US2552776A

US2552776A - Fuel injector

Info

Publication number: US2552776A
Application number: US748140A
Authority: US
Inventors: Louis O French
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-05-14
Filing date: 1947-05-14
Publication date: 1951-05-15
Anticipated expiration: 1968-05-15

Description

L. o. FRENCH May 15, 1951 FUEL INJECTOR Filed May 14, 1 947 1N VEN TOR.

Patented May 15, 1951 UNITED STATES FATELNT @ENCE FUEL INJECTOR Louis O. French, Milwaukee, Wis.

Application May 14, 1947, Serial No. 748,140

` 14 Claims.

The invention relates to liquid fuel injectors for internal combustion engines and more particularly to those injectors in which the pump and nozzle are associated as a unit.

One of the objects of this invention is to improve the pump discharge valving by providing a light Weight disk type check valve between the pump chamber and the heavily loaded discharge valve, said check valve being mounted in a jpocket including the head portion of said discharge valve which check valve will automatically close under the action of cylinder gases and the suction effect of the pump to insure complete filling of the pump chamber even if the loaded valve may be leaking but which will open readily during the delivery stroke of the pump to permit delivery of the fuel charge past the loaded valve and through the nozzle into the engine cylinder.

A further object of the invention is to provide a discharge valving for unit injectors comprising a disk type check valve and a resilient metal disk disposed adjacent said check valve and initially il'exed to a loaded condition.

Automatic or compression pressure operated unit fuel injectors have advantages over the usual injectors in which the pump plunger or the injector valve is mechanically operated, but they present certain problems in design, one of which is the efficient cooling of the moving parts of the injector without making the same too bulky. A further object of this invention is to provide an automatic unit fuel injector in which the compression pressure operated piston is so formed as to insure cooling of the lower end of said piston and the parts of the discharge valve I bylthe fuel, preferably circulated through said piston and its cylinder and in this connection this application is a continuation in part of my copending application Serial No. 578,695, filed February 19, 1945, and also a continuation in part of my copending applications Serial No. 676,952, filed June l5, 1946, and Serial No. 698,834, led September 23, 1946, now Patent 2,516,692, granted July 25, 1950, as to cooling features that may be common to both. Reference is here made to my copending application Serial No. 673,075, filed May 29, 1946, now abandoned, for Valve for Fuel Injection Systems, for any claims to common subject matter.

A further object of the invention is to provide a unit fuel injector of the compression pressure operated type in which the operating piston has a constant stroke and is cushioned at the end of its outer stroke by a hydraulic dash pot formed between said piston, its cylinder and an end (Cl. 12S- 139) cap removably secured to the cylinder, the metering and timing of the fuel injection being accomplished by the rotation of the high pressure pump plunger relative to the inlet port or ports in the barrel portion of the operating piston.

A further object of the invention is to insure a close concentric t between the operating piston, its cylinder and a sleeve extension of the end cap forming the fluid cushion stop even though the high pressure pump plunger and its rotator may not be truly concentric with these parts by providing an Oldham coupling connection between the piston and its rotator, the parts of said connection being held in operative relation by the spring for returning the operating piston, said spring also holding the valved end of the rotator in fluid-tight sealing engagement with said end cap.

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

In the drawings:

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

Fig. 2 is a detailed horizontal sectional view taken on the line 2 2 of Fig. 1;

Fig. 3 is a detailed vertical sectional View taken on the line 3-3 of Fig. 1, parts being broken away; l

Fig. 4, is an enlarged vertical sectional view of parts shown in Fig. 1;

Fig. 5 is a View similar to Fig. 4 showing certain niodications, parts being broken away;

6 is a detailed vertical sectional view 'through a check Valve;

Fig. 7 is a vertical sectional view through a portion of an operating piston showing certain modications.

