US2552778A - Fuel injector - Google Patents

Description

L. O. FRENCH FUEL INJECTOR May 15; 1951 Filed Aug. 28, 1948 lllll INVENTOR.

Patented May 15, 1951 UNITED STATES Y PATENT OFFICE FUEL INJECTOR Louis 0. French,` Milwaukee, Wis.

Application August 28, 1948, Serial No. 46,683

vide a unit injector in which any products of l combustion are effectively prevented from blowing back into the pump chamber.

A further object of the invention is to provide an automatic or compression pressure operated unit fuel injector in which the operating piston i is effectively sealed against the escape of gases from the combustion chamber.

A furtherobject of the invention is to provide an automatic or compression pressure operated unit fuel injector in which the operating piston is efficiently cooled by a continuous circulation of fuel while fuel is intermittently supplied from the same fuel supply as a checking fluid to vary the stroke of the operating piston.

A further object of the invention is to provide a novel arrangement of pump discharge valve, injection pressure control valve, and fuel discharge conduit for fuel injectors.

A further object of the invention is to provide an injection pressure control valve of the differential needle type of simple and compact construction.

The invention further consists in the several features hereinafter described and more particularly defined by claim at the conclusion hereof.

In the drawings:

Fig. 1 is a vertical sectional view through a fuel injector embodying the invention;

Fig. 2 is a vertical sectional view taken on the line 2-2 of Fig. 1;

Fig. 3 is a horizontal sectional view taken on the line 3--3 of Fig. 1;

Fig. 4 is a side elevation view of a portion of the operating piston;

Fig. 5 is an enlarged sectional view of the check valve and the injection pressure control valve showing certain' modifications.

Referring to the drawings, the injector has the relatively fixed metal housing parts comprising a piston stop 6, cylinder 1, and cap 8.

The stop 6 is a ring seating on an annular flange 9 formed in the head IIJ of an internal combustion engine and has a valve seat surface II.

The cylinder 1 has a flat top and a straight bore I2, a counter bore I3, a relief port I4, a coolant supply port I5, and a coolant return port I8. In the form shown, the fuel is used as the coolant. The cylinderl'l is secured in the ensol 1 Claim. (Cl. 10S- 41) gine head against the stop 6 by any suitable clamping means.

The cap 8 has a flat faced flanged end I1, a guide bore I8, and a valve seat I9 at the inner end of said bore. It also has a checking fluid inlet 20 in which a spring closed check valve 2| is mounted. A packing ring 22 of elastic material, such as a suitable synthetic rubber composition, is mounted in the counterbore |I3 and compressed between the cylinder 'I and the cap 8 when the flat faces of said cap and cylinder are clamped together by screw bolts 23 passing through the flanged portion of the cap and anchored ,in the cylinder.

A piston 24 working in the bore I2 is moved in one direction by the compression pressure of the gases in the combustion chamber C of the engine and in the opposite direction by a spring 25. The piston 24 has an operating piston portion 26 and a checking piston portion 21 and a high pressure pump bore 28 provided with fuel inlet ports 29.

The portion 26 is provided with a groove 30 to receive an O-ring 3| of elastic material, such as a suitable synthetic rubber composition, and

with a recess 3| to receive abutting metal piston rings 32 which are `retained therein by sleeve nut 33 mounted on the reduced threaded end 34 of said piston and provided with Wrench engaging flats 35. Portion 26 also has a bore 36 of larger diameter than the bore 28 and forming a shoulder 31, and it is also preferably annularly recessed at 38 back of the ring portion 30 to increase the cooling surface adjacent said ring. The piston 24 is preferably a casting, and where the pump bore 28 is integral, it may be made of a suitable alloy steel. Where said piston 24 is made of cast iron or aluminum, it may have the usual hardened steel liner for the bore 28.

