JP2012241671A - Exhaust gas reflux device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of sealing while reducing cost by reduction in assembly man-hours and reduction in the number of components in assembling an exhaust gas reflux device with an internal combustion engine.SOLUTION: An EGR device 15 provided in an internal combustion engine and serving as the exhaust gas reflux device which refluxes an exhaust gas to the downstream of a throttle valve of an intake system includes: an EGR valve serving as an exhaust gas reflux valve for controlling a flow rate of the exhaust gas to be refluxed; a valve case 22 for accommodating the EGR valve, and in addition directly connected to a surge tank 11 serving as an inlet manifold part of the intake system; and an exhaust gas cooler 23 serving as a duct for connecting the inside of the valve case 22 with an exhaust system. Such a constitution is employed, that a connecting surface 22b for connecting the valve case 22 with the surge tank 11 is parallel to a connecting surface 12a for connecting an intake manifold 10 including the surge tank 11 of the intake system with a cylinder head 1a.

Description

  The present invention relates to an exhaust gas recirculation device used for an internal combustion engine mounted on a vehicle or the like.

  2. Description of the Related Art Conventionally, an exhaust gas recirculation device that recirculates exhaust gas downstream of an intake system throttle valve houses an exhaust gas recirculation valve that adjusts the flow rate of the exhaust gas to be recirculated, and the exhaust system. A first pipe that connects the intake system and the exhaust gas cooler, and a valve case that is directly connected to the intake air collecting portion and an exhaust gas cooler that is provided upstream of the valve case and that is provided to cool the exhaust gas. A configuration has been adopted that includes a passage, a second pipe connecting the exhaust gas cooler and the exhaust gas recirculation valve, and a third pipe connecting the exhaust gas recirculation valve and the intake system.

  However, when such a configuration is adopted, a joint for attaching these pipes to both ends of each of the first to third pipes described above and a seal for preventing leakage of exhaust gas are required. A large number of parts and assembly man-hours are required, and the number of joints increases, so that there is a problem that reliability is lowered.

  As a method for reducing such inconveniences, it is considered that the exhaust system and the exhaust gas cooler are directly connected without passing through the pipeline, and that the exhaust gas recirculation valve and the intake system are also directly connected without going through the pipeline. (For example, see Patent Document 1). In the configuration described in Patent Document 1, a check valve is provided between the exhaust gas recirculation valve and the intake system, and between the exhaust gas recirculation valve and the check valve, and between the check valve and the intake system. There is no direct connection between the two.

  However, in the configuration described in Patent Document 1, since a pipe line still exists between the exhaust gas cooler and the exhaust gas recirculation valve, a joint is formed at a joint portion between the pipe line and the exhaust gas cooler or the exhaust gas recirculation valve. And a seal is required. Further, in the configuration described in Patent Document 1, when the exhaust gas recirculation device is attached, the exhaust gas recirculation device is provided downstream of the intake system and the exhaust gas recirculation valve. Since it is necessary to separately adjust the direction of the connecting portion between the check valve and the check valve, the reliability of the seal may be lowered from this point.

Japanese Patent No. 4171714

  The present invention pays attention to the above points, and an object of the present invention is to improve the reliability of the seal while reducing the cost by reducing the number of assembling steps and the number of parts when attaching the exhaust gas recirculation device to the internal combustion engine.

  That is, an exhaust gas recirculation device according to the present invention is an exhaust gas recirculation device that is provided in an internal combustion engine and recirculates exhaust gas downstream of an intake system throttle valve, and is an exhaust that adjusts the flow rate of the recirculated exhaust gas. A gas recirculation valve; a valve case that houses the exhaust gas recirculation valve and that is directly connected to an intake air collecting portion of the intake system; and an exhaust gas cooler that is a pipe connecting the inside of the valve case and the exhaust system. The connection surface connecting the valve case and the intake manifold portion of the intake system is parallel to the connection surface connecting the intake manifold portion of the intake system and the cylinder head.

  If this is the case, the exhaust system and the exhaust gas cooler, the exhaust gas cooler and the valve case, and the valve case and the intake system are connected without passing through the pipe. It is possible to reduce the number of mounting steps when the gas recirculation device is attached to the internal combustion engine and the number of parts of the exhaust gas recirculation device. Furthermore, since the connection surface connecting the valve case and the intake manifold portion of the intake system and the connection surface connecting the intake manifold portion of the intake system and the cylinder head are parallel, the accuracy of each connection surface can be easily managed. Therefore, the reliability of the exhaust gas seal can be improved, and the valve case can be used as a stay for supporting the intake manifold portion, so that the vibration of the intake manifold portion can be suppressed.

  In the present invention, the “connection surface connecting the intake manifold portion of the intake system and the cylinder head” is a concept including a connection surface connecting the intake manifold integrally provided with the intake manifold portion and the cylinder head. .