Referring to the drawings, a fixed casing is formed by a valve seat and stop member IQ, a cylinder I I, an end cap or cover I2, and means for clamping said cylinder and cap together including a flanged sleeve member I3 having a differential bore I4 in which the outer flanged end of the cylinder is mounted and threaded at its cuter end i5 to take a sleeve nut IB which abuts the inner flanged end I'I of the cap to clamp both said cap and cylinder between it and a ange I6, a suitable sealing gasket I9 being interposed between the nut, cap, and member I3. The member I0 may seat on an annular flange 26 on the cylinder head 2| of an internal combustion engine at the end of a bore 22 in which the lower end of the cylinder II is mounted in abutting relation therewith, these parts being held in assembled relation with the head in any suitable manner, as for example, by a work holder` type of clamp whose forked ends 23 are indicated in Fig. 1.

The cylinder II has a straight through bore 24, a slot 25 connecting at one end With a fuel inlet port '.25 in the casing member I3 and at its other end with a port 21. It also has a slot 2S through which an alining screw 29 mounted in the member I3 extends. It has a flat outer end 3D.

The cap or cover I2 has an inwardly extending cylindrical portion 3| spaced from the walls of the bore 2A, a centrally disposed bore 32 with a valve seat 33 at its end and a bore 34 extending from said seat to the outer end of the cap. The lower face 35 of its flanged end I'I is flat to abut the end 3U and has a fuel outlet 36.

An operating piston 3l is mounted to reciprocate in the cylinder I I and is preferably formed of two parts, an outer sleeve 33 and a headed inner sleeve member 39.

The outer sleeve 355 is preferably a plain cylindrical member having grooves 40 to receive piston rings il a port i2 which may have a grooved inlet and registering with the port 21 in any position of the piston and a key slot 43 in which the extended end of the screw 29 projects to form a sliding key connection therewith. It has a lubricant supply groove M which may connect either with a suitable separate supply of lubricant, or where the fuel is used as lubricant, a groove l5 extending outwardly to a position near the port i2 may be used to allow fuel seeping along the piston to find its way to said groove.

The member 39 is formed with a flanged head 46 closing off the inner end of the member 38 and provided with wrench engaging flats 6.1 and having a tapered end surface 43 for seating on the seat l to reduce the loading pressure of a return spring 49 and permit rapid acceleration of said piston after said valve opens and the full area of said piston is exposed. Member 33 has a cylindrical portion ii which has a drive or tight pressed fit in the inner end of the sleeve 3B to form a fluid-tight connection therewith, or it may be welded to said sleeve 38. Member 39 also has a cylindrical portion 5I spaced from the inner walls of the sleeve 38 and which connects with a high pressure pump barrel portion 52, which parts form with the sleeve 38 a cooling chamber 53. The barrel portion 52, as shown in Fig. l, and in some instances a part of the portion 5I, has a flanged or cylindrical portion 5d which preferably nts loosely in the bore of the sleeve 38 and forms a partition provided with diametrically disposed slots or

passages

55 and 55 forming fuel inlet and outlet passages, respectively. The portions v5i) and 5I have a bore 5'! of larger diameter than the barrel bore forming a shoulder 58 therewith, ysaid bore extending through 'the head @-8 and threaded at 59 for either the spray nozzle 53 or a sleeve clamping nut 6I engaging the 'shouldered portion of said nozzle. A high pressure pump plunger `52 works in the `'barrel 52 and controls one or more fuel ports '33 connecting its interior with either the chamber 53 or the

passages

55 and 56 communicating therewith.

This plunger extends up into the bore 32 and is operatively connected with a rotator 34 either by forming these parts in one piece or by an Oldham type of universal coupling connection between these parts vwhich will permit self-centering of the plunger relative to its barrel and the rotator. The rotator 64 has a valved head 65 seating on seat 33 and a shank '55 extending through the bore 34 and operatively connected at its exposed end to the usual rack and pinion actuator or to a crank arm 61 which may be either manually or governor controlled. The coupling connection is formed by a disk member 53 which may be loosely pinned (not shown) to either the rotator or the plunger to facilitate assembly and having diametrically extending tongues or ribs 39 extending at right angles to each other, one of these ribs being slidably mounted in a diametrically disposed slot 1|! in the head 35 and the other in a similar slot 'FI in the outer end of the head of the plunger. These parts are held in assembled relation by the spring 39 which is interposed between the head of the plunger and a part of the piston 3l, said spring also serving to hold the head 65 in duid-tight sealing relation with its seat 33.

