GB2252454A

GB2252454A - Ignition coil for an internal combustion engine

Info

Publication number: GB2252454A
Application number: GB9126558A
Authority: GB
Inventors: Maurizio Marcuzzi
Original assignee: Industrie Magneti Marelli SRL; Magneti Marelli SpA
Current assignee: Industrie Magneti Marelli SRL; Marelli Europe SpA
Priority date: 1990-12-27
Filing date: 1991-12-13
Publication date: 1992-08-05
Anticipated expiration: 2011-12-13
Also published as: GB9126558D0; FR2673981B3; FR2673981A3; IT9053454U1; GB2252454B; IT220769Z2; DE9114575U1; IT9053454V0

Abstract

An ignition coil for mounting on a spark plug of an internal combustion engine comprises an insulating container (2) in which a primary winding (4) and a secondary winding (6) are disposed. The container (2) has an aperture (2b) in which there is mounted an insulating support member (13) bearing a conductor member (18) acting as an output terminal. A semiconductor diode (16) connected between the secondary winding (6) and the output conductor member (18) is housed within this support member (13). <IMAGE>

Description

IGNITION COIL FOR AN INTERNAL COMBUSTION ENGINE The present invention relates to ignition coil units for use in internal combustion engines. Particularly, it relates to such units for use in engines with an ignition plant and electronic distribution.

The invention relates more specifically to an ignition coil unit of the type known as "plug-top", i.e. adapted to be mounted directly on a respective spark plug, and comprising an insulating container, typically a substantially tank-shaped insulating container in which a primary winding and a secondary winding are housed. The container bears means for connecting the secondary winding to an associated spark plug.

The connecting means comprise a support member of insulating material traversed by at least one output conductor member and inserted, usually with the interposition of a sealing ring, in a corresponding aperture provided in the container.

According to the invention, a semiconductor diode is disposed between the secondary winding and the output conductor member in an ignition coil unit of the above type.

The diode is disposed in a housing provided in the support member of the connection means. The empty spaces in the container are normally filled with an electrically insulating material typically cast in liquid phase and then solidified and conveniently, the aperture in which the output conductor member is mounted is at or beyond the boundary of the insulating material.

The invention will now be described by way of example, and with reference to the accompanying drawings wherein: Figure 1 is a sectional view of an ignition coil unit according to the invention; and Figure 2 is an axial section through a connecting member acting as an output terminal for an ignition coil of the invention.

In Figure 1 an ignition coil comprises a substantially tank-shaped body 2 of electrically insulating material. A bobbin 3 on which the primary winding 4 of the coil is wound is positioned centrally in this body. A further bobbin 5 on which the secondary winding 6 is wound is disposed about the bobbin 3 and the winding 4. The magnetic core of the coil, formed by packs of laminations enclosed in a frame 8, is shown overall by 10. These laminations extend within the bobbin 3 passing through a central aperture 2a provided in the wall of the container 2.

At one end the body 2 forms an integral input connector shown by 11 having a pair of connection members in the form of lamellar pins only one of which, shown by 12, can be seen in Figure 1. These connection members are connected in a known manner in the container 2 with the primary winding 4 and the secondary winding 6 of the coil.

On the side opposite to the connector 11, the container 2 has a substantially cylindrical aperture 2b in which a substantially tubular support member 13 of electrically insulating material is positioned. This member has a first axial tubular portion 13a facing the container 2 and a second axial tubular portion 13b having a greater inner diameter so as to form a shoulder shown by 14 with respect to the portion 13a.

A housing 15 in which a semiconductor diode 16 is disposed is formed in the first tubular portion 13a of the member 13. This diode has a first connector 16a which extends through an end passage 17a of a drilled end baffle 17 of the tubular portion 13a. During assembly, the diode 16 is inserted into the member 13 via the tubular portion 13b thereof and is held there by the baffle 17 once it has been disposed in the housing 15.

An output conductor member, also of substantially tubular shape, is shown by 18 and has an external annular projection 18a in its median portion. During assembly the member 18 is inserted in the support member 13 via the passage formed in its tubular portion 13b and is positioned as shown in Figure 1 with the projection 18a abutting against the shoulder 14.