`A check valve interposed between the high pressure pump chamber 39 and the injection pressure control valve is formed by a metal ring member 40 provided with an internal flange 4I forming a seat for one side of a valve member in the form of an O-ring 42 of elastic material, such as a suitable synthetic rubber composition. A metal ball valve 43 is mounted in the ring 40 and seats on the other side of the O-ring 42 and is held thereagainst under a predetermined compression due to the spacing of the bottom plate 44 from the flange 4I, said plate having a central fuel passage 4S connected by grooves 4l in the top face of its projection 48 with the interior ofthe sleeve or ring 4i).` v.Fuel from the pump chamber is forcedoutwardly from the, pump chamber against the inner bore of the elastic ring 42 which will yield enough so as to allow the fuel to pass between said ring 42 and the ball 43. Should gases from the engine reach this valve, they will act on the ball 43 tending to exert further pressure on the ring 42 than thai'l initially imposed and acting to hold said ring 42 in sealing engagement with the ball and in sealing engagement with the flange 4I. The gases may also act upon the lower exposed surface of the ring 42 tending to hold it against the seat formed by the flange 4I. No seat grinding is necessary for this check valve structure, and the 5I which may at this end form with the valve a spray nozzle 54, as shown in Fig. l, or which maybe connected by a passage 55 with a spray orifice or nozzlerli, as shown in Fig. 5. Valve 524 has a flange portion 51 of large diameter and ay stem portion 58 of reduced diameter, the differences in area between these portions being greater than the area of the said stem and its prolongation 59 on the other side of said flange 51. A fuel passage 60 extends through the portions 58 and 51 and into the prolongation 59 and connects below the flange portion 51 with a crosspassage BI communicating with the lower end of the bore 55. The annular space between the stem portion 58 and the bore 55 is filled with an elastic packing, conveniently formed by'a stack of O-rings 62 of a suitable'synthetic rubber composition. With the valve in assembled position the plate 44 in abutting the top of member 49 puts a predetermined pressure on the rings 52 which in turn act to hold the valve 52 against its seat. When the pressure in the high pressure pump builds up to a point above that of the initial pressure imposed on the packing or rings, the fuel passing through the passages 6B and 6I acts on the lower face of the valve 52 and lifts the same from its seat and fuel may then pass through the discharge member 49 to the spray nozzle. It will be noted that the fuel passing through the stem cools those portions of the valve with which the O-rings 52 are in contact. The stem portion 58 preferably extends above the top of the packing to facilitate disassembly, and the lift of the valve 52 may be limited by the top of said stem engaging the top ofthe' guide bore 63 in the plate @L The prolongation 59'is provided with flats 54 to form fuel passages to the lower end of the bore 5I. The-member :i9 may have direct threaded connection with the lower threaded end of the nut 33, or it may be mounted in the differential bores 65 and 66 of va sleeve nut 61 provided with wrench engaging flats 58 and with a conical seating surface 59 which normally seatson the seat surface I1. The nut 61 clamps both of the valve assemblies in the lower end of the operating piston.

A high pressure pump plunger 10, working in the'bore 28, controls the ports 29, and after their closure on the outward movement of piston 24, fuel isl compressed or put under pressure in the pump chamber 39 until the closing pressures of the check valve and the needle valve' are overcome, and then this fuel is discharged into the combustion chamber through-the spray orifice,

the' amount of fuel depending upon the relative movement ofl said plunger' and/piston '24. "To

oflthe available stroke period at which this occurs being determined by the angular setting V,of said edges 12 and 13 relative to said port so as to produce either a complete lapping of this port relative to the control edge 12 or a lapping of said port after a predetermined movement of said piston.

For adjusting the angular position of control edges 12 and 13 relative to the port I4, a rotatable valve like member 14 mounted in the bore I8 and seating on the seat I9 has depending key projections 15 slidably engaging in key slots 1B in a flange 1l 'at the top of the piston part 21. The exposed end of the stem of the member 14 has an operating handle 1S slidably keyed thereto and Secured by a nut 19 against a shoulder on said stem. The spring 25 engages the head of plunger 'Iii which in turn abuts the'head of member 14, so that the same is normally sealed against the cap 8. By rotation of the member 14 either through the handle 18 or any other suitable turning means, such for example, as a rack and pinion, the piston 25 is moved to the desired po sition relative tothe port I4.

