Abstract:
The invention relates to a device for cooling a metering module, in particular a module for metering an operating agent/auxiliary agent such as a reducing agent into the exhaust gas system of an internal combustion engine. A cooling device through which a cooling fluid flows is associated with the metering module ( 10 ). An outer surface ( 34 ) of the metering module ( 10 ) is enclosed by a cooling member ( 18, 20, 22 ) through which the cooling fluid flows. The multi-part cooling member ( 18, 20, 22 ) comprises drainage openings ( 30 ) for discharging ( 78 ) the cooling fluid/for discharging liquids in order to prevent said fluid/liquids from accumulating on the bottom of the cooling member ( 18, 20, 22 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    DE 44 36 397 A1 relates to a device for the aftertreatment of exhaust gases. According to this solution, a reducing agent is introduced into the exhaust gas which is fed to the catalyst. The introduction is carried out in this case via an electrically controlled metering valve which is combined with a control valve in a common housing. The control valve serves for the controlled introduction of supplied pressurized air, in which a quantity of reducing agent, which is received via the metering valve, is processed and intermittently introduced into the exhaust gas. As a result, urea deposits and agglutinations on the metering valve and control valve can be avoided and an optimum processing of the introduced reducing agent can be achieved. 
         [0002]    US 2010 0313553 relates to an injector for exhaust gas aftertreatment, which introduces an urea solution for lowering NOx emissions in an exhaust gas system. In this case, the injection end of the injector is enclosed by an inner housing and an outer housing. A gap which results between the inner housing and the outer housing serves as a temperature barrier. The outer housing is of nozzle-like design and allows the mounting of the injector inside an exhaust gas pipe by means of a flange. 
         [0003]    U.S. Pat. No. 5,647,316 relates to an injector device for an internal combustion engine for introducing a pressurized fluid into a cylinder space. The injector in this case comprises a first valve and a second valve. Whereas the first valve serves for injecting fuel, the second valve serves for introducing an auxiliary substance, for example water or a urea solution. The second valve is operated by means of a valve element. This valve element is hydraulically actuated via a hydraulic line. A drainage line, by means of which surplus hydraulic fluid can be drained off and fed to a tank, is located on the valve element. 
         [0004]    DE 10 2009 047 375 A1 relates to a metering module with fluid cooling. Disclosed there is a device for cooling a metering module, especially for the metered feed of a reducing agent into the exhaust gas tract of an internal combustion engine. A cooling device, through which flows a cooling fluid, is associated with the metering module. A generated surface of the metering module is enclosed by a cooling body through which flows a cooling fluid. 
         [0005]    A disadvantage of known active cooling solutions is the absence of cooling effect in the upper region, especially in the electrical contact region of an injection valve of the metering module. As a result, there is no possibility of using the metering module at an ambient temperature level above 160° C. The electrical plug-in connector and the coil of the injection valve can suffer damage at a temperature level which lies above 160° C. 
       SUMMARY OF THE INVENTION 
       [0006]    According to the invention, it is proposed to enclose a metering module, especially for introducing an operating/auxiliary substance, such as a reducing agent, into the exhaust gas tract of an internal combustion engine, by means of a housing which enables cooling of the entire metering module. As a result of the arrangement of at least one drainage opening, it is ensured that the forming of a sump as a result of fluid residue being deposited in a part of the cooling body of one-piece or multi-piece design, which encloses the metering module as a complete housing, is minimized and ideally totally excluded. 
         [0007]    Drainage openings can advantageously be formed, for example with a 90° spacing or with a 120° spacing, on a part, for example on an annularly formed collar of a cup-shaped insert. Particularly when the channel-like recesses in the annular surface of the cup-shaped insert of the cooling body of multi-piece design extend in the radial direction, it is ensured that transporting away of the fluid can be facilitated as a result of the radial inclination of the channel-like recesses from the inside outward. 
