JP2010090771A - Exhaust gas recirculation device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation device for an internal combustion engine facilitating maintenance work at the time of inspection, replacement or the like of an intake manifold and an exhaust gas recirculation pipe. <P>SOLUTION: This device includes a synthetic resin intake manifold 26 including an intake passage 27 sucking air, an exhaust gas recirculation pipe 21 including the recirculation passage 22 recirculating exhaust gas to the intake passage 27, a metal insert nut 29 retained by the intake manifold 26, and a metal connecting bolt 36 screwed to the insertion nut 29, including an introduction hole 31 introducing exhaust gas to the intake passage 27 form the recirculation passage 22 by providing communication of the recirculation passage 22 and the intake passage 27, and connecting the intake manifold 26 and the exhaust gas recirculation pipe 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust gas recirculation device for an internal combustion engine that recirculates exhaust gas from a recirculation passage of an exhaust recirculation pipe to an intake passage of an intake manifold.

  2. Description of the Related Art Conventionally, an exhaust gas recirculation device for an internal combustion engine (hereinafter referred to as an EGR device) that reduces nitrogen oxides in the exhaust gas of the internal combustion engine by recirculating the exhaust gas to the intake passage is known. In this EGR device, the exhaust gas is returned to the intake passage of the intake manifold and mixed with the intake air in the intake passage.

  Recently, the intake manifold has been formed of a light material such as resin to reduce the weight of the internal combustion engine. However, when the high-temperature exhaust gas is recirculated through such an intake manifold, the intake manifold is exposed to the high-temperature exhaust gas at a portion connected to the exhaust recirculation pipe. For this reason, the intake manifold may be thermally deformed and the introduction hole at the connection portion between the exhaust gas recirculation pipe and the intake manifold may be deformed. Therefore, conventionally, an exhaust gas recirculation device has been proposed in which the structure of the connecting portion between the intake manifold and the exhaust recirculation pipe is improved to avoid thermal influence (see, for example, Patent Documents 1 to 5).

  An exhaust gas recirculation device described in Patent Document 1 includes a synthetic resin intake manifold body provided with an opening for attaching an EGR guide pipe, a metal EGR guide pipe, and a heat insulating seal member having a through hole. The EGR guide tube is attached to the EGR guide tube mounting opening by a seal member, and a part of the EGR guide tube is inserted into the intake manifold main body through a through hole provided in the seal member. The EGR gas is inserted into the intake manifold body where the EGR gas circulates in the intake manifold body. In this exhaust gas recirculation device, the EGR guide is attached to the EGR guide pipe mounting opening of the synthetic resin intake manifold main body by a heat-insulating sealing member, so that the synthetic resin intake manifold main body extends from the EGR guide pipe. Heat transfer is reduced and thermal deformation of the intake manifold made of synthetic resin is prevented.

  The exhaust gas recirculation device described in Patent Document 2 is provided with an EGR passage port forming portion at a collecting portion in a synthetic resin intake manifold having a collecting portion to which a plurality of individual intake passages and upstream end portions are connected. The EGR passage portion having a tip tubular portion protruding into the collecting portion is attached via a heat insulating material, and between the outer peripheral surface of the tip tubular portion and the portion surrounding the outer peripheral surface of the tip tubular portion in the EGR passage opening forming portion. A void is formed in the intake manifold to prevent thermal deformation of the synthetic resin intake manifold.

  In the exhaust gas recirculation device described in Patent Document 3, an exhaust gas pipe is connected to an opening of a synthetic resin intake manifold via a connector, and the exhaust gas pipe is recirculated by increasing the tip of the exhaust gas pipe. The exhaust gas expands suddenly at the tip of the large diameter and lowers the temperature. For this reason, the amount of heat transmitted from the connector to the attachment portion of the intake manifold is reduced, so that there is almost no thermal influence, and thermal deformation of the intake manifold made of synthetic resin is prevented.

