WO2022102561A1

WO2022102561A1 - Egr device

Info

Publication number: WO2022102561A1
Application number: PCT/JP2021/040937
Authority: WO
Inventors: 衛吉岡; 伸二河井; 海翔曹
Original assignee: 愛三工業株式会社
Priority date: 2020-11-13
Filing date: 2021-11-08
Publication date: 2022-05-19
Also published as: JPWO2022102561A1

Abstract

This EGR device has an EGR passage provided with: an EGR cooler (13) for cooling an EGR gas; a bypass passage (21g) for bypassing the EGR cooler (13); a bypass valve (24) for opening/closing the bypass passage (21g); an EGR valve (14) for adjusting the flow rate of the EGR gas; a pipe (16); and an EGR gas distributor (15). The EGR cooler (13) and the bypass passage (21g) constitute an upstream passage portion of the EGR passage, the EGR valve (14) and the pipe (16) constitute a midstream passage portion thereof, and the EGR gas distributor (15) constitutes a downstream passage portion thereof. The inner wall of a flow path (34) of the EGR valve (14) and the inner wall of the pipe (16) are provided with a thermal barrier coating (41) serving as a heat insulating means for maintaining the temperature of the EGR gas flowing therein.

Description

EGR device

The technique disclosed in this specification relates to an EGR device configured to flow a part of the exhaust gas discharged from the engine to the exhaust passage as EGR gas to the intake passage through the EGR passage and return it to the engine.

Conventionally, as this kind of technique, for example, the EGR apparatus described in Patent Document 1 below is known. In this EGR device, an EGR cooler and an EGR valve are provided in the EGR passage, and an electronic control unit (ECU) controls the EGR valve to the required opening degree based on the engine rotation speed and the engine load. .. Further, in this EGR device, in order to prevent a malfunction caused by the EGR gas cooled by the EGR cooler being returned to the combustion chamber of the engine before the engine warms up, the ECU determines at least one of the intake air temperature and the EGR gas temperature. When one of them is lower than the set value, the EGR valve is controlled to have an opening degree smaller than the required opening degree. This control prevents a large amount of EGR gas, which has not been heated to a predetermined temperature, from flowing into the combustion chamber. Further, even before the engine is warmed up, the EGR passage is warmed by flowing a certain amount of EGR gas through the EGR passage.

Japanese Unexamined Patent Publication No. 2014-125974

However, in the EGR apparatus described in Patent Document 1, although the EGR passage is warmed by flowing the EGR gas through the EGR passage even before the engine is warmed up, the EGR gas temperature is lowered by receiving heat from the EGR gas in the EGR passage. Therefore, the warm-up effect of the EGR gas is reduced toward the downstream side (downstream passage portion) of the EGR passage, and it is not possible to sufficiently warm the EGR passage. Therefore, there is a possibility that condensed water is generated in the downstream passage portion of the EGR passage (for example, the EGR gas distributor at the final stage).

This disclosed technique has been made in view of the above circumstances, and its purpose is to suppress a decrease in temperature of EGR gas flowing to a downstream passage portion of the EGR passage and to suppress generation of condensed water in the downstream passage portion. The purpose is to provide an EGR device that makes it possible.

(1) In order to achieve the above object, an embodiment of the present invention is configured such that a part of the exhaust gas discharged from the engine to the exhaust passage is made into EGR gas and flows to the intake passage through the EGR passage and is returned to the engine. In the EGR device, the EGR passage is provided with an EGR valve for adjusting the flow rate of the EGR gas, and the EGR passage includes an upstream passage portion near the exhaust passage, a downstream passage portion near the intake passage, and an upper flow. It is intended that at least the most downstream portion of the middle flow passage portion, including the middle flow passage portion between the road portion and the downstream passage portion, is provided with a heat insulating means for keeping the EGR gas flowing there. ..

According to the configuration of (1) above, a heat insulating means for keeping the EGR gas flowing there is provided at least in the most downstream part of the middle flow passage portion of the EGR passage. Therefore, the heat of the EGR gas flowing from the upstream passage portion to the middle flow passage portion of the EGR passage is difficult to be transmitted to the outside by the heat insulating means, and flows to the downstream passage portion in a state where the EGR gas is kept warm.

(2) In order to achieve the above object, in the above configuration (1), it is preferable that the heat insulating means is formed by forming the middle flow passage portion with a resin material having a function of retaining heat of EGR gas. ..

According to the configuration of (2) above, in addition to the action of the configuration of (1) above, the heat insulating means is configured by forming the middle flow passage portion with a resin material having a function of retaining heat of EGR gas. , The heat retaining property can be obtained in the middle flow passage portion itself, and it is not necessary to separately provide a heat insulating means.

(3) In order to achieve the above object, in the above configuration (1) or (2), the heat insulating means is preferably a heat insulating coat provided on the inner wall of the middle flow passage portion.

According to the configuration of (3) above, in addition to the action of the configuration of (1) or (2) above, the heat insulating means is a heat insulating coat provided on the inner wall of the middle flow passage portion, so that the inner wall of the middle flow passage portion is provided. It becomes easy to form a heat insulating means for the warmth.

(4) In order to achieve the above object, in the configuration of (3) above, the middle flow passage portion includes a pipe made of a resin material having a function of retaining heat of EGR gas, and the heat insulating coat has a thickness thereof. Is preferably formed so as to gradually or gradually increase from the downstream side to the upstream side of the pipe.

According to the configuration of the above (4), in addition to the action of the configuration of the above (3), the heat insulating coat is formed so that its thickness gradually or gradually increases from the downstream side to the upstream side of the pipe. Here, the temperature of the EGR gas flowing through the pipe is high on the upstream side of the pipe and decreases toward the downstream side. Therefore, the heat insulating property of the pipe is set according to the temperature change of the EGR gas flowing therein from the upstream side to the downstream side.

(5) In order to achieve the above object, in any of the above configurations (1) to (4), the heat insulating means is preferably an air layer provided outside the middle flow passage portion.

According to the configuration of (5) above, in addition to the action of any of the configurations (1) to (4) above, since the heat insulating means is an air layer, it is necessary to use a special member for the heat insulating means. not.

(6) In order to achieve the above object, in any of the above configurations (1) to (5), it is preferable that the heat insulating means includes a heating portion for heating the middle flow passage portion.

According to the configuration of the above (6), in addition to the action of the configuration of any one of the above (1) to (5), since the heat insulating means includes the heating portion, the middle flow passage portion is heated by the heating portion. Therefore, both heat retention and temperature rise are possible.

(7) In order to achieve the above object, in the configuration of the above (6), it is preferable that the heating portion is a heat-generating film that generates heat by energization.

According to the configuration of the above (7), in addition to the action of the configuration of the above (6), the heat generating film is heated by energization, so that the middle flow passage portion is widely heated in terms of surface at an arbitrary timing.

(8) In order to achieve the above object, in the configuration of (6) above, it is preferable that the heating portion is formed in at least a part of the middle flow passage portion and is composed of a hot water passage through which hot water flows.

According to the configuration of the above technique (8), in addition to the action of the configuration of the above (6), since the heating unit is composed of the hot water passage through which the hot water flows, the engine cooling water warmed by cooling the engine can be used. It can be used as hot water and flowed into a hot water passage.

(9) In order to achieve the above object, in the configuration of the above (8), the middle flow passage portion provided with the hot water passage includes an outer outer pipe and an inner inner pipe sandwiching the hot water passage, and is an outer pipe. It is preferable that the thickness of the inner tube is larger than the thickness of the inner tube.

According to the configuration of the above (9), in addition to the action of the configuration of the above (8), in the middle flow passage portion, the thickness of the outer pipe sandwiching the hot water passage is larger than the thickness of the inner pipe, so that the heat of the hot water is generated. It is easily transmitted to the inner wall of the inner pipe and difficult to escape to the outer wall of the outer pipe.

(10) In order to achieve the above object, in the configuration of the above (8) or (9), it is preferable that the hot water passage is provided along the flow path longitudinal direction of the middle flow passage portion.

According to the configuration of the above (10), in addition to the action of the configuration of the above (8) or (9), since the hot water passage is provided along the flow path longitudinal direction of the middle flow passage portion, in the middle flow passage portion. The EGR gas is warmed for a long time along the flow of the EGR gas.

(11) In order to achieve the above object, in the configuration of the above (8) or (9), the middle flow passage portion includes the EGR valve and the pipe arranged downstream from the EGR valve, and the EGR valve and the pipe. Is connected via a valve outlet flange provided on the outlet side of the EGR valve and a pipe inlet flange provided on the inlet side of the pipe, and the pipe and the downstream passage portion are connected to the pipe outlet provided on the outlet side of the pipe. It is connected via a flange and a passage inlet flange provided on the inlet side of the downstream passage portion, and a spacer is provided between the valve outlet flange and the pipe inlet flange and between the pipe outlet flange and the passage portion inlet flange. It is preferable that the hot water passage is provided along the circumferential direction of the spacer.

According to the configuration of (11) above, in addition to the operation of the configuration of (8) or (9) above, at least between the valve outlet flange and the pipe inlet flange and between the pipe outlet flange and the passage portion inlet flange. A hot water passage is provided along the circumferential direction of the spacer provided sandwiched between them. Therefore, at least one of the EGR gas flowing through the valve outlet flange and the pipe inlet flange and the EGR gas flowing through the pipe outlet flange and the passage portion inlet flange is warmed by the hot water in the hot water passage along the circumferential direction of the spacer.

(12) In order to achieve the above object, it is preferable that the hot water passage is composed of a metal pipe provided along the longitudinal direction of the flow path of the middle flow passage portion in the configuration of the above (8).

According to the configuration of the above (12), in addition to the action of the configuration of the above (8), since the hot water passage is composed of the metal pipe provided along the longitudinal direction of the flow path of the middle flow passage portion, the hot water passage is formed. It is more advantageous than the resin material against cracks caused by disturbance.

(13) In order to achieve the above object, in the above configuration (12), it is preferable that the metal pipe is fixed to the middle flow passage portion by insert molding.

According to the configuration of the above (13), in addition to the action of the configuration of the above (12), since the metal pipe is fixed to the middle flow passage portion by insert molding, the adhesion to the middle flow passage portion of the metal pipe is good. Therefore, the contact area between the metal pipe and the middle flow passage portion becomes large. Further, depending on the specifications of insert molding, it is possible to prevent the metal pipe from being exposed from the inner wall of the midstream passage portion.

(14) In order to achieve the above object, in the configuration of the above (12), the middle flow passage portion is provided with a holding means for holding the metal pipe along the longitudinal direction of the flow path, and the metal pipe is provided with a holding means. , It is preferable that the metal is fixed to the middle flow passage portion by being held by the holding means.

According to the configuration of the above (14), in addition to the action of the configuration of the above (12), the metal pipe is fixed by being held by the holding means along the longitudinal direction of the flow path of the middle flow passage portion. In terms of resin cracks due to the difference in thermal expansion between the resin middle flow passage portion and the metal pipe and the manufacturing cost, it is superior to fixing the metal pipe to the middle flow passage portion by insert molding.

(15) In order to achieve the above object, it is preferable to provide a heat transfer member between the metal pipe held by the holding means and the middle flow passage portion in the configuration of the above (14).

According to the configuration of the above (15), in addition to the action of the configuration of the above (14), a heat transfer member is provided between the metal pipe held by the holding means and the middle flow passage portion, so that the metal pipe is provided. There is no gap between the pipe and the midstream passage, and the adhesion between the two is improved.

(16) In order to achieve the above object, in the configuration of the above (15), the heat transfer member is a flexible heat transfer sheet that is in close contact with the metal pipe and the middle flow passage portion.

According to the configuration of the above (16), in addition to the action of the configuration of the above (15), even if a thermal expansion difference occurs between the metal pipe and the middle flow passage portion due to the flexibility of the heat transfer sheet, the metal pipe and Adhesion between the midstream passage and the heat transfer sheet is ensured.

(17) In order to achieve the above object, in any of the above configurations (14) to (16), it is intended that an air layer for heat insulation is provided between the metal pipe and the holding means.

According to the configuration of (17) above, in addition to the action of any of the configurations (14) to (16) above, an air layer for heat insulation is provided between the metal pipe and the holding means, so that the metal pipe is provided. The escape of heat from the air to the atmosphere is suppressed by the air layer.

(18) In order to achieve the above object, in any of the above configurations (2) to (17), the EGR passage has an EGR cooler for cooling the EGR gas and a bypass for bypassing the EGR cooler. A passage and a bypass valve for opening and closing the bypass passage are further provided, the EGR cooler includes a heat exchanger for cooling, the heat exchanger includes an inlet and an outlet for EGR gas, and the bypass passage includes an EGR. It is preferred that the midstream passage is located downstream of the heat exchanger outlet and the bypass passage outlet, including the gas inlet and outlet, and the EGR valve is provided in the midstream passage.

According to the configuration of (18) above, in addition to the action of any of the configurations (2) to (17) above, the middle flow passage portion is located downstream from the outlet of the heat exchanger and the outlet of the bypass passage, and is in the middle. Since the EGR valve is provided in the flow passage portion, the EGR gas flowing through the EGR valve and the middle flow passage portion flows to the downstream passage portion in a state of being kept warm by the heat insulating means.

