JP2010112201A - U-turn type egr cooler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a U-turn type EGR cooler of a compact structure capable of making both compatible in heat exchange performance and the prevention of clogging, and capable of also preventing heat damage. <P>SOLUTION: This U-turn type EGR cooler is formed by blocking up its opposite end surface by a circular arc header 2 formed in a circular arc shape, by arranging an inlet and an outlet of exhaust gas in parallel on the same end surface of a square cylindrical shell 1 for enclosing a heat exchange part. A tube 5 formed by blocking up by arranging a circular arc part on one end of a flat pipe, is transversely installed and laminated in large numbers in the heat exchange part. An offset fin 8 internally installed up to the circular arc part from the inlet and forming a forward passage part and a wavy fin 9 internally installed up to the outlet from the circular arc part and forming a backward passage part, are arranged in parallel in this tube 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an EGR cooler, and more particularly, to a U-turn type EGR cooler in which an exhaust gas outlet and an inlet are arranged in parallel on the same end surface of a shell, and an arc header on which the exhaust gas makes a U-turn is provided on the opposite end surface.

In the conventional plate tube type EGR cooler, as shown in FIG. 9, a tube 11 in which an inner fin (for example, a waby fin 9) is inserted and brazed into a flat tube is used. The tube 11 is manufactured by a method of extrusion molding or a method of brazing an upper plate 11a and a lower plate 11b that are divided into two vertically.
A large number of such tubes 11 are arranged in parallel in the shell, and heat exchange is performed between the exhaust gas flowing inside the tube 11 and the cooling water flowing around the tube 11 by using one end of the shell as an inlet and the other end as an outlet. The core part to be formed was formed.

  Further, in recent years, as shown in FIG. 10, the gas passage in the core portion in the shell 1 is divided into the forward path and the backward path, and the exhaust gas flowing in from the inlet pipe 3a passes through the forward path and is turned on the arc header 2 on the opposite end surface. However, a U-turn type EGR cooler that passes through the return path and is discharged from the outlet pipe 3b provided on the same end surface as the inlet pipe 3a is also used (Patent Documents 1 and 2). In this U-turn type EGR cooler, the exhaust gas inlet and outlet are provided on the same side, so that the limited engine room space can be utilized effectively.

Also in the conventional U-turn type EGR cooler, as shown in FIG. 10, the flat tube 11 is arranged in parallel in the vertical direction and fixed by the end plates 10 and 12, and is divided into the forward path and the return path with the center of the core portion as a boundary. Have been used.
The arrows in FIG. 10 indicate the flow of exhaust gas. The exhaust gas flowing in from the inlet pipe 3a of the inlet / outlet header 3 passes through the tube 11 in the forward path, makes a U-turn in the arc header 2 on the opposite side, passes through the tube 11 in the return path, and flows out from the outlet pipe 3b of the inlet / outlet header 3 It has become. Further, around each tube 11, the cooling water flows from the cooling water inlet pipe 1 a provided on the lower surface on the inlet / outlet header 3 side of the shell 1 toward the cooling water outlet pipe 1 b provided on the upper surface on the arc header 2 side. Thus, heat exchange is performed between the exhaust gas and the cooling water.

As the inner fin of the tube 11, an offset fin 8 having excellent heat exchange performance as shown in FIG. 5 has been used. However, the offset fin 8 has a slit-like fin shape that overlaps many times, and soot easily adheres to it. Particles contained in the engine exhaust gas adhere to the fin as soot, and the soot attached to the inner fin grows over time. Finally, clogging sometimes occurred.
In addition, the soot lump deposited on the tube inlet side was blown off by the pressure of the exhaust gas, and caught on the tube outlet side and deposited again, which could cause clogging.

  Shell tube type EGR coolers that do not insert inner fins into the tube are advantageous in that clogging due to flaws is less likely to occur, but due to the recent increase in EGR rate of vehicles, heat exchange performance is emphasized in EGR coolers, which is compact. Countermeasures against clogging have been sought with a plate tube type EGR cooler with high heat exchange efficiency.

For this reason, the wavy fin 9 that is hard to be clogged as shown in FIG. 6 is also used as the inner fin (FIG. 9).
The waveby fin 9 has a corrugated shape obtained by bending a single plate, and is not cut and is difficult to attach wrinkles, but is inferior in heat exchange performance to the offset fin 8. For this reason, when high heat exchange performance of the EGR cooler is required as the EGR rate increases, it is necessary to increase the EGR cooler by increasing the number of tubes or extending the length of the tube. It was difficult to make the EGR cooler compact.

