WO2008148643A1

WO2008148643A1 - Injector

Info

Publication number: WO2008148643A1
Application number: PCT/EP2008/056228
Authority: WO
Inventors: Nadja Eisenmenger; Hans-Christoph Magel
Original assignee: Robert Bosch Gmbh
Priority date: 2007-06-04
Filing date: 2008-05-21
Publication date: 2008-12-11
Also published as: DE102007025961A1

Abstract

The invention relates to an injector (1) for injecting fuel into a combustion chamber of an internal combustion engine, especially a common rail injector, said injector comprising an electromagnet arrangement (27), and a valve element (9) that can switch between a closing position and an opening position wherein the fuel flow is released into the combustion chamber, and which is actively connected to a control chamber (11) that can be connected to a low-pressure region (6) by means of a control valve (21) comprising an adjustable valve sleeve (22). A pressure rod (23) subjected to pressure in the axial direction is radially arranged inside the valve sleeve (22). According to the invention, the pressure rod (23) is supported beneath the electromagnet arrangement (27), at an axial distance from same.

Description

description

Title injector prior art

The invention relates to an injector for injecting fuel into a combustion chamber of an internal combustion engine, in particular a common rail injector, according to the preamble of claim 1.

EP 1 612 403 A1 describes a common rail injector with a control valve (servo valve) pressure balanced in the axial direction for blocking and opening a fuel drain path from a control chamber. By means of the control valve, the fuel pressure can be influenced within the control chamber, wherein the control chamber is permanently supplied via an inlet throttle with fuel under high pressure. By varying the fuel pressure within the control chamber, a valve element is moved between an open position and a closed position, the valve element releasing the fuel flow into the combustion chamber of an internal combustion engine in its open position. The control valve comprises an adjustable in the axial direction by means of an electromagnetic actuator valve sleeve which is guided on an integrally formed with a valve piece guide pin. The valve sleeve defines a valve chamber of the control valve formed by a reduced diameter portion of the guide pin only radially outward, so that no opening or closing forces from the high-pressure fuel within the valve chamber to the valve sleeve Act. Due to this characteristic, the control valve is suitable for switching very high pressures. The high-pressure fuel flows with the control valve open through the vertical discharge channel and through these intersecting transverse bores in the direction of the low-pressure region. The miniaturization of such control valves are set narrow limits, since too small a diameter there is a risk of breakage of the valve piece in the area of the bore intersections.

In the applicant, therefore, a (previously) in-house state of the art has been developed in which the valve sleeve is guided radially outwardly from the valve piece and in which within the valve sleeve a pressure-aufschlagter in the axial direction pressure pin is provided which is formed within the valve sleeve valve chamber seals up in the axial direction and which is supported in the axial direction of an electromagnet assembly of the injector. In this case, depending on the size of the fuel pressure to be switched by the control valve, the electromagnet arrangement must absorb a supporting force of several 100 Newtons. In order to be able to reliably support this supporting force over the life of the injector, the electromagnet arrangement must be correspondingly solid, which in turn leads to cost-intensive constructions. A further disadvantage is that an armature stroke measurement in the described injector design is difficult to realize because a central access is blocked by the solenoid assembly to an anchor plate or to the valve sleeve by the pressure pin supporting itself on the solenoid assembly. DISCLOSURE OF THE INVENTION Technical Problem

The invention is therefore based on the object to reduce the force acting centrally on the solenoid assembly load.

Technical solution

This object is achieved with the features of claim 1. Advantageous developments of the invention are specified in the subclaims. All combinations of at least two features specified in the description, the claims and / or the figures also fall within the scope of the invention.

The invention is based on the idea no longer support the pressure pin directly on the underside of the solenoid assembly, but below the solenoid assembly with axial distance to this. An upper end face of the pressure pin is preferably located at an axial distance from a lower pole face of the electromagnet arrangement. Due to the inventive support of the pressure pin below the solenoid assembly, this can be made less massive and thus simpler and less expensive. In addition, the support of the pressure pin with axial distance to the solenoid assembly allows easier integration of Ankerhubmessung in the injector, since the anchor plate and / or the valve sleeve of the control valve in the case of providing the electromagnet assembly passing through channel from the Injektoroberseite are easily accessible / is. Through such an optional channel can the fuel flows directly to an injector return.

In a further development of the invention is advantageously provided that the axial distance between the solenoid assembly and the pressure pin, in particular the upper end side of the pressure pin, is dimensioned so large that the pressure pin is supported below one of the solenoid assembly facing top of a valve sleeve operatively connected to the armature plate. As a result, the top of the anchor plate for an optional Ankerhubmessung is even more accessible. To produce an operative connection between the valve sleeve and the anchor plate, it is conceivable to design these components in one piece or to fix them to one another.

