WO2007098985A1

WO2007098985A1 - Fuel injection valve

Info

Publication number: WO2007098985A1
Application number: PCT/EP2007/050451
Authority: WO
Inventors: Uwe Bruetsch; Dietmar Uhlmann; Christoph Radsak
Original assignee: Robert Bosch Gmbh
Priority date: 2006-02-28
Filing date: 2007-01-17
Publication date: 2007-09-07
Also published as: DE102006009069A1

Abstract

The invention relates to a fuel injection valve (1) which is used, in particular, as an injector for fuel-injection systems of air-compressing, self-igniting internal combustion engines, comprising an actuator (30) which controls the pressure in a control chamber (9) by means of a stroke transmission device (31) and a valve (18). Said valve (18) comprises a valve bolt (21) and a spring element (22). Said valve bolt (21) comprises a bolt part (24) and a spherical element which is pressed into a recess (43) of the bolt part (24). The spherical element (23) is pressed against a sealing edge (42) of the valve (18) through the spring element (22) by means of the bolt part (24). As a result, the spherical element (23) enables the valve (18) to operate in a reliable manner.

Description

description

Title fuel injector

State of the art

The invention relates to a fuel injection valve for fuel injection systems of internal combustion engines. Specifically, the invention relates to an injector for fuel injection systems of air-compressing, self-igniting internal combustion engines.

From DE 101 45 862 Al a fuel injection valve is known, in which an actuator by means of a valve controls the pressure in a control chamber, wherein in response to the pressure in the control chamber actuation of a valve needle for spraying of fuel. In this case, the control chamber is connected via an inlet throttle with a high-pressure region and an outlet throttle with a valve chamber of the valve. Furthermore, the valve chamber is connected via a bypass directly to the high pressure area. A valve pin serves to control the passage via the bypass and at the same time controls a passage to a low pressure area. To control the passage from the valve space to the low pressure area, the valve pin cooperates with a seat.

The fuel injection valve known from DE 101 45 862 A1 has the disadvantage that, in the unpressurized state, the seat may not be completely closed to the low-pressure region by means of the valve pin. As a result, the pressure build-up in the valve chamber during commissioning of the fuel injection valve can be delayed because part of the fuel to Low pressure area drains off. It is conceivable that a valve spring is used, which adjusts the valve pin in a desired starting position. However, such a valve spring has the disadvantage that lateral forces occur that cause undesirable wear on the seat. In a partial open position of the valve may also damage the seat, in particular by cavitation caused.

Disclosure of the invention

Advantages of the invention

The fuel injection valve according to the invention with the features of claim 1 has the advantage that the valve pin is at least substantially applied without transverse forces or with vanishing transverse forces in the direction of the starting position, so that wear of a sealing edge or the like is reduced to the low pressure region. Damage to the seat, for example due to cavitation, can also be prevented or reduced.

The measures listed in the dependent claims advantageous developments of the fuel injection valve specified in claim 1 are possible.

It is advantageous that the valve, which may be configured in particular as a switching valve, having a valve pin which cooperates to close the connection between the valve chamber and the low-pressure region via the drain opening with the ball element of the valve pin to a sealing seat. In this case, the sealing seat between the ball element and the valve seat body is preferably formed on a sealing edge of the control valve seat body, wherein the spring element uniformly urges the ball element by means of the bolt part of the valve pin against the sealing edge. Due to the uniform loading of the sealing edge in particular punctual loads of the sealing edge, as they can occur at shear forces prevented, so that wear of the valve seat body is prevented, especially in the region of the sealing edge. In addition, a reliable closing of the connection between the valve chamber and the low-pressure region is ensured, which allows a rapid pressure build-up when putting the fuel injection valve and prevents the occurrence of cavitation on the seat to the low pressure area. Furthermore, the sealing edge can be designed simply by the configuration of the ball element as at least partially spherical ball element, since in particular a precise compliance with a specific seat geometry due to the ball seat is not required. Furthermore, the diameter of the sealing edge can be easily adapted to the existing requirements.

