DE10346222A1 - Fuel injection device, especially for internal combustion engine with direct injection, has alignment arrangement that aligns sleeve part radially relative to housing recess and valve element is guided in sleeve part - Google Patents

Abstract

The fuel injection device has a housing (28) and a valve element (48) in a housing recess (30) with at least one associated fuel outlet channel (32) and a sleeve part (34) coaxial to the valve element that sits on the valve element. There is an alignment arrangement (38) that aligns the sleeve part radially relative to the housing recess and the valve element is guided in the sleeve part.

Description

The The invention relates to a fuel injection device, in particular for an internal combustion engine with direct fuel injection, with a housing and arranged in a housing recess Valve element, which is associated with at least one fuel outlet channel, and with a sleeve member coaxial with the valve member which rests on the valve member sitting.

A fuel injection device of the above type is known from DE 101 22 256 A1 known. This shows a fuel injection device with a nozzle body in which a longitudinal bore is present. In this an elongated valve element is partially performed. The valve element is "stroke-controlled", that is, it has, at its end facing away from a combustion chamber in the installed position on a control surface which limits a hydraulic control chamber. If a high pressure prevails in the hydraulic control chamber, the valve element is pressed into its closed position. In the event of a pressure drop, the valve element can be opened by an admission device acting in the opening direction. The control chamber is bounded radially outwardly by a sleeve part, which is pushed fluid-tightly onto an end region of the valve element and is pressed by a spring against a housing part lying opposite the control surface.

When in the DE 101 22 256 A1 shown fuel injection device, the valve element has approximately in its axial center on a guide portion which cooperates with a corresponding guide portion of the longitudinal bore in the housing. As a result, the valve element is guided relative to the housing and prevents it from tilting during operation relative to the longitudinal axis of the housing. In order to avoid tensioning of the valve element, the sleeve part at the end, which limits the control chamber radially, is not radially fixed relative to the recess in the housing.

The The present invention has the object of a fuel injection device of the type mentioned in such a way that they are as inexpensive as possible can be produced.

These Task is in a fuel injection device of the aforementioned Sort of solved by that it comprises alignment means, which the sleeve part against the Housing recess radially align, and that the valve element is guided in the sleeve part.

Advantages of invention

By the alignment means becomes the radial position and axial alignment of the sleeve part clearly defined. Therefore, it can very well be one or the only one guide for the Form valve element. On the elaborate and expensive production of Guide surfaces in the wall of the housing recess can therefore in the fuel injection device according to the invention be waived. This is therefore relatively inexpensive.

advantageous Further developments of the invention are specified in subclaims.

First, will proposed that the alignment means at least one peripheral wall at the sleeve part include, which rests against the wall of the housing recess. at this particularly simple embodiment of the alignment is it is at the sleeve part more or less a fitting ring in the housing recess for example, is pressed. This is very simple, robust and cheap.

Is possible also that the alignment means have a plurality of radially extending ones Has webs, each with its projecting end on the wall the housing recess issue. By such webs are automatically between the webs Free rooms formed, for example, part of a fluid connection of a High pressure connection to the fuel outlet channel can be. This facilitates and simplifies the flow guidance in the fuel injection device according to the invention.

In Continuing this it is suggested that the between the webs existing open spaces are dimensioned so that a desired throttling effect achieved becomes. The sleeve part In this advantageous embodiment, therefore, it has a double function, because it also serves to tune the dynamics of the valve element at its opening and closing process.

A further particularly preferred embodiment of the fuel injection device according to the invention provides that at the remote in the installed position from the combustion chamber end of the valve element acting in the closing direction control surface is present, which limits a hydraulic control chamber, and that the sleeve member at least when the valve element is closed via this end of the Valve element protrudes and is pressed by a biasing means against a control surface of the opposite wall of a counter-element, such that it the control chamber opposite the Ge sealing element. Also in this development, the sleeve part has a double function: in addition to the leadership of the valve element, it also serves to the radial delimitation of the control chamber and to seal the control chamber with respect to the counter element. The corresponding fuel injection device therefore builds comparatively compact.

If in such a fuel injection device the above called webs are present, it is advantageous if these webs axially offset from the control room away. This allows additional Freedoms in the design of the wall directly on the counter element adjacent area of the housing recess.

