DE102005062549A1 - Fuel injector for internal combustion engine has control valve fully integrated into fuel injector, high pressure fuel storage device connected to control chamber and integrated into fuel injector - Google Patents

Abstract

The fuel injector (10) has a nozzle needle (16) that bounds a control chamber (60) with a control surface (64) and a control valve (32) that can connect the control chamber to a low pressure region (52). The control valve is fully integrated into the fuel injector. A high pressure fuel storage device connected to the control chamber is integrated into the fuel injector. An independent claim is also included for a method of manufacturing a control valve for an inventive device.

Description

State of technology

The The invention relates to a fuel injector for an internal combustion engine The preamble of claim 1. The invention is further a method of manufacturing a control valve for a Fuel injector according to the preamble of the independent claim.

from Market ago, common rail fuel injectors are known. These are coming For example, in internal combustion engines for motor vehicles used. In such injection systems, the fuel is from a high pressure pump in a high-pressure fuel storage ("Rail") promoted to the multiple fuel injectors are connected. These inject the fuel directly into one each associated combustion chamber.

to Control of a fuel injector has such an over magnetically actuated Control valve, which is laterally or above the fuel injector is attached to its end facing away from the combustion chamber. When open Solenoid valve becomes a control chamber, which is from a nozzle needle of the fuel injector is limited, with a low pressure area connected, whereby the pressure in the control room decreases, which in turn to open the nozzle needle leads. As a valve element of the control valve usually comes a valve ball for use.

task the present invention is to provide a fuel injector, which is compact and inexpensive and has a long life. Furthermore the injection should be controlled very precisely.

epiphany the invention

These Task is performed by a fuel injector with the characteristics of Claim 1 solved. A further solution is in the manufacturing method mentioned in the independent claim specified. Advantageous developments of the inventions are in dependent claims called. Important features of the invention are further in the description and the drawing. It should be noted at this point that said Features also in very different combinations for the invention can be essential without being explicitly pointed out.

Advantages of invention

By the integration of the control valve in the fuel injector is it is possible the distance between the control chamber and an injection nozzle of the fuel injector to minimize. This in turn allows the use of a very short, little yielding nozzle needle or a short, acting on the nozzle needle closing piston, which allows a direct control of the injection process. By integrating the control valve in the fuel injector builds this compact overall. In addition, the so far on the Combustion chamber remote end of the fuel injector reduces existing mass accumulation or completely avoided what the load of the fuel injector due to Motor vibrations reduced. About that In addition, the fact that at the projecting end of the fuel injector no control valve is available, the degrees of freedom for the arrangement a high pressure port and a low pressure port larger.

Under the concept of complete Integration of the control valve in the fuel injector is thereby understood that the control valve including valve element and Betätigungsaktor Completely inside the case the fuel injector is located.

by virtue of the integration of the control valve in the fuel injector is it is possible a high pressure fuel storage connected to the control room is to also integrate into the fuel injector. An appropriate one High-pressure fuel storage in the sense of a "common rail" to which all Fuel injectors are connected to the internal combustion engine, is therefore no longer required. This will be a cost savings achieved and simplifies the installation of the fuel injector according to the invention. Due to the smaller distance between the control room and the volume of the high-pressure fuel storage are also on the one hand strong pressure drops to the beginning of an injection avoided, and on the other serves the high-pressure fuel storage at the end of an injection as a damping volume. Overall, this pressure oscillations in the high-pressure fluid system reduces and thus the mechanical stresses on high pressure loaded Reduced components of the fuel injector.

In order to fully integrate the control valve in the fuel injector, a miniaturization of the control valve is required. This can for example be achieved in that the control valve has a multi-part body, which comprises a valve needle receiving a valve body and a partially plate-shaped sealing element with a sealing seat for the valve needle. As a result, an internal sealing seat and a corresponding internal processing of the sealing seat is avoided. Instead, the sealing seat is accessible from the outside and can easily and despite small dimensions with high precision.

there is particularly preferred when the valve body and the sealing element a one-piece Blank are made by cutting. For example, first the Pre-treated blank, for example, be subjected to a heat treatment, then the separation of the blank into a valve body and a sealing element take place, then be on the sealing element of the Sealing seat and into the valve body a valve needle guide incorporated, and finally become valve bodies and sealing element reassembled at the separation point. In order to can be a very high positioning accuracy between the valve body and Sealing element can be achieved in the installed position. On the use of positioning pins or centering sleeves can be dispensed with. A good fluid seal even at high pressures will do so also in the case of the miniaturized control valve according to the invention allows.

