EP3080435B1 - Nozzle head and fluid injection valve - Google Patents

Description

The invention relates to a nozzle head and a fluid injection valve, in particular a fuel injection valve.

Fuel injection valves are known with a nozzle head for atomizing a fluid. Usually, such fuel injection valves are used for atomizing fuel in a combustion chamber of an internal combustion engine. In particular, if it concerns a so-called direct injection of the fuel into the combustion chamber in an internal combustion engine designed as a gasoline engine, the fuel, among other things with the help of the nozzle head, very fine to atomize. to produce as complete a combustion as possible in a gasoline engine, a fine mixture of air present in the combustion chamber and the injected fuel is required.

With the help of direct injection, the fuel is injected in gasoline engines today's internal combustion engines directly into the combustion chamber, which compared to an older principle of the introduction of fuel, the so-called intake manifold injection, the advantage of reduced fuel consumption is effected. Furthermore, a regulation of an exhaust gas aftertreatment system of the internal combustion engine with the aid of direct injection is considerably improved.

Another advantage of direct injection is an improvement in the elasticity of the internal combustion engine with regard to its response in dynamic operation, since the fuel passes into the combustion chamber much faster than in the intake manifold injection, in which the fuel together with the via a gas inlet valve incoming combustion air enters the combustion chamber.

The problem, however, is that the required homogeneous mixture must be prepared within a short period of time to achieve the stated advantages of direct injection. Because the fuel is quickly introduced into the combustion chamber, evaporation and mixing of the fuel with the combustion air have little time available.

Thus, the fuel injection valve and its jet preparation play a special role, in particular in direct injection. The fuel is to be introduced into the cylinder with the help of a particularly fine atomization, i. a droplet size of the fuel should be made as small as possible to allow rapid processing - i. in a very short period of time a homogeneous mixture - can be achieved.

Also, the fuel should not get to the cylinder walls of the combustion chamber, since there is the possibility of a so-called oil dilution. The oil dilution, since it causes a change in a lubricant composition, can cause severe damage to the internal combustion engine due to insufficient viscosity behavior of the diluted lubricating oil. A piston bottom and / or gas inlet valves should not be wetted by the fuel, because from there the fuel can evaporate only insufficiently.

Another problem is deposition of the fuel at the fuel injection valve. After several hours of operation of the internal combustion engine, the fuel injection valve has a solid and sooty deposit layer. In this deposition layer fuel can accumulate subsequent injection cycles. In later combustion cycles, this fuel may be considered Escape fuel vapor and lead to an undesirable sooting combustion. This leads to an unfavorably large, possibly impermissible number of soot particles in the exhaust gas of the internal combustion engine.

It is known that a reduction of the soot particles is to be achieved in that nozzle holes of the nozzle head are introduced by means of a laser process in the nozzle head. This should have the advantage over a conventional Elektrodier method that sharp-edged nozzle holes can be generated. Another way to reduce the deposit layer is to increase a fuel pressure upstream of the nozzle head, so that an exit velocity of the fuel is so large that deposits are avoided and thus no deposit layer is built. However, this is very costly, since an increase in the fuel pressure can only be realized with a higher energy consumption. Furthermore, all components exposed to the fuel pressure must have a higher strength adapted to the higher fuel pressure, which can be achieved on the one hand with more expensive materials and / or with an increase in a corresponding component wall.

DE 3801778 A1 discloses an aperture for an electromagnetically operable fuel injection valve for internal combustion engines. The diaphragm is made of a material of high natural hardness, such as monocrystalline silicon, and processed by a stepwise etching process. The contouring of the particularly accurate hole can be done by the use of high-energy radiation.

US 5054691 A relates to an electromagnetically operated injector for an electronically controlled fuel injection system, which controls the fuel oil injection by means of a displacement of a ball valve unit. The ball valve unit comprises a Flat anchor and a ball valve, the flat armature is slid without a guide sliding. When the ball valve unit is sucked and moved to an open state, the flat armature abuts against a thin plate of high magnetic resistance. A compressed compression spring acts on the top of the flat armature, with an upper end of the compression spring abutting a spring adjustment tube so that the spring force acting on the flat armature can be altered by adjusting the spring adjustment tube. Both the compression spring and the ball valve are arranged in the magnetic stator of the solenoid, wherein the flat armature and the ball valve are arranged so that the spring force biases the ball valve perpendicular to the inclined cone concave on top of the valve seat.

