DE102013223453A1 - Valve for metering fluid - Google Patents

Abstract

The invention relates to a valve for metering fluid, which has a valve needle (13) actuated by a valve closing spring (14) and an electromagnet (15) for controlling an orifice (12). The electromagnet (15) has a hollow cylindrical magnetic core (21) and a coaxial thereto, on the valve needle (13) attacking magnetic core (21). The valve closing spring (14) is arranged inside the magnet core (21) on the valve needle (13) and is supported on the magnetic core side and on the valve needle side. In the magnetic core (21), a guide element (32) is received for sliding the valve needle (13). In order to keep the inner diameter of the hollow cylindrical magnetic core (21) as small as possible in the area of its pole faces opposite the armature (23), the guide element (32) is arranged beyond the valve closing spring (14) as seen from the armature (23). 21), centrally receives an end portion of the valve needle (13) axially displaceable and takes over the magnetic core-side support of the valve closing spring (14).

Description

State of the art

The invention is based on a valve for metering fluid according to the preamble of claim 1, wherein the standing for a flowing or flowing medium, superordinate term fluid is used in accordance with the fluid flow theory for gases and liquids.

A known fuel injection valve ( DE 101 08 945 A1 ) has a sleeve-shaped nozzle body which is closed by a valve seat body with an injection opening enclosed by a valve seat. In the nozzle body of the ejection opening is preceded by a valve chamber which is in communication with a fuel inlet. In the nozzle body immerses the injection opening controlling valve needle, which carries a forming a sealing seat with the valve seat closing head. At the needle end remote from the closing head, a T-shaped carrier is firmly inserted into the hollow valve needle, on which a cylindrical guide element for sliding the valve needle in the magnetic core is formed, which dips into the inner pole or magnetic core of an electromagnet for valve needle actuation. In the interior of the magnetic core, a valve closing spring is arranged coaxially with the valve needle, which is supported on the one hand on the guide element of the driver and on the other hand on a pressed-in in the magnetic core sleeve. By the force applied by the valve closing spring on the driver on the valve needle closing force of the closing head is pressed onto the valve seat, so that the injection opening is closed. The closing force of the valve closing spring is adjusted by the position of the pressed-in sleeve. The electromagnet has a magnetic coil arranged coaxially to the magnetic core, a magnet pot concentrically enclosing magnet pot, the cup bottom side firmly connected to the nozzle body and potpfnungsseitig connected via a magnetic yoke to the magnetic core, and a slidably mounted on the driver armature, which is connected to the magnetic core limited working air gap. At the armature facing end face of the driver is a stop shoulder and arranged on the side facing away from the stop shoulder side of the armature on the valve pin anchor stop. Stop shoulder and anchor stop limit a free path or forward stroke of the armature, which is smaller than the axial gap width of the working air gap. A pushed onto a diameter-reduced portion of the driver Vorhubfeder supported on the one hand on the armature and on the other hand on the guide element and presses the armature against the anchor stop. When the magnet coil of the electromagnet is energized, the armature firstly executes the free travel or preliminary stroke relative to the valve needle until it abuts the driver on the stop shoulder and thereby gives the valve needle a mechanical opening pulse. In the further armature movement of the driver and the driver over the valve needle is entrained, whereby the closing head begins to stand out from the valve seat. At the end of the complete armature stroke, the armature abuts against the pole face of the magnetic core, and the ejection opening is completely released, so that the fuel under pressure in the valve chamber is sprayed off in a metered quantity via the ejection opening. In the absence of energization of the solenoid, the valve closing spring on the driver and the valve needle presses the closing head on the valve seat, and the Vorhubfeder pushes the armature against the anchor stop.

