air conditioner

Abstract

The air conditioner 1 comprises an indoor heat exchanger 9, an outdoor heat exchanger 7, refrigerant piping 4 connecting the indoor heat exchanger 9 and the outdoor heat exchanger 7, a pressure reducing device 8 provided in the refrigerant piping 4, a first strainer 11 provided in the refrigerant piping 4 connecting the outdoor heat exchanger 7 and the pressure reducing device 8, and a second strainer 12 provided in the refrigerant piping 4 connecting the pressure reducing device 8 and the indoor heat exchanger 9, wherein the flow path cross-sectional area S1 of the first strainer 11 is larger than the flow path cross-sectional area S2 of the second strainer 12.

Description

Technical Field

[0001] The present disclosure relates to an air conditioner.

Background Art

[0002] In an air conditioner having a plurality of indoor units, when refrigerant is temporarily circulated through a stopped indoor unit, the opening degree of a pressure reducing device connected to the stopped indoor unit is adjusted. However, by adjusting the opening degree of the pressure reducing device, noise of the pressure reducing device due to the passage of the refrigerant may occur, and the quietness may be reduced.

[0003] Patent Document 1 discloses an air conditioner having a pressure reducing device connected to a heat source side heat exchanger and including a relay unit connected to a part of a plurality of indoor units. This relay unit includes a flow path switching valve provided in a refrigerant pipe connecting a compressor and a load side heat exchanger, and a bypass pipe connecting a refrigerant pipe connecting the pressure reducing device and the heat source side heat exchanger and the flow path switching valve.

[0004] Thereby, when the indoor unit is stopped, the internal flow path of the flow path switching valve can be switched so that refrigerant does not flow into the indoor unit, and the refrigerant can be diverted to the bypass pipe, suppressing noise of the pressure reducing device due to the passage of the refrigerant.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the above-mentioned air conditioner is equipped with strainers both downstream and upstream of the pressure reducing device. When heating is performed under certain environmental conditions (for example, when the outside air temperature is low), there is a risk that a choke phenomenon may occur in the strainer located downstream of the pressure reducing device, where the refrigerant flow velocity is limited by the speed of sound, obstructing the flow of the refrigerant.

[0007] The purpose of this disclosure is to provide an air conditioner capable of suppressing the occurrence of choke phenomena in the strainer located downstream of the pressure reducing device during heating operation. [Means for solving the problem]

[0008] The air conditioner disclosed herein is Indoor heat exchanger, Outdoor heat exchanger, Refrigerant piping connecting the indoor heat exchanger and the outdoor heat exchanger, A pressure reducing device provided in the refrigerant piping, A first strainer is provided in the refrigerant piping connecting the outdoor heat exchanger and the pressure reducing device, The system includes a second strainer provided in the refrigerant piping connecting the pressure reducing device and the indoor heat exchanger, The cross-sectional area of ​​the flow path of the first strainer is larger than the cross-sectional area of ​​the flow path of the second strainer.

[0009] The air conditioner disclosed herein is Indoor heat exchanger, Outdoor heat exchanger, Refrigerant piping connecting the indoor heat exchanger and the outdoor heat exchanger, A pressure reducing device provided in the refrigerant piping, The system includes a strainer provided in the refrigerant piping connecting the outdoor heat exchanger and the pressure reducing device, The flow path cross-sectional area of ​​the strainer is 0.8 times or more the flow path cross-sectional area of ​​the refrigerant piping connected to the strainer on the side of the pressure reducing device. [Brief explanation of the drawing]

[0010] [Figure 1]Schematic diagram showing the configuration of an air conditioner according to one embodiment. [Figure 2] Cross-sectional view showing the strainer [Modes for carrying out the invention]

[0011] One embodiment of the air conditioner of this disclosure will be described with reference to Figures 1 and 2. Note that the dimensional ratios in the drawings do not necessarily match the actual dimensional ratios. Furthermore, the dimensional ratios between the drawings do not necessarily match. Figure 1 is a schematic diagram showing the configuration of an air conditioner according to one embodiment. In Figure 1, solid arrows indicate the flow of refrigerant during heating operation, and dashed arrows indicate the flow of refrigerant during cooling operation.

