CN1074089C

CN1074089C - Fuel injector for internal combustion engine

Info

Publication number: CN1074089C
Application number: CN97195659A
Authority: CN
Inventors: 芬恩·Q·延森
Original assignee: MAN B&W Diesel AS
Current assignee: MAN Energy Solutions Filial af MAN Energy Solutions SE
Priority date: 1996-06-20
Filing date: 1997-06-18
Publication date: 2001-10-31
Anticipated expiration: 2017-06-18
Also published as: PL183912B1; JP2000505172A; RU2177560C2; KR20000016779A; JP3301616B2; DK68296A; CN1222221A; UA41479C2; PL330812A1; EP0906508B1; NO986015D0; DE69712201T2; KR100427569B1; EP0906508A1; DE69712201D1; ES2176745T3; NO986015L; WO1997048901A1; DK174075B1; NO322670B1

Abstract

A fuel injector (1) for an internal combustion engine has an outer housing (4) with a mounting flange (2) at its back end and an injection nozzle (8) protruding from the housing at its front end, and a fuel passage (34) extending centrally in the injector. A spindle (26) is mounted on the outside of a fuel tube (19) and within a spindle guide (9). A closing spring (21) biasses the spindle forwards in the closing direction, and the spindle guide is pressed forwards in the injector housing by a thrust bushing (10). The fuel tube is a separate unit which is in contact with the valve member positioned behind it via an annular surface (18) which is substantially perpendicular to the longitudinal axis of the injector. The front spindle section (32) has an outer diameter which is at the most 8 mu m smaller than the inner diameter of the spindle guide bore (27), and an inner diameter which is at the most 8 mu m larger than the outer diameter of the front section (24) of the fuel tube.

Description

The fuel injector that a kind of internal-combustion engine is used

The present invention relates to that a kind of internal-combustion engine uses, the fuel injector used of two stroke band crosshead engines particularly, it has a shell, a mounting flange is arranged in its back-end, front end has one from the outstanding nozzle of shell,, a fuel channel that in sparger, extends along the center, fuel channel is from mounting flange, at least by a thrust piece, a center fuel pipe, a push rod and a bar guiding element, till nozzle, the bar guiding element has center hole, its internal surface of column has constituted the guide surface of push rod, fuel pipe have one over half in bar guiding element center hole to extending down, and the proparea that external diameter is littler than the back zone, one this two districts transition position facing to nozzle shaft to ring surface, and guidance behind spring that is used for the preload closing spring, push rod has one and opens backward, center hole is wherein inserted in the fuel pipe proparea, a push rod proparea that has needle, needle cooperates with the open and close sparger with stationary valve seat surface in the bar guiding element hole, and spring top guide that is used for closing spring, spring guide is outwards outstanding from bar guiding element hole in the push rod back zone, closing spring push rod to the closing direction bias voltage previous dynasty, at putting back-end an annular end face is arranged, it is abutted against on the ring surface of fuel pipe owing to the opening motion backward of push rod, in the sparger shell, press forward by a thrust bush barre guiding element at least, thrust bush abut against the bar guiding element towards after annular surface on, and extend back and pass through closing spring, when sparger assembled, mounting flange was pressed thrust piece forward in compression close spring.

This fuel injector knows that from DK-B-155757 it has described a kind of be used to spray easy IGNITION CONTROL oil and gaseous fuel.Wherein thrust bush has played the leading role of valve slide outside, with the open and close air feed.In its back-end, fuel pipe has played the valve chamber effect of vent valve, so it integrally extends along the major component of sparger length.The push rod that is used for open and close control oil be designed to and inboard fuel pipe and outboard beam guiding element hole between sizable gap is all arranged, to prevent because aligning is inaccurate between elongated fuel pipe and the bar guiding element hole push rod is stuck or is subjected to uneven wear.

DK-B-167502 (EP-A 0 606 371) has illustrated a kind of sparger, and wherein, closing spring is accommodated in the center cavity of sliding guide piece, and the rear portion of center fuel pipe and sliding guide piece forms integral body.In addition, between push rod base area and sliding guide piece hole and fuel pipe proparea, all need sizable gap this moment respectively, with incomplete coaxality between compensation manufacturing tolerances and fuel pipe that causes thus and the sliding guide piece hole.

