US2018159A

US2018159A - Electrical fuel injection system for internal combustion engines

Info

Publication number: US2018159A
Application number: US731446A
Authority: US
Inventors: Walker Brooks; Harry E Kennedy
Original assignee: Individual
Current assignee: Individual
Priority date: 1934-06-20
Filing date: 1934-06-20
Publication date: 1935-10-22
Anticipated expiration: 1952-10-22

Description

Oct. 22, 1935. a. WALKER ET AL 5 ELECTRICAL FUEL INJECTION SYS TEM'FOR INTERNAL COMBUSTION ENGINES Filed June 20, 1934 INVENTORJ. 75W

. BY 51W @wnsmaL-w ATTORN s.

Patented Oct. 22,1935

UNITED STATES PATENT OFFICE ELECTRICAL FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES Application June 26, 1934, Serial No. 731,446 29 Claims. (01.123-32) This application is a continuation in part of our copending application entitled Fuel injection system for Diesel engines, filed September 10, 1930, bearing Serial No. 480,960.

Our invention relates to electrical fuel injection systems for internal combustion engines of the type wherein the air charge of the combustion chamber is constant regardless of engine speed or throttle position, and wherein the fuel is injected into the combustion chamber in spray form. In internal combustion engines of this type, ignition may be eifected as in the "Diesel cycle, the Otto cycle or by means of the method of ignition fully described and claimed in United States Letters Patent.#l,903,381, issued Aprill l, 1933 to Harry E. Iennedy. We prefer the latter inasmuch as high firing pressures and uncontrolled ignition lag. are avoided enabling relatively high speeds in engines of comparatively light weight per horsepower.

Prior to our invention two methods of injecting fuel into the combustion chamber of internal combustion engines operating on the cycles above referred to were in general use. The first method is what is most commonly known as the jerk pump system in which an. individual fuel pump is provided for each cylinder of the engine. The plunger of this pump acts to create the pressure necessary for injection and at the same time meters the fuel charge. To throttle the engine, the displacement of this pump is varied. This system has limitations which render it practically unsuitable for high speed engine operation, and by high speed we means speeds in excess of say approximately 2000 R. P. M. This is manifest when it is realized that in this system as the engine speed increases, the hydraulic pressure applied to the injection nozzles increases with great rapidity due to the fact that the displace ment stroke of the pump plunger must take place through a constant crank angle. Therefore, in order to effect the injection of a constant charge of fuel at all speeds, the pressure of the fuel at the nozzle or spray valve orifice must vary as the square of the engine speed. Consequently, when comparatively high engine speeds are appreached, the hydraulic pressure of the'fuel between the pump and the nozzle rises to a point rendering the system impractical because of mechanical limitations. Further, the plunger of the pump may complete its displacement stroke but due to the compressibility of the fuel, injection through the nozzle may lag resulting in late burning of the fuel in the combustion charm her and consequently inemcient engine operation.

It has also been observed that in this system detrimental vibrations are set up in the fuel column between the pump and the spray nozzle by the action of the pump plunger, which vibrations or pulsatiqnsresult in irregular or erratic injection of each'charge to the detriment of proper combustion and engine operation.

In general, the second well known method of injecting fuel into the combustion chamber of internal combustion engines operating on the ill cycles above set out is commonly termed the common rail system. In this system there is a common source of fuel, which is maintained under a substantially constant pressure, for all of the cylinders of the engine. The injection 15 into the individual cylinders is effected in proper timed relation to the piston strokes through the medium of spray valves which are mechanically actuated at properly timed intervals from the crankshaft of the engine. That is to say, these 20 spray valves are open tmough a predetermined crank angle which may be varied to effect throttling. Obviously, this angle must be increased as the engine speeds increase in order that sumcient time will elapse to enable injection of the proper fuel charge. There is a limit to which the crank angle can be increased without causing late burning with consequent inefficient operation, and it has been found that in using the rail pressure system, this maximum crank angle is insufficient in higher speeds to enable injection of a proper fuel quantity without the use of excessive fuel pressures. When the maxi mum crank angle and fuel pressure is reached, increasingly smaller 'fuel charges are introduced into the cylinder as the engine speed is increased, resulting in loss in torque at the higher speeds.

In both of the above systems, in order to effect the discharge or injection of a sufficient quantity of fuel at the higher speeds, the size of orifice in the spray jet must necessarily be so large that when the-engine is throttled at reduced load, atomization would becomeso poor that inefflciept combustion and consequent poor engine operation would result. Another disadvantage which is common to both of the above systems of fuel injection is that in the smaller bore engines where the fuel charge is minute, the wear and manufacturing variations of the mechanical parts prevents accurate metering with consequent inefficient operation. This in multiple cylinder engines prevents proper balance between the cylinders and ragged uneven engine operation. I