The DE 3230671 A1 is based on an injection valve which serves to supply fuel to internal combustion engines with fuel injection systems. The injector includes a movable valve member which cooperates with a fixed valve seat provided on a nozzle body. The valve seat is convexly formed on a shoulder of the nozzle body. The valve member has a concave sealing surface cooperating with the valve seat. Downstream of the valve seat, a collecting space is formed between the valve part and the nozzle body, starting from the swirl channels, which open into a processing bore, through the open end of the fuel is injected.

From the WO 02/29244 A1 a fuel injection valve for fuel injection systems of internal combustion engines is known, which includes, inter alia, an actuator and a movable valve member, which cooperates for opening and closing the valve with a fixed valve seat, which is formed on a valve seat body. Downstream of the valve seat, a disc-shaped swirl element is arranged, which has at least one inlet region and at least one outlet opening, and which has at least one swirl channel upstream of the Outlet has. The inlet area in the swirl element is centrally impinged. From him all swirl channels go out, whereby the swirl channels exclusively radially from inside to outside flowing through fuel a swirl component is impressed.

At the fuel injection valve of EP 718490 A2 a perforated disc carrier is provided downstream of the valve seat surface, which has an inner cup-shaped support portion into which a plurality of perforated discs with different dimensions can be inserted. The pot-shaped perforated plate carrier is to partially on the lower end face of the valve seat surface having valve seat body and is firmly connected thereto. The selected according to the appropriate requirements and used in the support section perforated disc is also in the mounted state on the lower end face of the valve seat body.

US 5,752,316 discloses a nozzle plate to be mounted on a fuel jet portion of an injector. The nozzle plate has a plurality of nozzle holes for injecting fuel. The nozzle plate includes a curved surface formed on an inlet peripheral edge of each of the nozzle holes, and a cylindrical protrusion formed on an outlet of each of the nozzle holes. The cylindrical projection has the same inner diameter as the nozzle hole.

It is an object of the present invention to provide a nozzle head for a depleted fuel injection valve.

This object is achieved by a nozzle head according to claim 1. Advantageous embodiments with expedient and non-trivial developments of the invention are specified in the subclaims.

In one aspect, a nozzle head for a fluid injector is provided. The nozzle head is intended to atomize the fluid. The fluid is preferably a fuel for an internal combustion engine, in particular for gasoline. The nozzle head has a longitudinal axis.

According to a further aspect, a flow-through valve body is specified for a fluid injection valve. At a first end of the valve body is a supply formed device for supplying the fluid. At a remote from the first end second end of the valve body of the nozzle head for atomizing the fluid is arranged. In particular, the nozzle head and the valve body have a common longitudinal axis. The nozzle head may be formed integrally with a base body of the valve body. Alternatively, the nozzle head may be a separate workpiece which is fixed to the main body of the valve body.

According to a third aspect, a fluid injection valve - in particular a fuel injection valve - is specified with the nozzle head or with the valve body. The fuel injection valve is in particular provided to inject fuel directly into a combustion chamber of the internal combustion engine.

The nozzle head has a nozzle hole disc. The nozzle perforated disk has an end face and an inner face opposite the end face. In one embodiment, the end face is formed facing away from the first end of the valve body and the inner surface is formed facing the first end of the valve body. In one embodiment, a first axial distance extending in the direction of the longitudinal axis is formed between the inner surface and the end surface.

The nozzle perforated disk has at least one nozzle hole channel which completely penetrates the nozzle perforated disk in the direction of the longitudinal axis. In addition, another nozzle hole channel is formed penetrating the nozzle disk.

An outlet surface is formed on the first channel end assigned to the nozzle-hole channel, and an outlet surface is formed on a second channel-end of the nozzle-hole channel that faces away from the first channel end. The entrance surface is disposed on the inner surface of the nozzle hole disc. One Nozzle hole projection of the nozzle hole channel, which is positioned in particular at the first axial distance from the inlet surface, has a channel wall. The duct wall is formed over a circumference of the nozzle hole protrusion. In other words, the channel wall of the nozzle hole projection defines a portion of the nozzle hole channel. The channel wall runs completely around a channel axis of the nozzle hole channel. The channel wall has a wall height extending from the end face in the direction of the longitudinal axis, in particular away from the inner face, such that the second channel end corresponds to a channel wall end of the channel wall which faces away from the end face.