[0012] As shown in Figure 1, the air conditioner 1 is, for example, a packaged air conditioner or a multi-split air conditioner for buildings. The air conditioner 1 comprises an outdoor unit 2, an indoor unit 3, and refrigerant piping 4 connecting them. The refrigerant piping 4 includes liquid refrigerant piping 4a and gaseous refrigerant piping 4b that connect the outdoor unit 2 and the indoor unit 3. A refrigerant with a relatively low GWP (Global Warming Potential) (for example, R290) is used as the refrigerant flowing through the refrigerant piping 4.

[0013] The outdoor unit 2 (air conditioner 1) comprises a compressor 5, a four-way valve 6, an outdoor heat exchanger 7, a pressure reducing device 8, and a control unit (not shown), which are connected via refrigerant piping 4. The indoor unit 3 (air conditioner 1) comprises an indoor heat exchanger 9.

[0014] The compressor 5 compresses the inhaled low-pressure refrigerant and discharges it as high-pressure refrigerant. For example, a variable-capacity compressor such as a rotary compressor or a scroll compressor can be used as the compressor 5. The four-way valve 6 can switch the direction of refrigerant flow to either the outdoor heat exchanger 7 side or the indoor heat exchanger 9 side.

[0015] The outdoor heat exchanger 7 is a heat exchanger that exchanges heat between the refrigerant and the outdoor air. The outdoor heat exchanger 7 functions as a condenser during the cooling operation and as an evaporator during the heating operation. As the outdoor heat exchanger 7, for example, an air-cooled heat exchanger such as a fin-and-tube heat exchanger or a plate-fin heat exchanger, or a water-cooled heat exchanger such as a shell-and-tube heat exchanger or a plate heat exchanger is used.

[0016] The decompression device 8 is a device that expands and decompresses the refrigerant, and is provided in the refrigerant pipes 4c and 4f on the liquid refrigerant pipe 4a side. The decompression device 8 is composed of an expansion valve 81 and a capillary tube 82. As the expansion valve 81, for example, an electronic expansion valve, a temperature automatic expansion valve, a constant pressure automatic expansion valve, etc. are used.

[0017] The capillary tube 82 is an elongated copper tube (capillary tube) for decompressing the refrigerant. The capillary tube 82 is provided on the side of the outdoor heat exchanger 7 rather than the expansion valve 81, and is connected in series with the expansion valve 81. Note that the decompression device 8 may be configured not to include the capillary tube 82.

[0018] The indoor heat exchanger 9 is a heat exchanger that exchanges heat between the refrigerant and the indoor air. The outdoor heat exchanger 7 functions as an evaporator during the cooling operation and as a condenser during the heating operation. As the indoor heat exchanger 9, for example, an air-cooled heat exchanger such as a fin-and-tube heat exchanger or a plate-fin heat exchanger is used.

[0019] The operation during the heating operation will be described. The control unit switches the four-way valve 6 to the solid line side in FIG. 1 during the heating operation.

[0020] The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 5 flows into the indoor heat exchanger 9 through the four-way valve 6 and the gaseous refrigerant piping 4b. The incoming gaseous refrigerant liquefies in the indoor heat exchanger 9 by releasing heat into the indoor air. The liquefied liquid refrigerant flows into the outdoor heat exchanger 7 through the liquid refrigerant piping 4a and the pressure reducing device 8. In the pressure reducing device 8, the liquid refrigerant is depressurized to become a gaseous-liquid mixture. The gaseous-liquid mixture that flows into the outdoor heat exchanger 7 exchanges heat with the outdoor air, absorbs heat, gasifies, and is returned to the compressor 5. Heating operation is performed by the circulation of the refrigerant through the refrigerant piping 4 in this manner.

[0021] The operation during cooling operation will now be explained. The control unit switches the four-way valve 6 to the dashed line side in Figure 1 during cooling operation.

