US2078286A - Fuel injection system for internal combustion engines - Google Patents

Description

April 27, 1937. J. SEAGREN 2,078,286

FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Nov. 2, 1935 IN VEN TOR.

A TTORNEY Patented Apr. 27, 1937 Y 1 I 2,078,286

. UNITED STATES PATENT OFFICE FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES John Seagren, Alameda, Calif., assignor to Atlas Imperial- Diesel Engine Company, Oakland, Calif., a corporation of Delaware Application November 2, 1935, Serial No. 47,953

4 Claims. (01.123439) This application is a continuation in part Of amount of fuel is injected under identical fuel my prior application entitled, Fuel injection syspressure conditions to all of the cylinders, which tem, Ser. No. 681,109, filed July 19, 1933. will result in smooth engine operation. The in- This invention relates to internal combustion .jection system is applicable to engines-with any 5 motors of the compression ignition type, and parnumber of cylinders, with any crank arrangement 5 ticularly pertains to a fuel injection system for and regardless of whether or not the engine opersuch motors. ates on the two or four cycle principle.

It is the principal object of my present inven One form which the invention may assume is tion to provide animproved fuel injection sysexemplified in the following description and illustem' for internal combustion engines which overtrated by way of example in the accompanying 10 comes the disadvantages of prior systems by efdrawing, in which:

fecting uniform injection to all cylinders The figure is a schematic view of my improved throughout a wide range of engine speeds withfuel injection system. a out any throttling effect and with a sharp begin- Referring more particularly to the accompanyning and cut-off of injection, and in which ing drawing, I have there schematically illus- 15 system the beginning and termination of injectrated my fuel injection system for solid or airtlon may be independently varied, either manless injection type internal combustion engines. ually or by means of an engine driven governor. My system in some respects resembles the com- In practicing my invention, I provide a fuel mon rail type system in that fuel at injection injection system of the common rail type and pressure is maintained in a reservoir or accumu- 20 which is embodied in an apparatus which inlator and the injection charge is measured by the, cludes a .fuel'accumulator. in which fuel under a interval of time during which the accumulator is substantially constant injection pressure is mainin communication with the injection orifice. This tained. The apparatus also includes an engine interval of time is controlled as to duration, as

driven distributor which functions to .place the to time of commencement and as to time of ter- 25 accumulator in communication with the cylinders mination with relation to the engine crankshaft of the engine in their firing order. In the conoperation. nection between the accumulator and the dis- The fuel is stored in a main tank l0 and pumped, tributor I provide a pair of piston type valves from there to a day tank II by means of any engine operated at high speed and in synchronism suitable type of pump l2. From the day tank 3 with the distributor and crankshaft operation. II, the fuel is conducted through a pipe line H.

These valves are actuated by engine driven echaving a filter I 5 therein, to the intake port l6 centrics and are so driven that the opening and of a pump chamber H. The intake port I6 is closing of the communication between the accontrolled by an intake valve IBas in the usual Cl. mulator and the distributor take place at submanner. The pump chamber I! has a discharge st: ntially midway of only one stroke of the valves port l9 connected by a conduit 20 to an accumuwhere their velocity is atamaximum. The valves lator 2|. The exhaust port I9 is fitted with a are so relatively timed that fuel is admitted to discharge valve 22 of any preferred design.

the distributor onlyduring one of the two strokes, The pump chamber I1 is formed in a primary and one of the valves always prevents communivalve housing 23. This valve housing 23 is formed cation between the accumulator and the distribuwith a primary piston valve bore 24, in which a tor when the other 'is open on the'opposite stroke. piston type primary valve 25 is reciprocably Due to the fact that these valves operate at high mounted. The piston valve bore 24 communispeed, all throttling of the fuel is eliminated, cates with the pump chamber I! so that as the which is necessary for efficient engine operation. primary valve 25 reciprocates, it creates a pump The time of commencement of injection, the time lng action drawing fuel into the pump chamber of duration of injection and the timeof termina- I! through the intake port IS on one stroke, and

tion of injection is solely determined by the two discharges the fuel in the pump chamber ll under valves mentioned and is in no way regulated by high pressure through the'discharge port to the the distributor. Consequently, exactly the same accumulator on its opposite stroke. It should be same at the time of commencement of every in--v jection.

