DE102011077972A1 - Valve assembly for internal combustion engine, has valve seat arranged in region of connection piece of exhaust gas duct, and cooling device engaged with exhaust gas duct facing end of metering valve in circumferential direction - Google Patents

Abstract

The valve assembly (1) has a metering valve (6) for controlled introduction of reducing agent into exhaust system of internal combustion engine. A valve seat (7) is arranged in a region of connection piece (5) of exhaust gas duct. A cooling device (10) is equipped for cooling the metering valve and is provided with coolant circuit (13) which is engaged with exhaust gas duct (2) facing the end (16) of metering valve in the circumferential direction. The end of the metering valve is spaced apart from an opening (38) of connecting piece.

Description

The invention relates to a valve arrangement having a metering valve and a valve receptacle for the metering valve, wherein the metering valve is provided for the controlled introduction of a reducing agent in an exhaust tract of an internal combustion engine and the valve receptacle has a cooling device for cooling the metering valve.

State of the art

Valve arrangements of the type mentioned are known from the prior art. Such a valve arrangement has the metering valve and the valve receptacle. The metering valve is arranged at least partially in the valve seat and held or fastened with this. The metering valve serves for the controlled introduction of the reducing agent into the exhaust gas tract or into an exhaust gas line of the exhaust gas tract. The exhaust tract is traversed by the exhaust gas of the internal combustion engine when it is in operation. The internal combustion engine is preferably a diesel internal combustion engine. In this case, a catalyst for carrying out a catalytic purification process of the exhaust gas is provided in the exhaust tract. For this purpose, it is necessary to introduce the reducing agent into the exhaust gas upstream of the catalyst so that it can subsequently pass through the catalyst together with the exhaust gas.

The reducing agent serves to reduce a pollutant contained in the exhaust gas. The reducing agent may for example be a urea-water solution, which is also known under the name AdBlue ^® . The amount of reducing agent to be introduced into the exhaust gas may be different at different times. For this reason, the metering valve is provided with which the reducing agent can be selectively introduced into the exhaust gas or the exhaust gas tract. The exhaust system or the exhaust pipe has the connection piece. This branches off in particular at a certain angle from the exhaust pipe. The valve receptacle is at least partially arranged in the connecting piece, thus engages with at least one area in this. The valve receptacle in turn serves to receive the metering valve and to keep it stationary in the connection piece.

During operation of the valve assembly, the metering valve and the valve seat, due to heat input from the hot, the exhaust gas stream flowing exhaust gas, heat up. The heat input takes place by heat transfer from the exhaust gas to the metering valve or the valve receiving, in particular by convection and / or thermal radiation. However, a maximum permissible operating temperature of the metering valve or the valve receptacle must not be exceeded in order to ensure proper operation of the valve arrangement and to avoid damage. For this reason, the valve holder is associated with the cooling device. This serves to cool the metering valve. For this purpose, the metering valve is thermally connected to the cooling device, so that heat can be dissipated from the metering valve by means of the cooling device. For example, it is known from the prior art that the cooling device has a heat sink which has surface-enlarging ribs, so that the heat of the metering valve can be delivered by means of the heat sink to an environment of the valve arrangement. The cooling device is insofar as passive cooling device, so is not dependent on an energy supply for cooling, but on the lowest possible ambient temperature. Such a heat sink is due to the cooling fins in terms of its space or its space requirement very large. In addition, the ambient temperature, in particular due to the arrangement in the exhaust system, in certain operating modes assume values that are so great that, despite the heat sink, no reliable cooling of the metering valve is possible.

The area of the valve receptacle on which the cooling body or the ribs are present, and thus also the metering valve, must therefore be arranged to a large extent or even completely outside the connecting piece. In order to achieve a certain cooling capacity, the heat sink must have a certain size or a certain surface size. However, this is usually only achievable if there is a comparatively large distance of the metering valve from the exhaust gas tract or the exhaust gas line. Due to the dimensions of the heat sink with its cooling fins a closer arrangement of the metering valve on the exhaust pipe is therefore not possible. However, such would be advantageous in terms of the formation of deposits. Deposits are, for example, to be understood as deposits which result from the introduction of the reducing agent into the exhaust gas tract, in particular thus reducing agent deposits or corresponding secondary products which arise as a result of a reaction of the introduced reducing agent.

