JP5916366B2 - Exhaust gas recirculation device - Google Patents

Description

  The present invention relates to an exhaust gas recirculation device that extracts a part of exhaust gas from an exhaust side and recirculates it to an intake side.

  2. Description of the Related Art Conventionally, in an automobile engine or the like, a part of exhaust gas is extracted from the exhaust side and returned to the intake side. So-called exhaust gas recirculation (EGR), which reduces the generation of NOx by lowering, is performed. Generally, when this type of exhaust gas recirculation is performed, an exhaust manifold is used. An EGR pipe connects between one end portion of the cylinders in the (exhaust passage upstream from the turbine) and one end portion of the intake pipe (intake passage downstream from the compressor) connected to the intake manifold, The exhaust gas is recirculated through the EGR pipe.

  In addition, if the recirculated exhaust gas is cooled in the middle of the EGR pipe, the temperature of the exhaust gas decreases and the volume of the exhaust gas decreases, thereby reducing the combustion temperature and reducing the combustion power effectively. Since generation of objects can be reduced, a water-cooled EGR cooler is provided in the middle of an EGR pipe for recirculating exhaust gas.

  The prior art document information related to the exhaust gas recirculation device includes the following Patent Document 1 and the like.

JP 2003-120430 A

  However, in the conventional exhaust gas recirculation device as described above, the exhaust manifold and the intake pipe are simply connected by an external EGR pipe to extract a part of the exhaust gas. It has a structure that does not contribute to keeping the temperature of the exhaust gas emitted from the engine high, and there is a problem that the heat of the exhaust gas emitted from the engine is lost wastefully.

  In other words, many water cooling chambers are formed in the cylinder block and cylinder head of the engine as long as the required strength is not impaired, and the engine can be efficiently cooled with cooling water. The exhaust gas discharged to the exhaust port is immediately cooled by the cooling water in the water cooling chamber surrounding the exhaust port, and the exhaust gas discharged from each exhaust port to the exhaust manifold By having a large heat dissipation surface, much heat was taken away by the outside air.

  As a result, the turbine inlet temperature decreases, turbine work efficiency becomes worse, and the turbine expansion ratio must be set higher to obtain the required compressor work, resulting in higher exhaust manifold pressure. This was one factor that increased pumping loss and reduced fuel consumption.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to insulate exhaust gas emitted from an engine by devising a flow path structure of exhaust gas recirculated from the exhaust side to the intake side. And

The present invention relates to an exhaust gas recirculation device in which a part of exhaust gas is extracted from the exhaust side and recirculated to the intake side, and the outlet portion is arranged around the outlet portion of each exhaust port in the cylinder head. Forming an EGR chamber isolated from each other, communicating the EGR chamber and the outlet of the exhaust port for each cylinder, and communicating each EGR chamber adjacent to each other between the cylinders. The EGR chamber located in the EGR chamber is used as an extraction EGR chamber , the exhaust manifold has a double shell structure, an EGR flow passage is formed between the outer shell and the inner shell, and the end of the extraction EGR chamber and the EGR flow The ends of the passages are connected by connecting pipes, and the exhaust gas in the EGR flow passage is connected to the vicinity of the intake manifold on the opposite side of the connecting side of the connecting pipe in the EGR flow passage. Connect the EGR pipe leading to the trachea, characterized in that it has an exhaust gas taken out from the EGR chamber for the withdrawal to so that to recirculation to the intake side guided to the EGR pipe via the EGR passage Is.

  Thus, in this way, the EGR chamber around the outlet portion of each exhaust port in the cylinder head becomes a heat insulating layer, and the outlet portion of each exhaust port is isolated from the water-cooled chamber by the EGR chamber. Therefore, the heat transfer area between the exhaust gas and the cooling water in each exhaust port is greatly reduced, and the amount of heat taken by the cooling water in the water-cooled chamber from the exhaust gas discharged from each cylinder to the exhaust port is reduced.

  As a result, in an engine equipped with a turbocharger, under the same operating conditions, the turbine inlet temperature is maintained higher than before, improving the efficiency of turbine work, and the required compressor work with a small turbine expansion ratio. As a result, it is possible to reduce the pressure of the exhaust manifold, thereby reducing the pumping loss in the engine and improving the fuel consumption.

  Further, in an engine in which an exhaust purification catalyst (NOx occlusion reduction catalyst, selective reduction catalyst, oxidation catalyst, three-way catalyst, etc.) is interposed in the exhaust pipe, the temperature of the exhaust gas emitted from the engine is high. As a result, the catalyst bed temperature of the exhaust purification catalyst easily rises to the activation temperature, so that the operating range in which the exhaust purification catalyst functions effectively increases, and the exhaust gas can be efficiently purified.