In addition, since the amount of soot generated and the wetness varies depending on the specifications and usage of the engine, it has been difficult to achieve both heat exchange performance and prevention of clogging with such a conventional EGR cooler.
It is also considered to install a soot collection filter upstream of the EGR cooler, but it is necessary to have a filter that can withstand high temperatures, increase the number of parts, and secure installation space. There was a problem.

  The fine particles of the soot that cause clogging are difficult to dry and adhere to the inner fin when the temperature of the exhaust gas is high, and when the temperature of the exhaust gas becomes low, moisture tends to be attached and tends to adhere to the inner fin. For this reason, soot tends to accumulate on the outlet side of the exhaust gas having a low temperature.

Further, as shown in FIG. 10, in the conventional U-turn type EGR cooler, the core portion inside the shell 1 and the inside of the arc header 2 are partitioned by the end plate 12, and when the exhaust gas passes through the arc header 2, Heat exchange with cooling water was not performed. For this reason, the heat of the exhaust gas is directly transmitted to the arc header 2 and becomes high temperature, which causes a problem of heat damage to the engine room.
In addition, when a plurality of tubes having different degrees of bending as in Patent Document 1 are used, a plurality of molds are required and cost is increased. In Patent Document 2, heat exchange is performed even with an arc header, but the structure is complicated and material costs are also incurred.

JP 2000-97113 A JP 2004-116913 A

  The present invention has been made to solve the above-described problems, and can achieve both heat exchange performance and prevention of clogging, and further can prevent heat damage, and has a U-turn EGR having a compact structure. The challenge is to provide a cooler.

In the present invention, means for solving the above problems are as follows.
In the first invention, an exhaust gas inlet and outlet are provided in parallel on one end face of a rectangular shell surrounding the heat exchanging portion, and the opposite end face is closed with an arc header formed in an arc shape. In this U-turn type EGR cooler, a large number of horizontally closed tubes are provided in the heat exchanging portion by providing a circular arc portion at one end of a flat tube, and the tube is stacked from the inlet. An offset fin that is internally provided between the arc portion and forms the forward path portion, and a waby fin that is internally provided between the arc portion and the outlet and forms the return path portion are arranged in parallel.

According to a second invention, in the first invention, the tube is formed by joining an upper plate made of an upper wall and a side wall and a lower plate made of a bottom plate and a side wall.
A third invention is characterized in that, in the first invention, a partition part for partitioning the forward path part and the return path part is projected and formed from at least one of the upper wall and the bottom plate of the tube.

  According to a fourth invention, in the first invention, a tube assembly formed by laminating a large number of the tubes and binding and fixing the end portion on the entrance / exit side with an end plate is inserted into the assembly of the shell and the arc header. It is characterized by.

  According to the first invention, in the heat exchanging part, a plurality of tubes, which are provided with a circular arc part at one end of a flat tube and are closed, are stacked in a horizontal position, thereby realizing a forward path and a return path with one tube. And the number of parts can be reduced. The standard of each tube is also the same, and the number of types can be reduced. In addition, heat is exchanged between the exhaust gas in the tube and the cooling water around the tube inside the arc header, and the exhaust gas and the arc header can be shielded by the cooling water to the engine room. Can prevent heat damage.

  Further, in this tube, there are offset fins that are internally provided from the inlet to the arc part to form the forward path part, and waby fins that are provided from the arc part to the outlet to form the return part. Are arranged in parallel, the exhaust gas passage in the tube can be divided into the forward path part and the return path part, and the number of manufacturing steps can be reduced. Furthermore, the heat exchange performance is improved by offset fins in the forward path where exhaust gas temperature is high and soot is difficult to adhere, and clogging can be prevented by wayby fins in the return path where exhaust gas temperature is low and soot is likely to adhere. Thus, both heat exchange performance and prevention of clogging can be achieved.

According to 2nd invention, the said tube can be easily manufactured by joining the upper plate which consists of an upper wall and a side wall, and the lower plate which consists of a bottom plate and a side wall.
According to the third invention, the exhaust gas passage in the tube is clearly formed by projecting and forming the partition portion that partitions the forward path portion and the return path portion from at least one of the upper wall and the bottom plate of the tube. Therefore, when the inner fin is disposed on the tube, positioning without deviation can be easily performed, and a tube that can withstand high temperature and high pressure can be formed.

  According to a fourth aspect of the present invention, a tube assembly formed by laminating a large number of the tubes and bundling and fixing the end portions on the inlet / outlet side thereof with the end plate is inserted into the assembly of the shell and the arc header. Even inside the arc header, heat exchange between the exhaust gas in the tube and the cooling water around the tube is ensured, and the exhaust gas and the arc header can be shielded by the cooling water. Heat damage can be prevented.

