JP2016200090A - Catalyst-using exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst-using exhaust emission control device that can suppress a decline in an exhaust purification rate in a catalyst even when an exhaust flow rate in an exhaust pipe is large.SOLUTION: A catalyst-using exhaust emission control device 100 purifies exhaust gas discharged from an internal combustion engine 101 through an exhaust pipe 102 into the atmosphere by using a catalyst. The catalyst-using exhaust emission control device 100 includes an exhaust storage device 400 for storing exhaust gas when an exhaust flow rate in the exhaust pipe 102 is large and emitting the stored exhaust gas when the exhaust flow rate in the exhaust pipe 102 is small.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a catalyst-based exhaust purification device that purifies exhaust using a catalyst.

  An automobile equipped with an internal combustion engine such as a diesel engine employs an exhaust purification device that purifies exhaust discharged from the internal combustion engine through an exhaust pipe. As an exhaust purification device, there is known a catalyst-based exhaust purification device such as a selective catalyst reduction device that reduces nitrogen oxides discharged into the atmosphere by reducing nitrogen oxides contained in exhaust gas with an SCR catalyst. (For example, see Patent Document 1).

JP 2000-303826 A

  By the way, in a catalyst-based exhaust purification device, when the exhaust gas flow rate in the exhaust pipe is large (for example, when an automobile is accelerated), the exhaust gas flow velocity in the exhaust pipe increases and the exhaust gas immediately passes through the catalyst without waiting for the purification. Therefore, there is a problem that the exhaust gas purification rate in the catalyst decreases.

  Accordingly, an object of the present invention is to provide a catalyst-based exhaust purification device capable of suppressing a decrease in the exhaust purification rate of a catalyst even when the exhaust flow rate in the exhaust pipe is large.

  The present invention devised to achieve this object is a catalyst-based exhaust gas purification apparatus that purifies exhaust gas discharged from an internal combustion engine into the atmosphere through an exhaust pipe using a catalyst, and has a large exhaust flow rate in the exhaust pipe. In this case, the exhaust gas is stored in the exhaust pipe and the exhaust gas is stored when the exhaust gas flow rate in the exhaust pipe is small.

  The exhaust storage device stores exhaust when the exhaust flow rate in the exhaust pipe is assumed to be greater than or equal to a threshold based on the operating state of the internal combustion engine, and the exhaust flow rate in the exhaust pipe is assumed to be less than the threshold. In this case, it is preferable to release the stored exhaust gas in a range where the exhaust gas flow rate in the exhaust pipe does not exceed the threshold value.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where the exhaust gas flow rate in an exhaust pipe is large, the catalyst utilization exhaust gas purification apparatus which can suppress the fall of the exhaust gas purification rate in a catalyst can be provided.

It is the schematic which shows the catalyst utilization exhaust gas purification apparatus which concerns on this invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, a catalyst-based exhaust purification device 100 uses a catalyst to remove harmful substances contained in exhaust discharged from an internal combustion engine 101 such as a diesel engine through an exhaust pipe 102. This is a device for purifying exhaust gas discharged into the atmosphere. For example, a diesel particulate filter (DPF) device 200 and a selective catalyst reduction (SCR) device 300 are mounted.

  The diesel particulate filter device 200 is installed in the exhaust pipe 102 and collects particulate matter contained in the exhaust to reduce the amount of particulate matter discharged into the atmosphere. A collection filter 201 is provided. Although FIG. 1 is drawn in a simplified manner, the exhaust pipe 102 is routed through various routes according to the layout of the automobile.

  In the diesel particulate filter device 200, the internal combustion engine control unit (ECU) 103 is installed on the exhaust upstream side of the diesel particulate filter 201 when the particulate matter accumulation amount in the diesel particulate filter 201 is equal to or greater than a threshold value. The fuel is injected into the exhaust gas from the exhaust pipe fuel injector 202, the fuel is combusted in the exhaust gas to raise the exhaust gas temperature, and the diesel particulate filter temperature is raised to raise the diesel particulate filter 201. The particulate matter collected by the diesel particulate filter 201 is removed by burning the particulate matter collected by the diesel particulate filter.

