EP2276922B1 - Fuel injector with solenoid valve - Google Patents

Description

State of the art

DE 196 50 865 A1 and WO 0235080 A2 refer to a solenoid valve for controlling the fuel pressure in a control chamber of an injection valve, such as a common rail injection system. About the fuel pressure in the control chamber, a stroke movement of a valve body is controlled with an injection port of the injection valve is opened or closed. The solenoid valve comprises an electromagnet, a movable armature and a valve member which is moved with the armature and acted upon by a valve closing spring in the closing direction and which cooperates with the valve seat of the valve member to control the fuel discharge from the control chamber.

There is known a common rail fuel injector with a two-piece armature actuated by a solenoid valve. The armature exerts the closing force on a valve ball in the currentless case. When the electromagnet is energized, the armature moves upwards by the armature stroke, against the closing force acting on the valve ball and opens a discharge valve. An armature guide, which is bolted firmly in the injector body of the fuel injector, receives the anchor bolt. On the anchor bolt, the anchor plate is guided, which in turn is attracted by the electromagnet. The anchor bolt may tip over due to the guide clearance in the anchor guide. The anchor plate in turn can tilt on the anchor bolt, so that the total tilt of the assembly anchor bolt / anchor plate with respect to the injector main axis can be determined as the sum of the leadership games.

In fuel injectors in which a solenoid valve actuator is arranged in the head region, the solenoid valve actuator and the switching valve are screwed to the injector body. The bearing surface for the switching valve is a valve piece, which is supported on a shoulder in the injector body. The switching valve comprises the movable armature. In the valve piece a releasable by a closing element and closable valve seat is executed. The Support for the solenoid valve actuator is a higher-lying shoulder in the injector, on which the Ankerhubeinstellscheibe rests. The position of both elements, which work in close interaction with each other, is thus determined over a relatively long tolerance chain. In particular, an important measure is the parallelism of the anchor plate top to the pole face of the electromagnet. Poor parallels or large differences in these parallels from one injector to another result in inaccurate injections, wear, or an injection quantity spread from specimen to specimen.

With fuel injectors currently under development, an angular error between solenoid valve actuator and switching valve is to be minimized. In a centrally arranged guide bore of the armature, a cylindrical pin is received, which allows the pressure balance of the switching valve. In the closed state of the switching valve, this pin is pressed from the bottom with system pressure, i. the pressure prevailing in the high-pressure accumulator body (common rail) of the high-pressure accumulator injection system pressure applied. The resulting force is supported at a location in the solenoid valve actuator, for example on a support disk. If a large angular error occurs due to long tolerance chains between solenoid valve actuator and switching valve, this angular error degrades the perpendicularity between the support plane in the solenoid valve actuator and the anchor bolt. Depending on the design of a contact point, it is therefore to initiate shear forces in the anchor bolt. As a result, the anchor bolt is bent and thus tilts the armature assembly in addition to the angular error farther out of the vertical position. This results in an undesirable friction component in the armature guide, which acts as a disturbance in the injection process and also changes the injected amount.

Disclosure of the invention

According to the invention, in a solenoid valve serving as an actuator for a fuel injector, the magnet group, in particular the magnet holder, is placed on a modified armature stroke adjusting disk. The modified Ankerhubeinstellscheibe acting in the sense of a plate spring, based on a valve clamping screw (or an armature guide), which in turn rests on the end face of a valve piece. The parallelism between a plan side of the armature plate and a pole face of the magnetic core is improved because the reference for the solenoid valve and the Schaltvenril is respectively the top of the valve spool biased valve member on which both the leadership of the armature and the bearing surface of the valve piece are present , Guide and bearing surface can be ground in one clamping, whereby the different surfaces have a good geometric tolerance with respect to each other. In particular, the guide surface of the armature assembly in the valve piece on an improved squareness with respect to the support of the valve clamping screw. The valve clamping screw as well as the modified Ankerhubeinstellscheibe can be ground double plan, whereby the parallelism of the same to each other is further improved. Deviations from perpendicularity, ie perpendicularity errors can only be adjusted by errors between the guide and the upper side of the armature as well as by parallelism errors within the magnet holder between a lower support on the modified Ankerhubeinstellscheibe and the support for the magnetic core. In the manufacture of the armature, the guide surface to the valve piece and the upper anchor plate surface machined with very high surface quality to each other, preferably ground. Furthermore, in the magnet holder, ie the magnet sleeve whose lower support forms the support of the magnetic core, rotated in a Aufspannvorgang so that can achieve small component tolerances.

