EP1395748B1 - High pressure sealing element for injectors - Google Patents

Abstract

The invention relates to an injector for the injection of fuel into the combustion chamber of an internal combustion engine. The injector (1) comprises an injector housing (2) in which a pressure chamber (3) enclosing an insert (7) is embodied. The above may be filled with high pressure fuel by means of a high pressure inlet (21). A control chamber (25) is pressurised by means of the pressure chamber (3), defined by the insert (7), fixed in a drilling (6, 46) in the injector housing (2) and a valve component (26). The valve component (26) may be displaced by executing a stroke displacement (47) within the insert (7). A one-piece metallic sealing element (9) is arranged with a friction fit (14) around the periphery (8) of the insert (7). The sealing element (9) is pressurised with the high pressure in the pressure chamber (3).

Description

Technical area

In fuel injection systems for air-compressing internal combustion engines come today injection systems with high-pressure accumulation space (Common Rail) are used. The Fuel injection systems further include injectors for injecting fuel into the combustion chambers of the internal combustion engine, the in the fuel injection system prevailing pressures in terms of tightness and material resistance. For this purpose, annular sealing elements are used on injectors with which a seal of the high pressure area of the injector against low areas Pressure of the injector is made. Will the pressure level in fuel injection systems for generating a higher thermodynamic efficiency of the internal combustion engine raised, the demands on the sealing elements of the Fuel injector.

State of the art

EP-A 0 483 770 relates to a high-pressure sealing system for the control valve of an electromagnetic Fuel injection valve for internal combustion engines. This high pressure seal system comprises a sealing ring made of a deformable material between a pair of substantially parallel surfaces of the valve body and a Hollow body is compressed. These surfaces are with a high degree of precision edited in order to achieve a minimum margin.

DE 196 19 523 A1 relates to a fuel injection valve for high-pressure injection. According to this solution, a fuel injection valve is proposed, the High-pressure injection is used in self-igniting internal combustion engines and the Control of injection includes a solenoid valve. For controlling this solenoid valve a control circuit is provided which is in a first circuit part and a split second circuit part. The second circuit part is of the first circuit part, which together serves to control multiple injectors, separated on each arranged individual injection valve. The housing is clipped onto the fuel injection valve and traversed inside the fuel for cooling.

According to this solution, a sealing ring made of bronze-reinforced Teflon and a metallic support ring are inserted between the housing and a recessed in this insert below the control room. The support ring of metallic material is required to improve the sealing effect of the bronze reinforced Teflon ring and to prevent the extrusion of the bronze reinforced Teflon ring. To prevent migration of the sealing ring on the insert in the direction of the pressure-reducing the control chamber flow restrictor, appropriate measures must be taken. In addition, it is necessary in the previous solution when using the bronze-reinforced Teflon ring and the metallic support ring to assemble this process safely in the correct position, which makes a considerable manufacturing effort required. A further injection valve according to the preamble of claim 1 is shown in WO 99 37 909 A. Presentation of the invention

With the solution according to the invention can be compared to that of the prior art known solution on the one hand to save a component and on the other hand in the pressure chamber prevailing pressure at high pressure loading e.g. via the inlet from the high-pressure collecting chamber (Common rail) to support the sealing force of the sealing element deploy. If the sealing element according to the proposed invention frictionally by means of a press fit on a recessed in the injector housing of the fuel injector Shrunk insert, is a manufacturing technology particularly easy to produce solution given. The preferred of a metallic material or alloys metallic Materials manufactured one-piece sealing element in particular does not tend to to deform such that it is in an annular gap between insert and one in this movable valve component creeps and the ease of movement of the valve component obstructed within the injector housing of the fuel injector. This by means of a press fit On a lateral surface of the insert fastenable sealing element provides about In addition, a symmetrical, inexpensive to produce component.

Due to the one-piece design of the sealing element can be an uncomplicated installation be achieved; In addition, this offers by means of a press fit on the lateral surface of the insert part fastenable sealing element a Abdichtpotential, which also further pressure level increases withstand in the fuel injector of fuel injection systems, so that as well at further increasing pressures, the sealing of the high pressure region of the pressure chamber is ensured at the fuel injector.