A further particularly preferred embodiment of the fuel injection device according to the invention provides that the alignment means have a conical recess in the Comprise wall of the counter element in the region of the housing recess, in this way that the sleeve part is centered by the conical recess. In this way, the sleeve part across from aligned with the housing recess be without any angular error between the wall of the counter element and the orientation of the housing recess play a role. This simplifies the production and lowers the Production costs of the fuel injection device according to the invention. At the same time, the reliability during operation of the fuel injection device according to the invention elevated, since the seal of the control room even with such angle errors guaranteed is. The correct alignment of the housing and the counter element to each other by simple and usual measures, such as dowel pins, a centering groove, or the like.

alternative it is also possible in that the alignment means have an overall conical and the control surface opposite Wall of the counter element and a corresponding complementary thereto housing wall comprise, such that the sleeve part and the case be centered by the conical wall. That way too will automatically the centering of the sleeve part across from the housing ensured without any contact between the sleeve part and the housing or other alignment means for aligning the counter element with respect to the casing required are. In particular, the assembly of such a fuel injection device is very simple.

there Is it possible, that the wall of the counter element is conically concave. Basically, though also conceivable that this wall is configured conical convex. In both cases The wall can be made very easily and ensures a good centering of the sleeve part.

Further is inventively provided that in a preferred embodiment of the fuel injection device the valve element a guide portion has, which is guided in the sleeve part and a larger diameter has as a portion of the valve member around which the biasing means is arranged. In this way, a contact between the pretensioner and the valve member causing a sliding friction in the operation of the fuel injection device would, avoided. This allows even better and more accurate fuel injection.

drawing

following become particularly preferred embodiments the present invention with reference to the accompanying Drawing closer explained.

In show the drawing:

1 a schematic representation of a fuel system of an internal combustion engine with a fuel injection device;

2 a partial section through a first embodiment of the fuel injection device of 1 ;

3 a section along the line III-III of 2 ;

4 similar to a partial section 2 a second embodiment; and

5 similar to a partial section 2 a third embodiment.

description the embodiments

In 1 a fuel system of an internal combustion engine carries the reference numeral 10 , It includes a fuel tank 12 from which a conveyor system 14 the fuel to a fuel rail ("Rail") 16 promotes. The conveyor system 14 For example, it may include a prefeed pump and a high pressure pump.

To the fuel manifold 16 are several fuel injectors 18 connected, of which in 1 only one is shown. The fuel injector has this feature 18 via a high pressure connection 20 , The fuel injector 18 is a combustion chamber 22 assigned, in which it injects the fuel directly. From the fuel injector 18 leads one Return line 24 to the fuel tank 12 back. The return line 24 is to the fuel injector 18 at a low pressure connection 26 connected.

The construction of the fuel injector 18 will now be with reference to the 2 and 3 explained in more detail:
Thereafter, the fuel injector includes 18 a housing 28 in which a longitudinally extending housing recess 30 is available. The housing 28 is also called a "nozzle body". At the in 2 lower end of the housing 28 are distributed over the circumference arranged fuel outlet channels 32 present, via the fuel from the housing recess 30 in the combustion chamber 22 can get.

The housing recess 30 includes an in 2 lower and at the end tapered section 30a and an upper section 30b that has a larger diameter than the section 30a having. In the upper section 30a the housing recess 30 is a sleeve part 34 used. As in particular from 3 shows, this sleeve part has 34 via a continuous and radially inner guide section 36 , a tapered sealing portion 37 and a plurality of over the circumference of the guide portion 36 distributed, radially outwardly extending webs 38 ,

How out 2 shows, are the webs 38 while the guide section 36 arranged slightly downwards. The bridges 38 become by semicircular open spaces 40 formed between the jetties 38 available. The radially projecting end surfaces 42 of the bridges 38 lie on a common cylindrical surface, which is approximately the lateral surface of the upper portion 30b the housing recess 30 equivalent. In this way, the sleeve part 34 opposite the housing recess 30 radially fixed and centered.

The sleeve part 34 has a centric continuous guide bore 44 on. This works with a leadership section 46 a valve element 48 together, which in this way in the sleeve part 34 guided and so in the housing recess 30 movable in the axial direction, but held immovable in the radial direction. At the guide section 46 joins in 2 lower end of the valve element 48 down a section 50 on, which has a smaller diameter than the guide portion 46 , Just above the transition from the section 30a to the section 30b the housing recess 30 points the section 50 of the valve element 48 a circumferential collar 52 on. Between this collar 52 and the guide section 36 of the sleeve part 34 is a helical compression spring 54 braced.

