DE102010029269A1 - Fluid tank for use in fluid heating system, for storing aqueous urea solution to reduce nitrogen oxide in exhaust gas of diesel engine of motor car, has heating element connected with cooling system such that fluid in tank volume is heated - Google Patents

Abstract

The fluid tank (2) has a cooling system exhausting heat generated from a motor during operation of the motor. A tank volume (4) retains fluid. A heating element (10) is connected with the cooling system such that the fluid in the tank volume is heated by the heat generated during operation of the motor. The heating element is arranged at a bottom (8a) of the fluid tank to an outer side of the tank volume. The heating element is arranged between a confinement (8) of the tank volume and a protection and/or insulation wall. An independent claim is also included for a fluid heating system comprising a fluid tank.

Description

State of the art

The invention relates to a heatable tank container and a system for heating such a tank container.

It is known that the exhaust gases of an internal combustion engine, in particular a diesel engine, a fluid such. As an aqueous urea solution, to be added to reduce existing pollutants in the exhaust gases, especially nitrogen oxides. Aqueous urea solution freezes at low ambient temperatures and the freezing point can only be lowered within a limited range by the addition of additives without adversely affecting the effectiveness of the urea solution in the exhaust aftertreatment.

One way to ensure the reliability of a system for reducing pollutants even at low ambient temperatures, is to store the fluid in a heatable tank container. By heating the tank container, freezing of the fluid can be prevented and / or frozen fluid can be thawed by heating the tank container.

Usually, a heating pot is mounted within the tank container in the vicinity of a suction, which contains an electric heater. By operating the electric heater, frozen fluid in the vicinity of the suction point is melted and / or freezing of the fluid in the area of the suction point is prevented.

Disclosure of the invention

It is an object of the invention to provide a heatable fluid tank for a motor vehicle which enables efficient and energy-efficient heating of fluid stored in the fluid tank.

This object is achieved by a fluid tank according to the invention according to independent claim 1. The dependent claims relate to advantageous embodiments of a fluid tank according to the invention and a system with such a fluid tank.

A fluid tank according to the invention is provided for a motor vehicle having an engine and a cooling system, the cooling system being designed to dissipate heat generated by the engine during operation. A fluid tank according to the invention has a tank volume for receiving and storing fluid and at least one heating element. The heating element is adapted to be connectable to the cooling system of the motor vehicle such that heat generated by the engine during operation is delivered via the cooling system and the heating element to fluid present in the tank volume and heats the fluid when the heating element is connected to the cooling system connected is.

Since the engine waste heat is available as a "waste product" in the operation of the engine "free", the power consumption of the motor vehicle by the heating of the fluid is not adversely affected. In particular, an additional power generation, as required for the operation of a conventional electric heating element and which has an increased fuel consumption of the engine result, can be dispensed with.

In one embodiment, the cooling system of the motor vehicle includes a fluid coolant and the heating element is connectable to the cooling system such that, during operation, at least a portion of the fluid coolant flows through the heating element. Cooling systems containing a fluid coolant, such. As cooling water, are widely used. By using fluid coolant of the cooling system for heating the fluid in the tank volume this is particularly easy and effectively heated.

In one embodiment, the heating element is disposed outside the tank volume on the tank. Characterized in that the heating element is arranged outside of the tank volume, a direct contact of the heating element is avoided with the fluid in the tank volume and damage, wear or aging of the heating element by a chemical reaction with the fluid, such as. B. corrosion, is reliably prevented.

In one embodiment, the heating element is in a lower region, e.g. B. arranged in the region of a bottom of the fluid tank. Because heated fluid has a lower density than cold fluid and therefore rises within the tank volume, a heating element disposed in a lower portion of the fluid tank enables uniform and complete heating of the fluid in the tank volume. Uneven local heating and thawing of the fluid, which could result in the formation of undesirable cavities, is thus reliably avoided.

