US3116379A - Ignition system for internal combustion engines - Google Patents

Description

Dec. 31, 1963 F. M. FOSTER 3,116,379

IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Aug. 18, 1960 lllli! IN V EN TOR. fiv/vk M 5 .s'rzae United States Patent 3,116,379 IGNITHQN SYSTEM FOR INTERNAL CQMBUSTEQN ENGINES Frank M. Foster, South Pasadena, Calili, assignor to Seas, Ltd, South Pasadena, Calilh, a corporation of (Ialifornia Filed Aug. 18, 1960, Ser. No. 50,358 9 Claims. (til. 200-) The invention relates to a spark ignition system for internal combustion engines, particularly to a circuit 7 breaker in the ignition system to produce successive high voltage pulses of current for ignition with the engine spark plugs.

The invention provides a circuit breaker of the type des ribed above which is reliable and durable, which permits more precise timing of the igniting spmk at the spark plugs in relation to rotation of the engine crankshaft, and which operates with minimal pitting and carbonization of its electrical contact points.

Conventional spark ignition systems for internal cornbustion engines include a step-up transformer or coil which has a low voltage primary winding of few turns connected in a series primary circuit with a low voltage source of potential and with a circuit breaker. The transformer has a secondary winding, of many more turns than the primary winding, which is connected successively in a series secondary circuit with the spark gap of each spark plug, at the proper time for ignition of the air-fuel mixture in the cylinder, by a distributor rotor, rotativcly driven in timed synchronism with the rotation of the engine crankshaft, and by an adjacent circular arrangement of terminals, each connected in series to one of the spark plug gaps.

The primary circuit is normally closed to permit current fiow through the primary winding of the transformer to build up a magnetic flux field about the secondary windings. The primary circuit is periodically opened for a short time interval by the circuit breaker in the primary circuit in timed synchronism with the distributor rotor and the rotation of the engine crankshaft. The opening of the primary circuit causes the magnetic flux field to collapse and thereby induce a high voltage current in the secondary winding of the transformer, which causes a spark to jump the spark gap of the spark plug.

The circuit breaker is conventionally operated by a cam fixed to the distributor rotor shaft for rotation with the shaft in timed synchronisrn with the engine crankshaft and with the distributor rotor. The distributor rotor normally closes the secondary circuit to the proper spark plug for an appreciable length of time, and the opening of the primary circuit, and thus the igniting spark at the spark gap of such proper spark plug, is selectively timed to occur at the proper moment during the power stroke of the engine by adjusting the rotary position of the circuit breaker about the distributor rotor shaft.

The working surface of the conventional circuit breaker cam is of relatively small diameter. This results in a relatively small arc of displacement of its working surface 'for a given rotary angular displacement of the engine crankshaft and the distributor shaft. As a result, actuation of the circuit breaker is undersensitive in relation to the rotational cycle of the engine crankshaft, and this is a disadvantage because it makes difficult the selective adiustment of the circuit breaker and cam to open the primary circuit at precisely the correct moment during such rotational cycle of the engine crankshaft.

Another disadvantage of conventional circuit breakers is the fact that the circuit breaker points tend to spark when they are separated to open the primary circuit, and

this causes pitting and carbon deposition on such points, leading to unreliability and ultimate failure thereof.

The invention removes the above disadvantages by means of a circuit breaker wherein the contact points rotate and are actuated to open and close the primary circuit by means of structure spaced concentrically from the center of rotation of the contact points.

The rotation of the points results in an air stream past the points. This air stream tends to prevent sparking between the points when they are separated, and thus reduces pitting and carbon deposition on the points.

The spacing of the actuating structure from the center of rotation of the points results in a larger arc of displacement about such center for a given rotary angular displacement of the engine crankshaft. As a consequence, the sensitivity of the actuation of the circuit breaker in relation to the rotation of the engine crankshaft is increased. This makes it possible, through selective adjustment of the circuit breaker, to time more precisely the opening of the primary circuit in relation to the rotation of the engine crankshaft.

