EP1491757A1 - Fuel injection system for internal combustion engine - Google Patents

Abstract

The device (1) has a fuel injection valve (10) connected to a high-pressure line and a control valve (30) with a valve body (31) with a piston longitudinally movable in a bore. In a first valve position the piston separates a valve chamber from a return or leakage oil system. In a second valve positron the valve pressure chamber is relieved of pressure to the return pressure and actuation of the fuel injection valve is initiated. The piston has at least two individual, longitudinally movable control pistons (71,72), each with a control edge (73,74) for both valve settings.

Description

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

State of the art

A fuel injection device for internal combustion engines of this type is known from EP 1 176 306 A2, in which a servo control circuit with a control valve is provided for controlling a fuel injection valve, said control circuit having a control piston which is longitudinally displaceable in a bore and which controls the pressure control of the fuel injection valve by a solenoid valve as a switching valve realized. The control valve has a first valve seat that delimits a first pressure chamber and a second valve seat designed as a slide seal that delimits a second pressure chamber. The fuel injection device is designed without a pressure booster interposed between the pressure accumulator and the fuel injection valve.

A fuel injection device for internal combustion engines with a pressure booster is known, for example, from DE 43 11 627 A1, in which an integrated pressure booster piston increases or increases the fuel injection pressure beyond the value provided by the pressure accumulator (common rail system) by filling or emptying a rear space allows.

Advantages of the invention

The fuel injection device according to the invention with the characterizing features of claim 1 has the advantage that lower demands on the manufacturing tolerances are necessary when designing the control edges of the control valve assigned to the control piston. Due to the at least two-part design of the control piston, the housing of the control valve can also be made in several parts. As a result, the manufacturing tolerances for the individual sealing seats of the control edges can be compensated for by means of the multi-part housing, which simplifies the manufacture and adjustment of the servo valve or the control valve. A multi-part design of the valve housing also allows good accessibility when machining the sealing seats, which also results in simple and inexpensive manufacture.

The measures listed in the subclaims enable advantageous developments and improvements of the fuel injection device specified in the main claim.

The control valve with the two individual, longitudinally displaceable partial pistons can be used particularly expediently for controlling fuel injection devices with a pressure booster. This makes it possible to alternately connect a differential pressure chamber of the pressure booster from the two control edges to a high-pressure chamber connected to the high-pressure line or to a leakage oil system connected to a return line. Due to the at least two-part design of the control piston, it is also possible to implement a 3/2-seat seat valve. As a result, wear on the otherwise used slide seals with slight overlaps for the usual second control edge can be avoided.
Alternative designs of valve seats are possible for the execution of the control edges, which are explained in more detail in the later description.

A particularly advantageous development of the control valve consists in actuating the second valve piston only by the hydraulic flow and pressure forces that occur. As a result, the spring force required to move the second control piston can be dispensed with. This spring requires additional installation space and has the effect that the control valve requires an additional closing force with a further closing spring on the first control piston when the pressureless system is switched off. This prevents problems from occurring when the engine is started, otherwise it will not enough system pressure is built up. Consequently, the additional spring for the first control piston can also be dispensed with, as a result of which the installation space can also be reduced here. The enlargement of the control space resulting from the increased installation space due to the additional spring also leads to oscillation-related switching operations, so that this disadvantage of a smaller control space can also be eliminated. The omission of the spring associated with the first control piston and the resultant further waiver of the spring associated with the second control piston results in a space-saving and inexpensive design of the control valve. In addition, this eliminates the necessary adjustment processes for balancing the spring forces to open and close the two pistons.

According to a first embodiment, the hydraulic flow and pressure forces can be exploited by means of a defined throttle bore which leads through the second control piston. In a second embodiment, a recess is provided in the guide region of the second control piston and a throttle is connected upstream of this recess, which is implemented by a defined opening stroke of the control edge of the second control piston.

drawing

Embodiments of the invention are shown in the drawing and explained in more detail in the following description.