From the DE 10 2008 001 092 A1 For example, a reducing agent supply apparatus is known which supplies a reducing agent to exhaust gas discharged from an internal combustion engine. The reducing agent supply apparatus has a supply pump that discharges the reducing agent from a predetermined tank, an injection valve that is mounted on an exhaust pipe, through which the exhaust gas and discharges the reducing agent discharged from the feed pump into the exhaust passage, and a heat removing means which removes heat from the reducing agent stored in the tank. It is provided that the reducing agent is sprayed directly into the exhaust pipe. However, this requires an at least regional arrangement of the metering valve in the exhaust pipe, so that it is acted upon directly by the exhaust gas with heat, resulting in a high temperature load. Such an arrangement is also susceptible to deposits which accumulate on the projecting into the exhaust pipe metering valve, which is directly flowed by the exhaust gas accumulate.

Disclosure of the invention

In contrast, the valve arrangement with the features mentioned in claim 1 has the advantage that the metering valve can be arranged close to the exhaust pipe, in particular in a direct comparison with valve arrangements which have the mentioned heat sink with ribs. This is inventively achieved by the valve holder is at least partially disposed in a connecting piece of the exhaust gas and the cooling device has a cooling liquid circuit having a cooling body, which surrounds an exhaust tract facing the end of the metering valve in the circumferential direction at least partially, wherein the end of the metering valve of an orifice of the connecting piece is spaced in an exhaust pipe of the exhaust tract. As a result of the at least regional arrangement of the valve receptacle and thus also of the metering valve in the connection piece of the exhaust gas tract, an outlet of the metering valve, from which the reducing agent exits in the direction of the exhaust gas tract, is arranged closer to the exhaust gas tract or the exhaust gas line than is the case with valve arrangements. which have the heat sink with cooling fins. Due to the closer arrangement of the metering valve to the exhaust tract, it is subjected to a larger amount of heat. In addition, because the cooling fins omitted in favor of the closer positioning of the metering valve to the exhaust tract, this higher amount of heat must be removed in other ways.

For this purpose, the cooling device has the cooling liquid circuit, that is, it is designed as a liquid cooling device, which can be supplied with cooling liquid for cooling the metering valve. In other words, the cooling device has the heat sink, in which the metering valve is arranged and which has the cooling liquid circuit. The cooling liquid is different in particular from the reducing agent. For example, the cooling liquid can be taken from a cooling circuit of the internal combustion engine. The cooling device is insofar an active cooling device, that is, it requires an energy supply for cooling, which is used according to the invention for supplying cooling fluid by means of a coolant delivery device. For supplying the cooling device or the cooling liquid circuit with cooling liquid, the cooling body or the valve receptacle has at least one cooling liquid connection. This can be connected to a coolant line or a coolant tube, for example by means of a spring band clamp. The cooling device designed in this way can thus readily be arranged at least in some areas in the connecting piece. In order to ensure a reliable cooling of the metering valve, the heat sink should surround that end of the metering valve in the circumferential direction at least partially, which faces the exhaust gas tract. In this respect, this end of the metering valve has the outlet for the reducing agent, by means of which the reducing agent can be introduced into the exhaust gas which flows through the exhaust gas tract.

The end of the metering valve or its outlet is spaced from the mouth of the connecting piece in the exhaust pipe of the exhaust tract. The mouth is represented by an opening in a wall of the exhaust pipe, on which the connecting piece is arranged. As a result, the reducing agent emerging from the metering valve passes through the mouth into the exhaust gas tract or the exhaust gas line.

