Measuring and testing – Speed – velocity – or acceleration
Reexamination Certificate
1999-08-27
2001-12-11
Moller, Richard A. (Department: 2856)
Measuring and testing
Speed, velocity, or acceleration
Reexamination Certificate
active
06327906
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a rotary sensor and more particularly to a rotary sensor capable of detecting rotation angle with high reliability.
2. Description of Related Art
In a prior art rotary sensor, as shown in
FIG. 8
, a housing
1
is formed in an approximately cylindrical shape surrounding the outer periphery. In this housing
1
a partition wall
1
a
is formed.
On the right side surface of the partition wall
1
a
in the drawing a resistor board
2
is positioned by the use of an annular spacer
3
and fixedly attached to the partition wall
1
a.
On one end of the resistor board
2
a terminal
4
is attached. The terminal
4
is projectively formed on the left side of the partition wall
1
a
in the drawing. A sealant
1
b
is filled in a gap portion of the partition wall
1
a
where the terminal
4
is attached, to thereby separate the partition wall
1
a
to the right and left members in the drawing.
In the vicinity of the forward end of the terminal
4
the end of a lead
4
is soldered. The lead is led out upwardly in the drawing.
On the surface of the resistor board
2
a resistor pattern not depicted is formed by printing. A slider piece
6
which slides in elastic contact with the resistor pattern is attached on a slider holder
7
, which is rotatably disposed oppositely to the resistor board
2
. Between the outer periphery of the slider holder
7
and the annular spacer
3
there is mounted a thrust washer
8
to reduce frictional resistance.
The slider holder
7
is rotatably mounted with the hollow portion of its boss portion
7
a
formed on the center of rotation inserted over a stationary shaft
9
a
of a holder guide
9
. On the upper right side surface of the slider holder
7
in the drawing, a lock pawl
7
b
is formed projecting to the holder guide
9
side.
On the outer periphery side of the boss portion
7
a
one torsion coil spring
10
is mounted. The torsion coil spring
10
is attached at one end to the slider holder
7
side and at the other end to the holder guide
9
side, so that the slider holder
7
will constantly be pressed to rotate in one direction.
The holder guide
9
is securely attached at the outer peripheral side surface to the inner peripheral surface of the housing
1
, and a circular long hole
9
b
as viewed from the front is formed above the stationary shaft
9
a
in the drawing, thus schematically constituting the prior art rotary sensor.
The prior art rotary sensor, when used as an accelerator pedal position sensor of an automobile for example, is attached on a predetermined mounting member not depicted. On the right side of the rotary sensor in the drawing, a rotatable drive shaft
11
is disposed and coupled with the automotive accelerator pedal not depicted. On the forward end of the drive shaft
11
an arm member
12
having an approximately L-shaped retaining portion
12
a
is fixedly mounted.
The forward end of the retaining portion
12
a
is positioned within the long hole
9
b
of the holder guide
9
, and is constantly in elastic contact with the lock pawl
7
b
of the slider holder
7
which is pressed to rotate in one direction by the elastic force of the torsion coil spring
10
.
When for instance the accelerator pedal is depressed to turn the drive shaft
11
through a specific angle in the other direction, the slider holder
7
is also turned through a specific angle in the other direction against the elastic force of the torsion coil spring
10
.
With the rotation of the slider holder
7
, the resistance value of an unillustrated resistor on the resistor board
2
varies. This variation in the resistance value is detected by an unillustrated control unit connected to the lead wire
5
, thereby enabling detection of the rotation angle of the drive shaft
11
.
In the meantime, when the accelerator pedal is released, the drive shaft
11
is restored to the initial state and, with the rotation of the arm member
12
, the slider holder
7
is reset to the initial position by the elastic force of the torsion coil spring
10
.
In the prior art rotary sensor described above, however, only a single torsion coil spring
10
is employed to elastically force the slider holder
7
towards the direction of rotation. The torsion coil spring
10
, therefore, is subjected to accumulated metal fatigue on the slider holder
7
side or in the retaining portion on the holder guide
9
side, resulting in a spring failure during rotation of the slider holder
7
after a use for long-time. In the event of the failure of the torsion coil spring
10
, the slider holder
7
can not be restored to the initial position and consequently the automobile will fail to operate.
Also it is necessary to provide a force of restoration of a specific value or more in any position of rotation. Where the torsion coil spring
10
alone is used, it becomes necessary to increase a spring constant, which, however, will make the torsion coil spring
10
liable to break. The problem also arises that the torsion coil spring
10
of the rotary sensor requires an increase in the strength of its mounting portion.
As a measure to solve these problems, the number of coils of the torsion coil spring
10
needs to be increased to lower the rate of increase of the spring force with respect to the amount of rotation. In this case however, the problem arises that the rotary sensor will increase in height.
SUMMARY OF THE INVENTION
To solve the aforementioned problems, therefore, this invention has an object to provide a rotary sensor which can continue to operate without stopping if there occurs such a trouble as the failure of the torsion coil spring
10
during operation, and also can achieve a relatively uniform elastic force of the torsion coil spring
10
at any angle of rotation in the direction of rotation, and an excellent effect of decreasing in thickness.
As the first arrangement to solve the aforesaid problems, the rotary sensor of this invention is comprised of a rotator for transmitting rotation from outside, a housing for rotatably supporting the rotator, and an angle sensing member for detecting the angle of rotation of the rotator; and at least two first and second torsion coil springs constantly applying a spring force to turn the rotator in one direction towards the housing are mounted between the rotator and the housing.
As the second arrangement to solve aforesaid problems, a rotating shaft formed on the center of rotation of the rotator is rotatably supported on the housing; the first torsion coil spring is disposed to surround the rotating shaft; and the second torsion coil spring is disposed outside of the first torsion coil spring to surround the first torsion coil spring.
As the third arrangement to solve the aforesaid problems, the first and second torsion coil springs are made such that the retaining portion formed at one end is retained to a part of the housing and the retaining portion formed on the other end retained to a part of the rotator; the retaining portion on the one end of the second torsion coil spring being superposed on the retaining portion at one end of the first torsion coil spring.
As the fourth arrangement to solve the aforesaid problems, the first and second torsion coil springs are disposed in the first and second guide grooves of a specific depth formed in the housing. The first guide groove is formed deeper by the wire diameter of the first torsion coil spring than the second guide groove. And the depth of the second guide groove is made equal to the depth of the first guide groove in the superposed retaining portions on the one end of the first and second torsion coil springs.
Other features and advantages of this invention will become apparent from the following description of embodiments of this invention, together with the accompanying drawings.
REFERENCES:
patent: 5201291 (1993-04-01), Katoh et al.
patent: 5506502 (1996-04-01), Maennle
patent: 5567874 (1996-10-01), Suzuki et al.
patent: 5571960 (1996-11-01), Tateishi et al.
patent: 43 31 902 A1 (1995-03-
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Moller Richard A.
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