DE102004035293A1 - Fuel injector for injecting fuel under pressure in combustion chamber of internal combustion engine through nozzle in segment of injector assembly by pressurizing fuel in compression area with pressure intensifier - Google Patents

Abstract

The fuel injector (1) has high pressure inlet (2) and check valve (6) for injecting fuel under pressure through inlet line (3). There is a control line (9), a supply line (28) and feeder lines (15,34) arranged with assembly segments and a nozzle (14) and injector valve (13). The operating piston (33) and pressure intensifier (5) compress the fuel before injection. The return line (50) takes the excess fuel back.

Description

technical area

The Fuel supply of the combustion chambers self-igniting Internal combustion engines usually take place by means of fuel injectors. The required injection pressure can be achieved by high-pressure storage systems to be provided. A further pressure increase takes place, for example, by pressure booster in the fuel injector. To a defined injection behavior too reach, the needle lift of the injection valve member is damped.

Out DE-A 102 29 415 is a device for injecting fuel in a combustion chamber of an internal combustion engine known. The Device for injecting fuel comprises a fuel injector, the over a high pressure source of high pressure fuel actable and over a metering valve actuated is. The injection valve member, which closes at least one injection port or releases, is associated with a independently movable damping element, which a damping room limited. In the damping element is at least one overflow channel to Connection of the damping chamber taken up with another hydraulic space.

A improved atomization and thus an improved combustion behavior of the fuel in the Combustion chamber is achieved in that the injection valve member only then opens, when the full injection pressure is present in the nozzle chamber. At the The prior art fuel injector begins the opening process of the injection valve member, however, even before the full injection pressure in the nozzle room is reached.

Presentation of the invention

One later opening the Einspritzventilgliedes and thus a higher fuel pressure at the beginning of Injection process is performed by the inventively designed fuel injector reached. The higher one Fuel pressure at the beginning of the injection process leads to a finer and more uniform atomization of the Fuel, resulting in a further reduced exhaust emissions.

Of the Fuel injector according to the invention Injecting fuel into a combustion chamber of an internal combustion engine is from a high-pressure accumulator with high pressure Fuel supplied. The fuel injector includes a compression space, the over a control line and a branching supply line connected to the high-pressure accumulator. Furthermore, the compression space with a nozzle space connected, which encloses an injection valve member, which at least one Injection port closes or releases. The injection valve member is an independent of this movable damping element assigned, which in turn limits a damper space. In a Connecting line from the control line to the damper room a switching piston is arranged, which releases a valve seat or closes.

Of the Switching piston is preferably designed such that an end face of the Control piston limits a control room. The control room is with the Compression space over a supply line hydraulically connected.

In an embodiment is in the supply line from the compression chamber into the control room arranged a throttle element.

In a preferred embodiment is in the supply line to the compression chamber a 2/2-way valve added. The 2/2-way valve is preferably a ball valve educated. Once through the movement of a piston in the compression chamber the pressure in the compression chamber is increased, the 2/2-way valve closes. This will prevent fuel from the compression chamber in the supply line and thus via the control valve in the returns arrives.

In a preferred embodiment is in the damping element formed a central bore. The central bore is used for Supply of damper space with fuel.

to Simplifying the manufacture of the injector housing is the Injektorgehäuse in individual Segments divided, which are stacked for mounting on top of each other. At branch positions of the housed in the housing channels are in the faces the segments recesses formed in the at least one channel flows over which Fuel supplied will and at least two channels lead over which Fuel dissipated becomes. The channels are preferably formed as holes in the segments.

Next the use of the inventively designed Fuel injector in high-pressure storage systems, this is too on other pressure-controlled injection systems, such as on pump-nozzle units, Pump lines nozzle units and distributor injection pumps used.

drawing

in the The invention will be described in more detail with reference to a drawing.

It shows:

1 an inventively designed fuel injector in a first embodiment,

2 a nozzle body of a fuel injector designed according to the invention in a first embodiment,

3 a nozzle body of an inventively designed fuel injector in a second embodiment.

variants

In 1 a fuel injector designed according to the invention is shown in a first embodiment variant.

in the The following is the inventively designed Fuel injector described using a system with high-pressure accumulator. In addition to the high-pressure accumulator can supply with high But also for example by a pump-nozzle unit, a pump-line-nozzle unit or a distributor injection pump. All systems in common is that the inventively formed Fuel injector is provided with a pressure booster.