A development of the invention provides that the valve receptacle has a passage opening in which a passage region of the metering valve is at least partially disposed, wherein there is at least in regions between walls of the passage opening and the passage area in the radial direction a gap. The passage opening preferably passes completely through the valve receptacle in the axial direction. It can have different dimensions or diameter (in a circular cross-section). At the metering valve, the passage area is provided. This passage area should now be arranged in the valve receptacle. Preferably, the passage region of the metering valve fully penetrates the passage opening. However, it can also be provided that the end of the metering valve facing the exhaust tract is spaced from the likewise the exhaust tract facing the end of the passage opening, so this does not pass.

Both the passage opening and the passage area each have a wall, wherein the wall of the passage opening an inner wall and the passage area a Outside wall is. The passage area should now be arranged in the passage opening in such a way that the walls are spaced apart from one another in the radial direction, so that the gap exists at least partially between them. The gap therefore does not have to extend over the entire longitudinal extent of the passage opening or of the passage area (although this may be the case), but may be present only over part of the longitudinal extent. It is particularly advantageous if the gap is closed on its side facing away from the exhaust tract, so does not extend to the exhaust tract. In this embodiment, the inner wall of the passage opening and the outer wall of the passage area are substantially in surface contact contact in order to close the gap in the direction of the exhaust gas tract.

A gap between the metering valve and the valve seat is initially undesirable because the thermal connection between the metering valve and the cooling device having valve receptacle is interrupted. The heat with which the metering valve is acted upon by the exhaust gas, thus can not be reliably dissipated. However, for example, the gap may be at least partially utilized to locate a fastener or sealant between the metering valve and the valve seat.

A further development of the invention provides that at least one heat-conducting element, in particular consisting of graphite, is arranged in the gap. The heat-conducting element serves to improve the thermal connection of the metering valve to the valve seat. In this way, despite the gap, an excellent heat transfer and thus efficient cooling of the metering valve, in particular its outlet, can be ensured. For this purpose, the heat-conducting element is preferably made of a good heat-conducting material, such as graphite or a metal. The heat-conducting element surrounds the passage region at least regionally, preferably completely in the circumferential direction. The gripping can be particularly ring-like. To produce the thermal connection, it must be ensured that the heat-conducting element is in touching contact with both the metering valve and the valve seat. The contact contact is provided in particular to the walls of the passage opening and the passage area.

A development of the invention provides that the heat-conducting element is pressed onto the passage region and / or pressed into the passage opening. By pressing or pressing in a particularly good thermal connection of the heat-conducting is achieved to the metering valve or the valve seat, because thus a substantially full-surface contact between the heat conducting element and the respective other element is given. To improve the heat transfer between the heat-conducting element and the respective other element, it may also be provided that a heat-conducting agent, for example a thermal compound, is applied to the heat-conducting element or the respective other element before the heat-conducting element is pressed or pressed in. It can be provided either to press the heat-conducting element onto the passage region or to press it into the passage opening. However, it is particularly advantageous if the heat-conducting element is pressed on both the passage region and pressed into the passage opening. This can be done, for example, such that upon assembly of the valve assembly, first the heat-conducting element is pressed onto the passage region and then pressed together with the metering valve into the passage opening.

A development of the invention provides that the passage region is held in the passage opening by means of the heat-conducting element and / or a seal at least in the radial direction. Because the heat conducting element is preferably designed such that it completely fills the gap in the radial direction and in particular can be pressed both with the passage region and with the passage opening, it effectively prevents a displacement of the metering in the Dosieraufnahme. Additionally or alternatively, the seal may be provided, which is present in particular as a form-sealing element or Grommet. The mold sealing element is a ring or a spout, which is arranged in the valve receptacle or its passage opening and which in turn has a passage opening through which the metering valve or its passage area can pass. The mold sealing element is preferably made of an elastic material, in particular rubber or a plastic. Also by means of the mold sealing element, the metering valve can be held at least in the radial direction with respect to the valve seat. In addition, however, holding in the axial direction is possible by means of the heat-conducting element or the shape-sealing element, in particular if the heat-conducting element is pressed or pressed both onto the passage region and into the passage opening. If holding in the axial direction can not be realized by means of the heat-conducting element or the shape-sealing element, an additional holding device for holding in the axial direction is preferably provided, for example a clip.

