JP2000282963A - Egr cooler device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of a soldered part by chamfering many holes formed on a tube sheet to be fitted with the end parts of many hole tubes, so as to form recessed parts of triangular section outside the tube sheet at inserting the tubes, and soldering so as to bury recessed parts. SOLUTION: Tube sheets 2 are arranged on the inside of both ends of a cylindrical main body 1 of an EGR cooler, and the outer circumferences are fixedly fitted to the inner circumference of the main body 1. Tubes 3 are respectively inserted into many holes 4 drilled on the tube sheet 2, and they are fixedly fitted by soldering. In this case, on the gas passage side of the holes 4 drilled on the tube sheet 2, chamfering parts 2a are formed so as to form recessed parts of triangular section by the tube sheet 2 and the tubes 3 inserted in the respective holes 4, and soldering is executed so as to bury the recessed parts to fix the tubes 3. Hereby, solder is prevented from penetrating the water side of the tube sheet 2, and reliability of the soldered part is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A tube sheet having a large number of holes is fixed to both ends of a tubular body, and both ends of a tube passing through the holes of the tube sheets at both ends are connected to the tube.
The present invention relates to an EGR cooler brazed to a seat.

[0002]

2. Description of the Related Art For example, a water-cooled multi-tube cooler used for an EGR cooler or the like is known.

[0003]

This cooler has a simple structure, and is convenient because it is small and has high heat resistance.
When used in a cooler, if the tube (gas conduit) cracks, the gas side and the water side become conductive, and the cooling water (tube cooling water) may pass through the tube and flow to the intake system, or It is conceivable that the high-temperature and high-pressure gas leaked from the tank raises the system pressure of the cooling water to cause a so-called “blow-back” from a vehicle or a water (sub) tank.

[0004] In order to confirm the possibility of the above (tube crack) and to confirm the crack site, a vibration test was performed on a structure composed of only the tube and the tube sheet. Was confirmed to occur. As a result of investigating the brazed part where the crack occurred, it was found that the surface of the brazed part was in a state of many sharp irregularities,
This acute angle unevenness is considered to be one of the possible causes of crack initiation. That is, when the brazing portion is present on the water side of the tube sheet, there is a possibility that conduction between the gas side and the water side due to the cracking of the brazing or the tube.

Accordingly, an object of the present invention is to provide an EGR cooler having a structure in which a gas side and a water side are not conducted even when a crack occurs in a “brazed” portion of a tube and a tube sheet.

[0006]

According to the present invention, a tube sheet having a large number of holes is fixed to both ends of a tubular body, and the ends of the tubes penetrating through the holes of the tube sheets at both ends are formed as described above. E brazed to tubesheet
In a GR cooler, these holes are chamfered so that a triangular cross section is formed on the outside of the tube sheet when the tube is inserted, and are brazed to fill the recess.

Further, according to the present invention, a tube sheet having a large number of holes is fixed to both ends of a tubular body, and the ends of the tubes passing through the holes of the tube sheets at both ends are attached to the tube sheet. In a brazed EGR cooler, tubes having collars inserted at both ends are inserted into holes of the tube sheets, and brazed from outside the tube sheet.

Further, according to the present invention, one end of the tube is expanded in a trumpet shape, and the expanded side is brazed to one tube sheet.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, an outer periphery of a tube sheet 2 is fixed to an inner periphery of a main body 1 inside both ends of a main body 1 of an EGR cooler formed in a cylindrical body. A plurality of tubes 3 are inserted and brazed into a large number of perforated holes 4.

A hood 5 is provided at both ends of the main body 1.
A gas inlet 7 is attached to one of the bonnets 5, or a bonnet 5 integrated with the gas inlet is attached to the other bonnet 5, and a gas outlet 8 is fixed to the other bonnet 5. A bonnet 5 integrated with a gas outlet is fixed, and an inlet 9 and an outlet 11 for cooling water are provided near both ends of the main body 1. In FIG. 1, the hood 5 and the gas inlet 7 are formed separately, but may be formed integrally.

FIG. 2 shows an enlarged cross section of a brazing portion between the tube sheet 2 and the tube 3. A hole 4 formed in the tube sheet 2 has a chamfered portion 2a formed on the gas passage side.
Section 3 formed by tube 3 inserted into hole 4
It is brazed so as to fill the angular recess.

