US2816534A - Fuel injection apparatus - Google Patents

Description

Dec. 17, 1957 L. o. FRENCH FUEL INJECTION APPARATUS Filed May 24 1956 INVENTOR.

$.40 QFM' United States Patent FUEL INJECTION APPARATUS Louis 0. French, Milwaukee, Wis.

Application May 24, 1956, Serial No. 586,985

2 Claims. (Cl. 123---139) The invention relates to fuel injector pumps for internal combustion engines and more particularly to unit fuel injector pumps of the compression pressure operated type.

it has been found in some designs of compression ignition internal combustion engines that the time delay period for the ignition of the fuel can be reduced and that in prechamber type engines the use of an ignition plug may be dispensed with if a pilot ignition charge of fuel is introduced in advance of the main charge. The object of the present invention is to provide a unit type of fuel injector pump in which the introduction of the pilot charge may be accomplished in a very simple manner and without any major change in the pump itself. More particularly, the invention resides in a modified form of nozzle structure from that disclosed in my prior U. S. Patent No. 2,642,315, dated June 16, 1953, whereby the needle that moves with the outwardly moving pump plunger is provided with one or more directional spray orifices for introducing the pilot fuel charge and which orifices are cut oif when the main charge is introduced.

The invention further consists in the several features hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In the drawings, Fig. 1 is a vertical sectional view through a fuel injector pump embodying the invention showing a form of application thereof.

Referring toF-ig. 1, the numeral 2 designates an engine cylinder, 3 the piston working in said cylinder and having an air cell 4 formed therein, and 5 an engine cylinder head.

The cylinder head 5 is shown as provided with a prechamber 6 and a tangentially disposed passage 7 leading from this chamber to a point in the head in line with the cell 4, a plug 8 closing the bottom of the chamber. The head has concentric bores 9 and 10 for receiving parts of the fuel injector pump which is clamped to the head by a clamping means including parts 11, parts of the bore 10 being separated by a water jacket space W.

The pump includes a housing 12, a top cap .13, and a bottom nozzle cap 1'4. The cap '13 is secured to the housing by the interlocking connection of castellated flanges on the upper part of the housing with similar flanges 16 on the cap and a set screw 17 for holding said parts against rotation relative to each other. The cap 14 has a flanged portion fitting over the lower end of the housing and is clamped thereto and in sealing engagement with the bottom of the bore 10 when the housing is clamped in position.

A differential diameter operating piston P has a larger diameter head part 13 working in a bore 19 of the housing and smaller diameter part 20 working in a housing bore 21 alined with the bore 19. Piston P has a centrally disposed bore threaded at its lower end 22 and has an annular groove 23 in registry with a fuel inlet port 24 and a fuel outlet port 25 of a suitable circulatory fuel supply system. The head part 13 carries sealing rings S. The part 20 has a liquid outlet groove 26 connected with a port 27 and fuel inlet groove 28 connected with groove 23, a port 29, and a pump supply and relief port St). A key 31 in the housing Works in a keyway 32 in part 26.

A fuel pump plunger 33 in the form of a sleeve is mounted at its upper flanged end between the housing and a recessed portion of the cap 13 for angular movement and carries an actuator 34 Working in a slot in the cap. A by-pass metering scroll 35 on the plunger cooperates with the port 30 to by-pass more or less fuel from the pump chamber. Oppositely disposed arcuate grooves 36 and 37 are connected with the interior of the plunger by ports 38 and 39 and register respectively with the ports 27 and 2a in any angular position of the plunger relative to the piston 20.

A member 40 in threaded engagement with the bore 22 closes off said bore and has a needle extension 41 working in a bore 42 in the cap 14, said bore having an enlargement 43. The extension 41 cooperates with the lower end of the bore 42 to form an annular fuel discharge orifice. Member 40 has a valve seat 44 with a fuel discharge passage 45 leading therefrom to one or more orifices 46 and may have a passage 46a registering with the enlargement 43 to permit fuel to feed to the lower end of bore 42 as determined by the pintle end of the needle extension. The cap 14 has gas passages 47 connecting a reduced diameter bore 43, communicating with the bore 9, with the prechamber 6.

A differential pressure operated needle valve 45 works in the bore of the sleeve plunger 33 and controls passage of fuel through the discharge passage 45. Its upper end is of differential diameters, the smaller of which normally abuts a timing piston valve 56.

The valves 49 and 50 are adjustably loaded by a spring 51 mounted in the bore of plunger 7 between the valve 250 and a load adjusting screw 52 mounted in a threaded bore 53 in the cap, said spring acting through said valves to move piston P to its inner position, and hold valves 49 and 50 in their closed positions.

