WO1989012745A1

WO1989012745A1 - Capacitive discharge ignition system for endothermic engines, preferably low-powered ones

Info

Publication number: WO1989012745A1
Application number: PCT/IT1989/000039
Authority: WO
Inventors: Astorre Biondi; Gianni Regazzi
Original assignee: Ducati Energia S.P.A.
Priority date: 1988-06-20
Filing date: 1989-05-23
Publication date: 1989-12-28
Also published as: IT1220902B; KR900702226A; IT8883422A0; AU3682189A; EP0422023A1; DE68917923T2; ATE110822T1; DE68917923D1; EP0422023B1

Abstract

Method of ignition for spark-fired endothermic engines, using a high-voltage generator device of the type having two capacitive windings paired together with the device using at least one recharging winding (1) of capacitor means (7) of the ignition system (C), and in which the charging voltage of said capacitor is induced by the flow variation provoked by the relative movement of magnetic means, and where said recharging winding (1) also alternatively carries out the function of secondary winding for high voltage, thus becoming a recharging winding with twin function.

Description

Capacitive discharge ignition system for cndoihcrmi engines. preferably low-powered ones.

The subject of the present invention is a capacitive discharge ignition system for endothermic engines, preferably low-powered ones.

The invention has a particular although not exclusive application for motor saws, lawn mowers, and all those small engines, generally low powered, which have a particularly small ignition system. However, this does not exclude application in various sectors in the ambit of the above-mentioned title, and is therefore not limited to low powered engines as this sector is only the preferential one. The capacitive discharge ignition systems commonly developed on two-pronged or three-pronged statoric irons and permanent magnet rotors are known in the present state of art, and these foresee a circuit of the type having three distinct windings: - a recharging winding of the ignition capacitor - a primary winding - a secondary winding.

The scope of the present invention is to eliminate one of said windings in order to further simplify the device and reduce the overall dimensions in particular. Another scope of the invention is to improve ihc efficacy of the ignition system. These and other scopes are achieved by the present invention. according to the characteristics given in the- attached claims, which solves the given problems by a method of ignition for spark-fired endothermic engines, using a high voltage generator device of the type having two inductive windings paired together; the device uses at least one recharging winding o f the ignition capacitor where the charging voltage of said capacitor is induced by the flow variation provoked by the relative movement of magnetic means, characterized by the fact that said recharging winding also alternatively carries out the function of secondary winding for high voltage, thus becoming a twin-funct ion, recharging winding. In this manner one winding is eliminated, the efficacy of the ignition is improved and the whole system simplified.

The proposed solution consists in the use of a "block" diode which is also able to operate at high voltage, connected to the recharging winding coil of the capacitor in such a way that it is possible to utilize the recharging coil of the same capacitor also as a high voltage coil, exploiting the respective inversion of polarity.

The advantages of this solution derive from: - the minimum overall dimensions of Ihc ignit ion, in that the bulky secondary winding is eliminated - the improved efficiency of the ignition, because there is no more dissipated power on the capacitor's recharging winding which feeds the sparking phase as there arc only two windings (the recharging one carries out the function of primary and secondary winding), as the present solution pairs the primary winding with the recharging winding having a twin function, cont rary to what occurs in the conventional capacitive discharge igni t ions which pair two windings during the sparking phase i .e. secondary one and recharging winding. The auxiliary circuitry to be connected with t he diode which can also operate on high voltage, at the winding o f said recharging coil which also has the function of secondary winding, will be such as to polarize said diode: - directly when the capacitor is charged, and - inversely when the capacitor discharges and the spark ing instant occurs. A possible diagram for said auxiliary circui try m ay ut i lize a capacitor element wound with controlled impedance as described in the Italian patent applications (IT-83490A/87-IT-83491 A/87) in the name of DUCATI ENERGIA, corresponding to ihc appl icat ion for international "PCT" patent (PCT/IT88/00039), which however docs not prevent the use of traditional components in said ci rcui ting, that is to say, the use of adequate separate induct ance and capacitive elements.

These and other advantages can be seen in the following detailed description of preferential solutions of real ization, together with the help of the attached drawings, the execution details of which are not to be held as limiting but only as examples. Figure 1 gives a view of one circuit of the invent ion, using the device as in the above-mentioned "PCT/IT88/00039". Figure 2 gives a view of an alternative less preferable ci rcuit realized with separate, adequate elements o f i nduc t ance and capacity used in the traditional techniques. 1

2 With reference to the above figures, it can be seen that the spark

3 plug's ignition system is marked with "C" . the twin-function,

4 recharging induced winding is marked with " 1 ", the diode which is

5 also able to operate on high voltage is marked with "2". and the

6 respective circuitry which is able to carry out the inductance

7 function is marked with "PV" and includes the primary winding

8 marked with "3-4-5-6/6" and capacity "7".

