WO2007098986A1

WO2007098986A1 - Fuel injection valve

Info

Publication number: WO2007098986A1
Application number: PCT/EP2007/050454
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: DE102006009071A1

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 (19). Said valve (19) comprises a valve bolt (22) and a spring sleeve (25) which surrounds a bolt section (23) of the valve bolt (22). The spring sleeve (25) exerts a uniform pressure on a sealing edge (37) of a valve seat body which forms a seal seat with a sealing cone (9) of the valve bolt (22), thus preventing damage to the sealing edge (37).

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 a nozzle needle is indirectly controlled by a valve. In this case, a control chamber is provided, which can be filled by a high-pressure region by means of an inlet throttle and connected via an outlet throttle with a valve chamber. Furthermore, a bypass is provided, via which the valve space communicates directly with the high pressure area. A valve pin serves to control a passage from the valve space to a low pressure area, while controlling the flow through the bypass.

The fuel injection valve known from DE 101 45 862 A1 has the disadvantage that, especially in the unpressurised state, the passage to the low-pressure region can not be completely closed. When commissioning the fuel injection valve, in which the pressure is built up, it can therefore come to a certain delay until a readiness to operate occurs. It is conceivable that a valve spring is used to act on the valve pin in a starting position. However, such a valve spring has the disadvantage that lateral forces occur, so that an undesirable wear on a seat to the low pressure area occurs and possibly damage to the seat caused by cavitation or the like.

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 lateral forces or with vanishing transverse forces in the direction of the starting position, so that wear of a sealing edge 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.

Advantageously, the valve has a valve seat body, which cooperates with a sealing cone of the valve pin to a sealing seat to close the connection between the valve chamber and the low-pressure region via the drain opening. In this case, the sealing seat is preferably formed on a sealing edge of the formed on a valve plate valve seat body, wherein the spring sleeve uniformly acts on the sealing cone of the valve pin against the sealing edge. As a result, the sealing cone is pressed uniformly in the initial state against the sealing edge of the valve seat body, in particular a punctual loading of the sealing edge, as may occur with lateral forces, is prevented, so that wear of the sealing cone and the valve seat body, in particular in the region of the sealing edge, is prevented , In this case, the valve chamber is closed in the initial state with respect to the low-pressure region, so that when the fuel injection valve is put into operation a rapid pressure buildup is made possible and the occurrence of cavitation on the seat is prevented.

It is advantageous that the spring sleeve has at least two recesses extending in a circumferential direction. The recesses allow compression of the spring sleeve and at the same time a flow of fuel so that, for example, fuel from the bypass channel can get into the part of the valve chamber between the spring sleeve and a wall of the valve chamber. The recesses are preferably designed substantially slit-shaped, wherein the slot ends of the recesses are designed rounded to avoid cracks and the like in the material of the spring sleeve. It is particularly advantageous that the Spring sleeve has a plurality of recesses which lie in a same height and which are arranged sequentially in the circumferential direction. For example, two recesses may be provided at a certain height, each having a radian measure of almost 180 °, wherein webs are formed between the recesses. Such webs preferably have at least approximately the same width in the circumferential direction. As a result, a uniform unfolding of the spring force of the spring sleeve is achieved, transverse forces are reliably prevented. At a certain height, however, more than two such recesses may be provided, which preferably have a matching configuration, so that their extent in the circumferential direction is preferably the same.

It is advantageous that the spring sleeve has at several heights in each case such recesses, which are arranged successively in the circumferential direction. As a result, the spring rate of the spring sleeve can be further reduced. In a longitudinal or vertical direction seen adjacent arrangements of recesses are preferably arranged offset in the circumferential direction to each other, so that an occurrence of shear forces is prevented.

The spring sleeve may be formed from a sleeve-shaped metal sheet having, for example, a sheet thickness of 0.1 mm, 0.15 mm or 0.2 mm.

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 shows in Fig. 1 with Il designated section of the fuel injection valve of the first embodiment in further detail and

Fig. 3, the spring sleeve shown in Fig. 2 in a side view. Description of the embodiment

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 housing 2, which is connected to a nozzle body 3. The nozzle body 3 is connected by means of a nozzle lock nut 5 with a holding body 10 of the housing 2. On the nozzle body 3, a needle seat 4 is formed, which cooperates with a nozzle needle 6 to a sealing seat. In this case, the valve needle 6 is formed so that it encloses a control chamber 9 at a side facing away from the sealing seat with a sleeve 7 and a throttle plate 8.

