US1147806A - Injection of liquid fuel in internal-combustion engines. - Google Patents

Description

I. McKECHNIE.

INJECTION 0F LIQUID FUEL IN INTERNAL COIVIBUSTION ENGINES.

APPLICATION FILED AUG.5. 1913.

1,147,806. Patented July 27, 1915.

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L J 0 r1 5 J. McKECHNIE.

INJECTION 0F LIQUID FUEL IN INTERNAL COMBUSTION ENGINES.

' APPLICATION FILED was. 1913.-

1,147,806. Patented July 27, 1915.

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JAMES MCKEGHNIE, 0F BARROW-IN-FURNESS, ENGLAND, ASSIGNOR TO VICKERS LIMITED, OF BARROW- IN-FURNESS, ENGLAND.

INJECTION 0F LIQUID FUEL IN INTERNAL-COMBUSTION ENGINES.

Application filed August 5, 1913.

tion.

This invention relates to the injection of liquid fuel at very high pressures into the cylinders of internal combustion engines (of the type in which the fuel is ignited as it enters the cylinder) by means of a resilient pressure accumulator and an injector valve, the chief object of the invention being to insure the injection of such fuel, unmixed with air, at a pressure which is the same for varying fuel supply and engine power, so

that a greater range of power and increased economy at low powers may be obtained.

According to my present invention a practically constant maximum injection pressure in the resilient accumulator is obtained by pumping in a quantity of liquid always somewhat in excess arranging for excess liquid to be returned to the suction side of the pump, or to a fuel reservoir, through a relief valve set at a predetermined pressure which gives the constant maximum desired. The injection valve, which I prefer to include in one casing with the pump and accumulator but which may be at the engine cylinder, serves to control the quantity of fuel injected, the period and extent of opening being adjusted according to the power to be developed in the engine. The period of opening must, of course, be very short, as the time occupied in injecting even a full charge of fuel under the very hlgh resilient pressure attained in the accumulator is extremely small.

The adjustment of the valve opening may be effected by any suitable means. A simple arrangement consists in providing'an axially adjustable cam having a tapering cam surface shaped so as simultaneously to time the opening and vary the period and extent of opening according to the power required. The cam may act through a valve lever opposing a valve closing spring. Another convenient method of adjustment is by means of a moving of a jointed cam lever, the opening of the Specification of Letters Patent.

of the fuel charge and and its head 6 fulcrum acting on' one member Patented July 27, 1915.. Serial No. 783,053.

valve varying according to the position of the fulcrum. By arranging the moving fulcrum on an eccentric or on a swinging arm or equivalent adjustable support the cam roller may be, simultaneously with the adjustment of leverage, advanced or retracted with regard to the cam, so as to time the valve opening according to the fuel supply.

In order that the said invention may be clearly understood and readily carried into effect the same will be described more fully with reference to the accompanying drawings in which Figure l is a section of pump and valve apparatus embodying my invention. Fig. 2 is a detail view of a slight modification of the injection valve. Fig. 3 is a diagram illustrating the application of the invention to a multi-cylinder engine, and Figs. 4, 5 and 6 illustrate three modifications of the moving fulcrum device for varying the opening of the injection valve.

A is the pump body or casing, which in the construction illustrated in Fig. 1 carries all the valves required for the present method of injection.

B is the pump plunger.

C is the pump suction valve operated by the cam c on the cam shaft D.

E is the relief valve.

F is the injection "alve controlled by the sliding cam f on the shaft D.

is a sprin accumulator of pressure tube type in which the walls expand to receive the fuel under pressure and contract to force the fuel into the engine cylinder.

H is a nozzle in the cylinder cover J, through which nozzle the oil is injected into the cylinder.

K is a pressure gage on the small bore pipe 7?. connecting the nozzle H to the pump casing.

The pump plunger B is driven by the cocentric b on the shaft D, the diameter of the plunger and its stroke being so proportioned that the volume swept out by the plunger 1s in excess of the maximum amount of fuel required for each stroke. The plunger extends through the gland b' in the casing A slides in an extension a of the casing and forms a ball and socket joint with the end of a short rod 6 on the eccentric 5. During the suction stroke of the plunger B the fuel is drawn into the passage a of the pump casing from the fuel chamber L, which is kept supplied with fuel through the pipe 1, the suction valve G being opened against the pressure of the spring 0. Above the short stem of the suction valve is avalve operating rod a passing through the gland c and provided with a head adjustably connected at 0*, sliding in an extension a of the pump casing and having a spring 0 bearing on its under side. The cam 0 acts on the rod 0 against the spring 0 through the roller 0 on the head 0. The cam therefore may maintain the suction valve-C open after the suction stroke has ended and the compression begun.

The cam c is so formed as to allow the valve C to close gradually during the compression stroke, so that the fuel pressure in the passage a due to the compression stroke of the plunger B gradually increases and reaches its maximum only at or after the complete closing of the suction valve. During this gradually increasing pressure the accumulator tube G expands to receive its charge of fuel, the walls yielding to an extent corresponding to the pressure attained in the passage a. This gradual closing of the suction valve is not an essential feature, as the resilient action of the accumulator G prevents any sudden shock due to reversal of the pump plunger.

