DE102005032464A1 - Fuel injecting device for use in e.g. high pressure accumulator injecting system, has pre-controlling space and damping space hydraulically connected by connecting channel that has reactive unit serving as discharging reactor - Google Patents

Abstract

The device has a fuel injector supplying a fuel that is highly pressured, and an injecting value unit (42) supplying the fuel by a pressuring space. An injecting opening (50) is released and closed in a combustion chamber (52), and the unit (42) is operated by a control valve. A pre-controlling space and a damping space are hydraulically connected by a connecting channel that has a reactive unit serving as a discharging reactor.

Description

The The invention relates to a fuel injector for internal combustion engines, in particular a stroke-controlled fuel injector for high-pressure accumulator injection systems.

DE 102 18 904 A1 refers to a fuel injector. The fuel injection device comprises a fuel injector, which can be supplied by a high-pressure fuel source. Between the fuel injector and the high-pressure fuel source is connected to a movable pressure booster piston having pressure booster. This comprises a pressure booster piston, which separates a connectable to the high-pressure fuel source chamber from a high-pressure chamber connected to the fuel injector. By filling a back space of the pressure booster device with fuel or by emptying the rear space of fuel, the fuel pressure in the high-pressure chamber can be varied. The fuel injector comprises a movable closing piston for opening and closing injection openings, wherein the closing piston projects into a closing pressure space, so that the closing piston is acted upon by fuel pressure, in order to achieve a force acting on the closing piston in the closing direction. The closing pressure chamber and the back space are formed by a common closing pressure back space. All partial areas of the closing pressure rear space are permanently connected to one another for the purpose of exchanging fuel. There is provided a high-pressure space for supplying the injection openings with fuel and for acting on the closing piston with a force acting in the opening direction. The high-pressure chamber communicates with the high-pressure fuel source in such a way that at least the fuel pressure of the high-pressure fuel source can constantly rest in the high-pressure chamber, the pressure chamber and the high-pressure chamber being formed by a common injection space. All sections of the injection chamber are permanently in communication with each other for the exchange of fuel.

stroke- High-pressure accumulator injection systems advantageously allow that the injection pressure at load and speed of the internal combustion engine can be adjusted.

Known are stroke-controlled fuel injectors, a piezoelectric actuator and a 3/2-way control valve to Control of the pressure in a control room for the needle-shaped Have injection valve member. The control room of such fuel injectors will when opening of the needle-shaped trained injection valve member via an inlet and an outlet throttle flows through. This results in a relatively high tolerance sensitivity of this Fuel injectors on different parameters such as the opening pressure of the injection valve member and the ratio of the flow cross sections from inlet throttle to outlet throttle to each other. Furthermore, goes with such solutions a very high sensitivity of the drift behavior over the Lifetime regarding an adjusting wear on the seat of the injection valve member associated. To comply with the expected future Emission limit values, in particular for self-igniting internal combustion engines, In contrast, a very high injection accuracy is required, by no means by a lifetime drift, caused by a weary one Seat of the injection valve member, may be influenced.

presentation the invention

task the present invention is to provide a fuel injector the high insensitivity to manufacturing tolerances and Operating parameters has.

Of the proposed according to the invention solution following, will change one hydraulic circuit of the needle-shaped injection valve member acting control room to improve the tolerance sensitivity proposed. In the hydraulic circuit according to the invention is a separate throttle for controlling the opening speed of Realized injection valve member, so that the opening speed of the acicular trained injection valve member not dependent on a throttle ratio such as for example, the flow area ratio of Inlet to outlet throttle is. This allows on the one hand the tolerance sensitivity reduce production-related dimensional variations, on the other hand let yourself be chosen by the solution the design limits for the achievable opening speed expand an injection valve member.

In contains advantageous manner the invention proposed Fuel injector for High-pressure injection systems a pilot chamber and a damping chamber, which is preferably needle-shaped trained injection valve member is assigned directly. To one fast closing of the preferred acicular to allow trained injection valve member is additionally a Filling path to damping space created the injection valve member, in which a check valve can be integrated.

the inventive proposal following, has the throttle element used as an outlet throttle a very small flow on. This leads to a stable manufacturing tolerance insensitive behavior of the injection valve member. In addition, the tolerance insensitivity increases the injection valve member by the inventively proposed solution in the course of operation adjusting nozzle seat wear. The lifting speed of the preferably acicular trained injection valve member can be arbitrarily slow vote and is now not limited by a minimum opening pressure. This in turn leads to a very advantageous, ramped injection course, which In turn, the emissions of the internal combustion engine favorably influenced and positive effects regarding the noise behavior of the self-igniting Internal combustion engine has.

