JP3663799B2 - Heat exchanger - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat exchanger, and is effective when applied to a refrigeration cycle using a combustible fluid (gas) such as propane or butane as a refrigerant.
[0002]
[Prior art]
An evaporator in a heat exchanger of a refrigeration cycle using chlorofluorocarbon as a refrigerant normally constitutes a tube and a tank section by laminating and joining a large number of thin plates formed in a predetermined shape.
[0003]
[Problems to be solved by the invention]
By the way, in recent years, refrigeration cycles using a flammable fluid such as propane or butane as a refrigerant have been actively studied as a countermeasure against chlorofluorocarbons. A heat exchanger considering leakage is desired.
[0004]
As a heat exchanger in consideration of leakage, for example, Japanese Patent Laid-Open No. 58-120087 proposes a double cylindrical tube structure.
However, since the one described in the above publication is a heat exchange for a water supply and has a simple double cylindrical tube structure, as described above, a large number of sheets are taken into consideration when considering the joining property of the tube and the tank portion located inside. The above-mentioned publication cannot be applied as it is to a heat exchanger (hereinafter referred to as a laminated heat exchanger) configured by laminating and joining thin plates.
[0005]
Specifically, since the laminated heat exchanger has a large number of joints, it is necessary to consider the balance between the joint strength of the joints (particularly the joints in contact with the atmosphere) and the strength of the thin plate itself. There is.
In view of the above points, an object of the present invention is to provide a heat exchanger in which leakage of fluid (refrigerant) is considered in a heat exchanger configured by stacking and joining a plurality of thin plates.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention uses the following technical means.
In invention of Claims 1-3, among both the thin plates (31, 32, 51, 52) which form the space | gap (4) of a tube (2) and a tank part (3), and a covering member (5), The joining length of the joint portion of the contact portion (A, B) that contacts the second fluid that exchanges heat with the first fluid is equal to or greater than the thickness of the thin plate of the contact portion (A, B).
[0007]
Thereby, before a crack occurs in the thin plate (31, 32, 51, 52) due to corrosion, fatigue failure, or the like, it is possible to suppress the occurrence of a crack in the joint, and the first fluid is heated from the joint. The possibility of leakage to the outside of the exchanger can be reduced.
The invention according to claim 2 is characterized by having a valve device (11) for communicating the gap (4) and the external space when the pressure of the gap (4) fluctuates from a predetermined pressure range. .
[0008]
By the way, when the pressure of the gap (4) fluctuates from a predetermined pressure range, it is considered that at least one of the first thin plate (31, 32) and the second thin plate (51, 52) has cracked.
In the present invention, when the pressure of the gap (4) fluctuates from the predetermined pressure range, the gap (4) and the external space can be communicated with each other, so that the first thin plate (31, 32) is temporarily cracked. When the refrigerant leaks out, the first fluid can be quickly released to the external space.
[0009]
As in the third aspect of the present invention, a third fluid higher than the pressure of the second fluid and lower than the pressure of the first fluid is enclosed in the gap (4), and the pressure in the gap (4) is reduced. You may control a valve apparatus (11) based on the detected value of the pressure detection means (10) to detect.
The invention according to claim 4 has a joint (A) between the first thin plates (31, 32) that directly contacts the second fluid that exchanges heat with the first fluid. And
[0010]
In addition, the code | symbol in the bracket | parenthesis of each said means shows a corresponding relationship with the specific means of embodiment description later mentioned.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In this embodiment, since the heat exchanger according to the present invention is applied to an evaporator (evaporator) of a vehicle air conditioner, FIG. 1 is a front view of the evaporator 1 (viewed from the air flow direction). .
Reference numeral 2 denotes a plurality of tubes through which the refrigerant (first fluid) flows, and reference numeral 3 denotes a tank unit that distributes the refrigerant to the plurality of tubes 2 or collects the refrigerant flowing out of the plurality of tubes 2. As shown in FIGS. 2 and 3, the tube 2 and the tank unit 3 are configured by laminating a large number of first aluminum thin plates 31 and 32 that are press-formed into a predetermined shape. 2 is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 3 is a cross-sectional view of the tank portion 3 as viewed from the direction of air flow.
[0012]
Moreover, the tube 2 and the tank part 3 are covered with a covering member 5 disposed with a predetermined gap 4 between the first thin plates 31 and 32, and the covering member 5 has a predetermined shape. A plurality of second thin plates 51 and 52 formed as a set are stacked and joined together with the first thin plates 31 and 32.