The maximum pressure pump is determined by the relief valve E on which strength of which spring can be regulated by screwing the separate valve head e in or out of the plug a secured in the valve body A, this plug having a relief opening e in its side through which excess fuel can esca e to a reservoir or back to the chamber The spring 6 is set so as to give the maxiv mum pressure desired at the beginning of the injection, this pressure being attained before the plunger B reaches the end of its stroke. The remainder of the stroke, usually only a small portion, drives any excess fuel through the relief valve.

The injection valve F is shown in Fig. 1 fitted to the pump body, but it may of course be situated in any convenient position between the pump and the nozzle H. The cam f opens this valve at the required point of the engine stroke through an arm f on a bracket (1, this arm bearing on a collar f on the valve stem f the upper end of which is acted upon by the spring f placed in a cup at the end of a bracket 45, the spring f closing thevalve when released by the arm f. The timing cam f is arranged to slide upon the cam shaft D, a groove f 'receiving the cam adjusting means. The cam surface varies from one end of the cam to the other so that the points of opening and closing of the valve F can be regulated in accordance with the running of the engine and the power to. be developed. The opening of the developed by the bears the powerful spring e, thethe fulcrum of the lever f,

valve F always occurs after the closing of the pump suction valve and when the maximum fuel pressure has been attained, so that immediately the valve F is'opened the accumulator tube G contracts and forces the fuel under the extremely high maximum pressure through the small bore pipe 71. and the cylinder nozzle H, the fuel entering the cylinder as a fine spray which intsantly'vaporizes. To avoid the necessity of opening the valve F against the force due to the high pressure of the fuel in the passage 0, acting on the bottom of the valve, the valve stem f may be continued below the valve itself through the gland a in the pump body, as shown in the detail view Fig. 2.

As applied to a multi-cylinder engine, the

arrangement illustrated diagrammatically in Fig. 3 may be used, in which the fuel under pressure passes into a main supply pipe 7:. from which it is supplied to the injection valves F, one for each cylinder J, these valves being situated outside the pump body A. They are operated from the sliding cams f on the cam shaft D in the manner already described. The small bore tubes it lead from these valves to injection nozzles in each of the cylinder heads J. The relief valve E is also shown outside the pump body and the accumulator G is placed immediately below this valve. Excess fuel flows back into the pump through the small pipe 6 The pump employed in the multicylinder engine is preferably a three-throw pump, but the type of pump and also the details of the arrangement of valves and other parts may be varied as found convenient;

Referring to the three constructions of injection valve operating mechanism shown in Figs. 4-, 5 and 6 the valve lever f is controlled through the auxiliary lever operated by the cam f and turning around a movable fulcrum, the members f and f forming together a jointed double lever. In'Fig. f the lever f is mounted on an eccentric f on the shaft f the latter being rotatable through an angle by the arm The connection between the levers f an i is through the swivel f in which'the' end of the lever 7 slides. It will be seen that which fulcrum is the center of the eccentric f, is displaceable through an angle indicated on the shaft f", the displacement being towardor away from the end of the lever f. At the same time the fulcrum is lowered or raised, lowering or raising the cam roller f toward or from the cam f and thus varying the lift of the injection valve as well as the timing. Fig. 5 shows a very similar arrangement" but instead of employing an eccentric the lever f is mounted on the end of a vertical lever 7 carried by the pin 7 and the lever 7' is turned around thisv pm to move the fulcrum inc of the ltWeI f in a manner similar to that already described with reference to Fig. 4. In Fig. 6 the movable fulcrum of the lever 7 (which in this case is simply jointed to the lever f) is provided by the sliding roller 7 on the rod f, the roller travelingbetween the lever f and the fixed abutment f". In this arrangement the timing of the valve -is not altered but the lift may vary from zero to a maximum according to the position of the roller f and the consequent leverage of the lever f with respect to the cam and the end of the valve lever f.

What I claim and desire to secure by Letters Patent of. the United Statesis:

1. Fuel injecting apparatus for internal combustion engines, comprising a pressure accumulator, an injection valve, a pump adapted to pump an excess of. fuel into the accumulator at each stroke and an automatic relief valvein the same fuel channel as the accumulator and set to act at a predeter mined pressure that controls the maximum pressure at which the accumulator injects the fuel through the injection valve.

2. Fuel injecting apparatus for internal combustion engines, comprising a fuel receiving tube with resilient walls forming a pressure accumulator, an injectionvalve, a pump adapted to pump an excess of fuel into the accumulator at each stroke and an automatic valve in the same fuel channel as the accumulator and set to act at a predetermined pressure and adapted to limit the maximum pressure at which the accumulator injects the fuel through the injection valve.

3. Fuel injection'app'aratus for internal combustion engines, comprising a pressure accumulator, an injection valve, a pump adapted to pump an excess of fuel into the accumulator at each stroke, a suction valve for the said pump, means for holding the suction valve open and for allowing it to close slowly during the compression stroke of the pump so as to exercise an increasing choking action on the escape of the fuel and thus to raise its pressure gradually, and a relief valve set to act at a predetermined pressure and adapted to limit the maximum pressure at which the accumulator injects the fuel through the injection valve.

4. Fuel injection apparatus for multicylinder internalcombustion engines, comprising a pressure accumulator, an injection valve for each cylinder, a fuel supply pipe leading from the accumulator to each injection valve, a' pump adapted to pump an excess of fuel into the accumulator and a relief 'valve set to act at apredetermined pressure JAMES MQKECHNIE.

Witnesses:

JAS. C. FERGUSON, W. H. ATKINSON.

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