(19) In order to achieve the above object, it is preferable that a cooling unit for cooling at least a part of the bypass passage is further provided in the configuration of the above (17) or (18).

According to the configuration of the above (19), in addition to the action of the configuration of the above (17) or (18), the EGR gas flowing through the bypass passage is cooled by the cooling portion, so that the EGR gas flows from the bypass passage to the middle flow passage portion. The temperature of the EGR gas drops.

(20) In order to achieve the above object, in any of the above configurations (2) to (17), the EGR passage is further provided with an EGR cooler for cooling the EGR gas, and the EGR cooler is cooled. The heat exchanger includes an inlet and an outlet for EGR gas, the middle flow passage portion is located downstream from the outlet of the heat exchanger, and the EGR valve is provided in the middle flow passage portion. Is preferable.

According to the configuration of (20) above, in addition to the action of any of the configurations (2) to (17) above, the middle flow passage portion is located downstream from the outlet of the heat exchanger, and the EGR is located in the middle flow passage portion. Since the valve is provided, the EGR gas flowing through the EGR valve and the middle flow passage portion flows to the downstream passage portion in a state of being kept warm by the heat insulating means.

(21) In order to achieve the above object, in any of the above configurations (1) to (20), the EGR valve includes a flow path through which the EGR gas flows, and the inner wall of the flow path has a function of retaining heat of the EGR gas. It is preferable that it is composed of a resin material having.

According to the configuration of (21) above, in addition to the action of any of the configurations (1) to (20) above, the flow path of the EGR valve is composed of a resin material having a function of retaining heat of the EGR gas. Heat retention is obtained in the flow path itself, and molding of the flow path becomes easy.

(22) In order to achieve the above object, in any of the configurations (16) to (21) above, the flow path of the EGR valve includes an inlet and an outlet, and the inlet of the flow path becomes the outlet of the heat exchanger. It is preferable that they are arranged substantially adjacent to each other.

According to the configuration of (22) above, in addition to the operation of any of the configurations (16) to (21) above, the inlet of the flow path of the EGR valve is arranged substantially adjacent to the outlet of the heat exchanger. The EGR gas that has just flowed out from the outlet of the heat exchanger flows into the inlet of the resin flow path of the EGR valve at an early stage.

According to the configuration of (1) above, the heat transfer of the EGR gas to the middle flow passage portion can be reduced, the temperature drop of the EGR gas flowing to the downstream passage portion can be suppressed, and the downstream passage portion thereof can be suppressed. It is possible to suppress the generation of condensed water in.

According to the configuration of (2) above, in addition to the effect of the configuration of (1) above, it is possible to facilitate the manufacture of an EGR device provided with heat insulating means.

According to the configuration of (3) above, in addition to the effect of the configuration of (1) or (2) above, it is possible to facilitate the manufacture of an EGR device provided with heat insulating means.

According to the configuration of (4) above, in addition to the effect of the configuration of (3) above, the EGR gas can be effectively kept warm from the upstream side to the downstream side of the pipe according to the temperature change of the EGR gas flowing through the pipe. The heat resistance of the piping can be effectively secured.

According to the configuration of (5) above, in addition to the effect of any of the configurations (1) to (3) above, the number of parts constituting the EGR device can be reduced by the amount of the heat insulating means.

According to the configuration of (6) above, in addition to the effect of the configuration of (1) or (2) above, the EGR gas flowing through the middle flow passage portion can be effectively kept warm.

According to the configuration of (7) above, in addition to the effect of the configuration of (6) above, the EGR gas flowing through the middle flow passage portion can be responsively and stably kept warm.

According to the configuration of (8) above, in addition to the effect of the configuration of (6) above, heating can be performed without using the electrical configuration. Further, even if the flow of EGR gas in the middle flow passage is stopped, the heating of the middle flow passage is continued by the hot water in the hot water passage, so that when the EGR gas flows again in the middle flow passage, the middle flow is performed. The generation of condensed water in the road can be suppressed.

According to the configuration of (9) above, in addition to the effect of the configuration of (8) above, the heatability and heat retention of the EGR gas flowing inside the inner pipe can be enhanced.

According to the configuration of (10) above, in addition to the effect of the configuration of (8) or (9) above, the heatability and heat retention of the EGR gas flowing through the middle flow passage portion can be further enhanced.

According to the configuration of (11) above, in addition to the effect of the configuration of (8) or (9) above, the EGR gas flowing through the portion of the middle flow passage portion adjacent to the spacer can be effectively kept warm.

According to the configuration of (12) above, in addition to the effect of the configuration of (8) above, the durability as a hot water passage can be enhanced.

According to the configuration of the above (13), in addition to the effect of the configuration of the above (12), it is possible to enhance the heatability and heat retention of the EGR gas flowing through the middle flow passage portion by the hot water of the hot water passage. Further, since the metal pipe is not exposed from the inner wall of the middle flow passage portion, it is possible to prevent the metal pipe from being corroded by the condensed water.

According to the configuration of (14) above, in addition to the effect of the configuration of (12) above, it is possible to extend the metal pipe and improve the degree of freedom in design.

According to the configuration of (15) above, in addition to the effect of the configuration of (14) above, the heat transfer property of the hot water flowing through the hot water passage in the metal pipe to the inner wall of the middle flow passage portion can be improved. It is possible to improve the temperature rise property of the inner wall, and it is possible to improve the temperature rise property of the EGR gas flowing inside the middle flow passage portion.

According to the configuration of the above (16), in addition to the effect of the configuration of the above (15), the heat transfer property of the hot water flowing through the hot water passage to the inner wall of the middle flow passage portion can be further improved, and the temperature of the inner wall thereof is raised. The property can be further improved, and the temperature rise property of the EGR gas flowing inside the middle flow passage portion can be further improved.

According to the configuration of (17) above, in addition to the effect of any of the configurations (14) to (16) above, it is possible to suppress a decrease in temperature of the inner wall of the middle flow passage portion.

According to the configuration of (18) above, in addition to the effect of any of the configurations (2) to (17) above, the temperature of the EGR gas can be lowered by the heat exchanger, and the EGR gas in the middle flow passage portion can be lowered. It is possible to suppress the melting damage due to.

According to the configuration of the above (19), in addition to the effect of the configuration of the above (17) or (18), the temperature of the EGR gas can be brought close to the heat resistant temperature of the resin constituting the middle flow passage portion, and the bypass passage can be provided. Even if the high temperature EGR gas flows, it is possible to suppress the melting damage of the middle flow passage portion due to the EGR gas.

According to the configuration of (20) above, in addition to the effect of any of the configurations (2) to (17) above, the temperature of the EGR gas can be lowered by the heat exchanger, and the EGR gas in the middle flow passage portion can be lowered. It is possible to suppress the melting damage due to.

According to the configuration of the above (21), in addition to the effect of the configuration of any one of the above (1) to (20), it is possible to facilitate the suppression of the temperature decrease of the EGR gas in the EGR valve.

According to the configuration of (22) above, in addition to the effect of any of the configurations (16) to (21) above, the temperature drop of the EGR gas that has just flowed out from the outlet of the heat exchanger is suppressed by the flow path of the EGR valve. can do.

A schematic configuration diagram showing an engine system according to the first embodiment. FIG. 6 is a configuration diagram showing a specific configuration on an EGR passage from an EGR cooler to an EGR gas distributor with a partial breakage according to the first embodiment. FIG. 6 is a configuration diagram showing a configuration from the EGR valve of FIG. 2 to the EGR gas distributor according to the first embodiment. FIG. 3 is a sectional view taken along line AA of FIG. 3 showing piping according to the first embodiment. FIG. 3 is a sectional view taken along line BB of FIG. 3 showing piping according to the first embodiment. A time chart showing the opening and closing of the EGR valve and the bypass valve and changes in various temperatures after the engine is started according to the first embodiment. FIG. 3 is a configuration diagram according to FIG. 3 showing a configuration from piping to an EGR gas distributor according to a second embodiment. FIG. 5 is a cross-sectional view according to FIG. 5 showing piping according to the second embodiment. FIG. 2 is a configuration diagram according to FIG. 2 showing a configuration from an EGR cooler to an EGR gas distributor according to a third embodiment. FIG. 2 is a configuration diagram according to FIG. 2 showing a configuration from an EGR cooler to an EGR gas distributor according to a fourth embodiment. FIG. 5 is a cross-sectional view showing a pipe cut in a direction orthogonal to the longitudinal direction thereof according to the fifth embodiment. FIG. 6 is a cross-sectional view showing a pipe cut in a direction orthogonal to the longitudinal direction thereof according to the sixth embodiment. FIG. 2 is a configuration diagram according to FIG. 2 showing a configuration from an EGR cooler to an EGR gas distributor according to a seventh embodiment. FIG. 2 is a configuration diagram according to FIG. 2 showing a configuration from an EGR cooler to an EGR gas distributor according to an eighth embodiment. FIG. 9 is a configuration diagram according to FIG. 9 showing a configuration from an EGR cooler to an EGR gas distributor according to a ninth embodiment. FIG. 15 is a sectional view taken along line CC of FIG. 15 showing piping according to the ninth embodiment. FIG. 16 is a cross-sectional view according to FIG. 16 showing a configuration of piping according to the tenth embodiment. FIG. 15 is a configuration diagram according to FIG. 15 showing a configuration from an EGR cooler to an EGR gas distributor according to the eleventh embodiment. FIG. 18 is a sectional view taken along line DD of FIG. 18 showing piping according to the eleventh embodiment. FIG. 19 is a cross-sectional view according to FIG. 19 showing piping according to the twelfth embodiment. FIG. 19 is a cross-sectional view according to FIG. 19 showing piping according to the thirteenth embodiment. FIG. 19 is a cross-sectional view according to FIG. 19 showing piping according to the 14th embodiment. FIG. 19 is a cross-sectional view according to FIG. 19 showing piping according to the fifteenth embodiment. A side view showing a part of a pipe to which a metal pipe is fixed according to a sixteenth embodiment. FIG. 24 is a sectional view taken along line EE of FIG. 24 showing a pipe to which a metal pipe is fixed according to a sixteenth embodiment. A side view showing a part of a pipe to which a metal pipe is fixed according to the seventeenth embodiment. FIG. 26 is a sectional view taken along line FF of FIG. 26 showing a pipe to which a metal pipe is fixed according to the 17th embodiment. FIG. 25 is a cross-sectional view according to FIG. 25 showing a pipe to which a metal pipe is fixed according to the eighteenth embodiment. FIG. 27 is a cross-sectional view according to FIG. 27 showing a pipe to which a metal pipe is fixed according to the nineteenth embodiment. FIG. 28 is a cross-sectional view according to FIG. 28 showing a pipe to which a metal pipe is fixed according to the twentieth embodiment. FIG. 29 is a cross-sectional view according to FIG. 29 showing a pipe to which a metal pipe is fixed according to the 21st embodiment. A side view showing a part of a pipe to which a metal pipe is fixed according to the 22nd embodiment. FIG. 32 is a sectional view taken along line GG of FIG. 32 showing a pipe to which a metal pipe is fixed according to the 22nd embodiment. A side view showing a part of a pipe to which a metal pipe is fixed according to the 23rd embodiment. FIG. 34 is a sectional view taken along line OH of FIG. 34 showing a pipe to which a metal pipe is fixed according to the 23rd embodiment. FIG. 15 is a configuration diagram according to FIG. 15 showing a configuration from an EGR cooler to an EGR gas distributor according to the 24th embodiment. FIG. 4 is a cross-sectional view showing a connection portion between a metal upstream pipe and its outlet flange and a resin downstream pipe and its inlet flange, which are the objects of measurement according to the 24th embodiment. FIG. 4 is a cross-sectional view showing a connection portion between a metal upstream pipe and its outlet flange and a metal downstream pipe and its inlet flange, which are related to the 24th embodiment in inverse proportion and are measurement targets. A time chart showing (A) changes in engine speed (EGR flow rate) and (B) changes in various temperatures according to the 24th embodiment. FIG. 9 is a configuration diagram according to FIG. 9 showing a configuration from an EGR cooler to an EGR gas distributor according to another embodiment. FIG. 6 is a configuration diagram showing a configuration from an EGR cooler to an EGR gas distributor according to another embodiment. A cross-sectional view according to FIG. 23 showing the pipe 16 according to another embodiment. FIG. 6 is a cross-sectional view according to FIG. 35 showing the pipe 16 according to another embodiment.

Hereinafter, some embodiments in which the EGR device is embodied in a gasoline engine system will be described.

<First Embodiment>
First, the first embodiment will be described in detail with reference to the drawings.

[About the engine system]
FIG. 1 shows a gasoline engine system of this embodiment (hereinafter, simply referred to as “engine system”) by a schematic configuration diagram. The engine system mounted on the automobile includes an engine 1 having a plurality of cylinders. The engine 1 is a 4-cylinder, 4-cycle reciprocating engine and includes well-known configurations such as a piston and a crankshaft. The engine 1 is provided with an intake passage 2 for introducing intake air into each cylinder and an exhaust passage 3 for deriving exhaust gas from each cylinder of the engine 1. The intake passage 2 is provided with a throttle device 4 and an intake manifold 5. The exhaust passage 3 is provided with an exhaust manifold 6 and a catalyst 7. In addition, a high-pressure loop type exhaust gas recirculation device (EGR device) 11 is provided between the exhaust passage 3 and the intake passage 2.