The structure of the invention includes a member surrounding and extending transversely of a rotary shaft rotatable synchronously with the crankshaft of the engine, such as a conventional distributor shaft. The member has a plurality of cam portions for actuation of a follower in a direction axially of the shaft arranged symmetrically and concentrically about the shaft in equal spaced relation therefrom and in spaced relation to each other. A first arm is fixed to the shaft for rotation therewith and extends radially therefrom. A second resilient flexible arm is fixed to the shaft for rotation therewith and extends radially therefrom for displacement axially of the shaft by the cam portions. Electrical contact points are provided on the first and second an. s which are adapted to alternately engage and disengage responsive to displacement of the second arm in opposite directions by the cam portions. The electrical contact points are spaced from each other and connected in series with the primary winding of a conventional electrical induction transformer and source of potential in the ignition circuit to effect alternate opening and closing of such circuit, which thereby induces successive pulses of high voltage current in the secondary winding of the transformer.

The invention and its advantages will be fully understood from. a reading of the following description, taken in conjunction with the accompanying drawings, in which:

'PlG. l is a schematic circuit diagram of the ignition system for an internal combustion engine and a plan view of the distributor in such system embodying the invention;

FIG. 2 is a vertical section along the line 22 in PEG. l; and

3 is a vertical section along the line 3-3 in FIG. 1.

Referring to 1, ill is the case of a conventional automobile distributor with the ca and rotor removed. A conventional rotatable distributor shaft ll extends through the distributor to be rotatively driven in conventional manner synchronously with the crankshaft of the engine as represented by meshed gears '7 and S and by shaft rotatably driving shaft ll by connection through the gears. The conventional advance plate in such distributors is shown schematically at 12. The advance plate is normally stationary relative to the distributor shaft, except for small amounts of rotation thereof responsive to conventional mechanism to advance and retard the tim ing of the engine. Although the invention is described herein in conjunction with a conventional automobile ignition distributor and distributor she. t, it is to be understood that the invention may comprise a unit separate 3 from the distributor with a separate rotatable shaft rotatively driven in conventional manner synchronously with the engine crankshaft performing the functions of the distributor shaft.

A cam plate 15, preferably annular in shape, is disposed on the advance plate i2. and extends transversely of the axis of the distributor shaft 11. If the cam plate is the preferred annular shape, it is disposed coaxially with the distributor shaft. The cam plate is releasably fixed to the advance plate in non-rotatable position with conventional means, such as a plurality of tabs receiving screws threadedly received in the advance plate, as shown for the tab 16 and screw 17. Although the cam plate is fixed to the advance plate in non-rotatable position, it is adapted to be so fixed in preselected rotary ositions about the axis of the distributor shaft 11, this being permitted in conventional manner, as by arcuately slotted holes, such as the hole 18, in the tabs. Thus, the cam plate may be released from the advance plate, positioned in a selected rotary position about the axis of the distributor shaft, and non-rotatably releasably fixed in such position.

Disposed about the outer periphery of the cam plate in spaced relation to the distributor shaft are a plurality of cam portions, such as the cam portions 20 and 21. Each cam portion extends in a direction transverse to the plane of the cam plate and parallel to the axis of the shaft 11 a greater amount than the extent in the same direction of the portion of the cam plate between it and the next cam portion, as best shown in FIG. 3 for the cam portions 29 and 21 and the portion of the cam plate therebetween 22. All the cam portions are identical and are symmetrically, equally and concentrically spaced about the axis of the distributor shaft. The cam portions are each arcuate in the plane of the cam plate with a constant and common radius about the distributor shaft so that they are concentric therewith. Each cam portion is of equal arc length about the axis of the distributor shaft. The profile of the cam portions in a curved plane transverse to the plane of the cam plate and concentric with the axis of the distributor shaft may vary for particular applications, but in general will be as shown in FIG. 3, wherein the cam portion 20 has an approach ramp 23 extending angularly transversely of the plane of the cam plate, a dwell portion 24 which extends substantially parallel to the plane of the cam plate and an abrupt retreat 25 which extends to the portion 22 of the cam plate between the cam portion 2% and the ramp of the next succeeding cam portion 21. It is thus apparent that the cam portions are designed so that a follower rotating about the axis of the distributor shaft in the direction indicated with the arrow 13 in FIG. 1 is displaced alternately in opposite directions transverse to the plane of the cam plate and axially of the distributor shaft, the displacement being up responsive to the cam portions and down responsive to the portions between cam portions.

