EP0461082A2

EP0461082A2 - Wheel movable contact for internal combustion engine coil ignition system

Info

Publication number: EP0461082A2
Application number: EP91830217A
Authority: EP
Inventors: Luciano Di Sisto; Giovanni Maniglia
Original assignee: Sincros Md Srl
Current assignee: Sincros Md Srl
Priority date: 1990-06-04
Filing date: 1991-05-23
Publication date: 1991-12-11
Also published as: IT9020517A1; EP0461082A3; IT9020517A0; IT1248935B

Abstract

There is disclosed a movable contact construction, including a contact wheel, which has been specifically designed for improving the construction of the coil ignition system of internal combustion engines.

The contact construction comprises an electrically conductive body, in the inside of which there is arranged a movable contact electrically coupled to this body through resilient biasing means and a flexible bridging element, the movable contact cooperating with a fixed contact which is electrically insulated from the mentioned body and is electrically coupled to a plug-in element which can be accessed from the outside of the body, a driving element being moreover provided for operating the movable contact, which is driven by a cam element for electrically disconnecting it from the fixed contact.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a wheel movable contact for internal combustion engine coil ignition systems.
As is known, the coil ignition system or assembly is an electric component which is conventionally used on internal combustion engines for producing the high voltage which is necessary for providing the sparks for operating the spark plugs of the engine.
A coil ignition system usually comprises a high voltage distributor for the spark-plugs, and a low voltage current switch which power supplies a primary winding of the coil so that, as the electric current through the primary circuit of the coil is abruptely interrupted, a high voltage current is generated by induction in the secondary winding, which generated electric current is supplied to the distributor.
In conventional ignition coil systems, the switch or breaker element substantially comprises a breaker arm which is arranged on the body of the ignition coil assembly and which can be difficulty replaced, even if is subjected to a comparatively quick wear.
Devices are also known which are specifically designed for generating opening extra-currents by a related movement of a movable contact with respect to a fixed contact.
The movement of said movable contact, in particular, is conveniently counter-biased, by a resilient means, usually comprising a spring which, however, during the calibrating step of the device,can easily disengage from its seat or can be subjected to a deleterious lubricating effect.
In both cases, because of leakages of lubricating substances and/or dust, an insulating film can be formed between the parts provided for mutual contact, which negatively affects a proper operation of the ignition coil system.

SUMMARY OF THE INVENTION

Accordingly, the aim of the present invention is to overcome the above mentioned drawbacks, by providing a wheel movable contact for internal combustion engine coil ignition systems, which can advantageously replace the conventional breaker arm of the coil system breaker and which, moreover, can be applied on the ignition coil system body in a very quick and simple way.
Within the scope of the above mentioned aim, a main object of the present invention is to provide such a movable contact construction which is practically devoid of quick wear phenomena.
Another object of the present invention is to provide such a movable contact for coil ignition systems of internal combustion engines which is very reliable and safe in operation.
According to one aspect of the present invention, the above mentioned aim and objects, as well as yet other objects, which will become more apparent hereinafter, are achieved by a wheel movable contact for internal combustion engine coil ignition systems, characterized in that said movable contact comprises an electrically conductive tubular body, in the inside of which there are arranged a movable contact element electrically connected to said body through biasing resilient means and a flexible bridging element, said movable contact cooperating with a fixed contact which is electrically insulated from said body and is electrically coupled to a plug-in element which can be accessed from the outside of said body, there being moreover provided an actuating element acting on said movable contact which can be driven by a cam element for disengaging said movable contact from said fixed contact.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the wheel movable contact for internal combustion engine coil ignition systems according to the present invention will become more apparent from the following detailed disclosure of a preferred, though not exclusive, embodiment thereof, which is illustrated, by way of an indicative but not limitative example, in the figures of the accompanying drawings, where:

Figure 1 is a perspective view illustrating the movable contact construction according to the present invention;
Figure 2 is a longitudinal cross-sectional view of the movable contact according to the invention;
Figure 3 is a vertical cross-sectional view illustrating an actuating element, which can be driven by a cam element, included in the movable contact construction according to the present invention; and
Figure 4 is a cross-sectional view of the movable contact taken at the region thereof where a movable contact element and a fixed contact element operate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the figures of the accompanying drawings, the movable contact construction according to the present invention, which has been overally indicated at the reference number 1, comprises a hollow body 2, made of an electrically conductive material which has, preferably, a substantially cylindric shape.
At one end thereof, the hollow body is closed by a plug element 3 which axially defines a guiding seat 4, for a stem 5 which supports a movable contact element 6.
Said movable contact element is turned to and cooperates with a fixed contact element 7 which has a hollow configuration, also preferbaly of cylindric shape, and being housed in that portion of the body 2 which is opposite the portion thereof closed by said plug element.
Between the fixed contact element and the bottom of the body 2, moreover, there is provided an electrically insulating material cap 8.
To the fixed contact element 7 there is electrically coupled a plug-in element 9 which projects from the body 2 through the interposition of an electrically insulating sheath 10.
The movable contact element 6, in particular, is resiliently urged against the fixed contact element 7 by a first spring 11, operating between the plug 3 and said movable contact element, said first spring also operating as an electrically connecting element between the movable contact element and hollow body 2.
In order to improve and make more efficient this electrical connection, there is provided a flexible bridging element 12 which encompasses said first spring, in its axial direction, and which, practically, interconnects the movable contact element and the plug 3 so as to provide a flexible type of connection.
In order to further improve the electrical connection to the ground, an auxiliary spring 13 is furthermore provided, which is arranged about the stem 5 and operates between the central portion of the plug 3 and the end-piece 6a of the movable contact element 6.
The aforesaid stem 15, which supports the movable contact element 6, extends through a hole 14 which is coated by an electrically insulating material and is formed along the axis of the fixed contact element 7.
The stem projects from the axial end portion of the body 2 where a ring-nut 15 is arranged, provided with an end piece 16 defining an axial hollow 17 therein there is slidably restrained an actuating element, overally indicated at the reference number 18.
In this connection it should be pointed out that in the hole 14 which slidably receives the stem 5 there is arranged coaxially a supporting element 19 which has a substantially frustum of cone shape configuration.
This coaxial element restrains, by its top edge, an 0-ring 20 adapted to seal the holes from grease, dust and the like.
Said actuating or driving element 18 is provided with a rod-like body 21 which is slidably housed in the axial hollow 17, and being counter-biassed by a cup spring 22, operating between a shoulder 23 of the rod body and the bottom of the guide.
This cup spring, in particular, can be restrained, by its end turns, respectively, in a slot 24 which is circumferentially formed with respect to said rod like body, and against an abutment 25 formed between the ring-nut 15 and related end-piece 16.
Accordingly, said rod-like body can not disengage from its axial sliding hollow and, accordingly, fall on the ground or on the working table so that it is always held in a perfect clean condition.
At its end portions arranged inside said sliding hollow, the rod-like body contacts the stem 15 so as to cause the latter to be reciprocately driven, thereby electrically disengaging the movable contact element from the fixed contact element, against the biassing of the two coaxial springs 11 and 13.
At the end of the rod-like body 21, on the outside of the axial hollow 17 there is provided an idle or cam following small roller 26, which engages by contact with a cam element arranged on the shaft of the ignition coil assembly.
This roller, because of the rotary movement of the cam, causes the rod-like body 21 to reciprocate which in turn causes the movable contact element to quickly disengage from the fixed contact element with a consequent interruption of the low-voltage current, that is that current which circulates through the primary winding of the ignition coil assembly.
It should be pointed out that the calibrating of the spacing between the movable contact element and fixed contact element is carried out at the start of the assembling operations and, accordingly, the hollow body defining the operating contact cartridge is conveniently coated so as to present a continuous tight surface.
As shown, on the rod-like body 21 there is provided a diametrical pin 27 which is housed in a slot 28 defined by the end piece 16, in order to prevent the rod-like body from rotating about its pivot axis, so that the roller 26 will always properly engage with the cam mounted on the shaft of the ignition coil assembly.
During the assembling procedure, the disclosed wheel movable contact construction, or roller, will be applied on the ignition coil assembly casing so as to abruptely interrupt, as the cam element is turned, the contact on the primary winding or circuit thereby providing the desired voltage variation, owing to the conventional magnetic induction effect, through the secondary winding of the coil.
From the above disclosure and the figures of the accompanying drawings it should be apparent that the invention fully achieves the intended aim and objects.
While the invention has been disclosed and illustrated with reference to a preferred embodiment thereof, it should be apparent that the disclosed embodiment is susceptible to several modifications and variations all of which will come within the spirit and scope of the appended claims.

Claims

A wheel movable contact for internal combustion engine coil ignition systems, characterized in that said movable contact comprises an electrically conductive tubular body, in the inside of which there are arranged a movable contact element electrically connected to said body through biassing resilient means and a flexible bridging element, said movable contact cooperating with a fixed contact which is electrically insulated from said body and is electrically coupled to a plug-in element which can be accessed from the outside of said body, there being moreover provided an actuating element acting on said movable contact which can be driven by a cam element for disengaging said movable contact from said fixed contact.
A wheel movable contact construction, according to Claim 1, characterized in that said resilient means comprise a first spring, operating between a closure cover of said body and said movable contact element, and an auxiliary spring, coaxially arranged inside said first spring, said springs resiliently urging said movable contact element against said fixed contact.
A wheel movable contact construction according to claims 1 and 2, characterized in that said flexible bridging element axially encompasses the outer spring.
A wheel movable contact construction according to one or more of the preceding claims, characterized in that said closure cover is provided with a guide seat for said stem supporting said movabloe contact element.
A wheel movable contact construction according to one or more of the preceding claims, characterized in that said fixed contact has a substantially hollow cylindric shape, said fixed contact being housed in said body through the interposition of an electrically insulating material cap.
A wheel movable contact construction according to one or more of the preceding claims, characterized in that said stem axially extends through an electrically insulated hollow of said fixed contact element and projects from said body with an end piece provided with an axial hollow in which the actuating or driving element is slidably housed.
A wheel movable contact construction according to one or more of the preceding claims, characterized in that in said hollow in which said stem slides there is coaxially arranged a supporting element having a substantially frustum of cone shape,said coaxial element restraining, by its top edge a sealing 0-ring.
A wheel movable contact construction according to one or more of the preceding claims, characterized in that said actuating or driving element comprises a rod-like body which is slidably housed in said hollow and is adapted to contact said stem, at the end of said rod-like body arranged outside of said end piece there being arranged a cam follower roller adapted to engage with a cam element.
A wheel movable contact construction according to one or more of the preceding claims, characterized in that said rod-like body is counter-biassed by a cup spring operating between a shoulder of said rod-like body and the bottom of the guide, said cup spring being restrained, by its end turns, in a slot circumferentially formed on said rod-like body at said shoulder and against an abutment formed between the ring-nut and related end piece.
A wheel movable contact construction according to one or more of the preceding claims, characterized in that said construction further comrpises on said rod-like body a diametrical pin which is driven within diametrical slots formed through said end-piece in order to prevent said rod-like body from turning.
A wheel movable contact construction according to one or more of the preceding claims, characterized in that said hollow body is coated so as to provide a tight continuous type of outer surface.