DE102009027103A1 - Fuel injector for injecting fuel into high-pressure reservoir of internal combustion engine, has valve module housing resting on bearing surface of valve piece of injector, where stroke of actuator is set in direction by bearing surface - Google Patents

Abstract

The fuel injector (110) has a pre-mountable valve (156) including a valve module housing and a rotor module that is movably supported in the housing in axial direction. The rotor module is provided with a rotor (138) and an actuator (136) that is connected with the rotor. The valve module housing rests on a bearing surface (128) of a valve piece (118) of the injector, where a stroke of the actuator is set in a direction by the bearing surface and is set in another direction by a stopper in the valve module housing.

Description

State of the art

The The invention is based on known fuel injectors for injection of fuels in the combustion chamber of an internal combustion engine. In particular, will the invention described with reference to fuel injectors for injecting fuel from a common high-pressure accumulator (Common Rail), about which fuel to a plurality of fuel injectors under high pressure is provided, so-called common rail injectors. Especially The invention relates to fuel injectors having at least one Magnetic actuator in which by means of a magnetically actuated valve a movement of an injection valve member, which one or more Injection ports releases or closes over one or more hydraulic control chambers is controlled.

at Today, in series common rail injectors, in which a solenoid valve is disposed at the upper end of the injector, for example Coaxial, the solenoid valve is usually off during assembly several components mounted in the fuel injector. It will be usually with the help of selection wheels functionally relevant dimensions such. B. valve lift and residual air gap of the magnetic actuator set. Thereby have to Individual components are usually not made so accurately. One Disadvantage of the known production methods and fuel injectors lies however in the fact that the production comparatively expensive is because the fuel injectors from a variety of individual components must be composed and in a complex assembly process by means of said individual components have to be adjusted.

Disclosure of the invention

It Therefore, a fuel injector and a valve group for Use in the fuel injector proposed which has the disadvantages avoid the known fuel injectors at least partially and which allow a simpler and more reliable installation. The fuel injector is used for the injection of fuels in one Combustion chamber of an internal combustion engine, in particular, as shown above, from a high-pressure accumulator. The fuel injector includes a Pre-assembled valve group. Under a pre-assembled group is in general an assembly to understand, which in one separate step and as a separate manageable component manufacturable is. The valve group comprises a valve module housing and at least one in the Valve module housing axially movable mounted anchor module. In particular, the anchor module be stored coaxially. The anchor module comprises at least one anchor, which with a magnetic coil and / or a magnetic core of a magnetic actuator can cooperate, and at least one connected to the anchor Actuator. The actuator can in particular completely or partially cylindrically be configured and used to close or release an opening in a valve piece of Fuel injector, for example, an opening in at least one Bore in the valve piece of the fuel injector. For example, this hole can be directly or indirectly connected to a control chamber of the fuel injector be directly or indirectly hydraulically a stroke of an injection valve member to control.

The Valve module housing, which, for example, designed essentially cylindrically symmetrical can be on a support surface of a valve piece of the Fuel injector. For example, this valve piece in a casing be formed of the fuel injector and thus an integral part of the housing or, alternatively, as a separate component of the fuel injector be educated. The valve piece may, for example, as mentioned above, have at least one bore, which, for example, with a control chamber of the fuel injector connected is.

The Valve group is designed such that a stroke of the actuating element in a first direction (closing direction) through the support surface of the valve piece and in another direction (opening direction) is predetermined by a stop in the valve module housing. The actuator In particular, at least one projection and / or at least include a shoulder. For example, this may be a annular Expansion of the actuating element, for example, at its the support surface zuweisendem End, act. The projection and / or the shoulder act with the Stop of the valve housing together, allowing the stroke of the actuator in the opening direction is limited. The adjusting element can in particular at least partially as a sleeve, for example as an anchor sleeve, be designed. The actuator can accordingly, for example annular on the support surface rest and, for example, enclose an opening in the support surface annular. Also However, other embodiments are possible in principle.

The valve module housing may comprise at least one radial bore through which hydraulic fluid, in particular fuel, can flow from at least one bore received in the bearing surface when the actuating element is lifted off the support surface. For example, the valve module housing may comprise a, for example cylindrical, space in which the actuating element, in particular the at least one projection and / or the at least one shoulder of the Actuator, between a closed position and an open position can move. The at least one radial bore can be received in particular in the region of this space.

Of the Anchor may for example comprise an anchor plate, which for example plate-shaped and, for example, can be configured rotationally symmetrical. The anchor can in particular be materially connected to the actuating element be, for example by a welded joint. Between the anchor and the actuator can at least one shim for a Be provided residual air gap.