In one embodiment, a heating element is disposed on at least one side wall of the fluid tank. A heater mounted on a sidewall allows additional heat transfer to upper layers of the fluid in the tank volume. The heating and / or thawing takes place simultaneously over the entire height of the tank volume and is accelerated.

In one embodiment, a protective and / or insulating wall which at least partially surrounds the tank volume and the heating element is provided, wherein the heating element is arranged between the tank volume and the protective and / or insulating wall. By an insulating wall disposed outside the heating element, an undesirable release of heat from the heating element to the environment is prevented and the efficiency of the heating process is increased. An outer protective wall prevents damage to the heating element and / or the limitation of the tank volume by external mechanical influences, such. Eg rockfall.

In one embodiment, the heating element is formed meander-shaped. A meander-shaped heating element allows a particularly uniform heating of the fluid and prevents the formation of undesirable cavities within frozen fluid particularly reliable.

In one embodiment, the fluid tank has at least two heating elements that are independently connectable to the cooling system. By a plurality of heating elements, which are independently connectable to the cooling system, the heat given off by the cooling system to the fluid heat can be adjusted particularly well as needed. Overheating of the fluid, which could result in the formation of vapor bubbles and / or undesirable chemical alteration of the fluid, can thus be avoided by reducing the number of heating elements connected to the cooling system and reducing heat transfer to the fluid becomes.

The invention also includes a system for heating a fluid stored in a tank container with a fluid tank according to the invention and at least one switchable valve, the system being configured such that a flow of fluid coolant through the at least one heating element is controllable by the switchable valve. The heating of the fluid in the tank volume by the heating element can be turned on and off particularly easily.

In one embodiment, the tank system comprises at least one temperature sensor, which is designed to measure the temperature of the fluid in the tank volume and / or the temperature of the coolant. By measuring the temperature of the fluid in the tank volume and / or the temperature of the coolant, the heating element can be controlled connected to or disconnected from the cooling system to set the desired or required heating power. In particular, overheating of the fluid in the tank volume, which could lead to the formation of vapor bubbles and / or an undesirable chemical change of the fluid, can be reliably avoided by measuring and monitoring the temperature of the fluid and / or the coolant.

The invention will be explained in more detail below with reference to the attached figures. Showing:

1 a schematic sectional view of an embodiment of a fluid tank according to the invention;

2 an enlarged section of the boundary of a fluid tank according to the invention, as shown in the 1 is shown;

3 a schematic sectional view of a second embodiment of a fluid tank according to the invention;

4 a schematic view of a fluid tank according to the invention from below;

5 a schematic representation of a system according to the invention for heating a fluid tank according to the invention.

1 shows a schematic sectional side view of an embodiment of a heatable fluid tank according to the invention 2 ,

The Indian 1 shown fluid tank 2 indicates a tank volume 4 for inclusion in the 1 not shown fluids, wherein the tank volume 4 from one to the tank volume 4 circumferential boundary 8th is included. The limit 8th is in its lower part as ground 8a formed the tank volume 4 limited to the bottom. In a middle area of the ground 8a is a recessed place, a so-called swamp 6 , formed in which, especially in a small amount of filling that still in the tank volume 4 collected fluid collects. As a result, even at a low level reliably fluid from the tank volume 4 be removed.

The swamp 6 opposite is on an upper side of the boundary 8th the tank volume 4 an opening formed with a flange. The opening is by a lid attached to the flange 3 locked. The lid 3 and the flange may, for. B. be designed as a screw or snap closure to securely close the opening and an uncontrolled sloshing of fluid from the tank volume 4 to prevent.

On the lid 3 is on the of the tank volume 4 facing away from a so-called conveyor module 5 arranged, which in particular contains a pump. The conveyor module 5 is designed to remove fluid from the tank volume 4 through a suction line 7 extending from the conveyor module 5 through the lid 3 and the tank volume 4 to the swamp 6 extends, from the tank volume 4 and via a fluid line 9 to one in the 1 injector, not shown, which is designed to inject the fluid into an exhaust system to deliver. In addition to a pump can in the delivery module 5 a fluid filter may be provided to pass through the suction line 7 from the tank volume 4 to remove removed fluid. Alternatively or additionally, a filter element at the inlet of the suction line 7 be provided to the fluid already before entering the suction line 7 to filter.

