EP2462335A1

EP2462335A1 - Device for high-pressure fuel injection

Info

Publication number: EP2462335A1
Application number: EP10728156A
Authority: EP
Inventors: Sebastian Jansen
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2009-08-05
Filing date: 2010-06-17
Publication date: 2012-06-13
Anticipated expiration: 2030-06-17
Also published as: KR20120040731A; WO2011015405A1; EP2462335B1; KR101762106B1; DE102009028234A1

Abstract

The invention relates to a valve arrangement for high-pressure fuel injection, comprising a valve housing (2), an outward opening valve needle (3) arranged in the valve housing (2) in a compression chamber (4) filled with fuel to which fuel (K) is supplied under pressure, wherein the valve needle (3) is sealed off at a valve seat (16), a closing spring (5) that guides the valve needle (3) back to a starting position, an electromagnetic actuator (6) with a displaceably arranged armature (7) to actuate the valve needle (3), and a control valve (8) with a valve element (10) and a valve seat (11), wherein the valve element (10) has a first functional surface (13) and a second functional surface (14), wherein the first functional surface (13) faces the compression chamber (4), the second functional surface (14) faces a pressure chamber (12) connected to a low-pressure space (ND), and the valve element (10) enables and closes a connection between the compression chamber (4) and the pressure chamber (12), and the valve seat (11) is arranged on the armature (7) or a component connected to the armature (7), wherein upon the activation of the electromagnetic actuator (6), the control valve (8) opens in front of the outward opening valve needle (3) to reduce an opening force for the valve needle (3) by enabling the connection between the compression chamber (4) and the pressure chamber (12).

Description

description

title

Device for high-pressure fuel injection prior art

The present invention relates to a device for high pressure fuel injection, in particular in internal combustion engines with direct injection in

Stratified charge mode is used.

As high-pressure fuel injection devices in direct-injection engines, high-pressure injection valves become outward

opening valve needle used because of its advantageous

Spraicharakteristik due to the annular gap between the valve needle and

Valve body are particularly suitable for combustion processes with beam-guided stratified operation. However, with injectors with outward opening

Valve needle due to the larger diameter seat of the valve needle, the hydraulic force generated by the fuel pressure significantly higher than compared to injectors with inwardly opening needle. Because of the high forces and short switching times are therefore usually injectors with

Piezo actuators used, however, cause an increased cost.

In a concept described in EP 1783 358A1 an injection valve with outwardly opening valve needle is disclosed, which is actuated by a solenoid actuator and having a guide element on the valve needle, which in a

Valve housing is guided, wherein the diameter of the guide element and a valve seat of the valve needle are selected so that the valve needle in

Is essentially pressure balanced. The high-pressure injection valves of the prior art are only insufficiently suitable to a simple and inexpensive to produce device for To provide high-pressure injection for internal combustion engines with direct injection in stratified charge mode, which provides a high sealing force between the valve seat and valve needle in the closed state, and can be operated by a magnetic actuator with low actuation force or low power consumption, while a comparable switching dynamics as a

Has injection valve with piezo actuator.

DISCLOSURE OF THE INVENTION The valve arrangement according to the invention with the features of

Claim 1, in contrast, has the advantage that it has a simple and thus more cost-effective design with a magnetic actuator having a valve needle opening outwardly due to a pressure equalization effective at the valve needle with a significantly reduced

Actuating force opens. Therefore, in the inventive

Valve assembly solenoid actuators with low power requirements, especially at injection pressures of 20 MPa or higher, are used, which allow sufficient switching dynamics and a reliable sealing of the valve needle on the valve seat of the valve in the closed state. This is inventively achieved in that when activating a

electromagnetic actuator a between the high pressure area and

Low pressure region of the valve assembly disposed control valve is opened in front of an outwardly opening valve needle. By releasing a connection between a pressure chamber in the high pressure area and a

Pressure chamber in the low pressure region of the valve assembly is a

Pressure equalization, d. H. a pressure increase in the low pressure region, which causes a hydraulic force on an active surface of a valve element of the control valve in the opening direction of the valve needle and thereby significantly reduces an opening force of the electromagnetic actuator for the valve needle. As a result, an easy and fast switching is possible. The control valve is opened by means of a freely movable magnet armature or a component connected to the magnet armature.

