Withdrawal device, tank device

Abstract

Withdrawal device (4) for a tank device (1) of a vehicle, in particular a motor vehicle, wherein the withdrawal device (4), which can be arranged in a tank (2) of the tank device (1) providing liquid, has at least one withdrawal opening (6) through which the liquid can be withdrawn from the tank (2), and at least one heating device (7, 12), characterized in that the withdrawal device has a fluid line (8) which forms a closed circuit, wherein at least a first section (9) of the fluid line (8) is designed as a riser pipe with an upper and a lower end, and wherein the lower end is assigned to the heating device (7).

Description

[0001] The invention relates to a withdrawal device for a tank device of a vehicle, in particular a motor vehicle. The withdrawal device, which can be arranged in a tank of the tank device providing liquid, has at least one withdrawal opening through which the liquid can be withdrawn from the tank, and at least one heating device. Furthermore, the invention relates to a tank device with a corresponding withdrawal device. State of the art

[0002] Modern motor vehicles frequently use a liquid exhaust gas aftertreatment agent in the form of an aqueous urea solution, which is carried in a tank in the vehicle. The freezing point of the exhaust gas aftertreatment agent is typically around -11°C. In colder ambient conditions, the liquid in the tank freezes and must be thawed before it can be pumped out through the tank's outlet. For this purpose, a heating device is typically provided. This is usually a solid-state heater and uses, for example, two so-called PTCs pressed into an over-molded aluminum block. The heating output depends directly on the temperature-dependent resistance of the PTCs (PTC = "Positive Temperature Coefficient"). The heating device is located in the tank and is in direct contact with the liquid.As soon as a certain volume of the liquid has thawed, natural convection creates a cooling flow within the tank.

[0003] Heat losses at the contact points between the PTC, aluminum block, and overmolding lead to poor heat transfer from the heater to the liquid, resulting in high PTC temperatures. Since the resistance of PTCs increases sharply at temperatures as low as around 60°C, heating performance drops significantly. When the tank level is low or sloshing occurs, parts of the heater or heating elements are exposed and are no longer cooled, which can result in an additional sharp drop in heating performance. During thawing, the heat flow from the heater must be transported through the already thawed liquid to the melt front. The key effects are heat conduction and natural convection. These are weak, which is why the melt front cannot move far from the heater. A corresponding removal device is known, for example, from DE 10 2011 088 684 A1.

[0004] During thawing, the tank level decreases in the cavity created by heating. An air bubble forms between the liquid and the still-frozen ice. This air bubble insulates the ice above and beside it, preventing further thawing in that direction. During the cooling phase, the existing liquid refreezes, retaining the air bubble. This process repeats with the next heating phase, with the air bubble growing larger with each heating phase and the ice volume achieved by heating and natural convection shrinking.

[0005] DE 10 2005 059 581 A1 also discloses a device for heating a tank for a urea-water solution. DE 10 2013 201 591 A1 describes a reducing agent system with a thermosiphon. Disclosure of the invention

[0006] The removal device according to the invention with the features of claim 1 has the advantage that the tank volume of the tank is thawed in a simple manner and reliably over a large area, even at a distance from the removal opening, so that the ice volume is advantageously thawed even when the fill level drops. The removal device according to the invention is characterized in that a fluid line is provided which forms a closed circuit, wherein at least a first section of the fluid line is designed as a riser pipe with an upper and a lower end, and wherein the lower end is assigned to the heating device. The invention thus provides a fluid heating system in which a liquid and / or gaseous medium is conveyed through the fluid line.The fluid is pumped by heating a riser pipe at its lower end so that the fluid, which changes particularly in its density due to the heating, rises in the riser pipe and thereby sets the circuit in motion. For example, it is possible to additionally operate the fluid heating using an existing or known heating device. The riser pipe also ensures that heat is transferred to the frozen volume further above, in particular at a distance from the removal opening. Particularly during a first thawing process, this ensures that the largest possible cavity or a cavity that is open at the top is formed in the ice volume in order to keep the gas bubble in the area of ​​the removal opening as small as possible. This reliably avoids the disadvantages mentioned above in a simple manner.

