Valve for a flowing medium

Abstract

Valve for a flowing medium, in particular a metering valve for dispensing a freezing liquid, with a valve chamber (12) upstream of a valve opening (11), with an inlet channel (13) leading to the valve chamber (12) for the medium and with a filter (14) arranged in the inlet channel (13) through which the medium flows, characterized in that the filter (14) is fixed in the inlet channel (13) in a manner that allows it to be elastically displaceable with axial limitation, wherein the filter (14) is supported on a first stop (17) arranged in the inlet channel (13) and an elastically deformable element, preferably designed as a compression spring (16), is supported between the filter (14) and a second stop (18) arranged in the inlet channel (13).

Description

State of the art

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

[0002] A known valve, referred to as a fuel injection valve, for metering liquid fuel in fuel systems for motor vehicles (DE 10 2005 061 424 A1) has a valve chamber located in a sleeve-shaped valve seat carrier, which is positioned upstream of a valve opening formed in a valve seat body enclosing the valve seat carrier. An electromagnetically actuated closing element, which interacts with a valve seat surrounding the valve opening to control the valve opening, has a closing head that is firmly connected to a hollow cylindrical magnet armature of an electromagnet via a connecting tube. The magnet armature is axially aligned with a hollow cylindrical magnet core. A working air gap of the electromagnet is enclosed between the annular end faces of the magnet core and the magnet armature.The connecting tube, the hollow cylindrical magnet armature, the hollow cylindrical magnet core, and a plastic connecting piece molded onto the magnet core form a fuel inlet channel leading to the closing head, which communicates with the valve chamber via openings in the wall of the connecting tube. A fuel filter is inserted into the connecting piece. The fuel filter is pot-shaped and fixedly mounted in the connecting piece at a radial distance from the inlet channel wall, with the pot opening facing outward, away from the closing head.

[0003] Furthermore, a fuel injection valve is known from DE 10 2008 050 431 B3.

[0004] Such a valve is also sometimes used for exhaust gas aftertreatment in motor vehicles as a metering valve for injecting a urea-water solution into the exhaust gas to reduce the nitrogen oxide content. Due to the high water content, the pressurized solution during vehicle operation freezes even at temperatures below zero. It has been shown that the axial ice pressure that occurs in the intake channel when the solution freezes causes the filter, which is preferably made of plastic, to rupture. Disclosure of the invention

[0005] The valve according to the invention with the features of claim 1 has the advantage that, due to the limited axial displacement of the filter in the inlet channel, the filter can avoid the axial ice pressure, thus preventing any significant pressure from acting on the less stable screen section of the filter. This makes the valve sufficiently resistant to ice pressure even in the screen area and thus suitable for freezing.

[0006] The measures listed in the further claims enable advantageous further developments and improvements of the valve specified in claim 1.

[0007] According to an advantageous embodiment of the invention, the filter is supported on a first stop arranged in the inlet channel, and an elastically deformable element, preferably a compression spring, is supported between the filter and a second stop arranged in the inlet channel. By means of the elastically deformable element or the compression spring, it is achieved in a structurally simple manner that, on the one hand, the filter is axially fixed during operation of the valve and, on the other hand, when the medium in the inlet channel freezes, it is able to evade the resulting axial ice pressure by axial displacement while compressing the element or the compression spring, so that the sieve region of the filter is not subjected to the axial ice pressure.

[0008] According to an advantageous embodiment of the invention, the filter is designed as a sieve bowl with a closed bowl base and a radially projecting collar surrounding the sieve bowl, to which the compression spring engages. The robust collar absorbs the opposing forces of the ice pressure acting on the bowl base and the compression spring acting on the collar, leaving the relatively sensitive sieve region unstressed.

[0009] According to an advantageous embodiment of the invention, the strainer bowl is made of plastic in one piece with two longitudinal webs connecting the bowl base and collar. A strainer cylinder, with one end fixed in the bowl base, extends through the longitudinal webs. Alternatively, the strainer bowl is deep-drawn from metal, and strainer holes are laser-drilled into the bowl shell. With both strainer bowl designs, the valve's ability to move axially in the inlet channel ensures ice-pressure resistance in the strainer area. Short description of the drawings

[0010] The invention is explained in more detail in the following description using exemplary embodiments illustrated in the drawings. They show: Fig. 1 a longitudinal section of a valve for a flowing medium, Fig. 2 an enlarged view of section II in Fig. 1, Fig. 3 a longitudinal section of an alternative embodiment of a filter in the valve according to Fig. 1.

[0011] The Fig. 1 The valve for a flowing medium shown in longitudinal section is used, for example, as a metering valve for metering a freezable liquid. An example of such a liquid is a urea-water solution, which is injected in a metered amount into the exhaust gas of an internal combustion engine using the metering valve to reduce nitrogen oxides in the exhaust gas. The metered medium is subjected to a system pressure of several bar.