Known a kind of slightly different another kind of sparger that designs from DE-A-2030445 wherein, slides in the quite thin annular space of hollow push rod between fuel pipe and bar guiding element hole of wall thickness.The very heavy shaping spring top guide that putting back-end has a closing spring to use.Wherein, the motion of opening of push rod is restricted, because at its maximum diameter place, the projection of sparger shell has been run in the rear surface of spring guide.This can make thin push rod wall be subjected to a moment of flexure and cause the push rod wall outwardly-bent.Be stuck for fear of push rod, between the annular surface of push rod and its both sides, need sizable gap.Fuel pipe is made up of two-part, its junction surface be positioned at the rear spring guidance above.When sparger assembles, just in time before fuel pipe is forced together, do not have part to come to provide initial position, thereby have the wrong risk in fuel pipe supporting surface location these two tube components.So, may leak at the junction surface place, will cause the variation of fuel injection amount thus.Another shortcoming of this sparger is: the degree that tightens up downwards in the sparger shell according to thrust piece decides the amount of preload of pressure spring.Therefore many same spargers opens pressure and can change.

Known fuel injector type has a hollow push rod between center fuel pipe and bar guiding element hole, its advantage is that the solid push rod of the mass ratio of movable push bar is much smaller, and the sparger movable members that quality is quite little can promote the rapid movement of valve.But hollow push rod has such shortcoming: they slide between two ring surfaces, if the push rod wall produces distortion, can cause the jammed risk of push rod.Consider this point, and in order to compensate above-mentioned malalignment, gap between push rod and the adjacent annular face is quite big, this might make push rod along laterally being displaced to slightly on the slightly eccentric position, wherein, the gap between push rod and bar guiding element hole and the fuel pipe all is that a side at the sparger longitudinal axis is greater than opposite side.Although lateral shift is very little, they can cause the variation by the fuel leak amount in gap in injection program.If push rod is coaxial fully, little by 50% to 70% when then the comparable push rod of leakage rate has the lateral shift position, thereby for identical valve and constant nozzle parameter, as constant sparger supply pressure and fuel quantity, when fuel was done different the injection, the fuel quantity of actual ejection will change.Although adopt the same fuel that parameter and the same state of supply are set, the fuel quantity that different spargers spray also can change.

The objective of the invention is in the fuel injector of the above-mentioned type, improve the repeatability of fuel injection amount and make injection program reach more accurate control.

For this reason, the invention provides the fuel injector that a kind of internal-combustion engine is used, it has a shell, a mounting flange is arranged in its back-end, and front end has one from the outstanding nozzle of shell, a fuel channel that extends along the center in sparger, fuel channel is from mounting flange, at least by a thrust piece, a center fuel pipe, a push rod and a bar guiding element, till nozzle

The bar guiding element has center hole, and its internal surface of column has constituted the guide surface of push rod,

Fuel pipe has: one over half in bar guiding element center hole to extending down and the external diameter proparea littler than the back zone, one this two districts transition position face toward nozzle shaft to ring surface, and guidance behind spring that is used for the preload closing spring,

Push rod has: one open backward, the cartridge proparea inserts centre bore wherein; Push rod proparea with needle; Needle cooperates with the open and close injector with stationary valve seat surface in the bar guide hole; And spring top guide that is used for closing spring; Spring guide is outwards outstanding from bar guide hole in the push rod back zone; Closing spring push rod to the closing direction bias voltage previous dynasty; At putting back-end an annular end face is arranged; It is abutted against on the ring surface of cartridge owing to the opening backward motion of push rod

In the sparger shell, press forward by a thrust bush barre guiding element at least, thrust bush abut against the bar guiding element towards after annular surface on, and extend back and pass through closing spring, when sparger assembles, mounting flange is pressed thrust piece forward in compression close spring, it is characterized in that: the guidance external diameter is less than the internal diameter of thrust bush behind the spring of fuel pipe, fuel pipe is an independent separation member, contact with the valve member that is positioned at its back by a supporting surface, this supporting surface is on the rear surface of guidance behind the spring, and be one around the center fuel channel, ring surface perpendicular to the sparger longitudinal axis, and in the push rod proparea in insertion rod guiding element center hole, the push rod external diameter is at most than the little 8 μ m of bar guiding element hole internal diameter, and internal diameter is at most than the big 8 μ m of fuel pipe proparea external diameter.