The dependent claims show preferred developments of the invention. According to a preferred embodiment of the invention, the

The device according to the invention for high-pressure fuel injection further comprises a driver attached to the valve needle with an armature contact region, wherein the driver is arranged in the starting position at a predetermined distance from the armature and the armature movable on the

Valve needle is arranged. A closing spring for closing the valve needle also restores the armature. This ensures that upon activation of the electromagnetic actuator whose armature first moves from the starting position to the armature contact region of the driver and thereby opens the control valve for pressure equalization, without operating the valve needle. Only when the armature is applied to the driver, the

Valve needle operated and opened directly via the armature.

Preferably, a ring-cylindrical component is attached to the armature, wherein on a free end face of the annular-cylindrical component of the valve seat of the

Control valve is arranged. This will be a simple design of the

Control valve with a minimum number of components achieved.

Further preferred is between the annular cylindrical member and the

Valve housing formed a gap seal. As a result, a simple and cost-effective seal between the two components is realized with a small amount of leakage.

Particularly preferably, a diameter of the gap seal is formed larger than a diameter of the valve seat of the valve needle. In this way, a resulting hydraulic force is generated in the opening direction of the valve needle with open control valve and pressure equalization and thus reduces the force to be overcome by the armature opening force of the valve needle. When the control valve is closed results from the low pressure in the

Pressure chamber, however, a hydraulic force in the closing direction of the

Valve needle, which causes a reliable sealing of the valve.

According to a further preferred embodiment of the invention, the distance from the starting position of the magnet armature to the driver attached to the valve needle is smaller than a total stroke of the magnet armature, ie, there is a residual stroke for opening the valve needle. Through a first partial stroke the magnet armature from the starting position to the driver is a rapid opening of the control valve for pressure equalization and thus a rapid pressure equalization for the easier opening of the valve needle achieved, which is then opened with a second partial stroke. When closing the valve needle is first a first partial stroke of the armature from the driver to the

executed closed position of the control valve and the control valve thus closed. Here, the valve element of the control valve acts as another actuated by the armature driver for the return of the valve needle. By thus again occurring at the control valve pressure difference between the high pressure region and the low pressure region of the device can then close the valve needle by a closing direction in the

Valve needle supportive hydraulic force to be done faster.

This can reduce the use of magnetic actuators

Power consumption allows and for gasoline injection in the

Shift operation of internal combustion engines required switching dynamics can be realized.

According to a further preferred embodiment of the invention, the device for high-pressure fuel injection between the pressure chamber and the low-pressure region further comprises a throttle. This is going to be easy

Way a rapid pressure reduction over an annular gap between the valve needle and the valve housing in the pressure chamber with the control valve closed and thus achieved a high contact pressure and a good sealing effect between the valve needle and the valve seat.

Alternatively to the throttle can between the pressure chamber and the

Low pressure range a leakage stop valve can be used. As a result, a leakage or return amount of fuel to a fuel return when opening the valve needle is significantly reduced. Thus, the

inventive device can be used very economically.

Preferably, the leakage check valve has a closing member on the

Valve needle formed collar-like extension and a seat which is formed on the valve housing. This is a simple structure of the

Leakage check valve with a minimum number of components feasible.

Furthermore, this can provide a very reliable device. Short description of the drawing

Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings. In the drawing is:

Figure 1 is a simplified schematic sectional view of

device according to the invention with valve needle closed FIG. 2 is an enlarged schematic sectional view of a part of the device of FIG. 1,

Figure 3 is a simplified schematic sectional view of

Device of Figure 1 when opening the valve needle,

Figure 4 is a simplified schematic sectional view of

Device of Figure 1 with open valve needle,

FIG. 5 is an enlarged schematic sectional view of part of the device of FIG. 4;

Figure 6 is a simplified schematic sectional view of

Device of Figure 1 when closing the valve needle, Figure 7 is a simplified schematic sectional view of a second

Embodiment of the device when closed

Valve needle,

Figure 8 is a simplified schematic sectional view of

Device of Figure 7 with open valve needle,

9 shows an enlarged schematic sectional view of a part of the device of FIG. 7 with the valve needle closed, and FIG. 10 shows an enlarged schematic sectional view of part of the device of FIG. 7 with the valve needle open. Hereinafter, with reference to FIGS. 1 to 6, a device 1 for high-pressure fuel injection according to a first preferred

Embodiment of the invention described in detail.