There have been many attempts to employ electromagnetic injection valves in connection with internal combustion engines. Such valves were operated by connecting the windings of the valve to a source of electromotive force through the medium of an engine driven contacting ,ously known injection mechanism. These types of injection systems lack the, inherent characteristics essential for proper injection, for the reason that in. order that the current for operating the valve may not reach excessivevalues, the winding of the valve must consist of many turns of fine wire so "that it will have suflicient resistance to limit the current to a safe value. The inductance of such a winding is, therefore, correspondingly high and the circuit must have a large time constant. The current in such a winding builds up comparatively slowly so that the maximum value of the magnetic force available does not appear until a comparatively long interval after the closing of the contact. This at high speed may not reach a value high enough to lift the valve at all. Assuming, however, that the current reaches a value sufficient to lift the valve, the reluctance of the magnetic circuit will have been enormously reduced and in consequence the winding will have become more highly inductive. When the contacts open, they will be required to rupture the maximum current with consequent vicious sparking at the contact points and the development of high eddy current within the structure of the valve, tending to retard the closing thereof. Such a system has inverse characteristics to those which are required. -It provides a minimum force when the maximum is necessary at starting and develops the maximum force at substantially the moment when it is required to close the valve. Furthermore, if the engine stalls with the contacts closed, the cylinder will be flooded with oil and the battery run down. This accounts for the indifferent success of prior attempts to accomplish electrically what had previously been done mechanically.

It is the principal object of our present invention to provide an electrical fuel injection system for internal combustion engines which overcomes all ofthe disadvantages of prior systems and which will operate efllciently under a moderate constant fuel pressure to inject, during a relatively short angle of the engine crankshaft rotation, an accurately metered quantity of fuel, regardless of whether the fuel charges are minute, at properly timed intervals through a speed range far exceeding the limits of previsystems.

To accomplish our object we provide anelectrical fuel injection system which includes a common source of fuel maintained under substantially constant pressure. The injection into each cylinder is effected through the medium of a magnetic injection valve which is electrically operated to effect injection at properly timed intervals relative to the piston operation. At wide open throttle the injection valve is held open for a constant time interval regardless of the engine speed and, therefore, regardless of engine speed, a constant quantity of fuel will be injected into the cylinder under a constant fuel pressure so that the torque will not diminish with engine speed, and the injection pressure need not vary with engine speed. At reduced throttle for a. given load, a decrease of that load tends to increase the engine speed. This is compensated for by a. corresponding decrease in the fuel charge as the speed increases. Likewise, if

the load increases and the engine speed decreases, the fuel charge is automatically in creased. Therefore, the system is absolutely and inherently self-governing. To operate the injection valves in this manner we have provided 5 a source of electromotive force and a condenser which is electrically connected with the source of electromotive force and with the magnetic injection valve. The charge and discharge of this condenser is engine controlled so that the condenser will act as a. medium by which electrical impulses are periodically delivered from" the source of electroinotive force to the valve for operating the latter at properly timed in-' tervals, the capacity of the condenser, of course, 16 determining the quantity of each electrical impulse to the valve.

The invention is exemplified in the following description and illustrated by way of example in the accompanying drawing, in which: 20

Fig. l diagrammatically illustrates one embodiment of our invention.

Fig. 2 diagrammatically illustrates a second embodiment of our invention.

Fig. 3 diagrammatically illustrates the application of the distributor to a multi-cylinder engine.

In the present application we disclose two preferred embodiments of our electrical fuel injection system' for internal combustion engines. These two systems are identical in principle and each are equally capable of producing ideal fuel injection characteristics which include '(1) constant time duration of injection valve opening 'at wide open throttle'position regardless of engine speed; and the use of a constant moderate fuel pressure. This, of course, results in a constant accurately metered charge of fuel being injected and full torque produced at all engine speeds. (2) Inherent self-governing at reduced 40 throttle-this is important as it enables the engine to be self-goveming without the use of governing auxiliaries on the engine. (3) Accurately timed full opening of the injection valve for a controlled exceedingly short time duration-this, of course, enables extremely high speeds to be reached in that a full charge of fuel can be injected in an exceedingly short period of time which will not exceed the maximum crank angle limits (even at extremely high speeds) during which fuel must be injected for proper operation of the engine. Likewise, it enables properly timed injection of fuel in high speed engines operating with comparatively low compression pressures wherein the ignition period must be limited to a crank angle comparable with that common to gasoline practice.

In both of our systems herein disclosed we prefer to employ a magnetic injection valve III which is fully described and claimed in Letters Patent 00 #l,892,956, issued to Harry E. Kennedy January 3, 1933.

In general, this magnetic valve, which is indicated by the numeral it in the drawing, consists of a housing constituting the stator. cably mounted in this housing is an armature which is connected with a valve member so that reciprocation of the armature will be accompanied by reciprocation of the valve member. This valve member controls the discharge of fuel through a nozzle orifice. The fuel is directed to the valve and the stator is so constructed that the fuel may pass therethrough to gain access to the nozzle when the valve member is unseated.