The Valve group may in particular be designed such that the Control element in an open Stop position rests directly on the stop in the valve module housing, this means without the interposition of one or more adjustment elements. Farther the valve group can be designed such that the actuating element in a closed stop position rests directly on the support surface, this means again without the use of additional Setting elements. The control element can for example be designed in one piece be, especially in the area of the stop and in the area of the bearing surface.

The Valve group can with a housing of the Fuel injector in particular by a non-positive and / or positive Be connected.

For example this can be a screw connection. Especially This screw connection between the valve module housing and consist of a valve clamping screw of the fuel injector.

Of the Fuel injector may include at least one solenoid, which for example, may also include a magnetic core. The solenoid is set up to act on the armature and thereby a stroke to cause the actuator. Furthermore, at least one spring element act on the anchor and / or the actuator, for example in a direction opposite to the magnetic force. The fuel injector can in particular be designed such that a residual air gap, So a gap remaining at maximum stroke between the anchor and a magnetic core of the solenoid, fixed by the armature module is given without any additional Residual air gap disks or similar Adjustment elements are provided.

Next the fuel injector in one or more of those described above Embodiments will continue to be a valve group for use in a fuel injector according to the above Description proposed. The valve group is as preassembled Valve group configured and has a valve module housing as well at least one axially movably mounted in the valve module housing Anchor module on. The anchor module comprises at least one anchor and at least one actuator connected to the armature. The valve module housing is set up, around on a support surface a valve piece of the fuel injector. A stroke of the actuating element is doing so in one direction through the support surface and in another direction specified a stop in the valve module housing. For further possible Embodiments of the valve group can be made to the above description of Fuel injector be referenced.

Of the proposed fuel injector and the proposed valve group show respect to known Devices of this type have numerous advantages. The invention is based inter alia on the recognition that it is fuel injectors according to the state the technique first may be advantageous that the valve lift can be adjusted and so that the individual components do not have to be manufactured with the highest precision. Indeed This usually only applies if the components in their entirety do not demand high accuracy. Own the individual components the fuel injector already due to increasing demands generally a higher one Quality, so it is an advantage for the the valve lift relevant dimensions directly into the components to introduce, for example, to grind. This can be done during The assembly eliminates the calibration process, and it may be additional Setting elements are dispensed with.

The actual valve can then be finished in the form of the valve group pre-assembled and adjusted module to be supplied to an assembly line of the fuel injector. There it can be mounted directly without having to do it again a calibration is required. Another advantage of the fuel injector and the valve group is that a smaller number of Components involved in the valve lift. This will change the tolerance chain generally reduced, and the number of interfaces based on from setting behavior over the lifetime can change the valve lift is reduced.

In addition to the above-described advantage that a calibration of the valve lift can be omitted during assembly of the fuel injector, it is an advantage of the invention that the dimensions involved in the valve lift can be configured very close to each other spatially. As a result, a small temperature influence on the total stroke can be realized. If the valve group, which is also referred to below as a valve module (both terms can be used interchangeably), placed directly on the support surface, so also results in a lower Verän the valve lift during operation. The support surface may, but does not necessarily have to lie in a plane with a valve seat of the valve group.

In the series variants of known fuel injectors can under System pressure come to an elastic deflection of the valve piece. These leads high rail pressures too a valve lift reduction. This can be done at system pressures of approx. 2000 bar in total strokes of 25 μm up to 5 μm be. In the embodiment according to the invention the valve lift, however, by a distance between the support surface and determined the stop. As well as the valve module housing on the bearing surface rests, this distance remains even with an elastic displacement the valve piece and / or a deflection substantially constant, so no change the valve lift occurs.

Brief description of the drawings

embodiments The invention is illustrated in the drawings and in the following Description closer explained.

It demonstrate:

1 and 2 Embodiments of known fuel injectors;

3A to 3C the various representations of a first embodiment of a fuel injector according to the invention; and

4 A second embodiment of a fuel injector according to the invention.

embodiments

In the 1 and 2 are known from the prior art and partially available in series fuel injectors 110 shown. The fuel injectors 110 include a housing 112 with a high pressure area 114 and a low pressure area 116 (here eg 2 ). In the case 112 is a valve piece 118 taken, which is a bore 120 includes, such as, for example 2 shows, with a control room 122 connected is. About the control room 122 is, for example, as in 2 recognizable, the movement of an injection valve member 124 in the case 112 controllable. The hole 120 has an opening at its upper end 126 in a bearing surface 128 of the valve piece 118 on.

