EP2547895A1

EP2547895A1 - Fuel injector

Info

Publication number: EP2547895A1
Application number: EP11702983A
Authority: EP
Inventors: Oliver Rain; Marco Beier; Roman Etlender
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-03-15
Filing date: 2011-02-04
Publication date: 2013-01-23
Anticipated expiration: 2031-02-04
Also published as: DE102010002845A1; CN102792003B; CN102792003A; RU2555066C2; RU2012143687A; EP2547895B1; WO2011113640A1

Abstract

The invention relates to a fuel injector (10), in particular a common rail injector, for injecting fuel into a combustion chamber (11) of an internal combustion engine, having an injection valve element (27) that can be displaced between a closed position and an open position opening a nozzle hole arrangement (25), it being possible for the injection valve element (27) to be driven by a magnetic armature assembly (49; 18) via a coupling chamber (70) filled with a pressurized medium. According to the invention, provision is made for the magnetic armature assembly (49; 80) to have at least two magnetic armatures (55, 55a, 55b, 56, 56a, 56b, 81, 86, 92, 94, 95, 97, 101, 108, 108a) which can be moved relative to one another and the end faces (65, 65c, 66, 66c) of which project into the coupling chamber (70).

Description

description

Fuel injector

State of the art

The invention relates to a fuel injector according to the preamble of claim 1. Such a fuel injector is from the post-published

DE 10 2008 042 227 A1 of the Applicant known. The known fuel injector is used for injecting fuel into a combustion chamber of an internal combustion engine and has a pin-shaped injection valve member which is arranged via a coupler space in operative connection with a magnet armature. The coupler space serves as a force translator, which translates a movement of the magnet armature into a movement of the injection valve member in order to open or close injection openings on the housing of the fuel injector. The coupling of the magnet armature with the injection valve element via the coupler space takes place because the energy density of a magnet armature or its force is insufficient in a direct mechanical coupling with the injection valve member to the

Lift injection valve member from its sealing seat. Although it is possible in the prior art fuel injector to increase the force acting on the injection valve member opening force by an appropriate interpretation of the geometric relationships of gas tank, coupler and injection valve member, however, then the maximum possible stroke of the injection valve member for a sufficient function of the injector, ie for a complete release of the injection valve openings, not sufficient. Furthermore, it has been found that the required opening force for the injection valve member is only necessary as long as the injection valve member has not yet left its sealing seat on the housing. At this moment, the space under the injection valve member with the acted upon relatively high rail pressure, resulting in an additional opening force on the injection valve member. As a result, the force which is applied by the armature to the injection valve member can be reduced. Once the injection valve member has left the seat, however, it must be ensured that the injection valve member can cover a sufficiently large stroke.

Disclosure of the invention

Based on the illustrated prior art, the present invention seeks to further develop a fuel injector according to the preamble of claim 1 such that the magnet armature on the one hand applies the required opening force for lifting the injection valve member from its seat and on the other hand, the injection valve member has a relatively large Hub can perform.

The size or the cost of the armature should be relatively low. This object is achieved with a fuel injector having the features of claim 1. The invention is based on the idea, by at least two magnet armature movable relative to each other, which protrude with their end faces in the coupler space, the force transferable from the magnetic coil to the magnet armature force on the two armature such that a first armature substantially for lifting the injection valve member is responsible for its seat, while the other armature allows the required, relatively large stroke of the injection valve member.

Advantageous developments of the fuel injector according to the invention are specified in the subclaims. All combinations of at least two of the features disclosed in the claims, the description and / or the figures fall within the scope of the invention.

On the one hand to achieve a relatively simple guidance of the armature and on the other hand to avoid lateral forces on the armature during their movement, it is proposed in a preferred constructive implementation of the invention that the at least two armature are arranged concentrically to each other. It is particularly preferably provided that the at least two armature are formed rotationally symmetrical. As a result, in particular, a relatively inexpensive production of the magnetic tankers is made possible.

