Linear position sensor

• US 5,642,043 A
• Filed: 07/31/1996
• Issued: 06/24/1997
• Est. Priority Date: 01/11/1989
• Status: Expired due to Term

• Current Assignee: Uusi LLC (Nartron Corporation)
• Original Assignee: Nartron Corporation
• Inventors: Ko, Clyde, Munch, Carl, Shank, David, Strom, Peter H.
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US08/690,029
• Time in Patent Office: 328 Days
• Field of Search: 324/207.13, 324/207.15, 324/207.16, 324/207.17, 324/207.22, 324/207.24, 324/225, 324/226, 324/239, 324/262, 340/870.31, 340/870.32, 340/870.33, 340/870.34, 340/870.35, 340/870.36, 336/30, 336/45, 336/73, 336/75, 336/77, 336/84 R, 336/130, 336/132, 336/133, 336/136
• US Class Current: 324/207.24
• CPC Class Codes: B60G 17/01933 Velocity, e.g. relative velocity-displacement sensors
• CPC Class Codes: B60G 2204/111 on pneumatic springs
• CPC Class Codes: B60G 2204/112 on dampers, e.g. fluid dampers
• CPC Class Codes: B60G 2400/202 Piston speed; Relative velocity between vehicle body and wheel
• CPC Class Codes: B60G 2400/25 Stroke; Height; Displacement
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2401/17 Magnetic/Electromagnetic
• CPC Class Codes: F15B 15/2861 using magnetic means
• CPC Class Codes: G01D 5/2046 by a movable ferromagnetic element, e.g. a core
• CPC Class Codes: G01D 5/2053 by a movable non-ferromagnetic conductive element

Abstract

A linear position sensor includes coextensively positioned primary and secondary windings, each having an elongated core and a coil radially spaced around the core. A cyclically varying signal is applied to the primary winding which develops a signal across the secondary winding due to transformer coupling. A coupling adjustment member varies the amount of transformer coupling and is longitudinally movable with respect to the winding assembly. The relative longitudinal positioning of the coupling member with respect to the winding assembly is determined by measuring the signal developed across the secondary winding. In one embodiment, the windings are similarly configured, are arranged side-by-side and spaced apart; the coupling adjustment member enhances the transformer coupling between the windings which are telescopingly received within the member. In another embodiment, one winding is concentrically positioned within the other and the coupling adjustment member disrupts the transformer coupling between the windings by being positionable in a gap between the windings. Embodiments are illustrated both for location internal to, and external of, a vehicle shock absorber.

Claims

1. A position sensor for providing a signal indicative of the relative position of movable members comprising:

an elongated sensor housing supporting an elongated sensor having a conductive coil that is radially wound about an axis and that extends through a length of the elongated sensor housing;

an elongated coupling member having an outer surface that is sized for insertion and slidable movement within the elongated sensor housing to slide in and out of the sensor housing over a range of travel along the elongate dimension of the sensor housing, and to overlap a variable portion of the elongated sensor contained in the sensor housing;

a control module housing electronically coupled to the elongated sensor housing, said control module containing a sensor control module having i) a signal generator for electrically energizing the conductive coil with an alternating sensor energization signal to create a magnetic field in a region of the conductive coil of said elongated sensor and ii) an output circuit electrically coupled to the elongated sensor for converting an alternating output from the elongated position sensor into an analog position signal output that is functionally related to an extent of overlap of the coupling member with the elongated sensor as the elongated coupling member intercepts the magnetic field set up by energization of the conductive coil;

a generally tubular shaped flexible boot with one end sealingly joined around an outer surface of one end of the coupling member and the other end of the boot sealingly joined around an outer surface of the elongated sensor housing;

a first mounting fixture joined to an end of the elongated sensor housing spaced from the flexible boot having a socket that is designed to mount one end of said position sensor onto one movable member adapted to receive the first fixture;

a second mounting fixture joined to a non-insertion end of the coupling member having a socket that is designed to mount the other end of said position sensor onto another movable member adapted to receive the second fixture; and

a wire harness coupled to the sensor control module housing including conductors for energizing the signal generator of the sensor control module and routing the analog position output signal away from the control module housing.

2. The position sensor of claim 1 where said sensor control module comprises circuitry that senses the depth of insertion of said coupling member into said elongated sensor housing and thereby deduces the degree of separation between said first and second mounting fixtures and wherein the wire harness comprises a conductor for transmitting an output signal related to the depth of insertion.

3. The position sensor of claim 1 where said elongated coupling member is a tube comprised of aluminum.

4. The position sensor of claim 1 where each of said first and second mounting fixtures comprises a split spherical socket having an entry opening that has a diameter smaller than an internal diameter of the split spherical socket.

5. The position sensor of claim 1 where each of said first and second mounting fixtures comprises a split spherical socket having an entry opening that has a diameter smaller than the internal diameter of the split spherical socket and

where said socket is composed of a rigid but elastic material such as plastic to allow said socket opening to stretch and widen the opening and then reforms to its unstretched state.

6. The position sensor of claim 1 where said elongated coupling member comprises a polymeric support tube coupled to said second mounting fixture that overlies a nonferrous metal coupling member.

7. The position sensor of claim 1 wherein said sensor control module is encapsulated in said control module housing in a material that inhibits moisture from contacting said sensor control module.

8. The position sensor of claim 1 further including damping means for sealingly joining one end of the flexible boot around the outer surface of one end of the elongated coupling member and sealingly joining the other end of the flexible boot around an outer surface of the elongated sensor housing.