In contrast, in the solution known so far from the prior art, the deviation of the parallelism between the upper side of the valve piece (interface valve) and the underside of the valve piece is included in the parallelism errors between the anchor plate top side and the pole face. These are particularly large, since the valve piece is rotated on the support to the injector and the lower cylindrical approach. For grinding the valve piece top, the valve piece is received on the cylindrical shoulder. This means that in the solution of the prior art, a poorly twisted surface and a strapping add up to a large error between the two surfaces.

The Ankerhubeinstellscheibe can be modified so that it is no longer supported on a shoulder in the injector body, but directly from a flat surface of the valve clamping screw, with which the valve member is biased in the injector body. The magnet armature of the magnet group acting on the modified armature stroke adjusting disk is connected to an external thread on the injector body of the fuel injector by means of a magnetic clamping nut. The proposed solution improves the parallelism between the upper side of the armature assembly, in particular an armature plate and the end face of the pole face of the magnet core assigned thereto. The orientation of the armature assembly, including an armature and an anchor bolt, is defined by a guide on top of the valve member. The orientation of the magnet group and thus of the electromagnet are defined by the upper plane surface. The guide and the plane surface are machined in one clamping, so that the armature assembly is aligned with respect to the electromagnet with almost no error.

In an advantageous embodiment of the invention underlying the idea, the leakage amount from the leadership of preferably needle-shaped injection valve member and the valve piston guide, which emerges from the oblique holes in the injector, not - as in the prior art - via a recess in the injector in the Anchor space passed, but can flow into a space between the Ankerhubeinstellscheibe and the injector and flow from there via initial interruptions in the low-pressure side return.

Brief description of the drawings

Figur 1

Einen Kraftstoffinjektor mit einem Magnetventil gemäß des Standes der Technik,

Figur 2

eine Ausführungsvariante des erfindungsgemäß vorgeschlagenen Magnetventils, montiert im Kopfbereich eines Kraftstoffinjektors,

Figur 3

eine Darstellung im vergrößerten Maßstab in dem Bereich gemäß Figur 2 in dem der Magnethalter des Magnetventils auf der modifizierten Ankerhubeinstellscheibe aufsteht,

Figur 3.1

eine alternative Ausführungsform, bei der sich die Ankerhubeinstellscheibe auf einer Schulter des Ventilstücks abstützt,

Figur 4

eine Darstellung der erfindungsgemäß vorgeschlagenen Rücklaufführung und

Figur 5

Darstellungen des Magnethalters in Seitenansicht und in einer Ansicht von der Hinterseite.

It shows:

FIG. 1

A fuel injector with a solenoid valve according to the prior art,

FIG. 2

an embodiment variant of the inventively proposed solenoid valve, mounted in the head region of a fuel injector,

FIG. 3

a representation on an enlarged scale in the area according to FIG. 2 in which the magnet holder of the solenoid valve stands up on the modified armature stroke adjusting disc,

Figure 3.1

an alternative embodiment in which the Ankerhubeinstellscheibe is supported on a shoulder of the valve piece,

FIG. 4

a representation of the inventively proposed return flow and

FIG. 5

Representations of the magnet holder in side view and in a view from the rear.

FIG. 1 shows a fuel injector which is actuated by means of a solenoid valve according to the prior art.