The operation will be described below. As shown in FIG. 2, the wax does not enter the water side (left side in the figure) of the tube sheet 2, and sharp irregularities are generated on the brazing surface, and even if a crack is formed, the gas side of the tube sheet (right side in the figure). ), The tube is a non-vibrating part and does not have a crack leading to the water side.

Further, even if the wax enters the water side through a slight gap, the surface of the tube 3 is plated, so that it does not cause cracks.

FIG. 3 shows a second embodiment of the present invention. Collars 17 are attached to both ends of the tube 3, and a hole 16a into which the tube 3 fits is formed in the tube sheet 16. Are assembled so as to abut the tube sheet 16, and the tube sheet 16 and the tube 3 are brazed, or the tube sheet 16, the tube 3 and the collar 17 are brazed. The wax does not enter the interior (left side in the figure) from the collar 17,
Since the collar 17 also serves as a reinforcing member of the tube 3, a crack is formed from this portion, and conduction between the gas side and the water side is prevented.

FIG. 4 shows another embodiment of the present invention, in which a tube 13 having an expanded portion 13a in which one end of the tube 13 is expanded in a trumpet shape is different from the tube 3 used in the first and second embodiments. Used. At the time of assembling,
a acts as a stopper and the other end is a straight pipe. Here, conventionally, since the expanded portions 13a are formed at both ends of the tube, when the tubes 13 are collectively brazed by a heating furnace (not shown), a difference in the amount of thermal expansion between the tube 13 and the cylindrical body of the EGR cooler main body 1 is caused. , Residual stress exists after brazing. On the other hand, in the embodiment of FIG. 4, only one end is expanded by the tube 13 and the other remains a straight pipe. Therefore, even when the tube 13 and the main body shell are heated in a furnace (not shown), the difference in the amount of thermal expansion between
There is almost no residual stress as it is absorbed at the straight end of the tube 13. In other words, in the embodiment of FIG. 4, if the brazing material is temporarily applied to the tube 13 and the tube sheet 2 on the straight tube side by applying a brazing material, and the brazing is collectively brazed in a furnace,
The residual stress of the tube is slight, which is effective in preventing the tube from cracking, and has an advantage of good workability.

[0016]

The present invention is constructed as described above, and since the brazing of the tube and the tube sheet is not on the water side of the tube sheet, the brazing is affected by cracks entering from the unevenness of the surface of the brazing. Therefore, it is possible to prevent conduction between the gas side and the water side from fatigue fracture of the tube caused by "wax" due to vibration.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an EGR cooler showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a brazing portion between the tube and the tube sheet of FIG. 1;

FIG. 3 is a sectional view showing a brazed portion between a tube and a tube sheet according to a second embodiment.

FIG. 4 is a cross-sectional view showing a brazing portion according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Main body 2, 16 ... Tube sheet 3, 13 ... Tube 4 ... Hole 5 ... Bonnet 17 ... Color

Continuing from the front page (72) Inventor Yukio Konno 1-chome, 1-chome, Ageo-shi, Saitama Nissan Diesel Industry Co., Ltd. In-house (72) Inventor Hidefumi Fujiwara 1-1-1, Oji, Ageo-shi, Saitama Nissan Diesel Industry Co., Ltd. (72) Inventor Yuji Miyauchi 24-4-1 Shinjuku, Shimizu-cho, Sunto-gun, Shizuoka F-term (reference) 3G062 ED08 GA08 GA10 3L065 BA02 CA12 CA17

Claims (3)

[Claims] An EGR wherein a tube sheet having a large number of holes is fixed to both ends of a tubular body, and ends of the tubes passing through holes of the tube sheets at both ends are brazed to the tube sheet. EG, characterized in that the holes are chamfered such that a recess having a triangular cross section is formed on the outside of the tube sheet when the tube is inserted, and brazed to fill the recess.
R cooler device. 2. An EGR wherein a tube sheet having a large number of holes is fixed to both ends of a tubular body, and ends of the tubes passing through the holes of the tube sheets at both ends are brazed to the tube sheet. An EGR cooler device, wherein tubes having collars inserted at both ends thereof are inserted into holes of the tube sheets and brazed from outside of the tube sheets. 3. The EGR cooler device according to claim 1, wherein one end of the tube is expanded in a trumpet shape, and the expanded side is brazed to one tube sheet.