Encoding system for determining the position of a cylinder rod along a path of movement

• US 6,147,342 A
• Filed: 06/02/1998
• Issued: 11/14/2000
• Est. Priority Date: 06/02/1998
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Kucher, Trent S.
• Primary Examiner(s): Le, Que T.
• Assistant Examiner(s): PYO, KEVIN K
• Application Number:
  US09/088,998
• Time in Patent Office: 896 Days
• Field of Search: 250/231.13, 250/231.14, 250/231.18, 356/373, 356/375, 341/9, 341/11, 341/13, 341/15
• US Class Current: 250/231.13
• CPC Class Codes: F15B 15/2846 using detection of markings, e.g. markings on the piston rod
• CPC Class Codes: F15B 15/2861 using magnetic means
• CPC Class Codes: F15B 15/2876 using optical means, e.g. laser
• CPC Class Codes: G01D 5/34 the beams of light being detected by photocells
• CPC Class Codes: G01D 5/34776 Absolute encoders with analogue or digital scales

Abstract

An encoding system for determining the position of a cylinder rod along a path of movement, the encoding system including a sequence of code segments located on the rod along the path of movement, each of the code segments including a distinct pattern of marks extending from a starting position in a direction transverse to the path of movement and identifying the position of the code segment on the rod, the encoding system further including at least one mark on the rod extending substantially continuously along the path of movement in predetermined relation to the starting positions of the patterns of marks for indicating the locations thereof.

Claims

1. An encoding system for determining the position of a cylinder rod along a path of movement, comprising:

a sequence of code segments located on the rod along the path of movement, each of the code segments comprising a distinct pattern of marks extending from a starting position in a direction transverse to the path of movement and identifying the position of the code segment on the rod, and

at least one orientation mark on the rod extending substantially continuously along the path of movement in predetermined relation to the starting positions of the patterns of marks for indicating the locations of the starting positions of the code segments.

2. The encoding system, as set forth in claim 1, wherein each of the patterns of marks comprises a binary code.

3. The encoding system, as set forth in claim 2, wherein the binary code comprises at least five bits.

4. The encoding system, as set forth in claim 3, wherein the binary code comprises about ten bits.

5. The encoding system, as set forth in claim 1, wherein the marks are formed on the cylinder rod chemically.

6. The encoding system, as set forth in claim 1, wherein the marks are formed on the cylinder rod by diffusing a material into the surface of the cylinder rod.

7. The encoding system, as set forth in claim 1, wherein the marks are etched on the cylinder rod.

8. The encoding system, as set forth in claim 1, wherein the marks have detectable capacitance characteristics.

9. The encoding system, as set forth in claim 1, wherein the direction transverse to the path of movement is substantially perpendicular to the path of movement.

10. The encoding system, as set forth in claim 1, wherein the direction transverse to the path of movement is a direction oriented at an acute angle to the path of movement.

11. The encoding system, as set forth in claim 1, wherein at least the marks comprising the code segments are dots.

12. The encoding system, as set forth in claim 1, wherein the sequence of the code segments comprises adjacent code segments located in substantially abutting or closely spaced relation.

13. The encoding system, as set forth in claim 1, wherein the path of movement is defined by relative movement between the cylinder rod and a cylinder body.

14. The encoding system, as set forth in claim 1, wherein the at least one orientation mark comprises a plurality of orientation marks extending in single file order along the path of movement.

15. The encoding system, as set forth in claim 1, wherein the at least one orientation mark comprises an elongate mark.

16. The encoding system, as set forth in claim 1, comprising a device for detecting the presence or absence of the marks.

17. The encoding system, as set forth in claim 16, wherein the device for detecting the presence or absence of the marks has a sensory extent greater in the direction transverse to the path of movement than the extent of the pattern of the marks.

18. A cylinder rod comprising:

an outer circumferential surface and a longitudinal axis;

an axially extending sequence of code segments located on the outer circumferential surface, each of the code segments comprising a distinct pattern of marks extending from a starting position in a direction transverse to the longitudinal axis and identifying the position of the code segment on the outer circumferential surface; and

at least one orientation mark on the outer circumferential surface in predetermined relation to the starting position of the patterns of marks for indicating the locations of the starting positions of the code segments.

19. The cylinder rod, as set forth in claim 18, wherein each of the patterns of marks comprises a binary code.

20. The cylinder rod, as set forth in claim 19, wherein the binary code comprises at least five bits.