A fuel injector 10 is formed symmetrically to the injector axis 12 and comprises an injector body 14. In the injector body 14, a first support shoulder 116 is executed, on which a valve piece 32 is supported. The fuel injector 10 includes a solenoid valve 20 having a magnetic core 22 and an embedded in the magnetic core 22 Magnetic coil 24 has. The magnetic coil 24 has with its end face to an end face of an armature 28. The end face of the magnetic coil 24 is identified by reference numeral 26 and represents a pole face. Furthermore, the injector body 14 comprises a second support shoulder 30, on which according to FIG FIG. 1 a previously used Ankerhubeinstellscheibe 18 is supported. On this, in turn, a magnet holder 52 of the solenoid valve 20 is supported. As shown in the illustration FIG. 1 Furthermore, the valve piece 32 is biased by a valve clamping nut 34.

FIG. 1 further shows that in the injector body 14 of the fuel injector 10, an oblique return bore 36 extends, which opens into a recess 38. The recess 38 is located below the Ankerhubeinstellscheibe 18 supported in the injector body 14 by the second support shoulder 30 to allow outflow of fuel, which escapes through guide leakage at the Einspritzventilgliedführung and the valve piston guide, via the return 36, the recess 38 is below in the injector the previously used Ankerhubeinstellscheibe 18 made.

Models:

FIG. 2 shows an embodiment of a fuel injector, which is actuated by the inventively proposed solenoid valve. For the following statements applies that the magnet holder may be formed one or more parts, which may be dependent on manufacturing and Möntageanforderungen. For the following explanations applies that under magnetic holder 52 both embodiments are subsumed.

At the in FIG. 2 illustrated embodiment of the erfindungemäß proposed solution, the valve member 32 is located on the first support shoulder 116 of the injector body 14. The valve member 32 is acted upon by means of the valve clamping screw 34 with axial force, so that the interface between the valve member 32 and the injector body 14 is high pressure-tight. The valve piece 32 has a neck, in whose guide 72, the armature assembly, in particular an armature 60, is movably guided in the vertical direction. In armature 60, an anchor bolt 56 is guided, which ensures the pressure balance of the solenoid valve 20. The armature guide 72 also represents a sealing point, since it has an extremely low clearance and therefore allows only minimal leakage.

On the valve clamping screw 34, with which the valve piece 32 is placed against the first support shoulder 116 of the injector body 14, a modified Ankerhubeinstellscheibe 62 is placed. This centered by means of its outer diameter with respect to the injector body 14. The thickness of the modified Ankerhubeinstellscheibe 62 is determined to the Set the length of the path of the axially movable armature 60 to a predetermined value, which is referred to as anchor stroke. The thickness of the modified Ankerhubeinstellscheibe 62 is therefore dependent on the distance between the plan side of the armature 60 to the upper bearing surface of the valve spanner 34 and the Rückstellmaßes, around which the magnetic core 22 of the magnetic group 50 behind the lower support of the magnet holder 52 back. On the upper plan side of the modified Ankerhubeinstellscheibe 62 of the magnet holder 50 is placed and screwed by means of a magnetic clamping nut 108 against the injector 14.

During tightening of the magnetic lock nut 108 with a defined tightening torque, the modified armature lift adjusting washer 62 acts like a Belleville spring. How out FIG. 2 As can be seen, the modified Ankerhubeinstellscheibe 62 is on a flat side 96, but not on the second support shoulder 30 in the injector 14 on. Thereby, the modified Ankerhubeinstellscheibe 62 according to the solution in FIG. 2 be deformed in the axial direction, in particular in the radially outer region in the form of a plate spring. In this region of the modified armature stroke adjusting disc 62, which is no longer supported by the on side 96 of the valve nut 34, the modified Ankerhubeinstellscheibe 62 is axially deformable and can be elastically deformed by impressed axial forces.

By varying the axial force and the tightening torque of the magnetic clamping nut 108, the armature stroke in the mounted fuel injector 10 can be changed. This serves to reduce the armature stroke tolerance of already delivered fuel injectors 10 and thus to improve the output and to reduce the required injection quantity tolerance.