Show it:

Figure 1

a schematic structure of an entire fuel injection device,

Figure 2

2 shows a schematic sectional illustration through a control valve according to a first exemplary embodiment,

Figure 3

2 shows a schematic sectional illustration through a control valve according to a second exemplary embodiment,

Figure 4

2 shows a schematic sectional illustration through a control valve according to a third exemplary embodiment,

Figure 5

3 shows a sectional illustration through a concrete embodiment of a servo valve according to the embodiment of the control valve shown in FIG. 2,

Figure 6

a schematic structure of a fuel injection device with a control valve according to a fourth embodiment and

Figure 7

the fuel injection device according to Figure 6 with a control valve according to a fifth embodiment.

FIG. 1 shows a fuel injection device with a fuel injector 1, which is connected to a high-pressure fuel source 5 via a fuel line 3. The high-pressure fuel source 5 comprises a number of elements, not shown, such as a fuel tank, a high-pressure pump and a high-pressure line, for example a common rail system known per se, the pump providing a fuel pressure of up to 1600 bar via the high-pressure line. The fuel injector 1 shown has a fuel injection valve 10 which projects with injection openings 11 in a combustion chamber 7 of an internal combustion engine. The fuel injection valve 10 has a closing piston 12 with a pressure shoulder 13 which is surrounded by a pressure chamber 14. The closing piston 12 is guided at an end facing away from the combustion chamber 7 in a guide region 15, which is followed by a closing pressure chamber 16. The closing piston 12 is biased in the closing direction by means of a closing spring 17.

The fuel injector 1 according to FIG. 1 has a pressure booster device 20 for pressure boosting. The pressure booster device 20 has a booster piston 21 which is resiliently mounted by means of a return spring 18 and is, for example, of two parts and has a first part piston 22 and a second part piston 23 with a smaller diameter. The partial pistons 22, 23 are each assigned a corresponding cylinder 24, graduated in diameter, so that the smaller diameter piston 23 in the cylinder 24 separates a high-pressure chamber 25 from a rear chamber 26 in a liquid-tight manner. The first partial piston 22, which is larger in diameter and is guided in the cylinder section of the cylinder 24 with the larger diameter, also separates the rear space 26 from a pressure translation space 27 in a liquid-tight manner.

Furthermore, the fuel injector 1 has an electrohydraulic servo valve 90, which comprises a hydraulic control valve 30 and an electrically controllable switching valve 40, the actuation being carried out by an electromagnetic or piezoelectric actuator 41. The switching valve 40 has an actuator piston 42 connected to the actuator 41, which is guided in an actuator bore 43. With an actuator-side sealing seat 44, the actuator piston 42 separates an actuator-side leakage space 45 from an actuator-side annular space 46 in a liquid-tight manner.

The control valve 30 has a valve body 31 with a stepped bore 32 which opens into a control chamber 33 and at the opposite end into a pressure chamber 34. A valve chamber 35 and a connecting space 36 are formed by the stepped bore 32 between the control chamber 33 and the pressure chamber 34. A first control piston 71 and a second control piston 72 are guided axially one behind the other in the stepped bore 32 of the control valve 30. A first control edge 73 is assigned to the first control piston 71 in the stepped bore 32 and a second control edge 74 is assigned to the second control piston 72. The first control piston 71 is biased with a first spring 75 and the second control piston 72 with a second spring 76 in the closing direction of the respective control edge. The two control pistons 71, 72 touch with their facing end faces at a contact point 77 which lies between the two control edges 73 and 74. A first pressure surface 78 is assigned to the first control piston 71 and a second pressure surface 79 is assigned to the second control piston 72. The pressure surface 78 of the first control piston 71 is larger than the pressure surface 79 of the second control piston 72. In addition, a stop 89 can be provided for the second control piston. By forming two separate control pistons 71, 72, I can divide the valve body 31 into several housing sections, which then also contain the individual control edges 73, 74. This allows manufacturing tolerances for the control edges 73, 74 to be compensated. In addition, the multi-part design of the valve housing allows good accessibility for machining the control edges 73, 74. When the second control edge 74 is open, the connection space 36 is connected to the pressure space 34 via a connection channel 37 incorporated in the outer surface of the second control piston 72.

