DE102006050032A1 - Injector, particularly common-rail injector, for injecting fuel into combustion chambers of internal-combustion engines, has control valve, which influences pressure in control chamber - Google Patents

Abstract

The injector (1) has an actuator (30), a valve piston (36), a particular axial load-balanced control valve (31) between a valve seat surface (40) and an axially operating opposite stroke stop face (47). A control valve influences the pressure in a control chamber (20), and thus a needle (8) is adjustable between one of the fuel flow releasing opening position and a closing position. The stroke stop face is conically shaped. The valve piston is designed as valve sleeve.

Description

State of the art

The The invention relates to an injector according to the preamble of the claim 1.

The EP 1 612 403 A1 describes a common rail injector with a pressure compensated in the axial direction control valve for locking 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 supplied via a pressure channel (throttle bore) with fuel from an annular chamber connected to a high-pressure fuel storage. By varying the fuel pressure within the control chamber, a nozzle needle is moved between an open position of a closed position, wherein the nozzle needle in its open position releases the fuel flow into the combustion chamber of an internal combustion engine. The axial travel of the valve sleeve is limited on the one hand by a stationary valve seat surface and on the other hand by a Hubanschlagsfläche. In the known injector, the Hubanschlagsfläche is formed by a flat annular surface of a locking ring which is received in a circumferential groove of a valve sleeve passing through the pin. The switching behavior of the control valve is affected by abutment bouncers of the valve sleeve on the flat Hubanschlagsfläche. For damping the abutment flare, it is known to form the anchor surfaces of a valve sleeve actuated solenoid drive as large as possible. In this case, however, there are large tolerance problems caused by the non-negligible influences of the fuel temperature, the air content and the return pressure. Furthermore, large-surface anchor surfaces cause a delay in the closing movement, which has a negative effect on the switching times and thus on the multiple injection capability of the injector.

Disclosure of the invention

Technical task

Of the The invention is therefore based on the object of proposing an injector, at the stop flash of the valve sleeve on the Hubanschlagsfläche simple way, with minimized negative effects on the switching time muted become.

Technical solution

These The object is achieved with the features of claim 1. The under claims give cheap Further developments of the invention. In addition, fall within the framework of Invention all combinations of at least two of the in the description, the drawing and / or the claims disclosed features.

Of the Invention is based on the idea, instead of a flat Hubanschlagsfläche a conically shaped Hubanschlagsfläche provide that with a corresponding counter-cone of the valve sleeve or one with the valve sleeve firmly Connected component cooperates. By providing a conical stroke stop will be a good stop damping reached and effectively prevented stop burr. It is with Advantage only a small radial Hubanschlagsfläche needed to a large hydraulic as well as mechanical stop damping to realize. This allows negative impact of the impact attenuation on the closing and / or opening time of the control valve can be significantly reduced. At the control valve it is preferably a pressure-balanced in the axial direction Valve. In a pressure balanced in the axial direction control valve no effect on the valve piston with the control valve closed or only minimal pressure forces in the axial direction. A realization of such an axial pressure balanced Control valve can be easily realized by that a valve sleeve with a sleeve bore is used, wherein the sleeve bore has the same diameter as the valve seat. The valve sleeve is located preferably with its inner diameter sealingly against the valve seat surface. By providing an axial-pressure compensated control valve only small spring forces and / or low actuator switching forces, in particular low magnetic forces for Actuation and / or needed to hold the control valve in its closed position. This again has beneficial effects. the stop behavior the valve piston, in particular a valve sleeve, as well as the maximum required Space. Furthermore you can smaller valve piston strokes and thus faster switching times are realized, whereby the Multiple injection capability is improved.

to Recording the acting in the axial direction of compressive forces provided with advantage a bolt, which in the axial direction within the valve sleeve is included. This bolt transmits the pressure forces to an injector body.

For this The bolt can either be firmly connected to the injector body or integral with this be educated. It is also conceivable that the bolt is not fixed Connection to the injector body has, but is supported only on this. This will be the bolt For example, from the fuel pressure acting on it to the injector pressed.

Of particular advantage is when the ke Gelförmige Hubanschlagsfläche is integrally formed on the bolt. As a result, the concentricity of Hubanschlagsfläche is significantly increased to the adjustment of the valve sleeve.

any Angle error between valve sleeve and Hubanschlagsfläche can according to a advantageous development of the invention can be reduced thereby that the valve sleeve, preferably high pressure-tight, with its inner circumferential surface on the outer surface of the Bolzens led is.

A additional damping the stop of the valve sleeve at the Hubanschlagsfläche can according to a advantageous development of the invention can be achieved thereby that inside the valve sleeve a damping room is provided, on the one hand by the valve sleeve and on the other hand, from the end face of the Bolzens is limited. To achieve the damping property of the Damping room with Advantage over at least one throttle hydraulically connected to a valve seat chamber, wherein the valve seat chamber in turn hydraulically with the control chamber connected is. about the valve seat chamber may release fuel from the control chamber when open Flow control valve in a range of low fuel pressure.

