KR20120036004A - Exhaust gas reducing device for vehicles with burner to improve purification performance - Google Patents

Abstract

PURPOSE: An emission reduction system of a car for improving emission reduction performance using a burner is provided to increase the temperature of exhaust gas when necessary and to operate a burner when the regeneration of a DPF is required. CONSTITUTION: An emission reduction system of a car for improving emission reduction performance using a burner comprises a burner(300), an oxidation catalyst(400), a DPF(500), an SCR(Selective Catalytic Reduction)(710), and an electronic control module(900). The burner increases the temperature of exhaust gas by burning fuel. The oxidation catalyst oxidizes unburned hydrocarbon and carbon monoxide generated from an engine(100). The SCR reduces nitrogen oxide. The electronic control module controls the operation of the burner using values measured from sensors(810,820,830,840,850).

Description

Exhaust Gas Reducing Device for Vehicles with Burner to Improve Purification Performance}

The present invention relates to a vehicle emission reduction device.

Recently, many countries around the world, including Korea, are strengthening regulations in consideration of the harmful effects of soot, nitrogen oxides, unburned hydrocarbons, and carbon monoxide emitted from automobiles, and emission reduction technologies for regulatory response are continuously being developed. Automotive internal combustion engines typically operate using gasoline fuel or diesel fuel. Nitrogen oxides (NOx) and particulate matter (PM) contained in large amounts in the exhaust gas of diesel vehicles are responsible for 40% of the total air pollution. It is recognized as a major cause of air pollution, and environmental regulations are strictly applied in the production of diesel vehicles. However, with the advent of high oil prices, diesel cars, which are more efficient than conventional gasoline cars, have been spotlighted. Accordingly, in order to reduce emissions of air pollutants generated in proportion to the production of diesel cars, advanced engines have been developed. Increasingly, regulations on emission pollutants are being tightened.

In addition, in recent years, gasoline cars, like diesel cars, directly inject fuel into a combustion chamber to burn fuel and burn them in a lean condition with a lot of air, so that the existing three-way catalytic converter cannot be used. Substance will be discharged additionally.

As a countermeasure to satisfy the emission regulations of internal combustion engines, pretreatment technologies aimed at reducing the generation of pollutants such as fuel improvement, combustion methods, and engine improvements, and exhaust gas outlets It is divided into post-treatment technology to purify the emitted gas generated by mounting. Although steady research and development is being conducted in each field, post-treatment technology is currently considered to be more advantageous for commercialization, and thus, more research and development is being conducted on post-treatment technology. Such post-treatment techniques include (1) an oxidation catalyst for purifying unburned hydrocarbons (HC) and carbon monoxide (CO) in the exhaust gas, and (2) a filter for removing particulate matter that filters particulate matter (PM) through a filter ( Diesel Particulate Filter (hereinafter referred to as 'DPF'), and (3) DeNOx catalyst system for decomposing or reducing nitrogen oxides (NOx) in a reducing atmosphere. For example, hybrid post-processing devices such as DPF systems with catalytic filters are widely used.

Among the conventional soot filter technologies, there is a natural regeneration method in which soot is collected in a catalyst-coated filter and the collected soot is directly oxidized soot using a catalytic reaction. However, this technology has a disadvantage in that it is difficult to obtain a natural regeneration effect by the catalyst when it is applied to a vehicle with a heavy traffic and a low temperature of exhaust gas having a lot of low-speed driving sections. In addition, in order to maximize the natural regeneration effect by the catalyst, there is a large amount of precious metal catalyst loading, and the recent rise in the precious metal price is another disadvantage of the natural regeneration type soot filter.

In order to overcome such disadvantages, a technique of increasing the temperature of the exhaust gas and regenerating the soot filtration filter by additionally injecting fuel at the end of the combustion stroke of the engine has been developed and applied to automobiles. There were disadvantages such as difficulty in controlling the engine.

In addition, nitrogen oxides, carbon monoxide, unburned hydrocarbons are usually reduced by using a catalytic reaction, but as shown in FIG. However, when the start-up or low-speed urban operation, the exhaust gas temperature is low, there is a disadvantage in reducing these harmful emissions when using only the catalyst.

Accordingly, the present invention has been made to solve the problems of the prior art as described above, an object of the present invention is to provide a burner in the exhaust gas reduction device consisting of an oxidation catalyst, a soot filtration filter, a selective reduction catalyst for reducing nitrogen oxides. If the exhaust gas temperature discharged from the engine is lower than the catalytic reaction temperature, the burner is operated to increase the exhaust gas temperature to maximize the emission gas reduction efficiency of the catalyst. The present invention provides a vehicle exhaust gas reducing device that solves the conventional problem by regenerating the filter.