Preferably, for supporting the pressure pin, a built-in part, in particular an inserted between two components insert is provided, which is designed such that the force acting on the pressure pin pressure force is guided in the radial direction to the outside and is supported there on an injector. For example, it is conceivable to support the mounting part in the axial direction at the edge on the electromagnet arrangement or to receive it in an internal thread of an injector component, in particular into the injector body.

It has proven to be advantageous for the component to have the supporting force of the pressure pin deflecting radially outwardly at least one support arm extending in the radial direction. Preferably, the built-in part with at least two, preferably evenly over equipped with the circumference distributed support arms. In order for the at least one support arm to be formed continuously from radially outward to radially inward up to the pressure pin, in particular up to the upper end side of the pressure pin, the valve sleeve and / or the anchor plate is provided with at least one lateral recess (notch) for the support arm, which is penetrated by the support arm in the radial direction. Preferably, each support arm is associated with such, in particular identically formed, recess.

In order to ensure a symmetrical introduction of force of the supporting force with a radial distance to the pressure pin in an injector, in particular the solenoid assembly or an internal thread of Injektorbauteils, is advantageously provided in an embodiment of the invention that the support arm associated with an outer support ring, in particular integrally formed therewith , Is, by means of which the force acting on the pressure pin pressure force can be intercepted in the injector.

In order to realize an improved injector control, the injector in a development of the invention is equipped with an armature stroke measuring device, in particular an optical one.

In particular, in order to ensure good accessibility of the armature plate and / or the valve sleeve for measuring the armature stroke, in a development of the invention, preferably centrally in the electromagnet arrangement, a channel extending in the axial direction is provided which preferably leads to an injector return. Through this channel, the armature stroke can be measured. It is advantageous if the valve sleeve is spring-loaded with a closing spring in the direction of its valve seat, that is, downwards in the direction away from the electromagnet arrangement. The closing spring ensures a quick return of the valve sleeve in its valve seat when not energized solenoid assembly. In particular, for space saving reasons, it is advantageous to arrange the closing spring within the channel passing through the electromagnet assembly.

Preferably, the closing spring is not supported directly on the anchor plate and / or the valve sleeve, but rather on a spring plate, which preferably rests on the anchor plate or the valve sleeve. The upper end face of the spring plate then serves to be exposed to light waves for measuring the armature stroke.

In particular, in order to minimize the sealing diameter of the pressure pin within the valve sleeve, the pressure pin is in development of the invention in several parts, in particular two parts, formed, preferably a lower part of the pressure pin has a smaller diameter than an upper, supported below the solenoid assembly part. However, a one-piece pressure pin training is alternatively feasible.

Brief description of the drawings

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 partial sectional view of a common rail injector,

2 shows an alternative embodiment of a common rail injector,

3 is a sectional view of a possible embodiment of a fitting for supporting a pressure pin,

4 shows a non-cut, perspective view of the insert according to FIG. 3, FIG.

5 shows a plan view of the mounting part according to FIGS. 3 and 4,

6 shows an alternative embodiment of a built-in part and

Fig. 7: another, alternative embodiment of the insert.

Embodiments of the invention

In the figures, the same components and components with the same function with the same reference numerals.

In Fig. 1, designed as a common rail injector injector 1 is shown for injecting fuel into a combustion chamber of an internal combustion engine. The injector 1 is connected via a high pressure supply line 2 of a High-pressure fuel storage 3 (Rail) with under high pressure (about 1800 to 2000 bar) standing fuel, especially diesel oil or gas supplied. The fuel high-pressure accumulator 3 is supplied with fuel from a low-pressure reservoir 5 by a high-pressure pump 4 designed in particular as a radial piston pump. A low pressure region 6 of the injector 1 is hydraulically connected via an injector return 7 to the reservoir 5. In the injector return 7, a later to be explained control amount of fuel is discharged and fed via the high pressure pump 4 to the high-pressure circuit again.

The injector 1 has an injector body 8, in which a one-part or multi-part valve element 9 in the axial direction between an open position and a closed position is adjustable. In its open position, the valve element 9 releases the fuel flow from a nozzle hole arrangement (not shown) into the combustion chamber of the internal combustion engine.

With an upper end face 10, the valve element 9 defines a control chamber 11 within a valve piece 12, which is pressed by a clamping sleeve 13 in the axial direction on an annular shoulder 14 of the injector body 8 and thus arranged stationary within the injector body 8.

