EP1000240B1 - Fuel injection valve for internal combustion engines - Google Patents

Abstract

An actuator (100) is actively connected to a closing member (370) by means of a tappet (200), whereby the closing member (370) is located in a valve chamber (345). Said member and a valve seat (350) extending conically as part of a servo valve (340) form a seal resistant to high pressures. The cross section of the closing member (370) has a mushroom-shaped embodiment, whereby the closing head has a semispherical shape and a central flattened area enabling the tappet (200) to have an enlarged bearing area. The butt of the closing member is surrounded by a valve spring (390). The closing member (370) is preferably formed from a solid sphere.

Description

The invention relates to a fuel injection valve according to the preamble of claim 1.

Such a fuel injection valve is from document EP 0 816 670 A1 known. The well-known fuel injection valve, contains a servo valve that serves to hydraulically open it and closing the fuel injector, especially the beginning and end of the injection process to be determined exactly in time. In the valve chamber of the servo valve is introduced a spherical closing body that over a plunger is operatively connected to an actuator. The Closing body forms together with a conical, first Valve seat of the valve chamber a high pressure resistant seal. When the actuator is deflected, the closing body is moved from the first The valve seat is lifted, causing the servo valve to open (2/2-way valve). Another form of training is in Valve chamber another, the first valve seat in the axial Arranged opposite conical sealing seat, the closing body in the deflected state of the actuator covers the other valve seat and thus a hydraulic one Lock occurs (3/2-way valve).

From DE 36 27 865 A1 a check valve with one is known a ball-made movable valve member, the one spherical sealing surface interacting with the valve seat has and guided radially in a housing bore and corresponding recesses for the flow passage has that of the medium region to be controlled between Valve seat and guide to the downstream of the valve member Lead valve area.

The object of the invention is to design the servo valve improve.

The object of the invention is achieved with a device and a Process solved as in the independent patent claims are described.

Further advantageous developments and improvements of the invention are specified in the dependent claims.

An advantage of the invention is the life of the Increase servo valve. Another advantage is that small design of the servo valve and in the simple manufacturing process of the closing body.

The special shape of the closing body is advantageous as a rotationally symmetrical body on one end (Head) has a partial circular termination and in Longitudinal direction to the opposite end face in passes a slim stem with a smaller diameter. The cross-sectional shape of the closing body is approximate mushroom-shaped.

The head of the closing body has a central one Flat on which a plunger rests, which with a Actuator is connected. This creates an enlarged effective area reached between plunger and closing body, which is advantageous for less wear and less risk of Tilting the closing body leads.

The stem of the closing body is surrounded by a valve spring, which the closing body towards the first valve seat biases. This makes a compact one advantageous Size of the servo valve and a stabilization of the Closing body reached.

The stem of the closing body is closed in a spherical shape, the partial spherical shape together with a sealing seat advantageously serves as a sealing surface.

The closing body is preferably made from a solid ball. This results in low manufacturing tolerances and a simple manufacturing process.

Figur 1:

einen Längsschnitt durch ein Kraftstoffeinspritzserventil mit einem Servoventil in einer ersten Ausführungsform;

Figur 2:

einen Längsschnitt durch ein Kraftstoffeinspritzventil mit einem Servoventil in einer zweiten Ausführungsform;

Figur 3:

einen Querschnitt des Schließkörpers mit einer Ventilfeder

The invention is explained in more detail below with reference to the figures; show it:

Figure 1:

a longitudinal section through a fuel injection valve with a servo valve in a first embodiment;

Figure 2:

a longitudinal section through a fuel injection valve with a servo valve in a second embodiment;

Figure 3:

a cross section of the closing body with a valve spring

Figure 1 shows a fuel injection valve with a 2/2-way valve (Servo Valve). The fuel injector with rotationally symmetrical basic body shape is axial in the longitudinal direction divided into different bodies.

