JPS59129396A - Heat exchanger - Google Patents

Abstract

PURPOSE:To prevent a core plate from being cracked by stress corrosion cracking, by providing a gap between a bottom wall of a holding groove of a core plate and a bottom wall of a calking plate, in a heat exchanger comprising a synthetic resin made tank connected by calking to a metallic heat-exchanging core. CONSTITUTION:A radiator comprises a metallic heat-exchanging core part 2, which comprises copper made corrugated fins 2a and brass made tubes 2b, and synthetic resin made tanks 1, 3 which are sealdedly fitted respectively to the upper and lower ends of the core part 2. A predetermined gap is provided between the bottom wall 4b of the holding groove 4d of the core plate 4 and the bottom wall 5b of the calking plate 5. Accordingly, even when the calking plate 5 is calked, a compressive stress is generated at the surface of the bottom wall 4b of the holding groove 4d on the side of a seal ring 6. Namely, since the gap delta is provided between the bottom wall 4b and the bottom wall 5b, the bottom plate 4b subjected to a load at the time of bending working absorbs the bend at the gap delta on the lower side thereof, so that the stress at the surface of the bottom wall 4b is a compressive stress, whereby the core plate is restrained from being cracked by stress corrosion cracking.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a +JP exchanger in which a synthetic resin tank is attached to a metal heat exchange core by caulking, and is used, for example, in a heat exchanger for an automobile lanator or a heat exchanger for an automobile cooling system. It is a proper G6.

This type of heat exchanger, for example a heat exchanger for automobiles, is constructed as shown in FIG. That is, the lanator includes a metal heat exchange core part 2 including copper corkated fins 2a and yellow FIM tubes 2b, and a synthetic resin tank 1.3 sealed at the upper and lower ends thereof. upper tank 1
is provided with a cooling water supply Dl a and a cooling water inflow pipe 1b, and the lower tank 3 is provided with a cooling water outflow pipe 3a, but basically the upper and lower tanks 1.3 are the same. Since this is the structure, only the upper tank l will be described below. It should be understood that the following explanation can also be applied to the lower tank 3 if considered upside down.

FIG. 2 shows a conventional method of sealingly mounting the tank 3 to the core part 2. One end of the tank 3 is open, and a sealed space is formed by inserting this open end into the holding a4d of the core play 14 connected to the tube 2b. Therefore, the tank 3 has a substantially rectangular cross section along the entire circumference of the open end thereof, and is provided in the section 3C. The core plays 1 and 4 are made of brass, and a suitable means is attached to the end of the tube 2b.
For example, it is fixed with semi-IB attachment, brazing, etc. Also,
An elastic sealing material 6 made of a rubber O-ring is installed between the edge attachment portion 3c of the tank 3 and the bottom wall 4b of the groove portion 4d. Then, a tightening plate 5 made of an iron plate having a cross section of approximately a 2-shape (in the figure, it is an inverted 12-shape, but it is an 11-shape on the opposite side) with a claw portion 5a on the top edge is attached to the core plate 4. The pawl portion 5a is engaged with the groove portion 4C, and the pawl portion 5a is inserted at the top of the tooth edge attachment portion 3c of the tank 3. As a result, the elastic sole material 6 is deformed on the lower surface of the tank edge attachment=++3C, and is tightly sealed in the groove 4d of the core plate 4.

However, in the conventional rashek, as shown in Fig. 2, the height of the groove 4d of the core play I・4 is 1.
1 or the height of the constriction part I (is almost equal to
・When t9 is set at 5, the groove 4d of the core plate 4 and the bottom wall 4b
Tensile stress had been generated on the surface facing the inner seal.

Hereinafter, the mechanism of generating tensile stress in this conventional lassoator will be explained in more detail with reference to FIG.

In FIG. 3(a), an elastic sealing material 6 is placed on the bottom 4b of the core plate groove 4d, the tank edge attachment part 3c is fitted into this groove 4d, and the caulking plate 5 is engaged with the outer surface of the groove 4d. Show stages. At this time, since the caulking work has not yet been performed, there is naturally no strain in the bottom wall 4b of the groove portion 4d.

