KR101592701B1 - Device and method for heating urea of SCR system - Google Patents

Abstract

The present invention relates to a urea heating apparatus for an SCR system, and more particularly, to an urea heating apparatus using an SCR To a urea heating apparatus for a system.
That is, according to the present invention, a heating block is mounted on a cap of a urea tank, and a thermoelectric element and a cooling block are laminated on the heating block in order, and the heating block is heated by the heat generation of the thermoelectric element upon cold starting under low- And it is an object of the present invention to provide a urea heating device of an SCR system capable of improving the low-temperature operation of the SCR system by dissolving the urea frozen in the urea or preventing freezing of the urea.

Description

Technical Field [0001] The present invention relates to a urea heating apparatus and a method of a SCR system,

The present invention relates to an apparatus and a method for urea heating in an SCR system, and more particularly, to an apparatus and a method for urea heating in a SCR system, in which a urea in a urea tank for an SCR system of a commercial vehicle is heated using a thermoelectric element, To an urea heating apparatus and method in an SCR system.

Considering the fact that the exhaust gas discharged from the diesel engine contains nitrogen oxide (hereinafter referred to as NOx) which causes serious air pollution, a catalytic reduction method for removing NOx is used.

To this end, a Diesel Particulate Filter (DOC) or a Diesel Particulate Filter (DOC), which is a kind of exhaust gas post-treatment device for physically collecting and burning PM (particulate matter) A selective catalytic reduction (SCR) catalyst is continuously installed to remove the catalyst effectively.

The SCR catalyst system is a system capable of effectively reducing NOx by injecting urea (Urea, Urea), which is a reducing agent, into SCR catalyst. As shown in FIG. 5, the urea in the urea tank 1 is supplied to the supply module 2 the urea dosing unit 3 is supplied with urea dosing module 3, which is a kind of injector mounted on the SCR catalyst inlet by the pumping of the supply module, and the urea dosing unit 3 injects urea into the SCR catalyst to reduce NOx.

That is, in the SCR catalyst system, the urea injected into the exhaust pipe is pyrolyzed by heat in the exhaust pipe or in contact with the SCR catalyst to be catalytically decomposed so that one molecule of the urea is converted into two-component ammonia, and the converted ammonia is converted into nitrogen oxide And SCR (Selective Catalyst Reduction) reaction of the reaction product, thereby discharging harmless nitrogen and water, which are the products of the reaction, to the outside.

Since the freezing point (-11 °) of the urea used in such an SCR system is not so low, the urea in the urea tank does not circulate smoothly to the dosing unit at low temperature icing (ICING) There is an urgent need to improve the sex.

As a conventional method for improving the low temperature operation performance of urea, a method of installing a resistance heater around a pump mounted on a urea tank or providing a resistance heater in a channel from a pump to an SCR catalyst to prevent freezing of urea has been applied .

Alternatively, as another conventional method, a cooling water inflow path is provided in the urea tank, and the urea in the urea tank is melted by heating the engine cooling water.

Alternatively, as another conventional method, a method of melting a urea frozen by adopting a hot-wire heater in a urea tank is used.

However, the above-described conventional urea low temperature operation improving method has the following problems.

First, temperature control of resistive type heater and hot-wire type heater uses battery power. Therefore, excessive heating prevention logic must be included in designing and cost problems, and heater breakdown due to overheating of heater or fire around exhaust system may intermittently occur There is a problem that occurs.

Second, there is an inconvenience that the heating pipe is made of Teflon tubing in order to eliminate the possibility of corrosion of the electric heating line, There is a problem that the heater breaks due to overheating of the electrode line and the tubing material melts.

Third, when a heater is mounted in a urea tank, the heater must be made of SUS material in consideration of corrosiveness, which causes a problem of cost increase.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a thermoelectric conversion device in which a heating block is mounted on a cap of a urea tank, a thermoelectric element and a cooling block are laminated on the heating block, A Urea heating device of a SCR system is provided which can improve the low-temperature operation of the SCR system by melting the urea in the urea tank by heating the heating block by the heating block, or by preventing ice phenomenon of the urea, There is a purpose.

According to an aspect of the present invention for achieving the above object, there is provided a brewing apparatus for a brewing machine, comprising: a brewing unit for brewing a brewing unit into a urea tank, A block; A thermoelectric element disposed on the heating block, wherein the heating element is disposed in contact with the heating block; A cooling block stacked on the heat absorbing portion of the thermoelectric element to cool the heat absorbing portion; The heating block is heated by the heat transferred from the heat absorbing portion of the thermoelectric element to the heat generating portion and the urea which has been freezing by the heating of the heating block is discharged to the urea supply line through the urea discharge passage. The urea heating device of the SCR system.

