JP2007255256A - Exhaust emission control device in internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely regenerate a particulate filter by injection supply of fuel from an injection valve of regenerating fuel. <P>SOLUTION: This internal combustion engine is formed by arranging the injection valve 14 of the regenerating fuel to the particulate filter in a part between an exhaust turbocharger and the particulate filter among an exhaust passage, by arranging at least the particulate filter 12 by positioning the particulate filter on the downstream side of the exhaust turbocharger, by arranging the exhaust turbocharger 5 in the exhaust passage 6 to the atmosphere from a cylinder. A bypass passage 15 is arranged in the exhaust passage for communicating its upstream side with the downstream side by bypassing the exhaust turbocharger. At least in the timing when the injection valve of the regenerating fuel performs the injection supply of the fuel, exhaust gas on the upstream side of the exhaust turbocharger is introduced to a fuel injection place by the injection valve of the regenerating fuel via this bypass passage. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides an internal combustion engine such as a diesel engine provided with an exhaust turbocharger in an exhaust path from the internal combustion engine, and at least a part of the exhaust gas included in the exhaust gas downstream from the exhaust turbocharger. The present invention relates to an exhaust emission control device provided with a particulate filter (hereinafter referred to as DPF) for collecting curates.

  In recent diesel engines, a DPF is provided at a site downstream of the exhaust turbocharger in the exhaust path from the cylinder of the diesel engine to the atmosphere for purification of the exhaust gas. If the collected particulate matter accumulates as it is, the pressure loss of the exhaust gas will increase and the performance of the internal combustion engine will deteriorate, so by adding and supplying fuel to the exhaust path at an appropriate time, The DPF is regenerated by burning off.

In this case, Patent Document 1 as the prior art discloses an exhaust manifold for guiding the exhaust gas supplied from each cylinder in the internal combustion engine to the exhaust turbo supercharger for supplying fuel for regenerating the DPF to the exhaust path. In addition, Patent Document 2 as another prior art proposes that a refueling fuel injection valve provided on the exhaust path between the exhaust turbocharger and the DPF in the exhaust path. It is proposed to use a fuel injection valve for regeneration provided at the site.
JP 2001-280125 A JP-A-7-269329

  The temperature of exhaust gas from each cylinder in the internal combustion engine is the highest in the exhaust manifold portion, but when the exhaust gas passes through the exhaust turbocharger, the thermal energy it has is recovered by the exhaust turbocharger It becomes low suddenly.

  Therefore, if the fuel injection for regenerating the DPF is performed by the regenerative fuel injection valve provided in the exhaust manifold as in Patent Document 1, the regenerative fuel is heated to a high temperature. The exhaust gas is sufficiently vaporized instantaneously at the same time as the supply, so that the reaction in a nearly complete state (reaction between oxygen in the exhaust gas and hydrogen and carbon of the regenerative fuel) is achieved. However, on the other hand, when the regeneration fuel passes through the exhaust turbocharger, a part of the fuel adheres to the impeller and the turbine shaft, and the exhaust turbocharger has a serious malfunction. Not only will this cause a problem, but the regeneration fuel injection valve will be directly subjected to the heat damage of the exhaust manifold, which is at the highest temperature.

  In addition, as in Patent Document 2, the fuel supply for regenerating the DPF is performed by a regeneration fuel injection valve provided downstream of the exhaust turbocharger. Although it is possible to alleviate the occurrence of malfunction of the exhaust turbocharger due to fuel and the thermal damage in the regeneration fuel injection valve, the exhaust gas at the location of the regeneration fuel injection valve is: In order to sufficiently vaporize the regeneration fuel sufficiently, there is a problem that the regeneration fuel cannot be sufficiently vaporized due to its low temperature after passing through the exhaust turbocharger. As described in Patent Document 2, it is necessary to provide a heater such as a glow plug at the injection supply portion of the regeneration fuel in the exhaust path so as to promote vaporization. there were

  It is a technical object of the present invention to provide an exhaust purification device that solves these problems.

In order to achieve this technical problem, the present invention as described in claim 1,
“In the exhaust path from the cylinder to the atmosphere, an exhaust turbocharger is provided, and at least the particulate filter is provided so that the particulate filter is located downstream of the exhaust turbocharger. In an internal combustion engine in which an injection valve for regeneration fuel for the particulate filter is provided in a portion of the exhaust path between the exhaust turbocharger and the particulate filter.
The exhaust passage is provided with a bypass passage that bypasses the exhaust turbocharger and communicates the upstream side and the downstream side thereof, and at least the time when the regeneration fuel injection valve performs fuel injection supply In addition, the exhaust gas on the upstream side of the exhaust turbocharger is configured to be led to a fuel injection point by the regeneration fuel injection valve via the bypass passage. "
It is characterized by that.

  In this configuration, the regeneration fuel injection valve portion of the exhaust path is supplied with exhaust gas at a high temperature before passing through the exhaust turbocharger through the bypass passage, so that the regeneration fuel is supplied. Since the fuel supplied by the fuel injection valve is directly brought into contact with and mixed with the exhaust gas at this high temperature, all of the fuel can be instantly and reliably vaporized simultaneously with the injection.

  Therefore, according to the present invention, the regeneration of the particulate filter is performed by the fuel injection from the regeneration fuel injection valve, which causes less heat damage to the regeneration fuel injection valve, and further to the exhaust path. This can be reliably achieved without providing a heater for vaporizing the regeneration fuel and without adversely affecting the exhaust turbocharger due to malfunctions due to the regeneration fuel.

  An embodiment of the present invention will be described below with reference to the drawing of FIG.