Therefore adopt this design, push rod only is slightly larger than fuel pipe, and is slightly less than the slip valve opening, has limited the possibility that produces lateral shift between difference injection degree basically, is restricted to usually to below half of side-play amount in the type prior art sparger.Because to the fluid friction of periphery, fuel leak is prevented from basically, though therefore between the surface gap of maximum possible obtain seldom restriction, also can significantly reduce the variation of leakage rate.Obtain more uniform fuel injection amount thus, promoted to have the more accurate burning of power demand, reduced the fuel consumption of motor, and more likely limit environmentally harmful bad radiation product, as NO _x, the also decomposition of residue of combustion on thermal force on the control cylinder component and the cylinder component better.This is for the two-stroke large diesel machine advantageous particularly of the low grade fuel that usually burns.

Three conditions that valve member is accurately aimed at mutually when push rod respectively and precision-fit is sparger work between fuel pipe and the bar guiding element hole.Opposite with the sparger of prior art, even the aligning between three valve members has error slightly, perhaps on this tubulose thin-walled push rod, act on uneven load, will cause the uneven wear of push rod and/or be stuck, for example cause the bar wall outwards slightly crooked.The present invention has avoided this problem, and it separates the valve member of fuel pipe with its back, makes fuel pipe include only from the rear spring guidance of closing spring and extends, also enters the fuel channel district in the push rod downwards.During sparger part in assembling sparger shell, can be inserted in push rod in the bar guiding element, can be contained in the fuel pipe with closing spring on the push rod, distaff guiding element rear end pushes away thrust bush downwards, and the sparger shell can the location of relative vertical center axis with these sparger parts then.Meticulous cooperation between push rod, bar guiding element and fuel pipe means that under with vertical shaft location and load-less condition, each part can be mutually adjusted into coaxial position, thus in other valve member insertion shell, and fastening mounting flange.When installing other part, the valve member that is positioned at the fuel pipe back is inserted thrust bush, then it is moved forward near fuel pipe.This provides the initial guiding of valve member, and has prevented the lateral shift of valve member when valve member contacts with fuel pipe.When continuing fastening sparger, valve member is pressed downwardly onto the annular bearing surface that makes progress with fuel pipe and is close to, and therefore, because the friction between supporting surface and the valve member, fuel pipe is correctly fixed, and has suitable coaxality with respect to the bar guiding element.The position of correct fixed fuel pipe is very important, can make supporting surface be substantially perpendicular to the longitudinal axis of sparger, thereby laterally steering power can not affact on the supporting surface when assembling.By the same token, between guidance behind the spring and thrust bush, should have the gap, thereby can not hinder the correct adjustment of spring guide during the percussion thrust bush.

Preferably, the external diameter in push rod proparea is than little 2 to the 4 μ m of bar guiding element hole internal diameter, and the internal diameter of above-mentioned putting green is than big 2 to the 4 μ m of fuel pipe proparea external diameter.Because the cooperation of this precision, the variation of leakage rate reduces greatly, and the gap between movable push bar and static bar guiding element and the fuel pipe just in time even as big as push rod can be vertically moved without a doubt.

In a further advantageous embodiment, at least to the spring top guide, preferably to being positioned at the push rod proparea of rod guidance to the part hole, the diameter difference between push rod internal surface and the fuel pipe outer surface is actual to be bigger than the putting green that is positioned at the front from putting back-end.For example, in the push rod back zone, the gap between push rod and the fuel pipe than between these two parts at the big 0.1mm in the gap in push rod proparea.Its effect is: in inside and outside lip-deep vertical annulus along push rod proparea scope inner push-rod, can reach roughly the same pressure drop by the slit.Consequently, can not bear the pressure reduction of any radial effect, might produce at the very little push rod of push rod proparea wall thickness at the push rod wall in push rod proparea.

The present invention also provides many different ways to reduce the quality of push rod.Can make inner cone to the spring top guide of push rod, the thickness at its maximum diameter place is minimum.The also comparable fuel pipe of the wall thickness in push rod proparea proparea is little.To the pressure chamber around needle, the length of inclined hole is less than 35% of push rod proparea external diameter from push rod center hole bottom, and this has reflected that the push rod front bulkhead has little wall thickness, can reduce the push rod front end quality of needle peripheral region thus.The needle of center hole is opened in employing forward on its end face, also can further reduce this regional quality.But the latter only provides limited quality to reduce.These various schemes can be used separately.If several scheme combination are used,, can obtain the minimum push rod of quality then with respect to the size of sparger.

