Abstract:
The invention relates to a reservoir tank, particularly for receiving a reducing agent for metering into the exhaust gas tract of an internal combustion engine. A spill basin is accommodated in the hollow space of the reservoir tank. At the base region, the spill basin is radially and axially guided into a recess of the reservoir tank base.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     application is a 35 USC 371 application of PCT/EP2008/051239 filed on Feb. 1, 2008. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a reservoir, particularly for receiving a reducing agent for metering into the exhaust gas tract of an internal combustion engine. 
     2. Description of the Prior Art 
     In vehicles with internal combustion engines, the pollutant NO x , among others, has to be reduced because of the increasingly stringent laws on exhaust gases that will come into effect in the next few years. One method that is used is SCR (selective catalytic reduction), in which the pollutant NO x  is reduced to N 2  and H 2 O with the aid of liquid reducing agent. The liquid reducing agent is stored in a tank and is pumped by the delivery module from the tank to the metering module via a line. Since the reducing agent freezes below a temperature of −11° C., the tank must be equipped with a heater. This heater is switched on as needed and thaws the frozen reducing agent. The heater and a sensor unit are accommodated in a pot. This pot, which simultaneously acts as a slosh pot, as positioned inside the tank. Since there is always an air cushion above the liquid, the tank on principle begins to freeze from the tank base upward. Because of the ice formation, the slosh pot is initially firmly held to the base of the tank. 
     Since the reducing agent on freezing expands by approximately 10% of its original volume, the slosh pot must be flexibly fixed to the tank cap. If because of the volumetric expansion the frozen reducing agent presses against the tank cap, the tank cap can yield upward because of the flexible fixation of the slosh pot. Thus damage to the slosh pot from ice pressure is precluded. The provision employed thus far requires that the slosh pot be locked in the lower region of the tank and coupled flexibly to the tank cap in the upper region. The locking in the lower region is very complicated to achieve, especially because the corresponding tanks are made by the blowing method, and thus at least one additional welding operation is also required. 
     From European Patent Disclosure EP 1 561 016, a method for posttreatment of the exhaust from an internal combustion engine is known in which a liquid reducing agent is used as an aid in treatment. If the temperature of the liquid reducing agent drops below a critical value, a partially chemical conversion of the reducing agent in a substance that lowers the freezing point of the reducing agent is brought about. 
     SUMMARY OF THE INVENTION 
     According to the invention, it is proposed that a slosh pot for damping motions of a fluid in a tank that in particular receives a reducing agent is guided in an indentation in the tank base radially and axially along a guide portion. To that end, the tank, preferably produced by means of the blowing method, is provided with a number of protuberances, which may for example be embodied in riblike fashion. The riblike protuberances embodied in particular in the tank base of the tank produced by blowing have a contact face, oriented toward the slosh pot that is guided in the indentation of the tank base, and in particular, a conical angle is formed between the protuberances, disposed on the circumference of an indentation in the tank base, and the corresponding recesses in the jacket face of the slosh pot. 
     By the embodiment of a conical angle between the contact faces of the protuberances, which for example are disposed in a star pattern around the indentation and are preferably riblike, and the recesses corresponding to them in the jacket face of the slosh pot in its guide region, radial and axial guidance of the slosh pot in guide portions embodied along the wall face of the indentation in the tank base is achieved. The indentation in the tank base simultaneously acts as a pump sump. Protuberances preferably embodied in riblike fashion are preferably embodied in the tank base, for example in a 120° arrangement to one another, in the tank blow mold, and the slosh pot with its guide region, which has a number of recesses corresponding to the number of protuberances embodied in the tank base, is inserted. 
     By means of the at least three protuberances, embodied in riblike fashion in the tank base around an indentation, and by means of the recesses corresponding to them in the jacket face on the slosh pot, the radial fixation of the slosh pot and tank relative to one another occurs from the formation of the conical angle, that is, a conicity between the indentation and the slosh pot. Moreover, a partial embodiment of the protuberances, embodied in particular in riblike fashion, causes the reducing agent stored in the tank to be capable of flowing into the sump region of the tank. 