The outer tubular end of the member 38 slidably rits within the bore 24 and the cylindrical portion 3i of the cap i2 and cooperates with said cap and cylinder II to form an annular chamber 'E2 in which fuel will be trapped and act as a hydraulic cushion or snubber to arrest the outward movement of the operating piston 3l, one or more .Jy-pass ports 'E3 being provided in the sleeve 3i to regulate the escape of cushioning) fuel in the advance of the piston reaching its stop position in which the ports are lapped. YAs the face 35 of the cap has a flat faced contact with the end 3G against which it is clamped by the nut i5, 4it is Vself-centering relative to the sleeve 3S, so that if the inner and outer surfaces of said sleeve 38 are ground truly concentric, an efcient dash pot and cushioning stop action of the piston by fuel trapped in the chamber I2 is assured.

The plunger 52 is recessed to provide control surfaces le and "l5, an annular recess 'I6 and groove il, these being .of known construction and cooperating with the port or ports 63 in the barrel, so that Vvariable timing of the beginning of injection determined by the control surface ill and variable volume of injections determined by the surface 'l5 may be obtained by shifting the angular position of said plunger relative to said ports by the adjustment of the rotator 64. Other forms of by-pass control edges may be used 'without departing from the invention, it being noted that the stroke of the piston 31 is constant while the by-pass in the plunger provides a variable relief for the fuel in the high pressure pump chamber.

Various forms of discharge valve mechanism may be associated with the high pressure pump, but those shown in Figs. l and 4. to 6 are preferred. Referring to Figs. 1 to 5, a pair of concentrically arranged intertting sleeve members 'lil and i9 having abutting flanged heads are mounted'in the bore 5l between the shoulder and the upper lbored end of the nozzle member 3'? which may have a direct threaded connection with the threads 59, as shown in Fig. 5, or may, in the case of specially directed sprays, .have a leyed connection K with the member 33 be clamped with said sleeve members in assembled position by the sleeve nut 6I. The inner sleeve 'i8 has a flat seating face 85 spaced from a similar' face 8| on the outer sleeve. A discharge valve 32 seats on the face 8! and is urged thereagainst by a spring 83 mounted in the here 3@ of said nozzle, the stem 85 of said valve being slidably mounted in a bore 86 of the nozzle communicating at its lower end with the spray orifices 91, said stem either having external flats or provided with a fuel passage 8S as shown and normally being spaced above the lower end of the bore 86 to a height determined by the de-V sired lift of said valve. A light weight flat disk check valve 89 is mounted in the pocketJ 99 formed between its seat 90, the head of the loaded valve 82, and the sleeve 19, a projection 9i on the valve 82 determining the initial clearance between the valve 69 and its seat which is preferably only a few thousandths of an inch, so that said valve will be closed automatically either under the action of cylinder gases that might leak by the valve 82 or under the suction effect of the plunger 62 to insure complete filling of the pump chamber even if the loaded valve may be leaking but which will open readily during the delivery stroke of the pump to permit delivery of the fuel charge past the loaded valve 92 and through the passages associated therewith and the spray orifices 81. The check valve 9 may be formed from ground metal strip stock of five to fteen thousandths of an inch thick, and as shown in Fig. 6, it may have a seating layer 92 of neoprene or other fuel resistant synthetic rubber coating bonded thereto. The diameter of the check valve 99 is less than that of the pocket 99, so that fuel may readily pass around it.