The automobile exhaust gas reducing device of the present invention for achieving the above object, in the vehicle exhaust gas reducing device installed in the exhaust pipe 200 of the engine 100, by burning the fuel supplied from the vehicle fuel tank exhaust gas Burner 300 to increase the temperature of the; An oxidation catalyst 400 installed at the rear end of the burner 300 to oxidize unburned hydrocarbon and carbon monoxide generated from the engine 100 or the burner 300; A soot filtration filter 500 positioned at a rear end of the oxidation catalyst 400 to collect particulate soot in the exhaust gas; Located at the rear of the burner 300, a urea supply device for supplying urea which is a reducing agent for reducing nitrogen oxide in the exhaust gas to nitrogen and water; A selective reduction catalyst 710 positioned at a rear end of the urea supply device 700 to reduce nitrogen oxides; An exhaust gas pressure sensor 830 installed in front of the soot filtration filter 500 to monitor an amount of soot collected in the soot filtration filter 500; An exhaust gas temperature sensor 840 positioned at a rear end of the oxidation catalyst 400 to monitor an exhaust gas temperature flowing into the soot filtration filter 500; A nitrogen oxide concentration sensor 850 positioned at a rear end of the selective reduction catalyst 710 to measure a concentration of nitrogen oxides in the exhaust gas; The burner using the values measured by the sensors provided in the vehicle exhaust gas reducing device including the exhaust gas pressure sensor 840, the exhaust gas temperature sensor 850, the nitrogen oxide concentration sensor 860. An electronic control module 900 for controlling the operation of 300; And a control unit.

At this time, the burner 300 is the soot filtration filter 500 is operated when regeneration is required to increase the temperature of the exhaust gas to 500 ℃ to 600 ℃, or the oxidation catalyst 400 or the selective reduction catalyst ( When the exhaust gas temperature is 200 ° C. to 250 ° C. or less so that the purification at 710 is performed efficiently, the temperature of the exhaust gas is increased.

In addition, the burner 300 uses the value measured by the intake air flow rate sensor 810 or the engine speed detection sensor 820 installed in the engine 100 to reach the target temperature of the exhaust gas. The fuel injection amount supplied to 300 is determined, and the fuel injection amount supplied to the burner 300 is additionally feedback-controlled by using the value measured by the exhaust gas temperature sensor 840.

In addition, the electronic control module 900 predicts the amount of soot collected in the soot filtration filter 500 based on the value measured by the exhaust gas pressure sensor 830, and filters the soot filtration filter 500. When the amount of particulate particulate collected per volume is more than a predetermined standard, the burner 300 is operated to regenerate the particulate filter 600. At this time, the predetermined reference is characterized in that the value within the range of 5g / L to 8g / L.

In addition, the electronic control module 900 measures the concentration of nitrogen oxide discharged from the selective reduction catalyst 710 based on the value measured by the nitrogen oxide concentration sensor 860, and uses the nitrogen oxide concentration value. It is characterized by feeding back the amount of urea supplied from the urea supply device (700).

In addition, the vehicle exhaust gas reducing device includes an auxiliary burner 600 provided between the soot filtration filter 500 and the urea supply device 700; An auxiliary oxidation catalyst (410) provided between the urea supply device (700) and the selective reduction catalyst (710); An auxiliary exhaust gas temperature sensor 841 positioned at a rear end of the auxiliary oxidation catalyst 410 to monitor an exhaust gas temperature flowing into the selective reduction catalyst 710; It further comprises a, characterized in that the exhaust gas passing through the oxidation catalyst 400 and the soot filtration filter 500 to the secondary temperature is to be introduced into the selective reduction catalyst 710.

The vehicle exhaust gas reducing device of the present invention, by using a burner to increase the exhaust gas temperature when necessary, such as the start-up, improve the ability to reduce the harmful emissions of the selective reduction catalyst and oxidation catalyst, irrespective of the engine operating conditions, oil pollution problem It is effective to regenerate the soot filtration filter without causing the back.

1 is an embodiment 1 of the vehicle exhaust gas reduction device of the present invention.
Figure 2 is a second embodiment of the vehicle exhaust gas reducing apparatus of the present invention.
3 is a nitrogen oxide, carbon monoxide, unburned hydrocarbon reduction efficiency of the general catalyst according to the exhaust gas temperature.

Hereinafter, with reference to the accompanying drawings, a vehicle exhaust gas reducing device according to the present invention having the configuration as described above will be described in detail.