A holding body 5 of the valve housing 2 has a fuel inlet 12, which is connectable by means of a suitable fuel line with a common rail. Through the fuel inlet 12, fuel enters a provided in the interior of the holding body 5 of the valve housing 2 fuel passage 13 and via this into a fuel chamber 14. The fuel passage 13 and the fuel Räum 14 are part of a high pressure area 15. In operation of the fuel injection valve is located in the high pressure area 15th high pressure fuel.

The control chamber 9 is connected via an inlet throttle 16 to the fuel channel 13 of the high-pressure region 15. In addition, an outlet throttle 17 is provided, via which the control chamber 9 is connected to a valve chamber 18 of a valve 19. The valve chamber 18 is formed in a valve plate 20. Furthermore, the valve chamber 18 communicates via a bypass channel 21 with the fuel chamber 14 of the high-pressure region 15. The bypass channel 21 is a bypass 21 and in particular as Bypass bore 21 configured. Therefore, there is a direct connection between the high-pressure region 15 and the valve chamber 18 of the valve 19 via the bypass channel 21. The valve 19 has a valve pin 22 which has a pin section 23 and a sealing cone 24. Furthermore, the valve 19 has a spring sleeve 25, which acts on the sealing cone 24 of the valve pin 22 against a valve seat body 26 of the valve plate 20 with a closing force.

A piezoelectric actuator 30 arranged in the interior of the holding body 5 of the valve housing 2 acts on the valve pin 22 via a hydraulic coupler 31, which may be designed in particular as a stroke transmission device 31. In this case, the valve pin 22 by means of an actuating element (piston) 32, which acts on a contact element 33 of the valve pin 22, against the force of the spring sleeve 25 is acted upon by an actuating force. As a result, a sealing seat formed between the sealing cone 24 and the valve seat body 26 of the valve plate 20 is opened at a sealing edge 37 (FIG. 2), so that a connection between a valve chamber 18 and a low-pressure region 34 is opened.

When starting up the fuel injection valve 1, high-pressure fuel is introduced into the high-pressure region 15. As a result, fuel flows via the inlet throttle 16 into the control chamber 9, so that the pressure in the control chamber 9 increases. Further, fuel flows through the outlet throttle 17 in the valve chamber 18. Due to the force of the spring sleeve 25 which is biased, the sealing seat formed between the sealing cone 24 and the valve plate 20 is closed in the starting position, so that in addition a connection via the bypass channel 21st is open and the pressure in the valve chamber 18 rises rapidly.

Upon actuation of the fuel injection valve 1 by means of the actuator 30, the sealing seat of the valve pin 22 is opened, so that the pressure in the valve chamber 18 drops and fuel flows through the outlet throttle 17 from the control chamber 9. Due to the pressure drop in the control chamber 9, there is an opening of the nozzle needle 6, so that the sealing seat formed between the nozzle needle 6 and the needle seat 4 of the nozzle body 3 is opened and fuel from the fuel chamber 14 via the open sealing seat and at least one nozzle opening 35 from the Fuel injection valve 1 is injected. After actuation of the fuel injection valve 1, the valve pin 22 is reset due to the force of the spring sleeve 25 in the starting position, in which the Connection of the valve chamber 18 is interrupted to the low pressure region 34 and the connection to the high-pressure region 15 is opened via the bypass channel 21, so that a rapid increase in pressure in the valve chamber 18 is generated. It can also come to fill the control chamber 9 with fuel (fuel) via the outlet throttle 17. The conditional increase in the pressure in the control chamber 9 then leads to the closing of the nozzle needle 6, so that the injection process is completed. The valve 19 allows an advantageous specification of the course of injection and in particular short injection times.

