Contactless linear angular position sensor having an adjustable flux concentrator for sensitivity adjustment and temperature compensation

• US 5,332,965 A
• Filed: 06/22/1992
• Issued: 07/26/1994
• 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:
  US07/902,075
• Time in Patent Office: 764 Days
• Field of Search: 324/202, 324/207.12, 324/207.2, 324/207.21, 324/207.22, 324/207.25, 324/225, 324/173, 324/174, 324/235
• 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.

Claims

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

a housing;

a magnet 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 disposed adjacent said magnet for sensing the magnetic flux density generated by said magnet;

means for mechanically adjusting said sensing means;

means for carrying said sensing means at a predetermined fixed air gap relative to said magnet;

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

2. An angular position sensor as recited in claim 1, wherein said flux concentrator is formed from a plurality of materials defining one or more layers.

3. An angular position sensor as recited in claim 2, wherein said one or more of said layers are formed from a material whose permeability decreases at a different rate with increasing temperature relative to the other material layer.

4. An angular position senor as recited in claim 3, wherein said one or more of said layers are formed from an iron-nickel alloy.

5. An angular position sensor as recited in claim 2, wherein said one or more of said layers are formed from steel.

6. A method for adjusting the sensitivity of a throttle position sensor which includes a magnet and a magnetic sensing element, said throttle position sensor including a magnet, a magnetic sensing element, disposed a first predetermined distance from said magnet and a movably mounted flux concentrator, disposed a second predetermined distance from said magnet, said magnet and said magnetic sensing element being rotatably mounted relative to each other;

the method comprising the steps of;

a) varying said second predetermined distance until the desired sensitivity is attained without altering said first predetermined distance; and

b) securing said flux concentrator in place at the location of desired sensitivity.