US2090365A - Motor ignition apparatus - Google Patents

Description

Aug. 17, 1937. G. c. HARRIS MOTOR IGNITION APPARATUS Filed March 5, 1956 INVENTOR TTORNEY Patented Aug. 17, 1 937 MOTOR IGNITION APPARATUS Gwin C. Harris, Orange, N. 1., assignor to Thomas A. Edison, Incorporated, West Orange, N. J., a corporation of New Jersey Application March 5, 1936, Serial No. 67,219

14 Claims.

This invention relates to ignition systems, and more particularly to systems of the type employed in connection with internal combustion motors. The principal object of the invention is to increase the intensity of theigniting sparks produced by the system, not only at the time of starting of the motor but also thereafter for a shortinterval; for during such interval the motor temperature is yet low and the battery may yet 1U remain in the condition of abnormally low charge to which it has been reduced by the immediately preceding operation of the starter and by the further preceding period of idleness. The invention of course contemplates this increased spark 1;, intensity as a temporary function only, since the concomitantincreased primary current would, if a continuous function, seriously impair the conventional breaker points.

There are known in the art a variety of devices 90 directed toward a generally similar end. Insofar as I am aware, however, such of those devices as have provided improved spark intensity for an appreciable interval after motor starting have been so arranged as to render that interval mate- 5 rially dependent on characteristics of the ignition system which are differently established in different systems, and on characteristics which in any one ignition system are conmionly permitted to vary at random over a considerable rangewith 30 the results, among others, that the mentioned interval not only has varied between different systems to which the device might be applied, but also in any one system has from time to time fluctuated widely, in the absence of repeated and 3 critical adjustments of the device. Furthermore, insofar as I am aware, the current-making and -breaking portions of all those devices have invariably been of the simpler forms which are subject to, impairment and failure with operation 40 and even mere passage of time, with the result that the benefits of the device were frequently lost and/or permanent damage done to other components-and this, in view of the auxiliary nature of the device,sometimes without being perceived 45 by the motor operator.

It is an object of my invention to provide increased spark intensity -t the time of starting of the motor and thereafter for an appreciable interval which is substantially unaffected by variations in adjustments and in characteristics of the ignition system.

- It is another object of my invention to provide, in association with an ignition system, automatic 55 means of improved dependability and life for effecting increased spark intensity during starting and initial motor operation.

It is another object of my invention to provide in association with an' ignition system, generally improved such automatic means.

It is another object of my invention to provide such automatic means of a form well adapted for interchangeable installation on ignition systems of different characteristics. I

Still another object is to provide such automatic means adapted for substantially uniform operation with an ignition system whose adjustment may change from time to time.

. Other and allied objects will more fully appear from the following description and the appended claims.

In the description reference is had to the accompanying drawing, of which:

Figure 1 is a diagrammatic view illustrating a first embodiment of my invention.

Figure 2 is a like view illustrating a modified embodiment; and

Figure 3 is another like view, but illustrating a further modified, and in certain respects preferred, embodiment.

The conventional portions of Figure 1 are first conveniently described. The numeral i designates a storage battery, such as is commonly employed in connection with the internal combustion motor of an automobile or other motor vehicle, with one of its terminals (for example the negative) grounded, as to the vehicle frame. The letter M designates an electric starting motor arranged to crank the internal combustion motor and having one terminal grounded; the openly biased switch S when closed connects the starting motor M with the battery I. The switch 2 is the ignition switch", which when closed connects the lead 5 with battery I; the lead 5 is then arranged to supply current to the ignition sys: tem, which comprises the coil or transformer 4 wound upon the core C, the condenser I4, the current interrupter or circuit breaker 9, the distributor l9, and the spark plugs of the motor. The lead 5 is connected to one extremity of the primary- 3 of the coil 4, the other extremity of which primary is connected through lead I with the breaker contact or point 8. The other breaker point Il is carried by the arm in and is oscillatorily moved into and out of contact with the point 8; it is connected by the lead l2 to ground at l3. Across the'points is shunted the condenser M. In series with the coil primary 3 is'connected the secondary l5, which in turn is connected through lead I! to the distributor arm i8. Wires the plug gap 22 is produced by the breaker 9' V interrupting the flow of current through the pril mary 3, and that the intensity of the spark is a function of the parameters of the coil 4, and 'of the rate of decay of current in the primary circuit ensuing the interruption.