Reduce the push rod quality and can further improve the accurate control of the repeatability and the injection program of fuel injection amount simultaneously.This is because less push rod quality can cause when the open and close sparger pushrod movement faster, and push rod and the prooving of valve seat also tail off, because lighter push rod all diminishes to valve seat and the bump of opening the sports limiting block.The unexpected startup that the opening rapidly of valve provides fuel to spray, this has promoted the fuel good and stable atomizing of emitted dose first, thereby obtains clearly and fuel ignition rapidly.The more important thing is the rapid closing of sparger, it provides stopping suddenly of burning, and this promptly under low pressure and the not enough condition of Spraying rate (gram fuel/second), has reduced the emitted dose of closing motion phase fuel under adverse condition.The final fuel that sprays is to form as No basically _xThe radiation product, it has constituted the cylinder part, and strong heat is carried and oil smoke decomposes, and causes the increase of fuel consumption.Lighter push rod has reduced the disadvantageous fuel quantity of injection, in each total fuel quantity that sprays, has increased the fuel ratio that sprays under optimum condition.

In a preferred embodiment, on the back side of guidance behind the spring, the supporting surface external diameter of fuel pipe is littler than the external diameter in fuel pipe proparea.At first, little supporting surface external diameter has such effect: the fuel pipe longitudinal axis and the small angle between the valve member longitudinal axis of its back can not cause the leakage on the supporting surface, because the manufacturing roughness of two pressure surfaces has compensated any little misalignment, wherein, the mutual immediate side on two surfaces, uneven being compressed, and form airtight supporting at the relative opposite side of diameter.Secondly, little supporting surface external diameter can make airtight surface pressure between each supporting surface always surpass current fuel pressure in fuel channel.When sparger is closed, owing to spring force backward to guidance effect behind the spring, and owing to fuel pressure on the fuel pipe front end surface makes to have produced surface pressure between two supporting surfaces to the power backward of fuel pipe effect.When sparger is opened because fuel pressure acts on the entire front end of push rod, this power backward by on fuel pipe towards axial annular surface, pass on the fuel pipe from push rod, so fuel pressure is used on the fuel pipe with bigger masterpiece backward.Preferably, fuel pipe backward the inside and outside diameter of supporting surface the inside and outside diameter dimension with the push rod proparea is identical respectively basically, this size can provide fully directly axial force stream in the push rod wall.

In making the simple especially design of manufacturing and assembling, fuel injector is used for jet preheat fuel, as heavy fuel oil, valve member in the fuel pipe back is the valve chamber of fuel cycle valve, when sparger assembles, the annular rear end of thrust bush leans against on the supporting surface forward of an annular notch rear end in the valve chamber outer surface proparea, and thus, the length of thrust bush has been determined the preload of closing spring.Adopt this design, the thrust bush in institute's installation valve is respectively between two supporting surfaces on bar guiding element and the valve chamber, and the valve seat in the bar guiding element and against between the valve chamber front surface of fuel pipe supporting surface, set up clear and definite and predetermined distance.Because the push rod band of valve the spring top guide, the fuel pipe racks guidance behind the spring of closing spring, when sparger assembled, closing spring can be preloaded into definite state, and push rod has clear and definite and predetermined stroke or raises height between closure and open position simultaneously.For example, during application sprayers, the length that can change thrust bush is finely tuned the height of raising of preload and push rod in a concrete motor, length short and other all constant, will produce higher preload and the less height of raising.This provides very big simplification for the sparger assembling, as long as the sparger part is tightened together as much as possible, just can obtain correct spring preload, and the correct pressure of open and close sparger.This has prevented between each valve spring preload and has opened the variation of pressure too big, how much comes the setting spring preload to what mounting flange was screwed into the sparger shell downwards if rely on, and then just has this problem in valve.

The valve chamber of barre guiding element, push rod, closing spring, fuel pipe, thrust bush and circulating valve is assembled into a prepackage accessory, then can further simplify assembling, wherein by thrust bush valve chamber and bar guiding element is locked together mutually.This makes might be for sparger provides complete sum preassembled Replacement Part, thereby can change important part as quick as thought.In order to realize locking, for example, can be on bar guiding element and valve chamber the thrust bush hot charging, after perhaps on thrust bush being pressed onto two sparger parts, adopt a pin, laterally inserted on thrust bush and above-mentioned part in the corresponding hole, fixedly thrust bush is with respect to the position of other two parts.

