Egr device for internal combustion engine

Abstract

Provided is an EGR device that allows an EGR valve to be removed with ease even when the EGR valve is provided adjacent to a turbocharger. The EGR device includes a first connecting pipe portion ( 41 b ) extending from a compressor of the turbocharger and having a first annular shoulder surface ( 41 c ) at a base end thereof, an EGR valve ( 65 ) fixedly attached to a part of the engine, a joint member ( 71 ) including a flange ( 71 a ) attached to the EGR valve ( 65 ) and a second connecting pipe portion ( 71 b ), and opposing the first connecting pipe portion in a coaxial relationship, the second connecting pipe portion being provided with a second annular shoulder surface ( 71 c ) at a base end thereof, and a flexible pipe member ( 72 ) having a first end fitted onto the first connecting pipe portion and a second end fitted onto the second connecting pipe portion. A distance (L 2 ) between the two annular shoulder surfaces is greater than a length (L 1 ) of the flexible pipe member by a prescribed distance.

1 . An EGR device for a multiple-cylinder engine equipped with a supercharger for returning a part of exhaust gas expelled from an exhaust system of the engine to an intake system of the engine, comprising:
 a first connecting pipe portion extending from a compressor of the supercharger and having a first annular shoulder surface at a base end thereof;   an EGR valve fixedly attached to a part of the engine;   a joint member including a flange attached to the EGR valve and a second connecting pipe portion defining a passage communicating with an inlet end of the EGR valve, and opposing the first connecting pipe portion in a coaxial relationship, the second connecting pipe portion being provided with a second annular shoulder surface at a base end thereof; and   a flexible pipe member having a first end fitted onto the first connecting pipe portion and a second end fitted onto the second connecting pipe portion;   wherein a distance between the two annular shoulder surfaces is greater than a length of the flexible pipe member by a prescribed distance.   
     
     
         2 . The EGR device according to  claim 1 , wherein the supercharger consists of a turbocharger including a turbine for powering the compressor and attached to a part of the engine such that the compressor projects from an exhaust side part of the engine beyond a cylinder row end part of the engine, and the first connecting pipe portion, the EGR valve, the flexible pipe member and the second connecting pipe portion extend from the compressor along the cylinder row end part of the engine. 
     
     
         3 . The EGR device according to  claim 2 , further comprising an upstream EGR pipe assembly communicating a part of the exhaust system to the inlet end of the EGR valve, the upstream EGR pipe assembly including a part extending generally vertically along the cylinder row end part of the engine toward a downstream part of the exhaust system of the engine. 
     
     
         4 . The EGR device according to  claim 3 , wherein an exhaust gas purification device is positioned on an exhaust side of the engine under the turbine, and an upstream end of the upstream EGR pipe assembly is connected to a downstream part of the exhaust gas purification device. 
     
     
         5 . The EGR device according to  claim 4 , wherein the upstream EGR pipe assembly extends generally upward from the upstream end thereof between the engine and the exhaust gas purification device, and along the cylinder row end part of the engine toward the intake side of the engine before doubling back toward the exhaust side of the engine and being connected to the inlet end of the EGR valve. 
     
     
         6 . The EGR device according to  claim 5 , wherein the upstream EGR pipe assembly comprises an EGR cooler. 
     
     
         7 . The EGR device according to  claim 6 , wherein the upstream EGR pipe assembly includes a rigid pipe member connected between the EGR cooler and the EGR valve. 
     
     
         8 . The EGR device according to  claim 7 , wherein a plurality of threaded bolts are passed through a flange provided on a downstream end of the rigid pipe member of the upstream EGR pipe assembly, the EGR valve and the joint member to fasten these components to one another. 
     
     
         9 . The EGR device according to  claim 8 , wherein the threaded bolts include at least a pair of stud bolts each having a base end threaded into one of the flange of the rigid pipe member and the flange of the joint member, and a free end having a threaded portion having a nut fastened thereon. 
     
     
         10 . The EGR device according to  claim 9 , wherein the free end of each stud bolt is provided with a tool engagement feature. 
     
     
         11 . The EGR device according to  claim 9 , wherein the threaded portion on the free end of each stud bolt is provided with a length at least twice as long as a thickness of the nut. 
     
     
         12 . The EGR device according to  claim 9 , wherein a first gasket is interposed between the flange of the rigid pipe member of the upstream EGR pipe assembly and the EGR valve, and a second gasket is interposed between the EGR valve and the joint member, and wherein the distance between the two annular shoulder surfaces is greater than the length of the flexible pipe member at least by a combined thickness of the two gaskets in an unused state. 
     
     
         13 . The EGR device according to  claim 9 , wherein each end of the flexible pipe member is secured onto the corresponding connecting pipe portion with a hose band.