[0022] The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 5 flows through the four-way valve 6 into the outdoor heat exchanger 7. The incoming gaseous refrigerant exchanges heat with the outdoor air in the outdoor heat exchanger 7, liquefying as it releases heat. The liquefied liquid refrigerant is then depressurized by the pressure reducing device 8 to become a gas-liquid mixture, which flows through the liquid refrigerant piping 4a into the indoor heat exchanger 9. The incoming refrigerant gases in the indoor heat exchanger 9 by absorbing heat from the indoor air. The gaseous gaseous refrigerant is returned to the compressor 5 through the gaseous refrigerant piping 4b. Cooling operation is performed by the circulation of the refrigerant through the refrigerant piping 4 in this manner.

[0023] The outdoor unit 2 (air conditioner 1) is equipped with a first strainer 11 (also simply called "strainer 11") located in the refrigerant pipes 4c and 4d connecting the outdoor heat exchanger 7 and the pressure reducing device 8, and a second strainer 12 located in the refrigerant pipes 4e and 4f connecting the pressure reducing device 8 and the indoor heat exchanger 9. Each of the strainers 11 and 12 is a filter that filters out dust and impurities contained in the refrigerant, such as sludge, generated during the operation of the compressor 5.

[0024] Figure 2 is a cross-sectional view of the first strainer 11. The first strainer 11 will be described below with reference to Figure 2. The second strainer 12 has the same configuration as the first strainer 11, so its description will be omitted.

[0025] As shown in Figures 1 and 2, the first strainer 11 comprises a cylindrical housing 111 having an enlarged portion whose interior is larger than that of the refrigerant piping 4, and an annular member 112 and a first filter 113 provided within the enlarged portion of the housing 111.

[0026] The first filter 113 is joined to the annular member 112 on the upstream side of the housing 111 during heating operation. The first filter 113 is formed with a U-shaped (concave) cross-section, with the side joined to the annular member 112 being open and the opposite side being closed. During heating operation, the first filter 113 is open on the upstream side and closed on the downstream side. The first filter 113 is also formed in a mesh shape with multiple wires intersecting. The dimension of the space between adjacent wires becomes the opening of the mesh of the first filter 113. The second filter of the second strainer 12 is arranged so that the downstream side is open and the upstream side is closed during heating operation. The first filter 113 and the second filter are each arranged so that the side facing the pressure reducing device 8 is open. Note that the arrangement directions of the first filter 113 and the second filter are not limited to those described above. For example, the first filter 113 and the second filter may be arranged in the same direction, or they may be arranged in different directions.

[0027] During heating operation (operation with low refrigerant pressure), liquid refrigerant flows into the second strainer 12, and then the liquid refrigerant is depressurized by the pressure reducing device 8, and the gas-liquid mixed refrigerant flows into the first strainer 11. It is known that the speed of sound decreases in the case of a gas-liquid mixed refrigerant compared to liquid refrigerant. In particular, the speed of sound decreases sharply when the void fraction is between 0 and 0.2. Therefore, if the cross-sectional areas of the flow paths of the first strainer 11 and the second strainer 12 are the same, the speed of sound in the first strainer 11 will be slower than the speed of sound in the second strainer 12. As a result, during heating operation, a choking phenomenon may occur in the first strainer 11, where the flow velocity of the refrigerant is limited by the speed of sound and the flow of refrigerant is obstructed. In particular, during heating operation when the outside air temperature is low, the refrigerant pressure becomes even lower, and the likelihood of choking occurring in the first strainer 11 increases. If choking occurs, the amount of refrigerant discharged from the compressor 5 decreases, and there is a risk that the pressure reducing device 8 may become clogged with, for example, refrigerant oil.

[0028] Furthermore, when the refrigerant circulation flow rate is high during heating operation, the flow velocity of the refrigerant passing through the first strainer 11 increases, and if the flow path cross-sectional area of ​​the first strainer 11 is smaller than the flow path cross-sectional area of ​​the refrigerant piping 4c, the refrigerant flow velocity may locally reach the speed of sound. Therefore, during heating operation, a choke phenomenon may occur in the first strainer 11. In particular, when the outside air temperature is low during heating operation, the likelihood of a choke phenomenon occurring in the first strainer 11 increases.