The loading of spring 25 may be used todeterminethe time of injection, but preferably the timing of the injection is controlled by a variable pressure relief valvecomprising a valve casing 55, a valve 8l, and an adjustable closing spring 82 associated with the relief port I4. The valve 8i carries an elastic O-ring SI 1.

The casing 85 has a passage 83 connecting port I4 with a valve seat B4 and a guide bore 85 enlarged adjacent the seat'and connected by a return passage with piping leading back to the fuel supply pump. Casing 8l) has a threaded end 86 for a manually adjustable spring tensioning nut 81. The loading of the spring 82 acting t0 close the valve is suicient to check the movement of the piston .'24 'until the desired time for injection, near the end ofthe compression stroke, has been reached, and this time may be varied to suit engine operating conditions.

The fuel supply piping has been indicateddia-'- grammatically in Figs. l and 3 wherein the numeral 38 designates a fuel supply pipe for 'conf neotion with any-suitable low pressure fuel pump and provided with branch connections 89V and .-90-

connecting, respectively, with the check valve 2l and the inlet port I5. A fuel return pipe 9| leadingback. to the supply tank, respectively,

connects by. branch connectionsSZ and 83 with,

the return port I5 and the outlet from the timing relief valve. Thus the fuel is continuously circulated through the space @4in the bore I2, cooling the piston `24 and supplying the high 4presy sure pump chamber 39 with fuel while the cham ber 1I is supplied with fuel as a checking fluid` in accordance with its requirementsQthe displaced checking iiuid returning to the fuelV sup-f ply.c The fuel supply system will, of course, have a suitable cooler so that the piston'Zll is kept at by. the.

With the above construction, the lower end of the piston 24 being exposed to the pressure of the gases in the combustion chamber C of the engine, when this pressure exceeds the loading of spring 25 and the spring 82, port I4 is opened to relief and piston 24 moves outwardly, closing oif the ports 29 and building up pressure in the pump chamber 39 which then acts to open the check valve including ring 42 and to open the needle valve 41 to cause the injection of fuel. The unit pressure imposed on the checking fluid in chamber 1I against movement is relatively loW compared to the fuel injection pressure. Angular adjustment of piston 24 changes the amount of fuel injected, and adjustment of the relief valve changes the time of injection.

Reference is here made to my copending applications Serial No. 748,140, filed May 14, 1947, for Fuel Injector, and Serial No. 785,179, filed N0- vember 10, 1947, as to claims for common subject matter.

I desire it to be understood that this invention is not to be limited to any particular form or arrangement of parts except in so far as such limitations are included in the claim.

What I claim as my invention is:

In a fuel injector, the combination of a housing provided with a bore and fuel inlet and discharge passages and a relief passage communi'd eating with said bore, said housing also provided with a check valve controlled checking fluid inlet passage communicating with said bore, a fuel supply pipe connected with said fuel inlet passage and the checking fluid inlet passage, a return pipe connected with said fuel discharge passage and said relief passage, a piston movable in said to hold the operating piston bore in response to gases under compression having an operating piston portion and a checking piston portion spaced therefrom to form a cooling space, said fuel inlet and discharge passages being in continuous communication with said space in any position of said piston in said cylinder for continuously circulating fuel through said space, a fuel pump having its bore in said piston, a pump plunger held against longitudnal movement and Working in said fuel pump bore to discharge fuel therefrom on the movement of said piston by said gases, means for supplying fuel to said fuel pump, said checking piston portion having a control edge cooperating with said relief port to vary the amount of checking fluid discharged through said relief port to varably limit the movement of said piston and thereby vary the amount of fuel delivered by said fuel pump, and .rea-ns for angularly adjusting said ypiston relative to said relief port.

LOUIS O. FRENCH.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 1,863,075 Terry June 14, 1932 2,045,196 Mohr June 23, 1936 2,061,813 Smith Nov. 24, 1936 2,337,731 Buck Dec. 28, 1943 2,350,434 Wallgren et al June 6, 1944 2,371,787 Ward Mar. 20, 1945 2,378,165 Waeber June 12, 1945 2,389,492 Edwards Nov. 20, 1945 2,408,288 Bremser Sept. 24, 1946

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