US3036565A

US3036565A - Fuel supply apparatus

Info

Publication number: US3036565A
Application number: US7679A
Authority: US
Inventors: Neville M Reiners
Original assignee: Cummins Engine Co Inc
Current assignee: Cummins Inc
Priority date: 1960-02-09
Filing date: 1960-02-09
Publication date: 1962-05-29
Anticipated expiration: 1979-05-29

Description

May 29, 1962 N. M. REINERS FUEL SUPPLY APPARATUS 2 Sheets-Sheec 1 Filed Feb. 9, 1960 INVENTOR. 1y ez llame 72ers,

May 29, 1962 N. M. REINERS FUEL. SUPPLY APPARATUS 2 Sheets-Sheet 2 Filed Feb. 9, 1960 ]NVE N TOR. emllefl ianera, BY

United States Patent Ofilice 3,036,565 Patented May 29, 1962 3,035,565 FUEL SUPPLY APPARATUS Neville M. Rainer-s, Columbus, Ind., assignor to Cummins Engine Company, Inc, Columbus, Ind, 21 corporation of Indiana Filed Feb. 9, 1960, Ser. No. 7,679

19 (Ilaims. (61. 123139) This invention relates generally to a fuel supply apparatus for an internal combustion engine.

The general object of the invention is to provide novel fuel supply apparatus for an internal combustion engine, which has superior fuel control and metering characteristics.

Another object is to provide an improved fuel supply apparatus for delivering accurately metered quantities of fuel to an internal combustion engine and having a long life under varying operating conditions.

A further object is to provide a novel fuel injector for an internal combustion engine, which may be easily and accurately calibrated for use in a set, both initially and after it has been in use.

A more specific object is to provide a novel fuel in jector for an internal combustion engine, which is less subject to the effects of changes in the flow characteristics in the injector, resulting from use.

Still another object is to provide a novel fuel injector for an internal combustion engine, which permits accurate and rapid compensation in the field for changes resulting from use.

Other objects and advantages of the invention will become apparent from the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a diagrammatic View of a fuel supply apparains for a multi-cylinder engine of the diesel type, embodying the features of the invention;

FIG. 2 is a top plan view, with portions in section, of one of the injectors employed in the apparatus shown in FIG. 1;

FIG. 3 is an enlarged sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is an enlarged end view of a part of the injector shown in FIG. 2;

FIG. 5 is a sectional view taken along the line S5 of FIG. 4;

FIG. 6 is an enlarged fragmentary top plan view similar to FIG. 2 but showing a modified form of fuel injector; and

FIG. 7 is a fragmentary sectional view taken along the line 7-7 of FIG. 6.

The present invention relates to fuel supply apparatus similar to that disclosed in my prior Patent No. 2,727,498, issued December 20, 1955. The fuel supply system disclosed in that patent comprises a plurality of injectors for injecting fuel into the respective engine cylinders, a supply rail for supplying fuel to the injectors, and a return rail connected to the injectors for returning fuel to the fuel tank. Fuel is supplied to the supply rail by an enginedriven pump, and the pressure of the fuel in the supply rail is controlled by the delivery of the pump and a pressure regulator which by-passes some of the fuel back to the intake side of the pump. In the line connecting the pump with the supply rail there is also a manually operable throttle and a governor operated valve for controlling the flow of fuel to the engine at idle speed and for shutting off the flow of fuel to the engine when the engine reaches a predetermined maximum speed.

Each injector, shown in the prior patent, has a passage extending therethrough, which at one end is connected to the supply rail and at the other end to the return rail. The passage comprises a supply portion, a return portion, and

istics of the orifice can be compensated for.

an intermediate portion connecting the supply and return portions. The intermediate portion is located adjacent the nozzle of the injector. Extending from the intermediate portion is a metering orifice for metering fuel into a chamber in the nozzle. The metered fuel is discharged from the chamber through the nozzle by a plunger which also opens and closes the metering orifice. Fuel is circulated through the passage in the injector continuous- 1y while the metering orifice is open, and the flow through the metering orifice is determined by the pressure of the fuel applied to the metering orifice and hence by the pressure in the intermediate portion. While fuel could be circulated through each injector during the entire period of operation of the engine, such circulation is preferably stopped shortly after the metering orifice is closed and is reestablished shortly before the metering orifice is Opened so as to purge the injector passage of any air. The return portion of the injector passage also includes a restriction to flow therein so as to maintain the fuel in the intermediate portion under pressure.

