EP1682773A1

EP1682773A1 - Fuel injection valve

Info

Publication number: EP1682773A1
Application number: EP04791271A
Authority: EP
Inventors: Stefan Arndt; Martin Maier; Joerg Heyse
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2003-10-29
Filing date: 2004-10-21
Publication date: 2006-07-26
Also published as: DE10350548A1; WO2005042968A1; JP2007509285A; US20080035130A1

Abstract

Fuel injection valves known per se comprise a valve closing body which co-operates with a sealing seat of a valve seat, and a flow outlet area which is arranged downstream from the sealing seat. The fuel spray produced by means of the fuel injection valves has an average drop diameter which is not sufficiently reduced for future waste gas emission specifications. The invention relates to a fuel injection valve wherein injection is improved in a simple manner and the average diameter of the drop is reduced without the requirement of any additional auxiliary energy. According to the invention, elevations (22) influencing the flow of fuel in the flow outlet area (14) are disposed therein.

Description

Fuel injector

State of the art

The invention relates to a fuel injector according to the preamble of the main claim.

There is already a fuel injector out of the

No. 4,759,335 is known with a valve closing body, which cooperates with a sealing seat of a valve seat, and with a downstream of the sealing seat

Flow outlet area. The known

Fuel injector produces a spray, the average drop diameter of which for future use

Exhaust emissions regulations are not sufficiently low.

Advantages of the invention

The fuel injector according to the invention with the characterizing features of the main claim has the advantage that the atomization is improved in a simple manner by arranging bumps or elevations influencing the fuel flow in the flow exit area. In this way, the average droplet diameter of the spray can be used without the need for additional auxiliary energy be reduced so that lower exhaust emissions can be achieved.

The measures listed in the subclaims allow advantageous developments and improvements of the fuel injector specified in the main claim.

It is particularly advantageous if the flow exit area is formed by a first wall and a second wall opposite the first wall, an outlet gap being formed between the first wall and the second wall, since the fuel jet flows out of the fuel injection valve in a defined manner in this way.

It is also advantageous if, seen in the direction of flow, the second wall ends with a second trailing edge after the first wall with a first trailing edge, since this represents a particularly simple embodiment.

According to an advantageous exemplary embodiment, the elevations have a height measured perpendicular to a surface of the flow exit area, which is less than 100 micrometers and greater than the roughness peaks of the base area.

It is very advantageous if the projections are arranged in the exit gap, since a so-called Karmann ^Λ specific vortex street is generated in this manner, the periodically detaching vortices create turbulence, so that the fuel spray as disintegrates into smaller droplets in the prior art. It is also advantageous if the elevations are arranged downstream of the first trailing edge, since in this way the fuel jet already breaks down into many individual jets with a large jet surface at the elevations.

It is furthermore advantageous if the elevations are cylindrical, tetrahedral, pyramid-shaped, conical, prismatic, cuboid, hemispherical or knob-shaped, since in this way a sufficiently large amount of turbulence can be generated in the fuel jet emerging from the fuel injection valve to cover the surface of the fuel jet Excite vibrations and thereby atomize the fuel jet into very small drops.

It is also advantageous if the height of the elevations increases or decreases continuously or step-wise downstream, since the fuel jet is split into many individual jets at the elevations, which then collide less frequently downstream with other individual jets.

According to an advantageous embodiment, the elevations are arranged in rows provided transversely to the flow, the rows being provided, for example, offset from one another.

It is also advantageous to generate the elevations by roughening, micro-embossing, laser ablation, etching, micro-electroplating or applying a coating, since these are suitable methods for producing the elevations. drawing

Embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description.

1 shows a first exemplary embodiment of a fuel injection valve, FIG. 2 shows a partial plan view of the first exemplary embodiment, FIG. 3 shows a second exemplary embodiment, FIG. 4 shows a third exemplary embodiment, FIG. 5 shows a partial plan view of the third exemplary embodiment, FIG a fourth exemplary embodiment, FIG. 7 a fifth exemplary embodiment, FIG. 8 a so-called A valve and FIG. 9 a so-called I valve.

Description of the embodiments

Fig.l shows simplified a first embodiment of a fuel injector designed according to the invention.

The fuel injector is used to atomize fuel as a spray to reduce fuel consumption and exhaust emissions. The fuel is injected, for example, in the so-called intake manifold injection into an intake pipe or in the so-called direct injection directly into a combustion chamber of the internal combustion engine.

