EP2516840A1

EP2516840A1 - Injection valve

Info

Publication number: EP2516840A1
Application number: EP10762643A
Authority: EP
Inventors: Anton Dukart; Olaf Ohlhafer; Dirk Schmidt; Robert Giezendanner-Thoben
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2009-12-21
Filing date: 2010-09-30
Publication date: 2012-10-31
Also published as: CN102713246A; US20120256013A1; WO2011076452A1; DE102009055042A1

Abstract

The invention relates to an injection valve (1), which is used in particular as an injector for fuel injection systems or exhaust gas aftertreatment systems, comprising a shock wave actuator (4), a valve closing body (8) that interacts with a valve seat surface (7) to form a sealing seat (9), and a shock wave amplification channel (22). The shock wave amplification channel (22) is used to conduct shock waves (27) generated by the shock wave actuator (4) to the sealing seat (9) and to amplify said shock waves (27).

Description

description

title

Injection valve prior art

The invention relates to an injection valve, in particular an injector for

Fuel injection systems or for exhaust aftertreatment systems. From DE 10 2006 026 153 A1 a spraying device for fluids is known. The known spray device has a nozzle and an actuator for regulating the fluid flow through the nozzle outlet. In addition, a shock wave actuator for generating shock waves is provided in the fluid in the nozzle. Via the shockwave actuator, shockwaves are generated in the spray device, which are conducted to the fluid located in the nozzle.

In a spraying device for fluids with a shock wave actuator, the problem arises that against an ambient pressure, which is given for example by the pressure in the combustion chamber, must be used. In addition, problems arise in the

Beamforming.

Advantages of the invention

The injection valve according to the invention with the features of claim 1 has the advantage that an injection behavior is improved. Specifically, defined injection jets can be realized and it can be at least largely independent of the ambient pressure, in particular combustion chamber pressure, opening of the

Injector be realized. The measures listed in the dependent claims are advantageous

Further developments of the injection valve specified in claim 1 possible. Advantageously, the shockwave actuator generates shock waves which are conducted to the sealing seat. The physical phenomenon of the shock wave is a strong pressure wave in elastic media, such as liquids that can propagate at supersonic speeds, with high mechanical stresses and pressures in the shock front of the shock wave. The shock wave represents a pressure pulse in which within a fraction of a second the pressure rises steeply and then falls steeply again. The extreme pressure change produced by the pressure wave is further enhanced by the shock wave amplification channel. In this way, the valve closing body can be lifted from the valve seat surface in an advantageous manner in order to open the sealing seat formed between the valve closing body and the valve seat surface. As a result, very high injection pressures can be realized to an advantageous

Atomization to realize even at high ambient pressures. For example, fuel may be injected at a pressure of about 200 MPa (2000 bar) for diesel direct injection or 20 MPa (200 bar) for gasoline direct injection into the combustion chamber of an internal combustion engine. On the one hand, it is possible to realize defined, individual injection jets. On the other hand, it is possible to achieve an opening of the injection valve which is independent of the combustion chamber pressure or another ambient pressure.

It is advantageous that a serving for managing the shock waves, remaining free

Cross-sectional area of the shock wave amplification channel from the Stoßwellenaktorik to the sealing seat towards at least partially decreases. Hereby the non-binding takes

Cross-sectional area preferably evenly from the sealing seat down. This results in an advantageous reinforcement of the shock wave, which exerts a high local pressure and thus a large opening force on the valve closing body on the sealing seat.

Furthermore, it is advantageous that an injector body is provided, which has at least one interior space, that a shockwave reinforcement element is inserted into the interior, that the shockwave reinforcement channel is at least partially configured between an inner wall of the interior space and the shockwave reinforcement element, and that a tip of the shockwave reinforcement element in the

Shock wave amplification channel counter to a propagation direction of the generated

Shock waves is oriented. The shock wave generated by the shock wave actuator runs in the direction of the sealing seat. Here, the shock wave front at the top of

Pierce shock wave reinforcement element. Behind the top narrows the

Shock wave channel, so that the shock wave increasingly amplified. Here, it is also advantageous that the shock wave amplification channel between the inner wall of the interior and the shock wave reinforcement element at least partially annular and / or at least partially partially annular and / or at least partially configured as a ring interrupted several times. Additionally or alternatively, it is advantageous that the shock wave amplifying element at least

is approximately configured as a conical shock wave amplification element and / or that the inner wall of the interior, at least in sections of the

Shock wave actuator tapers to the sealing seat. Furthermore, it is advantageous that the

Inner wall of the interior is configured at least partially conical. As a result, the shock wave amplification channel advantageously as narrowing

Annular gap, which is optionally divided into sections, are formed. The annular gap preferably narrows further in the direction of the sealing seat, so that the shock wave is increasingly reinforced. In the region of the sealing seat, a high pressure of the shock wave, which leads to the opening of the sealing seat, then acts at least approximately uniformly over the sealing seat.

