JP2004076733A - Fuel injection valve used for internal combustion engine - Google Patents

Abstract

An object of the present invention is to reduce the mass of a valve needle and the wear between a valve sealing surface and a valve seat.
The valve needle (10) has at least two lateral holes (40) in its piston-like section (110, 210, 310).
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection valve used for an internal combustion engine, wherein a valve body is provided, and a valve needle is disposed in a hole provided in the valve body so as to be movable in a longitudinal direction. Has a piston-like section and a substantially conical valve sealing surface at the end facing the combustion chamber, in which the valve needle cooperates with a valve seat, This is of the type adapted to control the opening of at least one injection opening.
[0002]
[Prior art]
A fuel injector of this type is known, for example, from DE 100 24 703 A1. This known fuel injection valve has a valve body. A valve needle is disposed in a hole provided in the valve body so as to be movable in a longitudinal direction. In this case, the valve needle has a piston-like section and transitions at the end on the combustion chamber side into a substantially conical valve sealing surface. The valve needle cooperates at its valve sealing surface with a valve seat formed in the valve body, thereby controlling the opening of the at least one injection opening.
[0003]
However, in this case, the known fuel injection valve has a relatively large mass of the valve needle, which limits the speed of the opening and closing movement and requires a large force to move the needle. Has disadvantages. Thus, the high mass of the valve needle limits the opening and closing speed of the fuel injector and thus the minimum effort in time between two injections. Furthermore, known valve needles are designed to be relatively rigid. As a result, the valve needle vibrates when the valve seat needle is mounted on the valve seat. This vibration results in wear between the valve sealing surface and the valve seat.
[0004]
[Patent Document 1]
DE 100 24 703 A1 [0005]
[Problems to be solved by the invention]
It is therefore an object of the present invention to improve a fuel injection valve of the type mentioned at the outset used in internal combustion engines so that the mass of the valve needle and the wear between the valve sealing surface and the valve seat are reduced. It is to be.
[0006]
[Means for Solving the Problems]
In accordance with an embodiment of the invention, the valve needle has at least two lateral holes in its piston-like section.
[0007]
【The invention's effect】
The fuel injection valve according to the present invention having the features described in claim 1 can appropriately adjust the longitudinal rigidity of the valve needle as compared with the conventional fuel injection valve, and the valve needle has a known mass. Has the advantage that it is significantly reduced. For this purpose, the valve needle has at least two transverse holes in its piston-like section. Due to the reduced mass of the valve needle, greater dynamics of the valve needle and thus faster opening and closing of the fuel injector can be achieved without changing the material. This allows for a rapid succession of successive injections, thereby allowing an injection divided into a plurality of partial injections. On the other hand, due to the reduced longitudinal stiffness of the valve needle, it is achieved that the pressure oscillations that occur when the valve needle impinges on the valve seat are absorbed and compensated by the valve needle. As a result, a reduction in wear between the valve sealing surface and the valve seat is achieved, so that the service life of the fuel injector is extended.
[0008]
The dependent claims enable advantageous configurations of the subject of the invention.
[0009]
In a first advantageous configuration, a plurality of lateral holes are formed in the valve needle, and adjacent lateral holes are circumferentially offset from one another by a certain angle. This configuration of the transverse holes reduces longitudinal stiffness without the transverse stiffness indicating a preferred direction. In this case, it is particularly advantageous if the angle of the transverse holes adjacent to one another is set at least approximately 90 °.
[0010]
In another advantageous embodiment, the transverse bore has a diameter dimensioned between 0.2 and 0.4 times the diameter of the valve needle. This results, on the one hand, in a significant reduction in weight and, on the other hand, very little mechanical weakening of the valve needle and thus even a virtually constant load resistance.
[0011]
Further advantages and advantageous configurations of the subject of the invention can be gleaned from the description and the brief description of the drawings.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0013]
FIG. 1 shows a longitudinal section of a fuel injection valve according to the invention. The valve body 1 is tightened against the valve holder 2 via the throttle disk 3. This is done by the clamping nut 5. The tightening nut 5 is in contact with the valve body 1 and is screwed to the valve holder 2. A hole 8 is formed in the valve body 1. The bore 8 is delimited at its combustion chamber end by a substantially conical valve seat 19. A plurality of injection openings 17 depart from this valve seat 19. These injection openings 17 open into the combustion chamber of the internal combustion engine at the position where the fuel injection valve is installed. A piston-shaped valve needle 10 is disposed in the hole 8 so as to be movable in the longitudinal direction. This valve needle 10 has a longitudinal axis 11. At the end of the valve needle 10 on the combustion chamber side, a substantially conical valve sealing surface 22 is arranged. The valve needle 10 cooperates with the valve seat 19 at this valve sealing surface 22. The valve needle 10 has a guide section 210. In this guide section 210 the valve needle 10 is guided in the guide section 108 of the bore 8. The guide section 210 of the valve needle 10 is provided with a plurality of grinding sections 34. Through this grinding section 34, fuel can flow between the valve needle 10 and the wall of the guide section 108. Starting from the guide section 210, the valve needle 10 tapers towards the valve seat 19 to form a pressure-receiving shoulder 24 and transitions to a reduced-diameter shaft 110. This shaft portion 110 is adjacent to the valve sealing surface 22. An annular passage 27 is formed between the shaft 110 and the wall of the hole 8. Fuel can flow into the injection opening 17 through the annular passage 27.
[0014]
At the end opposite the combustion chamber, the bore 8 is expanded to form a spring chamber 25. A sleeve 29 is arranged in the spring chamber 25 and surrounds a spring section 310 of the valve needle 10. The valve needle 10 is tightly guided in the sleeve 29. The spring section 310, the guide section 210 and the stem 110 form the piston-like section of the valve needle 10. The control chamber 14 is partitioned by the sleeve 29, the end face of the valve needle 10 on the side opposite to the combustion chamber, and the throttle disk 3. The pressure in the control chamber 14 can be controlled by a control valve 15 arranged on the valve holder 2. In addition to the sleeve 29, the valve needle 10 is surrounded by a support ring 30. The support ring 30 is supported on the shoulder of the valve needle 10. Between the support ring 30 and the sleeve 29, a closing spring 32 surrounding the valve needle 10 is arranged under a compression preload or under a compression preload. The spring chamber 25 can be filled with fuel under high pressure via the inflow passage 12 extending to the valve holder 2 and the throttle disk 3.
