Valve for a flowing medium

Abstract

A valve for a flowing medium, comprising a tubular valve seat support (11) connected to a medium inlet (10) and closed at one end by a valve seat body (12) having a valve opening (13) with a valve seat (14), comprising an electromagnet (15) arranged on the valve seat support (11) for actuating a valve needle (16) cooperating with the valve seat (14) to open and close the valve opening (13), comprising a magnet pot (22) with a smaller-diameter pot section (222) surrounding the valve seat support (11) and a larger-diameter pot section (221) receiving a magnetic coil (24) of the electromagnet (15), wherein a sheet-metal sleeve (27) is placed on the end of the smaller-diameter pot section (222) facing the valve seat body (12),which rests with a first sleeve section (271) on the smaller-diameter pot section (222) and extends with a second sleeve section (272) over part of the valve seat carrier (11) emerging from the magnet pot 22, in that the first sleeve section (271) is connected to the smaller-diameter pot section (222) in a medium-tight manner by means of a circumferential weld seam (28), and in that sealing means are arranged in the second sleeve section (272) between the second sleeve section (272) and the valve seat carrier (11), characterized in that the sheet metal sleeve (27) is stepped in diameter and the second sleeve section (272) of the sheet metal sleeve (27) has an inner diameter reduced to the outer diameter of the valve seat carrier (11), and in that the sealing means have a circumferential weld seam (35) connecting the second sleeve section (272) to the valve seat carrier (11) in a medium-tight manner.

Description

State of the art

[0001] The invention is based on a valve for a flowing medium, in particular a metering valve for metering a liquid, according to the preamble of claim 1.

[0002] Such a valve is used, for example, for the metered spraying of a liquid medium, e.g., fuel or a urea-water solution for reducing nitrogen oxide in the exhaust gas of an internal combustion engine. The valve is inserted into a reaction chamber, e.g., the intake manifold or exhaust pipe of an internal combustion engine, in such a way that a portion of the magnet cup and a tube section of the valve seat carrier protruding from the magnet cup and supporting the valve seat body with valve opening and valve seat at the end, protrude into the reaction chamber.

[0003] In a known fuel injection valve of this type (DE 199 32 763 A1), the tubular valve seat support, with a tube section protruding from the magnet pot, is welded to the smaller-diameter pot section of the magnet pot by means of a fillet weld running circumferentially around the annular end face of the magnet pot. If the weld is of high quality, this prevents the sprayed-off liquid medium from the reaction chamber from penetrating through the annular gap between the valve seat support and the inner wall of the smaller-diameter pot section of the magnet pot into the interior of the larger-diameter pot section of the magnet pot, which forms the coil chamber for the solenoid coil. However, process reliability in the execution of a reliably sealing weld cannot be guaranteed under all circumstances with such a fillet weld.Further injection valves are known from DE 10 2010 030 947 A1 and DE 10 2005 052 256 A1. Disclosure of the invention

[0004] The valve according to the invention with the features of claim 1 has the advantage that the sheet metal sleeve offers ideal conditions for process-reliable sealing welding over its sheet metal wall thickness and thus the larger diameter pot section accommodating the magnetic coil is reliably protected against the penetration of medium, such as fuel or urea-water solution, from the reaction chamber via the smaller diameter pot section of the magnetic pot.

[0005] The measures listed in the further claims enable advantageous further developments and improvements of the valve specified in claim 1.

[0006] According to an advantageous embodiment of the invention, the sleeve is provided with a sleeve base at the free end of the second sleeve section facing away from the first sleeve section. The base has a bottom opening for the valve seat carrier to pass through. The sealing means comprise an elastic, annular sealing element pressed between the valve seat carrier and the second sleeve section of the sheet metal sleeve. The sealing element is preferably an O-ring supported on the sleeve base. Only a small cord thickness is required for the annular sealing element, which in turn allows the use of a high-quality elastomer as the material for the sealing element.

[0007] According to an alternative embodiment of the invention, the sheet metal sleeve is deep-drawn and stepped in diameter, and the second sleeve section has an inner diameter reduced to the outer diameter of the valve seat carrier. The sealing means comprise a circumferential weld seam on the second sleeve section, which tightly connects the second sleeve section to the valve seat carrier. This structural design represents a robust design without elastomers in the sealing of the coil chamber in the larger-diameter pot section of the magnet pot. Here, too, the sheet metal wall thickness provides ideal conditions for the tight welding of the sheet metal sleeve and valve seat carrier.

