KR101487369B1 - Injection valve for direct injection - Google Patents

Abstract

An injection valve according to the present invention for directly separating fuel into a combustion chamber of a self-ignition internal combustion engine is provided with a valve needle. Such a valve needle can be seated on the needle seat and has a needle point on the valve seat that intercepts the injection opening to the combustion chamber at the position of the valve needle. The injection valve also has a variable lift control device for adjusting the axial lift of the valve needle, the needle point partially blocking the injection opening.

Description

{INJECTION VALVE FOR DIRECT INJECTION}

The present invention relates to an injection valve for directly injecting fuel into a combustion chamber of a self-ignition internal combustion engine having an axially movable valve needle. The valve needle is seated on the needle seat and has a needle point in the region of the valve seat that intercepts the injection opening to the combustion chamber at the position of the valve needle.

In a climate-controlled internal combustion engine, the structural configuration of the injection valve and the profile of the injection process over time affect the progress of combustion and thus the output and release behavior.

A multijet injection valve of the type mentioned at the outset is known from DE 28 37 606. The advantage of such an injection valve is that it has little or no blind hole volume. In addition, hydrocarbon emissions are significantly reduced compared to standard injection valves. In addition, with the above-described configuration, the phenomenon that the fuel is evaporated from the blind hole and the fuel is dripped off due to the needle recoil is greatly reduced.

In the step injection valve proposed in the above-mentioned publication, the injection holes of more or less valve needle are sequentially opened depending on the respective injection amount to be injected. When the number of open injection holes is small, a higher injection pressure is applied to the storage system disposed in the valve. Such a storage system automatically causes more and more injection holes to open depending on the spray duration. No additional control system for valve lift is provided.

DE 197 14 505 proposes a fuel injection nozzle in which a rotary valve is arranged in the hole. In such a fuel injection nozzle, the area of the injection opening changes corresponding to each position of the rotary valve. However, in order to rotate the rotary valve, a device for detecting and regulating the position of the rotary valve is needed. In this rotary valve, although it is described that the atomization and the fuel injection angle are controlled, the structure of the valve requires high structural cost and high position accuracy of the rotary valve.

Other known injection valves use, for example, two valve springs, which limit the needle lift to a prestroke for pre-injection. When the pressure regulated by the second compression spring is exceeded, the valve needle is further lifted to the maximum lift for main injection. Such a discharge valve is disadvantageous in that its flexibility is low because the needle lift is controlled solely by the pressure in the entire nozzle chamber. It is impossible to combine a partial lift with a high pressure in the entire chamber of the nozzle.

It is an object of the present invention to provide a jetting valve that avoids the disadvantages of the prior art and permits variable fuel injection.

According to the invention, such an object is achieved by the subject matter of claim 1. Preferred additional configurations are the subject of the dependent claims.

An injection valve according to the present invention for directly separating fuel into a combustion chamber of a self-ignition internal combustion engine has an axially movable valve needle which can be seated and seated on a needle seat. Here, the valve needle includes a needle point which substantially completely blocks the injection opening from the position of the valve needle to the combustion chamber in the region of the valve seat. The injection valve also has a variable lift control for adjusting the axial lift of the valve needle, the needle point partially blocking the injection opening during lift movement. Depending on the load required, the injection opening may be partially obstructed or completely opened by the valve needle at the maximum lift position. Here, the injection opening refers to a region connecting the internal space of the injection valve to the combustion chamber. Such a zone may consist of one or a plurality of connection openings, which are preferably arranged radially and / or axially distributed around the injection openings.

Variably adjusting the axial lift movement of the valve needle is preferably accomplished by a control device which is connected to a control device which is operative to process a plurality of operating parameters of the internal combustion engine and to control the engine desirable. It is preferable that the engine characteristic diagram is stored in the control device for controlling the engine and the injection quantity necessary for the predetermined load range of the engine is determined therefrom. Starting from the required injection quantity, the corresponding axial lift of the valve needle in the injection valve is ascertained.

The control device for the injection valve includes a regulating element, by the actuation of which regulating element, the valve needle is moved to the desired lift position, preferably maintained in its lift position, and the valve is again regressed through a predetermined axial movement of the valve needle It is preferable to close it. Such regulating elements are operated according to the electromechanical operating principle. That is, it is preferable that the control movement is performed by the electromagnet, the servo motor, or the piezoelectric actuator. However, the regulating element may be operated by hydraulic pressure or by other operating principles.