With the help of the channel wall of the nozzle hole projection of the nozzle hole channel is thus extended in its along the longitudinal axis formed axial extent. Was the second end of the channel, and thus the exit surface, according to the prior art contained in a smooth face, e.g. in a first axial distance from the entry surface in the direction of the longitudinal axis, the second channel end is now positioned with the aid of the nozzle hole projection in a distance from the entry surface which is increased by the wall height. In one embodiment, the distance of the exit surface corresponds to a sum of the first axial distance and the wall height. This has the consequence that the outlet surface of the nozzle hole channel, which is formed at the second channel end, spaced from the end face is configured on the nozzle hole disc. The second channel end is offset in particular in relation to the end face in the direction away from the inner surface.

If the exit surface is not axially spaced from the end face in the direction of the longitudinal axis, an ambient air present there is sucked in over a circumference of the exit face in the region of the end face. That is, the ambient air present in the area of the fuel jet is entrained by the fuel jet. This effect, the entrainment or entrainment of the air in the region of a fluid jet, is known and is used in particular in water jet pumps for generating large volume flows.

By means of the channel wall, which axially separates the exit surface from the end face in the direction of the longitudinal axis, it is possible to supply ambient air from the nozzle hole channel - i. from the exit surface - to supply escaping fuel. This means that a larger volume flow can be achieved, which realizes an improved, that is, faster fuel treatment. Since the ambient air present over the circumference of the exit surface is entrained with the fuel of the fuel jet, an area pressure is formed in this area, which prevents or at least greatly reduces a backflow of fuel vapor and / or fuel droplets. This means that the risk for the formation of deposits is particularly low. In this way, a deposit-reduced or deposit-free fuel injector is realized.

In one embodiment of the fluid injection valve, a valve needle is arranged in the valve body. The valve needle is axially movable relative to the valve body, such that a closing element of the valve needle in a closed position of the valve needle against a valve seat of the valve body to prevent fluid flow through the nozzle hole channels and the valve needle by means of an actuator unit of the fluid injection valve from the closed position is displaceable to release fluid flow through the nozzle hole channels.

In an advantageous embodiment, the inner surface of the - in particular one-piece - nozzle hole disc on the valve seat. In this way, the nozzle head for comparatively large fluid pressures - eg of 100 bar or More, preferably of 200 bar or more, in particular in a range between 250 bar and 500 bar, the limits are included - used.

In one embodiment of the fuel injection valve according to the invention, the channel wall is designed with a hollow-truncated cone shape. The advantage of this embodiment is that the ambient air present in the region of the channel wall has an inflow direction which is inclined to the fuel jet which emerges from the outlet surface. Thus, the ambient air is the fuel jet improved fed. This means that the flow direction of the guided over the hollow truncated cone-shaped channel wall ambient air crosses the flow direction of the fuel jet, so that a mixing of the fuel jet and the ambient air is already brought about by the flow directions.

The improved feedability can be seen in comparison to a hollow-cylinder-like duct wall. In a hollow cylinder-like designed channel wall, the ambient air has the same flow direction as the fuel jet, so that due to the same flow directions, the feedability and thus thorough mixing takes place only with the help of entrainment of the ambient air.

In one embodiment, the exit surface is smaller than the entry surface. This has the advantage that the fuel, which flows through the nozzle hole channel according to Bernoulli's law of flow at the exit surface has a first speed, which is greater than a second speed, which prevails in the entrance surface or in the region of the entrance surface. Thus, the fuel atomization is improved in a simple manner due to an increase in speed at the exit surface.

