Electricity: measuring and testing – Magnetic – Displacement
Reexamination Certificate
2000-10-17
2002-07-23
Lefkowitz, Edward (Department: 2862)
Electricity: measuring and testing
Magnetic
Displacement
C324S207250
Reexamination Certificate
active
06424147
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotation angle detection apparatus, and more particularly relates to a rotation angle detection apparatus that is connected to a rotor such as a steering shaft of an automobile capable of generating two angle detection signals having 90 degree phase difference corresponding to the rotation angle and rotation direction of a steering wheel and capable of correctly detecting the rotation angle of the rotor by obtaining the cotangent angle of the obtained two angle detection signals.
2. Description of the Related Art
Generally, a rotation angle detection apparatus, which is an apparatus used for detecting the rotation angle of a rotor, is provided at least with a rotation angle detection unit for detecting the rotation angle of a rotor, a control unit for controlling the operation of the rotation angle detection apparatus, and a controller for controlling a controlled mechanism. In the case that a rotation angle detection apparatus is used for detecting the rotation angle of a steering shaft of an automobile, the rotation angle detection apparatus is mounted on an automobile, and a rotation angle detection unit is coupled with a steering shaft of the automobile. In this case, various types of rotation sensors have been used for a rotation angle detection unit in a rotation angle detection apparatus mounted on an automobile, a rotation sensor as described hereunder has been proposed as one of these various types of rotation sensors.
The above-mentioned proposed rotation sensor has a rotation angle detection unit provided with a base member and a rotor unit disposed rotatable with respect to the base member, and the rotor unit is coupled to a rotor, namely a steering shaft of an automobile in this case. Furthermore, the rotation angle detection unit has a first magnet and a second magnet disposed on the base member, a first Hall element and a second Hall element disposed on the rotor unit with approximately 90 degree interval at the position facing to the first magnet, and a third Hall element disposed at the position facing to the second magnet. When the rotor namely the rotor unit is rotated, the sine wave-like first angle detection signal and the second angle detection signal having the constant maximum amplitude, the same period, and 1/4 wavelength phase difference are generated, and a third angle detection signal having a period of the entire rotation range of the rotor unit that increases linearly is generated simultaneously from the third Hall element.
The generated first angle detection signal, the second angle detection signal, and the third angle detection signal are supplied to the control unit. The control unit detects the rough rotation angel and rotation direction with reference to the neutral position of the steering wheel (steering shaft) based on the supplied third angle detection signal. The control unit detects the fine rotation angle with reference to the neutral position of the steering wheel based on the supplied first angle detection signal and second angle detection signal. Then, the control unit supplies the rotation angle and rotation direction with reference to the neutral position of the steering wheel to the controller as the angle detection information. The controller finely performs suspension control and automatic transmission control of an automobile based on the supplied angle detection information.
Herein,
FIG. 3
shows a characteristic diagram for describing the relation between the rotation angle of the steering wheel generated from the rotation sensor and the respective detection signal voltage values of the first to third angle detection signals in the rotation angle detection apparatus in which the above-mentioned proposed rotation sensor is used.
In
FIG. 3
,
16
represents the first angle detection signal,
17
represents the second angle detection signal, and
18
represents the third angle detection signal. These three signals represent the change of respective detection signal voltage values of the first to third angle detection signals
16
,
17
, and
18
for the entire rotation angle (±720 degrees with respect to the neutral position) of the steering wheel.
In this case, the first angle detection signal
16
and the second angle detection signal
17
are the same sine wave-like signals having the same maximum amplitude and the same one period, and having the 1/4 wavelength phase difference. The maximum voltage value is 4.5 V and the minimum voltage value is 0.5 V for both signals. The first angle detection signal
16
falls to the minimum value (voltage value of 0.5 V) at the rotation angles of −22.5 degrees and +67.5 degrees with respect to the neutral position, at the rotation angles of successive subtraction of −90 degrees from −22.5 degrees, and at the rotation angles of successive addition of +90 degrees to +6.75 degrees. The second angle detection signal
17
falls to the minimum value (voltage value of 0.5 V) at the rotation angle of the neutral position 0 degree, at the rotation angles of successive subtraction of −90 degrees from 0 degree, and at the rotation angle of successive addition of +90 degrees to 0 degree. On the other hand, the third detection signal
18
increases linearly from the rotation angle of −720 degrees to +720 degrees, and takes the minimum value (voltage value of 0.5 V) at the rotation angle of −720 degrees and takes the maximum value (voltage value of 4.5 V) at the rotation angle of +720 degrees.
FIG. 10
is a characteristic diagram that shows the enlarged range from the rotation angle of −90 degrees to +90 degrees of the characteristic diagram shown in FIG.
3
.
In
FIG. 10
,
16
U is an approximately linear upward (slope) portion of the first angle detection signal
16
,
16
D is an approximately linear downward (slope) portion of the first angle detection signal
16
,
17
U is an approximately linear upward (slope) portion of the second angle detection signal
17
, and
17
D is an approximately linear downward (slope) portion of the second angle detection signal
17
. The same components shown in
FIG. 10
as those shown in
FIG. 3
are given the same characters.
The detection of the rotation angle and the rotation direction of the steering wheel executed by means of the known rotation angle detection apparatus will be described with reference to the characteristic diagram shown in FIG.
10
.
At first, when the control unit detects the rotation direction with respect to the neutral position (rotation angle of 0 degree) of the steering wheel, the control unit uses the voltage value of the supplied third angle detection signal
18
. In detail, if the voltage value of the third angle detection signal
18
is larger than 2.5 V, the control unit detects that the rotation direction of the steering wheel is the one direction (positive rotation angle direction) with respect to the neutral position, on the other hand if the voltage value of the third angle detection signal
18
is smaller than 2.5 V, the control unit detects that the rotation direction of the steering wheel is the other direction (negative rotation angle direction) with respect to the neutral position.
Next, the control unit divides the entire rotation angle ±720 degrees of the steering wheel into rotation angle sections N−1, N, N+1, . . . . that are corresponding to each one wavelength of the first angle detection signal
16
and the second angle detection signal
17
as shown in
FIG. 10
, and detects the rough rotation angle that represents what rotation angle section corresponds to the rotation angle of the steering wheel depending on the voltage value of the supplied third angle detection signal
18
. For example, when the control unit detects 2.8 V as the voltage value of the third angle detection signal
18
, the control unit detects the angle section N as the angle section that is corresponding to that voltage value.
Next, the control unit deter
Hoshi Toshiyuki
Kato Hironori
Okumura Hirofumi
Sanpei Yoshio
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Lefkowitz Edward
Zaveri Subhash
LandOfFree
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