The throttle device 4 is arranged in the intake passage 2 upstream of the intake manifold 5, and by driving the butterfly type throttle valve 4a to open and close with a variable opening according to the accelerator operation of the driver, the amount of intake air flowing through the intake passage 2 Is designed to be adjusted. The intake manifold 5 is mainly composed of a resin material and is arranged in the intake passage 2 directly upstream of the engine 1. One surge tank 5a into which the intake air is introduced and the intake air introduced in the surge tank 5a are used in the engine 1. It includes a plurality of (four) branch pipes 5b branched from the surge tank 5a for distribution to each cylinder. The catalyst 7 contains, for example, a three-way catalyst in order to purify the exhaust gas.

The engine 1 is provided with a fuel injection device (not shown) for injecting fuel corresponding to each cylinder. The fuel injection device is configured to inject fuel supplied from a fuel supply device (not shown) into each cylinder of the engine 1. In each cylinder, a combustible air-fuel mixture is formed by the fuel injected from the fuel injection device and the intake air introduced from the intake manifold 5.

The engine 1 is provided with an ignition device (not shown) corresponding to each cylinder. The igniter is configured to ignite the combustible mixture in each cylinder. The combustible air-fuel mixture in each cylinder explodes and burns due to the ignition operation of the ignition device, and the exhaust gas after combustion is discharged from each cylinder to the outside via the exhaust manifold 6 and the catalyst 7. At this time, the piston (not shown) moves up and down in each cylinder, and the crankshaft (not shown) rotates to obtain power to the engine 1.

[About EGR equipment]
As shown in FIG. 1, in the EGR device 11 of this embodiment, a part of the exhaust gas discharged from each cylinder of the engine 1 to the exhaust passage 3 is flowed to the intake passage 2 as an exhaust gas recirculation gas (EGR gas) to the engine 1. It is configured to recirculate to each cylinder of. The EGR device 11 adjusts the flow rate of the exhaust gas recirculation passage (EGR passage) 12, the exhaust gas recirculation cooler (EGR cooler) 13 for cooling the EGR gas flowing through the EGR passage 12, and the EGR gas flowing through the EGR passage 12. Exhaust gas recirculation valve (EGR valve) 14 and exhaust gas recirculation gas distribution for distributing EGR gas to each branch pipe 5b of the intake manifold 5 in order to distribute the EGR gas flowing through the EGR passage 12 to each cylinder of the engine 1. A device (EGR gas distributor) 15 is provided. The flow path through which the EGR gas of the EGR cooler 13, the EGR valve 14, and the EGR gas distributor 15 flows also constitutes the EGR passage 12. The piping constituting the EGR passage 12 includes an inlet 12a and an outlet 12b. The inlet 12a is connected to the exhaust passage 3 upstream of the catalyst 7, and the outlet 12b is connected to the EGR gas distributor 15. In this embodiment, the EGR gas distributor 15 constitutes the final stage of the EGR passage 12. In the EGR passage 12, the EGR valve 14 is provided downstream from the EGR cooler 13, and the EGR gas distributor 15 is provided downstream from the EGR valve 14.

The EGR gas distributor 15 is mainly composed of a resin material, has a horizontally long shape as a whole, and is arranged so as to cross a plurality of branch pipes 5b of the intake manifold 5 in the longitudinal direction thereof. In this embodiment, the EGR gas distributor 15 has a gas chamber 15a in which the introduced EGR gas is collected, and a plurality (four) gas distribution passages 15b for distributing the EGR gas from the gas chamber 15a to each branch pipe 5b. include.

In this EGR device 11, when the EGR valve 14 is opened, a part of the exhaust gas flowing through the exhaust passage 3 flows through the EGR passage 12 as EGR gas, and passes through the EGR cooler 13, the EGR valve 14, and the EGR gas distributor 15. It is distributed to each branch pipe 5b of the intake manifold 5, and further distributed to each cylinder of the engine 1 to be circulated.

As shown by an arrow in FIG. 1, the EGR passage 12 includes an upstream passage portion USP near the exhaust passage 3, a downstream passage portion DSP near the intake manifold 5 constituting the intake passage 2, and an upstream passage portion USP and downstream. Includes a midstream passage MSP between the passage DSP. In this embodiment, the upstream passage portion USP includes a passage portion between the inlet 12a of the EGR passage 12 and the EGR cooler 13. The midstream passage portion MSP includes a passage portion from the EGR cooler 13 to the inlet of the EGR gas distributor 15 (details of the range of the midstream passage portion MSP will be described later). The downstream passage DSP includes a passage in the EGR gas distributor 15. As described above, in this embodiment, the upstream passage portion USP, the middle flow passage portion MSP, and the downstream passage portion DSP are not separated by the substantial flow path length of the EGR passage 12, and are on the EGR passage 12. It is classified according to the arrangement of equipment such as the EGR cooler 13, the EGR valve 14, and the EGR gas distributor 15 provided in the EGR cooler 13. It is also possible to classify the upstream passage portion USP, the middle flow passage portion MSP and the downstream passage portion DSP by the substantial flow path length of the EGR passage 12.

FIG. 2 is a configuration diagram showing a specific configuration on the EGR passage 12 from the EGR cooler 13 to the EGR gas distributor 15 with a partial break. FIG. 3 shows the configuration from the EGR valve 14 to the EGR gas distributor 15 in FIG. 2 by a block diagram. As shown in FIGS. 2 and 3, in this embodiment, the inlet 34a of the flow path 34 of the EGR valve 14 is connected to the outlet 21c of the EGR cooler 13, and the EGR passage 12 is connected to the outlet 34b of the flow path 34 of the EGR valve 14. The inlet 16a of the pipe 16 constituting the above is connected, and the outlet 16b of the pipe 16 is connected to the inlet of the EGR gas distributor 15.

As shown in FIG. 2, the EGR cooler 13 includes a casing 21. The casing 21 is provided from the main passage 21a through which the EGR gas flows, the inlet 21b for introducing the EGR gas, the outlet 21c for leading out the EGR gas, the introduction portion 21d between the main passage 21a and the inlet 21b, and the main passage 21a. It includes a lead-out portion 21e to the outlet 21c, a bent flow path portion 21f, and a bypass passage 21g provided in parallel with the main passage 21a and for bypassing the main passage 21a. The main passage 21a is provided with a cooling heat exchanger 23 that exchanges heat between the EGR gas and the refrigerant. The heat exchanger 23 cools the EGR gas flowing through the main passage 21a. The cooling water of the engine 1 circulates in the heat exchanger 23 as a refrigerant. The heat exchanger 23 has a well-known configuration. A butterfly valve type bypass valve 24 for opening and closing the bypass passage 21g is provided in the upstream portion of the bypass passage 21g. In this embodiment, as shown in FIG. 2, in the EGR cooler 13, the EGR gas (black arrow, indicated by a hatched arrow) flows diagonally upward through the main passage 21a and the bypass passage 21g. Arranged diagonally. In this diagonally arranged state, the outlet 21c is arranged at a position higher in the vertical direction than the inlet 21b. Further, in this diagonally arranged state, the condensed water generated inside the EGR cooler 13 (indicated by a white arrow) flows through the bypass passage 21 g from the downstream portion to the upstream portion.

As shown in FIG. 2, the heat exchanger 23 includes an inlet 23a and an outlet 23b of the EGR gas, and the bypass passage 21g includes an inlet 21ga and an outlet 21gb of the EGR gas. In this embodiment, the midstream passage MSP is located downstream of the outlet 23b of the heat exchanger 23 and the outlet 21gb of the bypass passage 21g, and the EGR valve 14 is provided in the midstream passage MSP. That is, in this embodiment, the midstream passage portion MSP is composed of a passage portion from the outlet 23b of the heat exchanger 23 of the EGR cooler 13 to the inlet of the EGR gas distributor 15.

As shown in FIGS. 2 and 3, the EGR valve 14 is composed of a motor unit 31 having a built-in step motor and a valve unit 32. The valve portion 32 includes a flow path 34, a valve seat 35 arranged in the flow path 34, a valve body 36, and a valve shaft 37. The valve portion 32 includes a metal outer housing 38, a resin inner housing 39, and a resin flow path member 40 that covers a portion of the outer housing 38 facing the flow path 34. The inner wall of the flow path 34 is composed of a resin inner housing 39 and a resin flow path member 40. That is, the inner wall of the flow path 34 is made of a resin material having a function of retaining heat of the EGR gas.

The pipe 16 connected to the outlet 34b of the EGR valve 14 is formed by refracting in a channel shape. In this embodiment, the pipe 16 is made of a resin material having a function of keeping the EGR gas warm. As the resin material, for example, "66 nylon" can be used.

FIG. 4 shows the pipe 16 with a cross-sectional view taken along the line AA of FIG. FIG. 5 shows the pipe 16 with a cross-sectional view taken along the line BB of FIG. In this embodiment, as shown by the broken line in FIG. 2 and the hatching in FIGS. 3 to 5, the flow path 34 and the pipe 16 are formed on the entire inner wall of the flow path 34 of the EGR valve 14 and the entire inner wall of the pipe 16. A heat insulating coat 41 is provided to keep the EGR gas flowing through the water warm. As the heat insulating coat 41, for example, a "ceramic coat" can be used. The heat insulating coat 41 corresponds to an example of the heat insulating means of this disclosed technique. A heat insulating coat 41 for keeping the EGR gas warm is provided on the inner wall of the flow path 34 of the EGR valve 14 and the inner wall of the pipe 16 constituting the midstream passage portion MSP. In this embodiment, as shown in FIGS. 3 and 5, the thickness of the heat insulating coat 41 is formed to be uniform (same) between the upstream portion US, the middle flow portion MS, and the downstream portion DS of the pipe 16. To. Since the flow of EGR gas collides with the corner portion of the pipe 16 surrounded by the two-dot chain line S1 in FIG. 3, it is desirable to make the thickness of the heat insulating coat 41 particularly thicker than that of other portions.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment described above, a part of the exhaust gas discharged from the engine 1 to the exhaust passage 3 flows into the EGR passage 12 as EGR gas, and the EGR cooler 13, the EGR valve 14 and the EGR gas It flows through the distributor 15 and the like, is suitably distributed to each branch pipe 5b of the intake manifold 5, is distributed to each cylinder of the engine 1, and is circulated.

Here, as shown in FIG. 1, the EGR passage 12 is composed of an upstream passage portion USP including an EGR cooler 13, a middle flow passage portion MSP including an EGR valve 14 and a pipe 16, and an EGR gas distributor 15. It is divided into a downstream passage section DSP. Since the flow path 34 of the EGR valve 14 and the inner wall of the pipe 16 constituting the midstream passage portion MSP are made of a resin material having a function of retaining heat of the EGR gas and have a certain length, the EGR valve 14 is used. The temperature drop of the EGR gas in the flow path 34 and the pipe 16 and the temperature of the EGR gas flowing into the EGR gas distributor 15 become problems. This is because when the EGR gas becomes lower than the dew point temperature, condensed water is generated in the EGR gas distributor 15.

Therefore, according to the configuration of the EGR device 11 of this embodiment, the EGR gas flowing there is kept warm on the inner wall of the flow path 34 and the pipe 16 (middle flow passage portion MSP) of the EGR valve 14 provided in the EGR passage 12. A heat insulating coat 41 (heat insulating means) is provided for this purpose. Therefore, the heat of the EGR gas flowing from the EGR cooler 13 or the like (upstream passage portion USP) provided in the EGR passage 12 to the flow path 34 of the EGR valve 14 and the pipe 16 (middle flow passage portion MSP) is generated by the heat insulating coat 41. It becomes difficult to transmit to the outside, and the EGR gas flows to the EGR gas distributor 15 (downstream passage portion DSP) in a state where the EGR gas is kept warm. In particular, the midstream passage portion MSP is located downstream from the outlet 23b of the heat exchanger 23 of the EGR cooler 13 and the outlet 21gb of the bypass passage 21g, and the EGR valve 14 is provided in the midstream passage portion MSP. Therefore, the EGR gas flowing through the flow path 34 of the EGR valve 14 and the pipe 16 flows to the EGR gas distributor 15 in a state of being kept warm by the heat insulating coat 41. Therefore, the temperature of the EGR gas can be lowered by the heat exchanger 15, and the flow path 34 and the pipe 16 (middle flow passage portion MSP) of the EGR valve 14 formed of the resin material are not melted by the EGR gas. It can be suppressed. Further, it is possible to reduce the heat transfer of the EGR gas to the resin material in the flow path 34 and the pipe 16 (middle flow passage portion MSP) of the EGR valve 14, and to the EGR gas distributor 15 (downstream passage portion DSP). The temperature drop of the flowing EGR gas can be suppressed, the EGR gas distributor 15 can be quickly warmed up, and the generation of condensed water in the EGR gas distributor 15 can be suppressed.

According to the configuration of this embodiment, since the flow path 34 of the EGR valve 14 constituting the middle flow passage portion MSP and the inner wall of the pipe 16 are made of a resin material having a function of retaining heat of the EGR gas, the flow path 34 thereof. In addition, heat retention is obtained in the pipe 16 itself, and the flow path 34 and the pipe 16 can be easily formed. Therefore, it is possible to easily suppress the temperature drop of the EGR gas in the EGR valve 14 and the pipe 16 (middle flow passage portion MSP).