Disclosure of the invention

The valve according to the invention for metering fluid with the features of claim 1 has the advantage that seen by the displacement of the inset in the magnetic core guide element for the valve needle from the anchor beyond the valve closing spring of the inner diameter of the magnetic core in its end faces carrying the pole faces are made smaller can, so that the available for the installation of the armature pole face of the magnetic core is larger area. Thus, the magnetic force acting on the armature increases while the current of the electromagnet is unchanged. By maintaining the magnetic force, conversely, the electromagnet can be designed to have lower power. Furthermore, the displacement of the guide element behind the valve closing spring opens up the possibility of using the guide element for further functions, such as support of the valve closing spring and / or magnetic separation of valve needle and magnetic core.

The measures listed in the further claims advantageous refinements and improvements of the claim 1 valve are possible.

According to an advantageous embodiment of the invention, the guide element is fixed in the magnetic core and takes on the one hand centrally an end portion of the valve needle axially displaceable and on the other hand takes over the magnetic core side support of the valve closing spring.

For this purpose, according to an advantageous embodiment of the invention, the guide element is designed as a hollow-cylindrical sleeve with a sleeve wall delimited by an inner and outer surface, which has a guide region for the valve needle and a pressing region for pressing into the magnetic core. Guide area and pressing area each extend over one Axial section of the sleeve. In the guide region of the sleeve, the inner surface of the sleeve is designed as a guide surface for the valve needle, and between the outer surface of the sleeve and the inner surface of the hollow cylindrical magnetic core, a radial clearance is present. In the press area of the sleeve, the sleeve has a press fit to the magnetic core via its outer surface. Through this constructive realization of the guide element, on the one hand, a compression stress is produced between the sleeve and the magnetic core, which fixes the sleeve at the position required for adjusting the closing force of the valve closing spring within the magnetic core and, on the other hand, ensures a play-free sliding guide of the valve needle in the magnetic core, which does not suffer from the compressive stress becomes. In order to limit the pressing force according to an advantageous embodiment of the invention, the pressing region is slotted, so provided the sleeve wall with at least one radial slot. The radial slot also allows a precise positioning of the sleeve during their pressing into the magnetic core and thus a sensitive fine adjustment of the spring force of the valve closing spring. The sleeve is made as a separate component and is firmly connected to the valve needle after installation of armature and valve closing spring. The material for the valve needle can be selected independently of the valve needle.

In order to reliably decouple the press tension generated by the press-fitting of the sleeve into the magnet guide in the guide area of the sleeve, the guide and press area of the sleeve are separated by a constriction, the constriction being realized by an axial section reduced between the guide and press areas is. Preferably, the axial length of the at least one radial slot in the pressing region of the sleeve extends into the constriction.

According to an advantageous embodiment of the invention, the sleeve has at least one passage channel for the fluid, which is designed as a throttle channel. Such a throttling channel allows a hydraulic throttling of the fluid flow flowing from the fluid inlet to the metering opening.

The throttle channel can be realized structurally diverse. In a preferred embodiment of the invention, the at least one throttle channel is realized by at least one axial groove, which is incorporated in the guide surface in the guide region of the sleeve and bounded by the valve needle section guided on the guide surface. Alternatively, the at least one throttle channel can also be incorporated as at least one longitudinal groove in the outer surface of the sleeve in the pressing region and limited by the inner surface of the hollow cylindrical magnetic core. Furthermore, the throttle channel can also be designed as an axial bore running in the sleeve wall of the sleeve.

According to an advantageous embodiment of the invention, the sleeve is made of a non-magnetic material, that is, of a magnetically non or poorly conductive material. Thus, the already responsible for needle guide, closing force adjustment for the valve closing spring and throttling the fluid flow sleeve still takes on the additional function of magnetic separation of a magnetically conductive material existing valve needle and the magnetic core, so that the magnetic flux of the electromagnet via armature and working air gap to the magnetic core not by a is weakened via anchor, valve needle, sleeve and magnetic core forming, parallel flow path is weakened.