A rotor 3t? is disposed on the distributor shaft ill and is fixed thereto for rotation with the distributor shaft with conventional means, as a setscrew 31 threadedly received through the rotor and engaging the distributor shaft.

An actuating arm 32 extends radially from the rotor 3th in juxtaposed relation to the cam plate 15 and to the cam portions thereof and is fixed to the rotor for rotation therewith, as by means of a ring portion 33 connected to the rotor in conventional manner. The arm 32 is made of resilient, spring material, such as spring steel. Mounted on the arm 32 is a follower member 34- which may be a cylindrical contact point as shown, a roller, or a skid portion of the arm 32 itself. The follower member 34 is aligned with the cam portions on the cam plate with its end normally disposed below the dwell surfaces of the cam portions, such as the dwell 24 of the cam portion Zil, so that when it is in contact ,4 with such dwell surfaces, as shown in FIG. 2, the actuating arm is displaced upwardly and when it is disposed between the cam portions the arm is displaced downwardly through resilient flexure thereof. Thus it is apparent that as the distributor shaft 11 rotates, the actuating arm rotates therewith and its follower member successively engages and disengages the cam portions to cause the actuating arm to displace successively in opposite directions axially of the shaft.

Also fixed to the rotor for rotation therewith is an butment arm 35, which may be so fixed by means of a ring portion 36 connected to the rotor 30 in conventional manner. The arm 35 extends radially from the distributor shaft in juxtaposed spaced relation to the actuating arm. It is made of springy, resilient material, such as spring steel, the same as the actuating arm 32, although it is apparent that the abutment arm need not be springy and resilient and may be made of other material.

An electrical contact point 37 is fixed to the actuating arm 32 and another electrical contact point 38 is fixed to the abutment arm 35. The contact points 37, 38 are aligned and made of electrically conductive material such as is commonly found in the contact points for conventional distributor circuit breakers. The contact points 37 and 38 are spaced from each other axially of the shaft 11 a maximum amount which is less than the maximum displacement of the point 37 resulting from displacement of the arm 32 responsive to engagement of the follower member with the cam portions, so that the points 37 and 33 alternately engage and disengage to close and open an electrical circuit completed therethrough, as will be described below, responsive to the alternate displacements of the arm 32 in opposite directions as described above. As illustrated in FIG. 2, the contact points 37 and 38 are spaced from one another so that they do not engage when the follower member 34 is between cam portions and do engage when the follower member is in contact with a cam portion. As shown in FIG. 2, when the follower member 34 engages a cam portion, both the arm 32 and the arm 35 are resiliently displaced upwardly which, due to the spacing of the contact points described above, results in positive urging together of the contact points 37 and 38 to close a circuit therethrough effectively and reliably. It is apparent that other arrangements may be adopted within the scope of the invention for the alternate engagement and disengagement of the contact points 37 and 33, such as, for example, disposing the arm 35 intermediate the arm 32 and the cam plate and designing the cam portions so that the contact points will be disengaged when the arm 32 is displaced upwardly responsive to a cam portion and engaged while the follower member of the arm is disposed intermediate the cam portions. Also, if desired, a plurality of pairs of actuating and abutment arms may be used, each pair of such arms having a set of contact points and operating as described above, so that a plurality of contact points synchronously engage and disengage for more reliable closing and opening of the circuit.

The contact surface of one of the contact points is arcuate, as at 39, so that the radial displacement of one contact point relative to the other as the first and second arms flex upwardly results in a wiping action between the points in a plane substantially parallel to the plane of the cam plate 15 which tends to prevent formation of carbon deposits and the like on the contact surfaces of the points.

