JPH0829016A - Outdoor heat exchanger for heat pump - Google Patents

Abstract

PURPOSE:To prevent the lowering in performance in summer season and effec tively restrict the lowering in performance of an evaporator to be caused by frosting in winter season by a method wherein projected and corrugated fins are of flat plate shape having no louver and in turn portions oppositely facing against flat tubes are formed with louvers. CONSTITUTION:Corrugated fins 5 formed in corrugated shape are arranged between flat surfaces of flat tubes tubes 4 and connected thereto. The corrugated fins 5 are integrally formed with projecting portions 5a projected from an air upstream end 4b of the flat tube 4 toward an air upstream side in an air flowing direction A. A projecting part 5a of the corrugated fin 5 is of a flat plate shape without a louver 5b, while the louver 5b is formed in a part oppositely facing against an air flowing direction of the flat tube 4 is formed. With such an arrangement, a reduction in condensing perforamnce in summer season is not produced and a reduction in performance of an evaporator caused by frosting in winter season can be restricted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outdoor heat exchanger for a heat pump used for an air conditioner for electric vehicles, households, etc.

[0002]

2. Description of the Related Art Conventionally, when the outdoor heat exchanger of this type is used as an evaporator in winter, the louver is turned off under the operating condition that the outside air temperature is low and the humidity is high. Frost is likely to occur on the corrugated fins, and the air passages of the corrugated fins are narrowed due to this frost, so that the performance of the outdoor heat exchanger is significantly reduced, and thus the heating capacity of the heat pump is significantly reduced.

Therefore, in the one disclosed in Japanese Patent Laid-Open No. 5-322478, the corrugated fin joined to the flat tube is divided into two parts, an air upstream side portion and an air downstream side portion of the flat tube. The corrugated fin has a louver-free flat plate shape as a whole, and a structure is proposed in which the tip (air upstream end) of this louver-free plate-shaped corrugated fin is projected from the air upstream end of the flat tube.

According to such a structure, there is an advantage that the frost formation inside the core can be suppressed by forming the frost on the tip protruding portion of the corrugated fin. Further, since the louver is not cut on the tip protruding portion of the corrugated fin, there is an advantage that the heat transfer coefficient on the air side of that portion is reduced, and thereby frosting itself at the tip protruding portion of the corrugated fin can be suppressed.

[0005]

However, in the above publication, the corrugated fin is divided into the air upstream side portion and the air downstream side portion of the flat tube, and the corrugated fins in the air upstream side portion are entirely distributed. Since it is a flat plate without louvers, when the outdoor heat exchanger is used as a condenser in the summer, the heat transfer coefficient on the air side of the entire corrugated fins on the air upstream side is significantly reduced, and the condensation performance is reduced. There is a problem.

Further, since the corrugated fins are divided into two parts, that is, the air upstream side part and the air downstream side part of the flat tube, the fin pitch is easily deviated between the two divided corrugated fins during assembly. . When the fin pitch of the corrugated fins divided into two parts is displaced, the shape resistance of the fins is increased and the ventilation resistance is increased, which further promotes performance deterioration.

The present invention has been made in view of the above points,
An object of the present invention is to provide an outdoor heat exchanger for a heat pump, which can effectively suppress deterioration of evaporator performance due to frost formation in winter without causing deterioration of condensation performance in summer.

[0008]

In order to achieve the above object, the present invention employs the following technical means. According to the first aspect of the invention, the corrugated fins (5) formed in a wavy shape are arranged and joined between the flat tube (4) through which the refrigerant flows and the flat surfaces of the flat tube (4). The corrugated fin (5) is provided with a protruding portion (5a) further protruding toward the air upstream side from the air upstream side end of the flat tube (4). ), The projecting portion (5a) has a flat plate shape without a louver, while the louver (5b) is formed in a portion facing the flat tube (4). It has a feature.

According to a second aspect of the present invention, in the outdoor heat exchanger for a heat pump according to the first aspect, the amount of protrusion of the protruding portion (5a) toward the upstream air side is 2 to 8 mm. . According to a third aspect of the present invention, the heat pump outdoor heat exchanger according to the first or second aspect has a first header tank (6) and a second header tank (7), A plurality of flat tubes (4) are arranged in parallel between the first header tank (6) and the second header tank (7).