[0007] According to an advantageous development of the invention, the fluid line is designed to be deformable, in particular elastically deformable, at least in sections. The deformable design of the fluid line enables easy insertion of the fluid line into the tank, for example, through an opening in the bottom of the tank. In particular, this makes it possible to arrange the fluid line in an area that projects beyond the surface of the tank opening by folding or deforming the fluid line before insertion into the tank in order to pass through the opening. The fluid line then unfolds again into the desired orientation / position within the tank, for example due to its inherent elasticity and / or due to the fluid pressure generated in the fluid line.Preferably, the riser pipe is rigid or non-deformable to ensure its position and orientation within the tank at all times, even when ice pressure acts on the riser pipe. Particularly preferably, the riser pipe is oriented such that it projects vertically upwards, with the tank of the tank device in this case preferably having its opening for the withdrawal device in the tank bottom.

[0008] According to an advantageous development of the invention, a second section of the fluid line adjoining the upper end of the riser pipe is designed, at least in part, as a sink pipe. The sink pipe is characterized in that it guides the fluid conveyed upwards through the riser pipe back down, wherein the sink pipe is preferably led away from the riser pipe at an angle such that the liquid is not guided vertically downwards again, but is in particular guided laterally outwards or in the direction of a lateral tank wall of the tank, i.e. away from the heating device, so that the heat of the conveyed fluid also reaches external areas of the tank and leads to thawing of frozen liquid there. This ensures that the tank is heated or thawed over a large area, particularly during a repeated or longer thawing phase.At the same time, it is ensured that the fluid in the riser pipe is not heated by the heating device, thus avoiding counterflow in the sink pipe.

[0009] Preferably, the sink pipe ends at the level of the lower end of the riser pipe. This returns the fluid to the initial level, so that it also thaws any frozen fluid over a wide area near the initial level, especially near the bottom of the tank.

[0010] Preferably, a third section of the fluid line extends from the sink pipe in a plane, in particular parallel to the tank bottom, over a large area, and leads back to the lower end of the riser pipe. In the third section, the fluid line is designed in particular such that it fan-outs in the plane or runs in a ring-shaped, circular, serpentine, wave-shaped, or flower-shaped manner. This allows many areas of the tank to be reached, and a correspondingly large volume to be thawed.

[0011] According to an advantageous development of the invention, the heating device is arranged outside the fluid line. In this case, for example, the lower end of the riser pipe—as already mentioned—is assigned to the existing heating device, whereby the heat emanating from it heats the lower end of the riser pipe and thus the fluid therein with the previously described effect.

[0012] Alternatively or additionally, the heating device is arranged within the fluid line to directly heat the fluid in the fluid line. For this purpose, the heating device is preferably designed as a sheathed-element glow plug and arranged in the fluid line. Particularly preferably, the sheathed-element glow plug is arranged at the point at the lower end of the riser tube where the third section of the fluid line opens into the riser tube, in order to ensure particularly efficient energy yield.

[0013] The fluid line preferably has an air catcher at its highest point, i.e., close to the upper end of the riser pipe. The air catcher is characterized by providing a hollow space into which air conveyed through the fluid line can escape. For this purpose, the air catcher is provided, for example, as a cup-shaped branch at the upper end of the riser pipe. Particularly preferably, the air catcher is provided in a portion of the fluid line between the upper end of the riser pipe and the sink pipe, which portion runs essentially horizontally.

[0014] Furthermore, it is preferably provided that the heating device is assigned to the extraction opening and / or at least one further heating device is assigned to the extraction opening. Depending on whether the heating device is arranged outside or inside the fluid line, a further heating device is preferably assigned to the extraction opening in order to quickly and directly thaw the area around the extraction opening, so that liquid exhaust gas aftertreatment agent or thawed fluid is available in the shortest possible time.

[0015] The tank device according to the invention with the features of claim 10 is characterized by the removal device according to the invention. The tank of the tank device preferably has an opening in its base into which the removal device is or can be inserted in a sealing manner.

[0016] The invention will be explained in more detail below with reference to the drawings. Fig. 1 an advantageous tank device with a removal device in a sectional view, Fig. 2 a top view of the removal device and Fig. 3 a perspective view of the removal device.

[0017] Fig. 1 shows a simplified sectional view of a tank device 1 comprising a tank 2 for providing a liquid exhaust gas aftertreatment agent and a withdrawal device 4 arranged in an opening 3 in the bottom of the tank. The withdrawal device 4 is arranged on the tank 2 so as to tightly seal the opening 3. The withdrawal device 4 has a conveying device 5 associated with a withdrawal opening 6 through which the liquid in the tank 2 can be withdrawn by means of the conveying device 5.