The contact points 37, .33 are electrically insulated from each other when they are disengaged and are disposed in an electrical circuit as described below. For this reason the rotor 3th is made of dielectric material and the arms 32, and 35 are made of electrically conductive material to which the contact points are fixed in electrically conductive relation. Electrical circuitry is completed to the arm 32 through the ring 3-3 thereof, the setscrew 31 con.-

ductively engaging the ring 33 and the distributor shaft iii, an electrically conductive leaf spring 4d fixed to the advance plate ill with mount 42 and screw 41 and hearing against the distributor shaft lit in resiliently displaced condition, and a conventional electrical connection 14 of the advance plate to a ground terminal 43. Electrical circuitry is completed to the contact point 38 by means of a second leaf spring which at one end is fixed to a stationary terminal and is resiliently displaced with its free end portion engaging on the ring 36 of the arm 3:? to effect a reliable electrical connection between the spring dd and the ring 36. Thus, electrical connections to the arms 3-2 and 35 are maintained during rotation of such arms with the rotor through the sliding engagement of the leaf springs and dd with the rotating shaft ll and ring 36, respectively.

Referring now to MG. 1, circuitry and apparatus for a spark ignition system for an internal combustion engine are schematically shown. A conventional electrical induction transformer, or spark coil, is indicated at and has a primary winding 551 of few turns and a secondary winding 52. of many turns. The primary winding fill is connected in a series primary circuit to a conventional source of low voltage potential 56, a conventional condenser 57, and also the contact points 37, The connection of the contact points 3'7 and 38 in the primary circuit is accomplished through the terminals 43 and 45 and the electrical connection of the contact points thereto as described above. The contact points 37 and are in engagement during the time the fol-lower member 34 engages a cam portion, which thereby closes the primary circuit and permits a magnetic iiux field to be built up about the secondary windings 52 by the primary windings :31 as a result of current flowing therethrough from the source of potential When the follower member Ed reaches the retreat of a cam portion, such as the retreat of the cam portion 2, it displaces away from the arm and causes the contact points 3'7 and to disengage and thus open the primary circuit. The opening of the primary circuit causes the magnetic field to decay or fall, thereby inducing a high voltage current in the secondary coil winding 5'2. This high voltage electrical current is conducted to the proper spark plug in timed relation to the operation of the engine by means of a conventional distributor rotor mounted on the distributor shaft for rotation therewith which ro tates and completes successively a circuit to each of the spark plugs through a terminal for each spark plug, such as a circuit to the spark plug gap 55 through the terminal to cause a spark across the spark plug it is an parent that the cam plate is selectively positioned about the distributor shaft ll in such rotary position that the portions of the cam plate between the cam portions are properly oriented with respect to the distributor shaft ill and rotor and with respect to the rotational cycle of the engine crankshaft so that the high voltage current produced by the opening of the primary circuit as a result of disengagement of the contact points 25", and 33 occurs at the proper time during the rotational cycle of the engine crankshaft and corresponds with the comple* tion of an electrical circuit through the secondary winding to the proper spark plug. This timing is accomplished in conventional manner as a result of the rotary adjustability of the cam plate relative to the rotor shaft ill; per mitted by the means for releasably attaching the cam plate to the advance plate, as described above. The [lllu ing is greatly facilitated and may be accomplished with more precision than conventionally because the cam portions are spaced from the distributor shaft and hence extend a greater are distance about the distributor shaft for a given rotary angular displacement of such shaft than the conventional circuit breaker cam, which increases the sensitivity of the actuation of the contact points relative to the rotation of the engine crankshaft f5 and the rotation of the distributor shaft, as explained in the introductory portion hereof.

I claim:

1. A circuit breaker comprising a rotary shaft, means for rotating the shaft, a member surrounding the shaft and extending transversely of the axis of the shaft, a plurality of cant portion means on the member equally spaced from the shaft concentrically with its axis and spaced from each other about the shaft for displacement of a cam follower axially of the shaft, a first arm fixed to the shaft for rotation therewith and extending radially therefrom, a second resilient flexible arm fixed to the shaft for rotation therewith and extending radially therefrom, said first and second arms being juxtaposed and spaced from each other axially of the shaft, cam followor means disposed on the second arm engageable with the cam portion means for displacing the second arm in opposite directions axially of the shaft responsive to engagement and disengagement of the cam follower means with the cam portion means, a first electrical contact on the first arm, a second electrical contact on the second arm in spaced aligned relation axially of the shaft to said first electrical contact, and means connected to the first and second contacts for conducting electrical current through the contacts when the contacts are engaged and the second electrical contact, whereby an electrical circuit is alternately closed and opened through engagement and disengagement of the first and second electrical contacts responsive to displacement of the second arm by the cam portion means.

