KR20120040731A

KR20120040731A - Device for high-pressure fuel injection

Info

Publication number: KR20120040731A
Application number: KR1020127005659A
Authority: KR
Inventors: 세바스챤 얀센
Original assignee: 로베르트 보쉬 게엠베하
Priority date: 2009-08-05
Filing date: 2010-06-17
Publication date: 2012-04-27
Also published as: EP2462335A1; DE102009028234A1; WO2011015405A1; KR101762106B1; EP2462335B1

Abstract

The present invention relates to a high pressure fuel injection valve device, comprising a valve housing (2), a valve needle (3) opening to the outside, a closing spring (5), an electromagnetic actuator (6) and a control valve (8). The valve needle is disposed in the pressure chamber 4, which is supplied with fuel K under pressure and filled with fuel in the valve housing 2, in which case the valve needle 3 is sealed in the valve seat 16, The closing spring returns the valve needle 3 to the starting position, the actuator comprises an armature 7 movably arranged for the operation of the valve needle 3, the control valve being a valve member 10. And a valve seat 11, in which case the valve member 10 has a first working surface 13 and a second working surface 14, the first working surface 13 having a pressure chamber 4. , The second working surface 14 faces the pressure chamber 12 connected to the low pressure region 19, and the valve member 10 faces the pressure chamber 4. Opening and closing a connection between the pressure chamber 12 and valve seat 11 is armature 7 Or on a part connected to the armature 7, to reduce the opening force for the valve needle 3 by opening the connection between the pressure chamber 4 and the pressure chamber 12 during operation of the electromagnetic actuator 6. The control valve 8 is opened in front of the valve needle 3 opening to the outside.

Description

Device for high pressure fuel injection

The present invention relates in particular to a high pressure fuel injection device which can be used in a direct injection internal combustion engine during stratified air supply operation.

In a direct injection internal combustion engine, a high pressure injection valve with a valve needle opening to the outside as a high pressure fuel injection device is used, which is particularly spray-induced layered due to the desirable spraying properties by the ring gap between the valve needle and the valve body. It is especially suitable for the combustion method by air supply operation. However, in the case of an injection valve with an open valve needle, the hydraulic pressure created by the fuel pressure due to the larger seat diameter of the valve needle is much higher than an injection valve with an internal opening needle. Injection valves with piezoelectric actuators are generally used because of high power and short switching times, but this adds cost.

In the concept described in EP 1783 358A1 a injection valve with a valve needle opening outward is known, which valve is operated by a magnetic actuator and comprises a guide member on the valve needle, the guide member being guided to the valve housing and In this case, the diameter of the valve seat of the guide member and the valve needle is selected such that the valve needle is substantially pressure compensated.

The high pressure injection valves of the prior art provide a high sealing force between the valve seat and the valve needle in the closed state and can be operated with a weaker actuation force or less power by a magnetic actuator, which is comparable to the injection valve with a piezoelectric actuator. It is not well suited to provide a high pressure injection device that has sufficient switching dynamics and can be manufactured simply and inexpensively for a direct injection internal combustion engine in layered air supply operation.

It is an object of the present invention to provide a high pressure fuel injection device for a direct injection internal combustion engine in layered air supply operation which can be produced simply and inexpensively.

The problem is solved by a high pressure fuel injection device comprising the features of claim 1.

The valve device according to the invention having the features of claim 1 has the advantage of having a simple and inexpensive configuration with a magnetic actuator that opens the valve needle to the outside by a significantly reduced actuation force due to the pressure compensation acting on the valve needle. Has Thus, in the valve arrangement according to the invention, a magnetic actuator having a low power demand, in particular even at a spray pressure of 20 MPa or more, can be used, which magnetic actuator is provided with a valve needle in the valve seat of the valve in a closed state with sufficient switching dynamics. Enables a secure seal This is achieved according to the invention by opening in front of a valve needle which opens outwardly a control valve disposed between the high and low pressure regions of the valve arrangement during operation of the electromagnetic actuator. Opening the connection between the pressure chamber in the high pressure region and the pressure chamber in the low pressure region opens pressure compensation, i.e., pressure rise, in the low pressure region, and this pressure compensation is applied to the operating surface of the valve member of the control valve in the opening direction of the valve needle. Pressure to act, thereby significantly reducing the opening force of the electromagnetic actuator for the valve needle. Thus, simple and fast switching is possible. The control valve is opened by a freely movable armature or by a part connected to the armature.

