JP2001227413A - Shell and tube egr gas cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shell and tube EGR gas cooling device attaining reduction of assembly man-hours and reduction of a cost also enhancing heat transfer performance of a pipe unit to obtain stable heat exchange effectiveness, by forming a fin provided in the inside of a heat transfer pipe into an integral structure with the pipe unit. SOLUTION: This shell and tube EGR gas cooling device, formed in a structure arranging a heat transfer pipe group secured in a tube sheet arranged in the inside of a drum pipe in addition securing an end part cap provided with an inflow/outflow port of EGR gas to both end parts of the above drum pipe to secure a tightening flange to the above end part cap, uses a heat transfer pipe protruded to an inner side in a pipe diametric direction integrally with a pipe wall part in the inside to have a fin part continued in a pipe axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for an EGR gas using an engine coolant or the like as a refrigerant, and more particularly, to a multi-unit using a heat transfer tube provided with fins inside the tube to improve heat transfer performance. The present invention relates to a tubular EGR gas cooling device.

[0002]

2. Description of the Related Art A part of exhaust gas is taken out of an exhaust system,
To return to the intake system of the engine and add it to the mixture,
EGR (Exhaust Gas Recircula)
Tion: exhaust gas recirculation). EGR is NOx
(Nitrogen oxides) generation, pump loss reduction, heat radiation loss to the cooling fluid due to lowering of combustion gas temperature, increase in specific heat ratio due to changes in working gas amount and composition, and reduction in cycle efficiency Since many effects such as improvement can be obtained, it is an effective method for improving exhaust gas purification and thermal efficiency of an engine.

[0003] However, when the temperature of the EGR gas increases and the amount of the EGR gas increases, the heat effect of the EGR gas causes the EGR gas to increase.
It has been recognized that the durability of the valve may deteriorate, leading to premature breakage, the need for a water-cooled structure to prevent this, and the reduction in fuel efficiency due to the decrease in charging efficiency due to the rise in intake air temperature. I have. To avoid this,
A device that cools the EGR gas with a coolant of the engine or the like is used. As this device, a multi-tube heat exchanger is generally used.

FIG. 13 shows an example of a multi-tube heat exchanger used in this case. A shell tube 1 having a cooling medium inlet P1 and a cooling medium outlet P2 provided at both ends. Inside, both ends of the heat transfer tube group 2 composed of straight tubes are fixed to the sheet metal tube sheet 3 by brazing, while the outer peripheral end of the tube sheet 3 is brazed to the inner wall of the body tube 1. An end cap (bonnet) 4 provided with an EGR gas inlet 4-1 is fixed at one end of the body tube 1, and an EGR gas outlet 4 is provided at the other end. -2 provided with an end cap 4 fixed thereto, and the end cap 4
A fastening flange 5 is externally fitted and fixed to the outer opening ends of the gas inlet 4-1 and the gas outlet 4-2. Reference numeral 6 denotes a baffle plate for holding the heat transfer tube group 2.

However, in such a heat exchanger tube of a multi-tube heat exchanger, the inner peripheral surface is smooth and simple over the entire length of the heat exchanger tube in the longitudinal direction as in a normal heat exchanger. Since a circular tube is used, the EGR gas flowing into the tube flows smoothly with almost no flow resistance. As a result, the EGR gas is not stirred in the heat transfer tube, and the EGR gas is not stirred.
Heat transfer from the R gas to the heat transfer tube is not sufficient, and EGR
The gas cooling efficiency had to be low.

As a countermeasure, conventionally, there is a means for improving the heat transfer performance of the tube by providing a protrusion in the heat transfer tube to positively increase the turbulence of the gas flow. As this means, for example, a spiral ridge is formed inside the heat transfer tube, and a plate-like fin is inserted into the heat transfer tube and joined to the spiral ridge, thereby forming a spiral ridge. There is known a method of increasing turbulence of a gas flow by using plate-like fins (see Japanese Patent Application Laid-Open No. H11-108578).

[0007]

However, the above-described conventional means for improving the heat transfer performance of the tube has the following disadvantages. That is, a method of providing a plate-shaped partition plate or fins in a pipe, and a method of forming a projection by combining a spiral ridge and a plate-shaped fin, all employ a pipe body and a partition plate or a plate-shaped fin. Since the fins must be separately manufactured and assembled, and the fins are inserted into the pipe and brazed, the manufacture of the pipe body and the assembling of the pipe and the fin require a large number of man-hours and a high cost. In addition, since a brazing portion always exists between the tube and the fin, the brazing portion serves as a heat barrier, so that heat from the fin is not easily transmitted to the tube wall of the heat transfer tube. Bubbles)
The heat transfer amount is further reduced when there is, and it is difficult to obtain high heat transfer performance.