Pressure lines, which are integrated, for example, into the fuel injector 1, are used to connect the individual components of the injection valve 10, pressure booster device 20, control valve 30 and switching valve 40. The Pressure chamber 14 of fuel injection valve 10 is connected to high pressure chamber 25 of pressure booster device 20 by a first pressure line 51. A second pressure line 52 leads from the closing pressure chamber 16 of the injection valve 10 to the rear chamber 26 of the pressure booster device 20. In addition, there is a connecting line 53 between the closing pressure chamber 16 and the high pressure chamber 25, into which a check valve 54 is connected. The hydraulic pressure of the high-pressure fuel source 5 is conducted via the high-pressure line 3 into the pressure translation space 27 of the pressure translation device 20. The pressure translation space 27 is connected to the pressure space 34 of the control valve 20, for example, via a connection bore 55. In addition, a further connecting line 57 provided with an inlet throttle 56 is placed between the pressure translation space 27 and the control space 33 of the control valve 30. A back space line 58 connects the back space 26 of the pressure booster device 20 to the connection space 36 of the control valve 30. From the valve chamber 35 of the control valve 30, a first return line 61 leads back to a fuel tank (also not shown) via a leak oil system (not shown in the drawing). The control chamber 33 of the control valve 30 is connected to the actuator-side annular chamber 46 of the switching valve 40 by means of a control line 59 via an outlet throttle 64. Finally, a second return line 62 leads out of the actuator-side leak space 45 of the switching valve 40 into the leak oil or return system. The return lines 61, 62 can, however, also be designed as a common return system.

The mode of operation of the fuel injector 1 is shown as follows: At the beginning of the injection process, due to the constant pressure in the high-pressure accumulator 5, the pressure in the pressure translation chamber 27 is also in the rear chamber line 58 and in the rear chamber 26 and via the second pressure line 52 and the connecting line 53 in the high-pressure chamber 25 and from there via the first pressure line 51 in the pressure chamber 14. The actuator 41 of the switching valve 40, which in the present exemplary embodiment is a solenoid valve, is energized such that the actuator piston 42 closes the control line 59 connected to the control chamber 33 of the control valve 30 against the actuator-side leak chamber 45 connected to the second return line 62 As a result, the same pressure prevails in the pressure chamber 34 as in the control chamber 33 which is connected to the pressure translation chamber 27 via the further connecting line 57. The high pressure acting on the first pressure surface 78 increases the pressure first control piston 31 pressed against the sealing seat of the first control edge 732. As a result, the valve chamber 35 and thus the first return line 61 are decoupled from the high pressure. The injection valve 10 is closed.

The opening stroke movement of the closing piston 12 of the injection valve 10 is initiated by lifting the actuator piston 42 from the actuator-side sealing seat 44 due to a corresponding energization of the actuator 41, so that the control chamber 33 is connected to the actuator-side annular chamber 46 and the actuator-side leak chamber 55. The flow resistors of the inlet throttle 56 and the outlet throttle 64 are dimensioned such that the flow resistance through the inlet throttle 56 is greater than the flow resistance of the outlet throttle 64, as a result of which the fuel flows out of the control chamber 33 into the actuator-side leakage chamber 45 faster than it flows out of the pressure translation chamber 27 can flow the connecting line 57. As a result, the pressure in the control chamber 33 drops and the first control piston 71 lifts off from the sealing seat of the first control edge 73. At the same time, the pressure of the high-pressure fuel source 5 acts on the second pressure surface 79 of the second control piston 72 via the pressure translation space 27 and the connection bore 55, so that the second control edge 74 closes the pressure space 34 toward the connection space 36. As a result, the rear space 26 is connected to the connecting space 36 and the valve chamber 32 via the return line 58. Accordingly, the high pressure prevailing in the rear space 26 of the pressure booster device 20 is released via the first return line 61 and the pressure in the rear space 26 drops. This activates the pressure transmission device 20 and the second partial piston 23, which has a smaller effective area, compresses the fuel in the high-pressure chamber 25, so that in the pressure chamber 14 connected to the high-pressure chamber 25, the pressure force acting on the pressure shoulder 13 in the opening direction increases and the closing piston 12 the injection openings 11 releases. As long as the rear space 26 is relieved of pressure, the pressure booster device 20 remains activated and compresses the fuel in the high-pressure space 25. To end the injection process, the switching valve 40 is returned to its starting position. This separates the rear space 26 from the first return line 61 and connects it again to the supply pressure of the high-pressure fuel source 5. As a result, the pressure in the high-pressure space 25 drops to system pressure, so that system pressure is again present in the pressure space 14. The resetting of the closing piston 12 is supported by the closing spring 17 arranged in the closing pressure chamber 16 and also by the second one Pressure line 52 applied system pressure realized. The direction of action of the check valve 54 in the connecting line 53 is such that the high pressure generated by the second partial piston 23 cannot be conducted into the closing pressure chamber 16 or the rear chamber 26. After the pressure equalization, the pressure booster piston 21 is returned to its initial position by the return spring 18, the high-pressure chamber 25 being filled from the high-pressure fuel source 5 via the check valve 54 and the connecting line 53. The pressure booster piston 21 can also be made in one piece. In addition, the return spring 18 can also be arranged in the pressure booster chamber 27. The control valve 30 according to the invention can, however, also be used in injection devices which do not require a pressure intensifying device for pressure amplification.