Dependent claims represent preferred embodiments of the invention.

According to a preferred embodiment of the present invention, the high pressure fuel injection device according to the present invention comprises a follower fixed to the valve needle and having an armature contact area, the follower being arranged at a predetermined interval from the armature at the starting position, The armature is movably disposed above the valve needle. The closing spring closing the valve needle returns the armature. This ensures that during operation of the electromagnetic actuator the armature of the actuator first moves from the starting position to the armature contact area of the follower, whereby the control valve is opened for pressure compensation without operating the valve needle. When the armature contacts the follower, the valve needle is actuated and opened directly by the armature.

Preferably the cylindrical part is fixed to the armature, in which case the valve seat of the control valve is arranged on the free end side of the cylindrical part. This achieves a simple configuration of a control valve with a minimum number of parts.

Also preferably a gap seal is formed between the cylindrical part and the valve housing. This results in a simple and inexpensive seal with low leakage between the two parts.

Particularly preferably the diameter of the gap seal is made larger than the diameter of the valve seat of the valve needle. This creates a hydraulic force in the opening direction of the valve needle when the control valve is opened and pressure compensation is made, which reduces the opening force of the valve needle to be overcome by the armature. In contrast, when the control valve is closed, hydraulic pressure is generated in the closing direction of the valve needle by low pressure in the pressure chamber, and the hydraulic force reliably seals the valve.

According to another preferred embodiment of the invention the distance from the starting position of the armature to the driven part fixed to the valve needle is smaller than the full stroke of the armature. That is, a residual stroke for opening the valve needle. The first partial stroke of the armature from the starting position to the follower results in rapid pressure compensation for the quick opening of the control valve for pressure compensation and for the easy opening of the valve needle subsequently opened by the second partial stroke. Upon closing of the valve needle, a first partial stroke is first implemented from the follower of the armature to the closed position of the control valve, and the control valve is closed. In this case the valve member of the control valve acts as another follower operated by another armature for the return of the valve needle. Therefore, the closing of the valve needle by the hydraulic force assisting in the closing direction of the valve needle can be made quickly by the pressure difference between the high pressure region and the low pressure region of the device which reappears in the control valve. This enables the use of actuators with low power consumption and the switching dynamics required for fuel injection during laminar air supply of the internal combustion engine.

According to another preferred embodiment of the present invention, the high pressure fuel injection device has a throttle between the pressure chamber and the low pressure region. This achieves a pressure reduction due to a ring gap between the valve needle and the valve housing, a high pressing force and a good sealing action between the valve needle and the valve seat in the pressure chamber when the control valve is closed.

As an alternative to the throttle a leak shutoff valve may be used between the pressure chamber and the low pressure region. Therefore, the amount of leakage or return of fuel to the fuel return portion when the valve needle is opened is significantly reduced. Thereby the device according to the invention can be used very economically.

Preferably the leak shutoff valve comprises an extension and seat in the form of a collar formed on the valve needle as a closing member, the seat being formed in the valve housing. This allows a simple configuration of a leak shutoff valve having a minimum number of members. This can also provide a very operational and stable device.

Embodiments of the present invention are described in detail below with reference to the accompanying drawings.

1 shows a schematic cross-sectional view of an apparatus according to the invention when the valve needle is open.
FIG. 2 is an enlarged sectional view schematically showing a part of the apparatus of FIG. 1; FIG.
3 is an enlarged sectional view schematically showing the apparatus of FIG. 1 upon opening of the valve needle;
4 is a schematic cross-sectional view of the apparatus of FIG. 1 when the valve needle is open;
5 is an enlarged sectional view schematically showing a part of the device of FIG. 4;
FIG. 6 is a schematic cross-sectional view of the apparatus of FIG. 1 in closing the valve needle; FIG.
7 is a schematic cross-sectional view of a second embodiment of the device when the valve needle is closed;
8 is a schematic cross-sectional view of the apparatus of FIG. 7 when the valve needle is open;
9 is an enlarged sectional view schematically showing a part of the apparatus of FIG. 7 when the valve needle is closed;
10 is an enlarged sectional view schematically showing a part of the apparatus of FIG. 7 when the valve needle is open;

Hereinafter, the high pressure fuel injection device 1 according to the first preferred embodiment of the present invention will be described in detail with reference to FIGS. 1 to 6.