According to the configuration of this embodiment, since the heat insulating means is the heat insulating coat 41 provided on the inner wall of the flow path 34 and the pipe 16 of the EGR valve 14, the inner wall of the flow path 34 and the pipe 16 (middle flow passage portion MSP). It becomes easy to form a heat insulating means for the warmth. Therefore, it is possible to facilitate the manufacture of the EGR device 11 provided with the heat insulating means.

According to the configuration of this embodiment, since the flow path 34 of the EGR valve 14 is made of a resin material having a function of retaining heat in the EGR gas, the flow path 34 itself can obtain heat retention and the flow path thereof. Molding of 34 becomes easy. Therefore, it is possible to easily suppress the temperature drop of the EGR gas in the EGR valve 14.

FIG. 6 shows in this embodiment the opening and closing of the EGR valve 14 and the bypass valve 24 and changes in various temperatures after the engine is started by a time chart. That is, FIG. 6 shows the EGR gas temperature (pipe inlet gas temperature) PIG at the inlet 16a of the pipe 16 and the inner wall temperature of the inlet 16a of the pipe 16 when the EGR valve 14 and the bypass valve 24 are opened from a low temperature. Pipe inlet inner wall temperature) PIW1, PIW2, EGR gas temperature at the outlet of the EGR gas distributor 15 (distributor outlet gas temperature) DOG1, DOG2, cooling water temperature (cooling water temperature) THW, at the outlet of the EGR gas distributor 15. The changes in the inner wall temperature (distributor outlet inner wall temperature) DOWN1 and DOWN2 are shown. Here, the pipe inlet inner wall temperature PIW1 indicates a case where the heat insulating coat 41 is not provided on the inner wall of the pipe 16, and the pipe inlet inner wall temperature PIW2 shows a case where the heat insulating coat 41 is provided on the inner wall of the pipe 16. The distributor outlet gas temperature DOG1 indicates a case where the heat insulating coat 41 is not provided on the inner wall of the pipe 16, and the distributor outlet gas temperature DOG2 shows a case where the heat insulating coat 41 is provided on the inner wall of the pipe 16. The distributor outlet inner wall temperature DOWN 1 indicates the case where the heat insulating coat 41 is not provided on the inner wall of the pipe 16, and the distributor outlet inner wall temperature DOWN 2 indicates the case where the heat insulating coat 41 is provided on the inner wall of the pipe 16.

As shown in FIG. 6, at time t1, when the above-mentioned temperatures PIG, PIW1, PIW2, DOG1, DOG2, DOW1, DOWN2, THW are at a predetermined temperature T0 (for example, “25 ° C.”), which is a low temperature, When the engine 1 starts to start, the cooling water temperature THW starts to raise the temperature, and eventually reaches the engine thermo temperature T3 which is the upper limit temperature at time t7.

Here, when the cooling water temperature THW reaches the EGR start temperature T1 (for example, “40 ° C.”) at time t2, the EGR valve 14 and the bypass valve 24 are opened (in this case, the bypass valve is opened at time t5). When only 24 is closed), EGR gas flows through the EGR passage 12, so that various temperatures other than the cooling water temperature THW, PIG, PIW1, PIW2, DOG1, DOG2, DOW1, and DOW2, also start to raise the temperature. At this time, the pipe inlet gas temperature PIG rises higher than the others toward time t7. On the other hand, the pipe inlet inner wall temperatures PIW1 and PIW2 become higher than the aromatic nylon heat resistant temperature T5, which is higher than the other temperatures T0 to T4, at time t7. Here, the pipe inlet inner wall temperature PIW1 when the heat insulating coat 41 is not provided is higher than the pipe inlet inner wall temperature PIW2 when the heat insulating coat 41 is provided.

On the other hand, the distributor outlet inner wall temperatures DOW1 and DOW2 are higher than the dew point temperature T2 at time t7, and the distributor outlet gas temperatures DOG1 and DOG2 are higher than the engine thermo temperature T3 at time t7, 66 nylon. The heat resistant temperature is lower than T4. Here, the distributor outlet inner wall temperature DOWN2 and the distributor outlet gas temperature DOG2 when the heat insulating coat 41 is provided are higher than the distributor outlet inner wall temperature DOWN1 and the distributor outlet gas temperature DOG1 when the heat insulating coat 41 is not provided. Will also be higher. From this, it can be seen that the temperature drop of the EGR gas flowing to the EGR gas distributor 15 can be suppressed more when the heat insulating coat 41 is provided. Moreover, the distributor outlet inner wall temperature DOWN1 when the heat insulating coat 41 is not provided reaches the dew point temperature T2 at the time between the time t6 and the time t7, whereas the distributor outlet when the heat insulating coat 41 is provided. The inner wall temperature DOWN2 has reached the dew point temperature T2 at a time between time t3 and time t4. From this, it can be seen that when the heat insulating coat 41 is provided, the EGR gas can be returned to each cylinder of the engine 1 from an earlier time after the engine is started without generating condensed water in the EGR gas distributor 15.

In this embodiment, since the heat insulating coat 41 is provided on the inner wall of the flow path 34 of the EGR valve 14 and the inner wall of the pipe 16, the bypass valve 24 is opened at time t2 and at time t5 as shown in FIG. I was able to close the valve. As a result, the high-temperature EGR gas can flow for a long time through the bypass passage 21g without melting the resin flow path 34 and the pipe 16 due to overheating, and the apparent heat resistance of the flow path 34 and the pipe 16 is improved. I was able to make it. On the other hand, when the heat insulating coat 41 is not provided on the inner walls of the flow path 34 and the pipe 16, the bypass valve 24 is closed at the latest at time t3 in order to suppress melting damage due to overheating of the flow path 34 and the pipe 16. Therefore, the time for the high temperature EGR gas to flow to the flow path 34 and the pipe 16 is shortened by the earlier the time to close the bypass valve 24.

<Second Embodiment>
Next, the second embodiment will be described in detail with reference to the drawings. In the following description, the components equivalent to those in the first embodiment are designated by the same reference numerals, the description thereof will be omitted, and the differences will be mainly described.

[About the composition of the heat insulating coat in piping]
This embodiment differs from the first embodiment in the configuration of the heat insulating coat 41 in the pipe 16. That is, FIG. 7 shows the configuration from the pipe 16 to the EGR gas distributor 15 by a configuration diagram according to FIG. FIG. 8 shows the pipe 16 in a cross-sectional view according to FIG. As shown in FIGS. 7 and 8, in this embodiment, the thickness of the heat insulating coat 41 is formed to be different between the upstream portion US, the middle flow portion MS, and the downstream portion DS of the pipe 16. That is, the thickness of the heat insulating coat 41 is the smallest in the downstream portion DS (downstream side) of the pipe 16, and gradually increases in the order of the middle flow portion MS and the upstream portion US (upstream side). That is, the heat insulating coat 41 is formed so that its thickness gradually increases from the downstream portion DS (downstream side) to the upstream portion US (upstream side) of the pipe 16. In FIGS. 7 and 8, it is exaggerated to clarify the stepwise change in the thickness of the heat insulating coat 41. Also in this embodiment, it is desirable that the thickness of the heat insulating coat 41 is thicker than that of other portions at the corner portion of the pipe 16 surrounded by the two-dot chain line S1 in FIG. 7. Although the EGR valve 14 is not shown in FIG. 7, the thickness of the heat insulating coat 41 provided on the inner wall of the flow path 34 of the EGR valve 14 is the thickness of the heat insulating coat 41 of the upstream portion US of the pipe 16. Can be the same as or larger than that.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, the following actions and effects can be obtained in addition to the actions and effects of the first embodiment. That is, in this embodiment, the heat insulating coat 41 is formed so that its thickness gradually increases from the downstream portion DS (downstream side) to the upstream portion US (upstream side) of the pipe 16. Here, the temperature of the EGR gas flowing through the pipe 16 is high in the upstream portion US of the pipe 16, and decreases toward the middle flow portion MS and the downstream portion DS. Therefore, the heat insulating property of the pipe 16 is set from the upstream portion US to the downstream portion DS according to the temperature change of the EGR gas flowing therethrough. Therefore, the EGR gas can be effectively kept warm from the upstream portion US to the downstream portion DS of the pipe 16 in accordance with the temperature change of the EGR gas flowing through the pipe 16, and the heat resistance of the pipe 16 can be effectively secured.

<Third Embodiment>
Next, the third embodiment will be described in detail with reference to the drawings.

[About the arrangement of EGR valves]
This embodiment differs from each of the above embodiments in that the EGR valve 14 is arranged in the EGR passage 12. That is, FIG. 9 shows the configuration from the EGR cooler 13 to the EGR gas distributor 15 by a configuration diagram according to FIG. 2. As shown in FIG. 9, in this embodiment, an assembly portion 21h for assembling the EGR valve 14 is provided in the flow path portion 21f of the casing 21 of the EGR cooler 13, and the EGR valve is provided in the hole of the assembly portion 21h. By incorporating (drop-in) the housing 46 of 14, the EGR valve 14 is attached to the EGR cooler 13. The housing 46 of the EGR valve 14 is made of a resin material having a function of retaining heat of the EGR gas, and is provided with a flow path 34 and a valve seat 35 on which the valve body 36 is seated. The inlet 16a of the pipe 16 made of a resin material is connected to the outlet 21c of the EGR cooler 13. A heat insulating coat 41 shown by a broken line is provided on the inner wall of the pipe 16. Also in this embodiment, the heat insulating coat 41 is formed to have a uniform thickness from the upstream side to the downstream side of the pipe 16, or is formed so as to gradually or gradually increase from the downstream side to the upstream side of the pipe 16. be able to. Further, the thickness of the heat insulating coat 41 can be made particularly thicker at the corner portion of the pipe 16 than at other portions.

In addition, in this embodiment, the flow path 34 of the EGR valve 14 includes an inlet 34a and an outlet 34b, and the inlet 34a of the flow path 34 is arranged substantially adjacent to the outlet 23b of the heat exchanger 23.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, the following actions and effects can be obtained in addition to the actions and effects substantially equivalent to those of the first embodiment. That is, in this embodiment, since the EGR valve 14 is assembled to the assembly portion 21h of the EGR cooler 13, the entire EGR device 11 can be made compact.

Further, according to the configuration of this embodiment, since the inlet 34a of the flow path 34 of the EGR valve 14 is arranged substantially adjacent to the outlet 23b of the heat exchanger 23, it has just flowed out from the outlet 23b of the heat exchanger 23. The EGR gas flows into the inlet 34a of the resin flow path 34 of the EGR valve 14 at an early stage. Therefore, the temperature drop of the EGR gas that has just flowed out from the outlet 23b of the heat exchanger 23 can be suppressed by the flow path 34 of the EGR valve 14.

<Fourth Embodiment>
Next, the fourth embodiment will be described in detail with reference to the drawings.

[About the arrangement of EGR valves]
This embodiment differs from each of the above embodiments in that the EGR valve 14 is arranged in the EGR passage 12. That is, FIG. 10 shows the configuration from the EGR cooler 13 to the EGR gas distributor 15 with a configuration diagram according to FIG. 2. As shown in FIG. 10, in this embodiment, an assembly portion 15c for assembling the EGR valve 14 is provided on the inlet side of the EGR gas distributor 15 made of a resin material, and a hole of the assembly portion 15c is provided. The EGR valve 14 is attached to the EGR gas distributor 15 by incorporating the housing 46 of the EGR valve 14 into the EGR valve 14 (drop-in). The housing 46 of the EGR valve 14 is made of a resin material having a function of retaining heat of the EGR gas, and is provided with a flow path 34 and a valve seat 35 on which the valve body 36 is seated. An inlet 15d is provided at the bottom of the assembly portion 15c made of a resin material, and the outlet 16b of the pipe 16 is connected to the inlet 15d. A heat insulating coat 41 shown by a broken line is provided on the inner wall of the pipe 16 and the inner wall of the flow path 34 of the housing 46. Also in this embodiment, the heat insulating coat 41 is formed to have a uniform thickness from the upstream side to the downstream side of the pipe 16, or is formed so as to gradually or gradually increase from the downstream side to the upstream side of the pipe 16. You can also do it.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, the following actions and effects can be obtained in addition to the actions and effects substantially equivalent to those of the first embodiment. That is, in this embodiment, since the EGR valve 14 is assembled to the assembly portion 15c of the EGR gas distributor 15, the entire EGR device 11 can be made compact.

<Fifth Embodiment>
Next, the fifth embodiment will be described in detail with reference to the drawings.

[About the configuration of heat insulating means]
This embodiment is different from each of the above-described embodiments in the configuration of the heat insulating means in the pipe 16. That is, FIG. 11 shows a cross-sectional view of the pipe 16 cut in a direction orthogonal to the longitudinal direction thereof. As shown in FIG. 11, the heat insulating means of this embodiment is composed of a heating unit 50 for heating the pipe 16 (middle flow passage unit MSP). In this embodiment, the heating unit 50 is provided on the inner wall of the pipe 16 made of a resin material, and is composed of a heat generating film 51 that generates heat by energization. In FIG. 11, a positive electrode 53 having a positive terminal 53a and a negative electrode 54 having a negative terminal 54a are connected to the heat generating film 51. Then, the heat generating film 51 is energized from the positive terminal 53a and the negative terminal 54a via the positive electrode 53 and the negative electrode 54.

