WO2011026689A1

WO2011026689A1 - Fuel injection device

Info

Publication number: WO2011026689A1
Application number: PCT/EP2010/060609
Authority: WO
Inventors: Nadja Eisenmenger
Original assignee: Robert Bosch Gmbh
Priority date: 2009-09-02
Filing date: 2010-07-22
Publication date: 2011-03-10
Also published as: DE102009029116A1

Abstract

The invention relates to a fuel injection device for injecting fuel into a combustion chamber of an internal combustion engine, having a control valve comprising a valve piece (104) that has a central through-hole (105) having a throttle point and that is clamped against a housing body by means of a valve clamp screw (102). In order to further improve the strength of a fuel injection device under higher pressures, the valve piece (104) has a chamfered shoulder (108) against which a complementary clamping shoulder (109) of the valve clamping screw (102) rests.

Description

description

title

Fuel injection device prior art

The invention relates to a fuel injection device for injecting fuel into a combustion chamber of an internal combustion engine, comprising a control valve, which comprises a valve piece having a central through hole with a throttle point and is clamped by means of a valve clamping screw against a housing body.

Such a fuel injection valve is known from German patent application DE 10 2007 047 152 A1. With increasing pressures, it is becoming increasingly difficult to make the individual components of the fuel injection device high pressure resistant. Components that are still uncritical in terms of strength need to be partially redesigned to withstand the higher pressures. Disclosure of the invention

The object of the invention is to further improve a fuel injection device according to the term of claim 1 in terms of strength under higher pressures.

The object is achieved in a fuel injection device for injecting fuel into a combustion chamber of an internal combustion engine, with a control valve comprising a valve piece having a central through hole with a throttle point and is clamped by means of a valve clamping screw against a housing body, achieved in that the valve piece has a sloping shoulder against which abuts a complementary clamping shoulder of the valve clamping screw. at conventional fuel injection devices, as they are known for example from German patent application DE 10 2007 047 152 A1, the force is applied to the valve piece via a flat shoulder. In the context of the present invention, it has been found that under high pressures inside the valve piece elastic tilting occurs, which can lead to tensile stresses in the interior of the valve piece. In turn, these tensile stresses can in the worst case lead to a failure in the area of the throttle point. The inventive design of the valve piece with the oblique shoulder, which cooperates with the clamping shoulder of the valve clamping screw, the unwanted tensile stresses in the interior of the valve piece can be eliminated or significantly reduced. This unexpected effect of the oblique shoulder on the valve piece is neither anticipated nor suggested by the European patent applications EP 0 569 727 A1 and EP 0 890 734 A2. European Patent Application EP 0 890 734 A2 discloses a fuel injection valve with an annular shoulder which is curved on its side facing an annular shoulder such that a ring-shaped bearing point results at a predetermined distance from a valve member axis, on which the conical annular shoulder in the assembled state is applied. European Patent Application EP 0 569 727 A1 discloses a fuel injection nozzle with a pipe socket, which has a convex cone at an outlet end and a convex shoulder in the middle region, against which a hollow cap screw presses.

A preferred embodiment of the fuel injection device is characterized in that the oblique shoulder is designed as a chamfer radially outward at a combustion chamber remote end of the valve piece. At an end near the combustion chamber, the valve piece has a planar end face, with which the valve piece bears against the housing body of the fuel injection device. Another preferred embodiment of the fuel injector is characterized in that the oblique shoulder includes a helix angle of 15 to 70 degrees to a transverse plane that is perpendicular to a longitudinal axis of the fuel injector. The helix angle is more preferably 15 to 45 degrees. In the context of the present invention, a helix angle of about 30 degrees has proved to be particularly advantageous. Another preferred embodiment of the fuel injection device is characterized in that the valve clamping screw has an external thread with which the valve clamping screw is screwed into a housing of the fuel injection device. When screwing the valve clamping screw into the housing, radial forces are transmitted via the clamping shoulder in addition to axial preload forces.

