KR20150112134A - Method for heating urea water solution - Google Patents

Abstract

The present invention includes a step of detecting urea water solution stored in a urea tank, a step of determining whether the temperature of the urea water solution is less than a predetermined reference temperature, and a step of heating the urea water solution according to whether the temperature of the urea water solution is less than the reference temperature.

Description

METHOD FOR HEATING UREA WATER SOLUTION [0001]

The present invention relates to a method for heating an aqueous urea solution, and more particularly to a method for heating an aqueous urea solution stored in a urea tank.

Vehicles equipped with a diesel engine inject a urea aqueous solution with a selective catalytic reduction (SCR) catalyst to reduce the NOx contained in the exhaust gas.

The urea aqueous solution is stored inside the urea tank mounted on the vehicle. When the outside air temperature is lower than the freezing point of the urea aqueous solution, the urea solution is not sprayed to the front end of the SCR catalyst. In this case, the vehicle has a problem that the engine output is limited or the NOx discharged from the engine can not be reduced.

In order to prevent freezing of the urea aqueous solution stored in the urea tank, a method of forming the urea tank as a plastic material or circulating the cooling water discharged from the engine to the urea tank has been proposed.

However, the method of forming the urea tank as a plastic material has a problem that when the urea tank is exposed to a low temperature for a long time, the urea aqueous solution is frozen.

In addition, the method of circulating the cooling water discharged from the engine to the urea tank requires circulating the cooling water fully heated by the engine to the urea tank, so that the urea aqueous solution can not be melted by the cooling water at the initial stage of engine startup, There is a problem that the installation structure for circulating the cooling water is complicated and the installation cost is increased.

The background art of the present invention is disclosed in Korean Patent Publication No. 10-2010-0007602 (2010.01.22).

It is an object of the present invention to provide an urea aqueous solution heating method for controlling the temperature of an aqueous urea solution stored in a urea tank.

Another object of the present invention is to provide an urea aqueous solution heating method for rapidly heating a low-temperature urea aqueous solution stored in a urea tank to a suitable temperature.

It is still another object of the present invention to provide an urea fuel cell which is capable of melting urea aqueous solution stored in a urea tank irrespective of whether an engine is heated at the beginning of the engine and preventing the urea aqueous solution from being supplied to the SCR catalyst, And a method for heating an aqueous solution.

It is still another object of the present invention to provide a method for heating an aqueous urea solution which prevents freezing of an aqueous urea solution and which can supply an aqueous urea solution with an SCR catalyst, thereby suppressing an increase in NOx emission.

It is still another object of the present invention to provide a method of heating a urea aqueous solution, which does not need to supply cooling water heated by an engine to a urea tank, so that its installation structure is simple and installation cost can be reduced.

According to an aspect of the present invention, there is provided a method of heating a urea aqueous solution, comprising: sensing a temperature of a urea aqueous solution stored in a urea tank; Determining whether the temperature of the aqueous urea solution is below a predetermined reference temperature; And heating the urea aqueous solution according to whether the temperature of the urea aqueous solution is lower than or equal to the reference temperature.

The present invention is characterized in that the urea aqueous solution is heated according to the comparison result by comparing the voltage of the generator for converting the output of the engine into electric energy to the reference voltage.

In the present invention, the step of heating the urea aqueous solution senses the level of the urea aqueous solution, and when the detected level of the aqueous urea solution is higher than a reference level, the aqueous urea solution is heated.

In the present invention, the step of heating the urea aqueous solution is characterized in that the urea aqueous solution is heated by an electric heater that generates heat from a power source applied from a generator that converts the output of the engine to electric energy.

In the present invention, the step of heating the urea aqueous solution heats the hot water stored in the hot water tank with a power supplied from the generator for converting the output of the engine into electric energy, and the heated hot water is supplied to the urea tank And the urea aqueous solution is heated.

In the present invention, the step of heating the urea aqueous solution is characterized in that the urea aqueous solution is heated through the hot water when the water level of the hot water is equal to or higher than a predetermined set water level and the temperature of the hot water is equal to or higher than a predetermined set temperature.