[About the action and effect of the EGR device]
According to the EGR device 11 configuration of this embodiment, the following actions and effects can be obtained in addition to the actions and effects substantially equivalent to those of the first embodiment. That is, since the heat retaining means is the heating unit 50, by heating the pipe 16 constituting the middle flow passage portion MSP by the heating unit 50, both the heat retention and the temperature rise of the pipe 16 become possible. More specifically, by generating heat by energizing the heating film 51 via the positive electrode 53 and the negative electrode 54, the inner wall of the pipe 16 (middle flow passage portion MSP) is heated over a wide area at an arbitrary timing. To. Therefore, the EGR gas flowing through the pipe 16 can be effectively kept warm. Further, the EGR gas flowing through the pipe 16 can be responsively and stably kept warm. As a result, the EGR gas flowing to the EGR gas distributor 15 can be effectively kept warm.

<Sixth Embodiment>
Next, the sixth embodiment will be described in detail with reference to the drawings.

[About the configuration of heat insulating means]
This embodiment is different from each of the above-described embodiments in the configuration of the heat insulating means in the pipe 16. That is, FIG. 12 shows a cross-sectional view of the pipe 16 cut in a direction orthogonal to the longitudinal direction thereof. As shown in FIG. 12, the heat insulating means of this embodiment is composed of an air layer 56 provided on the outside of a pipe 16 (middle flow passage portion MSP) made of a resin material having a function of keeping heat of EGR gas. .. The pipe 16 has a double pipe structure formed by the outer pipe 16c and the inner pipe 16d, and an air layer 56 is formed between the two

pipes

16c and 16d.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, the following actions and effects can be obtained in addition to the actions and effects substantially equivalent to those of the first embodiment. That is, since the heat insulating means is the air layer 56, it is not necessary to use a special member for the heat insulating means. Therefore, the number of parts constituting the EGR device 11 can be reduced by the amount of the heat insulating means. The air layer 56 can also effectively keep the EGR gas flowing through the pipe 16 warm.

<7th Embodiment>
Next, the seventh embodiment will be described in detail with reference to the drawings.

[About the configuration of the bypass passage]
This embodiment differs from each of the above embodiments in that the bypass passage 21g provided in the EGR cooler 13 is configured. That is, FIG. 13 shows the configuration from the EGR cooler 13 to the EGR gas distributor 15 by a configuration diagram according to FIG. 2. As shown in FIG. 13, this embodiment differs from the first embodiment in that a cooling unit 58 for cooling a part of the bypass passage 21g is further provided. The cooling unit 58 is provided around a part of the bypass passage 21g in the longitudinal direction so that the cooling water of the engine 1 circulates.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, in addition to the same actions and effects as those of the first embodiment, the following actions and effects can be obtained. That is, in this embodiment, since the EGR gas flowing through the bypass passage 21g is cooled by the cooling unit 58, the EGR gas flowing from the bypass passage 21g into the flow path 34 of the EGR valve 14 and the pipe 16 (middle flow passage portion MSP). The temperature drops. Therefore, the temperature of the EGR gas can be brought close to the heat resistant temperature of the resin material constituting the flow path 34 and the pipe 16 (middle flow passage portion MSP), and even if the high temperature EGR gas flows through the bypass passage 21 g, the EGR gas can be brought close to the heat resistant temperature. It is possible to suppress melting damage due to overheating of the flow path 34 and the pipe 16 (middle flow passage portion MSP) due to gas.

<8th Embodiment>
Next, the eighth embodiment will be described in detail with reference to the drawings.

[About the configuration of heat insulating means]
This embodiment is different from each of the above-described embodiments in the configuration of the heat insulating means in the EGR valve 14 and the pipe 16. That is, FIG. 14 shows the configuration from the EGR cooler 13 to the EGR gas distributor 15 with a configuration diagram according to FIG. 2. In the first embodiment, a heat insulating coat 41 as a heat insulating means is provided on the inner wall of the flow path 34 of the EGR valve 14 and the inner wall of the pipe 16 made of a resin material (66 nylon). On the other hand, in this embodiment, instead of omitting the heat insulating coat and providing the heat insulating coat, the flow path 34 and the pipe 16 of the EGR valve 14 are made of a resin material having a function of retaining heat of the EGR gas (for example, "aromatic". The heat insulating means is configured by forming it from "nylon"). Here, with respect to the flow path 34, the inner housing 39 and the flow path member 40 are formed of, for example, aromatic nylon.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, the following actions and effects can be obtained in addition to the actions and effects substantially equivalent to those of the first embodiment. That is, when the resin material constituting the flow path 34 and the pipe 16 of the EGR valve 14 is made of, for example, aromatic nylon, the heat resistant temperature of the aromatic nylon is higher than that of 66 nylon, so that the flow path 34 and the pipe The heat retaining property is obtained in the 16 itself, and it is not necessary to separately provide a heat retaining means. Therefore, it is possible to facilitate the manufacture of the EGR device 11 provided with the heat insulating means.

<9th embodiment>
Next, the ninth embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from each of the above-described embodiments in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 15 shows the configuration from the EGR cooler 13 to the EGR gas distributor 15 with a configuration diagram according to FIG. In the third embodiment, the inner wall of the flow path 34 of the EGR valve 14 is made of a resin material, and the inner wall of the pipe 16 (middle flow passage portion MSP) made of the resin material is provided with a heat insulating coat 41 as a heat insulating means. Provided. On the other hand, in this embodiment, in the pipe 16 (middle flow passage portion MSP), instead of omitting the heat insulating coat and providing the heat insulating coat, the hot water passage 61 through which hot water flows along the longitudinal direction of the flow path of the pipe 16 is provided. It is formed. For example, engine cooling water as hot water warmed by cooling the engine 1 flows through the hot water passage 61. The hot water passage 61 includes an inlet 61a provided in the vicinity of the inlet 16a of the pipe 16 and an outlet 61b provided in the vicinity of the outlet 16b of the pipe 16. The engine cooling water flows into the hot water passage 61 from the inlet 61a and flows out from the outlet 61b. FIG. 16 shows the pipe 16 with a cross-sectional view taken along the line CC of FIG. As shown in FIG. 16, the pipe 16 of this embodiment has a double pipe structure, includes an outer outer pipe 16c and an inner inner pipe 16d sandwiching the hot water passage 61, and they are not divided. It is formed integrally. In this embodiment, the thickness of the outer tube 16c is larger than the thickness of the inner tube 16d. The hot water passage 61 corresponds to an example of the heating unit 50 of this disclosed technique.

Here, as shown in FIG. 15, in this embodiment, the EGR valve 14 and the pipe 16 are the valve outlet flange 21i provided at the outlet 21c of the casing 21 on the outlet side of the EGR valve 14, and the inlet of the pipe 16. It is connected via a pipe inlet flange 16e provided on the side. Further, the pipe 16 and the EGR gas distributor 15 (downstream passage portion DSP) are provided with a pipe outlet flange 16f provided on the outlet side of the pipe 16 and a distributor inlet flange 15e provided on the inlet side of the EGR gas distributor 15. It is connected via the passage portion entrance flange).

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, it is possible to obtain almost the same operation and effect as that of the fifth embodiment. That is, in the EGR device 11 of this embodiment, since the heat insulating means of the pipe 16 constituting the middle flow passage portion MSP is the heating unit 50, the pipe 16 is heated by the heating unit 50 to keep the pipe 16 warm. And temperature rise are possible. More specifically, the engine cooling water (hot water) flows through the hot water passage 61, so that the inner wall of the pipe 16 (middle flow passage portion MSP) is heated widely in terms of surface. Therefore, the EGR gas flowing through the pipe 16 can be effectively kept warm. Further, the EGR gas flowing through the pipe 16 can be responsively and stably kept warm. As a result, the EGR gas flowing to the EGR gas distributor 15 can be effectively kept warm.

According to the configuration of this embodiment, since the heating unit 50 is composed of the hot water passage 61 through which the hot water flows, the engine cooling water warmed by cooling the engine 1 is used as hot water and flows to the hot water passage 61. It becomes possible. Therefore, unlike the fifth embodiment, heating can be performed without using an electric configuration. Further, even if the flow of the EGR gas in the pipe 16 is stopped, the heating of the pipe 16 is continued by the hot water in the hot water passage 61. Therefore, when the EGR gas flows through the pipe 16 again, the condensed water in the pipe 16 is continued. Occurrence can be suppressed.

According to the configuration of this embodiment, in the pipe 16 (middle flow passage portion MSP), the thickness of the outer pipe 16c sandwiching the hot water passage 61 is larger than the thickness of the inner pipe 16d, so that the heat of the hot water is the inner pipe 16d. It is easily transmitted to the inner wall and difficult to escape to the outer wall of the outer pipe 16c. Therefore, the heatability and heat retention of the EGR gas flowing inside the inner tube 16d can be enhanced.

According to the configuration of this embodiment, since the hot water passage 61 is provided along the flow path longitudinal direction of the pipe 16 (middle flow passage portion MSP), the EGR gas is warmed long along the flow of the EGR gas in the pipe 16. Will be. In this sense as well, the heatability and heat retention of the EGR gas flowing through the pipe 16 can be further enhanced.

<10th Embodiment>
Next, the tenth embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the ninth embodiment in the configuration of the hot water passage 61 as the heating unit 50 in the pipe 16. That is, FIG. 17 shows the configuration of the pipe 16 in a cross-sectional view according to FIG. As shown in FIG. 17, the pipe 16 of this embodiment is configured by joining the upper pipe portion 62 forming the upper side thereof and the lower pipe portion 63 forming the lower side thereof. In this embodiment, the hot water passage 61 is formed only in the lower pipe portion 63, and the hot water passage 61 is not formed in the upper pipe portion 62. That is, the lower pipe portion 63 is formed by the outer pipe 16c and the inner pipe 16d sandwiching the hot water passage 61. The upper pipe portion 62 has an outer diameter equivalent to that of the inner pipe 16d of the lower pipe portion 63, and a flange 62a is formed at the joint portion with the lower pipe portion 63 along the longitudinal direction thereof. Then, the flange 62a of the upper pipe portion 62 and the upper end surface 63a of the lower pipe portion 63 are joined by welding 64 to form the pipe 16.

In FIG. 17, the hot water passage 61 is provided on the lower side of the pipe 16, but by arranging the upper pipe portion 62 and the lower pipe portion 63 upside down in FIG. 17, the hot water passage 61 is provided on the upper side of the pipe 16. You can also do it.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, although the area of the hot water passage 61 in contact with the pipe 16 is reduced, almost the same operation and effect as those of the ninth embodiment can be obtained.

<11th Embodiment>
Next, the eleventh embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the ninth and tenth embodiments in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 18 shows the configuration from the EGR cooler 13 to the EGR gas distributor 15 with a configuration diagram according to FIG. In the ninth and tenth embodiments, the hot water passage 61 through which hot water flows along the longitudinal direction of the pipe 16 (middle flow passage portion MSP) made of a resin material is formed in a double pipe structure. It was formed integrally. On the other hand, in this embodiment, the hot water passage 61 is composed of a metal pipe 66 having a circular cross section provided along the longitudinal direction of the flow path of the pipe 16. In this embodiment, the metal pipe 66 is fixed to the resin pipe 16 by insert molding. As shown in FIG. 18, in the metal pipe 66, the vicinity of the inlet 61a of the hot water passage 61 is bent at a right angle, and the metal pipe 66 is insert-molded into the pipe 16 in this bent state. FIG. 19 shows the pipe 16 with a cross-sectional view taken along the line DD of FIG. As shown in FIG. 19, the pipe 16 of this embodiment includes an upper pipe portion 62 and a lower pipe portion 63, and both 62 and 63 have substantially the same outer diameter.

Flange

62a and 63b are formed in the upper pipe portion 62 and the lower pipe portion 63, respectively, along the longitudinal direction. Then, the flange 62a of the upper pipe portion 62 and the flange 63b of the lower pipe portion 63 are joined by welding 64 to form the pipe 16. In this embodiment, one metal pipe 66 is fixed by insert molding only to the lower pipe portion 63, and the metal pipe is not fixed to the upper pipe portion 62. In this embodiment, the metal pipe 66 is insert-molded so that the entire metal pipe 66 is completely covered with the resin material by the lower pipe portion 63. The metal pipe 66 can be made of, for example, an aluminum pipe or an iron-plated pipe.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, since the hot water passage 61 as the heating unit 50 is provided in the pipe 16, it is possible to obtain almost the same operation and effect as those of the ninth and tenth embodiments.

According to the configuration of this embodiment, since the hot water passage 61 is composed of the metal pipe 66 provided along the longitudinal direction of the flow path of the pipe 16 (middle flow passage portion MSP), the hot water passage 61 is cracked due to disturbance. On the other hand, it is more advantageous than the resin material. Therefore, the durability of the hot water passage 61 can be enhanced.

