EP0927303A1

EP0927303A1 - Fuel injection valve

Info

Publication number: EP0927303A1
Application number: EP98928157A
Authority: EP
Inventors: Jochen Riefenstahl; Henning Teiwes; Gottfried Flik; Ottmar Martin
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1997-06-14
Filing date: 1998-04-08
Publication date: 1999-07-07
Anticipated expiration: 2018-04-08
Also published as: JP2000517029A; DE19725198A1; DE59806618D1; KR20000068103A; EP0927303B1; WO1998058168A1; US6098598A

Abstract

The invention relates to a fuel injection valve (1), in particular an injection valve for fuel injection systems in internal combustion engines, having a valve closing body (9) connected to a valve needle (8), and a valve seat body (3). A valve closing surface (10), fitted on the closing body (9), cooperates with a surface (11) of a valve seat (12) which is formed on the valve seat body (3). In addition, the fuel injection valve (1) has at least one fuel channel (20, 21) in the region of the valve seat body (3) and upstream from the valve seat (12), for feeding fuel to said valve seat (12). The invention is characterized in that a choking point (29) is fitted in every fuel channel (20, 21), and the cross section of the choking point opening can be modified from outside the fuel injection valve (1).

Description

Fuel injector

State of the art

The invention relates to a fuel injector according to the preamble of the main claim. It is already known from DE-PS 49 47 40 a fuel injection valve in which a valve closing body connected to a valve needle interacts with a valve seat body to form a valve seat. To guide the fuel, a substantially axially extending fuel supply line is provided in a nozzle body, which leads into a fuel channel running in the radial direction in the valve seat body. The fuel channel opens into a spray opening in the area of the valve seat.

A newer design of a fuel injection valve for the direct injection of fuel into a cylinder of an internal combustion engine goes, for. B. from DE 196 00 403 AI.

In the known fuel injection valves, it is disadvantageous that the amount of fuel metered by the fuel injection valves is predetermined by the valve lift of the fuel injection valves. The valve lift of the fuel injection valves is, however, only relatively complex in the assembled state of the fuel injection valve and can be changed within narrow limits. The fine adjustment of the metered amount of fuel is therefore relatively complex in the known fuel injection valves.

Furthermore, the fuel distribution within the fuel jet sprayed by the known fuel injection valves is largely radially symmetrical. In practice, however, there are applications in which an asymmetrical fuel distribution within the fuel jet is desirable. So can For example, a different fuel-air mixture composition may be advantageous in the area of the spark plug than in the remaining area of the fuel jet.

Advantages of the invention

The fuel injector according to the invention with the characterizing features of the main claim has the advantage that an exact adjustment of the amount of fuel metered by the fuel injector is possible by specifically changing the opening cross section of a throttle point of the one fuel channel or the plurality of fuel channels in the fully assembled state of the fuel injector. The amount of fuel metered by the fuel injection valves according to the invention can be adjusted fully automatically in a relatively short time with relatively little effort. The manufacturing costs are therefore significantly reduced.

Advantageous further developments and improvements of the fuel injector specified in the main claim are possible through the measures listed in the subclaims.

If several fuel channels distributed circumferentially on the valve seat body are provided and the opening cross sections of the throttle points assigned to the fuel channels can be changed independently of one another, this has the advantage that the fuel distribution in the fuel steel sprayed from the fuel injection valve can be set asymmetrically. In the area with a higher desired fuel density, the opening cross section of the fuel channels arranged there has to be increased accordingly, while in an area with a desired lowered fuel density the opening cross section of the fuel channels arranged there has to be dimensioned accordingly smaller. Due to the resulting asymmetrical design of the fuel jet, the fuel distribution can be adapted to the installation geometry and the special design of the internal combustion engine, e.g. can be adapted to the position of the spark plug and the valves in the case of fuel injectors directly injecting into the cylinder of the internal combustion engine or to the special geometric shape of the intake manifold in the case of fuel injectors injecting into the intake pipe of the internal combustion engine. In particular, the amount of fuel impinging on wall areas of the cylinder or the intake manifold can be reduced, which manifests itself in improved exhaust gas values.

