KR20170029309A

KR20170029309A - Low Resistance and High Efficiency EGR Cooler

Info

Publication number: KR20170029309A
Application number: KR1020150126492A
Authority: KR
Inventors: 김창연; 서정일
Original assignee: 이래오토모티브시스템 주식회사
Priority date: 2015-09-07
Filing date: 2015-09-07
Publication date: 2017-03-15

Abstract

The present invention relates to a low-resistance, high-efficiency EGR cooler, and more particularly, to a cooler for an EGR system for reducing noxious gas, in which a streamlined dimple is formed in a tube constituting a part of an EGR cooler, And an EGR cooler capable of having a heat exchange ratio.
According to an embodiment of the present invention, there is provided an EGR tube having both ends opened and an EGR gas flowing therein, wherein a plurality of dimples are formed in the EGR tube from the outside to the inside, There is provided an EGR cooler formed in a streamline shape along the longitudinal direction of the EGR tube so as to reduce pressure loss.
According to an embodiment of the present invention, a plurality of EGR tubes, both ends of which are opened and EGR gas flows into the EGR tube, and a plurality of EGR tubes are stacked in the body, and an engine cooling water inlet and an outlet are provided on one side Wherein the EGR tube is formed with a plurality of dimples which are recessed from the outside to the inside, and the dimples are formed in a streamline shape along the longitudinal direction of the EGR tube so as to have a substantially S shape. EGR cooler.

Description

Low Resistance and High Efficiency EGR Cooler [

The present invention relates to a low-resistance, high-efficiency EGR cooler, and more particularly, to a cooler for an EGR system for reducing noxious gas, in which a streamlined dimple is formed in a tube constituting a part of an EGR cooler, And an EGR cooler capable of having a heat exchange ratio.

In general, diesel engines are more fuel efficient than gasoline and are widely used in commercial vehicles such as passenger cars, buses, trucks, and the whole industry. However, the exhaust gas of diesel engine vehicles contains harmful substances such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). Nitrogen oxides (NOx) are generated by the combination of oxygen and nitrogen at high pressure and high temperature, which causes corrosion of buildings and destruction of ecosystems as a major cause of acid rain, and causes human respiratory diseases such as bronchitis, pneumonia and asthma .

Korea follows the European standards as a standard for exhaust gas regulation of automobiles, and regulations are being tightened in line with the standards of Euro 6, which will be applied from 2014 (for commercial vehicles to 2015). According to Euro 6, for example, the allowable emission of nitrogen oxides (NOx) should be reduced to 0.4 g / kWh or less for medium and large diesel commercial vehicles.

In order to suppress such nitrogen oxides, an exhaust gas recirculation (EGR) system is widely used in which a part of the exhaust gas discharged into the atmosphere is supplied to the intake system side again to lower the maximum combustion temperature and reduce the supply of oxygen to reduce the production of nitrogen oxides .

In the EGR system, the combustion state of the fuel depends on the amount of the exhaust gas that is supplied to the intake system side part of the exhaust gas discharged to the atmosphere, thereby affecting the nitrogen oxide (NOx) contained in the engine output and the exhaust gas.

In addition, the amount of recirculated gas as well as the temperature of the recirculated exhaust gas are very important. This is because cooling the recirculated gas to lower the combustion temperature has an effect of reducing nitrogen oxides.

As described above, in the EGR system, the amount and temperature of the exhaust gas returned to the engine are important. The control of the amount of the exhaust gas (hereafter referred to as "EGR gas") returned here is the EGR valve, It is an EGR cooler of a cooled exhaust-gas recirculation (CEGR).

A typical EGR cooler is configured such that the recirculated EGR gas flows in a staggered manner inside the pipe and exchanges heat with cooling water at the widest surface area as compared to the length of the EGR cooler.

1 is a perspective view of an offset-fin for an EGR cooler according to the prior art. 2 is a front view of an EGR cooling tube equipped with an offset pin for an EGR cooler according to the related art.

