US2912168A

US2912168A - Fuel injection unit

Info

Publication number: US2912168A
Application number: US643312A
Authority: US
Original assignee: LOrange GmbH
Current assignee: LOrange GmbH
Priority date: 1956-03-03
Filing date: 1957-03-01
Publication date: 1959-11-10
Anticipated expiration: 1976-11-10

Description

Nov. 10, 1959 R. H. L'ORANGE 2,912,168

FUEL INJECTION UNIT Filed March 1, 1957 2 Sheets-Sheet 1 91 INVENTOR.

RUDOLF HEINRICH L'ORANGE ATTORNEY Nov. 10, 1959' Filed March 1, 1957 2 Sheets-Sheet 2 INVENTOR.

RUDOLF HEINRICH LORA/VGE ATTORNEY.

tats

FUEL INJECTION UNIT Rudolf Heinrich LOrange (deceased),

Freudenstadt, Germany, b.H., Glatten, many Unite Glatten, Kreis assignor to LOrange Gm. Wurttemberg, Germany, a firm of Ger- The present invention relates to a fuel injection device for internal combustion engines in which the fuel pump is combined with the fuel nozzle to form a unit.

One of the numerous difliculties preventing general use of a combined fuel pump and nozzle unit is the fact that the unit must be placed close to the combustion chamber so that the pump is exposed to high temperatures causing heating of the pump in addition to heating by the heat produced by the work of the pump.

Other difficulties are caused by the necessity of making at least the portion of the pump nozzle unit which is proximal to the combustion chamber very small so that there is sufficient space left for other elements which must be provided at the same locality, for example, inlet and outlet valves. Because of this requirement, the fuel pumps of conventional injection devices are spaced from the combustion chamber and from the fuel nozzle. This involves undesired dead spaces and additional joints which must be sealed.

It is an object of the present invention to provide a fuel injection pump and nozzle unit which overcomes the diniculties experienced with conventional fuel injection devices by directly and tightly seating a nozzle cap member, which have at least one atomizing orifice, on the guide sleeve for the fuel pump piston.

In the unit according to the invention only one packing or seal is needed against the very high pump pressure which is of advantage and is available in pump and nozzle units. This seal must be tightened only once when the device is assembled. All other elements required at the high pressure portion of the device are accommodated within the nozzle cap member which forms part of the high pressure pump chamber. These elements include one or more pressure valves, a nozzle valve which may be in the :form of a simple check valve or of a back pressure valve, :and auxiliary elements serving to supply, distribute, or whirl the fuel prior to its exit through the atomizing aperture or apertures.

The pump nozzle unit according to the invention is additionally improved by cooling the pump chamber by means of excess fuel. Since the nozzle cap member is in direct contact with the guide for the pump piston, the cap member forms a part of the pump chamber and benefits from the cooling action of the flowing fuel, there being no intermediate parts which interfere with heat conduction and heat transfer. The same is the case with the elements which are located inside of the nozzle cap, particularly the pressure valve and its seat.

The novel features which are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself however and additional objects and advantages thereof will best be understood from the following description of embodiments thereof when 'read in connection with the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional view of a pump nozzle unit according to the invention taken in a flat plane including the vertical axis of the pump nozzle unit;

Fig. 2 is a longitudinal sectional view of a modified pump nozzle unit according to the invention taken in a flat plane including the vertical axis of the pump nozzle unit.

Referring moreparticularly to Fig. 1 of the drawing, numeral 1 designates a casing having a cavity 1 containing a guide sleeve 2 for a pump piston 3 having an upper extension 3'. The lower part of the sleeve 2 is provided with a flange 4 abutting against an internal annular shoulder 5 of the casing 1. The axial extension 4' of the flange 4 is smaller than the thickness of the wall of the sleeve 2 and is so small that the sealing pressure applied to the flange cannot deform the cylindrical portion 2' of the sleeve. The lower surface 4" of the flange 4 is plain and is abutted by the upper end 6' of a nozzle cap member 6. The latter has a substantially cylindrical portion 6", a pressure valve 7 and a seat member 8 for the pressure valve. Also contained in the cap member 6 is an intermediate plate 9 which limits the down stroke of the valve 7, a nozzle valve 10, and an intermediate member ll having bores 11 through which the fuel flows into a chamber 12 from which the fuel is discharged through an atomizing orifice 13 in the bottom of the cap member 6.

The nozzle valve 10 has a cylindrical portion 91 and a frustoconical portion cooperating with

valve seats

14 and 15, respectively, provided at the lower end 16' of a seat element 16, the seat 14 being cylindrical, corresponding to the cylindrical valve portion 91. The valve 10 is pulled onto the

seats

14 and 15 by means of a coil spring 17 interposed between the element 16 and a shoulder 10' provided on the upper end of the stem 18 of the valve 10. The space 13 between the lower seat 14 and the orifice 13 is small.