9. The position sensor of claim 8 wherein the clamping means for at least one end of the flexible boot includes an annular band overlying and exerting pressure on a circumferential portion of the flexible boot at or near the end of the boot.

10. The position sensor of claim 9 wherein the clamping means further includes at least one of the elongated sensor housing and elongated coupling member having one or more raised annular ridges on its outer surface, the ridges engaging and exerting pressure on inner circumferential portions of the flexible boot overlying the ridges.

11. The position sensor of claim 1 further including structure defining one or more apertures in fluid communication with an interior region enclosed by the flexible boot as the coupling tube slides in and out of the sensor housing.

12. The position sensor of claim 1 further including structure defining one or more apertures in fluid communication with an interior region enclosed by the flexible boot for equalizing pressure as the coupling member slides in and out of the elongated sensor housing and further including clamping means for sealingly joining one end of the flexible boot around the circumference of one end of the coupling member and sealingly joining the other end of the flexible boot around the surface of the elongated sensor housing and wherein the clamping means for at least one end of the flexible boot includes an annular band overlying and exerting pressure on a circumferential portion of the flexible boot at or near the end of the boot.

13. The position sensor of claim 1 further including structure defining one or more apertures in fluid communication with an interior region enclosed by the flexible boot for equalizing pressure as the coupling member slides in and out of the elongated sensor housing and further including clamping means for sealingly joining one end of the flexible boot around the circumference of one end of the coupling member and sealingly joining the other end of the flexible boot around the surface of the elongated sensor housing and wherein the clamping means for at least one end of the flexible boot includes an annular band overlying and exerting pressure on a circumferential portion of the flexible boot at or near the end of the boot and further wherein at least one of the elongated sensor housing and coupling member includes one or more raised annular ridges on its outer circumference, the ridges engaging and exerting pressure on inner circumferential portions of the flexible boot overlying the ridges.

14. A position sensor for providing a signal indicative of the relative position of movable members comprising:

an elongated sensor housing supporting an elongated sensor having a conductive coil that is radially wound about an axis and that extends through a length of the elongated sensor housing;

an elongated coupling member having an outer surface that is sized for insertion and slidable movement within the elongated sensor housing to slide in and out of the sensor housing over a range of travel along the elongate dimension of the sensor housing, and to overlap a variable portion of the elongated sensor contained in the sensor housing;

a sensor control module housing containing a sensor control module having i) a signal generator for electrically energizing the conductive coil with an alternating sensor energization signal to create a magnetic field in a region of the conductive coil and ii) an output circuit electrically coupled to the elongated sensor for converting an alternating output from the elongated position sensor into an analog position signal output that is functionally related to an extent of overlap of the coupling member with the elongated sensor as the elongated coupling member intercepts the magnetic field set up by energization of the conductive coil;

a generally tubular shaped flexible boot with one end sealingly joined around an outer surface of one end of the coupling member and the other end of the boot sealingly joined around an outer surface of the elongated sensor housing;

a first mounting fixture joined to an end of the elongated sensor housing spaced from the flexible boot having a socket that is designed to mount one end of said position sensor onto one movable member adapted to receive the first fixture;

a second mounting fixture joined to a non-insertion end of the coupling member having a socket that is designed to mount the other end of said position sensor onto another movable member adapted to receive the second fixture; and

a wire harness for energizing the signal generator of the sensor control module and routing the analog position output signal from the output circuit away from the control module housing;

said position sensor including structure defining one or more apertures in fluid communication with an interior region enclosed by the flexible boot as the coupling member slides in and out of the sensor housing.

15. The position sensor of claim 14, further including damping means for sealingly joining one end of the flexible boot around the circumference of one end of the coupling member and sealingly joining the other end of the flexible boot around the surface of the elongated sensor housing and wherein the clamping means for at least one end of the flexible boot includes an annular band overlying and exerting pressure on a circumferential portion of the flexible boot at or near the end of the boot.

16. A position sensor for providing a signal indicative of the relative position of movable members comprising:

an elongated sensor housing supporting an elongated sensor having a conductive coil that extends through a length of the elongated sensor housing;

an elongated coupling member having an outer surface that is sized for insertion and slidable movement within the elongated sensor housing to slide in and out of the sensor housing over a range of travel along the elongate dimension of the sensor housing, and to overlap a variable portion of the elongated sensor contained in the sensor housing;

a control module housing electrically coupled to the elongated sensor housing that supports a sensor control module having i) a signal generator for electrically energizing the conductive coil with an alternating sensor energization signal to create a magnetic field in a region of the conductive coil and ii) an output circuit electrically coupled to the elongated sensor for converting an alternating output from the elongated position sensor into an analog position signal output that is functionally related to an extent of overlap of the coupling member with the elongated sensor as the elongated coupling member intercepts the magnetic field set up by energization of the conductive coil;

a generally tubular shaped flexible boot with one end sealingly joined around an outer surface of one end of the coupling member and the other end of the boot sealingly joined around an outer surface of the elongated sensor housing;

a first mounting fixture joined to an end of the elongated sensor housing spaced from the flexible boot having a socket that is designed to mount one end of said position sensor onto one movable member adapted to receive the first fixture;

a second mounting fixture joined to a non-insertion end of the coupling member having a socket that is designed to mount the other end of said position sensor onto another movable member adapted to receive the second fixture; and

a wire harness coupled to the sensor control module housing including conductors for energizing the signal generator of the sensor control module and routing the analog position output signal away from the control module housing.