Referring to FIGS. 1 and 2, there is shown an offset pin 10 commonly used in a conventional heat exchanger and an EGR cooling tube using the offset pin 10. The EGR gas flows along a flow path formed by the offset fin 10, Or heat exchange with the cooling water while winding the offset pin (10).

Therefore, as the shape of the offset fin 10 becomes more complicated, the contact area is widened, so that the heat exchange efficiency between the EGR gas and the cooling water can be generally increased.

However, in the case of the flow paths having the shapes as shown in FIGS. 1 and 2, the flow of the EGR gas is excessively disturbed, and there is a problem that the pressure drop (pressure drop) is very large. If the pressure loss is large and the other conditions are the same, the flow rate of the EGR gas may decrease, and the injection efficiency in the combustion chamber of the EGR gas may be rapidly lowered.

2, the lower plate 20 and the upper plate 30 are separately brazed and the offset pins 10 are inserted therein to form the offset pins 10, the lower plate 20, There is a problem that it is costly to manufacture one tube by brazing the plate 30 and the manufacturing process is also difficult and the economical efficiency is very low.

It is an object of the present invention to provide a low-resistance, high-efficiency EGR cooler to reduce excessive pressure loss due to fluid flow and to exhibit high heat exchange efficiency at the same time.

Still another object of the present invention is to provide a low-resistance, high-efficiency EGR cooler, which can be simply manufactured, thereby reducing the cost of manufacturing an EGR cooler.

According to an aspect of the present invention, there is provided an exhaust gas recirculation system including an EGR tube having both ends opened and an EGR gas flowing therein, wherein a plurality of dimples are formed in the EGR tube, The dimples may provide a streamlined EGR cooler along the longitudinal direction of the EGR tube to reduce the pressure loss inside the EGR tube.

Here, the dimples may be in the shape of an 'S' shape as viewed from the plane of the EGR tube.

In this case, the length ratio from the total length of the dimple to the inflection point at one end of the dimple may be 2: 1,

In this case, assuming that a length from one end of the dimple to an inflection point is 'A', and a height from a virtual straight line connecting one end of the dimple to the floor of the dimple center line is 'H' ,

Can be established.

Further, in one embodiment of the present invention, the dimple can reduce the pressure loss in the EGR tube by giving a gradient in the diagonal direction as viewed from the side end surface of the tube.

In this case, the dimple may be formed so as to have a double gradient continuously from the forward slope.

According to an embodiment of the present invention, the dimple may include an embossed protrusion formed on the inner surface of the tube front to form a vortex inside the tube,

According to one embodiment, the cross-sectional shape of the EGR tube may be substantially circular or rectangular.

According to another aspect of the present invention, there is provided an exhaust gas recirculation system comprising: a plurality of EGR tubes having both ends opened and an EGR gas flowing therein; A plurality of dimples are formed on an upper surface and a lower surface of the EGR tube, the dimples extending inward from the outer side, and the dimples are streamlined along the longitudinal direction of the EGR tube, And an EGR cooler having an 'S' shape.

According to an aspect of the present invention, there is provided a method of manufacturing an EGR cooler, comprising the steps of: forming a flat plate for an EGR tube by press working into a sheet having a plurality of dimples; A step of bending one end of the molded sheet so as to face the other end; And forming a tube by bonding one end and the other end of the folded sheet by welding, brazing or brazing, to form a tube.

The method may further include the step of forming a plurality of EGR tubes, stacking the EGR tubes, and providing a body shell formed to surround the plurality of stacked tubes.

In this case, the seat may be formed by bending in a shape corresponding to the cross-sectional shape of the body shell.

According to the present invention, it is possible to provide a low-resistance, high-efficiency EGR cooler that can reduce excessive pressure loss due to fluid flow and exhibit high heat exchange efficiency at the same time.

In addition, since the EGR cooler manufacturing process is significantly simpler than the conventional technology, the manufacturing cost is significantly reduced.

