JP2000045884A - Egr cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the heat exchange efficiency and to prevent thermal deformation of tubes by allowing cooling water to flow uniformly in the shell with no stagnation. SOLUTION: A plurality of cooling water feed holes 15 are formed at circumferential positions in the vicinity of one axial end of a shell 1, and an annular cooling water supply chamber 14 is provided in the vicinity of the one axial end of the shell 1 so that the plurality of cooling water feed holes 15 are covered thereby, and a plurality of cooling water discharge holes 17 are bored at circumferential positions in the vicinity of the other axial end of the shell 1, and an annular cooling water discharge chamber 16 is formed around the shell 1 in the vicinity of the other axial end of the latter so that the plurality of cooling water discharge holes 17 are covered thereby. With this arrangement, cooling water 9 fed into the chamber 15 flows into the shell 1 through the supply holes 15, being uniformly distributed, and then uniformly flows toward the discharge holes 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EGR cooler which is attached to an EGR device for recirculating exhaust gas of an engine to reduce the generation of nitrogen oxides and cools the exhaust gas for recirculation.

[0002]

2. Description of the Related Art Conventionally, an EGR device for reducing the generation of nitrogen oxides by recirculating a part of exhaust gas from an engine of an automobile or the like to the engine has been known.
In the device, when the exhaust gas recirculated to the engine is cooled, the temperature of the exhaust gas is reduced and its volume is reduced, so that the combustion temperature is reduced without significantly lowering the output of the engine and the nitrogen oxidation is effectively performed. In order to reduce the generation of substances, some engines are equipped with an EGR cooler for cooling the exhaust gas in the middle of a line for recirculating the exhaust gas to the engine.

FIG. 4 is a cross-sectional view showing an example of the EGR cooler. In the figure, reference numeral 1 denotes a cylindrical shell, and at both ends in the axial direction of the shell 1, the end faces of the shell 1 are closed. The plates 2 and 2 are fixed to each other, and both ends of a large number of tubes 3 are fixed to the respective plates 2 and 2 in a penetrating state.
Extends in the axial direction.

In the vicinity of one end of the shell 1,
A cooling water inlet pipe 4 is attached from the outside, and a cooling water outlet pipe 5 is attached from the outside near the other end of the shell 1, and cooling water 9 flows from the cooling water inlet pipe 4 into the shell 1. The supplied water flows outside the tube 3 and is discharged from the cooling water outlet pipe 5 to the outside of the shell 1.

Further, bonnets 6 and 6 formed in a bowl shape are fixed to the opposite sides of the shells 1 of the plates 2 and 2 so as to cover the end faces of the plates 2 and 2, respectively. The exhaust gas inlet 7 is provided at the center of the bonnet 6, and the exhaust gas outlet 8 is provided at the center of the other bonnet 6, respectively.
After the exhaust gas 10 of the engine enters the inside of one bonnet 6 from the exhaust gas inlet 7 and is cooled by heat exchange with the cooling water 9 flowing outside the tubes 3 while passing through a number of tubes 3, the other one is cooled. The exhaust gas is discharged into the bonnet 6 and recirculated from the exhaust gas outlet 8 to the engine.

[0006]

However, in such a conventional EGR cooler, the cooling water 9 supplied to the inside of the shell 1 from the cooling water inlet pipe 4 uniformly cools the internal cross section of the shell 1. There is a problem that the cooling water does not flow toward the water outlet pipe 5. As shown by a path 11, after flowing into the inside of the shell 1 from the cooling water inlet pipe 4, the cooling water is bent toward the cooling water outlet pipe 5 and cooled obliquely. The flow toward the water outlet pipe 5 becomes the main flow, and the cooling water 9 stagnates near the corner on the side facing the cooling water inlet pipe 4 and the cooling water outlet pipe 5 in the shell 1 to form the cooling water stagnation portion 12. Therefore, the heat exchange efficiency in the vicinity of the cooling water stagnation portion 12 is deteriorated, and there is a possibility that the temperature of the tube 3 becomes locally high in this portion, causing thermal deformation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and aims to improve heat exchange efficiency and prevent thermal deformation of a tube by allowing cooling water to flow evenly without stagnating in a shell. It is an object.