The magnetic operating structure of the valve Recipro- 06' I is such that it has direct force distance characteristics. That is to say, the maximum force exerted on the armature is at the commencement of its stroke, which force gradually diminishes as it reaches its maximum travel. In other words, the maximum force to lift the valve from its seat is exerted at the time injection is to commence, which, of course, results in a very rapid opening of the valve, and conversely permits equally rapid closing. The closing is effected through the provision of a spring force or its equivalent exerted against the valve and which is augmented by the fuel pressure as the valveapproaches its seat. It is to be noted that this valve operation results in sharp opening and sharp closing of the nozzle orifice, so necessary to proper engine operation.

The stator of the magnetic structure of the valve is wound so that it will be of relatively low inductance and consequently its circuit will have a small time constant This is necessary to effect fuel injection during an exceedingly short time duration. It is possible for us to utilize a magnetic valve of relatively low inductance because our valve operating circuits are capable of delivering current of high intensity to the valve during an extremely short time period, because our electrical fuel injection systems are characterized by the inclusion of a condenser in the valve circuit, the charge and discharge of which is engine controlled. The capacity of this condenser, of course, determines the maximum quantity of each electrical impulse delivered to the valve from the source of electromotive force provided to supply the necessary electrical energy.

In the injection system illustrated in Fig. 1, we have fitted an injection valve ID, of the type which we have previously described, to the combustion chamber A of an internal combustion engine B as illustrated. This valve is in constant communication with a source of liquid fuel which is maintained under a constant moderate pressure in a reservoir such as indicated at H. In a multi-cylinder engine this source of fuel supply is common to the injection valves of all of the cylinders. i

In the present instance we have preferred to illustrate that typeof engine which operates on comparatively low compression pressures and requires electrical ignition. For this purpose we have illustrated a spark plug Ila for the purpose of igniting the charge of the combustion chamber preferably by the method of ignition set out in United States Letters Patent #1303381, supra.

To provide electrical energy for operating the injection valve ill of our fuel injection system,

we have provided a source of electromotive force which in this instance is illustrated as a storage battery l8. We prefer that the voltage of this battery be twenty-four volts, although we are aware that other voltages are equally suitable.

In the injection system illustrated in Fig. 1, there are two circuits; a charging circuit for imposing a charge on a condenser and a dischargingcircuit for discharging the quantity of electricity stored in the condenser to the injection valve for operating the latter. That is to say,

in general, a circuit is completed through the condenser from the source of electromotive force to impose a charge thereon. This circuit is opened and the discharging circuit is closed to operate thevalve. It is essential that the discharging circuit be completed at a point in proper relation to the engine crankshaft rotation in order that the injection will commence at a defilever l9, the latter having a contact point 20 5 adapted to contact with a stationary contact point 2!. This latter contact point 2| is connected through a conductor 23 to a condenser 24 of the uni-directional type having a capacity of approximately 2000 micro-farads. The condenser is illustrated as being variable only because it may be desired to vary the condenser capacity for throttling purposes. In most instances, however, we prefer that the condenser capacity be fixed inasmuch as we provide a separate medium for varying the time constant of the condenser charging circuit for throttling purposes. In this instance we have shown a variable resistance 25 as interposed between the battery 18 and the contact lever IQ for varying the time constant of the 0 condenser charging circuit and by this we are enabled, as will be hereinafter described, to effect throttling.

Intermediate the battery It and the variable resistance 25 we interpcse an inductance 26 for 25 the purpose of creating current lag suflicient to enable the contact points and 2| to become firmly seated prior to the current reaching its maximum value. This prevents burning and rapid deterioration of the contact points.

We desire to point out, however, that we may substitute a variable inductance between the battery l8 and the contact lever IS in lieu of the variable resistance and the inductance 26. By means of such a variable inductance we are not only enabled to obtain a throttling efiect but are also enabled to obtain the current lag necessary to the proper seating of the points 20 and 2| prior to the current reaching its maximum value.

It should be pointed out here that it is well known that when a condenser is connected to a source of electromotive force, a momentary current flows until the condenser is charged to a potential equal to that of the source to which it has been connected. Therefore, when the points 20 and 2| contact, current from the battery it flows through the inductance 26, the variable resistance 25, between the contact points 20 and H and thence through the conductor 23 to charge the condenser 24.

The timing of the completion and opening of the circuits is such that subsequent to the condenser receiving its charge from the battery Hi, the discharging circuit through the valve is completed. By reference to the drawing, it will be noted that this discharging circuit includes a conductor led from the condenser 24 to a fixed contact point 21 which is adapted to contact with a contact point 28 on a contact lever 29. This lever in turn is electrically connected through a distributor contact lever 30 to the magnetic injection valve l0. Consequently, when the condenser discharge circuit is closed by contacting of the

points

21 and 28, the quantity of electricity stored in the condenser will be discharged through this discharge circuit through the valve in a time interval predicated upon the inductance and the capacity of the discharge circuit. It is necessary, however, that this circuit be closed at a definite angle of crankshaft rotation and be maintained closed a sufficient time duration to enable full discharging of the condenser to the valve.

