlling an independent metering valve operating in a hydraulic circuit determines a displacement command for one or more metering valves to provide desired flows through the metering valves and desired pressure drops across the metering valves. The system determines the displacement command based on a mode of operation of the hydraulic circuit and a velocity for a hydraulic device controlled by the hydraulic circuit. The system determines the displacement command further based on an amount of flow available to the hydraulic circuit. The system allows the hydraulic circuit to be electronically controlled thereby providing flexibility not found in conventional hydraulic control systems.

System and method for controlling an independent metering valve

A control system is typically used for controlling the implements of a machine. The control system includes a operator control section and a electronic control section having a module for sensing a pair of control signals from the operator control section. When a lift signal and a dump signal is sensed the module will modify the electronic control section in response to the sensed signals.

Control to improve dump while lifting

A control system is typically used for controlling the implements of a machine. The control system includes a lift circuit and a tilt circuit. The control system includes a module which receives a signal from the lift circuit and the tilt circuit and selects a signal for controlling a valve to meter pump-to-cylinder fluid flow.

Tilt priority scheme for a control system

A control system is provided for use in a hydraulic system to provide a simple arrangement with a limited number of elements that bypasses the system flow in the event of an electrical malfunction in the system and further allows other hydraulic circuits to operate even if one or more of the hydraulic circuits have experienced an electrical malfunction. The subject arrangement uses an electro-hydraulic fluid flow control valve mechanism in conjunction with directional valve mechanisms that have at least three functional positions and are controlled by associated electrically controlled displacement control mechanisms in response to receipt of electrical signals from an electrical controller. In the event of an electrical malfunction, each of the directional valve mechanisms are spring biased to one of its extreme positions in the absence of an electrical signal to the associated electrically controlled displacement control mechanisms and the electro-hydraulic fluid flow control valve mechanism bypasses all of the fluid from a source of pressurized fluid to a reservoir. With the directional valve mechanisms of one hydraulic circuit in their spring biased extreme positions, the electrical signal to the electro-hydraulic fluid flow control valve mechanism can be re-instated and the other hydraulics can be operated.

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Peoria, IL, United States of America

Douglas W Koehler