Vertical along sparger, between sparger inner surface of outer cover and valve chamber outer surface, and between thrust bush and bar guiding element, can provide the cavity of a perforation.The advantage that cavity provides is: the static sparger part in the sparger shell is all fixing between 2 o'clock, and promptly fixing between front on the mounting flange internal surface and the back on the nozzle, it has formed the rotation-symmetric load-up condition in the sparger part.Another advantage is that cavity has played the drain passage effect to any leaked fuel.

It is as follows referring now to accompanying drawing one embodiment of the present of invention to be described in further detail, and accompanying drawing has been represented the longitudinal sectional drawing of fuel injector of the present invention.

Summarize the fuel injector represent with 1 and have mounting flange 2 with inlet short tube 3, the high-voltage tube (not shown) that comes from fuel source can be connected with inlet short tube 3.For example, fuel source can be a Bosch formula piston fuel pump that is started by the camshaft overhead cam cycle, or passes through the pressure pan that control valve is communicated with inlet short tube 3 periodically.Fuel can be liquid or gas, or solid fuel slurry or contain the emulsion of one of above-mentioned state at least, valve also can be separately or hybrid mode be used for to firing chamber atomizing of liquids or additives gas.

Rely on union nut 5, the shell 4 of sparger is pressed on the mounting flange, and the screw that mounting flange is inserted in the flange hole 6 is fastened on the cylinder.Article one, fuel channel 34 can pass through nozzle bore not shown in the figures from extending to nozzle 8 by the inlet 7 in the inlet short tube 3 at sparger center, and fuel is ejected in the working room of internal-combustion engine from nozzle 8.

Thrust piece 12 before relying on thrust bush 10, valve chamber 11 and leaning against mounting flange on the internal surface, barre guiding element 9 is pressed downwardly onto on the internal surface of nozzle.Thrust bush has and the roughly the same external diameter of valve chamber 11 and bar guiding element 9 back zones, and inserts in the annular notch of these two parts, make thrust bush 10 nestle up the bar guiding element in the face of axial annular end face and above the valve chamber to axial supporting

surface

13,14.

Valve body 15 inserts in the hole of valve chamber 11, and is biased into illustrated position by quite weak pressure spring 16.Nestle up on the center fuel pipe 19 rear end outburst areas supporting surface 18 after the corresponding ring-type at the outstanding preceding supporting surface 17 of valve chamber front end, the junction surface between these two substantially parallel supporting planes is positioned at and the vertical substantially plane of the sparger longitudinal axis.

Be right after below supporting surface 18, fuel pipe has a bulge loop 20, has constituted guidance behind the spring of closing spring 21, and spring is conventional mechanical compression springs.In the spring guide front, fuel pipe has formed a cylindrical back zone 22, and its external diameter is slightly less than the internal diameter of spring.End in front, back zone 22 is an annular surface 23, and it is positioned at the plane vertical with the sparger longitudinal axis.Surface 23 transition zones that formed between fuel pipe back zone and the proparea 24, the proparea has less diameter, and extends down in the hole 25 of opening towards push rod 26 back zones, arrives from the hole the very short-range fuel pipe front end in 25 bottoms.This short distance is greater than the height of raising of push rod.

Bar guiding element 9 has a center hole 27, and wherein a part is a cylindrical form interior surface, has constituted the guide surface of push rod.In the front of this part, the bar guiding element has pressure chamber 28, and the pressure chamber has the static valve seat of taper, and static valve seat cooperates with corresponding taper activity valve seat on needle 29 front ends of push rod front end.In the valve seat front side, bar guiding element hole extends in the center hole of nozzle 8.

Push rod 26 has the spring top guide 30 of bulge loop form, and its back side is perpendicular to the sparger longitudinal axis, and its front 31 is taper.Closing spring is between two

spring guides

20 and 30, and within thrust bush 10.When the sparger part assembled, closing spring was compressed to condition of preload.The magnitude of closing force forward that spring produces on the spring top guide 30 of push rod is very accurate because when assembling spring decrement determined by the length of thrust bush 10 and the free length of closing spring.

