Inductive coupling position sensor method and apparatus having primary and secondary windings parallel to each other

• US 5,036,275 A
• Filed: 10/26/1989
• Issued: 07/30/1991
• Est. Priority Date: 01/11/1989
• Status: Expired due to Term

• Current Assignee: Nartron Corporation
• Original Assignee: Nartron Corporation
• Inventors: Munch, Carl A., Cooper, Stephen R. W., Rymut, Michael J.
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US07/427,641
• Time in Patent Office: 642 Days
• Field of Search: 324/207, 324/208, 324/225, 324/226, 324/262, 324/207.11, 324/207.15, 324/207.16, 324/207.17, 324/207.22, 324/207.23, 324/207.24, 324/207.25 , 324/207.26, 340/870.31, 340/870.32, 340/870.33, 340/870.34, 340/870.35, 340/87.36, 336/30, 336/45, 336/73, 336/75, 336/77, 336/84 R, 336/130, 336/132, 336/133, 336/136
• US Class Current: 324/207.17
• 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: 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 position sensing device including two spaced conductive coils constituting a primary and secondary winding of a transformer. A coupling member is mounted to a moveable object such as an automobile steering mechanism and moves relative the primary and secondary windings. This movement adjusts or alters the transformer coupling between the primary and the secondary and produces a variable output signal which can be correlated through use of appropriate circuitry to the position of the moveable member. Two alternate designs are disclosed. In a first design, the transformer primary and secondary are disposed side-by-side and the coupling member slips over the primary and secondary for relative linear movement. In a second design, the primary and secondary are disposed one within the other and the coupling member fits within a gap between the primary and secondary.

Claims

1. Position sensing apparatus for monitoring a relative position between two relatively moveable members comprising:

(a) an elongated field producing member coupled to a first of said moveable members and including a first multiturn conductor wound about a field producing member axis having a first controlled turn density, and an input for energizing the first multiturn conductor to produce an electromagnetic field in the vicinity of the field producing member;

(b) an elongated field responsive member fixed with respect to the field producing member including a second multiturn conductor wound about a field responsive member axis having a second controlled turn density, said elongated field responsive member oriented in side by side, generally parallel orientation to the elongated field producing member along a length of the field producing member, and having an output for providing an output signal in response to the electromagnetic field produced by the field producing member;

(c) a coupling member connected to a second of the moveable members for movement with the second moveable member and positioned relative the field producing and field responsive members to alter the response of the field responsive member as the moveable members move relative to each other and thereby change the signal at the output of the field responsive member;

(d) exciter means coupled to the input for energizing the field producing member; and

(e) circuit means coupled to the output from the field responsive member to correlate changes in the output signal with relative movement of the moveable members. muliturn conductor to produce an electromagnetic field in the vicinity of the field producing member;

(b) an elongated field responsive member fixed with respect to the field producing member including a second multiturn conductor wound about a field responsive member axis having a second controlled turn density, said elongated field responsive member oriented in side by side, generally parallel orientation to the elongated field producing member along a length of the field producing member, and having an output for providing an output signal in response to the electromagnetic field produced by the field producing member;

(c) a coupling member connected to a second of the moveable members for movement with the second moveable member and positioned relative the field producing and field responsive members to alter the response of the field responsive member as the moveable members move relative to each other and thereby change the signal at the output of the field responsive member;

(d) exciter means coupled to the input for energizing the field producing member; and

(e) circuit means coupled to the output from the field responsive member to correlate changes in the output signal with relative movement of the moveable member.

2. The apparatus of claim 1, wherein the multiturn conductors are deposited onto a magnetically permeable form.

3. The apparatus of claim 1 wherein the field producing and field responsive members are etched from a conductive layer supported by a magnetically permeable form.

4. The apparatus of claim 1 wherein the coupling means comprises an electrically conductive material.

5. The apparatus of claim 4 wherein the coupling means comprises a multi-turn coil arranged spirally around a form having a controlled turn density to form an elongated member.

6. The apparatus of claim 1 wherein the coupling means comprises a magnetically permeable material.

7. The apparatus of claim 1 wherein both the field producing and field responsive- members are elongated linear or curvilinear members disposed side by side in a direction generally parallel to a travel path followed by the moveable member.

8. The apparatus of claim 1 wherein the coupling member has a short length relative the length of the field producing and field responsive members.

9. The apparatus of claim 1 wherein the coupling member is an annular conductor having a length shorter than the elongated linear members and connected to the moveable member for movement along a travel path parallel to the elongated linear members in overlapping relation.

24. The position sensing apparatus of claim 1 wherein the coupling member comprises a passageway defining member having a controlled shape or wall thickness along its length.

10. A method of monitoring first and second relatively moveable members comprising the steps of:

(a) winding elongated conductors to form primary and secondary transformer windings having controlled turn densities along a length of primary and secondary axes that are relatively spaced from each other and connecting the primary and secondary transformer windings to a first of the relatively moveable members;

(b) supporting a transformer coupling member for movement along a tracking path that parallels the primary and secondary axes by connecting said coupling member to the second relatively moveable member;

(c) energizing the transformer primary winding with an external energy source; and

(d) monitoring an output from the secondary winding as the first and second relatively moveable members move in relation to each other; and

(e) correlating an output signal from the secondary winding with a relative position of said first and second relatively moveable members.

11. The method of claim 10 wherein the primary and/or secondary turn density is controlled to produce a specified amplitude versus position signal output.

