US2799535A - Fuel injection apparatus - Google Patents

Description

United States Patent The invention relates to fuel injection apparatus for internal combustion engines and more particularly to compression pressure operated fuel pumps.

One object of this'invention is'to provide a compression pressure operated pump having a timing valve which is concentrically disposed relative to the operating piston,

thereby simplifying the construction of the housing and facilitating the adjustable-loading of the valve. I

A further object of the invention is to associate the above mentioned timing valve with a valve controlling the discharge of fuel from the pump chamber, these valves preferably being loaded by a common spring means which may also act to return the piston.

A further object of the invention is to provide a fuel pump having a metering by-pass and a differential pressure operated discharge valve normally closed by a spring and hydraulic means for biasing said valve to closedp'osition when said by-pass is operative. 1

This application is a continuation in part of my application Serial No. 528,165, filed August 15, 1955, for Fuel Injection Apparatus, now abandoned.

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. l is a vertical sectional view through a'fuel pump embodying the invention;

Fig. 2 is a detailed horizontal sectional view taken on the line 22 of Fig. l;

Fig. 3 is a side elevationview of the timing valve shown in Fig. 1;

Fig. 4 is a side elevation view of the discharge valve shown in Fig. l;

Fig. 5 is a vertical sectional view similarto Fig. 1, showing a modification;

Fig.6 is a vertical sectional view similar to Fig. 1, showing another modification, parts being broken away;

Fig. 7 is a detailed vertical sectional view taken on the line 77 of Fig. 6, parts being broken away.

Referring to the drawings, the numeral 8 designates a portion of the cylinder or head of an internal combustion engine having concentric bores 9 and 10 and a cooling jacket space 11. a

A housing or cylinder 12 has its lower end mounted in bore 9 and held therein in anysuitable manner. Housing 12 has differential diameter concentric bores 13 and 14, a fuel inlet 15, a fuel outlet 16, a counterbore 17, and a threaded upper end 18. p

An operating piston has a head part 19 working in the bore 13 and a plunger part 20 working in the bore 14, these parts cooperating to form a coolant, checking, timing, andsealing chamber 21. The piston has a through bore 22 threaded at its head end to take a cap member 23 that has a valve seat 24 and a discharge passage 25 that may terminate in spray orifices 26 though other forms of spray nozzles may be used. The head part carries sealing rings 27. 7 7 7 g The plunger part 20 has a fuel inlet and spill port 28,

a groove 29 connecting this port and also chamber 21 with an annular groove 30, a groove 31 connected with a port 32, and a port 33. The piston is suitably slidably keyed against rotation, the part 20 having a keyway 34 slidably engaged by a key 34A.

A pump plunger 35 works in the bore 22 and is held against longitudinal movement by the rotatable mounting of its flange 36 in a pocket provided by the counterbo-re 17 and a flanged nut 37. At its upper end it carries an arm 38 operable either manually or by governor or by both to angularly adjust it so that the position of its metering scroll including the control edge 39 may be varied relative to the port 28 to thereby vary the amount of fuel by-passed from the pump chamber 40 as the operating piston moves outwardly on its injection stroke. 7 The plunger 35 has a through bore 41, a segmental recess 42 connected by a restricted orifice 43 with said bore, and a segmental recess 44 connected by a restricted outlet 45 with said bore.

A piston valve 46 is a cylindrical member working in the bore 41 and controls the passage of checking and sealing liquid from chamber 21 via groove 31, port 32, recess 42, orifice 43, bore 41 to the outlet 45.

A discharge valve 48 of the differential needle type has a reduced diameter head end 47 seating on the seat 24 and has a cylindrical portion working in the bore 41 and a reduced diameter outer end portion 49 abutting the lower face or head of the valve 46, see Fig. 4. As a result, it is not necessary to center the valve 48 relative to the valve 46.

Both valves 46 and 48 are normally closed by a spring 50 interposed between the top of the valve 43 and a tension adjusting screw 51 loose in the bore 41 and having threaded engagement with an extension 52 of the nut 37. The spring 50, acting through both valves as a thrust member, effects the return stroke of the operating piston. The plunger 35 is free to be rotated relative to the valves 46 and 48. It is to be noted that instead of providing a reduced diameter head on the valve 48, the inner end of the valve 46 may be of reduced diameter and the reduced diameter portion abut the outer end of the then full diameter outer end of valve 46 without departing from the invention and to produce the same effect. A separate spring for returning the plunger can also be used, if desired.

