US3510670A - Two coil,triple point ignition system - Google Patents

Description

May 5, 1970 F. M. UHLAND TWO COIL, TRIPLE POINT IGNITION SYSTEM Filed March 1.5, 1968 Floyd M. Uh/and INVENTOR. Mm wig M 3m United States Patent 3,510,670 TWO COIL, TRIPLE POINT IGNITION SYSTEM Floyd M. Uhland, 73 Center Granview, Quincy, II]. 62301 Filed Mar. 15, 1968, Ser. No. 713,519 Int. Cl. H01h 1/6'0 US. Cl. 307- '7 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a battery ignition system for internal combustion engines and more particularly to an ignition distributor assembly.

Conventional automotive systems include an ignition coil primary winding serially connected between the voltage source and a normally closed point assembly through which an energizing circuit is completed. Upon periodic breaking of the points, due to urging of a rotating distributor cam, the circuit is broken thereby causing deenergization of the primary winding which in turn rapidly reduces the flux of the primary winding. This rapid flux reduction induces a large voltage in the secondary of the ignition coil which is distributed to the spark plugs of the internal combustion engine through a rotor assembly in a manner well-known in the art. As will be appreciated, opening of the points creates a large potential gap which ionizes the air therebetween causing arcing and unidirectional transfer of metal from one point to the other. Such action occurs at a high frequency until deterioration of the points render them useless because of oxidized metal deposits on the contact surface of one of the point contacts. A common expedient to prevent arcing across the gap is provided by connecting a capacitor across the points. Thus, upon breaking of the points, current from the energizing primary winding charges the capacitor instead of arcing across the points. Although it is theoretically possible to eliminate this arcing by employment of perfectly complementing ignition coil and capacitor characteristics, in practice such is difficult to achieve over an extended period of time, due to variation in electrical component characteristics. The art is replete with attempts to minimize this aforementioned point deterioration problem. One solution to the problem enompasses a dual point construction being actuatable by a common cam. The art combines these dual points in a multitude of combinations and permutations with ignition coils and capacitors in order to reduce the potential developed across the points when opened or to reduce the numeral of cycles per engine revolution.

In accordance with the present invention the foregoing problems are dealt with by reversing the arcing current to prevent unidirectional transfer of metal from point to point and thereby avoid accumulation of metallic deposits on the contact surface.

In summary, the present invention achieves the latter mentioned object by providing a dual point assembly operatively driven by a common cam. Each set of points in the dual point assembly opens alternately thereby achieving a total number of actuations during a single rotation of the cam equal in number to the cylinders in the internal combustion engine. A third assembly is provided and is actuatable in response to a second cam causing a number of third point assembly actuations per revolution of the cam equal in number to the cylinders of the englne. These latter mentioned points are connected to the dual point assembly thus providing the third point assembly with an alternating ground connection whereby arcing current is alternately conducted in opposite directions across the third point assembly. Thus, the present invention establishes a system which prevents unidirectional transfer of metal from one point to the other to prolong the useful life of an ignition circuit breaker point assembly with an attendant financial saving and maintenance convenience.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIG. 1 is a cutaway elevational view exposing the interior of a distributor.

FIG. 2 is a horizontal sectional view taken along a plane passing through section line 22 of FIG. 1.

FIG. 3 is a horizontal sectional view taken on a plane passing through section 3-3 of FIG. 1.

FIG. 4 is an electrical schematic diagram of the present invention.

Referring specifically to the drawings, and more particularly to FIG. 1, reference numeral 10 generally denotes the three-point contact breaker mechanism of the present invention disposed within a distributor housing 12. The three-point mechanism 10 comprises a first dual point assembly generally denoted by reference numeral 14 and a single point assembly 28 cooperating therewith as hereinafter explained. FIG. 3 illustrates the orientation of points in assembly 14 with relation to a distributor cam 16 suitably keyed to a rotating distributor shaft 18. By way of example, the present invention is associated with an 8-cylinder engine for which the cam is contoured. However, it will be apparent that the cam could be redesigned so as to operate successfully with an internal combustion engine with a number of cylinders other than eight. The peripheral surface of the cam 16 in the illustrated embodiment includes four equally spaced high points or lobes indicated by 20. A dwell surface 22 connects adjacent high points. A first contact point assembly 24 is disposed in relation to the cam 16 so that its cam follower 25 is displaced from the cam follower 27 of a second point assembly 26. Thus, when either cam follower 25 or 27 is positioned upon a high point 20 of the cam 16, the other cam follower will contact a dwell portion of the cam medially between two other high points. As will be appreciated, this arrangement will permit alternative actuation of the point assemblies 24 and 26 for firing S-engine cylinders during one revolution of cam 16.