In the arrangement of Figure 1 I insert an impedance, for example the resistance 38, in series with. the ignition primary circuit, and alter the coil parameters so that with this impedance in circuit I provide a spark of normal intensity. I provide in shunt to the impedance a switch (31) which ordinarily during motor operation I maintain open, thus then maintaining the impedance included in circuit and providing the spark of normal intensity. During the desired periods, however, the switch 31 is closed to short the impedancei. e., to exclude or effectively disconnect the impedance from circuitand thus to provide increased primary current, correspondingly increased rate of decay thereof upon each interruption, and accordingly a spark of extra intensity. The illustrated resistance 38 (with switch 31) may be mechanically housed in a convenient container 6, and is electrically inserted in the lead .5, dividing the latter into portions 5" and 5' respectively on the battery and coil 35 sides of the resistance. The thermostatic switch 31, which has been shown shunted about the resistance 38 by leads 48 and 49, includes an arm 42 (shown connected to the lead 5') carrying contact 44, and a bimetallic arm 4! (shown connected to the lead 5") carrying contact 43both arms being for example mounted to an insulating block 45, and the arm 4! being biased or tensioned so that contact 43 tends to touch contact 44 but being heat-responsive to move contact 43 away 45 from contact 44. A heater element is closely associated with arm 4l-for example, wound about the latter-so that upon its traversal by sumcient current for a sufllcient time it will raise the temperature of the arm 4| sufficiently to 50 throw-i. e., to open-the switch 31.

Similar arrangements, but with the responsive element biased to open the switch and heat-responsive to close it, have been employed with the heater coil in parallel or series with the starting motor; these, however, have provided increased spark intensity substantially only during starting (1. e., while the starter switch was closed), or have carried over their effects for very minute intervals thereafter by virtue of a sluggish thermal response. which in turn prevented their coming into action'promptly when the starting operation was begun. Also other arrangements, with the responsive switch biased closed and heat responsive to open, have been employed with the heater element so connected as to respond to the primary circuit current, thereby providing extra spark intensity for the interval until the primary circuit current has suificiently heated the heater element to open the switch. But the primary current has an average or heating value which is materially dependent not only on the particular coil employed but also on the adjustment and condition of the breaker points; accordingly the interval during which the extra spark intensity has been provided has been a very variable one from installation to installation, or from time to time. Instead of following these known arrangements, I connect the heater element 50 from the lead 5" to ground (through lead 48, and through lead 5! to point 52)-i. e., in parallel with the ignition system, or across the serially disposed ignition switch and battery-so that from the time of closing of the switch 2 the heater element 50 is traversed by a current whose amplitude is fixed (excepting for influence of battery voltage) solely by the characteristics of the heater element itself. These characteristics, together with the other characteristics of the switch 31 and particularly its arm 48, principally determine in this arrangement the interval of time from closing of switch 2 during which the switch 8'! will remain closed and the extra spark intensity provided. All of these characteristics being capable of fairly accurate control, the time interval may be fairly closely predetermined without difficulty. The interval will of course be somewhat aifected by the ambient temperature, for this afiects the initial temperature of the arm 4| at the time of closing of switch 2; but this influence is only a moderate one, and furthermore is in a useful rather than harmful direction, in that it tends to render the interval longer the lower the ambient, and vice versa. I have preferred ordinarily to make this interval, at normal temperatures, of the order of one-third of a minute to one minute.

It will be appreciated that because of the continuing flow of current through the heater element during motor operation the switch 31 of course then stays open; after the ignition switch 2 has been opened and the motor permitted to remain idle for an appreciable time, the switch 37 will have cooled and closed and thus prepared the system again to provide increased spark intensity for an initial interval.

In such thermostatic arrangements as have been employed in the past for automatic ignition regulation, the current-making and -breaking ,contacts (such as 43, 44) have been freely exposed to the atmosphere; their operation has always proven unsatisfactory and, insofar as applicant is aware, none of them has proven commercially practicable. The fundamental cause, peculiar to a thermostatic switch opening which is to take place not rapidly but ratherafter an appreciable heating interval of the order of onethird of a minute to one minute, appears to be r the slow and small opening of the contactswhich, in the appreciably inductive primary circuit, causes serious arcing, disintegration, and overheating of the contacts, and sputtering or irregular transfer of material from the one to the other. Then either the contacts become so impaired that they fail to close electrically, and the extra spark intensity is not provided-sometimes without the fact being appreciated by the motor operator; or in more extreme cases the contacts will fuse together, providing permanently increased spark intensity and primary current, to the great detriment of the life of the breaker points (e. g., 8 and II). A secondary causeof unsatisfactory results, also operating by impairing the current-making and -breaking contacts, has doubtless been contamination of the contacts by oil, grease, and the condensation of vapors thereof, almost unavoidable in the immediate vicinity of a combustion motor.