The present invention rapidly heats a low temperature urea aqueous solution stored in a urea tank to a suitable temperature.

INDUSTRIAL APPLICABILITY The present invention can prevent urea aqueous solution stored in the urea tank from being melted regardless of whether the engine is heated at the initial stage of engine startup, and to prevent the engine output of the vehicle from being lowered because the urea aqueous solution is not supplied to the SCR catalyst.

The present invention prevents the freezing of the urea aqueous solution and enables the supply of the aqueous urea solution with the SCR catalyst, thereby suppressing the increase in NOx emissions.

The present invention eliminates the need to supply the cooling water heated by the engine to the urea tank, so that the installation structure is simple and the installation cost can be reduced compared with the conventional case.

1 is a block diagram of an urea aqueous solution heating apparatus according to an embodiment of the present invention.
2 is a view illustrating an exemplary installation structure of an electric heating apparatus according to an embodiment of the present invention.
3 is a block diagram of a hot water heater according to an embodiment of the present invention.
4 is a view illustrating an exemplary installation structure of a hot water heating apparatus according to an embodiment of the present invention.
5 is a flowchart of a method for heating an aqueous urea solution using an electric heating apparatus according to an embodiment of the present invention.
6 is a flowchart illustrating a method of heating a urea aqueous solution using a hot water heating apparatus according to an embodiment of the present invention.

Hereinafter, a method of heating a urea aqueous solution according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. Further, terms to be described below are terms defined in consideration of the functions of the present invention, which may vary depending on the user, the intention or custom of the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

FIG. 1 is a block diagram of an urea aqueous solution heating apparatus according to an embodiment of the present invention. FIG. 2 is a view illustrating an installation structure of an electric heating apparatus according to an embodiment of the present invention. FIG. 4 is a view illustrating an exemplary installation structure of a hot water heating apparatus according to an embodiment of the present invention. Referring to FIG.

The apparatus for heating urea aqueous solution according to the embodiment of the present invention is characterized by a direct heating system in which an aqueous urea solution is directly heated through an electric heater 71 in accordance with the temperature and the water level of an aqueous urea solution and indirect heating Method is used to control the temperature of the urea aqueous solution.

1, an urea aqueous solution heating apparatus according to an embodiment of the present invention includes a urea aqueous solution temperature sensing unit 20, a urea aqueous solution level sensing unit 30, an engine ECU (Electronic Control Unit) 30, an engine 40, a generator 50, a voltage measuring unit 60, a heating device 70, an output unit 80, and a main control unit 90.

The urea aqueous solution temperature sensing unit 20 senses the temperature of the urea aqueous solution stored in the urea tank 10.

The urea tank 10 may store the urea aqueous solution therein and may be made of a synthetic resin having a low thermal conductivity to prevent the heat of the urea aqueous solution from being discharged to the outside. As described above, since the urea tank 10 is made of plastic, the urea aqueous solution can be inhibited from being frozen at a temperature below a certain point. Further, the urea tank 10 may be further provided with a heat insulating material so that the heat insulating effect is further improved. As such a heat insulating material, any one of polyurethane, polystyrene, and hollow silica gel may be employed, and any one or more of these may be combined.

The urea aqueous solution level sensing unit 30 senses the level of the urea aqueous solution stored in the urea tank 10. In the urea aqueous solution level sensing part 30, not only a method of using a floater that moves in the vertical direction according to the level of the urea aqueous solution but also an optical method of sensing the level of the urea aqueous solution based on the amount of light received by emitting light to the urea aqueous solution In addition, various methods of sensing the level of the urea aqueous solution may be employed.

The engine ECU 30 controls the operation of the engine 40 of the vehicle as a whole so that when a key signal for starting the vehicle is input from a key box (not shown) or the like by a key operation of an occupant, And operates the engine 40 in response.

The generator 50 converts the output of the engine 40 into electric energy, and in the case of a diesel vehicle, for example, it can output a voltage of 24 V or more.