[0029] It is preferable that the flow path cross-sectional area of ​​the first strainer 11 is larger than the flow path cross-sectional area of ​​the second strainer 12. With this configuration, the flow velocity of the refrigerant flowing through the first strainer 11 can be reduced during heating operation. This suppresses the occurrence of choking in the first strainer 11. Furthermore, by increasing the flow path cross-sectional area of ​​only the first strainer 11, it is possible to suppress reductions in cycle space, cost increases due to increased material usage, and weight increases compared to when the flow path cross-sectional areas of each strainer 11 and 12 are increased individually.

[0030] Flow path cross-sectional area S1 (mm²) of the first strainer 11 2 ) is the cross-sectional area A (mm²) of the aperture 113a of the first filter 113. 2 The flow path cross-sectional area S2 (mm²) of the second strainer 12 is calculated using the following formula (Equation 1) based on the space ratio R (%) of the first filter 113. 2 The following formula (Equation 1) is also used to calculate the following. S1(mm 2 )=A×R / 100 (Equation 1)

[0031] Cross-sectional area A of opening 113a (mm²) 2 ) is calculated using the following formula (Equation 2) based on the inner diameter a (mm) of the opening 113a. A(mm 2 ) = (a / 2) 2 ×π (Formula 2)

[0032] The void ratio R (%) is calculated using the following formula (Equation 3) based on the wire diameter d (mm) and mesh opening B (mm) of the first filter 113. R(%) = {B / (B+d)} 2 ×100 (Formula 3)

[0033] The mesh opening B (mm) is calculated using the following formula (Equation 4) based on the mesh count M1 (mesh / inch) (number of meshes in a 1-inch (25.4 mm) square) and the wire diameter d (mm). The mesh count M1 is set appropriately according to the size of the expansion valve 81. The same applies to the mesh count M2 of the second filter of the second strainer 12. B=25.4 / M1-d (Formula 4)

[0034] Preferably, the flow path cross-sectional area S1 of the first strainer 11 is 110% or more of the flow path cross-sectional area S2 of the second strainer 12. This suppresses the occurrence of choking in the first strainer 11. Preferably, the flow path cross-sectional area S1 is 150% or less of the flow path cross-sectional area S2. This suppresses the reduction of cycle space, the increase in cost and weight due to increased material usage, etc. that occur when the flow path cross-sectional area S1 of the first strainer 11 is enlarged.

[0035] The flow path cross-sectional area S1 of the first strainer 11 is preferably 0.8 times or more the flow path cross-sectional area S3 of the refrigerant piping 4c connected to the first strainer 11 on the pressure reducing device 8 side. With this configuration, it is possible to suppress the increase in the flow velocity of the refrigerant passing through the first strainer 11 during heating operation. This suppresses the occurrence of choking in the first strainer 11. The flow path cross-sectional area S3 is calculated using the inner diameter d1 of the refrigerant piping 4c in the above (Equation 2).

[0036] It is more preferable that the flow path cross-sectional area S1 of the first strainer 11 is greater than or equal to the flow path cross-sectional area S3 of the refrigerant piping 4c connected to the first strainer 11 on the pressure reducing device 8 side. With such a configuration, it is possible to further suppress the increase in the flow velocity of the refrigerant passing through the first strainer 11 during heating operation. This further suppresses the occurrence of choking in the first strainer 11.

[0037] The flow path cross-sectional area S1 of the first strainer 11 is preferably 0.8 times or more the flow path cross-sectional area S4 of the refrigerant piping 4d connected to the first strainer 11 on the outdoor heat exchanger 7 side, and more preferably it is equal to or greater than the flow path cross-sectional area S4. The flow path cross-sectional area S4 is calculated using the above (Equation 2) based on the inner diameter d2 of the refrigerant piping 4d.

[0038] The flow path cross-sectional area S2 of the second strainer 12 is preferably 0.8 times or more the flow path cross-sectional area S5 of the refrigerant piping 4e connected to the second strainer 12 on the indoor heat exchanger 9 side, and more preferably S5 or more. The flow path cross-sectional area S2 is preferably 0.8 times or more the flow path cross-sectional area S6 of the refrigerant piping 4f connected to the second strainer 12 on the pressure reducing device 8 side, and more preferably S6 or more.

