US3105481A

US3105481A - Ignition system

Info

Publication number: US3105481A
Application number: US159223A
Authority: US
Inventors: James C Hoiby; Harry E Jorgenson
Original assignee: ONAN DIVISION OF STUDEBAKER PA
Current assignee: ONAN DIVISION OF STUDEBAKER PA; ONAN DIVISION OF STUDEBAKER-PACKARD Corp
Priority date: 1961-12-14
Filing date: 1961-12-14
Publication date: 1963-10-01
Anticipated expiration: 1980-10-01

Description

3 Sheets-Sheet 3 Oct. 1,1963 J. c. HOIBY ETAL IGNITION svsma Filed Dec. 14, 1961 United States Patent 3,105,481 EGNITION SYSTEM James Hoiby and Harry E. .lorgenson, Minneapolis,

Minn, assignors to Gnan, Division of Studebaker- Pacitard (Iorporation, Minneapolis, Minn, a corporation of Minnesota Filed Dec. 14, 1961, Ser. No. 159,223 (Iiaims. (Cl. 123-179) The present invention relates to magnetos and more particularly to an improved flywheel magneto adapted for use with an internal combustion engine.

In flywheel magnetos of the type in present use, there is ordinarily included a stationary core structure carrying a generating coil and a permanent magnet which is carried by and rotates with the flywheel. These component parts cooperate during rotation of the flywheel to induce a magnetic flux within the core structure and the coils.

During either hand cranking or electrical starting of an engine with a magneto of this type, there is a danger of kickback if the spark occurs too far in advance to top dead center because spark actuation is fixed. The selection of this angle in many prior engines is a compromise between the angle of advance required to obtain maximum power during normal running and the angle of spark retardation required for starting the engine without the danger of kickback. As a result of this compromise, an engine using a conventional flywheel magneto is likely to kickback if not started with a strong pull or cranking motion.

In an attempt to overcome this problem, a number of spark advancing systems have been proposed for providing a first current pulse to the spark plug during normal running of the engine and a second or retarded pulse to be used during starting. One example of this type of ignition system is illustrated by the patent to Glenday et al., U.S. Patent No. 2,982,805. In the Glenday device there are provided two reversals of flux during each rotation of the crankshaft and a means is provided for activating the breaker points of the magneto during either the first or the second reversal depending upon whether advanced or retarded spark timing is de sired.

In contrast to the Glenday system, the present invention utilize-s an in-rush and a reversal flux rather than two flux reversals during each revolution.

Briefly, according to the present invention, an in-rush of magnetic energy into the magneto core causes the current in the coil of the magneto to change from zero to a plus or minus maximum and during the flux reversal, current in the coil changes from a maximum through zero to a maximum thereby providing double the potential diflerence found in a transition from zero to a plus or minus. Since the current in the coil windings is dependent upon the time rate of change of the flux, the maximum flux change during in-rush is dependent upon the velocity of the flywheel. As a result, at low engine speeds the current resulting from in-rush flux is below the amount desired for normal running. 'During flux reversal on the other hand, the relatively large flux change causes a much larger current which is sufficient to operate the engine at low engine speeds. By means of this system, it is possible to use a bipolar magnet rather than a three pole or other more complicated magnetic structure to produce the current required at low engine speeds. Moreover, the current resulting from the in-rush of magnetic flux will increase substantially at higher speeds and will therefore provide a strong spark at normal engine running speeds. The present invention also provides an improved speed responsive SJQSASE Patented Qct. 1, i963 means for advancing the spark timing above a predetermined rotational velocity.

It is one object of the present invention to provide an improved flywheel magneto of the type described wherein a simplified magnetic structure can be used to provide a first and second current peak, one peak being used for normal operation and the other being used for starting the engine.

It is another object of this invention to provide an. improved flywheel magneto of the type described wherein a current resulting from the in-rush of magnetic flux can be used for normal opera-ting speeds and a current resulting from reversal of magnetic flux can be used for starting the engine.

