Rotational angel detector

Information

  • Patent Application
  • 20070229062
  • Publication Number
    20070229062
  • Date Filed
    March 30, 2007
    17 years ago
  • Date Published
    October 04, 2007
    17 years ago
Abstract
A small-sized rotational angle detector can output both the absolute rotational angle α including the frequency of the steering shaft and the relative rotational angle signal. The amount of change of the absolute rotational angle is calculated on a sampling-period basis. A transition interval is determined based on the sampling period and the amount of change of the absolute rotational angle. Based on the preset pulse pattern, A-phase, B-phase and Z-phase pulses transitioning at the transition intervals are generated. Assuming that the amount of change of the absolute rotational angle in the sampling period of 10 ms is 2°, 2.5 ms obtained by dividing the sampling period 10 ms by the range of change 4 converted based on a predetermined unit 0.5° of the absolute rotational angle region, is defined as a pulse transition interval. The pulses are outputted as a relative rotational angle signal. Unnecessity of large-diameter disk having slits enables reducing the size of the entire detector and enhancing the degree of shape freedom.
Description

BRIEF EXPLANATION OF THE DRAWINGS

Referring now to the attached drawings which form a part of this original disclosure:



FIGS. 1A and 1B are diagrams illustrating the layout of an angle sensor unit in an embodiment of the present invention;



FIG. 2 is a block diagram illustrating the overall structure of a rotational angle detector;



FIG. 3 is a diagram showing an example of a table used for generating a relative rotational angle signal;



FIG. 4 is a flowchart showing the flow of calculation processing;



FIG. 5 is a chart showing the relationship between angular positions of a driven gear and input to an electron control unit;



FIG. 6 is a chart showing the pulse generation based on the table.



FIG. 7 is a diagram illustrating a conventional example; and



FIG. 8 is a chart showing the pulse pattern of a relative rotational angle signal.


Claims
  • 1. A rotational angle detector equipped with an absolute rotational angle detecting means for detecting an absolute rotational angle including a frequency of a measured rotational element to output the absolute rotational angle, comprising: a rotational-angle change-amount calculating means for calculating the amount of change of the absolute rotational angle from one sampling period to another;a transition-interval setting means for setting a transition interval on the basis of the sampling period and the amount of change of the absolute rotational angle; anda pulse generating means for generating pulses transitioning in order at the transition intervals in accordance with the change of the absolute rotational angle in the sampling period on the basis of a pulse pattern present in correspondence with each predetermined-unit region of the absolute rotational angle,wherein the pulses thus generated are outputted as a relative rotational-angle signal.
  • 2. The rotational angle detector according to claim 1, further comprising a table containing table values respectively assigned to the predetermined-unit regions of the absolute rotational angle, and pulse data on the pulse pattern set in correspondence with each of the table values, wherein the transition-interval setting unit defines as the transition-interval setting unit defines as the transition interval a value obtained by dividing the sampling period by the number of table values corresponding to the amount of change of the absolute rotational angle in the table.
  • 3. The rotational angle detector according to claim 1, wherein the pulse pattern includes pulse trains of two phase pulses separated in phase by one quarter period from each other.
  • 4. The rotational angle detector according to claim 1, wherein the absolute rotational-angle detecting unit comprises an MR sensor provided a rotational member rotating in association with the measured rotational element for detecting a periodic angular position, and performs calculation processing on output of the MR sensor to detect the absolute rotational angle.
  • 5. The rotational angle detector according to claim 2, wherein the pulse pattern includes pulse trains of two phase pulses separated in phase by one quarter period from each other.
  • 6. The rotational angle detector according to claim 2, wherein the absolute rotational-angle detecting unit comprises an MR sensor provided a rotational member rotating in association with the measured rotational element for detecting a periodic angular position, and performs calculation processing on output of the MR sensor to detect the absolute rotational angle.
  • 7. The rotational angle detector according to claim 3, wherein the absolute rotational-angle detecting unit comprises an MR sensor provided a rotational member rotating in association with the measured rotational element for detecting a periodic angular position, and performs calculation processing on output of the MR sensor to detect the absolute rotational angle.
  • 8. The rotational angle detector according to claim 5, wherein the absolute rotational-angle detecting unit comprises an MR sensor provided a rotational member rotating in association with the measured rotational element for detecting a periodic angular position, and performs calculation processing on output of the MR sensor to detect the absolute rotational angle.
Priority Claims (1)
Number Date Country Kind
2006-097517 Mar 2006 JP national