Heat Exchanger

Abstract

A heat exchanger that performs heat exchange between a refrigerant and outside air includes: a plurality of tubes arranged in parallel; a fin provided between the tubes adjacent to each other. The fin includes: contact portions alternately in contact with one and the other of the adjacent tubes; wall portions each connecting the contact portions adjacent to each other so as to connect the adjacent tubes; an extension portion extending from the contact portions and the wall portions and protruding upstream in a flow direction of the outside air from the tubes; and a plurality of louvers provided on each of the wall portions continuously along the flow direction of the outside air. A downstream end portion of a most upstream louver in the flow direction of the outside air is located upstream of a tip end of each of the tubes in the flow direction of the outside air.

Description

TECHNICAL FIELD

The present invention relates to a heat exchanger.

BACKGROUND ART

JP5563162B discloses an outdoor heat exchanger of a vehicle air conditioner, the outdoor heat exchanger includes a plurality of flat tubes and corrugated fins provided between adjacent flat tubes, a plate portion of each of the corrugated fins includes a plurality of louvers, and the plate portion includes an extension portion expanding upwind from a joint region with the flat tube.

SUMMARY OF INVENTION

However, in the outdoor heat exchanger in JP5563162B, when the vehicle air conditioner performs heating operation, water vapor contained in outside air is cooled, and frost may be formed on the extension portion. When the frost is formed on the extension portion, the outside air does not directly contact the flat tube, and thus heat exchange performance of the outdoor heat exchanger decreases.

An object of the invention is to suppress a decrease in heat exchange performance of a heat exchanger.

According to an aspect of the present invention, a heat exchanger that performs heat exchange between a refrigerant circulating in a refrigeration cycle and outside air, the heat exchanger includes, a plurality of tubes arranged in parallel and configured to allow the refrigerant to flow therethrough, a fin provided between the tubes adjacent to each other and configured to allow the outside air to pass therethrough, the fin includes, a plurality of contact portions alternately in contact with one and the other of the adjacent tubes, a plurality of wall portions each connecting the contact portions adjacent to each other so as to connect the adjacent tubes, an extension portion extending from the contact portions and the wall portions and protruding upstream in a flow direction of the outside air from the tubes, and a plurality of louvers provided in each of the wall portions continuously along the flow direction of the outside air, each of the wall portions includes a flat plate portion formed in a flat plate shape, and arc portions each curved in an arc shape from the flat plate portion toward a corresponding one of the contact portions, the louvers include a first louver formed most upstream in the flow direction of the outside air in the extension portion, and a second louver formed downstream of the first louver in the flow direction of the outside air on a downstream side of an upstream end portion in the flow direction of the outside air in the tubes, the first louver and the second louver are formed at the same height throughout a height direction of the flat plate portion, and a downstream end portion of the first louver is located upstream of a tip end of each of the tubes in the flow direction of the outside air, and is formed at the same cut-and-raised height over a height direction of the downstream end portion.

In the above aspect, the fin includes the extension portion protruding upstream in the flow direction of outside air from the tube, and a plurality of louvers provided in each of the wall portions continuously along the flow direction of the outside air. Accordingly, when heating operation is performed while a temperature of the outside air is low, water vapor contained in the outside air is cooled, and frost may be formed on a most upstream first louver in the flow direction of the outside air. However, since the frost is formed intensively on the most upstream first louver, the frost is less likely to be formed on a downstream second louver. In addition, since the downstream end portion of the most upstream first louver is located upstream of the tip end of the tube in the flow direction of the outside air, even if the frost is formed on the first louver, a gap remains between the first louver and the tube. Therefore, the outside air entering through the gap passes through the tube, and heat exchange can be performed between the refrigerant and the outside air. Therefore, the decrease in the heat exchange performance of the heat exchanger can be suppressed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front view of a heat exchanger according to an embodiment of the invention.

FIG. 2 is an enlarged front view illustrating tubes and a fin.

FIG. 3 is a perspective view illustrating the tubes and the fin.

FIG. 4 is a cross-sectional view taken along a line IV-IV in FIG. 2.

FIG. 5 is a cross-sectional view taken along a line V-V in FIG. 2.