A development of the invention provides that on the heat sink at least one Sealing element is provided, which sealingly engages over an open-edged recess of the heat sink. The open-edged recess is in this case a component of the coolant circuit, so that the coolant flows through during the operation of the valve arrangement. The recess forms so far the coolant circuit with. It is preferably provided on the front side of the heat sink. The open-edge design of the recess allows easy production of the heat sink. During this, the recess is initially formed open edge in the heat sink and then arranged the sealing element over the recess such that a flow channel for the cooling liquid is present. The flow channel is so far formed by the heat sink and the sealing element together. The sealing element can be connected, for example, by laser welding to the heat sink. Alternatively, the recess may also be present on a lateral surface of the heat sink. In this case, the sealing element surrounds the heat sink in the circumferential direction at least partially, in order to close the recess.

A development of the invention provides that at least one shielding element is provided on the heat sink for shielding the exhaust tract facing the end of the metering valve with respect to the exhaust gas tract. The shielding element prevents so far at least partially, preferably completely, that exhaust gas from the exhaust tract accesses the exhaust tract facing the end of the metering valve and thus a convective heat transfer between the exhaust gas and the metering occurs. It is particularly advantageous if the shielding element is arranged such that it separates the cooling body or the sealing element fluidly from the exhaust tract at least in areas, preferably completely. The shielding element thus provides a heat shield of the valve arrangement at least for areas of the metering valve and the valve receptacle. In addition to the convection, the shielding element also at least partially, preferably completely, prevents the heat transfer from the exhaust gas to the metering valve by heat radiation and thus additionally serves as a heat radiation shield. Overall, as far as possible extensive thermal decoupling between the exhaust gas tract and the metering valve is achieved with the shielding element. Preferably, it consists of a material which is thermally fast, that is, in particular characterized by a good thermal conductivity.

The shielding element also makes it possible to adapt the dosing valve in a simple manner to different configurations of the exhaust gas tract. For example, the same metering valve can be installed by means of different shielding elements in different exhaust tracts, wherein in each case a shielding element is adapted to a corresponding exhaust tract. Thus, a modular system for the metering valve assembly is realized.

Advantageously, the reducing agent introduced by means of the metering valve does not come into touching contact with the shielding element. In this way, adverse deposits on the shielding can be prevented. However, the shielding element can still be provided additionally or alternatively to the guidance of the fluid in the direction of the exhaust gas tract and to that extent also be referred to as a fluid guide element. The shielding element thus has a flow connection from the outlet of the metering valve to the exhaust gas tract. From the outlet of the metering valve escaping reducing agent should therefore be performed by means of the shielding in the direction of the exhaust gas tract. For this purpose, this preferably has a Fluidleitbereich, which may be frusto-conical. In this case, the end of the fluid-conducting region having the smaller dimensions is preferably facing the outlet of the metering valve and the end having the larger dimensions facing the exhaust gas tract. The Fluidleitbereich is so far funnel-shaped.

The shielding element thus not only prevents the exhaust gas from being able to enter the region of the valve arrangement or the sealing element covered by the shielding element, but can additionally serve to guide the reducing agent. In such an embodiment, it can also be provided that the shielding element or the fluid-conducting element are arranged such that at least its surface exposed to the reducing agent assumes temperatures at which a degradation process of the reducing agent takes place. For the urea-water mixture described above, these temperatures are about 300 ° C to 350 ° C. Of course, for a (additional) heating of the Fluidleitelements a heater may be provided.

A further development of the invention provides that the shielding element is flush with the mouth of the connecting piece in the exhaust pipe of the exhaust tract. Thus, portions of the connecting piece, which are not flowed through during the introduction of the reducing agent by means of the metering valve of the reducing agent, fluidly separated. Thus, the exhaust gas and the reducing agent can not reach or at best in small quantities or with a low throughput in these areas. Thus, on the one hand a heat application of the metering valve or of the heat sink is reduced and on the other deposits in these areas largely prevented. By the flush closing of the shielding with the In addition, no flow disturbances or vortices in the exhaust gas, which would significantly increase the flow resistance of the exhaust gas tract, arise.

