JP2000310161A - Egr cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an (exhaust gas recirculation)EGR cooler having improved cooling efficiency without causing clogging even used to exhaust gas containing particulates such as in a diesel engine. SOLUTION: This device cools exhaust gas, in an internal combustion engine to be made recirculate into a combustion chamber, by cooling water, and an exhaust gas chamber 3 is composed of plural spiral air chambers 3-1 and 3-2. Any chamber 3-1 and 3-2 is opened into each gas inlet 4 and outlet 5 for the exhaust gas, and the thickness W of space parts in the chambers 3-1 and 3-2 is formed into a thin type by nearing two opposite cooling walls 8. The space parts are extended so as to be uncontacted with each other, while folded and bent from nearby the center part 22 in order to obtain the spiral shapes of the chambers 3-1 and 302, to thicken the thickness of an end part 9 to the utmost, and the outer side of the chamber 3 is made a cooling water chamber 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EGR cooler, and more particularly to a cooling device for cooling a high-temperature exhaust gas when the exhaust gas is recirculated to an intake side in an internal combustion engine.

[0002]

2. Description of the Related Art Exhaust gas recirculation (EGR) for improving fuel efficiency while complying with exhaust gas regulations for internal combustion engines.
It has become essential to do. For that purpose, it is necessary to cool the recirculated exhaust gas, and it is well known that an EGR cooler is used.

[0003]

However, since the exhaust gas of an internal combustion engine contains components that corrode metals, the exhaust gas has been conventionally used.
Stainless steel is used for the GR cooler. However, there is a problem that it is difficult to obtain sufficient cooling efficiency because stainless steel has poor thermal conductivity. Therefore, measures such as increasing the heat transfer area by reducing the diameter of the heat exchange pipe have been taken, but when the pipe diameter is reduced, particulate matter (so-called soot) in the exhaust gas of the diesel engine is reduced. There is a problem that the cooling efficiency and the pressure loss increase due to the adhesion and deposition on the pipe wall.

The present invention has been made in view of the above problems, and an EGR cooler having improved cooling efficiency without causing clogging even when used for exhaust gas containing fine particles such as a diesel engine. It is intended to provide.

[0005]

An EGR cooler according to the present invention for achieving the above object is a device for cooling exhaust gas recirculated to a combustion chamber of an internal combustion engine with cooling water, the exhaust gas chamber comprising: Consisting of a plurality of spiral air chambers, each air chamber has an inlet for introducing and discharging exhaust gas to and from the device.
Opening at the outlet, the two opposing cooling walls are brought closer to each other to form a thinner space in the air chamber, and to bend or curve from near the center of the device to obtain a vortex of each air chamber. While extending so as not to contact each other, the thickness is made the thickest at the end in the extending direction, and heat exchange is performed on the entire cooling wall using the outside of the exhaust gas cooling chamber as a cooling water chamber. Things.

[0006] The material of the cooling wall is not particularly limited, and any material may be used as long as it is excellent in heat conductivity, has a certain rigidity, and has moderate corrosion resistance. Preferred materials include a thin aluminum plate.

The opening opening toward the center does not need to be opened over the entire length of the air chamber in the exhaust gas flow direction, and can be provided separately on the exhaust gas inlet side and the outlet side.

The plurality of air chambers need not communicate with each other throughout the exhaust gas flow direction, and the central portions in the exhaust gas flow direction are separated from each other, and the exhaust gas flowing into the exhaust gas cooling chamber is supplied to each air chamber. Can be forcibly pushed into the device.

There is no particular limitation on the mounting position of the cooling water inlet opening to the cooling water chamber, but the cooling water inlet may be opened at a position where the cooling water is easily directed to the center of the device along the spirally formed cooling wall. Similarly, the mounting position of the cooling water outlet is not particularly limited, but it is preferable to open the cooling water outlet at a position where the cooling water flowing out from the central portion of the device can be easily discharged.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. EGR cooler 1 of the present invention according to the first embodiment shown in FIGS.
Arranges an exhaust gas chamber 3 coaxially arranged in a cylindrical device main body 2 and introduces high-temperature exhaust gas from a gas inlet 4;
The low temperature exhaust gas is discharged from the gas outlet 5.

The exhaust gas chamber 3 is manufactured by processing a thin aluminum plate and, as shown in FIG. 3, comprises two air chambers 3-1 and 3-2. 3-2 has two cooling walls 8 (FIGS. 2 and 3) which communicate with the central exhaust gas passage 6 through the openings 7 and face each other. The thickness W of the air chambers 3-1 and 3-2 composed of the opposed cooling walls 8
Is formed such that the thickness W-2 on the end 9 side is larger than the thickness W-1 on the opening 7 side (W-1 <W-2).