Instead of a solid head discharge valve I may use a resilient metal disk valve 93 of five to fteen thousandths of an inch thick which is normally urged against its seat 8l by a spring pressed abutment 94 acted on by a spring 95 and having a shank 96 closely fitting the nozzle bore 86 and provided with flats 91 forming fuel passages which may be connected with spray passages such as 81 or terminate at their lower ends opposite an annular groove 98 in the nozzle which connects with the engine through V- shaped spray notches 99. The tension of the spring 95 is sufcient to initially tension or flex the valve 93, so that its central portion will be closely spaced from the check valve B9, or where said valve 89 is of resilient metal, it may even engage said valve to put it under a small amount of sealing tension, the fuel pressure from the pump serving to flex both of said valves to an open position accompanied, if desired, by a slight compression of the spring 95 and a longitudinal movement of the abutment 94.

Flat or substantially fiat faced valves of the type above described are of advantage in fuel pumps because they and their seats may be lapped separately and then assembled together.

Where the. cylinder head is quite deep, the cylinder i I and the piston `31 are made longer and to accommodate the extra length of said pieton the portion 5I of the inner sleeve 39 may be lengthened as shown in Fig. 7, and the anged head of the valve 18 extended to form a spacer cylinder H39 having a small centrally disposed fuel duct I9! therein. Also in this form the chamber 53 is disposed at the inner or lower end of the portion 5I, and the cylindrical portion 54 extends down to this chamber and is provided with the

slots

55 and 56, it being noted that since the exposed head of the piston 31 is its hottest part, if this head is adequately cooled, the whole piston will be kept at a temperature which will prevent deterioration of the spring 83 or

valves

82 or 93, and overheating of the barrel 52 which might cause sticking of the plunger 62. In Fig. 7 the form of spray nozzle shown in Fig. 5 is also shown associated with the valve 82 whose shank 96 forms a slidably movable pintle.

It is to be noted that since the member I0 is separate from the cylinder I I, withdrawal of the injector from the engine exposes the head 46, so that while holding this head with a wrench, the nozzle or its clamping nut may be loosened and the nozzle and valves removed from the piston 31 for inspection or replacement without the necessity of removing the piston 31 from its cylinder I I.

With the above construction, the initial loading of the spring 49 determines the time at which in the compression cycle of the engine the compression in the combustion chamber C will act upon the exposed area of the piston 31 to move the same outwardly, and this is usually a few degrees before the end of compression in a compression ignition engine. Immediately after the piston 31 starts to move, it is rapidly accelerated by the action of the gases on the full area of the piston, and as it moves upwardly, the plunger 62 laps the ports 63, and fuel introduced into the high pressure pump chamber through said ports is compressed therein until its pressure overcomes the compression pressure acting on valve 89 and the loading pressure acting on the

valve

92 or 93, and fuel then flows through the discharge passages to the

spray orifices

81 or 99 and is introduced into the engine cylinder. The angular position of the plunger 62 relative to the ports 63 determines the end of injection or the time at which the ports 63 passes the control surface '55 to by-pass the fuel into passage 56, and then as the piston 31 comes to the end of its stroke, it is cushioned by the fuel trapped in the chamber 12. After the firing stroke in the engine cylinder when the gases therein drop to .heir inlet pressure, the spring 41 returns the piston 31 to its inner position, thus causing a suction stroke of the high pressure pump. During the dwell period of the piston 31 or during the entire cycle as shown the fuel as a cooling iiuid is being continuously circulated from the inlet 2S through the chamber 53 and cylinder II and out through the return passage 35, and it is especially to be noted that this serves to cool the head t5 of the member 39 and the walls of the bore 51 housing the discharge valve mechanism and also the piston ring area of the sleeve member 38, which parts ordinarily have to rely on such cooling as can be obtained from the engine head jacket by conduction through the cylinder Ii. Some advantages of this two-part walled construction of the piston 31 can. be obtained the form herein shown by using the port as an inlet port and dispensing with inlet 26 and its ported connection with the interior of said piston, but the construction shown is'especially preferred.

Of the parts not particularly mentioned it will be understood that they are made of suitable metals suitably treated to perform their designated functions.

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 claims.