Furthermore, it is advantageous that the valve closing body on the

Shock wave amplifying element is designed. The shock wave amplifying element can be designed in one or more parts. In a multi-part design, the individual parts are connected to each other in a suitable manner. In this case, it is also advantageous that at least one guide element is provided for the shockwave reinforcing element, which is arranged in the interior of the injector body. As a result, a guide of the guide element is ensured, for example, along a longitudinal axis of the injection valve.

Furthermore, it is advantageous that a spring element is provided, which acts on the valve closing body against the sealing seat. The opening force on the valve closing body induced by the shock wave due to the high local pressure on the sealing seat in this case acts against a bias of the spring element. As a result, a vote of the injector can be made.

It is also advantageous that the valve closing body has at least one pressure equalization channel. As a result, a hydraulic damping of the valve closing body is avoided during an opening movement.

It is advantageous that the shock wave actuator has an electrically conductive, elastic membrane and at least one field coil and that the field coil is assigned to generate an induction current in the membrane of the membrane. An induction current can be generated in the membrane via the field coil. The interaction of the magnetic field of the field coil and the induced magnetic field generated by the induction current in the membrane results in a force on the membrane. This is what happens Bending of the membrane. The bending of the membrane creates a shock wave in the medium adjacent to the membrane. This shockwave then passes from the diaphragm through the shockwave reinforcement channel to the sealing seat. It is advantageous that the membrane is designed as an at least approximately circular membrane and that the field coil in the region of one of the

Shock wave amplification channel facing away from the membrane is arranged. Upon actuation of the shock wave actuator, a repulsive force is generated due to the magnetic field of the coil and the induced magnetic field in the diaphragm. This results in an induction current (eddy current) in the membrane, which is oriented opposite to the current through the field coil.

However, it is also advantageous that the membrane is designed as a tubular and / or conical membrane that an inner side of the membrane

Shock wave amplifying channel limited and that the field coil is disposed in the region of an outer side of the membrane. As a result, the surface of the diaphragm serving to generate the shock wave can be enlarged in relation to an available installation space.

The membrane is preferably designed as a metal membrane. In particular, the metal membrane may be at least substantially formed of copper. A membrane may also be formed of at least two components which serve to seal and to allow the excitation. For example, the membrane may be formed from at least one noble metal, in particular platinum, and copper. The membrane may also be formed from a ferromagnetic steel sheet. In order to improve the conductivity of the membrane, a ferromagnetic steel sheet coated with copper or the like towards the field coil can also be used as the membrane.

Brief Description of the Drawings Preferred embodiments of the invention are described in the following description with reference to the accompanying drawings, in which:

Elements are provided with matching reference numerals, explained in more detail. It shows:

Fig. 1 shows a first embodiment of an injection valve of the invention in a partial, schematic sectional view and

Fig. 2 shows a second embodiment of an injection valve of the invention in a partial, schematic sectional view. Embodiments of the invention

Fig. 1 shows a first embodiment of an injection valve 1 in a partial, schematic sectional view. The injection valve 1 can serve in particular as an injector 1 for fuel injection systems. Such an injector 1 can be used for air-compressing, self-igniting internal combustion engines or for mixture-compression, spark-ignited internal combustion engines. Specifically, the injection valve 1 for

Injecting diesel fuel or gasoline into a combustion chamber of a

Serve internal combustion engine. However, the injection valve 1 can also for a

Exhaust aftertreatment system are used, for example, for injection for DeNox systems. However, the injection valve 1 according to the invention is also suitable for other applications. The injection valve 1 has an injector body 2, an injector sleeve 3 connected to the injector body 2, and a shockwave actuator 4. The shock wave actuator 4 is in this case arranged in the injector body 2. In addition, the injector body 2 has an inner space 5. The interior 5 is bounded by an inner wall 6 of the injector body 2. On the injector body 2, a valve seat surface 7 is formed. In addition, a valve seat 8 associated valve closing body 8 is provided with the

Valve seat surface 7 cooperates to a sealing seat 9. Further, a

Shock wave reinforcing element 10 is provided, which is at least partially disposed in the interior 5 of the injector body 2. In this case, a plurality of guide elements 1 1, 12, 13 are provided which hold the shock wave reinforcement element 10. Here are the

Guide elements 1 1, 12, 13 connected to the injector body 2.