Preferably, a plurality of cooling fins are integrally mounted on the surface of the cooling block for rapid cooling of the cooling block.

More preferably, a urea circulation pipe is connected between the inside of the cooling block and the urea tank so that the urea passing through the urea circulation pipe is iced and the cooling block can be cooled.

The Urea circulation pipe is equipped with a pump for circulating the urea in the urea tank through the urea circulation pipe when starting off.

In order to achieve the above object, according to the present invention, there is provided a method of manufacturing a Urea tank, comprising the steps of: embedding a heating block in contact with a heating part of a thermoelectric element in a cap of a urea tank; and immersing the lower end of the heating block in a urea in a urea tank. Stacking a cooling block on the heat absorbing portion of the thermoelectric element; Measuring atmospheric temperature and urea temperature at engine start-up of the vehicle; Applying a current to the thermoelectric element if the atmospheric temperature and the urea temperature are below the lower limit reference value; Heating the heating block by the heat transferred from the heat absorbing portion of the thermoelectric element to the heat generating portion; Releasing the icy-decomposed urea by heating the heating block to the urea supply line through the urea discharge passage; And an urea heating method of the SCR system.

Further, the method of the present invention is characterized in that, when the engine is turned off, the urea in the urea tank circulates and fills the urea circulation pipe formed in the cooling block; Freezing the urea in the urea circulation pipe at low temperature to cool the cooling block; And further comprising:

Through the above-mentioned means for solving the problems, the present invention provides the following effects.

First, by preventing the icy phenomenon of urea in the urea tank by using the thermoelectric element, it is possible to prevent the excessive heating by the heater and improve the heating ability compared with the conventional method using the low current compared to the conventional heating heater Of course, the prevention of fire can be achieved, and in particular, the electric consumption can be minimized and the cost can be reduced.

Second, since a thermoelectric element is mounted on the cap portion of the urea tank, a cooling block is mounted on the thermoelectric element, and the lower heating block is mounted on the thermoelectric element, Δt of the thermoelectric element can be easily adjusted. Excessive heating can be prevented.

Third, it is possible to remove icing for urea (urea water) of SCR system and to raise urea temperature at low temperature starting condition, and to precisely control urine number injected to SCR by controlling temperature accurately can do.

Fourth, SCR operation can be smoothly performed even when the atmospheric conditions are low, and it is possible to actively cope with the exhaust emission regulation, and it is advantageous to improve the gas purification ability due to the exhaust emission in the cold state, that is, to reduce NO _X and PM. do.

Fifth, the temperature of the cooling block adhered to the heat absorption side of the thermoelectric element can be controlled by using urea in running or freezing state so that the temperature difference (? T) between the heating block and the cooling block adhering to the heat generating side of the thermoelectric element can be maintained at a constant level It can be cooled and maintained at a constant temperature.

1 is a schematic view showing a urea heating apparatus of an SCR system according to a first embodiment of the present invention,
2 is a schematic view showing a urea heating apparatus of an SCR system according to a second embodiment of the present invention,
3 is a schematic view showing a urea heating apparatus of an SCR system according to a third embodiment of the present invention,
FIG. 4 is a flowchart showing an operation flow of a urea heating apparatus of an SCR system according to the present invention,
5 is a schematic diagram showing a configuration of an SCR system;

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention is focused on melting a urea in a urea tank while heating a heating block by heat generation of a thermoelectric element at a cold start in a low temperature condition, or preventing urea icing phenomenon.

The thermoelectric elements are commonly referred to by various names such as thermoelectric modules, Peltier elements, Thermoelectrical Coolers (TEC), and Thermoelectrical Modules (TEM).

Such a thermoelectric element can be referred to as a small heat pump, that is, a device that absorbs heat from a low temperature heat source and generates heat to a high temperature heat source.

In view of the principle of the thermoelectric element, when DC voltage is applied to both ends of the thermoelectric element, the heat moves from the heat absorbing portion to the heat generating portion, and accordingly the temperature of the heat absorbing portion is lowered and the temperature of the heat generating portion is increased over time. The polarity of the endothermic portion and the cooling portion is changed, and the heat flow is reversed

At this time, when a current is supplied to the thermoelectric element, the maximum temperature difference DELTA T between the heat generating portion and the heat absorbing portion is theoretically 65 to 73 DEG C, and the heat transfer amount from the heat absorbing portion to the heat generating portion can be maximized.