The pump piston 3 is actuated by a tipping lever 19, of which only a portion is shown, through a pusher 2t). Adjustment is effected by rotation of the piston 3. For this purpose a rotatable regulating shaft 21 is provided with a worm 2i cooperating with a worm. wheel 22' forming part of a regulating element 22 mounted on a sleeve 23 which is rotatable on a cylindrical upper extension 1" of the casing l. Interposed between the element 22 and the sleeve 23 is a Vernier ring 24 coacting with a pin 25 mounted on the element 22 and a pin 26 mounted on the sleeve 23. The lower end 23' of the sleeve 23 is provided with recesses 23" receiving pins 27 extending radially from a member 28 which is mounted on the extension 3' of the piston 3.

The fuel is supplied through a channel 29 in the casing 1 which channel communicates with an internal annular recess 39. The latter communicates with an inlet port 31 of an axial channel 32 in the interior of the piston 3. The lower end 32 of the channel 32 communicates with the pump chamber 33. The latter is formed by the interior of the piston guide sleeve 2, the seat member 8 of the pressure valve 7, and the upper cylindrical portion of the cap member 6. These parts are, therefore, cooled by the cold fuel. At the beginning of the working stroke of the piston 3, the inlet port 31 is closed because the latter moves below the annular recess 30 so that the fuel opens the valve 7 and flows through the valve 10 into the atomizing orifice 13 until a helical groove 34 in the piston 3 communicates with a pocket 35 having a helical edge in the lower end of the pump sleeve 2. From this moment the fuel flows through the groove 34 back into a fuel return conduit 36 in the casing 1.

Fig. 2 shows a modified arrangement in which the fuel supply to the working space of the pump is terminated by a suction valve 40, the other parts of the pump nozzle unit being substantially equivalents of the corresponding parts of the device shown in Fig. 1.

The device shown in Fig. 2 operates as follows:

The liquid fuel enters through an inlet element 41 and passes through a filter 43 into a supply channel 44 in a casing 45. Channel 44 communicates with an internal annular recess 46 of a pump piston guide sleeve 47. The recess 46 communicates through ports 43 in a pump piston 49 with an axial bore 50 in the piston 49. The suction or fuel admission valve 40 closes the lower end 50' of the bore 50 and moves relatively to the piston 49 because of its inertia. Since the pump piston is in the outer dead center position during the greater part of a revolution of a cam 51 actuating a lever 52 which operates the piston 49, the fuel flows into the pump chamber 53 during the greater part of a revolution of the cam 51. The valve 40 is held in the bore 50 by a weak spring 54 and the fuel flows freely past the valve 4%) when the piston is in the outer dead center position. The relatively cold fuel cools the sleeve 47, a seat member 55 for a pressure valve 56, and a nozzle cap member 57. As long as the pump piston is in the outer dead center position, the fuel flows through an opening 61 in the sleeve 47 into a return bore 58 in the casing 45 and through a bore 59 to an outlet element 60.

When the piston 49 is moved towards the inner dead center position and has passed the fuel return opening 61 fuel injection begins and lasts until a helical groove 62 on the outside of the piston 49 has reached a control opening 63 in the sleeve 47 so that the pump chamber 53 is relieved through a channel 64. When the pump piston 49 begins its outward stroke the suction valve 40 opens because of its inertia and because of the pressure of the fuel entering through the conduits 46 and 48. Fuel flows again through the pump chamber 53, cooling the adjacent parts.

The fuel passing the pressure valve 56 flows to the nozzle valve 33. The latter is held in closed position by means of a spring 65 until the fuel pressure overcomes the resistance of the spring. The pressure needed for opening the valve 83 is defined by the spring 65 and by the diameter of the valve seat 66. During the first part of the opening movement of the valve 83 the valve remains substantially closed because of the provision of a cylindrical or piston portion 67 on the valve 83, the portion 67 fitting into a corresponding cavity 68 in the seat member 68. The diameter of the portion 67 makes the opening of the valve 83 labile so that at low speed and little fuel supply the valve will close after an initial opening until suflicient fuel pressure is accumulated for reopening the valve. When the valve closes after termination of the injection the portion 67, because of its relatively great diameter, acts as a suction piston relieving the space 69 in the nozzle end of the cap member 57 and sucking fuel back from the nozzle orifice 70 for avoiding dripping of fuel which is still under considerable pressure into the combustion chamber.

The bottom end 47' of the sleeve 47 is provided with a flange 70 of relatively small axial extension which abuts against an annular shoulder 45' in the cavity 45" of the casing 45 which cavity receives the sleeve. The upper end 57' of the cap member 57 is pressed against the flange 70 by means of a nut member 71 which is screwed into the lower end 84 of the casing 45. Pins 72 fitted into suitable radial bores in the casing 45 extend into suitable recesses 85 in the flange 70 as well as in the upper end of the cap 57 to prevent relative rotation which is of particular importance when assembling and dismantling the device.

The fuel pressure produced during the working stroke of the piston 49 amounts to between 14,220 p.s.i. and 28,440 p.s.i., depending on the configuration of the cam 51, on the tension of the spring 65, and on the size of the atomizing orifice 70.