In this embodiment, the valve closing body 8 is at the

Shock wave reinforcing element 10 is formed. Here, a one- or multi-part design of the shock wave amplifying element 10 with the valve closing body 8 is possible. The guide elements 1 1, 12, 13 allow in this case an adjustment of the shock wave amplifying element 10 and thus also of the valve closing body 8 from the starting position shown in FIG. 1 in an opening direction 14 along an axis 15 of the injection valve 1. Here, the valve closing body 8 and so too

Shock wave reinforcing element 10 also on a guide bore 16 of the

Injector sleeve 3 out. The shock wave actuator 4 comprises an electrically conductive, elastic membrane 17 or a piston. In this case, the membrane 17 may be configured as a metal membrane 17. The

Metal membrane 17 may be formed of a metal or of several metals. For example, the metal membrane 17 of a steel foil with a

Copper coating be formed. The shock wave actuator also comprises a field coil 18. The field coil 18 is assigned to the diaphragm 17 and arranged on one side 19 of the diaphragm 19 of circular configuration in this embodiment. If the metal membrane 17 has a copper coating, this is preferably facing the field coil 18 and thus provided on the side 19. The membrane 17 also has a side 20 facing away from the side 19.

The side 20 of the diaphragm 17, the inner wall 6 of the interior 5 and an outer side 21 of the shock wave reinforcement member 10 define a shock wave reinforcement channel 22. The shock wave channel 22 extends from the diaphragm 17 of the shock wave actuator 4 to the sealing seat 9. The shock wave reinforcement channel 22 has one for conduction from

Shock waves serving unobstructed cross-sectional area 23, which is oriented perpendicular to the axis 15. In the area of the shockwave reinforcement element 10, the remaining cross-sectional area 23 is configured annularly or as a multiply interrupted ring, as is the case in the region of the guide elements 11, 12, 13.

Upon actuation of the membrane 17 by means of the field coil 18, the membrane 17 bulges in the interior 5, as illustrated by an interrupted line 24 shown. The injector body 2 has an inlet channel 25 and an outlet channel 26. Via the inlet channel 25, a medium, in particular fuel, is guided into the interior 5. About the drain channel 26, the medium can be led out of the interior 5. As a result, any resulting bubbles or the like can be guided out of the inner space 5. During operation of the injection valve 1, the shock wave amplification channel 22 is completely filled with the medium. Upon actuation of the diaphragm 17, a shock wave 27 is generated in the medium, which is configured approximately flat in this embodiment. The shock wave 27 propagates in a direction 28 in the medium and thus passes from the membrane 17 through the shock wave amplification channel 22 to the

Sealing seat 9.

The shock wave amplifying element 10 is designed conical. The

Shock amplification element 10 can also be designed exponentially shaped.

Here, a tip 29 of the Stoßwellenstärkungselements 10 is directed to the center of the membrane 17. The shock wave amplifying element 10 is with respect to the axis 15th formed symmetrically. In the region of the shockwave reinforcement element 10, a width 30 of the annular, remaining free cross-sectional area 23 decreases in the direction 28 as far as the sealing seat 9. Furthermore, the remaining cross-sectional area 23 also decreases between the membrane 17 and the tip 29. The cross-sectional area 23 is configured circular between the membrane 17 and the tip 29.

After the deflection of the diaphragm 17 to generate the shock wave 27 by means of the shock wave actuator 4, the shock wave 27 runs in the direction 28 to the

Shock wave reinforcement element 10. The conical shock wave reinforcement element 10 pierces the flat shock wave front of the shock wave 27 with its tip 29. Here, the shock wave reinforcement element 10 is designed such that only a minimal part of the shock wave 27 is reflected at the tip 29. Accordingly, the

Guide elements 1 1, 12, 13 designed so that reflections are avoided as possible. Since the remaining cross-sectional area 23, in particular the width 30 of

annular cross-sectional area 23, and thus reduces the area of the shock wave front 27 in the direction 28, the shock wave 27 amplifies in the narrowing

Shock amplification channel 22.

