DE10245735A1 - Fuel injector nozzle for internal combustion engine, has hollow housing with conical tip and offset large and small bores for outlet of fuel into cylinder - Google Patents

Abstract

The fuel injector nozzle (22) has a hollow housing (36) with a conical tip. It has offset large (58) and small (74) bores for outlet of fuel into the cylinder. There are two valve elements (40,42) inside the blind bore in the housing. They have conical surfaces (52,72) engaging on the conical inner surface at the end of the housing. The outer valve element is connected to the inner valve element by a compressible spring (64) with cutouts (65) to increase the flexibility.

Description

State of the art

The invention relates to a fuel injection device for one Internal combustion engine, in particular for an internal combustion engine Direct fuel injection, with a housing, with one existing in the housing Recess, with at least one arranged in the recess Valve element that works with a valve seat and soft which has a fuel outlet is assigned, wherein the at least one valve element of at least a biasing device is applied to the valve seat.

Such a fuel injector is from the DE 40 23 223 A1 known. This shows an injector with two coaxial valve needles. The valve needles are pressed against a valve seat by a helical compression spring. These are pushed away against the force of the helical compression springs when the pressure of the fuel in the area of the valve seat is increased.

Object of the present invention is a fuel injector of the type mentioned at the outset in such a way that they are as compact as possible and just build.

This task is accomplished with a fuel injector of the type mentioned in that the pretensioning device one piece in the valve element Integrated spring section includes.

Advantages of invention

According to the invention, in a single component, namely the valve element, several functions combined: The valve element has one task, the fuel flow from the Fuel injector by opening and closing one To control fluid paths. On the other hand, he is now additionally delegate the task for those To provide bias, which is required to at rest to interrupt the fluid connection, in other words the fuel injector keep closed.

This is made possible by the integration an elastic spring section in the otherwise high rigidity having valve element (in the fuel injection device according to the invention it is therefore a pressure-controlled device in which to open a portion of the valve element by a hydraulic force against the Actuation force lifted from the valve seat by the spring section becomes). As a result, the fuel injection device builds comparatively compact, since a separate pretensioning device is no longer required is, and the assembly is simplified because fewer parts are to be handled.

Advantageous further developments of Invention are in subclaims specified.

In a first advantageous development suggested that the fuel injector at least two valve elements arranged coaxially in the recess has, which against at least one biasing device the respective valve seat are acted upon, the biasing device at least one valve element into the valve element. integrated in one story Includes spring section. With such a fuel injection device with several valve elements, the compact design possible according to the invention Construction particularly noticeable.

It is also proposed that the Spring section is welded to a sealing section of the valve element. Such a welded joint can the forces that occur record very well. By the immediate. Connection of the spring section with the sealing portion of the valve element can also build the valve element very short and therefore very compact.

Despite its compact design, one can very good sealing effect and therefore precise switching of the valve element can be achieved if the spring section is integrally connected to at least one guide section is. Through this guide section overall despite the softness and elasticity of the spring section a precise Positioning of the valve element enables.

A particularly preferred variant the fuel injection device according to the invention is that the spring section comprises a tubular spring. With such a Bourdon tube can on the one hand, the high levels required for secure sealing personnel are applied, and on the other hand builds such a Bourdon tube very compact and offers about it a certain lateral stiffness.

In further training, it is proposed that the wall of the tube spring has a plurality of openings arranged offset from one another. Due to the location, shape and number of these openings, the rigidity of the Bourdon tube exactly to the special requirements of the fuel injection device be aligned.

A comparatively small spring travel of the spring section is required if it is supported on the housing. In this case, at least with regard to the preload force, there is no interaction with any other valve element that may be present. On the other hand, the compactness of the force according to the invention Substance injection device can be increased again when the spring section is supported on the other valve element.

The following are particularly preferred exemplary embodiments of the present invention with reference to the accompanying Drawing explained in detail. The drawing shows:

1 is a schematic representation of a fuel system of an internal combustion engine with a plurality of fuel injection devices;

2 a partial, simplified section through a first embodiment of one of the fuel injectors of 1 ;

3 a detailed view III of a portion of the fuel injector of 2 ; and

4 a detailed representation similar 3 of a second embodiment of one of the fuel injectors of 1 ,

description of the embodiments

In 1 a fuel system bears the overall reference number 10 , It is part of an internal combustion engine, which in 1 is not shown in detail.

To the fuel system 10 belongs to a fuel tank 12 , from which an electric fuel pump 14 Fuel into a low pressure fuel line 16 promotes. This leads to a high pressure fuel pump 18 , With the high pressure fuel pump 18 it is a piston pump which is driven by a camshaft (not shown) of the internal combustion engine. The high pressure fuel pump 18 compresses the fuel to a very high pressure and feeds it to a fuel manifold 20 , This is also known as a "rail". The fuel is stored in it under very high pressure.