FIG. 1 illustrates an embodiment of a vehicle exhaust gas reducing apparatus of the present invention, and the vehicle exhaust gas reducing apparatus of the present invention will be described in detail with reference to FIG. 1. The exhaust gas reducing device of the present invention is installed in the exhaust pipe 200 of the engine 100, the burner 300, the oxidation catalyst 400, the soot filtration filter 500, the urea supply device 700, the selective reduction catalyst ( 710, various sensors 830, 840, 850, 860 and electronic control module 900. Hereinafter, each part will be described in more detail.

The burner 300 serves to increase the temperature of the exhaust gas by burning the fuel supplied from the vehicle fuel tank. When the fuel is burned in the burner 300, combustion gas having a very high temperature is generated, and the combustion gas of this high temperature is mixed with the exhaust gas circulated through the burner 300 to transfer heat to the exhaust gas. As a result, the temperature of the exhaust gas is increased.

The oxidation catalyst 400 is located at the rear end of the burner 300 and serves to oxidize the unburned hydrocarbon and carbon monoxide generated from the engine 100 or the burner 300. It is well known that incomplete combustion occurs when fuel is combusted, resulting in unburned hydrocarbons and carbon monoxide, and these materials have a significant adverse effect on the environment. At this time, the automobile exhaust gas and the combustion gas burned by the burner 300 passes through the oxidation catalyst 400, thereby preventing and removing the unburned hydrocarbons and carbon monoxide generated during incomplete combustion.

The soot filtration filter 500 is located at the rear end of the oxidation catalyst 500 to serve to collect particulate soot in the exhaust gas. In general, the soot filtration filter 600 is made of a heat resistant material such as ceramic or metal, and the particulate soot is filtered into a porous shape through which the exhaust gas can pass.

The urea supply device 700 is located at the rear end of the soot filtration filter 600, and supplies urea, a reducing agent required to reduce nitrogen oxides in the exhaust gas to nitrogen and water, and the selective reduction catalyst 710 is the urea. Located at the rear end of the supply device 700 serves to reduce the nitrogen oxides.

Various devices as described above are operated according to various conditions, and these conditions are obtained through values measured by various sensors provided between the devices.

The exhaust gas pressure sensor 830 monitors the amount of soot collected in the soot filtration filter 500. As described above, the soot filtration filter 500 has a porous shape to filter particulate soot and allow exhaust gas to pass therethrough. Therefore, the longer the collection time, the more the flow resistance is increased by the particulate smoke accumulated in the soot filtration filter 500, the passage through which the exhaust gas can be reduced, and thus the exhaust gas passing through the soot filtration filter 500 The pressure drop of the gas rises. Therefore, by the pressure value measured by the exhaust gas pressure sensor 830, it is possible to determine the degree of soot collection.

The exhaust gas temperature sensor 840 is located at the rear end of the oxidation catalyst 400 to monitor the exhaust gas temperature, and when the exhaust gas temperature passing through the oxidation catalyst is low, the burner 300 operates to operate the exhaust gas temperature. It is raised above the temperature at which the catalytic reaction is possible. In addition, the exhaust gas temperature sensor 840 is used to control the feedback so that the temperature of the exhaust gas flowing into the soot filtration filter 500 becomes about 600 ° C. during regeneration.

The nitrogen oxide concentration sensor 860 is positioned after the selective reduction catalyst 710 to measure the concentration of nitrogen oxide in the exhaust gas.

Finally, the electronic control module 900 is provided in the vehicle exhaust gas reducing device including the exhaust gas pressure sensor 830, the exhaust gas temperature sensor 840, the nitrogen oxide concentration sensor 850. The value measured by the sensors is used to control the operation of the burner 300.

The operation of each unit by the sensors will be described in detail as follows.

First, the burner 300 is operated when the amount of particulate soot collected in the soot filtration filter 500 is greater than or equal to a predetermined standard so that the regeneration of the soot filtration filter 500 is performed efficiently. Alternatively, or when the exhaust gas temperature is less than a predetermined criterion to efficiently purify the oxidation catalyst 500 or the selective reduction catalyst 710, the temperature of the exhaust gas is increased.

