INDOOR HEAT EXCHANGER, INDOOR UNIT, AIR CONDITIONER, AND METHOD FOR MANUFACTURING INDOOR HEAT EXCHANGER

An indoor heat exchanger includes a heat exchanger body and a connection pipe connected to the heat exchanger body through a connection portion. The connection pipe includes a first curved portion having an elongation greater than or equal to 30%.

BACKGROUND

Technical Field

The present disclosure relates to an indoor heat exchanger, an indoor unit, an air conditioner, and a method for manufacturing an indoor heat exchanger.

Discussion of the Background

Examples of a known indoor heat exchanger include an indoor heat exchanger in which a connection pipe formed of copper has one end connected to a heat exchanger body and the other end connected to a flare nut (see, for example, JP 2013-155892 A).

SUMMARY

In a first aspect, an indoor heat exchanger of the present disclosure includes:a heat exchanger body; anda connection pipe connected to the heat exchanger body through a connection portion,in whichthe connection pipe includes a first curved portion with an elongation of 30% or greater.

Here, the elongation is measured in accordance with JIS Z2201 and Z2241 and is a ratio, expressed in percentage, between elongation occurring between gauge marks on a test specimen before the test specimen breaks and a gauge length in a tensile test.

In a second aspect, a method for manufacturing an indoor heat exchanger is a method for manufacturing an indoor heat exchanger including a heat exchanger body and a connection pipe connected to the heat exchanger body through a connection portion, the method including:bending the connection pipe to form a first curved portion in the connection pipe; andperforming annealing treatment on the first curved portion after bending the connection pipe to make the first curved portion larger in elongation than before the annealing treatment.

DESCRIPTION OF THE EMBODIMENTS

An indoor unit including an indoor heat exchanger and an air conditioner of the present disclosure will be described in detail below with reference to embodiments illustrated in the drawings. Note that the same parts in the drawings are denoted by the same reference numerals to avoid the description from being redundant. Upper, lower, left, and right in the description correspond to upper, lower, left, and right in a state where an indoor unit is installed in a room.

FIRST EXAMPLE

FIG.1is a diagram illustrating a refrigerant circuit RC provided in an air conditioner of a first example of the present disclosure. The air conditioner of the first example includes the indoor unit1and an outdoor unit2connected to the indoor unit1via the refrigerant circuit RC. The air conditioner is of a type in which the outdoor unit2is paired one-to-one with the indoor unit1.

The refrigerant circuit RC includes a compressor11, a four-way switching valve12, an outdoor heat exchanger13, an electric expansion valve14, an indoor heat exchanger15, and an accumulator16. As the compressor11is driven, a refrigerant (for example, an HFC refrigerant such as R410A or R32) circulates in the refrigerant circuit RC.

More specifically, the four-way switching valve12has one end connected to a discharge side of the compressor11. The four-way switching valve12has the other end connected to one end of the outdoor heat exchanger13. The outdoor heat exchanger13has the other end connected to one end of the electric expansion valve14. The electric expansion valve14has the other end connected to one end of the indoor heat exchanger15via a shutoff valve V1and a connection pipe L1. The indoor heat exchanger15has the other end connected to one end of the accumulator16via a connection pipe L2, a shutoff valve V2, and the four-way switching valve12. The accumulator16has the other end connected to an intake-side portion of the compressor11.

The indoor unit1is equipped with the indoor heat exchanger15and an indoor fan18. The indoor fan18is, for example, a cross-flow fan, and takes in indoor air through the indoor heat exchanger15.

The outdoor unit2is equipped with the compressor11, the four-way switching valve12, the outdoor heat exchanger13, the electric expansion valve14, the accumulator16, and an outdoor fan17.

The air conditioner switches the four-way switching valve12to a switching position indicated by a solid line to activate the compressor11for cooling operation and dehumidifying operation, and switches the four-way switching valve12to a switching position indicated by a dotted line to activate the compressor11for heating operation. A direction of a solid arrow inFIG.1indicates a direction in which the refrigerant flows during the cooling operation and the dehumidifying operation. A direction indicated by a dotted arrow inFIG.1indicates a direction in which the refrigerant flows during the heating operation.

FIG.2is a perspective view of the indoor unit1as viewed obliquely from above.FIG.3is a front view of the indoor unit1.

As illustrated inFIGS.2and3, the indoor unit1includes a casing21, and the indoor heat exchanger15(illustrated inFIG.1), the indoor fan18(illustrated inFIG.1), and the like are accommodated in the casing21.