In all embodiments of the invention, the armature can be fixedly arranged on the valve needle or be displaceable relative to the valve needle to improve the opening dynamics of the valve on the valve needle. This free path or forward stroke called displacement of the armature is limited by a stop shoulder and an anchor stop, which are arranged on mutually remote sides of the armature fixed to the valve needle. The stop shoulder is fixed to a valve needle, z. B. welded ring, which serves to support the valve closing spring. A forward stroke spring loads the armature in the direction of the anchor stop and applies the armature to the anchor stop when the electromagnet is not energized. The Vorhubfeder is pushed onto the side facing away from the working air gap side of the armature on the valve needle and is based on the anchor stop and on a loose sitting on the valve needle spring plate, whose plate is fixed to the anchor. Unlike the known valve described above, this arrangement of the Vorhubfeder requires no spring space inside the magnetic core and is not contrary to the formation of the magnetic core with the smallest possible inner diameter.

Brief description of the drawings

The invention is explained in more detail in the following description with reference to an embodiment shown in the drawings. Show it:

1 a section of a valve for metering fluid with a valve needle and a guide element for sliding the valve needle,

2 an enlarged perspective sectional view of the guide element in 1 ,

This in 1 Sectionally shown in longitudinal section valve for metering fluid is preferably used as an injection valve for injecting fuel in a fuel injection system of internal combustion engines. However, it can also be used in gas engines or in heating systems for the metered metering of fluid fuel or as a metering valve for injecting a fluid reducing agent into the exhaust gas tract of an internal combustion engine for the purpose of reducing nitrogen oxides.

The valve has one with a fluid inlet 11 related orifice 12 and one the orifice 12 by means of a closing head 131 controlling valve needle 13 on, the closing of the orifice 12 from a valve closing spring 14 is acted upon and to release the orifice 12 from an electromagnet 15 against the closing force of the valve closing spring 14 is pressed. The closing head 131 is in a valve seat body 16 led, which the orifice 12 and one the orifice 12 enclosing, with the closing head 131 the valve needle 13 a sealing seat forming valve seat 17 having. The valve seat body 16 includes a zumessseitiges end of a sleeve-shaped valve housing 18 fluid-tight, while in the inlet side, the other end of the valve housing 18 a fluid inlet 11 containing connecting piece 19 is used.

The electromagnet 15 has a magnetic coil 20 on, in the current supply in a known manner, a magnetic flux in a closed magnetic circuit of the inner and outer pole, which has a magnetic return 24 coupled, an anchor 23 and one between the end face of the anchor 23 and the pole face of the inner pole lying working air gap 25 generated. One in the valve housing 18 firmly arranged, hollow cylindrical magnetic core 21 forms the inner pole and a concentric magnetic pot 22 the outer pole. The magnet pot 22 is with a smaller diameter pot section on the valve body 18 attached, for example, welded, and surrounds with a larger diameter pot section on the valve body 18 sitting magnet coil 20 , The hollow cylindrical magnetic core 21 is in the valve body 18 firmly inserted. The magnetic coil 20 sits on the the pot sections 221 and 222 connecting, annular pot bottom, and the magnetic return 24 connects above the magnetic coil 20 the magnet pot 22 with the valve housing made of magnetically conductive material 18 , To prevent a magnetic short circuit between magnet pot 22 and magnetic core 21 through the valve body 18 made of magnetically conductive material is in the valve body 18 in the area of the working air gap 24 a constriction 26 provided a magnetic bottleneck with a high magnetic resistance in the valve body 18 generated.

The anchor 23 can firmly on the valve needle 13 be arranged. In the illustrated embodiment, the armature is to improve the opening dynamics of the valve 23 axially displaceable on the valve needle 13 arranged, with its displacement relative to the valve needle 13 , the so-called Freiweg or Vorhub the anchor 23 , which is smaller than the axial gap width of the working air gap 25 , by a stop shoulder 27 and an anchor stop 28 is fixed, on mutually remote sides of the anchor 23 firmly on the valve needle 13 are arranged. The stop shoulder 27 is doing one on the valve needle 16 attached ring 29 trained, and that at the anchor 23 facing front end of the ring 29 , A Vorhubfeder 30 impinges on the anchor 23 so that he is at the anchor stop 28 is pressed, with the Freiweg or Vorhub of the anchor 23 between facing faces of anchor 23 and stop shoulder 27 established. The Vorhubfeder 30 on the one hand relies on the anchor stop 28 and on the other hand on the plate bottom of the valve needle 13 loosely surrounding, approximately conical spring plate 31 off, its plate at the anchor 23 fixed, eg welded, is.