Hereinafter, a U-turn type EGR cooler according to an embodiment of the present invention will be described.
As shown in FIG. 1, the U-turn type EGR cooler according to the first embodiment of the present invention is formed by joining an arc header 2 and an inlet / outlet header 3 to both ends of a square shell 1, respectively. The arc header 2 incorporates a tube assembly 4 (FIG. 2).

The stainless steel (SUS) shell 1 is formed in a wide rectangular tube shape, a cooling water inlet pipe 1a is connected to the lower surface on the inlet / outlet header 3 side, and the cooling water outlet pipe 1b is connected to the upper surface on the arc header 2 side. Are connected, and cooling water flows through the inside.
The arc header 2 made of SUS or steel is formed by connecting an upper surface and a bottom surface formed in a substantially semicircular shape by side walls provided in respective arc-shaped portions. Portions corresponding to the diameters of the upper surface and the lower surface are opened without providing side walls and are joined to the shell 1.

  The entrance / exit header 3 made of SUS or steel has a box shape with one surface opened, and is connected to the shell 1 through this opening surface. An inlet pipe 3a and an outlet pipe 3b are connected in parallel to the left and right sides on the surface facing the opening surface (in FIG. 1, the right is the inlet pipe 3a and the left is the outlet pipe 3b), and the inlet pipe 3a and the outlet pipe 3b A partition plate 3c that bisects the inside of the entrance / exit header 3 to the left and right is provided at an intermediate position.

As shown in FIG. 2, the tube assembly 4 built in the shell 1 and the arc header 2 is constructed by laminating a number of flat SUS tubes 5 horizontally.
Each tube 5 has a shape in which one end of a flat tube is closed with an arc-shaped side wall, and offset fins 8 and wayby fins 9 are arranged in two rows on the left and right sides (FIGS. 2 and 2). 4).

  As shown in FIG. 4, the tube 5 includes an upper plate 6 having a side wall suspended from the upper wall portion of the tube 5, and a lower plate 7 having a side wall erected on the bottom plate portion of the tube 5. It is formed by covering the lower plate 7 and joining it by welding or brazing. At this time, since the side wall of the upper plate 6 is provided slightly outside the side wall of the lower plate 7, the side wall of the lower plate 7 is inscribed in the side wall of the upper plate 6 (FIG. 3A).

  In addition, a plurality of dowels 6a are installed on the upper surface of the upper wall of the upper plate 6 at a predetermined interval, and when the tubes 5 are stacked to form the tube assembly 4, a gap for allowing cooling water to flow is provided for each tube 5. (Figs. 2 and 4).

  As shown in FIG. 4, before the upper plate 6 is put on the lower plate 7, offset fins 8 and wayby fins 9 are laid in parallel on the lower plate 7 and joined by brazing. An offset fin 8 is disposed at a position corresponding to the back of the inlet pipe 3a to be a forward path portion, and a waby fin 9 is disposed at a position corresponding to the back of the outlet pipe 3b to be a return path portion. The innermost fin is not provided in the innermost part of the innermost plane, that is, the arc part, so that the exhaust gas can make a U-turn from the forward path part to the return path part.

As shown in FIG. 5, the offset fin 8 is formed by cutting a single SUS plate and offsetting it according to a predetermined rule by a press, so that the hot exhaust gas can exchange heat efficiently. It is a fin.
On the other hand, as shown in FIG. 6, the wayby fin 9 has a shape formed by geometrically bending one SUS plate without a cut, and has a shape that is difficult to clog because there is no slit-like cut. . Since the waveby fins 9 are formed of a single plate having no cuts, the return path portion can be airtight with respect to the forward path portion when brazed into the tube 5, and a special partition is provided in the tube 5. The forward path part and the return path part can be separated without any problem.

  A large number of such tubes 5 are stacked, and the open end side of the tubes 5 is bundled and fixed with an end plate 10 made of SUS to constitute the tube assembly 4 (FIG. 2). The tube assembly 4 is inserted into the assembly of the shell 1 and the arc header 2, and the opening of the assembly is closed by the entrance / exit header 3 and joined by welding or brazing to form a U-turn type EGR cooler. When the inlet / outlet header 3 is joined to the shell 1, the partition plate 3 c of the inlet / outlet header 3 is set to abut against the end plate 10 of the tube assembly 4, and serves to partition the exhaust gas inflow side and the outflow side.

