EP1584813A2 - Injector for combustion engine with a direct controlled nozzle needle - Google Patents

Abstract

An on/off nozzle (7) is provided to actuate the outer nozzle needle by connecting the closing chamber to low-pressure/return system. An additional on/off valve (90) is provided to actuate the inner nozzle needle (12) and to connect a control chamber (53) to the low-pressure/return system (88).

Description

The invention relates to a fuel injection device for internal combustion engines the preamble of claim 1.

State of the art

A fuel injector with two rows of injector nozzles with internal and external fuel injectors coaxial with an outer nozzle needle is assigned, for example, from DE 102 05 970 A1 known. Such injection nozzles, the pressure-dependent controlled release different injection cross sections are also referred to as Vario nozzles. The outer and inner nozzle needle is each assigned a control piston, respectively acting on a fuel-filled hydraulic space, so that the hydraulic Rooms act as actively connected control rooms. The two control rooms are over one Connecting channel hydraulically connected. The control room of the outer Nozzle needle is via an outlet throttle with a low-pressure return system connectable. The connecting channel is dimensioned so that when opening the Outflow throttle first, the pressure in the control chamber of the outer nozzle needle drops and only with a time delay, the pressure in the control chamber of the inner nozzle needle.

To increase the injection pressure, which is above the pressure level of the pressure accumulator (Common Rail) is from DE 102 29 417 A1 a fuel injection device with Pressure booster known, in addition to improving the Injection characteristic and to increase the efficiency also a Variodüse is inserted with an inner and an outer nozzle needles. It is the Opening pressure of the inner nozzle needle by spring support to a constant level or with the help of an additional assistant pressure on a certain ratio of Rail pressure and opening pressure set. This is an adaptation of the hydraulic Flow through the fuel injector to the load point of the internal combustion engine possible. The inner nozzle needle is adjusted so that they only at relatively high Pressing, for example, greater than 1500 bar opens, thus good emission levels in Partial load condition of the internal combustion engine to achieve. The setting of the constant Opening pressure for the inner nozzle needle is very sensitive to tolerances, as with the Opening of the inner nozzle needle is accompanied by a jump in quantity in the injection quantity. In this respect, specimen spreads are particularly unpleasant. In the another variant, the opening pressure of the inner nozzle needle on the constant Reaching the ratio of assist pressure and nozzle pressure opens the inner Nozzle needle even at partial load of the internal combustion engine.

To the effects of the variations in the control period of the control valve on the To prevent injection quantity in fuel injectors with pressure booster was already proposed in the earlier DE patent application 102 29 415.1, the To slow opening speed of a single nozzle needle, without a rapid closing of the nozzle needle is impaired. It is in the closing room of the Nozzle needle arranged a damping piston axially, which has a damping chamber limited and via an overflow channel with the closing space of the nozzle needle in Connection stands.

Object of the present invention is the adaptability of Fuel injection device to the operating points of the internal combustion engine continues to improve and meet the requirement for a homogeneous combustion process.

Advantages of the invention

The fuel injection device according to the invention with the characterizing Features of claim 1 has the advantage that an improved adaptation of the Injection time and the injection volume to the operating point of Internal combustion engine is possible. It is to control the outer nozzle needle a first switching valve and for driving the inner nozzle needle, a second switching valve intended. By means of the first switching valve is a closing space for the outer Nozzle needle connectable to a low pressure / return system. To control the inner nozzle needle is assigned to the inner nozzle needle control chamber by means of second switching valve with the low-pressure / return system connectable, so that a Pressure relief of the control room is done. This is a separate control of outer nozzle needle and the inner nozzle needle possible, so that the two Activate the nozzle needles of the Vario nozzle independently of each other. This can be done the injection quantity or the injection volume by means of the two rows of holes Injectors vary such that either a row of holes or the second row of holes or both rows of holes selected freely from injection to injection can or can. This is also the injection pressure level with and without Pressure ratio freely selectable.