The lift movement and the maximum needle lift are preferably controlled in such a manner as to be interlocked with the switching position of the control element and the fuel pressure to be applied. In another embodiment, the maximum lift of the valve needle is limited by the lift limiting element, which is also preferably accomplished by a regulating element.

It is preferable that the opening of the first section of the injection opening is achieved only after the valve needle has passed the constant lift. When the engine is operated in a partial load range, injection is effected only through a relatively small opening cross section of the injection opening. That is, the lift of the valve needle is correspondingly reduced. Particularly in the case of conventional injection systems, the injection cross section is so small that high pressure is applied and good atomization of the injected fuel is achieved. In this way, the smoke emission is reduced in comparison to the cylinder injection valve during combustion, because the fuel flows out as a nearly compact liquid jet there. The proportion of fuel in the form of steam is relatively low. The configuration of the injection valve according to the present invention preferably doubles the cavitation in the cross-section of the opening, increases the internal force within the jet, and improves the external wave formation, which, in conjunction with the combustion chamber atmosphere, . ≪ / RTI > The nature of such fuel injection improves mixer generation, thereby increasing the output and causing harmless combustion.

In order to improve the jet dispersion, it is desirable to provide a breakaway edge, which is preferably formed at the valve needle point when the spray cross section is only partially open, which serves to favor mixer production. It is also desirable to influence the jet dispersion by the geometry of the injection opening and / or the geometry of the valve needle, as well as the position of the valve needle point relative to the injection opening. According to the present invention, in the geometrical shape of the jet opening, other than the concentric shape can also be provided. By combining the geometry of the needle point with the geometry of the injection opening, it is possible to influence the combustion process as desired, in conjunction with the position at which the injection valve is assembled into the cylinder, and in conjunction with the gas flow distributed in the cylinder.

In the high load range of the engine, a high output is obtained by providing a high volumetric flow with a low injection pressure. In such a range, the emission value, particularly the formation of nitrogen oxides, must also exert a good influence. The parameters of the injection profile, substantially the profile of the valve needle movement with time of lift movement, and its maximum lift are determined in conjunction with the engine characteristic diagram stored in the control device and adjusted in the valve. That is, the preliminary injection may be performed through a short needle opening, which is preferably obtained in conjunction with a small lift. At the rated output, it is preferable that the injection opening of the injection valve is completely opened. When carrying out the control of the needle lift by means of the lift limiting element, it is preferably arranged at its maximum axial position of the lift limiting element. Even in the range of the rated output, it is preferable to influence the jet formation by the geometry of the jet opening and / or the geometry of the valve needle point.

It is also desirable to provide a limitation of the maximum lift of the valve needle so that the injection opening is not fully opened, even in the range of the rated output, in order to obtain the best possible jet configuration, depending on the configuration of the valve needle geometry associated with the injection system .

According to the invention, the geometry of the cross-section of the injection opening is configured to have a favorable effect on the injection profile. It can be constructed such that, for example, only a small opening cross section is opened at the beginning of the injection profile, whereas the cross section which opens at the end of injection increases proportionally. However, it may also be desirable to linearly expand the open cross-section. The change in volume flow over the duration of the injection can be influenced by the control over time of the lift motion of the valve needle, as well as on the geometric shape of the injection opening.

The injection valve proposed in the present invention enables variable control of fuel injection by its simple structure and advantageous nozzle configuration, which can be obtained by suitably adjusting a number of parameters.

The injection valve for the straight yarn according to the present invention avoids the disadvantage of the prior art that the flexibility of the needle lift is low due to the fact that it is controlled solely by the pressure in the entire chamber, thereby enabling variable fuel injection. In particular, its simple structure and advantageous nozzle configuration allows for a large number of parameters to be adjusted accordingly, thereby enabling variable control of fuel injection.

Other advantages, features, and possibilities of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.

Brief Description of the Drawings Fig. 1 shows an injection valve provided with a control device according to an embodiment of the present invention, which is provided in a combustion chamber of a large diesel engine for direct injection of fuel. Such injection valve 10 has an axially movable valve needle 11 that can be seated on the needle seat 12 and seated. The valve needle 11 includes a needle point 13 at which the valve needle 11 completely blocks the injection opening 14 at the position shown in the region of the needle seat 12. [ In such a position, it is not possible for fuel to flow from the injection pressure and volume flow source 40 to the injection space 17 of the injection valve 10 via the fuel line 21.