It is another object of this invention to provide an improved flywheel magneto which produces a first current peak for running and a retarded current peak of a greater amplitude for starting the engine wherein the first current peak increases in magnitude at high engine speeds.

It is still another object of this invention to provide an improved flywheel magneto of the type described having a simplified means for operating the breaker points at one angle relative to top dead center for starting the engine and at a diflerent angle for running the engine.

It is yet another object of this invention to provide 7 an improved flywheel magneto of the type described which is compact, reliable in operation and rugged in construction.

it is yet another object of this invention to provide an improved flywheel magneto of the type described wherein a simplified speed responsive means is provided for advancing breaker point operation relative to top dead center of the engine and simultaneously interrupting the operation of an engine starting motor.

These and other more detailed and specific objects will be disclosed in the course of the following specification, reference being had to the accompanying drawings, in which- FIG. 1 is a side elevational view partly in section of an internal combustion engine incorporating the present invention.

FIG. 2 is a vertical sectional view taken on line 2--2 of FIG. 1.

FIG. 3 is a schematic electrical circuit diagram of the magneto according to the present invention.

FIG. 4 is a vertical sectional view taken on line 4-4 of FIG. 2.

FIG. 5 is an enlarged view of the timing gear and associated elements partly broken away.

FIG. 5A is an enlarged view of a portion of FIGS. 4 and 5.

FIG. 6 is a vertical sectional view taken on line 6-6 of FIG. 4.

FIG. 7 is a graph showing the magnetic flux and primary current plotted against time at two different engine speeds.

FIG. 8 is a wiring diagram of the engine starter motor circuit.

FIG. 9 is a sketch showing the general features of the magnetic circuit arrangement of FIG. 2.

FIG. 10 is a vertical sectional view taken along the section line 10-10 of FIG. 9.

Referring now particularly to FIGS. 1 and 2, there is shown a flywheel magneto according to the present invention embodied in an internal combustion engine 10'. The engine It} includes the usual engine block 12,

cylinders

14 and 16,

pistons

18 and 20 and crankshaft 22. The

cylinders

14 and 16 are each provided with a spark plug 24, only one of which is shown in FIG. 1. Connected rigidly to the crankshaft 22 by means of bolts 26 is a flywheel 28 A field of circumferentially spaced apart

permanent magnets

30 and 32 is positioned on the inward surface of the flywheel. At the inward end of each of the magnets 311 and 32 are provided a pair of

pole pieces

34 and 36. The

structure comprising a pair inwardly facingsurfaces are curved to coact with a sta- Permanent magnet 32 is provided with a magnetic north pole at its inward end and a magnetic south pole at its outward end. The permanent magnet 30 is provided with a magnetic south pole at its inward end and a magnetic north pole at'its outward end. The flywheel 28 should either be formed from a magnetic material or in the alternative, provided with a magnetic material at 46 between the inward ends of the magnets 311 and 32 to act as a means for completing the magnetic flux circuit between them. As can be seen in FIG. 2, the directhrough which projects one end of the crankshaft 22.

Rigidly connected to the casing 511 is .a field structure comprising an ignition coil 54 and a core 56. The core 56 is made up oflaminations of 'a magnetic material and has three circumferentially spaced apart

legs

58, 611 and 62. The outward ends of these legs are spaced very close to the inward ends of

thelpole pieces

34 and 36,

' so that magnetic energy can be transferred from the permanent magnets to the core. The legs of the core are integrallyunited at their inner ends and extend more or less radially with the outerends circumferentially spaced apart and curved to coperate successively with the 'curved polar faces of the

pole pieces

34 and 36. A

sketch of the polestructure '56, showing the relative position of the above described apparatus may be seen in FIGS. 9 and 7 The coil 54 includes a primary coil 64 and a secondary.