Referring once again to FIG. 1 of the drawings, it will be noted that a third point assembly 28 is disposed in axially spaced relation to the aforementioned dual point assembly 14. As FIG. 2 clearly shows, the latter mentioned point assembly resembles a conventional single point assembly and is operatively actuated by a cam 30 having eight high points 32 equally spaced around the perimeter of the cam. In the present invention, cam 30 is disposed in spaced coaxial relation to cam 16 and is suitably keyed to the shaft 18 in fixed angular relation to cam 16. Attention is directed to the single point assembly 28 which illustrates an insulated connection to the point 68 instead of conventional grounding of said points to a grounded base plate for reasons to become hereinafter apparent.

Attention is directed to FIG. 4 which illustrates the various connections to circuit components of the present invention. As hereinbefore described, cam 16 actuates the first point assembly 24 having a first contact 38 thereof grounded. The second contact 36 thereof is connected to one side 40 of a capacitor 42, the opposite side of the capacitor being grounded. Connection between the contact 36 and capacitor 42 defines a primary winding 46. This primary winding is included in a conventional ignition coil (not shown). The opposite end 48 of the primary winding is connected to a DC. souce of voltage 50. As further illustnated in FIG. 4, the point assembly 26 includes a contact 54 connected to ground an a contact 52 connected to one end 56 of a second capacitor 58, the opposite end being grounded. Connection between the contact 52 and the capacitor 58 defines a junction point 60. This junction point is connected to a first end of primary winding 62, the latter forming part of a second ignition coil (not shown). The opposite end 64 of the primary winding is connected to the DC. voltage source 50. FIG. 4 further illustrates the circuit connections to the third point assembly 28 comprising a first contact 66 connected to the first mentioned junction point 47 connected to the first primary winding 46. Mating contact 68 is connected with the second mentioned junction point 60 connected to the second mentioned primary winding 62.

Considering the operation of the circuit described in FIG. 4, it is noted that during those times when dwell portions 22 on the cam 16 engage both point assemblies 24 and 26, all point assemblies are closed. This causes a closed series circuit between voltage source 50, primary 46, closed point assembly 24 and ground. Similarly, a series connection is completed between voltage source 50, primary 62, point assembly 26 and ground. Thus, both primary windings are energized. The cams 16 and 30 are angularly positioned on the shaft relative to each other to effectuate opening of point assembly 28 just a few degrees after the opening of either point assembly 24 or 26. FIG. 4 illustrates the state of affairs when a high point 20 of cam 16 opens point assembly 24. However, instead of arc development across the points 36 and 38 of point assembly 24 as occurs inconventional systems, the primay 46 is connected to ground through the closed points of point assembly 28 and point assembly 26 in series therewith. Should any arcing current be conducted across the point assembly 28 when it subsequently opens, it will be in a direction from contact 66 to 68 and then to ground via closed points assembly 26. Accordingly, deenergization of primary winding 46 occurs with a commensurate collapse of the field associated therewith. This in turn causes an induced secondary voltage for spark plug firing as occurs in conventional systems. As the high point on the cam 16 moves across the cam follower of point assembly 24, and as the same occurs with respect to cam 30 and its associated point assembly 28, all points are returned to closed positions thereby causing reenergization of both primary windings 46 and 62. From the position illustrated in FIG. 4, rotation of cam 16 through 45 causes contact between a high point on cam 16 and the cam follower of point assembly 26 thus forcing the points 52 and 54 of that point assembly to open. However, a break in the primary winding circuit connected in series with this point assembly does not occur because a continuing connection between the primary winding 62 and ground is maintained via the third point assembly 28 and point assembly 24. Accordingly, when point assembly 26 opens no arcing occurs. However, as previously occurred in connection with the actuation of point assembly 24, the third point assembly 28 opens several degrees after the opening of point assembly 26 thereby interrupting the energizing circuit of the primary winding 62. However, it is significant that any arcing current conducted through the open points 28 now occurs from contact 68 to contact 66. This arcing current direction is opposite from the arcing current which occurred upon the opening of point assembly 24 as hereinbefore explained. Accordingly, in the steady state operation of the device, arcing current is alternately reversed across the contacts of point assembly 28 thereby preventing transfer of metal therebetween. As will be appreciated, u-pon deenergization of the primary winding 62, a field collapse occurs as explained in connection with the first primary winding 46 which results in an induced voltage in the respective secondary winding associated with primary winding 62 for firing of a spark plug.