In contrast, can independently from the opening speed preferably needle-shaped Injection valve member whose closing speed over second throttle element can be adjusted. Will this second throttle element with a relatively large one Flow cross-section made, can be a very fast closing of the preferred acicular trained injection valve member can be achieved.

drawing

Based In the drawings, the invention will be described below in more detail.

It shows:

1 A hydraulic circuit diagram of an embodiment of the inventively proposed fuel injector,

2 Another embodiment of the present invention proposed fuel injector with integrated Rückström throttle valve within the control room and

3 An embodiment of the present invention proposed fuel injector with a 3/2-control valve, which is actuated by means of a piezoelectric actuator.

The representation according to 1 the hydraulic circuit diagram of a fuel injector proposed according to the invention can be seen.

As shown in the illustration 1 shows, is a fuel injector 10 , which is preferably a stroke-controlled Kraftstoffinjektor for high-pressure injection systems, with a pressure accumulator 12 (common rail). The accumulator 12 will have an in 1 not shown high pressure source constantly pressurized with system pressure.

From the accumulator 12 branches a high pressure line 14 into which a damping throttle 16 integrated, via which pressure oscillations in the high-pressure line 14 from the accumulator 12 kept away. The high pressure line 14 flows into a pilot room 32 to which a second throttle element 26 upstream. The second throttle element 26 , which serves as inlet throttle for the pilot control room 32 serves, is in the injector body 18 of the fuel injector 10 let in, the injector body 18 can be constructed in several parts. From the pilot control room 32 branches a third throttle element 28 over which the pilot control room 32 in a return 22 can be depressurized. Between the return 22 and the third throttle element 28 is a switching valve 20 interposed, which is, for example, electromagnetically actuated. To accelerate the pressure build-up in the pilot control room 32 is provided a dashed line branch, which with closed switching valve 20 Fuel via the third throttle element 28 the pilot control room 32 zuleitet, so that the pilot room 32 with closed switching valve 20 both via the second throttle element 26 as well as the third throttle element 28 - Which can be flowed through in both directions - can be filled.

Below the pilot control room 32 There is a damping chamber in the injector body 34 , which is a preferably needle-shaped injection valve member 42 applied. The damping chamber 34 on the one hand by a on the injection valve member 42 absorbed sealing sleeve 36 and on the other hand from a plane surface 38 of the injector body 18 limited. The sealing sleeve 36 For example, may have a biting edge, by means of the spring element 40 , which is attached to a covenant 44 of the injection valve member 42 supported, to the plane surface 38 of the injector body 18 is hired.

The sealing sleeve 36 , the spring element 40 and the injection valve member 42 are enclosed by a hydraulic space, which over one of the high-pressure line 14 branching high pressure inlet 56 is pressurized with fuel under system pressure. Due to the system pressure level prevailing in the hydraulic space, the fuel present there flows over at the injection valve member 42 trained open spaces 46 Injection ports 50 in a combustion chamber 52 an internal combustion engine too. In the presentation, according to 1 , is the injection valve member 42 in his seat 48 at the combustion chamber end of the fuel injector 10 placed so that the injection openings 50 in the combustion chamber 52 the internal combustion engine are closed. In this operating state of the injection valve member 42 Consequently, no fuel in the combustion chamber 52 injected.

The pilot control room 32 and the damping room 34 of the fuel injector 10 stand over a canal 55 which is a first throttle element 24 contains and another channel 55 in which a check valve 54 is received, hydraulically in communication. Starting from the in 1 shown switching position of the switching valve 20 In which this is closed, the pilot room becomes 32 pressurized; over the channel in which the first throttle element 24 is contained in the pilot storage room 32 pending system pressure also in the damping chamber 34 at. Thus, the injection valve member 42 in his seat 48 pressed. Will the switching valve 20 controlled, follows a pressure relief of the pilot control room 32 via the third throttle element in the return 22 , As a result, the pressure in the damping chamber also drops 34 off, leaving the injection valve member 42 opens and provided on the combustion chamber side end injection openings 50 in the combustion chamber 52 the internal combustion engine releases. During the opening phase of the preferably needle-shaped injection valve member 42 Fuel is via the first throttle element 24 from the damping chamber 34 in the pilot control room 32 repressed. This leads to a damping of the opening movement of the preferably needle-shaped injection valve member 42 , Depending on the design of the first throttle element 24 can be the opening speed of the needle-shaped injection valve member 42 to adjust. During the opening phase of the injection valve member 42 the check valve remains 54 closed.