When the reinforced shock wave reaches the sealing seat 9, a force is exerted on the valve closing body 8 in the opening direction 14 due to the high local pressure. The magnitude of the force can be adjusted over the given area ratios and angles of the level of the valve closing body 8 and the area in the region of the sealing seat 9. In an interior 35 of the injector 3, a spring element 36 in the form of a

Disc spring packs and an adjustment means 37 arranged in the form of shims. The spring element 36 is biased, so that the valve closing body 8 against the

Opening direction 14 is pressed with a bias against the valve seat surface 7. When the opening force applied to the valve closing body 8 by the reinforced shock wave 27 exceeds the closing force of the spring member 36, the valve closing body 8 is displaced in the opening direction 14. This leads to the opening of the sealing seat 9 and thus to the escape of the medium from the inner space 5 via injection holes 38, 39. In this case, an atomization of the medium in the surrounding space, in particular a combustion chamber of an internal combustion engine can be achieved by the shock wave.

The valve closing body 8 has a pressure compensation channel 40, so that a hydraulic damping of the valve closing body 8 during the opening movement is avoided. After the reinforced shock wave has left the pressure-effective areas of the valve closing body 8 at the sealing seat 9, again dominates the closing force of the spring element 36, so that the valve closing body 8 is adjusted against the opening direction 14 and by placing the valve closure member 8 on the valve seat surface 7 of the sealing seat. 9 is closed again. The leaked during the injection process via the injection holes 38, 39 medium is replaced by the inlet channel 25. In this case, a continuous flow of the medium to be injected can be achieved via the inlet channel 25 and the outlet channel 26, any gas bubbles formed being conveyed out of the interior 5. Thus, the injection valve 1 is prepared for the next injection.

In this embodiment, a sealing ring 41 is provided on the guide bore 16, which seals the interior 35 of the injector 3. The sealing ring 41 is formed of a temperature-resistant material, for example, up to a maximum

Combustion chamber temperature is stable. For example, the pressure of the medium in the interior 4 may be in the range between 100 kPa (1 bar) and 500 kPa (5 bar).

Thus, the injection valve 1 can generate defined individual injection jets. Specifically, a sufficient pressure is reliably generated, for example, a

to produce reliable injection against a large combustion chamber pressure.

For the shock wave generation by the shock wave amplifying element 10 a very fast, explosive discharge of the stored amount of energy is needed. Here, in a time of a few microseconds, an amount of energy of about 20 J are delivered, which corresponds to a power of a few MW. at

ferromagnetic or piezoelectric actuators, the power densities are limited due to the saturation effects of the ferromagnetism and the ferroelectric. On the other hand, relatively large volume displacements are needed to promote and thus inject a sufficient amount of medium through the shock wave amplification channel 22.

The metal diaphragm 17 is therefore actuated inductively in this embodiment.

In this case, a short current pulse in the designed as a spiral air-core coil

Field coil 18 generated. This current pulse generates a magnetic field which induces an induction current in the form of an eddy current in the conductive metal membrane 17, which current is directed counter to the coil current through the field coil 18. Here, the force acting on the metal membrane 17 according to the law of induction force is greater, the shorter the distance of the field coil 18 to the metal membrane 17 is. Therefore, the field coil 18 is as close as possible and preferably directly on the side 19 of the metal membrane 17th arranged. At a current of 1000 A, for example, a force in the range of a few kN can act on the metal membrane 17. With such forces, relatively large deflections, in particular deflections of more than 1 mm, of the metal membrane 17 can be achieved, as illustrated, for example, by the interrupted line 24.

The field coil 18 can also be mounted on a cylindrical or conical surface of a cylinder or cone, in order to increase the amplitude of the shock wave 27 with suitable wave concentrators.

The efficiency for the purely magnetic coupling is about 75%. Part of the energy is converted into heat in the metal membrane 17 and released to the medium in the region of the side 20. By heating, there is thus an expansion of the medium on the side 20 of the membrane 17, which leads to a thermal wave, so to speak, which supports the formation process of the shockwave 27.

In addition, the shock wave actuator 4 can realize a pumping function. The metal diaphragm 17 or the piston is preferably formed of a ferromagnetic steel sheet which is coated with the field coil 18 to improve the conductivity with copper or the like. After the amount determined by the pulse of the current through the field coil 18 has been injected by operating the membrane 17, the

Membrane 17 by means of a guided through the field coil 18 direct current or a low-frequency current having a frequency of less than 1 kHz in the illustrated in FIG

Origin are drawn. As a result, a negative pressure is generated on the side 20 of the membrane 17, which leads to the suction of the medium from the inlet channel 25.

Additionally or alternatively, the reset function can also be realized by a return spring which acts on the membrane 17. Thus, fuels, especially gasoline or diesel, urea for a

Exhaust gas improvement or other media are sprayed in a reliable manner from the injection valve 1 via the injection holes 38, 39.