     The slosh pot is preferably axially tensed against the tank cap by means of a spring element. Because of the fixation in the tank, that is, inside the guide region between the recesses, embodied in the jacket face of the slosh pot, and the preferably riblike protuberances corresponding to them in the tank base, the slosh pot is supported in shakeproof fashion by the spring element, which acts axially, in the hollow space of the tank that stores the reducing agent. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described in further detail below in conjunction with the drawings, in which: 
         FIG. 1  is a side view of the slosh pot, guided radially and axially in the tank inside a guide region on the tank base; 
         FIG. 2  is a top view on the tank base, with the slosh pot removed from the tank; and 
         FIG. 3  is the bottom face of the slosh pot as shown in  FIG. 1 , with recesses shown on the circumference. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG. 1 , the tank, which serves in particular to receive a reducing agent, is shown, in the tank base of which a guide region for guiding a slosh pot, prestressed by means of a spring, is embodied. 
       FIG. 1  shows a tank  10 , which is defined by a tank wall  12  and a tank base  14 . The tank  10  is preferably made by the blowing method in a blow mold and produced from plastic. 
     The tank  10  includes the tank base  14 , in which an indentation  16  is embodied that forms a sump  18 . A reducing agent, for conditioning the exhaust gas, that freezes below an outdoor temperature of −11° C. is preferably received in the tank  10 . 
     It can be seen from the view in  FIG. 1  that a slosh pot  20  is movably received in the tank  10 . The slosh pot  20  has a jacket face  22  as well as a top side  24  and a base  26 . 
     From the view in  FIG. 1 , it can be seen that the slosh pot  20  is guided with its guide region  28 , embodied in the lower region of the jacket face  22 , in the indentation  16  of the tank base  14 . To that end, in the tank base  14  around the indentation  16 , a number of preferably riblike protuberances  30  are embodied, disposed for instance in a circle. These protuberances  30  embodied in particular in riblike fashion may be embodied for example in an angular distribution of 120° (see the view in  FIG. 2 ) around the indentation  16  in the tank base  14 . The protuberance  30  shown in  FIG. 1  may for example be let into the blow mold in which the tank  10 , made by way of the blow molding process, is fabricated. From  FIG. 1 , it can be seen that the preferably riblike protuberance  30  has a contact face  32 . The contact face  32  extends across the guide region  28 , that is, the lower region of the jacket face  22  of the slosh pot  20  that is received axially movably in the indentation  16  in accordance with the course of motion  46 . 
     Especially good axial and radial guidance of the slosh pot  20  can be attained by means of a conicity  34  that is produced between the contact faces  32  and the recess, corresponding to it in the jacket face  22  in the guide region  28  of the slosh pot  20 . In particular, the conicity  34  between the contact faces  32  and the jacket face  22  of the slosh pot  20  can be characterized by a conical angle  36  that can be in the range between 5° and 15°. 
     A number of preferably riblike protuberances  30  is preferably made in the tank base  14 , around the indentation  16 , so that the slosh pot  20  is guided axially and radially in a guide region  28  at least three points in the indentation  16  of the tank base  14 . 
     As also seen from the view in  FIG. 1 , the top side  24  of the slosh pot  20  is acted upon by an elastic element  42 , embodied for example as a spring. The elastic element  42  is braced not only the top side  24  of the slosh pot  20  but also on an inside  40  of the tank cap  38  that closes the tank  10 . The action on the slosh pot  20  by the spring element  42  shown in  FIG. 1  causes tensing of the slosh pot  20  against the tank cap  38 . Because of this fixation in the hollow space  44  of the tank  10 , the slosh pot  20  is supported in shakeproof fashion in the hollow space  44  of the tank  10 . The rigidity of the support can be attained by varying the height of the guide region  28 , or in other words by varying the region in which the contact faces  32  of the preferably riblike protuberances  30  engage correspondingly embodied recesses in the jacket face  22  of the slosh pot  20 . The greater the axial length selected for this guide region  28 , the longer is the resultant guidance of the slosh pot  20  relative to the indentation  16  in the tank base  14 , and therefore the taller the slosh pot  20  can be. 