An upper portion of the casing21is provided with an intake port22through which indoor air is taken in. When the indoor fan18is driven, indoor air enters the casing21through the intake port22and flows toward the indoor fan18(cross-flow fan). At this time, in order to prevent dust and the like from entering the casing21together with indoor air, a filter (not illustrated) is attached to the intake port22.

A lower portion of the casing21is provided with a blow-out port23through which air from the indoor fan18(indoor air subjected to heat exchange with the indoor heat exchanger15) blows out. A horizontal flap24is rotatably attached to a peripheral edge portion of the blow-out port23.

When the cooling operation or the like is started, the horizontal flap24changes its position from a stop position to close the blow-out port23to an operation position to open the blow-out port23to adjust a vertical airflow direction of air blown out from the blow-out port23.

FIG.4is a front view of the indoor heat exchanger15.

The indoor heat exchanger15includes a heat exchanger body20, the heat exchanger body20including a heat exchange portion201and a plurality of heat transfer tubes202extending through the heat exchange portion201in a left-right direction. The heat exchange portion201and the heat transfer tubes202are each formed of aluminum or an aluminum alloy.

The indoor heat exchanger15further includes a liquid-refrigerant connection pipe31and a gas-refrigerant connection pipe32. The liquid-refrigerant connection pipe31and the gas-refrigerant connection pipe32are fluidly connected to the heat transfer tubes202of the heat exchanger body20. The liquid-refrigerant connection pipe31is an example of a connection pipe, and constitutes a part of the connection pipe L1(illustrated inFIG.1). The gas-refrigerant connection pipe32is an example of the connection pipe, and constitutes a part of the connection pipe L2(illustrated inFIG.1). The liquid-refrigerant connection pipe31guides a liquid refrigerant from the electric expansion valve14to the heat exchanger body20during the cooling operation and the dehumidifying operation. On the other hand, the gas-refrigerant connection pipe32guides a gas refrigerant from the heat exchanger body20to the compressor11during the cooling operation and the dehumidifying operation.

Configuration of Liquid-Refrigerant Connection Pipe31

The liquid-refrigerant connection pipe31has includes a first liquid-refrigerant pipe311formed of aluminum or an aluminum alloy, and a second liquid-refrigerant pipe312formed of copper or a copper alloy. The first liquid-refrigerant pipe311has one end fluidly connected to a flow divider33.

The second liquid-refrigerant pipe312has one end fluidly connected to the other end of the first liquid-refrigerant pipe311through a third liquid-refrigerant pipe313formed of stainless steel. On the other hand, the second liquid-refrigerant pipe312has the other end fixed to a liquid-refrigerant flare union41by brazing.

The third liquid-refrigerant pipe313has one end and the other end that is larger in outer diameter than the one end. The third liquid-refrigerant pipe313has the one end connected to the first liquid-refrigerant pipe311. On the other hand, the third liquid-refrigerant pipe313has the other end connected to the second liquid-refrigerant pipe312.

Configuration of Gas-Refrigerant Connection Pipe32

The gas-refrigerant connection pipe32is similar in configuration to the liquid-refrigerant connection pipe31, and includes a first gas-refrigerant pipe321formed of aluminum or an aluminum alloy, and a second gas-refrigerant pipe322formed of copper or a copper alloy.

The first gas-refrigerant pipe321has one end fluidly connected to a flow divider (not illustrated).

The second gas-refrigerant pipe322has one end fluidly connected to the other end of the first gas-refrigerant pipe321through a third gas-refrigerant pipe323formed of stainless steel. On the other hand, the second gas-refrigerant pipe322has the other end fixed to a gas-refrigerant flare union42by brazing.

FIG.5is a front view of a main portion of the indoor heat exchanger15.FIG.6is a top view of the main portion of the indoor heat exchanger15.FIG.7is a left-side view of the main portion of the indoor heat exchanger15.

Configuration of First Liquid-Refrigerant Pipe311Adjacent to Second Liquid-Refrigerant Pipe312

As illustrated inFIGS.5to7, the first liquid-refrigerant pipe311of the liquid-refrigerant connection pipe31includes a first section311aextending along a vertical direction or a direction inclined relative to the vertical direction. The first liquid-refrigerant pipe311includes a second section311bcloser to the second liquid-refrigerant pipe312than the first section311a. The second section311bis continuous with a lower end (end adjacent to the second liquid-refrigerant pipe312) of the first section311a, and is bent from the lower end toward the second liquid-refrigerant pipe312. The second section311bis an example of a first curved portion.

The first liquid-refrigerant pipe311includes a third section311ccloser to the second liquid-refrigerant pipe312than the second section311b. The third section311cis continuous with an end of the second section311badjacent to the second liquid-refrigerant pipe312, and extends in a horizontal direction or a direction inclined relative to the horizontal direction.