What I claim as my invention is:

1. In a fuel injector, the combination with a pump barrel having an inlet port, of a pump plunger movable in said barrel and controlling said port, a flanged sleeve member having a valve seat at the end of the sleeve, a loaded discharge valve normally seating on said seat, a second flanged sleeve member having its sleeve portion mounted within the sleeve of the rst named sleeve member and provided with a seat, a flat disk check valve seating on the seat of said second sleeve member and movable in a pocket formed between said seat and the loaded discharge valve, and means for clamping the flanges of said sleeve members together and in duidtight relation with said barrel.

2. In a fuel injector, the combination with a pump barrel having an inlet port, of a plunger movable in said barrel and controlling said port, a pair of interfltting sleeve members, each member having a valve seat at one end thereof, said seats arranged in juxtaposition, a loaded discharge valve cooperating with one of said seats and a ilat disk check valve confined in its movement by a part of said discharge valve and cooperating with the other one of said seats.

8. In a fuel injector, the combination of a cylinder, an operating piston movable in said cylinder in response to gases under compression, said operating piston including an outer sleeve and an inner sleeve having a head closing off the inner end of said outer sleeve, said sleeves being spaced apart adjacent said head to form a cooling chamber, said inner sleeve including a high pressure pump barrel provided with a fuel inlet port, means for circulating fuel through said cooling chamber and past said inlet port, a pump plunger working in said barrel and controlling said inlet port and iixed against longitudinal movement, a loaded discharge valve controlling the outlet of fuel from said barrel and disposed in that portion of said inner sleeve surrounded by said cooling chamber.

4. In a fuel injector, the combination of a cylinder, an operating piston movable in said cylinder in response to gases under compression, said operating piston including an outer sleeve and an inner sleeve having a head closing off the inner end of said outer sleeve, said sleeves being spaced apart adjacent said head to form a cooling chamber, said inner sleeve having a passage communicating with said chamber and having a pump barrel portion provided with a fuel inlet, a pump plunger working in said barrel and controlling said port and fixed against longitudinal movement, a loaded discharge valve controlling the outlet of fuel from said barrel and disposed in that portion of said inner sleeve surrounded by said cooling chamber.

5. In a fuel injector, the combination of a cylinder having a fuel inlet port, a cover for the outer end of said cylinder having a fuel outlet port, an operating piston movable in said cylinder in response to gases under compression, said operating piston including an outer sleeve having a fuel inlet port and an inner sleeve having a head closing ori the inner end of said outer sleeve, said sleeves being spaced apart adjacent said head to form a cooling' chamber, said inner sleeve having diametrically disposed passages communicating with said chamber, one of said passages connected with the port in the outer sleeve adapted to register with said fuel inlet port, the other of said passages connecting with the outer end of said cylinder, ymeans for supplying fuel to said inlet port, said inner sleeve having a pump barrel portion provided with a fuel inlet, a pump plunger working in said barrel and controlling said last named port and fixed against longitudinal movement, a loaded discharge valve conlll trolling the outlet of fuel from said barrel and disposed in that portion of the inner sleeve surrounded by said cooling chamber.

6. In a fuel injector, the combination of a cylinder, a cover for the outer end of said cylinder having an inwardly extending cylindrical portion spaced from the side Walls of said cylinder and cooperating therewith to form an annular chamber, said cover having a nat surface abutting the end of said cylinder and extending inwardly of the bore thereof to form a radially free self-centering fluid-tight sealed connection with said cylinder, an operating piston movable in said cylinder in response to gases under compression and having an annular outer end portion working in said annular chamber and acting on fuel coniined therein to arrest the outward movement of said piston, spring means for moving said piston inwardly, said piston having a high pressure pump barrel provided with a fuel inlet port, and a pump plunger iiXed against longitudinal movement Working in said barrel and controlling said port.

7. In a fuel injector, the combination of a cylinder, a cover for the outer end of said cylinder having a bore extending therethrough including a valve seat, a plunger rotator having a valve head portion seating on said seat, an operating piston movable in said cylinder in response to gases under compression and having a pump barrel provided with a fuel inlet port, a pump plunger working in said barrel and having an angularly adjustable control edge cooperating with said port to vary the amount of fuel delivered by said pump, a universal driving connection between said plunger and said rotator, a spring for returning said piston and acting on said plunger to hold it against longitudinal movement and the parts of said connection in assembled relation with said plunger and rotator and the head of said rotator in sealed relation with said cover.