A further development of the invention provides that the shielding element at least partially surrounds the heat sink in the circumferential direction, preferably at a radial distance. In this case, the shielding is held in the connection piece or on the wall thereof. Preferably, the shielding element as little as possible in contact with the heat sink in contact, to avoid unnecessary heat input in this. For this purpose, the shielding element can be arranged at a radial distance from the heat sink. For example, the shielding element bears against the wall of the connecting piece, while the cooling element has smaller dimensions in the radial direction and thus at least partially complies with the radial distance from the shielding element.

A development of the invention provides that a longitudinal axis of the metering valve with an axis of the exhaust pipe of the exhaust gas tract an angle of less than 90 °, in particular from 30 ° to 60 °, preferably exactly 30 ° or 60 °, includes. During the introduction of the reducing agent by means of the metering valve, the reducing agent thus has at least one component of movement which runs parallel to the main flow direction in the exhaust gas tract. The main flow direction is in the direction of the longitudinal axis of the exhaust pipe. The desired arrangement of the metering valve is usually achieved by a corresponding arrangement of the connecting piece. This means that its longitudinal axis with the longitudinal axis of the exhaust pipe also includes the said angle. In this way, it is particularly prevented that an excessive amount of the exhaust gas penetrates into the connecting piece and thus can penetrate in the direction of the metering valve. Thus, the thermal load of the metering valve is further reduced.

The invention will be explained in more detail below with reference to the embodiments illustrated in the drawing, without any limitation of the invention. Show it:

1 a longitudinal section through an exhaust tract of an internal combustion engine and a valve assembly in a first embodiment,

2 the one from the 1 known longitudinal section with a valve arrangement according to a second embodiment,

3 the valve arrangement after a first assembly step,

4 the valve assembly during a second assembly step,

5 the valve assembly after the second assembly step, and

6 the valve assembly after a third assembly step.

The 1 shows a longitudinal section through a valve assembly 1 and an exhaust tract 2 an internal combustion engine, not shown. The exhaust tract 2 has at least one exhaust pipe 3 pointing in the direction of the arrow 4 of exhaust gas, which is generated by the internal combustion engine, can be flowed through. In the exhaust pipe 3 opens a connecting piece 5 a, in which the valve assembly 1 at least partially arranged and fixed. The valve arrangement 1 consists of a metering valve 6 and a valve seat 7 ,

The metering valve 6 is for the controlled introduction of a reducing agent, which by a reducing agent line 8th can be supplied, provided. The metering valve 6 is for this purpose via a control terminal 9 controllable and / or controllable. Via the control connection 9 is the metering valve 6 in this respect connected to a not shown here control unit. Because that's the exhaust pipe 3 flowing exhaust gas has a high temperature and thus also the metering valve 6 is heated and thus heats up, it is necessary to the metering valve 6 to keep its temperature below a maximum allowable operating temperature. For this purpose, the valve seat 7 a cooling device 10 on. In the embodiment shown here, the cooling device 10 a liquid cooling device, thus has at least one cooling liquid circuit 11 , of which only a part is recognizable here. The coolant circuit 11 is at least partially formed by an open-edged recess 12 a heat sink 13 , which of a sealing element 14 sealingly overlapping. The open-edged recess 12 reaches through an end face 15 of the heat sink 13 ,

For a particularly efficient cooling of the metering valve 6 to ensure is an end facing the exhaust tract 16 at which an outlet 17 of the metering valve 6 is present, from the heat sink 13 in the circumferential direction at least partially, preferably completely, embraced. This is in the 1 clearly visible. Preferably, the encompassing is to be understood as an immediate encompassing, in which the heat sink 13 in the area of the end 16 or the outlet 17 directly with the metering valve 6 is in touching contact. In this way, an excellent thermal connection of the metering valve 6 to the cooling device 10 or the heat sink 13 ensures that the metering valve 6 can be cooled efficiently. For the arrangement of the metering valve 6 indicates the valve seat 7 a passage opening 18 on, which here essentially in the heat sink 13 is present. The metering valve 6 on the other hand has a passage area 19 which at least partially in the passage opening 18 is arranged. It should be between a wall 20 the passage opening 18 and a wall 21 of the passage area 19 A gap 22 be formed, which is at least over part of the longitudinal extension of the passage opening 18 extends.

