Exhaust gas recirculation sensor

Details Exhaust gas recirculation sensor Exhaust gas recirculation sensor

2001-06-21

2002-07-09

Easthom, Karl D. (Department: 2832)

Electrical resistors

Mechanically variable

Movable contact electrically adjustable over length of...

C338S153000

Reexamination Certificate

active

06417759

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an exhaust gas recirculation sensor for controlling an amount of the recycling of exhaust gas from an automobile. The exhaust gas recirculation will be hereinafter referred to as EGR.
2. Description of the Prior Art
A conventional EGR sensor will be described with reference to
FIGS. 12
to
14
. A case
31
consisting of a mold of synthetic resin has a hollow housing portion
31
a
with its one side opened, a pair of concave shoulder portions
31
b
extending in the front to rear direction in the housing portion
31
a
, a pair of right and left guide portions
31
c
located above the shoulder portions
31
b
and extending in the front to rear direction in the housing portion
31
a
, and a tubular portion
31
d
protruding in the direction normal to the housing portion
31
a.
An insulating substrate
33
provided with a plurality of metal terminals
32
is mounted with a hole IC
34
connected electrically to the terminals
32
. The insulating substrate
33
is inserted into a pair of the shoulder portions
31
b
of the case
31
to be mounted in the housing portion
31
a.
The terminals
32
mounted onto the insulating substrate
33
are soldered and connected to one end of an L-shaped pin
35
for connector embedded into the case
31
.
A cover
36
consisting of a mold of synthetic resin has a bearing portion
36
b
provided in its center portion with a circular hole
36
a
and a convex portion
36
c
provided in the rear side portion of the outer circumference thereof. The cover
36
is mounted by fitting the convex portion
36
c
into the case
31
so as to cover the opening portion of the case
31
.
An operating shaft
37
has a cylindrical shaft portion
37
a
, a stopper portion
37
b
provided at the rear side of the shaft portion
37
a
, and a convex portion
37
c
provided in the rear end of an axial direction G
2
. The shaft portion
37
a
is guided through the hole
36
a
of the cover
36
so as to move the operating shaft
37
linearly. The stopper portion
37
b
is contacted onto a rear end
36
d
of the bearing portion
36
b
so as to prevent the operating shaft
37
from coming off the bearing portion
36
b.
To assemble the operating shaft
37
, the shaft portion
37
a
is first inserted from the rear side of the cover
36
through the hole
36
a
. Then, the stopper portion
37
b
is retained to the rear end
36
d
of the cover
36
, and the operating shaft
37
is combined with the cover
36
. Thereafter, while both are combined with each other, the cover
36
is assembled into the case
31
.
A movable member
38
consisting of a mold of synthetic resin has a rectangular base portion
38
a
located in the center, a pair of spring receiving portion
38
b
extending from the base portion
38
a
to right and left and each having in its end a cross portion, and four sliding portions
38
c
each provided at the right or left side in the front or rear position of the base portion
38
a.
In addition, the movable member
38
is provided in its lower portion with a magnet
39
. The movable member
38
provided with the magnet
39
is mounted onto the case
31
so as to be moved linearly while the magnet
39
is opposite to the hole IC
34
and the sliding portions
38
c
are located in the guide portion
31
c
of the case
31
.
The magnet
39
and the hole IC
34
construct detection means K
2
.
Two coil springs
40
are disposed in the housing portion
31
a
so that one end of each of the coil springs
40
is contacted onto a back surface wall
31
e
, and the other end is contacted onto the spring receiving portion
38
b
of the movable member
38
.
The two coil springs
40
bias the movable member
38
forward. The center portion of the movable member
38
is thus contacted resiliently onto the convex portion
37
c
of the operating shaft
37
. The stopper portion
37
b
is contacted onto the rear end
36
d
of the bearing portion
36
b
to prevent the operating shaft
37
from coming off the bearing portion
36
b.
The operation of the conventional EGR sensor will be described. A rod for driving the EGR valve of an automobile pushes the operating shaft
37
against the coil springs
40
. The operating shaft
37
allows the movable member
38
to be guided by a guide portion
31
c
and to move linearly in the axial direction G
2
.
The magnet
39
is also moved to fluctuate the magnetic field to the hole IC
34
. As a result, the detection means K
2
varies the electric current value so as to detect an amount of the operating shaft
37
moved.
When the pushing of the operating shaft
37
by the rod is released, the coil springs
40
push back the movable member
38
, and the operating shaft
37
is also pushed back into the original state by the movable member
38
.
Thus, the conventional EGR sensor can be operated.
In the convention EGR sensor, while the operating shaft
37
is assembled into the bearing portion
36
b
of the cover
36
, the cover
36
is mounted onto the case
31
. The assembling operation is troublesome, so that the productivity is poor, and the cost is high.
Further, in the EGR sensor, in the case where the operating shaft
37
is found to be scratched in quality inspection before shipping, the operating shaft
37
must be replaced. The cover
36
must be removed during the replacement. The replacement operation is troublesome, so that, substantially, the EGR sensor must be discarded, and parts other than the operating shaft
37
are wasted.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an EGR sensor which facilitates the assembling operation and can easily replace the operating shaft.
As a first solving means for solving the foregoing problems, an exhaust gas recirculation sensor comprises an operating shaft movable linearly in the axial direction, a bearing portion for guiding movement of the operating shaft, a movable member movable linearly by the operating shaft, a spring member for returning movement of the movable member and biasing the movable member so as to resiliently contact the movable member onto the operating shaft, a case for guiding movement of the movable member, and detection means operated by movement of the movable member, wherein the operating shaft is provided in its rear portion with a convex portion protruding from a shaft portion in the direction orthogonal to the axial direction, the bearing portion is provided with a concave portion connected to a hole through which the shaft portion is inserted and allowing the convex portion to be inserted therethrough in the axial direction, and the convex portion protruding from the rear end of the bearing portion is retained to the rear end of the bearing portion other than the concave portion.
As a second solving means, the rear end of the bearing portion is provided with blocking portions for blocking movement of the convex portion to the concave portion.
As a third solving means, the blocking portions are formed by protrusions provided at both sides of the concave portion.


REFERENCES:
patent: 5072206 (1991-12-01), Kozuka et al.
patent: 5095299 (1992-03-01), Wakamatsu
patent: 5345215 (1994-09-01), Okumura et al.
patent: 6034590 (2000-03-01), Ishihara
patent: 6051897 (2000-04-01), Wissler et al.
patent: 6024749 (2001-03-01), Ishihara

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