The central exhaust gas passage 6 is connected to the intermediate portion C
It is also possible to force the exhaust gas into the air chambers 3-1 and 3-2.

The cross sections of the air chambers 3-1 and 3-2 are formed in a bent shape or a curved shape so as to form a spiral shape in the same direction from the central exhaust gas passage 6 as shown in FIG. Thus, a larger cooling area can be obtained in the narrow apparatus main body 2.

The cooling water chamber 10 is formed between the outside of the exhaust gas chamber 3 and the casing of the apparatus main body 2.
As shown in FIG. 2, the air chamber 3-
It was installed at the position where cooling water flows toward the opening 12 in the lower part of 1, 3-2 (therefore, at two places). Similarly, the cooling water outlet 13 was attached to a position (thus also two places) flowing out from the opening 12 in the upper part of the air chambers 3-1 and 3-2.

As described above, since the air chambers 3-1 and 3-2 are communicated with each other, even if the particulate matter floating in the exhaust gas adheres and accumulates on the cooling wall 8 and the gas partially stops flowing. ,
There is no risk of clogging, and the cooling wall 8 has a spiral continuous surface to increase the heat transfer area, so that the cooling efficiency can be improved. In addition, E
Since the GR cooler 1 has a relatively simple structure in which the plate-shaped cooling wall 8 is processed, a water leakage accident is unlikely to occur, repair and maintenance costs can be reduced, and reliability can be improved. The size of the cooler can be reduced.

FIGS. 5 to 7 show an EG according to the first embodiment.
A procedure for manufacturing the R cooler 1 will be described. As shown in the first step in the upper part of FIG. 5, a thin plate 13 made of aluminum is placed on a mold 14, the mold 15 is dropped from above and processed into the shape shown in FIG. 6, and then the arrow 16 is cut off. One side portion of the exhaust gas chamber 3 was made. Note that reference numerals 6, 7, 8 shown in FIG.
Indicates portions that become the central exhaust gas passage 6, the opening 7, and the cooling wall 8 described with reference to FIGS.

Next, a deformation-preventing corrugated plate 17 is arranged at the portions to be the air chambers 3-1 and 3-2, and one side portion of the other exhaust gas chamber 3 is put on the other side in a butt-like manner. As shown in FIG. 8, the central exhaust gas passage 6 is fixed by the mold 14 and rotated while pressing the mold 15 to form the air chamber 3.
Exhaust gas chamber 3 (FIG. 9) in which -1 and 3-2 are swirled can be obtained.

FIG. 10 illustrates another method for obtaining the same unshaped exhaust gas chamber 3 'as described above. That is, in FIG. 10, the aluminum sheet material 13 is disposed on the mold 14, and the mold 15 is dropped from above to form the vertically divided central exhaust gas passage 6 and the air chamber 3-1 (or 3-2). And the arrow part shown in FIG.
16 was cut off, and the vertically divided central exhaust gas passage 6 and air chamber 3
-1 (or 3-2) is obtained.

Next, as shown in FIG.
(Or 3-2) with the deformation preventing corrugated plate 17 inserted
When the butt portions 18 are welded to each other in a butt shape (not shown), an unshaped exhaust gas chamber 3 'similar to that of FIG. 7 can be obtained. Subsequent steps may be processed by the procedure shown in FIG. 8 to form the exhaust gas chamber 3 shown in FIG.

Next, a method of attaching the exhaust gas chamber 3 to the apparatus main body 2 will be described with reference to FIG. As shown in FIG.
The body of the apparatus main body 2 to which the cooling water inlet 11 and the cooling water outlet 13 are attached in advance is placed on the exhaust gas chamber 3, and the central exhaust gas passage 6 protruding from both sides is connected to the cylindrical portion 20 of the mirror portion 19 (the gas inlet). 4 or outlet 5) (FIG. 11). Then, the EGR cooler 1 can be obtained by welding the respective butted portions 18 and the portions 21 (FIG. 11) of the central exhaust gas passage 6 projecting from the cylindrical portion 20 by welding.

FIG. 12 shows a modification of the first embodiment, in which the air chambers 3-1 and 3-2 have one or more spirals. As described above, the cooling area can be increased by using the apparatus main bodies 2 having the same size.

The EGR cooler 1 according to the second embodiment shown in FIG. 13 has a central exhaust gas passage 6 shown in FIGS. 1-4 except for an exhaust gas inlet / outlet (not shown). -
The cooling water inlet 11 and the cooling water outlet 13 (13 not shown) are opened toward the opening 12 like the parts 1 and 3-2, and the vortex of the cooling water chamber 3 is formed. This makes it easier for the cooling water to flow into 10 ', thereby improving the cooling efficiency. The other configuration is the same as that of the first embodiment.
The same reference numerals are given to the same members as 4 and the description is omitted.