The present invention provides means for facilitating the balancing of all injectors for one engine so that equal quantities of fuel are injected into the respective cylinders. The present invention also provides an injector structure which is less affected by changes in the flow characteristics of the metering orifice. The quantity of fuel supplied to each cylinder is determined by the flow characteristics of the metering orifice and the pressure of the fuel applied thereto. If such flow characteristics vary due to erosion of the orifice, particularly at the entrance and exit, or to obstruction from carbon deposit, the quantity of fuel flowin g therethrough will vary. The present invention provides means for varying the pressure inside the injector at the metering orifice, so that variations in the flow character- It also provides compensation for other flow varying factors such as plunger clearance, production tolerances, etc.

To accomplish the foregoing, flow balancing means is provided in the fuelconduit for each injector, either upstream from the metering orifice or downstream therefrom, or both. Such flow balancing means preferably is in the form of a plug having a restrictive orifice therethrough. While a plug of this character may be placed in the line connecting the supply portion of the injector passage to the supply rail, or in the line connecting the return portion of the injector passage to the return rail, or in both, such plugs are preferably placed directly in the supply and return portions of the injector passage at the outer ends thereof where they can be readily inserted and replaced. The plug in the supply portion of the injector passage reduces the pressure internally within the injector. This makes it possible to have different pressures at the metering orifices of the respective injectors with a common rail pressure, by varying the orifices in the plugs for the respective injectors to compensate for variations in metering orifice characteristics. This also permits the use of larger metering orifices Without decreasing the external rail pressure. Consequently, for a given carbon deposit in the metering orifice, the percentage change in effective area will be less than with a smaller orifice and the eifect on the flow of fuel therethrough will be correspondingly less.

Such a plug on the downstream side controls pressure within the injector and controls total fiow through the injector. Thus, such a plug can be used to balance and equalize total flow to give better calibration of the fuel system as a whole. With such plugs both upstream and downstream from the metering orifice, all of these advantages can be obtained. Moreover, the plug may be made in a form which provides for ready adjustment of the effective size of the orifice therethrough.

In the drawings, FIG. 1 shows a fuel supply system comprising an engine-driven pump 11 for delivering fuel to the engine. Fuel is drawn by the pump from a tank 12 through a line 13 and is delivered through a line 14, the pressure of the fuel in the line 14 being controlled by a pressure regulator 15 connected to the line 14. The pressure regulator 15 is adapted to by-pass a portion of the fuel delivered by the pump 12 and thus cooperates with the pump to provide a predetermined variation in the pressure of the fuel to be delivered to the engine. The pressure regulator 13 is preferably of the character shown in my prior Patent No. 2,820,473 issued January 21, 1958.

Beyond the pressure regulator 15 the fuel is conducted to a manually operable throttle 16 movable between two positions, namely, an idling position and a full open position. The flow of fuel to the engine is also controlled by a governor-operated valve 17, the latter being adapted to be actuated by a governor 20 driven in timed relation with the engine. The governor operated valve 17 is adapted to control the flow of fuel when the engine is idling and to shut oif the flow of fuel to the engine when the engine reaches a predetermined maximum speed. From the governor-operated valve 17, fuel flows through a line 21 to a common supply rail or header 22. The latter is connected by branch lines 23 to a plurality of injectors 24, one for each cylinder. Each injector is provided with a passage therethrough connected at one end to a branch line 23 and at its other end to a branch line 26 connected to a common return rail 27, the latter being connected to the tank 12 by a line 28. The two

branch lines

23 and 26 and the passage through each injector comprises conduit means of the present fuel supply apparatus.