As shown in 1 becomes a fuel injector 1 via a high-pressure accumulator, shown schematically here 2 supplied with high pressure fuel. The fuel first passes through a supply line 3 in a workroom 4 a pressure intensifier 5 , So no fuel from the workspace 4 in the high-pressure accumulator 2 flows back, is in the supply line 3 to the workroom 4 a check valve 6 added. In the embodiment shown here, the check valve 6 designed as a ball valve. As soon as the pressure in the high-pressure accumulator 2 drops to a pressure below the pressure in the supply line 3 to the workroom 4 lies, closes the check valve 6 ,

From the workroom 4 extends a supply line 7 to a control valve 8th , The control valve 8th is preferably designed as a 3/2-way valve and is controlled by a piezoelectric actuator or an electromagnet. In the position of the control valve shown here 8th the fuel flows out of the working area 4 over the supply line 7 to the control valve 8th and from this into a control line 9 ,

The pressure intensifier 5 and the control valve 8th are in an injector body 10 added. To the injector body 10 closes a nozzle body 11 at. The injector body 10 and the nozzle body 11 are preferably non-positive, for example with a union nut, with the fuel injector 1 connected.

In the nozzle body 11 is at least one injection port 12 formed, which via an injection valve member 13 is released or closed. The injection valve member 13 is preferably a one-piece configured nozzle needle. However, this can also be configured in several parts. The injection valve member 13 is from a nozzle room 14 enclosed. The nozzle room 14 is via a connection line 15 with a compression space 16 hydraulically connected. The compression room 16 becomes on one side by a front side 17 a translator piston 18 of the pressure intensifier 5 limited. At the translator piston 18 is a step-shaped extension 19 formed, which with one in the direction of the compression space 16 pointing face 20 a control room 21 limited. The step-shaped extension 19 shares the translator piston 18 in a first piston part 22 which is the compression space 16 facing and a second piston part 23 which is on the compression space 16 facing away from the step-shaped extension 19 followed. The second piston part 23 is of a spring element 24 enclosed, which is preferably designed as a spiral spring. The spring element 24 supports itself with one side against a stop 25 , which is the translator piston 18 closes and with the other side against a received in the injector annular stop 26 , As an annular stop 26 For example, a locking ring for drilling or a snap ring is suitable. The control room 21 of the pressure intensifier 5 is over a bypass 27 with the control line 9 connected.

The compression room 16 is via a supply line 28 , which also from the control line 9 branches off, fueled. In the supply line 28 a 2/2-way valve is included, which is the supply line 28 closes as soon as the pressure in the compression chamber 16 is higher than the pressure in the control line 9 , The 2/2-way valve 29 is thus designed in the form of a check valve.

From the compression room 16 extends a supply line 30 to a second control room 31 , The second control room 31 is on one side by a face 32 a switching piston 33 limited. The control piston 33 acts as a 2/2-way valve and gives a connection line 34 from the control line 9 in a damper room 35 free or close this. With closed connection from the control line 9 in the damper room 35 is the switching piston 33 in a seat 36 , In the muffling room 35 is a damping element 37 taken, which is formed for example in the form of a piston. At the damping element 37 is a second step-shaped extension 38 educated. In the muffling room 35 is the damping element 37 from a second spring element 39 enclosed. The second spring element 39 is preferably formed as a spiral spring. However, it can also be any further compression spring known to the person skilled in the art as a second spring element 39 be used. The second spring element 39 supports itself with one side against an end wall 40 of the damping chamber 35 and with the second side against a setting ring 41 , The adjusting ring 41 encloses the damping element 37 and lies on the second step-shaped extension 38 on. The adjusting ring 41 is used to compensate for manufacturing tolerances, so that every fuel injector 1 , which is mounted, the same spring force on the damping element 37 acts. On the second spring element 39 opposite side limits the second stepped extension 38 a third control room 42 , The third control room 42 will have a feed 43 , which with the control line 9 connected, fueled.

The damping element 37 is on the injection valve member side facing a flat ground end face 44 Mistake. On his the flat ground face 44 of the damping element 37 facing side is on the injection valve member 13 also a flat ground face 45 educated.

The damping element 37 is independent of the injection valve member 13 movable. For closing the at least one injection opening 12 becomes the injection valve member 13 in a seat 46 put, with the flat ground face 45 of the injection valve member 13 of fuel passing through a central bore 58 in the damping element 37 flows, is acted upon. As a result, separate the injection valve member 13 and the damping element 37 and the injection valve member 13 will initially be independent of the damping element 37 in the direction of the at least one injection opening 12 emotional.