In effect, the dual point assembly including point assemblies 24 and 26 may be considered as current direction switching means for the third point assembly 28 for causing alternate deenergization of the primary windings 46 and 62.

When installed, dual point assembly 24 and 26 shown in FIG. 1 is mounted upon the base plate 70. In a similar manner, the single point assembly 28 is shown mounted upon base plate 72. It is noted that these base plates may be of a suitable form utilized in conventional distributors. Therefore, it will be appreciated that the present invention may be employed with conventional centrifugal and vacuum ignition advance means. All that is required is a common linking of base plate '70 and 72 so that they experience simultaneous angular adjustment with respect to the shaft 18 during mechanical ignition advance. The FIG. 1 further illustrates a distributor cap 74 which includes a number of peripherally disposed conventional connection sockets 75 into which are inserted leads 76 for connection with respective spark plugs (not shown). Because two primary coils are utilized, the distributor cap must include two input sockets 78. Such a construction is illustrated in Pat. No. 2,278,679, issued Apr. 7, 1942 to K. Staub.

It is noted that the present device is adaptable for cooperation with magneto ignition systems in a manner that should be obvious to one of ordinary skill in the art.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. In an ignition distributor system, a voltage source, first and second ignition coils connected in parallel to said voltage source, circuit breaker means connected to said ignition coils for energization thereof, and current reversing means actuated in synchronism with said circuit breaker means for alternately directing current therethrough in reverse direction during cyclic energization and deenergization of the ignition coils through the circuit breaker means, said current reversing means including, rotating cam means, first and second switch means sequentially actuated by said rotating cam means for opening normally closed circuits to the ignition coils, first and second capacitor means respectively connected to said first and second switch means in parallel with the respective ignition coils and means electrically connecting said switch means to the circuit breaker means for shunting the opened circuit to one of the ignition coils.

2. The combination of claim 1, wherein said circuit breaker means includes a breaker cam rotatably driven in synchronism with said rotating cam means, third switch means actuated by the breaker cam between sequential actuation of said first and second switch means, and means connecting said third switch means to said capacitor means for conducting current therethrough in opposite directions causing cyclically alternating deenergization of said ignition coils.

3. The system set forth in claim 1 wherein said rotating ca-m means is characterized by a peripheral surface having a plurality of equally spaced switch actuating portions thereon, said breaker cam having a number of equally spaced switch actuating portions thereon equal to twice the number of actuating portions on the rotating cam means causing sequential actuation of the respective switch means for preselected time intervals.

4. An ignition distribution device having a housing and a rotating shaft disposed therein, the combination comprising a first base plate mounted within said housing and having a central aperture through which said shaft extends, first switch actuating means operatively connected with said shaft and disposed in spaced overlying relation with said base plate, first and second switch means mounted in spaced relation on said base for sequential actuation by said first switch actuating means in response to rotation of the shaft, a second base plate attached to and rotatable with said first base plate in spaced relation thereto, second switch actuating means operaively connected to said shaft in angularly fixed relation to said first switch actuating means and third switch means mounted on said second base plate for actuation by said second switch actuating means in spaced time relation between actuation of said first and second switch means.

5. The apparatus set forth in claim 4 together with first and second ignition coil primary windings, first and second capacitor means, circuit means interconnecting said primary windings to respective first and second capacitor means and said aforementioned switch means for causing cyclic alternating energization and deenergization of said primary windings.

6. The apparatus set forth in claim 4 together with ignition advance means operatively connected with said first and second base plates.

7. A distributor switch assembly comprising first and 6 second switch means alternately opening and closing, third switch means connected to the first switch means for providing a momentary short circuit of the first switch means in response to opening of the first switch means to prevent arcing thereacross, means causing the opening of the third switch means moments after alternating opening of the first and second switch means, means connecting the third switch means to the second switch means upon the opening of the first switch means to effect arcing current flow across the third switch means in a first direction, the means connecting the first and third switch means eflfe'cting a reversed arcing current flow when the first switch means is closed and the second switch means is opened, the connection between the second and third switch means preventing arcing across the second switch means upon the opening thereof.

References Cited UNITED STATES PATENTS 1,487,002 3/1924 Adams 30710 2,195,612 4/1940 Carpenter 307-10 2,252,506 8/1941 Hartzell 30710 X 2,718,564 9/1955 Collins et al.

ROBERT K. SCHAEFER, Primary Examiner T. B. JOIKE, Assistant Examiner US. Cl. X.R. 290 3s; 307437

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