  In this figure, reference numeral 1 denotes a multi-cylinder type diesel engine having a plurality of cylinders. On one side of the diesel engine, compressed intake air from an exhaust turbocharger 5 described later is supplied to each cylinder. An intake manifold 2 for distributing and an exhaust manifold 3 for collecting exhaust gas from each cylinder in one exhaust passage 4 are attached to the other side surface.

  Reference numeral 5 denotes an exhaust turbocharger in which an exhaust turbine 5a and a compression blower 5b are directly connected. An exhaust inlet from the exhaust turbine 5a of the exhaust turbocharger 5 is connected to an exhaust from the exhaust manifold 3. An exhaust passage 6 to the atmosphere is connected to the discharge port of the passage 4.

  On the other hand, an intake pipe 8 from the air cleaner 7 is connected to the suction port of the compression blower 5b of the exhaust turbocharger, and an intake pipe 9 to the intake manifold 2 is connected to the discharge port. .

  In the middle of the exhaust path 6 from the exhaust turbocharger 5 to the atmosphere, an oxidation catalyst 10 that purifies HC and the like in the exhaust gas by an oxidation reaction and NOx in the exhaust gas are adsorbed. The NOx occlusion reduction catalyst 11 and the particulate filter 12 are provided in series in this order from the upstream side.

  A fuel supply unit 13 is provided in a portion of the exhaust path 6 upstream of the oxidation catalyst 10 and between the exhaust turbocharger 5 and a fuel injection valve 14 for regeneration fuel is provided in the fuel supply unit 13. When the regeneration of the particulate filter 12 is performed, the fuel for the regeneration is injected and supplied from the regeneration fuel injection valve 14 to the fuel supply unit 13.

  One end of a bypass passage 15 that bypasses the exhaust turbocharger 5 is connected to the exhaust manifold 3 or the exhaust passage 4 upstream of the exhaust turbocharger 5, and the other end of the bypass passage 15 is connected to the exhaust manifold 3 or the exhaust passage 4. , While being connected to the fuel supply unit 13, an on-off valve 16 is provided in the middle of the bypass passage 15, and the exhaust gas turbocharger 14 is in a state where the fuel injection valve 14 is supplying fuel. An appropriate amount of exhaust gas upstream from the supercharger 5 is configured to be introduced into the fuel supply unit 13.

  In this configuration, in the exhaust path 6 from the exhaust turbocharger 5 to the atmosphere, the fuel supply unit 13 to which the regeneration fuel injection valve 14 is attached is located before passing through the exhaust turbocharger 5. Since the high temperature exhaust gas is supplied through the bypass passage 15, the fuel injected and supplied to the fuel supply unit 13 by the regeneration fuel injection valve 14 is directly connected to the high temperature exhaust gas. Therefore, it is vaporized instantaneously and almost completely simultaneously with the injection supply.

  By the way, in order to further promote the vaporization of the fuel supplied to the fuel supply unit 13 by the fuel injection valve 14 for regeneration, for example, the fuel supply unit 13 is introduced through the bypass passage 15. The exhaust gas is configured to face the fuel injection direction from the regeneration fuel injection valve 14, or a swirl flow is imparted to the exhaust gas introduced into the fuel supply unit 13 via the bypass passage 15. Then, various means can be employed such as making the fuel supplied by the regeneration fuel injection valve 14 face or mount the swirling flow of the exhaust gas.

  Note that, as in the above-described embodiment, the oxidation catalyst 10 and the NOx occlusion reduction catalyst 11 are provided in a portion of the exhaust path 6 between the fuel supply unit 13 and the particulate filter 12. In this case, the fuel supply unit 13 can instantaneously and completely vaporize the regenerating fuel at the same time as the injection supply thereof, so that the oxidation catalyst 10 can be brought to a high temperature from the start of the internal combustion engine, In other words, exhaust gas purification by vigorous oxidation reaction in the oxidation catalyst 10 can be ensured from the start of the internal combustion engine, and the vigorous oxidation reaction from the start of the internal combustion engine. Thus, there is an advantage that reliable reduction in the NOx storage reduction catalyst 11 can be achieved.

  In the above embodiment, the particulate filter 12 is configured separately from the oxidation catalyst 10 and the NOx storage reduction catalyst 11. However, the present invention is not limited to this, and the particulate filter It goes without saying that the present invention can also be applied to a case where the filter is configured by combining one or both of an oxidation catalyst and a NOx storage reduction catalyst.

It is a figure which shows embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multi-cylinder diesel engine 2 Intake manifold 3 Exhaust manifold 4 Exhaust pipe 5 Exhaust turbocharger 5a Exhaust turbine 5b Compression blower 6 Exhaust path 7 Air cleaner 9 Intake duct 10 Oxidation catalyst 11 NOx storage reduction catalyst 12 Particulate filter 13 Fuel Supply section 14 Fuel injection valve for regeneration 15 Bypass passage 16 On-off valve

Claims (1)

An exhaust turbocharger is provided in the exhaust path from the cylinder to the atmosphere, and at least a particulate filter is provided so that the particulate filter is located downstream of the exhaust turbocharger. In the internal combustion engine in which a regenerative fuel injection valve for the particulate filter is provided in a portion of the path between the exhaust turbocharger and the particulate filter,
The exhaust passage is provided with a bypass passage that bypasses the exhaust turbocharger and communicates the upstream side and the downstream side thereof, and at least the time when the regeneration fuel injection valve performs fuel injection supply Further, the exhaust gas purifying apparatus for an internal combustion engine, characterized in that exhaust gas upstream of the exhaust turbocharger is guided to a fuel injection location by the fuel injection valve for regeneration through the bypass passage. .

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