The accumulator 2| is fitted with an adjustable regulating valve 28 which determines the pressure of the fuel in the accumulator. This pressure is intended to be the injection pressure and at present I prefer that the injection pressure be approximately 3500 pounds. The accumulator is of sumcient size so that the pressure drop after each injection will be unappreciable. However, any pressure drop will be taken. care of prior to each injection by the pump action as previously described.

The primary valve housing 23 is provided with a primary intake port 21 which is connected by means of a conduit 28 to the accumulator 2|. The primary valve intake port 21 communicates with the piston valve bore' 24 so that fuel at the injection pressure will be led to this bore through the conduit 28 from the accumulator.

The primary valve housing 23 is provided with a primary discharge port 29 likewise in communication with the piston bore 24. This port 28 is connected to a secondary intake port 30 formed in a secondary valve housing 3|. This valve housing is formed with a secondary piston bore 32 in which a piston type secondary valve 33 is reciprocably mounted.

The secondary valve housing 3| is provided with a secondary discharge port 35 in communication with the secondary pistori bore 32, which 'port 35 is connected by a conduit 36 to a distributor intake port 31 formed in a stationary distributor head 38.

The distributor head 38 is formed with a central bore 39 in which a distributor 'member 40 is rotatably mounted. The distributor member 4|! is formed with an internal distributing chamber 4| which is in constant communication 'with the port 31 through a port 42. The chamber 4| in the distributor 'member40 is formed with a single discharge port 43 which is adapted to successively communicate with distributor discharge ports 44 formed in the distributor head 38. One of these ports 44 is provided for each engine cylinder and is connected to the injection nozzle thereof. The number of the ports 44 depends upon the'number of cylinders of the engine and the port 43 registers with the ports 44 leading to the cylinders 'in their regular, firing order.

The distributor member 40 is driven from a shaft 45 through a set of gears 46. The shaft 45 is driven from the engine so that the distributor 40 will operate in synchronism with the crankshaft of the engine so that the port 43 will communicate successively with the cylinders in their proper firing order and at the proper time with relation to the piston operation therein. a It should be stated here that the port 43 registers with the proper port 44 just prior to injection and becomes out of register therewith subsequent to injection. The purpose of this is so that the distributor in no manner determines thequantity or time of injection. By time is meant the time of commencement of injection and the time of termination of injection.

I intend that theprimary 'valve' 25 and the secondary valve 33 operate to determine the time of commencement of injection and the time of termination of injection, which, of course, controls the time of duration of injection. I accomplish this by forming the primary valve 25 with a piston amazes port 41 which is in the form of an annular recess formed in the periphery of theprimary valve 25. When this port is in register with the primary intake port' 21 and the primary exhaust port 29, fuel under injection pressure from the accumulator 2| may discharge to the secondary intake port 30. The secondary valve 33 is formed with a similar piston port 48 which when in register with the secondary intake port 30 and the secondary exhaust port'35, will enablethe fuel from the accumulator to discharge directly to the distributor intake port 31 through the distributor member 40 through the selected distributor discharge port 44 to the injection nozzle of the proper cylinder.

I desire to point out that the primary valv 25 controls the time of commencement of injection, while the secondary valve 33 controls the time of termination of injection. That is to say, that at the proper time for injection in a particular cylinder, the port 43 of the distributor member 40 registers with the proper port 44. The piston port 48 of the secondary valve 33 then comes into register with both of the secondary ports 30 and 35 before the piston port 41 of the primary valve 25 comes into register with the primary intake port 21. However, the piston port 41 of the primary valve 25 registers with the primary exhaust port 29 before it commences registering with the primary intake port 21. As soon as it registers with the latter, injection commences.