         [0008]    As a result of the solution proposed according to the invention concerning the provision of drainage openings, whether they be with a 90° spacing or with a 120° spacing, in the case of a cooling body of one-piece or multi-piece design the forming of a sump in this can be avoided. The forming of a sump on the one hand can lead to corrosion phenomena, and on the other hand, in addition to corrosion phenomena on the cooling body, electrical short circuits can also occur on the electrically operated components of the metering module, especially in the region of the plug-in contact, so that the operability of the metering module cannot be ensured in all the operating phases, especially during fording or the like. 
         [0009]    As a result of the solution proposed according to the invention, a transporting away of fluid, whether it be infiltrated water or condensation water, from the interior of the cooling body of one-piece or multi-piece design is ensured. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    With reference to the drawing, the invention is described in more detail below. 
           [0011]    In the drawing: 
           [0012]      FIG. 1  shows a perspective plan view of a metering module which is enclosed by a complete housing in the form of a cooling body of multi-piece design, 
           [0013]      FIG. 2  shows a section through the metering module represented in  FIG. 1 , and 
           [0014]      FIG. 3  shows a perspective plan view of the metering module with the center shell removed, 
           [0015]      FIG. 4  shows a view of channel-like recesses which on an annularly formed collar extend with an inclination from the inside outward in the radial direction, 
           [0016]      FIG. 5  shows a perspective view of the metering module with channel-like recesses which are arranged with a 90° spacing, and 
           [0017]      FIG. 6  shows a view of the cooling fluid flow through the lower region of the metering module. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]      FIG. 1  shows a perspective view of a metering module which is enclosed by a housing, wherein the housing is formed from a plurality of components. 
         [0019]      FIG. 1  shows that a metering module  10  comprises a housing  12 . An electrical contact—not shown in FIG.  1 —which lies inside the metering module  10 , is enclosed by a plug cover  14  and towards the outside is sealed against spray water. Furthermore, the housing  12  comprises an upper shell  18  in which is located a reducing agent inlet  16  of angled design. Located beneath the upper shell  18  is a center shell  20 , below which is arranged in turn a rotatable flange  22  of the housing  12  of the metering module  10 . 
         [0020]    As also apparent from the view according to  FIG. 1 , an inner part  28  is let into the rotatable flange  22 . A cooling fluid inlet  24  and a cooling fluid outlet  26  are located at the side on the generated surface of the center shell  20  and of the rotatable flange  22  respectively. Via the cooling fluid inlet  24 , cooling fluid, which for example circulates in an internal combustion engine, enters the rotatable flange  22  of the housing  12 , and discharges again through the cooling fluid outlet  26  which is located at the side on the generated surface of the center shell  20 . The cooling fluid transports heat from the metering module  12  and ensures that depending upon the temperature level cooling of the metering module  10  and therefore maintaining of the operability of said metering module at a temperature level of approximately 120° C. or even above can be ensured. 
         [0021]    From the view according to  FIG. 1  it can be gathered that drainage openings  30  in the form of channel-like recesses can be formed along an annularly formed collar  60  of the rotatable flange  22 —compare more detailed views according to  FIG. 3 . 
         [0022]      FIG. 2  shows a sectional view through the metering module according to the view in  FIG. 1 , the housing of which is of multi-piece design. 
         [0023]    From the sectional view according to  FIG. 2  it is apparent that the housing  12  encloses the upper shell  18  along with the reducing agent inlet  16  of angled design. The upper shell  18  is located above the center shell  20  and covers this like a cap, for example. The center shell  20  in its turn encloses a generated surface  34 , i.e. a surface of the metering module  10  which is to be cooled. Located beneath the center shell  20  is the rotatable flange  22  which in its turn accommodates an inner part  28  which encloses the end of a metering valve  32  via which the operating/auxiliary substance, especially the reducing agent, is introduced into the exhaust gas tract of the internal combustion engine during operation of the metering module  10 . 
