US2221509A - Electric ignition system - Google Patents

Description

Nov. 12, 1940. L. DARKE 7 2,221,509

ELECTRIC IGNITION SYSTEM Filed Nov. 18, 1959 am vs/v mom ENGINE cm NKSHAF -r Inventor?- Leonard D Pke, by Zm-JMA: V Hi AO horne Patented Nov. 12, 1940 PATENT OFFICE ELECTRIC IGNITION SYSTEM Leonard Darke, Coventry, England, assignor to General Electric Company, a corporation oil New York Application November 18, 1939, Serial No. 305,123 In Great Britain May 31, 1939 3 Claims.

10 trembler coil. In such a system, a high voltage is induced in the secondary windings of the starting ignition coil and is impressed on a trailing electrode of a main magneto distributor brush holder. The current which passes through this electrode is then distributed to the appropriate distributor electrode so as to provide a spark at the spark plug for starting purposes.

An object of my invention is to provide an ignition system having an improved starting ig- 20 nition arrangement for an internal combustion engine.

A further object of my invention is to provide an improved ignition system utilizing a pulsating direct current voltage on the primary winding of 25 a magneto to provide the starting ignition voltage for an internal combustion engine. Further objects and advantages of my invention will become apparent from the following description referring to the accompanying drawin and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In the drawing, Fig. 1 diagrammatically illus- 3 trates a conventional magneto ignition circuit provided With contacts to which my improved starting arrangement may be connected; Fig. 2 is the magneto shown in Fig. 1 providedwith an embodiment of my improved starting system, and

40 Fig. 3 is a modification of the starting system shown in Fig. 2.

Referring to the drawing, in Fig. 1 I have illustrated diagrammatically a conventional magneto ignition system including a magneto l0 hav- 45 ing a core member ll witha primary winding l2 and a secondary winding l3 wound thereon. To

provide the necessary-cyclic interruption in the magneto primary circuit the primary winding l2 has shunted across it a breaker H and a capacitor 50 IS. The secondary winding I3 is in circuit with a conventional distributor l6 and a space discharge device or spark plug ll. Only one spark plug is shown, but it is to be understood that there is one in circuit with each one of the distributor 68 segments. A rotatable member is arranged to provide the field excitation for the magneto and includes permanent magnet pole pieces l8 which are magnetically connected with the primary and secondary windings through the core member II. The rotatable member is connected to 5 the crankshaft of an internal combustion engine either directly or through suitable gears and upon rotation thereof a current is induced in the primary winding l2. Upon the interruption of the primary winding circuit the breaker H which is 10 operated by the crankshaft either directly or by means of suitable gears through a cam member l9, voltage will be induced in the secondary winding I3 at the time the rotating brush of the dis tributor I6 is opposite a proper segment. Any dynamo-electric machine of the magneto type may be used which is designed to produce the desired voltage in the secondary ignition circuit for D the particular engine with which it is to be used.

In a conventional magneto, therefore, a sufficient voltage will not be induced in its primary winding until its rotatable member is rotated at a speed faster than starting or cranking speed, since it is the rotation of the rotatable member which causes the flux linking the winding to vary inmagnitude so that a voltage is induced therein. 7 Since this rotation is caused by the engine through its crankshaft, some auxiliaryarrangement must be used to produce the starting ignition for the engine. I provide the desired ignition for starting by impressing a suitable voltage of varying magnitude on the primary winding of the magneto and this causes .a voltage to be induced in the secondary winding which causes a current to be conducted to the spark plug through the distributor. In the circuit diagram shown in Fig. 1 the source of this voltage may be connected across the terminals 20 and 2|.

In Fig. 2 I have shown a simple and effective means for producing a voltage of varying 'magni- 40 tude and the energy source of this voltage includes a battery 22 across which is connected a trembler device having a trembler coil 23 which actuates an interrupter having contacts 24 and 25. In this circuit interrupter the contact 25 is carried by an armature 26 which is adapted to cooperate with a core member 21 of the trembler coil and the contact 24 is held stationary. In order to cause a current from the battery to flow through the trembler device a switch 28 which is in circuit therewith is closed. This flow of current will set up a. magnetic field which, attracts the armature and opens the contacts. A suitable capacitor 29 may be placed across these contacts so as to minimize arcing. When the contacts open the direct current stops flowing in the trembler coil and the magnetic field begins to subside. Since the armature is biased towards the contact 24, the contacts will close and direct current will again flow through the'trembler coil.