In the fuel injection valve of the invention, the nozzle hole disc has a plurality of nozzle hole channels, that is, the other nozzle hole channel is formed penetrating the nozzle hole plate. The nozzle hole channels according to the invention are arranged in a certain, generally uniform, radius of a nozzle hole center, in particular in plan view along the longitudinal axis, wherein the nozzle hole center is in one embodiment on the longitudinal axis. As soon as the fuel is injected, a fuel jet, which is in the form of a cone, is produced per nozzle hole channel. In the region of the nozzle hole center, an inner region is formed in this way, which is bounded by the fuel jets. In this interior, there is less pressure than in an environmental area defined by the fuel jets. In the surrounding area, in the vicinity of the fuel jet, there is a first area pressure, which is smaller than a second area pressure in a surrounding area further from the fuel jet. A third range pressure formed in the inner region is significantly reduced compared to the first range pressure and the second range pressure.

wobei h der Wandungshöhe und D dem freien radialen Abstand entspricht.There is a risk that the third range pressure compared to a first range pressure in the ambient range is so low that a negative pressure in the inner region is formed, which leads to a reversal of the direction of the fuel vapor and / or fuel droplets. That is, the fuel vapor and / or the fuel droplets flow in this case back to the face to settle there in the form of deposits. So that an effective axial distance of the exit surface from the end face is formed, the wall height can be determined as a function of a free radial distance. This free radial distance is a radially formed between the nozzle hole channel and the other nozzle hole channel distance. The Wall height according to the invention can be described as follows, depending on the radial distance: $$H\ge 1/4\cdot D.$$

where h is the wall height and D is the free radial distance.

With such, depending on the free radial distance between the nozzle hole channels determined wall height, a sufficiently large flow channel is configured over which ambient air in the inner region is feasible, so that the third range pressure in the interior is so large that a return flow of fuel vapor and / or fuel droplets inside is particularly well prevented.

The nozzle hole projection may have an outer peripheral surface whose contour is configured in a longitudinal section of a continuously differentiable function according to. Thus, the advantage is created that a tearing off of flow threads of the flowing over the channel wall, entrained by the fuel jet ambient air is avoided. Preferably, the outer circumferential surface is ramp-shaped. In other words, the nozzle hole projection, at least in its region adjacent to the end face, preferably has an outer contour which in longitudinal section has the shape of a continuously differentiable function and / or which is ramp-shaped - ie. in particular in the form of a ramp function - is formed.

In a further embodiment of the fuel injection valve according to the invention, the nozzle hole channel has a first channel region, which is adjacent to the inlet surface Cross-sectional area is smaller than the cross-sectional area of an outlet surface adjacent to the second channel region of the nozzle hole channel. Between the first and the second channel region of the nozzle hole channel has a step in a development.

• Fig. 1 in einer perspektivische Darstellung schematisch eine Düsenlochscheibe eines Kraftstoffeinspritzventils gemäß dem Stand der Technik,
• Fig. 2 in einer perspektivischen Darstellung schematisch die Düsenlochscheibe gemäß Fig. 1 mit Kraftstoffstrahlen während eines Einspritzvorganges,
• Fig. 3 in einer perspektivischen Darstellung schematisch die Düsenlochscheibe mit einer Ablagerungsschicht,
• Fig. 4 in einer Seitenansicht die Düsenlochscheibe gem. Fig. 1, mit einer Kraftstoffstrahlausbreitung zweier nebeneinander angeordneter Düsenlöcher, sowie sich im Bereich der Kraftstoffstrahlen einstellende Bereichsdrücke ohne Rückströmung,
• Fig. 5 in einer Seitenansicht die Düsenlochscheibe gem. Fig. 1, mit einer Kraftstoffstrahlausbreitung zweier nebeneinander angeordneter Düsenlöcher, sowie sich im Bereich der Kraftstoffstrahlen einstellende Bereichsdrücke mit Rückströmung von Kraftstoffdämpfen,
• Fig. 6 in einem Ausschnitt eine vergrößerte Darstellung der Düsenlochscheibe gem. Fig. 5, mit rückströmenden Kraftstofftröpfchen,
• Fig. 7 in einer perspektivischen Darstellung schematisch einen Düsenkopf eines erfindungsgemäßen Kraftstoffeinspritzventils,
• Fig. 8 in einem Ausschnitt eine Seitenansicht der Düsenlochscheibe des erfindungsgemäßen Kraftstoffeinspritzventils, mit einer Kraftstoffstrahlausbreitung, sowie sich im Bereich der Kraftstoffstrahlen einstellende Bereichsdrücke,
• Fig. 9 in einem Ausschnitt die Düsenlochscheibe des erfindungsgemäßen Kraftstoffeinspritzventils in einer ersten Variante, und
• Fig. 10 in einem Ausschnitt die Düsenlochscheibe des erfindungsgemäßen Kraftstoffeinspritzventils in einer zweiten Variante.

