초록 ▼

Described are system for recording piston rod position information in a magnetic layer on the piston rod. A piston rod has a magnetically hard layer formed thereon to provide a recording medium. A magnetic pattern is recorded in the magnetically hard layer. A magnetic field sensor disposed adjacent

Described are system for recording piston rod position information in a magnetic layer on the piston rod. A piston rod has a magnetically hard layer formed thereon to provide a recording medium. A magnetic pattern is recorded in the magnetically hard layer. A magnetic field sensor disposed adjacent to the piston rod senses the recorded magnetic pattern while the piston rod is moving and generates signals in response to the magnetic pattern that are used to determine a position of the piston rod.

대표청구항 ▼

What is claimed is: 1. A piston rod position sensing system, comprising: a ferromagnetic steel piston rod; a magnetically hard layer formed on the ferromagnetic steel piston rod to provide a recording medium, a magnetic pattern being recorded in the magnetically hard layer, wherein the magnetic pat

What is claimed is: 1. A piston rod position sensing system, comprising: a ferromagnetic steel piston rod; a magnetically hard layer formed on the ferromagnetic steel piston rod to provide a recording medium, a magnetic pattern being recorded in the magnetically hard layer, wherein the magnetic pattern includes a first magnetized line extending parallel to an axis of the piston rod and a second magnetized line extending along a length of the piston rod and diverging away from the first magnetized line; and a magnetic field sensor disposed adjacent to the piston rod to sense the magnetic pattern recorded in the magnetically hard layer while the piston rod is moving and to generate signals, in response to the sensed magnetic pattern, that are used to determine a position of the piston rod. 2. The piston rod position sensing system of claim 1, further comprising a magnetically soft layer disposed between the magnetically hard layer and the piston rod. 3. The piston rod position sensing system of claim 1, further comprising a non-magnetic layer disposed between the magnetically hard layer and the piston rod. 4. The piston rod position sensing system of claim 1, further comprising a protective layer disposed on the magnetically hard layer. 5. The piston rod position sensing system of claim 1, wherein an area bounded by the first and second magnetized lines is magnetized. 6. The piston rod position sensing system of claim 1, further comprising circuitry for computing one of a velocity and a direction of motion of the piston rod from readings of the magnetic pattern. 7. A piston comprising: a ferromagnetic steel piston rod extending axially from the piston; and a magnetically hard layer formed on the ferromagnetic steel piston rod to provide a recording medium for magnetically storing bits of information along a length of the piston rod, a magnetic pattern being recorded in the magnetically hard layer, wherein the magnetic pattern includes a first magnetized line extending parallel to an axis of the piston rod and a second magnetized line extending helically along a length of the piston rod. 8. The piston of claim 7, wherein an area between the first and second magnetized lines is magnetized. 9. The piston of claim 7, further comprising a magnetically soft layer disposed between the magnetically hard layer and a magnetic substrate of the rod. 10. The piston of claim 7, further comprising a non-magnetic layer disposed between the magnetically hard layer and a surface of the piston rod. 11. The piston of claim 7, further comprising a protective layer disposed on the magnetically hard layer. 12. A piston rod position sensing system, comprising: a cylinder; a piston arranged within the cylinder for movement therein, the piston having a ferromagnetic steel piston rod extending axially from the piston; a magnetically hard layer formed on the ferromagnetic steel piston rod to provide a recording medium, a magnetic pattern being recorded in the magnetically hard layer, wherein the magnetic pattern includes a first magnetized line extending parallel to an axis of the piston rod and a second magnetized line extending along a length of the piston rod and diverging away from the first magnetized line; and a plurality of magnetic field sensors disposed adjacent to the piston rod, each magnetic field sensor sensing a portion of the recorded magnetic pattern while the piston rod is moving relative to the cylinder and generating signals, in response to the sensed portion of the magnetic pattern, for use in determining a position of the piston rod. 13. The piston rod position sensing system of claim 12, further comprising a magnetically soft layer disposed between the magnetically hard layer and the piston rod. 14. The piston rod position sensing system of claim 12, further comprising a non-magnetic layer disposed between the magnetically hard layer and the piston rod. 15. The piston rod position sensing system of claim 12, further comprising a protective layer disposed on the magnetically hard layer. 16. The piston rod position sensing system of claim 12, wherein an area bounded by the first and second magnetized lines is magnetized. 17. The piston rod position sensing system of claim 12, further comprising circuitry for computing one of a velocity and a direction of motion of the piston rod from readings of the magnetic pattern. 18. A piston rod position sensing system, comprising: a ferromagnetic steel piston rod; and magnetically hard layer formed directly on an outer surface of the ferromagnetic steel piston rod to provide a recording medium in which a magnetic pattern is recorded longitudinally, wherein the magnetic pattern includes a first magnetized line extending parallel to an axis of the piston rod and a second magnetized line extending along a length of the piston rod and diverging away from the first magnetized line.