US1193909A - mckechnie - Google Patents

Description

l. MCKECHNIE.

INJECTI'ON 0F LIQUH) FUEL IN INTERNAL COMBUSTION ENGINES.

APPLICATION FILED AUG.5| 1913.

l, l 93,909. Patented Aug. 8, 1916.

.2 SHEETS-SHEET l.

!llllll Illia/114g J. IVICKECHNIE.

INJECTION 0F LIQUID FUEL IN INTERNAL COMBUSTION ENGINES.

v APPLICATION FILED AuG.5, |913.

1,193,909. I Pat-endAug. 8,1916.

2 SHEETS-SHEET 2.

/ INvIERIToR ,j Mw Z@ @ma f lpowers maybe obtained.

JAMES MQKECHNIE, 0F BrBROw-INFURNESS, ENGLAND, .SSIGNOR T0 VICKEBS VI'iIlflilIlITE'lD, 0F IBABRGW-IN-FUIBNESS, ENGLAND..

INJECTION OF LIQUID FUEL IN INTERNAL-COMBUSTIO ENGINES.

Specification of Letters Patent.

Patented Aug. 8, Igi.

Application filed August 5, 1913. Serial No. 783,054..

To all 'whom t 'may concern.'

Be it known that I, JAMES McKEoHNm, a subject of the King of Great Britain, residing at Naval Construction Works, Barrow-in-Furness, in the county of Lancaster, England, have invented certain new and useful Improvements inV the .Injection of Liquid Fuel 'in Internal-Combustion Engines', of which the following is a-speciiication.

'This invention relates to the injection of liquid fuel at extremely high pressures into the cylinders of 'internal combustion engines of the type in which the fuel is ignlted as it enters the cylinders, 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 According to my invention the fuel is injected by the direct action of a pump the plunger of which has 'a stroke capable of pumping a large excess of fuel and the high pressure desired at the period of injection is attained gradually during the idle portion of the pump compression stroke, by exercising an increasing choking action'on' the escape of the excess fuel, which choking action is conveniently produced by mechanically operating the suction valve so that it closes slowly during the first part of the said compression stroke. The fuel pressure-.iis by this means steadilypraised while the valve is slowly closing, the final portion of the pump stroke, with the valve closed, being arranged to give a fuel charge only slightly in excess ofthe full charge required. The gradual increase of pressure up to the maximum avoids any sudden shock which would otherwise be experienced in delivering the fuel at the high pressures necessary and in the short time allowed. The charge is determined by the operation of an injection valve, which I prefer to yfitl in the pump casin but which may be tted to the engine cylin er. Theopening of this valve, which is timed to occur during the final portion of the pump stroke, is controlled by any suitable mechanism such as a cam and lever, and the period and extent of valve opening regulate the charge of fuel injected. The excess of fuel delivered by the pump is' returned to the suction side through a relief valve which determines the maximum pressure'of injection and as there is always some excess to be passed through the relief valve the pressure is the same for the injection of both large and small quantities of fuel. The opening of the injection valve may be regulated by a sliding cam having a tapering cam surface of suitable form, so that anl axial movement of the cam simultaneously adjusts the timing and the period and extent of opening. 0r I may effect the desired adjustment' through the cam operated valve lever byproviding, for example, a movable fulcrum for a jointed lever, the extent .of valve opening varying according to the positlon of the fulcrum. The timing ofthe valve may be simultaneously adjusted by mount-v with reference to the accompanying draw- Figure 1 is a section of pump and valve apparatus 'embodying the principles of my invention. Fig, 2 is a side elevation of the suction valve cam. Fig. 3 is a diagram p villustrating the application of the invention to amulti-cylinder engine. n

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

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 valve controlled by the sliding cam f on the shaft D.

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

K is a pressure gage on the small bore pipe It connecting the nozzle II to the pump casing.

The pumpy plunger B is driven by the ec rio required for each stroke. The plunger `extends through the gland b in the casing A and its head b2 slides in an extension a of the'casing and forms a ball and socket joint with the end of a short rod b3 on the eccentric Zi. 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 Z, the suction valve C being opened against the pressure of the spring c. Above the short stem of the suction valve is a valve operating rod .c2 passing through the gland c3 and provided with a head c4 connected to the rod c2 at c* sliding in an eX- tension a2 of the pump casing and having al spring c5 bearing on its under side. The

' cam c acts on the rod c2 against the spring a5 l plunger B gradually increases by reason ofV through the roller c6 on the head c4. Thel 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 due to the compression stroke of the the choking action and reaches its maximum only at or after the complete closing of thev suction valve. The valve C is held fully open While the concentric cam face c" (-Fig. 2) is operative, but when the' cam c has turned until a point at about 08 on the sloping face 09 at the end of the part c7 is reached, the pump begins its delivery stroke. Immediately after, the very gradual cam slope 01 becomes operative .to .permit the valve C' to slowly'close, and thus produce a choking action upon the fuel. This choking action continues at increasing strength until the-point c is reached at which complete closing of the valve Cl takes place and full fuel pressure is exerted. The valve C remains closed throughout the remainder of the delivery stroke corresponding to the con- 'centric part 012 of the cam c.