Immediately below the ground 8a are outside the tank volume 4 to the ground 8a adjacent heating elements 10 arranged in which in the 1 shown embodiment as cylindrical tubes 10 are formed. The heating elements 10 are so connected to a cooling system of a motor vehicle, that in the operation of the cooling system from the engine of the motor vehicle heated coolant through the tubes 10 flows and so fluid that is in the tank volume 4 is heated.

The heating elements 10 may be considered a plurality of separate heating elements 10 be formed, which are flowed through in parallel or in series by the coolant. Alternatively, the heating element 10 as a single, continuous tube 10 be formed, the z. B. meandering below the soil 8a the tank volume 4 is arranged. In this case is in the 1 a number of cuts through the heating element formed as a continuous tube 10 shown.

2 shows an enlarged section of the floor 8a a fluid tank according to the invention 2 , trained as tubes and in the ground 8a embedded heating elements 10 , In the ground 8a embedded heating elements 10 allow a particularly good transfer of heat from a coolant, through the heating elements 10 flows, fluid in the tank volume 4 , In the ground 8a of the tank 2 embedded heating elements 10 are particularly good and safe on the tank container 2 attached. Advantageously, the floor 8a of the tank 2 formed of a good heat conductive material.

The limit 8th of the tank 2 and especially the ground 8a can z. B. in the manufacture of the tank 2 around the heating elements 10 be sprayed so that the heating elements 10 directly into the ground 8a of the tank 2 are embedded. Alternatively, in the manufacture of the tank container 2 groove 11 for later inclusion of the heating elements 10 trained or after the production of the tank 2 , z. B. by milling, in the ground 8a be incorporated.

In one embodiment, the floor 8a at least in the area of the grooves 11 and / or the heating elements 10 formed with a certain elasticity, so that the heating elements 10 into the grooves 11 clamped and by elastic forces in the grooves 11 can be fixed. Alternatively or additionally, the heating elements 10 by an adhesive and / or clamps 13 which z. B. by an adhesive or fasteners 15 , such as As screws or rivets, at the limit 8th the tank volume 4 are attached and which the heating elements 10 at least partially surrounded, on the ground 8a of the tank 2 be fixed.

In an alternative, not shown in the figures embodiment retaining clips are on the ground 8a of the tank 2 provided to the heating elements 10 record and fix. In this case, the formation of grooves 11 in the limit 8th of the tank 2 be waived.

On the floor 8a of the tank 2 described manner, heating elements 10 also on side walls 8b the limit 8th of the tank 2 be attached.

3 shows a second embodiment of a tank container according to the invention 2 , The characteristics of the tank 2 that with those of the 1 match the first embodiment shown, have the same reference numerals and will not be described again.

In addition to those in the 1 features shown has a tank container 2 according to the second embodiment, an outer protective and / or insulating wall 12 on, around a lower area of the tank 2 is arranged so that the heating elements 10 between the protective and / or insulating wall 12 and the limit 8th of the tank 2 are arranged.

The protective and / or insulating wall 12 preferably comprises a particularly resistant material, which the lower portion of the tank 2 and in particular the heating elements 10 from external damage due to mechanical influences, such. As rockfall protects.

Alternatively or additionally, the protective and / or insulating wall contains 12 a thermally insulating and / or heat-reflecting material to absorb heat from the heating elements 10 on the of the tank volume 4 opposite side of the heating elements 10 is discharged to the environment and not for heating the fluid in the tank volume 4 is available to reduce or in the direction of the tank volume 4 to reflect. The of the heating elements 10 output heating power is used so effectively and the thawing or heating of the fluid in the tank volume 4 required heating power is reduced.