To this end, the heat-generating portion must smoothly discharge heat from the heat-absorbing portion to the outside, and the heat-absorbing portion must be cooled to a proper temperature.

Accordingly, a heating block for heat dissipation is generally brought into contact with the heat generating portion of the thermoelectric element, and a cooling block for cooling is brought into contact with the heat absorbing portion.

Hereinafter, embodiments of the present invention in which the urea in the urea tank is heated at a low temperature by using the thermoelectric element having the above characteristics will be described.

First Embodiment

1 is a schematic view showing a urea heating apparatus of an SCR system according to a first embodiment of the present invention.

In Fig. 1, reference numeral 10 denotes a urea tank filled with urea, and 20 denotes a cap 20 which opens and closes the inlet of the urea tank.

The periphery of the cap 20 is openably and closably connected to the inlet of the urea tank 10. A heating block 32 for heating the urea is provided at the center of the cap 20, And the bottom portion of the heating block 32 extends toward the bottom so that the urea can reach the inside of the urea tank 10. [

At this time, the thermoelectric element 30 is mounted on the heating block 32 so that the heat generating portion 33 of the thermoelectric element 30 is in contact with the heating block 32 in a heat conductive manner.

A cooling block 34 is mounted on the thermoelectric element 30 so that the heat absorbing portion 31 of the thermoelectric element 30 is in contact with the cooling block 34.

More specifically, when a current is supplied to the thermoelectric element 30, the maximum temperature difference DELTA T between the heat generating portion 33 and the heat absorbing portion 31 is theoretically 65 to 73 DEG C, and the maximum temperature difference must be maintained before the heat absorbing portion 31 The heat generating portion 33 must discharge the heat from the heat absorbing portion 31 to the outside smoothly and the heat absorbing portion 31 is cooled to a proper temperature .

A heating block 32 serving as means for heating urea is brought into contact with the heat generating part 33 of the thermoelectric element 30 and the heat absorbing part 31 is cooled to a proper temperature The cooling block 34 is contacted.

According to the first embodiment of the present invention, when the vehicle is running, the outside air in a low temperature state, that is, the running wind touches the cooling block 34 to cool and maintain the cooling block 34 at an appropriate temperature.

In the heating block 32, a urea discharge passage 22 for discharging the urea in the urea tank, which has been frozen or frozen by the heating action of the heating block 32, into the urea supply line 24, do.

Preferably, the cap 20 is provided with a temperature sensor (not shown) for measuring the urea temperature in the urea tank 10 and sending it to the controller, a level sensor for measuring the urea filling level and transmitting it to the controller Is attached.

Hereinafter, an operation flow of the urea heating apparatus of the present invention will be described with reference to FIG.

First, when the ambient temperature is below the reference value (about -10 DEG C) and the urea (urea water) temperature in the urea tank 10 is below the lower limit reference value (about -10 DEG C) A current is applied to the thermoelectric element 30.

When DC voltage is applied to both ends of the thermoelectric element 30 in the controller in the normal direction, the thermoelectric element 30 moves to the heat generating part 33 which is in contact with the heating block 32 in the heat absorbing part 31 in contact with the cooling block 34, The heating block 32 in contact with the heating portion 33 of the thermoelectric element 30 is heated.

Therefore, by heating the heating block 32, the urea in the urea tank 10 is freezing or prevented from freezing.

When the temperature of the freezing or freezing urea reaches the upper and lower reference values, the controller performs the injection control of the urea dosing unit, so that the urea supply line 24 And then supplied to the urea dosing unit to be easily injected into the catalyst for NOx reduction.

At this time, depending on the outside temperature and the urea temperature, the increase and decrease in the heating capacity and the time can be operated by the map obtained through the experiment.

Second Embodiment

2 is a schematic view showing a urea heating apparatus of an SCR system according to a second embodiment of the present invention.

The configuration and operation flow according to the second embodiment of the present invention is the same as the first embodiment described above and the cooling block 34 is provided with the cooling pin 34 so that the cooling holding temperature for the cooling block 34 can be made more constant. (36) is formed.

That is, considering that it is necessary to cool the cooling block 34 in contact with the heat absorbing portion 31 more efficiently in order to maintain the maximum temperature difference range between the heat absorbing portion 31 and the heat generating portion 33 of the thermoelectric element 30 And the cooling fins 36 are formed in the cooling block 34. As shown in Fig.