The voltage measuring unit 60 measures the voltage output from the generator 50. [

The heating device 70 heats the aqueous urea solution using electric power applied from the generator 50. As the heating device 70, various methods for heating the urea aqueous solution may be employed.

In this embodiment, the direct heating method of directly heating the urea aqueous solution by the heating device 70 and the indirect heating method of heating the heated urea aqueous solution by the hot water are described as an example. As the direct heating method, an electric heater 71 that generates heat by the applied electric power may be employed, and as the indirect heating method, a hot water heating method of circulating the hot water into the urea tank 10 may be employed .

2, the electric heater 71 is installed inside the urea tank 10 and is fixed by the sender module 11. As shown in Fig. The electric heater 71 generates heat by the electric power supplied from the generator 50 to directly heat the urea aqueous solution. Since the electric heater 71 is instantaneously heated when power is supplied from the generator 50, the temperature of the urea aqueous solution can be raised to a suitable temperature within a short period of time at the initial start of the engine. As the electric heater 71, a sheath heater may be employed.

Referring to FIG. 2, the electric heater 71 may be installed in the urea tank 10 in various shapes and structures. That is, the electric heater 71 may be formed such that its end portion is bent in the horizontal direction as shown in FIG. 2 to increase the heat transfer area with the urea aqueous solution, or may be formed in a spring shape as well. As described above, the electric heater 71 can be formed in various structures to increase its heat transfer area.

Next, as the indirect heating method, a hot water heating device 72 may be employed.

The hot water heating device 72 heats the hot water and circulates hot hot water into the urea tank 10 to indirectly heat the urea aqueous solution.

3 and 4, the hot water heating device 72 includes a hot water level sensing unit 721, a hot water temperature sensing unit 722, a hot water circulation unit 723, and a hot water tank 729.

The hot water tank 729 stores hot water. The hot water tank 729 may be provided on one side of the urea tank 10 or integrally with the urea tank 10. FIG. 4 shows that the hot water tank 729 is installed on one side of the urea tank 10. 4, there is shown a mounting structure (not shown) for fixing the hot water tank 729 to one side of the urea tank 10, but a person skilled in the art will appreciate that various arrangements for fixing the hot water tank 729 to the urea tank 10 Structure can be adopted and applied.

The hot water level sensing unit 721 is installed in the hot water tank 729 and senses the level of the hot water stored in the hot water tank 729.

The hot water temperature sensing unit 722 is installed in the hot water tank 729 and senses the temperature of the hot water stored in the hot water tank 729.

The hot water circulation unit 723 heats hot water and circulates heated hot water in the urea tank 10 to heat the urea aqueous solution. The hot water circulating unit 723 includes a hot water heater 724 installed in the hot water tank 729 for heating the hot water, a hot water pump 728 for forcibly circulating hot water through the hot water circulating pipe 726, And a hot water circulation pipe 726 circulating hot water into the urea tank 725 and the urea tank 10 to transfer heat to the urea aqueous solution.

Here, the hot water circulation pipe 726 includes a heat supply pipe 728 and a connection pipe 727.

The heat supply pipe 728 is installed inside the urea tank 10 to transfer heat to the urea aqueous solution. The heat supply pipe 728 may be formed in various shapes, structures, and materials to effectively transmit the heat of the hot water to the urea aqueous solution.

The heat supply pipe 728 may be formed of a metal having a high heat transfer rate and may be formed in a shape suitable for increasing the heat transfer area. For example, as shown in FIG. 4, the heat supply pipe 728 may be formed of a metal material in a spring shape.

One of the connecting pipes 727 is connected to the hot water tank 729 and the other side thereof is connected to the heat supply pipe 728 to supply the hot water from the hot water tank 729 from the hot water tank 729 to the heat supply pipe 728 and supplies the hot water discharged from the heat supply pipe 728 to the hot water tank 729 again. The connection pipe 727 may be made of synthetic resin and may be manufactured in various shapes and lengths depending on the installation position of the hot water tank 729 and the quantity of water circulated.