According to a fourth aspect of the invention, in the heat pump outdoor heat exchanger according to the first or second aspect, the flat tube (4) is formed from a flat tube (4) bent in a meandering shape. In addition, the corrugated fins (5) are arranged and joined between the flat surfaces of the flat tube (4). According to a fifth aspect of the invention, in the heat pump outdoor heat exchanger according to any one of the first to fourth aspects,
The corrugated fins (5) are formed in a single continuous corrugated plate shape from the upstream side of the flat tube (4) to the downstream side of the air.

According to a sixth aspect of the invention, in the heat pump outdoor heat exchanger according to any one of the first to fifth aspects, the flat tube (4) of the protruding portion (5a) is provided. In the area close to the air upstream side end,
Slit-shaped narrow holes (5d) extending in the direction perpendicular to the air flow
Is formed. The reference numerals in parentheses of the above means indicate the corresponding relationship with the specific means described in the embodiments described later.

[0012]

According to the inventions of claims 1 to 6,
Due to having the above technical means, the outdoor heat exchanger (1)
When it acts as an evaporator in winter, the protruding portion (5a) of the corrugated fin (5) is a flat plate that does not form a louver, so the fin efficiency is reduced and the heat transfer coefficient on the air side is also reduced. Becomes higher and approaches the air temperature.

As a result, it is possible to prevent a large amount of frost from being concentrated on the tip of the protruding portion (5a) of the corrugated fin (5). At the same time, since the protruding portion (5a) of the corrugated fin (5) has the predetermined length L, frost is gradually generated from the tip of the protruding portion (5a) toward the air downstream side. Frost inside the core gradually occurs. Therefore, the phenomenon that the air flow path of the corrugated fin (5) is clogged rapidly due to frost can be reliably prevented, and the frost resistance of the outdoor heat exchanger (1) can be improved, so that the heating capacity of the heat pump in winter is improved. it can.

When the outdoor heat exchanger (1) acts as a condenser during summer cooling, the corrugated fins (5) are provided over the entire portion facing the flat tubes (4).
Since the louver (5b) is formed on the louver (5b)
Condenser performance can be satisfactorily exhibited due to the tip edge effect of. In addition to the above function and effect, in the invention according to claim 4,
Since the corrugated fins (5) are formed in one continuous corrugated plate shape from the air upstream side to the air downstream side of the flat tube (4), the corrugated fins are divided into two as in the prior art. There is no problem such as an increase in fin shape resistance due to the deviation of the fin pitch between
Therefore, both improvement of frost resistance and securing of heat exchanger performance can be achieved more favorably.

Further, in the invention according to claim 6, a slit extending in a direction perpendicular to the air flow is provided in a portion of the protruding portion (5a) close to the air upstream end (4b) of the flat tube (4). Since it has a small hole (5d),
The small holes (5d) exert a heat conduction blocking effect, and it becomes difficult for the low temperature of the louver (5b) portion of the corrugated fin (5) to be conducted to the protruding portion (5a). Therefore, frost formation on the tip of the protruding portion (5a) can be suppressed even more effectively.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) In FIGS. 1 and 2, reference numeral 1 is an outdoor heat exchanger for a heat pump according to the present invention, which is applied to an air conditioner for an electric vehicle. Reference numeral 2 is a side plate provided at the upper and lower ends for attaching the heat exchanger 1 to the vehicle body. Reference numeral 3 is a core portion for exchanging heat between the refrigerant and the blown air, and is composed of a flat tube 4 and corrugated fins 5.

Here, the flat tube 4 is a multi-hole tube having a flat cross-sectional shape as shown in FIG. 2 and having a large number of holes 4a formed in parallel, and is manufactured by extruding aluminum. The corrugated fin 5 is formed by corrugating an aluminum clad material in which a brazing material is clad on both front and back surfaces. The corrugated fin 5 extends from the air upstream side of the flat tube 4 to the air downstream side of the flat tube 4.
As shown in FIG. 2, the corrugated fins 5 formed in a continuous corrugated plate shape further project in the air flow direction A from the air upstream end 4b of the flat tube 4 to the air upstream side. The protruding portion 5a is integrally formed.

