US2753490A - Electric ignition system - Google Patents

Description

July 3, 1956 w. B. SMITS 2,753,490

ELECTRIC IGNITION SYSTEM Filed Feb. 12, 1952 2 Sheets-Sheet l a M R QM y 3 1956 w. B. SMITS 2353,490

ELECTRIC IGNITION SYSTEM Filed Feb. 12, 1952 2 Sheets-Sheet 2 5y Qua R QM United States Patent ELECTRIC IGNITION SYSTEM Wytze Beye Smits, Voorburg, Netherlands, assignor to Smitsvonk N. V., Rijswiik (S. H.), Netherlands Application February 12, 1952, Serial No. 271,118

2 Claims. (Cl. 315-218) The invention relates to an electric ignition system with at least one surface discharge spark plug, at least one condenser, a magneto for charging said condenser(s), and a switching device for alternately connecting the said c0ndenser(s) with the magneto and with the spark P s( The invention aims at providing an electric ignition system which is entirely simple in construction and particularly suitable for the internal combustion engine of a bicycle with a light motor. it is characterized in that the magneto consists of a rotatable permanent magnet and a stationary armature providing with a winding, that the switching device has the form of a distributor, the moving contact of which is supported by the member with the permanent magnet and rotates together with the latter, and that both the armature winding of the magneto and each of the spark plugs are connected to a special fixed contact of the distributor, cooperating with this moving contact.

In this system the armature of the magneto need be provided with only a single coil, and the rotatable member with the permanent magnet serves both to generate the current impulses and to produce the sparks at the right moment, while the said member also functions as a distributor when the system is provided with more than one spark plug.

A simple ignition system for feeding a single spark plug is obtained when the condenser is connected on the one hand to the moving contact of the distributor and on the other hand to the ground, and is supported by the rotatable member with the permanent magnet. In order to prevent the currents in this case from flowing via the bearings of the shaft of the rotatable member, it is to be recommended to provide a slip-ring with brush contact on the shaft. It will be obvious that if it is desired to charge the condenser with the aid of the alternating voltage generated in the armature winding, the moving contact of the distributor has to move past the fixed contact connected to the armature winding in such a way that the connection between the condenser and the armature winding is broken when the voltage generated in this winding has attained a given value, for example a value in the neighbourhood of the maximum amplitude of this voltage. The switching device or the distributor should therefore at the same time act as a rectifier.

If it is desired not to have the condenser(s) rotate with the rotatable member, the or each condenser may be connected to a fixed contact of the distributor, and the moving distributor contact may be given the form of a bridge contact capable of connecting a fixed contact connected to a condenser alternately to the fixed contact connected to the armature winding and a fixed contact connected to a spark plug. In order to prevent or at least greatly reduce the mechanical wear of the distributor contacts moving past each other, these contacts may be made to pass each other at some distance.

For the feeding of two or more spark plugs, use can be made of two or more condensers, which are con- 2,753,490 Patented July 3, 1956 nected to fixed distributor contacts located and designed in such a way that they are connected simultaneously to the armature winding and successively to a spark plug by the moving bridge contact. This system is suitable for motors with more than one cylinder The parallel charging of two or more condensers requires a powerful magneto. Then only two condensers are to be charged, the fixed distributor contacts connected thereto can advantageously be so arranged that one condenser is charged by the positive current impulse and the other condenser by the negative current impulse of the charging current generated by the magneto. In that case the magneto need not be more powerful than for the charging of a single condenser. These two condensers can then be made to discharge successively each via a spark plug of their own. It is also possible to connect the two successively charged condensers in series via a single spark plug. In that case double the sparking energy is generated on the spark plug.

The permanent magnet can advantageously be pro vided on the flywheel of the internal combustion engine, and this flywheel may enclose a space in which at least the armature and the distributor are accommodated. if necessary, this space may contain the condenser(s).

For the adjustment of the moment at which a spark is produced on a spark plug, at least the fixed distributor contact connected to the respective spark plug can made re-adjustable in the direction of rotation of the moving distributor contact.

The invention is explained with reference to the drawing, which illustrates a number of embodiments of the invention diagrammatically, by way of example. In this drawing Fig. 1 illustrates an ignition system with a magneto accommodated in the flywheel of an internal combustion engine, a distributor formed by this flywheel, and a condenser rotating together with this wheel.

Fig. 2 illustrates a variant of Fig. l, in which the condenser does not rotate together with the flywheel.

Fig. 3 is an axial cross-section of the system according to Fig. 2.

Fig. 4 shows another embodiment of a system according to the invention, in which two condensers are charged by one magneto and these condensers can discharge each via a spark plug of their can.

Fig. 5 shows a variant of the system according to Fig. 4, and

Fig. 6 shows a variant of the system according to Fig. 2, in which two condensers can discharge in series via one spark plug.