  According to the present invention, when the exhaust gas recirculation device is attached to the internal combustion engine, the reliability of the seal can be improved while reducing the cost by reducing the number of assembling steps and the number of parts.

1 is a diagram schematically showing an internal combustion engine according to an embodiment of the present invention. The top view which shows the principal part of the internal combustion engine which concerns on the same embodiment. The front view which shows the principal part of the internal combustion engine which concerns on the same embodiment. The side view which shows the principal part of the internal combustion engine which concerns on the same embodiment. The figure which shows schematically the internal combustion engine which concerns on other embodiment of this invention.

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

  An engine 100, which is an internal combustion engine according to the present embodiment, has two cylinders each provided with a combustion chamber therein and a cylinder head 1a that covers the upper part of each cylinder, as schematically shown in FIG. 1, an intake system 2 for supplying air to each cylinder of the engine body 1, an exhaust system 3 for exhausting exhaust gas from the engine body 1, and a turbine 5 and a turbine 5 driven by the exhaust gas And a turbocharger 4 having a compressor 6 connected by a rotating shaft. The intake system includes, in order from the upstream side, an air cleaner 7, a compressor 6, an intercooler 8 that cools the supercharged air discharged from the compressor 6, and a throttle valve 9 that controls the flow rate of the supercharged air supplied to the engine body 1. And an intake manifold 10 integrally having a surge tank 11 and a branch pipe 12 as an intake air collecting portion. On the other hand, the exhaust system includes an exhaust manifold 13, a turbine 5, and a three-way catalyst 14 in order from the upstream side. The upstream portion of the exhaust manifold 13 is formed in the cylinder head 1a. In addition, this engine 100 is an EGR device that is an exhaust gas recirculation device for recirculating a part of exhaust gas from the exhaust system exhaust manifold 13 to the downstream side of the intake system throttle valve 9 and mixing it with intake air. 15 is provided. 2 to 4, the engine body 1 is indicated by an imaginary line.

  As shown in FIGS. 1 to 4, the EGR device 15 houses an EGR valve 21, which is an exhaust gas recirculation valve for adjusting the flow rate of exhaust gas to be recirculated, and the EGR valve 21 and is directly connected to the surge tank 11. An exhaust gas cooler (EGR cooler) 23 which is a pipe connecting the inside of the valve case 22 and the exhaust manifold 13 of the exhaust system. And.

  As shown in FIG. 3, the EGR valve 21 is seated on a valve seat 22x formed in the valve case 22 and is closed from the valve seat 22x and fully opened to allow the exhaust gas to flow. A poppet valve movable between positions. The EGR valve 21 is driven by an actuator 22c attached to the valve case 22. The actuator 22c is an electromagnetic valve that drives the valve body of the EGR valve 21 by receiving a signal from an electronic control device (not shown) provided outside.

  As described above, as shown in FIG. 3, the valve case 22 houses the EGR valve 21 therein. As shown in FIGS. 2 and 3, one end of the valve case 22 is connected to the exhaust gas cooler 23, and the other end is connected to the surge tank 11 serving as an intake air collecting portion of the intake system. An exhaust gas flow passage 22a is provided. In the middle of the exhaust gas flow passage 22a, the valve seat 22x for seating the EGR valve 21 in the closed position is provided. Here, the portion 22a1 downstream of the valve seat 22x in the exhaust gas flow passage 22a is substantially flush with the central axis extending in the longitudinal direction of the surge tank 11, and intersects the longitudinal direction of the surge tank 11. Extending in the direction. As shown in FIG. 2, the connecting surface 22 b that connects the downstream end side of the exhaust gas flow passage 22 a and the surge tank 11 includes a branch pipe 12 that is provided integrally with the surge tank 11 and a cylinder head of the engine body 1. It is parallel to the connection surface 12a that connects 1a.

  As shown in FIGS. 2 and 3, the check valve 24 is integrally attached to the downstream end of the valve case 22. The check valve 24 is a plate-like member having an upstream end portion of intake air flow pivotally attached to the valve case 22 as a fixed end 24a and a downstream end portion being a free end. . Further, when the pressure in the surge tank 11 exceeds the pressure in the exhaust system exhaust manifold 13, the check valve 24 is urged toward the closed position where the free end contacts the valve case 22 due to the pressure difference. It is composed. The exhaust gas that has passed through the check valve 24 flows in a direction having an angle with respect to the flow of fresh air in the surge tank 11, and is introduced into each cylinder of the engine body 1 in a state of being mixed with fresh air. .