Fig. 2 shows the designated in Fig. 1 with Il section of the fuel injection valve 1 in more detail. The bolt portion 23 of the valve pin 22 is provided inside the valve space 18. The sealing cone 24 connected to the bolt portion 23 is partially provided within the valve chamber 18 and closes in the starting position shown in FIG. 2, a drain opening 36 of the valve chamber 18. Via the drain opening 36 of the valve chamber 18 is connected to the low pressure region 34, wherein the compound can be opened and closed by means of the valve pin 22. From the low-pressure region 36, the fuel can be conducted via a return line into a tank of the internal combustion engine. In the initial position shown, a sealing seat is formed between a sealing edge 37 of the control valve seat body 26 of the valve plate 20 and the sealing cone 24, so that the discharge opening (channel) 36 is closed. When the valve pin 22 is actuated against the force of the spring sleeve 25, this sealing seat is opened so that fuel can flow out of the valve chamber 18 into the low-pressure region 36.

The spring sleeve 25 surrounds the pin portion 23 of the valve pin 22 circumferentially, wherein an inner diameter 38 of the spring sleeve 25 is slightly larger than a diameter 39 of the pin portion 23 is selected so that between the pin portion 23 and the spring sleeve 25, a narrow gap 40 of the width 41 is provided , The spring sleeve 25 is centered with respect to an axis 42 of the pin portion 23 of the valve pin 22, wherein due to the small width 41 of the narrow gap 40, a substantial change in the position of the spring sleeve 25 over the life of the fuel injection valve 1 is prevented. In order to achieve a bias of the spring sleeve 25, an installation height Hl of the spring sleeve 25 is selected to be smaller than an initial height HO (FIG. 3). The spring sleeve 25 has a plurality of recesses 43, 44, 45, 46, 47, 48, 49, in order to allow compression of the spring sleeve 25 under a dynamic load. The recesses 43 to 49 also allow a flow of Fuel from the gap 40 in the remaining part of the valve chamber 18. This allows fuel from the bypass passage 21 into the valve chamber 18 flow when an opening 55 of the bypass passage 21 is at least partially open. In the initial state shown in FIG. 2, in which the sealing cone 24 bears against the sealing edge 37, the opening 55 of the bypass channel 21 is maximally opened. Due to the configuration and the number of recesses 43 to 49, the spring rate of the spring sleeve 25 can be specified. The recesses 43 to 49 are distributed uniformly over the spring sleeve 25 in order to achieve a uniform force development of the spring sleeve 25 for the uniform application of the sealing edge 37 by means of the sealing cone 24 of the valve pin 22. Specifically, the loading of the valve pin 22 takes place at least substantially in the direction of the axis 42 and without the occurrence of transverse forces. This also ensures that in the initial state shown in FIG. 2, a complete closure of the drain opening 36 is achieved, so that in particular damages due to cavitation are prevented. The end faces 56, 57 of the spring sleeve 25 are designed flat and optionally ground. As a result, a uniform contact of the spring sleeve 25 is achieved on the throttle plate 8 and the sealing cone 24 so that an axial alignment of the spring sleeve 25 achieved and a uniform force transmission can be achieved.

FIG. 3 shows the spring sleeve shown in FIG. 2 in a side view from the viewing direction designated III in FIG. In this case, in FIG. 3 further recesses 50, 51, 52 of the spring sleeve 25 are shown, while the recesses 48, 49 are located behind the recesses 44 and 46. As a result, at each height 70, 71, 72, 73, 74, which are defined in the direction of the axis 42, two of the recesses 43 to 52. For example, lie at the height 70, the recesses 43, 50, each having an arc length of almost 180 °, so that a web 58 remains with a width 59 between them. The recesses 43, 50 are arranged one after the other in a circumferential direction 60. The recesses 43, 50 closest to the recesses 44, 58, which are arranged at the height 71 are seen in the circumferential direction 60 offset by 90 ° to the recesses 43, 50 arranged to ensure a uniform force development of the spring sleeve 25. Accordingly, the recesses 45, 51, which lie at the height 72, 90 ° offset from the recesses 44, 48 are arranged, so that their arrangement in the circumferential direction 60 seen matches the arrangement of the recesses 43, 50. This also applies to the recesses 47, 52, while the recesses 46, 49 seen in the circumferential direction 60 according to the recesses 44, 48 are arranged.