coil 66 as shown in FIG. 3. The primary coil 64 is connected by means of conductors 68 and 7G in series with a set of breaker points 80 as best seen in FIGS. 3 and 6. A condenser 82 is connected across the breaker points 311 and the terminals of the, secondary coil 66 are connected by means of

conductors

84 and 86 to the respective spark plugs 24. a V

Mounted rigidly upon the crankshaft 2 2 is a gear W best seen in FIG. l.' Mountedrotatably upon the block 12 is a second gear 92 in driving engagement with the gear SW. The gear 12 is also in driving engagement with one end within a suitable opening 98 in thegear cover' 511 and at the other end within a suitable opening 1011 in support ;member 1112. The pin 96 is provided with an axial bore 97 at one end in which is mounted a plunger 99. Plunger 99 is urged outwardly bymeans of a spring 101. The end of the plunger 99' abuts against the end wall of the recess 1% thus'yieldably biasing the pin 96 toward the right as viewedin FIG. 4.

The support member 102 can be secured to the block 12 and gear coverfit) by means of

bolts

104 and 106. Gaskets 1118 are preferably provided between the block,

- j 12, cover 51) and members 1112, to provide aleak proof seal around the compartment 110 between member 102 and cover '50. The compartment 116 is preferably filled at least partially with oil.

' .posite sides ofthe' gear 94 are a pair of

weights

114 and 116. The outward movement of the free ends of the weights 114'and 116 can be limited by means of a tact assembly 1611 to energize the starting motor.

. 4 stop pin'118 extending through the gear 94. At the inward end of each of the

weights

114 and 116 is provided a gear sector 1211. The gear sectors 1211 are in driving engagement with gear teeth 122 provided on at least a portion of a cylindrical cam member 124 which is rotatably mounted upon the pin 96.

The cam member 124 is yieldably biased toward the gear 94 by means of a helical coil spring 126 connected between the pin 96 and the cam 124.

The free ends of the

weights

114 and 116 are urged inwardly by means of spring 1311 connected between the gear 94 and the weights as can be best seen in FIG. 5.

When the gear 94 is running at high speed, the free end of the

weights

114 and 116 will be thrown outwardly or to the right in the figure. Through the action of gear teeth 1211 and 122, the cam member 124 will therefore be rotated in a clockwise direction relative to the gear 94 as viewed in the figure;

As can be seen in FIGS. 4, 5 and 5A, the gear 94 is substantially provided with a V-sh-aped depression 132 in one face adjacent the opening therein through which the pin 96 extends. The sides of this depression comprise inclined-ramp surfaces. 132 is asubstantially V-shaped lobe 134 which extends outwardly or to the right in FIG. 4 from the right end of cam 124. The lobe 134 is so positioned with respect to pin 96, as viewed in FIG. 4. Lobe 134 slides into the depression 132, so that the end of lobe 134 is in contact with the left end of gear 94. g

Referring to FIGS. 4 and 8, a pair of contacts 1511 and .148 connected to

conductors

144 and 142 respectively are shown mounted on an insulating member 1411. The movable contact.148 is mounted on a resilient electrically conductive member 146 and is held in a normally open position by means of a pin 152'which extends through the wall of plate 102 and is in engagement with the end of cam 124 and so as to be positioned axially with respect to the position of cam 124 as described above. When cam 124 is in its extreme lefta'hand position, the cont-acts are maintained in an open position and when cam 124 is normally open contacts ldtl'and 148 to close. A

schematic diagram of a conventional starting motor control arrangement is shown in FIG. 8. A starting motor 147, suitably mounted in operative relationship on the stationary engine (not shown), is adapted to be energized from a battery 149'through conductor 142 and normally open contact assembly drivingly connected to relay winding 145. Relay winding is connected to the negative terminal of battery 149 through conduct-or 161 and to the positive terminal of battery 149through the conductor 162, a parallel'path comprised of norm-ally open manually operable switch means163 and normally open holding contact switch means 164 operatively connected to relay win-ding 165, normally closed de-ener gizing switch means 166 operatively connected to relay winding 167, conductor 168 and conductor 142. Itrnay be seen that closing of switch 163 through manual or other means serves to energize relay winding 145 which is held in by the closing of relay contact assembly 164 which establishes a holding circuit for relay winding 145. The energiz-ation of relay winding 145 serves to close normally open con- Normally open contacts 148 and 1541 are connected to battery 149 through conductor 142 and through conductor 144, relaywinding 167 and conductor 161.