I completely avoid these causes of failure, and at the same time render the thermostatic switch proof against accidental or ill-advised mal-adjustments, as well as minimize the electrical power requirements for initially opening and maintaining open the switch, by enclosing the entire switch including the heater coil in a sealed glass or other envelope 40 which is evacuated of air. (Optionally a small amount of one or another gas may after evacuation be inserted in the envelope for one or another special purpose, such for example as a trace of hydrogen for "cleaning" purposes, as will be understood.) In practise the switch is asl0 sembled onto a stem 40' and adjusted in open air for its desired characteristics, the stem thereupon being sealed into the envelope 40 to form a part thereof, and the latter evacuated. By the substitution of substantial vacuum for normal atmosphere about the switch I render it, inspite ofthe slow and small opening required by its use, better proof against contact arcing, 'disintegration, overheating, and sputtering than is a fast and wide opening switch in normal atmosphere.

It is also apparent that the switch is now proof against contamination by foreign matter and against mal-adiustments, and that a minimum of power will be required to raise the arm U to and maintain it at any given temperature.

The arrangement of Figure 1 employs a coil 4 which may be of usual commercial design, but must be of parameters somewhat altered from the usual. In Figure 2 I have shown an alternative arrangement wherein is employed a coil which may be of usual parameters, but comprises an additional portion. This coil has been designated as 4, its core as C, its regular or main primary as 3, its secondary as I5, and its additional portion-an auxiliary primary-as II.

In Figure 2 the conventional portions are as in Figure 1, the lead 5-this time unbroken-connecting the ignition system with the ignition switch 2 and battery I. The thermostatic switch 31, of course again desirably sealed in the evacuated envelope II, is again employed and may in this case form the sole contents of the convenient enclosure 0. The heater element 50 of the switch is connected from lead I through lead 0, and through lead SI to. ground at 5!. The switch arm ll is connectedas before to lead I (and therethrough to lead 5) while the arm 42 is connected through the lead I! to the auxiliary primary 83 and therethrough and through lead it to the breaker point I and condenser l4-i. e., the thermostatic switch proper is serially disposed with the auxiliary primary, and together they are in parallel with the main primary 3'. Since the coil 4', considered without the auxiliary primary II, is of normal parameters, it will be obvious that again when switch 31 is open (and the auxiliary winding therefore excluded from circuit) a spark of normal intensity is provided. Auxiliary winding 33 is wound in aiding inductive re tionship to the main primary 3', and is para lel with so the latter when switch 31 is closed; there is accordingly then provided increased total primary current and hence increased rate of decay thereof upon interruption. So again when switch is closed extra spark intensity is provided; and

66 the times or periods of open and closed conditions of switch 31 are of course as in the case of Figure 1.

In Figure 3 I show an arrangement which I have preferred becauseit employs a coil 4" which may be both of usual commercial design and of usual parameters. This coil has been designated as l", with core C, primary 3" and secondary IS". The circuit arrangement is precisely that of Figure-2, excepting that there is omitted the auxiliary primary and in its place in series with the thermostatic switch proper-i. e., between leads 4! and ll-is inserted a "booster" coil I, wound upon an individual core 0. This coil is conveniently housed in the container 8, along with the thermostatic switch 31 in its sealed and evacuated envelope 40. It will be obvious that the function of this arrangement will be identical with that of Figure 2, provided the booster-coil ll perform the same function as the auxiliary primary 33 of Figure 2. The booster coil does perform the same function of increasing the rate of primary current decay upon interruption. It is to be noted, however, that whereas the auxiliary primary performed this function by increasing the .primary current (i. e., current through the entire coil primary means), the booster coil (which is not a coil primary) increases the rate of current decay in the primary I 3" apparently by strongly opposing any residual current flow therein after the instant of interruption by the breaker 9. For both booster coil (as long as it is rendered active by a closed switch 3'!) and primary 3" are in parallel and together form a closed circuit; and the residual currents produced in that circuit by the simultaneously collapsing fields of both coils tend to neutralize each other and so to produce the high rate of primary current decay.

In review of the three illustrated embodiments it will be noted that in the arrangement'of Figure 1 there is included in circuit a device for reducing the rateof decayand the spark intensity; and that thethermostatic switch is biased to remove the device from circuit, but upon being thrown by the heater element reinserts the device. On the other hand in each of the circuits of Figures 2 and 3 there is providcd a device adapted for inclusion in circuit to increase the rate of decay and spark intensity; and that the thermostatic switch is biased to insert the device, but upon being thrown by the heater element removes the device from circuit. It is to be understood, however, that I do not intend my invention to be limited by the details of these embodiments: rather I intend to express its scope in the following claims, as broadly as the state of the art will permit.

