JPS6360315B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a plate fin type heat exchanger, which is a heat exchanger mainly used in construction machinery, and which has plate fins made of a large number of laminated rolled steel plates. .

[Technical background of the invention and its problems]

In heat exchangers for construction machinery, the plate fins themselves are constructed from rolled steel plates in order to prevent the plate fins from being damaged or bent by sand or the like contained in the blast air. However, during manufacture of this heat exchanger made of rolled steel plate, there was a problem that the tube meandered at the root of the tube and the tube sheet. That is, in its manufacture, first, a large number of tubes 2 are passed through a plate fin 1 made of a large number of steel plates, and both open ends of the tubes 2 are respectively provided to penetrate through a tube plate 3 made of brass. Thereafter, one surface of the tube plate 3 and the open end of the tube 2 are immersed in a heated and melted solder bath as shown by the chain line in FIG. Then, the tube sheet 3 mainly expands in the longitudinal direction due to the heat of the solder bath. However, the plate fin 1 made of a steel plate has a smaller coefficient of linear expansion than the tube plate 3 made of brass. Therefore, tube plate 3
Since the elongation of the plate fins 1 is less, the tube 2 penetrated by both curves outward in the longitudinal direction into an arch as shown in FIG. Next, when the heat exchanger core is taken out from the solder bath and cooled, the tube plate 3 contracts and residual deformation occurs in the tube 2 as shown in FIG. 4. As described above, when the root portion of the tube is deformed, more stress is concentrated at the root portion of the tube as the construction machine moves or vibrates. This sometimes caused cracks in the tubes, resulting in so-called water leakage accidents in the heat exchanger. The cause of the deformation of the tube 2 is not only due to the difference in linear expansion coefficient between the plate fin 1 made of steel plate and the tube sheet 3 made of brass, but also due to the difference in thermal conductivity between the two. It seems that he is getting used to it. That is, the thermal conductivity of the steel plate is extremely low compared to that of the brass plate. Therefore, when immersed in a solder bath, the tube plate 3 made of brass expands first, and the plate fin 1 made of a steel plate expands later, so that a difference in elongation occurs between the two, which causes the tube 2 to deform.

[Summary of the invention]

Therefore, the present invention prevents bending of the tube base during soldering of heat exchangers for construction machinery,
The purpose is to provide a heat exchanger with sufficient strength.

In the heat exchanger of the present invention, plate fins 1 made of a large number of steel plates are stacked at a slight distance from each other, and a large number of tubes 2 are passed through the plate fins 1. At the same time, both open ends of the tube 2 are disposed through a brass tube plate 3 to assemble a heat exchanger core. After that, the open ends of the tube sheet 3 and tube 2 are
Immerse it in a heated and molten solder bath. The present invention also relates to a plate-fin type heat exchanger in which the tube plate 3 and the outer peripheral surface of the open end of the tube 2 are brazed together. This heat exchanger is particularly characterized in that the plate fins in the portion A disposed close to the tube sheet 3 are made of a copper plate or a copper alloy plate.

Therefore, in this heat exchanger, the plate fins in the portion A close to the tube sheet 3 are made of copper plates or copper alloy plates, and the other plate fins are made of steel plates. Therefore, the linear expansion coefficient and thermal conductivity of the plate fins near the tube sheet 3 are close to those of the brass tube sheet 3. Therefore, tube plate 3
There is almost no difference in thermal strain during soldering between the tube 2 and the tube 2. Therefore, the base portion of the tube 2 is not deformed during soldering, and a highly reliable heat exchanger can be provided.

[Embodiments of the invention]

Next, embodiments of the present invention will be described based on the drawings.

In the heat exchanger of this embodiment, when assembling the heat exchanger core, a plurality of plate fins 1 made of copper plates are arranged in the area A close to each of the upper and lower tube sheets 3, and the other plate fins 1 are Plate fins 1 made of a large number of rolled steel plates are arranged in the part,
They are stacked at a slight distance from each other, and the tube 2 is passed through them. In this embodiment, the thickness of the portion A is approximately 50 mm to 80 mm. Next, the open end of the tube is slightly penetrated into the brass tube plate 3. The heat exchanger core thus assembled is then immersed in molten solder 4 as shown in FIG. That is, the tube 2 and tube plate 3 are relatively moved from the position indicated by the solid line to the position indicated by the two-dot chain line. Then, the heat of the molten solder 4 is transferred to the tube plate 3 and also to the plate fin 1 via the tube 2. Then, the plate fin 1 made of a copper plate or a copper alloy plate is elongated approximately equal to the amount of elongation of the tube sheet 3. Therefore, since there is no difference in thermal strain between the two, there is no risk that the tube 2 will deform as shown in FIG. This is a result of the temperature of each plate fin existing in the A portion becoming gradually lower as the distance from the tube sheet 3 increases, and the thermal strain decreasing accordingly.