Furthermore, the fuel injectors include 110 in the known embodiments according to the 1 and 2 valve modules 130 and magnetic modules 132 , By means of the valve modules 130 becomes the opening 126 released or closed. It acts a valve spring 134 on an actuator 136 a, so this against the support surface 128 is pressed. The actuator 136 is with an anchor 138 connected, on which a magnetic actuator 140 with a magnetic coil 142 and a magnetic core 144 acts.

In the 1 and 2 , which reproduce the designs according to the current state of the art, are provided in both examples, the components and the dimensions that contribute to the valve lift, with Maßpfeilen and letters. In both examples, it can be seen that the number of components with the respective interfaces to other components is very large. Each interface involves the risk that it can change over the lifetime, for example, set. This occurs mainly at interfaces that are not screwed tight, but at which components can rub against each other. Another problem is that with this arrangement, temperature differences can occur at the respective components. These act on the relatively large dimensions of the components and the respective coefficients of thermal expansion and change the stroke over the respective temperature.

To set the desired dimensions, for example, to compensate for manufacturing tolerances, are in the embodiments according to the 1 and 2 a plurality of adjusting elements 146 intended. These can, for example, during assembly of the fuel injector 110 as described above. These adjustment elements may, for example, as in 1 represented, a residual air gap disc 148 at the magnetic core 144 include, over which a stroke stop is adjustable. In the embodiment according to 2 however, a stroke stop occurs at one of the valve springs 134 surrounding sleeve 150 , which at its upper end on a shim 152 seated. Furthermore, the fuel injector 110 according to the in 1 Example shown as an adjustment 146 a dial 154 for adjusting the valve lift. This determines the position of the magnetic core 144 relative to the housing 112 and thus the valve lift. In the embodiment according to 2 is also such a dial 154 provided, which performs a similar function.

In the 3A and 3B however, is a first embodiment of a fuel injector according to the invention 110 with a pre-assembled valve group 156 shown, which as a valve module 130 or in a valve module 130 is used. The valve group 156 is in 3C shown in perspective sectional view in detail. The 3A and 3B which essentially has an identical section of the fuel injector 110 zei These serve to illustrate different details of the invention. So shows 3A relevant dimensions of the fuel injector, whereas in 3B a (there with the reference number 158 designated) return path is shown. The 3A to 3C will be described together below.

Again, the fuel injector includes 110 a housing 112 , In this case 112 is the valve module 130 recorded, on which in turn a magnetic module 132 with a magnetic actuator 140 seated. The magnetic module 132 includes a magnetic module housing 160 , which for example via a union nut 162 with the rest of the housing 112 connected and thus a part of this housing 112 forms. The magnetic module 132 furthermore comprises a magnetic coil 142 as well as a magnetic core 144 ,

Immediately below the magnetic actuator 140 which is coaxial in the housing 112 is included, is the valve module 130 with the pre-assembled valve group 156 arranged. The valve group 156 includes an anchor module 164 which is mounted coaxially and slidably in a valve module housing 166 is included. The valve module housing 166 has 3 sections in the illustrated embodiment. In an upper anchor section 168 , which is conically widened compared to the other sections, is a plate-shaped anchor 170 recorded, which part of the anchor module 164 is and on which the magnetic actuator 140 with its magnetic coil 142 and the magnetic core 144 acts. The anchor 170 is, preferably by a welded joint, with an actuating element 172 in the form of an anchor sleeve 174 connected. This anchor sleeve 174 is in a leadership area 176 in an actuating element spacing 178 , which forms part of the central bore of the valve module housing 166 below the anchor section 168 connects, leads. The anchor sleeve 174 in turn encloses a valve pin 180 , which at its upper end from the anchor sleeve 174 protrudes through the magnetic core 144 passes through and on the magnet module housing 160 is supported. Via a valve spring 134 becomes the anchor sleeve 174 acted upon by a force in the closing direction.

In a third, down to the actuator section 178 subsequent stop section 182 is the central bore in the valve module housing 166 widened again in comparison to the actuator element section 178 , Also the control element 172 has a cylindrical expansion in this area 184 up, with a shoulder 186 , In the stop section 182 are radial holes 188 in the valve module housing 166 intended.