I In Fig l' the parts are shown in their initial position. In this position cooled fuel from a circulatory supply system passes from the fuel inlet 15 via the annular groove 30 to the outlet 16, and some of this fuel passes from the groove 30 via the groove 29 to the chamber 21 and through the port 28 to the pump chamber to fill these chambers. During the compression stroke when the compression pressure is sufiicient to overcome the initial loading of the spring 50, the operating piston and the valves 46 and 48 are moved outwardly until the port 28 and groove 29 are lapped by the housing and the port 28 lapped by the plunger 35, thereby trapping fuel in the chambers 21 and 40. While so trapped, since the combined areas of chambers 21 and 40 are less than the area of the exposed front face of the piston, the pressure of the sealing and checking liquid in chamber 21 will be greater per unit area than that of the gases acting on the front end of the piston and thus prevent gas leakage by the piston should the rings 27 fail to prevent this leakage. This movement also brings the port 32 into full register with the recess 42 so that chamber 21 is then hydraulically connected with the annular space in the bore 41 formed by the head 49 of the valve 48 while the port 45 is still lapped by valve 46. As the compression pressure increases, liquid pressure builds up in the chamber 21 and against the exposed differential area of valve 46 and differential area of head 47 of the valve 48 until near the end of the compression stroke the loading of spring 50 is overcome by the pressures acting on the valve 46, it being noted, however, that pressure in the chamber 21 is acting on the differential area of the outer end 49 of the valve 48 so that the pressure in chamber 40 necessary to open the valve 48 will be greater than that in chamber 21. As soon as the valve 46 uncovers the port 45 sealing liquid in chamber 21 can pass via groove 31, port 32, recess 43, annular space between the valves 46 and 48, port 45, recess 44, port 33, grooves 29 and 38 to port 16 so that the operating piston is free to move outwardly on its injection stroke and then since the pressure in the chamber 21 has been reduced, the pressure in chamber 40 acting on head end 47 of the valve 48 opens this valve and keeps the valve 48 open and at the same time allows it to move with the valve 46. On opening of valve 48 fuel is discharged through the passage 25 and the nozzle 26 into the combustion chamber C of the engine. Depending upon the angular adjustment of the control edge 39, sooner or later the port 28 overruns this edge to connect the pump chamber 48 via port 28 and groove 29 with the groove 30 so that pressure in the pump chamber drops, permitting the spring 59 to move the valves 46 and 48 inwardly until the valve 48 seats while the valve 46 is still uncovering the port 45, and under these conditions the fuel pressure in chamber 21 is acting on the upper end of the valve 48 to hold it closed while both valves continue to move with the operating piston until the groove 31 is lapped by the housing and further movement of the piston stopped by the sealing liquid then trapped in the chamber 21. During the movement of the piston the orifice 43 permits the maintaining of a greater per unit pressure of sealing fluid in the chamber 21 than that of the gases acting on the exposed front end of the piston to seal against gas leakage. As soon as the piston comes to rest during the high pressure period of the engines cycle following injection, the pressure of liquid in the chamber 21 is obviously greater than that acting on the front face of the piston. When during the engines cycle, the pressure in the engine cylinder has dropped sufficiently, the spring 59 acting through the valves returns the piston to its initial position ready to repeat the cycle. Varying the loading of the spring 50 by the adjustment of the screw 51 varies the time of beginning injection. Under no load adjustment of the plunger 36 no pressures exist in the chamber 40 suflicient to open the valve so that the valve 48 due to the pressure of the spring and also fluid pressure on its upper end from chamber 21 remains on its seat and also in contact with the valve 46 which is only moved to its open position when the pressures in the chamber 21 acting through the passages previously described on the head end of the valve 46 reach a value sufiicient to overcome the loading of the spring 5%) and move the valve 46 to connect the chamber 21 to the then open orifice 45, and when this occurs, the piston with the valve 48 moves outwardly to its stop position while the valve 46 is held in its closed position, the timing of this no load movement being of no consequence since no fuel is being delivered to the combustion chamber. Since the differential surfaces of the valves 46 and 48 are of small area, it is not necessary to use a heavy spring to load these valves to secure the desired operation of the operating piston.

It is to be noted that since the loading of the spring 50 builds up during the stroke of the operating piston, the pressure of the injected fuel will increase with the amount of fuel injected since the loading on the discharge valve 48 increases as the effective stroke of the operating piston increases.

The construction shown in Fig. 1 has certain distinct advantages since pressure built up in the chamber 21 acts to hydraulically load the valve 48 to bias it to a closed position, for any given spring loading of this valve to closed position the pressures developed in the pump chamber 40 will be higher or for any predetermined pump pressure in the chamber 40 the spring load may be lower than where spring pressure alone is relied upon to close said valve. Also the hydraulic pressures acting to close the valve 48 will insure its prompt closing as soon as the pump by-pass becomes eflective, the diflerential area at the outer end of the valve being greater than the seating area of the passage 25 so that these closing pressures are greater than any counterpressure acting through the discharge passage 25 on the valve 48.