The injection pressure and volume flow source 40 is connected to the fuel line 21 only temporarily by an appropriate switching mechanism.

When the valve needle 11 is lifted from the needle seat 12, the connection with the fuel line 21 to the injection space 17 of the injection valve 10 is opened. Then, the fuel supplied via the fuel line 21 flows into the axial feed hole 16 of the valve needle 11 through the transverse hole 15. In such a valve position, the needle point 13 of the valve needle 11 only partially obstructs the injection opening 14, so that the fuel reaches the combustion chamber of the internal combustion engine via the injection opening 14.

In the illustrated embodiment of the invention, the valve needle 11 and the variable lift stopper 25 located above the tappet are controlled by the control device 30, which controls the engine And is connected to a control device 31 serving as a controller. An engine characteristic diagram 32 that can be read and processed by the computing device 34 of the control device 33 is stored in the control device 31. [ The control device 33 further includes a storage device 35 in which relevant data for control of the injection valve 10 is stored. The fuel supply to the injection valve 10 through the high pressure space 6 is controlled by the fuel supply device 40 which is also connected to the control device 33.

The control device 30 includes a regulating element 36 which is connected to the low pressure line 38 and which is operatively associated with the fuel pressure in the fuel line 21 during the desired lift movement, 11). Such an adjustment element 36 is operated by an electromagnet 37 controlled by a control device 33 in the illustrated embodiment.

The fuel pressure is applied to the high-pressure space (6). The spring space (5) is connected to the low pressure line (38). A spring (7) disposed in the spring space (5) pushes a force directed toward the closing direction of the injection valve (10) to the valve needle. In Figure 1, the adjustment element is shown in the rest position. In the switching position, the spring space (5) of the injection valve (10) is connected to the low pressure line (38). Thus, the pressure in the spring space 5 drops, and the valve needle is lifted from the valve seat and moved in the opening direction based on the pressure in the high-pressure space 6. [ By closing the connection to the fuel pressure by the fuel supply device 40, the pressure in the injection space 17 and the high-pressure space 6 falls, and the valve is closed by the spring force.

2 shows another exemplary embodiment of the injection valve 10 with a lift limiting device that can be variably controlled. In this embodiment, although opening and closing of the valve needle 11 in the injection valve 10 is performed similar to that of Fig. 1, the maximum lift is controlled in the form of an axially displaceable piston controlled by the regulating element 36 Lt; RTI ID = 0.0 > 25 < / RTI > The regulating element 36 is connected to the fuel line 21 and the fuel line 21 is again connected to the injection pressure and volume flow source 40.

The lift limiting element 25 can be variably adjusted between the lower lift limiting position and the upper lift limiting position shown by the adjusting element 36 switched by the control device 33. [ In the illustrated switched position of the regulating element 36, a lift limiting pressure space 8 is connected to the low pressure line 38. When the fuel pressure is applied, the medium leaks into the lift limiting pressure space 8 as long as the regulating element is open. In that case, the lift limiting element 25 is moved upwardly by the valve needle 11, which is moved towards the opening direction in the axial direction, so that the force is balanced at the lift limiting element 25 or mechanically brought into contact with the upper limiting position Until it is moved upward. In the illustrated switching position of the regulating element 25, the valve needle 11 and the lift limiting element 25 move axially to the stopper reaching the maximum valve lift.

Alternatively, the regulating element 36 may connect the lift limiting pressure space 8 to an auxiliary medium circuit having an appropriate pressure instead of the fuel line 21. [ In such an embodiment, it is desirable for a single regulating element 36 to be able to adjust the position of the plurality of lift limiting elements 25, and thereby the lift of multiple or all of the injection valves 10 of the engine side by side Do.

Figure 3 shows an injection valve 10 with a variably adjustable lift limiting arrangement in accordance with another configuration of the present invention. In this embodiment, although the opening and closing of the valve needle 11 in the injection valve 10 is similar to that of Figs. 1 and 2, it is also possible to adopt a configuration in which the maximum lift is in the form of two controllable pistons Is limited by the lift limiting element 25 and the corresponding control element 26. [ In this configuration, the volume flow into the pressure space of the injection valve 10 is variably controlled by the control device 30 and the injection pressure and volume flow source 40, similar to the configuration of Fig. 1, Pressure and volume flow sources 40 are not shown.