The modified Ankerhubeinstellscheibe 62 is preferably flat ground in its simplest embodiment and can be processed on both planets with high surface quality. However, the Ankerhubeinstellscheibe 62 may also have a different shape in longitudinal section, such. Conically curved or the like configured, if necessary. The modified Ankerhubeinstellscheibe 62 is preferably carried out always rotationally symmetrical. On the shape of the modified Ankerhubeinstellscheibe 62 in particular the desired elasticity in the region below the magnet holder 50 can be adjusted.

When the fuel injector is pressurized with system pressure at high pressure port 94 received laterally on the injector body 14, system pressure is applied to the armature pin 56 at the bottom thereof. The resulting axial force is absorbed in the magnet group, for example on a support disk 54. However, the support disk 54 may also be omitted. As from the cut die Resulting axial force is absorbed in the magnet group, for example on a support plate 54. However, the support disk 54 may also be omitted. As from the sectional view according to FIG. 2 Furthermore, the magnet group 50 includes, in addition to the magnet holder 52, which stands up on the upper plan side of the modified Ankerhubeinstellscheibe 62, the magnetic core 22, in turn, the magnetic coil 24 is recessed. The magnet coil 24 is contacted within the magnet group 50 by coil contacts 56, which enable energization of the magnet coil 24 of the magnet group 50. FIG. 2 shows, furthermore, that the armature assembly, in particular the armature 60, is acted upon in the closing direction by a closing spring 78 which is supported on the support disk 54. When not energized magnetic group 50, the armature 60 is employed with its lower sleeve-shaped projection, the valve seat, against the valve piece 32. As a result, a drainage channel 80, which extends through the valve piece 32, is closed, so that a control chamber 84, from which the drainage channel 80 extends, is not depressurized. In this state of the valve seat, the control chamber 84 is closed in the valve piece 32. The control chamber 84 is acted upon by a laterally the valve piece 32 passing through inlet throttle 88 with fuel under system pressure. This fuel is present in a high pressure chamber 92, which in turn by a in FIG. 2 only indicated high-pressure connection piece is acted upon by fuel under system pressure. The system pressure is shown in one in the illustration FIG. 2 Not shown high-pressure storage body generated for example via a high-pressure pump or the like. The system pressure, which the injector body 14 of the fuel injector 10 according to FIG. 2 is in the order of 1600 to 1800 bar, but may also be above the stated values.

The high-pressure chamber 92 in the injector body 14 is sealed by a sealing ring 90. The discharge channel 80 extending from the control chamber 84 in the vertical direction through the valve piece 32 with at least one discharge throttle point 82 opens in the bottom of a pressure chamber within the valve piece 32. This pressure chamber is closed by the armature 28.

The control chamber 84 is delimited by an end face of the preferably needle-shaped injection valve member 86, which releases or closes at least one injection opening provided at the combustion chamber end of the fuel injector 10, depending on the pressurization or pressure release of the control chamber 84. The control chamber 84 is further limited by the wall of the valve member 32, which is also symmetrical to the injector 12 and is employed via the valve clamping nut 34 against the first support shoulder 116 in the injector body 14.

The representation according to FIG. 3a is an enlarged section of the fuel injector according to FIG. 2 in the area of the magnet holder.

As the enlarged view according to FIG. 3a shows the magnetic core 22 is accommodated therein with magnetic coil 24 via at least one plate spring 100 against a collar on the underside of the magnet holder 52 employed. The front side of the magnetic core 22 and the magnetic coil 24 embedded therein form a pole face 26, which is opposite to the upper plan side of the armature assembly, in particular the armature 60. From the illustration according to FIG. 3a It can be seen that the anchor bolt 56 of the armature assembly with its lower end face the drain passage 80 is opposite. The anchor bolt 56 is supported via the support plate 54 and serves as a guide of the closing spring 78. About the anchor bolt 56, the pressure balance of the solenoid valve 20 is ensured. FIG. 3 shows that the magnetic coil 24 of the magnetic group 50 in the magnet holder 52 is energized by a coil contact 76.