That is, when the hot water heater 724 heats the hot water in the hot water circulating unit 723, the hot water pump 725 transfers the hot water to the heat supply pipe 728 through the connection pipe 727, ) Circulates heat through the urea aqueous solution. At this time, the aqueous urea solution is heated. The hot water discharged through the heat supply pipe 728 is supplied to the hot water tank 729 through the connection pipe 727 and is reheated by the hot water heater 724 and then supplied again to the heat supply pipe 728 < / RTI > This process is continuously repeated when the engine 40 is turned on and the temperature of the aqueous urea solution is below the reference temperature.

The output unit 80 outputs information related to the operation of the urea aqueous solution heating apparatus, for example, operation state information, error information, and the like according to an embodiment of the present invention. The operation state information may include whether the urea aqueous solution heating device is operating, the temperature and the water level of the aqueous urea solution, the temperature and the water level of the hot water, and the like. The error information may include the level of the urea aqueous solution, the level of the hot water, the voltage output from the generator 50, and the like. The output unit 80 includes a video output unit 81 and a sound output unit 82.

The video output unit 81 outputs operation state information and error information as a video or an image. The video output unit 81 may be separately provided in a cluster of a vehicle or the like.

The voice output unit 82 outputs the operation state information and the error information through a buzzer sound or a warning sound.

The main control unit 90 generally controls the urea aqueous solution heating apparatus according to an embodiment of the present invention. That is, when the passenger inputs a key signal for starting the engine 40 through the key box, the engine ECU 30 drives the engine 40. [ At this time, the generator 50 converts the output of the engine 40 into electric energy and supplies it to the heating device 70. At this time, the voltage measuring unit 60 measures the voltage of the generator 50, and the main controller 90 compares the voltage of the generator 50 with a predetermined reference voltage or higher, And determines whether to operate. In this case, when the voltage of the generator 50 is lower than the reference voltage, the main control unit 90 alerts the output voltage of the generator 50 via the output unit 80. The main controller 90 operates the heating device 70 with the power of the generator 50 when the voltage of the generator 50 is equal to or higher than the reference voltage so that the power of the battery (not shown) is not used. That is, since the heating device 70 does not use the power of the battery, the power consumption of the battery can be reduced.

Here, the reference voltage is a voltage that is a reference for determining whether the voltage of the generator 50 is sufficient to operate the heating device 70.

If the voltage of the generator 50 is higher than the reference voltage, the main control unit 90 senses the temperature of the urea aqueous solution through the urea aqueous solution temperature sensing unit 20. If the temperature of the urea aqueous solution is below the predetermined reference temperature, The heating device 70 is controlled to increase the temperature of the low-temperature urea aqueous solution. This will be described in detail with reference to FIGS. 5 and 6. FIG.

Here, the reference temperature is a temperature at which the urea aqueous solution can be judged to be in a state in which the urea aqueous solution is not injected due to reasons such as freezing of the urea aqueous solution, and the freezing point of the aqueous urea solution can be employed.

5 is a flowchart of a method for heating an aqueous urea solution using an electric heating apparatus according to an embodiment of the present invention.

Referring to FIG. 5, the main control unit 90 determines whether it is in the starting-on state (S100).

Here, when the passenger operates the key for starting the engine 40, the engine ECU 30 drives the engine 40 and inputs the start-on signal to the main control unit 90. [ Further, as the engine 40 is driven, the generator 50 converts the output of the engine 40 into electric energy.

On the other hand, if it is determined in step S100 that the power is on, the main control unit 90 measures the voltage of the generator 50 through the voltage measuring unit 60 (S102).

The main control unit 90 compares the voltage of the generator 50 measured by the voltage measuring unit 60 with a predetermined reference voltage to determine whether the voltage is equal to or higher than the reference voltage (S104).

If the voltage of the generator 50 is less than the reference voltage as a result of the determination in step S104, the main controller 90 alerts the generator 50 over the voltage of the generator 50 through the output unit 80 (S114).

On the other hand, if it is determined in step S104 that the voltage of the generator 50 is higher than the reference voltage, the main controller 90 senses the temperature of the urea aqueous solution through the urea aqueous solution temperature sensing unit 20 (S106).