8. l'n a fuel injector, the combination of a cylinder, a cover for the outer end of said cylinder having an inwardly extending cylindrical portion spaced from the side walls of said cylinder and cooperating therewith to form an annular chamber, said cover having a radially free self-centering duid-tight sealed connection with said cylinder, an operating piston movable in said cylinder in response to gases under compression and having an outer end portion working in said annular chamber and acting on fuel confined therein to arrestthe outward movement of said piston, said operating piston having a pump barrel provided with a fuel inlet port, a pump plunger working in said barrel and having an angularly adjustable control edge cooperating with said port to vary the amount of fuel delivered by said pump, a plunger rotator mounted in said cover, a driving connection between said rotator and said plunger accommodating for any eccentricity of said plunger relative to said rotator, and a spring for returning said piston and holding said plunger, said rotator and said driving connection in assembled relation.

9. In a fuel injector for internal combustion engines, the combination with a housing provided with a bore communicating with the combustion chamber of the engine and cooling fluid passages communicating with said bore and with an exterior supply of cooling fluid, of an injector operating piston movable in said bore in response to compression pressure, a fuel metering pump including a barrel carried by said piston, a sprayer including a pump discharge valve mounted in said piston, and means for circulating a cooling fluid from said external source of supply through said passages and within said piston about parts of said valve in any position of the piston in said bore.

10. In a fuel injector, the combination of a cylinder, an operating piston movable in said cylinder in response to compression pressure, said operating piston including an outer sleeve and an inner sleeve forming a pump barrel and provided with a fuel inlet port, a pump plunger working in said barrel and controlling said inlet port and fixed against longitudinal movement, a sprayer including a pump discharge valve mounted in said piston, and means including passages between said piston and said cylinder and between said outer and inner sleeves for circulating a cooling fluid from an external source of supply through said passages and Within said piston about parts of said valve in any position of the piston in said cylinder.

11. In a fuel injection apparatus for internal combustion engines, the combination with a casing provided with a bore communicating with the combustion chamber of the engine, of an injector operating piston movable in said bore in response to compression pressure, a fuel pump including a part moved by said piston, said piston formed to provide a cooling space between the ends thereof, and means for continuously circulating a cooling fluid from an external source of supply through said cooling space and portions of said bore in any position of the piston in said bore.

12. In a fuel injector for internal combustion engines, the combination with a casing provided with a bore communicating with the` combustion chamber of the engine, of an injector operating piston movable in said bore in response to compression pressure, a fuel pump including a barrel carried by said piston, a sprayer including a pump discharge valve mounted in said piston, said piston formed to provide a cooling space surrounding parts of said valve, and means for supplying coolant to said cooling space.

13. In a fuel injection apparatus for internal combustion engines, the combination with a casing provided with a bore communieating with the combustion chamber of the engine, of an injector operating piston movable in said bore in response to compression pressure and having a ring sealed portion, a fuel pump including a part moved by said piston, said piston formed to provide an inner cooling space for the ring sealed portion thereof communicating with said bore, and means for supplying a coolant to said bore and said cooling space.

14. In a fuel injector for internal combustion engines, the combination with a casing provided with a bore communicating with the combustion chamber of the engine, of an injector operating piston movable in said bore in response to cornpression pressure and having a ring sealed portion at the head end thereof provided with an inner cooling space for the rings and head of said piston, a fuel pump including a part moved by said piston, and means for supplying a coolant to said bore, said bore being in constant cornmunication with said cooling space.

LOUIS O. FRENCH.

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

UNITED STATES PATENTS Number Name lDate 1,749,975 Groff Mar. 11, 1930 2,007,871 Oldham July 9, 1935 2,109,785 Starr Mar. 1, 1938 2,110,314 Wisner Mar. 8, 1938 2,173,813 Bischof Sept. 19, 1939 2,378,165 Waeber June 12, 1945 2,408,288 Bremser Sept. 24, 1946