In FIGS. 25, inclusive, one of the fuel injectors 24 is illustrated, the latter including the flow balancing feature of the present invention. The injector 24 comprises an elongated, tapered injector body 31 having a head portion 32 formed integrally therewith at its upper end. The injector body 31 is also provided with a central longitudinally extending bore 33 therethrough for receiving an engine-operated reciprocable injector plunger 34.

Each injector has a fuel passage extending therethrough, which comprises a supply portion connected to the supply rail 22, a return portion connected to the return rail 27, and an intermediate portion connecting the supply and return portions. The supply portion comprises a longitudinal passage 35 in the injector body 31 adjacent the bore 33. The upper end of the passage 35 connects with a radial passage 36 in the head portion 32. The outer end of the passage 36 is enlarged and threaded as at 37 to receive a fitting (not shown) connecting the passage with one of the branch supply lines 23. The longitudinal passage 35 is adapted to be closed during part of the engine cycle, preferably by means including the injector plunger '34. To this end, the lower end of the longitudinal passage 35 connects with a transverse passage 40' extending into the plunger bore 34. Below the passage 40 is another similar transverse passage 41 extending from the plunger bore 34. The plunger 34 has a portion 42 of reduced diameter which, during a portion of the engine cycle, is aligned with the

transverse passages

40 and 41 to permit flow from one to the other. Extending downwardly from the lower transverse passage 41 is a passage 43 which constitutes in effect a continuation of the longitudinal passage 35.

The intermediate portion of the passage through the injection comprises an annular passage 44 at the lower end of the injector body 31 connected to the passage 43. The annular intermediate passage 44 is preferably formed between the lower end of the injector body 31 and a conical nozzle member 45 secured to the lower end of the injector body.

The return portion of the passage through the injector comprises a passage 46 extending upwardly from the annular passage 44 and angularly spaced from the passage 43. At its upper end, the passage 46 has a restriction 47 for maintaining pressure in the annular passage 44. Extending upwardly from the restriction 47 is a longitudinal passage 50 connected at its upper end to a radial passage 51. The outer end of the radial passage 51 is enlarged and threaded as at 52 to receive a fitting (not shown) connecting the passage with one of the branch return lines 26.

Fuel is injected into the engine cylinder through the nozzle member 45. To this end, the nozzle member is in the form of a cup having a chamber 53 forming a continuation of the plunger bore 33. The nozzle member is provided with a plurality of small nozzle openings 54 extending from the chamber 53. Fuel supplied to the chamber 53 is forced therefrom by the plunger 34 through the nozzle openings 54, the plunger 34 being reciprocable in timed relation with the engine as by a rocker arm and cam. The plunger 34 has a stroke such that the volume of the chamber 53 is reduced to zero, when the plunger is at the bottom of its stroke, to force all of the fuel from the chamber into the cylinder.

In order to provide a predetermined quantity of fuel for each injection stroke of the plunger 34, a metered quantity of fuel is supplied to the chamber 53 when the plunger 34 is raised from its lowermost position. For this purpose, a metering orifice 55 is provided, which extends from the annular passage 44 to the chamber 53. The metering orifice 55 is adapted to be opened and closed by the reciprocation of the plunger 34. Thus, when the metering orifice 55 is open, the quantity of fuel flowing therethrough to the chamber 53 is determined by the pressure of the fuel in the annular passage 44. Since, when the metering orifice 55 is open, the annular passage 44 should be free of any air, a flow of fuel through the passages in the injector is established prior to the time when the metering orifice 55 is opened and is cut off after the metering orifice is closed. To this end, the reduced portion 42 on the plunger 34 is so positioned that communication is established between the transverse passages 40 and 4-1 prior to the opening of the metering orifice 55, and the plunger 34 cuts off communication between the

transverse passages

40 and 41 after the metering orifice 55 is closed by the plunger 34.

With an injector of the foregoing character, it is do sirable to provide means which permits easy and accurate calibration with other injectors of a particular set to compensate for various flow varying factors such as production tolerances and wear. Moreover, it is desirable to maintain the fuel pressure in the supply rail at a value common to all injectors and sufiiciently high for proper idling, and the fuel pressures within the injectors at values varying with the characteristics of the respective metering orifices.