In the tube 2, as shown in FIG. 2, inner fins 6 that increase the contact area with the refrigerant and increase the heat exchange capability are disposed, and the tube 2 (first thin plate) is disposed in the gap 4. 31 and 32) are provided with heat conduction fins 7 for promoting heat conduction from the external space (second thin plate 51). In addition, 8 is a corrugated fin which contacts air (2nd fluid) and accelerates | stimulates heat exchange with a refrigerant | coolant and air.
[0013]
By the way, in this embodiment, among the thin plates 31, 32, 51, and 52 that form the gap 4, the joining lengths of the joining portions of the contact portions A and B that are in contact with air are as shown in FIGS. The thickness of the thin plates 31, 32, 51, 52 of the contact parts A, B is equal to or greater than that. Incidentally, in this embodiment, the thickness of the thin plate is 0.45 mm (both thin plates are the same), and the joining length of the contact portions A and B is 3 mm.
[0014]
In addition, when the thickness of the 1st thin plates 31 and 32 and the 2nd thin plates 51 and 52 differs, it is desirable to select joining length on the thicker thickness reference | standard, and joining length is thickness used as a reference | standard. 5 times or more is more desirable.
Incidentally, the two thin plates 31, 32, 51, 52 are both aluminum thin plates coated on both sides with a brazing material, and these are heated and brazed and joined in a furnace.
[0015]
In FIG. 1, reference numerals 91 and 92 denote connection pipes for connecting the evaporator 1, and the connection pipe 9 communicates with an inner cylindrical pipe (not shown) communicating with the tank portion 3 (tube 2) and the gap 4. It has a double cylindrical tube structure consisting of an outer tube. The outer tube communicates with the outside of the passenger compartment (external space).
A pressure sensor (pressure detecting means) 10 for detecting the pressure in the gap 4 is disposed on the outlet side of the evaporator 1 in the connection pipe 91 on the discharge side. An electromagnetic valve (valve device) 11 for controlling the communication state between the outside of the passenger compartment and the outer cylinder pipe is disposed in the cylinder pipe. The output from the pressure sensor 10 is input to a control device (not shown), and the control device controls the opening and closing of the electromagnetic valve 11 based on the output from the pressure sensor 10.
[0016]
In addition, fluid (nitrogen in this embodiment) is present in the gap 4 at a pressure (1.5 kgf / cm ² in this embodiment) that is higher than atmospheric pressure and lower than the pressure of the refrigerant (in the tube 2). The control device opens the electromagnetic valve 11 when the pressure in the gap 4 fluctuates from a predetermined pressure range, and communicates the gap 4 with the outside of the passenger compartment, and warning means such as a buzzer and a lamp toward the passenger A warning is issued.
[0017]
Here, the reason why the operation of the solenoid valve 11 is changed from the predetermined pressure range is that the pressure change due to the temperature change in the gap 4 is taken into consideration.
Next, features of the present embodiment will be described.
According to the present embodiment, the joining length of the joint portion of the contact portions A and B is equal to or greater than the thickness of the thin plates 31, 32, 51, and 52 of the contact portions A and B. Before the thin plates 31, 32, 51, 52 are cracked (cracked), it is possible to suppress the occurrence of cracks at the joints, thereby reducing the possibility of refrigerant leaking out of the evaporator 1 from the joints. be able to.
[0018]
By the way, when the pressure of the space | gap 4 fluctuates from the predetermined pressure range, it is considered that a crack has occurred in at least one of the first thin plates 31 and 32 and the second thin plates 51 and 52. That is, when the pressure of the air gap 4 is increased, it is considered that the first thin plates 31 and 32 are cracked. On the other hand, when the pressure is decreased, the second thin plates 51 and 52 are cracked. Conceivable.
[0019]
In the present embodiment, when the pressure in the gap 4 fluctuates from a predetermined pressure range, the electromagnetic valve 11 is opened. Therefore, if the first thin plates 31 and 32 are cracked and the refrigerant leaks, The refrigerant can be quickly discharged out of the passenger compartment. Even if only the second thin plates 51 and 52 are cracked, a warning is issued, so that the occupant can know that an abnormality has occurred in the evaporator 1.
[0020]
When cracks occur in both thin plates 31, 32, 51, 52, it is considered that the gap 4 is sufficiently larger than the cracks generated in the second thin plates 51, 52. , 32, almost the entire amount of refrigerant leaking from the cracks generated is released outside the passenger compartment.
Incidentally, as is clear from the above description, the air gap 4 detects whether or not cracks (including cracks in the joints) have occurred in the first thin plates 31 and 32 together with the pressure sensor 10, and the leaked refrigerant is removed. The air gap 4 has a function of discharging outside the passenger compartment, and the air gap 4 can be said to be a leakage detection flow path.
