Case Corporation

Danley C Chan

Alan D Berger

Mohammad Javaid Arshad

Daniel L Maierhafer

Peter John Dix

James M Grupka

A hydraulic actuator is disclosed having a cylinder with a piston that is moved by hydraulic fluid. A light guide in one end of the cylinder directs a laser beam into the cylinder, and off the piston where the beam is reflected. The beam then exits the cylinder through at least two light guides connected to two corresponding optical fibers. Each of the optical fibers are joined together into one fiber that carries the reflected beam of light to a photo-diode located remote from the cylinder. A control circuit measures the time of flight of the laser beam.

Multi-fiber cylinder position sensor using time-of-flight technique

A hydraulic actuator is disclosed having a cylinder with a piston that is moved by hydraulic fluid. A laser diode emits a pulse or pulses of light that form laser light beam. These pulses are provided to two or more optical fibers that extend into two or more corresponding cylinders. For each of these cylinders, the optical fiber enters the cylinder at one end of the cylinder and directs a laser beam into the cylinder, and off the piston where the beam is reflected. The reflected beam then exits the cylinder through at least two corresponding optical fibers disposed on either side of the fiber that conducted the light into the cylinder. Each of the optical fibers that receives reflected light is joined together with the others of the optical fibers into one fiber that carries the reflected beam of light to a photo-diode located remote from the cylinder. Each of the photo diodes for each of the two or more cylinders has a corresponding photo diode amplifier. The output of these amplifiers are coupled together and provided to a pulse expansion circuit. The timing circuit that generates the pulse that triggers the laser diode also generates gate pulses for each of the photo diode amplifiers. These gate signals suppress the output of all but one of the photo diode amplifiers. In this manner, the pulse expansion circuit and phase comparator circuits that receive the photo diode amplifier signals will generate an output signal indicative of the time-of-flight of the laser light pulse in only one cylinder at a time. This permits the system to select a specific cylinder and generate a signal indicative of the position of the piston within the cylinder: the time-of-flight of the laser light pulse.

Multi-fiber multi-cylinder position method and apparatus using time-of-flight technique

A loader of the type controlled with an electronic digital controller is disclosed herein. The loader may include conventional mechanical components. However, the hydraulic valve is electronically controlled to provide improved motion control. In particular, the operator controls the loader with a two-axis joystick. When the joystick is moved left or right, the bucket is rolled at a speed proportional to the rate of change of the joystick position and independent of the loader arms. When the joystick is moved forward or backwards, the loader arms of the bucket are raised or lowered. When the joystick is only moved forward or backward with substantially no component of motion left or right, the controller rolls the bucket to maintain a substantially constant angle between the bucket and the loader's frame. This constant attitude control decreases the operator workload and increases control accuracy. The controller provides velocity-based control over the loader arm and bucket motion, or flow-based control for improved stability and accuracy. The controller can monitor available flow and can then limit the commanded flows to the actuators to avoid exceeding the available flow.

Electronic control for a two-axis work implement

A system for determining the extended length or orientation of a hydraulic actuator, or of an implement or joint, is disclosed herein. Electromagnetic (EM) bursts such as ultra-wideband or frequency pulses are generated and applied to a transmitter unit attached to a stationary or moveable portion of the actuator. The EM bursts are launched by the transmitter toward a receiver located on the other of the stationary or moveable portion of the actuator. The time for the EM bursts to travel between the associated antennas of the transmitter and the receiver is determined and converted into a position signal representing the distance therebetween.

Method and apparatus for sensing the orientation of a mechanical actuator

A system for determining the position of a piston moveable within a cylinder, or of an implement or joint, is disclosed herein. Electromagnetic (EM) bursts such as ultra-wideband or frequency pulses are generated and applied to a transmitter/receiver unit. The EM bursts are launched by the transmitter via a focusing antenna assembly from an end of the cylinder housing towards the piston. The fluid in the cylinder housing is in electrical communication with the piston such that a surface of the piston represents an electrical impedance discontinuity which causes the EM bursts to be reflected back to the receiver. The time for the EM bursts to travel from the transmitter to the piston and for the reflections to travel back to the receiver via the antenna assembly is determined and converted into a position signal representing the piston's position. A compensation signal can be used to compensate the position signal for variations in a parameter of the fluid within the cylinder. The parameter may be the dielectric constant, and the variations may be caused by factors such as temperature, contamination and fluid type. The compensation circuit can include a pulse level analyzer, resonance circuit, mini-dipstick, or a capacitance circuit.

Method and apparatus for sensing piston position

A system for determining the position of a piston moveable within a cylinder, or of an implement or joint, is disclosed herein. Electromagnetic (EM) bursts such as ultra-wideband or frequency pulses are generated and applied to a transmitter/receiver unit. The EM bursts are launched by the transmitter along a transmission guide from an end of the cylinder housing towards the piston. The transmission guide can be a dipstick mounted within the cylinder housing or the cylinder housing itself. The dipstick or cylinder housing is in electrical communication with the piston such that a surface of the piston represents an electrical impedance discontinuity which causes the EM bursts to be reflected back to the receiver. The time for the EM bursts to travel from the transmitter to the piston and for the reflections to travel back to the receiver is determined and converted into a position signal representing the piston's position. A compensation signal can be used to compensate the position signal for variations in a parameter of the fluid within the cylinder such as dielectric constant caused by factors such as temperature, contamination and fluid type. The compensation circuit can include a pulse level analyzer, resonance circuit, capacitance circuit, compensation dipstick, or second transmitter/receiver circuit configured to measure the piston's position from the opposite end of the cylinder.

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West Burlington, IA, United States of America

Danley C Chan