A closing of the injection valve member 42 takes place by renewed activation of the switching valve 20 , so, that the pilot control room 32 from the return 22 is disconnected. In the pilot room 32 the system pressure builds up in the accumulator 12 prevails. Because of in the pilot control room 32 building up pressure, the damping chamber becomes 34 over which the first throttle element 24 containing channel 55 as well as over the canal 55 in which the check valve 54 recorded, filled. Depending on the stroke of the spring-loaded check valve 54 and depending on the design of the second Dros selelementes 26 allows the closing speed of the preferred needle-shaped injection valve member 42 to adjust. To accelerate the closing process of the injection valve member 42 can the pilot control room 32 both via the second throttle element 26 which is in the high pressure supply line 14 is included, as well as via a branch - the in 1 is shown in dashed lines and a fourth throttle element 30 receives - over the third throttle element 28 be filled. Accordingly, the pilot control room 32 be filled faster during closing.

The representation according to 2 is a further embodiment of the inventively proposed fuel injector can be seen, wherein the first throttle element is received in a piston contained in the space.

According to the in 2 illustrated embodiment is - deviating from the in 1 illustrated embodiment - in the injector body 18 the first throttle element 24 as integrated Rückströmdrosselventil 60 in a flask 62 educated. The serving as a valve element piston 62 contains a throttle channel 64 over which the damping chamber 34 with the pilot control room 32 hydraulically communicating. In this embodiment, the integrated Rückströmdrosselventil forms a check valve. The in the damping room 34 recorded, serving as a valve element piston 62 rests on a spring 66 on the front side of the preferred designed as a nozzle needle injection valve member 42 from.

Also in this embodiment, the pilot chamber 32 via the one damping throttle 16 containing high pressure line 14 , in which also the second throttle element 26 may be included, pressurized with system pressure. The pilot control room 32 is about the third throttle element 28 and an intermediate switching valve 20 in the return 22 be pressure. Also in this embodiment branches from the high pressure line 14 a branch off, which is a fourth throttle element 30 contains, which with closed switching valve 20 over the third throttle element 28 a faster filling of the pilot control room 32 allowed.

The damping chamber 34 , in which the the integrated Rückströmdrossel 24 containing pistons 62 is absorbed, via the sealing sleeve 36 sealed. The sealing sleeve 36 is by means of a spring element 40 which is attached to the covenant 44 of the injection valve member 42 supported, against a plane surface of the injector body 18 hired.

The sealing sleeve 36 , the spring element 40 and the injection valve member 42 are accommodated in a hydraulic space, which via the high-pressure inlet 56 subjected to system pressure. As a result, fuel flows from the hydraulic space along the open spaces 46 below the covenant 44 of the injection valve member 42 the combustion chamber end of the injection valve member 42 to. Im in 2 State shown are the injection openings 50 in the combustion chamber 52 the self-igniting internal combustion engine, through the injection valve member 42 locked.

The functioning of the in 2 illustrated embodiment of the inventively proposed fuel injector is analogous to the operation of the in 1 illustrated embodiment of the fuel injector.

The representation according to 3 is a further embodiment of the inventively proposed fuel injector to refer, which is a 3/2-control valve 70 contains, which is controlled by a piezoelectric actuator.

Unlike the in 1 and 2 illustrated embodiments of the inventively proposed fuel injector, in this embodiment, a 3/2-control valve 70 used. The 3/2 control valve 70 causes the pressure relief of the pilot control room 32 in the return 22 that is the connection of the pilot control room 32 with the low pressure side of the fuel injection system.

Analogous to the in 1 and 2 illustrated embodiments of the fuel injector 10 flows under system pressure fuel from the pressure accumulator 12 via the high pressure supply line 14 that the damping choke 16 contains, the pilot control room 32 of the injector body 18 to. In the high pressure supply line 14 is the second throttle element 26 integrated. Before the second throttle element 26 branches a high-pressure branch 86 which is located in a hydraulic chamber of the 3/2-way control valve 70 at the second seat 74 empties. Into the hydraulic space of the 3/2 control valve 70 also opens a connection line from the pilot control room 32 from runs and which the third throttle element 28 contains. Is the 3/2 control valve 70 closed, so is the valve element 84 in the first seat 72 , In this case, the branch 86 from the high pressure line 14 and the connection line, which is the third throttle element 28 contains, short closed, leaving the pilot control room 32 both via the second throttle element 26 as well as the third throttle element 28 is filled with fuel under system pressure. In the closed state, ie in the first seat 72 Asked state of the valve element 84 is the return 22 closed to the low pressure side of the fuel system.