As described above, when the burner 300 is operated to increase the exhaust gas temperature, an intake air flow rate sensor 810 or an engine speed sensor installed in the engine 100 to reach a target temperature of the exhaust gas. The fuel injection amount supplied to the burner 300 is determined by using the value measured at 820, and the fuel injection amount supplied to the burner 300 by using the value measured at the exhaust gas temperature sensor 850. In addition, feedback is controlled. In the burner 300, heat is supplied by burning the injected fuel, and as the amount of fuel injected increases, the temperature of the exhaust gas may rise quickly. However, if too much fuel is injected, the temperature of the exhaust gas will rise sufficiently, but it may adversely affect the fuel efficiency of automobiles. Therefore, as described above, an appropriate fuel injection amount is determined through a value specified by the intake air flow rate sensor 810 or the engine speed detection sensor 820 provided in the engine 100, and is stepwise by feedback control. By determining the fuel injection amount, it is possible to reduce the waste of fuel and to reach the appropriate exhaust gas temperature as quickly as possible.

As described above, the electronic control module 900 may control the operation of the burner 300 by using values measured by various sensors, but may further control the following operations. First, the electronic control module 900 predicts the amount of soot collected in the soot filtration filter 500 based on the value measured by the exhaust gas pressure sensor 830, and then, in the exhaust gas pressure sensor 830. When the measured value is more than a predetermined reference, the burner 300 is operated to regenerate the soot filtration filter 500. As described above, as the collection amount of particulate soot increases, the flow resistance in the exhaust gas passing through the soot filtration filter 500 increases, thereby increasing the pressure drop, measured by the exhaust gas pressure sensor 830. The regeneration point of the soot filtration filter 600 is determined using the pressure value. That is, when the amount of particulate particulates collected per filter volume in the particulate filter 500 is greater than or equal to a predetermined standard (there is a constant correlation between the amount of particulate particulates collected per filter volume and the pressure, the pressure value is simply calculated therefrom. To make the filter play. At this time, the predetermined reference is preferably a value within the range of 5g / L to 8g / L.

In addition, the electronic control module 900 may determine the amount of nitrogen oxide in the exhaust gas based on a value measured by the intake air flow sensor 810 or the engine speed sensor 820 installed in the engine 100. In the prediction, the amount of nitrogen oxide is used to determine the amount of urea supplied from the urea supply device 700. Or, similar to the fuel injection amount control in the burner 300, the electronic control module 900 is the nitrogen oxide discharged from the selective reduction catalyst 710 by the value measured by the nitrogen oxide concentration sensor 860. The concentration may be measured, and the nitrogen oxide concentration value may be used to feed back the amount of urea supplied from the urea supply device 700. In addition, by mixing the two methods as described above, the amount of nitrogen oxides predicted by the value measured by the intake air flow sensor 810 or the engine speed sensor 820 installed in the engine 100 is calculated. The urea supply may be initially determined, and then fed back using the nitrogen oxide concentration value measured by the nitrogen oxide concentration sensor 860.

2 is another embodiment according to the present invention. In the embodiment of FIG. 2, one more burner is added in the embodiment of FIG. 1. In detail, one burner 300 is installed in front of the oxidation catalyst 400 and the soot filtration filter 500. In addition, a separate auxiliary burner 600 is installed in front of the selective reduction catalyst 710 to determine the exhaust gas temperature introduced into the oxidation catalyst 400, the soot filtration filter 500 and the selective reduction catalyst 710, respectively. It is a vehicle exhaust gas reduction device characterized by heating up. As such, when a separate auxiliary burner 600 is installed, the temperature of the exhaust gas flowing into the separate auxiliary oxidation catalyst 410 and the selective reduction catalyst 710 for the purpose of reducing unburned hydrocarbons and carbon monoxide generated from the burner is controlled. For this purpose, an auxiliary exhaust gas temperature sensor 841 is added.

Figure 3 shows the nitrogen oxide, carbon monoxide, unburned hydrocarbon reduction efficiency of the general catalyst according to the exhaust gas temperature, as shown in the case of carbon monoxide (CO) at 250 ℃ or more, at 300 ℃ or more for unburned hydrocarbons, In the case of nitrogen oxide (NOx) it can be seen that the highest purification efficiency between 300 ℃ to 400 ℃. The oxidation catalyst 500 mainly purifies unburned hydrocarbons and carbon monoxide, and the selective reduction catalyst 710 mainly purifies nitrogen oxides. Therefore, in order to achieve efficient purification of all harmful substances, it is preferable that a predetermined criterion of the exhaust gas temperature for purification in the oxidation catalyst 500 or the selective reduction catalyst 710 is a value of 250 ° C. to 300 ° C. or more. Do.

The present invention is not limited to the above-described embodiments, and the scope of application of the present invention is not limited to those of ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention as claimed in the claims. Of course, various modifications can be made.