The realized via the inclination of the nozzle bore inlet direction of the spray jet in the combustion chamber, which is also indicated as the elevation angle, influences besides the pressure and the injection angle, the combustion method of the internal combustion engine. If the two rows of holes of the nozzle holes for the injectors with different Tilt and / or spray cone are executed, the potential arises by the separately controllable rows of holes of the individual injectors with different To work at elevation angles, so that with a very small elevation angle a homogeneous Combustion at an early start of injection without wetting of the cylinder wall Internal combustion engine can be realized. Because homogeneous combustion process only can be used for certain loads of the internal combustion engine, also results from the flexible injection with different elevation angles or spray angles, one optimal adaptability to different combustion concepts.

The measures listed in the dependent claims are advantageous Further developments of the invention possible. Filling the control room from the Rail pressure system is useful via a throttle or via a check valve possible, wherein the check valve, the emptying of the control chamber in the control line locks.

By the independently feasible connection of the two nozzle needles, This control concept can be particularly useful in so-called leak-oilless Insert injector, in which for the inner injectors a separate Fuel supply is provided. The separate fuel supply leads from a the outer nozzle needle associated nozzle chamber to one of the inner injection nozzle upstream pressure shoulder on the inner nozzle needle. The separate fuel supply line is expediently as a gap between the inner nozzle needle and formed the outer nozzle needle. A quick closing of the outer nozzle needle is achieved when, within a closing space between the end face of the outer nozzle needle and an associated damping piston a parting line is formed and in addition a hydraulic connection between the damping chamber and closing room exists.

Particularly useful is also the independent control of the two Nozzle needles of the Vario nozzle with an integrated into the fuel injector Combine pressure booster device.

drawing

Embodiments of the invention are illustrated in the drawing and in the explained in more detail below description.

Figur 1

eine Prinzipdarstellung einer erfindungsgemäßen Kraftstoffeinspritzeinrichtung gemäss einem ersten Ausführungsbeispiel,

Figur 2

eine Prinzipdarstellung einer erfindungsgemäßen Kraftstoffeinspritzeinrichtung gemäss einem zweiten Ausführungsbeispiel,

Figur 3

eine Prinzipdarstellung einer erfindungsgemäßen Kraftstoffeinspritzeinrichtung gemäss einem dritten Ausführungsbeispiel und

Figur 4

eine Prinzipdarstellung einer erfindungsgemäßen Kraftstoffeinspritzeinrichtung gemäss einem vierten Ausführungsbeispiel.

Show it:

FIG. 1

1 is a schematic representation of a fuel injection device according to the invention according to a first embodiment,

FIG. 2

a schematic diagram of a fuel injection device according to the invention according to a second embodiment,

FIG. 3

a schematic diagram of a fuel injection device according to the invention according to a third embodiment and

FIG. 4

a schematic diagram of a fuel injection device according to the invention according to a fourth embodiment.

embodiments

The fuel injectors illustrated in FIGS. 1 to 4 include one Fuel injector 1 and a high-pressure accumulator 2 (common rail), wherein the Fuel injector 1 via the high-pressure accumulator 2 with high pressure standing Fuel is supplied. The fuel injector 1 includes a pressure intensifier 5, a Servo valve 6 and an injection valve 9, via which in a not shown Combustion chamber of an internal combustion engine at the combustion chamber end of the fuel injected becomes. The servo valve 6, which is designed for example as a 3/2-way valve, has a first switching valve 7 and a controlled by this control valve 8. The Switching valve 7 is in the present embodiment of an electromagnet actuated. However, the electromagnet can also be replaced by a piezo actuator. As further embodiments for the servo valve 6 can also be a directly controlled Solenoid valve or a pressure compensated 3/2-way valve with piezo actuator used become.

The injection valve 9 has a Variodüse with an outer nozzle needle 11 and an inner nozzle needle 12. The nozzle needles 11, 12 are coaxial with each other guided and independently longitudinally displaceable. The vario nozzle has two Hole rows of injectors with outer injectors 13 and inner Injection nozzles 14, wherein the outer nozzle needle 11 to the outer injection nozzles 13th and the inner nozzle needle 12 are associated with the inner injection nozzles 14. The outer one Nozzle needle 11 has a pressure shoulder 16 within a nozzle chamber 15. On the combustion chamber side, the inner nozzle needle 12 with a further pressure shoulder 18th executed, which is the internal injection nozzles 14 upstream. In the combustion chamber opposite side of the outer nozzle needle 11 is associated with a closing space 20, in which the outer nozzle needle 11 with a closing space side acting in the closing direction Pressure surface 21 is located. The outer nozzle needle 11 is further a damping piston 41st associated, which is guided in a subsequent to the closing space 20 bore 42 is.