1 shows a schematic cross-sectional view of a device according to the invention in a closed state. As can be seen in the schematic cross-sectional view of FIG. 1, the device 1 comprises a valve housing 2, a valve needle 3 which opens outwards, the valve needle being in fuel, within the valve housing 2. It is placed in the filled pressure chamber 4. The pressure chamber 4 is supplied with fuel under pressure via the fuel supply 24, and the valve needle 3 is sealed in the valve seat 16 in the valve housing 2. The device 1 also comprises a closing spring 5 and an electromagnetic actuator 6, which spring returns the valve needle 3 to the starting position, the electromagnetic actuator being a magnetic coil 63, an inner pole 62. And a magnet housing 61 and a movable armature 7, which armature actuates the valve needle 3 by means of a follower 9 formed or fixed therein. The control valve 8 with the valve member 10 and the valve seat 11 is arranged in the end region 29 of the valve needle 3, opposite the injection side.

The valve member 10 has a first working surface 13 facing the pressure chamber 4 and a second working surface 14 facing the pressure chamber 12 connected to the low pressure region 19. The valve member 10 of the control valve 8 is designed to open and close the connection between the pressure chamber 4 and the pressure chamber 12, and the valve seat 11 of the control valve 8 has an armature 7. It is arranged at the end side of the cylindrical member 17 fixed to it. A gap seal 18 having a small guide play is formed between the outer circumference of the cylindrical member 17 and the valve housing 2.

In addition, as shown in FIG. 1, the outlets 30 and 31 for supplying the fuel K are formed in the armature 7 and the cylindrical member 17. Thus, when the valve needle 3 and the control valve 8 are closed, the high pressure of the fuel supplied through the fuel supply 24 is applied to all internal chambers of the device connected to the pressure chamber 4. There is a low pressure in the pressure chamber 12 because the pressure chamber is connected to the fuel return 25 by the throttle 21 and the control valve 8 is closed.

Since the diameter ds of the valve seat 16 in the device 1 according to the invention is smaller than the diameter d1 of the valve member 10, the valve needle 3 is in addition to the force of the closing spring 5. The hydraulic force component is also pressed into the valve seat 16, and the hydraulic force component is caused by the diameter difference. This ensures reliable sealing of the device 1 even when the valve needle 3 is closed.

FIG. 2 shows a schematic enlarged cross-sectional view detailing a part of the device of FIG. 1. As can be seen in FIG. 2, the armature 7 of the actuator is in its starting position in the closed state of the device 1 with the control valve 8 closed and the electromagnetic actuator 6 inactive. The closing spring 5 is fixed to the armature 7 and supported by the housing 2. The armature 7 freely moving in the axial direction at the starting position is spaced with respect to the follower 9 and the inner pole 62 with respect to the follower 9 on the valve needle 3 due to the spring force of the closing spring 5. Has (H)

3 shows a schematic cross-sectional view of the device 1 of FIG. 1 in opening the valve needle 3. In this case, a current is supplied to the magnetic coil 63 of the electromagnetic actuator 6 (this is indicated by the flash line), and the armature 7 implements the first partial stroke in the direction of the inner pole 62, which is driven by the armature. Corresponds to the distance A until contact with the follower 9. This opens the control valve 8 so that fuel K flows from the fuel supply 24 into the pressure chamber 4 and beyond the outlet 31 to the pressure chamber 12 (in arrow B of FIG. 3). Shown). This causes the pressure in the pressure chamber 12 to immediately rise, and the force resulting from the ratio of the first and second working surfaces 13, 14 in which the hydraulic pressure in the valve member 10 is applied and the high pressure is provided is the valve needle. It acts on (3). This resulting force acts in the opening direction of the valve needle 3 in addition to the magnetic force of the armature 7 when the control valve 8 is open, and the pressing force of the valve needle 3 against the valve seat 16. Decreases. The valve needle 3 can be moved or moved together in the opening direction by the follower 9 with a small force of the armature 7, so that the valve needle 3 can be opened and the spraying process can be started.