The main control unit 90 compares the temperature of the urea aqueous solution with the reference temperature to determine whether the temperature of the urea aqueous solution is below a predetermined reference temperature (S108).

If it is determined in step S108 that the temperature of the urea aqueous solution exceeds the reference temperature, the main control unit 90 returns to step S100 and repeats the above process.

On the other hand, if it is determined in step S108 that the temperature of the urea aqueous solution is below the reference temperature, the main control unit 90 senses the level of the urea aqueous solution through the urea aqueous solution level sensing unit 30 (S110).

The main control unit 90 compares the level of the urea aqueous solution with the reference level to determine whether the level of the urea aqueous solution is equal to or higher than the reference level (S112).

If the water level of the urea aqueous solution is less than the reference water level as a result of the determination in step S112, the main control unit 90 warns the water level of the urea aqueous solution through the output unit 80 (S114).

On the other hand, if it is determined in step S112 that the level of the urea aqueous solution is equal to or higher than the reference level, the main control unit 90 turns on the electric heater 71 (S116).

As a result, heat is generated in the electric heater 71, and as a result, the heat of the electric heater 71 is transferred to the aqueous urea solution to increase the temperature of the aqueous urea solution, thereby maintaining the aqueous urea solution at a suitable temperature exceeding the reference temperature .

6 is a flowchart illustrating a method of heating a urea aqueous solution using a hot water heating apparatus according to an embodiment of the present invention.

Referring to FIG. 6, the main control unit 90 determines whether it is in a starting-on state (S200).

Here, when the passenger operates the key for starting the engine 40, the engine ECU 30 drives the engine 40 and inputs the start-on signal to the main control unit 90. [ Further, as the engine 40 is driven, the generator 50 converts the output of the engine 40 into electric energy.

On the other hand, if it is determined in step S200 that the power is on, the main control unit 90 measures the voltage of the generator 50 through the voltage measuring unit 60 (S202).

The main control unit 90 compares the voltage of the generator 50 measured by the voltage measuring unit 60 with a predetermined reference voltage to determine whether the voltage is equal to or higher than the reference voltage (S204).

If it is determined in step S204 that the voltage of the generator 50 is lower than the reference voltage, the main control unit 90 alerts the voltage of the generator 50 via the output unit 80 (S218).

On the other hand, if it is determined in step S204 that the voltage of the generator 50 is equal to or higher than the reference voltage, the main control unit 90 detects the level of the hot water stored in the hot water tank 729 through the hot water level sensing unit 72 (S206).

The main control unit 90 compares the level of the hot water stored in the hot water tank 729 with the set water level and determines whether the water level of the hot water stored in the hot water tank 729 is equal to or higher than the set water level (S208).

The set water level is set to a predetermined water level in the hot water tank 729 based on a sufficient amount of water to sufficiently control the temperature of the urea aqueous solution while preventing the hot water pump 725 from operating normally and overheating the hot water heater 724 And can be variously set as needed.

If the level of the hot water stored in the hot water tank 729 is less than the set water level as a result of the determination in step S208, the main control unit 90 warns the water level beyond the hot water level through the output unit 80 (S218).

On the other hand, if it is determined in step S208 that the level of the hot water stored in the hot water tank 729 is equal to or higher than the set water level, the main control unit 90 senses the temperature of the urea aqueous solution through the urea aqueous solution temperature sensing unit 20 (S210).

Next, the main control unit 90 compares the temperature of the urea aqueous solution with the reference temperature to determine whether the temperature of the urea aqueous solution is below a predetermined reference temperature (S212).

If it is determined in step S212 that the temperature of the urea aqueous solution exceeds the reference temperature, the main control unit 90 returns to step S200 and repeats the above process.

On the other hand, if it is determined in step S212 that the temperature of the urea aqueous solution is below the reference temperature, the main control unit 90 senses the level of the urea aqueous solution through the urea aqueous solution level sensing unit 30 (S214).