  In the exhaust gas recirculation device described in Patent Document 4, an exhaust gas pipe is connected to an opening of a synthetic resin intake manifold via a connector, and the connector is fixed to the intake manifold with a bolt and is close to the exhaust gas pipe. Thus, heat radiation fins are formed. The heat of the exhaust gas is transmitted from the exhaust gas pipe to the connector, but is released into the intake air by the heat radiating fin, and the thermal influence is reduced at the connection portion with the intake manifold on the outer periphery of the connector, so that the intake made of synthetic resin The thermal deformation of the manifold can be prevented.

In the exhaust gas recirculation device described in Patent Document 5, a metallic cooling housing is interposed between a synthetic resin intake manifold and an exhaust recirculation control valve, and cooling water is passed through a cooling water passage in the cooling housing. Let it flow. By introducing high-temperature exhaust gas through the exhaust discharge pipe so that it does not come into contact with the inner peripheral surface of the exhaust introduction hole, the thermal influence of the synthetic resin intake manifold is reduced, and thermal deformation of the synthetic resin intake manifold is reduced. Can be prevented.
JP 2000-161161 A Japanese Utility Model Publication No. 05-024937 Japanese Patent Application Laid-Open No. 08-021315 Japanese Patent Application Laid-Open No. 08-021316 JP-A-10-089160

  As described above, the conventional exhaust gas recirculation devices described in Patent Documents 1 to 5 can prevent the thermal influence of the intake manifold made of synthetic resin and prevent its thermal deformation. However, since the connection structure between the intake manifold and the exhaust gas recirculation pipe is complicated, the workability of maintenance work during inspection and replacement of the intake manifold and the exhaust gas recirculation pipe deteriorates. was there.

  The present invention has been made in order to solve the above-described conventional problems. The intake manifold and the exhaust gas recirculation pipe have a simple structure while stabilizing the flow rate of the exhaust gas recirculated from the exhaust gas recirculation pipe to the intake manifold. It is an object of the present invention to provide an exhaust gas recirculation device for an internal combustion engine that can be easily connected to the intake manifold and the exhaust recirculation pipe so that maintenance work such as inspection and replacement can be performed. It is.

  In order to achieve the above object, an exhaust gas recirculation device for an internal combustion engine according to the present invention is an exhaust manifold having a synthetic resin intake manifold having a suction passage for sucking air and a recirculation passage for returning exhaust gas to the suction passage. In the exhaust gas recirculation apparatus for an internal combustion engine including a recirculation pipe, a metal insert nut held by the intake manifold, and a threaded engagement with the insert nut, and the recirculation passage and the suction passage communicate with each other. The intake passage has an introduction hole for introducing exhaust gas into the intake passage, and includes a metal connection bolt that connects the intake manifold and the exhaust gas recirculation pipe.

  With this configuration, an introduction hole for introducing exhaust gas from the return passage of the exhaust return pipe to the intake passage of the intake manifold is provided in the metal connection bolt, and the connection bolt is held in the intake manifold and is made of a metal insert nut. Therefore, the introduction hole can be prevented from being thermally deformed, and the flow rate of the exhaust gas recirculated from the exhaust recirculation pipe to the intake manifold can be stabilized.

  In addition, since the exhaust gas recirculation pipe and intake manifold are connected by a bolt having an exhaust gas introduction hole, the exhaust gas recirculation pipe and intake manifold can be easily disassembled and assembled, and the exhaust gas recirculation pipe and intake manifold can be inspected. Maintenance work such as time or replacement can be easily performed.

  Furthermore, since the introduction hole of the passage for introducing the exhaust gas from the exhaust gas recirculation pipe to the intake manifold is provided in the metal connection bolt, when deposits adhere to the connection bolt and the circulation of the exhaust gas becomes insufficient In addition, it is possible to easily ensure the flow of the exhaust gas by exchanging the connecting bolts.

  According to the present invention, the intake manifold and the exhaust gas recirculation are configured so that the intake manifold and the exhaust gas recirculation pipe can be connected with a simple structure while stabilizing the flow rate of the exhaust gas recirculated from the exhaust gas recirculation pipe to the intake manifold. It is possible to provide an exhaust gas recirculation device for an internal combustion engine that can easily perform maintenance work such as pipe inspection and replacement.