He follows the separation of the blank in the valve body and sealing element Wire erosion, special can Positioning be realized on the sealing element, which allow precise positioning of the sealing element to the valve body. Is the separation for example, by breaking, by first in the blank a inserted lateral notch and at this the blank is then broken, reach the fractured surfaces for positioning the sealing element relative to the valve body.

If the control valve has a multi-part body and thus the Sealing seat is easily accessible for editing, can be different especially advantageous seat geometries can be realized: For example a flat seat to be reakisiert, in which at the valve needle Undercut is available with a virtually burr-free sealing edge. Of the appropriate sealing seat on the sealing element is made flat. Is possible but also the realization of a spherical shell seat. In this is on the valve needle no undercut available, but a vertical puncture. Possible is also a concave configuration of this area of the valve needle. in the Sealing element is introduced a spherical shell-shaped seat. This has the advantage that runout tolerances are compensated can, resulting in a particularly high tightness of the control valve in the closed Condition leads.

drawings

following become particularly preferred embodiments the present invention with reference to the accompanying Drawing closer explained. In the drawing show:

1 a partially sectioned view of a fuel injector;

2 an enlarged view of a portion II of the fuel injector of 1 ;

3 an enlarged and partially sectioned view of a portion of a first embodiment of a control valve of the fuel injector of 1 ;

4 a representation similar 3 a second embodiment;

5 a perspective view of a first embodiment of a sealing element of a control valve of the fuel injector of 1 ;

6 a representation similar 5 a second embodiment; and

7 a side view of a blank for producing a valve body and a sealing element of a control valve of the fuel injector of 1 ,

description the embodiments

A fuel injector for an internal combustion engine contributes in 1 Overall, the reference number 10 , It serves to inject fuel into a combustion chamber directly assigned to it 12 who in 1 indicated only by a dashed line. The injector comprises a nozzle body 14 in which a nozzle needle 16 and a closing piston acting on it 17 is received axially movable. At the one in the combustion chamber 12 protruding end of the nozzle body 14 are fuel exit channels 18 present as well as a housing-side valve seat (without reference numeral), with which the nozzle needle 16 cooperates.

The nozzle needle 16 has a conical pressure surface 20 on, the hydraulic force resulting in the opening direction of the nozzle needle 16 shows and the one pressure room 22 limited. This is via a high pressure channel 24 with a large volume fuel high pressure accumulator 26 connected in a housing element 28 of the fuel injector 10 is arranged, which is at the of the combustion chamber 12 opposite end of the fuel injector 10 located. The fuel high-pressure accumulator 26 is with a high-pressure connection of the fuel injector, not shown in the drawing 10 connected. About a spring 30 that are on the nozzle body 14 supports, the nozzle needle 16 acted upon in the closing direction.

In the fuel injector 10 is how particular out 2 shows, a control valve 32 integrated, with which the nozzle needle 16 can be operated. The control valve 32 includes a to the nozzle body 14 subsequent and as a sealing plate trained sealing element 34 and a to the sealing element 34 adjoining valve body 36 , At these closes turn the housing element 28 in which the high-pressure fuel storage 26 is available. In the valve body 36 is a step-shaped recess 38 present, the longitudinal axis in the present embodiment with that of the high-pressure fuel storage 26 is aligned and opposite the longitudinal axis of the nozzle needle 16 is somewhat offset, which, however, parallel to the longitudinal axis of the nozzle needle 16 runs.

A to the sealing element 34 adjacent area 38a the recess 38 , which has a comparatively small diameter, serves as a guide for a valve needle 40 of the control valve 32 , This is at her in the 1 and 2 upper end with an anchor plate 42 connected to an electromagnetic actuator 44 belongs. In one in the 1 and 2 upper area 38b the recess 38 with larger diameter is an electromagnetic coil 45 of the electromagnetic actuator 44 added. A feather 46 is supported by a spring plate 48 on the housing element 28 from and acts on the anchor plate 42 and attached to this valve needle 40 in the closing direction of the coil 45 path.