According to experiments, the tube sheet 3 is made of brass (Shichisan Brass), a plate fin made of a copper plate is provided in the A part (50 mm to 80 mm) near the tube sheet 3, and a steel plate (SS) is provided in the other part B. ), the base of the tube 2 did not deform during soldering. Moreover, the same result could be obtained even if a brass plate was used instead of a copper plate. In addition, each condition in this experiment is H in Figure 1.
= 1490mm, E = 1500mm, C = 140mm, Thickness of tube plate 3 = 6mm, Thickness of copper plate or brass plate that is plate fin = 0.25mm, Thickness of steel plate that is plate fin = 0.25mm, Pitch of each plate fin = 4.0mm,
The temperature of the solder bath was set to 390°.

Incidentally, the linear expansion coefficient and thermal conductivity of the plate fins 1 and tube sheets 3 of the heat exchanger core are as follows.

Linear expansion coefficient of brass tube plate and brass plate fin = 19 x 1/1000000, thermal conductivity 0.96 (cal/cm
sec°C), linear expansion coefficient of copper plate fin 16.5
×1/1000000, thermal conductivity = 0.94 (cal/cmsec°C),
Linear expansion coefficient of plate fin made of rolled steel plate: 11.7×
1/1000000, thermal conductivity 0.18 (cal/cmsec°C).

〔Effect of the invention〕

In the present invention, plate fins 1 made of a large number of steel plates are stacked at a slight distance from each other, and a large number of tubes 2 are passed through them. At the same time, both open ends of the tube 2 are disposed through a brass tube plate 3 to assemble a heat exchanger core. Thereafter, the open ends of the tube sheet 3 and tubes 2 are immersed in a heated and melted solder bath. The present invention also relates to a plate-fin type heat exchanger in which the tube plate 3 and the outer peripheral surface of the open end of the tube 2 are brazed together. This heat exchanger is particularly characterized in that the plate fins in the portion A disposed close to the tube sheet 3 are made of a copper plate or a copper alloy plate.

The present invention has the above configuration and has the following effects.

(1) In this heat exchanger, the plate fins of part A, which are arranged adjacent to the tube sheet 3, are made of a copper plate or a copper alloy plate. This copper plate or copper alloy plate has a coefficient of linear expansion of plate fin 1 made of steel plate.
It is close to brass tube plate 3 compared to . Therefore,
When the open ends of the tube sheet 3 and the tubes 2 are immersed in a heated and molten solder bath, the plate fins themselves also expand by an amount approximately equal to the thermal expansion of the tube sheet 3.
Therefore, no difference in thermal expansion occurs between the tube sheet 3 and the plate fins 1 in the vicinity of the tube sheet 3. Therefore, during soldering, it is possible to prevent the tube from meandering, which occurs in the case of plate fins made only of steel plates, and to provide a highly reliable heat exchanger.

(2) Further, in the heat exchanger of the present invention, plate fins 1 made of a large number of steel plates are provided at positions other than those close to the tube sheets 3. Therefore, the mechanical strength of the plate fin 1 itself is increased, and the plate fin is extremely unlikely to be damaged by sand contained in the blown air, especially when used in a construction machine or the like. At the same time, the plate fins will not be easily deformed even if relatively small pebbles or the like contained in the air collide with the plate fins. Thereby, the durability of the heat exchanger can be increased.

(3) Furthermore, the heat exchanger of the present invention has a plate fin 1 made of a copper plate or a copper alloy plate near the tube sheet 3, and the plate fin made of the copper plate has a thermal conductivity that is extremely high compared to that of a steel plate. . Therefore, when the tip of the tube and the tube plate 3 are immersed in a heated and melted solder bath, the heat of the solder bath is transferred to the plate fins extremely quickly. Therefore, the plate fins 1 and the tube sheet 3 extend almost simultaneously with the tube sheet 3. Thereby, the tube plate 3 and the plate fin 1
It is possible to prevent the tube 2 from meandering due to a difference in thermal strain, with almost no difference in elongation between the two.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing an example of a plate-fin type heat exchanger, and Fig. 2 shows its tube 2 and tube plate 3.
FIG. 3 is an explanatory diagram showing the state of deformation of the tip of the tube that occurs during the soldering process;
FIG. 4 is an explanatory diagram of the second stage of the heat exchanger, and FIG. 5 is an explanatory diagram of the plate-fin type heat exchanger of the present invention. 1...Plate fin, 2...Tube, 3...
...tube sheet, 4...molten solder.

Claims (1)

[Claims] 1 A heat exchanger core is formed by passing a large number of tubes 2 through a plate fin 1 made of a large number of steel plates slightly spaced apart from each other, and by disposing both open ends of the tubes 2 through brass tube plates 3 respectively. In a plate fin type heat exchanger formed by assembling, the open end of the tube sheet 3 and the tube 2 are immersed in a heated and melted solder bath, and the tube sheet 3 and the outer peripheral surface of the open end of the tube 2 are brazed together. , a plate fin type heat exchanger characterized in that the plate fins of the portion A disposed close to the tube sheet 3 are made of a copper plate or a copper alloy plate.