That the fuel distribution within the fuel jet can still be changed in the fully assembled state of the fuel injector is particularly advantageous since the Installation position of the fuel injection valve on the internal combustion engine and the special geometric shape of the components of the internal combustion engine can vary considerably depending on the type of internal combustion engine, ie from vehicle type to vehicle type.

The throttle point can be formed in a particularly advantageous and simple manner in that a nozzle body surrounding the valve seat body in this area from the outside, for. B. is plastically deformable by means of a bolt element and constricts the fuel channel according to its deformation. The opening cross-section of the throttling point can advantageously be set particularly easily by an automatic machine.

It is also particularly advantageous to use a manipulator that can be inserted into the fuel channel, the insertion depth of which defines the opening cross section of the throttle point of the assigned fuel channel. It is particularly advantageous in this development that the opening cross section of the throttle point can be both reduced and enlarged, which simplifies the adjustment process. By welding the manipulator to the valve seat body, a locking and sealing result at the same time.

drawing

Embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description. 1 shows an axial section through a first exemplary embodiment of a fuel injection valve according to the invention shown in excerpts, and FIG. 2 shows an axial section through a second embodiment of a fuel injection valve according to the invention shown in excerpts.

Description of the embodiments

1 shows an axial section through a first exemplary embodiment of a fuel injector 1 designed according to the invention in a partial illustration. Only the spray-side end of the fuel injection valve 1 is shown.

Within a hollow cylindrical nozzle body 2, a valve seat body 3 is arranged at the spray-side end thereof and is sealingly connected to the nozzle body 2 by means of a weld seam 4. The valve seat body 3 is also essentially hollow-cylindrical, the outer diameter of the valve seat body 3 essentially having the inner diameter of the nozzle body 2 coincides, so that the valve seat body 3 is fitted into the inner opening 5 of the nozzle body 2. The valve seat body 3 has a guide bore 7, which serves to guide a valve needle 8, concentrically with its longitudinal axis, which corresponds to the longitudinal axis 6 of the fuel injector 1.

In the exemplary embodiment, the valve needle 8 is cylindrical and is formed in one piece with a valve closing body 9. To reduce the inertial mass, the valve needle 8 can, however, also be designed as a hollow cylinder or from a bent sheet metal part. The valve closing body 9 has a conical valve closing surface 10 which interacts with a likewise conical valve seat surface 11 arranged on the spray-side end of the valve seat body 3 to form an externally closing valve seat 12. The valve needle 8 and the valve closing body 9 connected to the valve needle 8 are along the longitudinal axis 6 by means of a z. B. electromagnetically or piezoelectrically operating actuator with a translational stroke. A not shown, for. B. formed as a return spring holds the valve closing surface 10 of the valve closing body 9 in the closed state of the fuel injector 1 in flush contact with the valve seat surface 10 of the valve seat body 3. The valve seat 12 opening outside is particularly for a fuel injector 1 for direct injection of fuels into a cylinder or Combustion chamber of an internal combustion engine is suitable, since the combustion pressure prevailing in the cylinder acts on the valve closing body 9 in the closing direction and does not lead to an unintentional opening of the fuel injection valve 1.

According to the invention, at least one fuel channel, but preferably a plurality of fuel channels, is provided in the valve seat body 3. The fuel channel consists of a first section 20 running in the radial direction and a second section 21 connected to the first section 20 and running in the axial direction. The first radial section 20 of the fuel channel 20, 21 is part of a through hole 22 which extends from the outer lateral surface 23 of the valve seat body 3 extends through this up to the guide bore 7. The second, axial section 21 of the fuel channel 20, 21 is designed as a blind bore 31 in the exemplary embodiment. In the same way, however, it would also be possible to design the second section 21 of the fuel channel 20, 21 as a through hole and to close it on the spray-side end face 24 of the valve seat body 3 by means of a suitable closing body. The first, radial section 20 of the fuel channel 20, 21 opens into an annular groove 25 formed on the valve needle 8 independently of the stroke position of the valve needle 8. From the opening of the through bore 22 located on the outer lateral surface 23 of the valve seat body 3, a manipulator 26 designed as a stepped cylinder in the exemplary embodiment can be inserted therein. The manipulator 26 has a guide section 27 adapted to the diameter of the through bore 22 and a pin-like section 28 with a reduced diameter. As can easily be seen from FIG. 1, the opening cross section of the fuel channel 20, 21 is reduced the more, the deeper the manipulator 26 into the through hole 22 and thus into the