The diameter of push rod internal surface is than big 2 to the 4 μ m of external diameter in fuel pipe proparea 24, and push rod proparea 24 external diameters in the insertion rod guiding element hole are than little 2 to the 4 μ m of hole 27 internal diameters.The wall thickness in push rod proparea is littler by 30% than the wall thickness in fuel pipe proparea 24 approximately.The push rod front bulkhead of 25 bottoms has smaller wall thickness in the hole, and is almost vertical with the sparger longitudinal axis around the annular end face of needle 29.Because wall thickness is less, the length that the inclined hole 33 that hole 25 is communicated with pressing chamber 28 is had is littler by 35% than push rod proparea 32 external diameters.

Center fuel channel 34 extends to the center hole 35 of valve body 15 downwards from inlet 7 by thrust piece 12, passage is divided into several inclined holes 36 there, leads to the pressure chamber 38 around needle 37.The static valve seat front that is cooperating with needle 37, fuel channel extends at the center, by valve chamber 11 fronts, cross supporting

surface

17 and 18, and further forward by fuel pipe 19, outwards open 25 bottoms, hole in push rod, and fuel channel continues to enter nozzle 8 by inclined hole 33, pressure chamber 28 and nozzle bore not shown in the figures therefrom.

Drain boles 39 can be excreted to the fuel that spills along sparger vertically the perforation cavity that sparger shell 4 internal surfaces extend from the cavity around closing spring 21.

Between two injection periods, there are some low pressure pre-heating fuels to supply with inlet 7.In the cavity of side leakage passage 40 inflows around pressure spring 16 of these fuel by thrust piece 12 front portions.Outfall 41 in valve chamber 11 is sent into chamber 42 to circulating fuel, has a recovery tube not shown in the figures that fuel is taken out of sparger therefrom.Fuel cycle in the closed phase of sparger has guaranteed that fuel system is suitably keeping preheating under the high temperature.

When injection period begin, when fuel pressure raises, the pressure of pressure chamber 38 raises immediately, the masterpiece backward that has overcome pressure spring 16 power is used on the valve body, valve body moves backward thus, cuts off leakage way 40.Fuel pressure propagates into pressure chamber 28 downwards by fuel channel then.When the fuel pressure when here reached the cracking pressure of sparger, push rod 26 was subjected to the backward power effect bigger than closing spring 21, and push rod is moved backward, ran on the fuel pipe till the ring surface 23 up to the annular end face of push rod.Therefore the effect of pushrod movement positive stop has been played on surface 23, and has determined the height of raising of push rod.The mobile fuel outlet of having opened to nozzle of push rod, the beginning burner oil.The discharge pressure of fuel descends once more spraying at the end, 28 internal pressures corresponding decline in chamber makes closing spring overcome the backward pressure of fuel to push rod, and push rod is got back to closed initial position thus, needle 29 is close on the corresponding valve seat, and cuts off the outlet of leading to nozzle.

For shown in the push rod of thin-walled design, for fear of the distortion of cylindricality push rod wall, importantly make the putting back-end surface become extending axially of cylindricality push rod wall, because this can guarantee that push rod only passes to push rod to axial force to the bump on surface 23.

If do not need the circulation of pre-heating fuel in the closed phase of sparger, then can save circulating valve and simplify sparger.This moment, thrust piece 12 and valve chamber 11 can form a single piece as the thrust piece shape, had the central through bore in formation fuel channel 24 zones, and it is communicated with inlet 7 with central passage in the fuel pipe.

Also can enlarge the application of sparger, be connected, for example adopt above-mentioned sparger part to be connected with the sparger of above-mentioned Danish Patent number 155757 types with several different liquids injections.For example, this sparger can be used to gas jet and control oil, or is used for other liquid of burner oil and change combustion process, as water, to reduce the formation of bad radiogen.