         [0024]    From the sectional view according to  FIG. 2  it can be gathered that the reducing agent inlet  16  extends through the center shell  18  and merges into the metering valve  32  on the upper end face. The upper shell  18  is sealed against the metering valve  32  by means of a sealing ring  36 . The operating/auxiliary substance, especially the reducing agent, flows through the interior of the metering valve  32 —not shown here in more detail—to the “hot” part of the metering valve  32  in which is accommodated an injection valve via which the operating/auxiliary substance is injected into the exhaust tract—not shown here in more detail—of an internal combustion engine. 
         [0025]    If like in the views according to  FIGS. 1 and 2  the reducing agent inlet  16  is of an angled design and is oriented in one plane with regard to the cooling fluid inlet  24  and also of the cooling fluid outlet  26 , the possibility exists, depending upon installation conditions, of arranging the reducing agent inlet  16  in a horizontal plane in any positions spanning 360° on the upper shell  18 . This is dependent upon the available installation space, the length of the connecting hoses or connecting lines—and also upon further installation parameters. 
         [0026]    The metering valve  32  is enclosed by a cooled surface  34  according to the sectional view in  FIG. 2 . The center shell  20  which is arranged beneath the upper shell  18  on the one hand includes a cavity  42  which receives a cooling fluid and on the other hand includes a cavity  44  which does not come into contact with cooling fluid, i.e. in the present context can be referred to as being dry. 
         [0027]    Located in the cavity  44  is an electrical plug-in contact  46  which by means of the plug-in connector cover  14 , which is already explained in conjunction with  FIG. 1 , is protected against spray water and dirt. 
         [0028]      FIG. 2  shows that a separating ring  38  extends on the inside with regard to the cooled surface  34  of the metering module  10 . On the outside, the cooled surface  34  of the metering module  10  with the inner side of the center shell  20  delimits a cavity  42  which receives the cooling fluid. This cavity extends in the circumferential direction around the metering valve  32 . Part of this cavity  42  is also a cavity part which is separated by a dividing wall  40  from the radially inner cavity  44  which is not in contact with cooling fluid. 
         [0029]    The rotatable flange  22  comprises the already mentioned cooling fluid inlet  24  which extends in the radial direction at the side, starting from the generated surface of the rotatable flange  22 . Via the cooling fluid inlet  24 , cooling fluid flows to the inner part  28  and finds its way into its cavity  56 . From there, the inflowing cooling fluid, via a transfer opening  64 , passes into the cavity  42  of the center shell  20 . As soon as the cooling fluid passes via the at least one transfer opening  64  from the cavity  56  of the inner part  28  into the cavity  44  which is formed by the center shell  20 , this region of the metering valve  32  is cooled as a result of the wetting by the cooling fluid of the cooled surface  34  or of the dividing wall  40 . From the cavity  44 , which lies inside the center shell  20 , the cooling fluid, then having a higher temperature on account of its heating, flows via the at least one cooling fluid outlet  26  back again into the cooling fluid circuit of an internal combustion engine or into a separate cooling fluid circuit, for example. 
         [0030]    From the sectional view according to  FIG. 2  it is apparent that the forming of a sump in the lower region of an inner space  42  between the cooling surfaces  34  or of the dividing wall  40  is avoided by the fact that at the lower end of the inner space this leads into at least one drainage opening  30  which is impressed, or produced in another way, as a channel-like recess in an annularly formed collar  60 . Ideally, this at least one channel-like recess, which functions as a drainage opening  30 , has an inclination from the inside outward in the radial direction so that fluid can flow out of the inner space  42 . 
         [0031]    In the right-hand part of  FIG. 2 , a further drainage opening  30 , formed as a channel-like recess in the annularly formed collar  60  of the cup-shaped insert  50 , is not shown since it does not lie in the section plane according to  FIG. 2 . 