That in the 1 and 2 lower end of the valve needle 40 works with closed control valve 32 in a more detailed manner below with a sealing seat 50 together, on the top of the sealing element 34 is trained. From the seal seat 50 leads a discharge channel 52 to one in the 1 and 2 invisible low pressure connection of the fuel injector 10 , The in the 1 and 2 above the sealing seat 50 located area 38a the recess 38 in the valve body 36 points in close proximity to the sealing seat 50 an extension through which an inflow room 54 is formed. This is about a in the sealing element 34 existing channel 56 and an outflow throttle 58 with a control room 60 connected in the bottom of the sealing element 34 in the area of the upper end of the nozzle needle 16 is incorporated. The control room 60 is via an inflow throttle 62 with the high pressure channel 24 connected. The the control room 60 limiting top of the closing piston 17 forms a control surface 64 with in the closing direction of the nozzle needle 16 acting hydraulic force resultant.

How out 3 As can be seen, the sealing seat 50 on the sealing element 34 be designed as a flat seat, whereas on the valve needle 40 an undercut 66 is present, with the flat seat 50 cooperates. Alternatively, as can 4 shows the valve needle 40 have no undercut, but one to the longitudinal axis of the valve needle 40 vertical recess 68 , The sealing seat in turn is spherical shell-shaped, which allows axial tolerances, ie an angular offset of the longitudinal axis of the valve needle 40 opposite the sealing seat 50 to compensate.

One recognizes 1 that the control valve 32 completely in the fuel injector 10 is integrated. In the miniaturization of the control valve according to the invention 32 need to ensure reliable operation of the control valve 32 very tight tolerances are maintained. At a diameter of the valve needle 40 By typically 1.5 mm it is especially necessary that the positioning of the valve body 36 relative to the sealing element 34 or the positioning of the recess 38 to the seal seat 50 is very precise. Therefore, it is proposed in the present case that the sealing element 34 and the valve body 36 are made of an initially one-piece blank. This is, in order to have the required strength, a pretreatment, for example, subjected to a heat treatment. The corresponding hardness distortion of the blank, when the blank is, for example, a cylindrical part, symmetrical.

Before the heat treatment into the blank, the recess 38 and the discharge channel 52 brought in. After the heat treatment, the blank is in the valve body 36 and the sealing element 34 separated, for example by wire erosion. The area of the sealing seat 50 on the sealing element 34 is now easily accessible, leaving the sealing seat 50 with high accuracy on the sealing element 34 can be produced. Due to the symmetrical hardening distortion in the sealing element 34 and the valve body 36 The two parts can then be reassembled at the resulting separation point with a very high positioning accuracy. The use of positioning pins or on a centering can be dispensed with. Like from the 5 and 6 it can be seen on the sealing element 34 a fixing or positioning section in the form of notches 70a or in the form of a lateral slope 70b are introduced by the positioning of the sealing element 34 relative to the valve body 36 is ensured in a simple manner. How out 7 can be seen, sealing element 34 and valve body 36 from the one-piece blank are also made by breaking, with the break above a defined notch 72 is initiated. If the blank (reference numeral 74 in 7 ), so that from this the sealing element 34 and the valve body 36 arise, the fracture surfaces are sufficient for positioning.

The in 1 shown fuel injector 10 works as follows: About a in 1 fuel high-pressure pump, not shown, fuel in the high-pressure fuel storage 26 promoted. This is above the high pressure channel 24 the high pressure also in the pressure room 22 and over the inflow throttle 62 also in the control room 60 in front. In this initial state, in that of the fuel injector 10 no fuel is delivered, is the control valve 32 closed, that is, the coil 45 is de-energized and the valve needle 40 from the spring 46 to the seat 50 is pressed. Due to the small diameter of the valve needle 40 of only 1.5 mm, to the necessary surface pressure at the sealing seat 50 to get that from the spring 46 exerted spring force be comparatively low. This in turn has the positive effect of that coil 45 and anchor 42 and with it the whole control valve 32 build comparatively small.