When the caulking work is started at the stage (b) in Fig. 3, an oblique load F1 is applied to the pawl portion 5a of the caulking plate 5, and the outer side wall 4a of the groove portion 4d is pressed against the tank Oh'l i & mounting portion 3c. As a result, the groove portion 4d is deformed by receiving a downward force, and a strain ε0 in the compressive direction is generated on the surface of the groove portion 4d and the wall 4b on the seal ring 6 side.

As the caulking work further progresses, as shown in FIG. 3(c), the load completely changes to a vertical load, which is transmitted to the groove bottom wall 4b via the outer side wall 4a. At this time,
Since the outer surface of the groove 4d is restrained by the caulking plate 5, the groove bottom wall 4b deforms into a convex strip toward the elastic sealing material 6, and a strain ε1 in the tensile direction is generated on the surface thereof.

At the completion stage of the caulking work shown in FIG. 3(d), the load F2 is removed and the pawl portion 5a of the caulking play).5 returns slightly upward under the action of springback. Therefore, the strain on the surface of the bottom wall 4b of the /IvI section is reduced to ε2. At this time,
The bottom wall also contains a compositional deformation strain ε3, and if the caulking plate 5 is removed and the restraint is released in the state of the cage, the bottom wall 4b will return to its initial state by an amount of elastic strain ε2−ε3. Become. Therefore, when the strain generation pattern of the conventional structure shown in FIG. 2 is expressed by length and line, it can be seen that elastic strain occurs in the tensile direction on the surface of the groove wall.

In this way, the fact that the surface of the groove bottom surface 4b, especially the side that is in direct contact with the seal ring 6, is placed under tensile stress has a very large effect on the corrosion of the core plays 1 and 4, as described below. become.

That is, in the case of an automotive lasoator, the cooling water present inside the tank 3 penetrates into the contact gap between the bottom wall 4b of the core plate groove 4d and the lower surface of the elastic sealing material 6, creating a crevice corrosion environment (2 In other words, corrosive components in the liquid that accumulates in the crevice are difficult to diffuse, and the immobile coating (oxide film) on the surface of the brass core play I tries to maintain its passivity by causing the corrosive components in the crevice to spread out. Oxygen in the liquid is consumed, resulting in a difference in oxygen concentration between the liquid in the gap and the liquid in the tank, forming an oxygen concentration cell.

Due to the battery action, the pH of the liquid in the gap decreases, and the resulting corrosive environment becomes extremely severe.

In addition, when pressure is applied to the inside A of the tank 3, the tank 3 tends to expand outward, and the y of the tank 3
lii The cart is transmitted outwardly through the outer wall 4a of the core bra 14 via the edge attachment portion 3c, and this load also causes tensile stress to be generated on the surface of the bottom wall 4b of the groove portion on the side of the seal ring 6.

If tensile stress is applied to the surface of the bottom wall 41) of the core plate groove 4c on the seal link 6 side under the above conditions, stress corrosion cracking will easily occur. Of course, the above fact has been elucidated as a result of various experiments conducted by the present inventors. In addition, the present inventors also confirmed through synthesis that when used as normal engine cooling water containing a large amount of components such as ammonia, the cracking life deteriorates rapidly.

The present invention was devised based on the experimental results elucidated by the inventors, and reduces the tensile stress generated on the inner seal ring side surface of the bottom surface of the retaining groove of the core brake 1, thereby preventing stress corrosion cracking. It is Ll-like to move ↑ to the direction of life.

Therefore, the present invention adopts a configuration in which a gap is provided between the core plate holding groove lower wall and the bottom wall of the caulking plate.

An embodiment of the present invention will be described below based on the drawings.

Since the basic structure of the heat exchanger is the same as that shown in FIG. 1, the explanation will be omitted, and the caulking plate 5 will be mainly explained. In this example, as shown in FIG. 4, a predetermined (0.4 mmJ° 1 degree) 1tJl gap is provided between the retaining groove 4d of the core plate 4 and the bottom wall 4b of the third brake 1-5. It is set up. Therefore, in this example, even when the tightening plate 5 is tightened, compressive stress is not applied to the surface of the back seal link 6 side of the retaining groove 4d of the core plate 4a on the bottom wall 4b. ing.

