Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION
Field of the Invention:
The present invention relates in general to auto-
motive ignition systems, and more particularly to an
ignition transformer and spark plug cover assembly for
use in internal combustion engines.
Description of the Prior Art:
- Conventional ignition systems for internal combus-
tion engines have proven themselves to be reliable and
adequate for many years. In recent times these systems
have been upgraded by means of various electronic
switching apparata. However, even with the addition of
electronic apparata, the systems remain very similar in
operation to the conventional electromechanical
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systems. For example, current is introduced to an
ignition transformer primary winding coil from a
battery through a switch, such as a transistor. The
energy of the ignition current supplied via the switch
is accumulated as magnetic energy and discharged
through a secondary (high voltage) winding coil across
the electrodes of a spark plug.
Modern engines are required to meet a multitude of
ever-tightening standards regarding the quantity and
qualit~ of exhaust emissions. In order to meet these
requirements, engine manufacturers have resorted to
producing engines which operate under very lean
fuel-to-air mixtures and engines which employ strati-
fied charge or turbulent flow technology. Lean burning
engines require increased spark duration for proper
operation~ This is accomplished in the conventional
systems by increasing the open circuit spark voltage.
However, increasing the voltage results in an increase
in the amplitude as well as the duration of the spark
current which greatly decreases the life of the spark
plugs. In turbulent flow-type systems, the flow of the
charge within the individual cylinders of the engine
tends to blow out or ex-tinguish the spark plug arc
prematurely thereby decreasing the duration of the
spark which is detrimental to proper ignition.
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Another problem inherent in conventional designs
is that they generally use a common high-voltage gener-
ator in the form of a single ignition coil for all the-
spark plugs in the engine. The high voltage from the
single coil is then distributed to the various plugs by
means of a rotary high voltage switch or distributer
and a system of high voltage cables. The distribution
i and hlgh voltage cables are well-known to be frequent
( sources of problems and thus are the weak links in the
conventional system. --
SUMMARY OF THE INVENTION
-
Accordingly, one object of this invention is to
provide a novel AC igni-tion system wherein the duration
of ignition can be increased over that of a conven-
tional system without decreasing the life of the spark
plugs.
Another object of the present invention is to
provide a novel AC ignition system which eliminates the
need for a high voltage distribution system.
Still another object is to provide a novel igni-
tion system wherein a separate high voltage generator
is provided for each spark plug in the engineO
Yet another objective is to provide a novel igni-
tion transformer and spark plug cover assembly capable
of being securely mounted on an engine head immediately
adjacent a respective spark plugO
3~
Another object of this invention is to provide an
ignition system employing a novel transformer and spark
plug cover assembly of the above-noted type whereby it
is possible to reduce the size of the ignition coil and
yet maintain adequate energy discharge across the spark
plug electrodes.
Yet another object is to provide a novel AC igni-
tion system which produces an alternating current and
therefore an intermittent spark within the spark
plug~ In such an AC system, the duration of the igni-
tion can be greatly increased over that of the conven-
tional systems without a corresponding decrease in
spark plug life. Also, since the total ignition com-
prises a plurality of short intermittent sparks, the
blow-out problems of turbulent flow engines are greatly
reduced.
Still a further object of this invention is to
provide a novel ignition system which overcomes the
difficulties inherent in the conventional systems uti-
lizing a common high voltage generator by providing an
essentially independent high voltage generator system
for each spark plug in the engine.
These and other objects are achieved or facili-
tated in accordance with the invention by providing a
new and improved ignition transformer and spark plug
cover for an internal combustion engine, wherein
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separate ignition transformers are mounted in a respec-
tive such assembly and each assembly is mounted on an
engine head immediately adjacent a respective spark
plug and electrically connected thereto. This
eliminates most of the high voltage wiring, as well as
the distributor of the conventional ignition system
In a preferred embodiment, the assembly of the
invention includes a mounting base member adapted to be
fixedly fastened to the engine head, wherein the base
member includes connector receptacles for making elec-
trical connection thereto, a connector member mounted
on said base member and having connector contacts mat-
ing with respective receptacles of the base member, a
transformer assembly including an ignition transformer
mechanically connected to and supported by the connec-
tor member, and a cover member adapted for making elec-
trical connection to a respective spark plug, wherein
the cover member is electrically connected to the igni-
tion transformer by means of a short length high
tension conductor supported by the transformer
assembly.
According to a further broad aspect of the
present invention, there is provided an ignition trans-
former and spark plug cover assembly adap-ted for mounting
on an internal combustion engine for application of
ignition signals from an ignition circuit to a respective
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engine spark plug. The assembly comprises a connector
means fixedly fastened to the engine in close proximity
to said respective spark plug. A transformer assembly,
including an ignition transformer, is mechanically con-
nected to and supported by the connector means. Electri-
; cal connection means, including low tension conductors,
is provided for interconnecting the ignition circuit to
the ignition transformer. A high tension conductor
electrically interconnects the ignition transformer
with a respective spark plug through a spark plug cover
member associated with a respective spark plug.