To compensate for pressure pulsations is in the connecting line 34 to the damping room 35 a first throttle element 47 and in the inflow 43 to the third control room 42 a second throttle element 48 educated.

At rest, the control valve is located 8th in the in 1 shown position and there is no fuel injection in a fuel injector 1 associated combustion chamber 49 , This is the injection valve member 13 in the seat 46 and thus closes at least one injection opening 12 , Also lies the flat ground face 44 of the damping element 37 on the flat ground face 45 of the injection valve member 13 so that the central hole 58 in the damping element 37 is closed.

With closed injection opening 12 is the connection from the supply line 3 in the control line 9 via the control valve 8th Approved. From the control line 9 the fuel under storage pressure (system pressure) reaches the bypass 27 in the control room 21 , Furthermore, fuel passes through the supply line 28 in the compression room 16 and from there via the connecting line 15 in the nozzle chamber 14 and the supply line 30 in the second control room 31 , The third control room 42 will be over the inlet 43 also supplied with fuel under storage pressure. Thus, the work space 4 , the control room 21 , the compression room 16 , the second control room 31 , the muffling room 35 , the third control room 42 and the nozzle space 14 with the in the high-pressure accumulator 2 prevailing pressure level and the booster piston 18 in the pressure intensifier 5 is in the pressure balanced state. In this state is the pressure booster 5 deactivated and there is no pressure boost. The translator piston 18 is by the spring element 24 held in the starting position.

To start the fuel injection process, the control valve 8th switched to its other position. This will cause the control line 9 with a low-pressure return 50 connected and the supply line 7 locked. By connecting the control line 9 with the low-pressure return 50 the fuel under storage pressure flows out of the fuel injector 1 , reducing the pressure in the with control line 9 connected hydraulic rooms 21 and 42 decreases. Furthermore, closes due to the pressure difference between the compression chamber 16 and the control line 9 the 2/2-way valve 29 , In the workroom 4 that directly with the high-pressure accumulator 2 on the line 3 connected, the pressure does not change. Due to the decreasing pressure in the control room 21 and the resulting decreasing pressure on the face 20 the step-shaped extension 19 the booster piston moves 18 in the compression room 16 , resulting in a decrease in the volume in the compression chamber 16 and thus leads to an increase in pressure. Because the compression space 16 over the connecting line 15 with the nozzle space 14 and over the supply line 30 with the second control room 31 hydraulically connected, increases in the nozzle chamber 14 and in the second control room 31 the pressure too. The increasing pressure in the second control room 31 causes due to the on the face 32 of the control piston 33 acting pressure force of the switching piston 33 the connection line 34 from the damping room 35 in the control line 9 closes. For this reason, the damping chamber 35 continues to be filled with fuel under storage pressure. The force acting on the damping piston 37 in the direction of the injection valve member 13 acts and thus the injection valve member 13 in his seat 46 represents, is composed of the compressive force due to the fuel under storage pressure in the damping chamber 35 and the spring force of the spring element 39 , As soon as due to the increasing pressure in the nozzle chamber 14 increasing pressure force on the injection valve member 13 in the direction of the damping element 37 greater than that in the direction of the injection valve member 13 acting pressure force in the damping chamber 35 and the spring force of the second spring element 39 , the composite moves out of injection valve member 13 and damping element 37 from the at least one injection port 12 away, causing the injection valve member 13 from his seat 46 lifts and so does the at least one injection port 12 releases. As soon as the injection valve member 13 from his seat 46 lifts, fuel is in the combustion chamber 49 injected.

When opening the composite beats from injection valve member 13 and damping element 37 to the control piston 33 which causes it to leave its seat 36 lifts. This will cause the connection line 34 from the damping room 35 in the control line 9 released, reducing the pressure in the damping chamber 35 drops, resulting in a quick further opening of the injection valve member 13 leads.