It will be noticed that in order to operate the contact levers l9 and 29 in properly timed relation that we have provided a cam 22 which is engine operated and so formed and timed that the contact arms will be alternately operated and the contacts 21 and 2! closed at a definite angle of crankshaft rotation. We may prefer to advance and retard the beginning of fuel injection, when it is found necessary under certain operating conditions where the engine is to be operated through a wide speed range. This may beeasily accomplished and we have done so in practice by fitting an automatic governor to the cam 22 in the same manner that the automatic governor is fitted to the cam which operates the breaker arm in the ignition systems of conventional automotive design. In connection with the distributor contact arm 30, it'may be said that this is merely illustrated and described in this application in order to illustrate the application of our injection system to multiple cylinder engines as in Fig. 3. It maybe pointed out, however, that the points operated by the distributor arm 30 contact prior to the contacting of the

points

21 and 28 of the discharge circuit and such contact endures untilafter the opening of the contact points 21 and 28. This is in order that no current will be broken by the points of the distributor contact lever.

It should also be pointed out that the inductance of the winding of the magnetic structure of the valve Ill serves the same purpose in the discharging circuit in preventing sparking at the contact points 21. and 28 as does the fixed inductance 26 in thecharging circuit in preventing sparking" at the contact points 20 and.

It is obvious that in reality the condenser in the circuit functions as a current transformer because it is possible to draw a relatively small current during the comparatively long charging period that the charging circuit is closed, and then to subsequently discharge into the valve a current whose maximum value may exceed many times the charging current drawn from the battery.- This is important because at the instant of injection valve opening, a great force is necessary to rapidly overcome the inertia of moving parts and the unbalanced fuel oil pressure and thereby provide a sharp valve opening. Likewise, by the use of the condenser, the opening force falls rapidly to zero to obtain a sharp closing of 'the injection valve. 7

Such a condition is inherent in the circuit which we have just described because the instant that the discharging circuit closes, full condenser potential accelerates the current rapidly to its maximum value and consequently maximum force is developed in the magnetic operating structure of the valve nearly simultaneously with the closing of the circuit. The rapid lowering of potential across the condenser due to the depletion of its charge permits the current to die away quickly. A slight reversal may occur, due to the tendency of such a circuit to oscillate, which demagnetizes the valve and tends to prevent sticking of theparts thereof.

We have determined in practice by means of an oscillograph and a stroboscope that the first increment of fuel just emerges from the spray valve tip when the current reaches its crest value and that injection continues until the current has gone slightly negative and that we can inject a full charge of fuel through the injection valve illustrated in an injection period of of a second. As previously pointed out, it is exceedingly important that short injection duration be attained, particularly in engines in the higher speed range or in the lower compression engines in which ignition is effected by means 5 of electrical ignition, such as disclosed in United States Letters Patent #1,903,381, supra.

It maybe here emphasized that the duration of the contact time in the discharging circuit has nothing whatever to do with the time to discharge 10 the condenser through the valve circuit, but that the contact duration on the charging circuit does determine the quantity of electricity that will be stored on the plates of the condenser. This gives rise to engine characteristics which are desirable. This characteristic of our circuit enables the engine to become self-governing. That is to say, a reduction of engine speed due to increased load results in a greater quantity of electricity stored in the condenser and the subsego quent discharge into the injection valve will be correspondingly greater with an equivalent increase of fuel so that as the speed decreases, there is a continuous increase in the quantity of fuel injected per cycle until the maximum quantity 2; which the engine is capable of burning is injected.

It is also apparent that if the engine-speed increases due to a decrease in load that a lesser quantity of electricity will be stored in the con- 30 denser and that the subsequent discharge into the injection valve will be correspondingly lesser with an equivalent decrease of fuel so that as the speed increases, there will be a continuous decrease in the quantity'of fuel injected per cycle. 5

To throttle the engine, of course, the time constant of the condenser charging circuit is varied by means of the variable resistance 25. The throttling eifect of varying the time constant of the condenser charging circuit is, of course, ap- 4 parent.

There is another inherent advantageous characteristic of our iniection system. That is, when the throttle is at idling position, with the resistance of the condenser charging circuit at its maxi- 45 mum, and the engine is over driven, the magnitude of the electrical impulse delivered to the magnetic structure of the injection valve will be insufllcient to lift the valve and consequently no fuel will be injected into the combustion cham- 5o ber. The advantage of this is apparent, for example,'when the engine is used as a brake in a vehicle while descending grades, at which time the engine will, of course, be operating at a speed greater than idling but with the throttle set at 65 idling position. The duration of time which the condenser. charging circuit is closed will, therefore, be materially shortened so that the quantity of electricity discharged to the injection valve will be insufficient to lift the valve member 60 thereof from its seat. Therefore, the engine can be freely used as a brake without any likelihood of crank case dilution or loading up in the combustion chamber. I

In Fig. 2 we have illustrated a fuel injection as system for internal combustion engines which has all the advantageouscharacteristics of the system illustrated-in Fig. 1 and previously described .herein. The system is composed of the'same elements, the difference being in the electrical cir- 70 cults connecting these elements. Reference being had to Fig. 2, it will be seen that this system also: includes a magnetic injection valve 50 of the type previously described which is supplied with fuel oil under a constant pressure from a reservoir 5| hi ly is The electrical operating system for this valve 50 includes two circuits, which we prefer to term a charging circuit and a discharging circuit. That is to say, a circuit is completed through a condenser and the valve 58 in the charging circuit and then a discharging circuit is completed which fully or partially discharges the condenser as will be more fully described. It is essential, of course,

- that the charging circuit be completed at a point in proper relation to the engine crankshaft rotation in order that the. injection will commence at a definite point with relation to the engine crankshaft rotation.