The damping piston 41 is biased by a closing spring 44 in the closing space 20 and has within the closing space 20 a nozzle needle-side end face 47, the the closing space side pressure surface 21 of the outer nozzle needle 11 is present. Between the Nozzle-side end face 47 of the damping piston 41 and the pressure surface 21 of the outer nozzle needle 11 is a parting line 45 is formed. The damping piston 41 also shows me a trained as an annular end surface pressure surface 49 in a damping chamber 50.

The inner nozzle needle 12 is connected to a control piston 43, in the form of a Piston rod is guided through the damping piston 41 therethrough. Between the Control piston 43 and the inner cylinder wall of the damping piston 41, is in the Embodiments of Figures 1 to 3, a flow channel 46 in the form of a Annular gap performed that leads from the damping chamber 50 to the parting line 45. The as Piston rod executed control piston 43 for the inner nozzle needle 12 passes through the Control chamber 50 through and has a control room side pressure surface 52 in one Control chamber 53. The inner nozzle needle 12 also has at the transition to Control piston 43 in the closing direction of the inner nozzle needle 12 facing step 22nd as supporting the closing operation of the inner nozzle needle Pressure shoulder acts.

From the schematically indicated high pressure accumulator 2 fuel passes through combined check / throttle valve 23 and a rail pressure line 24 in a Pressure chamber 25 of the booster 5. The pressure booster 5 includes in addition to the mentioned pressure chamber 25 a back space 26 and a high-pressure chamber 27. Within of the pressure intensifier 5, an axially displaceable stepped piston 30 is received, the a first partial piston 31 which, in comparison to a second partial piston 32 with a guide permitting larger diameter is formed. Of the Stepped piston 30 can consist of two separate components as well as one Be manufactured component. The stepped piston 30 also has a in the pressure chamber 25th protruding piston rod 33 with spring holder 34 for a closing spring 35. Of the second partial piston 32 of the stepped piston 30 limited with its end face the High-pressure chamber 27 to which a high-pressure line 36 is connected, the Nozzle chamber 15 of the injection valve 9 with fuel under very high pressure applied. From the rear space 26 of the booster 5 branches a first control line 28 and a second control line 29 from, wherein the first control line 28 to the Control valve 8 and the second control line via a closing space throttle 54 to the Closing chamber 20 of the injection valve 9 is connected. The closing space 20 is above a Check valve 55 also connected to the high pressure line 36. The control room 50 is connected via an outlet throttle 56 to the second line 29. Another Line 57 leads from the pressure chamber 25 in the control chamber 53, wherein in the line 57 a another throttle 58 is connected.

The control valve 8 is designed with a control piston 81 having a pressure surface a control valve-side control chamber 82 limited. In the control piston 81 is a Connecting channel 83 incorporated, the pressure chamber 25 via a throttle 84 with the Control room 82 connects. On the control piston 81 is a sealing seat 78 and a control edge 85 trained. The sealing seat 78 separates a low-pressure space 86 which is connected to a Return line 87 is connected, from a valve chamber 89. The return line 87 is connected to a low pressure return system 88. The control edge 86 separates the valve chamber 89 into which the line 28 opens, from the pressure chamber 25th

The switching valve 7 has an actuator-side control chamber 73 and an actuator side Low pressure space 75, wherein the control chamber 73 via a control line 76 with the control valve-side control chamber 82 and the low-pressure chamber 75 via another Return line 77 is connected to the low pressure / return system 88.

The fuel injector 1 further has a second switching valve 90, the one Control piston 91 having an actuator-side pressure chamber 92 of a Low pressure space 93 separates. From the pressure chamber 92, a control line 94 leads to Control chamber 53. At the low pressure chamber 93 is another return line 95th connected, which also leads into the low pressure / reflux system 88.