To this end, a plurality of cooling fins 36 are provided on the surface of the cooling block 34 so as to maintain the cooling block 34 in a continuous low temperature state by improving the contact area between the low- Respectively.

Therefore, according to the second embodiment of the present invention, when the vehicle is running, the outside air in a low-temperature state, that is, the running wind touches the cooling block 36 integrated with the cooling block 34 as well as the cooling block 34, 34) can be cooled and maintained at an appropriate temperature.

Third Embodiment

FIG. 3 is a schematic view showing a urea heating apparatus of an SCR system according to a third embodiment of the present invention.

The configuration and operation flow according to the third embodiment of the present invention are the same as those of the first embodiment described above, and the cooling operation using the urea iced in the low temperature state so that the cooling retention temperature for the cooling block 34 can be more consistently made. The point is characterized.

The urea circulation pipe 38 is connected between the inside of the cooling block 34 and the urea tank 10 and the urea in the urea tank 10 is connected to the urea circulation pipe 38 38 to be filled by circulation.

Therefore, the pump 40 is operated at the pre-icing temperature of the urea during the start-off so that the urea in the urea tank 10 is filled into the urea-circulating pipe 38 extending in the staggered interior of the cooling block 34 do.

This makes it possible to cool the cooling block 34 in contact with the heat absorbing portion 31 more efficiently in order to maintain the maximum temperature difference range between the heat absorbing portion 31 and the heat generating portion 33 of the thermoelectric element 30 The urea is frozen and remains in the urea circulation pipe 38 after a certain period of time under the low temperature condition after the start-off.

As a result, the urea iced in the urea circulation pipe 38 causes the cooling block 34 to keep the cooling block 34 at a constant low temperature state, so that the maximum value between the heat absorbing portion 31 and the heat generating portion 33 of the thermoelectric element 30 The cooling block 34 in contact with the heat absorbing portion 31 can be more efficiently cooled to maintain the temperature difference range.

10: Urea tank
20: Cap
22: urea discharge passage
24: Urea supply line
30: thermoelectric element
32: heating block
34: Cooling block
36: cooling pin
38: urea circulation pipe
40: pump

Claims (6)

The upper end portion is embedded in the cap 20 of the urea tank 10 and the lower end portion thereof is immersed in the urea in the urea tank 10 so as to be able to be heated and the urea discharge passage 22 for discharging the urea in the urea tank 10, A heating block 32 having a through-hole formed therethrough;
A thermoelectric element (30) disposed on the heating block (32), wherein the heating element (33) is disposed in contact with the heating block (32);
A cooling block (34) laminated on the heat absorbing part (31) of the thermoelectric element (30) to cool the heat absorbing part (31);
So that the heating block 32 is heated by the heat transferred from the heat absorbing portion 31 of the thermoelectric element 30 to the heat generating portion 33 and the urea decompressed by the heating of the heating block 32 is heated by the urea To be discharged to the urea supply line 24 through the discharge passage 22,
A urea circulation pipe 38 is connected between the inside of the cooling block 34 and the urea tank 10 so that the urea passing through the urea circulation pipe 38 is freezed to cool the cooling block 34, Characterized in that the urea circulation pipe (38) is equipped with a pump (40) for circulating and filling the urea in the urea tank (10) into the urea circulation pipe (38) during startup off.
The method according to claim 1,
Characterized in that a plurality of cooling fins (36) are integrally mounted on the surface of the cooling block (34) for rapid cooling of the cooling block.
delete delete The heating block 32 in contact with the heating portion 33 of the thermoelectric element 30 is built in the cap 20 of the urea tank 10 and the lower end of the heating block 32 is heated in the urea in the urea tank 10 Possibly locking;
Laminating a cooling block (34) on the heat absorbing portion (31) of the thermoelectric element (30);
Measuring atmospheric temperature and urea temperature at engine start-up of the vehicle;
Applying a current to the thermoelectric element (30) if the atmospheric temperature and the urea temperature are below the lower limit reference value;
The heating block 32 is heated by the heat transferred from the heat absorbing portion 31 of the thermoelectric element 30 to the heat generating portion 33;
The urea decompressed by the heating of the heating block 32 is discharged to the urea supply line 24 through the urea discharge passage 22;
Lt; / RTI >
When the engine is turned off, the urea in the urea tank (10) is circulated and filled in the urea circulation pipe (38) formed in the cooling block (32);
Cooling the urea in the urea circulation pipe (38) to cool the cooling block (32) at low temperature conditions;
Further comprising the steps < RTI ID = 0.0 > of: < / RTI > delete

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