FIG. 3a moreover shows that the magnet holder 52 is screwed to the injector body 14 via the magnetic clamping nut 108. The magnet holder 52 is supported with a lower annular surface on the upper side of the modified Ankerhubeinstellscheibe 62. The Ankerhubeinstellscheibe 62 is - as already mentioned above - centered with its outer diameter in the injector 14. The modified Ankerhubeinstellscheibe 62 is supported with its radially inner region on a flat side 56 of the valve clamping screw 34 and not - as in the embodiment according to the prior art according to FIG. 1 - At a running in the injector 14 second support shoulder 30th

The inventively proposed modified Ankerhubeinstellscheibe 62 gives the magnet holder 52 corresponding to the defined tightening torque with which the magnetic clamping nut 108 is tightened, a very high elasticity and also allows a later modification of Ankerhubes due to relative movement of the pole face 26 to the plan side of the armature assembly, in particular the armature 60th

FIG. 3a shows that at least one interruption 98 is provided at the lower annular surface of the magnet holder 52 serving as a contact surface. This serves as a modified return line 102, via which leakage amount from the nozzle and the valve piston can be passed into the return-side low-pressure region. At the in FIG. 1 In the illustrated embodiment according to the prior art, the return takes place via a bore 36 running obliquely in the injector body 14. In the embodiment according to FIG FIG. 1 is the mouth of the return 36 through the there illustrated, previous Ankerhubeinstellscheibe closed, so that it is necessary to form the recess 38 in the injector 14.

As in particular from the illustration according to FIG. 5 As can be seen, the annular contact surface on the lower end face of the magnet holder 52 is provided at several points with interruptions 98, so that there is a composed of several interruptions return opening 102. About this, the diverted fuel flow between the modified Ankerhubeinstellscheibe 62 and the bottom of the magnet holder 52 in the low-pressure side back space and are passed from there together with the escaped when opening the solenoid valve 20 outflow in the return of the fuel injector 10.

For completeness, it should be mentioned that the magnet holder 52 has at its periphery above its annular contact surface a receiving groove 106, in which an O-ring 104 is inserted. About the O-ring 104, the magnet holder 52 is sealed against the injector body 14 according to the tightening torque of the magnetic clamping nut 108.

FIG. 3a moreover shows that the valve piece 32 has a neck-shaped portion which forms the armature guide 72. In this, the armature assembly, which is preferably designed as an anchor 60, performed with minimal play. The armature guide 72, by virtue of its design, is a sealing guide in which sealing is effected between the anchor bolt 56 and the armature assembly 60, so that minimal leakage is ensured.

FIG. 4 shows the inventively proposed solenoid valve. A support, with which the valve clamping screw 34 rests on a flat surface on the valve piece 32 is indicated by reference numeral 70. The recess 38 is shown in the illustration FIG. 4 not shown; this is not necessary because the return bore 36 is open at the top, since the modified Ankerhubeinstellscheibe 62 does not rest on the injector body 14.

In the illustration according to FIG. 3b an alternative embodiment of the storage of Ankerhubeinstellscheibe 62 is shown. This is located in the FIG. 3b illustrated embodiment on an upper shoulder of the guide of the valve piece 32. This is in turn secured by the valve clamping nut 34 in the injector 14. On the valve piece 32 is the armature guide 72, in which the armature assembly 60 is guided. Partial is in FIG. 3 the reproduced by the injector 14 extending flow channel 80 with outlet throttle 82. The valve clamping nut 34 is supported on the support 70 of the valve piece 32. The others in FIG. 3b correspond represented components the components provided with identical reference numerals according to the embodiment in FIG. 3a ,

As the representations according to FIGS. 3a and 4 can be removed, run the interruptions 98 at the Ankerhubeinstellscheibe 62 facing end side of the magnet holder 52 in the circumferential direction substantially slit-shaped. Due to the extent of the interruptions 98 in the circumferential direction and in the formation of multiple interruptions 98 on the lower end face of the magnet holder 52, a return guide 102 is formed, which the fuel - as in FIG. 4 shown - derived from the return 56 in the low pressure region of the fuel injector 10. The magnet holder 52 is sealed against the injector body 14 via the O-ring 104, which is recessed in the receiving groove 102. The modified Ankerhubeinstellscheibe 62 is about its outer diameter in the injector body 14 - as already mentioned - centered.