ment' of cam 124 to its right-hand'position, relay winding 167' is energized to open its associated normally closed Cooperating with the depression,

When normally, open contacts 148 and 1511 are closed by-the. moveof the

weights

114 and 116 serves two functions.

contact assembly 166 which deenergizes relay winding 145 to de-energize the starting motor. Once relay winding 165 has been de-energized by the opening of contact assembly 166, the starter will not again be energized unless normally open contact assembly 163 is closed to complete a circuit to relay winding 145. The circuit shown in the schematic diagram of FIG. 8 is only an illustrative example as it will be apparent to those skilled in the art that normally

open contacts

148 and 150 may be utilized 'with a variety of starter motor control circuits and apparatus.

It will be thus understood that the outward movement The first is the rotation of the timing cam 124 with respect to the gear 94 to change the timing of breaker point operation as described hereinbelow and the second is the interruption of the starter motor as a result of the axial movement of the cam 124 on the pin 96.

As can be best seen in FIG. 6, the support member 102 is provided with a bore 160 in which there is slidably mounted a plunger 162. The plunger 162 extends radially outward from the cam 124 through a rubber diaphragm 164 which serves to seal the chamber in which the cam is contained. The free end of the plunger 162 is operatively associated with a breaker member 166 which is pivot-ally mounted on member 102 by means of pin 168. The member 166 includes a radially extending portion 170 upon which one of the breaker points as is positioned. Thus when the lobe of the cam 124 moves the plunger outwardly or to the right, as viewed in FIG. 6, the memher 166 will pivot in the clockwise direction thereby opening the breaker points 80 and allowing a pulse of current to be transmitted to one of the spark plugs 24. The points 80 are urged together and normally held in a closed position by means of a resilient spring 172. The operation of the magneto will now be described. As mentioned briefly above, because of the compromise in ignition timing for running and starting in a conventional engine, the engine is likely to kick back if not started with a firm pull or cranking motion. This problem is overcome with the present invention through the action of the speed responsive breaker point actuation, field and magnetic structures described above. Moreover the magneto described provides substantially uniform ignition cur. rents for both starting and running as contrasted with a conventional flywheel magneto which, in many cases, exhibits starting voltages of from one half to two thirds that of running voltage in the speed range of 100 to 300 rpm.

During operation, the permanent magnet pole group consisting of the

permanent magnets

34 and 32 in passing over the three leg laminated core 56 produces two major peaks of current in the primary coil 64. First of these peaks in point of time is designated A and the second peak is designated B. As can be seen in FIG. 7, the flux in coil 54 changes from zero to a first maximum value to create the relatively small peak A andfrom the first maximum through Zero to a second maximum value to create the second and correspondingly larger peak value B. Since the voltage output of ignition coil is directly proportional to the current interrupted in the primary, at rotational speeds of from about 100 to 300 rpm, for example, the maximum value of the current at B will be greater than that at A. The peak designated A results from a flux change due to the in-rush of flux as the magnetic group consisting of the

magnets

30 and 32 aligns itself with the first two legs of the core and the second peak B is due to the very rapid reversal of flux through the middle leg of the core as the magnet group consisting of

magnets

30 and 32 progresses so that each of the respective magnets is aligned with the last two legs of the core. As can be seen by comparing the two graphs of FIG. 7, as rotational speed is increased to an operating range of from 180*!) to 3600 rpm. for example, the amplitude of current peak at A will increase and approach that of peak B, while the maximum current at peak B changes little from the starting speed to the operating speed. When starting the engine, the cam 124 is set to interrupt the current at peak B thereby providing a retarded spark timing as well as more than adequate ignition voltage during engine starting. When the speed of the engine is increased above a predetermined point, the breaker point cam 124 is rotated by the action of the weights 1:14 and 116 thereby advancing the opening of the breaker points to coincide in time with the occurrence of peak A. The current peak at A will thus furnish the running ignition voltage.