The maximuml pressure developed by the pump is determinedby the relief valve E on which bears the powerful spring e, thestrength of which spring can be regulated by screwing the separate valve head e in or out of the plug a3 secured in the valve body A, this plug having a relief'opening e2 in its side through which excess fuel can escape to a reservoir or back to the chamber L.4 The spring e is set so as to give the maximum pressure desired, this pressure being attained before the plunger B reaches the end of its stroke. The remainder of the stroke forces the fuel into the cylinder on the opening of the valve F and drives the excess fuel l from the (usually a small portion'only) through the relief valve. -The maximum pressure may thus be practically maintained throughout the injection, owing to the excess supply pump during the latter part of its stroke.

The injection Valve F is shown in Fig. l 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 a4, this arm bearing on a collar .f2 on the valve stem f3, the upper end of which is acted upon vby thespring f4 lplaced in a cup at the end of a bracket a5, the spring f* closing the valve when released by the arm f. The timing cam f is arranged to slide v upon the cam shaft D, a groove f5 receiving the cam adjustingrmeans. 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 valve F always occurs after the closing of the pump suction valve and when the maximum fuel pressure has been attained so that imme 'ately the valve F is opened the fuel is for d under the extremely high pressure given by the pump and relief valve through the small bore pipe la. and the cylinder nozzle H, the fuel entering the cylinder as a fine spray which instantly vaporizes.

The general operation of the fuel injection mechanism is as follows The pump plunger B is driven from the engine through the shaft D and eccentric b, the stroke of the pump 4being constant. The suction valve C is also controlled by the same shaft D through the cam c .which is so formed as to permit the suction valve to close very gradually. 4At each revolution, therefore, of the shaft D the pump B on its upward stroke draws in a constant -volume of fluid from the fuel chamber L through the suction valve C. On the return or compression stroke of the plunger the suction valve C does not close immediately as would be the case if it were not under mechanical control. The cam c allows -it to approach its seat gradually the passage being reduced suiiciently to exercise a choking effect so that the pressure of the fuel in the passage a. gradually rises. At a convenient point in thepump stroke the valve C isl allowed to close completely and the pump works in its normal manner. The maximum pressure of the fuel vis however limited by the spring controlled relief valve E. After the closing of the suction valve the injection valve F is Opened by the camA f, the time and period of opening being variable as already described. The pump plunger continues its compression stroke whlle the injection valve ing cams ner alrea y described. The small bore tubes for maintaining the openingof the said f is open so that it directly forces the fuel under extremely high pressure through the valve and into the cylinder. l

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 It 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 slidon the cam shaft D in the manh lead from these valves to injection nozzles in leach of the cylinder heads J. The relief valve E is also shown outside the lpump body and the excess fuel flows back into the pump through the small pipe e3.

What I claim and desirev to secure by Letters Patent of the United States is 1. Fuel injecting apparatus for internal combustion engines, comprising a pump adapted to pump a large excess of fuel ateach stroke, mechanically operated valve mechanism for regulating the supply of fuel to the e ine cylinder and for admitting it only during the latter part of the pump compression stroke, a valve allowing escape of fuel during the idle portion of the pump compression stroke and mechanical means valve, before'the admission of the fuel to the cylinder, so small as to exercise a substantial choking effect on the escape ofthe fuel and for slowly closing the valve so as to increase the choking effect up to complete closing and thus gradually to raise the fuel pressure up to the high pressure of injection. e

2. Fuel injecting apparatus fol' internal combustion englnes, comprising a pump adapted to pump a large excess of .fuel at each stroke, mechanically operated valve mechanism for Yregulating the supply of fuel to the engine cylinder and for admitting it only during the latter part of they pump compression stroke, a pump suction valve and means for maintaining the opening of the said suction valve during the idle portion of the compression stroke of the only during the latter partV ofthe pump j compression stroke, a Valve allowing escape of fuel during the idle portion of the pump compression stroke, mechanical means for maintaining the opening of the said valve, before the admission of the fuel to the cylinder, so small as to exercise a substantial choking effect on the escape of the fuel and for slowly closing the valve so as to increase the choking effect up to complete closing and thus gradually to raise the fuel pressure up tofthe high pressure of injection, and a relief valve between the pump and the engine, set to .open at a predetermined fuel ressure which controls the pressure 4of inn jection.

In testimony whereof l ax my signature in presence of two witnesses. Y

J AMESA MCKECHNIE. vWitnesses:

JAS. 0.*FERGUsoN, W. H. ATKINSON.

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