1 is a perspective view of an offset-fin for an EGR cooler according to the prior art;
2 is a front view of an EGR cooling tube equipped with an offset pin for an EGR cooler according to the prior art;
3 is a perspective view of an EGR tube in which dimples are formed according to an embodiment of the present invention.
4 is a front view of an EGR tube in which dimples are formed according to an embodiment of the present invention;
5 is a conceptual diagram of an 'S' shaped dimple according to an embodiment of the present invention.
6 is a side sectional view in the direction of AA 'in Fig.
Figure 7 shows dimples having a double gradient in Figure 6;
8 is a view showing further embossments formed in Fig. 6;
9 is a perspective view of an EGR cooler having a dimple according to an embodiment of the present invention.
10 is a perspective view of an EGR cooler in which a dimple is formed according to another embodiment of the present invention.
11 is a block diagram of a method for manufacturing an EGR cooler according to an embodiment of the present invention.
12 is a perspective view of a method for manufacturing an EGR cooler according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the present invention, a detailed description of known configurations will be omitted, and a detailed description of configurations that may unnecessarily obscure the gist of the present invention will be omitted.

As used herein, the term "bond " may refer to any physical connection, such as attachment, attachment, contact, abutment, bonding, etc., of a member to another member (e.g., one end and the other end of the molded sheet) .

In the orthogonal coordinate system shown in Fig. 3 of the present invention, the x-axis direction is a direction parallel to the longitudinal direction of the EGR tube (the front side of the EGR tube), the y-axis direction is a direction parallel to the width direction of the EGR tube Side direction), and the z-axis direction can indicate a direction parallel to the thickness direction of the EGR tube.

First, the EGR tube 100 of the present invention will be described in detail.

3 is a perspective view of an EGR tube having a dimple according to an embodiment of the present invention. 4 is a front view of an EGR tube having a dimple according to an embodiment of the present invention. 5 is a conceptual diagram of an 'S' shaped dimple according to an embodiment of the present invention.

3 and 4, an EGR cooler according to an embodiment of the present invention includes an EGR tube 100 having both ends opened and an EGR gas flowing therein, and the EGR tube 100 has an EGR tube 100 The dimples 110 may be formed in a streamlined shape along the longitudinal direction of the EGR tube 100 so as to reduce the pressure loss inside the EGR tube 100. [

Unlike the prior art, the EGR cooler according to an embodiment of the present invention does not form a separate offset pin. In the present invention, heat exchange with EGR gas can be realized by forming the dimples 110 in the direction of the inside of the EGR tube 100 simply.

Here, the dimple 110 preferably has a curved shape in front of the first portion to meet the fluid so as to minimize the resistance of the fluid.

Referring again to FIG. 4, a plurality of dimples 110 are formed on the upper and lower surfaces of the inside of the EGR tube 100, aligned with each other. The dimples 110 are preferably formed on the upper and lower surfaces of the EGR tube 100 for the sake of convenience of manufacture, but are not necessarily limited thereto. For example, the dimple 110 may be disposed in a somewhat irregular manner if it has a structure capable of increasing the thermal efficiency, and may be disposed on the left / right side of the inside of the EGR tube 100 as needed.

However, the dimple 110 according to an embodiment of the present invention is formed in a streamlined shape to minimize the resistance of the fluid, and is formed in a substantially S shape in plan view of the EGR tube 100 so as to increase heat exchange efficiency. Is more preferable.

As shown in FIG. 3, the 'S' shaped dimples 110 are formed to have a smooth wavy shape to reduce the pressure loss during the flow of the EGR gas, and the dimple 110 has one end and the other end It is preferable that the imaginary center line connecting the center line and the EGR tube 100 is parallel to the longitudinal direction of the EGR tube 100. It is possible to increase the contact area per unit area between the EGR gas and the EGR tube 100 when the dimple 110 is formed in a streamlined shape with a longer curve than in the case of forming the dimple 110 in a circular or oval shape There is an advantage that the cooling efficiency of the EGR gas can be increased from the side.