FIG. 6 is a diagram illustrating an action of the heat exchanger.

FIG. 7 is a diagram illustrating an action of the heat exchanger.

FIG. 8 is a schematic diagram illustrating formation of frost on a fin according to a comparative example.

FIG. 9 is a schematic diagram illustrating the formation of frost on the fin.

FIG. 10 is a cross-sectional view illustrating a modification of the fin.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a heat exchanger 100 according to an embodiment of the invention will be described with reference to the drawings.

First, an overall configuration of the heat exchanger 100 will be described with reference to FIG. 1. FIG. 1 is a front view of the heat exchanger 100.

The heat exchanger 100 is mounted on a vehicle (not illustrated). The heat exchanger 100 is an outdoor heat exchanger in a refrigeration cycle of an air conditioner (not illustrated). The heat exchanger 100 performs heat exchange between a refrigerant circulating in the refrigeration cycle and outside air. The heat exchanger 100 functions as a condenser when the air conditioner performs cooling operation, and functions as an evaporator when the air conditioner performs heating operation.

The heat exchanger 100 includes a plurality of tubes 1, a pair of tanks 2a and 2b, and a plurality of fins 3. The tubes 1, the tanks 2a and 2b, and the fins 3 are made of metal such as aluminum, and are joined integrally to each other by brazing or the like.

The tubes 1 are arranged in parallel and laminated at intervals. A flow path through which the refrigerant flows is formed in each tube 1. The tube 1 is disposed such that a heat exchange surface 11 in contact with the fin 3 is horizontal.

The tank 2a and the tank 2b are arranged so as to be respectively connected to both end portions of the tube 1 in a longitudinal direction. The tank 2a and the tank 2b are arranged so as to be connected to the plurality of tubes 1 from the longitudinal direction. The tank 2a and the tank 2b temporarily store the refrigerant.

The refrigerant circulating in the refrigeration cycle and used for air conditioning flows into the tank 2a. The refrigerant flowing into the tank 2a flows through the plurality of tubes 1. The refrigerant performs heat exchange with the outside air when flowing through the tubes 1.

The refrigerant flowing through the tubes 1 flows into the tank 2b. The refrigerant flowing into the tank 2b circulates in the refrigeration cycle again and is used for air conditioning.

The fins 3 are each provided between adjacent tubes 1, and are alternately laminated with the tubes 1. The fin 3 is formed in a wave shape along the longitudinal direction of the tube 1, and is joined to two tubes 1 adjacent thereto. The outside air introduced by traveling of the vehicle and an outdoor fan (not illustrated) passes around the plurality of tubes 1 and the fins 3. Therefore, the refrigerant flowing inside the tube 1 can perform the heat exchange with the outside air via a surface of the tube 1 and the fin 3. In this way, the fin 3 promotes the heat exchange between the refrigerant and the outside air.

The plurality of tubes 1 and the fins 3 of the heat exchanger 100 function as a core 9 that performs the heat exchange between the refrigerant flowing in the tubes 1 and the outside air passing around the tubes 1.

Next, the fin 3 will be described in detail with reference to FIGS. 2 to 5. FIG. 2 is an enlarged front view illustrating the tubes 1 and the fin 3. FIG. 3 is a perspective view illustrating the tubes 1 and the fin 3. FIG. 4 is a cross-sectional view taken along a line IV-IV in FIG. 2. FIG. 5 is a cross-sectional view taken along a line V-V in FIG. 2.

As illustrated in FIGS. 2 and 3, each fin 3 includes contact portions 31, wall portions 32, an extension portion 35, and louvers 36. The contact portions 31 and the wall portions 32 are connected in a wave shape.

As illustrated in FIG. 2, a plurality of contact portions 31 are provided and are alternately in contact with one and the other of the adjacent tubes 1. Each contact portion 31 is formed in a flat plate shape. The contact portion 31 is joined to the heat exchange surface 11 of the tube 1 by brazing or the like.

A plurality of wall portions 32 are provided, and connect adjacent contact portions 31 so as to connect the adjacent tubes 1. Each wall portion 32 includes a flat plate portion 33 and arc portions 34.