In the corrugated fin 5, the protruding portion 5a is formed in a flat plate shape without forming a louver, while the louver 5b is formed in a portion facing the length of the flat tube 4 in the air flow direction. . The louver 5b is a large number of rectangular strips formed by cutting and raising from the surface of the corrugated fins 5, and the louver 5b is arranged so that the cutting and raising direction of the louver 5b is reversed with the intermediate portion 5c in the air flow direction A as a boundary. Has been formed.

Reference numeral 6 is a first header tank, and one end (the left end in the drawing) of the flat tube 4 is communicatively supported. The second header tank 7 is the other end of the flat tube 4 (right end in the figure).
Are supported for communication. First and second header tanks 6, 7
Are header plates 6a, 7a, tank plates 6b, 7b, and upper and lower caps 6c, 6d, 7c, 7d, respectively.
Are joined together to form a substantially cylindrical shape.

Further, in the first and second header tanks 6 and 7, partition plates 6e and 7e each having a substantially disk shape are incorporated, and the internal space thereof is two chambers 6f, 6g and 7e.
It is divided into f and 7g. A refrigerant inlet / outlet pipe 6h is provided in the first header tank 6 so as to communicate with the upper chamber 6f, and a refrigerant inlet / outlet pipe 6h is provided in the second header tank 7 so as to communicate with the lower chamber 7g. A pipe 7h is provided.

In the outdoor heat exchanger 1 described above, the side plates 2 and the flat tubes 4 are made of an aluminum bare material which is not clad with a brazing material, and the other members are all made of an aluminum material clad with a brazing material. After being temporarily assembled in the state shown in FIG. 1, the parts are joined by brazing in a furnace. Next, the operation of this embodiment with the above configuration will be described. When the outdoor heat exchanger 1 is used as a condenser of a refrigeration cycle during summer cooling, as shown by the arrow B in FIG. 1, the inlet / outlet pipe 7h → the lower chamber 7g of the second header tank 7 → the lower flat plate Tube 4 → lower chamber 6 of first header tank 6
g → middle flat tube 4 → second header tank 7 upper chamber 7f → upper flat tube 4 → first header tank 6 upper chamber 6f → inlet / outlet pipe 6h The refrigerant is indicated by an arrow A by a blower (not shown).
The air blown in the direction is heat-exchanged through the corrugated fins 5 to be cooled and condensed.

When the outdoor heat exchanger 1 is used as an evaporator in a refrigeration cycle during heating in winter, the flow of the refrigerant reverses, and as shown by the arrow a in FIG.
-> Upper chamber 6f of the first header tank 6-> upper flat tube 4-> upper chamber 7f of the second header tank 7-> middle flat tube 4-> lower chamber 6g of the first header tank 6 → Lower flat tube 4 → Lower chamber 7g of second header tank 7 → Refrigerant flows in the route of inlet / outlet pipe 7h,
During this time, the refrigerant exchanges heat with the air blown in the direction of arrow A by a blower (not shown) through the corrugated fins 5 to absorb heat and evaporate.

By the way, when the outdoor heat exchanger 1 acts as an evaporator of the refrigeration cycle during heating in winter, the cycle may be operated at a low temperature such that the outside air temperature drops to 0 ° C. or less. Corrugated fin 5
Is formed on the surface of the outdoor heat exchanger 1 due to the formation of frost on the surface of the corrugated fins 5, which narrows the air flow path of the louver 5b.
There may occur a phenomenon that the performance of is significantly reduced.

Therefore, in this embodiment, as shown in FIG. 2, the corrugated fin 5 is provided with a protruding portion 5a which further protrudes in the air flow direction A from the air upstream side end 4b of the flat tube 4 to the air upstream side. In the corrugated fin 5, the protruding portion 5a is formed in a flat plate shape without forming a louver, while the louver 5b is formed in a portion facing the length of the flat tube 4 in the air flow direction.

Here, the louver 5b serves to form a large number of highly efficient leading edge portions on the surface of the corrugated fins 5 to enhance fin efficiency and improve air side heat transfer coefficient. Since the portion 5a has a flat plate shape without a louver, the fin efficiency is reduced, the heat transfer coefficient on the air side is also reduced, and the temperature rises, approaching the air temperature.