The representation according to FIG. 5 is a side view and a bottom view of the magnet holder 52 can be seen.

The magnet holder 52, in which according to the FIGS. 2, 3a and 4 the magnetic core 22, the coil 24, the coil contacts 76 are received, has on its outer circumference a receiving groove 106, in which the O-ring 104 according to the FIGS. 3a and 4 is admitted. Seen from below, the magnet holder 52 has passage openings through which the coil contacts 76 are led out of the fuel injector or its head region. FIG. 5 shows that at the bottom of the magnet holder 52 at a pitch of about 90 ° with respect to the circumference of the slot-shaped configured interruptions 98 extend. The slot-shaped configured interruptions 98 in the region of the contact surface of the magnet holder 52 on the modified Ankerhubeinstellscheibe 62 allow leakage of the leakage amount in the low-pressure side region of the fuel injector 10. Instead of in FIG. 5 At an angle of 90 ° to each other oriented 4 interruptions 98, a smaller or a larger number of circumferentially spaced interruptions 98 could be formed on the lower contact side of the magnet holder 52. The interruptions 98 could also be mounted on the top of the valve clamping screw 70, this can be freely chosen according to requirements.

From the control chamber 84 effluent control amount and leakage amount, which originates from the leadership of the preferably needle-shaped injection valve member and the valve body and derived from the valve piston flows outside the magnetic core 22 over, between the magnet holder 52 and the magnetic core 22. This tax or leakage quantity becomes

Claims (9)

1. Fuel injector (10) having a solenoid valve (16), having an injector body (14) in which a valve piece (32) is accommodated, having a clamping nut (108) and having an armature stroke setting disc (62), wherein the solenoid valve (16) comprises a magnet coil (24), a magnet core (22) and a magnet holder (52) and actuates an armature assembly (60), and wherein the valve piece (32) is loaded by means of a valve clamping screw (34) against a first abutment shoulder (116) of the injector body (14), and wherein the magnet holder (52) is supported by way of a lower annular surface against the top side of the armature stroke setting disc (62),
   characterized in that the magnet holder (52) is supported via the armature stroke setting disc (62) on a valve clamping screw (34) or on an armature guide (72) such that the armature stroke setting disc (62) acts as a plate spring when the clamping nut (108) is tightened, wherein the armature guide (72) is formed in a neck of the valve piece (32) and the armature assembly (60) is guided movably in a vertical direction in the armature guide (72).
2. Fuel injector (10) according to Claim 1, characterized in that a flat side (96), on which the armature stroke setting disc (62) abuts, of the valve clamping screw (34) supports said armature stroke setting disc in the radially inner region.
3. Fuel injector (10) according to Claim 1, characterized in that a reference dimension for the setting of parallelism between a top side of the armature assembly (60) and a pole surface (24) of the magnet assembly (50) is an abutment (70) of the valve piece (32).
4. Fuel injector (10) according to Claim 1, characterized in that an armature guide (72) for guiding the armature assembly (60) on the valve piece (32) is oriented at right angles to the abutment (70) of the valve piece (32).
5. Fuel injector (10) according to Claim 1, characterized in that both the armature stroke setting disc (62) and also the valve clamping screw (34) are doubly ground-flat components.
6. Fuel injector (10) according to Claim 1, characterized in that the armature assembly (60) has an armature pin (56) for pressure equilibrium of the solenoid valve, said armature pin being supported on a support disc (54).
7. Fuel injector (10) according to Claim 1, characterized in that the magnet holder (52) comprises, in the region of an annular set-down surface on the armature stroke setting disc (62), at least one recess (98) which permits an outflow of a hydraulic medium.
8. Fuel injector (10) according to Claim 7, characterized in that the at least one recess (98) is in the form of a slot, running in a circumferential direction, on the magnet holder (52).
9. Fuel injector (10) according to Claim 1, characterized in that the magnet holder (52) is loaded by means of a magnet clamping screw (108) against the elastically mounted armature stroke setting disc (62).

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