EP2700808A1

EP2700808A1 - Seat plate and valve assembly for an injection valve

Info

Publication number: EP2700808A1
Application number: EP12181436.2A
Authority: EP
Inventors: Stefano Filippi; Mauro Grandi; Valerio Polidori
Original assignee: Continental Automotive Technologies GmbH
Current assignee: Aumovio Germany GmbH
Priority date: 2012-08-23
Filing date: 2012-08-23
Publication date: 2014-02-26

Abstract

Seat plate (26) for an injection valve (62) is provided, comprising a fluid outlet portion (44) and a fluid flow directing element (30) being configured as a recess (46) in the seat plate (26), the recess (46) being configured to direct the fluid flow to the fluid outlet portion (44) and being configured to swirl a fluid being directed through the fluid flow directing element (30). Furthermore, a valve assembly (60) comprising a seat plate (26) and an injection valve (62) is provided.

Description

The invention relates to a seat plate and a valve assembly for an injection valve.
Injection valves are in wide spread 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 also 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 very high pressures. The pressures may be in case of a gasoline engine, for example, in the range of up to 200 bar and in the case of diesel engines in the range of up to 2000 bar.
The object of the invention is to create a valve assembly which facilitates a reliable and precise function.
These objects are achieved by the features of the independent claim. Advantageous embodiments of the invention are given in the sub-claims.
The invention is distinguished by a seat plate for an injection valve, comprising a fluid outlet portion and a fluid flow directing element being configured as a recess in the seat plate. The recess may be configured to direct the fluid flow to the fluid outlet portion and to swirl a fluid being directed through the fluid flow direction element. The recess may be provided on a plane surface of the seat plate.
In an advantageous embodiment, the recess comprises at least one recess fluid inlet portion and at least one channel portion arranged between the at least one recess fluid inlet portion and the fluid outlet portion. The recess fluid inlet portion may have a cylindrical shape. The channel portion may have an upstream end which is located adjacent to the recess fluid inlet portion and a downstream end being adjacent to the fluid outlet portion. In particular, at the upstream end, the channel portion may be hydraulically coupled to the recess fluid inlet portion, and at the downstream end it may be hydraulically coupled to the fluid outlet portion. A fluid may enter the fluid inlet portion with a high velocity, and may then be directed through the channel portion to the fluid outlet portion.
The upstream end may in particular be offset in an angular direction, i.e. in clockwise or counter clockwise direction, with respect to a longitudinal axis of the seat plate which in particular coincides with a central longitudinal axis of a valve assembly of the injection valve. Swirling of the fluid may be particularly efficient in this way.
In one embodiment, the channel portion may be straight-lined. The channel may also be curved. Alternatively, the channel portion may have a convex shape, a concave shape or the shape of a drop. The shape of a drop is in particular composed of a convex section and a concave section. These embodiments may allow a good adaption of the channel portion to the recess fluid inlet portion with a stepless transition between the channel portion 50 and the recess fluid inlet portion.
In an advantageous embodiment, the recess comprises a plurality of fluid inlet portions and channel portions. For example, the recess may comprise three or more and/or ten or less fluid inlet portions and, respectively, channel portions. In an expedient development, it comprises four or six fluid inlet portions, and, respectively, four or six channel portions. The fluid inlet portions and channel portions may be evenly distributed around the fluid outlet portion.
The characteristic of the fluid flow releasing through the fluid outlet portion can be strongly influenced by the shape of the seat plate, in particular by the shape of the fluid flow directing element.
With advantage, the fluid flow receives a high fluid flow velocity available at the downstream end of the channel portion where the fluid leaves the fluid flow directing element. In particular, a high tangential speed of the fluid flow may be achieved when the fluid flow leaves the fluid flow directing element. By this, a high fuel pressure may be available at the downstream end of the channel portion and, consequently, a large cone angle of the spray of the fluid may be possible. In particular, the fluid flow releasing through the fluid outlet portion, which can be a spray, may have a big spray angle and a favorable distribution of fluid droplets.
A further advantage of the invention is that the seat plate comprising the fluid flow directing element is easy to manufacture. For example, the seat plate may be manufactured by metal injection molding, stamping or punching. Furthermore, since the fluid flow directing element is integrated in the seat plate, the number of components in an injection valve may be kept low. In this way, the risk of misalignment between individual components may be particularly low.
Furthermore, the invention is distinguished by a valve assembly for an injection valve, comprising a valve body comprising a cavity with a fluid inlet portion, a seat plate and a valve needle axially movable in the cavity, the valve needle preventing a fluid flow through the fluid outlet portion in a closing position and releasing the fluid flow through the fluid outlet portion in further positions, wherein the valve needle is in contact with the seat plate in the closing position.
Preferably, the seat plate is configured as previously described.
Furthermore, the invention is distinguished by an injection valve comprising a valve assembly as previously described, and further comprising a housing and an inlet tube.
Exemplary embodiments of the invention are explained in the following with the aid of schematic drawings. These are as follows:

Figure 1: a segment of a seat plate comprising a fluid flow directing element,
Figure 2: an injection valve with a seat plate in a longitudinal section view,
Figure 3: an enlarged illustration of section II of the valve assembly of the injection valve according to figure 1 in a longitudinal section view.

Elements of the same design and function that appear in different illustrations are identified by the same reference numerals.
Figure 1 shows a segment of a seat plate 26 for an injection valve comprising a fluid outlet portion 44 and a fluid flow directing element 30. A further segment of the seat plate 26 is cut away in Figure 1 for better representability.
The fluid flow directing element 30 may be configured as a recess 46 in a surface 72 of the seat plate 26. The recesses 46 may be configured to direct a fluid flow to the fluid outlet portion 44. The recess 46 comprises six fluid inlet portions 48 and, respectively, six channel portions 50, which are not entirely shown due to the sectional representation of the seat plate 26. Each channel portion 50 has an upstream end 52 and a downstream end 54. At the upstream end 52 the channel portion 50 is hydraulically coupled with the recess fluid inlet portion 48. The downstream end 54 of the channel portion 50 enables a hydraulic coupling of the channel portion 50 with the fluid outlet portion 44. In the shown embodiment, the channel portion 50 is straight-lined. Alternatively, the channel portion 50 may have a convex shape, a concave shape or the shape of a drop.
Figure 2 shows an injection valve 62 that is in particular suitable for closing fuel to an internal combustion engine. The injection valve 62 comprises an inlet tube 2, a housing 6 and a valve assembly 60.
The valve assembly 60 comprises a valve body 4 with a central longitudinal axis L and a cavity 8, which takes in a valve needle 10 and preferably a part of an armature 12. The valve needle 10 has a surface 11 and a seat part 64 (see figure 3). In the inlet tube 2 a recess 16 is provided which further extends to a recess 18 of the armature 12. A spring 14 is arranged in the recess 16 of the inlet tube 2 and/or the recess 18 of the armature 12. Preferably, it rests on a spring seat being formed by an anti-bounce disc 20. By this the spring 14 is mechanically coupled to the needle 10. An adjusting tube 22 is provided in the recess 16 of the inlet tube 2. The adjusting tube 22 forms a further seat for the spring 14 and may be axially moved during the manufacturing process of the fluid injection valve in order to preload the spring 14 in a desired way.
In a closing position of the needle 10 it sealingly rests on the seat plate 26 by this preventing a fluid flow through the fluid outlet portion 44. The fluid outlet portion 44 may comprise an injection nozzle 24. The injection nozzle 24 may be, for example, an injection hole. However, it may also be of some other type suitable for closing fluid. In addition to that a lower guide 28 for guiding the needle 10 is provided.
The lower guide 28 further comprises an orifice 70 for guiding the fluid flow, as shown in Figure 3. In particular, the lower guide 28 comprises a plurality of orifices 70, a respective orifice 70 assigned to and preferably aligned with each of the fluid inlet portions 48 of the recess 46. Preferably, the orifices 70 have the same lateral dimensions as the fluid inlet portions 48. The lower guide 28 may be arranged adjacent to and preferably in direct contact with the seat plate 26.
The injection valve 62 is provided with an actuator unit that comprises preferably an electromagnetic actuator, comprising a coil 36, which is preferably overmolded. A valve body shell 38, the armature 12 and the inlet tube 2 are forming an electromagnetic circuit. The actuator unit may, however, also comprise another type of actuator, which is known to a person skilled in the art for that purpose. Such an actuator may be, for example, a piezoelectric actuator.
A fluid inlet portion 42 is provided in the valve body 4 which communicates with the fluid outlet portion 44 of the seat plate 26.
The upstream end 52 and the downstream end 54 of each channel portion 50 of the recess 46 in the seat plate 26 are positioned offset from each other in an angular direction, so that the fluid flow obtains a tangential velocity component, i.e. a velocity component perpendicular to the longitudinal L and radial directions. In this way, swirling of the fluid may be particularly efficient.
The fluid flow speed at the downstream end 54 of the channel portion 50 may be large. Thereby, the tangential speed of the fluid flow when the fluid enters the fluid outlet portion 44 may be large, which may result in a large radial component of the fluid flow and the distribution of the fluid in radial direction may be very good. This can result in an increased spray angle of the fluid flow through the fluid outlet portion 44, in particular the injection nozzle 24, and a good distribution of droplets of the spray.
In the following, the function of the injection valve 10 is described in detail with reference to Figures 2 and 3:

The fluid is led from the fluid inlet portion 42 to the fluid outlet portion 44. The axial position of the valve needle 10, which determines whether the fluid outlet portion 44 is opened or closed for a fluid flow, depends on the force balance between the spring 14 and the forces applied to the valve needle 10 by the actuator unit with the coil 36.
The fluid flow through the fluid outlet portion 44 can be described with a flow path 68 with flow path sections 68a, 68b.
The fluid flow on the flow path 68 is passing the fluid flow directing element 30 thereby being accelerated in the channel portion 50. By this the fluid flow obtains a radial velocity component which results in a distribution of droplets in a spray in the flow path section 68b of the second flow path 68.

The radial component of the fluid flow velocity on the flow path section 68b is high and a good distribution of fluid in radial direction is available. Therefore the fluid flow through the fluid outlet portion 44 generating a spray can result in a large spray angle and a good distribution of the droplets of the spray.
The invention is not limited to specific embodiments by the description on the basis of said exemplary embodiments but comprises any combination of elements of different embodiments. Moreover, the invention comprises any combination of claims and any combination of features disclosed by the claims.

Claims

Seat plate (26) for an injection valve (62), comprising a fluid outlet portion (44) and a fluid flow directing element (30) being configured as a recess (46) in the seat plate (26), the recess (46) being configured to direct the fluid flow to the fluid outlet portion (44) and being configured to swirl a fluid being directed through the fluid flow directing element (30).
Seat plate (26) according to claim 1, wherein the recess (46) comprises at least one recess fluid inlet portion (48) and at least one channel portion (50) arranged between the at least one recess fluid inlet portion (48) and the fluid outlet portion (44) .
Seat plate (26) according to claim 2, wherein the recess fluid inlet portion (48) has a cylindrical shape.
Seat plate (26) according to claim 2 or 3, wherein the channel portion (50) has a straight, a convex or concave shape or the shape of a drop.
Seat plate (26) according to any of the preceding claims, being manufactured by metal injection moulding or stamping.
Valve assembly (60) for an injection valve (62), comprising
- a valve body (4) comprising a cavity (8) with a fluid inlet portion (42),

- a seat plate (26) according to any of claims 1 to 5, and

- a valve needle (10) axially movable in the cavity (8), the valve needle (10) preventing a fluid flow through the fluid outlet portion (44) in a closing position and releasing the fluid flow through the fluid outlet portion (44) in further positions, wherein the valve needle (10) is in contact with the seat plate (26) in the closing position.
Injection valve (62) comprising a valve assembly (60) according to claim 6 which comprises the seat plate (26) according to one of claims 2 to 4 and further comprises a guide (28) for guiding the valve needle (10), wherein the guide (28) has at least one orifice (70), the orifice (70) being aligned with the at least one recess fluid inlet portion (48).
Injection valve (62) comprising a valve assembly (60) according to claim 6 or 7, further comprising a housing (6) and an inlet tube (2).