A further preferred embodiment of the fuel injection device is characterized in that the oblique shoulder is arranged in the vicinity of the throttle point. The oblique shoulder is arranged on the valve piece, preferably radially outside the throttle point.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, an embodiment is described in detail.

Short description of the drawing

Show it:

Figure 1 is a partial sectional view of a conventional fuel injection device and

FIG. 2 shows a simplified representation of an enlarged section of a valve piece with a valve clamping screw from FIG. 1.

Description of the embodiment

FIG. 1 shows a section of a fuel injection device 1 designed as a common-rail injector, which is also referred to as an injector, for injecting fuel into a combustion chamber of an internal combustion engine of a motor vehicle. A high-pressure pump 2 delivers fuel from a reservoir 3 into a high pressure fuel accumulator 4. In this fuel, especially diesel or gasoline, under high pressure, stored in this embodiment about 2000 bar. To the high-pressure fuel accumulator 4, the injector 1 is next to other, not shown, injectors via a supply line 5 an closed. The supply line 5 opens into a pressure chamber 6 of the injector 1 and flows from there in an injection process directly into the combustion chamber of the internal combustion engine. The injector 1 is connected via an injector return valve 7 to a return line 8, which leads to the reservoir 3. Through the return line 8, a later to be explained control amount of fuel flow from the injector 1 to the reservoir 3 and are fed from there from the high pressure circuit again.

Within a housing part or housing body 9, an injection valve element 10 which is integral in this exemplary embodiment and which may also be designed in several parts, can be adjusted in the axial direction. In this case, the injection valve element 10 is guided within a nozzle body, not shown, clamped to the housing part 9 on its outer periphery. This nozzle body, not shown, is preferably clamped by means of a union nut, also not shown, with the housing part 9.

The injection valve element 10 has at its (lower) tip (not shown) a closing surface with which the injection valve element 10 can be brought into tight engagement with an injection valve element seat (not shown) formed within the nozzle body.

When the injection valve element 10 bears against its injection valve element seat, that is to say is in a closed position, the fuel outlet is blocked from a nozzle hole arrangement (also not shown) within the nozzle body. On the other hand, if it is lifted from its injection valve element seat, can

Fuel from the pressure chamber 6 to flow past the injection valve element seat to the nozzle hole assembly and there, are substantially injected under high pressure, injected into the combustion chamber. From a in the drawing plane upper portion 1 1 of the injection valve member 10 and a lower in the drawing plane, sleeve-shaped portion 12 of a valve body 13, which is also referred to as a valve piece, a control chamber 14 is limited, via a radially in the sleeve-shaped portion 12 of the valve body 13 extending inlet throttle 15 is supplied with high-pressure fuel from the pressure chamber 6 h. The sleeve-shaped section 12 with the control chamber 14 enclosed therein is radially outward of The high-pressure fuel enclosed, so that an annular guide gap 16 is comparatively fuel-tight radially between the sleeve-shaped portion 12 and the injection valve member 10. The control chamber 14 is connected via a arranged in the valve body 13 drain passage 17 with outlet throttle 18 hydraulically connected to a valve chamber 19 which is bounded radially outwardly by an axially adjustable valve sleeve 20 of a pressure-balanced in the axial direction of the control valve 21. The axial pressure balance of the control valve 21 is achieved in that the inner guide diameter D-ι the valve sleeve