  A part of the exhaust gas of each exhaust port flows into each EGR chamber from the outlet portion of each exhaust port, is collected from each EGR chamber into the EGR chamber for extraction, and is recirculated to the intake side. .

In this case, the EGR flow passage between the outer shell and the inner shell of the exhaust manifold becomes a heat insulating layer, and the exhaust gas in the exhaust manifold is isolated from the outside air by the EGR flow passage. The heat transfer area between the exhaust gas in the exhaust manifold and the outside air is greatly reduced, and the amount of heat taken by the outside air from the exhaust ports to the exhaust manifold is reduced.

  As a result, it is possible to further insulate the exhaust gas emitted from the engine. Therefore, in an engine equipped with a turbocharger, it is possible to further improve the fuel consumption, and the exhaust gas. It is also possible to further increase the operating range in which the exhaust gas purification catalyst in the middle of the pipe functions effectively and to purify the exhaust gas more efficiently.

In the present invention, the exhaust manifold and the EGR flow passage may be communicated with each other, and in this way, exhaust gas can be extracted from the exhaust manifold and recirculated to the intake side.

  According to the exhaust gas recirculation device of the present invention described above, it is possible to insulate the exhaust gas emitted from the engine by devising the flow path structure of the exhaust gas that is recirculated from the exhaust side to the intake side. Therefore, in an engine equipped with a turbocharger, the efficiency of the turbine work is improved so that the required compressor work can be obtained with a small turbine expansion ratio. By reducing the pressure of the exhaust manifold, the pumping loss of the engine can be reduced, and fuel consumption can be greatly improved. Furthermore, an exhaust purification catalyst (NOx occlusion) inserted in the middle of the exhaust pipe The catalyst bed temperature of the reduction catalyst, selective reduction catalyst, oxidation catalyst, three-way catalyst, etc.) can be easily raised to the activation temperature, so the exhaust purification catalyst is effective Thus, it is possible to obtain various excellent effects, such as increasing the operating region that can function to efficiently purify the exhaust gas.

It is the schematic which cuts off one part and shows an example of the form which implements this invention. It is sectional drawing of the II-II arrow of FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 and FIG. 2 show an example of an embodiment for carrying out the present invention. In the figure, 1 shows an engine which is a diesel engine. The engine 1 includes a turbocharger 2 and is led from an air cleaner (not shown). The intake air 3 is sent to the compressor 2 a of the turbocharger 2 through the intake pipe 4, the intake air 3 pressurized by the compressor 2 a is sent to the intercooler 5 to be cooled, and further from the intercooler 5 to the intake manifold 6. The intake air 3 is guided and distributed to each cylinder 7 of the engine 1.

  The exhaust gas 8 discharged from each cylinder 7 of the engine 1 is sent to the turbine 2b of the turbocharger 2 through the exhaust manifold 9, and the exhaust gas 8 driving the turbine 2b is sent through the exhaust pipe 10. It is designed to be discharged outside the vehicle.

  An EGR chamber 14 that isolates the outlet portion from the water cooling chamber 13 is formed around the outlet portion of each exhaust port 12 in the cylinder head 11 of the engine 1, and the EGR chamber 14 and the exhaust port 12 are separated from each other. The EGR chambers 14 adjacent to each other are communicated with each other via the communication path 16 and communicated with each other through the communication port 15.

  Further, the EGR chamber 14 'positioned at the end of the cylinders 7 in the arrangement direction is used as an extraction EGR chamber so that the exhaust gas 8 can be extracted to the communication pipe 17, while the exhaust manifold 9 has a double shell structure as the outer shell. An EGR flow passage 18 is formed between the inner shell and the inner shell, and the exhaust gas 8 extracted from the extraction EGR chamber 14 ′ can be introduced into the EGR flow passage 18 through the communication pipe 17. It is like that.

  Here, an EGR pipe 19 that guides the exhaust gas 8 in the EGR flow passage 18 to the intake pipe 4 in the vicinity of the intake manifold 6 is connected to the EGR flow passage 18 on the side opposite to the connection side of the communication pipe 17. The exhaust gas 8 extracted from the extraction EGR chamber 14 ′ can be guided to the EGR pipe 19 via the EGR flow passage 18.

  Here, the EGR pipe 19 is equipped with an EGR valve 20 for opening and closing the EGR pipe 19 as appropriate, and an EGR cooler 21 for cooling the recirculated exhaust gas 8, and the EGR cooler 21 Then, the temperature of the exhaust gas 8 can be lowered by heat exchange between the cooling water and the exhaust gas 8, and the combustion temperature is lowered by recirculation of the water-cooled exhaust gas 8 to the engine 1. To get.

  In the example shown here, the exhaust manifold 9 and the EGR flow passage 18 communicate with each other via a communication hole 22, and the exhaust gas 8 is extracted from the exhaust manifold 9 and recirculated to the intake side. It has come to be able to do.