         [0032]    Also apparent from the view according to  FIG. 2  is that the lower tapering region of the metering valve  32 , which is in the direction of a valve tip  76 , is supported or centered in the cup-shaped insert  50  by means of a support ring  68 . The valve tip  76 , which is subjected to the highest thermal stress, extends through a first opening  72 , which is formed in the cup-shaped insert  50 , into a further, second opening  74  which is located on the bottom surface of the inner part  28 . The exhaust gas flow—not shown in FIG.  2 —in the exhaust gas tract of an internal combustion engine passes across the furthest outer-lying second opening  74  with regard to the metering module  10  so that the valve tip  76  is not directly subjected to the temperatures of the exhaust gas flow. The temperature of the exhaust gas flow lies typically within a temperature range in the order of magnitude of between 200° C. and 750° C., depending upon the operating temperature of the internal combustion engine. 
         [0033]    From the view according to  FIG. 2  it can be gathered that the cup-shaped insert  50  comprises an annularly formed collar  60  into which are let individual channel-like recesses which form the drainage openings  30 . It can also be gathered from  FIG. 2  that between the cup-shaped insert  50 —on the inside—and the inner wall of the inner part  28  a baffle plate can be arranged. 
         [0034]    On the left-hand side in  FIG. 2 , above the cooling fluid inlet  24 , a radially extending channel-like recess, which forms a drainage opening  30  and is arranged in the annularly formed collar  60 , is identified by item  30 . 
         [0035]    Finally, it can be gathered from  FIG. 2  that the rotatable flange  22  of the housing  12  which encloses the upper shell  18  and the center shell  20  has a clamping ring  48  with which the cooling body  18 ,  20 ,  22  of multi-piece design, which constitutes the housing  12 , is fastened on the exhaust gas tract—not shown here—of an internal combustion engine. 
         [0036]    On account of the fact that the cooling fluid first of all enters the rotatable flange  22  via the cooling fluid inlet  24 , a significant cooling effect can be achieved at the end of the metering valve  32  of the metering module  10  at which the highest operating temperatures occur during operation of said metering module  10 —this means in the region of the valve tip  76  of the metering valve  32 —without, however, neglecting cooling of the metering module  10  in the upper region, i.e. in the region of the electrical plug-in contact  46 . By means of the solution proposed according to the invention cooling of all the temperature-sensitive regions of the metering module  10  is possible. 
         [0037]      FIG. 3  shows a perspective plan view of an annularly formed collar which is constructed on the cup-shaped insert of the cooling body of multi-piece design. 
         [0038]    For reasons of improved presentability, in the perspective view according to  FIG. 3  the center shell  20  of the housing  12  and also the cooled surface  34  of the metering module  10  are not shown. For this reason, a hexagon  62 , which is formed on the metering valve  32 , can be seen in  FIG. 3 . The metering valve  32 , as shown in  FIG. 3 , is encompassed by an annularly formed collar  60  in which are formed individual channel-like recesses—with a 120° spacing (compare item  58 ), for example—which constitute drainage openings  30 . In the embodiment variant of the drainage openings  30  according to  FIG. 3 , these are formed in the annularly formed collar  60  with a 120° spacing  58 , but could also be constructed with a 90° spacing (compare item  66  according to the  FIG. 5 ) or with another spacing. The channel-like recesses, which constitute the drainage openings  30 , can also extend in the surface  60  of collar-like design of the cup-shaped insert  50  with an inclination from the inside outward in the radial direction, as is shown in the example of  FIG. 4 . 
         [0039]    Reverting to  FIG. 2 , which shows a sectional view of the metering module  10 , channel-like recesses  64 , which are arranged beneath the center shell  20 —with a 120° spacing  58  for example—extend in the surface  60  of collar-like design so that fluid can flow out from the center shell  20  from the inside outward in the radial direction, avoiding the forming of a sump. Therefore, it is ensured that fluid that may be present can flow out of the inner space  42 —formed by the separating ring  38 , the inner side of the cooled surface  34  and the outer side of the metering valve  32 —on account of gravitational effect in the downward direction into the drainage openings  30 —in the form of impressed channel-like recesses, for example—which are formed in the annularly formed collar  60  so that the occurrence of corrosion is effectively counteracted. 