In the control chamber 11 opens an introduced into the valve member 12 inlet throttle 15, which supplies the control chamber 11 with fuel from a surrounding a lower portion of the valve member 12 pressure chamber 16. The pressure chamber 16 is in turn via the high pressure supply line 2 and a supply channel 17 supplied with fuel from the high-pressure fuel storage 3. When the valve element 9 is open, the fuel flows directly from the pressure chamber 16 through the nozzle hole arrangement (not shown) into the combustion chamber of the internal combustion engine.

The control chamber 11 is connected to a flow passage 18 in the axial direction within the valve piece 12 with outlet throttle 19 with a valve chamber 20 of a control valve 21 (servo valve). The valve chamber 20 is radially outwardly bounded by an axially adjustable valve sleeve 22 and in the axial direction of a two-piece pressure pin 23. The pressure pin 23 is pressurized in the axial direction in the plane of the drawing upwards, wherein a lower pressure pin part 23 a has a smaller diameter than an upper portion of a stepped upper pressure pin part 23b. The control valve 21 is a pressure-balanced valve in the axial direction, since the valve sleeve 22 formed integrally with an armature plate 24 does not have any hydraulic opening forces when the control valve 21 is closed.

To open the control valve 21, that is, to lift off the valve sleeve 22 from its valve seat 12 provided on the valve seat 25, an electromagnet 26 of an electromagnet assembly 27 is energized, so that arranged below a lower pole face 28 of the solenoid assembly 27 anchor plate 24 and thus also the Valve sleeve 22 are moved in the plane of the drawing in the axial direction upwards. This allows fuel from the valve chamber 20 radially below the valve sleeve 22 into the low pressure region 6 of the injector 1 and from there via a central channel 32 within the solenoid assembly 27 in the axial direction to the injector return 7 and thus to the reservoir 5 to flow. The flow cross-sections of the outlet throttle 19 and the inlet throttle 15 are matched to one another such that a net outflow of fuel from the control chamber 11 results, with the result that the force acting on the end face 10 of the valve element 9 compressive force decreases and the valve element 9 of its not shown Valve seat lifts off. On its way from the control chamber 11 to the injector return 7, the outflowing fuel (control amount) passes lateral transverse bores 33 in a guide extension 29 of the valve member 12. The guide extension 29 is formed integrally with the valve member 12 and guides the valve sleeve 22 at its outer periphery.

The pressure pin 23, or the upper end face 30 of the upper

Pressure pin part 23b is below the lower pole face 28 and thus below a holding body 31 of the

Electromagnet assembly 27 and below an upper side

34 of the integrally formed with the valve sleeve 22 armature 24 is supported in the axial direction. For this purpose, the pressure pin 23 is located with its upper end face 30 on the underside of a built-in insert part

35 on. The built-in part 35 has three support arms 36, which are distributed uniformly in the circumferential direction and which respectively pass through a lateral recess 37 of the armature plate 24 in the radial direction. The built-in part 35 has an outer support ring 38 which is supported at a radial distance from the pressure pin 23 in the axial direction upward on an adjusting ring 39, which of a sleeve member 40 and a clamping nut 41 in the axial direction is pressed onto an inner peripheral shoulder 42 of the injector body 8. In this case, the clamping nut 41 is screwed to an external thread 43 of the injector body 8. The support arms 36 formed integrally with the outer ring 38 extend radially inwardly from the outer ring 38 and upwardly in a curved portion in the axial direction and meet centrally above the pressure pin 23 to form a longitudinal center axis L of the injector 1 Centric support surface 44 for abutment of the pressure pin 23. The underside of the Einstellringscheibe 39 is located both in the radial direction outwardly and in the axial direction downwardly spaced from the upper end face 30 of the pressure pin 23rd

As can be seen from FIG. 1, one of the support surface 44 also directly opposite upper side 45 of the installation part 35 is spaced apart in the axial direction from the upper side 34 of the anchor plate 24.

An armature plate 46 extending into the channel 32 rests on the armature plate 24, which is subjected to spring force in the axial direction downwards on the armature plate 24 by means of a closing spring 47, which is likewise arranged within the channel 32, so that the armature plate 24 is moved together with the valve sleeve 22 in non-energized solenoid 26 in the axial direction down to the valve seat 25. The closing spring 47 rests on a peripheral shoulder 48 of the spring plate 46, whereby a cylindrical extension 49 protrudes in the axial direction in the formed as a helical spring closing spring 47 and serves as a projection surface for a Ankerhubmesseinrichtung not shown. In FIG. 2, an alternatively designed injector 1 is shown, wherein the structure essentially corresponds to the structure of the injector according to FIG. 1, so that in the following, in order to avoid repetition, essentially only the differences between the embodiments will be discussed. With regard to the similarities, reference is made to the preceding description of the figures.