Alternatively or additionally, a thermally insulating material is in the room 14 that is between the limit 8th the tank volume 4 and the outer protective and / or insulating wall 12 is formed, arranged. The release of heat from the heating elements 10 to the environment can be reduced. The thermally insulating material in this case need not have high mechanical resistance, as it passes through the protective and / or insulating wall 12 is protected from external mechanical influences.

4 shows a schematic view of a tank container according to the invention 2 according to the in the 1 shown first embodiment from below.

In a middle area of the ground 8a tank container 2 is a swamp 6 trained in the in the 4 shown top view is circular.

A heating element designed as a meandering tube 10 is on the ground 8a of the tank 2 arranged. Due to the meandering design of the heating element 10 is the entire surface of the soil 8a of the tank 2 with a single heating element 10 good and evenly heated. With little design effort, especially with a single heating element 10 , a uniform heating of the fluid in the tank volume 4 reached. An uneven thawing of the fluid, which could result in the formation of unwanted cavities in the fluid, is thus reliably avoided.

The in the 4 shown meandering structure of the heating element 10 is only an example. There are also alternative structures possible, which cause the entire floor 8a of the tank 2 evenly through the heating element 10 is heated. In particular, the distances between the individual sections or windings of the heating element 10 Closer than in the 4 be shown formed to even more uniform heating of the tank volume 4 to effect. Alternatively, the distances between the sections or turns of the heating element 10 be made larger to that for the production of the heating element 10 reduce the necessary material costs.

5 shows a schematic representation of a system according to the invention for heating a fluid with a heatable tank container according to the invention 2 a motor 16 , and a cooler 18 , A coolant outlet of the engine 16 is via coolant lines L1 and L2 or L1 and L4 with the input of the cooler 18 or with one on the tank container 2 trained heating element 10 connected. The output of the radiator 18 is via a coolant line L3 with a coolant inlet of the engine 16 connected. The output of the heating element 10 is via coolant lines L5 and L6 or L5 and L7 with a coolant inlet of the engine 16 or with the input of the cooler 18 connected.

In the coolant lines L2, L4, L6 and L7 in each case a valve V1, V2, V3 and V4 is arranged. The valves V1, V2, V3 and V4 are designed to release or interrupt the flow of coolant through the respective coolant line L2, L4, L6 or L7 in a controlled manner. The valves V1, V2, V3 and V4 are over in the 5 not shown electrical lines with a control device 22 connected so that the valves V1, V2, V3 and V4 from the control device 22 can be targeted.

In a conventional operating mode (cooling mode) of the system in which the fluid in the tank container 2 is not heated, the valve V1 is open and the valves V2 and V4 are closed.

The coolant is generated by the operation of the engine 16 heats and flows from the engine 16 through the line L1, the opened valve V1 and the line L2 in the cooler 18 where it is cooled. The cooling can z. B. be supported by the wind of the moving motor vehicle or by a generated by a fan not shown airflow. From the radiator 18 the coolant flows through the line L3 back into the engine 16 where there is again heat of the engine 16 receives.

To the fluid in the tank container 2 to heat the valve V1 is closed and the valve V2 and at least one of the valves V3 and V4 are opened.

In this operating mode (heating mode) flows from the engine 16 heated coolant through the line L1, the valve V2 and the line L4 in the heating element 10 the heated tank container 2 ,

After the coolant through the heating element 10 the heated tank container 2 has flowed and heat to the fluid in the tank volume of the tank 2 is stored, the coolant flows either directly through the line L5, the valve V4 and the line L6 back into the engine depending on whether the valve V3 or the valve V4 is opened 16 where it is heated again, or it flows through the line L5, the valve V3 and the line L7 in the radiator 18 where it is further cooled before it returns to the engine through line L3 16 is guided to absorb heat from this and the engine 16 to cool.