To the fuel rail 20 are multiple fuel injectors 22 connected. For this purpose, they each have a high-pressure connection 24 , The fuel injectors 22 inject the fuel directly into the combustion chambers assigned to them 26 the internal combustion engine. To control an injection is for each fuel injector 22 a control valve 28 provided, the function of which will be discussed in more detail below. The control valve is 28 in 1 separately from the fuel injector 22 shown, but this is only for illustrative reasons. The control valve is usually 28 into the fuel injector 22 integrated. The fuel used can also be gasoline or diesel fuel.

Operation of the internal combustion engine, the fuel system 10 , and in particular the fuel injectors 22 is controlled by a control device 30 controlled or regulated. For this, this is via lines (without reference numerals) with the control valves 28 of fuel injectors 22 connected. The control and regulating device also receives 30 Signals from a pressure sensor 32 with which the pressure in the fuel rail 20 is recorded. The control unit is on the output side 30 with a pressure control valve 34 connected to which the pressure in the fuel rail 20 can be adjusted.

The construction of one of the fuel injectors 22 will now be described with reference to the 2 and 3 explained in detail.

The fuel injector 22 includes a housing 36 , In this is an elongated and in the longitudinal direction of the housing 36 running recess 38 available. In the recess 38 are two coaxial valve elements 40 and 42 visible.

The one valve element 40 is designed as an elongated cylindrical valve body. It includes a guide section 44 , the sliding but fluid-tight on the inner wall of the recess 38 of the housing 36 is applied. Between the top ( 2 ) of the guide section 44 and a closure part 45 of the housing 36 is a helical compression spring 47 braced. To the leadership section 44 is a transition section 46 molded, which is slightly smaller in diameter than the guide section 44 Has. In 2 below the transition section 46 includes the valve element 40 a holding section 48 , whose special function will be discussed in more detail below. Between holding section 48 and transition section 46 is a paragraph 50 available.

This in 2 lower end of the valve element 40 is through a sealing section 52 formed that tapers conically. The sealing section 52 includes two areas with different taper angles, creating a sealing edge 54 is formed. Radially outside of the sealing edge 54 is a printing area 55 available. The sealing edge 54 works with a valve seat 56 in a tapered end region of the recess 38 together. Radially inward from the valve seat 56 becomes the wall of the case 36 from a fuel outlet channel 58 penetrated.

The second valve element 42 is considerably shorter than the first valve element 40 , It only extends approximately over the length of the holding section 48 of the valve element 40 , The valve element 42 includes on his in the 2 and 3 upper end of an annular guide section 60 and at his in the 2 and 3 lower end of a likewise annular combined guide and sealing section 62 , The annular guide section 60 is with the top edge and the combined guide and sealing section 62 with the bottom a Bourdon tube 64 welded, openings in the wall 65 available. The corresponding welds have the reference symbols 66 and 68 , Although the welds shown are 66 or 68 one-piece, but the formation of a two-part weld is also conceivable.

The one in the 2 and 3 upper annular guide section 60 is based on the one hand on the paragraph 50 between the transition section 46 and the holding section 48 from. On the other hand, it has an inner diameter which is approximately the outer diameter of the holding section 48 equivalent. It is through the holding section 48 so centered and guided. The same applies to the combined guide and sealing section 62 : Also the inside diameter corresponds approximately to the outside diameter of the holding section 48 , So it is through the holding section 48 centered and guided. Here is the fit between the combined guide and sealing section 62 and the holding section 48 chosen so that the combined guide and sealing section 62 on the holding section 48 can slide in the longitudinal direction.

The inside diameter of the Bourdon tube 64 is slightly larger than the outer diameter of the holding section 48 , The combined guide and sealing section 62 of the valve element 42 is similar to the sealing section 52 of the valve element 40 educated: he tapers into the 2 and 3 downwards conical, it has two areas with different conicity, between which a sealing edge 70 is formed. The radially outside of the sealing edge 70 located area forms a printing area 71 , The sealing edge 70 also works with a valve seat 72 together, on the inner wall in a conically tapered end region of the recess 38 is available. Radially inwards from the valve seat 72 becomes the wall of the case 36 from a second fuel outlet channel 74 penetrated. Its diameter is smaller than the diameter of the fuel outlet channel 58 ,

Between the transition section 46 and the second valve element 42 on the one hand and the inner wall of the recess 38 on the other hand is an annulus 76 available.

This is over a channel 78 that in the housing 36 runs, with the high pressure connection 24 connected.

The fuel injector 22 works as follows:
The control valve is at rest when no injection is to take place 28 closed. In this case the annulus is 76 depressurized. The corresponding forces on the pressure surfaces 55 and 71 the opposing forces of the helical compression spring are not sufficient 47 or the Bourdon tube 64 to overcome. The sealing edges 54 and 70 are therefore due to their valve seats 56 and 72 so that the fluid connection between the fuel outlet channels 58 and 74 and the annulus 76 , ie ultimately to the high pressure connection 24 and on to the fuel rail 20 , is interrupted. So fuel cannot leak.