The fuel injector 24 includes means for accomplishing the foregoing in a form of pressure balancing means controlling the flow of fuel through the injector and preferably interposed in the fuel passage in each injector so as to compensate for flow varying factors at the metering orifice and thereby maintain a better control of the quantity of fuel entering the chamber of the injector. The flow balancing means is adjustable either by replacement or by having an adjustable portion.

As heretofore mentioned, the flow balancing means may be placed either in the supply portion of the fuel passage in the injector, or in the return portion, or in both. With the flow balancing means in the supply portion, the pressure of the fuel within the injector is reduced. Consequently, in order to compensate for differences in injectors, it is possible to have .a common supply rail pressure with different pressures in the respective injectors at the metering orifices thereof. Thus, variations in effective metering orifice size due to production tolerances or wear can be compensated for, with the result that all injectors in an engine will deliver equal charges of fuel. The flow balancing means can be used to compensate for other factors such as changes in plunger clearance due to wear and changes in orifice entrance and exit coefiicients. The flow balancing means is also helpful in compensating for carbon deposit. Thus, with the flow balancing means in the supply portion and a reduced fuel pressure .applied to the metering orifice, the metering orifice is made larger so that for a given thickness of carbon deposit therein, the percentage change in the elfective area of the orifice will be less. With a flow balancing means in the return portion, the pressure internally of the injector can be varied but more importantly, the total fiow through the injector can be controlled. Consequently, such a flow balancing means can be used to balance and equalize total flow, making possible accurate calibration of the fuel pump relative to the injectors. With flow balancing means in both the supply and return portions, all of these advantages are obtained.

In FIGS. 2 and 3, the pressure balancing means of the present invention is shown as comprising a member preferably in the form of an externally threaded plug 56 having an axial bore 57 therethrough defining an orifice. One end of the plug member 56 may be chamfered at 60 to seat against a shoulder in the body 31 to assure a fluid tight engagement with the shoulder. In order to facilitate the removal or replacement of the plug 56, the bore 57 is provided with a hexagonal socket 61.

In the preferred embodiment of the invention, flow balancing means is provided in both the supply and return portions, the flow balancing means comprising one of the plugs 56 threaded into the outer end of the radial passage 36, and another of the plugs 56 threaded into the outer end of the radial passage 51. The two plugs in the injector will have axial bores 57 therethrough of such size as to provide proper pressures within the injector for its metering orifice and to provide for proper flow characteristics for the system as a whole. Thus, when an engine is initially put into service, control of the fuel may be readily calibrated. In use, when wear or other changes in the flow characteristics occur, plugs 56 with different bores 57 may be substituted for the initially installed plugs. This permits compensation in the field without the necessity of returning the injectors to the factory.

In FIGS. 6 and 7, a modified construction of the pressure balancing means is illustrated, the latter being adjustable. In this instance, the pressure balancing means, indicated at 70, comprises a cylindrical cup-shaped member 71 adapted to be placed in a bore 72 in the head portion 32, the bore 72 intersecting either of the

radial passages

36 or 51, in this instance, the radial passage 36. The member 71 is provided with a transverse opening 73 therethrough aligned with the radial passage 36. Mounted in the member 71 is an element in the form of a plunger 74 which is movable Within the member 711 to vary the effective size of the transverse opening 73. To effect adjustment of the plunger 74, a coil spring 75 is interposed between the inner end of the plunger 74 and the base of the cup member 71 to urge the plunger outwardly of the cup member. To move the plunger 74 against the pressure of the spring, manually operable means is provided, which in the present instance comprises a screw 76 threaded in a bore 77 extending transversely to the bore 72. The screw 7 6 has a tapered portion 80' which engages the end of the plunger 74 and preferably has a pilot portion 81 on its end. With the foregoing construction, it will be apparent that adjustment of the screw 76 will adjust the position of the plunger 74 to vary the effective size of the opening 73.