The fuel injector has a valve housing 1 with an inlet channel 2 for the fuel. A schematically represented actuator 3 for the axial adjustment of a valve needle 4 is arranged in the valve housing 1. The actuator 3 is, for example, one with an excitable coil interacting magnetic armature, a hydraulic element, a piezo actuator or the like.

The valve needle 4 is axially movable in the valve housing 1 and has, for example, a needle shaft 7 facing the actuator 3 and a valve closing body 8 facing away from the actuator 3. The actuator 3 transmits its movement directly or indirectly to the needle shaft 7 of the valve needle 4, as a result of which the valve closing body 8 interacting with a valve seat 9

Fuel injection valve opens or closes in the direction of a valve axis 5. The fuel injection valve has, for example, a so-called spherical conical seat, the valve seat 9 being, for example, conical and the valve closing body 8 having a spherical or radial section 10 which interacts with the valve seat 9. However, the fuel injector can of course also have a different design, for example a ball-ball seat, a cone-cone seat or a cone-ball seat. When the fuel injection valve is closed, the valve closing body 8 lies tightly over its entire circumference on the valve seat 9 with line or surface contact, which is referred to below as the sealing seat 11.

Downstream of the valve seat 9 is included

Flow exit area 14, from which the fuel is admixed as a so-called free jet to the air drawn in by the internal combustion engine.

The flow exit area 14 is through a first

Wall 15 and a second wall 16 opposite the first wall 15 are formed, an outlet gap 17 being formed between the first wall 15 and the second wall 16, through which the fuel 20 flows out when the fuel injection valve is open. The first wall 15 extends from the sealing seat 11 to a first trailing edge 18 and the second wall 16 extends from the sealing seat 11 in the direction of flow to a second trailing edge 19.

The first wall 15 and the second wall 16 can, for example, be connected to one another in one piece or can also be provided on a separate part in each case. The outlet gap 17 is designed as a closed flow channel, the cross section of which can have any shape, for example circular, ring-shaped or rectangular. The second wall 16 with the second trailing edge 19 ends on the side facing away from the sealing seat 11 downstream of the first trailing edge 18 of the first wall 15. The first trailing edge 18 and the second trailing edge 19 can of course also lie in a same plane perpendicular to the valve axis 5.

According to the invention, 14 unevenness or elevations 22 are arranged in the flow exit area, which in the

The fuel flow protrude into it and influence or disrupt it in this way.

The elevations 22 are opposite a base surface 23 of the base wall, for example formed on the second wall 16

The flow exit area 14 is raised and has a height measured perpendicular to the base 23, which is, for example, less than 100 micrometers and greater than the height of the roughness peaks of the base 23.

The elevations 22 can be arranged side by side as desired, for example in one or more rows 24 which are transverse to the flow (FIG. 2). The rows 24 are arranged one behind the other as seen in the direction of flow, with the elevations 22 of a row 24, for example the elevations 22 of the adjacent rows 24 are arranged offset from one another.

The elevations 22 can be arranged in the outlet gap 17 and / or with the second trailing edge 19 lying downstream, downstream of the first trailing edge 18. The elevations 22 can be provided on the first wall 15 and / or on the second wall 16. The elevations 22 protrude from one of the two walls 15, 16 into the outlet gap 17 and can extend as far as the opposite wall 15, 16.

The bumps or elevations 22 are, for example, cylindrical, tetrahedral, pyramidal, conical, prismatic, cuboid, hemispherical, knob-shaped or similar.

The elevations 22 can be aligned with the flow as desired, for example the elevations 22 can be aligned with an edge or a surface in the direction of the flow.

Pyramids and tetrahedra have a streamlined shape that avoids or at least reduces flow turbulence on the downstream side, so that little or no deposits occur on the downstream side of the pyramids or tetrahedra.

The fuel is conducted in the valve housing 1 starting from the inlet channel 2 to the valve closing body 8 upstream of the sealing seat 11. When opening the

Fuel injection valve lifts the valve closing body 8 from the sealing seat 11, so that fuel flows through an outlet opening formed between the valve closing body 8 and the valve seat 9 into the fuel jet Outlet gap 17 of the flow outlet region 14 flows out.

In the outlet gap 17, the fuel jet is spread over the entire circumference by the surface of the

Flow exit area 14 guided, while the fuel jet is only partially guided along the circumference as a partial free jet with the second outflow edge 19 downstream in the flow direction downstream of the first outflow edge 18. The fuel jet leaves the

Flow exit area 14 of the fuel injection valve downstream of the second trailing edge 19 as a complete free jet and breaks down into many small individual drops. The smaller the average drop diameter, the lower the consumption of the internal combustion engine and the lower the exhaust gas emissions.

