Electricity: measuring and testing – Magnetic – Displacement
Reexamination Certificate
1999-11-12
2001-12-11
Snow, Walter (Department: 2862)
Electricity: measuring and testing
Magnetic
Displacement
C324S207120
Reexamination Certificate
active
06329815
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotation sensor such as a throttle position sensor, attached to a throttle valve, for detecting an opening level of the valve, and more particularly to a rotation sensor accommodable to the eccentricity of a rotation portion of the valve relative to the rotating shaft of the sensor.
2. Description of the Related Art
FIG. 23
is a schematic diagram showing a conventional rotation sensor as described above. As shown in the figure, a shaft
52
is coupled to a rotor
51
of a detection side, the shaft
52
is rotatably supported at a location of a bearing
53
, and a magnetized code plate
54
that is integrally connected to the tip of the shaft
52
. In the vicinity of the circumference of the code plate
54
that is disposed a magnetism detecting element
55
, which is supported by a casing (not shown).
By way of example, the conventional rotation sensor, which has a so-called one-point support configuration in which the shaft
52
is supported at one point, has the shaft
52
supported by the bearing
53
with some backlash so that it is freely rotatable. If the rotor
51
is attached to the shaft
52
with their center axes in misalignment or if in its place the rotor
51
itself rotates eccentrically, then the code plate
54
will rotate eccentrically, and a gap G between the code plate and the magnetism detecting element
55
will change greatly. As a consequence, a linear output will not be obtained in a magnetic variable resistor. This has been a disadvantage of conventional rotation sensors.
If the shaft
52
is supported at two points to solve this disadvantage, although a relative positional relationship between the code plate
54
and the magnetism detecting element
55
can be maintained to a degree of the clearance between the shaft
52
and the bearing
53
, without enhancing the accuracy of mounting dimensions, detailed detection of rotation states would become impossible because of actuating force decreased due to center misalignment. Another disadvantage is that the eccentricity of the shaft
52
causes wear on the two-point support portions, reducing the operating life of the sensor.
SUMMARY OF THE INVENTION
An object of the present invention is to solve these disadvantages of the related art and provide a highly reliable rotation sensor capable of correctly detecting rotation states.
To achieve the above described object, the present invention provides a rotation sensor comprising:
a rotor having a magnetized portion on, e.g., a circumferential side, rotating together with a rotation portion of a detection side such as, e.g., a throttle valve;
a first supporting member for rotatably supporting the rotor; and
a detecting member, secured to the first supporting member, and having a hole IC for detecting a rotation state of the rotor,
wherein the first supporting member is supported movably in both directions, that is, an X direction which is orthogonal to the direction of the rotating shaft of the rotor and a Y direction which is orthogonal to the direction of the rotating shaft of the rotor and orthogonal to the X direction.
According to the present invention, as previously described, since both the rotor and the detecting member for detecting a rotation state thereof are supported by the first supporting member and the rotor and the detecting member are movable together in the X and Y directions, even if the rotation portion becomes eccentric, the rotor and the detecting member together can follow the eccentricity and the spacing between the rotor and the detecting member is always constant, and therefore there is no output variation due to the eccentricity of the rotation portion.
Since this construction eliminates the need to support the shaft at two points, there can be provided a rotation sensor which is free of decrease in actuating force, capable of correct detection of a rotation state, and highly reliable.
A rotation sensor of the present invention may comprise:
a second supporting member for supporting the first supporting member; and
a third supporting member for supporting the second supporting member,
wherein the first supporting member is supported movably to the Y direction by the second supporting member, and
the second supporting member is supported movably to the X direction by the third supporting member.
According to the present invention, if both the first supporting member and the third supporting member are constructed from a synthetic resin and the second supporting member is constructed from metal, friction resistance is reduced and the rotation sensor moves smoothly in the X and Y directions, so that it can detect a rotation state more correctly.
According to the present invention, Y-direction guide means which permits the travel of the first supporting member in the Y direction and prevents the travel thereof in the X direction is provided in the second supporting member, and X-direction guide means which permits the travel of the second supporting member in the X direction and prevents the travel thereof in the Y direction is provided in the third supporting member, whereby the travel in the X and Y directions is distinctly divided so that the rotation sensor can respond appropriately to the eccentricity of a rotation portion.
According to the present invention, since the third supporting member is formed with an exterior member of the sensor in a fixed state, the third supporting member need not be provided additionally, so that parts can be reduced in quantity, size, and weight.
According to the present invention, a terminal is provided in the third supporting member, and the terminal and the detecting member are connected by a flexible connecting wire, whereby the first supporting member moves without trouble and a rotation state can be correctly detected.
According to the present invention, a concave housing part is formed in the first supporting member and the detecting member is inserted and secured within the housing member, and thereby the detecting member is disposed close to the rotor, so that correct detection of a rotation state can be made and the detecting member does not project substantially from the first supporting member, providing no obstacle for the travel of the first supporting member.
According to the present invention, if the first supporting member is of shape of almost rectangular frame and is disposed in sliding on the second supporting member, the first supporting member moves stably.
According to the present invention, since the rotor has a magnetized portion on the circumferential side and the detecting member is a magnetism detecting element, the reliability of detection is high and the configuration of the detection part is simple and inexpensive.
According to the present invention, since a rotation part of a detection side is a throttle valve, there can be provided a highly reliable throttle position sensor capable of correct detection of a rotation state.
REFERENCES:
patent: 4495700 (1985-01-01), Ernst
patent: 4901562 (1990-02-01), Beakas et al.
patent: 5088319 (1992-02-01), Hirose et al.
patent: 39 42 826 A 1 (1991-06-01), None
patent: 0 762 081 A1 (1997-03-01), None
patent: 4-17455 (1992-02-01), None
Ogawa Toshio
Yamazaki Kenji
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Snow Walter
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