WO2010098321A1

WO2010098321A1 - Egr cooler

Info

Publication number: WO2010098321A1
Application number: PCT/JP2010/052766
Authority: WO
Inventors: 津田　寛司; 泰生大久保; 和夫古橋; 恵市稲葉
Original assignee: 株式会社小松製作所
Priority date: 2009-02-27
Filing date: 2010-02-23
Publication date: 2010-09-02
Also published as: DE112010000919T5; JP5048695B2; JP2010196679A; DE112010000919B4; CN102333949A; US20110308778A1

Abstract

The EGR cooler (10) comprises a case (11) wherein cooling water flows, multiple tubes (12) housed inside the case (11) and wherein exhaust gas flows, header plates (13), to which the ends of the multiple tubes (12) are joined, and that are joined to the ends of the case (11), and an intake-side tank (14) that is configured to allow inflow of the exhaust gas and is joined to an end of the case (11). A shielding member (19) for shielding the inner wall of the intake-side tank (14) from the incoming exhaust gas is provided inside the intake-side tank (14).

Description

EGR cooler

The present invention relates to an EGR (Exhaust Gas Recirculation) cooler.

Conventionally, in an EGR system mounted on a diesel engine, an EGR cooler may be provided to cool the exhaust gas returned to the air supply side. The EGR cooler includes a plurality of tubes for circulating the exhaust gas, and a case (sometimes referred to as a shell) in which the tubes are accommodated, and one end side of the case is provided with an inlet for introducing the cooling water. At the other end side, an outlet for discharging the cooling water is provided.

Also, the case is cylindrical, and an inlet side tank is provided at the opening on one end side of the case to allow the exhaust gas to flow into the tube, and the end on the other side of the case is the exhaust gas from the tube There is an outlet tank that lets out the water. In such a case, each end of the tube is fixed to the header plate by brazing or the like, and the header plate is fixed to the inner circumferential surface of the case by welding so as to close the opening of the case There is. That is, the cooling water flows in the outside of the plurality of tubes and the exhaust gas flows in the inside of the tubes in the case where both ends are closed by the header plate.

By the way, in the inlet side tank, since the high temperature exhaust gas directly strikes one side of the header plate, that is, the side facing the inlet side tank, the brazed portion of the header plate and the tube is heated by the exhaust gas As a result, there is a problem that the temperature is raised to lower the bonding strength and a crack is formed in the soldered portion.

Therefore, in order to prevent exhaust gas from directly striking such a header plate, a shield plate having substantially the same shape as the header plate is provided on the upstream side of the header plate, and the tube end is extended to this shield plate. An EGR cooler having a structure has been proposed (e.g., Patent Document 1).
In such a structure, since the space between the inlet tank and the inside of the case is a double structure, the high temperature exhaust gas flowing into the inlet tank does not hit the header plate, and the temperature of the brazed portion with the tube is increased You can suppress it. Therefore, there is no fear that such a brazed portion will be cracked, and it is possible to prevent the cooling water in the case from leaking out.

JP, 2000-45882, A

However, although the EGR cooler described in the above publication can prevent the exhaust gas from directly hitting the brazing part, the exhaust gas still directly contacts the peripheral wall portion (bonnet) of the inlet side tank. As the tank, the peripheral wall thermally expands to a large extent outward, and a thermal expansion difference occurs between the inlet side tank and the case or header plate to which it is fixed. That is, the casing and the header plate do not become very hot because most of them are always in contact with the cooling water, and the degree of thermal expansion is small, but the peripheral wall of the inlet side tank may be in contact with the cooling water Also, the thermal expansion is significant because only the exhaust gas contacts.

Therefore, at the joint portion between the inlet side tank and the case or header plate, the case or header plate is deformed outward due to the significant thermal expansion of the inlet side tank, and as a result, the header plate and tube are jointed. High stress occurs in the part and cracks occur.

An object of the present invention is to provide an EGR cooler which can suppress thermal deformation due to a large thermal expansion difference from the inlet side tank and can prevent the occurrence of cracks.

In the EGR cooler of the present invention, a case in which the cooling water flows inside, an exhaust gas flowing inside, a plurality of tubes accommodated in the case, and an end of the plurality of tubes are joined to end the case A header plate joined to the head, and an inlet-side tank configured to allow exhaust gas to enter and joined to the end of the case, and the inlet-side tank from the exhaust gas entering into the inlet-side tank A shielding member for shielding the peripheral wall portion of the tank is provided.