The present invention has been made in order to solve the above-mentioned problems of the conventional multi-tube heat exchanger, and has a structure in which fins provided inside the heat transfer tubes are integrated with the tube body.
It is an object of the present invention to provide a multi-pipe EGR gas cooling device that can reduce the number of assembling steps and cost, improve the heat transfer performance of a pipe, and obtain a stable heat exchange rate.

[0009]

According to the present invention, as a means for solving the above-mentioned problems, pipes are produced mainly by a method for producing a welded steel pipe such as an electric resistance welded steel pipe, a forged steel pipe or a UO steel pipe made of stainless steel, or by various methods. The fin provided inside the heat transfer tube is integrated with the tube using a method of pressing the outer wall of the tube toward the center, etc. The main point is that the cooling medium inlet near the end A heat transfer tube group is fixedly arranged on a tube sheet fixed near both ends of a body tube provided with a cooling medium outlet, and an inlet and an outlet for EGR gas are provided near both ends of the body tube. Multi-pipe type EGR having a structure in which a fixed end cap is fixed, and a fastening flange is externally fixed to an outer opening end of a gas inlet and an outlet of the end cap directly or through an EGR pipe portion. Gas cooling equipment Oite, the heat transfer tube is characterized in that comprising a fin portion continuous to the wall portion and projecting vital tube axis a tube radially inwardly integrally therein.

In the present invention, since the tube wall and the fin of the heat transfer tube are integrated, there is no heat barrier such as brazing material or voids in heat transfer from the fin to the tube wall. Therefore, not only the heat from the EGR gas flow flowing near the pipe wall but also the heat from the EGR gas flow flowing near the center of the pipe axis is quickly and reliably transmitted to the pipe wall to transfer the heat to the engine cooling water. Can be.

Further, as described above, the heat transfer tube having the tube wall portion and the fin portion integrated with each other may be an electric resistance welded steel tube, a forged steel tube or a U-welded steel tube.
Manufacturing method of welded steel pipe such as O steel pipe, multiple winding pipe manufacturing method,
Since it is manufactured using a method of pressing the outer wall of the pipe body manufactured by various methods toward the center, it is not necessary to manufacture the pipe and the fin separately, and the fin is inserted into the pipe and brazed. Work is not required, so that the number of assembly steps can be significantly reduced. Further, since the fin portion is integral with the tube wall portion, it is resistant to vibration and impact.

[0012]

FIG. 1 shows a multi-tube EGR according to the present invention.
FIG. 2 is a longitudinal sectional view showing a first embodiment of the heat transfer tube in the gas cooling device, FIG. 2 is a longitudinal sectional view showing a second embodiment of the heat transfer tube in the same manner,
FIG. 3 is a longitudinal sectional view showing a third embodiment of the heat transfer tube, and FIG.
Is a longitudinal sectional view showing a fourth embodiment of the heat transfer tube, FIG. 5 is a longitudinal sectional view showing a fifth embodiment of the heat transfer tube, and FIG. 6 is a longitudinal sectional view showing a sixth embodiment of the heat transfer tube. 7 is a longitudinal sectional view showing a seventh embodiment of the heat transfer tube, FIG. 8 is a longitudinal sectional view showing an eighth embodiment of the heat transfer tube, and FIG.
FIG. 10 is a longitudinal sectional view showing an embodiment, and FIG.
FIG. 11 is a longitudinal sectional view showing an embodiment, and FIG.
FIG. 12 is a longitudinal sectional view showing an embodiment, and FIG.
It is a longitudinal section showing an example.

As shown in FIG. 13, the multi-tube type EGR gas cooling apparatus according to the present invention has a cooling medium inlet port P1 and a cooling medium outlet port P2 at both ends.
Inside 1, both ends of a heat transfer tube group 2 composed of straight tubes are fixed to a sheet metal tube sheet 3 by brazing, while the outer peripheral end of the tube sheet 3 is brazed to the inner wall of the body tube 1. An end cap (bonnet) 4 provided with an EGR gas inlet 4-1 is fixed at one end of the body tube 1, and an EGR gas outlet is provided at the other end. End cap 4 provided with 4-2
And a structure similar to the structure in which the fastening flange 5 is externally fitted and fixed to the outer opening ends of the gas inlet 4-1 and the gas outlet 4-2 of the end cap 4. is there.