To the heat transfer between the metering valve 6 and the heat sink 13 despite the gap 22 Sufficient to dimension is in the gap 22 at least one heat conducting element 23 (here two heat-conducting elements 23 ) arranged. The heat-conducting elements 23 surround the passage area 19 in the circumferential direction preferably completely. They are ring-shaped for this purpose. It can be provided that the heat conducting elements 23 on the passage area 19 of the metering valve 6 are pressed on. Additionally or alternatively, the heat-conducting elements 23 in the passage opening 18 be pressed. By means of the heat-conducting elements 23 is a hold of the passage area 19 in the passage opening 18 achieved at least in the radial direction. In addition, however, is a seal 24 provided, which also in the passage opening 18 present and the passage area 19 completely encompasses in the circumferential direction. The seal 24 is present as a form sealing element or Grommet. The seal 24 consists preferably of an elastic material, in particular rubber.

Because by means of the heat-conducting elements 23 and the seal 24 a hold of the passage area 19 or of the metering valve 6 in the valve holder 7 is achieved only in the radial direction, serves a holding device 25 holding the metering valve 6 regarding the valve seat 7 and also the connecting piece 5 in the axial direction. The holding device 25 is formed in the present embodiment by a screw. This is a holding plate 26 by means of a screw 27 at the valve seat 7 or the heat sink 13 attached. The retaining plate 26 engages in a not shown here groove of the metering valve 6 a, so the latter in the axial direction opposite the valve seat 7 is held.

By means of another holding device 28 is the valve seat 7 on the connecting piece 5 held. For the formation of the holding device 28 have the connecting pieces 5 a retaining flange 29 and the valve seat 7 a retaining flange 30 on. The retaining flanges 29 and 30 are in the axial direction by means of an insulating part 31 spaced apart. The insulating part 31 consists preferably of a poor thermal conductivity material, so that a thermal decoupling of the valve seat 7 from the connecting piece 5 is reached. To hold the two retaining flanges 29 and 30 a retaining ring serves each other 32 , the two retaining flanges 29 and 30 engages in each case to form a rear grip, so that the two retaining flanges 29 and 30 in the axial direction can not be removed from each other. The retaining ring 32 rather pushes the retaining flanges 29 and 30 each in the direction of the insulating part 31 ,

The valve arrangement 1 also has a shielding element 33 on which of the thermal decoupling of the metering valve 6 from the exhaust tract 2 or the exhaust gas flowing through it serves. The shielding element 33 consists of a first isolation area 34 and a second isolation area 35 , The first isolation area 34 In addition to its decoupling function, it can also guide the reducing agent in the direction of the exhaust tract 2 or the exhaust pipe 3 serve. It can be referred to as Fluidleitbereich accordingly. The first isolation area 34 is in the embodiment proposed here substantially frusto-conical and thereby arranged such that its smaller dimensions end having the metering valve 6 or its outlet 17 and its larger dimensions end having the exhaust tract 2 is facing. The first isolation area 34 can form a diffuser for the reducing agent so far. However, any other configuration is possible.

The metering valve is preferred 6 or its outlet 17 and the shielding element 33 or its first isolation area 34 arranged such that upon introduction of the reducing agent by means of the metering valve 6 this is not in touching contact with the shielding element 33 device, so it can not be deposited on it. The second isolation area 35 surrounds the first isolation area 34 and serves in particular its positioning within the connecting piece 5 , In this case, the shielding element 33 or the second isolation area 35 at least partially from an inner wall 36 of the connecting piece 5 spaced in the radial direction. This applies in particular to areas of the shielding element 33 , which in the connecting piece 5 in the axial direction of the metering valve 6 (indicated by the longitudinal axis 37 ) and a mouth 38 is present, at which the connecting piece 5 in the exhaust pipe 3 or the exhaust tract 2 opens.