Figure 1 shows a schematically simplified sectional view of

Device according to the invention in the closed state. As can be seen from the schematic sectional illustration of FIG. 1, the device 1 comprises a valve housing 2, an outwardly opening valve needle 3, which is arranged in the valve housing 2 in a pressure chamber 4 filled with fuel.

This pressure chamber 4, a fuel K is supplied via a fuel inlet 24 under pressure, wherein the valve needle 3 to a valve seat 16 on

Valve housing 2 seals. Furthermore, the device 1 has a closing spring 5, which returns the valve needle 3 to a starting position, and an electromagnetic actuator 6 with a magnetic coil 63, an inner pole 62, a magnet housing 61 and a movably arranged magnet armature 7, the valve needle 3 via a thereto trained or attached driver 9 is actuated. A control valve 8 with a valve element 10 and a valve seat 1 1 is arranged on one of the injection side opposite end portion 29 of the valve needle 3.

The valve element 10 has a first active surface 13, which faces the pressure chamber 4, and a second active surface 14, which faces a pressure chamber 12, which communicates with a low-pressure region 19. The valve element 10 of the control valve 8 is designed to release a connection between the pressure chamber 4 and the pressure chamber 12 and to close, wherein the valve seat 1 1 of the control valve 8 at an end face of an am

Magnet armature 7 attached annular cylindrical member 17 is arranged.

Between the outer circumference of the annular cylindrical member 17 and the

Valve housing 2 is a gap seal 18 is formed with a small guide clearance.

As can be seen from Figure 1, are in the armature 7 and in

annular cylindrical member 17 through openings 30, 31, formed for the supply of fuel K. Accordingly, when the valve needle 3 is closed and the control valve 8 is closed, the high pressure of the fuel inlet 24 is present supplied fuel in all connected to the pressure chamber 4

Interiors of the device. In the pressure chamber 12, there is low pressure, since it is connected via a throttle 21 to the fuel return 25 and the control valve 8 is closed.

Since in the device 1 according to the invention a diameter ds des

Valve seat 16 is smaller than a diameter d1 of the valve element 10, the valve needle 3 is additionally pressed in addition to the force of the closing spring 5 by a hydraulic force component in the valve seat 16, resulting from this difference in diameter. This is a reliable seal the

Device 1 ensured when the valve needle 3 is closed.

Figure 2 is an enlarged schematic sectional view illustrating a part of the device 1 of Figure 1 in more detail. As can be seen from the illustration of FIG. 2, when the housing is in the closed state

Device 1 with closed control valve 8 and inactivated

electromagnetic actuator 6 whose armature 7 in his

Starting position. The closing spring 5 acts on the armature 7 and is supported on the housing 2 from. In this initial position, the axially freely movable armature 7 due to the spring force of the closing spring 5 a

Distance A to the driver 9 on the valve needle 3, and a distance H to the inner pole 62.

FIG. 3 shows a schematically simplified sectional view of the device 1 of FIG. 1 when the valve needle 3 is opened. In this case, the magnetic coil 63 of the electromagnetic actuator 6 is supplied with current (which is illustrated by a lightning-shaped symbol), the magnet armature 7 making a first partial stroke in the direction of the inner pole 62, which corresponds to the dimension of the distance A, until it touches the driver 9. As a result, the control valve 8 opens, so that fuel K flows from the fuel inlet 24 into the pressure chamber 4 and via the flow opening 31 into the pressure chamber 12 (as illustrated by an arrow B in FIG. 3). As a result, the pressure in the pressure chamber 12 rises directly and causes a force on the valve needle 3, the ratio of the hydraulically effective first and second active surfaces 13 and 14 am

Valve element 10 results, which are each subjected to high pressure. This resulting hydraulic force acts in the open control valve 8 in addition to Magnetic force of the armature 7 in the opening direction of the valve needle 3 and reduces the contact pressure of the valve needle 3 on the valve seat 16. The valve needle 3 can now be taken or moved with little force from the armature 3 via the driver 9 in the opening direction, so that the valve needle 3 opens and the injection process can begin.

FIG. 4 shows a schematically simplified sectional view of the device of FIG. 1 with the valve needle open. Due to the continued energization of the solenoid 63, the magnet armature 7 was pulled together with the valve needle 3 in the opening direction of the device 1 and has a second partial stroke to stop at the inner pole 62 executed, and thereby raised the valve needle 3 from the valve seat 16 to the outside and opened. The second partial stroke for opening the valve needle 3 is designed to be larger than the first partial stroke A for opening the control valve 8. The between the valve needle 3 and the

Valve body 2 outflowing fuel spray is indicated by small arrows C in the

Figure 4 illustrates.