The first liquid-refrigerant pipe311has an outer peripheral surface extending from an end of the third section311cadjacent to the second liquid-refrigerant pipe312to an end of the second section311badjacent to the first section311a, the outer peripheral surface entirely covered with a waterproof tube51. The waterproof tube51further covers an outer peripheral surface of the end of the third liquid-refrigerant pipe313adjacent to the first liquid-refrigerant pipe311. The waterproof tube51is formed of a tube made of a waterproof material (for example, vinyl chloride, silicone rubber, fluorine-baed based polymer, or the like) and shrunk by heating.

Configuration of First Liquid-Refrigerant Pipe311Adjacent to Heat Exchanger Body20

The first liquid-refrigerant pipe311includes a fourth section311dcloser to the heat exchanger body20than the first section311a. The fourth section311dis continuous with an upper end (heat-exchanger-body20-side end) of the first section311a, and the fourth section311dextends upward from the end and then extends downward like a U-turn. The fourth section311dis an example of a second curved portion.

The first liquid-refrigerant pipe311includes a fifth section311ecloser to the heat exchanger body20than the fourth section311d. The fifth section311eis continuous with a lower end (heat-exchanger-body20-side end) of the fourth section311d, and is bent from the lower end toward the flow divider33. The flow divider33is an example of a connection portion.

The first liquid-refrigerant pipe311includes a sixth section311fcloser to the heat exchanger body20than the fifth section311e. The sixth section311fextends from a heat-exchanger-body20-side end of the fifth section311eto the flow divider33.

The flow divider33is formed of aluminum or an aluminum alloy. A branch pipe34formed of aluminum or an aluminum alloy is fixed to an end of the flow divider33adjacent to the heat exchanger body20by brazing.

In the first example, the gas-refrigerant connection pipe32is similar in configuration to the liquid-refrigerant connection pipe31.

In the indoor heat exchanger15configured as described above, the elongation of the second section311b(first curved portion) of the liquid-refrigerant connection pipe31connected to the heat exchanger body20through the flow divider33(connection portion) is made greater than or equal to 30%, and the elongation of the first curved portion of the gas-refrigerant connection pipe32is made greater than or equal to 30%. This allows the liquid-refrigerant connection pipe31and the gas-refrigerant connection pipe32to easily bend during installation of the indoor unit accommodating the heat exchanger body20, thereby increasing work efficiency during installation.

Since the liquid-refrigerant connection pipe31includes the fourth section311d(second curved portion) between the flow divider33and the second section311b, when bending stress acts on the second section311b, the bending stress is partially received by the fourth section311d, so that it is possible to prevent stress concentration on the second section311band reduce the risk of breakage of the second section311b(the same applies to the gas-refrigerant connection pipe32).

It is possible to reduce, by making the elongation of the fourth section311dof the liquid-refrigerant connection pipe31less than or equal to 20%, a stress load applied to the heat exchanger body20when bending stress acts on the second section311b(first curved portion) (the same applies to the gas-refrigerant connection pipe32).

The indoor heat exchanger15is provided with the liquid-refrigerant connection pipe31and the gas-refrigerant connection pipe32. The liquid-refrigerant connection pipe31and the gas-refrigerant connection pipe32includes portions formed of aluminum or aluminum alloy that are lower in tensile strength than portions formed of copper, but is particularly effective in increasing work efficiency.

Alternatively, the elongation of the second section311bof the liquid-refrigerant connection pipe31may be greater than or equal to 40% (the same applies to the gas-refrigerant connection pipe32). This allows the liquid-refrigerant connection pipe31and the gas-refrigerant connection pipe32to easily bend during installation of the indoor unit accommodating the heat exchanger body20, thereby allowing a further increase in work efficiency during installation.

The liquid-refrigerant connection pipe31and the gas-refrigerant connection pipe32each have an outer diameter as small as 9.52 mm (≈⅜ inches) or less, thereby making the work of bending the liquid-refrigerant connection pipe31and the gas-refrigerant connection pipe32easier.

The indoor unit1including the indoor heat exchanger15and the air conditioner including the indoor unit1allow the liquid-refrigerant connection pipe31and the gas-refrigerant connection pipe32to easily bend during installation of the indoor unit1, thereby increasing work efficiency during installation.

Method for Manufacturing Indoor Heat Exchanger15

FIG.8is a flowchart for describing a method for manufacturing the indoor heat exchanger15.

As illustrated inFIG.8, a bending step S1, an assembling step S2, and an annealing step S3are included.