In the EGR cooler of the present invention, the shielding member is preferably provided at the inlet side tank.

In the EGR cooler of the present invention, it is preferable that a gap be formed between the shielding member and the header plate.

In the EGR cooler of the present invention, the opening on the outlet side of the exhaust gas of the shielding member preferably covers the inlet side of all the tubes.

In the EGR cooler of the present invention, preferably, the shielding member is expanded toward the outlet side of the exhaust gas.

In the EGR cooler of the present invention, it is preferable that the opening portion on the outlet side be provided with a cylindrical outlet end portion having substantially the same diameter in the flow direction of the exhaust gas.

According to the present invention, since the shielding member is provided in the inlet side tank, the high temperature exhaust gas flowing into the inlet side tank is less likely to contact the peripheral wall portion of the inlet side tank, and to the outer side of the peripheral wall portion. Suppress thermal expansion. Therefore, the case and header plate joined to the inlet side tank are not affected by the thermal expansion of the inlet side tank, so there is no concern that they will be greatly deformed, preventing the generation of large stress at the joint portion between the header plate and the tube. Can prevent the occurrence of cracks.

When the shielding member is provided on the inlet side tank, the front and back direction is determined because the shielding member is not provided as the core formed of the header plate and the tube, so that the handedness of the front and back is the same. Such a case can be easily assembled without the risk of erroneously assembling the front and rear.

Here, by providing a gap between the shielding member and the header plate, even if the shielding member touches the exhaust gas and thermally expands, there is no possibility that the shielding member and the header plate come in contact, and the header plate is pressed. It is possible to prevent stress from being generated.

If the opening on the outlet side of the shielding member is sized to cover the ends of all the tubes, exhaust gas emitted from the shielding member can uniformly flow into each tube, and the cooling efficiency of the exhaust gas can be improved. .

By expanding the shielding member toward the outlet side, even when the opening area on the inlet side in the inlet side case is small and the opening area on the outlet side is large, exhaust gas can be reliably guided to each tube, which is also good Cooling efficiency can be realized.

When an outlet end for suppressing diffusion is provided on the outlet side of the shielding member, the exhaust gas flows into each tube without spreading, so the flow of exhaust gas becomes smooth and the cooling efficiency is further improved. It can be done.

FIG. 2 is a cross-sectional view of the EGR cooler according to the present embodiment taken along the flow direction of the exhaust gas. Sectional drawing along the II-II line of FIG. The enlarged view which shows the principal part of an EGR cooler. The figure which shows the component used for an EGR cooler. The cross-sectional perspective view which shows the said component. Sectional drawing which shows the modification of this invention.

Hereinafter, an embodiment of the present invention will be described based on the drawings.
FIG. 1 is a cross-sectional view of the EGR cooler 10 according to the present embodiment taken along the flow direction of the exhaust gas (see hatching arrows). 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is an enlarged view showing the main part of the EGR cooler 10. FIG. 4 is a view showing components used for the EGR cooler 10, and FIG. 5 is a cross-sectional perspective view thereof. In the following description, the front side means the upstream side of the flow of exhaust gas, and the rear side means the downstream side. Moreover, right and left mean right and left when viewed from the front side.

In FIG. 1, the EGR cooler 10 includes a cylindrical case 11, a plurality of flat tubes 12 for circulating exhaust gas housed inside the case 11, and header plates on both sides to which the ends of the tubes 12 are joined. 13 and an inlet-side tank 14 and an outlet-side tank 15 joined to the case 11 via the respective header plates 13, and the inlet-side tank 14 has a mounting flange 16 having an inlet 16A. A mounting flange 17 having an outlet 17A is provided on each of the housings.

At one end side and the other end side of the case 11, cylindrical projections 18 larger in diameter than the central body portion are formed. Below the protrusion 18 on the front side, there is provided an inlet 21 for allowing cooling water (see white arrow) to flow into the inside of the case 11. Above the protrusion 18 on the rear side, the cooling water in the case 11 is An outlet 22 is provided for outflow. A pair of gas venting holes 23 are provided at the upper part of the projection 18 on the cooling water inlet 21 side at a predetermined angle apart in the circumferential direction (only one is shown in FIG. 1).