         [0040]    From the perspective plan view according to  FIG. 3  it can be gathered that the surface  60  of collar-like design is located at the upper end of the cup-shaped insert  50  and in this embodiment variant encompasses the generated surface of the rotatable flange  22  in a flush manner. The cooling fluid inlet  24  is located in the generated surface of the rotatable flange  22 . Furthermore, parts of the upper shell  18  and of the reducing agent inlet  16  are to be seen, as well as the electrical plug-in contact  36  on the side of the upper shell  18  which lies opposite the cooling fluid outlet  26 . Also to be gathered from  FIG. 3  is the separating ring  38 , only partially shown in  FIG. 2 , which at the top delimits the inner space  42  between the metering valve  32  and the inner side of the cooled surface  34 . 
         [0041]    To be gathered from  FIG. 4  is an embodiment possibility of drainage openings which are formed as channel-like recesses. 
         [0042]    From the view according to  FIG. 4  it is apparent that drainage openings  30 , which are arranged with a 120° spacing  58 , extend in the upper planar surface of the annularly formed collar  60  of the cup-shaped insert  50 . These drainage openings are manufactured by impression or by a metal-cutting means, for example, into the planar surface of the annularly formed collar  60 . As can be gathered from the perspective view according to  FIG. 4 , in this advantageous embodiment variant the drainage openings  30 , formed as channel-like recesses, have an inclination from the inside outward. On account of the inclination which the drainage openings  30  have from the inside outward in the radial direction, it is ensured that fluid discharging from the inner space  42  drains off to the outside on account of gravitational force and the forming of a sump inside the metering module  10  is excluded. It is apparent from the view according to  FIG. 4  that with reference to  FIGS. 1 and 2  the rotatable flange  22  is arranged beneath the annularly formed collar  60 , from which flange the cooling fluid inlet  24 , which is partially shown in  FIG. 4 , extends radially at the side. 
         [0043]    It is apparent from  FIG. 4  that the geometry of the drainage openings  30 , formed as channel-like recesses, has a funnel-shaped appearance and continuously widens from the inside outward, as seen in the radial direction. The inclination angle at which the drainage openings  30 , formed as channel-like recesses, extend in the annularly formed collar  60  can be optimized with regard to production engineering. It is possible to impress, for example, the drainage openings  30 , formed as channel-like recesses, into the annularly formed collar  60  by means of a forming technique, or also to produce the drainage openings  30  by metal cutting. This depends upon the production engineering circumstances. 
         [0044]      FIG. 5  shows a further embodiment variant of the metering module which is proposed according to the invention. 
         [0045]    For reasons of improved representability, in the view according to  FIG. 5 , corresponding to the view according to  FIG. 3 , the center shell  20  is removed so that a better view of the planar surface of the annularly formed collar  60  can be achieved. 
         [0046]    It is apparent from  FIG. 5  that in this embodiment variant four drainage openings  30  extend in the annularly formed collar  60  with a 90° spacing  66 . The individual drainage openings  30  are also formed in this case as channel-like recesses which are impressed into the annularly formed collar  60 . As a variation to the view of the drainage openings  30  arranged with a 90° spacing  66 , these can also have an inclination which extends from the inside outward in the radial direction in order to facilitate the transporting away of a fluid. In  FIG. 5 , the 90° spacing  66 , in which the individual drainage openings are oriented relatively to each other in the annularly formed collar  60 , are identified by the designation  66 . To be seen beneath the annularly formed collar  60  is the generated surface of the rotatable flange  22  on which at least one cooling fluid inlet  24  is formed in the radial direction. To be seen beneath the rotatable flange  22  is the inner part  28  which is located at the lower end of the metering module  10 . 