[0021]
By the way, when the first thin plates 31 and 32 are brazed (heated in the furnace), the air in the space (tube 2 and tank portion 3) formed by the first thin plates 31 and 32 expands. It is necessary to evacuate the air.
Therefore, in this embodiment, in order to facilitate the above operation, as shown in FIGS. 2 and 3, a portion (contact portion A) that is in direct contact with air is present in the joint portion of the first thin plates 31 and 32. Is provided.
[0022]
(Other embodiments)
In the above-described embodiment, the opening control of the gap 4 is electrically controlled by the pressure sensor 10 and the electromagnetic valve 11, but instead of this, the pressure is mechanically detected and the valve is opened like a relief valve. Also good.
Incidentally, since the relief valve is normally opened when the pressure becomes a set value or more, it is difficult to determine whether or not the second thin plates 51 and 52 have cracked. However, even if both thin plates 31, 32, 51 and 42 are cracked, if the relief valve is opened, the leaked refrigerant can be quickly discharged out of the passenger compartment as described above. Instead of the pressure sensor 10 and the electromagnetic valve 11, a relief valve may be used.
[0023]
Moreover, in the above-mentioned embodiment, although the site | part (contact site A) which contacts air directly was provided in the junction part of the 1st thin plates 31 and 32, as shown in FIG. All of the joints may be covered with the covering member 5.
In the above-described embodiment, the heat exchanger according to the present invention has been described by taking the evaporator of the vehicle air conditioner as an example. However, the present invention also applies to other heat exchangers such as an evaporator of a domestic air conditioner. Can be applied.
[Brief description of the drawings]
FIG. 1 is a front view of an evaporator.
FIG. 2 is a cross-sectional view taken along the line AA of FIG.
FIG. 3 is a cross-sectional view of the tank portion as viewed from the air flow direction.
FIG. 4 is a cross-sectional view of a tank unit according to a modification as seen from the direction of air flow.
[Explanation of symbols]
1 ... Evaporator, 2 ... Tube, 3 ... Tank, 4 ... Gap,
5 ... Cover member, 10 ... Pressure sensor (pressure detection means),
11 ... Solenoid valve (valve device).

Claims (4)

A plurality of tubes (2) through which the first fluid circulates, and the first fluid is distributed to the plurality of tubes (2) or the first fluid flowing out from the plurality of tubes (2) is collected. The tank part (3)
A heat exchanger in which the tube (2) and the tank portion (3) are configured by laminating and joining a plurality of first thin plates (31, 32) molded into a predetermined shape,
A predetermined gap (4) is interposed between the first thin plates (31, 32), and a covering member (5) that covers the tube (2) and the tank portion (3) from the outside is provided.
The covering member (5) is configured by laminating and joining a large number of second thin plates (51, 52) together with the first thin plates (31, 32) formed into a predetermined shape,
Furthermore, of the thin plates (31, 32, 51, 52) that form the gap (4), the joint portion of the contact portion (A, B) that contacts the second fluid that exchanges heat with the first fluid. The joining length is equal to or greater than the thickness of the thin plate of the contact portion (A, B). The heat according to claim 1, further comprising a valve device (11) for communicating the gap (4) with an external space when the pressure of the gap (4) fluctuates from a predetermined pressure range. Exchanger. In the gap (4), a third fluid higher than the pressure of the second fluid and lower than the pressure of the first fluid is enclosed,
Furthermore, it has a pressure detection means (10) which detects the pressure in the said space | gap (4), and controls the said valve apparatus (11) based on the detected value of this pressure detection means (10). The heat exchanger according to claim 2. A plurality of tubes (2) through which the first fluid circulates, and the first fluid is distributed to the plurality of tubes (2) or the first fluid flowing out from the plurality of tubes (2) is collected. The tank part (3)
A heat exchanger in which the tube (2) and the tank portion (3) are configured by laminating and joining a plurality of first thin plates (31, 32) molded into a predetermined shape,
A predetermined gap (4) is interposed between the first thin plates (31, 32), and a covering member (5) that covers the tube (2) and the tank portion (3) from the outside is provided.
The covering member (5) is configured by laminating and joining a large number of second thin plates (51, 52) together with the first thin plates (31, 32) formed into a predetermined shape,
The heat exchanger further comprises a joint (A) between the first thin plates (31, 32) that directly contacts a second fluid that exchanges heat with the first fluid.

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