For reference, the gas velocity at the inlet side of the EGR tube 100 is approximately 3 m / sec to 10 m / sec, and the Reynolds number at the inlet side of the EGR tube 100 is approximately 1000 to 2000. According to the present invention, the flow of the EGR gas is changed so as to flow along the 'S' shape of the dimple, thereby promoting the turbulent flow in the laminar flow as a whole.

The length ratio of the dimple 110 to the inflection point at one end of the dimple 110 is 2: 1 and the length of the dimple 110 at the inflection point is 2: 1. The height H from a virtual straight line connecting one end to the other end of the dimple 110 to the floor (or valley) of the center line (Wavy Center Line) is the length from the one end of the dimple 110 to the inflection point Is preferably smaller than half of (A). 5 shows a dimension of the dimple 110 having such a characteristic. For example, in FIG. 5, the height H to the center line floor of the dimple 110 and the length A to the inflection point are 1: 3, respectively.

When the length (A) ratio from the entire length L of the dimple 110 to the inflection point at one end of the dimple 110 is 2: 1 and the shape of the dimple is symmetrical about the inflection point, the EGR gas flows from the front dimple It is possible to cause the fluid flow to flow naturally as it draws an approximately 'S' character when flowing in the direction of the adjacent rear dimple. Also, in relation to the length A from the virtual straight line connecting one end portion of the dimple 110 to the floor of the center line to the inflection point,

The pressure loss is large.

Is satisfied in terms of reducing the pressure loss. For example, if the curved shape formed by the center line is a semicircular (

), The pressure loss is large, but the pressure loss is much smaller when the relationship of H: A = 1: 3 is substantially the same as shown in Fig.

The radius of curvature R of one end and the other end of the dimple 110 may be half of the width W of the dimple 110. That is, the radius of curvature R has a value of W / 2, and when the dimple 110 has a streamline shape, it is easy in terms of manufacturing difficulty.

The EGR tube 100 in which the dimples 110 are formed will be described in detail with reference to FIGS. 6 to 8. FIG.

6 is a side sectional view taken along the line A-A 'of FIG. FIG. 7 is a view showing a dimple having a double gradient in FIG. 6. FIG. FIG. 8 is a view showing embosses formed in FIG. 6. FIG.

The dimple 110 according to an embodiment of the present invention can reduce a pressure loss in the EGR tube by giving a gradient (inclination,?) In a diagonal direction as viewed from a side end surface of the EGR tube 100.

Referring to FIG. 6, the flow direction of the EGR gas is formed from the left to the right. When the first contact with the EGR gas is referred to as forward, the dimples 110 are recessed while forming inclined surfaces on the front side have. Some of the EGR gas is mixed with the fluid not hitting the dimples 110 while gently riding against the inclined surface of the dimples 110, thereby increasing the heat exchange efficiency. The pressure loss at this time is significantly reduced compared to the prior art.

Further, the dimples 110 according to an embodiment of the present invention may be formed to have a double gradient α, β continuously from the forward inclination of the EGR tube 100 as shown in FIG. If the EGR gas has a double gradient (α, β), a secondary flow region may be formed in which a vortex is generated behind the second gradient (β) while passing through the first gradient (α) and the second gradient (β). This is due to the pressure difference due to the fluid flow, and it is possible to naturally increase the heat exchange efficiency. The first gradient? Is preferably formed in a range of about 20 to 70 degrees to reduce the pressure loss, and the second gradient? Is formed in a range of about 5 to 30 degrees, which is a smaller angle than the first gradient Which is preferable in terms of forming a secondary flow region.

According to an embodiment of the present invention, in order to provide an EGR tube 100 having a higher heat exchange efficiency, an EGR tube 100 is provided on the front inner surface of the EGR tube 100, an emboss 120 may be protruded. The emboss 120 is for generating a vortex from the front of the EGR tube 100. The number, shape, and size of the emboss 120 may vary, but the height of the dimple 110, which protrudes from the dimple 110 located at the rear, Side surface.