100: engine
200: exhaust pipe
300: burner 310: fuel supply module
400: oxidation catalyst 410: auxiliary oxidation catalyst
500: soot filtration filter
600: auxiliary burner 610: auxiliary fuel supply module
700: urea supply device 701: urea storage container
702: urea supply pump 703: urea supply nozzle
710: selective reduction catalyst (for reducing nitrogen oxides)
810: intake air flow sensor
820: engine speed sensor
830: exhaust gas pressure sensor
840: exhaust gas temperature sensor 841: auxiliary exhaust gas temperature sensor
850: nitrogen oxide concentration sensor
900: electronic control module

Claims (7)

In the vehicle exhaust gas reduction device installed in the engine 100, exhaust pipe 200,
A burner 300 for burning the fuel supplied from the vehicle fuel tank to increase the temperature of the exhaust gas;
An oxidation catalyst 400 installed at the rear end of the burner 300 to oxidize unburned hydrocarbon and carbon monoxide generated from the engine 100 or the burner 300;
A soot filtration filter 500 positioned at a rear end of the oxidation catalyst 400 to collect particulate soot in the exhaust gas;
Located at the rear of the burner 300, a urea supply device for supplying urea which is a reducing agent for reducing nitrogen oxide in the exhaust gas to nitrogen and water;
A selective reduction catalyst 710 positioned at a rear end of the urea supply device 700 to reduce nitrogen oxides;
An exhaust gas pressure sensor 830 installed in front of the soot filtration filter 500 to monitor an amount of soot collected in the soot filtration filter 500;
An exhaust gas temperature sensor 840 positioned at a rear end of the oxidation catalyst 400 to monitor an exhaust gas temperature flowing into the soot filtration filter 500;
A nitrogen oxide concentration sensor 850 positioned at a rear end of the selective reduction catalyst 710 to measure a concentration of nitrogen oxides in the exhaust gas;
The burner using the values measured in the sensors provided in the vehicle exhaust gas reducing device including the exhaust gas pressure sensor 840, the exhaust gas temperature sensor 850, the nitrogen oxide concentration sensor 860. An electronic control module 900 for controlling the operation of 300;
Vehicle emission reduction device, characterized in that comprises a.
The method of claim 1, wherein the burner 300
The soot filtration filter 500 is operated when regeneration is required to raise the temperature of the exhaust gas to 500 ℃ to 600 ℃, or
When the exhaust gas temperature is 200 ° C to 250 ° C or less so as to efficiently purify the oxidation catalyst 400 or the selective reduction catalyst 710, the vehicle exhaust gas reduction, characterized in that to increase the temperature of the exhaust gas Device.
The method of claim 1, wherein the burner 300
In order to reach the target temperature of the exhaust gas, a value measured by the intake air flow rate sensor 810 or the engine speed sensor 820 installed in the engine 100 is used to supply the fuel injection amount to the burner 300. It is determined, and the value measured in the exhaust gas temperature sensor (840) is used, the fuel injection amount supplied to the burner (300) further feedback control, characterized in that the vehicle.
The method of claim 1, wherein the electronic control module 900
The amount of soot collected in the soot filtration filter 500 is predicted based on the value measured by the exhaust gas pressure sensor 830, and the amount of particulate soot collected per filter volume in the soot filtration filter 500 is predetermined. The vehicle exhaust gas reduction device, characterized in that for regenerating the soot filtration filter 600 by operating the burner (300) or more than the reference.
The method of claim 4, wherein the predetermined criterion is
Vehicle emission reduction device, characterized in that the value in the range of 5g / L to 8g / L.
The method of claim 1, wherein the electronic control module 900
The concentration of nitrogen oxide discharged from the selective reduction catalyst 710 is measured based on the value measured by the nitrogen oxide concentration sensor 860, and the nitrogen oxide concentration value is supplied from the urea supply device 700. A vehicle emission reduction device characterized in that the feedback of the amount of urea.
According to claim 1, wherein the vehicle emissions reduction device
An auxiliary burner 600 provided between the soot filtration filter 500 and the urea supply device 700;
An auxiliary oxidation catalyst (410) provided between the urea supply device (700) and the selective reduction catalyst (710);
An auxiliary exhaust gas temperature sensor 841 positioned at a rear end of the auxiliary oxidation catalyst 410 to monitor an exhaust gas temperature flowing into the selective reduction catalyst 710;
It further comprises, the exhaust gas passing through the oxidation catalyst 400 and the soot filtration filter 500 to increase the secondary gas inlet to the selective reduction catalyst 710, characterized in that for introducing the selective reduction catalyst 710 .

Images