For the second switching valve 90 is also an arrangement at the top of the Fuel injector 1 conceivable. As a simplification is also an arrangement outside the fuel injector 1 possible, in which case the switching valve 90 centrally for all Cylinder an internal combustion engine can act. The application is here by the number of cylinders and the injections required, because after each Activation of the inner nozzle needle 12 is a break in all cylinders in order to avoid uncontrolled opening of the inner injection nozzles 14. A Such embodiment has significant space advantages at the fuel injector. 1 However, an additional hydraulic connection for the fuel injector 1 be provided. An external switching valve 90 must also have a sufficient Have dynamics to realize activation in a break in the spray. When Operating pressure is the rail pressure or a defined low pressure of, for example, 5 to 50 bar conceivable. Accordingly, a corresponding design of the pressure surface 52nd required in the control room 53. When using pressures of the order of magnitude of about 5 bar, the second switching valve 90 can be executed as a low-pressure switching valve. at all variants are the injection nozzles 13, 14 and the damping chamber 50 pressurized. To prevent leakage through the guides between the inner and the To avoid outer nozzle needle 11, 12, the measures known per se are too choose how double needle seat on the outer nozzle needle 11 or an additional Leakage removal between the nozzle needles 11, 12th

In a ground state, in which the injection nozzles 13, 14 from the outer and the inner nozzle needle 11, 12 are closed, all pressure chambers in the pressure booster. 5 subjected to rail or system pressure. The stepped piston 30 is here pressure-balanced. In this state, the pressure booster 5 is deactivated, the Stepped piston 30 is returned via the return spring 35 in its initial position and the pressure chamber 25 was filled via the check valve 23. In the ground state lies in the closing space 20, in the damping chamber 50 and in the control chamber 53 rail or System pressure on. Due to the area ratios of the end faces 49, 52 and the the nozzle needles 11, 12 formed pressure shoulders 16, 18 acts a hydraulic Closing force on the inner and outer nozzle needle 11, 12. The on the Damping piston 41 and thus acting on the outer nozzle needle 11 compression spring 44th also supports the closing process. As a result, the rail pressure constantly in Nozzle space 15 pending without the outer nozzle needle 11 opens.

To effect an opening of the outer nozzle needle 11, the pressure in the nozzle chamber 12 rise above the rail pressure, which is achieved by connecting the booster 5 becomes. This is, as shown in Figures 1 to 4, by a pressure relief of Rear space 26 initiated by activation of the electromagnet of the Switching valve 7, a pressure relief of the control valve-side control chamber 82 via the Actuator-side control chamber 73 and the actuator-side low-pressure space 75 to Low pressure / return system takes place. Thereby, the control piston 81 of the Control valve 8 is raised, whereby the control edge 85 the connection to the pressure chamber 25 closes. At the same time, a connection between the valve chamber 89 and the Low pressure space 86 released, as shown in Figures 1-4. This is the result Rear chamber 26 connected via line 28 to the low pressure / return system 88. The pressure in the back space 26 drops, whereby the pressure booster 5 is activated and while the stepped piston 30 with the partial piston 32 in the high-pressure chamber 27th compressed fuel. The compressed fuel is over the High-pressure line 36 is directed into the nozzle chamber 15. At the same time, the closing space 20 Relieved via the closing space throttle 54, so that by the action of high pressure on the pressure shoulder 16, the outer nozzle needle 11, as shown, is raised, whereby injection via the outer injection nozzles 13 begins. By doing this resulting upward movement of the outer nozzle needle 11 is through the end face 49th of the damping piston 51, a volume in the damping chamber 50 is compressed, wherein the compressed fuel from the damping chamber 50 via the outlet throttle 56 in the discharged line 29 can flow. The outlet throttle 56 has a larger Throttle action as the closing space throttle 54, so that it is the damping effect of Damping piston 41 may come in the damping chamber 50. By a suitable Dimensioning of the outlet throttle 54 and the closing space throttle 54 can be Opening speed of the outer nozzle needle 11 and thus the injection rate determine.

