Electronic ignition device for internal combustion engines

Abstract

 The device comprises a first element provided with a permanent magnet (4) or (4′) having two pole pieces, and a second element provided with a magnetic core (1) or (1′) having two or three pole pieces; on a pole piece of the core (1) or (1′) there is wound a solenoid (6) or (6′) having one side connected to earth through a rectifier diode (15) and its other side, by way of a second rectifier diode (8), feeding a capacitor (10) which discharges through the primary winding (12) of a transformer; the secondary winding (13) of this latter feeds the spark plugs; that side of the capacitor (10) facing the diode (8) is connected to earth through a controlled diode (9); the diode (9) is rendered conducting by the triggering voltage generated by the same solenoid (6).

Description

[0001] This invention relates to an electronic ignition device of the type in which capacitor discharge is induced by a system consisting of a rotary part containing one or more magnets and a fixed part containing the capacitor charge winding, said winding also being used to trigger the controlled diode.

[0002] Known devices of this type generally use a specific controlled diode triggering system, known as a starter or pick-up, consisting of one or more suitably sized windings positioned in the fixed part of the system.

[0003] The object of the invention is to provide an ignition device completely of solid state type in which the controlled diode is triggered without the aid of a specific pick-up, and which is of simplified construction and therefore economical and reliable.

[0004] This object is attained by a device comprising one or more magnets rigid with a rotary part known as the rotor and facing a fixed part known as the stator and comprising suitably shaped magnetic cores, from the windings of which induced voltages are obtained whenever said rotor and stator are in a state of relative movement.

[0005] According to the invention, a winding acting as a capacitor charging coil is wound on a magnetic core of the stator and has one end connected to the anode of a rectifier diode, the cathode of which is connected to one plate of the capacitor, the second plate of which is connected to one end of the primary winding of the ignition transformer, the second end of which is connected to the second end of the capacitor charging winding by way of a second rectifier diode.

[0006] A resistor is connected to the intermediate point between the first end of the capacitor charging coil and the anode of the first rectifier diode, a control diode being connected to the common point between the cathode of the first rectifier diode and the capacitor plate and the common point between the end of the primary winding and the anode of the second rectifier diode, and having its grid connected to the common point between the second end of the charging coil and the cathode of the second rectifier diode by way of a resistor.

[0007] These and further operational and constructional characteristics of the invention will be apparent from the detailed description given hereinafter with reference to the figures of the accompanying drawings which illustrate some preferred embodiments thereof by way of non-limiting example

Figure 1a is a diagrammatic representation of the fixed part and rotary part;

Figure 1b is an embodiment alternative to that of Figure 1a;

Figure 2 is a further embodiment alternative to that of Figure 1a;

Figure 3 shows the basic schematic diagram of the invention;

Figure 4 shows the variation of the voltage V as a function of time t.

[0008] Figures 1a and 1b show a magnetic core 1 rigid with the engine crankcases and having three pole pieces so as to be of E-shape.

[0009] Said magnetic core 1 forms part of the fixed stator part which is faced by the rotating rotor part consisting of a flywheel 3, generally of aluminium, on which there is a permanent magnet 4 with two respective pole pieces 5. The flywheel 3 is generally keyed onto the internal combustion engine crankshaft and connected rigidly to it.

[0010] On the central pole piece of the magnetic core 1 there are wound a solenoid 6 forming the capacitor charging coil, and coils 12, 13 forming the primary and secondary windings of the ignition transformer.

[0011] The characteristics of the present invention also allow the primary and secondary windings to be mounted on a different magnetic core separate from the core 1.

[0012] The embodiment shown in Figure 1b differs from that shown in Figure 1a by the different shape and arrangement of the magnet 4 and pole pieces 5.

[0013] The alternative embodiment illustrated in Figure 2 shows a magnetic core 1′ rigid with the engine crankcase and forming part of the fixed stator, which is faced by the rotor formed from a flywheel 3 generally of magnetic steel, on which one or more magnets 4′ are located. The flywheel 3′ is generally keyed onto the engine crankshaft and is connected rigidly thereto.

[0014] The stator comprises a magnetic core 1 consisting of a substantially rectilinear lamination pack disposed along a chord, and about which the solenoid 6′ forming the capacitor charging coil is wound. Said magnetic core faces the rotor.

[0015] Generally, the ignition transformer 12, 13 forms part of an external unit sometimes also comprising the electronic components shown in the basic scheme of Figure 3.