According to the configuration of this embodiment, since the metal pipe 66 is fixed to the pipe 16 (middle flow passage portion MSP) by insert molding, the adhesion of the metal pipe 66 to the pipe 16 is improved, and the metal pipe 66 is connected to the metal pipe 66. The contact area with the pipe 16 becomes large. Therefore, it is possible to improve the heatability and heat retention of the EGR gas flowing through the pipe 16 by the engine cooling water (hot water) of the hot water passage 61. Further, since the metal pipe 66 is not exposed from the inner wall of the pipe 16, it is possible to prevent the metal pipe 66 from being corroded by the condensed water.

Further, according to the configuration of this embodiment, since the hot water passage 61 is formed by the metal pipe 66, the metal pipe 66 is not cracked due to disturbance, and the engine cooling water flowing through the hot water passage 61 is the pipe 16. There is no risk of leaking inward. Further, as shown in FIG. 19, by not exposing the metal pipe 66 from the inner wall of the pipe 16, the metal pipe 66 is completely covered with the resin material, so that the condensed water generated inside the pipe 16 becomes the metal pipe 66. There is no contact. Further, since the metal pipe 66 can be made of, for example, an aluminum pipe or an iron-plated pipe, the manufacturing cost can be suppressed.

According to the configuration of this embodiment, since a part of the metal pipe 66 is bent and insert-molded into the pipe 16, the metal pipe 66 is positioned with respect to the pipe 16. Therefore, it is possible to prevent the metal pipe 66 from being displaced in the pipe 16.

<12th Embodiment>
Next, the twelfth embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the eleventh embodiment in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 20 shows the pipe 16 in a cross-sectional view according to FIG. As shown in FIG. 20, in this embodiment, two metal pipes 66 having a circular cross section are arranged in parallel only on the lower pipe portion 63 and fixed by insert molding. Other configurations are the same as those of the eleventh embodiment.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, the following actions and effects can be obtained in addition to the actions and effects of the eleventh embodiment. That is, in this embodiment, two metal pipes 66 having a circular cross section are arranged in parallel only on the lower pipe portion 63 and fixed by insert molding, thereby forming a hot water passage 61. Therefore, the area of the hot water passage 61 in contact with the pipe 16 increases. Therefore, the heatability and heat retention of the EGR gas flowing through the pipe 16 by the engine cooling water (hot water) of the hot water passage 61 can be further improved.

<13th Embodiment>
Next, the thirteenth embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the eleventh and twelfth embodiments in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 21 shows the pipe 16 in a cross-sectional view according to FIG. As shown in FIG. 21, in this embodiment, one metal pipe 67 having an elliptical cross section is arranged only in the lower pipe portion 63 and fixed by insert molding. In the cross section shown in FIG. 21, the major axis of the metal pipe 67 is set to be about twice the outer diameter of the metal pipe 66, and is arranged parallel to the horizontal direction of the pipe 16. Further, the minor diameter of the metal pipe 67 is set to be substantially the same as the outer diameter of the metal pipe 66, and is arranged in parallel with the vertical direction of the pipe 16. Other configurations are the same as those of the eleventh and twelfth embodiments.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, one metal pipe 67 having an elliptical cross section is inserted and fixed only to the lower pipe portion 63, whereby the hot water passage 61 is formed. Therefore, the twelfth embodiment is performed. It is possible to obtain almost the same action and effect as the morphology.

<14th Embodiment>
Next, the 14th embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the ninth embodiment in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 22 shows the pipe 16 in a cross-sectional view according to FIG. As shown in FIG. 22, in this embodiment, one metal pipe 66 having a circular cross section is inserted and fixed only to the lower pipe portion 63. Here, in FIG. 22, a metal heat sink 68 having a cross-sectional waveform is provided on the upper side of the metal pipe 66 so as to be in contact with the metal pipe 66, and the heat sink 68 is integrally piped with the metal pipe 66. It is fixed by being insert-molded into. In the cross-sectional view of FIG. 22, the width of the heat sink 68 is preferably three times or more the outer diameter of the metal pipe 66. Other configurations are the same as those of the ninth embodiment.

[About the action and effect of the EGR device]
Therefore, according to the EGR device 11 of this embodiment, one metal pipe 66 and the heat radiating plate 68 in contact with the metal pipe 66 are integrally fixed to the lower pipe portion 63 of the pipe 16 by insert molding. Therefore, in addition to the operation and effect of the ninth embodiment, the heat dissipation characteristic from the metal pipe 66 to the pipe 16 can be improved by the heat sink 68.

<15th Embodiment>
Next, the fifteenth embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the ninth embodiment in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 23 shows the pipe 16 in a cross-sectional view according to FIG. As shown in FIG. 23, in this embodiment, one metal pipe 66 having a circular cross section is inserted and fixed only to the lower pipe portion 63. Here, as shown in FIG. 23, the upper side of the metal pipe 66 is exposed and arranged inside the pipe 16, that is, in the flow path through which the EGR gas flows. The metal pipe 66 of this embodiment is formed of SUS to prevent rust. Other configurations are the same as those of the ninth embodiment.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, one metal pipe 66 is insert-molded only in the lower pipe portion 63, and the upper side of the metal pipe 66 is exposed and arranged in the inner flow path of the pipe 16. Will be done. Therefore, in this embodiment, in addition to the operation and effect of the ninth embodiment, the heat of the hot water passage 61 can be directly transferred to the EGR gas flowing inside the pipe 16, and the metal pipe 66 to the pipe 16 can be directly transferred. It is possible to improve the heat dissipation characteristics to.

<16th Embodiment>
Next, the 16th embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the ninth to fifteenth embodiments in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 24 shows a part of the pipe 16 to which the metal pipe 66 is fixed by a side view. FIG. 25 shows the pipe 16 to which the metal pipe 66 is fixed by the cross-sectional view taken along the line EE of FIG. 24. As shown in FIGS. 24 and 25, the lower pipe portion 63 of the pipe 16 (middle flow passage portion MSP) has a plurality of pipe holders for holding one metal pipe 66 along the longitudinal direction of the flow path. 71 is formed integrally with the pipe 16. As shown in FIG. 25, each pipe holder 71 is configured as a set of a pair of claw portions 71a so as to sandwich the outer periphery of the metal pipe 66 from both sides. The space between the two claws 71a opens downward, and the metal pipe 66 is fitted between the two claws 71a. By being fitted into the pipe holder 71 in this way, the metal pipe 66 is held by the pipe holder 71 with respect to the lower pipe portion 63 and is fixed. In this fixed state, the metal pipe 66 is in contact with the lower outer wall of the lower pipe portion 63. The pipe holder 71 corresponds to an example of a holding means in the disclosed technique.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, the contact area of the metal pipe 66 with respect to the pipe 16 is inferior to that of the insert molding of the eleventh embodiment, but other than that, almost the same operation and effect as those of the eleventh embodiment are obtained. be able to.

Further, according to the configuration of this embodiment, the metal pipe 66 is fixed by being held by the pipe holder 71 (holding means) along the flow path longitudinal direction of the pipe 16 (middle flow passage portion MSP). In terms of resin cracks due to the difference in thermal expansion between the resin pipe 16 and the metal pipe 66 and manufacturing cost, it is superior to fixing by insert molding. Therefore, the extension of the metal pipe 66 and the degree of freedom in design can be improved.

<17th Embodiment>
Next, the 17th embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the 16th embodiment in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 26 shows a part of the pipe 16 to which the metal pipe 66 is fixed by a side view. FIG. 27 shows a pipe 16 to which the metal pipe 66 is fixed by a sectional view taken along the line FF of FIG. 26. As shown in FIGS. 26 and 27, a pipe holder 73 for holding one metal pipe 66 is provided in the lower pipe portion 63 of the pipe 16 (middle flow passage portion MSP) along the longitudinal direction thereof. .. As shown in FIG. 27, the pipe holder 73 receives the lower receiving portion 74 for receiving the lower part of the metal pipe 66, the upper receiving portion 75 for receiving the upper side of the metal pipe 66, and the lower receiving portion 74. It is composed of a plurality of clips 76 for fixing to 75. The lower receiving portion 74 extends along the longitudinal direction of the metal pipe 66 to receive the lower side of the metal pipe 66, has an arcuate cross section, and has flanges 74a on both sides. The upper receiving portion 75 projects downward from the lower pipe portion 63 to receive the upper side of the metal pipe 66, extends along the longitudinal direction of the metal pipe 66, has a recess 75a having an arcuate cross section, and has flanges 75b on both sides. Is formed. The upper half of the metal pipe 66 is fitted into the recess 75a of the upper receiving portion 75, the lower half thereof is covered with the lower receiving portion 74, and the

flanges

74a and 75b thereof are sandwiched by a plurality of clips 76. It is fixed to the pipe 16. In this fixed state, the metal pipe 66 is in contact with the lower outer wall of the lower pipe portion 63. The pipe holder 73 corresponds to an example of a holding means in the disclosed technique.

<18th Embodiment>
Next, the eighteenth embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the 16th embodiment in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 28 shows the pipe 16 to which the metal pipe 66 is fixed by a cross-sectional view according to FIG. 25. As shown in FIG. 28, in this embodiment, the metal pipe 66 held by the pipe holder 71 (holding means) and the lower pipe portion 63 of the pipe 16 extend along the metal pipe 66 and have thermal conductivity. A good heat transfer sheet 77 is provided. The heat transfer sheet 77 is formed of a flexible sheet material (for example, a rubber sheet). This embodiment differs from the 16th embodiment in this respect. The heat transfer sheet 77 corresponds to an example of a heat transfer member in the disclosed technique.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, the following actions and effects can be obtained in addition to the actions and effects of the 16th embodiment. That is, in this embodiment, the heat transfer sheet 77 is sandwiched between the metal pipe 66 held by the pipe holder 71 (holding means) and the lower pipe portion 63 (middle flow passage portion MSP) of the pipe 16. Therefore, there is no gap between the metal pipe 66 and the lower pipe portion 63, and the adhesion between the two 66 and 63 is improved. Therefore, the heat transfer property to the inner wall of the lower pipe portion 63 by the hot water flowing through the hot water passage 61 in the metal pipe 66 can be improved, the temperature rise property of the inner wall can be improved, and the inside of the pipe 16 can be improved. It is possible to improve the temperature rise property of the EGR gas flowing through the water.

Further, according to the configuration of this embodiment, even if a thermal expansion difference occurs between the metal pipe 66 and the lower pipe portion 63 due to the flexibility of the heat transfer sheet 77, heat transfer between the metal pipe 66 and the lower pipe portion 63 and the heat transfer portion 63. Adhesion with the sheet 77 is ensured. In this sense, the heat transfer property of the hot water flowing through the hot water passage 61 to the inner wall of the lower pipe portion 63 can be further improved, the temperature rise property of the inner wall can be further improved, and the EGR flowing inside the pipe 16 can be further improved. The temperature rise property of the gas can be further improved.

<19th Embodiment>
Next, the 19th embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the 17th embodiment in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 29 shows the pipe 16 to which the metal pipe 66 is fixed by a cross-sectional view according to FIG. 27. As shown in FIG. 29, in this embodiment, the metal pipe 66 is formed between the metal pipe 66 held by the pipe holder 73 (holding means) and the lower pipe portion 63 (middle flow passage portion MSP) of the pipe 16. A heat transfer sheet 77 that extends along the line and has good thermal conductivity is provided. This embodiment differs from the 17th embodiment in this respect. The heat transfer sheet 77 corresponds to an example of a heat transfer member in the disclosed technique.

[About the action and effect of the EGR device]
Therefore, according to the EGR device 11 of this embodiment, the following actions and effects can be obtained in addition to the actions and effects of the 17th embodiment. That is, in this embodiment, the heat transfer sheet 77 is sandwiched between the metal pipe 66 held by the pipe holder 73 (holding means) and the lower pipe portion 63 (middle flow passage portion MSP), so that the metal is provided. There is no gap between the pipe 66 and the lower pipe portion 63, and the adhesion between the two 66 and 63 is improved. Therefore, it is possible to improve the temperature rise property of the inner wall of the lower pipe portion 63 by the hot water flowing through the hot water passage 61 in the metal pipe 66, and improve the temperature rise property of the EGR gas flowing inside the pipe 16. can.

<20th Embodiment>
Next, the twentieth embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the eighteenth embodiment in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 30 shows the pipe 16 to which the metal pipe 66 is fixed by a cross-sectional view according to FIG. 28. As shown in FIG. 30, in this embodiment, the metal pipe 66 is held by the pipe holder 71 (holding means) in the lower pipe portion 63 (middle flow passage portion MSP) of the pipe 16, and the metal pipe 66 is a heat transfer sheet. Although it is in contact with the lower pipe portion 63 via 77, a gap 78 is provided between the claw portion 71a of the pipe holder 71 and the metal pipe 66. The gap 78 constitutes an example of an air layer (heat insulating layer) in the disclosed technique. In this respect, this embodiment is different from the eighteenth embodiment.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, the following actions and effects can be obtained in addition to the actions and effects of the 18th embodiment. That is, in this embodiment, the heat transfer sheet 77 is sandwiched between the metal pipe 66 and the lower pipe portion 63 in a state where the metal pipe 66 is held by the pipe holder 71, but the claw portion 71a and the metal pipe 66 A gap 78 is provided between the two. Therefore, when the engine is stopped, the heat escape from the metal pipe 66 to the atmosphere side is suppressed by the gap 78. Therefore, when the engine is stopped, it is possible to suppress a decrease in temperature of the inner wall of the pipe 16 (middle flow passage portion MSP). Here, when the engine is stopped, hot water does not flow through the hot water passage 61 of the metal pipe 66, but the hot water stays, so that the staying hot water becomes a heat source. Since the heat escape from the metal pipe 66 is suppressed, the temperature drop of the inner wall of the pipe 16 can be effectively suppressed. Even during engine operation, the gap 78 suppresses the escape of heat from the metal pipe 66 to the atmosphere side, and the temperature drop of the inner wall of the pipe 16 can be suppressed.