In an advantageous manner, the ball element of the valve pin is pressed into the recess of the bolt part of the valve pin facing the outlet opening. Characterized a phase shift in the movement of the ball member and the bolt member is prevented during the actuation of the valve pin, so that a reliable operation of the control valve is ensured. This is particularly advantageous in combination with a spring element which is also firmly connected to the bolt part.

For actuating the control valve member, the actuator acts in an advantageous manner via an actuating element on the ball element of the valve pin, wherein a contact surface of the actuating element bears against the ball element. It is advantageous that the contact surface of the actuating element and the surface of the ball element facing the contact surface are adapted to each other. For example, a planar configuration of the contact surface and a planar configuration of the ball element adapted thereto on the side of the contact surface of the actuating element by a flat flattening are advantageous. This configuration allows within certain limits a radial degree of freedom between the actuating element and the ball element, wherein a cost-effective design with certain tolerances is possible. Also advantageous is an embodiment of the contact surface of the actuating element as a matched to the geometry of the ball element, concave contact surface. It is possible that the ball element is designed as a solid ball, which allows a cost-effective design of the control valve.

It is advantageous that the spring element has a sleeve-shaped end portion which encloses a peripheral step of the bolt part of the valve pin circumferentially. In this case, a fixed connection may be formed by pressing the sleeve-shaped end portion of the spring element on the peripheral step of the bolt part. Due to the peripheral step, a centering of the spring element is ensured with respect to the bolt part, so that the occurrence of transverse forces is prevented. The fixed connection prevents phase shifts in the oscillatory movement of the bolt part and spring element, so that the function of the valve is improved.

drawing

Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings, in which corresponding elements are provided with corresponding reference numerals. It shows:

Fig. 1 shows a first embodiment of an inventive

Fuel injection valve in a partial schematic sectional view.

Fig. 2 denoted in Fig. 1 with Il section of the

Fuel injection valve of the first embodiment in more detail and Fig. 3, the control valve member shown in Fig. 2 and an actuating element in a partial representation according to a second embodiment of the invention.

Description of the embodiments

Fig. 1 shows an embodiment of a fuel injection valve 1 of the invention in a partial, schematic sectional view. The fuel injection valve 1 can serve, in particular, as an injector for fuel injection systems of mixture-compression, self-igniting internal combustion engines. In particular, the fuel injection valve 1 is suitable for commercial vehicles or passenger cars. A preferred use of the fuel injection valve 1 is for a fuel injection system with a common rail, the diesel fuel under high pressure leads to a plurality of fuel injection valves 1. However, the fuel injection valve 1 according to the invention is also suitable for other applications.

The fuel injection valve 1 has a multi-part valve housing 2, which is connected to a nozzle body 3. In this case, a nozzle retaining nut 5 is screwed to a holding body 26 of the housing 2 in order to connect the nozzle body 3 to the housing 2. A needle seat 4 formed on the nozzle body 3 interacts with a nozzle needle 6 to form a sealing seat. The nozzle needle 6 closes at a distal end of the sealing seat with a sleeve 7 and a throttle plate 8 a control chamber 9 a. In the operation of the fuel injection valve 1 is located in the control chamber 9 under a certain pressure standing fuel. Depending on the pressure prevailing in the control chamber 9 of the fuel pressure actuation of the nozzle needle 6 takes place, which opens at a low pressure in the control chamber 9 of the formed between the nozzle needle 6 and the needle seat 4 sealing seat so that fuel from a fuel chamber 10 on the opened sealing seat and at least one injection hole 11 is sprayed into the combustion chamber of an internal combustion engine. The fuel injection valve 1 also has a fuel inlet nozzle 12 shown in simplified form, which can be connected to a common rail or the like by means of a suitable fuel line. The fuel passes into a fuel channel 13 provided in the interior of the housing 2 via the fuel inlet connection 12 and into the fuel chamber 10. The fuel channel 13 and the fuel chamber 10 form a high-pressure region 14 in which high-pressure fuel is provided during operation of the fuel injection valve 1 is.