[0015]
Via the inflow passage 12, the spring chamber 25 and thus also the annular passage 27 are always loaded with fuel under injection pressure. In the closed state of the fuel injection valve, a high pressure exists in the control chamber 14. This pressure pushes the valve needle 10 together with the force of the closing spring 32 towards the valve seat 19, whereby the injection opening 17 is closed. When fuel injection is desired, the pressure in the control chamber 14 is released via the control valve 15. The hydraulic force of the fuel in the spring chamber 25 and in the annular passage 27, in particular of the fuel on the pressure receiving shoulder 24, moves the valve needle 10 in the direction of the control chamber 14 and thus away from the valve seat 19. Press in the direction. As a result, the fuel reaches the injection opening 17 from the annular passage 27 through the space between the valve seal surface 22 and the valve seat 19, and the fuel is injected into the combustion chamber of the internal combustion engine through the injection opening 17. The pressure in the spring chamber 25 or in the annular passage 27 is maintained by the subsequently guided fuel during the injection. In the region of the guide section 108 of the hole 8, fuel flows through the grinding section 34. In this case, the flow cross-section of this grinding section 34 is such that, in order to maintain the injection pressure there, it is generally sufficient, at least at maximum load of the internal combustion engine, that the fuel continues to flow into the annular passage 27. It is set large. In order to close the fuel injection valve, the pressure in the control chamber 14 is increased again, whereby the valve needle 10 is brought back into contact with the valve seat 19.
[0016]
When the valve needle 10 collides with the valve seat 19 at a high speed due to an extremely short closing time, a pressure oscillation of the valve needle 10 results. This pressure oscillation of the valve needle 10 can cause wear between the valve sealing surface 22 and the valve seat 19. This is because at this point a slight movement of the valve sealing surface 22 relative to the valve seat 19 takes place. In order to damp this vibration and thus reduce the load peak, a plurality of transverse holes 40 are formed in the valve needle 10. These transverse holes 40 increase the longitudinal elasticity of the valve needle 10 so that the pressure oscillations of the valve needle 10 are absorbed and compensated for at the same time. As a result, wear in the region of the valve seat 19 is reduced. It is particularly advantageous if at least two transverse holes 40 are formed. This is because, in this case, the remaining material between the two lateral holes 40 acts like a cantilever, thereby producing a high longitudinal elasticity. The transverse bore 40 may be arranged in the area of the shaft 110, the guide section 210 and / or the spring section 310, ie the piston-like section of the valve needle 10, as shown in FIG.
[0017]
Furthermore, the lateral bore 40 has the advantage that the mass of the valve needle 10 is reduced. As is common in today's common rail injection systems, the valve needle 10 must slide from the open position to the closed position in a very short time for a rapid and continuous injection operation. The smaller the mass to be moved and the greater the force, the more quickly the fuel injector can open and close. If the valve needle 10 has a relatively large mass, a large force must be exerted, and the valve needle 10 accordingly absorbs a large amount of kinetic energy during its movement. This kinetic energy must be reduced during mounting on the valve seat 19. This causes high wear in the area of the valve seat 19. On the other hand, when the valve needle 10 has a small mass, the valve needle 10 absorbs a small amount of kinetic energy at the same speed, so that the load when the valve needle 10 is mounted on the valve seat 19 is reduced. Is correspondingly reduced.
[0018]
The horizontal holes 40 are arranged on the shaft portion 110 such that adjacent horizontal holes 40 are rotated by a predetermined angle α, that is, are shifted in the circumferential direction. In this case, the transverse hole 40 is formed so as to extend perpendicular to the longitudinal axis 11 of the valve needle 10. However, as shown by the transverse hole 40 provided in the area of the guide section 210, this transverse hole 40 may have an angle different from 90 ° with respect to the longitudinal axis 11 of the valve needle 10. May be proposed. In the area of the grinding part 34, the lateral holes 40 are formed so as to communicate from one grinding part 34 to the grinding part 34 located on the opposite side. In this case, in the case where four grinding parts 34 are provided, the adjacent lateral holes 40 are correspondingly shifted in the circumferential direction by 90 ° so that they are opposite from the laterally located grinding parts 34. Is connected to the grinding portion 34 located on the side of. A plurality of lateral holes 40 may be formed in the region of the spring chamber 25. In this case, adjacent lateral holes 40 are circumferentially offset from one another by an angle α which is also defined. Due to the appropriate angle α, preferably 90 °, of the lateral bores 40 adjacent to each other, the valve needle 10 has no preferred direction with respect to its lateral stiffness, and the valve needle 10 is guided by slight buckling. No risk of getting stuck in section 108 is achieved.
[0019]
On the one hand, in order to achieve a significant reduction in longitudinal stiffness without causing significant mechanical weakening of the valve needle 10 which can impair the stability of the valve needle 10 during operation, a transverse The diameter of the bore 40 is dimensioned to be approximately 0.2 to 0.4 times the diameter of the valve needle 10 in this region. As a whole, the lateral bore 40 advantageously has a volume in which the mass of the valve needle 10 is reduced by at least 10% compared to the valve needle 10 without the lateral bore 40.
[Brief description of the drawings]
FIG.
1 is a longitudinal section of a fuel injection valve according to the present invention.
[Explanation of symbols]
Reference Signs List 1 valve body, 2 valve holder, 3 throttle disk, 5 tightening nut, 8 holes, 10 valve needle, 11 longitudinal axis, 12 inflow passage, 14 control room, 15 control valve, 17 injection opening, 19 valve seat, 22 Valve sealing surface, 24 pressure receiving shoulder, 25 spring chamber, 27 annular passage, 29 sleeve, 30 support ring, 32 closing spring, 34 grinding part, 40 lateral hole, 108 guide section, 110 shaft section, 210 guide section, 310 Spring section