FIG. 5 is an enlarged schematic sectional view illustrating a part of the device 1 of FIG. 4 in more detail. As can be seen from the illustration of FIG. 5, part of the valve flows when the control valve 8 is open

Fuel in the pressure chamber 12 via the throttle 21 (as illustrated by an arrow D) in the fuel return 25 as a leakage amount back. This leakage amount through the throttle 21 is defined or limited to a predetermined value, so that the pressure drop in the pressure chamber 12 after the

Shutdown of the electromagnetic actuator 6 (closing the valve needle 3) does not take too long and extends the dead times of the switching cycles and thus degrades the switching dynamics.

FIG. 6 illustrates a schematically simplified sectional illustration of the device of FIG. 1 when the valve needle 3 is closed. Here is the

State of the device 1 shown after switching off the

Magnetic coil 63 of the electromagnetic actuator 6 sets, wherein first the control valve 8 is closed. Thereafter, the pressure in the pressure chamber 12 decreases due to the connection to the fuel return 25 via the throttle 21 again, so that the second effective area 14 only with the low pressure from the

Fuel return 25 is acted upon. The first active surface 13 is still with the high pressure in the interior of the annular cylindrical member 17 acted upon. As a result, a hydraulic closing force is generated, which presses the valve needle 3 in addition to the spring force of the closing spring 5 in the valve seat 16 until the closed state of the valve needle 3 (see Figure 1) is restored and the

Injection process is completed. The closing spring 5 engages over the

Magnetic armature 7, the annular cylindrical member 17 and the valve element 10 to the valve needle 3 at.

Characterized in that the opening and closing of the valve needle 3 of the

Inventive device 1 for high-pressure fuel injection

hydraulically supported by the use of the pressure prevailing in the interior of the device 1 high pressure in conjunction with the arranged on the valve element 10 of the control valve 8 first and second active surfaces 13 and 14, the device 1 can already provide a high switching dynamics with high sealing force with relatively low magnetic forces.

Hereinafter, with reference to FIGS. 7 to 10, a device 1 for high-pressure fuel injection according to a second preferred

Embodiment of the invention described in detail. The same or functionally identical parts are denoted by the same reference numerals as in the first

Designated embodiment.

FIG. 7 shows a schematically simplified sectional illustration of a second exemplary embodiment of the device 1 according to the invention

High-pressure fuel injection with closed valve needle 3. The second

Embodiment of the device 1 according to the invention differs from the first embodiment described above in that in this case between the pressure chamber 12 and the low-pressure region 19 of

Fuel return 25 a leakage check valve 26 is arranged. By the leakage check valve 26 is a leakage amount to the fuel return 25, as occurs in the first embodiment in the throttle 21, drastically reduced. The leakage check valve 26 has a collar-like extension 22 of the diameter at the end region 29 of the valve needle 3. In conjunction with a arranged at the output of the pressure chamber 12 stop 23 on the valve housing 2, the leakage check valve 26 closes the pressure chamber in the closed state

12 from the fuel return 25 from. As can also be seen from FIG. 7, when the valve needle 3 is closed the control valve 8 is closed and the leakage check valve 26 is opened so that a low pressure prevails in the pressure chamber 12.

FIG. 9 shows an enlarged schematic sectional view of a part of the device of FIG. 7, which illustrates the pressure conditions when the valve needle 3 is closed. As can be seen from FIG. 9, an annular groove 27 is in FIG

Valve housing 2 is formed in an area between the annular cylindrical member 17 and the valve element 10 of the control valve 8 to an unhindered

Fuel flow into the pressure chamber 12 with open control valve 8 (see FIG. 10) to allow. When the valve needle 3 is closed that is

Control valve 8 is closed and the leakage check valve 26 is opened. Here, behind the closed valve element 10 of the control valve 8, d. H. in the annular groove 27, the pressure chamber 12 and the adjacent fuel return 25th

Low pressure present (marked with the reference numeral 19), while in the remaining interior spaces of the device 1 to the closed

Valve element 10 is applied high pressure (indicated by the reference numeral 28).

