Electricity: measuring and testing – Magnetic – Displacement
Reexamination Certificate
2003-05-27
2004-08-31
Le, N. (Department: 2862)
Electricity: measuring and testing
Magnetic
Displacement
C324S207200
Reexamination Certificate
active
06784661
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotation detecting apparatus provided for detecting a rotational angle of a steering wheel of an automobile or the like.
2. Description of Related Art
There is a conventional rotation detecting apparatus described in, for example, JP-A-2000-283704 as shown by FIG.
17
.
FIG. 17
shows a rotation detecting apparatus integrated to a rotational connector apparatus
101
for electrically connecting a vehicle body side thereof and a steering wheel side thereof. That is, a rotation detecting apparatus
107
is provided between a lower housing member
103
and a lower cover member
105
of the rotational connector apparatus
101
. The rotation detecting apparatus
107
is generally constituted by a drive gear
109
, a driven gear
111
, and a circuit board
113
.
The drive gear
109
is constructed by a constitution of being cooperatively rotated in accordance with rotation of the steering wheel. The driven gear
111
is brought in mesh with the drive gear
109
. The driven gear
111
is provided with a magnet
115
at a rotational center portion thereof. The magnet
115
includes a plane portion
117
. The plane portion
117
is contiguously formed with an N pole and an S pole with a rotational center of the driven gear
111
as a boundary. The driven gear
111
is constructed by a constitution in which one face side thereof is rotatably supported by the cover member
105
and other face side thereof is brought into sliding contact with the circuit board
113
. The circuit board
113
is provided with a magnetic reluctance element
119
opposed to the plane portion
117
of the magnet
115
.
Further, when the drive gear
109
is rotated in accordance with steering of the steering wheel, the driven gear
111
is rotated cooperatively therewith. When the magnet
115
is rotated by rotating the driven gear
111
, a magnetic field of the magnetic reluctance element
119
opposed to the plane portion
117
formed with the N pole and the S pole is changed and a reluctance value of the magnetic reluctance element
119
is changed in accordance with the change. An angle signal can be outputted to an external system by converting the change into the angle signal by an electronic circuit portion.
Therefore, a steering angle of the steering wheel or the like can accurately be detected without restricting an angle detecting range.
However, according to the above-described structure, one side face of the driven gear
111
is directly brought into sliding contact with the circuit board
113
and therefore, when the driven gear
111
is rotated, vibration or the like is brought about at the circuit board
113
. Therefore, there is a concern of effecting adverse influence by the vibration on a soldered portion of a circuit element mounted to the circuit board
113
or the magnetic reluctance element
119
per se and there is a concern of deteriorating durability and detection accuracy of the apparatus.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a rotation detecting apparatus capable of promoting durability and promoting detection accuracy of the apparatus by restraining vibration or the like from being brought about on a side of a circuit board when a driven gear is rotated.
A first aspect of the invention is characterized in that in a rotation detecting apparatus comprising a drive gear supported rotatably by a case having a cover and capable of rotating cooperatively with an object to be detected, a driven gear brought in mesh with the drive gear and capable of rotating cooperatively therewith, a magnet provided at a rotational center portion of the driven gear and having an end face portion contiguously formed with an N pole and an S pole, a circuit board arranged at the case, and a magnetic reluctance element attached to the circuit board and being opposed to the end face portion of the magnet and an electronic circuit part for converting an output signal of the magnetic reluctance element into a rotational angle signal, wherein the driven gear is rotatably interposed by the case and the cover and a constant distance is maintained between the end face portion and the magnetic reluctance element.
A second aspect of the invention is a method of fabricating the driven gear for the rotation detecting apparatus according to the first aspect of the invention and is characterized in that the case, the cover, the drive gear and the driven gear are formed by materials having substantially the same linear expansion coefficient.
According to first aspect of the invention, when the drive gear rotatably supported by the case having the cover is rotated cooperatively with the object to be detected, the driven gear brought in mesh with the drive gear can be rotated cooperatively therewith. The driven gear is provided with the magnet having the end face portion contiguously formed with the N pole and the S pole at the rotational center portion and the magnet can be rotated along with the driven gear. The case is arranged with the circuit board, the circuit board is provided with the magnetic reluctance element opposed to the end face portion of the magnet, a magnetic field of the magnetic reluctance element is changed by rotating the magnet, the reluctance value of the magnetic reluctance element is changed in accordance with the change and a signal can be outputted. The output signal of the magnetic reluctance element is converted into the rotational angle signal by the electronic circuit part provided to the circuit board and can be outputted to an external system as an angle signal.
Further, the driven gear is rotatably interposed by the case and the cover, the constant distance is maintained between the end face portion of the magnet and the magnetic reluctance element and therefore, when the driven gear is rotated, the driven gear is rotatably supported by the case and the cover and vibration or the like can be restrained from being brought about at the circuit board. Therefore, adverse influence by vibration can be restrained from effecting on a soldered portion of a circuit element and the magnetic reluctance element mounted to the circuit board, durability of the apparatus is promoted, and rotation can be detected accurately.
According to the second aspect of the invention, in addition to an effect of the first aspect of the invention, since the case, the cover, the drive gear and the driven gear are formed by materials having substantially the same linear expansion coefficient, even when temperature is changed to high temperature or low temperature, an influence is restrained from effecting on a relative relationship among the case, the cover, the drive gear and the driven gear and the detection accuracy equivalent to that at normal temperature can be ensured.
REFERENCES:
patent: 5055781 (1991-10-01), Sakakibara et al.
patent: 5742160 (1998-04-01), Bergstedt et al.
patent: 6646432 (2003-11-01), Malinowski
patent: 199 29 200 (2000-12-01), None
patent: 19929200 (2000-12-01), None
patent: 2000-283704 (2000-10-01), None
EPO Search Report dated Sep. 8, 2003.
Inabe Shinya
Inotsuka Tetsuya
Okuma Sakae
Le N.
Niles Parts Co., Ltd.
Zaveri Subhash
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