What we have termed here the charging circuit includes a battery 52 which is electrically connected with a condenser 53 of the same type as used in the system illustrated in Fig. 1. This condenser is connected by means of a conductor 54 to a stationary contact point 55 which is adapted to contact with a contact point 58 on a contact lever 51. The contact lever 51 is electrically connected to the injection valve 50 through a distributor 58. This distributor 58 is illustrated and described in order to illustrate the application of our injection system to multiple cylinder engines. It should be pointed out here also that the contact points of the distributor 58 contact prior to the contacting of the points 55 and 5B and such contact endures until after the opening of the points 55 and 56 in order that no current will be broken by the points of the distributor contact arm 58.

It will, therefore, be seen that at the moment that the charging circuit is closed due to the contacting of the points 55 and 5B, the electromotive force "of the battery causes a momentary rush of current through the condenser 53 to the valve 50, operating the latter. This current, which during its existence operates the valve, is quickly brought to zero by the building up of a countervoltage in the condenser which opposes the electromotive force of the battery 52. Obviously, the electrical charge which the condenser 53 can receive determines the magnitude of the impulse delivered to the valve 58 and consequently determines the time duration of injection.

After the valve has been operated by what we term the charging circuit, the condenser 53 is discharged through the discharge circuit. For this purpose the condenser 53 is connected by a conductor 59 to a contact point which is adapted to contact with a point 6| on a contact lever 52, the latter being connected back to the-condenser through a variable resistance 63 and an inductance 64. When the contact points 80 and GI contact, the condenser 53 is, of course, discharged. The value of the resistance of the circuit and the time of duration of the contact between the points 60 and BI, of course, will determine the degree to which the condenser will have been discharged. Consequently, the degree to which the condenser has been discharged in turn determines the quantity of electricity re quired in the succeeding closing of the charging circuit to fully charge the condenser. It is this amount that determines the magnitude of the impulse delivered to the valve 58 so that by varying the time constant of the discharging through the medium of the variable resistance 83 we are enabled to effect throttling of the engine by changing the time duration of opening of the injection valve 58.

The inductance 54 is in the'discharging circuit, of course, to create a current lag to enable the contact points 65 and SI to become firmly seated circuit prior to the building up of the current to its maximum value.

It will be noticed that we employ a cam 85 which is engine operated to operate the contact levers 51 and 62 in properly timed relation. This 5 cam is so formed and timed that the contact arms will be alternately operated and the contacts 55 and 58 will be closed at a definite angle of crankshaft rotation. In practice, we have fitted this cam 65 with an automatic governor 10 to advance and retard the beginning of fuel injection but it is not believed necessary to illustrate this feature because the automatic governor operates the cam 65 to accomplish advance and retard in the same manner as the 15 automatic governor which is fitted. to the cam which operates the breaker arm in ignition systems of conventional design.

It will be seen that the difference in the injection system shown in Fig. 1 and that shown 20 in Fig. 2 is that in the system shown in Fig. 1 the operation of the injection valve is the result of a current flow which discharges the condenser, while in the system shown in Fig. 2 the operation of the fuel valve is the result of a current flow 25 which charges the condenser. The two systems, however, have the common feature that the condenser is always in the injection valve circuit and that the quantity of energy stored in the condenser in both systems is determined by 30 changing the time constant of a circuit in which the condenser is interposed. That is to say, in the fuel injection system shown in Fig. 1, the degree to which the condenser is charged is relied upon for throttling purposes, which regulation is attained by varying the time constant of the charging circuit of the condenser. In the system shown in Fig. 2, the degree to which the condenser is discharged is varied which is attained by varying the time constant of the dis- 0 charging circuit of the systemby means of a variable resistance included in the circuit.

As previously pointed out, however, both systems here disclosed produce the same advantageous engine operating characteristics and have the same inherent advantageous characteristics. That is to say, both systemsgwill operate emciently with the use of a constant moderate fuel pressure to inject, during a relatively short angle of the crankshaft rotation an accurately 5o metered quantity of fuel regardless of whether the fuel charges are minute and that injection will commence at an accurate given point relative to crankshaft rotation. Further, the time of duration of valve opening is exceedingly short. and accurate in order that a proper fuel charge can be injected in engines in the higher speed range and in low compression engines utilizing electrical ignition wherein the fuel charge must be injected during a relatively short angle of the crankshaft rotation.

While we have shown two preferred methods of practicing our invention, it is to be understood that various changes may be made therein by those skilled in the art without departing from the invention as defined in the appended claims.

Having thus described our invention, what we claim and desire to secure by Letters Patent is:

andclosingsaidcircmtsalternatelyandinsynchronism with the engine crankshaft operation.