Here, a heat transfer tube used in the multi-tube type EGR gas cooling device will be described with reference to FIGS. The heat transfer tube 2a shown in FIG. 1 has a fin having a length slightly shorter than the inner diameter of the tube, which is integrally formed with the tube wall 2a-1 and projects inward in the radial direction of the tube and has a length slightly shorter than the inner diameter of the tube. Part 2
a-2, and its manufacturing method is hoop material (SU
When S316L or the like is formed into a cylindrical shape by roll forming, one end side of the hoop material is bent in the inner radial direction by a predetermined length to form a fin portion 2a-2, and the fin portion 2a-2 is formed.
The hoop is manufactured by joining the other end of the hoop material to the base of the hoop using, for example, a TIG welding method. 2a-3 is a weld bead.

The heat transfer tube 2b shown in FIG.
-1 is projected inward in the radial direction of the pipe in a direction slightly longer than the inner diameter of the pipe, and its tip is bent along the inner wall of the pipe so as to divide the pipe into two chambers. It has a fin portion 2b-2 which is continuous in the axial direction, and its manufacturing method is such that when a hoop material with brazing material plating is formed at least at one end side into a cylindrical shape by roll forming, one end side of the hoop material is directed inward. Bend a predetermined length and fin 2b-
2, and the other end of the hoop material is joined to the base of the fin portion 2b-2 by using, for example, a TIG welding method, and then the distal bent portion 2b-3 of the fin portion 2b-2 is attached to the inner wall of the pipe. Manufactured by brazing. 2a-4 is a weld bead and 2b-5 is a brazing part.

The heat transfer tube 2c shown in FIG. 3 is integrally formed with the tube wall portion 2c-1 and projects a little shorter than the inside diameter of the tube inward in the tube radial direction and is continuous with the tube axial direction in the same manner as the tube shown in FIG. A fin portion 2c-2 having a length slightly shorter than the inner diameter of the pipe, and a lap portion provided at the joint portion. The method for producing the hoop material is as follows. Is bent inward by a predetermined length to form a fin portion 2c-2, and the other end of the hoop material is overlapped on the base of the fin portion 2c-2 to form a wrap portion 2c-3. It is manufactured by joining the parts using a TIG welding method or the like and then performing a die drawing to eliminate the step of the lap part and to smooth the outer peripheral surface of the pipe. 2c-4 is a weld bead. It is more preferable to use a hoop material plated with a brazing material and braze the wrap portion 2c-3.

A heat transfer tube 2d shown in FIG.
-1 which has a long fin portion 2d-2 and a short fin portion 2d-3 which protrude inward in the pipe diameter direction and are continuous in the pipe axis direction, and which are continuous with the pipe axis direction. When the hoop material is formed into a cylindrical shape by roll forming, both ends of the hoop material are long,
The other is bent inward shortly and fins 2d-2 and 2d-3
And the joints are joined by using a TIG welding method or the like. 2d-4 is a weld bead. The short fin portion 2d-3 may have the same length as the long fin portion 2d-2 as shown by a two-dot chain line. Also, if a hoop material plated with a brazing material is used and the short fin portion 2d-3 is brazed, More preferred.

The heat transfer tube 2e shown in FIG.
-1 which has a bent fin portion 2e-2, 2e-3 which projects inward in the pipe diameter direction and is formed in a forked shape and is continuous in the pipe axis direction, and is long in the pipe diameter direction. When the hoop material is formed into a cylindrical shape by roll forming, both ends of the hoop material are each bent inward, and the tip portion is further bent in a fork shape to form the fin portions 2e-2 and 2e-3. Formed and its seam is TI
It is manufactured by joining using a G welding method or the like.
2e-4 is a weld bead. It is more preferable to use a hoop material plated with a brazing material and braze both fin portions 2e-2 and 2e-3.

The heat transfer tube 2f shown in FIG.
-1 and a bifurcated fin portion 2f-2, 2 protruding inward in the pipe diameter direction and continuous in the pipe axis direction, and long in the pipe diameter direction.
When the hoop material is formed into a cylindrical shape by roll forming, both ends of the hoop material are each bent inward into a forked shape to form a fin portion 2f-2,
It is manufactured by forming 2f-3 and joining the joint thereof using a TIG welding method or the like. 2f-4 is a weld bead.