The sealing of the high-pressure region of the fuel injector is preferably carried out with a Press fit between the sealing element inner diameter and valve element / ram / or Nozzle needle OD differences between 0.04 to 0.15 mm.

drawing

With reference to the drawing, the invention will be explained in more detail below.

Figur 1

einen Längsschnitt durch die Komponenten eines Kraftstoffinjektors sowie des Injektorgehäuses und

Figur 2

eine Wiedergabe des Details Z aus Figur 1 in vergrößertem Maßstab.

It shows:

FIG. 1

a longitudinal section through the components of a fuel injector and the injector and

FIG. 2

a reproduction of the detail Z of Figure 1 on an enlarged scale.

variants

Figure 1 is a longitudinal section through the components of a fuel injector and the Injector housing to remove.

The representation according to FIG. 1 can be taken from that in a fuel injection system inserted fuel injector 1 for injecting fuel an injector 2 includes. The injector housing 2 of the fuel injector 1 contains a pressure chamber 3, from whose pressure chamber bottom 5 extends from a bore 6 through the injector housing 2. The bore 6 is penetrated by a rotationally symmetrical insert part 7. The insert 7 may in its axial extent of a cylindrical cross section in go over a frusto-conical tapered paragraph. Between the circumference 8 of the insert 7 and the wall of the bore 6 is required for assembly reasons Annular gap 18. Within the insert part 7 is an injection valve member 26, for example formed as a valve piston shown in Figure 1, received in accordance with of the double arrow shown in Figure 1, reference numeral 47, a vertical Lifting movement for opening / closing of injection openings, not shown in Figure 1 at the combustion chamber end of the fuel injector 1 is used.

The formed in the interior of the injector 2 pressure chamber 3 is except through the Pressure chamber bottom 5 bounded by the wall 4 of the injector 2. The pressure chamber 3 is a high-pressure inlet 21 shown in dashed lines, which at an estuarine point 20 opens into the pressure chamber 3, with the high pressure port 22 of the high pressure source in connection. The mouth 20 of the high pressure inlet 21 is preferred at a strength-optimized location of the wall 4 of the pressure chamber 3 in the interior the injector housing 2.

On the circumference 8 of the insert part 7, a sealing element 9 is received, which by the in the pressure chamber 3 prevailing high pressure on the one edition 17 forming Pressure chamber bottom 5 is pressed. The pressure prevailing in the pressure chamber 3 high pressure acts on the integrally formed sealing element 9 at the first annular surface 12, which represents the effective hydraulic pressure for the upcoming hydraulic pressure force. The sealing element 9 is preferably formed in one piece and of annular shape. The integrally formed sealing element 9 is connected by a non-positive connection 14, for example a press fit, received on the circumference 8 of the insert part 7. The Press fit 14 is made by differences in the inner diameter of the one-piece formed sealing element 9 and the outer diameter of the insert 7 causes which can be between 0.04 to 0.15 mm. The one-piece ring element, which is preferably made of metallic material or an alloy of metallic materials exists, it can be shrunk onto the circumference 8 of the insert part 7. The integrally formed sealing element 9 may e.g. made of aluminum or an aluminum alloy consist. Between the peripheral surface 8 of the insert part 7 and the inner diameter the one-piece sealing element 9 made of metallic material can be a non-positive Connection in the form of a press fit 14 by cold pressing of the metallic Material manufactured sealing element 9 on the peripheral surface 8 of the insert part 7 done. Depending on the differences in diameter of the non-positive connection 14th to be joined together components 7 and 9, a corresponding radial force, which the strength of the press fit 14 between insert 7 and integrally formed Sealing element 9 determined. The sealing element 9 has a first annular surface 12 which is the Assigns pressure chamber 3 and another, the pressure chamber bottom 5 zuweisende second ring surface. When sealing contact the second annular surface 13 of the sealing element. 9 made of metallic material on the pressure chamber bottom surface 5, the pressure chamber bottom acts as a support 17 which a between the peripheral surface 8 of the insert part 7 and the bore 6 within the injector 2 required for assembly reasons Annular gap 18 sealing closes. The sealing effect of the sealing element 9 is determined by the increased in the pressure chamber 3 pending fuel pressure, since in the pressure chamber. 3 prevailing pressure in the direction 19 (see illustration according to Figure 2), the sealing element 9 acted upon in the direction of the pressure chamber bottom 5 of the pressure chamber. by virtue of the use of a metallic material or a metallic alloy Materials in the manufacture of the sealing element, its deformation is excluded. This avoids that with increasing life of the fuel injector 1 the Sealing element 9 in the annular gap 18 between the peripheral surface 8 of the insert part 7 and the hole 6 inside the Injektorsgehäuses 2 creeps in and then leaks to adjust. In addition to avoiding leaks remain when using the proposed according to the invention, of a metallic material or alloys Metallic materials manufactured sealing element 9, the leakage losses from the limited with high pressure pressure chamber 3 limited.