The valve needle 13 is at its Schließkopffernen end by means of a inside the hollow cylindrical magnetic core 21 arranged guide element 32 sliding manner. The valve closing spring 14 is in the range of the magnetic core 21 Loosely on the valve needle 13 deferred and magnet core side and valve needle side axially supported, wherein the valve needle side support on the stop shoulder 27 wearing ring 29 is made. The guide element 32 is at the anchor 23 turned off end of the valve closing spring 14 So from the anchor 23 seen from beyond the valve closing spring 14 arranged. Here is the guide element 32 in the magnetic core 21 set and takes on the one hand centrally the end portion of the valve needle 13 axially displaceable and on the other hand takes over the magnetic core side support of the valve closing spring 14 , This is the guide element 32 as a hollow cylindrical sleeve 33 formed with a limited by an inner and outer surface sleeve wall, which is a guide area 331 for the valve needle 13 and a pressing area 332 for pressing into the magnetic core 21 having. guide region 331 and pressing area 332 are arranged axially one behind the other and by a constriction 333 separated from each other by an outer diameter reduced axial portion of the sleeve 33 is formed. In the management area 331 the sleeve 33 is the inner surface of the sleeve 33 as a guide surface 34 for the valve needle 13 is formed and is between the outer surface of the sleeve 33 and the inner surface of the magnetic core 21 a radial play exists. In the pressing area 332 the sleeve 33 has the sleeve 33 over its outer surface a press fit 35 to the magnetic core 21 , To the Limiting press force is in the press area 332 slotted the socket wall. The at least one radial slot 36 runs in the pressing area 332 radially to the inner surface of the sleeve 33 and extends axially into the constriction 333 forming axial portion of the sleeve 33 , The annular, free end face of the guide area 331 the sleeve 33 provides an abutment for the valve closing spring 14 represents.

For fluid passage from the fluid inlet 11 over the hollow magnetic core 21 for metering 12 On the one hand, there is the anchor 23 at least one axial channel 37 and on the other hand, the sleeve 33 at least one passageway, which is used for throttling the fluid flow and as a throttle channel 38 referred to as. In the illustrated embodiment, the at least one throttle channel 38 through a into the inner surface of the sleeve 33 machined axial groove formed, which is the guide surface 34 in the management area 331 the sleeve 33 interrupts and through the in the guide surface 34 guided needle section of the valve needle 13 is covered.

We are not shown here, the throttle channel 38 also between the outer surface of the sleeve 33 and the inner wall of the magnetic core 21 run. This is in the outer surface of the sleeve 33 an axial groove incorporated after pressing the sleeve 33 in the magnetic core 21 from the inner wall of the magnetic core 21 is closed. The throttle channel 38 but can also be introduced into the sleeve wall itself as axial bore extending parallel to the sleeve axis.

The sleeve 33 is non-magnetic, so made of a magnetically not or only poorly conductive material, so that the valve needle 13 with closing head 131 , Sleeve 39 and anchor stop 28 may consist of magnetically conductive material. The non-magnetic sleeve 33 prevents a magnetic flux parallel to the working air gap 25 over the valve needle 13 to the magnetic core 21 , which leads to a significant loss of flow in the working air gap 25 would lead. The already for sliding guide of the valve needle 13 , Closing force setting of the valve closing spring 14 and fluid flow throttling used multi-functional sleeve 33 thus assumes the additional function of magnetic separation of magnetically conductive valve needle 13 and magnetic core 21 ,

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10108945 A1 [0002]

Claims (13)