Various embodiments for realizing the control valve 30, in particular the second control piston 72, can be seen in FIGS. 2, 3 and 4. In FIG. 2, the second control piston 72 is designed as a slide piston 80 with a control edge 81. The control edge 81 acts as a sealing edge when immersed in the bore 32. In the embodiment according to FIG. 3, the second control piston 72 is formed by a plate valve 82 with a sealing surface 83 facing the bore 32, which achieves the sealing effect with the annular surface surrounding the bore 32. For the interaction with the slide valve 82, a piston rod 84 is provided through the bore 32 and is connected either to the first control piston 71 or to the slide valve 82. In the embodiment according to FIG. 4, the second control piston 72 is formed by a sealing ball 85, an intermediate piston rod 88, which can be connected to the first control piston 71, acting on the sealing ball 85. The sealing ball 85 presses by means of a compression spring 86 against a conical seat 87 formed on the housing, so that the second control edge 74 is formed as a sealing seat on the contact surface. In the first control piston 71 of the exemplary embodiments in FIGS. 2, 3 and 4, the first control edge 73 is in each case designed as a sealing seat.

A detailed design of a compact servo valve 90 with the control valve 30 and the switching valve 40 can be seen in FIG. 5. The first sealing edge 73 is designed as a sealing seat and the second sealing edge 74 as a slide seal. The valve body 31 has a lower housing section 91 and an upper housing section 92. In the lower housing section 91 is a first one Flange connection 93 for the first return line 61 and a second flange connection 94 for the second return line 62 are formed. The lower housing section 91 is also designed with a cavity 95, in which there is a cylinder body 96, in which the stepped bore 32 is formed. To extend the stepped bore 32, a further bore 97 is made in the lower housing section 91, which forms the pressure chamber 34 and into which the connecting bore 55 leads. A first annular space 10 and a second annular space 102 are formed axially offset one above the other in the stepped bore 32. The first annular space 101 forms the connection space 36 into which the rear space line 58 opens. The second annular space 102 has the function of the valve chamber 35, which leads via a first oblique bore 103 with a further annular space 123 formed between the cavity 95 and the cylinder body 96 and from there to the flange 93 in the first return line 61. The first control piston 71 with the first control edge 73 as a sealing seat and the second control piston 72 with the second control edge 74 as a slide seal are located within the stepped bore 32. The second control piston 72 has a flattened area 104, which realizes the connecting channel 37 and via which, in the open position of the sealing edge 74, a connection is made to the further bore 97 and the first annular gap 101. A further cylinder body 105 is located above the cylinder body 96, which has a recess 106 following the stepped bore 32. The depression 106 serves to receive the first spring 75. Between the first pressure surface 78 of the first control piston 71 and the cylinder body 105 or the depression 106 there is a cavity 107 which forms the control chamber 33. A longitudinal bore 108 is also passed through the cylinder body 96 and the disk-shaped cylinder body 105, which via a first cross connection 109 with the further bore 97 or the pressure chamber 34 and via a second cross connection 110 and a throttle bore 111 machined into the cylinder body 105 with the cavity 107 or the control room 33 is connected. The throttle bore 111 forms the inlet throttle 56.