The EGR cooler 1 of the third embodiment shown in FIG. 14 has openings 12 of the air chambers 3-1 and 3-2 on the cooling water inlet 11 side.
The closer the cooling wall 8 is to the cooling water inlet 11 (that is, the lower side in the figure), the deeper the cut end 9 is, and the spiral portion 10 ′ of the cooling water chamber 10 is formed.
In addition, the cooling water is made easier to flow in and out, and the cooling efficiency is improved.

The EGR of the fourth embodiment shown in FIGS.
The cooler 1 is different from the exhaust gas chamber 3 described in the first to third embodiments in that the central exhaust gas passage 6 is cut in the middle and separated from each other at the central part 22 of the exhaust gas chamber 3. The exhaust gas flowing into the air chamber 3 is formed so as to always flow into one of the air chambers 3-1 and 3-2, thereby improving the cooling efficiency.

[0025]

According to the EGR cooler of the present invention described above, the exhaust gas chamber is formed to be spiral and thin to increase the cooling area as much as possible, so that the cooling efficiency per unit deposition of the apparatus can be improved. The size of the device can be reduced. Further, the particulate matter in the exhaust gas due to the expansion of the cooling area is attached to the air chamber to reduce the thickness of the particulate matter to prevent clogging, and even if the particulate material is deposited between opposing cooling walls, the exhaust gas is Since the surroundings can be circulated, there is no risk of clogging, and it is possible to prevent a decrease in cooling efficiency and reduce labor and cost required for maintenance and repair.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of an EGR cooler according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II (two places) of FIG.

3 is a development view in which a cross section in a width direction before the exhaust gas chamber shown in FIG.

FIG. 4 is a front view of FIG. 3;

FIG. 5 is a perspective view showing an outline of a molding process of a manufacturing process of the spiral exhaust gas chamber shown in FIG. 1;

6 is a perspective view showing an outline of a formed body in the step shown in FIG. 5 and a preparation step for moving to the next step.

FIG. 7 is a perspective view showing a shape of an exhaust gas chamber before being formed into a spiral shape.

FIG. 8 is a view for explaining an outline of a process of spiraling the air chamber of the unformed exhaust gas chamber shown in FIG.

FIG. 9 is a perspective view showing the exhaust gas chamber of the first embodiment shown in FIG.

10 is a perspective view illustrating another method of manufacturing the exhaust gas chamber before the spiral shape shown in FIG. 7 for each process, in which a state before processing of a thin plate material, a state after processing, and The steps of inserting the deformation preventing corrugated sheet are shown respectively.

FIG. 11 is a process explanatory view of attaching the exhaust gas chamber shown in FIG. 10 to the apparatus main body, where FIG. 11 is a perspective view showing a state of attachment, and FIG. ing.

FIG. 12 is a modification example of the exhaust gas chamber of the first embodiment shown in FIGS.

FIG. 13 is an explanatory view of a main part of an EGR cooler according to a second embodiment of the present invention.

FIG. 14 is a perspective view of an exhaust gas chamber of an EGR cooler according to a second embodiment of the present invention.

FIG. 15 is a development view of an exhaust gas chamber of an EGR cooler according to the second embodiment of the present invention.

16 is a sectional view in which the exhaust gas chamber shown in FIG. 15 is formed in a spiral shape.

[Explanation of symbols]

 3 Exhaust gas chamber 3-1 Air chamber 3-2 Air chamber 4 Gas inlet 5 Gas outlet 8 Cooling wall 9 End 10 Cooling water chamber 22 Central part W Thickness

Claims (2)

[Claims] An apparatus for cooling exhaust gas recirculated to a combustion chamber of an internal combustion engine with cooling water, wherein the exhaust gas chamber comprises:
It is composed of a plurality of spiral air chambers, each of which opens at an inlet / outlet for introducing / discharging exhaust gas to / from the apparatus, and makes two opposing cooling walls close to each other so that the thickness of the air chamber space is reduced. Are formed thin, and bent or curved from the vicinity of the center of the device to obtain a spiral shape of each of the air chambers, and extend so as not to contact with each other, and the thickness is increased at the end in the extending direction. An EGR cooler in which the outside of the exhaust gas cooling chamber is used as a cooling water chamber and heat exchange is performed on the entire cooling wall. 2. A cooling water inlet opening to the cooling water chamber,
Along the cooling wall formed in a spiral shape, an opening is provided at a position where the cooling water is easily directed to the center of the device, and a cooling water outlet is provided.
2. The EGR cooler according to claim 1, wherein the EGR cooler is opened at a position where the cooling water flowing out from the central portion of the device is easily discharged.