EP1816344A1

EP1816344A1 - Valve assembly for an injection valve and injection valve

Info

Publication number: EP1816344A1
Application number: EP06002243A
Authority: EP
Inventors: Paolo Bertini; Alessandro Morelli
Original assignee: Siemens AG
Current assignee: Continental Automotive GmbH
Priority date: 2006-02-03
Filing date: 2006-02-03
Publication date: 2007-08-08
Anticipated expiration: 2026-02-03
Also published as: DE602006007674D1; EP1816344B1

Abstract

Valve assembly (10) of an injection valve (12), the valve assembly (10) comprising a valve body (20) with a seat body (27), a cavity (18) and an orifice disc (37) being arranged away from the cavity (18) relative to the seat body (27), and a valve needle (22) axially movable in the cavity (18). The seat body (27) comprises a needle seat (29) for the valve needle (22) and a projection (28) extending away from the cavity (18) relative to the seat body (27). The orifice disc (37) comprises a nozzle (41) and a protrusion (39) extending away from the cavity (18) relative to the seat body (27) and abutting the projection (28) of the seat body (27) and being rigidly coupled to the projection (28) of the seat body (27).

Description

The invention relates to a valve assembly for an injection valve and an injection valve.
Injection valves are in widespread use, in particular for internal combustion engines where they may be arranged in order to dose the fluid into an intake manifold of the internal combustion engine or directly into the combustion chamber of a cylinder of the internal combustion engine.
Injection valves are manufactured in various forms in order to satisfy the various needs for the various combustion engines. Therefore, for example, their length, their diameter, and all the various elements of the injection valve being responsible for the way the fluid is dosed may vary in a wide range. In addition to that, injection valves may accommodate an actuator for actuating a needle of the injection valve, which may, for example, be an electromagnetic actuator or a piezoelectric actuator.
In order to enhance the combustion process in view of the creation of unwanted emissions, the respective injection valve may be suited to dose fluids under high pressures.
The pressures may be in case of a gasoline engine, for example, in the range of up to 200 bar.
The object of the invention is to create a valve assembly for an injection valve and an injection valve which is simple to be manufactured and which facilitates a reliable and precise function.
This object is achieved by the features of the independent claim. Advantageous embodiments of the invention are given in the sub-claims.
According to the first aspect, the invention is distinguished by a valve assembly of an injection valve, the valve assembly comprising a valve body with a seat body, cavity and an orifice disc being arranged away from the cavity relative to the seat body, and a valve needle axially movable in the cavity. The seat body comprises a needle seat for the valve needle and a projection extending away from the cavity relative to the seat body. The orifice disc comprises a nozzle and a protrusion extending away from the cavity relative to the seat body and abutting the projection of the seat body being rigidly coupled to the projection of the seat body.
This has the advantage that a good alignment of the orifice disc relative to the seat body can be obtained. Consequently, a good injection performance of the nozzle is possible.
In an advantageous embodiment of the invention, the coupling between the protrusion of the orifice disc and the projection of the seat body is laser-welded. This allows a reliable coupling between the seat body and the orifice disc.
In a further advantageous embodiment, the orifice comprises a plurality of protrusions distributed over the circumference of the orifice disc. By this, a very exact positioning of the orifice disc relative to the seat part is possible.
In a further advantageous embodiment of the invention, the orifice disc comprises two protrusions which are arranged on opposing sides of the orifice disc. This enables a simple construction of the orifice disc of the protrusions. Consequently, a low-cost solution for the production of the orifice disc may be obtained.
Exemplary embodiments of the invention are explained in the following with the aid of schematic drawings. These are as follows:

Figure 1, an injection valve with a valve assembly in a longitudinal section view,
Figure 2, a part of the valve assembly of the injection valve in a longitudinal section view, and
Figure 3, the part of the valve assembly of the injection valve in a plan view along line III-III of figure 2.