As a result, it is possible to prevent a large amount of frost from being concentrated on the tip of the protruding portion 5a of the corrugated fin 5. At the same time, since the protruding portion 5a of the corrugated fin 5 has the predetermined length L, frost is gradually generated from the tip of the protruding portion 5a toward the air downstream side, so that the frost formation inside the core is increased. Frost also gradually occurs. Therefore, the phenomenon that the inlet of the air flow path of the corrugated fins 5 is clogged rapidly due to frost formation can be reliably prevented, and the frost resistance of the outdoor heat exchanger 1 can be improved, so that the heating capacity of the heat pump in winter can be improved. .

When the outdoor heat exchanger 1 acts as a condenser during summer cooling, since the louver 5 is formed on the corrugated fin 5 over the entire portion facing the flat tube 4, the edge effect of the louver 5b is formed. The condenser performance can be exhibited satisfactorily. According to the study by the present inventor, the protruding length L (see FIG. 2) of the protruding portion 5a of the corrugated fin 5 is preferably about 3 mm from the viewpoint of frost resistance. The range of the protrusion length L is 2 in consideration of practically frost resistance, space restrictions, and the like.
It is preferable to set it to about 8 mm. (Second Embodiment) As shown in FIG. 3, corrugated fins 5
A slit-shaped thin hole 5d extending in the direction perpendicular to the air flow is formed in a portion of the protruding portion 5a of the flat tube 4 close to the air upstream end 4b, and the louver of the corrugated fin 5 is formed by the thin hole 5d. The low temperature of 5b is the protruding portion
It is difficult to conduct to a. In order to effectively exhibit the heat conduction blocking effect by the fine holes 5d, it is preferable that the width of the fine holes 5d is set to at least 0.1 mm or more.

(Third Embodiment) FIG. 4 shows a third embodiment in which the present invention is applied to an outdoor heat exchanger 1 using a meandering flat tube 40.
This is an embodiment, and the tube 40 is composed of one multi-hole flat tube bent and formed in a meandering shape, and the corrugated fins 5 are arranged and joined between the flat surfaces of the multi-hole flat tube 40. There is. Reference numerals 60 and 70 denote inlet and outlet pipes for letting the refrigerant into and out of the flat tube 40.

Also in this third embodiment, the flat tube 40 is attached to the corrugated fin 5 in the air flow direction A.
Of the corrugated fin 5, the protruding portion 5a of the corrugated fin 5 has a flat plate shape without a louver, while the protruding portion 5a of the flat tube 4 is formed. By forming the louver 5b in the portion facing the length in the air flow direction,
The same effect as that of the first embodiment can be exhibited.

[Brief description of drawings]

FIG. 1 is a front view showing a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is an enlarged sectional view of an essential part showing a second embodiment of the present invention.

FIG. 4 is a perspective view showing a third embodiment of the present invention.

[Explanation of symbols]

 4 Flat tube 4b Air upstream side end 5 Corrugated fin 5a Projection part 5b Louver 5d Small hole

Claims (6)

[Claims] 1. A flat tube through which a refrigerant flows, and a corrugated fin formed in a corrugated shape, which is disposed and joined between flat surfaces of the flat tube, and the corrugated fin has the above-mentioned structure. The flat tube is provided with a projecting portion further projecting toward the air upstream side from the air upstream side end, and the corrugated fin has the projecting portion in the form of a flat plate without forming a louver, while facing the flat tube. An outdoor heat exchanger for a heat pump, which is characterized in that a louver is formed in a portion to be formed. 2. The outdoor heat exchanger for a heat pump according to claim 1, wherein the protruding amount of the protruding portion toward the air upstream side is 2 to 8 mm. 3. A first header tank and a second header tank, wherein a plurality of the flat tubes are arranged in parallel between the first header tank and the second header tank. The outdoor heat exchanger for a heat pump according to claim 1 or 2, wherein the outdoor heat exchanger is a heat pump. 4. The flat tube is formed of a flat tube bent in a meandering shape, and the corrugated fins are arranged and joined between flat surfaces of the flat tube. The outdoor heat exchanger for a heat pump according to claim 1 or 2. 5. The corrugated fins are formed in the shape of a single continuous corrugated plate from the upstream side of the flat tube to the downstream side of the air in the flat tube. The outdoor heat exchanger for a heat pump according to any one of claims. 6. A slit-shaped narrow hole extending in a direction perpendicular to the air flow is formed in a portion of the protruding portion near the air upstream end of the flat tube. The heat exchanger outdoor heat exchanger according to any one of claims 1 to 5.