Further advantages, features and details of the nozzle head, the valve body and the fluid injector will become apparent from the following description of preferred embodiments and from the drawing. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention. Identical or functionally identical elements are assigned identical reference numerals. For reasons of clarity, it is possible that the elements are not provided with reference numbers in all figures, but without losing their assignment. Show it:

• Fig. 1 1 schematically shows a nozzle perforated disk of a fuel injection valve according to the prior art,
• Fig. 2 in a perspective view schematically the nozzle hole disc according to Fig. 1 with fuel jets during an injection process,
• Fig. 3 in a perspective view schematically the nozzle hole disc with a deposit layer,
• Fig. 4 in a side view of the nozzle hole disc gem. Fig. 1 , with a fuel jet propagation of two juxtaposed nozzle holes, as well as in the area the fuel jet setting range pressures without backflow,
• Fig. 5 in a side view of the nozzle hole disc gem. Fig. 1 , with a fuel spray propagation of two juxtaposed nozzle holes, as well as in the area of the fuel jet adjusting range pressures with backflow of fuel vapors,
• Fig. 6 in a section of an enlarged view of the nozzle hole disc gem. Fig. 5 , with backflowing fuel droplets,
• Fig. 7 1 is a perspective view of a nozzle head of a fuel injection valve according to the invention,
• Fig. 8 in a section of a side view of the nozzle hole disc of the fuel injection valve according to the invention, with a fuel spray propagation, and adjusting in the range of the fuel jets range pressures,
• Fig. 9 in a section of the nozzle hole disc of the fuel injection valve according to the invention in a first variant, and
• Fig. 10 in a section of the nozzle hole disc of the fuel injection valve according to the invention in a second variant.

The nozzle hole disc of a prior art fuel valve is according to FIG Fig. 1 formed, wherein the fuel injection valve as a so-called multi-stream injector ("multi-jet injector") is formed, that is, the nozzle hole disc 10 has a plurality of nozzle hole channels 12, wherein the nozzle hole channel 12, the nozzle hole disc 10 is formed completely penetrating.

The fuel injection valve comprises a non-illustrated valve body having a longitudinal axis 14, wherein at a first end of the valve body, a supply device not shown for supplying a fluid, usually fuel for internal combustion engines is formed.

At a remote from the first end second end of the valve body of the nozzle head 11 is arranged with the nozzle hole disc 10 for atomizing the fluid. The nozzle hole disc 10 has an end face 16 remote from the first end.

The nozzle hole channel 12 has at a first channel end 18 an entry surface 22 (s. Figures 9 and 10 ) and at a side remote from the first channel end 18 second channel end 20 an exit surface 24, wherein the inlet surface 22 is formed on a remote from the end face 16 formed inner surface 26 of the nozzle hole disc 10. Between the inner surface 26 and the end face 16 there is a first axial distance W1 extending in the direction of the longitudinal axis 14.

The nozzle hole disc 10 is received in the nozzle head 11 of the fuel injection valve. The nozzle head 11 is positioned at the second end of the fuel injection valve, which is arranged in a combustion chamber, not shown, of an internal combustion engine, not shown. This means that fuel, which is supplied by means of the fuel injection nozzle of the internal combustion engine, is injected directly into the combustion chamber. In particular, it is important for optimal, ie efficient and low-emission operation of the internal combustion engine, that the fuel with the aid of the fuel injection nozzle finely atomized - that is supplied in very fine droplets - the combustion chamber. This fine Atomization leads to a rapid fuel treatment, ie a mixture formation between the fuel injected into the combustion chamber and a combustion air already present in the combustion chamber and usually partially compressed.

