US2453910A - Ignition magneto - Google Patents

Description

Nov. 16, 1948.

H. T. HEAL IGNITION MAGNETO Filed Jan. 4, 1945 INVENTOR.

ATTORNEY Patented Nov. 16, 1948 IGNITION MAGNE'IO Henry Thomas Heal, London, England; assignor to Rotax Limited, London, England ApplicationJanuary 4, 1945', Serial No. 571,337 In Great Britain December 1, 1943 Section 1, Public Iiaw 690, August 8, 1946 Patent expires December 1, 1963 9 Claims.

This invention relates to ignition magnetos for internal combustion engines, and particularly aircraft engines, the object of the invention being to provide simple and satisfactory means for re'-' stricting the duration of each. of the successive high tension spark discharges.

. The invention consists of the combination with. the primary winding (or each such winding) of:

a small inductive winding connected in parallel with the make-and-break device.

The invention also consists in the combination with the inductive winding of a non-inductive resistance arranged in series therewith.

Moreover, the invention comprises the combination with the inductive winding (and series resistance when the latter is used), of an automatic, device for controlling the connection of this wind-I- ing or winding and resistance with the primary winding.

In the accompanying sheet of explanatory diagrams Figure 1 illustrates one mode of carrying the. invention into efiect.

Figures 2 and 3 illustrate respectively two modified features of the invention.

In Figure l (1 indicates an ignition magneto provided with the usual spark generator and distributor. The spark generator comprises a primary winding b, a secondary winding 0, a condenser d, and a make-and-break device e, the condenser and make-and-break device being connected in parallel with each other and with the primary winding. The distributor comprises a rotary contact arm connected to the secondary winding 0, and fixed contacts as g over which the arm is movable.

In applying the invention to the magneto illustrated in Figure 1, I connect a small inductive Winding h across the ends of the primary winding 1) and in parallel with the make-andbreak device 6. It is impossible to specify in general terms, the most suitable amount of inductance required in the winding h, as this will vary with the size and design of the magneto a, but the optimum value can very readily be ascertained by trial, the object in view being that of reducing the duration of the spark discharge to what is considered to be satisfactory.

When the amount of energy to be dissipated is relatively large it may be advantageous to arrange in series with the inductive winding h a noninductive resistance 2' as illustrated in Figure 2. This non-inductive resistance may be mounted on the inductive winding h, and its optimum Value can readily be ascertained by trial.

2 When the invention is applied to'magnetos for aircraft engines, it may be unnecessary or undesirable to have the inductive winding (or the. inductive winding and the non-inductive resistance when the latter is employed) in continual; For example, it may be required'that the use. controlof spark duration shall be operative only, when flying at high altitudes. To meet this or any other allied condition I employ any con.-

venient automatic switch for putting the said,

winding or winding and resistance in orout' of action, this switch being responsive to barometric:

pressure or other appropriate conditions. As. illustrated in Figure 3, such a switch may con"- sist ofa pair of complementary (fixed and movable) contacts 7', arranged in series with the:

windings h, 2', a resilient member m carrying the? movable contactlaand an evacuatedcapsule n1 connected by astem 0 to the resilient member and arranged in a container p communicating with the atmosphere, the arrangement beingsuch.

that the movable contact is responsive to barometric conditions.

By this invention the required control of the duration of each of the high tension spark discharges of the magneto can be effected in a very simple and satisfactory manner and without unduly impairing the efficiency of the magneto.

When the invention is applied to a magneto having more than one primary winding, an inductive winding (and if desired a non-inductive resistance) as above described may be associated with each primary winding.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a sparking apparatus of the type having a coil comprising primary and secondary windings and a make and break device connected across said primary winding, the improvement that comprises means for limiting the duration of the sparks under atmospheric conditions of relatively low pressure comprising an inductive winding and a non-inductive resistance in series, and means operable by changes in atmospheric pressure to connect the said series in parallel with the make and break device when the atmospheric pressure decreases, and to break the connection when the atmospheric pressure increases.

2. In a sparking device of the type having a coil comprising primary and secondary windings and a make and break device connected across said primary winding, the sparks of which are affected by changes in surrounding atmospheric condi tions, the improvement that comprises means for 3 limiting the duration of the sparks under atmospheric conditions of relatively low pressure comprisin an inductive winding, and means operable by changes in atmospheric pressure to connect the said inductive winding in parallel with the said make and break device when the atmospheric pressure decreases and to break the connection when the atmospheric pressure increases.

3. In a sparking device of the type having a coil with primary and secondary windings and a make and break device, the sparks of which are affected in their operative eiiect by surrounding conditions, the improvement that comprises means for limiting the duration of the spark when said affecting surrounding conditions are changed comprisin an inductance, and means operable by said changes in said surrounding conditions to connect the said inductance in parallel with the said make and break device when a said change of one type occurs, and to break the connection when an opposite change occurs.

4. In a sparking device of the type having a primary windin and a make and break device, the sparks of which are afiected in their operative effect by surrounding conditions, the improvement that comprises means for limiting the duratiton of the spark when said affecting surrounding conditions are changed comprising an inductance, and means operable by said changes in said surrounding conditions to connect the said inductance in parallel to the said make and break device when a said change of one type occurs, and to break the connection when an opposite change occurs.

5. Apparatus for controlling the duration of a magneto spark including an inductance, smaller than those of the generator and transformer windings of the magneto, connected in parallel to the make and break device of the magneto.

6. Apparatus for controlling the duration of a magneto spark including an inductance, smaller than those of the generator and transformer windings of the magneto, connected in series with a non-inductive resistance and in parallel with the make and break device of the magneto.

7. Apparatus for controlling the duration of a spark from a transformer coil including a transformer coil, a make and break device in parallel therewith, an inductance smaller than the inductance of the transformer coil connected in parallel therewith, a current controlling means between the said inductance and the said make and break device, and atmospheric pressure operated means operatively connected to the current controlling means. 8. A magneto ignition device having the make and break device of the magneto, and a small inductive winding connected in parallel across the primary winding of the magneto transformer and including pressure-sensitive means for making and breaking the connection of said inductive winding with the primary winding in response to variations in circumambient pressure.

9. A magneto ignition device having the make and break device of the magneto, and a small inductive winding connected in parallel across the primary winding of the magneto transformer and including means comprising a diaphragm responsive to changes in atmospheric pressure for making and breaking the connection of the inductive winding with the make and break device.

HENRY THOMAS HEAL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,224,24l Wacker May 1, 1917 1,640,936 Hawkins Aug, 30, 1927 2,007,373 Kongsted July 9, 1935 2,090,365 Harris Aug. 17, 1937 2,117,422 Holthouse May 17, 1938 2,196,693 Blake Apr. 9, 1940 2,292,809 Welch Aug. 11, 1942

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