Non-contact system for detecting an angle of rotation

• US 6,212,783 B1
• Filed: 12/31/1998
• Issued: 04/10/2001
• Est. Priority Date: 05/27/1997
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Ott, Karl, Lehner, Michael
• Primary Examiner(s): Bennett, G. Bradley
• Assistant Examiner(s): VERBITSKY, GAIL KAPLAN
• Application Number:
  US09/214,249
• Time in Patent Office: 831 Days
• Field of Search: 33/1.PT, 324/207.25, 324/207.2, 324/207.4, 338/32.H, 338/32.R
• US Class Current: 33/1.0PT
• CPC Class Codes: F02P 7/067 Electromagnetic pick-up devices , e.g. providing induced current in a coil
• CPC Class Codes: F02P 7/07 Hall-effect pick-up devices
• CPC Class Codes: G01B 7/30 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

The arrangement for contactless determination of an angular position of a rotatable element, such as a camshaft of an internal combustion engine, which includes a magnet arranged to rotate with the rotatable element; a magnetic field sensor stationary in relation to the rotatable element and including a first sensor element (IC1) and a second sensor element (IC2), wherein the first sensor element generates a first output signal linearly dependent on an angle between the magnetic field and the magnetic field sensor according to a magnetoresistive effect, whereby the first output signal has respective values between 0° and 180° that repeat between 180° and 360°, and the second sensor element generates a second output signal having a high value between 0° and 180° and a low value between 180° and 360° according to a Hall effect; and an evaluation circuit (A) for analyzing output signals of both sensor elements to determine the angular position of the rotatable element between 0° and 360°. The evaluating circuit finds that the absolute angular position is either of two angular orientations spaced 180° from each other only from the signal from the first sensor element and selects one of them as the absolute angular position according to the second output signal.

Claims

1. An arrangement for contactless determination of an absolute angular position of a rotatable element between 0°

and 360°

, said arrangement comprising

means for generating a magnetic field comprising at least one magnetic field-producing element arranged to rotate with said rotatable element;

a magnetic field sensor stationary in relation to said rotatable element and arranged to detect said magnetic field, said magnetic field sensor including a first sensor element (IC1) and a second sensor element (IC2), wherein said first sensor element operates according to a magnetoresistive effect so as to generate a first output signal linearly dependent on an angle between said magnetic field and said magnetic field sensor, whereby said first output signal has respective values when said angle is between 0° and

180°

that repeat when said angle is between 180° and

360°

, said second sensor element operates according to a Hall effect to generate a second output signal which has a high value when said angle is between 0° and

180° and

a low value when said angle is between 180° and

360°

; and

an evaluation circuit (A) comprising means for evaluating said first output signal and said second output signal in order to determine said absolute angular position of said rotatable element between 0° and

360°

.

2. The arrangement as defined in claim 1, wherein said first sensor element and said second sensor element are mounted on a sensor mount in a fixed relationship to each other and oriented at an angle of approximately 90°

to each other.

3. The arrangement as defined in claim 1, wherein said first sensor element and said second sensor element are arranged so that magnetic field lines of said magnetic field are oriented approximately parallel to said first sensor element and perpendicularly penetrate said second sensor element.

4. The arrangement as defined in claim 1, wherein said rotatable element is a rotatable shaft of an internal combustion engine.

5. The arrangement as defined in claim 4, wherein said rotatable shaft is a camshaft.

6. The arrangement as defined in claim 1, wherein said rotatable element is a camshaft of an internal combustion engine, said camshaft is connected with pistons of said internal combustion engine and said sensor elements are mounted so that said angle is at 0°

, 180° and

360°

when said pistons are at top dead center points of the internal combustion engine.

7. An arrangement for contactless determination of an absolute angular position of a rotatable element between 0°

and 360°

, said arrangement comprising

means for generating a magnetic field comprising at least one magnetic field-producing element arranged to rotate with said rotatable element;

a magnetic field sensor stationary in relation to said rotatable element and arranged to detect said magnetic field, said magnetic field sensor including a first sensor element (IC1) and a second sensor element (IC2), wherein said first sensor element operates according to a magnetoresistive effect so as to generate a first output signal linearly dependent on an angle between said magnetic field and said magnetic field sensor, whereby said first output signal has respective values when said angle is between 0° and

180°

that repeat when said angle is between 180° and

360°

, said second sensor element operates according to a Hall effect to generate a second output signal which has a high value when said angle is between 0° and

180° and

a low value when said angle is between 180° and

360°

; and

an evaluation circuit (A) comprising means for evaluating said first output signal and said second output signal in order to determine said absolute angular position of said rotatable element between 0° and

360°

, wherein said means for evaluating includes means for determining two angular orientations spaced 180°

from each other from only said first output signal of said first sensor element and means for selecting one of said two angular orientations as said absolute angular position of said rotatable element according to said second output signal of said second sensor element.