Each flat plate portion 33 is formed in a flat plate shape. The flat plate portions 33 are arranged obliquely in opposite directions so as to be staggered. The louvers 36 are formed in the flat plate portion 33.

Each arc portion 34 is curved in an arc shape from the flat plate portion 33 toward the contact portion 31. By providing the arc portions 34, the flat plate portion 33 and the contact portion 31 are connected by a smooth curved surface.

As illustrated in FIG. 3, the extension portion 35 protrudes upstream in a flow direction of the outside air from the tube 1 by extending the contact portions 31 and the wall portions 32.

As illustrated in FIG. 4, a length LP [mm] of a plane portion 35a in which the louver 36 is not provided in the extension portion 35 is shorter than a length LL [mm] of a louver forming portion 35b in which the louver 36 is provided in the extension portion 35. This is because if the length of the plane portion 35a in the extension portion 35 is larger, heat exchange performance may be deteriorated.

As illustrated in FIGS. 4 and 5, a plurality of louvers 36 are provided in the flat plate portion 33 continuously along the flow direction of the outside air. A downstream end portion 36b of a most upstream louver 36 in the flow direction of the outside air is a linear cut and raised end portion located upstream of a tip end 12 of the tube 1 in the flow direction of the outside air. That is, the entire most upstream louver 36 (first louver) in the flow direction of the outside air is located upstream of the tip end 12 of the tube 1 in the flow direction of the outside air. In FIG. 3, triangular portions located above and below the downstream end portion 36b which is the linear cut and raised end portion of the louver 36, are just portions simply connecting the downstream end portion 36b of the louver 36 and the wall portion 32 of the fin 3. That is, in FIG. 3, the downstream end portion 36b is a linearly cut and raised downstream end portion of the louver 36, and does not include the triangular portion located above and below.

As illustrated in FIG. 5, the most upstream louver 36 in the flow direction of the outside air is a single-louver (single-side opening louver) 361 in which only the downstream end portion 36b is cut and raised in one side surface of the wall portion 32. Each of other louvers 36 (second louvers) provided continuously downstream of the single-louver 361 is a double-louver (double-side opening louver) 362 in which the downstream end portion 36b is cut and raised in the one side surface of the wall portion 32 and an upstream end portion 36a is cut and raised in the other side surface of the wall portion 32.

The louver 36 is not formed in the arc portion 34. The louver 36 is formed throughout an entire height direction of the flat plate portion 33 of the wall portion 32. Accordingly, since the louver 36 can be formed as large as a height H [mm] (see FIG. 2) over the entire flat plate portion 33, the outside air can be prevented from bypassing the louver 36 and flowing downstream. Therefore, frost can be prevented from being formed downstream in the flow direction of the outside air.

There is one downstream end portion 36b of the louver 36 located upstream of the tip end 12 of the tube 1 in each wall portion 32. That is, only one louver 36 protrudes upstream of the tip end 12 of the tube 1. Although two or more louvers 36 may protrude upstream of the tip end 12 of the tube 1, and since the frost is formed intensively on the most upstream louver 36, heavy frost is not formed on the second louver 36. Therefore, in the heat exchanger 100, by forming just one louver 36 that protrudes upstream of the tip end 12 of the tube 1, a decrease in the heat exchange performance is suppressed while suppressing an increase in the flow resistance of the outside air.

Next, actions of the heat exchanger 100 will be described with reference to FIGS. 6 to 9. FIG. 6 is a diagram illustrating the action of the heat exchanger 100 and illustrating a state before frost F is formed. FIG. 7 is a diagram illustrating the action of the heat exchanger 100 and illustrating a state after the frost F is formed. FIG. 8 is a schematic diagram illustrating formation of the frost F on a fin according to a comparative example. FIG. 9 is a schematic diagram illustrating the formation of the frost F on the fin 3.

As illustrated in FIG. 6, the fin 3 includes the extension portion 35 protruding upstream in the flow direction of the outside air from the tube 1, and the plurality of louvers 36 provided in the wall portion 32 continuously along the flow direction of the outside air. In a general state where the frost F is not formed in the heat exchanger 100, the outside air passes through the tubes 1. Therefore, the refrigerant flowing inside the tube 1 performs heat exchange with the outside air via the surface of the tube 1 and the fin 3.