For the compact design of the servo valve 90, the switching valve 40 is seated directly on the disk-shaped cylinder body 105 with a base body 112. There is a further stepped bore 113 in the base body 112, in which the actuator piston 42 is guided. The actuator piston 42 has an end face 114 on which the actuator 41 engages. The actuator piston 42 forms the actuator-side sealing seat 44 with a step in the step bore 113. Below the actuator-side sealing seat 44 is from the stepped bore 113 and the end face of the adjacent disc-shaped Cylinder body 105 has a further cavity 115, which forms the actuator-side leakage space 45. Above the sealing seat 44 on the actuator side there is an annular space 116 within the stepped bore 113 which, according to FIG. 1, forms the annular space 46 on the actuator side. A second oblique bore 117 and a third oblique bore 118 with a further throttle bore 119 lead from the annular gap 116 into the cavity 107 and the control chamber 33, respectively. The further throttle bore 119 forms the outlet throttle 64. A transverse channel 120 leads from the cavity 115 into a further annular gap 121, which leads to the second flange 94 and thus to the second return line 62 via different line guides 122. The mode of operation of the servo valve 90 described in FIG. 5 is the same as that explained in connection with the description of the entire fuel injector 1 according to FIG. 1.

In the exemplary embodiments described in FIGS. 6 and 7, the same components of the fuel injector 1 are provided with the same reference symbols. A difference that is insignificant for the present invention from the fuel injector according to FIG. 1 consists in the routing of the connecting line 53, which in the exemplary embodiments according to FIGS. 6 and 7 opens directly into the closing pressure chamber 16. Furthermore, in contrast to the fuel injector in FIG. 1, the pressure transmission device 20 has a different arrangement of the return spring 18. The return spring 18 is arranged in the exemplary embodiments in FIGS. 6 and 7 in the pressure translation space 27 and, in order to generate the necessary return movement, is tensioned between a spring holder 125 connected to the translation piston 21 and a ring element 126 fastened to the injector housing. In addition, in the exemplary embodiments in FIGS. 6 and 7, the closing pressure chamber 16 is assigned a damping piston 127 known per se.

The special feature of the exemplary embodiments in FIGS. 6 and 7 in comparison to the exemplary embodiments in FIGS. 1 to 5 is that the control valve 30 for the first control piston 71 and the second control piston 72 has no return springs. For this purpose, the second control piston 72 is designed with a hydraulic throttle connection 130, which establishes a connection between the pressure chamber 34 and the connection chamber 36.

In the exemplary embodiment in FIG. 6, the throttle connection 130 is realized through a bore 131 with a defined hydraulic throttle 132. The bore 131 can but also be designed as a throttle 132. The bore 131 with the throttle 132 leads from an annular space 133 formed on the second control piston 72, which is connected to the pressure space 34 when the control edge 74 is open, into the connecting space 36.

In the embodiment according to FIG. 7, the hydraulic throttle connection 130 is realized by the connecting channel 37 formed on the lateral surface of the second control piston 72, to which a throttle point 134 is assigned. However, it is also conceivable to guide the connecting channel 37 axially through the second control piston 72. The throttle point 134 is located on the annular space 133 on the second control edge 74, the hydraulic throttle being formed by an opening stroke of the second control edge 74 denoted by h.