I claim:-

' i. In a motor system having a current source, and an ignition system arranged for connection thereacross and adapted to produce an igniting spark: means for altering the intensity of said spark, and a thermostatic switch for controlling said altering means, said thermostatic switch including and being responsive to a heating element connected in parallel with said ignition system.

2. In a motor system having a serially disposed current source and ignition switch, and an ignition system connected thereacross and adapted to produce an igniting spark: means for altering the intensity of said spark, and a thermostatic switch for controlling said altering means, said thermostatic switch including and being responsive to a heating element connected across said current source and ignition switch.

3. In a motor system having a current source, and an ignition system arranged for connection thereacross and serially including primary winding means and a current interrupter: a device adapted for electrical inclusion in and exclusion from said ignition system to alter the rate of decay of interrupted primary current, and a thermostatic switch for effecting such inclusion and exclusion, said thermostatic switch including and being responsive to a heating element connected in parallel with said ignition system.

4. In a motor system having a serially disposed current source and ignition switch, and an ignition system connected thereacross and serially including primary winding means and a current interrupter: a device adapted for electrical inclusion in and exclusion from said ignition system to alter the rate of decay oi interrupted primary current, and a thermostatic switch for efiecting such inclusion and exclusion, said thermostatic switch including and being responsive to a heating element connected across said current source and ignition switch.

5. In a motor system having a current source, and an ignition system arranged for connection thereacross and serially including primary vinding means and a current interrupter: a device included in said system for reducingthe rate of decay of interrupted primary current; athermostatic switch connected with said device and biased to render said device inoperative; and a heating element forming a throwing means for said thermostatic switch and connected in parallel with said ignition system.

6. In a motor system having a serially disposed current source and ignition switch, and an ignition system connected thereacross and serially including primary winding means and a current interrupter: a device included in said system for reducing the rate of decay of interrupted primary current; a thermostatic switch connected with said device and biased to render said device inoperative; and a heating element forming a throwing means for said thermostatic switch and connected across said current source and ignition switch.

7. In a motor system having a current source, and an ignition system arranged for connection thereacross and serially including primary winding means and a current interrupter; an impedance connected in series with said system; a thermostatic switch biased closed to short-circuit said impedance; and a heating element forming' an opening means for said thermostatic switch and connected in parallel with said ignition system.

8. In a motor system having a serially disposed current source and ignition switch, and an ignition system connected thereacross and serially including primary winding means and a current interrupter: an impedance connected in series vwith said system; a thermostatic switch biased closed to short-circuit said impedance; and a heating element forming an opening means for said thermostatic switch and connected across said current source and ignition switch.

9. In a motor system having a current source, and an ignition system arranged for connection thereacross and serially including primary winding means and a current interrupter: a device adapted upon electrical inclusion in said ignition system to increase the rate of decay of interrupted primary current; a thermostatic switch connecting said device and system and biased to eflect such inclusion; and a heating element forming a throwing means for said thermostatic switch and connected in parallel with said ignition system.

10. In a motor system having a serially disposed current source and ignition switch, and an ignition system connected thereacross and serially including primary winding means and a current interrupter: a device adapted upon electrical inclusion in said ignition system to increase the rate oi! decay of interrupted primary current; a thermostatic switch connecting said device and system and biased to effect such inclusion; and a heating element forming a throwing means for said thermostatic switch and connected across said current source and ignition switch.

11. In a motor system having a current source, and an ignition system arranged for connection thereacross and serially including a main primary winding and a current interrupter: an auxiliary primary winding inductively coupled to said main primary winding; a thermostatic switch biased closed to shunt said auxiliary winding across said main winding; and a heating element forming an opening means for said thermostatic switch and connected in parallel with said ignition system.

12. In a motor system having a serially disposed current source and ignition switch, and an igni-- tion system connected thereacross and serially including a main primary winding and a current interrupter: an auxiliary primary winding inductively coupled to said main primary winding;

a thermostatic switch biased closed to shunt said auxiliary winding across said main winding; and a heating element forming. an opening means for said thermostatic switch and connected across said current source and ignition switch.-

13. In a motor system having a current source, and an ignition system arranged for connection thereacross and serially including primary winding means and a current interrupter: a booster coil a thermostatic switch biased closed to shunt said booster coil across said winding means; and a heating element forming an opening means for said thermostatic switch and connected in parallel with said ignition system.

14. In a motor system having a serially disposed current source and ignition switch, and an ignition system connected thereacross and serially including primary winding means and a current interrupter: a booster coil; a thermostatic switch biased closed to shunt said booster coil across said winding means; and a heating element forming an opening means for said thermostatic switch and connected across said current source and ignition switch.

GWIN C. HARRIS.

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