In addition, the EGR tube 100 according to an embodiment of the present invention may have a substantially circular or rectangular cross-sectional shape. The EGR tube 100 shown in FIGS. 3, 5, and the like has a rectangular cross-section as viewed from the front, but may have a circular cross-section.

9 and 10, an EGR cooler having a dimple according to an embodiment of the present invention will be described.

FIG. 9 is a perspective view of an EGR cooler having a dimple according to an embodiment of the present invention, and FIG. 10 is a perspective view of an EGR cooler having a dimple according to an embodiment of the present invention. FIG. 10 is different from FIG. 9 in the manner of fixing the EGR tube 100 to the body shell 200.

The EGR cooler according to an embodiment of the present invention includes a plurality of EGR tubes 100 having both ends opened and EGR gas flowing therein, and a plurality of EGR tubes 100 stacked inside the engine, A plurality of dimples 110 are formed on the upper and lower surfaces of the EGR tube 100 from the outside to the inside, and the dimples 110 are formed on the upper and lower surfaces of the EGR tube 100, May be formed to have a streamlined shape along the longitudinal direction of the EGR tube 100, and to have an approximately 'S' shape.

In the present embodiment, detailed descriptions of the shapes of the EGR tube 100 and the dimples 110 are the same as those described above, and thus will not be described. However, the plurality of EGR tubes 100 may be stacked one upon the other, and the EGR tubes 100 may be accommodated in the body shell 200 surrounding the EGR tubes 100 and heat exchanged with the cooling water. According to an embodiment of the present invention, since the EGR tube 100 unit is formed in a thin thickness of approximately mm units, the dimples 110 are formed on substantially the upper and lower surfaces except the side surface of the EGR tube 100 .

The EGR tube 100 may be soldered or brazed to the inner wall of the body shell 200 and inserted into a separate fixing plate 400 or 400 ' 200 as shown in FIG.

The cooling water is supplied through an inlet 210 formed at one side of the body shell 200 and passes through a cooling channel (not shown) formed in the interior of the body shell 200. After the heat exchange with the EGR gas inside the EGR tube 100, And is discharged from an outlet 220 formed at one side. Referring to FIG. 9, the cooling water inlet 210 and the outlet 220 are all formed on the upper surface of the body shell 200, but the present invention is not limited thereto.

The EGR cooler according to the present embodiment is provided with a front flange 300, a rear flange 300 'and a separate gasket to seal the joint between the front gas pipe and the rear gas pipe of the body shell 200 .

Finally, a method of manufacturing the EGR cooler according to an embodiment of the present invention will be described in detail.

FIG. 11 is a block diagram of a method for manufacturing an EGR cooler according to an embodiment of the present invention, and FIG. 12 is a perspective view of a method for manufacturing an EGR cooler according to an embodiment of the present invention.

Referring to FIGS. 11 and 12 together, the method of the present invention is a method of manufacturing the above-described EGR cooler, comprising the steps of molding a flat plate for an EGR tube into a sheet having a plurality of dimples by press working (S1001) (S1002) in which one end of the folded sheet is bent so as to face the other end, and the other end opposite to the one end of the folded sheet is joined by welding, soldering or brazing to form a tube (S1003).

The EGR cooler manufacturing method will be described in more detail. First, a flat plate 101 for manufacturing an EGR tube is provided. The material of the flat plate is preferably a material having high corrosion resistance such as stainless steel or titanium, and the thickness is preferably thin so as to facilitate press forming.

Then, the prepared flat plate 101 is formed into a sheet having a plurality of dimples 110 having regular or irregular arrangement (S1001). Here, the dimple 110 may be formed by pressing a press provided with a projection having a shape corresponding to the dimple 110.