In the idle state, the control valve 30 according to FIG. 6 is in the first, closed switching position shown. The control pistons 71 and 72 are arranged and designed such that the first control piston 71 forms a seal on the first control edge 73 due to its pressure surfaces facing the control chamber 33, the valve chamber 35 and the connection chamber 36. To form the second sealing edge 74, the second control piston 72 has pressure surfaces to the pressure chamber 34 and to the connection chamber 36. The contact point between the first control piston 71 and the second control piston 72 is, as in the exemplary embodiment according to FIG. 1, in the region between the control edges 73 and 74. In the exemplary embodiments according to FIGS. 6 and 7, the first control edge 73 is a sealing seat and the second control edge 74 designed as a slide seal. However, it is also conceivable to use the control edges according to FIGS. 2 to 4 described in connection with the exemplary embodiment of FIG. 1 also in the exemplary embodiments according to FIGS. 6 and 7.

To activate the fuel injector 1 in FIGS. 6 and 7, the switching valve 40 is first activated and the actuator piston 42 opens. As a result, the pressure in the control chamber 33 drops. The control piston 71 moves upward and thereby opens the seal of the control edge 73 and thus establishes a connection from the connecting space 36 to the return line 61. As a result, the pressure in the connection space 36 drops and fuel flows from the pressure space 34 via the throttle connection 130 to the connection space 36. The pressure drop at the throttle 132 causes a hydraulic force on the second control piston 72 in the direction of the first control piston 71 generated. As a result, the second control piston 72 moves upward together with the first control piston 71 in the drawing plane and thereby closes the second control edge 74. The servo valve 90 is now in its second switching position, which is used for fuel injection via the injection openings 11, as in connection with the Description of the operation of the embodiment described in Figure 1 leads. To end the injection process, the actuator-side sealing seat 44 is closed by corresponding actuation of the switching valve 40, so that the rail pressure builds up again in the control chamber 33 and the first control piston 71 moves into its starting position and thereby due to the pressure force on the pressure surface 78 of the first control piston 71 the first control edge 73 is closed and the second stere edge 74 of the second control piston 72 is opened. It is expedient that a stop in the closing direction, that is, downward in the drawing plane, is provided on the second control piston 72 in order to avoid an unnecessarily wide opening of the second control edge 74. It is also expedient to allow an additional stroke of the second control piston 72 in order to ensure a defined closing force on the sealing seat of the first control edge 73. In order to avoid tolerance problems due to different starting positions of the control pistons 71 and 72, however, the permissible overstroke should be made as small as possible.

The embodiment in FIG. 7 works according to the same functional principle, with a defined opening stroke h of the second control edge 74 being set here, which realizes the throttle effect of the described throttle connection 130 for closing the second control piston 72.

The servo valves described can be used with all common rail injectors, in particular with pressure booster devices, in which the pressure booster device is controlled via a differential space as a pressure booster.