2. A fuel injection system for internal combustion engines which includes a magnetic fuel injection valve, a source of electromotive force, a variable condenser, a charging circuit connecting the source of electromotive force with the condenser, a circuit connecting the condenser with the valve, engine operated means opening and closing said circuits alternately and in synchronism with the engine crankshaft operation.

3. A fuel injection system for internal combustion engines which includes a magnetic fuel injection valve of low inductance, a battery, a condenser, an electrical charging circuit electrically connecting the battery with the condenser, an electrical discharging circuit electrically connecting the condenser with said valve, means operated by the engine in timed relation with the engine crankshaft to alternately open and close said circuits whereby to charge the condenser from said battery and discharge the condenser to said valve to operate the latter.

4. Afuel injection system for internal combustion engines whichincludes a magnetic fuel injection valve, 8. source of electromotive force, a condenser, a charging circuit connecting the source of electromotive force with the condenser, a discharging circuit connecting the condenser with the valve, engine operated means opening and closing said circuits alternately and in synchronism with the engine crankshaft operation, and a variable resistance interposed in said charging circuit to vary the time constant thereof.

5. A fuel injection system for internal combustion engines which includes a magnetic fuel injection valve of low inductance, a battery, a condenser, an electrical charging circuit electrically connecting the battery with the condenser, an electrical discharging circuit electrically connecting the condenser with said valve, means operated by the engine in timed relation with the engine crankshaft to alternately open and close said circuits whereby to charge the condenser from said battery and discharge the condenser to said valve to operate the latter, and a variable resistance interposed in said charging circuit to vary the time constant thereof.

6. A fuel injection system for internal combustion engines which includes amagnetic fuel injection valve, a source of electromotive force, an operating circuit connecting the source of electromotive force with said valve for operating the latter, engine operated means for periodically closing said circuit, a condenser in said circuit to determine the quantity of the electrical impume'delivered from the source of electromotive force to the valve each time said circuit is closed, a discharge circuit associated with the condenser for discharging the same during the period said operating circuit is open, an engine operated means opening and closing said circuit.

7. A fuel injection system for internal combustion engines which includes a magnetically operated fuel iniection valve, a source of electromotive force. an electrical connection between said source of electromotive force and said valve for operating the latter, engine operated means for rendering said electrical connection between the electromotive force and the valve periodically effective, a condenser in said connection determiningthequantityoftheelectrical chargedeliveied from the source of electromotive force to the valve during each eil'ectiveperiod of said connection, and engine operated means effecting the discharge of the condenser during the ineifective periods of said connection.

8. A fuel injection system for internal combustion engines which includes a magnetic fuel injection valve, a source of electromotive force, an electrical connection between said source of electromotive force and said valve for operating the latter, engine operated means for rendering said electrical connection between the elec- 10 tromotive force and the valve periodically ef-, fective, a condenser in said connection determining the quantity of each electrical charge delivered from the source of electromotive force to the valve during each effective period of said con- 15 nection, a discharge circuit to eiIect the discharge of the condenser during the ineil'ective periods of said connection, engine operated means operating in timed relation to the engine to open and close said circuit, a variable resistance in said cirgo cult to vary the time constant thereof.

9. A fuel injection system for internal combustion engines which includes a magnetic fuel injection valve, a source of electromotive force. an operating circuit connecting the source of elecg5 tromotive force with said valve for operating the latter, engine operated means for periodically closing said circuit, a condenser in said circuit to determine the magnitude of the electrical impulse delivered from the source of electromotive so force to the valve each time said circuit is closed,

a discharge circuit associated with the condenser for discharging the same during the period said operating circuit is open, engine operated means operating in timed relation to the engine as for opening and closing said discharge circuit, and a variable resistance in said discharge circuit to vary the time constant thereof.

10. A fuel injection system for internal combustion engines which includes a magnetic fuel 40 injection valve, a source of electromotive force, an electrical connection between said source of electromotive force and said valve for operating the latter, engine operated means for rendering said electrical connection between the electromotive force and the valve periodically effective, a condenser in said connection to determine the magnitude of the electrical impulse delivered from the source of electromotive force to the valve during each effective period of said connection, a discharge circuit to effect the discharge of the condenser during the ineifective periods of said connection, engineoperated means operating in timed relation to the engine to open and close said discharge circuit, and an inductance in said discharge circuit.

11. A fuel injection system for internal combustion engines which includes a magnetic fuel injection valve, a source of electromotive force, an operating circuit connecting the source of electromotive force with said valve for operating the latter, engine operated means for periodically closing said circuit, a condenser in said circuit to determine the quantity of the electrical harge delivered from the source of clectromotive force to the valve each time said circuit is closed, a discharge circuit associated with the condenser for discharging the same during the period said operating circuit is open, engine operated means operating in timed relation to the m gine for closing the bustion engines which cal charge delivered bustion engines which includes a magnetic fuel injection valve, a source ofelectromotive force, an operating circuit connecting the source of electromotive force with said valve for operating the latter, engine operated means for periodically closing said circuit, a condenser in said circuit to determine the quantity of the electrical charge delivered from the source of electromotive force to the valve each time said circuit ,is closed, a discharge circuit associated with the condenser for discharging the same during the period said operating circuit is open, engine operated means operating in timed relation to the engine for opening and closing the discharge circuit, and an inductance in said discharge circuit.