Whether the coolant after passing through the heating element 10 of the tank 2 has flowed, in addition through the radiator 18 is guided, before going back to the engine 16 flows, in particular, depends on the temperature of the coolant after passing through the heating element 10 the heated tank container 2 has flowed, the operating condition, in particular the temperature of the engine 16 and the ambient temperature.

At the coolant lines 14 and 15 Temperature sensors T1 and T2 are provided which measure the temperature of the coolant and to the controller 22 hand off. Additional temperature sensors T3, T4 are on the engine 16 and in the environment provided to respectively the operating temperature of the engine 16 or to measure the ambient temperature. The control device 22 controls the valves V1-V4 taking into account the temperatures measured by the temperature sensors T1-T4 so that the engine 16 and the fluid in the tank volume 4 each occupy a temperature within a desired, predetermined temperature range in which the engine 16 can be operated optimally and a freezing of the fluid in the tank container is reliably prevented.

In the in the 5 shown system is also a pump 20 provided, which supports the circulation of the coolant through the system. Thereby, a good circulation of the coolant is achieved even with small temperature differences between the heated and the cooled coolant, which result in only a small thermal circulation.

The pump 20 is via control lines not shown with the control device 22 connected and is controlled by this in dependence on the measured by the temperature sensors T1-T4 temperatures and possibly other parameters so that the engine 16 and the fluid in the tank volume 4 each occupy a temperature within a desired, predetermined temperature range.

In one possible operating mode (mixed operating mode), the valves V1-V4 are each partially open, so that the cooling system is operated in a mixed operation, in which the coolant by heating both the heated tank container 2 as well as by conventional cooling by the radiator 18 is cooled. Such a mixed operation allows a particularly effective operation of a cooling and heating system according to the invention.

Claims (10)

Fluid tank ( 2 ) for a motor vehicle with a motor ( 16 ) and a cooling system adapted to move from the engine ( 16 ) heat generated by the engine during operation ( 16 ), wherein the fluid tank ( 2 ) at least one tank volume ( 4 ) for receiving a fluid and at least one heating element ( 10 ), which is connectable to the cooling system in such a way that fluid in the tank volume ( 4 ) by the engine ( 16 ) heat generated in operation is heatable. Fluid tank ( 2 ) according to claim 1, wherein the heating element ( 10 ) is connectable with a cooling system, which comprises a fluid coolant, that in operation at least a portion of the coolant through the heating element ( 10 ) flows. Fluid tank ( 2 ) according to claim 1 or 2, wherein at least one heating element ( 10 ) outside the tank volume ( 4 ) on the fluid tank ( 2 ) is arranged. Fluid tank ( 2 ) according to one of the preceding claims, wherein at least one heating element ( 10 ) on a floor ( 8a ) of the fluid tank ( 2 ) is arranged. Fluid tank ( 2 ) according to one of the preceding claims, wherein at least one heating element ( 10 ) on at least one side wall ( 8b ) of the fluid tank ( 2 ) is arranged. Fluid tank ( 2 ) according to one of the preceding claims, wherein at least one heating element ( 10 ) between a boundary ( 8th ) of the tank volume ( 4 ) and a protective and / or insulating wall ( 12 ) is arranged. Fluid tank ( 2 ) according to one of the preceding claims, wherein at least one heating element ( 10 ) is meander-shaped. Fluid tank ( 2 ) according to one of the preceding claims with at least two heating elements ( 10 ), which are independently connectable to the cooling system. System for heating a fluid with a fluid tank ( 2 ) according to one of claims 2 to 8 and at least one switchable valve (V1, V2, V3, V4), wherein the system is designed such that a flow of the coolant through the at least one heating element ( 10 ) is controllable by the switchable valve (V1, V2, V3, V4). System according to claim 9, comprising at least one temperature sensor (T1, T2, T3, T4) for measuring the temperature of the coolant, the Temperature of the engine ( 16 ) and / or the ambient temperature is formed.

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