The broken line arrows in FIG. 1 indicate the flow of exhaust gas in the U-turn type EGR cooler configured as described above.
The exhaust gas flowing into the inlet / outlet header 3 from the inlet pipe 3a flows into the forward path portion of each tube 5, makes a U-turn at the arc portion, passes through the return path portion, and flows out from the outlet pipe 3b of the inlet / outlet header 3. The exhaust gas is cooled by the cooling water flowing around the tube 5 in the shell 1 when passing through the forward path part and the return path part. Further, since the arc portion of the tube 5 is accommodated inside the arc header 2, heat exchange is performed between the exhaust gas and the cooling water, so that the heat exchange efficiency is improved and the exhaust gas and the arc header 2 are Can be shielded by the cooling water, and heat damage to the engine room can be prevented.

  Further, heat exchange is efficiently performed by the offset fins 8 in the forward path portion where the temperature of the exhaust gas is high and soot is difficult to adhere. On the other hand, since the soot easily gets wet and adheres in the return path portion where the temperature of the exhaust gas is low, clogging can be prevented by the waby fins 9, and both heat exchange performance and clogging prevention can be achieved. it can. Further, by arranging the offset fins 8 and the wayby fins 9 in parallel, the exhaust gas passage in the tube 5 can be divided into the forward path part and the return path part, and the number of manufacturing steps can be reduced.

<Another aspect>
As another aspect, a partition portion 5 a that partitions the forward path portion and the return path portion may be projected between the offset fin 8 and the waby fin 9 from at least one of the upper wall and the bottom plate of the tube 5.
As shown in FIGS. 3B, 7, and 8, in this alternative embodiment, a partition portion 5 a that is a convexly bent bottom plate portion of the lower plate 7 of the tube 5 is extended in the longitudinal direction. As shown in FIG. 3C, the partition portion 5a may be formed by protruding from both the upper wall and the bottom plate of the tube 5, or the partition portion 5a may be provided only on the upper wall.

Since the forward path part and the return path part can be clearly separated in the tube 5 by the partition part 5a, it is easy to prevent rattling and right / left misalignment when the offset fin 8 and the waby fin 9 are arranged on the tube 5. Can be positioned.
Moreover, since the rigidity of the tube 5 increases by the partition part 5a, the tube 5 that can withstand high temperature and pressure can be realized.

1 is a perspective view of a U-turn type EGR cooler according to an embodiment of the present invention. It is a perspective view of the tube assembly built in the U-turn type EGR cooler. (A) is sectional drawing of the tube which concerns on embodiment of this invention, (b) And (c) is sectional drawing of the tube which concerns on another aspect. It is a disassembled perspective view of the tube which concerns on embodiment of this invention. It is a figure which shows the offset fin built in the tube, (a) is a perspective view, (b) is explanatory drawing. It is a figure which shows the waveby fin built in the tube, (a) is a perspective view, (b) is explanatory drawing. It is a disassembled perspective view of the tube which concerns on another aspect of this invention. It is a horizontal sectional view of the tube. It is a disassembled perspective view of the tube used for the conventional EGR cooler. It is a top view of the conventional U-turn type EGR cooler.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shell 1a Cooling water inlet pipe 1b Cooling water outlet pipe 2 Arc header 3 Inlet / outlet header 3a Inlet pipe 3b Outlet pipe 3c Partition plate 4 Tube assembly 5 Tube 5a Partition part 6 Upper plate 6a Dowel 7 Lower plate 8 Offset fin 9 Wayby fin 10 End plate 11 Tube 11a Upper plate 11b Lower plate 12 End plate

Claims (4)

A U-turn EGR comprising an exhaust gas inlet and outlet arranged in parallel on one end face of a rectangular tube-like shell surrounding the heat exchanging portion, and the opposite end face closed with an arc header formed in an arc shape. A cooler,
In the heat exchanging part, a large number of tubes are placed horizontally and closed by providing a circular arc part at one end of the flat tube,
In this tube, an offset fin, which is provided between the inlet and the arc portion and forms the forward path portion, and a waby fin which is provided between the arc portion and the outlet and forms the return portion are arranged in parallel. U-turn type EGR cooler characterized by being arranged.   2. The U-turn type EGR cooler according to claim 1, wherein the tube is formed by joining an upper plate made of an upper wall and a side wall and a lower plate made of a bottom plate and a side wall.   2. The U-turn type EGR cooler according to claim 1, wherein a partition part for partitioning the forward path part and the return path part is projected from at least one of an upper wall and a bottom plate of the tube.   The U-turn type EGR cooler according to claim 1, wherein a tube assembly in which a large number of the tubes are stacked and a tube assembly formed by bundling and fixing the end portion on the inlet / outlet side is inserted into the shell and the arc header assembly. .

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