From the pressure chamber 3 from the inflowing via the high-pressure inlet 21, under very high pressure fuel via an inlet funnel 23 and a to this subsequent inlet throttle 24 in the wall of the insert part 7 in a control room 25th one. The control chamber 25 is on the one hand by the insert part 7 and on the other hand by a in this guided valve component 26, for example, designed as a valve piston can be limited. In the end face of the valve component 26 may have a contour 26.1 exhibit. Thus, at the end face of the valve component 26 is a frusto-conical Form area 26.2, which has a complementarily shaped conical area 27.1 at the outlet 27 on the outlet side of the control chamber 27 cooperates. From the control room 25 extends from a drain 27, in which a flow restrictor 28 is received is.

The outlet throttle 28, via which upon actuation of a here designed as a spherical body Closing element 29 a pressure relief of the control chamber 25 is brought about is on End of the expiration 27 arranged. That the outlet throttle 28 releasing or closing Schliesselement 29 is partially surrounded by a molding 30, which at a lower end face of an anchor part 31 of a magnet arrangement for actuating the fuel injector 1 is arranged.

In the illustration according to FIG. 1, the anchor part 31 is formed integrally and comprises a bolt part and a plate-shaped configured part.

The insert 7, which has an upper cylindrical part and a adjoining tapered, an annular gap 18 delimiting part can, is by means of a fastener 33 in the form of a clamping nut fixed in a stepped bore 6, 46 in the injector housing 2. The fastening screw 33 is screwed into an internal thread 45 of the injector housing 2 and is located at an upper End face 32 of the insert part 7 at. Thereby, the insert part 7 with an annular Approach, causing a seal 34, to the injector 2 above a Bore 46 employed, so that the pressure chamber 3 in the interior of the injector 2 in Direction to the solenoid valve actuator assembly is pressure-tight manner.

The integrally formed in the representation of Figure 1 anchor member 31 of the actuator assembly is acted upon by a spring element 35, which is guided in a sleeve. The sleeve 35 surrounding the spring element is surrounded by a magnetic coil 36, the in turn can be accommodated in a magnet sleeve 37. On the outer peripheral surface the magnet sleeve 37 is an annular projection 38 formed on which a union nut 39 is applied. The magnet sleeve 37 is screwed through the union nut 39 with an external thread 40 on the outside of the injector 2 of the Fuel injector 1 causes.

The integrally formed armature part 31 of the actuator assembly is partially in one Insert sleeve 41 out, with the interposition of a spacer ring 42 via the magnet sleeve 38 is fixed, which in turn via the union nut 39 on the external thread 40 of the injector 2 is fixed. Between the magnet sleeve 38 and the injector housing 2, which are connected to each other via the union nut 39, is an O-ring Made of elastic material executable sealing element 43.