Embodiments of an exhaust gas recirculation device for an internal combustion engine according to the present invention will be described below with reference to the drawings.
1 and 2 are views showing an embodiment of an exhaust gas recirculation device for an internal combustion engine according to the present invention.

First, the configuration will be described.
FIG. 1 is a schematic configuration diagram of a four-cylinder gasoline engine equipped with an exhaust gas recirculation device. Here, intake air (shown by arrows in the drawing) taken from an air cleaner (not shown) is taken into the intake pipe 12 and introduced into the throttle body 14. In the throttle body 14, after the intake air is adjusted by the internal throttle valve 16, the intake air flows into the intake manifold 26.

Further, exhaust gas (hereinafter simply referred to as EGR gas) is introduced from the exhaust manifold 24 to the intake manifold 26 via the recirculation passage 22 in the exhaust recirculation pipe 21 according to the operating state of the engine 20.
The intake air that has flowed into the intake manifold 26 is introduced into the cylinders 20a, 20b, 20c, and 20d of the engine 20 via the surge tank 28.

  In each cylinder 20a-20d, an air-fuel mixture is formed by injecting fuel directly into the cylinders 20a-20d from a fuel injection valve (not shown). Next, the air-fuel mixture is ignited by a spark plug (not shown) to generate rotational torque in the engine 20.

  Exhaust gas after combustion is discharged from the cylinders 20a to 20d as indicated by arrows, collected in the exhaust manifold 24, and discharged through a three-way catalyst, a muffler, etc. (not shown). A part of the exhaust gas becomes EGR gas as described above and is returned to the intake manifold 26 through the recirculation passage 22 of the exhaust recirculation pipe 21.

  An exhaust gas recirculation valve (hereinafter referred to as EGR valve) 30 is disposed in the recirculation passage 22. The opening degree of the EGR valve 30 is determined by an electronic control unit (hereinafter referred to as an ECU) 32 that controls the operating state of the engine 20 by various sensors (not shown) according to the operating state of the engine 20. It is controlled to be (the ratio of exhaust gas in the intake air).

  The part 22a of the recirculation passage 22 also serves as a part of the intake air bypass circuit 34 that bypasses the throttle valve 16 for idle speed control. The intake air bypass circuit 34 is provided with an idle speed control valve 35. When the engine 20 is in an idle state, the opening degree is adjusted by the ECU 32 to control the rotational speed of the engine 20 during idling.

  The throttle body 14 is made of metal, for example, mainly aluminum or aluminum alloy, and the intake manifold 26 is made of synthetic resin.

  Next, a detailed configuration of the exhaust gas recirculation device will be described. FIG. 2 shows a cross-sectional view of the connecting portion 18 between the intake manifold 26 and the exhaust gas recirculation pipe 21. The exhaust gas recirculation device includes an intake manifold 26 and an exhaust recirculation pipe 21.

  The intake manifold 26 has a suction passage 27 for sucking air, and the exhaust recirculation pipe 21 has a recirculation passage 22 for recirculating EGR gas in the suction passage 27. The intake manifold 26 made of synthetic resin has a cylindrical protrusion 26a protruding radially outward, and a metal insert nut 29 is inserted and held in the protrusion 26a.

  For example, the metal insert nut 29 may be held such that a screw is formed on the outer side of the insert nut 29 and a screw is also formed on the protruding portion 26a, and the insert nut 29 is screwed to the protruding portion 26a. Good. In addition to the screw connection between the insert nut 29 and the protruding portion 26a, the insert nut 29 and the protruding portion 26a may be joined together with an adhesive, and any other means that connects the insert nut 29 and the protruding portion 26a. It may be a coupling means.

  A screw is formed on the inner side of the insert nut 29, and a tip end portion of a metal stud bolt 36 is screwed into the insert nut 29. The stud bolt 36 has an introduction hole 31 through which the recirculation passage 22 and the suction passage 27 are communicated to introduce EGR gas from the recirculation passage 22 to the intake passage 27, and connects the intake manifold 26 and the exhaust recirculation pipe 21. The metal connecting bolt in the present invention is constituted.