2. A circuit breaker, comprising a rotary shaft, means for rotating the shaft, a member surrounding the shaft and extending transversely of the axis of the shaft, a plurality of cam portion means on the member equally spaced from the shaft concentrically with its axis and spaced from each other about the shaft for displacement of a cam follower axially of the shaft, a first resilient flexible arm fixed to the shaft for rotation therewith and extending radially therefrom, a second resilient flexible arm fixed to the shaft for rotation therewith extending radially therefrom, said first and second arms being juxtaposed and spaced from each other axially of the shaft, cam follower means disposed on the second arm engageable with the cam portion means for displacing the second arm in opposite directions axially of the shaft responsive to engagement and disengagement of the cam follower means with the cam portion means, a first electrical contact on the first arm, a second electrical contact on the second arm in aligned relation to said first electrical contact, said first and second electrical contacts being spaced from each other axially of the shaft a maximum amount which is less than the displacement of the second electrical contact resulting from said displacement of the second arm, and means connected to the first and second contacts for conducting electrical current through the contacts when the contacts are engaged, whereby an electrical circuit is alternately closed and opened through engagement and disengagement of the first and second electrical contacts responsive to displacement of the second arm by the cam portion means.

3. A circuit breaker comprising a rotary shaft, means for rotating the shaft, a non-rotatable member surrounding the shaft and extending transversely of the axis of the shaft, a plurality of cam portions on the member extending therefrom longitudinally of too axis of the shaft and radially spaced equally from the axis of the shaft concentrically with such axis, said cam portions being spaced from each other about such axis, a first resilient flexible arm fixed to the shaft for rotation therewith and extending radially therefrom, a second resilient flexible arm fixed to the shaft for rotation therewith and extending radially therefrom in juxtaposed relation to the first arm and to the cam portions, said first and second arms being spaced from each other along the axis of the shaft,

cam follower means on the second arm engageable with the cam portions for displacing the arm in opposite directions in the plane of the axis of the shaft responsive to engagement and disengagement of such means with the cam portions, a first electrical contact on the first arm, a second electrical contact on the second arm in juxtaposed relation to the first electrical contact and normally spaced therefrom longitudinally of the axis of the shaft, the maximum spacing of the first and second electrical contacts being less than the maximum displacement of the second contact resulting from said displacement of the second arm, and means connected to the first and second contacts for conducting electrical current through the contacts when the contacts are engaged, whereby the first and second electrical contacts are successively engaged and disengaged to successively close and open an electrical circuit.

4. A circuit breaker comprising a rotary shaft, means for rotating the shaft, a non-rotatable member surrounding the shaft and extending transversely of the axis of the shaft, a plurality of cam portions on the member extending therefrom longitudinally of the axis of the shaft and radially spaced equally from the axis of the shaft concentrically with such axis, said cam portions being of equal angular extent about the axis of the shaft and being spaced from each other symmetrically about such axis, a first resilient flexible 'trm fixed to the shaft for rotation therewith and extending radially therefrom, a second resilient flexible arm fixed to the shaft for rotation therewith and extending radially therefrom intermediate the first arm and the cam portions in juxtaposed relation to the first arm and to the cam portions, said first and second arms being spaced from each other along the axis of the shaft and being made of electrically conductive material, cam follower means on the second arm for displacing the arm in opposite directions in the plane of the axis of the shaft responsive to engagement and disengagement of such means with the cam portions, a first electrical contact on the first arm in electrically conductive relation thereto, a second electrical contact on the second arm in electrically conductive relation thereto in juxtaposed relation to the first electrical contact and normally spaced therefrom longitudinally of the axs of the shaft, said spacing of the first and second electrical contacts being less than the maximum displacement of the second contact resulting from said displacement of the second arm, at least one of said first and second electrical contacts having an arcuate surface juxtaposed to the adjacent surface of the other, and means connected to the first and second contacts for conducting electrical current through the contacts when the contacts are engaged are successively engaged and disengaged to successively close and open an electrical circuit.