In the drawing, 1 is the flywheel of an internal combustion engine, for example the light motor of a bicycle. 2 and 3 are the poles of a permanent magnet accommodated in the rim of the flywheel. 4 is a stationary armature cooperating with this permanent magnet. This armature is provided with a single coil 5. One end of this coil is connected to the ground, while the other end is connected to a fixed contact 6 of a member functioning as a distributor, which further consists of an insulated moving contact 7 provided in the rim of the flywheel 1 and a fixed contact 3. The moving co ct "l of the distributor is connected to an ignition co. nser 9, supported by the flywheel 1, the other end of which condenser is connected to the conductive mass of the fiywheel. Via a slip-ring 10 on the shaft 11 of the flywheel and a brush 12 forced against this slip-ring the mass of the flywheel is connected to the ground, while bypassing the bearings of the shaft. The fixed contact 8 of the distributor is connected to a surface discharge spark plug 13.

The fixed contact 6, past which the moving contact 7 may be dragged or past which it may freely move at a short distance is located in such a way that the connection between the condenser 9 and the armature coil 5 is broken at the moment when the voltage generated in it has attained a given value, in general a value in the neighbourhood of the maximum amplitude. The condenser is thus charged by the coil 5 and remains charged until the moving contact 7 moves past the fixed contact 8. As soon as the contacts 7 and 8 face each other, the condenser 9 discharges via the spark plug 13, and an ignition spark is produced. The moment at which the spark is produced depends entirely on the location of the fixed contact 8. If it is desired to make this moment adjustable, the fixed contact 8 has to be provided so as to be readjustable.

In the system according to Figs. 2 and 3 the condenser 9 is provided on the stationary plate with the armature 4, and it is connected to a third fixed contact 14, which has been represented in Fig. 2 as being concentric with the contacts 6 and 8, but in reality is placed coaxially in relation to the contacts 6 and 8, in the way shown in Fig. 3. The moving distributor contact has the form of an insulated bridge contact 15 provided in the rim of the flywheel 1, which bridge contact upon rotation first establishes a connection between the fixed contacts 6 and 14, and subsequently between the contacts 14 and 8. Through the first connection the condenser 9 is charged, while the second connection closes the discharging circuit with the spark plug 13. This system operates in the same manner as the system according to Fig. 1.

Fig. 4 shows a variant of the system according to Fig. 2, in which two condensers 9 and 9' are simultaneously charged by the coil 5, but these condensers are discharged successively via spark plugs 13 and 13 of their own respectively. To this end the condenser 9' is connected to two fixed contacts 14 and 14". In this case the contacts 6, 14 and 14 are located coaxially side by side, so that they can be interconnected simultaneously by the bridge contact. Further, the contacts 14 and 3 are situated coaxially in relation to each other in the manner of Fig. 2, while the contacts 14 and 8 are located coaxially side by side at another place of the path of the bridge contact 15. In this case the spark plug contacts 8 and 8 of the distributor lie diametrically opposite each other. The condensers 9 and 9' are thus simultaneously charged, but are discharged via the respective spark plugs with a difierence of phase of 180". For the simultaneous charging of the condensers 9 and 9' the magneto should be able to generate double the energy. This system is suitable for motors with two cylinders.

Fig. 5 shows a variant of the system according to Fig. 4, in which the condensers 9 and 9 are connected to fixed contacts 14 and 14, Which are out of phase in relation to the direction of movement of the bridge con tact 15 to such an extent that, for example, the condenser 9 is charged by the positive current impulse and the condenser 9 by the negative current impulse of the alternating voltage generated in the coil 5. The condensers are again discharged successively via their respective spark plugs.

Fig. 6 illustrates an ignition system, which resembles the system according to Fig. 5, but in which the coni densers 9 and 9 are connected in series, the connecting point of those condensers is connected to one end of the armature coil 5, the condenser 9 is connected to the fixed contact 14, the condenser 9 is connected both to the fixed 7 contact 14 and to the ground, and the fixed contacts 14 and 14' are out of phase in relation to the direction of movement of the bridge contact 15 to such an extent that, for example, the condenser 9 is charged by the positive and the condenser 9 by the negative current impulse of the magneto. The discharge takes place when the bridge contact connects the condenser contact 14 to the spark plug contact 8. In this position of the bridge contact 15 the condensers 9 and 9' are connected in series to the spark plug 13, and an ignition spark of double the energy is produced.

I claim:

1. An ignition system comprising, in combination, a low voltage spark plug, a condenser, a magneto comprising a rotating member having a permanent magnet there-' on and a stationary armature, and means including a switch operatable by rotation of said magneto connecting said condenser alternately with said stationary armature and said spark plug, the switch comprising a contact on the rotating member and stationary contacts sequentially engaged by said first-named contact.

2. An ignition system according to claim 1 wherein said contact on the rotating member comprises a bridging element, said bridging element adapted to bridge the gap between said stationary contacts.

References Cited in the file of this patent UNITED STATES PATENTS 1,274,115 Warren July 30, 1918 1,459,252 Plumm June 19, 1923 1,935,230 Pfrommer Nov. 14, 1933 2,125,035 Smits July 26, 1938 2,212,404 Robinson Aug. 20, 1940 2,602,149 Brunelle July 1, 1952,

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