In order to enable one magnet armature to exert the highest possible opening force on the injection valve member at the first moment, while the other magnet armature is suitable for realizing the largest possible stroke of the injection valve member after opening, it is further proposed that the opening into the coupler space protruding end faces of the armature have a different size. In this case, the desired opening behavior can be influenced or controlled by varying the size. Since the one armature to achieve a relatively large opening force and the other armature should achieve the largest possible stroke, it is further proposed that of two armatures, the end face of the inner armature has a smaller area than the end face of the outer magnet armature. As a result, in the case of a concentric design of the magnet armature, in particular a relatively large wall thickness of the outer magnet core region is achieved, which can be implemented relatively easily in terms of manufacturing technology.

It is particularly advantageous in this case if the outer armature forms a guide for the inner armature. As a result, with a compact design, a secure guidance of the inner magnet armature is made possible.

In a first constructive implementation of the invention, it is provided that the armature are each formed as a flat armature. Such flat anchors have the advantage of being able to achieve relatively large tightening forces. However, the disadvantage here is that the physically meaningful stroke is limited as a result of the design.

Therefore, it is proposed in an alternative embodiment of the invention that the outer armature is designed as a flat armature and the inner armature as a solenoid plunger. Such a plunger anchor has a relatively large Lift up. Thus, the achievable stroke of the inner magnet tanker can be maximized.

In a further constructive embodiment, it is also possible to design both magentankers as plunger anchors, so that particularly large strokes can be achieved on both magnet anchors.

In order to limit the path of the outer magnet armature or to allow entrainment of the inner magnet armature by the outer magnet armature, so possibly only need a spring element is further proposed that the inner armature forms a stop element for the outer armature in the opening direction of the injection valve member.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings.

These show in:

1 is a schematic, sectional view of the basic structure of a fuel injector according to the invention, wherein the injection valve member is in the closed position,

2 shows a partial region of the fuel injector according to FIG. 1 in a first structural design of the magnet armature by means of two flat armatures, FIG.

3 shows a modified arrangement according to FIG. 2 with a stroke limiter for the inner flat armature, FIG.

4 shows representations of a modified magnet armature, consisting of two flat armature element elements,

5 shows a modified embodiment of a magnet armature assembly in a longitudinal section, in which the inner magnet armature as a plunger anchor ausgebil- det is and has a stop limit, while the outer armature is designed as a flat armature,

6 shows a comparison with FIG. 5 modified magnetic assembly with a modified stop for the inner gas tanker in a sectional view,

7 shows the magnet assembly according to FIG. 6 using a modified stop element for the inner armature, FIG.

Fig. 8

and 9 cross sections through in each case a modified magnet armature arrangement, in which the two magnet armature are each formed as a plunger armature and

FIG. 10 shows a modified magnet armature arrangement using two magnet anchors designed as plunger anchors. FIG.

The same components or components with the same function are provided in the figures with the same reference numerals.

In Fig. 1 is a schematically designed as a common rail injector fuel injector 10 for injecting fuel into a combustion chamber 1 1 of an internal combustion engine, not shown. The fuel injector 10 has a high pressure port 12, to which a supply line 13 is connected. About the supply line 13 of the fuel injector 10, among other fuel injectors, not shown with under high pressure (rail pressure) of, for example, over 2000bar standing fuel from a high-pressure accumulator 15 (Rail) supplied. The high pressure accumulator 15 in turn is supplied from a reservoir 16 (tank) with the aid of a preferably designed as a radial piston pump high pressure pump 17 with fuel. The high-pressure port 12 opens into a first pressure chamber 18, which is filled with substantially standing under rail pressure fuel. The first pressure chamber 18 is formed in a housing 20 of the fuel injector 10. In the longitudinal axis 21 of the fuel injector 10, a blind hole 22 is formed in the housing 20. The blind hole 22 extends from the first pressure chamber 18 and extends to the combustion chamber of the engine 1 facing the end of the fuel injector 10. The blind hole 22 extends at its the combustion chamber 1 1 end facing a second pressure chamber 24. In the housing 20 are further formed in the region of the second pressure chamber 24 nozzle holes 25 through which the second pressure chamber 24 injects fuel into the combustion chamber 1 1 of the internal combustion engine.