To terminate injection, the port 48 in the secondary valve 33 passes out of register with the. secondary intake port 30, consequently cutting oif injection. During the time that the port 48goes out of registration with the port 30, the piston port 41 in the primary valve' 25 is still in register with the primary ports 21 and 29. So, therefore, it is obvious that the relative positions of the piston ports 41 and 48 of the primary valve 25 and the secondary valve 33 are such that the primary valve 25 determines the time of commencement of injection and the secondary valve 33 determines the time of termination of injection.

These valves arev driven in synchronism with relation to each other and with relation to the crankshaft operation so that injec tion will commence at the proper crank angle and will terminate at the proper crank angle. The interval of time between the commencement and termination of injection, of course, determines the quantity of injection at a given injection pressure. By raising the pressure, a greater quantity will be injected, and conversely, lowering the pressure will cut down the amountinjec'ted.

The operating mechanism for the valves consists of an eccentric shaft 50- driven from the crankshaft of the engine and in timed relation thereto. Mounted on this shaft 50 are two eccentrics 5| and 52. The eccentric 5| is connected by a connecting rod 53 'to a reciprocable plunger 54 which in turn is operatively associated with the primary valve 25 to'operate thesame. The

eccentric 52 is connected by means of a connecting rod 55 to a reciprocable plunger 55 which in turn is operatively connected to one end of a centrally pivoted lever 51. The other end of this centrally pivoted lever 51 is connected to the secondary valve member 33 so that reciprocation of the plunger 58 will be accompanied by reciprocation of the secondary valve 33; The lever 51 is pivoted on an eccentric 58 fixed on a shaft 59 so that by turning the shaft 59, the relative poaovaaae a operation will be varied. The shaft 59 is connected to an engine driven governor 50 as illustrated so that the time of terminationof injection will be engine controlled. I may point out, however, that the time of termination may be manuu ally controlled if so desired.

To regulate the operation of the primary valve 25 and thus change the time of commencement of injection with respect to the crankshaft operation, I provide a mechanism indicated at 6| which constitutes a manually operated lever 62, a pair of bevel gears 63, which drivesn spur gear 64. This spur gear is in mesh with a spur gear 65 which forms a part of the plunger 54. By turning this spur gear, the threaded connection 0 66 either shortens the plunger or lengthens it,

and consequently changes the position of the piston valve port 41 with relation to the primary intake and discharge ports 21 and 29. This change in position of the piston port in respect the time of commencement of injection relative to the crankshaft operation.

I want to call particular attention to the fact that injection occurs only on one stroke of the two stroke cycle of the primary and secondary valves. In this instance I have shown injection occurring on the down stroke of these valves. I also call attention to the fact that the valvular action of the primary and secondary valves occurs approximately at the center of their down stroke, at which time they are travelling at their highest velocity, due to the position of the eccentrics and 52. This can be readily appreciated from the drawing. The eccentrics .revolve J in the direction of the arrows in the drawing and although they appear on the drawing to be revolving in opposite directions, they are really fixed on one shaft and it is merely the schematic arrangement of the drawing which gives this 9 false impression.

The'eccentric shaft 50 is, of course, driven from the crankshaft of the engine so that the valves will operate in synchronism with relation to each other and in timed relation to the crankshaft and piston operation. By regulating the primary valve, injection can be made to commence at any preferred crank angle, and'likewise by regulating the secondary valve, termination of injection can be made to occur at any crank, angle. By automatically; adjusting the position of the secondary valve through the means of the engine governor, the time of termination of injection will be engine controlled.

It is seen that with a single cylinder engine, the eccentric shaft 50 will operate at one-half crankshaft speed. In a two cylinder motor, the eccentric shaft will operate at crankshaft speed, and in a four cylinder motor, the eccentric shaft will operate at twice crankshaft speed. This is very important in that it moves the primary valve '25 and the secondary valve 33 at comparatively high linear velocity so that the ports are rapidly uncovered-and covered, so that throttling of the fuel will be negligible. This is important as throttling is extremely detrimental to efficient engine operation.