[0012] The valve has a valve opening 11, a valve chamber 12 located upstream of the valve opening 11, and an inlet channel 13 for the medium leading to the valve chamber 12. A filter 14 is arranged in the inlet channel 13, which filters out medium components that, due to their size, could cause blockages or damage in the valve.

[0013] The Fig. The filter 14, shown in an enlarged longitudinal section in Figure 2, is designed as a sieve pot 15 with a closed pot base 151 and a radially projecting collar 152 extending circumferentially around the sieve pot 15 and axially spaced from the pot base 151. The sieve pot 15 is made in one piece from plastic with two diametrically opposed longitudinal webs 155 connecting the pot base 151 and the collar 152, and is provided with a sieve cylinder 37, one end of which is inserted into the pot base 151 and passed through the longitudinal webs. The other, free end of the collar 152 is recessed behind the collar.

[0014] In the Fig. In the alternative embodiment shown in Figure 3, the sieve pot 15 is deep-drawn from metal, and the pot shell 153 connecting the pot base 151 and the collar 152 is provided with laser-drilled sieve holes 154. The collar 152 is positioned directly at the pot opening.

[0015] As from Fig. 2, in order to make the valve suitable for freezing in the filter area, the filter 14 is fixed in the inlet channel 13 so that it can be elastically displaced to a limited extent axially. For this purpose, the filter 14, designed as a sieve pot 15, is supported, preferably with the collar 152 on the sieve pot 15, on a first stop 17 formed in the inlet channel 13 and an elastically deformable element, which is preferably a compression spring 16, is supported between the sieve pot 15, preferably between its collar 152, and a second stop 18 arranged in the inlet channel 13. If the medium present in the inlet channel 13 freezes, the axial ice pressure resulting from the increase in volume of the medium presses on the filter 14, in particular on the pot base 151 of the sieve pot 15, and displaces the filter 14 axially against the spring force of the compression spring 16.This prevents the axial ice pressure forces from being introduced into the less stable sieve part of the sieve pot 15 and causing cracks and damage.

[0016] The inlet channel 13 runs in a sleeve-shaped valve seat carrier 20 closed by a valve seat body 19 and in an extension sleeve 21. The valve seat carrier 20 has a carrier section 201 of larger diameter at its end remote from the valve body, with an annular shoulder 202 formed at the transition to the larger-diameter carrier section 201. The extension sleeve 21 dips into the larger-diameter carrier section 201 of the valve seat carrier 20 and, at the end remote from the valve seat carrier, is provided with a connection piece 22 for the medium, here formed integrally with the extension sleeve 21. The valve opening 11 is arranged in the valve seat body 20, and a valve seat 23 enclosing the valve opening 11 is formed.The valve opening 11 is usually followed by a spray hole disk 36 with at least one spray hole (not shown for the sake of clarity), which lies against the end face of the valve seat body 20 facing away from the valve seat 23 and is connected to it, e.g. welded. An electromagnetically actuated closing member 24 for controlling the valve opening 11 cooperates with the valve seat 23. The closing member 24 is loaded in the valve closing direction by a valve closing spring 25 and can be lifted more or less far from the valve seat 23 by means of an electromagnet 26 against the force of the valve closing spring 25 to release the valve opening 11. The closing member 24 has a spherical closing head 27 which is fastened to a hollow cylindrical magnet armature 28 of the electromagnet 26, which is guided axially displaceably in the valve seat carrier 20 and closes the open end thereof pointing towards the valve seat body 19.The valve chamber 12 located in the valve seat carrier 20 is delimited by the sleeve wall of the valve seat carrier 20, the valve seat body 19, and the magnet armature 28, and is connected to the hollow interior of the magnet armature 28 via at least one opening 29 formed in the magnet armature 28. In addition to the magnet armature 28 combined with the closing head 27 in the closing member 24, the electromagnet 26 also has a magnet coil 30 pushed onto the valve seat carrier 20 and a hollow cylindrical magnet core 31 firmly inserted into the valve seat carrier 20, which, together with the magnet armature 28, delimits the working air gap 32 of the electromagnet 26. The magnetic coil 30 is accommodated in a pot-shaped magnet housing 33, which rests against the valve seat carrier 20 with a housing section 331 of reduced diameter and establishes the magnetic return between the magnetic core 31 and the magnet armature 28.The valve closing spring 25 is designed as a compression spring arranged inside the magnetic core 31, which is supported on the one hand on the magnetic armature 28 and on the other hand on an adjusting sleeve 34 fixed in the magnetic core 31, e.g. by pressing or screwing. The inlet channel 13 is thus delimited in the region of the valve seat carrier 20 by the adjusting sleeve 34, the magnetic core 31 and the magnetic armature 28 and closed off at the end by the closing head 27, so that the medium flowing into the inlet channel 13 via the connecting piece 22 reaches the valve chamber 12 via the at least one opening 29 in the magnetic armature 28.