' 3. A fuel injection system for internal combustion engines which includes a magnetic fuel injection valve, a source of electromotive force, an electrical connection between said source of electromotive force and said valve for operating the latter, engine operated means for rendering said electrical connection between the electromotive force and the valve periodically effective, a variable'condenser in said connection to determine the magnitude of the electrical impulse delivered from the source of electromotive force to the valve during each effective period of said connection, a discharge circuit efiecting the discharge of the condenser during the ineffective periods of said connection, and an engine operated means operating in timed relation to the endischarge circuit during the ineffective periods of said connection.

14. A fuel injection system for internal comincludes a magnetic fuel injection valve, a source of electromotive force, an operating circuit connecting the source of electromotive force with said valve for operating the latter, engine operated means for periodically closing said circuit, a variable condenser in said circuit to determine the quantity of the electrical charge delivered from the source of electromotive force to the valve each time said circuit is closed, a discharge circuit associated with the condenser for discharging the same during the period said operating circuit is open, engine operated means for opening and closing the discharge circuit, and an inductance in said discharge circuit.

15. A fuel injection system for internal com bustion engines which includes a magnetic fuel injection valve, a source of electromotive force, an operating circuitconnecting the source of electromotive force with said valve for operating the latter, engine operated means for periodically closing said circuit, a variable condenser in said circuit to determine the quantity of the electrifrom the source of electromotive force to the valve each time said circuit is closed, a discharge circuit associated with the condenser for discharging the same during the period said operating circuit is open, engine operated means for closing the discharge circuit, and a variable resistance in said discharge circuit.

16. A fuel injection system for internal combustion engines which includes a source of liquid fuel under a constant pressure, a source of electromotive force, a condenser, a charging circuit connecting the source of electromotive force with the condenser, a discharging circuit connecting the condenser with the valve, engine operated means opening and closing said circuits alternately, said means closing the discharging circuit injection valve in constant engine operated means at an exact point relative to the engine crankshaft rotation.

1'7. A fuel injection system for internal combustion engines which includes a source of liquid fuel under a constant pressure, a magnetic fuel communication with said source of fuel, a source of electromotive force, an electrical vconnection between said source of electromotive force and said valve for operating the latter, engine operated means for rendering said electrical connection between the electro: motive force and the valve periodically effective, a condenser in said electrical connection determining the magnitude of the electrical impulse delivered from the source of electromotive force to the valve during each effective period of said connection, and engine operated means effecting the discharge of the condenser during the ineffective periods of said connection.

18. A fuel injection system for internal combustion engines which includes a source of electromotive force, a condenser, an electromagnetic fuel injection valve, two electrical circuits each associated with said condenser, the electromotive force being connected to one of said circuits, the valve being connected to one of said circuits, for opening and closing said circuits to cause a current to periodically flow in said circuits alternately and in synchronism with the engine operation to alternately charge and discharge said condenser, the current flow from the condenser in one of said circuits being utilized to operate said valve.

19. A fuel injection system for internal combustion engines which includes a source of electromotive force, a condenser, an electromagnetic fuel injection valve, ciated with said condenser, the electromotive force forming a part of one of said circuits, the valve forming a part of one of said circuits, said circuits being so arranged that when said circuits are alternately rendered effective a current origi nating in the electromotive force will flow through one circuit and charge the condenser and then flow through the other circuit to discharge the condenser, the electromotive force, the condenser and valve being so associated with said circuits that the flow of the current from the condenser for alternately rendering said circuits effective in synchronism with the operation of the crankshaft of the engine.

20. A fuel injection system for internal combustion engines which includes a source of electromotive force, a condenser, an electromagnetic fuel injection valve, two electrical circuits of which said condenser forms a part, the electromotive force forming a part of one circuit, the valve forming a part of one circuit, said circuits being so arranged that when said circuits are alternately rendered effective a current originating in the electromotive force will flow through one circuit and charge the condenser and then flow through the other circuit to discharge the condenser, the electromotive force, the condenser and valve being so associated with said circuits that the flow of the current from the condenser in one of said circuits will flow through the valve to operate the same, a medium in one of said circuits for varying the resistance thereof to vary the magnitude of the displacement current flowing through said valve, and engine operated switch means for alternately rendering said circuits effective, said means operating in syn-.

two electrical circuits asso.--

- bustion engines which includes chronism with the operation of the crankshaft o! the engine.

21. A fuel injection system for internal combustion engines which includes a source of electromotive force, a condenser, an electromagnetic fuel injection .valve, a charging circuit and a discharging circuit electrically associated with said condenser, the electromotive force being associated with said charging circuit, said condenser and electromotive force being so associated with said circuits that a current originating in the electromotive: force will flow in the charging circuit to charge the condenser when the charging circuit is rendered effective, the condenser being so associated with the discharging circuit that when the latter is efiective it will discharge the condenser, the said valve being so disposed in one of said circuits that the displacement current flow in said circuit from the condenser will energize the electromagnetic valve and operate the same, and engineoperated switch means in said circuits for alternately rendering said circuits eilective and ineilective in timed relation and in synchronism with the engine operation.