When the spring space 5 is connected to the pressure line 39 by the adjusting element 36 switched by the control device 33 the lift limiting element 25 is moved to the lower limit rest position shown. In the illustrated switched position of the regulating element 36, the spring space 5 is connected to the low pressure line 38. Thereby, the pressure in the spring space 5 drops and the control element 26 and the lift limiting element 25 are moved upward by the valve needle 11 moved in the axial direction toward the opening direction, Or until the lift limiting element 25 abuts the stopper in the housing. At the illustrated switching position of the regulating element 25, the maximum valve lift has been reached.

In this embodiment too, it is also possible for a single regulating element 36 to be able to adjust the position of the plurality of lift restricting elements 25, and thus the lift of many or all of the injection valves 10 of the engine It is possible.

4 is an enlarged view schematically illustrating an exemplary injection valve 10 in various lift positions. In the closed position, the valve needle 11 is seated on the valve seat 12 and seats. In such a position, the valve needle point 13 completely blocks the injection opening 14. The connection between the fuel line 21 and the injection space 17 is disconnected from the valve seat 12. [ Virtually no force acts on the injection space 17.

After the lift movement of the valve needle 11 by the lift L ₁ (shown only for the needle point), the valve needle 11 no longer seats on the needle seat 12, The connection to the space 17 is opened. The fuel reaches the injection space 17 via the feed hole 16 via the transverse hole 15. In such a position, in particular in the case of a conventional injection system, an increased pressure is produced due to the narrowing of the cross section due to the jet opening 14 only partially open. Thus, the fuel outflow rate at such a spray cross section becomes relatively high.

After the lift movement of the valve needle 11 by the lift L ₂ (shown for the needle points and the needle seat), the valve needle 11 reaches its maximum lift. Since the injection opening 14 is almost completely open and the volume flow fed to the combustion chamber is very high, a very high injection pressure is created in the injection space 17, especially at the corresponding stage in the injection profile in the case of the conventional injection system I can not. Thus, by varying the injection cross-section, it is possible to influence the volume flow, the pressure, and the structure of the outgoing fuel jet and thus the mixer production.

5 shows an exemplary cross-sectional view of the injection opening 14 of the injection valve 10. As shown in Fig. In this embodiment, the lift of the valve needle 11 required for full opening of the injection opening 14 is relatively long. In Fig. 5, approximately half of the injection opening 14 of the injection valve 10 is opened. The injection opening 14 has an upwardly enlarged cross-section, which realizes a very high fuel injection pressure with a small volume flow from the beginning at a linear opening speed. From about half of the injection profile, the volumetric flow is greatly increased at night.

6 shows another exemplary cross-sectional view of the injection opening 14 of the injection valve 10. In Fig. In this embodiment, the injection opening 14 is constructed so that the needle point 13 opens an already large cross-section already at a small lift to enable a rapid increase in volume flow.

7 shows an exemplary configuration of the needle point 13 of the valve needle 11, which needle point 11 has an annular nose 18. Such a nose generates a so-called breakaway edge. Such break away edges serve to improve the mixer generation and combustion by creating a structure of good jet 3.

Fig. 8 shows an exemplary configuration of the injection opening 14 of the injection valve 10. Fig. Also in this embodiment, when the valve needle 11 is only partially opened, a good breakaway edge is formed similarly to the configuration of Fig. In contrast to the configuration of the jetting opening 14 shown in Fig. 7, the jetting opening 14 here is disposed obliquely to the sleeve 19 of the jetting valve 10, and accordingly the forwarding of the jet takes place.

9 shows another configuration of the injection opening 14 of the injection valve 10. As shown in Fig. The injection openings 14 are configured conically in the sleeve 19 such that the outer diameter is smaller than the inner diameter toward the needle point 13.

Fig. 10 shows another detail of the injection opening 14 in which the edge of the sleeve 19 can be rounded in a suitable manner.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a jetting valve provided with a control device according to an embodiment of the present invention;

FIG. 2 is a view showing an injection valve having a variable-lift restriction device according to another embodiment of the present invention; FIG.

FIG. 3 is a view illustrating an injection valve provided with a variable lift restriction device according to another embodiment of the present invention;

Figure 4 is an enlarged view of the injection valve of Figure 1 in various lift positions,

5 is a cross-sectional view of an injection opening of an injection valve according to an embodiment of the present invention,

6 is another cross-sectional view of the injection opening of the injection valve according to one embodiment of the present invention,

7 is a view showing the configuration of a valve point of a valve needle according to an embodiment of the present invention,

8 is a view showing a configuration of an injection opening of an injection valve according to an embodiment of the present invention,

FIG. 9 is a view showing the configuration of an injection opening of an injection valve according to another embodiment of the present invention; FIG.