<21st Embodiment>
Next, the 21st embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the 19th embodiment in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 31 shows the pipe 16 to which the metal pipe 66 is fixed by a cross-sectional view according to FIG. 29. As shown in FIG. 31, in this embodiment, the metal pipe 66 is held by the pipe holder 73 (holding means) in the lower pipe portion 63 (middle flow passage portion MSP) of the pipe 16, and the metal pipe 66 is a heat transfer sheet. Although it is in contact with the lower pipe portion 63 via 77, a gap 78 (air layer (heat insulating layer)) is mainly provided between the lower receiving portion 74 of the pipe holder 73 and the metal pipe 66. In this respect, this embodiment is different from the 19th embodiment.

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, the following actions and effects can be obtained in addition to the actions and effects of the 19th embodiment. That is, in this embodiment, the heat transfer sheet is held between the metal pipe 66 and the lower pipe portion 63 (middle flow passage portion MSP) of the pipe 16 in a state where the metal pipe 66 is held by the pipe holder 73 (holding means). 77 is sandwiched, but a gap 78 is mainly provided between the lower receiving portion 74 and the metal pipe 66. Therefore, when the engine is stopped, the heat escape from the metal pipe 66 to the atmosphere side is suppressed by the gap 78. Therefore, when the engine is stopped, the temperature drop of the inner wall of the pipe 16 can be suppressed. Here, when the engine is stopped, hot water does not flow through the hot water passage 61 of the metal pipe 66, but the hot water stays, so that the staying hot water becomes a heat source. Since the heat escape from the metal pipe 66 is suppressed, the temperature drop of the inner wall of the pipe 16 can be effectively suppressed. Even during engine operation, the gap 78 suppresses the escape of heat from the metal pipe 66 to the atmosphere side, and the temperature drop of the inner wall of the pipe 16 can be suppressed.

<22nd Embodiment>
Next, the 22nd embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the eighteenth embodiment in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 32 shows a part of the pipe 16 to which the metal pipe 66 is fixed by a side view. FIG. 33 shows a pipe 16 to which the metal pipe 66 is fixed by a sectional view taken along the line GG of FIG. 32. As shown in FIGS. 32 and 33, in this embodiment, heat is generated between the metal pipe 66 held by the pipe holder 71 (holding means) and the lower pipe portion 63 (middle flow passage portion MSP) of the pipe 16. A heat transfer plate 79 having good conductivity is provided. In this respect, this embodiment is different from the 18th embodiment in which the heat transfer sheet 77 is provided. The heat transfer plate 79 corresponds to an example of a heat transfer member in the disclosed technique.

As shown in FIGS. 32 and 33, the heat transfer plate 79 is a metal plate and has a larger area than the heat transfer sheet 77 in order to expand the heat transfer range from the metal pipe 66 to the lower pipe portion 63. The heat transfer plate 79 is sandwiched between the metal pipe 66 and the lower pipe portion 63, and is sandwiched between the main trunk portion 79a extending along the metal pipe 66 and the adjacent pipe holder 71 between the main trunk portion 79a and the lower pipe portion 63. Includes a wing 79b extending along the outer wall of the. The main trunk portion 79a exerts the same function as the above-mentioned heat transfer sheet 77, but the wing portion 79b exerts a function of transferring the heat transferred from the metal pipe 66 to the heat transfer plate 79 to the outer wall of the lower pipe portion 63. ..

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, the following actions and effects can be obtained in addition to the actions and effects of the 18th embodiment. That is, in this embodiment, the heat transferred from the metal pipe 66 to the heat transfer plate 79 is further transferred to the outer wall of the lower pipe portion 63 via the blade portion 79b. Therefore, the temperature riser of the lower pipe portion 63 can be further improved by the amount of heat transferred to the outer wall of the lower pipe portion 63, and the temperature riser of the EGR gas flowing inside the pipe 16 can be further improved. ..

<23rd Embodiment>
Next, the 23rd embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the 19th embodiment in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 34 shows a part of the pipe 16 to which the metal pipe 66 is fixed by a side view. FIG. 35 shows the pipe 16 to which the metal pipe 66 is fixed by the cross-sectional view taken along the line HH of FIG. 34. As shown in FIGS. 34 and 35, in this embodiment, heat is generated between the metal pipe 66 held by the pipe holder 73 (holding means) and the lower pipe portion 63 (middle flow passage portion MSP) of the pipe 16. A heat transfer plate 79 having good conductivity is provided. This embodiment differs from the 19th embodiment in which the heat transfer sheet 77 is provided in this respect. The heat transfer plate 79 corresponds to an example of a heat transfer member in the disclosed technique.

As shown in FIGS. 34 and 35, the heat transfer plate 79 is sandwiched between the metal pipe 66 and the lower pipe portion 63, and is between the main trunk portion 79a extending along the metal pipe 66 and the adjacent pipe holder 73. Includes a wing portion 79b extending from the main trunk portion 79a along the outer wall of the lower pipe portion 63. The main trunk portion 79a exerts the same function as the above-mentioned heat transfer sheet 77, but the wing portion 79b exerts a function of transferring the heat transferred from the metal pipe 66 to the heat transfer plate 79 to the outer wall of the lower pipe portion 63. ..

[About the action and effect of the EGR device]
According to the EGR device 11 of this embodiment, the following actions and effects can be obtained in addition to the actions and effects of the 19th embodiment. That is, in this embodiment, the heat transferred from the metal pipe 66 to the heat transfer plate 79 is further transferred to the outer wall of the lower pipe portion 63 via the blade portion 79b. Therefore, the temperature riser of the lower pipe portion 63 can be further improved by the amount of heat transferred to the outer wall of the lower pipe portion 63, and the temperature riser of the EGR gas flowing inside the pipe 16 can be further improved. ..

<24th Embodiment>
Next, the 24th embodiment will be described in detail with reference to the drawings.

[About the configuration of the heating part]
This embodiment is different from the ninth to 23rd embodiments in the configuration of the heating unit 50 in the pipe 16. That is, FIG. 36 shows the configuration from the EGR cooler 13 to the EGR gas distributor 15 by a configuration diagram according to FIG. In the ninth to 23rd embodiments, the hot water passage 61 is provided along the flow path longitudinal direction of the pipe 16. On the other hand, in this embodiment, the inlet side heating spacer 81 is provided sandwiched between the valve outlet flange 21i and the pipe inlet flange 16e. Further, an outlet side heating spacer 82 is provided so as to be sandwiched between the pipe outlet flange 16f and the distributor inlet flange 15e. In this embodiment, a hot water passage 61 is provided along the circumferential direction of each of the

heating spacers

81 and 82. Cooling water (hot water) that has cooled the engine 1 flows through the hot water passage 61 of the inlet side heating spacer 81 and the hot water passage 61 of the outlet side heating spacer 82. The hot water passage 61 of the inlet side heating spacer 81 and the hot water passage 61 of the outlet side heating spacer 82 are connected by a hot water pipe 83, and the hot water flowing through the hot water passage 61 on the inlet side passes through the hot water pipe 83 to the hot water on the outlet side. It is designed to flow to the passage 61. In this embodiment, the

heating spacers

81 and 82 are each made of a resin material.

[About the action and effect of the EGR device]
According to the configuration of the EGR device 11 of this embodiment, the following actions and effects can be obtained unlike the ninth to 23rd embodiments. That is, in this embodiment, between the inlet side heating spacer 81 and the pipe outlet flange 16f provided sandwiched between the valve outlet flange 21i and the pipe inlet flange 16e and the distributor inlet flange 15e (passage inlet flange). A hot water passage 61 is provided along the circumferential direction of the outlet-side heating spacer 82 provided so as to be sandwiched between the two. Therefore, the EGR gas flowing through the valve outlet flange 21i and the pipe inlet flange 16e and the EGR gas flowing through the pipe outlet flange 16f and the distributor inlet flange 15e are heated by the heat of the hot water in the hot water passage 61 of the

heating spacers

81 and 82. .. In addition, the heat of the hot water flowing through the hot water passages 61 of the

heating spacers

81 and 82 passes through the front and

rear flanges

21i, 16e, 16f and 15e via the

heating spacers

81 and 82, and the flow path portion 21f of the casing 21 ( EGR valve 14 outlet side), the inlet 16a and outlet 16b of the pipe 16, and the inlet 15d of the EGR gas distributor 15, and their inner walls are heated. Therefore, the EGR gas flowing through each

portion

21i, 16e, 16f, 15e, 21f, 16a, 16b, 15d of the middle flow passage portion MSP adjacent to each

heating spacer

81, 82 can be effectively kept warm.

Here, various temperature measurement results assuming that an inlet side heating spacer 81 having a hot water passage 61 is provided between the valve outlet flange 21i and the pipe inlet flange 16e as in this embodiment will be described. FIG. 37 is a cross-sectional view showing a connection portion between the metal upstream pipe 85 and its outlet flange 85a and the resin downstream pipe 86 and its inlet flange 86a, which are the objects of measurement according to this embodiment. .. For the upstream pipe 85 and its outlet flange 85a, a metal flow path portion 21f and a valve outlet flange 21i are assumed. As the resin downstream pipe 86 and its inlet flange 86a, a resin inlet side heating spacer 81, a pipe inlet flange 16e, and a pipe 16 are assumed. A hot water passage 61 is formed in the inlet flange 86a. FIG. 38 is a cross-sectional view showing a connection portion between the metal upstream pipe 85 and its outlet flange 85a and the metal downstream pipe 87 and its inlet flange 87a, which are in inverse proportion to each other and are measurement targets. As for the metal downstream side pipe 87 and its inlet flange 87a, it is assumed that the inlet side heating spacer 81, the pipe inlet flange 16e, and the pipe 16 are made of metal. A hot water passage 61 is formed in the inlet flange 87a. Here, for example, hot water of "60 ° C." flows through the hot water passage 61 of FIGS. 37 and 38, and the temperature of the outside air around the hot water passage 61 is, for example, "25 ° C.". FIG. 39 shows (A) changes in engine speed (EGR flow rate) and (B) changes in various temperatures by time charts.

In FIG. 39B, the thick solid line shows the temperature of hot water (first hot water temperature) TW1 flowing through the hot water passage 61 of the resin inlet flange 86a, and the solid line shows the hot water passage 61 flowing through the hot water passage 61 of the metal inlet flange 87a. The temperature of hot water (second hot water temperature) TW2 is shown, the thick broken line shows the temperature of the inner wall of the resin inlet flange 86a (first inner wall temperature) TI1, and the broken line shows the temperature of the inner wall of the metal inlet flange 87a. (Second inner wall temperature) TI2 is shown, the thick one-point chain wire indicates the temperature of EGR gas flowing inside the resin inlet flange 86a (first EGR gas temperature) TG1, and the one-point chain wire is the metal inlet. The temperature of the EGR gas flowing inside the flange 87a (second EGR gas temperature) TG2 is shown, and another broken line shows the cooling water temperature THW.

As shown in FIG. 39, when the engine 1 is alternately started and stopped, the various temperatures TW1, TW2, TI1, TI2, TG1, TG2, THW are set during engine operation in which the engine speed (EGR flow rate) becomes high. When the engine is stopped and the engine speed (EGR flow rate) becomes zero, the various temperatures TW1, TW2, TI1, TI2, TG1, TG2, THW decrease.

Here, after the engine is stopped, the resin inlet flange 86a has low thermal conductivity and cooling by the outside air is suppressed, so that the heat escape from the hot water passage 61 to the outside air becomes relatively small. Therefore, the drop in the first inner wall temperature TI1 is relatively small. On the other hand, after the engine is stopped, the metal inlet flange 87a has high thermal conductivity and is easily cooled by the outside air, so that the heat escapes from the hot water passage 61 to the outside air becomes relatively large. Therefore, the drop in the second inner wall temperature TI2 becomes relatively large. In this way, by making the inlet flange 86a made of resin, the temperature rise of the inner wall thereof can be improved when the engine is running (when EGR is executed), and when the engine is stopped (when EGR is stopped), the temperature rise can be improved. It is possible to suppress the temperature drop of the inner wall. Further, by heating the EGR gas by the hot water passage 61 of the resin inlet flange 86a, the temperature drop of the inner wall of the downstream pipe 86 and the EGR gas flowing therethrough can be suppressed. In addition, the heating of the downstream side pipe 86 is not transmitted to the upstream side pipe 85.

[About another embodiment]
The disclosed technique is not limited to each of the above-described embodiments, and a part of the configuration may be appropriately modified and implemented without departing from the spirit of the disclosed technique.

(1) In each of the above-described embodiments, the heat insulating means is provided in almost all of the middle flow passage portion MSP, but it is also possible to provide the heat insulating means only in the most downstream portion of the middle flow passage portion.