LIST OF REFERENCE NUMBERS

1

fuel injector

3

Fuel line

5

High-pressure fuel source

7

combustion chamber

10

Fuel injection valve

11

Injection port

12

closing piston

13

pressure shoulder

14

pressure chamber

15

guide region

16

Closing pressure chamber

17

closing spring

18

Return spring

20

Pressure booster device

21

Booster piston

22

first partial piston

23

second partial piston

24

cylinder

25

High-pressure chamber

26

backcourt

27

Pressure boosting chamber

30

control valve

31

Control valve body

32

drilling

33

control room

34

pressure chamber

35

valve chamber

36

communication space

37

connecting channel

40

switching valve

41

actuator

42

actuator piston

43

actuator bore

44

actuator-side sealing seat

45

leakage on the actuator side

46

annular space on the actuator side

51

first pressure line

52

second pressure line

53

connecting line

54

check valve

55

connecting bore

56

inlet throttle

57

further connecting line

58

Backcourt line

59

control line

61

first return line

62

second return line

64

outlet throttle

71

first control piston

72

second control piston

73

first control edge

74

second control edge

75

first spring

76

second spring

77

contact point

78

first printing area

79

second printing area

80

spool

81

control edge

82

reed valve

83

sealing surface

84

piston rod

85

sealing ball

86

compression spring

87

conical seat

88

piston rod

89

attack

90

Servo-valve

91

lower housing section

92

upper housing section

93

first flange

94

second flange

95

cavity

96

cylinder body

97

continued drilling

101

first annulus

102

second annulus

103

first oblique hole

104

flattening

105

further cylinder body

106

deepening

107

cavity

108

longitudinal bore

109

first cross connection

110

second cross connection

111

throttle bore

112

body

113

further stepped bore

114

face

115

further cavity

116

annular gap

117

second oblique hole

118

third oblique hole

119

further throttle bore

120

Querkanal

121

further annular gap

122

wiring

123

further annulus

125

spring retainer

126

ring element

127

damping piston

130

throttle connection

131

drilling

132

throttle

133

annulus

134

restriction

Claims (15)

Fuel injection device for internal combustion engines with a fuel injection valve (10) connected to a high-pressure line, a control valve (30) which has a valve body (31) with a piston which is arranged to be longitudinally displaceable in a bore (32), the piston in a first valve position having a valve pressure chamber separates from a return or leakage oil system and wherein in a second valve position, by activating a switching valve (40) acting on the control valve (30), the valve pressure chamber is expanded to the return system and an actuation of the fuel injection valve (10) is initiated, characterized in that that the piston has at least two individual, longitudinally displaceable control pistons (71, 72), each of which is assigned a control edge (73, 74) for the two valve positions. Fuel injection device according to Claim 1, characterized in that the two control pistons (71, 72) are arranged axially one behind the other in the bore (32). Fuel injection according to claim 1 or 2, characterized in that a hydraulic throttle connection (130) is formed on the second control piston (72), which realizes hydraulic flow and pressure forces, such that actuation of the second control piston (72) when the valve pressure chamber relaxes arises. Fuel injection device according to claim 3, characterized in that the throttle connection (130) a connection between one of the second control edge (74) associated pressure space (34) and a connecting space (36) assigned to the first control edge (73). Fuel injection device according to Claim 3 or 4, characterized in that the throttle connection (130) is formed by a throttle bore (131, 132) which is guided through the second control piston (72). Fuel injection device according to Claim 3 or 4, characterized in that the throttle connection (130) on the second control piston (72) is implemented by means of a throttle point (134) assigned to the second control edge (74), the throttle effect of the throttle point (134) being dependent on an opening stroke h the second control edge (74) is generated. Fuel injection device according to claim 1, 2 or 3, characterized in that the first control piston (71) and the second control piston (71) are in contact at a contact point (77) and in that the contact point (77) between the first control edge (73) and the second control edge (74). Fuel injection device according to claim 7, characterized in that the contact point (77) are each formed by end faces of the first control piston (71) and the second control piston (72). Fuel injection device according to Claim 1, 2 or 3, characterized in that between the first control edge (73) and the second control edge (74) there is a connecting space (36) which forms the valve pressure space and which in the first valve position is acted upon by a system pressure Pressure chamber (34) and in the second valve position via a valve chamber (35) with the return system in connection. Fuel injection device according to Claim 9, characterized in that a rear space line (58), which communicates with a rear space (26) of a pressure booster device (20), opens into the connecting space (36), so that in the second valve position the rear space line (58) via the valve chamber (35) is connected to the return system, so that the rear space (26) can be depressurized. Fuel injection device according to Claim 10, characterized in that the pressure booster device (20) has a pressure booster piston (23) which separates a pressure booster chamber (27) permanently connected to the high-pressure fuel source (5) from a high-pressure chamber (25) connected to the fuel injection valve (10). Fuel injection device according to one of the preceding claims, characterized in that the first control edge (73) and / or the second control edge (74) is designed as a sealing seat. Fuel injection device according to one of the preceding claims, characterized in that the second control piston (72) is designed with a sealing ball (85), so that the second control edge (74) is designed from the sealing seat formed by the sealing ball (85). ' Fuel injection device according to one of the preceding claims, characterized in that the second control piston (72) is designed as a plate valve (82), so that the second control edge (74) is designed from the sealing seat formed by the plate valve (82). Fuel injection device according to one of the preceding claims, characterized in that the first control edge (73) and / or the second control edge (74) is designed as a slide seat.

Images