In operation of my fuel injection system, when the engine commences to operate, the piston primary valve will draw fuel from the day tank I II and pump the fuel under high pressure into to the intake and discharge ports will change the accumulator 2|. By adjusting the regulating valve 26,.the injection pressure may be determined. Fuel at injection pressure from the accumulator will be present at the bore 24. The port 43 of the distributor member 40 will register with the proper port 44 in the distributor head 38 which is connected with the injection nozzle of the selected cylinder. ondary valve '33 then moves downwardly to place its port 43 into communication with both of the secondary ports and 35, which places the distributor intake port 3'! into communication with the primary discharge port 29. The piston port 41 of the primary valve 25 has already commenced registering with the discharge port 29 and then commences registering with the primary intake port 21, placing the accumulator 2| into communication with the distributor and through the latter to the selected cylinder, effecting an injection. The time of termination of the injection occurs by the piston port 48 of the secondary valve 33 passing out of register with the secondary intake port 30. t

I also intend to relieve the line between the injection nozzle at the cylinder and the secondary valve 33, and I accomplish this by providing the secondary valve housing 3| with a relief port 3la which communicates with the main storage tank l0 through a pipe line 3Ib. After the piston port 48 of the secondary valve 33 passes out of register with the secondary intake port 30, but before it passes out of register with the secondary discharge port 35, it registers with the relief port 3Ia, relieving the line between the nozzle and the secondary valve. This is advantageous in that it aids in effecting a sharp cut-off of injection and prevents dribbling of fuel into the cylinder.

vAs previously described, the port 43 becomes in register with the selected port 44 prior to the commencement of injection and goes out of register with the port 44 subsequent to the termina- The section of injection. Therefore, there is no throttling action here and likewise the distributor in no way affects either the quantity or duration of injection.

On the upstroke of the primary valve 25, it, of course, pumps fuel to the accumulator to maintain the pressure therein. The injection pressure, of course, can be regulated by the regulator 26 so thatthe injection pressure in the accumulator will remain substantially constant at any given setting, and will not be a function of engine speed. On the upstroke of thevalves 25 and 33, one of the two valves is always in a position cutting off communication between the accumulator and the distributor. The latter offers a second seal against leakage. It is obvious that due to this double seal during non-injection periods, the chances of fuel leaking'from the accumulator to the injection nozzle at the cylinder are slight, and consequently the fit of these parts in their bores need not be made as accurately as it is necessary to fit the parts in a jerk pump system. Likewise, my system will be less sensitive to wear.

It is also obvious that since the fuel passes through exactly the same elements on its way from the accumulator to the outlet of the distrib- 'utor for each and every injection,'it does not matter if these various elements leak slightly, since any leakage will affect all injections in all cylinders to the same degree. g

It is obvious that there will be no appreciable throttling of the fuel due to the fact that the valves 25 and 33 operate at high velocity, so that they rapidly uncover and cover the ports. This is of great importance, particularly with respect to eflicient operation of the engine.

I also call attention to the fact that the volume of fuel between the valves and the injection nozzles of the cylinders will be small, and consequently the effects of inaccuracy due to the compressibility of the fuel will be negligible.

From the foregoing it is obvious that I have provided a very efiicient fuel injection system in which exactly the same amount of fuel will be injected in all of the cylinders under identical fuel pressure conditions, and in which the time of commencement of injection and the time of termination of injection may be independently varied.

