Caterpillar Inc.

Tony L Marcott

Thomas J Hajek

Hongliu Du

Andrew Henry Nippert

Noel J Rytter

Srikrishnan T Tolappa

Michael Anthony A'Hearn

Matthew G Branch

Randall M Mitchell

David E Nelson

James E Schimpf

Kirk S Shively

Lowell E Johnson

Michael F Coffman

Dwight S Holloway

Saurabh Pandey

Philip C McKenzie

David W Bump, Deceased

A system for providing hydraulic power in a machine transmission includes a first hydraulic variator and a second hydraulic variator, each variator having a mechanical input to a hydraulic pump, and a hydraulic motor linked to the hydraulic pump via a hydraulic circuit, and a mechanical output from the hydraulic motor. In an embodiment, the first hydraulic circuit side of one variator is hydraulically connected to the first hydraulic side of the other variator, and the second hydraulic circuit sides are likewise linked together. A common input is geared to the inputs of the variators and a common output is geared to the outputs of the variators, tying the pump and motor of each variator to rotate at the same speed as the counterpart components of the other variator.

Multiple-variator control for split power CVT and hydrostatic transmissions

A system for controlling a power output is disclosed. The system includes a hydraulic actuator configured to output a first torque and a source of pressurized fluid configured to supply a flow of pressurized fluid to the hydraulic actuator. The system further includes a controller configured to control the flow of pressurized fluid as a function of the first torque, a predetermined torque, and changes to the first torque caused by a load operatively connected to the hydraulic actuator.

System for controlling a power output

A fluid control system including a control valve providing a simple, easy to use regeneration capability in association with a pump, a tank, and a double acting actuator having a first actuating chamber and a second actuating chamber. The control valve has a first actuating chamber port connected to the first actuating chamber, a second actuating chamber port connected to the second actuating chamber, a tank port connected to the tank, a first pump port and a second pump port. The control valve includes a connecting passage connecting the first pump port and the second pump port to the pump, and is operable in a first position to allow fluid flow from the pump through the first pump port and the first actuating chamber port to the first actuating chamber and fluid flow from the second actuating chamber through the second actuating chamber port and the tank port to the tank. For regeneration, the control valve member is movable from the first position to a second position to allow the fluid flow from the second actuating chamber port to be diverted to the second pump port such that the fluid flow can pass through the connecting passage to the first pump port and through the first actuating chamber port to the first actuating chamber of the actuator.

Fluid control system with regeneration

An electrohydraulic pressure regulating valve comprises a variable orifice disposed between a supply port and a control port and has a fixed size vent orifice disposed downstream of the variable orifice and in parallel with the control port to reduce the flow forces acting on the spool so that the valve is less sensitive to solenoid and spool quality and has improved pressure control capability.

Electrohydraulic pressure regulating valve

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 determining the position of an armature of an electromagnetic actuator having a coil, the armature being movable to and between first and second positions in response to a current flowing in the coil. The apparatus includes circuitry for measuring the magnitude of current in the coil and producing a magnitude signal, measuring the rate of change of current in the coil and producing a rate of change signal, and measuring the derivative of flux linkage versus current in the coil in response to the rate of change signal and producing a flux linkage signal. The apparatus additionally includes circuitry for determining the position of the armature with respect to the coil in response to the magnitude and flux linkage signals.

Method and apparatus for determining the position of an armature of an

An electrohydraulic steering system has a three position pilot operated directional valve disposed between a variable displacement pump and a pair of steer cylinders. The directional valve controls the direction of fluid flow from the pump to the steer cylinders while the displacement of the variable displacement pump is controlled to vary the rate of fluid flow to the steer cylinders. The directional valve is moved to an on position in response to a pilot signal delivered thereto from a pilot valve device while the displacement setting of the variable displacement pump is varied by an electrical signal delivered to a displacement controller from a position sensor mechanism.

Electrohydraulic steering system

An electrohydraulic steering system has a pair of proportional valves for controlling displacement of a steering valve for normal steering functions. The proportional valves are selectively energized by a position sensor in response to rotation of a steering wheel. However, should an electrical malfunction occur, rotation of the steering wheel beyond the normal operating range causes a steering control member to mechanically move an armature of the proportional valves through a spring to provide mechanical/hydraulic steering. Making the armatures of the proportional valves responsive to a mechanical input through the springs provides a simple, cost effective mechanical/hydraulic backup for the primary electrohydraulic steering control.

In machines that are articulated in response to a steer input mechanism, it is many times necessary for the operator to make a steer input and then to make corrective adjustments in order to obtain the desired steer angle of the machine. In the subject invention, an electro-hydraulic steering system is provided which senses the desired steer input by the operator, senses the degree of articulation of the machine and a microprocessor delivers an electrical control signal (P) to an electro-hydraulic valve mechanism which effectively controls articulation of the machine. Once the machine has reached the degree of articulation desired by the operator, the microprocessor signals the electro-hydraulic valve mechanism to stop articulation of the machine. Consequently, the operator does not have to provide any adjustments thereto. Additionally, the ground speed of the machine is sensed and the rate of articulation is controlled in response thereto. In the subject arrangement, in the event of an electrical system failure, a back-up steering control circuit is automatically functional to control steering of the machine in a conventional manner. This arrangement provides an electro-hydraulic steering system that eases the operators fatigue by eliminating the need for corrective steer adjustments and is simple in construction and reliable in operation.

Electro-hydraulic steering system

Electromagnetic actuators having a coil and an armature are used in a number of applications in which it is useful to have an indication of the position of the armature with respect to the coil without the use of external sensors. Accordingly, an actuator control system is provided for determining the position of the armature with respect to the coil in response to the magnitude and rate of change of current flowing in the coil.

Method and apparatus for determining the position of an armature in an

An apparatus is adapted to detect an end-of-fill condition of an actuator having a varying control volume, C. The apparatus includes a solenoid having a coil and an armature. The armature is movable relative to the coil in response to energization of the coil. A control valve delivers a flow of fluid to the actuator. The rate of the fluid flow is responsive to the movement of the armature. An electrical circuit detects a voltage spike across the coil and responsively produces an end-of-fill signal. The voltage spike is generated by an electromotive force produced by the armature in response to the control volume achieving a predetermined end-of-fill pressure.

End of fill detector for a hydraulic clutch

A vehicle such as an earthmoving wheel loader has an engine, a torque converter having an impeller element, a reactor element and a turbine element, and an input clutch connected between the engine and the impeller element. An electrohydraulic control device is provided to controllably engage the input clutch and that includes a microprocessor-based electronic control module, an actuator mechanism having a control member that is progressively movable between first, second and third positions to deliver a first electrical signal to the electronic control module, and a valve for directing fluid to the input clutch at a decreasing pressure level when the control member is moved from the first to the second positions in response to another signal from the electronic control module. The electronic control module is programmed to maintain at least a minimal pressure level to the actuating piston of the input clutch when the control member is between the second and third positions. Moreover, a service brake is increasingly engaged by a service brake mechanism in response to the control member moving between the second and third positions. Other logic functions are included to control the input clutch and a lockup clutch connected between the engine and the turbine element.

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Plainfield, IL, United States of America

Tony L Marcott