Fuel channel 20, 21 is introduced. The manipulator 26 therefore forms a throttle point 29 with an adjustable opening cross section. The opening cross section of this throttle point 29 can be varied without further ado even when the fuel injector 1 is in the fully assembled state. After the opening cross section of the throttle point 29 has been set, the manipulator 26 in the exemplary embodiment is sealingly connected to the valve seat body 3 by means of a weld seam 30. As a result, the manipulator 26 is locked on the valve seat body 3 and at the same time prevents fuel from escaping from the through bore 22 to the outside.

Preferably, a plurality of fuel channels 20, 21 are provided in the valve seat body 3, which, for. B. are preferably arranged uniformly distributed on a concentric pitch circle. The throttling points 29 of the individual fuel channels 20, 21 can be adjusted independently of one another by their respective manipulator 26. In this way, a radially asymmetrical fuel distribution can be generated in the fuel jet sprayed from the fuel injection valve 1, since the fuel distribution in the circumferential groove 25 of the valve needle 8 is uneven due to the differently throttled supply of the fuel via the differently throttled fuel channels 20, 21. Such an asymmetrical fuel distribution in the sprayed fuel jet is e.g. B. advantageous if the fuel content in the fuel-air mixture in the area of individual components, for. B. a spark plug, the intake or exhaust valves of the cylinder or the wall areas of the cylinder or the intake manifold should be reduced. In this way, the combustion of the internal combustion engine can be optimized and the exhaust gas values can be significantly improved.

It is particularly advantageous that the variation of the fuel distribution by adjusting the manipulators 26 is still possible in the fully assembled state of the fuel injector 1 and the fuel distribution in the fuel jet sprayed from the fuel injector 1 is e.g. B. can be adapted to the specific geometry of the internal combustion engine or to the vehicle type. FIG. 2 shows a second exemplary embodiment of a fuel injector 1 according to the invention in a sectional, excerpted illustration. Elements which have already been described are provided with the same reference numerals, so that a repetitive description is unnecessary.

The first, radial section 20 of each fuel channel 20, 21 is also formed in the exemplary embodiment shown in FIG. 2 as a radial bore 44 which opens into the annular groove 25 of the valve needle 8. The second axial section 21 of each fuel channel 20,

In the exemplary embodiment shown in FIG. 2, 21 is designed as a groove 40, which is created by flattening 21 of the valve seat body 3. The groove 40 is connected both to the inner opening 5 of the nozzle body 2 and to the first section 20 of the fuel channel 20, 21.

In contrast to the exemplary embodiment shown in FIG. 1, the throttle point 29 is not formed by a manipulator 26, but rather by plastically deforming the wall 41 of the nozzle body 2, which is relatively thin-walled in the region of the throttle point 29. The deformation of the wall 41 can, for. B. take place by means of a bolt element 42 which penetrates into a recess 43 of the nozzle body 2 and engages on the thin-walled wall 41 of the nozzle body 2. The amount of fuel metered by the fuel injector 1 can therefore be fully assembled

State of the fuel injector 1 can be set fully automatically in such a way that the throttle point 29 is gradually narrowed until that of the

Fuel injection valve 1 to be metered amount of fuel is reached. The special one

An advantage of the embodiment according to the invention is that the valve lift does not necessarily have to be changed in order to adjust the amount of fuel metered by the fuel injection valve 1.

