GB2231729A

GB2231729A - An ignition coil for an internal combustion engine

Info

Publication number: GB2231729A
Application number: GB9009756A
Authority: GB
Inventors: Gianfranco Ghilardi; Maurizio Marcuzzi
Original assignee: Industrie Magneti Marelli SRL; Magneti Marelli SpA
Current assignee: Industrie Magneti Marelli SRL; Marelli Europe SpA
Priority date: 1989-05-02
Filing date: 1990-05-01
Publication date: 1990-11-21
Also published as: GB9009756D0; FR2648519A3; DE9004829U1; ES1014187Y; FR2648519B3; ES1014187U

Abstract

An ignition coil (1) for an internal combustion engine includes a casing (5) in which a primary winding and a secondary winding (7, 9) are located coaxially with each other. The casing is filled with an electrically insulating resin 18 which is poured into the casing in a liquid state and then solidified. The casing (5) carries means (13, 14, 12b) for connecting the primary and secondary windings (7, 9) to an external control circuit and to an associated sparking plug, respectively at least one such means being below the level of the insulating material. The connection means comprise an element of insulating material (13) through which one or more connecting conductor members (14, 12b) pass and which is arranged in a corresponding aperture (5c) in the casing (5) with the interposition of a sealing ring (17) to prevent the resin leaking out while still liquid. <IMAGE>

Description

An ignition coil for an internal combustion engine The present invention relates to an ignition coil, particularly for use in an internal combustion engine having an ignition system with electronic distribution.

More specifically, the invention relates to an ignition coil of the type which is intended to be mounted directly on a respective spark plug and includes a substantially tank-shaped insulating casing provided with support means carrying a primary winding and a secondary winding which are coaxial with each other, the casing carrying first and second connection means connected to the primary winding and to the secondary winding to enable their connection to an external control circuit and to the associated sparking plug respectively, the empty spaces in the casing being filled with an electrically-insulating material which is poured in the liquid state and then solidified.

The ignition coil according to the invention is characterised in that the first and/or second connection means comprise a support element of insulating material through which one or more connecting conductor members pass in a sealed manner and which is arranged, with the interposition of a sealing ring, in a corresponding aperture provided in the casing below the level that the electricallyinsulating material which is poured in the liquid state is intended to reach.

According to a further characteristic, the insulating support element has a radial appendage which is urged against an internal stop surface of the casing when the element is in its mounted condition.

The sealing ring between the insulating support element and the casing may conveniently be arranged in a peripheral groove in the support element.

The support element may conveniently be cup-shaped and arranged in the corresponding aperture in the casing with its concavity facing outwardly.

In order for the secondary winding to be connected to the associated sparking plug, the insulating support element may conveniently be shaped so as to define a seat for housing a first end of a tubular element of flexible insulating material, the other end of which is intended to be fitted onto the associated plug, connecting conductor means being provided in the tubular element for electrically connecting the conductor member carried by the support element to the plug.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows an ignition coil according to the present invention mounted directly on a sparking plug of an internal combustion engine, Figure 2 is a partial section of a coil according to the invention, on an enlarged scale, Figure 3 is an electrical diagram of the ignition coil, Figure 4 is a partial section of a coil according the invention, Figure 5 is a section taken on the line V-V of Figure 4, Figure 6 is a perspective view of another ignition coil for an internal combustion engine, according to the present invention, Figure 7 is a partially-sectioned view taken on the line VII-VII of Figure 6, Figure 8 is an electrical diagram of the ignition coil of Figures 6 and 7, Figure 9 is a partial section taken on the line IX-IX of Figure 7, and Figure 10 is a view similar to that of Figure 9, with a support element carrying connection terminals of the coil in a different orientation.

Figure 1 shows an ignition coil 1 mounted on an associated plug 2 in a recess 3 in the body 4 of an internal combustion engine.

As can be seen in Figure 2 in particular, the coil 1 includes a substantially tank-shaped body 5 of electrically-insulating material. A spool 6 is positioned centrally within the body and the primary winding 7 of the coil is wound thereon. A further spool 8, on which the secondary winding 9 is wound, is arranged around the spool 6. The magnetic core of the coil, indicated 10, is formed by packs of plates enclosed in a frame 11 with their central arms extending inside the spool 6. With reference to Figure 2, the central arm of the lower pack of plates extends into the spool 6 and passes through a central aperture 5a in the base wall of the casing 5.

In the embodiment of Figure 2, a recess 5b is formed at one end of the body 5 with its mouth facing downwards.

Two connection members 12a, 12b, only the second of which is visible in Figure 2, are fixed in the recess.