9 In Figure 1 said circuitry (PV) foresees the inclusion of a sole

I 0 integrated device which carries out a triple function:

I I - primary inductance and capacity (1=3-4-5-6-7)

1 2 - with a "TRIGGER" terminal (8) associated to the pair of voltage

1 3 dividing resistors (1 1-12) which control the "SCR" ( I I ) which 1 4 therefore acts substantially as a circuit breaker.

1 5 All the above works with the presence of a current rc-cycling

1 6 diode (9).

1 7 The circuitry solution (PV) in Fig.2 is substantially similar to that

1 8 in Fig. 1, but has a different design.

1 9 It is understood that the recharging winding ( I ) shall be

2 0 preferably coaxial to the primary one (^"3-4-5-6/6). thus forming a 2 1 sole coil with several coaxial windings.

2 2 Operation is as follows:

23 - the rotation of the magnet/s which arc solid with the rotor causes

2 4 a variation of the flow linked together with the winding having a

2 5 twin function (1) so as to originate on said winding a potential

2 6 which directly polarizes the diode which can also operate on high

2 7 voltage (2) with consequent charge of the capacitive means (7);

2 8 - the continuation of said rotation causes the inversion of the 2 9 potential on said winding, thus inversely polarizing the block diode (2); as this inversion is simult aneousl y present on the "TRIGGER" winding (8,...) too, it causes the start of the "SCR" by the corresponding resistive divider ( 1 1 - 12) in such a manner as to determine the discharge of said capacit ive means ( 7) on the primary inductance (3-4-5-6/6); - in these conditions the twin-function , recharging winding is magnetically paired with the primary winding system (3-4-5-6/6), which therefore has the function of secondary winding in this phase, and consequently a high potential sign is created which is such as to inversely polarize said block diode, which is also able to work on high voltage (2), in agreement wit h what has al ready been done by the potential induced in said winding by the flow variation provoked by the rotation of one or more magnets which are solid with the rotor.

Claims

CLAIMS 1. Method of ignition for spark-fired, cndothcrmic engines, using a high-voltage generator device of the type having at least two inductive windings paired together which can be actuated by magnetic flow variation, of which at least one is a recharging winding system (1) of capacitor means (7) of the ignition system (C), and in which the charging voltage of said capacitor is induced by the flow variation provoked by the relative movement of magnetic means, characterized by the fact that: - to said recharging winding system (1 ) also alternatively carries out the function of secondary winding for high voltage, thus becoming substantially a twin-funcl ion, recharging winding system which exploits the respective inversion of polarity on the block diode (2) by means of an associated circuit ( PV) which includes at least another paired winding system (3-4-5-6/6).

2. Ignition device for endothermic engines which operates with the method as per claim 1 , characterized by the fact that it includes: - at least one induced recharging winding of the ignition capacitor associated with a block diode (2) which is opcratively conceived to bear high voltage too, said diode being associated to circuit means (PV) which are able to provoke discharge of the capacitive means (7) on the primary inductance (3-4-5-6/6) through an "SCR" (10), thereby inducing on the recharging winding (1) a potential with polarity opposite to that necessary for the charging o f the capacitive means (7); - said induced, recharging winding/s (1) which carry out said twin function are coaxial to respective primary induction windings (3- 4-5-6/6) co-operates with said corresponding capacitive means (7).

3. Method, as per claim 1, utilizing an ignition device for endothermic engines as per claim 2, characterized by the fact that said circuit means (PV): - are able to provoke the discharge of the capacitive means (7) on the primary inductance (3-4-5-6/6) through an "SCR" (10), thereby inducing on the recharging winding (1) a potential with polarity opposite to that necessary for the charging of the capacitive means (7); - are such that said high-voltage diode is polarized: - directly when said capacitive means (7) arc charged, and - inversely when the capacitor discharges and the sparking instant occurs.

4. Method, as per claim 1, utilizing an ignition device for endothermic engines as per claim 2, characterized by the fact that said circuit means (PV): - are able to provoke the discharge of the capacitive means (7) on the primary inductance (3-4-5-6/6) through an "SCR" (10), thereby inducing on the recharging winding (1) a potential with polarity opposite to that necessary for the charging of the capacitive means (7); - include an integrated inductive and capacitive device (I), the inductive means (3-4-5-6/6) of which arc coaxially arranged with the respective capacitive means (7).

5. Method, as per claim 1 , utilizing an ignition device for endothermic engines as per claim 2, characterized by the fact that said circuit means (PV): - are able to provoke the discharge of the capacitive means (7) on the primary inductance (3-4-5-6/6) through an "SCR" ( 10), thereby inducing on the recharging winding (1 ) a potential with polarity opposite to that necessary for the charging o f the capacitive means (7); - include "TRIGGER" means (8) associated to resistive means ( 12-1 T) which control a respective "SCR" (10), and the whole of it being controlled by inversion of polarity through a recycling diode (9) of said inductive means (3-4-5-6/6).