  A bolt insertion hole 21b is formed at the tip of the exhaust gas recirculation pipe 21 close to the intake manifold 26. When the exhaust gas recirculation pipe 21 is connected to the intake manifold 26, the stud bolt 36 is inserted into the bolt insertion hole 21b. Then, the exhaust gas recirculation pipe 21 and the intake manifold 26 are connected to each other by being screwed into the insert nut 29.

  That is, when the exhaust gas recirculation pipe 21 and the intake manifold 26 are connected, the recirculation passage 22 and the suction passage 27 communicate with each other so that EGR gas can be introduced from the recirculation passage 22 into the suction passage 27 through the introduction hole 31. It has become. The rear end portion of the stud bolt 36 is tightened by a tightening nut 37 and firmly connects the exhaust gas recirculation pipe 21 and the intake manifold 26.

  As described above, in the present embodiment, the exhaust recirculation pipe 21 and the intake manifold 26 are connected by the stud bolt 36, so that hot EGR gas passes through the introduction hole 31 in the recirculation passage 22 of the exhaust recirculation pipe 21. Even if it is returned to the suction passage 27, since the insert nut 29 and the stud bolt 36 are made of metal, deformation of the introduction hole 31 is suppressed, and the inner diameter thereof does not change over time. Therefore, the gas flow rate through the introduction hole 31 can be stabilized.

  Further, in the present embodiment, the exhaust gas recirculation pipe 21 and the intake manifold 26 are connected by the stud bolt 36 having the introduction hole 31, so that the exhaust gas recirculation pipe 21 and the intake manifold 26 can be connected by a simple structure. it can.

  When it is necessary to perform maintenance such as inspection and replacement between the exhaust gas recirculation pipe 21 and the intake manifold 26, the exhaust bolts can be attached to and removed from the exhaust gas recirculation pipe 21 and the intake manifold 26. 21 and the intake manifold 26 can be easily disassembled and assembled, so that the maintenance work of the exhaust gas recirculation pipe 21 and the intake manifold 26 can be easily performed.

  Further, in the present embodiment, since the introduction hole of the passage for introducing the EGR gas from the exhaust gas recirculation pipe 21 to the intake manifold 26 is provided in the metal stud bolt 36, deposits adhere to the stud bolt 36. When the circulation of the EGR gas becomes insufficient, the circulation of the EGR gas can be easily ensured by replacing the stud bolt 36.

  In addition, as for the front-end | tip part and rear-end part of the stud bolt 36 screwed together with the insert nut 29 and the fastening nut 37, the screw from which a pitch differs may be formed, respectively, and the screw with an equal pitch may be formed.

  The embodiment disclosed this time is illustrative in all respects and is not limited to this embodiment. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims for patent.

  As described above, the exhaust gas recirculation apparatus for an internal combustion engine according to the present invention has an effect that maintenance work such as inspection and replacement of the intake manifold and the exhaust gas recirculation pipe can be easily performed. This is useful as an exhaust gas recirculation device for an internal combustion engine that recirculates exhaust gas from the recirculation passage to the intake passage of the intake manifold.

1 is a diagram showing an embodiment of an exhaust gas recirculation device for an internal combustion engine according to the present invention, and is a schematic diagram of a gasoline engine provided with the exhaust gas recirculation device. 1 is a view showing an embodiment of an exhaust gas recirculation device for an internal combustion engine according to the present invention, and is a cross-sectional view of the exhaust gas recirculation device.

Explanation of symbols

21 Exhaust recirculation pipe 22 Recirculation passage 26 Intake manifold 27 Suction passage 29 Insert nut 31 Introduction hole 36 Stud bolt (connection bolt)

Claims (1)

An intake manifold made of synthetic resin having a suction passage for sucking air;
In an exhaust gas recirculation apparatus for an internal combustion engine comprising an exhaust gas recirculation pipe having a recirculation passage for recirculating exhaust gas in the suction passage,
A metal insert nut held in the intake manifold;
A metal threadedly engaged with the insert nut, having an introduction hole for introducing the exhaust gas from the return passage to the intake passage through the return passage and the intake passage, and connecting the intake manifold and the exhaust return pipe An exhaust gas recirculation device for an internal combustion engine, comprising: a connecting bolt made of metal.

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