22. A fuel injection system for internal combustion engines which includes a source of elec-.- tromotive force, a condenser, an electromagnetic fuel injection valve, a charging circuit and a discharging circuit electrically associated with said condenser, the electromotive force and condenser being associated with the charging circuit whereby when the charging circuit is rendered effec tive a current originating in the electromotive force will flow in the charging circuit to charge the condenser, the condenser being so associated with the discharging circuit that when the discharging circuit is rendered eifective it will discharge the condenser, the valve being disposed in one of said circuits so that the current flow in said circuit from the condenser will energize the electromagnetic valve and operate the same, means for varying the resistance of one of said circuits whereby to yary the magnitude of the current flow to the valve, and engine operated means in said circuits for alternately rendering the same effective and inefifective in timed relation and in synchronism with the engine operation.

23. A fuel injection system for internal combustion engines which includes a source of electromotive force, a condenser, an electromagnetic fuel injection valve, a charging circuit and a discharging circuit electrically associated with said condenser, the electromotive force forming a part of the charging circuit so that when the charging circuit is rendered effective a current originating in the electromotive force will iiow in the charging circuit to charge the condenser, the condenser being so associated with the discharging circuit that when the latter is rendered eifective it will discharge the condenser, the valve being so disposed in one of said circuits that the current flow in said circuit from the condenser will energize the electromagnetic valve and operate the same, means for varying the resistance of the circuit other than the last-mentioned circuit to vary the magnitude of the current to the valve, and engine operated means in said circuits for alternately rendering the same eilective and ineffective in alternate relation and in synchronism with the engine operation.

24. A fuel injection system for internal coma normally open charging circuit and a normally open discharging circuit. a battery, a condenser, said battery and condenser being included in the charging circuit,

I the condenser being included in the discharging circuit, engine operated means for alternately rendering said circuits effective and in synchronism with the engine operation whereby the cur- 5 charging circuit and a normally open discharging circuit, a battery, a variable condenser, said bat tery and condenser being included in the charging circuit, the condenser being included in the discharging circuit, engine operated means for alternately rendering said circuits effective and 20 in synchronism with engine operation whereby the current flow in the charging circuit will charge the condenser and the current flow in the discharging circuit will discharge the condenser, an electromagnetic fuel injection valve included in 25 one of said circuits in a manner whereby current flow in said circuit from the condenser will operate the valve.

26. A fuel injection system for internal combustion engines which includes a normally open 30 charging circuit and a normally open discharging circuit, a battery, a condenser, said battery and condenser being included in the charging circuit, the condenser being included in the discharging circuit, engine operated means for alternately 35 rendering said circuits eiiective and in synchronism with the engine operation whereby the current flow in the charging circuit will charge the condenser and the current flow in the discharging circuit will discharge the condenser, an electro- 40 magnetic fuel injection valve included in one of said circuits in a manner whereby current flow in. said circuit from the condenser will operate the valve, and means for varying the resistance of the circuit other than the one in which the valve 5 is included to vary the magnitude of the current flow to the valve.

27. A fuel injection system for internal combustion engines which includes a source of electromotive force, a condenser, an electromagnetic 0 fuel injection valve, a charging circuit including said source of electromotive force and said condenser, a discharging circuit including the condenser, engine operated means for opening and closing said circuits alternately and in synchronism with the engine operation to cause a current to periodically and alternately flow in said circuits in synchronism with the engine operation and thereby alternately charge and discharge said condenser, the said electromagnetic valve be- 60 ing included in one of said circuits and so disposed therein that the current flow from the condenser in said circuit will actuate said valve, and an electrical medium associated with the other circuit to vary the magnitude of the displacement 05 current flo""ng to the valve.

28. A Iuel injection system for internal combustion engines which includes a source of electromotive force, a condenser, an electromagnetic fuel injection valve, a normally open charging cir- 70 cuit, a normally open discharging circuit, the said charging circuit including the electromotive force and the valve, a condenser in said circuit between the electromotive force and the valve whereby the condenser will limit the magnitude of the current 75 flow to the valve when said circuit is rendered eflective, the discharging circuit including the condenser for discharging the same when said circuit is rendered effective, and engine operated 5 means for alternately rendering said circuits eijective in timed relation and in synchronism with the engine operation.

29; A fuel injection system for internal combustion engines which includes a source of electromotive force, a condenser, an electromagnetic fuel injection valve, a normally open charging circuit, a normally open discharging circuit, the said charging circuit including the electromotive cluding the condenser for discharging the same when said circuit is rendered effective, engine operated means for alternately rendering said circuits effective in timed relation and in synchronism with the engine operation, and a variable 10 resistance in said discharging circuit.

: BROOKS WALKER.

HARRY E. KENNEDY.