[0039] In this embodiment, the respective flow path cross-sectional areas S3 and S4 (each inner diameter) of the refrigerant pipes 4c and 4d connected to the first strainer 11 are the same, and the respective flow path cross-sectional areas S5 and S6 (each inner diameter) of the refrigerant pipes 4e and 4f connected to the second strainer 12 are the same. The respective flow path cross-sectional areas S3 and S4 of the refrigerant pipes 4c and 4d are the same as the respective flow path cross-sectional areas S5 and S6 of the refrigerant pipes 4e and 4f, respectively. Note that the respective flow path cross-sectional areas S3 to S6 may be different.

[0040] (modified version) (A) In the above embodiment, the outdoor unit 2 (air conditioner 1) is equipped with a second strainer 12, but is not limited to this. For example, the outdoor unit 2 (air conditioner 1) may be configured not to be equipped with a second strainer 12. Alternatively, for example, the indoor unit 3 may be equipped with a second strainer 12.

[0041] (B) In the above embodiment, the outdoor unit 2 (air conditioner 1) is equipped with two strainers 11 and 12, but is not limited to this. For example, the outdoor unit 2 (air conditioner 1) may be equipped with three or more strainers.

[0042] (C) In the above embodiment, the flow path cross-sectional area S1 of the first strainer 11 is larger than the flow path cross-sectional area S2 of the second strainer 12, but is not limited to this. For example, the flow path cross-sectional area S1 may be the same as the flow path cross-sectional area S2, or smaller than the flow path cross-sectional area S2.

[0043] (D) In ​​the above embodiment, the flow path cross-sectional area S1 of the first strainer 11 is 0.8 times or more the flow path cross-sectional area S3 of the refrigerant piping 4c, but is not limited thereto. The flow path cross-sectional area S1 may be less than 0.8 times the flow path cross-sectional area S3. The same applies to the flow path cross-sectional area S2 of the second strainer 12.

[0044] (E) The mesh count M1 of the first filter 113 in the first strainer 11 may be smaller than the mesh count M2 of the second filter in the second strainer 12. With this configuration, the rate of flow of refrigerant passing through the first strainer 11 during heating operation can be further suppressed. This further suppresses the occurrence of choke phenomenon in the first strainer 11. Note that the mesh count M1 may be the same as the mesh count M2, or it may be larger than the mesh count M2.

[0045] [1] As described above, the air conditioner 1 preferably comprises an indoor heat exchanger 9, an outdoor heat exchanger 7, refrigerant piping 4 connecting the indoor heat exchanger 9 and the outdoor heat exchanger 7, a pressure reducing device 8 provided in the refrigerant piping 4, a first strainer 11 provided in refrigerant piping 4c, 4d connecting the outdoor heat exchanger 7 and the pressure reducing device 8, and a second strainer 12 provided in refrigerant piping 4e, 4f connecting the pressure reducing device 8 and the indoor heat exchanger 9, wherein the flow path cross-sectional area S1 of the first strainer 11 is larger than the flow path cross-sectional area S2 of the second strainer 12.

[0046] With this configuration, by making the flow path cross-sectional area S1 of the first strainer 11 larger than the flow path cross-sectional area S2 of the second strainer 12, the flow velocity of the refrigerant flowing through the first strainer 11 can be reduced during heating operation. This suppresses the occurrence of choking in the first strainer 11.

[0047] [2] Furthermore, it is preferable that the air conditioner 1 comprises an indoor heat exchanger 9, an outdoor heat exchanger 7, refrigerant piping 4 connecting the indoor heat exchanger 9 and the outdoor heat exchanger 7, a pressure reducing device 8 provided in the refrigerant piping 4, and a first strainer 11 provided in the refrigerant piping 4c, 4d connecting the outdoor heat exchanger 7 and the pressure reducing device 8, wherein the flow path cross-sectional area S1 of the first strainer 11 is 0.8 times or more the flow path cross-sectional area S3 of the refrigerant piping 4c connected to the first strainer 11 on the pressure reducing device 8 side.