[0008] According to an advantageous embodiment of the invention, the first sleeve section is provided with a radially outwardly projecting collar at its free end facing away from the second sleeve section. A plastic support ring is injection-molded onto the collar and extends over a portion of the first sleeve section and the smaller-diameter pot section of the magnet pot. The collar ensures that the support ring forms a positive connection with the magnet pot and fulfills its supporting function for a sealing ring seated on the smaller-diameter pot section of the magnet pot. The sealing ring serves to seal a reaction chamber into which the smaller-diameter pot section of the magnet pot and the section of the valve seat carrier emerging from the magnet pot and carrying the valve seat body at its end protrude. Short description of the drawings

[0009] The invention is explained in more detail in the following description with reference to exemplary embodiments illustrated in the drawings. They show: Fig. 1 a partial longitudinal section of a valve for a flowing medium, Fig. 2 a similar representation of a modified valve.

[0010] The Fig. 1 and in Fig. The valve for a flowing medium shown in Figure 2 is used as a metering valve for metering a liquid medium into a reaction chamber, e.g., fuel into an intake manifold of an internal combustion engine or a urea-water solution into the exhaust pipe of an internal combustion engine for the purpose of reducing nitrogen oxides in the exhaust gas. The valve has a tubular valve seat carrier 11 connected to a medium inlet, which is closed at the end by a valve seat body 12. The medium inlet is in Fig. 1 symbolized by arrow 10. The valve seat body 12 is provided with a valve opening 13 and a valve seat 14 surrounding the valve opening 13. The valve further comprises an electromagnet 15 for actuating a valve needle 16 arranged inside the valve seat carrier 11, which valve needle interacts with the valve seat 14 to open and close the valve opening 13. The valve needle 16 is hollow and is connected to the medium inlet 10. The end of the valve needle 16 facing away from the medium inlet 10 is closed off with a closing head 17. The valve needle 16 is pressed with its closing head 17 onto the valve seat 14 by means of a valve closing spring 18. The valve closing spring 18 is supported on the one hand on the end of the valve needle 16 remote from the closing head and on the other hand on an adjusting member 19 for adjusting the closing force of the valve closing spring 19.At a distance from the closing head 17, passage openings 20 are provided in the valve needle 16, so that the medium flowing via the medium inlet 10 through the hollow adjusting member 19 and the hollow valve needle 16 can flow into the valve chamber 21 located in the valve seat carrier 11 upstream of the valve seat body 12 and is present at the valve seat 14 and closing head 17 under system pressure.

[0011] The electromagnet 15 has a magnet pot 22, a magnet core 23, a magnet coil 24, and a magnet armature 25 firmly connected to the valve needle 16. The magnet pot 22 has a larger-diameter pot section 221 and a smaller-diameter pot section 222 that continues integrally thereto. The smaller-diameter pot section 222 encloses a portion of the valve seat carrier 11 protruding from the magnet pot 22, and the larger-diameter pot section 221 accommodates the magnet coil 24 pushed onto the valve seat carrier 11. The magnet core 23 is arranged in the valve seat carrier 11 and, together with the magnet armature 25, which is guided axially displaceably in the valve seat carrier 11, encloses a working air gap 26 of the electromagnet 15.

[0012] In order to prevent the liquid medium from penetrating from a reaction chamber, into which the valve injects medium in a metered manner, into the coil chamber formed by the interior of the larger-diameter pot section 221, and thus to prevent damage to the electromagnet 15, a sheet metal sleeve 27 is placed on the end of the smaller-diameter pot section 222 facing the valve seat body 12. The sheet metal sleeve 27 rests on the smaller-diameter pot section 222 with a first sleeve section 271 and extends, with a second sleeve section 272 continuing integrally thereto, over part of the valve seat carrier 11 emerging from the smaller-diameter pot section 222 of the magnet pot 22. The first sleeve section 271 is connected to the magnet pot 22 in a medium-tight manner by means of a circumferential weld seam 28. Sealing sealing means are arranged on the second sleeve portion 272 between the second sleeve portion 272 and the valve seat carrier 11.

[0013] In the embodiment of the valve according to Fig. 1, the sleeve 27 is provided with a sleeve base 273 integrally formed on the free end of the second sleeve section 272 facing away from the first sleeve section 271, which has a base opening 29 for the passage of the valve seat carrier 11. The inside diameter of the base opening 29 is only slightly larger than the outer diameter of the valve seat carrier 11. The sealing means comprise an elastic, annular sealing element 30, which is pressed between the valve seat carrier 11 and the inner wall of the second sleeve section 272 facing the valve seat carrier 11. The sealing element 30 is preferably designed as an O-ring 31 made of an elastomer, which is supported on the sleeve base 273.