Above the case 28 includes the fuel injector 18 a plate-shaped counter element 56 , This is on in 2 not shown manner on the housing 28 attached. It points to the housing 28 towards a flat wall surface 58 on. Against this is the sleeve part 34 from the helical compression spring 54 applied. Between the wall surface 58 , the sleeve part 34 , and in 2 upper end surface of the valve element 58 is a hydraulic control room 60 educated. Therefore, the upper end surface of the valve element becomes 48 also referred to as a control surface. It bears the reference number 62 ,

In the plate-shaped counter element 56 are housed different channels and chokes. Therefore, the counter element becomes 56 Also referred to as throttle plate. A first high-pressure channel 64 connects a radially outside of the sleeve part 34 between this, the valve element 48 , and the housing recess 30b existing high pressure room 66 with the high pressure connection 20 , An inlet channel 68 with an inlet throttle 70 leads from the high pressure connection 20 to the control room 60 , A drainage channel 72 , the one flow restrictor 74 contains leads from the control room 60 to a control valve 76 , About this can the control room 60 optionally with the low pressure connection 26 connected or disconnected.

The in the 2 and 3 shown fuel injector 18 is mounted as follows:
First, the valve element 48 in the housing recess 30 used and the helical compression spring 54 on the valve element 48 threaded. Then the sleeve part 34 on the guide section 46 of the valve element 48 deferred and in the section 30b the housing recess 30 centered. Finally, the counter element 56 on the housing 28 attached.

The in the 2 and 3 shown fuel injector 18 is operated as follows:
In the initial state is the control valve 76 closed, and at the high pressure port 20 is located in the fuel rail 16 prevailing high pressure. Thus lies also in the high pressure channel 64 as well as in the high pressure room 66 the corresponding high fuel pressure. Also on a conical pressure surface 78 , which at the in 2 lower end of the valve element 48 is present, this high fuel pressure, so that acts there in an opening direction acting hydraulic force. At the same time the high pressure on the inlet channel 68 also in the control room 60 transfer. Also in this there is therefore a high fuel pressure.

The at the control surface 62 in the closing direction acting hydraulic force is due to the area ratios, however, greater than those at the pressure surface 78 acts in the opening direction. The valve element 48 is therefore with a sealing edge 80 pressed against a corresponding housing-side valve seat (without reference numeral). Fuel can therefore pass through the fuel outlet channels 32 do not leak.

For an injection, the control valve 76 open. Fuel can thus escape from the control room 60 to the low pressure connection 26 flow out. The inlet throttle 70 and the outlet throttle 74 are coordinated so that the pressure in the control room 60 in a certain way sinks. Below that at the control surface 62 acting in the closing direction of the hydraulic force acting in the opening direction of the force acting on the pressure surface 78 abuts, lifts the sealing edge 80 from the housing-side valve seat, and the valve element 48 opens.

It is during this opening movement through the guide section 46 in the guide hole 44 of the sleeve part 34 safely guided. At the same time, the narrow sliding guide between the guide section ensures 46 and the pilot hole 44 for a good seal of the control room 60 opposite the high pressure room 66 , As the sealing edge 80 lifts off the housing-side valve seat, fuel may leak to the fuel exit channels 32 arrive, leaving the fuel injector 18 Fuel in the combustion chamber 22 injects.

If the injection is to be ended, the control valve 76 closed again. This increases the pressure in the control room 60 on and the valve element 48 comes with the sealing edge 80 in contact with the housing-side valve seat.

By doing that section 50 of the valve element 48 , in whose area the helical compression spring 54 is arranged, has a comparatively small diameter, it can during the movement of the valve element 48 between the helical compression spring 54 and the valve element 48 do not come to a sliding friction. Thus, a corresponding wear of the spring 54 and the valve element 48 reduced or completely avoided. As the valve element 48 as soon as the sealing edge 80 lifted from the housing-side valve seat, only on the guide section 46 in the guide hole 44 of the sleeve part 34 is guided, is a complex processing of the housing recess 30 for guiding the valve element 48 not mandatory. The semicircular free spaces 40 between the bridges 38 of the sleeve part 34 can be dimensioned so that a desired throttle effect from the high-pressure channel 64 to the fuel exit channels 32 enters. In an embodiment not shown is on the helical compression spring 54 completely omitted. In this case, the sleeve part 34 in the housing recess 30 in the case 28 fitted in press fit.