According to a still further broad aspect of
the present invention, there is provided a method of
fabricating an igni-tion transformer and spark plug cover
assembly adapted for mounting on an internal combustion
engine for application of ignition signals from an ignition
circuit to a respective engine spark plug, wherein the
ignition transformer and spark plug cover assembly is
formed at least of connector means adapted to be electri-
cally connected to the ignition circuit by means of low
tension conductors and fixedly fastened to the engine in
close proximity to the respective spark plug. A trans-
former assembly is mechanically connected to and supported
by the connector means and includes an ignition transformer
and an insulating casing surrounding the ignition trans-
former. A cover member is adapted for making electrical
connection with the respective spark plug and includes a
high tension conductor connected to the ignition trans-
,
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former. The transformer assembly further includes a
first bobbin having a secondary winding wound thereon
and having a central bore in which a core member is
disposed. A second bobbin surrounds the first bobbin
and the secondary winding. The second bobbin has a
primary winding wound thereon. The method comprises
molding the first bobbin and winding the secondary wind-
; ing onto the first bobbin. The core is then inserted
into the bore and the second bobbin is molded onto the
first bobbin. The primary winding is then wound on thesecond bobbin and the-insulating casing is molded in
surrounding relation to the first and second bobbins.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention
and many of the attendant advantages thereof will be
readily obtained as the same becomes better understood
by reference to the following detailed description when
considered in connection with the accompanying drawings
illustrating an example of a preferred embodiment of the
invention, wherein:
FIGURE 1 is a side view of the ignition trans-
former and spark plug cover assembly of the invention
adap~ed for mounting on an engine block (this Figure is
out of sequence and appears on the sheet with Figures
6-8);
3~
FIGURE 2 is an enlarged~partially sectioned
view of FIGURE 1 showing the assembly according to
-the invention,
E'IGURE 3 is a cross-sectional view taken
along the lines 3-3 shown in FIGURE 2 of the connector
member of the assembly according to the invention'
FIGURE 4 is a cross-sectional view taken
along the lines 4-4 shown in FIGURE 5 of the base
member of the assembly according to the invention'
FIGURE 5 is a cross-sectional view taken
along the lines 5-5 shown in FIGURE 4 of the base
member of the assembly according to the invention'
FIGURE 6 is a perspective view of the base
member of the assembly according to the invention,
FIGURE 7 is a cross-sectional view taken
along lines 7 7 shown in FIGURE 2 of the assembly
according to the invention' and
FIGURE 8 is a circuit diagram illustrating
the electrical connections implemented by means of
the assembly according to the invention.
DESCRIPTION OF T~IE PREFERRED EMBODIMENTS
Referring now to the drawings, wherein like
reference numerals designate identical or corresponding
parts throughout the several-views, and more particu
larly to FIGURE 1 thereof~ in FIGURE 1 the assembly 10
of the invention is shown as including a base member
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100 securely fas-tened to an engine block 12, a connec-
tor rnember 200 mounted on the base member 100, a trans-
former assembly 300 mounted on the connector assembly
200, and a cover 400, including a high tension conduc-
tor 402 for making connection to the transformer
assembly 300 and a cover member 404 shown making an
electrical connection to a conventional spark ~lug 14
by means of a connector member (not shown~ making
electrical connection to a terminal (not shown) of the
spark plug 14.
In FIGURE 2, the assembly of the invention
is shown in more detail~ The high tension conductor
402 is shown as including an inner conductor 406
surrounded by an insulating layer 408. Conductor 402
is o~ conventional design.
Transformer assembly 300 includes an ignition
transformer 302 including a secondary winding 304
mounted on a first bobbin 306 and a primary winding
308 mounted on a second bobbin 310, The secondary
winding 304 as shown in FIGURE 2 is implemented in
nine series connected sections. Bobbins 306 include
a central bore 312 in which is disposed a core 314.
Electrical connection is made to the secondary winding
304 on one side thereof to the conductor 406 by means
of pin 316. The other side of secondary winding 304 is
electrically connected to a contact 204b of connector
member 200 by means of pin 318.