I claim:

1. In a fuel supply apparatus for a multi-cylinder internal combustion engine including a source of fuel under pressure, a supply rail connected to said source, a return rail, a plurality of injectors for the respective cylinders, conduit means for each injector connected to said rails and including a fuel passage within the injector, and means in each injector connected to said passage for injecting fuel into the associated cylinder, the improvement comprising flow balancing means separate from said injecting means and interposed in each conduit means for balancing the quantity of fuel injected by the respective injectors.

2. The combination of claim 1, in which said balancing means comprises a plug inserted in its associated conduit means and having an orifice, the sizes of the orifices in the respective plugs being such as to balance the quantity of fuel injected by the respective injectors.

3. The combination of claim 1, in which said balancing means is located in said conduit means between said supply rail and the means for injecting the fuel into the associated cylinder.

4. The combination of claim 1, in which said balancing means is located in said conduit means between said means for injecting fuel into the associated cylinder and the return rail.

5. The combination of claim 1, in which said balancing means comprises a pair of plugs having orifices and located respectively upstream and downstream of the means for injecting fuel into the associated cylinder.

6. The combination of claim 1, in which said balancing means comprises a plug having an orifice, and means for varying the effective size of said orifice to balance the flow of fuel to the respective injectors.

7. An injector for injecting fuel into each cylinder of a multi-cylinder internal combustion engine, comprising an injector body including a nozzle and having a fuel passage therethrough adapted to be connected to a supply line and a return line, said body having a metering orifice connected to said passage for supplying a meter-ed quantity of fuel to said nozzle, the improvement comprising fiow balancing means located in said passage remote from said metering orifices for controlling the quantity of fuel flowincludes means for varying the effective size of said orifice.-

10. An injector according to claim 8, in which said plug is threaded in said passage and has a tool receiving socket, whereby it may be readily replaced by a plug having a different size of orifice.

11. An injector according to claim 7, in which said balancing means comprises a pair of plugs having orifices and located respectively upstream and downstream of said metering orifice.

12. An injector according to claim 11, in which said fuel passage at its respective ends is adapted to be connected to said supply line and return line, and said plugs are located in said ends.

13. An injector according to claim 7, in which said balancing means comprises a member having a tubular portion extending across said passage and having a transverse opening aligned with said passage, and an element adjustably mounted in said tubular portion for varying the effective size of said transverse opening.

14. An injector according to claim 13, in which a spring is mounted in said tubular portion urging said element in a direction to increase the effective size of said transverse opening, and manually operable means is provided for adjusting said element against the pressure of said spring to decrease the effective size of said transverse opening.

15. An injector according to claim 14, in which said manually operable means comprises a screw threaded in said body and having a tapered portion engaging said element.

16. An injector according to claim 7, in which said balancing means is located in said passage upstream from said metering orifice.

17. An injector according to claim 7, in which said balancing means is located in said passage downstream from said metering orifice.

18. An injector according to claim 7, in which said balancing means comprises an element mounted in said injector body and extending into said fuel passage, said element being movable toadjust the effective size of said passage.

19, An injector for injecting fuel into a cylinder of an internal combustion engine, comprising an injector body having a nozzle and having a supply passage adapted to be connected to a supply line, a return passage adapted to be connected to a return line, and a metering orifice communicating with said supply passage for metering fuel to said nozzle, and a plug having a balancing orifice and mounted in said supply passage for reducing the pressure of the fuel from said supply line whereby the size of said metering orifice may be increased to provide a predetermined quantity of fuel flowing to said nozzle.

References Cited in the file of this patent UNITED STATES PATENTS 1,252,254 Fisher Jan. 1, 1918 1,333,612 Fisher Mar. 16, 1920 2,347,363 Palurn'bo Apr. 25, 1944 2,389,492 Edwards Nov. 20, 1945 2,614,888 Nichols Oct. 21, 1952 2,777,433 MacCracken Jan. 15, 1957 FOREIGN PATENTS 957,699 Germany Feb. 7, 1957