Electrical connectors – Having spark or glow plug cover
Reexamination Certificate
1999-11-15
2001-03-27
Patel, Tulsidas (Department: 2839)
Electrical connectors
Having spark or glow plug cover
Reexamination Certificate
active
06206709
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high voltage terminal for connecting an ignition cable to a terminal of approximately columnar shape such as an end terminal of an ignition plug.
2. Description of Background Information
Conventionally, the structure of the connecting part between the ignition cable and the ignition plug has been constituted as shown in FIG.
10
.
According to this structure of the connecting part, an ignition plug P is fitted to the engine body E such that the insulator part Pg at the top of the ignition plug P projects upwardly. At the upper part of the insulator part Pg, a ball-topped, generally columnar end terminal Pt projects for receiving a secondary high voltage from the ignition coil. Also, a rubber boot
100
is provided to accommodate a high voltage terminal
110
at the end of the ignition cable K. The rubber boot
100
is engaged with the insulator part Pg of the ignition plug P, and inside the rubber boot the high voltage terminal
110
and the end terminal Pt are held in an electrically connected state. Furthermore, the rubber boot
100
is covered with a metal heat shielding member
105
, thereby preventing thermal degradation of the rubber boot
100
by shielding radiating heat from a heat generation source such as exhaust pipe.
In the construction shown in
FIG. 11
, a high voltage terminal
110
is formed by continuous connection on a straight line, through a connecting part
116
, of a tubular terminal
114
on one end of a channel-shaped, press-fit clamping part
112
having a projection
111
at the tip of both sides. Also, a portion of the continuous connecting part
116
and the bottom part of the terminal
114
are cut and deformed upwardly to form a contact piece
117
projecting between the press-fit clamping part
112
and the tubular terminal
114
. When the end of the ignition cable K is accommodated in the press-fit clamping part
112
and its end is press-fitted to the contact piece
117
, the press-fit clamping part
112
is deformed inwardly to press-fit the projection
111
in a manner to bite into the outer peripheral part of the ignition cable K, such that the high voltage terminal
110
is fixed to the ignition cable K end.
A generally C-shaped elastic C-ring member
118
is clipped onto the above terminal
114
. This C-ring member
118
is formed in a manner to be fitted onto the terminal
114
, as shown in
FIG. 12
, and on both sides of its inner peripheral surface are formed a pair of projections
119
which project inwardly. On the other hand, on the outer peripheries of both sides of the terminal
114
are formed a pair of stopping holes
115
within which the projections
119
may be engaged. By applying the C-ring member
118
to the terminal
114
in a manner to engage each projection
119
within each stopping hole
115
, the C-ring member
118
is fixed to the high voltage terminal
110
.
According to this construction of the high voltage terminal
110
, by inserting the end terminal Pt of the ignition plug P into engagement with the terminal
114
, the high voltage terminal
110
and the end terminal Pt of the ignition plug P are electrically connected.
In order to assemble the structure of the connecting part between the ignition cable K and the ignition plug P using the high voltage terminal
110
of such construction, when the rubber boot
100
is engaged in the insulator Pg of the ignition plug P, the end terminal Pt must be inserted deep within the high voltage terminal
110
for the connection to be sufficiently attained. However, if, for example, under the condition where the rubber boot
100
is engaged with the insulator Pg, and insertion of the end terminal Pt into the terminal
114
is shallow and their engagement is insufficient, there is a risk of accidental firing of the ignition plug or stoppage of engine due to a faulty electrical connection between the high voltage terminal
110
and the end terminal Pt. Even if the insertion of the end terminal Pt into the terminal
114
is not shallow, if the relative positions between the end terminal Pt and the terminal
114
are inadequate due to displacement or the like, the high voltage terminal
110
and the end terminal Pt may be abraded or vibrated by engine vibration and the like to cause unsatisfactory electric connection between the high voltage terminal
110
and the end terminal Pt, thereby providing a risk of accidental firing of the ignition plug or stoppage of engine.
In order to prevent the above drawbacks, it is necessary to provide improved dimensional precision of parts such as the rubber boot
100
, the high voltage terminal
110
, and the like, and improvement in precision of the assembly position of these parts, especially of the high voltage terminal
110
into the rubber boot
100
, thereby inviting the total increase in cost of this structure and loss of assembly efficiency.
Accordingly, in conventional constructions to ensure electrical connection between the high voltage terminal
110
and the end terminal Pt, there are devices using spring members, as shown in
FIG. 13
or FIG.
14
.
In a high voltage terminal
140
shown in
FIG. 13
, a stopper
144
projecting inwardly on a peripheral wall of the generally tubular shaped terminal part
142
is formed over the entire periphery of the terminal part. On the other hand, the spring member
146
is formed at one end to have a portion with a larger diameter than the intermediate portion of the spring. The high voltage terminal
140
is configured so that, by pushing the spring member
146
into the terminal part
142
, the enlarged diameter portion
146
a rides over the stopper
144
and is disposed on the opposite side of the stopper
144
, so that the spring member
146
is fixedly received within the terminal part
142
.
When an end terminal Pt is inserted in the terminal
142
of the high voltage terminal
140
, the spring member
146
is compressed and forced to be pressed to the end terminal Pt, thereby allowing the electrical connection between the high voltage terminal
130
and the end terminal Pt to be made with greater assurance.
Japanese Utility Model Laid-open Publication HEI 5-66891 and U.S. Pat. No. 5,340,323 (which corresponds to the Japanese document) are noted as showing techniques related to the high voltage terminal of FIG.
13
.
In a high voltage terminal
150
shown in
FIG. 14
, an insertion port
154
is formed on one side of the peripheral wall of the generally tubular terminal part
152
. On the other hand, the C-ring member
158
, which is clipped over the terminal
152
as shown in FIG.
14
and
FIG. 15
, is formed with a tongue piece
159
which can be inserted into the terminal part
152
through the insertion port
154
. According to this construction, by clipping the C-ring member
158
over the terminal part
152
and inserting the tongue piece
159
into the terminal part
152
from the insertion port
154
, the tongue piece
159
is inserted into a gap between the pitch of the spring member
156
to hold the end of the spring member
156
at a predetermined position in the terminal part
152
.
With this high voltage terminal
150
, in the same manner as in the situation of
FIG. 13
, when an end terminal Pt is inserted in the terminal part
152
, the spring member
156
is compressed and forced in a manner to be pressed to the end terminal Pt, thereby allowing a more positive electric connection between the high voltage terminal
150
and the end terminal Pt.
Japanese Utility Model Laid-open Publication HE16-80295 and U.S. Pat. No. 5,421,736 (which corresponds to the Japanese document) are noted as showing techniques related to the high voltage terminal of FIG.
14
.
However, in the high voltage terminal
140
shown in
FIG. 14
, the other end of the spring member
145
projects outward from the opening of the terminal
142
in the non-compressed state, so that, upon inserting the end terminal Pt of the ignition plug P into the terminal
142
, the spring member
146
may be caught by the openin
Greenblum & Bernstein P.L.C.
Patel Tulsidas
Sumitomo Wiring Systems Ltd.
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