A controllable actuator 100, preferably a piezoelectric one Actuator, with a closing body 370 over a plunger 200 in operative connection. The plunger 200 is in a central Guide bore 310 of a servo body 300 out. The servo body 300 additionally has a fuel channel 320, a Return channel 330 and a central valve chamber 345. The return channel 330 protrudes laterally into the guide bore 310 and is connected to a fuel tank. The pilot hole 310 goes over a conically opening first Valve seat 350 into the valve chamber 345. In the valve chamber 345, the closing body 370 is introduced, which together with the first valve seat 350 in the closed state forms a high pressure resistant seal. The closing body 370 is mushroom-shaped, the stem of the closing body 370 is surrounded by a valve spring 390 which is in the valve chamber 345 is arranged and on the closing body 370th exerts a spring force directed towards the first valve seat 350.

The shape of the closing body 370 is described in the description of FIG Figure 3 explained in more detail.

The valve chamber 345, the closing body 370, the valve spring 390 and the first valve seat 350 form a servo valve 340, which is actuated by the actuator 100 via the plunger 200. By opening the actuator 100 from the idle state the servo valve 340, creating a hydraulic connection (Drain) between the valve chamber 345 and the fuel tank via the guide bore 310 and the return channel 330 becomes. On the one opposite the guide bore 310 Side is the valve chamber 345 from an intermediate body 400 limited to the servo body 300 in the axial direction followed.

The intermediate body 400 has a fuel channel 430, one Connection channel 420 and an inlet channel 410, which the Fuel channel 430 connects to the valve chamber 345 and which has an inlet throttle 415 that controls the fuel flow confined in the valve chamber 345.

The nozzle body axially adjoining the intermediate body 400 500 has a central nozzle guide 510, in the axial Direction of a nozzle needle 600 is guided. The nozzle needle 600 and the nozzle body 500 form with their valve tips 640 or with its tapered, second valve seat 540 a valve 640, 540 that controls fuel injection one or more arranged at the tip of the nozzle body 500 Controls spray holes 550 in a combustion chamber. In the Nozzle needle 600 ring heels are incorporated, which by the Fuel pressure is axial, from the second valve seat 540 force directed away on the nozzle needle 600.

The rear of the nozzle needle 600 protrudes into a control chamber 440, via the connecting channel 420 with the valve chamber 345 is connected. The pressure in the control chamber 440 exerts one axial, directed in the direction of the second valve seat 540 Force on the nozzle needle 600.

A movement axially towards the intermediate body 400 the nozzle needle 600 opens the valve 640, 540, an opposite one Movement closes valve 640, 540.

By opening the servo valve 340, fuel flows from the Valve chamber 345 via the guide bore 310 and the return channel 330 in the fuel tank. Through the inlet throttle 415 not enough fuel can flow into the inlet channel 410, the fuel pressure in the valve chamber 345 and the control chamber connected to it via a connecting channel 420 Hold 440. The reduced pressure in the control chamber 440 leads to a deflection of the nozzle needle 600 from second valve seat 540 away and thus at the beginning of the injection process. The actuator 100 pulls itself into its rest position the closing body 370 returns because of the pressure difference between the valve chamber 345 and the return passage 330 and because of the restoring force of the valve spring 390 at first Valve seat 350 back and interrupts the hydraulic Connection between the valve chamber 345 and the return channel 330 (closed position). It flows through the inlet throttle 415 Fuel from the fuel channel 430 into the valve chamber 345 and the control chamber 440, whereby the high pressure in the control chamber 440 is rebuilt. This will make the Nozzle needle 600 pressed onto the second valve seat 540 so that the injection process through the spray holes 550 is ended.

FIG. 2 shows a fuel injection valve from FIG. 1 a 3/2-way valve (servo valve). The difference to the fuel injector from Figure 1 is in the inlet channel 410 there is no inlet throttle 415. Furthermore points out the difference to Figure 1, the valve chamber 345 on the first Valve seat 350 opposite end a tapered Sealing seat 360, which in connection with the lower Body part of the locking member 370, the locking foot 386 (see. Fig. 3) forms a high pressure resistant seal. This seal closes when actuator 100 is deflected, i.e. when open Drain, the inlet channel 410 from the valve chamber 345 hydraulically from.