While I have shown the preferred form of my invention, itis to be understood that various changes in its construction maybe made by those skilled in the art without departing from 7 internal combustion engines, an accumulator containing fuel under a predetermined injection pressure, an engine driven fuel distributor adapted to communicate with each cylinder of the engine in its proper firing order and in proper timed-relation to the crankshaft operation, a fuel conducting connection between said distributor and said accumulator, a primary'valve-and a secondary valve interposed in said connection to control the passage of fuel from the accumulator to the distributor, sai primary valve operating'to open said connection and said secondary valve operating to close said connection, said secondary valve unobstructing the said fuel conducting connection at the time the primary valve operates to open it, and said primary valve unobstructing the said connection at the time said secondary valve operates to close said connection, said valves being engine operated in synchronism and in timed relation to the crankshaft operation, said distributor communicating with the proper cylinder prior to the opening of said connection and cutting off said communication subsequent to the closing of said connection.

2. ,In 'a fuel injection system for multi-cylinder internal combustion engines, an accumulator to contain fuel under a predetermined injection pressure, a fuel supply tank, engine driven pump means drawing fuelfrom said tank and pumping it. to said accumulator to maintain the fuel pressure therein substantially constant, an engine driven rotary fuel distributor adapted to sepaducting connection between said distributor and said accumulator, a primary valve and a secondary valve interposed in said connection to control the passage of fuel from said accumulator to said distributor, said primary valve-operating tion ineffective, said secondary valve unobstructing the flow of fuel through said connection at the time said primary valve operates to render gsaid connection effective, said primary valve un- .ob'structing the fiow of fuel through said connec at the time said secondary valve operates to render said-connection ineffective, said valves be--. ing engine driven in synchronism and in timed relation to the crankshaft and distributonoperation, said distributor communicating with the with just' subsequent to injection, andseparate means for regulating both of said valves whereby the time of commencement of injection and the time of termination of injection with relation to the crankshaft operation may be independently varied.

3. In a fuel injection system for multi-cylinder internal combustion engines, an accumulator containing fuel under a predetermined injection pressure, said accumulator being of sufllcient capacity to maintain said predetermined injection pressure substantially constant, adjustable means for predetermining said injection pressure, pump means associated with said accumulator for maintaining the pressure therein, an engine driven fuel distributor adapted to separately communicate with the cylinders of the engine in their proper firing order and in timed relation to the crankshaft operation, said communication cumulator, a primary and a secondary valve interposed in said connection to control the passage of fuel from the accumulator to the distributor, said primary valve ,operating to render-said connection effective and thereby determine the time of commencement of injection, said secondary valve operating to render said connection ineffective and thereby determine the time of termination of injection, said secondary valve unobstructing fuel flow through said connection at the time said primary valve operates to commence injection, said primary valve unobstructing fuel flow through said connection at the time said secondary, valve operates to'terminate injection, said valves being of the reciprocable piston type and operating at high velocity to effect sharp commencement and cut-off of injection and thereby prevent throttling, said valves being tain said predetermined injection pressure substantially constant, adjustable means for predetermining said injection pressure, pump means associated with said accumulator for maintaining the pressure therein, an engine driven fuel distributor adapted to separately communicate with the cylinders of 'the engine in their proper firing order and in timed relation to the crankshaft operation, a fuel conducting connection be- .tween said-distributor and said accumulator, a

primary and a secondary valve, interposed in said connection to control the passage of fuel.

from the accumulator to the distributor, said primary valve operating to render said connection effective and thereby'determine the time of commencement of injection, said secondary valve operating to render said connection ineffective and therebydetermine the time of termination of injection, said secondary valve unobstructing injection at the time said primary valve operates to commence injection, said primary valve unobstructing said connection at the time said sec-,

ondary valve operates to terminate injection, said valves being of the piston type and operating at high velocity to prevent throttling, said valves being engine driven in synchronism and in timed relation to the crankshaft and distributor operation, said distributor communicating with the selected cylinder prior to the rendering of said connection effective and ceasing communication with said cylinder subsequent to the time said connection is rendered inefiective, and means for adjusting said secondary valve whereby the time of termination of injection may be varied with relation to the crankshaft operation.

JOHN SEAGREN.

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