4 shows a schematic cross-sectional view of the device of FIG. 1 when the valve needle is open. The current is continuously supplied to the magnetic coil 63 so that the armature 7 is pulled in the opening direction of the device 1 together with the valve needle 3 and the second partial stroke is realized until it contacts the inner pole 62. This causes the valve needle 3 to be lifted out of the valve seat 16 and open. In this case, the second partial stroke opening the valve needle 3 is designed to be larger than the first partial stroke opening the control valve 8. The fuel jet injected between the valve needle 3 and the valve housing 2 is shown by the small arrow C in FIG. 4.

FIG. 5 shows a schematic enlarged cross sectional view showing a portion of the device of FIG. 4 in more detail. FIG. As can be seen in FIG. 5, when the control valve 8 is open, a portion of the fuel in the pressure chamber 12 leaks through the throttle 21 (shown by arrow D) into the fuel return 25. As reflux. Since this amount of leakage by the throttle 21 is fixed or limited to a predetermined value, the pressure reduction in the pressure chamber 12 after closing of the electromagnetic actuator 6 (closure of the valve needle 3) does not take so long, By prolonging the downtime of the switching cycle, the switching dynamics deteriorate.

6 shows a schematic cross-sectional view of the device of FIG. 1 upon closing of the valve needle 3. In this case, the state of the device 1 set after the magnetic coil 63 of the electromagnetic actuator 6 is cut off is shown, in which case the control valve 8 is first closed. The pressure in the pressure chamber 12 then decreases again due to the connection with the fuel return 25 via the throttle 21, so that only the low pressure is provided to the second working surface 14 from the fuel return 25. Only the high pressure of the cylindrical part 17 is provided on the first working surface 13. This creates a hydraulic closing force, which is in addition to the spring force until the closed state of the valve needle 3 of the closing spring 5 is restored to its original state (see FIG. 1) and the valve is finished. The needle 3 is pressed into the valve seat 16. The closing spring 5 acts on the valve needle 3 by means of an armature 7, a cylindrical part 17 and a valve member 10.

The opening and closing of the valve needle 3 of the device 1 according to the invention for high pressure fuel injection is carried out by means of the first and second working surfaces 13, 14 arranged in the valve member 10 of the control valve 8. By being hydraulically supported together with the high pressure in the device 10, the device 1 can simultaneously provide high switching dynamics with a relatively small magnetic force even when the sealing force is high.

Subsequently, the high-pressure fuel injection device 1 according to the second preferred embodiment of the present invention will be described in detail with reference to FIGS. 7 to 10. Parts having the same or identical functions have the same reference numerals as in the first embodiment.

7 is a schematic cross-sectional view of a second embodiment of the device 1 according to the invention for high pressure fuel injection with the valve needle 3 closed. The difference between the second embodiment and the first embodiment of the apparatus 1 according to the present invention is that a leak shutoff valve 26 is arranged between the pressure chamber 12 and the low pressure region 19 of the fuel return section 25. It is. In the first embodiment, the amount of leakage to the fuel return portion 25 as occurring in the throttle 21 is drastically reduced by the leakage shutoff valve 26. The leak shutoff valve 26 has a collar-shaped extension 22 of the diameter of the end region 29 of the valve needle 3. The leak shutoff valve 26, together with the stopper 23 on the valve housing 2 arranged at the outlet of the pressure chamber 12, isolates the pressure chamber 12 from the fuel return 25 in a closed state.

As can also be seen in FIG. 7, since the control valve 8 is closed and the leak shutoff valve 26 is opened in the state where the valve needle 3 is closed, there is a low pressure in the pressure chamber 12.

FIG. 9 is an enlarged sectional view schematically showing a part of the device of FIG. 7, showing the pressure state with the valve needle 3 closed. FIG. As can be seen in FIG. 9, the ring groove 27 in the valve housing 2 allows fuel to be introduced into the pressure chamber 12 without interruption when the control valve 8 is opened (see FIG. 10). In the region between the cylindrical component 17 and the valve member 10 of the control valve 8. When the valve needle 3 is closed, the control valve 8 is closed and the leak shutoff valve 26 is opened. In this case low pressure is present behind the closed valve member 10 of the control valve 8, ie in the ring groove 27, in the pressure chamber 12 and in the adjacent fuel return portion 25 (with reference numeral 19). High pressure is applied to the remaining inner region of the device 1 until the valve member 10 is closed (shown with reference 28).