Next, the molded sheet is bent (S1002) so that one end of the sheet is opposed to the other end. When the flat plate 101 is bent along a plurality of hypothetical lines set in the longitudinal direction, it can be formed in the same shape as the tube shown in FIG. It is very economical to insert the sheet into a bending machine simply by bending it.

Lastly, one end and the other end of the folded sheet are firmly connected to each other to form a tube. Welding or soldering or brazing may be employed. However, it is sufficient that the one end and the other end of the sheet can be smoothly joined so as not to accumulate impurities in the flow of the EGR gas.

Further, the method of manufacturing an EGR cooler according to an embodiment of the present invention may further include the step of providing a body shell 200 formed by stacking a plurality of the EGR tubes 100 and enclosing a plurality of stacked tubes You may. When a plurality of EGR tubes 100 stacked on the body shell 200 having the cooling water inlet, the cooling passage and the outlet are inserted and the front and rear flanges 300 and 300 'and the gasket (not shown) It is possible to provide an EGR cooler having a reduced pressure loss and an excellent thermal efficiency.

Meanwhile, in the step of bending the sheet (S1002), the folding of the sheet may be bent into a shape corresponding to the cross-sectional shape of the body shell 200. [ For example, if the cross section of the body shell 200 is circular, the sheet may have a substantially circular shape, and if the cross section of the body shell 200 is rectangular, the sheet may have a substantially rectangular shape. It is good to increase the space efficiency by stacking more sheets.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

10: offset pin
20: Lower bray plate
30: Upper bray plate
100: EGR tube
101: Reputation
110: dimple
120: Embossed
130: coupling surface
200: Body shell
300, 300 ': front and rear flanges
400: Fixed plate

Claims

And an EGR tube having both ends opened to allow the EGR gas to flow therein,
The EGR tube is formed with a plurality of dimples extending from the outside to the inside,
Wherein the dimple is formed in a streamline shape along the longitudinal direction of the EGR tube so as to reduce a pressure loss inside the EGR tube.

The method according to claim 1,
Wherein the dimples have an S shape when viewed from a plane of the EGR tube.

3. The method of claim 2,
Wherein the ratio of the length of the dimple to the inflection point at one end of the dimple is 2: 1.

3. The method of claim 2,
When the height from one end of the dimple to the inflection point is defined as 'A' and the height from a virtual straight line connecting one end of the dimple to the floor of the dimple center line is 'H'

Wherein the EGR cooler has an EGR cooler.

3. The method of claim 2,
Wherein the dimples are provided with a gradient in a diagonal direction as viewed from a side end surface of the tube to reduce pressure loss in the EGR tube.

6. The method of claim 5,
Wherein the dimple is formed so as to have a double gradient continuously from the forward slope.

The method according to claim 1,
And an embossment protruding from an inner surface of the tube front to form a vortex inside the tube.

The method according to claim 1,
Wherein the cross-sectional shape of the EGR tube is substantially circular or rectangular.

A plurality of EGR tubes, both ends of which are opened and in which EGR gas flows,
And a body shell in which the plurality of EGR tubes are stacked in the body, and an engine cooling water inlet and an outlet are provided on one side,
A plurality of dimples are formed on the upper and lower surfaces of the EGR tube from the outside to the inside,
Wherein the dimples are formed in a streamlined shape along the longitudinal direction of the EGR tube so as to have a substantially 'S' shape.

A method of manufacturing an EGR cooler according to any one of claims 1 to 8,
Molding a flat plate for an EGR tube into a sheet having a plurality of dimples formed by press working;
A step of bending one end of the molded sheet so as to face the other end; And
Forming a tube by bonding one end and the other end of the folded sheet by welding, brazing or brazing;
Gt;

10. The method of claim 9,
Forming a plurality of EGR tubes, stacking the plurality of EGR tubes, and providing a body shell to surround the plurality of stacked tubes.

12. The method of claim 11,
Wherein the sheet is bent in a shape corresponding to a cross-sectional shape of the body shell.