Valve for metering a flowing medium

Abstract

A valve for metering a flowing medium, in particular a fluid, is described, comprising a filter (14) with a filter fabric (29) arranged in the medium flow. The filter (14) is arranged in a medium flow flowing from an inlet (11) to a metering opening (12) and has a plurality of filter pores in the filter fabric (29) with an outer inlet side facing the inlet (11) and an inner outlet side facing the metering opening (12). The filter fabric (29) is received in a filter body (32). The filter is a ring filter (14), wherein, according to the invention, the filter body (32) with its embedded filter fabric (29) is enclosed radially outwards by a thin-walled mounting tube (28).

Description

State of the art The invention relates to a valve for metering a flowing medium, in particular a fluid, preferably a gaseous fluid such as hydrogen, according to the preamble of claim 1. A known fuel injector (DE 10 2006 040 648 A1) has a hollow cylindrical valve body with at least one radial inlet bore, which connects the hollow interior of the valve body, accommodating a valve needle, to an inlet for supplying the fuel. Upstream of the inlet bore, in the direction of fuel flow, an annular filter is arranged for filtering the fuel. The filter has a filter housing, referred to as a fixing device, and a filter fabric made of metal or plastic fixed to the filter housing. The filter housing is preferably a plastic overmold of the filter fabric and seals the filter to the valve body. On the downstream side of the filter, a support element in the form of an annular ridge is integrally formed on the valve body, which is recessed in the area of ​​the at least one inlet bore and rests approximately centrally against the filter fabric.On both sides of the annular ridge, there is an annular groove in the valve body, through which several inlet bores can communicate with each other. In a known fuel injection valve (DE 10 2005 037 265 A1), the filter, arranged in the fuel flow, has a hollow cylindrical filter housing with two axially spaced support rings connected to each other by at least three axially extending webs. A tubular filter surface made of a mesh screen is rigidly connected to the filter housing. A support body for the filter surface is provided on the downstream side of the filter. The support body has a hollow cylindrical support section with projections supporting the filter surface, which are, for example, rib-shaped and only contact the filter surface along a line. Drainage channels remain between the projections through which the filtered fuel can flow away.The support body is inserted into the filter housing through an insertion opening provided in the filter housing, after which the hollow cylindrical support section extends over the inner wall surface of the annular filter surface. Furthermore, a valve for metering a flowing medium is already known from DE 10 2012 201 940 A1, in which a ring filter is used that has a filter ring containing a plurality of filter pores, with an outer inlet side facing the inlet and an inner outlet side facing the metering opening. The ring filter has a support body that supports the filter ring on its outlet side. The support body is designed as a radially elastic support ring with a plurality of through-holes, which bears against the filter ring with radial preload. Disclosure of the invention The valve according to the invention with the features of claim 1 has the advantage of being a very space-saving solution, since the radial extent of the ring filter is very small. According to the invention, the ring filter is closed off radially outwards by a thin-walled mounting tube. The ring filter, with its filter fabric embedded in a filter base body, is advantageously fixed and sealed via the mounting tube. The measures listed in the further claims enable advantageous further developments and improvements of the valve specified in claim 1. Advantageously, the mounting tube is made of thin walls throughout, particularly with a constant wall thickness. Deep drawing is especially suitable for manufacturing the mounting tube. It is advantageous to provide a reduced-diameter end section at one axial end to ensure a high degree of tightness between the mounting tube and the filter body. The reduced-diameter axial end section advantageously transitions into a bent radial section that then axially seals and encloses the filter body on one side. Preferably, the mounting tube is attached to a valve body belonging to the valve housing by means of a weld, several weld points and / or crimping, thus securing the entire ring filter to the valve. The filter body is advantageously sealed against the mounting pipe via several press points. Brief description of the drawings The invention is explained in more detail below with reference to an embodiment illustrated in the drawings. The drawings show: Fig. 1 a partial longitudinal section of a valve for metering a flowing medium with a ring filter arranged in the medium flow according to the prior art, Fig. 2 a partial longitudinal section of a valve for metering a flowing medium with a ring filter arranged in the medium flow according to an embodiment of the invention, and Fig. 3 a detailed longitudinal section view of the ring filter as section III of Fig. 2. Preferred embodiments of the invention The valve shown in longitudinal section in Fig. 1, for metering a flowing medium, in particular a fluid, is used, for example, as a valve for injecting fuel or, in particular, for injecting a gaseous medium such as hydrogen into the combustion cylinder of an internal combustion engine. Fig. 1 shows the longitudinal section of the injection-side end of the injection valve, the complete valve being shown and described, for example, in DE 10 2009 026 532 A1. The valve shown in Fig. 1 is thus part of the prior art; Fig. 1 is intended to illustrate the