Claims (6)

A fuel injection valve for use in an internal combustion engine, wherein a valve body (1) is provided, and a valve needle (10) is movable in a longitudinal direction in a hole (8) provided in the valve body (1). A valve needle (10) having a piston-like section (110; 210; 310) and a substantially conical valve sealing surface (22) at the end facing the combustion chamber; At the valve sealing surface (22) the valve needle (10) is adapted to cooperate with the valve seat (19) so as to control the opening of at least one injection opening (17). In one type, the valve needle (10) has at least two transverse holes (40) in its piston-like section (110, 210, 310). Fuel injection valve. A plurality of lateral holes (40) are formed in the valve needle (10), and adjacent lateral holes (40) are circumferentially offset from one another by a predetermined angle (α). 2. The fuel injection valve according to 1. 3. The fuel injection valve according to claim 2, wherein the angle (α) is set to at least approximately 90 °. 2. The fuel injection valve according to claim 1, wherein the transverse bore (40) intersects the longitudinal axis (11) of the valve needle (10) at right angles. 2. The fuel injection according to claim 1, wherein the at least one lateral bore has a diameter dimensioned to be 0.2 to 0.4 times the diameter of the valve needle in this region. valve. 2. The fuel injection according to claim 1, wherein the weight of the valve needle (10) is reduced by the transverse bore (40) by at least 10% compared to a valve needle (10) without the transverse bore (40). valve.

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