Linear position sensor using a strain gage

• US 6,369,689 B1
• Filed: 07/10/2001
• Issued: 04/09/2002
• Est. Priority Date: 07/10/2001
• Status: Expired due to Fees

• Current Assignee: CTS Corporation
• Original Assignee: CTS Corporation
• Inventors: Rainey, Robert, Osmer, William G.
• Primary Examiner(s): Easthom, Karl D.
• Application Number:
  US09/902,137
• Time in Patent Office: 273 Days
• Field of Search: 338/2, 338/4, 338/6, 338/47, 338/39, 338/114, 338/5, 738/624.74, 738/626.27
• US Class Current: 338/2
• CPC Class Codes: G01D 2205/77 Specific profiles
• CPC Class Codes: G01D 2205/775 Tapered profiles
• CPC Class Codes: G01D 5/04 using levers; using cams; using gearing
• CPC Class Codes: G01D 5/183 Sensing rotation or linear movement using strain, force or pressure sensors

Abstract

A linear position sensor for sensing the position of an attached object. The linear position sensor uses a strain gage to detect the position of the object. The sensor includes a housing and a ramp shaped actuator located in the housing. The actuator is attachable to the object. A strain gage is positioned in contact with the actuator. The actuator applies a strain to the strain gage as the actuator is moved. The strain gage generates an electrical signal that is proportional to the position of the object.

Claims

1. A linear position sensor for sensing the position of a linearly moving object, comprising:

a) a housing having a cavity;

b) a slot located in a first end of the housing;

c) an aperture located in a second end of the housing;

d) a sloping wedge shaped ramp located in the cavity, the ramp having a thick end and a thin end;

e) a shaft attached to the thick end of the ramp, the shaft extending through the aperture and attachable to the object, the shaft adapted to transmit linear motion from the object to the ramp such that the ramp moves in a linear manner within the cavity;

f) a strain gage in contact with the ramp, the strain gage having a substrate with a first and a second end and a surface, the first end of the substrate being in contact with the ramp, the second end of the substrate being retained within the slot;

g) four strain sensitive resistors mounted on the surface of the substrate and electrically connected to form a wheatstone bridge, the strain sensitive resistors generating an electrical signal that is proportional to the linear position of the object; and

h) a plurality of terminals mounted to the housing and electrically connected to the strain sensitive resistors.

2. The linear position sensor according to claim 1, wherein the strain increases on the substrate as the ramp moves from being in contact with the first end of the substrate at the thin end to being in contact with the thick end.