The control chamber 9 is connected on the one hand via an inlet throttle 15 to the fuel passage 13 of the high-pressure region 14. On the other hand, the control chamber 9 via an outlet throttle 16 with a valve chamber 17 of a valve

18 connected. The valve 18 is preferably designed as a switching valve 18. Via a bypass channel 19, a connection of the fuel chamber 10 of the high-pressure region 14 with the control valve chamber 17, bypassing the inlet throttle 15, the control chamber 9 and the outlet throttle 16 is possible. The bypass channel 19 is designed as a bypass 19 and in particular as a bypass bore 19. The inlet throttle 15, the outlet throttle 16 and the bypass channel

19 are formed in the throttle plate 8.

The valve 18 is disposed within a valve plate 20 of the fuel injection valve 1. The valve 18 has a valve pin 21 and a spring element 22. The valve pin 21 comprises a ball element 23 and a pin part 24, wherein the ball element 23 is pressed into the pin part 24. The ball element 23 of the valve pin 21 cooperates with a valve seat body 25, which is formed on the valve plate 20, to form a sealing seat. The structure and the design of the valve 18 are described in more detail with reference to FIG. 2.

The fuel injection valve 1 also has a piezoelectric actuator 30 which is arranged in the interior of the housing 2 and which is connected via a hydraulic coupler 31, which in particular acts as a stroke transmission device 31 can be configured, with the valve pin 21 via an actuating element 32 of the hydraulic coupler 31 is in operative connection. Upon actuation of the actuator 30, the valve pin 21 is adjusted against the force of the spring element 22 by means of the actuating element 32 so that the seal formed between the ball member 23 and the valve seat body 25 is opened, whereby a pressure of the fuel in the valve chamber 17 drops and fuel from the Control chamber 9 flows via the outlet throttle 16 in the valve chamber 17. In this case, the pressure in the control chamber 9 is reduced, whereby it comes to injecting fuel from the fuel chamber 10 via the nozzle opening 11. When returning the valve pin 24 and in particular of the pressed into the pin member 24 ball member 23 of the valve pin 24 by the force of the spring element 22 in the starting position in which the seal formed between the ball member 23 and the valve seat body 25 is closed, fuel flows from the high-pressure region 14th via the bypass passage 19 in the valve chamber 17, so that the pressure in the valve chamber 17 increases rapidly. It can also come to a reflux of fuel from the valve chamber 17 into the control chamber 9 via the outlet throttle 16. The conditional rise of the pressure in the control chamber 9 then leads to the closing of the fuel injection valve 1, so that the injection process is completed. The valve 18 allows an advantageous specification of the course of the injection, even for short injection times.

Fig. 2 shows the designated in Fig. 1 with Il section of the fuel injection valve 1 in more detail. A connection between the valve chamber 17 and a low-pressure region 40 via a drain opening 41 can be opened and closed by means of the valve pin 21, wherein the ball element 23 rests in the closed state against a sealing edge 42 which is provided on the valve seat body 25. A bolt part 24 of the valve pin 21 is arranged within the valve chamber 17 and has a drain opening 41 facing recess 43 into which the ball element 23 is inserted. In this case, the ball element 23 is pressed into the recess 43 of the bolt part 24 in order to achieve a firm connection between the ball element 23 and the bolt part 24. The bolt part 24 also has a peripheral step 44, on the spring element 22 is pressed with a sleeve-shaped end portion 45. By the circumferential step 44, on the one hand, a centering of the spring element 22 with respect to an axis 46 of the bolt part 24 of the valve pin 21 is achieved, whereby the uniform application of the sealing edge 42 is improved due to the force of the spring element 22. On the other hand, a phase shift in the oscillatory movement of the bolt part 24 and the spring element 22 is excluded by the connection between the sleeve-shaped end portion 45 of the spring element 22 and the peripheral step 44 of the bolt part 24. As a result, the operation of the valve 18 is further improved.