10 is a view showing a configuration of an injection opening of an injection valve according to still another embodiment of the present invention.

Description of the Related Art

5, 6, 8: volume space 10: injection valve

11: valve needle 12: needle seat

13: Needle point 14: injection opening

25: Lift limiting element 31: Control device

32: Engine Characteristic Diagram 36: Adjustment Element

37: Electromagnetism

Claims (21)

The valve needle 11 is axially movable and can be seated on the needle seat 12 so that the valve needle 11 is in a position in the needle seat 12, For injecting fuel directly into a combustion chamber of a self-ignition internal combustion engine, said needle valve (13) having a needle point (13) intercepting an injection opening (14) A variable lift control device for adjusting the axial lift of the valve needle 11 such that the needle point 13 partially blocks the injection opening 14 and the variable lift control device comprises a lift limiting element 25 And the lift limiting element 25 is moved upwardly by a valve needle 11 which is moved toward the opening direction in the axial direction so that the force is balanced at the lift limiting element 25, And is moved upwards until it abuts. The injection valve according to claim 1, characterized in that the injection opening (14) is only opened after the valve needle (11) has passed a predetermined axial lift. The injection valve according to claim 1 or 2, characterized in that the data of the engine characteristic diagram (32) is used to determine the axial lift of the valve needle (11). The injection valve according to claim 1 or 2, characterized in that the actuation of the regulating element (36) causes the valve needle (11) to make a predetermined axial movement. 5. A jetting valve as claimed in claim 4, characterized in that the regulating element (36) is operated according to a mechanical working principle, a pneumatic working principle, an electromechanical working principle, or a hydraulic working principle. 6. The injection valve according to claim 5, characterized in that the regulating movement of the regulating element (36) is effected by an electromagnet (37), a servo motor, or a piezoelectric actuator. 3. A method according to claim 1 or 2, characterized in that the axial movement of the valve needle (11) is an equilibrium movement resulting from the propelling of the fuel pressure or the pressure of the auxiliary medium in the volume spaces (5, 6, 8) Injection valve. The injection valve according to claim 4, characterized in that the maximum needle lift is controlled in such a manner as to be interlocked with the switching position of the regulating element (36) and the fuel pressure applied. 3. A valve according to claim 1 or 2, characterized in that the maximum lift of the valve needle (11) is limited by a lift limiting element (25) ) Or the movement of the valve needle. ≪ Desc / Clms Page number 13 > The injection valve according to claim 9, characterized in that the element (25) for limiting the maximum lift of the valve needle (11) is arranged at its maximum axial position at rated output. The injection valve according to any of the preceding claims, wherein the cross-section of the injection opening (14) is configured to provide a predetermined injection profile. A jetting valve as claimed in claim 1 or 2, characterized in that the needle point (13) is configured to form a brake away edge at the valve needle point (13). The injection valve according to claim 1 or 2, characterized in that a jet of fuel is injected by the geometry of the valve needle point (13). 3. A jetting valve as claimed in claim 1 or 2, characterized in that a jet of fuel is injected by the geometry of the jetting opening (14). 3. A jetting valve as claimed in claim 1 or 2, characterized in that a jet of fuel is injected by the position of the valve needle point (13) with respect to the jetting opening (14). The injection valve according to claim 14, wherein the injection openings (14) are arranged at an angle with respect to the radial direction of the injection valve (10). 17. The injection valve according to claim 16, wherein the injection opening (14) is configured such that the outer diameter is formed to be smaller than the inner diameter toward the valve needle point (13). The injection valve according to claim 16, characterized in that the injection opening (14) is rounded at its inside towards the valve needle point (13) side. 3. A dispensing valve as claimed in claim 1 or 2, characterized in that a limitation of the maximum lift of the valve needle (11) is provided. 3. A jetting valve as claimed in claim 1 or 2, characterized in that the parameters of the injection profile are determined in conjunction with the engine characteristic diagram (32) stored in the control device (31). 3. The injection valve according to claim 1 or 2, characterized in that a change in the volumetric flow of the fuel over the injection duration is controlled by the lift motion of the valve needle (11).

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