[0008]

SUMMARY OF THE INVENTION The present invention provides a shell formed in a cylindrical shape, a plate fixed to both ends of the shell in the axial direction so as to close a shell end face, and a plate on the opposite side of the plate from the shell. A bonnet fixed so as to enclose the end surface; and a tube extending in the axial direction inside the shell and having both ends penetratingly fixed to the respective plates, for supplying and discharging cooling water to the inside of the shell. An EGR cooler configured to exchange heat between the exhaust gas and the cooling water by passing exhaust gas from one bonnet side to the other bonnet side in the tube, wherein the EGR cooler is located near one axial end of the shell. Cooling water supply holes are drilled at a plurality of locations in the circumferential direction, and a cooling water supply chamber is provided in an annular shape on the outer periphery near one axial end of the shell so as to cover the cooling water supply holes, Cooling water discharge holes are formed at a plurality of locations in the circumferential direction near the other end in the axial direction of the shell, and a cooling water discharge chamber is provided on the outer periphery near the other end in the axial direction of the shell so as to cover each of the cooling water discharge holes. Are provided in an annular shape.

When the cooling water is introduced into the cooling water supply chamber at one end in the axial direction of the shell, the cooling water that has spread over the entire circumference in the cooling water supply chamber is formed at a plurality of locations in the circumferential direction. The cooling water is supplied from the cooling water supply hole to the inside of the shell in a distributed manner and flows evenly through the shell toward the cooling water discharge holes formed at a plurality of circumferential positions at the other axial end of the shell. Since the cooling water is discharged from the cooling water discharge hole into the cooling water discharge chamber and collected, the cooling water does not stagnate in the shell and a cooling water stagnation portion does not occur.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an example of the embodiment of the present invention. The same parts as those in FIG. 4 are denoted by the same reference numerals.

In the EGR cooler of this embodiment, cooling water supply holes 15 are formed at a plurality of circumferential positions near one axial end of the shell 1 (near the right end in FIG. 1). A cooling water supply chamber 14 is provided in an annular shape on the outer periphery near one axial end of the shell 1 so as to enclose the cooling water supply chamber 14, and a cooling water inlet pipe 4 is attached to an upper portion of the cooling water supply chamber 14.

On the other hand, the vicinity of the other end of the shell 1 in the axial direction (FIG. 1)
(In the vicinity of the left end in FIG. 3), cooling water discharge holes 17 are formed at a plurality of positions in the circumferential direction, and a cooling water discharge chamber 16 is provided on the outer periphery near the other axial end of the shell 1 so as to cover each of the cooling water discharge holes 17. A cooling water outlet pipe 5 is attached to the upper part of the cooling water discharge chamber 16.

In the illustrated example, the cooling water inlet pipe 4
The cooling water supply hole 15 drilled in the upper half of the shell 1 close to the cooling water supply hole 1 drilled in the lower half
The cooling water discharge holes 17 formed in the shell 1 near the cooling water outlet pipe 5 are all the same size, and the cooling water 9 is made as uniform as possible at each position in the circumferential direction. Considered to be supplied and discharged. The sizes and arrangements of the cooling water supply holes 15 and the cooling water discharge holes 17 have various optimal combinations depending on the size of the EGR cooler, and can be appropriately changed.