2, in which the sealing seat formed between the ball element 23 and the sealing edge 42 of the valve seat body 25 is closed, an opening 47 of the bypass passage 19 is released, so that the connection between the bypass passage 19 and the valve space 17th is opened, wherein fuel from the bypass channel 19 provided in the spring element 22 recesses 48, 49, of which in FIG. 2, for the sake of simplicity, only the recesses 48, 49 are marked, is possible. Due to the circumferential step 44, an annular gap 50 between the spring element 22 and the pin member 24 is also formed, which allows an unobstructed power delivery of the spring element 22.

For actuating the valve pin 21 with the pressed-in ball element 23, the ball element 23 is acted upon against the force of the spring element 22, wherein an actuating element 32 of the hydraulic coupler 31 acts on a contact surface 51 of the actuating element 32 on a flat surface 52 of the ball element 23 , By actuating the valve pin 21, the sealing seat formed between the ball element 23 and the sealing edge 42 is opened so that fuel can flow out of the valve chamber 17 via the discharge opening 41 into the low-pressure region 40. At the same time the bypass channel 19 is at least partially closed, so that the Nachfließen of fuel from the high-pressure region 14 via the bypass passage 19 into the valve chamber 17 is at least reduced. As a result, takes the pressure in the valve chamber 17 from, so that the pressure of the fuel in the control chamber 9 decreases and it comes to spraying of fuel through the injection hole 11 from the fuel injector 1.

After actuation of the valve pin 21 by means of the actuating element 32 of the hydraulic coupler 31 takes place due to the force of the spring element 22, a provision of the valve pin 21 in the starting position shown in FIG. In this case, the outflow opening 41 is closed and the opening 47 of the bypass channel 19 is released again, so that fuel flows into the valve chamber 17 and the pressure of the fuel in the valve chamber 17 increases. This completes the injection process.

In the mounted state of the fuel injection valve 1, the position of the sealing edge 42 with respect to a predetermined ideal position with respect to a predetermined axis 46 of the valve pin 41 may be both slightly offset radially and slightly inclined. Due to the planar configuration of both the contact surface 51 of the actuating element 32 and the flat flattening 52 of the ball member 23, a certain displacement of the axis 46 of the valve pin 21 in a radial direction is possible. In addition, the hydraulic coupler 31 is preferably designed so that when actuated actuator 30 at least largely unpressurized concerns the actuator 32 to the ball member 23, so that due to the flexible design of the spring member 22 has a certain inclination of the pin member 24 with respect to the axis 46 is allowed to close the ball seat formed between the ball member 23 and the sealing edge 42. Thus, the described embodiment allows tolerance compensation at least within certain limits. In this case, certain wear and tear, which occur during the life of the fuel injection valve 1, can be compensated.

FIG. 3 shows the valve pin 21 of the valve 18 shown in FIG. 2 and the actuating element 32 in an excerpted, partially sectioned illustration according to a second exemplary embodiment of the invention. In this Embodiment, the contact surface 51 on the fully spherical geometry of the ball member 23 adapted concave contact surface 51. As a result, the contact surface 51 bears against the surface 53 of the ball element 23 when the valve pin 21 is actuated. The ball element 23 can thereby be configured as a solid ball and is therefore inexpensive to produce. When pressing in the spherical ball element 23 results in an overall height 60 of the valve pin 21, so that the ball member 23 protrudes by a Vorstehlänge 61 via an end face 62 of the pin member 24. To compensate for certain tolerances when pressing the ball member 23 into the recess 43, the Vorstehlänge 61 and / or the total height 60 can be determined to adjust a valve lift of the valve 18 individually. An initial length HO of the spring element 22 pressed onto the circumferential step 44 is selected to be somewhat greater than an installation length H 1 (FIG. 2) in order to ensure a certain prestressing of the spring element 22. This bias caused in the pressureless state of the fuel injection valve 1, that the valve pin 21 is moved to the starting position shown in FIG. 2, in which the formed between the ball member 23 and the sealing edge 42 sealing seat is closed.