(2) In each of the above embodiments, the downstream passage portion DSP of the EGR passage 12 is configured by the EGR gas distributor 15, but the downstream passage portion can also be configured by the piping of the EGR passage instead of the EGR gas distributor.

(3) In the fifth embodiment, the heat generating film 51 is provided on the inner wall of the pipe 16, but the heat generating film can also be provided on the outer wall of the pipe. Further, although the heating unit 50 is composed of the heating film 51, the heating unit can also be composed of a heating wire.

(4) In the third embodiment, as shown in FIG. 9, the casing 21 of the EGR cooler 13 is provided with the bypass passage 21g and the bypass valve 24. However, as shown in FIG. 40, the casing 21 of the EGR cooler 13 is provided. Therefore, the bypass passage 21g and the bypass valve 24 can be omitted. In this case, as shown in FIG. 40, the flow path portion 21f of the casing 21 can be made shorter than that shown in FIG. In this case, although the bypass passage 21g and the bypass valve 24 do not have the detour function of the EGR gas, other than that, the same operation and effect as those of the third embodiment can be obtained. That is, since the middle flow passage portion MSP is located downstream from the outlet 23d of the heat exchanger 23 and the EGR valve 14 and the pipe 16 are provided in the middle flow passage portion MSP, the EGR gas flowing through the EGR valve 14 and the pipe 16 is kept warm. It flows to the EGR gas distributor 15 (downstream passage portion DSP) while being kept warm by the means. Therefore, the temperature of the EGR gas can be lowered by the heat exchanger 15, and the flow path 34 and the pipe 16 (middle flow passage portion MSP) of the EGR valve 14 formed of the resin material are not melted by the EGR gas. It can be suppressed. Further, it is possible to reduce the heat transfer of the EGR gas to the resin material in the flow path 34 and the pipe 16 (middle flow passage portion MSP) of the EGR valve 14, and the EGR gas distributor 15 (downstream passage) of the EGR passage 12 can be reduced. The temperature drop of the EGR gas flowing to the part DSP) can be suppressed, and the generation of condensed water in the EGR gas distributor 15 can be suppressed. FIG. 40 shows the configuration from the EGR cooler 13 to the EGR gas distributor 15 by a configuration diagram according to FIG.

(5) In another embodiment of (4) above, as shown in FIG. 40, the assembly portion 21h provided in the casing 21 in which the bypass passage 21g and the bypass valve 24 are omitted is provided in the axial direction of the heat exchanger 23. The EGR valve 14 was attached to the EGR cooler 13 by arranging along the line and incorporating (drop-in) the casing 46 of the EGR valve 14 into the hole of the assembly portion 21h. On the other hand, as shown in FIG. 41, the assembly portion 21h provided in the casing 21 excluding the bypass passage 21g and the bypass valve 24 is arranged along the direction orthogonal to the axis of the heat exchanger 23, and the assembly thereof. The EGR valve 14 can also be attached to the EGR cooler 13 by incorporating (drop-in) the casing 46 of the EGR valve 14 into the hole of the attachment portion 21h. In this case, the total height of the EGR cooler 13 to which the EGR valve 14 is attached can be shortened, and the whole can be made compact. FIG. 41 shows the configuration from the EGR cooler 13 to the EGR gas distributor 15 by a block diagram.

(6) In the fifteenth embodiment, as shown in FIG. 23, the upper side of the metal pipe 66 is exposed and arranged inside the pipe 16, that is, in the flow path through which the EGR gas flows. On the other hand, in FIG. 42, as shown in the cross-sectional view of the pipe 16 according to FIG. 23, the heat sink 68 is arranged on the upper side of the metal pipe 66 exposed inside the pipe 16, and the heat sink 68 is placed in the flow path. It may be exposed.

(7) In the 23rd embodiment, as shown in FIG. 35, between the metal pipe 66 held by the pipe holder 73 (holding means) and the lower pipe portion 63 (middle flow passage portion MSP) of the pipe 16. , Only the heat transfer plate 79 having good thermal conductivity was provided. On the other hand, in FIG. 43, as shown in the cross-sectional view of the pipe 16 according to FIG. 35, the metal pipe 66 held by the pipe holder 73 (holding means) and the lower pipe portion 63 (middle flow passage portion MSP) of the pipe 16 ), A heat transfer plate 79 having good thermal conductivity and a heat transfer sheet 77 may be provided on top of each other. At the same time, a gap 78 (air layer (heat insulating layer)) may be provided between the lower receiving portion 74 of the pipe holder 73 and the metal pipe 66. Here, the heat transfer plate 79 is formed of metal, but since the heat transfer sheet 77 is formed of a sheet material such as flexible rubber, the heat transfer sheet 77 is sandwiched between the heat transfer plate 79 and the lower pipe portion 63. It can be brought into close contact with the metal pipe 66, and the heat transfer property from the metal pipe 66 to the lower pipe portion 63 can be improved. Further, since the gap 78 is provided between the lower receiving portion 74 and the metal pipe 66, the escape of heat from the metal pipe 66 to the atmosphere side is suppressed by the gap 78. Therefore, it is possible to suppress a decrease in temperature of the inner wall of the pipe 16.

(8) In the first embodiment, the outer housing 38 constituting the valve portion 32 is made of metal and the inner housing 39 is made of resin, but both the outer housing and the inner housing may be made of resin.

(9) In the fifth, sixth, eighth to twenty-fourth embodiments, the heat insulating coating 51, the air layer 56, the hot water passage 61 and the like are provided instead of omitting the heat insulating coat 41, but together with the heat insulating coat. It is also possible to provide a heating film, an air layer, a hot water passage, and the like.

(10) In the 22nd embodiment, only the heat transfer plate 79 having good thermal conductivity is provided between the metal pipe 66 held by the pipe holder 71 (holding means) and the lower pipe portion 63 of the pipe 16. rice field. On the other hand, as in the other embodiment of (7) above, good thermal conductivity is transmitted between the metal pipe 66 held by the pipe holder 71 (holding means) and the lower pipe portion 63 of the pipe 16. The heat plate 79 and the heat transfer sheet 77 may be provided on top of each other.

(11) In the tenth to twenty-third embodiments, and in another embodiment of the above (6), (7) and (10), the pipe 16 is composed of an upper pipe portion 62 and a lower pipe portion 63, and the lower pipe portion 16 is formed. A heating portion was provided only in the pipe portion 63. On the other hand, it is also possible to provide a heating portion only on the upper pipe portion of the pipe.

This disclosed technology can be applied to EGR devices installed in gasoline engines and diesel engines.

1 Engine 2 Intake passage 3 Exhaust passage 11 EGR device 12 EGR passage 13 EGR cooler 14 EGR valve 15 EGR gas distributor (constituting the downstream passage portion of the EGR passage)
15e Distributor inlet flange (passage inlet flange)
16 Piping (constituting the midstream passage of the EGR passage)

16a Inlet 16b Outlet

16c Outer pipe 16d Inner pipe 16e Pipe inlet flange 16f Pipe outlet flange 21c Outlet 21g Bypass passage 21ga Inlet 21gb Outlet 21i Valve outlet flange 23 Heat exchanger 23a Inlet 23b Outlet 24 Bypass valve 34 Flow path 34a Inlet 34b Outlet 41 Insulation coat (heat insulation means)
50 Heating part 51 Heat-generating film (heating part)
56 Air layer (heat insulating means)
58 Cooling section 61 Hot water passage (heating section)
66 Metal pipe 67 Metal pipe 71 Pipe holder (holding means)
73 Pipe holder (holding means)
77 Heat transfer sheet (heat transfer member)
78 Gap (air layer)
79 Heat transfer plate (heat transfer member)
81 Inlet side heating spacer 82 Outlet side heating spacer USP Upstream passage MSP Midstream passage DSP Downstream passage

Claims

In an EGR device configured to flow a part of the exhaust gas discharged from the engine to the exhaust passage as EGR gas to the intake passage through the EGR passage and return it to the engine.
The EGR passage is provided with an EGR valve for adjusting the flow rate of the EGR gas.
The EGR passage includes an upstream passage portion close to the exhaust passage, a downstream passage portion close to the intake passage, and a middle flow passage portion between the upstream passage portion and the downstream passage portion.
An EGR device characterized in that at least the most downstream portion of the middle flow passage portion is provided with a heat insulating means for retaining heat of the EGR gas flowing therethrough.
In the EGR apparatus according to claim 1,
The heat insulating means is an EGR device characterized in that the middle flow passage portion is formed of a resin material having a function of retaining heat of the EGR gas.
In the EGR apparatus according to claim 1 or 2,
The EGR device is characterized in that the heat retaining means is a heat insulating coat provided on the inner wall of the middle flow passage portion.
In the EGR apparatus according to claim 3,
The middle flow passage portion includes a pipe made of a resin material having a function of retaining heat of the EGR gas.
The EGR device is characterized in that the heat insulating coat is formed so that its thickness gradually or gradually increases from the downstream side to the upstream side of the pipe.
In the EGR apparatus according to any one of claims 1 to 4.
The EGR device is characterized in that the heat insulating means is an air layer provided outside the middle flow passage portion.
In the EGR apparatus according to any one of claims 1 to 5,
The heat insulating means is an EGR device including a heating portion for heating the middle flow passage portion.
In the EGR apparatus according to claim 6,
The EGR device is characterized in that the heating unit is a heat-generating coating that generates heat when energized.
In the EGR apparatus according to claim 6,
The EGR device is characterized in that the heating portion is formed in at least a part of the middle flow passage portion and is composed of a hot water passage through which hot water flows.
In the EGR apparatus according to claim 8,
The middle flow passage portion provided with the hot water passage includes an outer outer pipe and an inner inner pipe sandwiching the hot water passage.
An EGR device characterized in that the thickness of the outer tube is larger than the thickness of the inner tube.
In the EGR apparatus according to claim 8 or 9.
The EGR device is characterized in that the hot water passage is provided along the flow path longitudinal direction of the middle flow passage portion.
In the EGR apparatus according to claim 8 or 9.
The midstream passage portion includes the EGR valve and a pipe arranged downstream of the EGR valve.
The EGR valve and the pipe are connected via a valve outlet flange provided on the outlet side of the EGR valve and a pipe inlet flange provided on the inlet side of the pipe.
The pipe and the downstream passage portion are connected via a pipe outlet flange provided on the outlet side of the pipe and a passage portion inlet flange provided on the inlet side of the downstream passage portion.
A heating spacer is provided between the valve outlet flange and the pipe inlet flange and at least one of the pipe outlet flange and the passage portion inlet flange, and the hot water passage is provided along the circumferential direction of the heating spacer. An EGR device characterized in that it is provided.
In the EGR apparatus according to claim 8,
The EGR device is characterized in that the hot water passage is composed of a metal pipe provided along the longitudinal direction of the flow path of the middle flow passage portion.
In the EGR apparatus according to claim 12,
The EGR device, wherein the metal pipe is fixed to the middle flow passage portion by insert molding.
In the EGR apparatus according to claim 12,
The middle flow passage portion is provided with a holding means for holding the metal pipe along the longitudinal direction of the flow path.
An EGR device characterized in that the metal pipe is fixed to the middle flow passage portion by being held by the holding means.
In the EGR apparatus according to claim 14,
An EGR device characterized in that a heat transfer member is provided between the metal pipe held by the holding means and the middle flow passage portion.
In the EGR apparatus according to claim 15,
The EGR device is characterized in that the heat transfer member is a flexible heat transfer sheet that is in close contact with the metal pipe and the middle flow passage portion.
In the EGR apparatus according to any one of claims 14 to 16.
An EGR device characterized in that an air layer for heat insulation is provided between the metal pipe and the holding means.
In the EGR apparatus according to any one of claims 2 to 17.
The EGR passage is further provided with an EGR cooler for cooling the EGR gas, a bypass passage for bypassing the EGR cooler, and a bypass valve for opening and closing the bypass passage.
The EGR cooler includes a heat exchanger for cooling, and the heat exchanger includes an inlet and an outlet for the EGR gas.
The bypass passage includes an inlet and an outlet for the EGR gas.
The middle flow passage portion is located downstream of the outlet of the heat exchanger and the outlet of the bypass passage.
The EGR valve is an EGR device provided in the middle flow passage portion.
In the EGR apparatus according to claim 17 or 18.
An EGR device further provided with a cooling unit for cooling at least a part of the bypass passage.
In the EGR apparatus according to any one of claims 2 to 17.
The EGR passage is further provided with an EGR cooler for cooling the EGR gas, the EGR cooler includes a heat exchanger for cooling, and the heat exchanger includes an inlet and an outlet for the EGR gas. ,
The middle flow passage portion is located downstream from the outlet of the heat exchanger.
The EGR valve is an EGR device provided in the middle flow passage portion.
In the EGR apparatus according to any one of claims 1 to 20,
The EGR valve includes a flow path through which the EGR gas flows, and the inner wall of the flow path is made of a resin material having a function of retaining heat of the EGR gas.
In the EGR apparatus according to any one of claims 16 to 21,
The EGR apparatus, wherein the flow path of the EGR valve includes an inlet and an outlet, and the inlet of the flow path is arranged substantially adjacent to the outlet of the heat exchanger.