In comparison to the exemplary embodiment according to FIG. 1, the installation part 35 according to FIG. 2 is made flatter. The mounting part 35 is provided with an outer support ring 38 which is not supported on the Einstellringscheibe 39, but directly on the lower pole face 28 and the holding body 31 of the solenoid assembly 27.

The force exerted by the pressure pin 23 on the support surface 44 of the built-in part 35 compressive force is distributed over the three evenly distributed in the circumferential direction supporting arms 36, as in the embodiment of FIG. 1 in the radial direction outwardly, but not in the axial direction downwards, but in the axial direction upwards. Starting from the outer support ring 38, the support arms 36 are therefore not curved upwards, but curved downwards. As can be seen from Fig. 2, also in this embodiment, the top 45 of the insert 35 is disposed below the top 34 of the anchor plate 24 and with axial distance to the spring plate 46.

In FIGS. 3 to 5, the installation part 35 according to FIG. 1 is shown in detail. Fig. 3 and 4 additionally show the installation situation of the mounting part 35 with respect to the anchor plate 24 with valve sleeve. In particular in FIG. 3, the support surface 44 formed by the support arms 36 can be seen to bear the pressure pin 23. It becomes clear that the upper surface 45 of the installation part 35 opposite the support surface 44 is arranged at an axial distance below the upper side 34 of the anchor plate 24.

From Fig. 4, the formation and arrangement of the lateral recesses 37 can be seen in the anchor plate 24, which are penetrated by the support arms 36.

5 shows a plan view of the mounting part 35 with outer support ring 38 and three support arms 36 offset by 120.degree. In the circumferential direction. It can be seen that the support arms 36, which extend in the radial direction and join concentrically in the circumferential direction, widen in a radially outer area are formed to initiate the support force as evenly as possible in the outer, circumferentially closed support ring 38.

FIGS. 6 and 7 show alternative types of built-in components 35. The exemplary embodiments shown are without the outer support ring 38. Common to both designs is a symmetrical arrangement of the support arms 36 in the circumferential direction. The built-in part 35 according to FIG. 6 has only two opposing support arms, whereas the built-in part 35 according to FIG. 7 comprises four support arms 36 arranged at 90 ° to one another in the circumferential direction.

Claims

claims

1. injector for injecting fuel into a combustion chamber of an internal combustion engine, in particular common rail Inj ector, with an electromagnet assembly (27), one between a closed position and the fuel flow in the combustion chamber releasing opening position adjustable valve element (9), the is operatively connected to a control chamber (11) which is connectable by means of a, an adjustable valve sleeve (22) having control valve (21) with a low pressure region (6), wherein radially within the valve sleeve (22) a pressure pin (23) is arranged,

characterized,

in that the pressure pin (23) is supported below the electromagnet arrangement (27) at an axial distance from it.

2. An injector according to claim 1, characterized in that the pressure pin (23) below a, a lower pole face (28) of the solenoid assembly (27) facing upper side (34) of an operatively connected to the valve sleeve (22) anchor plate (24) supported is.

3. Injector according to one of claims 1 or 2, characterized in that for supporting the pressure pin (23) has a built-in part (35), in particular an insert, is provided with which the on the pressure pin (23) acting pressure force in the radial direction outside is guided.

4. Injector according to claim 3, characterized in that the built-in part (35) has at least one radially extending support arm (36) having a recess (37) of the valve sleeve (22) and / or the anchor plate (24) in the radial Take hold of direction.

5. An injector according to claim 4, characterized in that the support arm (36) radially outside a support ring (38) is associated, which is supported in the axial direction within the injector (1).

6. Injector according to one of the preceding claims, characterized in that a Ankerhubmesseinrichtung is provided.

7. An injector according to one of the preceding claims, characterized in that the electromagnet arrangement (27) in the axial direction, in particular centrally, with a to an injector return (7) leading channel (32) is interspersed.

8. An injector according to claim 7, characterized in that within the channel (32) acting on the valve sleeve (22) closing spring (47) is arranged.

9. Injector according to claim 8, characterized that the closing spring (47) is supported on a spring plate (46).

10. Injector according to one of the preceding claims, characterized in that the pressure pin (23) is formed in several parts.