Valve body and fluid injector with a valve body

Abstract

 The invention is distinguished by a valve body with a needle (22) and a cartridge (21). A recess (22) of the cartridge (21) takes in the needle (22) and comprises on one of its ends a seat plate (27). The seat plate (27) comprises a needle seat (29) for the inward opening needle (22), with the needle (22) further comprising a seat-part (24) with a sealing area that is designed to rest on the needle seat (29). At least one sack disc (39a) is fixed to the seat plate (27) and restricts the sack volume (35) in conjuction with the seat plate (27) and the seat part (24) of the needle (22). Each sack disc (39a) comprises a sack disc recess (40a) in order to modify the sack volume (35). An orifice disc (37) is arranged facing away from the sack volume (35) related to the sack disc (39a), and the orifice disc (37) comprises a nozzle (41).

Description

[0001] The invention relates to a valve body and a fluid injector. The valve body comprises a needle and a cartridge with a recess, which takes in the needle and which comprises on one of its ends a seat plate, that comprises a needle seat for the inward-opening needle. Fluid injectors, in particular fuel injectors for diesel or gasoline internal combustion engines, comprise a housing, an actuator unit and a valve body. In the case of an inward-opening needle the needle controls the flow of the fluid into a sack volume, which leads to a nozzle.

[0002] In order to meet the requirements of strict emission legislation and in order to save fuel consumption fluid injectors, in particular fuel injectors for internal combustion engines, are arranged in a cylinder head of the internal combustion engine in a way, that they inject the fuel directly into a combustion chamber of the engine. In order to get a very fine atomization of the fluid in such applications it is necessary to provide the fluid under high pressure. In gasoline internal combustion engines the fluid pressure may reach up to 200 bars, in diesel engines fluid pressure may reach up to 2000 bars.

[0003] The object of the invention is to create a valve body and a fluid injector, which enabables simply an intended fluid atomization.

[0004] The object concerning the valve body is achieved by the features of claim 1. The object concerning the fluid injector is achieved by the features of claim 6. Advantageous embodiments of the invention are given in the subclaims.

[0005] The invention is distinguished by a valve body with a needle and a cartridge. The recess takes in the needle and comprises on one of its ends a seat plate. The seat plate comprises a needle seat for the inward opening needle, with the needle further comprising a seat part with a sealing area that is designed to rest on the needle seat. At least one sack disc is fixed to the seat plate and restricts a sack volume in conjunction with the seat plate and the seat part of the needle. Each sack disc comprises a sack disc recess in order to modify the sack volume. An orifice disc is arranged facing away from the sack volume related to the sack disc, and the orifice disc comprises a nozzle.

[0006] The invention concerning the fluid injector is distinguished by a fluid injector with a housing, an actuator unit and the valve body.

[0007] In an advantageous embodiment of the valve body the sack disc recess forms a spherical free volume. While operating the injector the spherical free volume produces vortices in fluid which enables an intended atomization of the fluid.

[0008] In a further advantageous embodiment of the valve body the sack disc recess forms a cylindrical free volume. A cylindrical free volume in the sack disc easily increases the sack volume.

[0009] In a further advantageous embodiment of the valve body the sack disc comprises a dowel pin hole. The dowel pin hole enables easy assembling of the sack disc, further sack discs and/or the orifice disc.

[0010] In a further advantageous embodiment of the valve body the sack disc, further sack discs and/or the orifice disc are laser-welded. This enables easy assembling of the sack disc.

[0011] Exemplary embodiments of the invention are explained in the following with the aid of schematic drawings. These are as follows:

Figure 1

a first embodiment of a fluid injector with a valve body,

Figure 2

an enlargement of the valve body according to Figure 1 with a first embodiment of sack discs,

Figure 3

an enlargement of the valve body according to Figure 1 with a second embodiment of the sack discs.

[0012] Elements of the same design and function that occur in the different illustrations are identified by the same reference character.

[0013] A fluid injector, that is used as a fuel injector for an internal combustion engine, comprises a housing 1, a valve body 2, an actuator unit and a fuel connector (Figure 1). The fuel connector is designed to be connected to a high pressure fuel chamber of the internal combustion engine, where fuel is stored under high pressure, for example under the pressure of about 200 bar.

[0014] The housing 1 is preferably formed in a way, that there is a space to lead the fuel from the fuel connector to a fuel inlet of the valve body.