In the blind bore 22, a pin-shaped injection valve member 27 is slidably guided whose the combustion chamber 1 1 facing end is formed enlarged in diameter and forms a sealing seat 29 with a conical surface 28 with a wall portion of the second pressure chamber 24 in the closed position of the injection valve member 27.

In the injection valve member 27, a longitudinal bore 31 is formed as a blind hole, which opens via a transverse bore 32 in a first, formed in the housing 20 annular space 33. The first annular space 33 is connected via a connecting bore 34 with the first pressure chamber 18. Between the first annular space 33 and the second pressure chamber 24, a second annular space 35 in the housing 20 is formed. The second annular space 35 has a relief bore 36 with a throttle 37 arranged therein connection with the low-pressure region of the injection system, in particular with the reservoir 16.

The injection valve member 27 has on the first pressure chamber 18 side facing a portion 38 of reduced diameter. In the region of section 38, the injection valve member 27 is partially surrounded by a compression spring 39, which is supported on an end face 41 of the longitudinal bore 31 and the force applied to the injection valve member 27 in the direction of the sealing seat 39. The compression spring chamber 42, in which the compression spring 39 is arranged, is further coupled via a transverse bore 43 with the connecting bore 34 and thus is also substantially under high pressure (rail pressure). The blind hole 22, in which the injection valve member 27 is guided, has on the first pressure chamber 18 side facing a diameter-enlarged first bore portion 46. The first bore section 46 merges into a second bore section 47 with a reduced diameter in relation to the first bore section 46 in which the section 38 of the injection valve member 27 is guided.

In the first pressure chamber 18, a magnet armature assembly 49 is arranged. The armature assembly 49 is part of a Magnetaktors 50, which cooperates with the magnet armature assembly 49 magnetic core 51 with centrally disposed through hole 52 and embedded in the magnetic core 51 magnetic coil 53. By energizing the magnetic coil 53, the magnet armature assembly 49 can be moved in the direction of the arrow 54, thereby allowing opening of the injection valve member 27.

In the first embodiment of the invention shown in Figs. 1 and 2, the magnet armature assembly 49 has two cooperating, rotationally symmetrical magnet armature 55 and 56 in Flachankerbau way. The first magnet armature 55 concentrically surrounding the second armature 56 has a disk-shaped portion 57 which on the

Injection valve member 27 facing side merges into a sleeve or pin-shaped area 58. The area 58 dips into the first bore section 46. In the longitudinal axis of the second armature 56, a through hole 59 is formed. The through-hole 59 serves to guide a pin-shaped portion 61 of the inner first armature 55, which has on the side facing away from the injection valve member 27 a disk-shaped portion 62 in a form-fitting adapted recess 63 of the disk-shaped portion 57 of the second, outer armature 56 to form a radially encircling air gap 68 is received. Between the disc-shaped portion 62 of the first inner armature 55 and the opposite

Wall of the housing 20 is supported on a guided in the through hole 52 further compression spring 64, both the inner armature 55 and due to the abutment of the disc-shaped portion 62 of the inner armature 55 in the recess 63 and the outer armature 56 in the direction of the injection valve member 27 subjected to force. Of the two end faces 65 and 66 of the portion 58 and the portion 61 of the two armature 55 and 56, the end face 67 of the injection valve member 27 and the two sections 46, 47 of the blind hole 22, a coupler space 70 is formed. The coupler space 70 filled with high-pressure fuel serves to transmit a movement of the two magnet armatures 55, 56 into a corresponding movement of the injection valve member 27.

