Electrical resistors – Mechanically variable – Movable contact electrically adjustable over length of...
Reexamination Certificate
1997-09-05
2001-03-20
Easthom, Karl D. (Department: 2832)
Electrical resistors
Mechanically variable
Movable contact electrically adjustable over length of...
C338S199000, C338S160000, C338S184000
Reexamination Certificate
active
06204749
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electric part for use as, for example, a valve opening control sensor for an exhaust gas recirculator in a vehicle, a sensor for controlling the mixture ratio between gasoline and air, and various kinds of encoders.
2. Description of the Related Art
A conventional electric part of this type will be described with reference to a cross-sectional view of FIG.
13
. The electric part shown in
FIG. 13
comprises a casing
1
which forms an outer shell, a shaft
2
movable from side to side in
FIG. 13
with respect to the casing
1
, an insulating substrate
3
housed in the casing
1
, a brush
4
which slidably contacts a conductive pattern (not shown), such as a resistor or a current collector, provided on the insulating substrate
3
, a slider receiver
5
for holding the brush
4
, a return spring
6
positioned offset from the axis of the shaft
2
to supply a spring force to the slider receiver
5
, and an external terminal
7
connected to the insulating substrate
3
.
In the casing
1
, the shaft
2
is inserted into a slot
1
a
provided at one end of the casing
1
, and an opening
1
b
at the other end is tightly sealed with a cover
8
. A pair of guide grooves (not shown), extending parallel to the axis of the shaft
2
, are formed on opposed inner walls of the casing
1
, and a pair of projections
5
a
formed on the slider receiver
5
are engaged with the guide grooves.
The insulating substrate
3
housed in the casing
1
is engaged, at both side ends thereof, with a second pair of grooves formed on the opposed inner walls of the casing
1
, and urged toward the slider receiver
5
by a corrugated leaf spring
9
interposed between the casing
1
and the back of the insulating substrate
3
.
At one end of the insulating substrate
3
, a terminal section
3
a
having thereon a conductive terminal pattern (not shown) connected to the resistor or the current collector is formed. A connecting section
7
a
is formed at one end of the external terminal
7
. The terminal section
3
a
of the insulating substrate
3
and the connecting section
7
a
of the external terminal
7
are connected to each other by a clip terminal
10
on the side of the opening
1
b
of the casing
1
. Furthermore, a groove
11
for holding the return spring
6
is formed at the position offset from the axis of the shaft
2
in the casing
1
, and the return spring
6
held in the groove
11
urges the slider receiver
5
in the axial direction. The shaft
2
and the slider receiver
5
are provided with a convex section
2
a
and a concave section
5
b
, respectively, which are engaged with each other. A hole
1
c
is formed for use in attaching this electric part to other devices.
The conventional electric part having the above-mentioned construction is assembled as follows: First, the leaf spring
9
and the insulating substrate
3
are loaded in the casing
1
. Next, the shaft
2
is inserted into the slot
1
a
, which is formed at the other side of the opening
1
b
of the casing
1
, from the side of the opening
1
b
, the pair of projections
5
a
of the slider receiver
5
are engaged with the pair of grooves in the casing
1
, and the slider receiver
5
is engaged with the shaft
2
. Then, the terminal section
3
a
of the insulating substrate
3
and the connecting section
7
a
of the external terminal
7
are resiliently clamped by the clip terminal
10
, and the return spring
6
is inserted into the groove
11
for housing the spring in the casing
1
. Finally, the opening
1
b
of the casing
1
is closed by the cover
8
.
In the foregoing electric part, however, since the shaft
2
must be inserted into the slot
1
a
located on the side of the casing
1
which is far back from the opening
1
b
, insertion is difficult, and assembly efficiency is thereby reduced.
The electric part constructed as mentioned above is, for example, attached to a control valve container
12
, as a valve opening detecting sensor for use in an exhaust gas recirculator in an engine, through an attachment member
13
or the like, as shown in FIG.
14
. The electric part is so attached that the shaft
2
projects into the control valve container
12
and that hermetic sealing is provided between the electric part and the control valve container
12
. The shaft
2
moves inward and outward in correlation to the motion of a control valve (not shown) in the control valve container
12
.
In such a state in which the electric part is attached to the control valve container
12
, the cover
8
covering the opening
1
b
of the casing
1
is exposed outside. Therefore, even if the opening
1
b
of the casing
1
is tightly sealed with the cover
8
, the sealing state is deteriorated under the influence of long-term changes in the external environment, such as temperature and humidity, dust or the like, whereby the contact between the brush
4
in the casing
1
and the resistor and the current collector on the insulating substrate
3
is made unstable.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an electric part which is excellent in assembly efficiency and is not influenced by environmental changes.
In order to achieve the above object, the present invention provides an electric part comprising a closed-end main casing, an insulating substrate held in the casing, an external terminal held in the main casing and connected to the insulating substrate, a slider receiver movably held in the casing, a shaft for moving the slider receiver, and a cover for closing an opening of the casing, wherein the shaft is supported by a bearing formed on the cover to protrude from the cover and further provided with a fall-preventive means, the insulating substrate has a terminal section at one end thereof, the outer terminal has a connecting section at one end thereof, and the terminal section and the connecting section are projected toward the opening of the casing and connected to each other by a clip terminal.
Furthermore, the cover is provided with a through hole, and the terminal section of the insulating substrate and the connecting section of the external terminal protrude outward through the through hole and are connected to each other.
Still furthermore, a protective cover for covering the terminal section of the insulating substrate and the connecting section of the external terminal is provided on the cover.
REFERENCES:
patent: 2850608 (1958-09-01), Bourns et al.
patent: 4213112 (1980-07-01), Alman et al.
patent: 4284969 (1981-08-01), Carbonneau
patent: 4894638 (1990-01-01), Flierl et al.
patent: 5072206 (1991-12-01), Kozuka et al.
patent: 5345215 (1994-09-01), Okumura et al.
patent: 5435181 (1995-07-01), Koebernik
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Easthom Karl D.
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