[0014] The first sleeve section 271 is provided at its free end facing away from the second sleeve section 272 with a collar 274 that is integrally bent radially outward. A plastic support ring 32 is injection-molded onto the collar 274 in such a way that it extends over part of the first sleeve section 271 and part of the smaller-diameter pot section 222 of the magnet pot 22. The support ring 32 serves to prevent a sealing ring 33, which is placed on the larger-diameter pot section 221, from falling off or being pulled off. The sealing ring 33, in turn, serves to seal an assembly opening in a reaction chamber after the valve has been inserted into the reaction chamber.

[0015] The valve seat support 11 is secured at its end portion remote from the valve seat body in a plastic housing 34, which is injection-molded onto the valve seat support 11 as a plastic jacket and extends over part of the larger-diameter pot portion 221 of the magnet pot 22. The medium inlet 10 is formed in the plastic housing 34 in the form of a valve connection (not shown here).

[0016] The Fig. The embodiment of the valve shown in Figure 2 is largely identical in design to the previously described valve according to Fig.1, so that identical components are provided with identical reference numerals. The only difference is the design of the sheet metal sleeve 27 for sealing the coil space enclosed by the larger-diameter pot section 221 of the magnet pot 22 and containing the magnetic coil 24. Here, the sheet metal sleeve 27 is deep-drawn and has two different inside diameters, with the first sleeve section 271 having an inside diameter corresponding to the outside diameter of the smaller-diameter pot section 222 and the second sleeve section 272 having an inside diameter corresponding to the outside diameter of the valve seat carrier 11. The larger-diameter first sleeve section 271 still engages over the free end of the smaller-diameter pot section 222 of the magnet pot 22 and is secured thereto in a medium-tight manner by means of the weld seam 28.The sealing means sealing between the second sleeve section 272, which is reduced in diameter to the outer diameter of the valve seat carrier 11, and the valve seat carrier 11 are realized here by a weld seam 35 running around the second sleeve section 272, which connects the second sleeve section 272 to the valve seat carrier 11 in a medium-tight manner.

Claims

[1] Valve for a flowing medium, comprising a tubular valve seat support (11) connected to a medium inlet (10), which is closed at its end by a valve seat body (12) having a valve opening (13) with a valve seat (14), comprising an electromagnet (15) arranged on the valve seat support (11) for actuating a valve needle (16) cooperating with the valve seat (14) to open and close the valve opening (13), which comprises a magnet pot (22) with a smaller-diameter pot section (222) surrounding the valve seat support (11) and a larger-diameter pot section (221) receiving a magnetic coil (24) of the electromagnet (15), wherein a sheet-metal sleeve (27) is placed on the end of the smaller-diameter pot section (222) facing the valve seat body (12),which rests with a first sleeve section (271) on the smaller-diameter pot section (222) and extends with a second sleeve section (272) over a part of the valve seat carrier (11) emerging from the magnet pot 22, that the first sleeve section (271) is connected to the smaller-diameter pot section (222) in a medium-tight manner by means of a circumferential weld seam (28), and that sealing means are arranged in the second sleeve section (272) between the second sleeve section (272) and the valve seat carrier (11), , characterized by that the sheet metal sleeve (27) is stepped in diameter and the second sleeve section (272) of the sheet metal sleeve (27) has an inner diameter reduced to the outer diameter of the valve seat carrier (11) and that the sealing means have a circumferential weld seam (35) connecting the second sleeve section (272) to the valve seat carrier (11) in a medium-tight manner. [2] Valve according to claim 1, characterized bythat the first sleeve section (271) of the sheet metal sleeve (27) is provided with a radially outwardly projecting collar (274) at its end remote from the second sleeve section (272). [3] Valve according to claim 2, characterized by that a support ring (32) made of plastic is injection-molded onto the collar (274), which support ring extends over part of the first sleeve section (271) of the sheet metal sleeve (27) and the smaller-diameter pot section (222) of the magnet pot (22). [4] Valve according to one of claims 1 to 3, characterized by that the valve seat carrier (11) is fixed in a plastic housing (34) which is injection-molded onto the valve seat carrier (11) and a part of the larger-diameter pot section (221) of the magnet pot (22), and that the medium inlet (10) is formed in the plastic housing (34).

Images