The valve module housing 166 is at its lower end on a support surface 128 a valve piece 118 on. At its upper end, the valve module housing 166 against the magnetic module 132 be supported, for example, against the magnetic core 144 , so that, for example, by tightening the nut 162 the lower end of the valve module housing 166 against the support surface 128 is pressed. In the valve piece 118 is, for example, analogous to the embodiment in the 1 and 2 , a hole 120 provided in an opening 126 in the support surface 128 empties. The hole 120 opens, for example, analogous to the embodiment in 2 in a control room 122 , The valve piece 118 is for example with a raised edge 190 provided, which the valve module housing 166 encloses annularly at its lower end.

In a closed state, the actuator is 172 through the valve spring 134 on the support surface 128 pressed. It surrounds the sleeve-shaped actuator 172 the opening 126 annular in an annular sealing seat. The opening 126 is thereby closed in this closed position. Here is the magnetic actuator 144 for example, without power. In an open position, however, becomes the anchor 170 through the magnetic actuator 140 pulled upwards, and with this the actuator 172 , The actuator 172 is thus lifted from his seat, until this with his shoulder 186 to a stop 192 which acts as a stroke stop and an upper position of the actuating element 172 Are defined. As shown in the illustration 3 which returns the return 182 shows, in this open position, hydraulic fluid through the radial bores 188 out of the opening 126 escape and fed to a low pressure drain.

The anchor 172 is in the illustrated embodiment, fixed to the actuator 172 connected, for example, by this anchor, which may for example have an iron-cobalt alloy, with the anchor sleeve 174 , which may for example be made of 100Cr6, is welded, in particular by laser welding. A weld is in the 3A and 3B with the reference number 193 designated. Below the anchor 170 is between the anchor 170 and an anchor shoulder 194 at the anchor sleeve 174 , a dial 196 as an adjustment 146 intended. By means of this shim 196 a residual air gap can be set.

Like from the 3A - 3C Furthermore, it is apparent that only two components are involved in the valve lift or limit the valve lift, namely the valve module housing 166 with the stop 192 , and the valve piece 118 with the support surface 128 , These components are also from Their dimensions are arranged relatively close to each other. An advantage is therefore that with regard to the temperatures it can be assumed that these components will always assume approximately the same temperature. Even if it comes to small differences, there will be little by the stroke of the actuator 172 change because the dimensions are very small overall. The dimensions are in 3A shown. The letter a denotes the distance between the support surface 128 and the stop 192 and thus the maximum possible valve lift. The dimension b, however, denotes the axial extent of the expansion 184 , wherein the difference between the dimensions with a and b, the maximum stroke of the actuating element 172 calculated.

When installing the fuel injector 110 becomes the valve group 156 of the valve module 130 either via the magnetic module 132 on the valve piece 118 excited, for example about the union nut 162 , Alternatively, other clamping methods come into question, for example, independent voltage, for example via a thread. This is in an in 4 illustrated second embodiment of the fuel injector 110 shown. This embodiment corresponds essentially to the embodiment according to the 3A - 3C , so that in many parts reference can be made to the description of these figures. Unlike the 3A to 3C is in the second embodiment according to 4 the valve module 130 or the valve module housing 166 not over the union nut 162 against the support surface 128 of the valve piece 118 pressed but over a thread 198 which is located between the valve module housing 166 and a valve clamping screw 200 is provided. It should be borne in mind that large preload forces can easily change the stroke during assembly. Therefore, it is usually advantageous if the screw connection of the valve module 130 from the high-pressure-tight screw connection of the valve clamping screw 200 and the valve piece 118 is decoupled.

In both embodiments of the invention, therefore, a valve module 130 in the form or comprising a preassemblable valve group 156 realized in which the armature stroke is fixed and is predetermined for example by the dimension a. Additional adjustment elements are preferably not provided. The valve group 156 Thus, for example, it can be paired and / or classified. The term "paired" is understood to mean an assignment of components via targeted production. For example, a first component can be manufactured, and a relevant dimension X of this first component can be measured. Subsequently, a dimension Y of a second component is selectively produced. The first and second components then form a pair and are preferably no longer separated. The term "classified" is usually understood to mean an independent production of a first component and a second component. Relevant dimensions X and Y of these first and second components are then sorted into classes. During assembly, components of the respective classes are installed. As a result, however, paired and classified components usually do not differ.