         [0047]      FIG. 5  also shows that in this embodiment variant the reducing agent inlet  16  and the at least one cooling fluid inlet  24  lie one above the other on the rotatable flange  22  in an imaginary plane which extends in the vertical direction. In this case, other geometries are naturally also possible, this depending upon the respective installation conditions of the metering module  10 , whether it be mounted in the engine compartment of a vehicle or in the floor assembly of a vehicle in the proximity of the exhaust gas tract of an internal combustion engine. 
         [0048]    Designation  62  identifies a hexagon, which is constructed on the metering valve  32 , and item  46  identifies an electrical plug-in contact which projects from the metering valve  32  at the side. A plug-in connector cover  14  is located above the plug-in contact  46 . The reducing agent inlet  16 , which is formed at the side as an angled inlet, is molded on an upper shell  18 , as a rule being a component which is produced as a plastic injected part. 
         [0049]    To be gathered from  FIG. 6  is the passage of the cooling fluid flow through the individual regions of a metering module which is enclosed by a housing. As  FIG. 6  shows, the metering module, or the metering valve  32  which is arranged therein, is enclosed by a housing  12  so that all the temperature-sensitive regions of the metering module  10  can be effectively cooled. 
         [0050]    From the view according to  FIG. 6  it is apparent that a cooling fluid flow  70  flows through the at least one cooling fluid inlet  24 , which is formed on the rotatable flange  22  at the side, into the cavity  56  of the inner part  28 . The cavity  56  of the inner part  28  is delimited on one side by simply that inner part  28  and on the other side by the generated surface of the cup-shaped insert  50 , at the upper end of which is located the annularly formed collar  60  which has already been mentioned on a number of occasions. The cooling fluid, as a cooling fluid flow  70 , flows via the at least one cooling fluid inlet  24  into the cavity  56 . As a result, the effect can be achieved of the valve tip  76  of the metering valve  32 , which is subjected to high thermal loads, being able to be optimally cooled since the cooling fluid at the at least one cooling fluid inlet  24  enters the metering module  10  with the relatively coldest temperature. After the filling of the cavity  56 , the cooling fluid transfers via the at least one transfer opening  64  into the upper part of the metering module  10 . The cooling fluid flows into the cavity  44  so that the dividing wall  40  in the region of the electrical plug-in contact  46  is effectively cooled and on the other hand the cooled surface  34 , which partially delimits the inner space  42 , can also be cooled. From the cavity  44 , the heated cooling fluid now flows via the at least one cooling fluid outlet  26  back into the cooling fluid circuit which can be either the cooling fluid circuit of the internal combustion engine or a separate cooling fluid circuit. 
         [0051]    From the perspective sectional view according to  FIG. 6  it can be gathered that fluids are transported away from the inner space  42  between the outer surface of the metering valve  32  and the inner side of the cooled surface  34  in the transporting direction  78  via the drainage openings  30 , formed in the annularly formed collar  60 , according to the marked arrow. On account of the gravitational effect, the fluids, or the fluid, are, or is, transported from the inner space  42  downward in the vertical direction and above the support ring  68  make their way radially outward to the side via the drainage openings  30  which in a corresponding number are formed in the planar surface of the annularly formed collar  60 . Therefore, the forming of a sump inside the metering module  10  can be avoided, in particular the occurrence of corrosion can be effectively counteracted. 
         [0052]    In the lower region of the metering module  10 , it is to be seen that the valve tip  76 , of tapered design, of the metering valve  32  projects through a first opening  72  which is formed in the cup-shaped insert  50 . Furthermore, a second opening  74 , along which passes the exhaust gas flow—not shown in FIG.  6 —is formed in the inner part  28 . Therefore, the valve tip  76  is not directly subjected to the exhaust gas flow which can feature temperatures in the region of between 200° C. and 750° C., depending upon the operating temperature of the internal combustion engine. 
         [0053]    As  FIG. 6  shows, the valve tip  76  is now arranged on the inside and does not project directly into the exhaust gas flow of the internal combustion engine.