As illustrated in FIG. 7, when the heating operation is performed while when a temperature of the outside air is low, water vapor contained in the outside air is cooled, and the frost F may be formed on the most upstream louver 36 in the flow direction of the outside air.

Specifically, in the comparative example illustrated in FIG. 8, there is no louver 36 protruding upstream of the tip end 12 of the tube 1. In this case, the frost F is formed intensively on the most upstream louver 36 may contact with the tip end 12 of the tube 1 to block a flow path of the outside air.

On the other hand, as illustrated in FIG. 9, in the heat exchanger 100, the downstream end portion 36b of the most upstream louver 36 is located upstream of the tip end 12 of the tube 1 in the flow direction of the outside air. Therefore, since the frost F is formed intensively on the most upstream louver 36, the frost F is less likely to be formed downstream. Even if the frost F is formed intensively on the most upstream louver 36, a gap remains between the most upstream louver 36 and the tip end 12 of the tube 1. Therefore, the outside air entering through the gap passes through the tube 1, and thus the heat exchange can be performed between the refrigerant and the outside air. Therefore, the decrease in the heat exchange performance of the heat exchanger 100 can be suppressed.

Thereafter, even if the frost F increases and blocks the gap with the tip end 12 of the tube 1, the heat exchange between the refrigerant and the outside air can be performed by the heat exchanger 100 until the gap is blocked. Therefore, a usable time of the heat exchanger 100 can be extended.

When the frost F increases and blocks and the gap with the tip end 12 of the tube 1, for example, defrosting operation (hot gas operation) of causing a high-temperature refrigerant compressed by a compressor (not illustrated) in the refrigeration cycle to flow through the tube 1 is performed. Accordingly, at a location downstream in the flow direction of the outside air where the frost F is relatively thin, when the defrosting operation is performed, the frost F immediately melts and becomes water.

At this time, the tube 1 is disposed such that the heat exchange surface 11 in contact with the fin 3 is horizontal. Since the frost F is porous, water adhering downstream in the flow direction of the outside air moves upstream in the flow direction of the outside air along the heat exchange surface 11, and is absorbed by the frost F formed on the most upstream louver 36 due to a capillary phenomenon. Thereafter, when the frost F formed on the extension portion 35 melts, the defrosting is completed. In this way, the downstream end portion 36b of the most upstream louver 36 is located upstream of the tip end 12 of the tube 1 in the flow direction of the outside air, and thus drainage during the defrosting operation can be facilitated.

According to the above embodiment, the following effects are achieved.

The heat exchanger 100 that performs the heat exchange between the refrigerant circulating in the refrigeration cycle and the outside air includes: the plurality of tubes 1 arranged in parallel and configured to allow the refrigerant to flow therethrough; the fin 3 provided between the tubes 1 adjacent to each other and configured to allow the outside air to pass therethrough. The fin 3 includes: the plurality of contact portions 31 alternately in contact with one and the other of the adjacent tubes 1; the plurality of wall portions 32 each connecting the contact portions 31 adjacent to each other so as to connect the adjacent tubes 1; the extension portion 35 extending from the contact portions 31 and the wall portions 32 and protruding upstream in the flow direction of the outside air from the tubes 1; and the plurality of louvers 36 provided in each of the wall portions 32 continuously along the flow direction of the outside air. Each of the wall portions 32 includes the flat plate portion 33 formed in a flat plate shape, and the arc portions 34 each curved in an arc shape from the flat plate portion 33 toward a corresponding one of the contact portions 31. The louvers 36 include the first louver formed most upstream in the flow direction of the outside air in the extension portion 35, and the second louver formed downstream of the first louver in the flow direction of the outside air on a downstream side of an upstream end portion in the flow direction of the outside air in the tubes 1. The first louver and the second louver are formed at the same height throughout the height direction of the flat plate portion 33. The downstream end portion 36b of the first louver is located upstream of the tip end of the tube 1 in the flow direction of the outside air, and is formed at the same cut-and-raised height in a height direction of the downstream end portion 36b.