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Fabrication of transformer assembly 300
begins with molding of the bobbin 306 of a thermoplastic
material such as epoxy resin, polytetrafluoroethylene
(TEFLON ~, etc. Pins 316, 318 are integrally molded
into the bobbin 306. Secondary winding 304 is then
wound in plural sections on the bobbin 306 and spot
welded to the pins 316, 318. Core 314 is then inserted
in the bore of the bobbin 306. Thereafter, the second
bobbin 310 is integrally molded around the first bobbin
306 and core 314, with a pair of pins 319, 320 formed
therein for making spot welded electrical connection to
the primary winding 308 which is subsequently wound
around the bobbin 310. Thereafter, the conductor 406
of the high tension wire 402 is interconnected to the
pin 316 and a plastic case 322 is molded around the
ignition transformer 302.
FIGURES 2 and 3 show the structure of the
connecting member 200 and the interconnection thereof
with the transformer assembly 300 as above described.
Connector member 200 includes a molded plastic housing
202 defining hollow cavities 206, 208 separated by a
midsection 210. Integrally molded within the mid-
section 210 and supported thereby are three contact
members 204a, 204b~ and 204c. Contact
204a is connected to pin 319 connected to one side of
the primary winding 308 of the ignition transformer
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302 and con-tact 204c is connected to pin 320 connected
to the opposite side of the primary winding 308.
Contact 318 is connected to one side of the secondary
winding via pin 318. Although FIGURE 3 indicates that
pins 318, 319 and 320 are connected respec-tively to
contacts 204a~ 204b and 204c by means of a solder
joint, it should be understood that this interconnec-
tion can otherwise be made by means of conventional
male/female pin engagement.
As is evident from FIGURES 3 and 7, trans-
former assembly 300 and connector member 200 are each
provided with opposed flange members 326a, 326b and 210a,
210b, respectively, by which transformer assembly 300
and conneetor member 200 are mechanically interconnected.
This interconnection may be made by providing either
the flanges of the transformer assembly 300 or the
connecting member 200 with a threaded hole and the
other flanges with a mating opposing hole and screwing
the respective opposed flanges together. Otherwise ?
opposed holes can be drilled through the opposed
flanges and the flanges interconneeted by means of a
nut, bolt and lock washer assembly, not shown.
FIGURES 4, 5 and 6 illustrate the base
member 100 of the present invention. Base member 100
is formed of an integrally molded housing 102 having
receptacle members 104a, 104b and 104c which provides for
mating engagement with contac~s 204a, 204b and 204c,
respectively. The housing 102 defines three hollow
cavities 106a, 106b and 106c in which respective ends
of the receptacles 104a, 104b and 104c protrude, and
wherein mating engagement of the male contacts 204a,
¦ 204b and 204c with one end of a respective female
receptacle 104a, 104b and 104c is accomplished. The
other ends of receptacles 104a and 104c are connected
to an ingition circuit 500 as shown in FIGURE 8, while
the other end of receptaele 104b is grounded to the
engine body 12 as shown in FIGURES 4 and 5.
The ignition circuit 500 may be any of the
I ignition eireuits shown in U.S. Patent No. 4,382,430
issued on May 10, 1983 and U.S. Paten-t No. 4,446,842
issued on May 8, 1984. The eonneetions from the
ignition circuit 500 to the base member reeeptaeles
104a and 104e need not be made by a high tension
eonneetion, according to the invention, since the
signals on these wires are rela-tively low voltage and
low eurrent.
As is also shown in FIGURES 4 and 6, the
base member 100 is fastened to the engine bloek by
¦ means of flange members 110, 11~, eaeh having holes
formed therein by whieh the flange members 110 and
112, as well as the base member 100, can be screw
fastened to the engine body by means of screws 114,
llÇ. Optionally, a rubber boot (not shown) can be
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provided surrounding the flange members llU, 112 and
the lower portion of the base member 100 as shown in
FIGURE 4~ As shown in FIGURE 6, a protective covering
118 may be provided to protect the interconnection
between the conductors from the ignition circuit 500
to the receptacles 104a, 104c.
The above-described ignition transformer
and spark plug cover assembly is particulary
advantageous in providing a secure mechanical mounting
of an ignition transformer in immediate proximity to
a respective spark plug, whereby the ignition trans-
former is relatively uninfluenced by engine tempera-
ture. Furthermore, in view of the secure mounting
provided by the several screw fastenings of the
invention, the above-disclosed assembly is unaffected
by engine vibration. Further, by providing an
assembly which can be mounted in immediate proximity
to a respective spark plug it is possible to employ
relatively long length low tension conductors for
interconnecting the ignition circuit with each
transformer, while employing only relatively short
length high tension conductors for application of
the ignition voltage and current -to the spark plug.
Obviously~ numerous modifications and
variations of the present invention are possi.ble in
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light of the above teachings. For example, the
mounting and connection teachings of the invention
can readily be adapted to replace the transformer
302 above-described with the ignition transformers
disclosed in my above cross-referenced related
applications. It is therefore to be understood that
within the scope of the appended claims, the invention
may be practiced otherwise than as specifically
described herein.