The heat transfer tube 2g shown in FIG.
-1 having a fin portion 2g-2 having an S-shaped cross section, which protrudes inward in the pipe diameter direction and is continuous with the pipe axis direction and is provided with a lap portion at a joint portion. When the hoop material plated with the brazing material is formed into a cylindrical shape by roll forming, one end side of the hoop material is bent inward into an S-shaped cross section to form a fin portion 2g-2, and the fin portion 2g-2 is formed. The other end of the hoop material is overlapped on the base to form a wrap portion 2g-3, and the wrap portion is joined using a TIG welding method or the like, and then the tip of the fin portion 2g-2 is brazed to the inner wall of the pipe. Thereafter, a die is drawn to eliminate the step of the lap portion and to smooth the outer peripheral surface of the tube. 2g-4 is a weld bead and 2g-5 is a brazing part.

The heat transfer tubes 2a to 2g shown in FIGS.
Is an example of a method in which a fin portion is formed when a pipe is roll-formed and a joint portion thereof is joined by using a TIG welding method or the like to manufacture the heat transfer tube. In 2h to 2j, a method of forming a fin portion by using a method of pressing the outer wall of a pipe body having a predetermined diameter in advance toward the center is used. That is, the heat transfer tube 2h shown in FIG. 8 is integrally formed with the tube wall portion 2h-1 and protrudes inward in the tube diameter direction, and is continuous in the tube axis direction, and has a double fin portion 2h-2 long in the tube diameter direction. The manufacturing method is based on the tube wall 2h-1 of a tube previously formed to a predetermined diameter.
Is pressed toward the center to form 2h-2 of a double structure having a length slightly shorter than the inner diameter of the tube. It is more preferable to braze the fin portions 2h-2 to each other by plating a brazing material on the outer surface side of the tube wall 2h-1 in advance.

The heat transfer tube 2i shown in FIG. 9 has a tube wall 2i inside.
And a pair of fins 2i-2 having a pair of diametrically long tubes extending inward in the pipe diameter direction and continuous in the pipe axis direction and opposed to each other on the diameter line. By pressing two opposing locations on the diameter line of the pipe wall 2i-1 of the pipe body previously formed to a predetermined diameter toward the center of the pipe, the pipe wall 2i-1 is pressed on the diameter line having the same length as the pipe radius. It is manufactured by forming a pair of double fin portions 2i-2 opposed to each other. It is more preferable to use a hoop material plated with a brazing material and braze the fin portions 2i-2.

The heat transfer tube 2j shown in FIG.
It has three fin portions 2j-2, which are integrally formed with j-1 and protrude at an interval of 120 degrees in the pipe diameter direction and are continuous in the pipe axis direction and have a long structure in the pipe diameter direction which is long in the pipe diameter direction. By pressing three places on the outer peripheral surface of the pipe body 2j-1 of the pipe body having a predetermined diameter at intervals of 120 degrees toward the center of the pipe, the pipe wall 2j-1 has a length substantially equal to the pipe radius. It is manufactured by forming three fin portions 2j-2 having a double structure. It is more preferable to use a hoop material plated with a brazing material and braze the fin portions 2j-2.

The heat transfer tubes 2k and 2l shown in FIGS. 11 and 12 are manufactured by the double winding method. The heat transfer tube 2k shown in FIG. 11 has a tube wall 2k-1 of a double winding tube inside. A fin portion 2k-2 projecting a little shorter than the inner diameter of the pipe in the radial direction of the pipe and being continuous in the axial direction of the pipe and having a length slightly shorter than the inner diameter of the pipe
In the manufacturing method, when plastically deforming a hoop material having a brazing material on its surface into a tubular body, the inner end portion of the double-wound tubular body is bent by a predetermined length in an inner radial direction. Fin part 2
k-2 is formed, and in this state, the brazing material between the walls of the double wound tube is heated and melted, and then the molten brazing material is cooled and solidified.