The angular displacement between the peaks A and B is, of course, determined by the degree of angular separation between the

magnets

30 and 32. We have found that very good results could be obtained by providing an angular separation of 30 between the center lines of the magnets 39 and 32.

It is understood that suitable modifications may be made in the structure as disclosed, provided such modifications come within the spirit and scope of the appended claims. Having now therefore fully illustrated and described our invention, what we claim to be new and desire to protect by Letters Patent is:

1. An ignition system for an internal combustion engine comprising in combination; an engine including a rotatable crankshaft, a sparking member mounted within a combustion chamber of said engine, a source of magnetic energy mounted for rotation upon said crankshaft, electric current generating means stationarily mounted on said engine and in magnetic energy transferring relationship with said source of magnetic energy, said generating means including a pair of output terminals, a first switch means connected to said output terminals, actuator means responsive to the velocity of rotation of said crankshaft for operating said first switch means at relatively high rotational speeds upon an in-rush of magnetic energy to said generating means and for operating said first switch means at relatively low rotational speeds upon the reversal of the direction of magnetic energy transferred to said generating means, conductor means interconnecting at least one of said output terminals and said sparking member, a starter motor connected to said engine, circuit means interconnecting said starter motor and a source of energy therefor, said circuit means including means operable to energize said starter motor and means connected to said actuator means operable to dc-energize said starter motor at relatively high rotational speeds.

2. In an internal combustion engine including a rotatable crankshaft, a sparking member mounted in a combustion chamber of said engine, a source of magnetic energy and an electric current generating means having a coil, said coil having a pair of output terminals, said electric current generating means and said source of magnetic energy being mounted for relative rotation in correspondence with the rotation of said crankshaft and means interconnecting at least one of said output terminals and said sparking member, the combination comprising, a timing gear rotatably mounted upon said engine and connected in driving relationship with said crankshaft, a pair of Weights, each of said Weights being pivotally connected at one end to either side of said timing gear, spring means yielda-bly biasing the free ends of said weights inwardly, a gear sector on each of said weights, a cam member rotatably mounted adjacent to said timing gear, said cam member including a plurality of gear teeth in driving engagement with said gear sectors whereby outward movement of the free end of said Weights will cause rotation of said timing cam with respect to said timing gear, breaker points connected in series with said coil and operatively associated with said cam, a lobe on one end of said cam, said timing gear having a depression in the face thereof, said depression being positioned in correspondence with the position of said lobe when the cam is rotated with respect to said timing gear to a predetermined position, a

, r c r 7 starter motor operatively connected to said engine and a switch means connected to turn off and on said starter motor, resilient means yieldably biasing said cam means axially toward said timing gear, a member slidably mounted within said engine between a portion of said cam and said switch means whereby rotational movement of said cam relative to said timing gear will cause said lobe to engage said recess thereby allowing said timing cam to move axially toward said gear and the corresponding movement of said member being adapted to actuate said switch means to stop sa-id starter motor. 7

3. In an ignition system for an internal combustion engine having a rotating crankshaft, the combination comprising; a bi-polar source of magnetic energy mounted for rotation in correspondence with said crankshaft, the poles of said source of magnetic energy having center lines of on said core, mounting means for said core and said source of said magnetic flux to provide relative rotational movement between said core and said source of flux,

means drivingly connected between said mounting means and the crankshaft of said internal combustion engine, a

' pair of normally closed contacts connected in series with open at relatively high notational speeds when said two a predetermined angular displacement; electric current generating means stationarily mounted with respect to 7 magnetic poles are positioned substantially opposite the first and second iegs of said core and to retard said cam at relatively low rotational speeds to a second position adapted to open said breaker points when said poles are positioned adjacent said second and third legs of said core,