[0016] From Figure 3 it can be seen that the coils 6 or 6′, 12 and 13 shown in Figures 1 and 2 are connected together and to the other electronic components of the device.

[0017] The solenoid 6 or 6′ forming the charging coil for the capacitor 10 has one end connected to the anode of the rectifier diode 8 and its other end connected to the cathode of the rectifier diode 15, these diodes participating in the charging of the capacitor 10, of which one plate is connected to the cathode of the diode 8 and the other plate to one end of the primary winding 12, the other end of which is connected to earth.

[0018] The circuit formed by the winding 6, the diode 8, the capacitor 10, the primary winding 12 and the diode 15 represents the charging circuit for the capacitor 10.

[0019] From Figure 3 it can further be seen that the first end 19 of the solenoid 6 is also connected to one end of the resistor 16 the other end of which is connected to earth, and that the second end 20 is also connected to one end of the resistor 17, the second end of which is connected to the grid of the controlled diode 9.

[0020] The circuit formed from the solenoid 6 or 6′, the resistor 17, the grid-cathode junction of the controlled diode 9 and the resistor 16 represents the trigger circuit for the controlled diode 9.

[0021] The circuit formed from the capacitor 10, anode-cathode junction of the controlled diode 9 and the primary winding 12 represents the discharge circuit for the capacitor 10.

[0022] The windings 12 and 13 together with the pole piece acting as the core form the ignition transformer 11, the secondary 13 of which is connected to the spark plug 14.

[0023] The device operates as follows, with reference to Figures 3 and 4: by way of the rectifier diode 8, the primary winding 12 and the rectifier diode 15, the voltage induced in the solenoid 6 or 6′ charges the capacitor 10 on the appearance of the rising front of the, with respect to the terminal 20, positive half-wave 18 at the terminal 19 of the winding 6.

[0024] The charge voltage of the capacitor 10 is indicated by 22.

[0025] Then during the half-wave 21 the voltage at the terminal 19 becomes negative with respect to the terminal 20, to result in the circulation of a positive current in the circuit defined by the terminal 20, the resistor 17, the grid-cathode junction of the controlled diode 9, the resistor 16 and the terminal 19. Said positive current, indicated by 23, attains the trigger threshold 24 for the controlled diode 9, and switches it into its conducting state to cause the capacitor 10 to discharge, as indicated by 25, through the path formed by the anode-cathode junction of the controlled diode 9 and the primary winding 12.

[0026] According to one embodiment not shown on the figures, the stator core is of U-shape and the capacitor charging solenoid 6 is wound on one of the two pole pieces of the core.

[0027] Numerous modifications of an applicational nature can be made to the invention, all of which must fall within the scope of the inventive idea as claimed hereinafter.

Claims

1. An electronic ignition device of magnetic flywheel type for internal combustion engines, comprising a first element provided with a permanent magnet (4), (4′) having two pole pieces, a second element provided with at least one magnetic core (1), (1′) having two or three pole pieces and facing said first element in relative rotational relationship therewith, a circuit provided with a first solenoid (6), (6′) arranged to charge a capacitor (10) and wound on a pole piece of the magnetic core (1), (1′), said first solenoid (6), (6′) having one side connected to earth through a rectifier diode (15) and its other side, by way of a second rectifier diode (8), feeding the capacitor (10) which discharges through the primary winding (12) of a transformer, the secondary winding (13) of which feeds the spark plugs, that side of said capacitor (10) facing the second rectifier diode (8) being connected to earth through a controlled diode (9), said controlled diode (9) being rendered conducting by the (triggering) voltage generated by said solenoid (6) which is used for charging the capacitor (10).

2. A device as claimed in claim 1, characterised in that said magnetic core (1), (1′) is of E-shape with three pole pieces, the solenoid (6) for charging the capacitor (10) and the coils (12) and (13) of the ignition transformer being wound on the central pole piece.

3. A device as claimed in claim 1, characterised in that said magnetic core (1), (1′) is of E-shape with three pole pieces, the solenoid (6) for charging the capacitor (10) being wound on the central pole piece of the magnetic core, and the coils (12) and (13) of the ignition transformer being wound not on said magnetic core.

4. A device as claimed in claim 1, characterised in that the stator core is of U-shape, the solenoid (6) for charging the capacitor being wound on one of the two pole pieces of said core.

5. A device as claimed in claim 1, characterised in that the rotary part comprises more than one magnet, the magnet core (1′) of its facing stator on which the capacitor charging solenoid is wound consisting of a rectilinear lamination pack disposed along a chord.

Drawing