Elements of the same design and function that appear in different illustrations are identified by the same reference characters.
An injection valve 12 that can be used as a fuel injector for an internal combustion engine comprises a valve assembly 10, an actuator unit 11, a fuel connector 13 and a housing 14 (figure 1). The fuel connector 13 is designed to be connected to a (not shown) fuel chamber of the internal combustion engine. The fuel can be stored under a pressure of about 200 bar, for example.
The housing 14 is preferably formed in a way that there is a space to lead the fuel from the fuel connector 13 to a fuel inlet of a valve body 20.
The actuator unit 11 is preferably arranged in the housing 14. The actuator unit 11 may be of a type known to a person skilled in the art that is suitable for the purpose. It may, for example, contain a piezoelectric actuator. However, the actuator unit 11 may alternatively contain an electromagnetic actuator that comprises an armature 31, a solenoid 32, and a pole element 33. A return spring 25 is arranged and preloaded in such a way that it pushes away the armature 31 from the pole element 33 unless an electromagnetic force created by the solenoid 32 is larger than the preloading force of the return spring 25.
The valve body 20 comprises a cartridge 16, which is fixed to the housing 14 at one of its free ends, preferably by welding, especially by laser-welding. The cartridge 16 comprises a cavity 18, which takes in a valve needle 22 and also serves as a fluid duct. The cavity 18 of the cartridge 16 takes in on one of its ends a seat body 27. The seat body 27 comprises in a conically shaped area a needle seat 29 for the inward-opening valve needle 22. The valve needle 22 comprises a seat part 24 with a sealing area 30 that is designed to rest on the needle seat 29, if the seat part 24 is pushed against the needle seat 29. The valve needle 22 is mechanically coupled to the armature 31.
The seat body 27 may be made in one part with the cartridge 16 or as a separate part from the cartridge 16. In addition to that a guide disc 35 for guiding the valve needle 22 is provided (figure 2).
The seat part 24 of the valve needle 22 may be shaped spherically which improves the sealing quality between the sealing area 30 of the seat part 24 and the needle seat 29. The spherical shape can be easily obtained by forming the seat part 24 out of a ball with a hole where the valve needle 22 is taken in. The ball is preferably fixed to the valve needle 22 by welding.
If the valve needle 22 rests with the sealing area 30 of its seat part 24 in the needle seat 29 of the seat body 27, fluid is prevented from flowing through one nozzle 41 or a plurality of nozzles 41. If the sealing area 30 of the seat part 24 of the valve needle 22 is distanced from the needle seat 29 of the seat body 27 the fluid can flow through the nozzles 41 out of the valve body 20. The nozzles 41 are arranged in an orifice disc 37 which is arranged away from the cavity 18 relative to the seat body 27. The orifice disc 37 is preferably laser-welded to the seat body 27. It may be also fixed in a different manner.
The seat body 27 comprises a projection 28 which extends away from the cavity 18 relative to the seat body 27. As can be seen in figure 2 the orifice disc 37 comprises a protrusion 39 which abuts the projection 28 of the seat body 27 and is coupled to the projection 28 of the seat body 27 by welding, preferably by laser-welding. This allows a reliable coupling between the seat body 27 and the orifice disc 37.
Figure 3 shows the valve assembly 10 with the orifice disc 37 comprising a plurality of protrusions 39 which are distributed over the circumference of the orifice disc 37. The protrusions 39 are forming spring elements and allow a very exact positioning of the orifice disc 37 relative to the seat body 27. Preferably each two protrusions 39 are arranged on opposing sides of the orifice disc 37. This enables a simple construction of the orifice disc 37 of the protrusions 39 and, consequently, a low-cost solution is possible.
Alternatively, the protrusion 39 is a one-piece element which extends over the whole circumference of the orifice disc 37. This means that the protrusion 39 forms a collar of the orifice disc 37 abutting the projection 38 of the seat body 27. The protrusion 39 works as a spring element and allows a precise fitting of the orifice disc 37 relative to the seat body 27.
In the following, the function of the injection valve 12 is described in detail:
The fluid is led from the fuel connector 13 to the cavity 18.
The spring 25 forces the valve needle 22 towards the actuator unit 11. In the case when the actuator unit 11 is deenergized the spring 25 can force the valve needle 22 to move in axial direction in its closing position. The axial position of the valve needle 22 which determines whether the cavity 18 is opened or closed for a fluid flow is depending on the force balance between the force on the valve needle 12 caused by the actuator unit 11 with the solenoid 32 and the force on the valve needle 22 caused by the spring 25.
In the closing position of the valve needle 22 the seat part 24 of the valve needle 22 sealingly rests on the needle seat 29 of the seat body 27 and consequently prevents a fluid flow through the nozzles 41.
In the case that the actuator unit 11 gets energized, the actuator unit 11 may effect a force on the valve needle 22. The valve needle 22 is able to move in axial direction out of the closing position. Outside of the closing position of the valve needle 22, there is a gap in an area between the needle seat 29 of the seat body 27 and the sealing area 30 of the valve needle 22. This enables a fluid flow through the nozzles 41 which can be directed very precise due to the exact positioning of the orifice disc 37 with the protrusions 39 relative to the seat body 27.

Claims

Valve assembly (10) of an injection valve (12), the valve assembly (10) comprising
- a valve body (20) with a seat body (27), a cavity (18) and an orifice disc (37) being arranged away from the cavity (18) relative to the seat body (27), and

- a valve needle (22) axially movable in the cavity (18), the seat body (27) comprising a needle seat (29) for the valve needle (22) and a projection (28) extending away from the cavity (18) relative to the seat body (27),
the orifice disc (37) comprising a nozzle (41) and a protrusion (39) extending away from the cavity (18) relative to the seat body (27) and abutting the projection (28) of the seat body (27) and being rigidly coupled to the projection (28) of the seat body (27).
Valve assembly (10) in accordance with claim 1 with the coupling between the protrusion (39) of the orifice disc (37) and the projection (28) of the seat body (27) being laser-welded.
Valve assembly (10) in accordance with claim 1 or claim 2 with the orifice disc (37) comprising a plurality of protrusions (39) distributed over the circumference of the orifice disc (37).
Valve assembly (10) in accordance with one of the preceding claims with the orifice disc (37) comprising two protrusions (39) being arranged on opposing sides of the orifice disc (37).
Injection valve (12) with a housing (14), an actuator unit (11) and a valve assembly (10) according to one of the preceding claims.