In the injector 2 of the fuel injector as shown in Figure 1 is a Bore 44 is formed, which via a connection not shown here with the high pressure port 22 is the high-pressure source of the fuel injector 1 in fluid communication and a nozzle space also not shown in Figure 1, which is also not shown Injector valve member surrounds, acted upon by high pressure fuel. The injection valve member serving as a nozzle needle with the combustion chamber side seat may be formed, is actuated by a pressure relief of the control chamber 25, the by the by means of the fixing screw 33 in the injector 2 fixed insert part. 7 on the one hand and by the valve component 26 on the other hand limited. The pressure relief / pressurization the control chamber 25 is effected by an actuation of the solenoid valve arrangement, e.g. via the energization of the solenoid coil 36.

FIG. 2 shows a reproduction of the detail Z according to FIG. 1 on an enlarged scale.

From the reproduced in Figure 2 representation of the designated in Figure 1 with Z range It is apparent that the pressure chamber 3 in the injector housing 2 is bounded by a wall 4 is that in the region of the mouth 20 of the high-pressure inlet 21 a radial Has diameter expansion. The discharge point 20 of the high-pressure inlet 21 of 2, not shown in FIG. 2, is preferably located in such a way with respect to its compressive strength optimized area of the limiting wall 4 of the pressure chamber Third

On the circumference 8 of the fixed by means of the fastening screw 33 in the injector 2 insert part 7, the sealing element 9 by a frictional connection 14 in shape attached to a press fit. The sealing element 9, which preferably consists of a metallic Material or alloys of metallic materials is manufactured, has a first Ring surface 12 of the pressure chamber 3 to, while the second annular surface 13 at the pressure chamber bottom 5 pressure chamber 3 is applied, which acts as a support 17 for the sealing element 9. Due to the prevailing in the pressure chamber 3 via the high-pressure inlet 21 high pressure is the first annular surface 12 of the sealing element 9 by the pressure 19 within the pressure chamber 3 acted upon. This pressurization of the sealing element. 9 causes a pressing of the metallic or alloys of metallic materials existing sealing element 9 to the pressure chamber bottom 5, i. is an increase in sealing force between the insert 7 and the injector 2 low. Of the Outer diameter of the sealing element 9 is identified by reference numeral 10, while the inner diameter 11, with the outer diameter of the insert 7, the non-positive connection 14 in the form of a press fit causes, and the outer diameter 10 opposite. At preferably annularly shaped sealing element. 9 for sealing the annular gap 18 between insert 7 and the bore 6 within the Injector 2, chamfers 15 and 16 may be formed.

While the sealing of the pressure chamber 3 to the annular gap 18 between the insert part. 7 and bore 6 within the injector 2 via the metallic material or Alloys made of metallic materials made sealing element 9, the seal the pressure chamber 3 at the top by the concerns of the insert part 7 am Injector 2 reaches the contact surface 34. As shown in Figure 1 is the insert 7 within the injector housing 2 in a stepped bore 6, 46 fixed by a fixing screw 33. The external thread of the fastening screw 33 acts with a formed inside the injector 2 internal thread 45 together, so that the insert part 7 in the injector 2 with a defined biasing force can be fixed. This will seal the top of the pressure chamber 3, which in the bore portion 46 of the stepped bore 6, 46 passes, reaches.

In the illustration according to FIG. 2, which enlarges the area represented by Z in FIG In addition, it can be seen that the valve component 26 whose end limits the control chamber 25 within the insert part 7, the Shape may be shaped such that the end face of the valve component 26 has a frustoconical Section 26.2, with a complimentarily formed drain cone. 27 of the sequence 27 protrudes. On the outer circumferential surface of the valve component 26 one or more annular grooves, as shown in Figure 2, are formed.