Preferably, a plurality of circumferentially distributed grooves 40 are provided on the valve seat body 3, each of which is connected to the annular groove 25 of the valve needle 8 via a radial bore 44. In a manner similar to that already described above with reference to the exemplary embodiment shown in FIG. 1, the individual opening cross sections of the throttle points 29 of the individual grooves 40 can be set independently of one another. This can be done in a machine either in succession by rotating the fuel injection valve 1 about its longitudinal axis 6 and a single bolt element 42 penetrating in time in all the recesses 43, or at the same time by a plurality of bolt elements 42 provided on the machine, which simultaneously set all the throttle points 29. The measured total amount of fuel from the fuel injector can first be adjusted by shifting the Valve seat body 3 and thus adjusting the valve lift can be adjusted and the weld 4 applied to lock the valve seat body 3. Subsequently or possibly also beforehand, a radially asymmetrical fuel distribution can be set at each throttle point 29 by pressing the wall 41 of the nozzle body 2. Furthermore, a fine adjustment of the amount of fuel metered by the fuel injection valve 1 can take place at the same time.

The invention is not restricted to the exemplary embodiments shown. Instead of the

Formation of flattenings 21, the axial grooves 40 can also be milled into the valve seat body 3. It is also possible to use other restricted throttling methods, such as those used for. B. are known from shut-off valves. It is also not absolutely necessary to form the fuel channel 20, 21 or the fuel channels 20, 21 in or on the valve seat body 3. The fuel channels 20, 21 could at least in sections, for. B. can also be arranged in or on the nozzle body 2.

Claims

claims

1. Fuel injection valve (1), in particular injection valve for fuel injection systems of internal combustion engines, with a valve closing body (9) connected to a valve needle (8), the one

Valve closing surface (10), which is formed with a valve seat body (3)

Valve seat surface (11) cooperates to form a valve seat (12), and at least one fuel channel (20, 21) provided in the region of the valve seat body (3) upstream of the valve seat (12) for supplying fuel to the valve seat (12), characterized in that A throttle point (29) is arranged in each fuel channel (20, 21), the

Opening cross section from outside the fuel injector (1) is changeable.

2. Fuel injection valve according to claim 1, characterized in that several in the region of the Ventilitzköφers (3) circumferentially distributed fuel channels (20, 21) are provided, the opening cross sections of the fuel channels (20, 21) associated throttling points (29) independently of one another for training an asymmetrical fuel distribution in a fuel jet sprayed from the fuel injection valve (1) can be changed.

3. Fuel injection valve according to claim 1 or 2, characterized in that a first section (20) of each fuel channel (20, 21) penetrates the valve seat body (3) upstream of the valve seat surface (11) with a radial component.

4. Fuel injection valve according to one of claims 1 to 3, characterized in that an upstream of the first section (20) arranged second section (21) of each fuel channel (20, 21) on or in the valve seat body (3) extends in the axial direction.

5. Fuel injection valve according to claim 4, characterized in that the second section (21) of each fuel channel (20, 21) penetrates the valve seat body (3) in the form of an axial bore (31).

6. Fuel injection valve according to claim 4, characterized in that the second section (21) of each fuel channel (20, 21) on the valve seat body (3) is designed in the form of an axial groove (40).

7. Fuel injection valve according to claim 6, characterized in that the valve seat body (3) is surrounded by a nozzle body (2) which closes the axial groove (40) of each fuel channel (20, 21) to the outside and to change the opening cross section of each throttle point (29) radially in the direction of the valve seat body (3) is plastically deformable.

8. Fuel injection valve according to claim 7, characterized in that the wall (41) of the nozzle body (2) in the region of each throttle point (29) has a reduced wall thickness in order to enable the deformation by a bolt element (42).

9. Fuel injection valve according to one of claims 1 to 8, characterized in that in each fuel channel (20, 21) a manipulator (26) can be inserted, the insertion depth of which defines the opening cross section of the throttle point (29) of the associated fuel channel (20, 21) and which is displaceable from outside the fuel injection valve (1).

10. Fuel injection valve according to claim 9, characterized in that each manipulator (26) with the valve seat body (3) can be welded.

11. Fuel injection valve according to one of claims 1 to 10, characterized in that the valve needle (8) or the valve closing body (9) has an annular groove (25) into which each fuel channel (20, 21) opens.