Valve for metering fluid, with one having a fluid inlet ( 11 ) communicating orifice ( 12 ), with an orifice ( 12 ) controlling valve needle ( 13 ), with an electromagnet ( 15 ) for valve needle actuation, one on the valve needle ( 13 ) attacking anchor ( 23 ) and a coaxial with the anchor ( 23 ) a working air gap ( 25 ) limiting, hollow cylindrical magnetic core ( 21 ), with a valve needle ( 13 ) for closing the orifice ( 12 ) acting valve closing spring ( 14 ) inside the magnetic core ( 21 ) on the valve needle ( 14 ) and valve needle side and the magnetic core side is axially supported, and with a magnetic core ( 21 ) received guide element ( 32 ) for sliding the valve needle ( 13 ), characterized in that the guide element ( 32 ) at the anchor ( 23 ) averted end of the valve closing spring ( 14 ) is arranged. Valve according to claim 1, characterized in that the guide element ( 32 ) in the magnetic core ( 21 ) is fixed and on the one hand centrally an end portion of the valve needle ( 13 ) receives axially displaceable and on the other hand, the magnetic core-side support of the valve closing spring ( 14 ) takes over. Valve according to claim 2, characterized in that the guide element ( 32 ) as a hollow cylindrical sleeve ( 33 ) is formed with a limited by an inner and outer surface sleeve wall which a guide area ( 331 ) for the valve needle ( 13 ) and a pressing area ( 332 ) for pressing into the magnetic core ( 21 ) having. Valve according to claim 3, characterized in that in the guide area ( 331 ) the sleeve ( 33 ) the inner surface of the sleeve ( 33 ) a guide surface ( 34 ) for the valve needle ( 13 ) and between outer surface of the sleeve ( 33 ) and magnetic core ( 21 ) a radial play is present. Valve according to claim 3 or 4, characterized in that in the pressing area ( 332 ) the sleeve ( 33 ) via its outer surface a press fit to the magnetic core ( 21 ) Has. Valve according to claim 5, characterized in that in the pressing area ( 332 ) the sleeve ( 33 ) the sleeve wall at least one radial slot ( 36 ) having. Valve according to one of claims 3 to 6, characterized in that between guide area ( 331 ) and pressing area ( 332 ) the sleeve ( 33 ) a constriction ( 333 ) in the sleeve wall forming axial portion of the sleeve ( 33 ) is present with reduced outer diameter. Valve according to one of claims 3 to 7, characterized in that on the valve needle ( 13 ) recorded valve closing spring ( 14 ) on the one hand at the management area ( 331 ) limiting, annular end face of the sleeve ( 33 ) and on the other hand on one on the valve needle ( 13 ) fixed ring ( 29 ) is supported. Valve according to one of claims 3 to 8, characterized in that the sleeve ( 33 ) at least one throttle channel ( 38 ) for the passage of fluid. Valve according to claim 9, characterized in that the at least one throttle channel ( 38 ) as axial groove ( 39 ) in the inner wall of the sleeve ( 33 ), which is in the management area ( 331 ) the sleeve ( 33 ) through the valve needle ( 13 ) is covered. Valve according to one of claims 3 to 10, characterized in that the sleeve ( 33 ) consists of an amagnetic material. Valve according to one of claims 8 to 11, characterized in that the armature ( 23 ) axially displaceable on the valve needle ( 13 ) is arranged on the valve needle-fixed ring ( 29 ) a stop shoulder ( 27 ) for the anchor ( 23 ) is formed, the one opposite the working air gap ( 25 ) smaller free path or forward stroke of the anchor ( 23 ), and that the anchor ( 23 ) by means of a Vorhubfeder ( 30 ) in the direction of an anchor stop ( 28 ), which is supported on that of the stop shoulder ( 27 ) facing away from the anchor ( 23 ) on the valve needle ( 13 ). Valve according to claim 12, characterized in that the Vorhubfeder ( 28 ) at the anchor stop ( 28 ) and on a loose on the valve needle ( 13 ) seated, cone-shaped spring plate ( 31 ) is supported, whose plate edge at anchor ( 23 ).

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