In particular, the fuel treatment in a trained as a gasoline engine or gasoline engine internal combustion engine makes high demands on the fine atomization. Because this type of internal combustion engine works based on a so-called spark ignition, i. a fuel-air mixture present in the combustion chamber with the aid of mixture formation is ignited with the aid of a spark plug. This form of ignition requires a homogeneous fuel-air mixture, so that complete combustion of the fuel-air mixture can be brought about. Since this is required in a very short time within an injection cycle, there is a need for a fine atomization by means of the fuel injection valve.

An equally high requirement for a fine atomization of the fuel is also given in a trained as a diesel engine internal combustion engine. The present in the combustion chamber of an engine designed as a diesel engine air-fuel mixture is burned due to a so-called auto-ignition. That is, the ignition takes place here due to high temperatures in the combustion chamber, which can be achieved by a high compression pressure. The air-fuel mixture ignites at different locations, the so-called ignitions, in the combustion chamber and combustion progresses due to an increasing temperature and increasing pressure in the air-fuel mixture. Here, insufficient combustion leads to a so-called soot formation, which can be avoided by means of a fine atomization.

The fine atomization is achievable with a plurality of nozzle hole channels 12 formed on the nozzle perforated disk 10. In principle, a fineness of the atomization depends on the diameter of the nozzle hole channel 12 and on the fuel pressure. The smaller the diameter of the nozzle hole channel 12 or the diameter of the exit surface 24 and the higher the pressure, the finer the atomization. It should be noted that a fuel mass to be injected, however, also depends on the diameter of the nozzle hole channel 12. D. h. in turn, the smaller the exit area 24, the lower the fuel mass per exit area 24. Thus, a number of the nozzle hole channels 12 must be taken into account to achieve the desired fuel mass to be injected. At this point, it should not go unmentioned that just as decisive for a fine atomization is a so-called injection pressure.

In order that atomization can be realized, the nozzle hole channels 12 are introduced into the nozzle perforated disk 10 in a completely penetrating manner through the nozzle perforated disk 10. In an injection process, the inlet surfaces 22 of the nozzle hole channels 12 are released by means of a nozzle needle, not shown, so that the fuel located in a valve body of the fuel injection valve flows through the outlet surfaces 24 under a corresponding Einspitzdruck the valve body.

Fig. 2 schematically shows from the exit surfaces 24 escaping fuel in the form of fuel jets 28 during an injection process. According to laws of fluid mechanics, the fuel escapes from a nozzle hole channel 12 to form a fuel cone.

The problem is that after several cycles of the internal combustion engine, ie after several ignitions and corresponding burns, a solid and soot-like Deposit 30 may form in the region of the outlet cross-sectional areas 24, as exemplified in Fig. 3 is shown.

This deposit 30 is a result of a pressure in the region of the fuel jet 28 during a Einspitzvorganges applied pressure ratio. For explanation, see Fig. 4 a side view of the nozzle hole disc 10 according to the prior art shown. In an environment of two fuel jets emerging from in each case one nozzle opening, different pressures occur in different regions of the fuel jets, hereinafter referred to as range pressures.

By the outflow of the fuel from the exit surfaces 24, ambient air is drawn in an exit region of the fuel. In other words, the ambient air located in the region of the fuel jet 28 is entrained by the fuel jet 28.

This means that in a suction region, which is located on the end face 16 in the area of the exit face 24, a lower first range pressure p1 is established than in an area remote from the exit face 24 in which a second range pressure p2 prevails, s. FIGS. 4 and 5 , Specifically, in an inner region 32 formed between the fuel jets 28, a third range pressure p3 is formed which is greatly reduced from the first range pressure p1 and the second range pressure p2, and represents an extreme negative pressure. This third range pressure p3, which is greatly reduced in comparison to the other range pressures, sets in the inner region 32, since no or only little ambient air or combustion air can flow in here.

As a consequence of this third range pressure p3, turbulence between outflowing ambient air and backflowing fuel vapors can be caused. A Return flow direction is by means of the return arrow 36 in the inner region 32 between the fuel jets 28 of the FIG. 5 indicated. The fuel vapors form due to high combustion chamber temperatures during the injection process. In other words, the fuel is in a liquid state of matter and a vapor state during the injection process.

In other words, this means that fuel leaving the exit surface 24 usually and predominantly in the direction of the directional arrow y moves away from the end face 16. However, due to the negative pressure p3, which forms in the inner region 32 between the fuel jets 28, there is a backflow of a fuel vapor-fuel droplet mixture. This is deposited on the end face 16.