In Development of the invention is provided with advantage that the Actuator is designed as an electromagnetic drive, wherein at least an anchor plate is provided which is fixed to the valve piston, in particular the valve sleeve, connected or in one piece is formed with this to the valve piston during energization of the Electromagnetic actuator to adjust in the axial direction. Of course it is conceivable, instead of an electromagnetic drive, for example a Provide piezoelectric actuator.

Prefers has the valve piston, in particular at its upper, the valve seat surface facing away Area an inner cone, which interacts with an outer cone (Hubanschlagsfläche). Here are inner cone and outer cone form congruent with each other. Alternatively, it is conceivable the valve piston has an outer cone and with a shape-congruent inner cone-shaped Hubanschlagsfläche, for example on the injector body or on a component connected thereto, in particular a Bolt, cooperates.

Brief description of the drawings

Further advantages, features and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing; this shows in the only one 1 a highly schematic injector with a control valve, the valve sleeve is provided with an inner cone, which cooperates with a conical Hubanschlagsfläche.

Embodiment of the invention

In the only one 1 is an injector 1 shown. The injector 1 has an injector body 2 , a nozzle body 3 and one between nozzle body 3 and injector body 2 recorded throttle plate 4 on. A nozzle retaining nut 5 is with the injector body 2 screwed and braced so the nozzle body 3 and the throttle plate 4 against the injector body 2 ,

The nozzle retaining nut 5 Coaxially surrounds the throttle plate 4 as well as partially the injector body 2 and the nozzle body 3 , The nozzle body 3 passes through a through hole in the axial direction 6 the nozzle retaining nut 5 ,

Inside the nozzle body 3 is a guide hole 7 formed, in which an elongated, in this embodiment, one-piece nozzle needle 8th is guided axially movable. Instead of a one-piece nozzle needle 8th can also be used a multi-part nozzle needle, the individual parts are operatively connected. At a needlepoint 9 has the nozzle needle 8th a closing area 10 on, with which they are in close contact with one within the nozzle body 3 trained needle seat 11 can be brought.

If the nozzle needle 8th at the needle seat 11 is applied, that is, is in a closed position, the fuel outlet from a nozzle hole arrangement 12 blocked. Is she on the other hand from the needle seat 11 Raised, fuel may leak from between the nozzle needle 8th and the circumferential shell of the guide bore 7 trained high pressure room 13 and an annulus disposed below in the flow direction 14 to the Na delsitz 11 to the nozzle hole arrangement 12 flow and there are essentially injected under the high pressure (rail pressure) standing in a combustion chamber. The high pressure room 13 is via a supply line 15 hydraulically with a high-pressure fuel storage 16 connected, which is supplied for example via a radial piston pump not shown with fuel.

The nozzle needle 8th is by a biasing spring 17 biased toward its closed position. For this purpose, the biasing spring is supported 17 one at one on the outer circumference of the nozzle needle 8th held circlip 18 and at the other end to a sleeve-shaped component 19 which, in turn, on the throttle plate 4 supported. The component 19 and the throttle plate 4 can also be formed in one piece.

Within the component 19 is a tax chamber 20 arranged, via a pressure channel 21 with inlet throttle 22 supplied with high-pressure fuel. The pressure channel 21 connects the control chamber 20 with an annulus 23 inside the nozzle body 3 , where the annulus 23 via a supply line 24 with the high-pressure fuel storage 16 connected is.

The nozzle needle 8th protrudes over a hole 25 in the component 19 with its upper front side 26 in the control chamber 20 into it, allowing the fuel pressure within the control chamber 20 on the nozzle needle 8th acts in the axial direction.

The control chamber 20 is about one with a drain throttle 27 equipped drain hole 28 that both the component 19 as well as the throttle plate 4 interspersed, with a fuel drainage path 29 connected.

By means of an electromagnetic actuator 30 can be a pressure balanced in the axial direction control valve 31 the fuel flow to the drain line 29 lock.

By the preload spring 17 and the action of the in the control chamber 20 prevailing pressure on the face 26 is an axially directed toward the combustion chamber closing force on the nozzle needle 8th exercised. This closing force acts axially against an opening force due to the action of the in the high-pressure chamber 13 prevailing pressure on one at the nozzle needle 8th trained cone surface 32 on the nozzle needle 8th is exercised. Is the control valve 31 in a closed position and is the fuel drain through the drain hole 28 locked, the closing force is greater than the opening force in the stationary state, which is why the nozzle needle 8th then assumes its closed position. Will the control valve 31 then opened, fuel flows out of the control chamber 15 in a low-pressure room 33 and from there by the drainage path 29 from. The fuel pressure in the low pressure space 33 is between 0 and 10 bar, depending on the operating condition. The fuel pressure in the annulus 23 and in the high pressure room 13 is about 1800 to 2000 bar.

The flow cross sections of the inlet throttle 22 and the outlet throttle 27 are coordinated so that the inflow through the pressure channel 21 weaker than the drain through the drain hole 28 is and therefore with the control valve open 31 a net outflow of fuel results. The consequent pressure drop in the Steuerkam mer 15 causes the amount of closing force below the amount of opening force decreases and the nozzle needle 8th from the needle seat 11 takes off.