If the internal combustion engine is operated in a low load range, only comparatively little fuel from the fuel injection device should be used 22 in the combustion chamber assigned to it 26 reach. Therefore, the pressure sensor 32 and the pressure control valve 34 from the control unit 30 in the fuel rail 20 only a certain but comparatively low fuel pressure in the fuel rail 20 adjusted.

If an injection is to take place, the control valve 28 by a corresponding signal from the control and regulating device 30 open. This increases the pressure in the annulus 76 , and in a corresponding manner, that increases on the printing surface 71 attacking hydraulic force. The stiffness of the Bourdon tube 64 is selected so that the regulated fuel pressure in the annulus 76 the on the printing surface 71 attacking hydraulic force is sufficient to the sealing edge 70 of the second valve element 42 against the force of application by the Bourdon tube 64 from the valve seat 72 to get free. At the same time, the rigidity of the helical compression spring 47 but chosen so that they are now on the printing surface 55 attacking hydraulic force is not sufficient to also the valve element 40 to move.

Because the sealing edge 70 now from the valve seat 72 has released fuel from the pressurized annulus 76 via the radially outer fuel outlet channels 74 from the fuel injector 22 in the combustion chamber assigned to it 26 reach. If the sealing edge 70 from the valve seat 72 is released, the combined guide and sealing section moves 62 , During this movement, it passes through the holding section 48 guided.

To end the injection, the control valve 28 closed again, so the pressure in the annulus 76 sinks and the combined guide and sealing section 62 of the valve element 42 due to the declining force on the pressure surface 71 from the Bourdon tube 64 again with its sealing edge 70 against the valve seat 72 is pressed.

At higher loads of the internal combustion engine, a larger amount of fuel should enter the combustion chamber 26 the internal combustion engine are introduced. It is also advantageous if this amount of fuel enters the combustion chamber at a higher pressure 26 reaches than at low engine load. Therefore, by means of the pressure sensor 32 and the pressure control valve 34 from the control unit 30 a higher pressure in the fuel rail 20 adjusted. If now the control valve 28 opens, not only the sealing edge 70 of the valve element 42 from the valve seat 72 moved away. Due to the higher pressure, this is now sufficient on the printing surface 55 effective force, including the sealing edge 54 against the force of action by the screws compression spring 47 from the valve seat 56 withdraw. Fuel can now also pass through the fuel outlet channel 58 in the combustion chamber 26 reach.

In 4 is another embodiment of a fuel injector 22 shown. Those areas and elements which have equivalent functions to areas and elements of the 2 3 and 3 have the same reference numerals and are not described again in detail.

In contrast to that in the 2 and 3 fuel injector shown 22 the Bourdon tube is supported by the in 4 shown device 22 not on the other valve element 40 but on the housing 36 from. For this purpose, the annular guide section 60 of the valve element 42 axially extended, and the inner wall of the recess 38 lies on the outer wall of the guide section 60 fluid-tight. The housing 36 is in two parts with a lower part 36a and a top 36b , The leadership section 60 supports itself on the upper part 36b from.

Claims (8)

Fuel injector ( 22 ) for an internal combustion engine, in particular for an internal combustion engine with direct fuel injection, with a housing ( 36 ), with one in the housing ( 36 ) existing recess ( 38 ), with at least one in the recess ( 38 ) arranged valve element ( 40 . 42 ), which with a valve seat ( 56 . 72 ) works together with a fuel outlet ( 58 . 74 ) is assigned, the at least one valve element ( 40 . 42 ) of at least one pretensioning device ( 47 . 64 ) to the valve seat ( 56 . 72 ) is acted on, characterized in that at least one pretensioning device fits into the valve element ( 42 ) integral spring section ( 64 ) includes. Fuel injector ( 22 ) according to claim 1, characterized in that they have at least two in the recess ( 38 ) coaxial valve elements ( 40 . 42 ), which each have at least one pretensioning device ( 47 . 64 ) against the valve seat ( 56 . 72 ) are acted upon, the pretensioning device of at least one valve element ( 42 ) one in the valve element ( 42 ) integral spring section ( 64 ) includes. Fuel injector ( 22 ) according to one of claims 1 or 2, characterized in that the spring section ( 64 ) to a sealing section ( 62 ) of the valve element ( 42 ) is welded on. Fuel injector ( 22 ) according to claim 3, characterized in that the spring section ( 64 ) with at least one guide section ( 60 . 62 ) is connected in one piece. Fuel injector ( 22 ) according to one of the preceding claims, characterized in that the spring section is a tubular spring ( 64 ) includes. Fuel injector ( 22 ) according to claim 5, characterized in that the wall of the tube spring ( 64 ) several openings arranged offset to each other ( 65 ) having. Fuel injection device according to one of the preceding claims, characterized in that the spring section ( 64 ) on the housing ( 36b ) supports. Fuel injector ( 22 ) according to one of claims 2 to 6, characterized in that the spring section ( 64 ) on the other valve element ( 40 ) supports.