       FIG. 2  shows a view of the tank base of the tank shown in  FIG. 1 , without showing the slosh pot. 
     From  FIG. 2 , it can be seen that in an angular distribution  58 , for example of 120°, in the tank base  14  around the indentation  16 , three preferably riblike protuberances  30  are disposed. Instead of the three preferably riblike protuberances  30  shown in the tank base  14  around the indentation  16 , protuberances  30  may instead be provided in the tank base  14 . The 120° distribution  58 , as shown in  FIG. 2 , results from the preferably riblike protuberances. Because of the partial embodiment of the protuberances in the indentation  16  embodied in the tank base  14 , a residue of the reducing agent collects in the sump  18 , as shown in  FIG. 1 . 
     The bottom of the slosh pot can be seen in the view in  FIG. 3 . 
       FIG. 3  shows that along the circumference  56  of the base  26  of the slosh pot  20 , a number of recesses  48  corresponding to the number, shown in  FIG. 3 , of the preferably riblike protuberances  30  is disposed. In the view in  FIG. 3 , the recesses  48  are embodied with a curvature  50 , which is engaged by the various protrusions of the preferably riblike protuberances  30  shown in  FIG. 2 , which are embodied around the indentation  16  in the tank base of the tank  10 . Because of the difference in diameter between the curvature  50  and the various tips of the preferably riblike protuberances  30 , free spaces are created, by way of which the reducing agent stored in the hollow space  44  of the tank can flow to the sump  18 . Because of the differences in diameter between the curvatures  50  on the circumference  56  of the base  26  and in the guide region  28  of the jacket face  22  of the slosh pot  20  and the preferably riblike protuberances, an axial and radial guidance of the slosh pot  20  can be attained in the indentation  16  in the tank base  14 . Since the sump  18 , with regard to the geometry of the tank  10 , is embodied as shown in  FIG. 1  on the underside in the tank base  14 , freezing of the reducing agent in the sump  18  causes a vertical displacement of the slosh pot  22  counter to the action of the elastic element  42 , which is braced on the inside  40  of the tank cap  38 . From  FIG. 1  it can be seen that depending on the coverage, that is, the length of the guide region  28  between the contact faces  32  of the preferably riblike protuberances in the tank base  14 , corresponding recesses  48  (see the view in  FIG. 3 ) in the base  26  and in the jacket face  22  of the slosh pot  20 , a vertical displacement in accordance with the course of motion, represented by the double arrow  46 , of the slosh pot  20  relative to the guide region  28  can be compensated for. By the action on the top side  24  of the slosh pot  20  by the elastic element  42 , a shakeproof disposition of the slosh pot  20  in the tank  10  can be achieved, since the slosh pot is on the one hand guided axially and radially in the guide region  28  in the indentation  16  in the tank base  14  and on the other is prestressed by the elastic element  42  on its top side in the axial direction. 
     Between the cap  38  and the slosh pot  20 , there is an elastomer seal  61 . It seals at a region  62  in the vicinity of the cap  38 . The elastomer seal  61  is lengthened in the axial direction and is pulled up onto the upper edge of the slosh pot  20  and secured there in the context of a press fit in the upper region. The elastomer seal  61  lends the slosh pot  20  greater radial stability. Second, the elastomer seal  61  prevents the slosh pot  20  from emptying, for instance when the car is going around a sharp curve. The liquid splashes against the elastomer seal  61  and from there runs back into the slosh pot  20 . The elastomer seal  61  has an axial elasticity, which can absorb a volumetric expansion of the reducing agent at the phase transition from liquid to solid. 
     The foregoing relates to the preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.