Thus, the exhaust gas 10 of the engine is dispersed from the exhaust gas inlet 7 through the inside of one bonnet 6 and passes through a number of tubes 3 to enter the inside of the other bonnet 6. While cooling water is recirculated from the exhaust gas outlet 8 to the engine, the cooling water 9 is supplied from the cooling water inlet pipe 4 to the cooling water supply chamber 14, spreads over the entire circumference of the shell 1, and is provided at a plurality of circumferential locations in the circumferential direction. The water is dispersed and flows into the inside of the shell 1 from the supply hole 15, and flows evenly through the shell 1 toward the cooling water discharge holes 17 formed at a plurality of circumferential positions at the other axial end of the shell 1. The cooling water is discharged from the cooling water discharge holes 17 into the cooling water discharge chamber 16 and collected from the cooling water outlet pipe 5.
The cooling water 9 does not stagnate in the inside of the cooling water and a cooling water stagnation portion does not occur.
Is efficiently exchanged with the cooling water 9 over the entire region in the longitudinal direction of the tube 3 to be cooled well.

Therefore, according to the above embodiment, since the cooling water 9 can flow evenly over the internal cross section of the shell 1 without stagnating in the shell 1, heat exchange between the exhaust gas 10 and the cooling water 9 can be achieved. Efficiency can be greatly improved, and local high temperature of the tube 3 can be avoided to reliably prevent thermal deformation.

FIG. 3 shows another embodiment of the present invention.
In this embodiment, the outer peripheral portion of the plate 2 is expanded radially outward to protrude more than the diameter of the shell 1 and refracted inward in the axial direction of the shell 1 to extend the required length and then radially inward. Again when it hits the outer periphery of the shell 1, and is bent again inward in the axial direction of the shell 1 to extend the required length.
The plate 2 and the cooling water supply chamber 14 and the other plate 2 and the cooling water discharge chamber 16 are integrally formed by welding or the like to the outer periphery of the plate, respectively. 2 is formed at an appropriate position on the end surface on the side opposite to the shell 1, and the stepped portion 2a is formed.
The fixed side end of the bonnet 6 is fitted to the outside and fixed from the outside by welding or the like.

By doing so, the above-described FIG.
The fixed side end of the bonnet 6 is
It is not necessary to consider a margin for fitting to the both ends of the cooling water supply chamber, and the cooling water supply chamber 14 and the cooling water discharge chamber 16 can be arranged as close as possible to each plate 2. In addition, the flow of the cooling water 9 can be surely spread to a position near the end of the tube 3 in the longitudinal direction, and the stagnation of the cooling water 9 can be more reliably prevented.

It should be noted that the EGR cooler of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

[0020]

According to the above-described EGR cooler of the present invention, since the cooling water can flow evenly to the internal cross section of the shell without causing stagnation in the shell, the heat exchange efficiency between the exhaust gas and the cooling water can be improved. Can be greatly improved, and an excellent effect of avoiding local high temperature of the tube and reliably preventing thermal deformation can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a sectional view showing an example of a conventional EGR cooler.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shell 2 Plate 3 Tube 6 Bonnet 9 Cooling water 10 Exhaust gas 14 Cooling water supply chamber 15 Cooling water supply hole 16 Cooling water discharge chamber 17 Cooling water discharge hole

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoji Yamashita 6-28, Owada-machi, Hachioji-shi, Tokyo F-term in Sankyo Radiator Co., Ltd.

Claims (1)

[Claims] 1. A shell formed in a cylindrical shape, a plate fixed to both ends in the axial direction of the shell so as to close a shell end face, and a plate fixed to the opposite side of the plate to cover the plate end face. And a tube extending axially through the inside of the shell and having both ends penetratingly fixed to the respective plates, for supplying and discharging cooling water to the inside of the shell and having one inside the tube. An EGR cooler configured to exchange heat between the exhaust gas and the cooling water by passing the exhaust gas from the bonnet side to the other bonnet side, and to supply cooling water to a plurality of circumferential positions near one axial end of the shell. A cooling water supply chamber is provided in an annular shape on the outer periphery near one axial end of the shell so as to cover each of the cooling water supply holes, and the other end near the other axial end of the shell. Cooling water discharge holes are formed at a plurality of locations in the circumferential direction in the vicinity, and a cooling water discharge chamber is provided in an annular shape around the other end in the axial direction of the shell so as to cover each of the cooling water discharge holes. EGR cooler.