As can be seen in FIG. 8, which shows a schematic cross-sectional view of the second embodiment of FIG. 7 when the valve needle 3 is open, in this state the leak shutoff valve 26 is closed and the control valve 8 is closed. Open. In this case, since there is a high pressure in the pressure chamber 12, the valve needle 3 can be opened with a small force. Since the leak shutoff valve 26 is closed, no leak amount is discharged into the fuel return portion 25. The collar extension 22 of the leak shutoff valve 26 in contact with the stopper 23 defines the stroke stopper of the valve needle 3 which is simultaneously open.

FIG. 10 is an enlarged sectional view schematically showing a part of the apparatus of FIG. 8 showing the pressure state when the valve needle 3 is opened. As can be seen in FIG. 10, in this case the control valve 8 is opened and the leak shutoff valve 26 is closed. The high pressure region 28 is formed in the control valve 8 and the leak shutoff valve 26, while the low pressure region 19 is formed only in the fuel return 25.

Since a small force is required to open and close the valve needle 3 in the device 1 according to the invention for high pressure fuel injection, the operation of the valve needle 3 is driven by an inexpensive electromagnetic actuator even at high injection pressures of 20 MPa. It can be made with sufficiently high switching dynamics. Due to the correspondingly small output requirement of the electromagnetic actuator, control of the device 1 can be achieved by conventional, ie available output stages for the self-high pressure injection valve. This provides further cost savings and improved economy of the high pressure fuel injection device 1 according to the invention.

2 valve housing
3 valve needle
4 pressure chamber
6 actuator
7 amateur
8 control valve
10 valve member

Claims

As a high pressure fuel injector,
A valve housing (2),
In the valve housing 2, a valve needle 3 which is supplied to the fuel chamber under pressure and is arranged in a fuel-filled pressure chamber 4 and opens outwardly sealed in the valve seat 16,
A closing spring 5 for returning the valve needle 3 to its starting position,
An electromagnetic actuator 6 having an armature 7 movably arranged for operation of the valve needle 3, and
A control valve (8) having a valve member (10) and a valve seat (11), said valve member (10) having a first working surface (13) and a second working surface (14); The first working surface 13 faces the pressure chamber 4, the second working surface 14 faces the pressure chamber 12 connected to the low pressure region 19, and the valve member 10 faces the pressure chamber. Opening and closing the connection between the pressure chamber 12 and the valve seat 11, the valve seat 11 is arranged on the armature 7 or on a part connected to the armature 7, and the electromagnetic actuator 6 In operation, the control valve 8 opens to the outside in order to reduce the opening force for the valve needle 3 by opening the connection between the pressure chamber 4 and the pressure chamber 12. High pressure fuel injector opening in front of the valve needle (3).

2. A follower (9) according to claim 1 is provided with a follower (9) fixed to said valve needle (3), said follower comprising an armature contact area (20) and spaced apart from said armature (7) in its starting position And the armature (7) is movably disposed on the valve needle (3).

The cylindrical part 17 is fixed to the armature 7, and the valve seat 11 of the control valve 8 is provided on the free end side of the cylindrical part 17. High pressure fuel injection device, characterized in that arranged.

4. The high pressure fuel injection device according to claim 3, wherein a gap seal (18) is formed between the outer circumference of the cylindrical part (17) and the valve housing (2).

5. The high pressure fuel injection device according to claim 4, wherein the diameter d1 of the gap seal 18 is larger than the diameter ds of the valve seat 16.

The distance A between the follower 9 and the armature 7 in the starting position is the total stroke H of the armature 7 and the distance as claimed in claim 2. A high pressure fuel injection device, characterized in that it is smaller than the difference in (A).

7. The high pressure fuel injection device according to any one of the preceding claims, characterized in that a throttle (21) is arranged between the pressure chamber (12) and the low pressure region (19).

7. The high pressure fuel injection device according to any one of the preceding claims, characterized in that a leak shutoff valve (26) is arranged between the pressure chamber (12) and the low pressure region (19).

9. The leak shutoff valve (26) according to claim 8, wherein the leak shutoff valve (26) comprises a collar-shaped extension (22) formed in the valve needle (3) as a closing member, wherein the seat (23) of the leak shutoff valve (26) is High pressure fuel injection device, characterized in that formed in the valve housing (2).