[0018] The removal device 5 further comprises a heating device 7, which in the present case forms a fluid heating device. For this purpose, the removal device 4 comprises a fluid line 8, which forms a closed circuit, which will be described below with reference to Fig. 1 to 3 will be explained in more detail.

[0019] Fig. 2 shows a top view of the removal device 4, while Fig. 3 shows the removal device 4 in a perspective view.

[0020] The fluid line 8 has a first section 9, which is designed as a riser pipe. For this purpose, the section 9 is essentially rigid and oriented in a straight line, with the first section 9 pointing vertically upwards or being oriented vertically. The lower end of the riser pipe or section 9 is assigned to the heating device 7, so that a fluid located in the fluid line 8 can be heated or warmed in this area. A second section 10 adjoins the upper end of the section 9. In the section 10, starting from the upper end of the riser pipe, the fluid line initially runs horizontally or horizontally away from the riser pipe, and then leads downwards towards the bottom of the tank 2 and further away from the section 9. The downward-leading part of the section 10 forms a sink pipe.In the present embodiment, the sink pipe is oriented at an angle of approximately 45° relative to the riser pipe. At its end, the sink pipe transitions into a third section of the fluid line, which is best illustrated in . Fig. 2. In the third section 11, the fluid line 8 is routed over a large area just above the bottom of the tank 2. In the present case, the fluid line 8 in the section 11 is routed through the interior of the tank 2 in an approximately flower-shaped manner, or according to the contour of a flower. The third section 11 ends at the lower end of the first section 9 or the riser pipe, and flows into it there.

[0021] The fluid is preferably a liquid with low viscosity, a strong temperature dependence of density, and a low melting point, especially <40°C. For this purpose, a water-glycol mixture in a mixing ratio of 40:60 can be used, for example. The fluid line 8 itself should be designed for temperatures of at least -50°C to 120°C.

[0022] By means of the heating device 7, the fluid in the fluid line 8 is heated at its lowest point, at the lower end of section 9. The heating of the fluid leads to a decrease in density, whereby the fluid rises vertically in section 9 or in the riser pipe, thereby heating and possibly thawing the liquid surrounding the riser pipe. The fluid is heated to such an extent that the differential pressure of the fluid in the fluid line 8, due to the density difference, is greater than the pressure loss in the fluid line 8, which can arise due to friction and curvatures in the fluid line 8. The diameter of the riser pipe is preferably selected to be as small as possible or relatively small in order to achieve high flow velocities and to prevent backflow. The remaining sections 10 and 11 of the fluid line 8 are preferably designed with a larger diameter in order to achieve lower friction losses.

[0023] The fluid that has risen through the riser pipe then enters section 10 and is guided towards the bottom of tank 2, as indicated by arrows. The fact that the sink pipe is arranged at a distance from the riser pipe prevents the fluid in the sink pipe from also being heated, which could lead to a counterflow. Preferably, both the riser pipe and the horizontally extending part of the fluid line 8 are essentially rigid. The third section 11 is preferably flexible to allow the fluid line 8 to be inserted in a deformed manner through the opening 3 into the tank 2.

[0024] The cooling fluid sinks back down the sink pipe to its original level and, due to the pressure differences, is pumped through section 11 until it returns to the heating device 7. This creates a closed circuit. The advantageous routing of the fluid line 8 ensures that the fluid in the tank 2 is heated, or warmed, over a large area and thawed.

[0025] The heating device 7 can be arranged outside the fluid line 8 or inside the fluid line 8. In the present embodiment, the heating device 7 is arranged in the fluid line 8 as a glow plug at the junction of section 11 and section 9, whereby the fluid in the fluid line 8 is directly heated. As shown in Fig.As shown in Figure 1, the riser pipe is extended downwards so that it extends outward through the extraction device. From there, the glow plug, for example, can be inserted to the desired location and the fluid line 8 can be sealed to the outside.