This opening and closing of the contacts will continue and a pulsating voltage will therefore appear across the interrupter contacts. In order to prevent a heavy current discharge through the primary windingand short circuiting of the battery, the contacts 24 and 25 are connectedacross the primary winding throughtwo condensers 30 and 3|. These connections are made through wires 32 and 33 and the capacitors 30 and 3| are respectively connected in series with these wires. One side of the primary winding may be grounded so as to form a return path from the spark plug. The side of the battery which is connected to one side of the tremblei' coil may also begrounded. Since a pulsating voltage appears across the interrupter contacts thecondensers 30 and 3| will becharged and discharged and a pulsating current will flow through the primary winding. Thus the pulsating current flowing through the primary winding will induce an alternating voltage in the secondary winding which will cause a current to flow through the distributor to a spark plug. A spark is only desired when the magneto breaker contacts are open so that ignition will occur at the proper time. Since these contacts, when closed, form a much lower impedance path to the current than the primary winding, the pulsating current will fiow in the rimary winding only when the contacts are open. spark at only the proper time.

thus providing a In the modification shown in Fig. 3, a circuit is shown similar to that illustrated in Fig. 12, except that the battery is not grounded and the con denser 3| is omitted. This circuit may be used when grounding of the battery is not desired. It is, of course, to be understood that condenser 30 may be omitted instead of omitting ill. The starting circuit, however, will operate similarly to that described in relation to Fig. 2.

Thus I provide a new system for supplying starting ignition voltage for an internal combustion engine which makes use of a conventional magneto which thereafter prothe engine, has been vides the ignition after started.

Modifications of the particular arrangements which I have disclosed will occur to those skilled in the art, so that I do not desire my invention to be limited to the particular arrangements set forth and I intend inthe appended claims to cover all modifications which do not depart from the spirit and scope of my invention. 2

What I claim as new and desire to securebi' Letters Patent of the United States is:

1. An ignition system for an-in'terna'l combustion engine including a magneto having a primary and a secondary winding and an excitation means responsive to the operating speed of said engine for inducing a current in said primary winding,

said primary winding having one side thereof tion engine including a and improved ignition connected to ground, a circuit breaker having an electrical connection with sald primary winding, means arranged to actuate=said.. circuit breaker periodically responsive to the operating speed of said engine for inducing a voltage in said secondary winding, a battery, an interrupter, and a cor? for. actuating said interrupter, connections including'isaid coil for connecting said interrupter across said battery, and connections betweensaid interrupter and said primary winding for connecting said interrupter across said primary winding said connections between said inter rupter and each side of said primary winding being provided with a capacitor; said interrupter being so constructed and arranged as to be periodically actuated by said coil so that ignitionis provided for the engine during starting.

2. An ignition system for an internal combusmagneto having a primary and a secondary winding and an excitation means responsive to the operating speed of said engine for inducing a, current in said primary winding, said primary winding having one side thereof connected to ground, a circuit breaker having an electrical connection with said primary winding, means arranged to actuate said circuit breaker periodically responsive to the operating speed of said engine for inducing a voltage in said secondary winding, a battery, an interrupter, and a coil for actuating said interrupter, connections including said coil for connecting said interrupter across said battery, and connections between said interrupter and said primary winding for connecting said interrupter across said primary winding, said connection between said interrupter and one side of the rimary winding being provided with a capacitor, said interrupter being so constructed and arranged as to be periodically actuated by said coil so that ignition is provided for the engine during starting.

3. An ignitionsystem for an internal combustion engine including a magneto having a primary and a secondary winding and an excitation means responsive to the operating speed of said engine for inducing a current in said primary winding, said primary winding having one side thereof connected to ground, having an electrical connection with said primary winding, means arranged to actuate said circuit breaker periodically responsive to. the operating speed of said engine for inducing a voltage in said secondary winding, a battery, an interrupter, and a coil for actuating said interrupter, connections including said coil for connecting said interrupter across said battery, an. connectionsbetween said interrupter and said primary winding for connecting said interrupter across said primary winding, said connection between saidinterrupter and the ungrounded side of the primary winding being provided with a capacitor, said interrupter being so constructed and arranged as to be periodically actuated by said coil so that ignition is provided for the engine during starting.

. LEONARD DARKE.

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