An alternative embodiment of a fuel injection device is shown in FIG 4 shown. In doing so, those elements and areas that carry equivalent functions to elements and areas of the context associated with the 2 and 3 have shown embodiment, the same reference numerals. They are not explained again in detail. For reasons of representation, not all reference numbers are also entered.

The differences of in 4 shown fuel injector 18 to the preceding relate to the configuration of the sleeve part 34 and the wall surface 58 the throttle plate 56 , The sleeve part 34 has no webs, but only a guide section 36 and to the throttle plate 56 over a sealing section 37 , The wall surface 58 points in the area of the housing recess 30 a conically concave recess 82 on. The sealing section 37 of the sleeve part 34 is located on the throttle plate 56 in the area of this conical recess 82 at. In this way, the sleeve part 34 opposite the throttle plate 56 centered against it by the helical compression spring 54 is pressed. On a direct centering of the sleeve part 34 opposite the housing recess 30 can therefore be waived. However, the throttle plate needs 56 opposite the housing 28 be positioned very accurately, which is possible for example by dowel pins or a centering groove (both not shown).

A further modified embodiment is in 5 shown. The above applies with regard to functionally equivalent elements and areas.

At the in 5 shown fuel injector 18 is the wall surface 58 the throttle plate 56 a total of conically concave. An opposite housing surface 84 is designed to be complementary, that is conical convex. In this way, on a particular positioning of the throttle plate 56 opposite the housing 28 be dispensed with, since they are virtually self-centering.

Claims (10)

Fuel injection device ( 18 ), in particular for an internal combustion engine with direct fuel injection, with a housing ( 20 ) and in a housing recess ( 30 ) arranged valve element ( 48 ), the at least one force substance outlet channel ( 32 ) and with a to the valve element ( 48 ) coaxial sleeve part ( 34 ), which on the valve element ( 48 ), characterized in that it comprises alignment means ( 38 ; 82 ; 58 ), which the sleeve part ( 34 ) relative to the housing recess ( 30 ) radially, and that the valve element ( 48 ) in the sleeve part ( 34 ) is guided. Fuel injection device ( 18 ) according to claim 1, characterized in that the alignment means ( 38 ) at least one peripheral wall ( 42 ) on the sleeve part ( 34 ), which on the wall of the housing recess ( 30 ) is present. Fuel injection device ( 18 ) according to one of claims 1 or 2, characterized in that the alignment means comprise a plurality of radially extending webs ( 38 ), each with its projecting end ( 42 ) on the wall of the housing recess ( 30 ) issue. Fuel injection device ( 18 ) according to claim 3, characterized in that between the webs ( 38 ) existing free spaces ( 40 ) are dimensioned so that a desired throttle effect is achieved. Fuel injection device ( 18 ) according to one of the preceding claims, characterized in that in the installation position of a combustion chamber ( 22 ) facing away from the end of the valve element ( 48 ) a control surface acting in the closing direction ( 62 ), which has a hydraulic control room ( 60 ) and that the sleeve element ( 34 ) at least when the valve element is closed ( 48 ) about this end ( 62 ) of the valve element ( 48 ) and by a biasing device ( 54 ) against one of the control surfaces ( 62 ) opposite wall ( 58 ) of a counter element ( 56 ) is pressed so that it the control room ( 60 ) against the counter element ( 56 ) seals. Fuel injection device ( 18 ) according to claim 5 in conjunction with one of claims 3 or 4, characterized in that the webs ( 38 ) axially from the control room ( 60 ) are offset away. Fuel injection device ( 18 ) according to claim 5, characterized in that the alignment means a conical recess ( 82 ) in the wall ( 58 ) of the counter element ( 56 ) in the region of the housing recess ( 60 ), such that the sleeve part ( 34 ) through the conical recess ( 82 ) is centered. Fuel injection device ( 18 ) according to claim 5, characterized in that the alignment means have an overall conical and the control surface ( 62 ) opposite wall ( 58 ) of the counter element ( 56 ) and a corresponding corresponding housing wall ( 84 ), such that the sleeve part ( 34 ) and the housing ( 30 ) through the conical wall ( 58 ) are centered. Fuel injection device ( 18 ) according to one of claims 6 or 7, characterized in that the conical recess ( 82 ) or the conical wall ( 58 ) of the counter element ( 56 ) is concave. Fuel injection device ( 18 ) according to one of the preceding claims, characterized in that the valve element ( 48 ) a guide section ( 46 ), which in the sleeve part ( 34 ) is guided and has a larger diameter than a region of the valve element ( 50 ) around which the pretensioner ( 54 ) is arranged.