From the engine control, not shown, is now the other switching valve 90th controlled and the control chamber 53 via the actuator-side pressure chamber 92 and the Low pressure space 93 connected to the low pressure / return system 88. Due to the in the embodiment of Figure 1 in the line 57 connected choke 58th less fuel flows out of the pressure chamber 25, so that the control chamber 53 is depressurized and thereby the inner nozzle needle 12, the inner injection nozzles 14th releases. By the separate control of the first switching valve 7 and the second Switching valve 90, it is also possible through an implementation of a corresponding control either only the outer nozzle needle 11 or one after the other the outer nozzle needle 11 and the inner nozzle needle 12 or both at the same time Open nozzle needles 11, 12, thereby realizing different injection rates. This allows a flexible injection with different pressures and Injection angles and thus an optimal adaptation to different Implement combustion concepts of the internal combustion engine.

In the embodiments illustrated in the other figures are the same Components designated by the same reference numerals. In the illustrated in Figure 2 Embodiment, the control chamber 53 for the inner nozzle needle 12 is not with the Pressure chamber 25 of the booster 5 is connected, but via a check valve 97th connected to the control line 29. The check valve 97 acts against the Emptying direction from the control chamber 53, so that the check valve 97th only a filling of the control chamber 53 can be made from the control line 29. The Opening of the inner nozzle needle 12 takes place by driving the second Switching valve 90, as described in connection with Figure 1.

The embodiment in Figure 3 shows a fuel injector 1 with a Injection valve 10, which has a Variodüse, wherein the inner injection nozzles 14 of the Fuel is supplied via a separate fuel supply 101. The separate Fuel supply is, for example, as a gap or as an annular gap between the inner nozzle needle 12 and the outer nozzle needle 11 realized. In addition, one is Connecting passage 102, for example, radially guided by the outer nozzle needle 11, the connects the nozzle chamber 15 with the fuel supply 101, so that at the combustion chamber-side pressure shoulder 18 of the inner nozzle needle 12 also in the Nozzle chamber 15 prevailing injection pressure is applied. This version becomes one known leak oil-free Variodüse realized in the on the outer nozzle needle 11 a not shown double seat is designed as a combustion chamber-side sealing seat. The Activation of the outer nozzle needle 11 is here as well - as in the Embodiments 1 and 2 described - by means of the first switching valve 7 under Intermediate circuit of the pressure booster 5 initiated. Again, this is Open the outer nozzle needle 11 is damped by means of the damping piston 41. In which Embodiment in Figure 3 is the control chamber 53 via a hydraulic connection 104 connected to a throttle 105 with the high pressure line 36. To fill the Control chamber 52 is additionally a connection via the check valve 55 to Closing space 20 is formed. As a result, in the pressure-relieved state, the control chamber 53 coupled via the closing space 20 to the rail pressure. By additionally activating the second switching valve 90, the row of holes of the inner injection nozzles 14 can be arbitrary be switched on and off. This embodiment allows over the separate fuel supply for the inner injectors 14 a stroke-controlled Injection without interposition of the pressure booster 5 with rail pressure can be done by a separate control of the inner nozzle needle 12. This allows small spray clearances and good multiple injection due to lower Pressure oscillations. In combination with a low inclination of the holes for the Injectors 14 can be an early injection with a homogeneous combustion to reach.

The embodiment according to FIG. 4 also uses an injection valve 100 a leak-free Vario nozzle. As in the embodiment of Figure 3 is for the inner injectors 14 a separate fuel supply 101 between the inner and the outer nozzle needle 11, 12 and via a connecting channel 102 available. In this embodiment, however, the control chamber 53 is not with the High-pressure line 36 connected, but - as in the embodiments according to Figure 1 and 2 - via the line 57 and the throttle 58 to the pressure chamber 25 of Pressure booster 5 connected. As a result, the control chamber 53 to the in Pressure chamber 25 adjacent rail pressure coupled. In contrast to Embodiment of the leak-less Variodüse in Figure 3 is also no hydraulic connection between the damping chamber 50 and the closing space 20th available. In this embodiment, the closing of the outer nozzle needle 11 supported only by the pressure surface 21 supported by the compression spring 44. The Control of the inner nozzle needle 11 also takes place here by means of the second Switching valve 90. This embodiment allows for an adapted pressure surface 52 the Use of an injection valve with low requirements for high pressure tightness and strength.

It is also conceivable that the control described in Figures 1 to 4 Vario nozzles 10, 100, also without pressure intensifier 5.