The mechanism of this compressive stress generation will be explained based on FIG. 5. (A) (B) (C) in Figure 5 (2 is (2) in Figure 3)
A) (B) (C) This corresponds to (D), and since (A) is before the strangling, it is the same as Figure 3. However, when the tightening operation is started (state (B)), in this example, the groove bottoms 4b of the core plays 1 and 4 are recessed more than the conventional ones due to the existence of the gap δ, and therefore, the seal ring 6 of the bottom 4b A large compressive pressure is generated on the surface in contact with.

Therefore, the choke gap progresses and the load becomes vertical,
The state in which it is transmitted to the groove bottom wall 4b via the outer side wall 4a (
Even in state (C)), the groove bottom wall 4b is somewhat recessed as before. Therefore, even in this state (c), compressive stress remains on the surface of the groove bottom wall 4b on the seal ring 6 side.

When the caulking work is completed (state (d)), the pawl portion 5a
Although the dent in the groove bottom wall 4b is somewhat reduced due to the springback, it is still dented, and compressive stress is generated on the seal ring side surface.

Therefore, in this example, since the swage gap δ is created when the bottom wall 4b of the core plate 4 and the bottom wall 5b of the swage plate 5 are joined together before swage, the core receives the cart during bending. The bending of the gap 6 below the plate bottom wall 4b (in the drawing) is absorbed, and the stress generated on the surface of the bottom wall 4b is in the compressive direction.

Therefore, in this example, even at the end of the caulking work,
This means that elastic strain occurs in the compressive direction on the surface of the bottom wall. Therefore, the above elastic strain (ε2-ε・3) is converted to stress σ-E (ε2-ε3) (where E is the longitudinal elastic modulus).
The experimental results, which were converted into stress values and arranged on the horizontal axis with δ, are shown in the sixth
As shown in the figure. As is clear from this figure, if δ≧0.2 fins, the stress on the surface of the groove 1+X wall becomes compressive stress and becomes stable. Therefore, the occurrence of stress corrosion cracking is significantly suppressed, and the life of this part is significantly extended.

In the above example, the height h of the side wall 4a of the core plate 4 was set to be the same as the height H of the constriction part, but as shown in FIG.
The width h may be lower than the constriction height t1. According to this example, when the tightening plate 5 is closed (state shown in (c) in Figure 3)
However, the core plate [the load in the strike direction is not directly applied to the side wall 4a, and therefore, combined with the effect of the gap δ mentioned above, the seal ring 1 of the core plate bottom wall 4b (
The 1111 plane is definitely in a compressive stress state. Therefore, stress corrosion cracking at this location is better prevented.

Furthermore,! In the example shown in Fig. 417, a step 5c is formed on the bottom 5b of the constriction plate 5, and the [Iy wall 4 of the core plate 4 is placed on this step 5c, so that the gap δ can be managed more reliably. Can be done quickly and accurately.

As explained above, in the heat exchanger of the present invention, a gap is provided between the bottom of the holding groove of the core plate and the bottom wall of the choke plate, so that the surface of the bottom of the holding groove of the core plate in contact with the inner seal ring is The core plate is always placed under compressive stress, which suppresses the occurrence of stress corrosion cracking in the core plate.
It has the excellent effect of significantly extending the life of the heat exchanger.

[Brief explanation of drawings]

Figure 1 is a front view of a conventional heat exchanger, Figure 2 is a sectional view taken along the arrow n-II in Figure 1, and Figure 3 is a view of the core plate surface during the tightening process of the conventional heat exchanger. An explanatory diagram showing the stress state, FIG. 4 is a sectional view showing the main part of the heat exchanger of the present invention, and FIG.
The figure is an explanatory diagram showing the stress state of the core play I and the surface due to the tightening process of the heat exchanger shown in @4. Figure 6 shows the relationship between the gap between the core plate and the choke plate and the stress on the core plate surface. The explanatory diagram shown in FIG. 7 is a sectional view showing the main parts of another example of the heat exchanger of the present invention. 1.3...Tank, 2b...Tube, 11...
Core play 1., 4C.. retaining groove, 5. choking plate. Agent B: Buried Earth Takashi Okabe Figure 4 Figure 5 (A) (B) (C) (=) Figure 6
Figure 7

Claims (1)

[Claims] A tube through which the cooling liquid flows; A constriction plate is provided to connect the tank and the core plate by sandwiching the tank and the retaining groove of the core plate, and a gap is provided between the comparison plate and the bottom of the retaining groove of the core plate I. Formed PIV exchanger.