JP2017110556A - Exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control device that can prevent soot from depositing in an injection port of an injector without a decline in cleaning rate of an exhaust gas.SOLUTION: The exhaust emission control device includes: the injector 4 inserted into an exhaust passage 2 of a diesel engine 1 having a plurality of bent parts 5a to 5d; and a PM collection filter 7 interposed into the exhaust passage 2 positioned downstream of the injector 4, where the injector 4 is inserted from an inner side of the bent part 5a coming closest to the diesel engine 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust gas purification device, and more particularly, to an exhaust gas purification device that can prevent soot from accumulating in an injection nozzle portion without reducing the purification rate of exhaust gas.

  A vehicle using a diesel engine as a drive source is equipped with an exhaust gas purification device for removing harmful substances such as particulate matter (PM) and nitrogen oxide (NOx) contained in the exhaust gas.

  As for the former PM, a PM collection filter that collects and purifies PM by a filter made of a honeycomb-like porous body made of ceramics is mainly used (for example, see Patent Document 1). In order to prevent clogging by the collected PM, the PM collection filter needs to burn and remove PM before reaching the collection limit amount. When the temperature of the exhaust gas is a high temperature such as 500 ° C. or higher, PM spontaneously burns continuously. However, when the temperature of the exhaust gas is low, unburned fuel is supplied into the exhaust gas, and the hydrocarbon (HC) of the unburned fuel is burned by the oxidation catalyst (DOC) arranged in the front stage of the filter, and the oxidation reaction The forced regeneration which heats exhaust gas by heating DOC to about 600 degreeC using heat and forcibly burns the collected PM is required.

  Usually, unburned fuel is supplied into the exhaust gas by an injector inserted in the exhaust passage. This injector sprays unburned fuel from the tip part of the nozzle, but there is a possibility that soot contained in the exhaust gas accumulates on the nozzle part and causes a spray abnormality.

JP 2005-16317 A

  An object of the present invention is to provide an exhaust gas purifying device capable of preventing soot from accumulating in an injection nozzle portion without reducing the exhaust gas purification rate.

  An exhaust gas purifying apparatus of the present invention that achieves the above object includes an injector inserted into an exhaust passage of an engine having a plurality of curved portions, a PM collection filter interposed in the exhaust passage downstream of the injector, The exhaust gas purifying apparatus having the above-described configuration is characterized in that the injector is inserted from the inside of the curved portion closest to the engine among the plurality of curved portions.

  According to the exhaust gas purification apparatus of the present invention, since the injector is inserted from the inside of the curved portion closest to the engine, the stay of soot is suppressed by the exhaust gas vortex generated inside the curved portion of the exhaust passage. As a result, accumulation of soot at the injection hole of the injector can be prevented. Moreover, since the unburned fuel is sprayed in the high-temperature exhaust gas, the unburned fuel is sufficiently mixed with the exhaust gas without forming droplets and used for regeneration of the PM collection filter. There is no decline.

It is a block diagram of the exhaust gas purification apparatus which consists of embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an exhaust gas purifying apparatus according to the first embodiment of the present invention.

  This exhaust gas purification device is inserted into a large-diameter catalytic converter 3 interposed in an exhaust passage 2 through which exhaust gas G from a diesel engine 1 mounted on a vehicle flows, and an exhaust passage 2 upstream of the catalytic converter 3. The injector 4 is provided.

  In the exhaust passage 2, a plurality (four in this example) of curved portions 5 a to 5 d corresponding to the layout of the vehicle are formed in order from the diesel engine 1.

  In the catalytic converter 3, a PM collection filter 7 in which an oxidation catalyst (DOC) 6 is disposed in the previous stage is stored. The DOC 6 is formed by supporting rhodium, cerium oxide, platinum, aluminum oxide or the like on a metal carrier formed into a structure having a function of mixing the exhaust gas G of the diesel engine 1. The PM collection filter 7 is formed of a monolith honeycomb wall flow type filter in which the inlet and outlet of a porous ceramic honeycomb channel (cell) are alternately plugged. In the configuration example of FIG. 1, the DOC and the PM collection filter are separated from each other. However, the DOC and the PM collection filter may be integrally used as a CSF in which an oxidation catalyst substance is supported on the filter.

  The injector 4 has a function of spraying unburned fuel pumped from a fuel tank (not shown) from the nozzle portion 8 at the tip located in the exhaust passage 2. The injector 4 is inserted inclined toward the downstream side of the exhaust passage 2 so that the unburned fuel and the exhaust gas G are sufficiently mixed.

  In such an exhaust gas purification device, the injector 4 is inserted into the exhaust passage 2 from the inside of the curved portion 5a closest to the diesel engine 1 among the four curved portions 5a to 5d.

  With this configuration, the stay of soot is suppressed by the vortex of the exhaust gas G generated inside the curved portion 5a of the exhaust passage 2, so that soot can be prevented from accumulating at the nozzle portion 8 of the injector 4. It can be done. Further, since the unburned fuel is sprayed in the high-temperature exhaust gas G immediately after being discharged from the diesel engine 1, the unburned fuel is sufficiently mixed with the exhaust gas G without forming droplets, and the PM collection filter 7 Since it is used for regeneration, the purification rate of the exhaust gas G does not decrease.

DESCRIPTION OF SYMBOLS 1 Diesel engine 2 Exhaust passage 3 Catalytic converter 4 Injector 5a-5d Curved part 6 DOC
7 PM collection filter 8 Port

Claims (2)

In an exhaust gas purification apparatus comprising: an injector inserted into an exhaust passage of an engine having a plurality of curved portions; and a PM collection filter interposed in the exhaust passage on the downstream side of the injector;
An exhaust gas purifier having a configuration in which the injector is inserted from the inside of a curved portion closest to the engine among the plurality of curved portions.   The exhaust gas purifying apparatus according to claim 1, wherein the injector is configured to be inclined and inserted toward the downstream side of the exhaust passage.

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