basic structure of such a valve type. The valve has an inlet 11 for the medium, i.e., for the fluid or fuel, and a metering port 12 for the medium, through which a desired metering quantity of the medium is controlled by means of a valve element or a valve needle 13. A filter 14 for retaining particles contained in the medium is arranged in the medium flow between the inlet and the metering port 12, the filter 14 covering at least one inlet bore 24 to the metering port 12. The metering port 12 is formed in a hollow nozzle body 15, which is coaxially attached to a hollow valve body 16. The valve body 16 is received in a valve housing 17, partially protruding from it. The nozzle body 15 and the valve body 16 enclose a valve chamber 18 upstream of the metering port 12, which is coaxially penetrated by the valve needle 13.The valve needle 13 exits the valve chamber 18 at the end furthest from the metering orifice in a medium-tight manner and is actuated here by an actuator 19, which is an electromagnetic or piezoelectric actuator 19 and, together with a valve closing spring 25 acting on the valve needle 13, drives the axially displaceable valve needle 13 to a stroke movement. The valve needle 13 carries a closing head 131 at its end furthest from the actuator, which interacts with a valve seat 20 formed on the nozzle body 15 and surrounding the metering orifice 12 to close and release the metering orifice 12. The actuator 19 is housed in a tube 21 concentrically fixed in the valve housing 17, with an annular gap 22 remaining between the tube 21 and the valve housing 17. This gap is connected to the inlet 11 and opens into an annular groove 23 formed in the valve body 16. From the annular groove 23, at least one inlet bore 24, formed as a radial bore in the valve body 16, leads into the valve chamber 18 located upstream of the metering opening 12. If there are multiple inlet bores 24, the annular groove 23 connects all of them. The medium, under system pressure, thus flows from the inlet 11 through the annular gap 22, the annular groove 23, and the one or more inlet bores 24 into the valve chamber 18.The closing head 131 is pressed onto the valve seat 20 by means of the valve closing spring 25 which is supported between the valve needle 13 and the valve body 16 and is lifted off the valve seat 20 against the force of the valve closing spring 25 when the actuator 19 is energized, thus releasing the metering opening 12. The filter 14, arranged in the medium flow, is pushed onto the valve body 16 until it completely covers the annular groove 23 and thus the inlet bores 24. In this position, the filter 14 is held axially immovably between a radial shoulder 161 formed on the valve body 16 and a radial shoulder 171 formed on the valve housing 17, and is radially fixed to the valve body 16 by the valve housing 17. The filter 14 has a filter ring with a plurality of fine filter pores and, in the described position, has an outer inlet side facing the inlet 11 and an inner outlet side facing the metering opening 12. A support body is provided on the outlet side of the filter ring, which has relatively low mechanical strength, to provide mechanical stabilization. Fig. 2 shows a partial longitudinal section of a valve for metering a flowing medium with a ring filter 14 arranged in the medium flow according to an embodiment of the invention, while Fig. 3 shows a detailed longitudinal section view of the ring filter 14 as section III of Fig. 2. The ring filter 14 according to the invention is arranged at a comparable location on the valve housing as in the valve shown in Fig. 1. In particular, the ring filter 14 is attached to the sleeve-shaped valve body 16. According to the invention, the ring filter 14 is closed off radially outwards by a thin-walled mounting tube 28. The ring filter 14, with its filter fabric 29, is fixed and sealed via the mounting tube 28. Advantageously, this design of the ring filter 14 and its mounting requires only a very small radial installation space. The ring filter 14 is attached to the valve body 16 by means of a weld 30 or several spot welds, or alternatively or additionally by press-fitting the thin-walled mounting tube 28 onto the valve body 16. The filter fabric 29 is embedded in a filter body 32, which is made, for example, of a plastic such as PA66, PPA, or PPS and partially surrounds and holds the filter fabric 29 in place by overmolding. The filter fabric 29 is either metallic (e.g., 1.4301, 1.4310) or made of a plastic such as PEEK. The filter body 32 is sealed to the mounting tube 28, for example, by several press fits. The filter body 32 is also pressed onto the valve body 16 at least at one axial end. Alternatively, welding can also be used here. The mounting tube 28 is preferably a thin-walled, sleeve-shaped component of the ring filter 14, which forms its housing, and is manufactured by deep drawing. Alternatively, the mounting tube 28 can also be an extrusion, a turned, a sintered, or a MIM (Metal Injection Molding) part. For optimized mounting of the ring filter 14, the mounting tube 28 has, for example, a diameter-reduced end section 33 at its upper axial end, wherein the end section 33 transitions into a bent radial section 34 that axially closes and encloses the filter body 32 on one side. In this way, axial support of the ring filter 14 is provided by the mounting tube 28. Several radial openings 35 in the mounting tube 28, which allow the flow of fluid through the filter fabric 29 from the radial outside to the inner valve chamber 18, are produced, for example, by punching. Alternatively, the openings 35 can also be produced by EDM, drilling, milling, etc. Suitable materials for the mounting tube 28 include, for example, 1.4301 or 1.4310. The wall thickness of the thin-walled mounting tube 28 is, for example, 0.08 to 0.3 mm. QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature DE 10 2006 040 648 A1