The connection from the control room 60 to the discharge channel 52 is interrupted. The on the nozzle needle 16 in the closing direction acting forces due to the spring 30 and due to the hydraulic force on the control surface 64 are larger in this state than those on the printing surface 20 in the opening direction of the nozzle needle 16 acting hydraulic force.

For an injection, the coil becomes 45 energized. This raises the valve needle 40 from the seal seat 50 off, leaving fuel from the control room 60 over the outflow throttle 58 to the discharge channel 52 and can continue to flow to the low-pressure port, not shown. As a result, the pressure in the control room decreases 60 and those at the control area 64 in the closing direction acting hydraulic force until the nozzle needle 16 opens and fuel from the fuel exit channels 18 can flow out. For a completion of a fuel injection, the coil 45 switched off again, causing the valve needle 40 from the spring 46 against the seal seat 50 pressed and the connection between control room 60 and outflow channel 52 is interrupted. Thus, the pressure in the control room 60 because of the over the inflow throttle 62 After-flowing fuel rise again, resulting in an increase in the control surface 64 in the closing direction acting hydraulic force leads. Outweigh the closing direction on the nozzle needle 16 acting forces, this moves back against its housing-side sealing seat (no reference numeral), so that the delivery of fuel through the fuel outlet channels 18 is ended.

One recognizes 1 that by integrating the control valve 32 in the fuel injector 10 , And there, in its axially central region, the possibility opened, the closing piston 17 comparatively short. This is therefore relatively stiff, which allows a direct control of the injection process. By integrating the control valve 32 in the axial center of the fuel injector 10 space is created for housing the fuel high-pressure accumulator 26 also in the fuel injector 10 , The distance between fuel high-pressure accumulator 26 and the fuel exit channels 18 is correspondingly short, whereby pressure oscillations are damped. One recognizes 1 also, that the fuel injector shown 10 at his in 1 upper end has no "mass accumulation", resulting in a lower vibration stress of the fuel injector 10 during its operation leads.

Claims (8)

Fuel injector ( 10 ) for an internal combustion engine, with a nozzle needle ( 16 ) with a control surface ( 64 ) a control room ( 60 ) and a control valve ( 32 ), which the control room ( 60 ) with a low pressure area ( 52 ), characterized in that the control valve ( 32 ) completely into the fuel injector ( 10 ) is integrated. Fuel injector ( 10 ) according to claim 1, characterized in that a high-pressure fuel storage ( 26 ) connected to the control room ( 60 ) is connected to the fuel injector ( 10 ) is integrated. Fuel injector ( 10 ) according to one of claims 1 or 2, characterized in that the control valve ( 32 ) has a multipart base body, which has a valve needle ( 40 ) partially receiving valve body ( 36 ) and a sealing element ( 34 ) with a sealing seat ( 50 ) for the valve needle ( 40 ). Fuel injector ( 10 ) according to claim 3, characterized in that the valve body ( 36 ) and the sealing element ( 34 ) from a one-piece blank ( 74 ) are made by cutting. Fuel injector ( 10 ) according to claim 4, characterized in that the sealing element ( 34 ) at least one positioning section ( 70 ) for positioning the sealing element ( 34 ) relative to the valve body ( 36 ) having. Fuel injector ( 10 ) according to one of claims 3 to 5, characterized in that the control valve ( 32 ) as a sealing seat ( 50 ) for the valve needle ( 40 ) has a flat seat or a ball socket seat. Method for producing a control valve ( 32 ) for a fuel injector ( 10 ) according to one of the preceding claims, characterized in that a valve body ( 36 ) and a sealing element ( 34 ) of the control valve ( 32 ) are prepared by a. a blank ( 74 ), b. the blank ( 74 ) in a valve body ( 36 ) and a sealing element ( 34 ), c. on the sealing element ( 34 ) a sealing seat ( 50 ) and in the valve body ( 36 ) a valve needle guide ( 38a ) is incorporated, d. Valve body ( 36 ) and sealing element ( 34 ) are reassembled at the separation point. Method according to claim 7, characterized in that in step b the blank ( 74 ) is separated by breaking or wire EDM.