The shielding element 33 surrounds the valve holder 7 in the circumferential direction at least partially. It preferably extends up to the holding device 28 and is attached by means of this. For this purpose, also the shielding element 33 a retaining flange 39 on which between the retaining flange 29 of the connecting piece 5 and the insulating part 31 is held clamped. In the area in which the shielding element 33 the valve holder 7 surrounds at least partially, it is spaced from this in the radial direction. For this purpose, it is in this area, for example, on the inner wall 36 of the connecting piece 5 at. In this way, the shielding element 33 thermally from the valve seat 7 decoupled. This is advantageous because the shielding element 33 from which the exhaust pipe 3 flowing through exhaust gas is subjected to a large amount of heat and thus has a high temperature. It should now be prevented that the heat with which the shielding 33 is applied directly to the valve seat 7 passed and thus the cooling effect of the cooling device 10 will affect.

On the exhaust tract 2 facing side of the shielding 33 should this with the estuary 38 of the connecting piece 5 in the exhaust pipe 3 finish flush. This means that no area of the shielding element 33 in the exhaust pipe 3 present, however, the connecting piece 5 at least in the direction of the exhaust tract 2 essentially completely. In this way, on the one hand, an efficient guidance of the means of the metering valve 6 achieved by reducing agent and on the other is by the shielding 33 , in particular by the interaction of the first isolation area 34 and second isolation area 35 ensures that the exhaust gas is not or only in small quantities in between a first isolation area 34 and metering valve 6 or valve intake 7 lying gap 40 can get. In this way, both the metering valve 6 as well as the valve holder 7 protected from additional heat input from the exhaust gas, in particular by convection and / or thermal radiation.

With the valve arrangement described above 1 can the distance between the outlet 17 of the metering valve 6 to the exhaust pipe 3 or the mouth 38 be significantly reduced compared to conventional valve arrangements. At the same time, however, continues to be an excellent cooling of the metering valve 6 provided and the occurrence of deposits on the metering valve 6 , the dose intake 7 or in the connecting piece 5 effectively prevented or at least reduced. In the in the 1 illustrated embodiment of the valve assembly 1 lies between the longitudinal axis 37 of the metering valve 6 and a longitudinal axis 41 the exhaust pipe 3 an angle of 30 ° before.

The 2 shows a further embodiment of the valve assembly 1 , This corresponds essentially to the basis of the 1 described, so that reference is made to the above statements. The difference between the two embodiments lies in the between the longitudinal axis 37 and the longitudinal axis 41 present angle. This is 60 ° instead of 30 ° for the present embodiment.

The 3 shows the dosing valve 6 and the valve seat 7 after a first manufacturing step. The metering valve 6 is shown only schematically. From the valve holder 7 lies after the first manufacturing step, only one end element 42 in front of which attachment areas 43 for the holding device 25 available. The attachment areas 43 have recesses through which the screws 27 pass. The final element 42 has a ring channel 44 on, posing as an annular recess in the final element 42 represents, however, is not present in the present embodiment over the entire scope. In the ring channel 44 open a cooling fluid inlet 45 and a coolant outlet 46 one.

The 4 shows the valve assembly 1 during a second assembly step. In the process, the heat-conducting elements already became 23 on the dosing valve 6 or its passage area 19 pressed. Subsequently, the heat sink 13 with the recesses 12 pushing him in the direction of the longitudinal axis 37 completely pass through, on the closing element 42 put on or in the annular channel 44 used. The ring channel 44 has dimensions that are those of a ring flange 47 of the heat sink 13 correspond. It becomes clear that the recess 12 the heat sink 13 not fully encompassed in the circumferential direction. Rather, it is a footbridge 48 provided, which the recess 12 interrupts in the circumferential direction.