[0015] The actuator unit is preferably arranged in the housing. The actuator unit may be of a type known to a person skilled in the art, that is suitable for that purpose. It may, for example, contain a piezoelectric actuator. However, it 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 pre-loaded in such a way, that it pushes the armature 31 away from the pole element 33 unless an electromagnetic force created by the solenoid 32 is larger than the pre-loading force of the return spring 25.

[0016] The valve body 2 comprises a cartridge 21, which is fixed to the housing 1 at one of its free ends, preferably by welding, especially by laser-welding. The cartridge 21 comprises a recess 23, which takes in a needle 22 and also serves as a fluid duct. The recess 23 of the cartridge 21 takes in on one of its ends a seat plate 27, which comprises in a conically-shaped area a needle seat 29 for the inward-opening needle 22. The needle 22 comprises a seat part 24 with a sealing area, that is destined to rest on the needle seat 29, if the seat part 24 is pushed against the needle seat 29. The needle 22 is mechanically coupled to the armature 31.

[0017] The seat part 24 of the needle 22 may be spherically-shaped, which improves the sealing quality between the seat part 24 and the sealing area of 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 needle 22 is taken in. The ball is preferably fixed to the needle 22 by welding.

[0018] If the needle 22 rests with the sealing area of its seat part 24 in the needle seat 27, fluid is prevented from flowing into a sack volume 35, which is limited by respective walls of the seat plate 27 and by a sack disc 39, which has a recess 40. On that side of the sack disc 39, which is facing away from the sack volume 35, there is an orifice disc 37, which comprises at least one nozzle 41 through which the fluid can flow out of the valve body 2 from the sack volume 35. The sack disc 39 comprises a sack disc recess 40. The sack disc recess 40 increases the sack volume 35. This offers the possibility to form different sack volume 35 shapes just by changing the sack disc 39. The fluid atomization is strongly dependent on the shape and size of the sack volume 35.

[0019] It is advantegous for the assembling of the orifice disc 37 and/or the sack disc 39, if the orifice disc 37 and/or the sack disc 39 comprise at least one hole 43 for a dowel pin. To adjust the orifice disc 37 and the sack disc 39, the dowel pin is arranged in the dowel pin hole 43. The orifice disc 37 and the sack disc 39 preferably are laser-welded. They may be also fixed in a different way.

[0020] It is possible to put multiple sack discs 39a,b,c,d between the orifice disc 37 and the seat plate 27. The multiple sack discs 39a,b,c,d comprise multiple sack disc recesses 40a,b,c,d. This easily increases the possibility of influencing the sack volume 35. Also a plurality of different sack volume 35 shapes and dependent on this different spray atomizations are feasible. The sack disc recesses 40a,b,c,d for example can form a spherical free volume (Figure 2). This embodiment will create turbulences in the fluid, which increases atiomzaion of the fluid. In an other embodiment the sack disc recesses 40a,b,c,d form a conical shaped free Volume (Figure 3) preferably with steps from one sack disc 39a,b,c,d to the other. The corners of the steps create areas of fast fluid flow and also areas of slow fluid flow. At the borders of those areas evolve turbulences in the fluid, which increases fluid atomization.

Claims

1. Valve body (2) with a needle (22) and a cartridge (21) with a recess (23), which takes in the needle (22) and which comprises on one of its ends a seat plate (27), that comprises a needle seat (29) for the inward opening needle (22), with the needle (22) further comprising a seat-part (24) with a sealing area, that is destined to rest on the needle seat (29), and with at least one sack-disc (39a), which is fixed to the seat plate (27) and which restricts a sack volume (35) in conjunction with the seat plate (27) and the seat part (24) of the needle (22), each sack-disc (39a) comprising a sack-disc recess (40a) in order to modify the sack volume (35), and with an orifice disc (37), which is arranged facing away from the sack volume (35) related to the sack-disc (40a), and with the orifice disc (37) comprising a nozzle (41).

2. Valve body (2) in accordance with claim 1 with the sack-disc recess (40a) forming a spherical free volume.

3. Valve body (2) in accordance with one of the preceding claims with the sack-disc recess (40a) forming a conical free volume.

4. Valve body (2) in accordance with one of the preceding claims with the sack-disc (39a) comprising a dowel pin hole (43).

5. Valve body (2) in accordance with one of the preceding claims with the sack-disc (39a) and/or the orifice disc (37) being laser welded.

6. Fluid injector with a housing (1), an actuator unit and a valve body (2) in accordance with one of the preceding claims.

Drawing