20 corresponds at least approximately to the diameter D _{2 of} an annular sealing line, by means of which the valve sleeve 20 in the closed state rests against a control valve seat 22 which is formed on the valve body 13. From the valve chamber 19 fuel can then flow into a low-pressure region 23 of the injector 1 and from there to the injector return port 7, when the valve sleeve 20, which is formed integrally with an anchor plate 24 in the embodiment shown, from its formed on the valve body 20 control valve seat 22nd is lifted, that is, the control valve 21 is open. For adjusting the valve sleeve 20 in the drawing plane upwards, an electromagnet arrangement 25 is provided, which has an electromagnet 26, which is held in a holding body 27. The electromagnet 26 interacts with the armature plate 24, which is arranged in an armature space 28, wherein the armature space 28 via a ring member 29 of an axially adjacent to the armature space 28 arranged annular space 30, the lower the valve sleeve 20 in a plane in the drawing Section radially outwardly encloses, is separated. Due to the one-piece design of armature plate 24 and valve sleeve 20 or alternatively by a firm connection between the armature plate 24 and the valve sleeve 20, lifts the valve sleeve 20 when energized electromagnet arrangement25 of its arranged on the valve body 13, formed in this embodiment as a flat seat, Control valve seat 22 from. The flow cross sections of the inlet throttle 15 and the outlet throttle 18 are matched to one another such that when the control valve 24 is open, a net outflow of fuel from the control chamber 14 via the valve chamber 19 in the low pressure region 23, more precisely in the annular space 30, the injector 1 and from there to the injector return port 7 and through the return line 8 in the Vor- storage tank 3 flows. As a result, the pressure in the control chamber 14 decreases rapidly, whereby the injection valve element 10 lifts off from its injection valve element seat, so that fuel can subsequently flow out of the pressure chamber 6 through the nozzle yoke arrangement into the combustion chamber.

To end the injection process, the energization of the solenoid assembly 25 is interrupted, whereby the valve sleeve 20 by means of a support plate 24 supported on the control closing spring 31, which is mostly within a centrally disposed within the solenoid assembly 25, spring chamber 32 is included in the drawing level down on its control valve seat 22 is adjusted. The fuel flowing in through the inlet throttle 15 into the control chamber 14 ensures a rapid increase in pressure in the control chamber 14 and thus for a force acting on the injection valve element

Closing force. The resulting closing movement of the injection valve element 10 is assisted by a closing spring (not shown), which is supported at one circumferential collar of the injection valve element 10 and at the other end at a lower, not shown end side of the valve body 13.

The fuel injection device 1 shown in Figure 1 has a longitudinal axis 101 along which the injection valve element 10 is movable back and forth. The valve body 13, also referred to as valve piece, is braced against the housing body 9 with the aid of a valve clamping screw 40. The drainage channel 17 with the outlet throttle 18 represents a central through hole which runs along the longitudinal axis 101.

In Figure 2, a valve clamping screw 102 is shown in fragmentary and greatly simplified in half section with a valve member 104. The valve piece 104 has a central through-hole 105, which corresponds to the outlet channel 17 with the outlet throttle 18 in FIG. The central through-hole 105 has a throttle point 106. According to one essential aspect of the invention, a helical shoulder 108 is formed on the valve piece 104 in the vicinity of the throttle point 106, against which a clamping shoulder 109 of the valve clamping screw 102 bears under tension. By cooperating with the clamping shoulder 109 oblique shoulder 108 on the valve member 104 undesirable tensile stresses in the interior of the valve member 104, in particular at the throttle point 106 can be eliminated.

Claims

claims

1 . A fuel injection device for injecting fuel into a combustion chamber of an internal combustion engine, comprising a control valve comprising a valve piece (13; 104) having a central through hole (17; 105) with a throttle point (18) and by means of a valve clamping screw (40; 102 ) is clamped against a housing body (9), characterized in that the valve piece (104) has a sloping shoulder (108) on which a complementary clamping shoulder (109) of the valve clamping screw (102) rests.

2. Fuel injection device according to claim 1, characterized in that the oblique shoulder (108) is designed as a chamfer radially outward at a combustion space distant end of the valve piece (104).

3. Fuel injection device according to one of the preceding claims, characterized in that the inclined shoulder (108) includes a helix angle of 15 to 70 degrees to a transverse plane which is perpendicular to a longitudinal axis (101) of the fuel injection device (1).

4. Fuel injection device according to claim 3, characterized in that the helix angle is 15 to 45 degrees.

5. Fuel injection device according to one of the preceding claims, characterized in that the valve clamping screw (104) has an external thread, with which the valve clamping screw (104) is screwed into a housing of the fuel injection device (1).

6. fuel injection device according to any one of the preceding claims, characterized in that the oblique shoulder (108) in the vicinity of the throttle point (106) is arranged.