In the illustrated embodiment, it is provided, the end face 66 of the inner armature 55 is smaller than the end face 67 of the injection valve member 27 form, so as to allow a greater force transmission in a movement of the inner Magentankers 55. Since the volume of the coupler space 70 remains constant during a movement of the magnet armatures 55, 56, this means that due to the different sizes of the end faces 66 and 67, a relatively large stroke of the inner magnet armature 55 is translated into a relatively small stroke of the injection valve member 27. In other words, this means that even with a small, acting in the direction of the arrow 54 force on the inner armature 55 due to energization of the solenoid 53, a relatively large opening force on the injection valve member 27 and its sealing seat 29 can be realized.

When the magnet coil 53 is energized, the inner magnet armature 55 initially moves in the direction of the arrow 54, while the outer magnet armature 56 remains at rest for the first time. As soon as the injection valve member 27 lifts off from its sealing seat 29, the outer armature 56 also moves in

Direction of the magnetic coil 53, wherein due to the relatively large surface of the end face 65 (compared to the end face 66) also takes place a relatively large subsequent stroke of the injection valve member 27 in the opening direction. Thus, after the successful lifting of the injection valve member 27 from the sealing seat 29 due to the movement of the inner armature 55 by means of the outer magnet armature 56 can generate a relatively large stroke of the injection valve member 27.

FIG. 3 shows an embodiment of the invention modified with respect to FIGS. 1 and 2. In this case, the outer magnet armature 56a has, on its side facing the magnet coil 53, at its outer region a ramp. dial revolving level 71. Between the step 71 and the opposite end face of the magnetic core 51, a first return spring 74 is supported. The first return spring 74 thus pushes the outer armature 56a in the direction of the injection valve member 27. Furthermore, the inner armature 55a has a pin-like extension 72, which passes through the through hole 52 of the magnetic core 51. On the side facing away from the injection valve member 27 side of the inner armature 55a is followed by the extension 72 to a plate-shaped region 73, on which a second return spring 75 acts. By means of the second return spring 75, the inner armature 55a is also subjected to force in the direction of the injection valve member 27, the plate-shaped portion 73, when it rests against the injection valve member 27 opposite side of the magnetic core 51, a stroke limiter for the inner armature 55a in the direction of the injection valve member 27th formed. By means of such a design, a larger stroke can be realized on the outer magnet armature 56a than on the inner magnet armature 55a.

FIG. 4 shows views of a further, modified exemplary embodiment of the invention. It is essential here that the outer magnet armature 56b in its disk-shaped region 76 in the exemplary embodiment has four longitudinal slots 77 offset by 90 ^{° from} one another, into which sections 78 of the inner magnet armature 55b, which are arranged in cross-section in a generally cross-shaped manner. The portions 78 are formed on a pin-shaped portion 79 of the inner armature 55b, which is guided in a through hole of the outer magnetic core 56b. The sections 78 and the disc-shaped region 76 are arranged opposite a (not shown) magnetic coil. The embodiment shown in FIG. 4 has the advantage that the magnetic fluxes through the two magnet armatures 55b, 56b are independent of each other, that is to say that the magnetic flux can only flow through one of the magnet armatures 55b, 56b. Thus eliminates a parasitic air gap, as exemplified in Fig. 3 between the two armatures 55a and 56a is present.