5. A circuit breaker comprising a rotary shaft, means for rotating the shaft, a member surrounding the shaft and extending transversely of the axis of the shaft, a plurality of cam portion means on the member concentric with the axis of the shaft for displacement of a cam follower axially of the shaft, 2. first arm fixed to the shaft for rotation therewith and extending radially therefrom, a second resilient flexible arm fixed to the shaft for rotation therewith and extending radially therefrom, cam follower means secnred to the second arm and engaging said cam portion means for displacing the second arm in opposite direction axially of the shaft responsive to engagement and disengagement of the cam follower means with the cam portion means, a first electrical contact on the first arm, a second electrical contact on the second arm in spaced aligned relation axially of the shaft to said first electrical contact, a source of electrical potential, electrical means to be switched by the circuit breaker, means for electrically connecting the source of potential and one of the electrical contacts, and means for electrically connecting the other electrical contact and the electrical means, whereby an electrical circuit is alternately closed and opened through engagement and disengagement of the first and second electrical contacts responsive to displacement of the second arm by the cam portion means.

6. A. circuit breaker for periodically interrupting the flow of electric power from a source of electric power to an electr'cally powered means comprising a rotary shaft, means for rotating the shaft, a stationary member surrounding the shaft and extending transversely of the axis of the shaft, means for varying and selectively releasably the stationary rotary position of the member about the shaft, a plurality of cam portions on the member extending therefrom longitudinally of the axis of the shaft and equally radially spaced from the axis of the shaft conccntrically about such axis, said cam portions being spaced from each other symmetrically about such axis, a rotor disposed on said shaft for rotation therewith, said rotor being made of a dielectric material, a. first resilient flexible arm fixed to the rotor for rotation therewith and extending radially of the shaft, a second resilient flexible arm fixed to the rotor for rotation therewith and extending radially of the shaft in juxtaposed relation to the first arm and to the cam portions, said first and second arms being spaced from each other longitudinally of the axis of the shaft and being made of electrically conductive material, cam follower means on the second arm engageable with the cam portions for displacing a portion of the second arm axially of the shaft responsive to engagement of the cam follower means with the cam portions, a first electrical contact on the first arm in electrically conductive relation thereto, a second electrical contact on the second arm in electrically conductive relation thereto in juxtaposed relation to the first electrical contact and normally spaced therefrom longitudinally of the axis of the shaft, said first and second electrical contacts being located radially of the shaft intermediate the cam portions and the shaft, the maximum spacing of the first and second electrical contacts from each other being less than the displacement of the second contact resulting from said displacement of the second arm responsive to engagement of the follower means with the cam portions, first and second electrical terminals associated with the stationary member, means for maintaining continuous electrical connection between the first terminal and the first contact, means for maintaining continuous electrical connection between the second terminal and the second contact, means electrically connecting the power source to one of the terminals, and means electrically connecting the electrically powered means to the other contact, whereby the first and second electrical contacts are successively engaged and urged together and disengaged to successively close and open an electrical circuit between the power source and the electrically powered means.

7. A circuit breaker comprising a rotatable shaft, a plurality of cam means disposed concentric to the shaft and at equal distances therefrom, each cam means defining a profile having first and second portions spaced apart from one another axially of the shaft, a pair of resilient parallel arms spaced apart from each other axially of the shaft, means connected to the shaft for providing rotational motion between the cam means and the arms, one arm including a cam follower portion engageable with the cam means, cooperating electrical contact elements on the arms, the contact elements being disengaged when the cam follower portion is engaged with the first portion of a cam means, the contact elements being engaged when the cam follower portion is engaged with the second portion of a cam means, and means for maintaining a continuous electrical connection between each contact element and a corresponding terminal remote from the shaft.