The heat transfer tube 2l shown in FIG. 12 is integrally formed with the tube wall 21-1 of the double-wound tube and protrudes in the radial direction of the tube, and its tip is bent along the inner wall of the tube to make the inside of the tube into two chambers. Fins 2 which are brazed so as to be separated and which are continuous in the pipe axis direction
When the hoop material whose surface is brazed is plastically deformed into a tubular body, the inside end of the double-wound tubular body has a predetermined length in the inner radial direction. The fin portion 21-2 is formed by bending and overlapping the tip portion with the inner wall, and in this state, the brazing material between the walls of the double wound tube is heated and melted, and then the molten brazing material is melted. Is produced by cooling and solidifying. The brazing may be performed when the heat transfer tube is manufactured, but it is preferable to perform the brazing at a time when the EGR gas cooling device is assembled.

[0026]

As described above, the multi-tube EGR gas cooling device according to the present invention uses the heat transfer tube in which the tube wall and the fin are integrated, so that the heat transfer from the fin to the tube wall can be achieved. Since there is no thermal barrier such as brazing material or voids (bubbles), not only the heat from the EGR gas flow flowing near the pipe wall, but also the heat from the EGR gas flow flowing near the center of the pipe axis quickly to the pipe wall. As a result, the heat can be transferred to the engine cooling water and the heat transfer performance can be improved.
In addition, the heat transfer tube having an integral structure of the tube wall and the fin portion is manufactured by a method of manufacturing a welded steel pipe such as an electric resistance welded steel pipe, a forged steel pipe, a UO steel pipe, a multiple winding pipe manufacturing method, or a pipe manufactured by various methods. Manufacture using the method of pressing the outer wall of the body toward the center, etc., so there is no need to manufacture the tube and fin separately, and the work of inserting the fin into the tube and brazing is unnecessary, so the assembly man-hour Can be greatly reduced, and the manufacturing cost can be reduced. Further, since the fin portion is integral with the tube wall portion and also functions as a rib of the fin, it has effects such as excellent vibration resistance.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a heat transfer tube in a multi-tube EGR gas cooling device according to the present invention.

FIG. 2 is a longitudinal sectional view showing a second embodiment of the heat transfer tube.

FIG. 3 is a longitudinal sectional view showing a third embodiment of the heat transfer tube.

FIG. 4 is a longitudinal sectional view showing a fourth embodiment of the heat transfer tube.

FIG. 5 is a longitudinal sectional view showing a fifth embodiment of the heat transfer tube.

FIG. 6 is a longitudinal sectional view showing a sixth embodiment of the heat transfer tube.

FIG. 7 is a longitudinal sectional view showing a seventh embodiment of the heat transfer tube.

FIG. 8 is a longitudinal sectional view showing an eighth embodiment of the heat transfer tube.

FIG. 9 is a longitudinal sectional view showing a ninth embodiment of the heat transfer tube.

FIG. 10 is a vertical sectional view showing a tenth embodiment of the heat transfer tube.

FIG. 11 is a longitudinal sectional view showing an eleventh embodiment of the heat transfer tube.

FIG. 12 is a longitudinal sectional view showing a twelfth embodiment of the heat transfer tube.

FIG. 13 is a cross-sectional plan view showing an example of a conventional multi-tube EGR gas cooling device to which the present invention is applied, omitting a central portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Body tube (shell) 2 Heat transfer tube group 2a-2l Heat transfer tube 3 Tube sheet 4 End cap (bonnet) 4-1 EGR gas inlet 4-2 EGR gas outlet 5 Fastening flange 6 Baffle plate P1 Coolant flow Inlet P2 Cooling medium outlet

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[Procedure amendment]

[Submission date] March 10, 2000 (200.3.1.1)
0)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

FIG. 3

FIG. 4

FIG. 5

FIG. 6

FIG. 7

FIG. 8

FIG. 9

FIG. 10

FIG. 11

FIG.

FIG. 13

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Tadahiro Goto 1200 Harada, Fuji-shi, Shizuoka F-term (reference) 3G062 ED08 GA08 GA10

Claims (1)

[Claims] 1. A heat transfer tube group is fixedly arranged on a tube sheet fixed near both ends of a body tube provided with a cooling medium inlet and a cooling medium outlet near an end, and furthermore, both ends of the body tube An end cap provided with an inlet and an outlet for the EGR gas is fixed in the vicinity, and a fastening flange is externally fixed to the outer opening end of the gas inlet and the outlet of the end cap. In the multi-tube EGR gas cooling apparatus, the heat transfer tube has a fin portion integrally formed with a tube wall portion and protruding inward in the tube radial direction and continuous in the tube axis direction. EGR gas cooling device.