  Thus, if the exhaust gas recirculation device is configured in this manner, the EGR chamber 14 around the outlet portion of each exhaust port 12 in the cylinder head 11 becomes a heat insulating layer, and the EGR chamber 14 causes the outlet of each exhaust port 12 to be exited. Since the portion is isolated from the water cooling chamber 13, the heat transfer area between the exhaust gas 8 in each exhaust port 12 and the cooling water is greatly reduced, and the exhaust gas discharged from each cylinder 7 to the exhaust port 12. The amount of heat 8 is lost to the cooling water in the water cooling chamber 13 is reduced.

  On the other hand, a part of the exhaust gas 8 of each exhaust port 12 flows from the outlet portion of each exhaust port 12 to each EGR chamber 14 and is collected from each EGR chamber 14 to the EGR chamber 14 ′ for extraction. It is recirculated to the intake side via the pipe 17, the EGR flow passage 18, and the EGR pipe 19.

  At this time, the EGR flow passage 18 between the outer shell and the inner shell of the exhaust manifold 9 becomes a heat insulating layer, and the exhaust gas 8 in the exhaust manifold 9 is isolated from the outside air by the EGR flow passage 18. The heat transfer area between the exhaust gas 8 in the exhaust manifold 9 and the outside air is greatly reduced, and the amount of heat taken by the outside air from the exhaust ports 12 to the exhaust manifold 9 is reduced.

  As a result, in the engine 1 in which the turbocharger 2 is mounted, the turbine 2b inlet temperature is maintained higher than the conventional temperature under the same operating condition, the efficiency of the turbine 2b work is improved, and the turbine 2b expansion ratio is low. Thus, the necessary work of the compressor 2a can be obtained, so that the pressure of the exhaust manifold 9 can be reduced, thereby reducing the pumping loss in the engine 1 and improving the fuel consumption.

  Further, in an engine 1 in which an exhaust purification catalyst (NOx storage reduction catalyst, selective reduction catalyst, oxidation catalyst, three-way catalyst, etc.) is interposed in the middle of the exhaust pipe 10, the exhaust gas 8 emitted from the engine 1 is used. As the temperature of the exhaust gas becomes high, the catalyst bed temperature of the exhaust purification catalyst easily rises to the activation temperature, so that the operating range in which the exhaust purification catalyst functions effectively increases and the exhaust gas 8 can be efficiently purified. Become.

  Therefore, according to the above embodiment, it is possible to insulate the exhaust gas 8 from the engine 1 by devising the flow path structure of the exhaust gas 8 that recirculates from the exhaust side to the intake side. Therefore, in the engine 1 in which the turbocharger 2 is mounted, the efficiency of the turbine 2b work is improved and the required compressor 2a work is achieved with a small expansion ratio of the turbine 2b. By reducing the pressure of the exhaust manifold 9, the pumping loss of the engine 1 can be reduced and the fuel consumption can be greatly improved. The catalyst bed temperature of the exhaust purification catalyst (NOx occlusion reduction catalyst, selective reduction catalyst, oxidation catalyst, three-way catalyst, etc.) can be easily raised to the active temperature. The exhaust gas 8 can be efficiently purified by increasing the operating range in which the exhaust purification catalyst functions effectively.

  Note that the exhaust gas recirculation device of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Engine 7 Cylinder 8 Exhaust gas 9 Exhaust manifold 11 Cylinder head 12 Exhaust port 13 Water cooling chamber 14 EGR chamber 14 'EGR chamber for extraction

Claims (2)

An exhaust gas recirculation device that extracts a part of exhaust gas from the exhaust side and recirculates it to the intake side, and isolates the outlet portion from the water cooling chamber around the outlet portion of each exhaust port in the cylinder head. An EGR chamber is formed, and the EGR chamber and the outlet portion of the exhaust port communicate with each cylinder and communicate with each other between the EGR chambers adjacent to each other. The chamber is an EGR chamber for extraction , the exhaust manifold has a double shell structure, an EGR flow passage is formed between the outer shell and the inner shell, and an end portion of the extraction EGR chamber and an end portion of the EGR flow passage Are connected by a connecting pipe, and the exhaust gas in the EGR flow path is guided to the intake pipe in the vicinity of the intake manifold on the side opposite to the connection side of the connecting pipe in the EGR flow path. Connect the EGR pipe, exhaust gas recirculation, characterized in that it has an exhaust gas taken out from the EGR chamber for the withdrawal to so that to recirculation to the intake side guided to the EGR pipe via the EGR passage apparatus. The exhaust gas recirculation device according to claim 1 , wherein the exhaust manifold and the EGR flow passage communicate with each other.

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