Rotation angle detector

• US 6,738,725 B2
• Filed: 12/26/2002
• Issued: 05/18/2004
• Est. Priority Date: 12/28/2001
• Status: Expired due to Fees

• Current Assignee: Niles Parts Co., Ltd. (Valeo SE)
• Original Assignee: Niles Parts Co., Ltd. (Valeo SE)
• Inventors: Uno, Koji, Koga, Osamu, Kawamura, Yasuharu
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): LE, JOHN H
• Application Number:
  US10/327,853
• Publication Number:
  US 20030122542A1
• Time in Patent Office: 509 Days
• Field of Search: 702/41, 702/151, 701/37, 701/41, 701/57, 180/443, 180/444, 180/446, 324/86, 324/163, 324/207.14, 324/207.22, 324/207.25, 477/123
• US Class Current: 702/151
• CPC Class Codes: B62D 15/02 Steering position indicators ; Steering position determination; Steering aids
• CPC Class Codes: G01D 2205/26 Details of encoders or position sensors specially adapted to detect rotation beyond a full turn of 360°, e.g. multi-rotation
• CPC Class Codes: G01D 2205/28 The target being driven in rotation by additional gears
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01D 5/2452 incorporating two or more tracks having an (n, n+1, ...) relationship

Abstract

In the disclosure, MR sensors 6a and 6b for detecting the periodical angle position of rotating members rotating in conjunction with a steering wheel shaft are disposed in the vicinity of rotating members. These MR sensors are connected with a CPU 12, which makes the operation/processing of data from the MR sensors to calculate an absolute steering angle, including the indication of how many times the wheel has turned (periodicity). When the ignition key is turned off, the CPU 12 changes its operation mode into a stop mode of suspending said operation/processing, after storing the periodicity and the angle position γ of the rotating members in a flash memory. If any steering has been done during the stop mode to a degree that the output voltage of the MR sensor 6a exceeds the standard voltage V ref, the comparator 4'"'"'s output conditions change and the CPU temporarily releases the stop mode to calculate a value to correct the periodicity, using the angle positions at the start of stop mode and at its release, and correct the periodicity with this value.

Claims

1. A rotation angle detector comprising:

a rotating member rotating in conjunction with a body of rotation to be measured,

an angle sensor disposed in the vicinity of said rotating member to detect a periodical angle position thereof,

a non-volatile data memory for storing the standard position of said angle sensor,

an operation/control means that the performs operation/processing of the standard position and the detection data from the angle sensors to determine the periodicity of said rotating members, calculates an absolute rotation angle of said body of rotation to be measured to provide a detection output, and when a stop signal is received from outside, changes from a normal operation mode of continuously reading detection data from said angle sensors and performing the operation/processing thereof to stop mode of suspending said operation/processing, and

a rotation detection means to detect that said rotating members have rotated to a prescribed angle position during said stop mode;

wherein said operation/control means causes to store the values of angle position and periodicity of said rotating member at the time point when the stop mode is switched to, temporarily releases said stop mode by an output signal received from said rotation detection means, determines a value to correct the periodicity of said rotating member based on the change of angle position of said rotating member taking place during a period from the start of said stop mode to its release and uses this value for correction, and

wherein during the normal operation mode the ignition switch is on and during the stop mode the ignition switch is off.

2. A rotation angle detector according to claim 1, wherein said rotation detection means is a comparator that receives an output signal from said angle sensor.

3. A rotation angle detector according to claim 2, wherein a hysteresis is set up in the output from said comparator.

4. A rotation angle detector according to claim 1, 2 or 3, wherein the power voltage supplied to said angle sensors is set up at a low level during said stop mode.