Specifically, the first liquid-refrigerant pipe311is bent into a predetermined shape to have the second section311b(first curved portion) and the fourth section311d(second curved portion) (bending step S1).

Next, the first liquid-refrigerant pipe311thus bent, the second liquid-refrigerant pipe312, the third liquid-refrigerant pipe313, and the liquid-refrigerant flare union41are assembled into the liquid-refrigerant connection pipe31, and the liquid-refrigerant connection pipe31, the flow divider33(connection portion), and the branch pipe34are assembled into a connection pipe assembly (assembling step S2).

Then, the portions of the connection pipe assembly are brazed together and subjected to annealing treatment by in-furnace brazing (annealing step S3).

As described above, an end (side remote from the flow divider33) of the branch pipe34of the connection pipe assembly subjected to the annealing treatment is brazed to the heat exchanger body20.

The gas-refrigerant connection pipe32is also subjected to the bending step S1, the assembling step S2, and the annealing step S3in a similar manner to complete the indoor heat exchanger15.

According to the method for manufacturing the indoor heat exchanger15, in the bending step S1, the second section311b(first curved portion) of the first liquid-refrigerant connection pipe311and the first curved portion of the first gas-refrigerant connection pipe321are reduced in elongation by half due to work hardening (the same applies to the gas-refrigerant connection pipe32). The annealing treatment in the annealing step S3after the bending step S1makes the second section311bof the first liquid-refrigerant connection pipe311connected to the heat exchanger body20through the flow divider33and the first curved portion of the first gas-refrigerant connection pipe321larger in elongation than before the annealing step, the annealing treatment allowing the liquid-refrigerant connection pipe31and the gas-refrigerant connection pipe32to easily bend during installation of the indoor unit1accommodating the heat exchanger body20, thereby increasing work efficiency during installation.

In the annealing step S3, performing the annealing treatment by in-furnace brazing allows each portion to be subjected to the brazing and the annealing treatment at the same time, and it is therefore possible to efficiently perform the brazing and the annealing treatment.

In the air conditioner of the first example, one indoor unit1is connected to one outdoor unit2, or alternatively, a plurality of indoor units1may be connected. In other words, the above-described air conditioner is of a pair-type, or alternatively, the air conditioner may be of a multi-type.

The first liquid-refrigerant pipe311and the first gas-refrigerant pipe321are formed of aluminum or an aluminum alloy in the first example, or alternatively, may be formed of metal other than aluminum and an aluminum alloy.

The second liquid-refrigerant pipe312and the second gas-refrigerant pipe322are formed of copper or a copper alloy in the first example, or alternatively, may be formed of metal other than copper or a copper alloy.

The flow divider33and the branch pipe34are interposed between the heat transfer tubes202of the heat exchanger body20and the one end of the first liquid-refrigerant pipe311in the liquid-refrigerant connection pipe31in the first example, or alternatively, the one end of the first liquid-refrigerant pipe311may be directly connected to the heat transfer tubes202of the heat exchanger body20with neither the flow divider33nor the branch pipe34interposed (the same applies to the gas-refrigerant connection pipe32).

The flow divider33that divides one refrigerant flow into two refrigerant flows is used in the first example, or alternatively, a flow divider that divides one refrigerant flow into three or more refrigerant flows may be used.

SECOND EXAMPLE

FIG.9is a front view of a liquid-refrigerant connection pipe31of an indoor heat exchanger1015of a second example of the present disclosure and a peripheral portion of the liquid-refrigerant connection pipe31. The indoor heat exchanger1015of the second example is similar in configuration to the indoor heat exchanger15of the first example except that a tubular member61covering the waterproof tube51is provided.

The tubular member61illustrated inFIG.9is formed of a heat insulating material (for example, foamed polyester). The tubular member61covers the first liquid-refrigerant pipe311from the upper end of the first section311ato a tip of the liquid refrigerant union41.

Although not illustrated, most of the gas-refrigerant connection pipe32is inserted into the tubular member61in a manner similar to the liquid-refrigerant connection pipe31. Therefore, the tubular member61has an inner diameter set larger than a sum of an outer diameter of the liquid-refrigerant connection pipe31and an outer diameter of the gas-refrigerant connection pipe32.

In the indoor heat exchanger1015configured as described above, since the tubular member61covers the waterproof tube51, liquid such as dew condensation water is prevented from adhering to the covering member or the waterproof tube51.

Covering the second section311bof the first liquid-refrigerant connection pipe311with the tubular member61allows a reduction in bending stress applied to the second section311b(the same applies to the gas-refrigerant connection pipe32).

REFERENCE SIGNS LIST