It is a particular advantage of the pump nozzle unit according to the inventionthat the aforesaid injection pressures, if required by the combustion arrangement of the engine in connection with which the unit is used, can be employed in plants which are exposed to considerable vibrations and the like.

It is important that escape of fuel between the sleeve 47 and the piston 49 be prevented. In the embodiment shown in Fig. 2 fuel flowing from the space 53 along the piston is received in an annular space 64-. The pressure in the latter is lower than the Working fuel pressure; the return flow, however, develops sporadic back-pressures which come close to the working pressure of the fuel. Fuel flowing farther upwards along the piston 49 reaches the annular space 46 into which fuel is supplied and whose pressure is usually not more than 30 p.s.i. Even at this low pressure fuel passes along the piston. This fuel is caught in an annular groove or recess 73 in the sleeve 47 from which it is removed through a conduit 74 which is separated from the fuel supply conduit 44 as well as from the fuel return conduit 59. This separation is important as otherwise the pressure in the conduits 44 or 58 reaches the leakage chamber 73 and forces fuel out of the pump nozzle unit.

For obtaining a tight seal against leakage of fuel collected in the recess 73 the sleeve 47 is provided with two annular steps 86 and 87, one below and one above the recess 73. The steps are opposed to corresponding annular shoulders 88 and 89 in the cavity of the casing 45. Packings 75 and 76 are pressed between the opposed steps and shoulders. The packings must resist the fuel and must be elastic. They are preferably made of pure aluminum, i.e., of a material containing about 99% aluminum.

It has been found of advantage to provide the upper packing 75 with a greater initial tension than the lower packing 74.

Since the pump nozzle unit requires a fuel supply conduit and a fuel return conduit, and, in addition, a third conduit for low pressure leakage fuel, a special column member 77 has been provided accommodating three conduits and extending outside of the cover 78 for the engine cylinder head, a fuel supply nipple 79 and return and leakage nipples being screwed into the top of the column 77.

The pump nozzle unit is held on the engine cylinder head 30 by means of a bracket 81 which presses against the casing 45. The latter presses through the cap member 57 and the nut member 71 against a soft packing 82 resting on the cylinder head and sealing the combustion space against the pump nozzle unit.

What is claimed is:

1. A fuel injection unit for internal combustion engines, comprising a casing, a pump including a sleeve member disposed in said casing, a pump piston reciprocable in said sleeve member, a nozzle means including a member having a hollow substantially cylindrical portion extending into said casing and placed coaxial of and endwisely abutting said sleeve member, an annular groove in said sleeve member opposite the portion of said piston which is distal of said nozzle means for receiving fuel leaking along said piston, the outside of said sleeve member being provided with two axially spaced annular steps, one of said steps being on a radial plane below said groove, the other of said steps being on a radial plane above said groove, said casing being provided with two axially spaced annular steps placed opposite the steps on said sleeve member, leakage removal conduit means in said casing and extending between said steps, and packing rings individually placed between the opposed steps of said sleeve member and of said casing. 1

2. A fuel injection device according to claim 1 in which said packing rings are made of substantially 99% pure aluminum.

3. A fuel injection device according to claim 1 including a column member laterally connected with said casing, said column member being provided with a leakage fuel removal channel connected with said leakage conduit means, a fuel supply channel for conducting fuel to said pump, and an excess fuel return channel for returning excess fuel from said pump.

4. A fuel injection device according to claim 3 including a filter element placed in at least one of said channels.

5. A fuel injection unit for internal combustion engines, comprising a casing, a sleeve in said casing, a hollow pump piston reciprocal in said sleeve, a fuel supply conduit extending through said casing and through said sleeve, a port in said piston for admitting fuel from said conduit into the interior of said piston, a nozzle cap member secured in said casing and abutting against said sleeve and forming a pump chamber with said sleeve, the interior of said piston communicating with said chamber, a fuel return conduit communicating with said pump chamber and extending through said sleeve and said casing and being controlled by said piston for returning excess fuel from said chamber upon a predetermined position of said piston for cooling said cap member, and a valve disposed in the hollow of said piston for closing the hollow of said piston against said pump chamber.

6. A fuel injection unit for internal combustion engines, comprising a pump including a sleeve member, and

a pump piston reciprocable in said sleeve member, a nozzle cap member having a hollow cylindrical portion coaxial of said sleeve member and endwisely abutting against said sleeve member, said cap member having a bottom provided with a fuel atomizing orifice, a pressure valve disposed in the cylindrical portion of said cap member and adapted to receive fuel from said sleeve member, and a nozzle valve placed in the cylindrical portion of said cap member opposite said orifice and receiving fuel from said pressure valve; said nozzle valve including a seat member having a seat and a bore adjacent to and having a greater diameter than said seat, said valve member having a frustoconical portion adapted to seat on said seat, said valve member having a cylindrical portion extending from the greater diameter end of said frustoconical portion and fitting into said bore.

References Cited in the file of this patent UNITED STATES PATENTS