The invention described in more detail in connection with Figures 1 and 2 Solution avoids for further fuel injector generations where higher pressures can be realized, targeted voting on a possible pressure build-up below the sealing ring. With the solution according to the invention, it is possible that Hochwandern exclude the sealing element 9 and by suitable choice of material that Extruding the sealing element 9 in the gap 18 to avoid. Furthermore, the invention provides proposed solution a one-piece inexpensive and easy to install Symmetrical sealing element 9. To increase the sealing effect of the sealing element This is advantageously arranged in such a way that this by the in the pressure chamber 3 prevailing high fuel pressure is applied, which in addition to training the non-positive connection 14 on the circumference of the insert part 7 to increase the Sealing force in the region of the pressure chamber bottom 7, which the support 17 for the sealing element 9 forms, boosts.

LIST OF REFERENCE NUMBERS

1

injector

2

injector

3

pressure chamber

4

pressure chamber wall

5

Pressure chamber floor

6

drilling

7

insert

8th

peripheral surface

9

sealing element

10

outer diameter

11

Inner diameter

12

first ring surface

13

second ring surface

14

non-positive connection (interference fit)

15

chamfer

16

chamfer

17

edition

18

annular gap

19

print direction

20

Mouth point high pressure inlet

21

High-pressure inlet

22

High pressure port

23

feed hopper

24

inlet throttle

25

control room

26

valve component

26.1

End surface contour

26.2

frusto-conical area

27

drain channel

27.1

Drain channel Cone

28

outlet throttle

29

closing element

30

moldings

31

Anchor part (one-piece)

32

Front side of the insert part 7

33

fixing screw

34

Contact surface of the front side 32 on the injector housing 2

35

spring element

36

solenoid

37

magnet sleeve

38

annular projection

39

Nut

40

External thread injector housing 2

41

insert sleeve

42

spacer

43

elastic sealing element

44

inlet bore

45

Internal thread injector housing 2

46

Bore portion of hole 6

47

stroke movement

Claims (8)

1. Injector for injecting fuel into the combustion chamber of an internal combustion engine, having an injector housing (1), in which there is formed a pressure chamber (3) which surrounds an insert part (7), has a pressure chamber base (5), can be filled with fuel under a high pressure via a high-pressure inlet (21) and via which pressure can be applied to a control space (25) which is delimited by the insert part (7), fixed in a bore (6, 46) in injector housing (2), and a valve component (26), the valve component (26) executing a reciprocating movement (47) within the insert part (7), a single-piece sealing element (9) being accommodated at the periphery (8) of the insert part (7), the sealing element (9) facing a first annular surface (12) of the pressure chamber (3) which is exposed to the high pressure prevailing in the pressure chamber (3), and the sealing element (9) bearing against the pressure chamber base (5) by means of a second annular surface (13) on the opposite side from the first annular surface (12), characterized in that the sealing element (9) is metallic and is held in a nonpositively locking connection (14) at the periphery of the insert part (7).
2. Injector according to Claim 1, characterized in that the sealing element (9) is produced from metallic material or alloys of metallic materials.
3. Injector according to Claim 2, characterized in that the sealing element (9) is produced as an aluminium ring.
4. Injector according to Claim 1, characterized in that the single-piece sealing element (9) is held at the periphery of the insert part (7) by means of a press fit (14).
5. Injector according to Claim 4, characterized in that the differences in diameter between internal diameter (11) of the sealing element (9) and the external diameter of the insert part (7) amount to between 0.04 and 0.15 mm.
6. Injector according to Claim 1, characterized in that when the second annular surface (13) of the single-piece sealing element (9) is bearing against the pressure chamber base (5) of the pressure chamber (3) an annular gap (18) between the insert part (7) and the bore (6) within the injector housing (2) is closed.
7. Injector according to Claim 1, characterized in that the pressure chamber (3) formed in the injector housing (2), in its upper region, is sealed off by a sealing location (34) which is formed between an annular surface of the insert part (7) and a delimiting surface of a bore section (46) and the sealing force of which is defined by means of a securing element (33) which can be received in the injector housing (2).
8. Injector according to Claim 1, characterized in that the pressure chamber (3) is delimited by a wall (4) inside the injector housing (2), which wall has a section of widened diameter and in which wall a location (20) of a high-pressure inlet (21) opens out.

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