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US 6,484,620 B2Granted
Laser based reflective beam cylinder sensor
AssigneeCase Corporation
InventorsMohammad J. Arshad, Alan D. Berger, Danley C. K. Chan
Life of this patent
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Abstract
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 a second light guide. A control unit measures the time of flight of the laser beam and calculates the piston position.
Claims21
A fluid actuated cylindrical actuator, comprising:
- a cylinder having first and second ends;
- an end cap fixed to the first end of the cylinder and having a rod opening;
- a piston disposed in the cylinder;
- a rod coupled to the piston and extending from inside the cylinder to outside the cylinder and passing through the rod opening;
- a first light guide extending from inside the cylinder to outside the cylinder and adapted to transmit at least a first beam of laser light at a first frequency from outside the cylinder to inside the cylinder and to bar the passage of the fluid;
- a second light guide extending from inside the cylinder to outside the cylinder and adapted to transmit the at least a first beam of laser light at said first frequency from inside the cylinder to outside the cylinder and to bar the passage of the fluid;
- and
- wherein the first beam of light is reflected off a first surface inside the cylinder, wherein the first surface is coupled to the rod and configured to move with the rod.
5 more elements
A fluid actuated cylindrical actuator, comprising:
- a cylinder having first and second ends;
- an end cap fixed to the first end of the cylinder and having a rod opening;
- a piston disposed in the cylinder;
- a rod coupled to the piston and extending from inside the cylinder to outside the cylinder and passing through the rod opening;
- a first light guide extending from inside the cylinder to outside the cylinder and adapted to transmit at least a first beam of laser light at a first frequency from outside the cylinder to inside the cylinder and to bar the passage of the fluid;
- and
- a second light guide extending from inside the cylinder to outside the cylinder and adapted to transmit the at least a first beam of laser light at said first frequency from inside the cylinder to outside the cylinder and to bar the passage of the fluid;
- wherein the first light guide is disposed to transmit said first beam of laser light substantially along a longitudinal axis of the cylinder such that the first beam impinges upon a reflective portion of the piston over substantially an entire range of piston travel;
- wherein the second light guide is disposed to receive the first beam after it has been reflected off the piston;
- wherein an optical distance between the first light guide and the second light guide is a function of the degree of extension of the rod outside of the cylinder;
- and
- wherein the first beam of light is reflected off a first surface portion inside the cylinder, wherein the first surface portion is coupled to the rod and configured to move with the rod.
9 more elements
A hydraulic actuator for an agricultural or construction vehicle, the actuator comprising:
- a) a cylinder having a substantially circular inner circumference and a longitudinal cylindrical axis;
- b) a piston having a substantially circular outer circumference configured to be received in and hydraulically sealed against the inner circumference of the cylinder;
- c) a piston rod with a substantially circular outer rod circumference, that is fixed to the piston and extends from the piston inside the cylinder, through a first end wall of the cylinder to a location outside the cylinder, wherein the first end wall is disposed to enclose and seal a first end of the cylinder and is substantially perpendicular to the longitudinal axis of the cylinder;
- d) a second end wall fixed to the cylinder substantially perpendicular to the longitudinal axis of the cylinder and disposed to seal a second end of the cylinder, the second end wall including a first optical element configured to transmit a beam of laser light through the second end wall to a reflective surface fixed to the piston and further including a second optical element configured to transmit the reflected beam of laser light back through the end wall;
- e) a first optical fiber optically and mechanically coupled to the second end wall to transmit the beam of laser light from a remote laser light source to the first optical element;
- and
- f) a second optical fiber optically and mechanically coupled to the second end wall to transmit the reflected beam of laser light to a remote laser light receiver.
4 more elements
Dependencies are inferred from the claim text.