The fuel vapors flowing back due to turbulence may be mixed with fuel droplets 34, s. Fig. 6 , These fuel droplets 34 are then accelerated in the direction of the end face 16 of the nozzle hole disc 10 and deposited in the region of the exit surfaces 24 on the end face 16 from. In other words, at least in part, the fuel particles located in the inner region 32 have a flow direction reversal. This flow direction reversal is reduced with an increase in the exit velocity of the fuel from the exit surfaces 24, which can be realized by increasing the Einspitzdruckes, since with increasing exit velocity of the third range pressure p3 is no longer sufficient to accelerate the fuel droplets in the direction of the end face 16.

The nozzle hole disc 10 of the fuel injection valve according to the invention is according to Fig. 7 educated. The nozzle hole channel 12 has a nozzle hole projection 25 with a channel wall 40, with the aid of the exit surface 24th is spaced away from the end surface 16 in the direction of the inner surface 26 away.

In the present case, the nozzle hole projection 25 is positioned at a first axial distance W1 from the entry surface 22. In the region of the nozzle hole projection 25, the channel wall 40 is formed over a circumference of the nozzle hole channel 12, which has a wall height h extending from the end face 16 in the direction of the longitudinal axis 14.

Thus, the second channel end 20 corresponds to a side facing away from the end face 16 channel wall end 46 of the channel wall 40th

In other words, in this case, the channel wall 40 of the nozzle hole 25 extends from a plane common to the end face 16 to the nozzle hole channel 12 such that its axial extent is formed starting from the face 16 in the direction of the fuel jet 28.

The embodiment of the fuel injection valve according to the invention has a channel wall 40, which is designed as a hollow truncated cone. The hollow frusto-conical duct wall 40 has a conically tapering and circumferential in the region of the nozzle hole projection 25 laterally around the nozzle hole channel 12 inner peripheral surface, so that the outlet surface 24 is smaller than an upstream at a distance h from the exit surface 24 positioned channel cross-sectional area of the nozzle hole 25, which has the diameter d indicated in the figures.

In a variant of the embodiment, the inner circumferential surface has the shape of a cylinder jacket, in particular a circular cylinder jacket. In a no closer shown further embodiment, the channel wall 40 is formed as a hollow cylinder.

The wall height h is determined such that ambient air can be supplied to the inner region 32 in the quantity entrained when the fuel flows out of the outlet surface 24 in accordance with the principle of the water jet pump.

Between two oppositely arranged nozzle hole channels 12, 13, d. H. between a nozzle hole channel 12 and another nozzle hole channel 13, a free radial distance D is formed. The free radial distance D is the distance between the nozzle hole channel 12 and the other nozzle hole channel 13 to understand, which is formed between two oppositely disposed channel walls 40. The free radial distance D is the distance between the nozzle hole channel 12 and the further nozzle hole channel 13, which is determined in a longitudinal axis 14 along the axial distance from the end face 16 and the wall height h corresponds.

It should be noted that the free radial distance D present is to be determined along a diameter of the nozzle hole disc 10. This can be assumed, since usually the nozzle hole disc 10 has a circular circumference. However, if the nozzle hole disc 10 has no circular circumference and / or an arrangement of the nozzle hole channels are not positioned symmetrically about a center of the nozzle hole disc 10, the free radial distance D between two opposite nozzle hole channels 12 is to be determined.

The wall height h can be determined as a function of the radial distance D: $$H\ge 1/4\cdot D,$$

As in Fig. 7 represented, between each two adjacent nozzle hole channels 12, a winding-like flow channel 41 is formed. So that this flow channel 41 is designed for a sufficient air supply into the inner region 32, a channel wall thickness 42 of the channel wall 40 in the determination of the wall height h is also to be considered. This means that the wall height h is greater than a quarter of the radial distance D to choose. For example, if the radial distance D between the nozzle hole channels 12 6 mm, results in a wall height h of 1.5 mm. So that now a sufficiently large flow channel 41 can be created, the wall height h is to be determined to about 2 mm.