a starter motor mounted in operative relationship to said internal combustion engine, and circuit means connecting said starter motor when said last named means is opercrankshaft; a weight pivotally mounted tart ne end upon 1 the rotatable member, the other end of said weight being adapted to move outwardly when said member is rotated at a predetermined speed; a timing cam rotatably mounted with respect to said member and said weight being operativelyt connected to'said timing cam to rotate said timing cam relative to said member when the free end of said Weight is thrown outwardly by centrifugal force; resilient means operatively associated with said weight for yieldably biasing the free end of said weight inwardly relative to the axis of rotation of said member; normally closed switch means connected in series with said primary winding and operatively associated with said timing cam, said timing cam being positioned with the free end of said weight atits inward position to open said switch means during'the reversal of magnetic energy through said coil and positioned with the free end of said weight at its outward position to open said switch means during anin-rush of magnetic energy through said core member; a starter motor mounted on said engine; and circuit means interconnecting said starter motor with a source of energy therefor, said circuit means including means forenergizing said starter motor and means responsive to the. movement of said cam member to said outward position to deenergize said starter motor. I

4. In an internal combustion engine, a core having three able in one position and for allowing energization of said a starter motor when said-means is in another position.

5. In combination with an internal combustion engine having a rotatable crankshaft and a sparking member mounted within a combustion chamber; a bi-polar source of magnetic energy mounted for rotation on said crankshaft; means responsive to variations in magnitude and direction of magnetic energy sta-tionarily mounted on said engine and in energy transferring relationship with said source of magnetic energy, said means including a pair of output terminals and having a three-legged core member of magnetizable material; switch means connected to said pair of terminals; speed responsive means connected to said switch means for actuating the same in timed relationship with said crankshaft whereby said switch means is actuated for a change in flux in said core member in one direction for a relatively low speed and said switch means is actuated during a change in flux in another direction for high speeds; means interconnecting said ouput terminals to said sparking members; a starting motor mounted in operative relationship upon said internal combusti-on engine; and circuit means interconnecting said starting motor with a source of energy therefor, said circuit means including means for energizing said starting motor and means connected to said speed responsive means for de-energizing said starting motor in accordance with the position of said speed responsive means for relatively high rotational speeds.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

1. AN IGNITION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE COMPRISING IN COMBINATION; AN ENGINGE INCLUDING A ROTATABLE CRANKSHAFT, A SPARKLING MEMBER MOUNTED WITHIN A COMBUSTION CHAMBER OF SAID ENGINE, A SOURCE OF MAGNETIC ENERGY MOUNTED FOR ROTATION UPON SAID CRANKSHAFT, ELECTRIC CURRENT GENERATING MEANS STATIONARILY MOUNTED ON SAID ENGINE AND IN MAGNETIC ENERGY TRANSFERRING RELATIONSHIP WITH SAID SOURCE OF MAGNETIC ENERGY, SAID GENERATING MEANS INCLUDING A PAIR OF OUTPUT TERMINALS, A FIRST SWITCH MEANS CONNECTED TO SAID OUTPUT TERMINALS, ACTUATOR MEANS RESPONSIVE TO THE VELOCITY OF ROTATION OF SAID CRANKSHAFT FOR OPERATING SAID FIRST SWITCH MEANS AT RELATIVELY HIGH ROTATIONAL SPEEDS UPON AN IN-RUSH OF MAGNETIC ENERGY TO SAID GENERATING MEANS AND FOR OPERATING SAID FIRST SWICTCH MEANS AT RELATIVELY LOW RATIONAL SPEEDS UPON THE REVERSAL OF THE DIRECTION OF MAGNETIC ENERGY TRANSFERRED TO SAID GENERATING MEANS, CONDUCTOR MEANS INTERCONNECTING AT LEAST ONE OF SAID OUTPUT TERMINALS, AND SAID SPARKING MEMBER, A STARTER MOTOR CONNECTED TO SAID ENGINE, CIRCUIT MEANS INTERCONNECTING SAID STARTER MOTOR AND A SOURCE OF ENERGY THEREFOR, SAID CIRCUIT MEANS INCLUDING MEANS OPERABLE TO ENERGIZE SAID STARTER MOTOR AND MEANS CONNECTED TO SAID ACTUATOR MEANS OPERABLE TO DE-ENERGIZE SAID STARTER MOTOR AT RELATIVELY HIGH ROTATIONAL SPEEDS.