This 3/2-way valve works as follows: In The non-deflected state of the actuator 100 is the control chamber 440 hydraulic with the high pressure fuel connected in the fuel channel 430. The hydraulic connection between the valve chamber 345 and the return duct 330 is interrupted. In the deflected state of the actuator 100 is the connection between the inlet channel 410 and the valve chamber 345 interrupted, the control chamber 440 is over the Valve chamber 345 hydraulically connected to the return channel 330. The deflection of the actuator 100 is thus in the Control chamber 440 achieves a rapid pressure drop, causing the fuel injection valve opened quickly becomes. If the actuator 100 goes from the deflected state into its Back to sleep, the control chamber 440 builds its pressure via the valve chamber 345 and the inlet channel 410 quickly and inhibited by no inlet throttle 415 again, whereby a the fuel injection process ended quickly becomes. In addition, the amount of fuel that is opened when open Servo valve 340 flows through the return channel 330.

FIG. 3 shows a cross section of the closing body 370 with the valve spring 390 in a preferred embodiment.

The closing body 370 is rotationally symmetrical along its longitudinal axis 371 educated. The closing body 370 is from Tappet 200 in FIG. 1 seen axially divided into one Locking head 375, in an indentation 380, in a locking handle 384 and a closing foot 386.

The closing head 375 is on the side of the first valve seat 350 partially spherical with a first radius R1 and has a central, preferably circular, flat head 376 on, making the plunger 200 a compared to the pure partial spherical shape has an enlarged contact surface. The end face with that of the plunger 200 on the flat head 376 rests, is also flat, so that the plunger 200 with a large area on the head flat 376 rests. The enlarged contact surface is advantageous a lower material load on the closing body 370 and the plunger 200 and thus less wear of the material achieved, which enables an increased service life. Farther is improved by head flattening 376 Guidance of the closing body 370 achieved by the plunger 200, since the end face of the plunger 200 parallel to the head flattening 376 is arranged.

The closing head 375 has on its the head flat 376 axially opposite bottom on a paragraph that to leads to a reduction in diameter and the beginning of indentation 380. Continuing in the axial direction the paragraph goes over a curve into a cylindrical one Stalk over which is conical over another rounding expanded and over a first ring edge in the cylindrical Lock handle 384 with an enlarged diameter merges. The locking handle 384 ends at a further ring edge and merges into the lock foot 386, which holds the lock handle 384 preferably terminates part-spherically with a second radius R2. The indentation 380 is essentially a annular recess formed.

The first radius R1 is preferably equal to the second radius R2, since the closing body 370 is made from a solid ball is shown by the dashed line is indicated in Figure 3. The solid ball is preferably made made of metal and is processed by milling, turning or similar that the closing body 370 results from what is advantageous represents a simple manufacturing method of the closing body 370. The part-spherical surfaces of the closing body 370 are designed so that they are together with the first valve seat 350 and the sealing seat 360 each a high pressure resistant Allow sealing, the partial spherical shape advantageous even with a slight tilt of the closing body 370 Sealing enables. The surfaces of the partial spherical surfaces have a low roughness to make the seals highly pressure-resistant close. Be advantageous by shaping the Closing body 370 made of a solid ball with low manufacturing tolerances, achieved especially in the area of the sealing surfaces.

The indentation 380 and the locking handle 384 are from one Valve spring 390 includes. The valve spring 390 is against one End on the intermediate body 400 (the bottom of the valve chamber 345, p. Figure 1 or Figure 2) and at the other end on the bottom of the closing head 375, the spring force of Valve spring 390 the closing body 370 against the first valve seat 350 and pushes the plunger 300. The indentation 380 serves that an end face of the valve spring 390 approximately abuts vertically on the underside of the closing head 375 and so advantageously essentially axial forces on the spring be exercised. The valve spring 390 also snaps into place the indentation 380 and is therefore advantageously mechanical firmly connected to the locking member 370.