The mounting of the timing valve in the plunger 35 has advantages whether .or not this valve is associated with the fuel discharge valve since it eliminates the drilling of valve passages in the housing and the mounting of the valve in an eccentric relation therewith and thereby simplifies the construction of the housing, saves material, and simplifies remote control connections with the screw 51 where such are used. In this connection I have shown in Fig. 5 a construction similar to Fig. 1 except that the timing valve 46A and the discharge valve 48A are separately loaded by springs 50A and 50B and the operating piston is returned by a separate spring 50C. The housing 12A is similar to the housing 12 so that similar parts have been similarly numeralled. The operating piston is similar to that of Fig. 1 and has been similarly numeralled and is suitably keyed against rotation.

The angularly adjustable plunger 35A has its flange 36A mounted for rotation between the nut 37A and a flanged washer 53 clamped in the recess 17A by said nut. The bore 22A extending part way through plunger 35A has a valve seat 54 at its end connected by an angled passage including port 43A with a-segmental recess 42A. Above the seat a port 45A connects with a segmental recess 44A. The spring 50A is interposed between the valve 46A and the screw 51A for adjustably loading the same.

The discharge valve 48A is normally seated by the spring 50B against an apertured seat member 55 clamped in position at the lower end of bore 22 by a member 56 having threaded engagement with the head 19 of the operating piston and housing the valve and its spring and provided with a discharge passage 25A connected with spray orifices 26A.

The action of this modified form of device is similar to that of Fig. 1 except that in this instance the pressure of sealing fluid in chamber 21 acts only on the valve 46A to open the same against the preloaded adjustment of the spring 50A to permit the operating piston to move outwardly near the, end of the compression stroke .of the engine to force fuel from the pump chamber past the valve 48A and through the passage 25A and the spray orifices 26A into the combustion chamberC, the spring SitC'acting to return the operating piston to its initial position.

Where the fuel to be injected is a volatile fuel, such as gasoline, the supply of fuel to the pump chamber is separate from the supply of coolant, checking, and sealing liquid to the checking and sealing chamber, and Figs. 6 and 7 show a modification to accomplish this. In this form the housing 128 is identical with the housing 12 except that a separate low pressure fuel supply inlet 57 is provided, the inlet 15A and outlet 16A being connected with a suitable circulatory cooled lubricant supply system, said housinghaving the differential diameter bores 13A and 14A.

The operating piston is identical to that of Fig. 1 except that the fuel inlet and spill port 28A connects only with the groove 29A that registers with the fuel inlet 57. The supply of lubricant or sealing liquid to the checking and sealing chamber 21A is through diametrically disposed grooves 29B, similar to the groove 29, and connecting with the annular groove 30A. Release of liquid from the chamber 21A is by Way of a groove 31A to port 32A. The piston has the through bore 228 closed at its lower end by the member 23A identical with member 23 having a valve seat 24A, discharge passage 25B, and orifices 26B.

The plunger 35B is similar to plunger 35, except I have shown this plunger provided with diiferential diameter bores 58 and 59 in which the abutting valves 46B and 48B are slidably mounted. Plunger 35B has the metering scroll including control edge 39A, ports 43B and 45B, segmental recesses 42B and 44B communicating respectively with said ports. The port 433 connects with the lower end of the bore 58 and the port 45B is located above the lower end of the valve 463 so that after the preliminary movement of the piston causing lapping of the grooves 29B by the housing to seal off the chamber 21A, the valve 46B will still have to'be moved through pressure developed in chamber 21A before it uncovers the port 45B to permit movement of the operating piston on its injection.

The upper portion of the structure of Fig. 6 is identical with that of Fig. 1 so has been omitted, the loading spring 50D being similar to the spring 50. This structure operates in the same way as that of Fig. 1 except that in this instance the valve 48B is not acted upon through a differential pressure area such as provided by the head 49 of the valve 48. The valve 46B is a plain cylindrical piston valve while valve 48B is a needle valve with a plain cylindrical shank long enough to bring the lower face of the valve 46B above the bottom of the bore 58.

The valves 46B and 48B may be made as a one piece unit, but the construction shown in Fig. 6 is preferred as it eliminates one concentric fit. The form shown in Fig. 1 is the preferred form as it eliminates concentric bores in the plunger and has the additional advantages previously pointed out.

Instead of direct manual control of the screw 51 or 51A, this screw may be turned by a rack and pinion connection with an actuator either manually or governor controlled, such connections being well known for angularly shifting the metering plunger of a fuel pump.

Reference is here made to my copending application Ser. No. 470,978, filed November 24, 1954, for Fuel Injection Apparatus, 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 except in so far as such limitations are included in the claims.