The 3/2 control valve 70 is about an actor 76 driven. Will the actor 76 , which may be a piezoelectric actuator containing a plurality of stacked piezocrystals, is supplied with a voltage, then it drives with the actuator 76 connected actuator pistons 82 in a coupling room 78 and acts on an actuating piston 80 , in turn, on the valve element 84 of the 3/2 control valve 70 acts. Upon application of the actuating piston 80 becomes the hemispherical formable valve element, for example 84 from the first seat 72 emotional. Depending on the voltage applied to the actuator 76 the actuating piston moves 80 partially or completely in the hydraulic space of the 3/2 control valve 70 and can, contrary to the action of the spring received in the hydraulic space with its lower end face in its second seat 74 be moved, where the high-pressure branch 86 empties.

The pilot control room 32 of the fuel injector 10 is about the first throttle element 24 containing channel and another, the check valve 54 containing channel 55 , with the damping chamber 34 hydraulically connected. Analogous to the embodiments according to 1 and 2 is the damping room 34 through a sealing sleeve 36 limited. The sealing sleeve 36 is on preferably needle-shaped injection valve member 42 guided. The sealing sleeve 36 is on an end face of the spring element 40 which is in turn at the covenant 44 supported, which at the periphery of the preferably needle-shaped injection valve member 42 is trained. Due to the effect of the spring element 40 is the sealing sleeve 36 with a biting edge to the plane surface 38 of the injector body 18 hired. The sealing sleeve 36 , the feather 40 and the upper portion of the preferably needle-shaped injection valve member 42 are surrounded by a hydraulic space, which via the high-pressure inlet 56 and the high pressure line 14 is pressurized with fuel under system pressure. The fuel contained in the hydraulic space and under system pressure flows over the circumference of the preferably needle-shaped injection valve member 42 trained flow areas 46 the seat 48 of the injection valve member 42 to. In in seat 48 set injection valve member 42 they are in the combustion chamber 52 the self-igniting internal combustion engine opening injection openings 50 locked.

The functioning of the in 3 illustrated embodiment of the fuel injector 10 Is as follows:
Starting from the in 3 shown switching state of the 3/2-control valve 70 is the return 22 of the fuel injector 10 because of in his first seat 72 Asked valve element 84 of the 3/2 control valve 70 from the pilot room 32 separated. In this operating state, the pilot control room 32 both via the second throttle element 26 as well as the third throttle element 28 pressurized fuel. The in the pilot room 32 prevailing pressure also prevails in the damping room 34 who with the control room 32 over which the first throttle element 24 containing channel and over which the check valve 54 containing channel communicates hydraulically. Due to the in the damping room 34 Sir Shearing pressure is the preferred needle-shaped injection valve member 42 in his combustion chamber side seat 48 posed. As a result, the injection ports are 50 at the combustion chamber end of the injection valve member 42 in the combustion chamber 52 closed the internal combustion engine. In the in 3 shown switching state is the actuator 76 , which over the coupling space 78 on the valve element 84 of the 3/2 control valve 70 acts, not subjected to a voltage.

If, however, a voltage to the actuator 76 created, this expands, leaving the actuator piston 82 in the coupling room 48 retracts. This will cause the actuating piston 80 shifted in the vertical direction, causing the valve element 84 from his first seat 72 is pressed. Now the pilot room is 32 via the flow in the outflow direction of fuel third throttle element 28 in the return 22 be pressure. The damping chamber 34 on the other hand, only the first throttle element is used 24 containing channel 55 depressurized; the check valve 54 remains in its closed position. Depending on the design of the throttle cross-section of the first throttle element 24 can be the opening speed of the injection valve member 42 to adjust. The corresponding to the pressure relief of the damping chamber 34 opening, needle-shaped injection valve member 42 now gives the injection openings 50 at the combustion chamber end of the injection valve member 42 free, so from the hydraulic space in which the sealing sleeve 36 , the feather 40 , the Bund 44 and the upper part of the injection valve member 42 are absorbed, fuel over the flow areas 46 the injection openings 50 and about this in the combustion chamber 52 the internal combustion engine can be injected.

All three embodiments described above, the inventively proposed fuel injector 10 is common that the opening speed of the injection valve member 42 by the design of the first throttle element 24 is realized. As a result, on the one hand, the tolerance sensitivity is reduced compared to, for example, a throttle cross-sectional ratio and on the other hand, the design limits for the feasible opening speeds of the needle-shaped injection valve member 42 extended. Furthermore, all three embodiments have in common that an additional filling path in the form of a high-pressure branch with a second throttle element 26 in the pilot control room 32 consists. Due to the configuration of the first throttle element 24 with a small flow rate can be a stable, largely production tolerance insensitive behavior of the needle-shaped injection valve member 42 to reach. The opening speed of the injection valve member 42 can be tuned arbitrarily slowly and is not dependent on a minimum opening pressure. This in turn can be advantageously a ramp-shaped course of fuel injection into the combustion chamber 52 which in turn leads to an improvement of the emissions of the internal combustion engine as well as to a reduction of the noise level.

