Fuel Injection Nozzle

Abstract

In a fuel injection nozzle, for varying the fuel quantities injected thereby, there is provided a movable throttle member which determines the flow passage section of a bypass or return channel provided in the fuel injection nozzle. The position and thus the throttling effect of the throttle member is determined by the axial distance between two threadedly interengaging components of the fuel injection nozzle.

Description

This invention relates to a fuel injection nozzle wherein the quantities of the injected fuel may be altered by changing the flow passage section of a return or bypass channel by means of a throttle member which is disposed in said channel and which is associated with a movable abutment to change its stroke.

In a known fuel injection nozzle of the aforenoted type (such as disclosed, for example, in German Published patent application DOS No. 1,551,645), for the purpose of altering the quantities of the returning (bypassed) fuel, and thus changing the quantities of injected fuel, either the nozzle has to be entirely removed from the fuel injection system or an adjustable throttle member has to be provided at an accessible location of the bypass channel. The first solution has the disadvantage that every time a nozzle is removed, the oil conduits are drained and further, until the desired adjustment is obtained, the nozzle has to be screwed in and out several times. The second solution has the disadvantage that in the nozzle structure between the throttle member and the injection opening there prevails a relatively large oil volume which, dependent upon the elasticity of the oil and the differing viscosity, leads to changes in the injected fuel quantities and particularly to additional or after-injection.

It is an object of the invention to provide an improved fuel injection nozzle of the aforenoted type wherein the quantities of the returned fuel may be altered without removal of the nozzle.

Briefly stated, according to the invention there is provided a fuel injection nozzle which comprises two parts, the relative position of which is variable in an axial direction. Between the two parts there is movably disposed the aforementioned throttle member. One of said parts accommodates the pressure chamber and the injection openings, as well as that part of the return conduit, the flow passage section of which is varied by the throttle member. The other part of the fuel injection nozzle carries an abutment which determines the stroke of the throttle member.

The invention will be better understood, as well as further objects and advantages will become more apparent, from the ensuing detailed specification of two exemplary embodiments taken in conjunction with the drawing, wherein:

FIG. 1 is an axial sectional view of a first embodiment of the invention and

FIG. 2 is an axial sectional view of a second embodiment of the invention.

Turning now to FIG. 1, there is shown a hollow nozzle body 1 into which there is clamped, by means of a sleeve 2 having an externally threaded integral collar, an insert 3 provided with an injection opening 3'. The sleeve 2 has a relatively small-diameter, downwardly open axial bore 6 and an adjoining, relatively large-diameter, upwardly open axial bore 7. Between the sleeve 2 and the insert 3 there is provided a vortex chamber 4 which is formed of a cylindrical and an adjoining conical cavity. The latter continues in the injection opening 3'. The cylindrical portion of the vortex chamber 4 communicates with the bore 6 of the sleeve 2. Into the vortex chamber 4 there merge tangential supply channels 8 (only one shown).

The bore 7 telescopically receives a tubular stub 9 of a nozzle holder 10 shown only in part. The nozzle holder 10 threadedly holds the nozzle body 1, so that depending upon the angular position of the stub 9, the latter projects into the bore 7 to a greater or lesser extent. In order to prevent an accidental rotation of the nozzle body 1 with respect to the nozzle holder 10, these two components are tightened to one another by means of a counternut 11. In the bore 7 there is axially displaceably disposed a throttle member 12 provided with guiding wings 12'. The conical needle-shaped extension 13 of the throttle member 12 projects into the bore 6 to affect the flow passage section thereof. Dependent upon how far the tubular stub 9 extends into the bore 7 after threading the nozzle body 1 into the nozzle holder 10, the needle 13, during operation, projects into the bore 6 to a greater or lesser extent thus throttling the bore 6 in a variable manner.

The fuel admitted to the fuel injector nozzle in the direction of arrows A through conduits not shown, flows through a schematically shown filter 14 into an annular space between the nozzle body 1 and the sleeve 2 then through openings 2' and supply channels 8 into the vortex chamber 4. From the vortex chamber 4 one part of the fuel is injected into a combustion chamber of the combustion engine through the nozzle opening 3', while the other part of the fuel flows through the bores 6 and 7 into the tubular stub 9 and then, through the return tube 15 in the direction of arrow B back, for example, to a fuel tank (not shown).