[0048] With this configuration, by making the flow path cross-sectional area S1 of the first strainer 11 at least 0.8 times the flow path cross-sectional area S3 of the refrigerant piping 4c, it is possible to suppress the increase in the flow velocity of the refrigerant passing through the first strainer 11 during heating operation. This makes it possible to suppress the occurrence of choking in the first strainer 11.

[0049] [3] Furthermore, in the air conditioner 1 described in [1] or [2] above, it is preferable that the flow path cross-sectional area S1 of the first strainer 11 is greater than or equal to the flow path cross-sectional area S3 of the refrigerant piping 4c connected to the first strainer 11 on the pressure reducing device 8 side.

[0050] With this configuration, it is possible to further suppress the increase in the flow velocity of the refrigerant passing through the first strainer 11 during heating operation. This further suppresses the occurrence of choking in the first strainer 11.

[0051] [4] Furthermore, in the air conditioner 1 described in any one of [1] to [3] above, it is preferable that the number of meshes M1 of the first filter 113 of the first strainer 11 is smaller than the number of meshes M2 of the second filter of the second strainer 12.

[0052] With this configuration, it is possible to further suppress the increase in the flow velocity of the refrigerant passing through the first strainer 11 during heating operation. This further suppresses the occurrence of choking in the first strainer 11.

[0053] [5] Furthermore, in the air conditioner 1 described in any one of [1] to [4] above, it is preferable that the refrigerant flowing through the refrigerant piping 4 is R290.

[0054] The air conditioner 1 is not limited to the configuration and methods of the embodiments described above, nor is it limited to the effects and benefits described above. Furthermore, the air conditioner 1 can be modified in various ways without departing from the gist of this disclosure. For example, one or more of the configurations and methods related to the modifications described above may be arbitrarily selected and adopted in the configurations and methods of the embodiments. [Explanation of symbols]

[0055] 1...Air conditioner, 2...Outdoor unit, 3...Indoor unit, 4...Refrigerant piping, 4a...Liquid refrigerant piping, 4b...Gas refrigerant piping, 4c~4f...Refrigerant piping, 5...Compressor, 6...Four-way valve, 7...Outdoor heat exchanger, 8...Pressure reducing device, 81...Expansion valve, 82...Capillary tube, 9...Indoor heat exchanger, 11...First strainer, 111...Housing, 112...Annular member, 113...First filter, 113a...Opening, 12...Second strainer

Claims

1. Indoor heat exchanger, Outdoor heat exchanger, Refrigerant piping connecting the indoor heat exchanger and the outdoor heat exchanger, A pressure reducing device provided in the refrigerant piping, The refrigerant piping connecting the outdoor heat exchanger and the pressure reducing device includes a first strainer having a first filter, The flow path cross-sectional area of ​​the first strainer in the portion where the first filter is located is 0.8 times or more the flow path cross-sectional area of ​​the refrigerant piping connected to the first strainer on the side of the pressure reducing device. The cross-sectional area of ​​the flow path of the first strainer in the portion where the first filter is located is calculated by the following formula (Equation 1) in an air conditioner. S1 (mm) ２ ) = A (mm ２ )×R(%) / 100 (Formula 1) S1: Flow path cross-sectional area of ​​the first strainer A: Cross-sectional area of ​​the opening of the first filter R: Space ratio of the first filter

2. The air conditioner according to claim 1, wherein the flow path cross-sectional area of ​​the first strainer in the portion where the first filter is located is greater than or equal to the flow path cross-sectional area of ​​the refrigerant piping connected to the first strainer on the side of the pressure reducing device.

3. The system includes a second strainer provided in the refrigerant piping connecting the pressure reducing device and the indoor heat exchanger, The air conditioner according to claim 1, wherein the mesh count of the first filter is smaller than the mesh count of the second filter of the second strainer.

4. The air conditioner according to any one of claims 1 to 3, wherein the refrigerant flowing through the refrigerant piping is R290.

Images