The residual air gap between the anchor 170 and the magnetic actuator 140 or the magnetic core 144 is fixed by the anchor module 164 specified. In the illustrated embodiment, the valve group 156 designed so that the anchor 170 with the anchor sleeve 174 , which acts as a valve sleeve, welded and / or otherwise firmly connected. Previously, the residual air gap on the dial 196 be set. However, it is also conceivable here, without shim 196 to work and grind the residual air gap, for example, directly, for example, by editing the magnetic core 144 and / or the anchor 170 , Alternatively, or in addition to a laser welding at the connection between the anchor 170 and the anchor sleeve 174 Further connection techniques are conceivable. After the anchor 170 is mounted, is the valve group 156 basically assembled and ready for mounting in the fuel injector 110 , There then no dimension must be measured and readjusted during assembly. Will during operation of the fuel injector 110 the valve piece 118 bent upwards or shifted upwards, so the entire valve module 130 with the valve group 156 offset upwards. The valve lift practically does not change as a result. Hub-relevant components of the valve group 156 are only offset together in the axial direction.

Claims (12)

Fuel injector ( 110 ) for injecting a fuel into a combustion chamber of an internal combustion engine, in particular from a high-pressure accumulator, comprising a preassemblable valve group ( 156 ), whereby the valve group ( 156 ) a valve module housing ( 166 ) and at least one in the valve module housing ( 166 ) axially movably mounted anchor module ( 164 ), wherein the anchor module ( 164 ) at least one anchor ( 170 ) and at least one with the anchor ( 170 ) connected actuator ( 172 ), wherein the valve module housing ( 166 ) on a support surface ( 128 ) of a valve piece of the fuel injector ( 110 ) rests, wherein a stroke of the actuating element ( 172 ) in one direction through the support surface ( 128 ) and in another direction by a stop ( 192 ) in the valve module housing ( 166 ) is given. Fuel injector ( 110 ) after the previous one the claim, wherein the actuator ( 172 ) at least one projection and / or at least one shoulder ( 186 ), which with the stop ( 192 ) in the valve module housing ( 166 ) cooperates. Fuel injector ( 110 ) according to one of the preceding claims, wherein the actuating element ( 172 ) at least partially as a sleeve, in particular as anchor sleeve ( 174 ), is configured. Fuel injector ( 110 ) according to one of the preceding claims, wherein the valve module housing ( 166 ) at least one radial bore ( 188 ), by which hydraulic fluid, in particular fuel, from one in the support surface ( 128 ) recorded bore ( 120 ) from the support surface ( 128 ) lifted actuator ( 172 ) can flow. Fuel injector ( 110 ) according to any one of the preceding claims, wherein the armature ( 170 ) with the actuating element ( 172 ) is materially connected, in particular by a welded joint. Fuel injector ( 110 ) according to one of the preceding claims, wherein between the anchor ( 170 ) and the actuator ( 172 ) at least one shim ( 196 ) is provided for a residual air gap. Fuel injector ( 110 ) according to one of the preceding claims, wherein the valve group ( 156 ) is configured such that the actuating element ( 172 ) in an open stop position directly on the stop ( 192 ) in the valve module housing ( 166 ) rests. Fuel injector ( 110 ) according to one of the preceding claims, wherein the valve group ( 156 ) is configured such that the actuating element ( 172 ) in a closed stop position directly on the support surface ( 128 ) rests. Fuel injector ( 110 ) according to one of the preceding claims, wherein the actuating element ( 172 ) is integrally formed. Fuel injector ( 110 ) according to one of the preceding claims, wherein the fuel injector ( 110 ) at least one magnetic coil ( 142 ), wherein the magnetic coil ( 142 ) is set up on the anchor ( 170 ), wherein a residual air gap fixed by the anchor module ( 164 ) is given. Fuel injector ( 110 ) according to one of the preceding claims, wherein the valve group ( 156 ) with a housing ( 112 ) of the fuel injector ( 110 ) is connected by a non-positive and / or a positive connection, in particular a Schaub connection, in particular by a Schaubverbindung between the valve module housing ( 166 ) and a valve clamping screw ( 200 ). Valve group ( 156 ) for use in a fuel injector ( 110 ) according to one of the preceding claims, wherein the valve group ( 156 ) as a preassemblable valve group ( 156 ), wherein the valve group ( 156 ) a valve module housing ( 166 ) and at least one in the valve module housing ( 166 ) axially movably mounted anchor module ( 164 ), wherein the anchor module ( 164 ) at least one anchor ( 170 ) and at least one with the anchor ( 170 ) connected actuator ( 172 ), wherein the valve module housing ( 166 ) is arranged to rest on a support surface ( 128 ) of a valve piece of the fuel injector ( 110 ), wherein a stroke of the actuating element ( 172 ) in one direction through the support surface ( 128 ) and in another direction by a stop ( 192 ) in the valve module housing ( 166 ) is given.