Measuring and testing – Simulating operating condition – Marine
Reexamination Certificate
1997-07-01
2001-01-23
Dombroske, G. (Department: 2855)
Measuring and testing
Simulating operating condition
Marine
C073S865900
Reexamination Certificate
active
06176124
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for inspecting a spark plug connector, and more particularly, to an apparatus for checking a spark plug connector used in internal combustion engines for vehicles such as automobiles.
2. Description of the Prior Art
The spark plug connector electrically connects the terminal of a spark plug (installed in a plug hole) to a high-tension electrical cable extending from a distributor. As shown in
FIG. 1
, a spark plug connector
6
includes a pipe
3
of circular cross-section, containing a connector terminal
2
. The pipe
3
may be formed from resin plastic. One end of the connector terminal
2
is electrically connected to a high-tension electrical cable
1
, while the other end is electrically connected to the terminal of a spark plug fitted at the base of a plug hole (not shown). A bushing
4
, made of an insulating elastic material such as silicone rubber, is fitted at one end portion of the pipe
3
. The bushing
4
covers the external and internal surface of the end portion of the spark plug connector
6
. A waterproof cover
5
, made of an insulating elastic material such as silicone rubber, is fitted at the other end portion of the pipe
3
, closing off the pipe entrance. In this structure, the term “bushing stem” designates the assembly of the pipe
3
, the bushing
4
and the waterproof cover
5
.
In order to avoid a loose contact between the spark plug and the bushing stem
7
after the bushing stem
7
is assembled, a distance S between the bushing-side rim of the bushing stem
7
and the tip of the connector terminal
2
is measured. The distance S is then assessed as to whether it is within a tolerated range.
As shown in
FIGS. 2 and 3
, a conventional detection device
8
is used to detect a departure from the tolerances. The detection device
8
includes a bushing holder unit
9
that laterally holds the bushing stem
7
(i.e., in the left and right directions in
FIGS. 2 and 3
) and a deviation detecting unit
10
. The deviation detecting unit
10
is provided to one side of the bushing holder
9
(the right side in FIGS.
2
and
3
). The deviation detecting unit
10
is introduced from the side of the bushing
4
of the bushing stem
7
so that the distance S from the bushing
4
to the connector terminal
2
may be measured.
The bushing holder unit
9
includes a fixing plate
11
having a flat rectangular form, and a bushing holder
12
provided at the plug end portion of the fixing plate
11
. The bushing holder
12
is formed with a holding recess
12
a
that holds the bushing
4
in a snug fit and a threshold plate
13
. The threshold plate
13
is formed with a (measuring) contact surface
13
a
for determining the contact position of the end face (rim) of the bushing
4
. A waterproof cover holder
14
is fixed on the leftward portion of the bushing holder unit
9
, and is formed with a fitting recess
14
a
that grips the waterproof cover
5
. The fixing plate
11
is fixedly provided on a frame portion
15
of the detection device
8
.
The deviation detecting unit
10
further includes a mobile base plate
16
fixed to the frame portion
15
of the detection device
8
, but freely reciprocable in the axial direction (i.e., the left and right directions of FIGS.
2
and
3
). A drive cylinder
17
, connected to the frame portion
15
, produces an axial thrust that displaces the mobile base plate
16
. A measuring probe
19
is mounted on the mobile base plate
16
, through a supporting block
18
. The measuring probe
19
therefore moves in accordance with the movement of the mobile base plate
16
. A distance measuring device
20
, including at least an optical sensor or the like, detects the shifted position of the measuring probe
19
. The mobile base plate
16
and the drive cylinder
17
are arranged on the frame portion
15
of the detection device
8
such that a tip portion
19
a
of the measuring probe
19
is in front of and aligns with the corresponding bushing stem
7
.
As shown in
FIG. 2
, the tip portion
19
a
of the measuring probe
19
is normally set up in a ready-to-trigger position by an elastic or biasing device (not shown), and the tip portion
19
a
may be thrust towards the bushing holder unit
9
by a predetermined length.
When detecting the deviation in the plug connector
6
, the waterproof cover
5
of the bushing stem
7
is retained within the fitting recess
14
a
of the waterproof cover holder
14
, while the bushing
4
is securely pressed into the holding recess
12
a
of the bushing holder
12
.
In this state, the drive cylinder
17
of the deviation detecting unit
10
is actuated toward full extension. The mobile base plate
16
is then shifted towards the bushing holder unit
9
. The tip
19
a
of the measuring probe
19
is passed through an orifice (not shown) formed in the threshold plate
13
, and is inserted from the side of the bushing
4
into the bushing stem
7
. As shown by the cross-sectional view in
FIG. 1
, the tip
19
a
abuts the rim of the connector terminal
2
.
If the mobile base plate
16
is further extended from this position, the measuring probe
19
is pushed back toward the distance measuring device
20
, against the force of the elastic or biasing device (not shown). The measuring plate
19
b
provided at the distance measuring device
20
end of the measuring probe
19
approaches the distance measuring device
20
.
Subsequently, the distance A between the measuring plate
19
b
(after being pushed back) and the distance measuring device
20
is measured by the distance measuring device
20
, so that the distance S between the rim of the bushing
4
and the tip of the connector terminal
2
, and/or deviation from a predetermined distance S, may be indirectly determined. Consequently, it can be determined whether the distance S is within appointed tolerances.
However, in a conventional detection device
8
for plug connector, the bushing holder unit
9
has a bushing holder
12
and a waterproof cover holder
14
specifically modelled on the particular forms of a bushing
4
of the bushing stem
7
and waterproof cover
5
to be inspected. That is, the particular waterproof cover
5
of the bushing stem
7
is retained within a matching fitting recess
14
a
on the waterproof cover holder
14
, while a particular bushing
4
is pressed into a matching holding recess
12
a
on the bushing holder
12
. Thereafter, the deviation of the distance between the rim of the plug connector
6
(specifically, the outside rim of the bushing
4
) and the tip of the connector terminal
2
is measured. Moreover, the bushing
4
and the waterproof cover
5
must be pushed to fit onto a pipe
3
of the bushing stem
7
. In such a case, depending upon the pushing force, the total length of the bushing stem
7
may vary, causing a distance deviation B between the (measuring) contact surface
13
a
of the threshold plate
13
and the rim of the bushing
4
.
In other words, when measuring the distance S, the rim of the bushing
4
cannot always be placed at a predetermined position, and the distance deviation B often occurs. This distance deviation B leads to measuring error, so that some errors may occur when categorizing conforming and non-conforming products.
Furthermore, in the known devices, a specific type of bushing holder is applied to each different type of plug connector, while each type of plug connector uses a number of types of waterproof cover. Consequently, the conformity of products may be determined by the degree of fit only after the waterproof cover is fitted into the fitting recess. Moreover, each type of bushing holder unit is applicable to one specific type of plug connector and is fixed on the frame portion of the deviation detecting device. In this construction, the bushing holder unit is not amenable for adaptation to various configurations, and therefore cannot be used to measure various plug connectors.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to pr
Dombroske G.
Greenblum & Bernstein P.L.C.
Sumitomo Wiring Systems Ltd.
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