The invention is not limited to the described embodiments. In particular, the pin member 24 may also be configured so that it is guided with a side surface 63 on an inner wall 64 of the valve chamber 17, wherein suitable longitudinal grooves are provided in the region of the side surface 63 on the pin member 24 to a flow of fuel in the direction of the discharge opening 41 to allow. Furthermore, the ball element 23 may be cylindrically shaped, in particular in the region of the recess 43, in order to allow a rotation-proof press-fitting of the ball element 23 into the recess 43 of the bolt part 24.

Claims

claims

1. Fuel injection valve (1), in particular injector for

Fuel injection systems of air-compressing, self-igniting internal combustion engines, comprising an actuator (30), a valve (18) having a valve chamber (17) and a valve pin (21), a control chamber (9) via an inlet throttle (15) with a high-pressure region (14), an outlet throttle (16) which connects the control chamber (9) with the valve chamber (17), a bypass passage (19) connecting the valve chamber (17) to the high-pressure region (14), wherein the valve chamber (16) 17) has a drain opening (41) through which the valve space (17) is connected to a low pressure area (40), the valve pin (21) for controlling a flow from the high pressure area (14) to the valve space (17) through the bypass passage (19) and for controlling a flow from the valve chamber (17) to a low-pressure region (40) through the outflow opening (41) of the valve chamber (17) by means of the actuator (30) is actuated, characterized in that the valve pin (21) a Bol Zenteil (24) and a ball element (23), that the ball element (23) is at least partially spherical in shape, that the bolt part (24) has a the discharge opening (41) facing recess (43) into which the ball element (23) is inserted, that a spring element (22) is provided, which acts on the bolt part (24) in the direction of a starting position in which the connection between the valve chamber (17) and the low-pressure region (40) via the discharge opening (41) by means of the ball element ( 23) of the valve pin (21) is closed and the connection between the high-pressure region (14) and the valve chamber (17) via the bypass channel (19) is opened.

2. Fuel injection valve according to claim 1, characterized in that the valve (18) has a valve seat body (25) for closing the connection between the valve chamber (17) and the low-pressure region (40) via the outflow opening (41) with the ball element ( 23) of the valve pin (21) cooperates to a sealing seat.

3. Fuel injection valve according to claim 2, characterized in that the sealing seat between the ball element (23) and the valve seat body (25) on a sealing edge (42) of the valve seat body (25) is formed and that the spring element (22), the ball element (23) acted upon by the valve pin (24) at least approximately uniformly against the sealing edge (42).

4. Fuel injection valve according to one of claims 1 to 3, characterized in that the ball element (23) in the outlet opening (41) facing recess (43) of the bolt part (24) is pressed.

5. Fuel injection valve according to one of claims 1 to 4, characterized in that the actuator (30) for actuating the valve pin (21) at least indirectly actuates an actuating element (32) having a contact surface (51) by means of which the actuating element (32 ) rests against the ball element (23) at least for actuating the valve pin (21).

6. Fuel injection valve according to claim 5, characterized in that the abutment surface (51) is designed as an at least substantially planar contact surface (51) and that the ball element (23) faces the abutment surface (51), at least substantially flat flattening (52). wherein the actuating element (32) for actuating the valve pin (21) with the contact surface (51) of the actuating element (32) on the flattening (52) of the ball element (23) acts on the valve pin (21).

7. Fuel injection valve according to claim 5, characterized in that the contact surface (51) is designed as a geometry adapted to the ball element (23), concave contact surface (51).

8. Fuel injection valve according to one of claims 1 to 7, characterized in that the spring element (22) has a sleeve-shaped end portion (45) that the bolt part (24) has a peripheral step (44) and that the sleeve-shaped end portion (45) surrounding circumferential step (44) of the bolt part (24) circumferentially.

9. Fuel injection valve according to claim 8, characterized in that the spring element (22) with its sleeve-shaped end portion (45) on the peripheral step (44) of the bolt part (24) is pressed.

10. Fuel injection valve according to claim 9, characterized in that the spring element (22) as at least substantially sleeve-shaped spring element (22) is configured and that the sleeve-shaped spring element (22) has at least one recess (48, 49).