In FIG. 2, a gap between mutually facing surfaces of the tubes 12 juxtaposed is a cooling water flow path 24 through which the cooling water passes. The cooling water channels 24 are preferably all set to the same width dimension. In the present embodiment in which the tubes 12 are arranged side by side, the cooling water inlet 21 (FIG. 1) is located below the projection 18 because the cooling water from the inlet 21 is the cooling water flow path In order to get into 24 immediately. Therefore, such an inlet 21 is preferably located at the lower central portion of the projection 18 as in the present embodiment. That is, in the present embodiment, the flow direction of the cooling water immediately after flowing in from the inflow port 21 and the vertical direction of each tube 12 are the same direction, and the flow of the cooling water is not hindered.

Further, in the present embodiment, although the tubes 12 are not illustrated in detail, part of the surface is brazed to each other with point-like protruding portions, and the header plate 13 is attached to the end of these tubes 12. Is brazed. The core 25 is configured to include the tube 12 and the header plate 13.

When assembling the EGR cooler 10, the core 25 is manufactured in advance by brazing the tubes 12 to each other or by brazing the header plate 13 thereto, and the core 25 is vertically or horizontally divided into a case body 11A. , 11B, and the

case bodies

11A and 11B are joined together by welding or the like. And each

tank

14 and 15 is attached to the edge part of case 11 (header plate 13) by welding etc.

At this time, as shown in an enlarged manner in FIG. 3, a cylindrical portion 131 formed on the outer periphery of the header plate 13 is fitted inside the opening end portion 111 of the case 11. The open ends 141 and 151 of the

tanks

14 and 15 are fitted, and they are integrally joined by welding. In the present embodiment, the outer shapes of the

open end portions

111, 141, 151 and the cylindrical portion 131 are not circular, and slightly shown as being representative of the open end portion 141 of the inlet side tank 14 in FIG. It has an odd shape with a square shape.

The inlet side tank 14 used in the present embodiment will be described in detail below based on FIGS. The inlet side tank 14 has a cylindrical inlet end 142 fitted to the inlet 16A of the mounting flange 16, the above-mentioned open end 141 forming the outlet side, and a peripheral wall connecting these

ends

141 and 142. And the peripheral wall portion 143 is expanded from the inlet end portion 142 toward the opening end portion 141 side.

Further, inside the inlet side tank 14, a shielding member 19 is provided to make it difficult for the inflowing exhaust gas to contact the inner surface of the peripheral wall portion 143. The shielding member 19 has a cylindrical inlet end 192 which is fitted and welded into the inlet end 142 of the inlet tank 14, an outer rectangular outlet end 191 opened rearward, and the like. It is formed of a peripheral wall portion 193 connecting the

end portions

191 and 192 with each other.
However, the external shape of the outlet end 191 is not limited to a square, and may be circular or the like, and the cross-sectional shape of the tube 12, the end of the core 25, or the open end 141 of the inlet side tank 14 It may be determined arbitrarily in consideration of the shape of the

The opening area of the outlet end 191 is sized to cover the entire area on the inlet side of all the juxtaposed tubes 12 so that the inflowing exhaust gas flows into the respective tubes 12 evenly. The outlet end 191 is also formed in a straight cylindrical shape having an equal diameter along the flow direction of the exhaust gas (over the back and forth), and flows smoothly into each tube 12 without diffusing the exhaust gas from the shielding member 19. It is possible to

A minute gap S is formed between the outlet end 191 and the header plate 13 (in FIG. 1, it is exaggerated and drawn large for the sake of easy viewing). The gap S should be small so that the exhaust gas does not get around to the peripheral wall portion 143 side of the inlet side tank 14, and it is also preferable to be small in order to smoothly flow the exhaust gas to each tube 12. Therefore, the gap S in the present embodiment is set smaller within a range in which the shielding member 19 does not contact the header plate 13 even when the shielding member 19 contacts the high temperature exhaust gas and thermally expands. .

The peripheral wall 193 extends from the inlet end 192 toward the outlet end 191. That is, the opening area of the outlet end 191 is larger than the opening area of the inlet end 192. However, the peripheral wall portion 193 may have a shape corresponding to the size of the inflow port 16A. For example, the opening area of the inflow port 16A is larger and the diameter is substantially the same as the upper and lower dimensions in the drawing of the tube 12 In this case, it is formed in a straight cylindrical shape having the same shape as the inlet end 192 and the outlet end 191.