The second connector 16b of the diode 16 extends through the output conductor member 18 and is soldered thereto at 18b.

The member 13, acting as a high voltage output terminal, has a jacket 13c about the tubular portion 13a, which jacket is also of tubular shape and has an external groove 19 in which a sealing ring 20 is disposed. The jacket portion 13c of the member 13 is inserted in the aperture 2b of the container 2 and the connector 16a of the diode 16 is connected to the output terminal of the secondary winding 6 within this container. This diode makes it possible to prevent inverse currents which could cause out of phase ignition of the cylinders of the internal combustion engine.

During assembly, the support member 13, already provided with the diode 16 and the output conductor member 18, is threaded into the aperture 2b of the container. After positioning the bobbins 3 and 5 in this way in the container 2, the windings borne by these bobbins may be connected by soldering to the input terminals 12 and to the connector 16a of the diode 16.

When this operation is complete, the empty spaces in the container 2 are filled with electrically insulating material, for instance a resin, cast in liquid phase and then solidified. During this stage the sealing ring 20 of the support member 13 prevents this material from being drawn externally.

In the embodiment of Figure 2, the support member 13 is further provided with two end projections 30 adapted to be connected to appropriate seats provided in the container 2, thereby forming a coupling of the bayonet type between the member 13 and this container.

The member 13 has a perimetral groove 40 for the engagement and retention of the end edge of a tubular member 50 of electrically insulating material, preferably elastomer material, whose remote end is adapted to be fitted on a spark plug of the internal combustion engine in the manner disclosed, for instance, in Italian Patent Application 53058 B/89. In the tubular member 50 a conductor member 60 extends in a known manner and is formed, in the embodiment shown, as a helical spring for the electrical connection of the output conductor member 18 of the ignition coil and an associated spark plug of the internal combustion engine.

The conductor member 60 extends within the tubular portion 13b of the support member 13 in contact with the output conductor member 18.

The embodiments described above are particularly advantageous in automating the mounting of the semiconductor diode in the output terminal of the ignition coil.

Claims

1. An ignition coil unit for mounting on a spark plug of an internal combustion engine comprising an insulating container housing a primary winding and a secondary winding, and bearing means for connecting the secondary winding to a spark plug, the connecting means comprising a support member of insulating material traversed by at least one output conductor member mounted in an aperture in the container, a semiconductor diode being disposed between the secondary winding and the output conductor member, which diode is disposed in a housing provided in the support member of the connecting means.

2. An ignition coil unit according to Claim 1 wherein the empty spaces in the container are filled with an electrically insulating material, and wherein the aperture in which the output conductor member is mounted is at or beyond the boundary of the insulating material.

3. An ignition coil unit according to Claim 1 or Claim 2 wherein the support member comprises a first axial tubular portion facing the container, in which the diode is housed, which first tubular portion has on the side facing the container, retention means adapted to retain the diode and forming a passage through which a connector from the diode extends into the container, and a second axial tubular portion facing the opposite side of the container and separated from this first portion by transverse stop means adapted to allow, during assembly, the introduction of the diode into the first tubular portion and against which abuts the output conductor member which is introduced, during assembly, into the support member from the side of its second tubular portion.

4. An ignition coil unit according to Claim 3 wherein the retention means comprises a drilled baffle rigid with the first tubular portion of the support member.

5. An ignition coil unit according to Claim 3 or Claim 4 wherein the transverse stop means comprise a shoulder formed between the tubular portions of the support member and against which an external peripheral projection of the output conductor member abuts.

6. An ignition coil unit according to any of Claims 2 to 5 wherein the support member has, about the first tubular portion, a tubular jacket inserted in the corresponding aperture of the container, the jacket having an external groove in which a sealing ring is disposed.

7. An ignition coil unit according to any preceding Claim wherein the output conductor member has an axial passage in which the other connector of the diode is positioned and soldered.

8. An ignition coil unit according to any preceding Claim wherein the support member and the corresponding aperture of the container are provided with coupling means of the bayonet type.

9. An ignition coil unit substantially as described herein with reference to the accompanying drawings.