FIG. 5 shows a magnet armature arrangement 80, in which an outer magnet armature 81 in flat armature construction has a disk-shaped region 82 and a pin-shaped section 83 projecting into the section 46. has. In the outer armature 81, a first bore portion 84 of relatively large diameter and a second bore portion 85 is formed with respect to the bore portion 84 of reduced diameter. The formed as a through hole second bore portion 85 is used together with the first bore portion 84 of the guide of an inner armature

86 in diving anchor design. The pin-shaped inner armature 86, which projects partially into the magnet core 51c, is provided on the side opposite the coupler space 70 with a stroke limiting element 87 which cooperates with a first return spring 88, which applies force to the inner armature 86 in the direction of the coupler space 70 , It is essential that the first bore section 84 of the outer magnet armature 81 has a connection bore 89 to connect to the first pressure chamber 18 or can be connected to high-pressure fuel. When lifting the inner armature 86 thus an annular space 90 is formed in the region of the first bore portion 84, which is filled with fuel. This solution has the advantage that the

Dimensioning or design of the two end faces 65c, 66c of the two magentankers 81, 86 can be made more independent of the magnetic circuit design, since the hydraulic forces in the transition region between the two bore sections 84, 85 are reduced via the space 90.

The embodiment of the invention shown in FIG. 6 essentially differs from the exemplary embodiment shown in FIG. 5 in that a stroke limiting element 91 is provided, which is designed as a collar on the inner magnet armature 92 and which is connected to a return spring 93. sammenwirkt. Further, the inner armature 92, except for the Hubbegrenzungselements 91, a pin-shaped or cylindrical shape. Furthermore, in contrast to the embodiment according to FIG. 5, no connecting bore 89 is formed on the outer magnet armature 94. This solution has the advantage that in comparison to the embodiment according to FIG. 5, the return spring 88 and the (separate) stroke-limiting element 87 can be dispensed with. However, it is now (in comparison to FIG. 5) only a limited independent movement of the two armature 92, 94 possible.

In the exemplary embodiment according to FIG. 7, the outer magnet armature 95 is force-actuated by means of a compression spring 96 in the direction of the injection valve member 27. beat. The inner armature 97 has a pin-shaped extension 98 which cooperates with a Hubbegrenzungsscheibe 99 outside of the magnetic core 51. The Hubbegrenzungsscheibe 99 is subjected to a force by a compression spring 100, so that on the one hand, the inner magnetic core 97 in the direction of the injection valve member 27 is subjected to force, on the other hand, however, a limitation of the adjustment of the inner magnetic core 97 in the direction of the injection valve member 27 is effected. By the pin-shaped extension 98 of the inner armature 97, which consists of magnetic material, the magnetic circuit can be influenced. In particular, by influencing the characteristic curve of the inner magnet armature 97 by a corresponding geometric dimensioning of the extension 98.

In the exemplary embodiment of the invention shown in FIG. 8, the outer armature 101 embodied in the form of plunger-type armature is designed in the form of a sleeve and protrudes with its upper half into the region of the magnet coil 102. Further, it has a circumferential collar 103, between which and a front surface of the magnetic core 104, a compression spring 105 is supported. The compression spring 105 thus presses the outer armature 101 in the direction of the injection valve member 27, wherein the movement of the outer armature 101 in the direction of the injection valve member 27 is limited by the circumferential collar 103. Within the outer armature 101, a cylindrical, also designed in Tauchankerbauweise inner armature 108 is disposed. The inner armature 108 has on the side facing away from the injection valve member 27 a preferably made of non-magnetic material, designed as a separate component part extension 109, the outside of the magnetic core 104 a

Hubbegrenzungsteller 1 10, on which a return spring 1 1 1 is supported, which forces the inner armature 108 in the direction of the injection valve member 27. Due to the geometric design of the magnetic core 104 and the magnetic cores 101 and 108, the forces on the armature 101, 108 can be adapted to the requirements. The forces on the outer armature

101 are determined mainly by the compression spring 105 and the magnetic flux 1 12. In contrast, forces on the inner armature 108 essentially by the return spring 1 1 1 and the magnetic flux 1 13 determined. Due to the formation of the Federal Circuit 103 and the Hubbegrenzungstellers 1 10 can be independent strokes of the Magentanker 101, 108 realize.