To end the injection process, the control valve 8th back in the 1 shown switched position. As a result, the connection from the high-pressure accumulator 2 in the control line 9 open. About the bypass 27 fuel under storage pressure flows into the control room 21 , Due to the thereby increasing pressure force on the face 20 the step-shaped extension 19 at the booster piston 18 the booster piston moves 18 supported by the spring force of the compression spring 24 from the compression room 16 , reducing the volume of the compression space 16 is increased and so the pressure in the compression chamber 16 decreases. At the same time, fuel under storage pressure flows via the connecting line 34 in the muffling room 35 , Thus, the pressure in the nozzle chamber decreases 14 due to the hydraulic connection of the nozzle space 14 with the compression space 16 over the connecting line 15 while the pressure in the damping chamber 35 increases. The decreasing pressure in the second control room 31 and the increasing pressure in the damping chamber 35 causes the switching piston 33 and the damping element 37 separate. This will be the central hole 58 in the damping element 37 released, by which fuel pressure under pressure in the direction of the injection valve member 13 flows. The in the central hole 58 of the damping element 37 flowing fuel acts on the flat ground face 45 the injection valve member, causing this from the damping element 37 triggers and in his seat 46 is provided. As a result, the at least one injection opening 12 closed and the injection process into the combustion chamber 49 completed. About the inlet 43 Fuel under storage pressure reaches the third control room 42 , Thus, the damping element 37 pressure balanced and is by the spring force of the spring element designed as a compression spring 39 with the flat-ground face 44 on the flat ground face 45 placed the injection valve member. This will be the central hole 58 in the damping element 37 closed, so no fuel from the damping chamber 35 in the third control room 42 can flow. Due to the decreasing pressure in the compression chamber 16 and the increasing pressure in the control line 9 opens the 2/2-way valve 29 and so gives the supply line 28 free, so that fuel under storage pressure from the control line 9 in the compression room 16 can flow. From the compression room 16 The fuel under storage pressure reaches the supply line 30 in the second control room 31 , Thus, the switching piston 33 pressure balanced and remains in the open position. Once the control valve 8th is pressed again to start a new injection process, and the pressure in the compression chamber 16 increases, is due to the thus also increasing pressure in the second control room 31 and the thus increasing pressure force on the end face 32 of the control piston 33 this in the seat 36 and so the connection from the damping room 35 in the control line 9 locked.

In 2 the nozzle body of a fuel injector designed according to the invention is shown in a first embodiment.

To the manufacture and installation of the fuel injector 1 to facilitate, is the nozzle body 11 divided into individual segments. The advantage of the division into individual segments is that in each case only holes are formed in the individual segments or depressions are milled. At the in 2 illustrated embodiment, the nozzle body 11 in a valve segment 51 , a throttle segment 52 , a piston guide segment 53 , a needle guide segment 54 and an injection segment 55 divided. In the valve segment 51 is the 2/2-way valve 29 and the second control room 31 educated. Continue to be in the valve segment 51 Drilling holes for the inlet 43 to the third control room 42 , the control line 9 and the connection line 15 to the nozzle room 14 , Furthermore, in the valve segment 51 a first groove 56 formed, via which the connecting line 34 over the control piston 33 with the damping chamber 35 connected is.

In the throttle segment 52 are the throttle chamber 35 and holes for the inlet 43 to the third control room 42 , the control line 9 , the supply line 28 to the compression room 16 , the connection line 34 to the damping room 35 as well as the connecting line 15 to the nozzle room 14 educated. Furthermore, in the throttle segment 52 the throttle elements 47 and 48 designed for damping of pressure pulsations.

In the piston guide segment 53 is a hole 57 formed, in which the damping element 37 with the second step-shaped extension 38 is guided. Next to the hole 57 for guiding the damping element 37 are in the piston guide segment 53 Holes for the inlet to the third control room 42 and a third groove 60 and the third control room 42 as well as a second groove 59 through which the control line 9 with the supply line 28 and the connection line 34 is connected, trained.

In the needle guide segment 54 is a hole 61 formed, in which the injection valve member 13 is guided. The hole 61 opens stepwise into the nozzle chamber 14 , Finally, in the needle guide segment 54 a hole for the connecting line 15 in the nozzle chamber 14 taken, which in the step-shaped extension, that of the injection port 12 forms remote part of the nozzle chamber formed.

In the injection segment 55 is the nozzle space 14 including the injection openings 12 educated.

When installing the nozzle body 11 Make sure that the holes in each segment 51 . 52 . 53 . 54 and 55 , each forming a line, are arranged flush with each other. For this purpose, for example, at the individual segments 51 . 52 . 53 . 54 . 55 spigot 62 be formed, which in corresponding recess 63 intervention. The pins have 62 and the depression 63 each with the same cross section.

The connection of the individual segments 51 . 52 . 53 . 54 . 55 is preferably non-positively. For this purpose, for example, a union nut, which with one on the injector body 10 mounted external thread cooperates.

3 shows a nozzle body of an inventively designed fuel injector in a further embodiment.