In the embodiment illustrated, the connection members are in the form of flat pins and the ends of the primary winding and one end of the secondary winding 9 are connected thereto in the manner illustrated in the diagram of Figure 3.

With reference again to Figure 2, at the opposite end from the recess 5b, the casing 5 has a substantially cylindrical aperture Sc in which a substantially cupor beaker-shaped support element 13 of electrically-insulating material is located. A connecting conductor member 14 extends through the base wall of the support element 13 and its end which faces into the casing 5 is connected to a conductor plate 15 connected to one end of the secondary winding 9 which represents the high-tension output of the coil.

The support element 13 has an external peripheral groove 13a in which a sealing ring 17 that cooperates with the surface of the wall of the aperture Sc in the casing is located.

The support element 13 also has an outer radial appendage 13b which is urged against an internal stop surface 16 of the casing 5 when the element is in its mounted condition.

During assembly, the support element 13, already provided with the connection member 14 and the plate 15, is fitted into the aperture Sc in the casing from the inside and its radial appendage 13b is brought into abutment with the stop surface 16, as shown in Figure 2. After the spools 6 and 8 have been positioned in the casing, the windings carried thereby can be soldered to the input terminals 12a and 12b and to the output terminal 14 according to the diagram of Figure 3.

Upon completion of this operation, the empty spaces in the casing 5 are filled with electrically-insulating material 18 (for example, a resin) which is poured in the liquid state and then solidified. The sealing ring 17 of the support element 13 prevents this material from leaking out.

Figures 4 and 5 show a variant according to which the input contacts 12a, 12b are also carried by a substantially cup-shaped support element 20 arranged in a cylindrical aperture 5d in the casing 5. In this case, the support element 20 also has an external peripheral groove 20a in which a sealing ring 21 is located (Figure 4). The support element 20 may conveniently be formed with a radial appendage 20b which is urged against a stop surface 5e of the casing (Figure 4) in the mounted condition.

The solution shown in Figures 4 and 5 is particularly advantageous in that, when the coil is manufactured, the positions of the terminals 12a-, 12b can be varied according to requirements as regards space and the fitting of the coil. In fact, it should be remembered that, in order for the coil to be connected to the ignition control unit, a connector, such as that indicated C in Figure 4, from which a connecting cable d extends, must be coupled to the terminals 12a and 12b.Since the terminals 12a, 12b can be arranged in any desired position in the place of manufacture of the coil, the coil can be formed so that, when it is mounted, the connector C and cable d are oriented in the most convenient manner, for example according to the characteristics of the engine on which the coil is to be mounted, without the need to alter the geometry of the coil or a part thereof.

With reference again to Figure 2, the cavity of the element 13 which carries the high-tension output terminal 17 defines a seat 30 in which is engaged one end 31a of a tubular element 31 of flexible, electrically-insulating material the other end of which is intended to be fitted onto the plug in the manner illustrated in Figure 1. The tubular element 31 is fixed to the casing 5 of the coil by means of a clamping member provided with spring engagement appendages 33 having end retaining teeth which engage in corresponding recesses in the casing 5.

In known manner, conductor members for connecting the output terminal 14 of the coil to the plug extend within the tubular sheath 31.

In ignition coils of the type described above, an end connector of a cable for connection to ignition control circuits is coupled to the flat pins or similar members 12a, 12b in use.

In certain circumstances, it may be convenient or necessary for the cable and connectors to be oriented in a certain direction (relative to the body of the device) and this means that the electrical terminals must be arranged correspondingly in a certain way.

In order for the same coil to be used in other circumstances, however, it may be convenient for the cable and the connectors to be oriented in another direction and hence for the terminals of the device to be arranged differently.

In order to satisfy these different requirements, it was necessary, according to the prior art, to provide different models of the same ignition coil, the terminals in each model being oriented differently.

Figures 6 to 10 show a coil produced so as to satisfy all these different requirements.

Figure 6 shows an ignition coil 1 for an internal combustion engine having an ignition system with electronic distribution, particularly intended for mounting near the sparking plug with which it is associated.

As can be seen with particular reference to Figure 7, the ignition coil illustrated includes a substantially tank-shaped casing 5 in the centre of which is arranged a hollow spool 6 with the primary winding 7 wound thereon. A further spool 8, on which the secondary winding 9 is wound, is arranged around the spool 6 and its winding.

The primary winding 7 is connected to electrical terminals 12a, 12b (only one of which is visible in Figure 7) carried by a cup-shaped support element 20 inserted sealingly in an aperture 5a of complementary shape in the casing 5. As can be seen from Figures 9 and 10, the aperture 5a in the casing 5 and the support element 20 are conveniently circular in cross-section so that the support element 20 can in fact be positioned in a plurality of angular positions relative to the casing 5, for example, in the two positions showin in Figures 9 and 10.