As can be seen from FIG. 8, which shows a schematically simplified sectional representation of the second embodiment of FIG. 7 with the valve needle 3 open, in this state the leakage check valve 26 is closed and the control valve 8 is opened. In this case, high pressure prevails in the pressure chamber 12, so that the valve needle 3 can be opened with small forces. Since that

Leakage check valve 26 is closed, no leakage occurs in the

Fuel return 25 off. The abutting the stop 23 collar-like

Extension 22 of the leakage check valve 26 also defines a stroke stop of the opened valve needle 3.

FIG. 10 shows an enlarged schematic sectional view of a part of the device of FIG. 8, which illustrates the pressure conditions when the valve needle 3 is open. As can be seen from FIG. 10, in this case the control valve 8 is opened and the leakage blocking valve 26 is closed. The high-pressure region 28 is in this case both in the control valve 8 and in the leakage check valve 26 formed while only in the fuel return 25 of the low pressure region 19 is formed.

Due to the low forces that are required in the inventive device 1 for high-pressure fuel injection for opening and closing the valve needle 3, the actuation of the valve needle 3 directly by a low-cost electromagnetic actuator, even at high

Injection pressures of 20 MPa, carried out with a sufficiently high switching dynamics. Because of the correspondingly low power requirement of the electromagnetic actuator, the control of the device 1 can therefore be compared with conventional, d. H. available power amplifiers for solenoid high-pressure injection valves. This contributes to another

Cost reduction and thus increased efficiency of

Device 1 according to the invention for high-pressure fuel injection.

Claims

claims

1. A device for high-pressure fuel injection, comprising

a valve housing (2),

- An outwardly opening valve needle (3) which is arranged in the valve housing (2) in a fuel-filled pressure chamber (4), the fuel

(K) is supplied under pressure, wherein the valve needle (3) on a

Valve seat (16) seals,

a closing spring (5) which returns the valve needle (3) to a starting position,

- An electromagnetic actuator (6) with a movable

arranged magnet armature (7) for actuating the valve needle (3), and

- A control valve (8) having a valve element (10) and a valve seat (1 1), wherein the valve element (10) has a first active surface (13) and a second active surface (14), wherein the first active surface (13) the pressure chamber (4), the second active surface (14) of a

A pressure chamber (12) facing, which is in communication with a low pressure region (19), and the valve element (10) a connection between the pressure chamber (4) and the pressure chamber (12) releases and closes, and the valve seat (11) on the armature (7) or is arranged on a component connected to the magnet armature (7),

wherein upon activation of the electromagnetic actuator (6), the control valve (8) opens in front of the outwardly opening valve needle (3) to provide an opening force for the valve needle (3) by releasing the connection between the pressure chamber (4) and the pressure chamber (12 ) to reduce.

2. A device for high-pressure fuel injection according to claim 1, further comprising a on the valve needle (3) fixed driver (9) with an armature contact region (20), wherein the driver (9) in the starting position at a distance (A) from the armature (7). is arranged, and the

Magnetic armature (7) is movably arranged on the valve needle (3).

3. A device for high-pressure fuel injection according to claim 1 or 2, characterized in that the magnet armature (7) a ring-cylindrical member (17) is fixed, wherein at a free end face of

annular cylindrical member (17) of the valve seat (1 1) of the control valve (8) is arranged.

4. A device for high-pressure fuel injection according to claim 3, characterized in that between the outer circumference of the annular cylindrical member (17) and the valve housing (2) a gap seal (18) is formed.

5. A device for high-pressure fuel injection according to claim 4, characterized in that a diameter (d1) of the gap seal (18) is greater than a diameter (ds) of the valve seat (16).

6. A device for high-pressure fuel injection according to claim 2 to 5, characterized in that the distance (A) between the driver (9) and armature (7) in the starting position smaller than a difference of a total stroke (H) of the armature (7) and the distance (A) is.

7. A device for high-pressure fuel injection according to one of

preceding claims, characterized in that between the pressure chamber (12) and the low pressure region (19), a throttle (21) is arranged.

8. A device for high-pressure fuel injection according to one of claims 1 to 6, characterized in that between the pressure chamber (12) and the low pressure region (19) a leakage check valve (26) is arranged.

9. A device for high-pressure fuel injection according to claim 8, characterized in that the leakage check valve (26) as a closing member on the valve needle (3) formed collar-like extension (22) and a seat (23) of the leakage check valve (26) on the valve housing (2) is formed.