[0026] The fluid heater thus formed can either heat the tank 2 alone, in which case a section of the fluid line 8 is advantageously routed fluidically downstream of the heating device at the extraction opening 6 and a filter that may be associated with the extraction opening 6, or, to provide better additional long-term heating, it can be provided in addition to a conventional heating device 12 that has, for example, a PTC heating element as the heating element, as shown in the figures. The additional heating device 12 is expediently associated with the extraction opening 6 and any filter that may be provided. The available heating power is preferably distributed such that the critical components, i.e., the extraction opening 6 and any filter that may be present, thaw within a predetermined time and the remainder of the tank 2 is then sustainably heated.For example, it is intended that the additional heating device 12 is initially operated at 80 watts for the first twenty minutes after the tank device 1 is put into operation, while the heating device 7 of the fluid heater is only operated at 40 watts. As soon as the critical components have thawed, the tank removal device 4 is controlled such that the heating device 12 is only operated at 20 or 30 watts, while the fluid heater 7 is operated at 100 or 90 watts. This ensures that the removal opening 6 and any filter provided are thawed and remain thawed, while simultaneously heating the remaining liquid in the tank 2.

[0027] Advantageously, an air catcher 13 is additionally formed on the horizontal part of section 10. This is formed by a cup-shaped projection that points upwards from the fluid line 8 and, in the present embodiment, is inclined. The inclination is selected in this case such that the air catcher 13 points toward the fluid line 8 in the direction of fluid flow. If air has entered the system, the fluid flowing past the air catcher 13 can then release this air into the air catcher 13, or the air automatically rises into the air catcher 13, thereby improving the overall efficiency of the fluid heating system.

[0028] When the heating device 7 is switched on for the first time, before any flow has yet established in the fluid line 8, it may be desirable for the fluid to evaporate in the vicinity of the heating device 7, particularly in the fluid line 8. The resulting vapor bubbles rise in the riser pipe or in section 9 and induce the desired flow in the fluid line 8. The air trap 13 prevents the vapor bubbles from accumulating and forming a barrier to the flow of the fluid in the fluid line 8, thus interrupting it.

[0029] According to a further embodiment not shown here, at least one further fluid heater, as described above, is provided, the third section of which extends, for example, on a plane between the upper and lower ends of the riser pipe or section 9.

[0030] The advantageous tank device 1 prevents the formation of cavities in the ice, which could prevent further melting of frozen fluid. Furthermore, it ensures that melting fluid is provided, which can be fed to the discharge opening 6 once thawed fluid has already been removed from the area of ​​the discharge opening 6.

Claims

[1] Removal device (4) for a tank device (1) of a vehicle, in particular a motor vehicle, wherein the removal device (4) which can be arranged in a liquid-providing tank (2) of the tank device (1) has at least one removal opening (6) through which the liquid can be removed from the tank (2), and at least one heating device (7, 12), characterized by that the removal device has a fluid line (8) which forms a closed circuit, wherein at least a first section (9) of the fluid line (8) is designed as a riser pipe with an upper and a lower end, and wherein the lower end is assigned to the heating device (7). [2] Removal device according to claim 1, characterized by that the fluid line (8) is designed to be deformable, in particular elastically deformable, at least in sections. [3] Removal device according to one of the preceding claims, characterized bythat a second section (10) adjoining the upper end of the riser pipe is designed at least in part as a sink pipe. [4] Removal device according to claim 3, characterized by that the sink pipe ends at the level of the lower end of the riser pipe. [5] Removal device according to claim 3 or 4, characterized by that starting from the sink pipe, a third section (11) of the fluid line (8) extends in a plane, in particular parallel to a tank bottom of the tank (2), flatly, in particular over a large area, and leads back to the lower end of the riser pipe. [6] Removal device according to one of the preceding claims, characterized by that the heating device (7) is arranged outside the fluid line (8). [7] Removal device according to one of the preceding claims, characterized by that the heating device (7) is arranged within the fluid line (8), in particular designed as a glow plug. [8] Removal device according to one of the preceding claims, characterized by that the fluid line (8) has an air catcher (13) at its highest point. [9] Removal device according to one of the preceding claims, characterized by that the heating device is assigned to the removal opening (6) and / or at least one further heating device (12) is assigned to the removal opening (6). [10] Tank device (1) for a vehicle, in particular for an exhaust gas aftertreatment system of a motor vehicle, characterized by a removal device (4) according to one or more of the preceding claims.

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