What I claim as my invention is:

1. In a fuel injection apparatus for internal combustion engines, the combination of a housing, an operating piston movable in said housing in response to gases under compression, said housing and piston formed to provide a sealing and checking chamber adapted to contain a sealing and checking liquid, means for supplying said chamber with said liquid, a fuel pump having relatively movable parts including a hollow plunger forming a part of said piston and a plunger mounted in said hollow plunger, means including a hydraulically operated timing valve mounted in said last named plunger for controlling the release of liquid from said chamber and adapted to be opened during the compression stroke of the engine by pressure built up in said checking and sealing chamber to permit movement of said piston on its injection stroke, and means for adjustably loading said valve to a closed position.

2. Fuel injection apparatus as defined in claim 1, wherein the fuel pump plunger is mounted in said hollow plunger for angular movement relative thereto and is provided with a by-pass control edge cooperating with a port in said hollow plunger to vary the amount of fuel delivered by the pump.

3. In a fuel injection apparatus for internal combustion engines, the combination of a cylinder, an operating piston movable in said cylinder and having a head end exposed to gases under compression and a hollow plunger portion cooperating with said cylinder to provide a check- '6 ing and sealing chamber adapted to contain a checking and sealing liquid, means for supplying said chamber with said liquid, a fuel pump plunger mounted in said hollow plunger, the head end of said piston having a fuel discharge passage, a hydraulically operated timing valve mounted in said fuel pump plunger for controlling the release of liquid from said chamber and adapted to be opened during the compression stroke of the engine by pressure built up in said sealing and checking chamber to permit movement of said piston on its injection stroke, a discharge valve controlling said discharge passage and extending into said fuel pump plunger into abutting engagement with said timing valve, and spring means for loading said valves.

4. Fuel injection apparatus as defined in claim 3, wherein said spring means acting through said valves also acts to return the operating piston.

5. In a fuel injection apparatus for internal combustion engines, the combination of a cylinder, an operating piston movable in said cylinder and having a head end exposed to gases under compression and a hollow plunger portion cooperating with said cylinder to provide a checking and sealing chamber adapted to contain a checking and sealing liquid, means for supplying said chamber with said liquid, a fuel pump plunger mounted in said hollow plunger and having a bore axially alined therewith, the head end of said piston having a fuel discharge passage, a hydraulically operated timing valve mounted in said bore, porting means operatively connecting said chamber with said bore to conduct liquid from said chamber to the head end of said valve to act to open the same, porting means adapted to be uncovered by said valve to release liquid from said chamber to allow movement of said operating piston, a fuel discharge valve of the differential needle type controlling said discharge passage and having its shank extending into said bore into abutting engagement with the head end of said timing valve, the head end of said timing valve and the abutting end of said discharge valve formed to provide a differential surface area for said timing valve, and spring means for loading said valves.

6. Fuel injection apparatus as defined in claim 5, wherein the differential area of the seating end of said discharge valve is greater than the differential area formed between the abutting end portions of said timing valve and discharge valve.

7. In a fuel injection apparatus for internal combustion engines, the combination of a cylinder, an operating piston movable in said cylinder and having a head end exposed to gases under compression and a hollow plunger portion cooperating with said cylinder to provide a checking and sealing chamber adapted to contain a checking and sealing liquid, means for supplying said chamber with said liquid, a fuel pump plunger mounted in said hollow plunger and having a bore axially alined therewith, the head end of said piston having a fuel discharge passage, a timing valve mounted in said bore, porting means operatively connecting said chamber with said bore to conduct liquid from said chamber to the head end of said valve, porting means adapted to be uncovered by said valve to release liquid from said chamber to allow movement of said operating piston, a fuel discharge valve of the difierential needle type controlling said discharge passage and having its shank extending into said bore in abutting engagement with the head end of said timing valve, the shanks of said valves being of the same diameter and the head end of said timing valve and the abutting end of said discharge valve formed to provide a differential area for the timing valve and the abutting end of said discharge valve, and spring means for initially loading said valves to a closed position.

8. In a fuel pump having a pump chamber and a metering by-pass leading therefrom, the combination of a discharge passage for said pump, a difierential pressure operated needle valve controlling said passage, spring means normally biasing said valve to closed position, and a source of liquid under a pressure greater than that of the fuel in said pump chamber, for biasing said valve to closed position, when said by-pass is operative.

References Cited in the file of this patent UNITED STATES PATENTS Tuscher Nov. 8, 1938 French July 25, 1950 French July 25, 1950 Dickson et a1 Sept. 25, 1951 Paluch et a1. Apr. 3, 1956 FOREIGN PATENTS 'Great 'Britain June 24, 1953

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