Due to the arrangement of the valve spring 390 and the closing body 370 to each other is advantageously a compact design of the servo valve 340.

The valve spring 390 is preferably close to the locking handle 384 so that the valve spring 390 and the closing body 370 are laterally stabilized.

• Der Stößel 200 liegt mit seiner Stirnfläche auf der Kopfabflachung 376 auf und bewirkt eine stabilisierende Kraft auf den Schließkörper 370, die wodurch ein Verkanten des Schließkörpers 370 erschwert wird.
• Die Ventilfeder 390 liegt mit einer Stirnseite an der Unterseite des Schließkopfes 375 und mit der gegenüberliegenden Stirnseite auf dem Boden der Ventilkammer 345 ringförmig an. Durch die axial gerichtete, ringförmig gleichmäßig auf den Boden der Ventilkammer 345 und die Unterseite des Schließkopfes 375 wirkende Federkraft der Ventilfeder 390 wird der Schließkörper 370 stabilisiert.
• Die Ventilfeder 390 umfaßt den Schließstiel 384 eng und hindert somit den Schließkörper 370 am Verkanten.

An advantageous, stabilized guidance of the closing body 370 improves the dynamic behavior of the servo valve 340 and accelerates its opening and closing, which is achieved by the following features:

• The plunger 200 rests with its end face on the head flattening 376 and brings about a stabilizing force on the closing body 370, which makes tilting of the closing body 370 more difficult.
• The valve spring 390 rests in a ring shape with one end face on the underside of the closing head 375 and with the opposite end face on the bottom of the valve chamber 345. The closing body 370 is stabilized by the axially directed spring force of the valve spring 390, which acts uniformly in a ring on the bottom of the valve chamber 345 and the underside of the closing head 375.
• The valve spring 390 tightly embraces the closing stem 384 and thus prevents the closing body 370 from tilting.

The valve spring 390 is preferably as a spiral spring or as Hollow spring executed.

Claims (6)

1. Fuel injection valve with a control chamber (440), which is connected to an intake channel (410), whereby the pressure in the control chamber (440) is actively connected to a nozzle needle (600) and the pressure in the control chamber (440) controls the nozzle needle (600),
   with a servo valve (340), which comprises a closing element (370) and an associated first valve seat (350), whereby the servo valve (340) is arranged between the control chamber (440) and a return flow channel (330) and the closing element (370) seals off a discharge in a closed position,
   with an actuator (100) which activates the closing element (370),
   whereby the closing element (370) has a closing head (375) in the form of a partial sphere, which is associated with the first valve seat (350),
   characterized in that
   the closing head (375) merges into a closing strut (384),
   a valve spring (390) is provided, which surrounds the closing strut (384) and pretensions the closing head (375) against the first valve seat (350),
   the closing element (370) has a central flattened head area (376), which is associated with the first valve seat (350),
   the actuator (100) is actively connected to a plunger (200), which is guided through the first valve seat (350) and rests on the flattened head area (376).
2. Fuel injection valve (340) according to Claim 1, characterized in that the closing strut (384) has a closing foot (386), which terminates the closing strut (384) in the form of a partial sphere.
3. Fuel injection valve (340) according to one of Claims 1 to 2, characterized in that
   a sealing seat (360) is configured, which is opposite the first valve seat (350), and
   the closing foot (386) and the sealing seat (360) form a high-pressure-resistant seal when the discharge is open.
4. Fuel injection valve (340) according to one of Claims 1 to 3, characterized in that the radius (R1) of the closing head (375) is equal to the radius (R2) of the closing foot (386).
5. Fuel injection valve (340) according to one of Claims 1 to 4, characterized in that the closing element (370) has a notch (380), into which the valve spring (390) is latched.
6. Fuel injection valve according to Claim 1, characterized in that the closing element (370) is formed by incorporating recesses in a complete sphere.

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