Mechanically adjustable linear-output angular position sensor

• US 5,497,081 A
• Filed: 04/28/1993
• Issued: 03/05/1996
• Est. Priority Date: 06/22/1992
• Status: Expired due to Term

• Current Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Original Assignee: Durakool, Inc.
• Inventors: Wolf, Ronald J., Hedeen, Larry
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US08/051,412
• Time in Patent Office: 1,042 Days
• Field of Search: 324/202, 324/207.12, 324/207.2, 324/207.21, 324/207.22, 324/207.25, 324/225, 324/235, 324/173, 324/174, 338/32 R, 338/32 H
• US Class Current: 324/207.12
• CPC Class Codes: G01D 3/02 with provision for altering or correcting the law of variation
• CPC Class Codes: G01D 3/0365 the undesired influence being measured using a separate sensor, which produces an influence related signal
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

An angular position sensor for sensing the angular position of a pivotally mounted device includes a magnetically sensitive device, such as a Hall effect IC, and a plurality of flux concentrators, rigidly disposed relative to the Hall effect IC, forming an assembly. The assembly is disposed in a housing a fixed distance from a rotatably mounted standard magnet defining a fixed air gap therebetween. The magnet is disposed in rotatably mounted magnet holder which also acts as a drive arm that is adapted to be mechanically coupled to a pivotally mounted device. The configuration of the flux concentrators assembled to the magnetically sensitive device cause the output of the Hall effect IC to be generally linear. In order to avoid problems associated with electrically adjustable angular position sensors, the angular position sensor in accordance with the present invention is adjusted mechanically. In particular, a flux concentrator, preferably having a halo shape, is disposed adjacent the magnet. The sensor is calibrated by varying the distance between the halo-shaped flux concentrator and the magnet. In one embodiment of the invention, the halo-shaped flux concentrator is formed to provide temperature compensation for the sensor. The sensor is hermetically sealed and is thus unaffected by wear or vibration. In an alternative embodiment, a circular magnet with a central aperture is utilized. In order to reduce the overall length of the sensor, the magnetic sensing element is disposed within the central aperture.

Claims

1. An angular position sensor for sensing the angular position of a pivotally mounted device about a predetermined pivot axis comprising:

a housing;

means for providing a mechanical coupling to said pivotally mounted device, rotatably mounted relative to said housing;

a magnet having north and south magnetic poles;

means responsive to said providing means for generating an electrical signal representative of the angular position of said pivotally mounted device;

said generating means being at least partially disposed between said north and south poles of said magnet; and

means for mechanically adjusting the sensitivity of said generating means, wherein said adjusting means includes a flux concentrator and means for carrying said flux concentrator a predetermined distance relative to said generating means.

2. An angular position sensor as recited in claim 1, wherein said additional flux concentrator is formed as a generally halo-shaped flux concentrator with a generally, centrally disposed aperture.

3. An angular position sensor as recited in claim 1, wherein said flux concentrator carrying means includes means for enabling the distance between said flux concentrator and said generating means to be varied.

4. An angular position sensor for sensing the angular position of a pivotally mounted device comprising:

a housing

a circular magnet with a central aperture for generating magnetic flux defining a magnetic axis through opposing North and South magnetic poles;

a drive arm, rotatably carried relative to said housing, said drive arm including means for providing a mechanical coupling to said pivotally mounted device and means for carrying said magnet;

means at least partially disposed within said central aperture of said magnet for sensing the magnetic flux density generated by said magnet;

means for mechanically adjusting said sensing means; and

means for providing temperature compensation for said sensor, wherein said temperature compensation providing means includes a flux concentrator.

5. An angular position sensor for sensing the angular position of a pivotally mounted device about a predetermined pivot axis, said sensor comprising:

a housing for rotatably carrying said pivotally mounted device about said predetermined pivot axis;

means for providing magnetic signals that vary as a function of the angular position of said pivotally mounted device including a magnet having north and south magnetic poles defining one or more magnetic axes therethrough;

means responsive to said magnetic signals for generating electrical signals representative of said angular position of said pivotally mounted device, said generating means having a predetermined offset voltage when said sensing plane is generally aligned with said magnetic axis, said generating means including a sensing plane, spaced away from said providing means defining a predetermined air gap;

sensitivity adjustment means for mechanically adjusting the sensitivity of said generating means; and

offset voltage adjustment means for mechanically adjusting the offset voltage of said generating means.