In the 3 illustrated embodiment differs from the in 2 illustrated embodiment by a third throttle element 64 in the supply line 30 from the compression room 16 in the second control room 31 , By the third throttle element 34 becomes the movement of the control piston 33 attenuated. This avoids that the switching piston 33 due to high speed when closing out of his seat 36 rebounds and thus before the final closure of the connection from the control line 9 in the muffling room 35 This initially releases again for a short time due to the rebound. Also, the rebound of the control piston 33 from his seat 36 to damage the control piston 33 or the seat 36 to lead.

1

fuel injector

2

High-pressure accumulator

3

supply

4

working space

5

Pressure intensifier

6

check valve

7

supply control valve

8th

control valve

9

control line

10

injector

11

nozzle body

12

Injection port

13

Injection valve member

14

nozzle chamber

15

connecting line

16

compression chamber

17

Front side spool

18

Booster piston

19

stepped extension

20

Face of the stepped extension

21

control room

22

first piston part

23

second piston part

24

spring element

25

attack

26

annular stop

27

bypass

28

supply line

29

2/2 way valve

30

supply

31

second control room

32

Front surface of the control piston

33

switching piston

34

connecting line to the damping room

35

damping space

36

Seat

37

damping element

38

second stepped extension

39

second spring element

40

bulkhead damping space

41

attitude

42

third control room

43

Intake to the third control room

44

plano Face-damping element

45

plano face Injection valve member

46

Seat

47

first throttle element

48

second throttle element

49

combustion chamber

50

returns

51

valve segment

52

throttle segment

53

Piston guide segment

54

Needle guide segment

55

Injection segment

56

first groove

57

drilling

58

central drilling

59

second groove

60

third groove

61

drilling

62

spigot

63

deepening

64

third throttle element

Claims (10)

Fuel injector for injecting fuel into a combustion chamber ( 49 ) of an internal combustion engine, which from a high-pressure accumulator ( 2 ) is supplied with high-pressure fuel, wherein a compression space ( 16 ), which via a control line ( 9 ) and a branching off supply line ( 28 ) with the high-pressure accumulator ( 2 ), with a nozzle space ( 14 ), the nozzle space ( 14 ) an injection valve member ( 13 ), which at least one injection opening ( 12 ) closes or releases, and the injection valve member ( 13 ) an independent of this movable damping element ( 37 ), which in turn has a damping chamber ( 35 ), characterized in that in a connecting line ( 34 ) from the control line ( 9 ) into the damping chamber ( 35 ) a control piston ( 33 ) is arranged, which the connection from the control line ( 9 ) into the damping chamber ( 35 ) releases or closes. Fuel injector according to claim 1, characterized in that an end face ( 32 ) of the switching piston ( 33 ) a control room ( 31 ) limited. Fuel injector according to claim 2, characterized in that the control room ( 31 ) with the compression space ( 16 ) hydraulically via a supply line ( 30 ) connected is. Fuel injector according to claim 3, characterized in that in the supply line ( 30 ) between the control room ( 31 ) and the compression space ( 16 ) a throttle element ( 64 ) is arranged. Fuel injector according to one of claims 1 to 4, characterized in that in the supply line ( 28 ) to the compression space ( 16 ) a 2/2-way valve (29) is received. Fuel injector according to claim 5, characterized in that the 2/2-way valve ( 29 ) is designed as a ball valve. Fuel injector according to one of claims 1 to 6, characterized in that in the damping element ( 37 ) a central bore ( 58 ) is trained. Fuel injector according to one of claims 1 to 7, characterized in that the injection element ( 13 ) and the damping element ( 37 ) in a nozzle body ( 11 ), which are divided into individual segments ( 51 . 52 . 53 . 54 . 55 ), which are stacked for assembly over each other. Fuel injector according to claim 8, characterized in that at branching positions the in the segments ( 51 . 52 . 53 . 54 . 55 ) recorded lines ( 9 . 15 . 28 . 34 . 43 ) in the end faces of the segments ( 51 . 52 . 53 . 54 . 55 ) Recesses ( 56 . 59 ) are formed, in the at least one line ( 9 ), via which fuel is supplied and at least two lines ( 9 . 43 ; 28 . 34 ) lead, over which fuel is discharged. Fuel injector according to claim 8 or 9, characterized in that the lines ( 9 . 15 . 28 . 34 . 43 ) as holes in the segments ( 51 . 52 . 53 . 54 . 55 ) are formed.