The fuel jet emerging through the outlet gap 17 when the fuel injection valve is open flows around and / or overflows the elevations 22, considerable turbulence being generated in the flow, which excite vibrations on the surface of the fuel jet. Due to the vibrations on the surface of the fuel jet, the fuel jet breaks up into particularly small drops. This improvement in atomization is achieved without using additional energy. The arrangement of the elevations 22 in the flow exit area 14 is therefore a simple and inexpensive way of producing smaller drop diameters than in the prior art.

If the elevations 22, such as the pyramids and the tetrahedra, have oblique surfaces, the fuel jet is already divided into many individual jets when flowing around and / or overflowing the elevations 22, since the flow follows the oblique surfaces transversely to Main flow is deflected and tears off at the downstream edges of the elevations 22 as a free jet. The individual jets generated on the elevations 22 have a larger jet surface overall than the fuel jet upstream of the elevations 22.

The elevations 22 are also produced, for example, by roughening, sandblasting, roller burnishing, micro-embossing, laser ablation, etching, micro-electroplating or applying a coating.

2 shows, in a plan view, a simplified partial view of the first exemplary embodiment according to FIG. In the fuel injector according to FIG. 2, the parts that remain the same or have the same effect as the fuel injector according to FIG. 1 are identified by the same reference numerals.

3 shows in a partial section, simplified, a second exemplary embodiment of a fuel injection valve.

In the fuel injector according to FIG. 3, the parts that remain the same or have the same effect as the fuel injector according to FIGS. 1 and 2 are identified by the same reference numerals.

The fuel injector according to FIG. 3 differs from the fuel injector according to FIG. 1 in that the elevations 22 are not designed as pyramids but as cylinders.

FIG. 4 shows a third exemplary embodiment of a fuel injection valve in simplified form in a partial section.

In the fuel injection valve according to FIG. 4, the fuel injection valve according to FIG. 1 to FIG. 3 parts that remain the same or have the same function are identified by the same reference numerals.

The fuel injection valve according to FIG. 4 differs from the fuel injection valve according to FIG. 1 in that the elevations 22 are not designed as pyramids but as tetrahedra.

The height of the elevations 22, for example the tetrahedron, can decrease or increase gradually or continuously in the flow direction. Since the individual beams 26 tearing off at the elevations 22 tear off as a free jet at different distances from the base area 23, there are few collisions between the individual beams 26, so that these are retained and have a large surface area.

The height of the elevations 22 of a row 24 is constant, for example, but can also be changed, for example according to a sine curve.

5 shows, in a top view, a simplified partial view of the third exemplary embodiment according to FIG. In the fuel injection valve according to FIG. 5, the parts that remain the same or have the same effect as the fuel injection valve according to FIG. 1 are identified by the same reference numerals.

6 shows, in a partial section, a fourth exemplary embodiment of a fuel injector in a simplified manner.

In the fuel injection valve according to FIG. 6, the parts that are the same or have the same effect as the fuel injection valve according to FIGS. 1 to 5 are identified by the same reference numerals. The fuel injector according to FIG. 6 differs from the fuel injector according to FIG. 1 in that the elevations 22 are designed as knobs.

The elevations 22 are applied galvanically, for example, as a structural layer 25. The structural layer 25 consists of a flat layer 26 on which, for example, hemispherical elevations 22 are provided. The structure layer 25 is made of chrome, for example. The diameter of the hemispherical

Elevations 22 are, for example, between 0 and 30 micrometers. The structure layer 25 can be produced, for example, by means of a known structure chromium process. The thickness of the structural layer 25 continuously decreases, for example, at an edge of the structural layer 25 facing the sealing seat 11, in order to avoid a step that disturbs the fuel flow.

The production of the structural layer 25 does not require high-precision machining of the surface and is therefore simple and inexpensive.

7 shows in a partial section, simplified, a fifth exemplary embodiment of a fuel injector.