[0017] The filter 14 located in the inlet channel 13, designed as a sieve pot 15, is arranged in the end region of the extension sleeve 21 such that its pot opening points towards the closing head 27 or the valve chamber 12 and covers the magnetic core 31 on its end face facing away from the magnet armature 28. A radial gap 35 ( Fig. 2). The first stop 17 for supporting the strainer cup 15 is formed by the shoulder 202 located at the transition to the larger-diameter support section 201 of the valve seat support 20. The second stop for supporting the compression spring 16 acting on the collar 152 of the strainer cup 15 is formed by the end of the extension sleeve 21 that extends into the valve seat support 20.

Claims

[1] Valve for a flowing medium, in particular a metering valve for metering a freezing liquid, with a valve chamber (12) upstream of a valve opening (11), with an inlet channel (13) for the medium leading to the valve chamber (12) and with a filter (14) arranged in the inlet channel (13) through which the medium flows, characterized by that the filter (14) is fixed in the inlet channel (13) in an axially limited elastically displaceable manner, wherein the filter (14) is supported on a first stop (17) arranged in the inlet channel (13) and an elastically deformable element, preferably designed as a compression spring (16), is supported between the filter (14) and a second stop (18) arranged in the inlet channel (13). [2] Valve according to claim 1, characterized bythat the filter (14) is designed as a sieve pot (15) with a closed pot base (151) and a radially projecting collar (152) running around the sieve pot (15), and that the elastically deformable element acts on the collar (152). [3] Valve according to claim 2, characterized by that the sieve pot (15) is made in one piece from plastic with at least two longitudinal webs (155) offset from one another by circumferential angles, connecting the pot base (151) and the collar (152) and is provided with a sieve cylinder (37) which is fixed with one end in the pot base (151) and is guided through the longitudinal webs (155). [4] Valve according to claim 2, characterized by that the sieve pot (15) is deep-drawn from metal and has a pot shell (153) with laser-drilled sieve holes (154). [5] Valve according to claim 3 or 4, characterized bythat the sieve pot (15) is arranged in the inlet channel (13) with the pot opening facing the valve chamber (12) in such a way that a radial gap (35) remains between the pot shell (153) and the channel wall of the inlet channel (13). [6] Valve according to one of claims 2 to 5, characterized by that the collar (152) is arranged on the pot opening, preferably projecting beyond it, and rests with its annular end face facing the valve chamber (12) on the first stop (17) and that the support of the elastically deformable element is carried out on the annular rear side of the collar (152) facing away from the end face. [7] Valve according to one of claims 1 to 6, characterized byin that the inlet channel (13) runs in a sleeve-shaped valve seat carrier (20) closed off by a valve seat body (19) and an extension sleeve (21) which dips into a larger-diameter carrier section (201) of the valve seat carrier (20) formed at the end of the valve seat carrier (20) remote from the valve seat body and is provided with a connection piece (22) for the medium at the end remote from the valve seat carrier, and in that the first stop (17) is formed by an annular shoulder (202) of the valve seat carrier (20) present at the transition to the larger-diameter carrier section (201) in the valve seat carrier (20) and the second stop (18) is formed by the front end of the extension sleeve (21) which dips into the valve seat carrier (20). [8] Valve according to claim 7, characterized bythat the valve opening (11) is arranged in the valve seat body (19) and is enclosed by a valve seat (23) which cooperates with an electromagnetically actuated closing member (24) for controlling the valve opening (11), that the closing member (24) has a closing head (27) which is fastened to a hollow cylindrical magnet armature (28) of an electromagnet (26) which is displaceably guided in the valve seat carrier (20), wherein the magnet armature (28), closing head (27), valve seat carrier (20) and valve seat body (19) delimit the valve chamber (12) which is connected to the hollow interior of the magnet armature (28) via at least one opening (29) in the magnet armature (28), that a magnet coil (30) is pushed onto the valve seat carrier (20) and a hollow cylindrical magnet core (31) is arranged in the valve seat carrier (20), and that the sieve pot (15) with its pot opening surrounds the magnet core (31) is covered on its end face facing away from the magnet armature (28). [9] Valve according to claim 8, characterized bythat the magnetic coil (30) is accommodated in a pot-shaped magnet housing (33) which bears against the valve seat carrier (20) with a housing section (331) of reduced diameter, and that a valve closing spring (25) which loads the closing member (24) in the valve closing direction is designed as a compression spring inserted in the magnet core (31) and is supported between the magnet armature (28) and an adjusting sleeve (34) inserted into the magnet core (31).

Images