The main control unit 90 compares the level of the urea aqueous solution with the reference level to determine whether the level of the urea aqueous solution is equal to or higher than the reference level (S216).

If the water level of the urea aqueous solution is less than the reference water level as a result of the determination in step S216, the main control unit 90 alerts the water level of the urea aqueous solution through the output unit 80 (S218).

On the other hand, if it is determined in step S216 that the level of the urea aqueous solution is higher than the reference level, the main controller 90 senses the temperature of the hot water through the hot water temperature sensing unit 722 (S220).

The main control unit 90 compares the temperature of the hot water sensed by the hot water temperature sensing unit 722 with the preset temperature, and determines whether the temperature of the hot water is equal to or higher than the preset temperature (S222).

If the temperature of the hot water is lower than the set temperature as a result of the determination in step S222, the main control unit 90 drives the hot water heater 724 to heat the hot water (S224), drives the hot water pump 725, 724 to the inside of the urea tank 10 through the hot water circulation pipe 726 (S226).

On the other hand, if it is determined in step S222 that the temperature of the hot water is equal to or higher than the set temperature, the main control unit 90 drives only the hot water pump 725 without driving the hot water heater 724, The hot water is supplied and circulated into the urea tank 10 (S226). This process is repeated continuously to maintain the temperature of the aqueous urea solution above the reference temperature.

In this embodiment, the low-temperature urea aqueous solution stored in the urea tank 10 is quickly heated to a suitable temperature.

In this embodiment, the urea aqueous solution stored in the urea tank 10 is melted irrespective of whether or not the engine 40 is heated at the initial stage of the engine startup, and the urea aqueous solution is not supplied to the SCR catalyst, Can be prevented.

In addition, the present embodiment can prevent the urea aqueous solution from freezing, and can supply the urea aqueous solution with the SCR catalyst, thereby suppressing the increase in the NOx emission. The cooling water heated by the engine 40 is supplied to the urea tank 10 So that the installation structure is simple and the installation cost can be reduced compared with the conventional case.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, I will understand. Accordingly, the true scope of the present invention should be determined by the following claims.

10: urea tank 20: urea aqueous solution temperature sensing unit
30: urea aqueous solution level sensing unit 30: engine ECU
40: engine 50: generator
60: voltage measuring unit 70: heating device
71: electric heater 72: hot water heating device
721: a hot water level sensing unit 722; The hot water temperature sensing unit
723: Hot water circulation part 724: Hot water heater
725: hot water pump 726: hot water circulation pipe
727: connector 728: heat supply pipe
729: Hot water tank 80: Output section
81: video output section 82: audio output section
90:

Claims (6)

Sensing the temperature of the urea aqueous solution stored in the urea tank;
Determining whether the temperature of the aqueous urea solution is below a predetermined reference temperature; And
And heating the urea aqueous solution according to whether the temperature of the aqueous urea solution is lower than or equal to the reference temperature.
The method for heating urea aqueous solution according to claim 1, wherein the urea aqueous solution is heated by comparing the voltage of the generator for converting the output of the engine to electric energy to a reference voltage and comparing the result with the comparison result.
The method of claim 1, wherein heating the urea aqueous solution
Detecting the level of the urea aqueous solution, and heating the urea aqueous solution when the detected level of the aqueous urea solution is not less than a reference level.
The method of claim 1, wherein heating the urea aqueous solution
Wherein the urea aqueous solution is heated by an electric heater that generates heat from an electric power source applied from a generator that converts the output of the engine to electric energy.
The method of claim 1, wherein heating the urea aqueous solution
The hot water stored in the hot water tank is heated by a power source applied from a generator for converting the output of the engine into electric energy and the heated hot water is circulated in the urea tank through the hot water circulation pipe to heat the urea aqueous solution Wherein the urea aqueous solution is heated.
6. The method of claim 5, wherein heating the aqueous urea solution
Wherein the urea aqueous solution is heated through the hot water when the water level of the hot water is equal to or higher than a predetermined set water level and the temperature of the hot water is equal to or higher than a predetermined set temperature.

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