12. The method of claim 10 wherein the coupling member has a relatively short extent compared to the primary and secondary transform windings.

13. The method of claim 10 where the primary and secondary transformer conductor turns are arranged with a controlled non-uniform density around a magnetically permeable core.

14. The method of claim 10 where the primary and secondary transformer conductor turns are arranged with a controlled turn density around a variable cross section magnetically permeable core.

15. The method of claim 10 where the windings are deposited or etched in a controlled pattern around a magnetically permeable core.

16. The method of claim 10 where the coupling member comprises a passageway defining member having a controlled shape or wall thickness along its length.

17. A position sensor, comprising:

(a) a primary winding having a first core and a conductor wound around said first core including a multiplicity of turns spaced along at least a portion of a length of said first core;

(b) a secondary winding having a second core and a second conductor wound around said second core including a multiplicity of turns spaced along at least a portion of a length of said second core;

(c) said secondary winding positioned adjacent said primary winding, in a spaced, transformer coupling relationship with the first and second cores in side by side, non-coaxial relation and attached to a first of two relatively positioned members; and

(d) coupling means moveable with a second of said two relatively positioned members to overlie at lest one of the primary and secondary windings and vary the transformer coupling between said windings as the two relatively positioned members move with respect to each other.

18. The position sensor of claim 17, wherein said primary and secondary windings are coextensive and substantially parallel.

19. The position sensor of claim 18, wherein said coupling means comprises a tubular member sized to receive said primary and secondary windings and moveable relative to said windings.

20. The apparatus of claim 18, wherein said tubular member has an axial extent less than a longitudinally extent of said primary and said secondary windings.

21. The position sensor of claim 18, wherein said tubular member has an axial extent sized to receive a substantial portion of said primary and secondary windings.

25. THe position sensor of claim 17 wherein the coupling means comprises a passageway defining member having a controlled shape or wall thickness along its length to uniquely define a secondary response as the relative position of the coupling means with respect to the primary and secondary change.

22. A sensor apparatus for monitoring a position of a wheel assembly member relative to a vehicle chassis portion, comprising:

(a) an elongated field producing member having a conductive coil wound about a field producing axis and an input for energizing the coil to produce an electromagnetic field in the vicinity of the field producing member;

(b) an elongated field responsive member fixed with respect to the field producing member having a conductive coil wound about a field responsive axis oriented generally parallel and spaced from the field producing axis along a length of the field producing member, and having an output for providing an output signal in response to the electromagnetic field produced by the field producing member, said field producing and field responsive members connected to said chassis portion;

(c) a coupling member connected to the wheel assembly member for movement with the wheel assembly member and positioned relative to the field producing and field responsive members to alter the response of the field responsive member as the wheel assembly member moves and thereby change the signal at the output of the field responsive member;

(d) exciter means coupled to the input for energizing the field producing member; and

(e) circuit means coupled to the output from the field responsive member to correlate changes in the output signal with movement of the wheel assembly member.

23. A sensor apparatus for monitoring a position of a wheel assembly member relative to a vehicle chassis portion, comprising:

(a) an elongated field producing member having a conductive coil wound about a field producing axis and an input for energizing the coil to produce an electromagnetic field in the vicinity of the field producing member;

(b) an elongated field responsive member fixed with respect to the field producing member having a conductive coil wound about a field responsive axis oriented generally parallel and spaced from the field producing axis along a length of the field producing member, and having an output for providing an output signal in response to the electromagnetic field produced by the field producing member, said field producing and field responsive members connected to said wheel assembly member;

(c) a coupling member connected to the chassis portion for movement with the chassis portion and positioned relative the field producing and field responsive members to alter the response of the field responsive member as the wheel assembly member moves and thereby change the signal at the output of the field responsive member;

(d) exciter means coupled to the input for energizing the field producing member; and

(e) circuit means coupled to the output from the field responsive member to correlate changes in the output signal with movement of the wheel assembly member.

26. A method of monitoring first and second relatively moveable members comprising the steps of:

(a) winding first and second elongated conductors to form primary and secondary transformer windings having controlled turn densities along a length of primary and secondary axes and connecting the primary and secondary transformer windings to a first of the relatively moveable members;

(b) supporting a transformer coupling member for movement along a tracking path that parallels the primary and secondary axes by connecting said coupling member to the second relatively moveable member;

(c) energizing the transformer primary winding with an external energy source; and

(d) monitoring an output from the secondary winding as the first and second relatively moveable members move in relation to each other; and

(e) correlating an output signal from the secondary winding with a relative position of said first and second relatively moveable members;

(f) said winding step performed by varying the turn density of the windings of both the primary and the secondary windings to provide an output signal from the secondary winding that is functionally dependent on the relative position of the first and second moveable members.

27. A position sensor, comprising:

(a) a primary winding having a first core and a conductor wound around said first core including a multiplicity of turns spaced along at least a portion of a length of said first core;

(b) a secondary winding having a second core and a second conductor wound around said second core including a multiplicity of turns spaced along at least a portion of a length of said second core;

(c) said secondary winding positioned in a spaced, generally co-axial transformer coupling relationship with the primary winding with both said primary and secondary windings attached to a first of two relatively positioned members; and

(d) coupling means moveable with a second of said two relatively positioned members to overlie at least one of the primary and secondary windings and vary the transformer coupling between said windings as the two relatively positioned members move with respect to each other;

(e) said primary and secondary windings having controlled turn densities along both their lengths to provide an output signal from the secondary winding that is functionally dependent on the relative position of the two relatively positioned members.