In the configuration, the fin 3 includes the extension portion 35 protruding upstream in the flow direction of the outside air from the tube 1, and the plurality of louvers 36 provided in each of the wall portions 32 continuously along the flow direction of the outside air. Accordingly, when heating operation is performed while a temperature of the outside air is low, water vapor contained in the outside air is cooled, and the frost F may be formed on the most upstream first louver in the flow direction of the outside air. However, since the frost F is formed intensively on the most upstream first louver, the frost F is less likely to be formed on the downstream second louver. In addition, since the downstream end portion 36b of the most upstream first louver is located upstream of the tip end 12 of the tube 1 in the flow direction of the outside air, even if the frost F is formed on the first louver, a gap remains between the first louver and the tube 1. Therefore, the outside air entering through the gap passes through the tube 1, and the heat exchange can be performed between the refrigerant and the outside air. Therefore, the decrease in the heat exchange performance of the heat exchanger 100 can be suppressed.

Thereafter, even if the frost F increases and blocks the gap with the tip end 12 of the tube 1, the heat exchange between the refrigerant and the outside air can be performed by the heat exchanger 100 before the gap is blocked. Therefore, a usable time of the heat exchanger 100 can be extended.

Embodiments of the present invention were described above, but the above embodiments are merely examples of applications of this invention, and the technical scope of this invention is not limited to the specific constitutions of the above embodiments.

For example, in the above embodiment, the most upstream louver 36 in the flow direction of the outside air is the single-louver 361, and other louvers 36 disposed downstream of the single-louver 361 are the double-louvers 362. However, as illustrated in FIG. 10, the most upstream louver 36 in the flow direction of the outside air may be the double-louver 362 similarly to the other louvers 36. In this case, similarly to the above embodiment, the decrease in the heat exchange performance of the heat exchanger 100 can also be suppressed.

Claims

1. A heat exchanger configured to perform heat exchange between a refrigerant circulating in a refrigeration cycle and outside air, the heat exchanger comprising: a plurality of tubes arranged in parallel and configured to allow the refrigerant to flow therethrough;a fin provided between adjacent tubes and configured to allow the outside air to pass therethrough, wherein the fin includes a plurality of contact portions alternately in contact with one and another of the adjacent tubes,a plurality of wall portions each connecting the contact portions adjacent to each other so as to connect the adjacent tubes,an extension portion extending from the contact portions and the wall portions and protruding upstream in a flow direction of the outside air from the tubes, anda plurality of louvers provided in each of the wall portions continuously along the flow direction of the outside air,each of the wall portions includes a flat plate portion formed in a flat plate shape, and arc portions each curved in an arc shape from the flat plate portion toward a corresponding one of the contact portions,the louvers include a first louver formed most upstream in the flow direction of the outside air in the extension portion, and a second louver formed downstream of the first louver in the flow direction of the outside air on a downstream side of an upstream end portion in the flow direction of the outside air in the tubes,the first louver and the second louver are formed at a same height throughout a height direction of the flat plate portion, anda downstream end portion of the first louver is located upstream of a tip end of each of the tubes in the flow direction of the outside air, and is formed at a same cut-and-raised height over a height direction of the downstream end portion.

2. The heat exchanger according to claim 1, wherein the first louver is a single-louver in which only the downstream end portion is cut and raised in one side surface of athe wall portion, and the second louver is a double-louver in which the downstream end portion is cut and raised in the one side surface of the wall portion and an upstream end portion is cut and raised in another side surface of the wall portion.

3. The heat exchanger according to claim 1, wherein a length of a plane portion in which the first louver is not provided in the extension portion is shorter than a length of a louver forming portion in which the first louver is provided in the extension portion.

4. The heat exchanger according to claim 1, wherein a number of the downstream end portion of the first louver located upstream of the tip end of a tube at each of the wall portions is one.

5. The heat exchanger according to claim 1, wherein a tube is disposed such that a heat exchange surface thereof in contact with the fin is horizontal.

6. The heat exchanger according to claim 1, wherein a wall portion includes the arc portions each curved in an arc shape toward a corresponding one of the contact portions, and the louvers are not formed in the arc portions.