LIST OF REFERENCE NUMBERS

1

fuel injector

2

High-pressure fuel source

5

Pressure booster device

6

servo valve

7

switching valve

8th

control valve

9

Fuel injection valve

10

Fuel injection valve

11

outer nozzle needle

12

inner nozzle needle

13

outer injectors

14

inner injectors

15

nozzle chamber

16

pressure shoulder

18

another pressure shoulder

20

closing chamber

21

closing space-side printing area

22

step

23

Non-return / throttle valve

24

Rail pressure line

25

pressure chamber

26

backcourt

27

High-pressure chamber

28

first control line

29

second control line

30

stepped piston

31

first part piston

32

second partial piston

33

piston rod

34

penholder

35

Return spring

36

High-pressure line

41

damping piston

42

drilling

43

spool

44

compression spring

45

parting line

46

flow channel

47

nozzle needle-side end face

49

annular end face

50

control room

52

print area

53

nozzle needle side control chamber

54

Closing chamber throttle

55

check valve

56

outlet throttle

57

management

58

another throttle

73

Actuator-side control room

75

actuator-side low pressure space

76

further control line

77

further return line

78

sealing edge

81

spool

82

control room

83

connecting line

84

throttle

85

control edge

86

Low-pressure chamber

87

Return line

88

Low-pressure / return system

89

valve chamber

90

second switching valve

91

spool

92

Actuator-side pressure chamber

93

Low-pressure chamber

94

control line

95

further return line

100

Injector

101

Fuel supply

102

connecting channel

104

connecting line

105

throttle

Claims (9)

Fuel injection device for internal combustion engines with a fuel injector can be supplied from a high-pressure fuel injector having an injection valve with a combustion chamber zukunftsenden injectors, wherein the injectors an inner nozzle needle and coaxially arranged an outer nozzle needle is assigned, the controllably enable injection cross sections at the injection nozzles or close, wherein the outer nozzle needle a damping piston and the inner nozzle needle is associated with a control piston, which are guided into each other movable relative to each other, wherein the damping piston of the outer nozzle needle acts on a damping chamber and the control piston of the inner nozzle needle to a control chamber, wherein a pressure surface of the outer nozzle needle associated with a closing space is, and wherein a first switching valve is provided, that controls the outer nozzle needle by verbun the closing space with a low pressure / return system is the, characterized in that for driving the inner nozzle needle (12), a further switching valve (90) is provided, with which the control chamber (53) for the inner nozzle needle (12) with the low pressure / return system (88) is connectable. Fuel injection device according to claim 1, characterized in that the control chamber (53) for filling via a throttle (58) is connected to a rail pressure line. Injection device according to claim 1, characterized in that the control chamber (53) for filling via a check valve (97) to a low pressure / return system (88) connectable control line (29) is connected, wherein the check valve (97), the emptying of the Control chamber (53) in the control line (29) locks. Fuel injection device according to claim 1, characterized in that for the inner injection nozzles (14) a separate fuel supply line (101) is provided which leads to a the injection nozzles (14) upstream pressure shoulder (18) on the inner nozzle needle (12). Fuel injection device according to claim 4, characterized in that the control chamber (53) for the inner nozzle needle (12) via a throttle (58) is connected to a rail pressure line. Fuel injection device according to claim 4, characterized in that the control chamber (53) for the inner nozzle needle (12) via a throttle (105) to a high pressure line (36) of a pressure booster device (5) is connected. Fuel injection device according to claim 4, 5 or 6, characterized in that the fuel supply line (101) as a gap between the inner nozzle needle (12) and the outer nozzle needle (11) is formed and via a connecting channel (102) in a nozzle chamber (15). leads, which a pressure shoulder (16) of the outer nozzle needle (11) is exposed. Fuel injection device according to one of the preceding claims, characterized in that the outer nozzle needle (11) with a pressure surface (21) associated with the closing space (20) and that the pressure surface (21) in a between the damping piston (41) and the outer nozzle needle ( 11) formed parting line (45) is arranged. Fuel injection device according to one of the preceding claims, characterized in that a pressure booster device (5) with a back space (26) is provided, which is connectable to the low pressure / return system (88), and that the damping chamber (50) of the outer nozzle needle (11 ) via the outlet throttle (56) with the rear space (26) is in communication.

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