All three embodiments shown is also common that the closing speed of the needle-shaped injection valve member 42 independent of the selected throttle cross-section of the first throttle element 24 , via a second throttle element 26 and optionally a third throttle element 28 can be done. Depending on the selected design of the second throttle element 26 and the third throttle element 28 can be a quick closing of the injection valve member 42 depending on the available flow cross section. In particular, a rapid closing of the injection valve member 42 be done by the pilot control room 32 on the one hand acted upon two filling paths and on the other hand, the filling of the damping chamber 34 both over the first throttle element 24 containing channel as well as the other, the check valve 54 containing channel can take place.

10

fuel injector

12

accumulator (common rail)

14

High-pressure line

16

damping throttle

18

injector

20

switching valve

22

returns

24

first throttle element

26

second throttle element

28

third throttle element

30

fourth throttle element

32

pilot chamber

34

damping space

36

sealing sleeve

38

Planar injector body

40

spring element

42

Injection valve member

44

Federation

46

open space

48

Seat

50

Injection port

52

combustion chamber

54

check valve

55

channel

56

High-pressure inlet

60

integrated Rückströmdrosselventil

62

piston (Valve element)

64

throttle channel

66

feather

70

3/2 control valve 70

72

first Seat

74

second Seat

76

actuator

78

coupling space

80

actuating piston

82

actuator piston

84

valve element

86

High pressure branch

Claims (10)

Fuel injection device for internal combustion engines with a fuel injector ( 10 ), which via a high-pressure fuel source ( 12 ) is acted upon by high-pressure fuel and with an injection valve member ( 42 ), which via at least one pressure chamber ( 32 . 34 ) is pressurized with high pressure fuel and injection openings ( 50 ) in a combustion chamber ( 52 ) releases or closes and the injection valve member ( 42 ) by means of a switching valve ( 20 . 70 ) is actuated, characterized in that a pressurized with high-pressure fuel pilot space ( 32 ) and a damping chamber ( 34 ) via at least one connecting channel ( 55 . 64 ) are hydraulically connected, which serves as a drain throttle first throttle element ( 24 ). Fuel injection device according to claim 1, characterized in that the pilot control chamber ( 32 ) and the damping chamber ( 34 ) over a channel ( 55 ), which is a check valve ( 54 ) communicates hydraulically. Fuel injection device according to claim 1, characterized in that the pilot control chamber ( 32 ) via a second throttle element ( 26 ) can be filled with fuel under high pressure. Fuel injection device according to claim 1, characterized in that the connecting channel ( 64 ) with the first throttle element ( 24 ) in a damping chamber ( 34 ) arranged valve element ( 62 ) is trained. Fuel injection device according to claim 3, characterized in that the pilot control chamber ( 32 ) with open switching valve ( 20 . 70 ) via the third throttle element ( 28 ) is pressure relieved Fuel injection device according to claim 3, characterized in that the flow through the first throttle element ( 24 ) compared to the flows through the second throttle element ( 26 ) and the third throttle element ( 28 ) is small. Fuel injection device according to claim 1, characterized in that when closing the injection valve member ( 42 ) the pilot control room ( 32 ) simultaneously via a high pressure supply line ( 14 ) with second throttle element ( 26 ) and by means of a branch ( 86 ) via the third throttle element ( 28 ) and the damping chamber ( 34 ) over the canal ( 55 ) with check valve ( 54 ). Fuel injection device according to claim 1, characterized in that when opening the injection valve member ( 42 ) the pilot control room ( 32 ) via the third throttle element ( 28 ) in a return ( 22 ) and the damping chamber ( 34 ) only via the connection channel ( 64 ) with first throttle element ( 24 ) into the pilot control room ( 32 ) is depressurized. Fuel injection device according to claim 1, characterized in that the switching valve ( 20 ) as a 3/2 control valve ( 70 ) is executed, whose valve element ( 84 ) by means of a piezoelectric actuator ( 76 ) between a first seat ( 72 ) and a second seat ( 74 ) is switchable. Fuel injection device according to claim 9, characterized in that the 3/2-control valve ( 70 ) has a hydraulic space which via the valve element ( 84 ) with the return ( 22 ) and in which a branch ( 86 ) from the high pressure supply line ( 14 ) and a connecting line to the third throttle element ( 28 ) from the pilot control room ( 32 ) below the second seat ( 74 ).