  In addition, the diesel particulate filter device 200 is installed on the exhaust upstream side of the diesel particulate filter 201 and at the injection destination of fuel injected into the exhaust gas from the exhaust pipe fuel injector 202 and is exhausted. A catalyst 203 for accelerating combustion of fuel injected into the exhaust gas from the pipe fuel injector 202 is provided.

  The selective catalyst reduction device 300 includes an SCR catalyst 301 that is installed in the exhaust pipe 102 and that reduces nitrogen oxides discharged into the atmosphere by reducing nitrogen oxides contained in the exhaust. Yes.

  In the selective catalyst reduction device 300, urea water is injected into the exhaust gas from the urea water injector 303 installed on the exhaust upstream side of the SCR catalyst 301 by the urea water injection control unit (DCU) 302 when the vehicle is running. Then, urea water is hydrolyzed in the exhaust gas to generate ammonia, and ammonia is stored in the SCR catalyst 301 to decompose nitrogen oxides contained in the exhaust gas into nitrogen and water. The contained nitrogen oxides are reduced.

  In addition, the selective catalyst reduction device 300 is installed on the upstream side of the SCR catalyst 301 on the exhaust side, at the injection destination of urea water injected into the exhaust gas from the urea water injector 303, and from the urea water injector 303. A catalyst 304 that promotes hydrolysis of urea water injected into the exhaust, a urea water storage tank 305 that stores urea water, and urea water from the urea water storage tank 305 to the urea water injector 303 through the urea water pipe 306. A urea water supply module 308 having a urea water supply pump 307 for supplying water.

  The exhaust gas temperature detector 104 that detects the exhaust gas temperature at the inlet of the SCR catalyst 301 and the first nitrogen oxide concentration detector 309 that detects the nitrogen oxide concentration at the inlet of the SCR catalyst 301 include the SCR catalyst 301. A second nitrogen oxide concentration detector 310 that is installed upstream of the exhaust and detects the nitrogen oxide concentration at the outlet of the SCR catalyst 301 is installed downstream of the SCR catalyst 301.

  Further, a urea water remaining amount detector 311 for detecting the urea water remaining amount in the urea water storage tank 305, a urea water temperature detector 312 for detecting the urea water temperature in the urea water storage tank 305, and the urea water storage tank 305. An SCR sensor 314 having a urea water quality detector 313 that detects urea water quality (for example, urea water concentration or presence / absence of foreign matter) is installed in the urea water storage tank 305.

  The urea water pipe 306 has a suction flow path 315 that connects the urea water storage tank 305 and the suction port of the urea water supply pump 307, and a supply flow that connects the discharge port of the urea water supply pump 307 and the urea water injector 303. A passage 316 and a recovery passage 317 connecting the discharge port of the urea water supply pump 307 and the urea water storage tank 305 are provided.

  The urea water supply module 308 includes a urea water supply pump 307 that sucks urea water from the urea water storage tank 305 through the suction flow path 315 and supplies urea water to the urea water injector 303 through the supply flow path 316, and a urea water supply pump. A temperature detector 318 that detects the temperature at 307, a urea water pressure detector 319 that detects the urea water pressure at the discharge port of the urea water supply pump 307, and urea water is supplied to the urea water injector 303 through the supply channel 316. And a switching valve 320 for switching the urea water storage tank 305 to the flow path for recovering urea water through the recovery flow path 317.

  Although FIG. 1 is drawn in a simplified manner, the internal combustion engine cooling water along a urea water supply path constituted by a urea water storage tank 305, a urea water injector 303, a urea water supply pump 307, and a urea water pipe 306. A circulation flow path 321 for circulating the internal combustion engine is arranged, and a defrosting output adjustment valve 322 for switching whether or not to flow the cooling water for the internal combustion engine along the urea water supply path is installed in the circulation flow path 321.

  Note that the circulation flow path 321 always supplies the internal combustion engine cooling water to the urea water injector 303 regardless of whether the thawing output adjustment valve 322 is open or closed, and the urea water filled in the urea water injector 303. Prevents alteration sticking.

  In the catalyst-based exhaust gas purification apparatus 100, the exhaust gas flow rate in the exhaust pipe 102 is set on the exhaust upstream side of a catalyst (for example, the SCR catalyst 301) that purifies exhaust gas exhausted from the internal combustion engine 101 through the exhaust pipe 102. The exhaust gas storage device 400 is provided for storing exhaust gas when there is a large amount of exhaust gas and discharging exhaust gas stored when the exhaust gas flow rate in the exhaust pipe 102 is small.