11. An angular position sensor as recited in claim 5 wherein said offset voltage adjustment means includes means for varying the angle between said magnetic axis and said sensing plane.

6. An angular position sensor for sensing the angular position of a pivotally mounted device mounted in a predetermined housing about a predetermined pivot axis, said sensor comprising:

a sensor housing adapted to be mechanically coupled to said predetermined housing, said housing including means for enabling rotatable coupling said pivotally mounted device in said predetermined housing;

means for providing magnetic signals that vary as a function of the angular position of said pivotally mounted device including means for providing a mechanical coupling to said pivotally mounted device and a magnet having north and south magnetic poles defining one or more magnetic axes therethrough;

means responsive to said magnetic signals for generating electrical signals representative of said angular position of said pivotally mounted device, said generating means having a predetermined offset voltage when said sensing plane is generally aligned with said magnetic axis;

said generating means including a sensing plane spaced away from said providing means defining a predetermined substantially constant air gap; and

sensitivity adjustment means for mechanically adjusting the sensitivity of said generating means wherein said sensitivity adjustment means includes a predetermined flux concentrator and means for carrying said predetermined flux concentrator relative to said magnet to enable the distance between said magnet and said predetermined flux concentrator to be varied to enable the sensitivity of said means to be adjusted.

7. An angular position sensor as recited in claim 6 wherein said predetermined flux concentrator is configured in a halo shape having a centrally disposed aperture.

8. An angular position sensor for sensing the angular position of a pivotally mounted device mounted in a predetermined housing about a predetermined pivot axis, said sensor comprising:

a sensor housing adapted to be mechanically coupled to said predetermined housing, said housing including means for enabling rotatable coupling said pivotally mounted device in said predetermined housing;

means for providing magnetic signals that vary as a function of the angular position of said pivotally mounted device including means for providing a mechanical coupling to said pivotally mounted device and a magnet having north and south magnetic poles defining one or more magnetic axes therethrough;

means responsive to said magnetic signals for generating electrical signals representative of said angular position of said pivotally mounted device, said generating means having a predetermined offset voltage when said sensing plane is generally aligned with said magnetic axis;

said generating means including a sensing plane, spaced away from said providing means defining a predetermined substantially constant air gap; and

sensitivity adjustment means for mechanically adjusting the sensitivity of said generating means wherein said magnet is a bar magnet.

9. An angular position sensor for sensing the angular position of a pivotally mounted device about a predetermined pivot axis, said sensor comprising:

a housing for rotatably carrying said pivotally mounted device about said predetermined pivot axis;

means for providing magnetic signals that vary as a function of the angular position of said pivotally mounted device including a magnet having north and south magnetic poles defining one or more magnetic axes therethrough;

means responsive to said magnetic signals for generating electrical signals representative of said angular position of said pivotally mounted device, said generating means including a sensing plane spaced away from said providing means defining a predetermined air gap;

said generating means having a predetermined offset voltage when said sensing plane is generally aligned with said magnetic axis;

sensitivity adjustment means for mechanically adjusting the sensitivity of said generating means; and

means for linearizing the output signal of said generating means, wherein said linearizing means includes one or more flux concentrators.

10. An angular position sensor as recited in claim 9 wherein said one or more flux concentrators are generally L shaped.

12. An angular position sensor for sensing the angular position of a pivotally mounted device, said sensor comprising:

a housing for rotatably carrying said pivotally mounted device about said predetermined pivot axis;

means for providing magnetic signals that vary as a function of the angular position of said pivotally mounted device including a magnet having opposing north and south magnetic poles defining one or more magnetic axes therethrough;

means responsive to said magnetic signals for generating electrical signals representative of the angular position of said pivotally mounted device, including a Hall effect device having a predetermined sensing plane, sensing plane disposed coaxially with respect to said predetermined pivot axis; and

means for linearizing the output signals from said generating means, wherein said linearizing means includes one or more flux concentrators.