The low pressure room 33 is radially outward of a Ankerhubeinstellring 34 limited over which the actuator 30 at the throttle plate 4 supported.

The control valve 31 comprises a valve sleeve which can be displaced in the axial direction 36 (Valve piston) fixed to an anchor plate 37 connected or integrally formed therewith. The anchor plate 37 acts with an electromagnet 38 of the electromagnetic actuator 30 together and is radially within the Ankerhubeinstellrings 34 added.

The valve sleeve 31 is supported by a coil spring 39 on the injector body 2 off and off of the coil spring 39 in the direction of its closed position, ie in the direction of a valve seat surface 40 spring force.

The coil spring 39 is in a through hole 41 inside the actuator 30 added. Radial inside the coil spring 39 is a bolt 42 arranged, with his in the drawing plane upper end face 43 on the injector body 2 supported. With a lower section 44 is the bolt 42 inside the valve sleeve 36 recorded, with the valve necks 36 high pressure-tight in the axial direction at the lower portion 44 is guided.

The lower section 44 goes in its in the drawing level upper end over a conically shaped paragraph 45 in an upper section 46 with a larger diameter over. In other words, the two cylindrical sections 44 . 46 over the conical towards the needle point 9 tapered heel 45 , preferably in one piece, connected together. The outer surface of the cone-shaped heel 45 forms a Hubanschlagsfläche 47 for the installation of an inner cone 48 , which is in the drawing plane upper portion of the valve sleeve 36 is provided. The inner cone 48 is by chamfering the sleeve bore 49 produced. inner cone 48 and paragraph 45 (Outer cone) are formed congruent with each other and are in the open position of the control valve 31 , so from the valve seat 40 lifted valve sleeve 36 together and thus dampen Auflaufpreller between valve sleeve 36 and bolts 42 ,

The lower end face in the drawing plane 50 of the bolt 42 limits a damping space 51 inside the valve sleeve 36 , The damping chamber 51 is over a throttle bore 52 inside the throttle chamber floor 53 with a valve seat chamber 54 connected. During a movement of the valve sleeve 36 from the valve seat surface 40 in the direction of the Hubanschlagsfläche 47 gets fuel through the throttle hole 52 in the valve seat chamber 54 ver urges and flows from there into the low pressure room 33 and from there via the passage opening 41 to the drainage route 29 , This causes the fuel through the throttle bore 52 must flow, the closing movement and thus the impact of the inner cone 48 at the Hubanschlagsfläche 47 attenuated.

At the control valve 31 it is, as mentioned, a pressure-balanced in the axial direction valve. For this the valve sleeve lies 36 with its inner contour 35 on the annular valve seat surface 40 at. The diameter of the lower section 44 of the bolt 42 corresponds to the inner diameter of the valve seat chamber 54 and the inner diameter of the damping chamber 51 , To optimize the valve design, the lower section 44 of the bolt 42 also have a slightly smaller diameter than the valve seat surface 40 ,

Claims (10)

Injector for injecting fuel into combustion chambers of internal combustion engines, in particular common-rail injector ( 1 ), with an actuator ( 30 ), which has a valve piston ( 36 ) of a particular axialdruckausbalanced control valve ( 31 ) between a valve seat surface ( 40 ) and an opposite Hubanschlagsfläche ( 47 ) is arranged axially actuated, wherein by means of the control valve ( 30 ) the pressure in a control chamber ( 20 ) and thereby a nozzle needle ( 8th ) is adjustable between a fuel flow releasing opening position and a closed position, characterized in that the Hubanschlagsfläche ( 47 ) is conically shaped. Injector according to one of the preceding claims, characterized in that the valve piston ( 36 ) as a valve sleeve ( 36 ) is trained. Injector according to claim 2, characterized in that in the valve sleeve ( 36 ) one fixed to an injector body ( 2 ) connected, or integrally formed therewith or on this supporting pin ( 42 ) is recorded. Injector according to claim 3, characterized in that the conical Hubanschlagsfläche ( 47 ) on the bolt ( 42 ) is trained Injector according to one of claims 3 or 4, characterized in that the valve sleeve ( 36 ) high pressure-tight on the bolt ( 42 ) is guided. Injector according to one of claims 3 to 5, characterized in that within the valve sleeve ( 36 ) one of the bolts ( 42 ) limited damping space ( 51 ) is arranged. Injector according to claim 6, characterized in that the damping chamber ( 51 ) via at least one throttle bore ( 52 ) hydraulically with a valve seat chamber ( 54 ) connected is. Injector according to one of the preceding claims, characterized in that the actuator ( 30 ) is designed as an electromagnetic drive and with at least one anchor plate ( 37 ), which is fixed to the valve piston ( 36 ) is connected or integrally formed therewith. Injector according to one of the preceding claims, characterized in that the valve piston ( 36 ) or a component connected to it, an inner cone ( 48 ) for engagement with the outer cone-shaped Hubanschlagsfläche ( 47 ) having. Injector according to one of claims 1 to 8, characterized in that the valve piston ( 36 ) or a component connected to it an outer cone for engagement with the inner cone-shaped Hubanschlagsfläche ( 47 ) having.