8. In an ignition system for an internal combustion engine comprising an electrical induction transformer having primary and secondary windings, a source of electric potential, a plurality of spark plugs connected individually in a predetermined sequence to the secondary winding,

and a circuit breaker connected for making and breaking an electrical circuit to the primary winding according to a predetermined rate related to the predetermined sequence, the improvement residing in a circuit breaker comprising a rotatable shaft, stationary cam means disposed radially of the shaft, the cam means defining a profile having a dwell portion and a pause portion parallel to each other and oriented perpendicular to the shaft at longitudinally spaced-apart locations relative to the shaft, first and second parallel and spaced-apart resilient arms of electrically conductive material secured to the shaft for rotation therewith, the arms extending radially of the shaft, the first arm extending to a free end adjacent the cam means, cam follower means at the free end of the first arm engageable with the cam means, cooperating electrical contact elements on the first and second arms, the contact elements being spaced apart axially of the shaft when the cam follower means is engaged with a pause portion of the cam means, the contact elements being engaged when the cam follower means is engaged with a dwell portion of the cam means, a pair of terminals forming a portion of a circuit of the ignition system, and means for maintaining continuous electrical connection between each of the contact elements and the terminals.

9. In an ignition system for an internal combustion engine having an electrical induction transformer having primary and secondary windings, a source of electric potential, a plurality of spark plugs connected individually in a predetermined sequence to the secondary winding, and a circuit breaker connected for making and breaking an electrical circuit to the primary winding according to a predetermined rate related to the predetermined se quence, the improvement residing in a circuit breaker comprising a rotatable shaft, a plurality of cam means disposed concentric to the shaft and at equal distances therefrom, each cam means defining a profile having first and second portions spaced apart from one another axially of the shaft, a pair of resilient parallel arms spaced apart from each other axially of the shaft, means connected to the shaft for providing rotational motion between the cam means and the arms, one arm including a cam follower portion engageable with the cam means, cooperating electrical contact elements on the arms, the contact elements being disengaged when the cam follower portion is engaged with the first portion of a cam means, the contact elements being engaged when the cam follower portion is engaged with the second portion of a cam means, and means for maintaining a continuous electrical connection between each contact element and a corresponding terminal remote from the shaft.

Shearer Oct. 23, 1923 Hartzell Feb. 13, 1940 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,116 379 December 31 1963 Frank M, Foster It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line 26, strike out "and the second electrical contact'h Signed and sealed this 23rd day of June 1964.,

ERNEST W. SWIDER v EDWARD J. BRENNER twisting Officer Commissioner of Patents M llllll UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3, 116,379 December 31 1963 Frank M, Foster It is hereby certified that error a ent requiring correction and that the sa corrected below. I

ppears in the above numbered patid Letters Patent should read as Column 6, line 26, strike out "and the second electrical contact'k Signed and sealed this 23rd day of June 196 1 (SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER tits/sting Officer Commissioner of Patents

Claims (1)

1. A CIRCUIT BREAKER COMPRISING A ROTARY SHAFT, MEANS FOR ROTATING THE SHAFT, A MEMBER SURROUNDING THE SHAFT AND EXTENDING TRANSVERSELY OF THE AXIS OF THE SHAFT, A PLURALITY OF CAM PORTION MEANS ON THE MEMBER EQUALLY SPACED FROM THE SHAFT CONCENTRICALLY WITH ITS AXIS AND SPACED FROM EACH OTHER ABOUT THE SHAFT FOR DISPLACEMENT OF A CAM FOLLOWER AXIALLY OF THE SHAFT, A FIRST ARM FIXED TO THE SHAFT FOR ROTATION THEREWITH AND EXTENDING RADIALLY THEREFROM, A SECOND RESILIENT FLEXIBLE ARM FIXED TO THE SHAFT FOR ROTATION THEREWITH AND EXTENDING RADIALLY THEREFROM, SAID FIRST AND SECOND ARMS BEING JUXTAPOSED AND SPACED FROM EACH OTHER AXIALLY OF THE SHAFT, CAM FOLLOWER MEANS DISPOSED ON THE SECOND ARM ENGAGEABLE WITH THE CAM PORTION MEANS FOR DISPLACING THE SECOND ARM IN OPPOSITE DIRECTIONS AXIALLY OF THE SHAFT RESPONSIVE TO ENGAGEMENT AND DISENGAGEMENT OF THE CAM FOLLOWER MEANS WITH THE CAM PORTION MEANS, A FIRST ELECTRICAL CONTACT ON THE FIRST ARM, A SECOND ELECTRICAL CONTACT ON THE SECOND ARM IN SPACED ALIGNED RELATION AXIALLY OF THE SHAFT TO

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