It is seen that the more the nozzle body 1 is screwed into the nozzle holder 10, the smaller is the flow passage section of the annular chamber formed between the needle 13 and the bore 6 and the greater is the fuel quantity injected into the associated combustion chamber of the internal combustion engine. As the fuel under pressure flows upwardly in the bore 6, the throttle member 12 is displaced upwardly and is stopped by an abutment constituted by the lower terminal edge face 9a of the tubular stub 9. FIG. 1 shows the throttle member 12 in this operative position.

Turning now to FIG. 2, in the second embodiment shown therein, a throttle member 16 -- functioning in the same manner as the throttle member 12 of the first embodiment -- has an integral, axially aligned pin 17 which serves as a closing member for the injection opening 3'. For this purpose the throttle member 16 is biased by a spring 18. At the conical portion of the throttle member 16 there are disposed wings 20 to ensure a uniform central guidance of the throttle member in the bore 6.

During the inoperative periods of the fuel injection nozzle, the throttle member 16 assumes a position as shown in FIG. 2. In this position the pin 17 entirely obturates the nozzle opening 3'. As soon as fuel under pressure is admitted to the vortex chamber 4, the throttle member 16 is, under simultaneous compression of the spring 18, shifted into its operative position where it contacts an abutment pin 19 held in the tubular stub 9. The flow passage section of the bore 6 is determined by the axial height position of the abutment pin 19. The second embodiment is particularly advantageous in that it comprises a nozzle closing means (i.e., the pin 17) which effectively prevents an after-injection (or the emptying of the fuel conduits) subsequent to the cut-off of fuel to the fuel injection nozzle.

Claims

What is claimed is:

1. In a fuel injection nozzle of the type that includes (a) means receiving fuel under pressure from outside said nozzle, (b) an injection opening through which a first part of said fuel leaves said nozzle and (c) a bypass channel through which a second, or remaining part of said fuel is returned uninjected, the improvement comprising,

A. a first part containing a portion of said bypass channel,

B. a throttle member movably disposed in said portion of said bypass channel,

C. a flow passage section defined jointly by said throttle member and said portion of said bypass channel; the magnitude of said flow passage section being determined by the position of said throttle member in said portion of said bypass channel,

D. a second part secured to said first part in axial alignment therewith,

E. means for varying the axial position of said first and second parts with respect to one another and

F. an abutment integral with said second part and moving with respect to said portion of said bypass channel upon variation of said axial position; said abutment being disposed in the path of motion of said throttle member for variably limiting its extent of motion.

2. An improvement as defined in claim 1, wherein said throttle member has a conical configuration.

3. An improvement as defined in claim 1, wherein said first and second parts are threadedly secured to one another; said axial position of said parts with respect to one another is variable by rotating said parts relative to one another; said portion of said bypass channel is formed as a cylindrical bore; said throttle member is axially reciprocably held in said cylindrical bore; said improvement further includes a tubular stub forming another portion of said bypass channel and forming an integral component of said second part; said tubular stub telescopically extends into said cylindrical bore and has a terminal edge face constituting said abutment.

4. An improvement as defined in claim 3, including

A. a closing member integral with said throttle member and disposed adjacent said injection opening to cooperate therewith and

B. a spring urging said throttle member away from said abutment and urging said closing member into a position where it obturates said injection opening; said spring has a force which is smaller than an oppositely directed force derived from said fuel under pressure to permit said throttle member to move into engagement with said abutment and said closing member to open said injection opening in response to said fuel under pressure.

5. In a fuel injection nozzle of the type that includes (a) means receiving fuel under pressure from outside said nozzle, (b) an injection opening through which a first part of said fuel leaves said nozzle and (c) a bypass channel through which a second, or remaining part of said fuel is returned uninjected, the improvement comprising,

A. a first part containing a portion of said bypass channel,

B. a throttle member movably disposed in said portion of said bypass channel,

C. a flow passage section defined jointly by said throttle member and said portion of said bypass channel; the magnitude of said flow passage section being determined by the position of said throttle member in said portion of said bypass channel,

D. a second part secured to said first part in axial alignment therewith,

E. means for varying the axial position of said first and second parts with respect to one another and

F. means integral with said second part and cooperating with said throttle member to vary said position thereof upon variation of said axial position of said first and second parts.