The 5 shows the valve assembly 1 after the second production step. The heat sink 13 now sits in the ring channel 44 such that the recess 12 towards the conclusion element 42 is sealed, so only coolant through the coolant inlet 45 enter and through the Kühlflüssigkeitsauslass 46 (both not visible here) can escape.

Subsequently, in a third assembly step, as in the 6 shown, the sealing element 14 on the heat sink 13 placed on and attached to this, for example by means of laser welding. With the sealing element 14 becomes the recess 12 also on the final element 42 opposite side of the heat sink 13 locked. The recess 12 is thus sealed so that only through the coolant inlet 45 Coolant enter it and through the Kühlflüssigkeitsauslass 46 can escape again. In this way is an efficient and space-saving cooling device 10 for the metering valve 6 realized, which is also easy and inexpensive to produce.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102008001092 A1 [0006]

Claims (10)

Valve arrangement ( 1 ) with a metering valve ( 6 ) and a valve seat ( 7 ) for the metering valve ( 6 ), whereby the metering valve ( 6 ) is provided for the controlled introduction of a reducing agent in an exhaust gas tract of an internal combustion engine and the valve seat ( 7 ) a cooling device ( 10 ) for cooling the metering valve ( 6 ), characterized in that the valve seat ( 7 ) at least partially into a connecting piece ( 5 ) of the exhaust tract ( 2 ) is arranged and the cooling device ( 10 ) via a heat sink having a cooling liquid circuit ( 13 ), the one the exhaust tract ( 2 ) facing end ( 16 ) of the metering valve ( 6 ) circumferentially at least partially surrounds, wherein the end ( 16 ) of the metering valve ( 6 ) from a mouth ( 38 ) of the connecting piece ( 5 ) in an exhaust pipe ( 3 ) of the exhaust tract ( 2 ) is spaced. Valve arrangement according to claim 1, characterized in that the valve seat ( 7 ) a passage opening ( 18 ), in which a passage region ( 19 ) of the metering valve ( 6 ) is at least partially arranged, wherein between walls ( 20 . 21 ) of the passage opening ( 18 ) and the passage area ( 19 ) in the radial direction at least partially a gap ( 22 ) is present. Valve arrangement according to one of the preceding claims, characterized in that in the gap ( 22 ) at least one heat conducting element ( 23 ), in particular made of graphite, is arranged. Valve arrangement according to one of the preceding claims, characterized in that the heat-conducting element ( 23 ) on the passage area ( 19 ) and / or in the passage opening ( 18 ) is pressed. Valve arrangement according to one of the preceding claims, characterized in that the passage area ( 19 ) in the passage opening ( 18 ) by means of the heat conducting element ( 23 ) and / or a seal ( 24 ) is held at least in the radial direction. Valve arrangement according to one of the preceding claims, characterized in that on the heat sink ( 13 ) at least one sealing element ( 14 ), which has an open-edged recess ( 12 ) of the heat sink ( 13 ) sealingly overlaps. Valve arrangement according to one of the preceding claims, characterized in that at least one shielding element ( 33 ) for shielding the exhaust tract ( 2 ) facing end ( 16 ) of the metering valve with respect to the exhaust gas tract ( 2 ) is provided. Valve arrangement according to one of the preceding claims, characterized in that the shielding element ( 33 ) with the mouth ( 38 ) of the connecting piece ( 5 ) in the exhaust pipe ( 3 ) of the exhaust tract ( 2 ) flush. Valve arrangement according to one of the preceding claims, characterized in that the shielding element ( 33 ) the heat sink ( 13 ) surrounds at least partially in the circumferential direction, preferably at a radial distance. Valve arrangement according to one of the preceding claims, characterized in that a longitudinal axis ( 37 ) of the metering valve ( 6 ) with a longitudinal axis ( 41 ) of the exhaust pipe ( 3 ) of the exhaust tract ( 2 ) includes an angle of less than 90 °, in particular from 30 ° to 60 °, preferably exactly 30 ° or 60 °.

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