As in the FIGS. 8 to 10 shown, the nozzle hole projection 25 has an outer peripheral surface 44. This outer peripheral surface 44 has in the embodiment of FIG. 9 a ramp-shaped contour 45 in a longitudinal section Fig. 10 this contour 45 is rounded ramp-like, ie formed in the shape of a curved, continuously differentiable function.

As in the Fig. 9 1, the nozzle hole channel 12 is formed in the form of a stepped hole in an alternative embodiment of the fuel injection valve according to the invention, so that the nozzle hole channel 12 has different channel diameters. The channel diameter d1 in a first channel region formed facing away from the entry surface 22 is smaller than a second channel diameter d2 of a second channel region of the nozzle hole channel 12 facing the exit surface 24, so that the first channel region has a smaller cross-sectional area than the second channel region. Between the first and the second channel region, the nozzle hole channel 12 has a step. In the present case, the second channel region extends in the axial direction from the nozzle hole projection 25 beyond the end face 16 in the direction of the inner surface 26.

Claims (8)

1. Nozzle head (11) for atomizing a fluid for a fuel injection valve with a valve body, through which flow can pass, wherein the nozzle head (11) has a longitudinal axis (14) and a nozzle perforated disk (10) which has a front surface (16) and an opposite inner surface (26),
   wherein the nozzle perforated disk (10) has at least one nozzle perforated channel (12) and a further nozzle perforated channel (13) which completely penetrate the nozzle perforated disk (10) in the direction of the longitudinal axis (14), and
   wherein the nozzle perforated channel (12) has an entry surface (22) at its first channel end (18) and an outlet surface (24) at its second channel end (20), which is arranged facing away from the first channel end (18), wherein the entry surface (22) is formed on the inner surface (26), and
   wherein the nozzle perforated channel (12) and the further nozzle perforated channel (13) are arranged lying opposite at a certain radius from a nozzle perforated disk center, wherein

   - the nozzle perforated channel (12) and the further nozzle perforated channel (13) each have a nozzle hole projection (25) which has a channel wall (40) completely encircling a channel axis of the nozzle perforated channel (12) or of the further nozzle perforated channel (13), wherein the channel wall (40) has a wall height h which extends away from the inner surface (26), starting from the front surface (16), in the direction of the longitudinal axis (14) and is configured over a circumference of the nozzle hole projection (25) in such a manner that the second channel end (20) corresponds to a channel wall end (46) of the channel wall (40), which channel wall end is configured so as to face away from the front surface (16),
   characterized in that

   - at an axial distance (W2) from the front surface (16), which axial distance is formed in the direction of the longitudinal axis (14), a free radial distance D is formed between the channel walls (40) the nozzle perforated channel (12) and the further nozzle perforated channel (13), for which: $$h\ge 1/4\cdot D$$

   

   wherein the axial distance (W2) corresponds to the wall height h.
2. Nozzle head (11) according to Claim 1,
   characterized in that the channel wall (40) is of hollow-frustoconical design.
3. Nozzle head (11) according to Claim 1 or 2, characterized in that the outlet surface (24) is configured to be smaller than the entry surface (22).
4. Nozzle head (11) according to one of the preceding claims, characterized in that the nozzle hole projection (25) has an outer circumferential surface (44), the contour (45) of which is formed in a longitudinal section in accordance with a continuously differentiable function.
5. Nozzle head (11) according to the preceding claims, characterized in that the outer circumferential surface (44) is of ramp-shaped design.
6. Nozzle head (11) according to one of the preceding claims, characterized in that the nozzle perforated channel (12; 13) has a first channel region which is adjacent to the entry surface (22) and the cross-sectional area of which is smaller than the cross-sectional area of a second channel region of the nozzle perforated channel (12; 13), which second channel region is adjacent to the outlet surface (24).
7. Nozzle head (11) according to the preceding claim, characterized in that the nozzle perforated channel (12; 13) has a step between the first and the second channel region.
8. Fluid injection valve, with a valve body, through which flow can pass, wherein a supply device for supplying a fluid is formed at a first axial end of the valve body, and a nozzle head (11) according to one of the preceding claims for atomizing the fluid is arranged at a second axial end of the valve body, which second end is formed facing away from the first end, wherein the front surface (16) is configured so as to face away from the first end and the inner surface (26) is configured so as to face the first end.

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