Claims

1. fuel injector (1) that internal-combustion engine is used, it has a shell (4), a mounting flange (2) is arranged in its back-end, front end has one from the outstanding nozzle (8) of shell,, a fuel channel (34) that in sparger, extends along the center, fuel channel is from mounting flange, at least by a thrust piece (12), a center fuel pipe (19), a push rod (26) and a bar guiding element (9), till nozzle

Bar guiding element (9) has center hole (27), and its internal surface of column has constituted the guide surface of push rod,

Fuel pipe has: one over half in bar guiding element (9) center hole to extending down and the external diameter proparea (24) littler than back zone (22), one this two districts transition position facing to nozzle shaft to ring surface (23), and guidance (20) behind spring that is used for preload closing spring (21)

Push rod has: one open backward, the cartridge proparea inserts centre bore (25) wherein; Push rod proparea (32) with needle (29); Needle cooperates with the open and close injector with stationary valve seat surface in bar guide (9) hole; And spring top guide (30) that is used for closing spring; Spring guide is outwards outstanding from bar guide (9) hole in the push rod back zone; Closing spring push rod to the closing direction bias voltage previous dynasty; At putting back-end an annular end face is arranged; It is abutted against on the ring surface (23) of cartridge owing to the opening backward motion of push rod

In the sparger shell, press forward by a thrust bush (10) barre guiding element (9) at least, thrust bush abut against bar guiding element (9) towards after annular surface (13) on, and extend back and pass through closing spring, when sparger assembles, mounting flange is pressed thrust piece (12) forward in compression close spring, it is characterized in that: guidance behind the spring of fuel pipe (20) external diameter is less than the internal diameter of thrust bush (10), fuel pipe (19) is an independent separation member, contact with the valve member that is positioned at its back by a supporting surface (18), this supporting surface is on the rear surface of guidance behind the spring, and be one around center fuel channel (34), ring surface perpendicular to the sparger longitudinal axis, and in the push rod proparea (32) in insertion rod guiding element (9) center hole (27), push rod (26) external diameter is at most than the little 8 μ m of bar guiding element (9) hole internal diameter, and internal diameter is at most than the big 8 μ m of fuel pipe proparea (24) external diameter.

2. according to the fuel injector of claim 1, it is characterized in that: the external diameter in push rod proparea is than little 2 to the 4 μ m of bar guiding element (9) hole internal diameter, and the internal diameter of above-mentioned putting green is than big 2 to the 4 μ m of fuel pipe proparea external diameter.

3. according to the fuel injector of claim 1, it is characterized in that: from putting back-end at least to the spring top guide, preferably to being positioned at the push rod proparea of rod guidance to part (9) hole, the diameter difference between push rod internal surface and the fuel pipe outer surface is actual to be bigger than the putting green that is positioned at the front.

4. according to the fuel injector of claim 1, it is characterized in that: the spring top guide (30) of push rod has inner cone (31), and the thickness at its maximum diameter place is minimum.

5. according to the fuel injector of claim 1, it is characterized in that: the wall ratio fuel pipe proparea (24) of push rod proparea (32) is little.

6. according to the fuel injector of claim 1, it is characterized in that: to the pressure chamber around needle (29), the length of inclined hole (33) is less than 35% of push rod proparea external diameter from push rod center hole (25) bottom.

7. according to the fuel injector of claim 6, it is characterized in that: needle (29) has on its end face the center hole towards front opening.

8. the fuel injector of any in requiring according to aforesaid right, it is characterized in that: on the back side of guidance behind the spring (20), the external diameter of the supporting surface of fuel pipe (18) is littler than the external diameter of fuel pipe proparea (24).

9. require in 1～7 the fuel injector of any according to aforesaid right, it is characterized in that: fuel pipe backward the inside and outside diameter of supporting surface (18) the inside and outside diameter dimension with push rod proparea (32) is identical respectively.

10. require in 1～7 the fuel injector of any according to aforesaid right, it is characterized in that: fuel injector is used for jet preheat fuel, as heavy fuel oil, valve member in the fuel pipe back is the valve chamber (11) of fuel cycle valve, when sparger assembles, the annular rear end of thrust bush (10) leans against on the supporting surface forward (14) of an annular notch rear end in the valve chamber outer surface proparea, and thus, the length of thrust bush has been determined the preload of closing spring (21).

11. fuel injector according to claim 10, it is characterized in that: the valve chamber of bar guiding element (9), push rod, closing spring, fuel pipe, thrust bush and circulating valve is assembled into a prepackage accessory, wherein by thrust bush valve chamber and bar guiding element (9) is locked together mutually.

12. require in 1～7 the fuel injector of any according to aforesaid right, it is characterized in that: vertical along sparger, between sparger shell (4) internal surface and valve chamber outer surface, and between thrust bush and bar guiding element (9), provide the cavity of a perforation.