FIG. 2 shows an injection valve 1 in an excerptional, schematic sectional view according to a second exemplary embodiment. In this embodiment, the membrane 17 is configured as a tubular and conical membrane 17. An inner side 20 'of the membrane 17 in this case limits the shock wave amplification channel 22. Further, the Field coil 18 in the region of an outer side 19 'of the membrane 17 is arranged. To actuate the Stoßwellenaktorik a current is passed through the field coil 18, the one

Induced current (eddy current) generated in the membrane 17 and thus leads to a repulsive force on the membrane 17. As a result, the membrane 17 bulges circumferentially in

Direction to the axis 15. Thus, there is the generation of a shock wave 27, which propagates in the direction 28 through the shock wave amplification channel 22. in the

Shock wave amplification channel 22, the shock wave 27 is amplified. The reinforced shock wave runs up to the sealing seat 9, whereby it for spraying the medium over the

Spray hole bores 38, 39 is coming.

In this embodiment, the amplitude of the shock wave 27 with suitable

Wave concentrators are increased.

The inlet channel 25 may open into the interior 5 at one end 42 of the interior 5.

The invention is not limited to the described embodiments.

Claims

claims

1 . Injection valve (1), in particular injector for fuel injection systems or for

Exhaust aftertreatment systems, comprising a shock wave actuator (4), a valve closing body (8) which cooperates with a valve seat surface (7) to a sealing seat (9), and a shock wave amplification channel (22) for conducting shock waves generated by the shock wave actuator (4) ( 27) to the sealing seat (9) and for reinforcing these shock waves (27).

2. Injection valve according to claim 1,

characterized,

a non-remaining cross-sectional area (23) of the shockwave amplification channel (22) serving to guide the shockwaves (27) decreases at least in sections from the shockwave actuator (4) to the sealing seat (9).

3. Injection valve according to claim 1 or 2,

characterized,

in that an injector body (2) is provided which has at least one interior space (5) that a shockwave reinforcement element (10) is inserted into the interior space (5) such that the shockwave reinforcement passageway (22) is at least partially interposed between an interior wall (6) of the interior space (6). 5) and the shock wave amplifying element (10) is configured and that a tip (29) of the shock wave amplifying element (10) in the

Shock wave amplification channel (22) against a propagation direction (28) of the generated shock waves (27) is oriented.

4. Injection valve according to claim 3,

characterized,

in that the shockwave reinforcement channel (22) between the inner wall (6) of the inner space (5) and the shockwave reinforcement element (10) is at least partially ring-shaped and / or partially partially ring-shaped and / or in sections as several times

broken ring is configured

and or

the shockwave reinforcement element (10) is designed at least approximately as a conical shockwave reinforcement element (10) and or

that the inner wall (6) of the interior (5) at least partially from the

Shock wave actuator (4) to the sealing seat (9) tapers

and or

that the inner wall (6) of the inner space (5) is at least partially conical.

5. Injection valve according to claim 3 or 4,

characterized,

in that the valve closing body (8) is designed on the shock wave amplification element (10).

6. Injection valve according to claim 5,

characterized,

in that at least one guide element (11, 12, 13) is provided for the shockwave reinforcement element (10) which is arranged in the inner space (5) of the injector body (2), and / or

a spring element (36) is provided which acts on the valve closing body (8) against the sealing seat (9),

and or

the valve closing body (8) has at least one pressure equalization channel (40).

7. Injection valve according to one of claims 1 to 6,

characterized,

in that the shockwave actuator (4) has an electrically conductive, elastic membrane (17) or a piston and at least one field coil (18), and in that the field coil is assigned to the membrane (17) for generating an induction current in the membrane (17)

or for generating an induction current in the piston associated with the piston.

8. Injection valve according to claim 7,

characterized,

the diaphragm (17) or the piston is designed as an at least approximately circular diaphragm (17) or as an at least approximately circular piston, and in that the field coil (18) in the region of one of the

Shock wave amplification channel (22) facing away from side (19) of the membrane (17)

or the piston is arranged.

9. Injection valve according to claim 7,

characterized,

in that the membrane (17) is configured as a tubular and / or conical membrane (17), that an inner side (20 ') of the membrane (17) delimits the shock wave amplification channel (22) and that the field coil (18) is arranged in the region of an outer side (19 ') of the membrane (17) is arranged.

10. Injection valve according to one of claims 7 to 9,

characterized,

the membrane (17) is designed at least substantially as a metal membrane (17).