In the fuel injection valve according to FIG. 7, the parts that are the same or have the same effect as the fuel injection valve according to FIGS. 1 to 6 are identified by the same reference numerals. The fuel injector according to FIG. 7 differs from the fuel injector according to FIG. 1 in that the elevations 22 in the outlet gap 17 of the

Flow exit area 14 are arranged and extend from the first wall 15 to the second wall 16. When the elevations 22 are arranged in the outlet gap 17, a so-called vortex trail is formed in the flow downstream of each elevation 22, which is also referred to as Karmann ^Λ see vortex street. With the flow, vortices periodically detach from each elevation 22 in the

₍ Flow creates additional turbulence and in this way promotes a breakdown of the fuel jet into droplets that are as small as possible. The smaller the cross section of the elevation 22 that is exposed to flow and the smaller the distances between the elevations 22, the higher the turbulence generated by the vortex wake Staggering the individual rows 24 also increases the turbulence in the fuel jet, Fig. 8 shows a simplified so-called A-valve, the

Valve closing body 8 performs a stroke seen in the flow direction to the outside.

In the fuel injector according to FIG. 8, the parts that are the same or have the same effect as the fuel injector according to FIGS. 1 to 7 are identified by the same reference numerals.

According to this embodiment, the first wall 15 on the valve seat 9 and the second wall 16 is at the _t

Valve closing body 8 formed. The valve closing body 8 widens from an end of the needle shaft 7 facing away from the actuator 3 in the flow direction up to the second trailing edge 19, which is downstream in the flow direction compared to the first trailing edge 18 formed on the valve seat 9. The valve seat 9 widens downstream of the sealing seat 11 up to the first trailing edge 18.

The outlet gap 17 is provided between the valve closing body 8 and the valve seat 9. The elevations 22 are provided, for example, on the valve closing body 8 downstream of the sealing seat 11 and upstream of the second trailing edge 19 and / or on the valve seat 9 downstream of the sealing seat 11 and upstream of the first trailing edge 18.

FIG. 9 shows in simplified form a so-called I-valve, the valve closing body 8 of which carries out a stroke against the flow direction inwards.

In the fuel injector according to FIG. 9, the parts that are the same or have the same effect as the fuel injector according to FIGS. 1 to 8 are identified by the same reference numerals.

According to this exemplary embodiment, the first wall 15 and the second wall 16, which are formed on a valve seat body 31, form the outlet gap 17 which is designed as a flow channel. The flow channel downstream of the valve seat is, for example, cylindrical in a first region 29 and then widens in a second Area 30 conical in the direction of flow. The first trailing edge 18 and the second trailing edge 19 lie in one plane. The elevations 22 are arranged, for example, in the second region 30.

When the fuel injection valve is open, the fuel is set into rotation, for example by means of a swirl disk, not shown, so that the flow entering the outlet gap 17 forms a rotationally symmetrical lamella due to the centrifugal force and flows along the first wall 15 and the second wall 16. The fuel flows around and overflows the elevations 22 and is atomized downstream of the elevations 22.

Claims

Expectations

1. Fuel injector with a valve closing body which interacts with a sealing seat of a valve seat and with a flow exit area for fuel arranged downstream of the sealing seat, characterized in that elevations (22) influencing the fuel flow are arranged in the flow exit area (14).

2. Fuel injection valve according to claim 1, characterized in that the flow exit region (14) is formed by a first wall (15) and a second wall (16) opposite the first wall (15), between the first wall (15) and the second wall (16) an outlet gap (17) is provided.

3. Fuel injection valve according to claim 2, characterized in that the elevations (22) on the first wall (15) and / or on the second wall (16) of the flow exit region (14) are arranged.

4. Fuel injection valve according to claim 2, characterized in that the second wall (16) ends with a second trailing edge (19) compared to the first wall (15) with a first trailing edge (13) in the flow direction after the first trailing edge (18).

5. The fuel injector according to claim 1, characterized in that the elevations (22) have a height measured perpendicular to a surface (23) of the flow exit area (14), which is less than 100 micrometers and greater than the roughness peaks of the surface (23) ,

6. Fuel injection valve according to claim 2, characterized in that the elevations (22) are arranged in the outlet gap (17).

7. Fuel injection valve according to claim 4, characterized in that the elevations (22) are arranged downstream of the first trailing edge (18).

8. The fuel injector according to claim 1, characterized in that the elevations (22) are cylindrical, tetrahedral, pyramidal, conical, prismatic, cuboid, hemispherical or knob-shaped.

9. The fuel injector according to claim 1, characterized in that the height of the elevations (22) increases or decreases downstream or continuously.

10. Fuel injection valve according to claim 1, characterized in that the elevations (22) are provided in one or more rows (24) arranged transversely to the flow.

11.Fuel injection valve according to claim 10, characterized in that the elevations (22) from row (24) to row (24) are arranged offset to one another.

12. Fuel injection valve according to claim 1, characterized in that the elevations (22) are generated by roughening, micro-embossing, laser ablation, etching, micro-electroplating or application of a coating.