[0002] DE 10 2005 037 265 A1

[0003] DE 10 2012 201 940 A1

[0004] DE 10 2009 026 532 A1

[0012]

Claims

Valve for metering a flowing medium, in particular a fluid, preferably a gaseous fluid such as hydrogen, comprising a filter (14) arranged in a medium flow from an inlet (11) to a metering opening (12) and comprising a filter fabric (29) containing a plurality of filter pores with an outer upstream side facing the inlet (11) and an inner downstream side facing the metering opening (12), and comprising a filter base body (32) receiving the filter fabric (29), characterized in that the filter is a ring filter (14) and the filter base body (32) with its embedded filter fabric (29) is enclosed radially outwards by a thin-walled mounting tube (28). Valve according to claim 1, characterized in that the mounting tube (28) completely radially surrounds the filter base body (32). Valve according to claim 1 or 2, characterized in that the mounting tube (28) has several radial openings (35) which allow flow to the filter fabric (29) from radially outside ultimately to an inner valve chamber (18). Valve according to one of the preceding claims, characterized in that the mounting tube (28) fixes and seals the ring filter (14) with its filter fabric (29). Valve according to one of the preceding claims, characterized in that the mounting tube (28) can be manufactured by deep drawing. Valve according to one of the preceding claims, characterized in that the mounting tube (28) has a diameter-reduced end region (33) at an axial end, which transitions into a bent radial region (34) which axially closes off and encloses the filter base body (32) on one side. Valve according to one of the preceding claims, characterized in that the mounting tube (28) is attached to a valve body (16) by means of a weld (30), several weld points and / or crimping, and thus the entire ring filter (14) is secured to the valve. Valve according to one of the preceding claims, characterized in that the sealing of the filter base body (32) to the mounting tube (28) is effected via several press points. Valve according to one of the preceding claims, characterized in that the wall thickness of the thin-walled mounting tube (28) is 0.08 to 0.3 mm.

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