With the parts, as shown in their initial position, cooled fuel from the circulatory system passes from inlet port 24 via groove 23 to outlet 25, and some of this fuel passes from groove 23 via groove 28 to a chamber 5% formed between piston P and the housing and also passes through port 30 to the pump chamber 55 to fill these chambers. Chamber 54 is a cooling, sealing, timing, and checking chamber. When, during engine compression, gases from prechamber 6 and passages 47 acting on the exposed end of piston P, move it outwardly against the initial loading of spring 51, the port 30 and groove 28 are lapped by the housing and the port 30 is lapped by the plunger 33, thereby trapping fuel in chambers 54 and 55 and stopping movement of piston P. While so trapped, the pressure of the liquid in chamber 54 will be greater per unit area than that :of the gases that might tend to leak by the piston. This movement also brings the port 27 into full registry with the recess 37 so that chamber 54 is then hydraulically connected with the annular space below valve 50 while the port 38 is still lapped. As compression increases, liquid pressure builds up in chamber 54 against the exposed differential area of valve 50 and the differential area of the back end of the valve 49 until near the end of the compression stroke the loading of spring 51 is overcome by the hydraulic pressure acting on the exposed area of valve 50, it being noted, however, that the pressure in chamber 54- is acting on the differential rear end area of the valve 49 so that the pressure in chamber 55 necessary to open this valve Will be greater than that in chamber 54. As soon as the valve 50 uncovers the port 38, then liquid in chamber 54- can pass via groove 26, port 27, groove 37, annular space between the valves 49 and 50, port 38, groove 36, port 29, groove 23 to outlet port 25 so that the operating piston is free to move outwardly on its injection stroke, and then since the pressures in chamber 54 have been reduced, the pressure in the chamber 55 acting on the head end area of the valve 49 opens this valve and allows it to move with the valve 50. On opening of the valve 49, fuel, as a pilot jet, is discharged through the orifice 46 into the passage 7, and then as the piston P continues to move this pilot jet is cut off and then fuel is discharged into the prechamber 6 through the orifice formed between the needle 41 and the bore 42. The shape of the needle below the orifice 46 will determine the rate and character of the spray delivered to the prechamber 6 for the rest of the pump stroke. The size of the orifice 46 may be such that some of the fuel discharged through the passage 7 may reach the combustion chamber C of the engine and mix with the air therein and be ignited and blow back into the prechamber 6 so that the air therein will readily ignite the main fuel charge delivered into this chamber as the piston 3 reaches or is passing its upper dead center. On expulsion of the burning fuel mixture from the chamber 3 some of this fuel will enter the air cell 4 and be ignited and blown back into the combustion chamber 3 to aid in distributing the charge, passing from passage 7 to cham ber C, throughout said chamber as the piston 3 makes its working stroke.

Depending upon the angular adjustment of the scroll 4 are of small area, it is not necessary to use a large spring to load these valves to secure the desired operation of the operating piston. Since the needle extension moves up into the bore 42 during injection, it is protected from the high heat of the gases following injection.

Reference is here made to my copending applications Ser. No. 470,978, filed November 24, 1954, for Fuel Injection Apparatus, now Patent 2,799,263 issued July 16, 1957, and Ser. No. 553,899, filed December 19, 1955, for Fuel Injection Apparatus, now Patent No. 2,799,535 issued July 16, 1957, having claims to common subject matter not claimed herein.

I desire it to be understood that this invention is not to be limited to any particular form or arrangement of parts 35, sooner or later, the port 30 overruns this edge to coning the port 38. Under these conditions the liquid pressure in chamber 54 is also acting on the upper end of valve 49 to close it and hold it closed while both valves continue to move with the operating piston until the groove 26 is lapped by the housing and further movement of said piston stopped by the liquid trapped in chamber 54. Port 27 is preferably a restricted orifice to permit, during the movement of piston P, the maintaining of per unit pressure in chamber 54 greater than that acting on the exposed face of said piston to seal against gas leakage. As soon as piston P comes to rest during the high pressure period of the engines cycle following injection, the pressure of the liquid in chamber 54 will obviously be greater to seal against gas leakage. When during the engines cycle, the pressure in the combustion chamber and chamber 6 drops sufiiciently, the spring 51 acting through the valves 49 and 50 returns piston P to its initial position ready to repeat the cycle.

Varying the loading of spring 51 by adjustment of the screw 52 varies the time of beginning injection. This adjustment can be under remote control, if desired. Under no load adjustment of the plunger 33 the cycle is the same as above 4 except insofar as such limitations are included in the claims.

What I claim as my invention is:

1. In a fuel pump for internal combustion engines, the combination with a fixedly positioned spray orifice communicating with the combustion chamber of the engine and a bore communicating therewith, of a fuel pump including a reciprocatory pump piston movable outwardly of the combustion chamber of the engine and having a fuel discharge conduit extension receiving fuel at pump injection pressure and working in said bore, the outer end of said discharge extension having a pintle portion cooperating with said orifice to form a pintle injection nozzle, and a spray orifice in said extension in advance of said fixedly positioned orifice for introducing a pilot jet of fuel into said combustion chamber during the first part of the outward movement of said piston and for thereafter supplying said pintle nozzle with fuel from said extension.

2. In a compression pressure operated fuel pump for internal combustion engines, the combination with a fixedly positioned spray orifice communicating with the combustion chamber of the engine and a bore communicating therewith, of a compression pressure operated fuel pump including a reciprocatory operating piston movable outwardly of the combustion chamber of the engine by compression pressure and having a fuel discharge conduit extension for receiving fuel at pump injection pressure, said extension working in said bore and having a pintle portion at its outer end cooperating with said orifice to form a pintle injection nozzle, and a spray orifice in said extension in advance of said fixedly positioned orifice for introducing a pilot jet of fuel into said combustion chamber during the first part of the outward movement of said piston and for thereafter supplying said pintle nozzle with fuel from said extension.

References Cited in the file of this patent UNITED STATES PATENTS 2,576,451 Dickson et al. Nov. 27, 1951 FOREIGN PATENTS 886,596 France July 5, 1943 977,818 France Nov. 15, 1950

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