  As shown in FIGS. 2, 3, and 4, the exhaust gas cooler 23 is a pipe line having one end connected to the exhaust manifold 13 from the exhaust port and the other end connected to the valve case 22. . More specifically, an EGR gas passage is branched from the upstream portion of the exhaust manifold 13 in the cylinder head 1a, and an end portion of the EGR gas passage is open toward the outside of the cylinder head 1a. One end of the exhaust gas cooler 23 is connected to the opening of the EGR gas passage. The exhaust gas passes through the exhaust gas cooler 23 and is cooled by exchanging heat with the outside air. Further, in the present embodiment, in order to collect moisture generated by condensation of water vapor contained in the exhaust gas, the valve case 22 side, that is, the downstream side has an inclination higher than the exhaust system side, that is, the upstream side. In addition, the exhaust gas cooler 23 and the valve case 22 are coupled on a surface substantially orthogonal to the connection surface between the surge tank 11 and the valve case 22, and variations in relative positions of the surge tank 11 and the valve case 22 are reduced. The exhaust gas cooler 23 and the valve case 22 are absorbed at the connecting surface portion. And although illustration is abbreviate | omitted, the drain outlet for collect | recovering water | moisture contents is provided in the upstream. The drain port communicates with the surge tank 11 via a drain pipe (not shown).

  That is, a part of the exhaust gas discharged from the combustion chamber of one cylinder through the exhaust valve is led from the exhaust manifold 13 in the cylinder head 1 a to the exhaust gas cooler 23 of the EGR device 6 and circulates in the exhaust gas cooler 23. It is cooled by exchanging heat with the outside air. Then, the exhaust gas is guided into the valve case 22 and reaches the point just before the check valve 24 via the exhaust gas flow passage 22a in the valve case 22 when the EGR valve 21 is located at the open position. When the pressure in the surge tank 11 does not exceed the pressure in the exhaust manifold 13, the check valve 24 is opened due to the pressure difference, and the exhaust gas is introduced into the surge tank 11.

  As described above, according to the configuration of the EGR device 15 of the present embodiment, between the exhaust manifold 13 of the exhaust system and the exhaust gas cooler 23, between the exhaust gas cooler 23 and the valve case 22, and between the valve case 22 and Since the connection with the surge tank 11 of the intake system is not made through a special pipe line, the number of mounting steps and the number of parts when mounting the EGR device 6 can be reduced. Furthermore, the connection surface 22b for connecting the valve case 22 and the surge tank 11 and the connection surface 12a for connecting the branch pipe 12 provided integrally with the surge tank 11 and the cylinder head 1a of the engine body 1 are parallel to each other. Therefore, the accuracy of each of the connection surfaces 22b and 12a can be easily managed. Therefore, the reliability of the exhaust gas seal can be improved, and the valve case 22 is used as a stay for supporting the intake manifold 10 including the surge tank 11. Therefore, the vibration of the intake manifold 10 can be suppressed.

  The present invention is not limited to the embodiment described above.

  For example, an aspect described below with reference to FIG. 5 may be adopted as a connection aspect between the valve case and the surge tank. In the following description, parts corresponding to those according to the embodiment described above with reference to FIGS. 1 to 4 are given the same names, and A at the head of those according to the embodiment described above. The added code is attached.

  In this aspect, the exhaust gas flow passage in the valve case A22 extends in a direction intersecting with the surge tank A13 that is the intake manifold portion of the intake system, and is arranged so as to be offset from the longitudinal axis center of the surge tank A13. Yes.

  Exhaust gas that has passed through the exhaust gas flow passage is formed along the inner wall of the surge tank A13 when the pressure in the surge tank A13 does not exceed the pressure in the exhaust system and the check valve A24 is opened due to the pressure difference. It flows spirally and mixes with fresh air as it travels downstream.

  That is, even when this aspect is adopted, the exhaust gas and the fresh air can be mixed more uniformly as compared with the conventional configuration, and therefore the combustion stability can be improved.

  Further, the upstream edge of the exhaust gas cooler may be connected to the downstream side of the exhaust manifold, that is, the portion outside the cylinder head.

  In addition, various modifications may be made without departing from the spirit of the present invention.

11 ... Surge tank (intake air collecting part)
15 ... EGR device (exhaust gas recirculation device)
21 ... EGR valve (exhaust gas recirculation valve)
22 ... Valve case 23 ... Exhaust gas cooler 12a, 22b ... Connection surface

Claims (1)

An exhaust gas recirculation device that is provided in an internal combustion engine and recirculates exhaust gas downstream of an intake system throttle valve,
An exhaust gas recirculation valve that adjusts the flow rate of the exhaust gas to be recirculated, a valve case that houses this exhaust gas recirculation valve and that is directly connected to the intake manifold of the intake system, and connects the inside of the valve case and the exhaust system An exhaust gas cooler that is a pipe line to be
An exhaust gas recirculation device characterized in that a connection surface connecting the valve case and an intake manifold portion of the intake system is parallel to a connection surface connecting the intake manifold portion of the intake system and the cylinder head.

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