The ends of the primary winding 7 are connected to the terminals 12a, 12b according to the diagram of Figure 8, in known manner, for example by soldering. One end of the secondary winding 9 can also be connected to the terminal 12b, according to the diagram of Figure 8, whilst the other terminal of the secondary winding is connected to a high-tension output terminal, not shown in Figures 6 and 7, intended to be connected to the associated sparking plug of the engine.

In known manner, the ignition coil illustrated also includes a magnetic core formed by packs 10 of plates enclosed in a frame-like structure 11. As can be seen from Figures 6 and 7, the central arms of the packs of plates extend inside the spool 6. With reference to Figure 7, the central arm of the lower pack of plates, in particular, projects towards a central aperture 6b formed in the base wall of the casing 5, facing the spool 6.

The support element 20 carrying the terminals 12a and 12b has an external peripheral groove 22 in which is arranged a sealing ring 21 which is urged against the wall of the aperture 5a in the casing 5.

In the embodiment illustrated, the support element 20 also has an outer radial appendage 20a (Figure 7) which is urged against an internal stop surface Sc of the casing in the mounted condition. During assembly, the cup-shaped support element 20 is inserted downwardly into the casing from above and the appendage 20a is brought into abutment with the stop edge 5c of the casing. The cup-shaped element 20 is then oriented in the desired position, that is, so that the terminals 12a, 12b previously fixed therein are oriented in the manner most suitable for the required orientation of the connector and the cable which will be coupled to the terminals in the condition of use.

The connections between the windings and the terminals are then made and, once this operation is completed, the casing 5 is filled with an electrically-insulating material (for example, a resin) which is poured in the liquid state and the solidified. This material is indicated 18 in Figure 7.

As the casing 5 is being filled with the insulating material, the sealing ring 21 prevents the material from leaking between the cup-shaped support element 20 and the associated aperture 5a in the casing 5.

In Figure 6, an end connector of a connecting cable 26 is indicated 25 and is intended to be coupled to the terminals 12a, 12b of the ignition coil. In Figures 9 and 10, the connector 25 and the cable 26 are shown in broken outline: as can be seen from these Figures, the connector 25 and the cable 26 can be oriented in the most convenient direction for the condition of use by arranging the support element 20 carrying the terminals 12a, 12b in an appropriate orientation during the production of the coil.

Claims

1. An ignition coil for an internal combustion engine, of the type intended to be mounted on a respective sparking plug and including a substantially tank-shaped insulating casing provided with support means carrying a primary winding and a secondary winding which are coaxial with each other, the casing carrying first and second connection means connected to the primary winding and to the secondary winding to enable their connection to an external control circuit and to the associated sparking plug respectively, the empty spaces in the casing being filled with an electricallyinsulating material which is poured in the liquid state and then solidified, in which the first and/or second connection means comprise a support element of insulating material through which one or more connecting conductor members pass and which is arranged, with the interposition of a sealing ring, in a corresponding aperture provided in the casing below the level that the insulating material which is poured in the liquid stated is intended to reach.

2. An ignition coil according to Claim 1, in which the insulating support element has a radial appendage which is urged against an internal stop surface of the casing when the support element is in its mounted condition.

3. An ignition coil according to Claim 1 or Claim 2, in which the sealing ring is arranged in a peripheral groove in the support element.

4. An ignition coil according to any one of the preceding claims, in which the insulating support element is substantially cup-shaped and is arranged in the corresponding aperture in the casing with its concavity facing outwardly.

5. An ignition coil according to Claim 4, in which, for the connection of the secondary winding to the associated sparking plug, the cavity of the support element associated with the secondary winding defines a seat for housing a first end of a tubular element of flexible insulating material the other end of which is intended to be fitted onto the plug, connecting conductor means being provided in the tubular element for the electrical connection of the conductor member carried by the support element to the plug.

6. An ignition coil according to any one of the preceding claims, in which the first and/or second connection means comprise a support element of insulating material through which one or more connecting conductor members pass sealingly and which is inserted sealingly in a corresponding aperture of complementary shape in the casing, the insulating support element and the corresponding aperture in the casing being shaped so as to enable the support element to be positioned in at least two predetermined relative positions.

7. An ignition coil according to Claim 6, in which the insulating support element and the corresponding aperture in the casing are circular.

8. An ignition coil according to Claim 6 or Claim 7, in which a sealing ring is interposed between the insulating support element and the corresponding aperture in the casing.

9. An ignition coil according to Claim 8, in which the sealing ring is arranged in an external peripheral groove in the insulating support element.

10. An ignition coil for an internal combustion engine, substantially as herein described with reference to, and as shown in, the accompanying drawings.