  The exhaust storage device 400 includes a bypass pipe 401 that bypasses a part of the exhaust discharged from the internal combustion engine 101 through the exhaust pipe 102, a bypass exhaust flow rate adjustment valve 402 that adjusts a bypass exhaust flow rate in the bypass pipe 401, and a bypass pipe 401. And an exhaust storage container 403 that compresses and stores the exhaust passing through the bypass pipe 401 by a compressor or the like.

  The exhaust storage device 400 stores the exhaust when the exhaust flow rate in the exhaust pipe 102 is assumed to be equal to or higher than a threshold based on the operating state of the internal combustion engine 101 (for example, during acceleration of the automobile) and When it is assumed that it is less than the threshold value (for example, when the automobile is decelerated), the exhaust gas stored in a range where the exhaust gas flow rate in the exhaust pipe 102 does not exceed the threshold value is released.

  As a result, when it is assumed that the exhaust gas flow rate in the exhaust pipe 102 will increase and the exhaust gas flow velocity in the exhaust pipe 102 will increase in the future, and the exhaust gas purification rate in the catalyst will decrease, the surplus that will cause the exhaust gas purification rate in the catalyst to decrease. Exhaust gas is stored in the exhaust gas storage container 403. In the future, the exhaust gas flow rate in the exhaust pipe 102 decreases, the exhaust gas flow rate in the exhaust pipe 102 decreases, and there is a margin until the exhaust gas purification rate in the catalyst decreases due to the increase in exhaust gas flow rate in the exhaust pipe 102 When it is assumed that there is an exhaust gas, surplus exhaust gas stored in the exhaust gas storage container 403 can be discharged to the exhaust pipe 102, so that the exhaust gas is purified by the catalyst, and the reduction in the exhaust gas purification rate in the catalyst is suppressed. It becomes possible to do.

  As described above, according to the present invention, even when the exhaust gas flow rate in the exhaust pipe 102 is large, the catalyst-based exhaust purification device 100 that can suppress the reduction in the exhaust purification rate in the catalyst (for example, the SCR catalyst 301). Can be provided.

DESCRIPTION OF SYMBOLS 100 Catalyzed exhaust gas purification apparatus 101 Internal combustion engine 102 Exhaust pipe 103 Internal combustion engine control apparatus 104 Exhaust temperature detector 200 Diesel particulate collection filter apparatus 201 Diesel particulate collection filter 202 Exhaust pipe fuel injector 203 Catalyst 300 Selective catalyst reduction apparatus 301 SCR Catalyst 302 Urea water injection control device 303 Urea water injector 304 Catalyst 305 Urea water storage tank 306 Urea water pipe 307 Urea water supply pump 308 Urea water supply module 309 First nitrogen oxide concentration detector 310 Second nitrogen oxide Concentration detector 311 Urea water remaining amount detector 312 Urea water temperature detector 313 Urea water quality detector 314 SCR sensor 315 Suction passage 316 Supply passage 317 Recovery passage 318 Temperature detector 319 Urea water pressure detector 320 Switching valve 321 Circulating flow path 322 Thaw output adjustment valve 00 exhaust storage device 401 bypassing pipe 402 bypassing the exhaust flow rate adjusting valve 403 exhaust reservoir

Claims (2)

In a catalyst-based exhaust purification device that purifies exhaust discharged into the atmosphere from an internal combustion engine through an exhaust pipe using a catalyst,
A catalyst-based exhaust gas purification device comprising an exhaust gas storage device that stores exhaust gas when the exhaust gas flow rate in the exhaust pipe is large and releases exhaust gas that is stored when the exhaust gas flow rate in the exhaust pipe is small .   The exhaust storage device stores exhaust when the exhaust flow rate in the exhaust pipe is assumed to be greater than or equal to a threshold based on the operating state of the internal combustion engine, and the exhaust flow rate in the exhaust pipe is assumed to be less than the threshold. 2. The catalyst-based exhaust purification device according to claim 1, wherein the exhaust gas stored in a range in which the exhaust gas flow rate in the exhaust pipe does not exceed the threshold value is released.

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