The illustrated in Fig. 9 embodiment of the invention differs from the embodiment shown in FIG. 8 by an annular elevation 1 14 on the magnetic core 1 15, which is arranged in operative connection with the outer armature 101 to the characteristic of the outer magnet armature 101st to influence. In addition, it is mentioned that by appropriate design of the magnetic core 1 15 also influencing the inner magnet tank 108 or on both armatures 101, 108 is possible.

The illustrated in Fig. 10 embodiment of the invention differs from the embodiment shown in FIG. 8 in the use of a Hubbegrenzungsscheibe 1 17 and a conically shaped portion 1 18 on the inner armature 108 a, in a corresponding stepped bore 1 19 of the magnetic core 104 b dips. Due to the geometric design of the area 1 18 and the stepped bore 1 19, the characteristic of the inner armature 108 a can be influenced.

The magnet armature arrangements of FIGS. 2 to 10 described so far can be modified or modified in many ways without deviating from the inventive concept. This consists in the use of at least two mutually independently movable armature, which are arranged longitudinally movable relative to each other and cooperate via a coupler space with an injection valve member.

Claims

claims

1 . Fuel injector (10), in particular common-rail injector, for injecting fuel into a combustion chamber (1 1) of an internal combustion engine, with an adjustable between an open position and a nozzle hole arrangement (25) opening position injection valve element (27), wherein the Injection valve element (27) can be actuated by a magnet armature arrangement (49, 80) via a coupler space (70) filled with pressure medium, characterized in that the magnet armature arrangement (49, 80) has at least two magnet armatures (55, 55a, 55b, 56) arranged so as to be movable relative to one another , 56a, 56b, 81, 86, 92, 94, 95, 97, 101, 108, 108a) which project with their end faces (65, 6c, 66, 66c) into the coupling space (70).

2. Fuel injector according to claim 1,

characterized,

in that the at least two magnet anchors (55, 55a, 55b, 56, 56a, 56b, 81, 86, 92, 94, 95, 97, 101, 108, 108a) are arranged concentrically with one another.

3. Fuel injector according to claim 2,

characterized,

the at least two magnet armatures (55, 55a, 55b, 56, 56a, 56b, 81, 86, 92, 94, 95, 97, 101, 108, 108a) are rotationally symmetrical.

4. Fuel injector according to claim 2 or 3,

characterized,

the end faces (65, 6c, 66, 66c) of the magnet armatures (55, 55a, 55b, 56, 56a, 56b, 81, 86, 92, 94, 95, 97, 101, 108, projecting into the coupler space (70) 108a) have a different size. Fuel injector according to claim 4,

characterized,

in the case of two magnet armatures (55, 56, 81, 86), the end face (66, 66c) of the inner magnet armature (55, 86) has a smaller area than the end face (65, 65c) of the outer magnet armature (56, 81).

Fuel injector according to one of claims 2 to 5,

characterized,

in that the outer magnet armature (56, 56a, 56b, 81, 94, 95, 101) forms a guide for the inner magnet armature (55, 55a, 55b, 86, 92, 97, 108, 108a).

Fuel injector according to one of claims 3 to 6,

characterized,

the magnet armatures (55, 55a, 55b, 56, 56a, 56b) of the magnet armature arrangement (49) are designed as flat armatures.

Fuel injector according to one of claims 3 to 6,

characterized,

that with two armatures (81, 86, 92, 94, 95, 97) of the outer armature (81, 94, 95) as a flat armature and the inner armature (86, 92, 97) is formed as a plunger armature.

Fuel injector according to one of claims 3 to 6,

characterized,

in the case of two magnet armatures (101, 108, 108a) both magnet armatures (101, 108, 108a) are designed as plunger anchors.

0. Fuel injector according to one of claims 7 to 9,

characterized,

in that the inner magnet armature (55, 55a, 55b, 86) forms a stop element for the outer magnet armature (56, 56a, 56b, 81) in the opening direction of the injection valve member (27).