According to the EGR cooler 10 of the present embodiment described above, the high temperature exhaust gas flowing into the inlet tank 14 from the inlet 16A is almost in contact with the peripheral wall portion 143 by being guided by the shielding member 19. Instead, it flows into each tube 12. The exhaust gas flowing through each tube 12 is cooled by the cooling water flowing outside the tube 12 in the case 11, flows out to the outlet side tank 15, and returns from the outlet side tank 15 to the air supply side of the engine.

Therefore, in the inlet side tank 14, the exhaust gas is less likely to contact the peripheral wall portion 143, so the thermal expansion of the peripheral wall portion 143 as shown by the two-dot chain line in FIG. 13 deformation can be prevented. And, by preventing the deformation of the header plate 13 in particular, it is possible to suppress the stress generation at the joint portion with the tube 12 and to prevent the occurrence of a crack at the outer joint portion.

Note that the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like as long as the object of the present invention can be achieved are included in the present invention.
For example, in the embodiment described above, the inlet tank 14, the mounting flange 16, and the shielding member 19 are separated from each other and joined by welding, but as shown in FIG. It may be manufactured as one piece.

In the embodiment, the shielding member 19 is provided in the inlet side tank 14, but may be provided in the header plate 13.
Moreover, as a shape of the shielding member 19, the case where there is no straight cylindrical outlet end part 191 like the said embodiment and the rear side opens the peripheral wall part 143 as it is is also included in this invention. However, by providing the outlet end 191, the flow of exhaust gas can be efficiently flowed into the tubes 12 toward the tubes 12, so this is preferable.

In the embodiment described above, the outlet end 191 has an opening area sized to cover the ends of the entire tube 12, but the invention is not limited to this. Even small cases are included in the present invention. However, since the exhaust gas can be uniformly flowed to all the tubes 12 by setting the size so as to cover the end portions of all the tubes 12, it is preferable to do so because the cooling efficiency can be improved.

Furthermore, the shape of the peripheral wall portion 193 is also arbitrary, and is not limited to the linearly expanded shape as in the above embodiment, and may be a round shape so that the entire peripheral wall portion 193 is formed by a curved surface. An appropriate shape can be applied in the implementation.

In the said embodiment, although the flat tube 12 was used as a tube which concerns on this invention, a tube of circular cross-section may be sufficient as a tube, and the tube of arbitrary shapes can be applied. When the tube is circular in cross section, the shape of the outlet end 191 of the shielding member 19 is also preferably circular.

In addition, the shape of the header plate 13 is also arbitrary, and is not limited to the one having the cylindrical portion 131 as in the embodiment. That is, it may be flat and the outer periphery thereof may be joined to the inner peripheral surface of the case 11. Even in such a case, when the peripheral wall portion 143 of the inlet side tank 14 thermally expands, there is a possibility that the header plate 13 may be deformed along with the deformation of the case 11, and the joint portion between the header plate 13 and the tube 12 Because large stresses may occur, it is effective to apply the present invention to prevent stress generation.

The present invention can be suitably applied to construction machines, transport vehicles, and various industrial machines on which an engine equipped with an EGR system is mounted.

10: EGR cooler, 11: case, 12: tube, 13: header plate, 14: inlet side tank, 19: shielding member, 191: outlet end, S: clearance.

Claims

At the EGR cooler,
In the case where cooling water flows inside,
A plurality of tubes, through which exhaust gas flows and contained in the case;
A header plate in which ends of the plurality of tubes are joined and joined to an end of the case;
And an inlet side tank configured to receive exhaust gas and joined to the end of the case;
An EGR cooler characterized in that a shielding member for shielding a peripheral wall portion of the inlet side tank from the inflowing exhaust gas is provided in the inlet side tank.
In the EGR cooler according to claim 1,
The shielding member is provided on the inlet side tank.
In the EGR cooler according to claim 2,
An EGR cooler characterized in that a gap is formed between the shielding member and the header plate.
In the EGR cooler according to any one of claims 1 to 3,
An EGR cooler characterized in that an opening on the outlet side of exhaust gas of the shielding member covers the inlet side of all the tubes.
In the EGR cooler according to any one of claims 1 to 3,
An EGR cooler characterized in that the shielding member is expanded toward an outlet side of exhaust gas.
In the EGR cooler according to any one of claims 1 to 3,
An EGR cooler characterized in that a cylindrical outlet end portion having substantially the same diameter in the flow direction of the exhaust gas is provided at an opening portion on the outlet side.