The recesses 43 to 52 are all configured the same. In particular, the recesses 43 to 52 are formed as slot-shaped recesses, wherein in the region of the ends of the recesses 43, 52 rounded 61 are provided, as shown by the example of the recess 52. By a recess height 62 and provided in the circumferential direction 60 curvature 63 of the recesses 43 to 52, the spring rate of the spring sleeve 25 can be specified within certain limits. However, a substantial influence is made possible by the web width 59 of the web 58 and further webs between the recesses 43 to 52, of which in FIG. 3 the webs 80, 81 are marked. The biasing force of the spring sleeve 25 is determined by the difference between the output length HO and the installation length Hl. In this case, the spring sleeve 25 can be additionally set to at least reduce a decrease in the biasing force over the life of the fuel injection valve 1. The setting of the spring sleeve 25 can be done, for example, by applying the spring sleeve 25 with 1.3 to 1.5 times the biasing force. Together with the choice of a wall thickness of the spring sleeve 25 and the material of the spring sleeve 25, the spring rate of the spring sleeve 25 can be specified with the possibilities described above in a wide range. The spring sleeve 25 can be made, for example, from a seamless drawn pipe section from a sheet with a wall thickness of 0.1 mm, 0.15 mm or 2 mm. The inner diameter 38 of the spring sleeve and the initial height HO can be, for example, a few millimeters each.

The invention is not limited to the embodiment described.

Claims

claims

1. Fuel injection valve (1), in particular injector for fuel injection systems of air-compressing, self-igniting internal combustion engines, with an actuator (30), a valve (19) having a valve chamber (18) and a valve pin (22), a control chamber (9), is connected via an inlet throttle (16) with a high pressure area (15), an outlet throttle (17) which connects the control chamber (9) with the valve chamber (18), a bypass passage (21), the valve space (18) with the High pressure area (15) connects, wherein the valve space (18) has a drain opening (36) through which the valve space (18) with a low pressure region (34) is connected, wherein the valve pin (22) for controlling a flow from the high pressure region (15 ) to the valve space (18) through the bypass passage (21) and for controlling a flow from the valve space (18) to the low pressure area (34) through the drain opening (36) of the valve space (18) by means of the actuator (30) is operable, d adurch in that the valve (19) has a spring sleeve (25), that the spring sleeve (25) at least partially surrounds a bolt portion (23) of the valve pin (22) and in that the spring sleeve (25) the valve pin (22) in the direction a starting position in which the connection between the valve chamber

(18) and the low-pressure region (34) via the discharge opening (36) closed and the connection between the high-pressure region (15) and the valve chamber (18) via the bypass channel (21) is opened.

2. Fuel injection valve according to claim 1, characterized in that the valve

(19) has a valve seat body (26) which cooperates to close the connection between the valve chamber (18) and the low pressure region (34) via the discharge opening (36) with a sealing cone (24) of the valve pin (22) to a sealing seat.

3. Fuel injection valve according to claim 2, characterized in that the sealing seat between the sealing cone (24) and the valve seat body (26) in Initial state at a sealing edge (37) of the valve seat body (26) is formed and that the spring sleeve (25) acts on the sealing cone (24) of the valve pin (22) at least approximately uniformly against the sealing edge (37).

4. Fuel injection valve according to one of claims 1 to 3, characterized in that the spring sleeve (25) has at least one in a circumferential direction (60) extending recess (43 - 52).

5. Fuel injection valve according to claim 4, characterized in that the recess (43 - 52) as at least substantially slot-shaped recess (43 - 52) is configured.

6. Fuel injection valve according to claim 5, characterized in that the recess (43 - 52) is configured rounded at least one end of the slot.

7. Fuel injection valve according to claim 4, characterized in that the spring sleeve (25) in at least a first height (70) has a plurality of recesses (43, 50) which are arranged in the circumferential direction (60) successively.

8. Fuel injection valve according to claim 7, characterized in that between the recesses (43 - 52) webs (58, 80, 81) are formed, wherein the webs (58, 80, 81) in the circumferential direction (60) at least approximately an equal width (59).

9. Fuel injection valve according to claim 7 or 8, characterized in that the recesses (43 - 52) at least approximately have a matching configuration.

10. Fuel injection valve according to one of claims 7 to 9, characterized in that the spring sleeve (25) in a second height (71) a plurality of recesses (44, 48) which are arranged sequentially in the circumferential direction (60), and that in the second height (71) formed recesses (44, 48) in the circumferential direction (60) offset from the in the first height (70) formed recesses (43, 50) are arranged.