air conditioner

Abstract

To provide an air conditioner capable of improving safety when a combustible refrigerant is leaked.SOLUTION: An air conditioner includes: an outdoor unit 20 having a compressor 21, an outdoor heat exchanger 23, an outdoor fan 24 and an expansion mechanism 25; and an indoor unit having an indoor heat exchanger 11 and an indoor fan 12. A refrigeration cycle circuit is constituted by connecting the outdoor unit 20 and the indoor unit by using refrigerant piping. The refrigeration cycle circuit uses a combustible refrigerant, and performs control so as not to start the compressor 21 when driving rotational frequency of the indoor fan 12 is predetermined rotational frequency or lower.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses an air conditioner in which electrical components are arranged at the upper part of a casing so as to be positioned above a heat exchanger. Even if a flammable refrigerant leaks from the heat exchanger and accumulates in the lower part of the casing, the electrical components that can be ignition sources for the leaked refrigerant are located above the heat exchanger and are spaced upward from the leaked refrigerant, so that the intrusion of the leaked refrigerant toward the electrical component side and the ignition of the leaked refrigerant are reliably prevented, and the safety during the leakage of the flammable refrigerant is ensured.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides an air conditioner capable of improving safety during the leakage of a flammable refrigerant.

Means for Solving the Problems

[0005] The air conditioner according to the present disclosure includes an outdoor unit having a compressor, an outdoor heat exchanger, an outdoor fan, and an expansion mechanism, and an indoor unit having an indoor heat exchanger and an indoor fan, and connects the outdoor unit and the indoor unit with a refrigerant pipe to form a refrigeration cycle circuit. In the air conditioner, the refrigeration cycle circuit uses a flammable refrigerant. , outdoor control unit and When the driving rotational speed of the indoor fan is less than or equal to a predetermined rotational speed, the compressor is controlled not to start. , indoor control unit and The indoor control unit transmits the rotational speed of the indoor fan to the outdoor control unit, and the outdoor control unit, [Effects of the Invention]

[0006] The air conditioner in this disclosure is controlled so that the compressor does not start when the indoor fan's rotational speed is below a predetermined speed, and the compressor is started only when the indoor fan's rotational speed is higher than the predetermined speed. This ensures a sufficient airflow, and even if a flammable refrigerant leaks, it is possible to adequately agitate the air in the conditioned space and suppress the formation of a flammable region by the flammable refrigerant. [Brief explanation of the drawing]

[0007] [Figure 1] Configuration diagram showing the refrigeration cycle circuit of an air conditioner according to Embodiment 1 [Figure 2] Block diagram showing the control configuration of the air conditioner according to Embodiment 1 [Figure 3] Flowchart showing the operation of Embodiment 1 [Modes for carrying out the invention]

[0008] (Knowledge and other information that formed the basis of this disclosure) At the time the inventors conceived this disclosure, it had been proposed that air conditioners switch to using hydrocarbon refrigerants, such as isobutane or propane, which have a low global warming potential, from the perspective of mitigating climate change. However, the inventors discovered that conventional air conditioners have a problem in that when flammable refrigerants are used, it is necessary to ensure safety in the event of refrigerant leakage. To solve this problem, the subject matter of this disclosure was established. Therefore, this disclosure provides an air conditioner that can improve safety in the event of a flammable refrigerant leak.

[0009] The embodiments will be described in detail below with reference to the drawings. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. The attached drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0010] (Embodiment 1) [1-1. Structure] [1-1-1. Configuration of the Refrigeration Cycle Circuit] Embodiment 1 will be described below with reference to Figures 1 to 3. Figure 1 is a diagram showing the refrigeration cycle circuit of the air conditioner 1 according to Embodiment 1. As shown in Figure 1, the air conditioner 1 comprises an indoor unit 10 and an outdoor unit 20. The air conditioner 1 circulates a flammable refrigerant, such as isobutane or propane, in the refrigeration cycle circuit shown in Figure 1, and performs air conditioning such as heating or cooling in the conditioned space where the indoor unit 10 is installed. Although devices such as accumulators that are not used in the explanation are not shown in Figure 1, the air conditioner 1 may have such devices.

[0011] The indoor unit 10 includes an indoor heat exchanger 11 and an indoor fan 12. The indoor heat exchanger 11 is, for example, a fin-tube type heat exchanger and has a flow path through which a refrigerant passes.

[0012] The indoor fan 12 is a cross-flow fan that blows air by rotating an impeller with a motor (not shown), for example. The indoor fan 12 draws air from the conditioned space into the indoor unit 10 and exchanges heat between the refrigerant inside the indoor heat exchanger 11 and the drawn-in air. The air that has exchanged heat with the refrigerant flows out to the outside of the indoor unit 10 again, and the conditioned space is air-conditioned.

[0013] The outdoor unit 20 includes a compressor 21, a four-way valve 22, an outdoor heat exchanger 23, an outdoor fan 24, and an expansion mechanism 25. The compressor 21 is, for example, a hermetic compressor 21, which sucks and compresses a gas refrigerant and discharges it toward the four-way valve 22. The four-way valve 22 can switch the flow paths of the refrigerant flowing into the compressor 21 and the refrigerant discharged from the compressor 21.

[0014] The four-way valve 22 switches the operation in the indoor unit 10 between a cooling operation and a heating operation by switching the flow path of the refrigerant. For example, when the four-way valve 22 allows the refrigerant to flow in the direction of the arrow shown in FIG. 1, the indoor unit 10 executes a cooling operation. The outdoor heat exchanger 23 is, for example, a fin-tube type heat exchanger and includes a flow path through which the refrigerant passes inside. The flow path of the outdoor heat exchanger 23 is connected to the four-way valve 22 and the expansion mechanism 25. The outdoor fan 24 is, for example, an axial flow blower, which exchanges heat between the air outside the outdoor unit 20 and the refrigerant inside the outdoor heat exchanger 23. The expansion mechanism 25 is, for example, a capillary tube or an expansion valve, which reduces the pressure of the refrigerant flowing inside.

[0015] The indoor unit 10 and the outdoor unit 20 are connected by a gas-side connection pipe 30 that connects the gas side of the indoor unit and the gas side of the outdoor unit 20, and a liquid-side connection pipe 31 that connects the liquid side of the indoor unit and the liquid side of the outdoor unit 20. A liquid-side two-way valve 33 and a gas-side three-way valve 34 are respectively provided in the middle of the gas-side connection pipe 30 and the liquid-side connection pipe 31. The indoor unit 10 and the outdoor unit 20 are connected via these liquid-side two-way valve 33 and gas-side three-way valve 34. The liquid-side two-way valve 33 and the gas-side three-way valve 34 are manually opened when the connection work between the outdoor unit 20 and the indoor unit 10 is completed. Note that the liquid-side two-way valve 33 and the gas-side three-way valve 34 may be automatically opened and closed by control by the outdoor control unit 41 or the indoor control unit 40.

[0016] In addition, safety shut-off valves 32 are provided on the inlet side and the outlet side of the indoor heat exchanger 11. When refrigerant leaks from the indoor heat exchanger 11 by any chance, the safety shut-off valves 32 shut off the gas-side connection pipe 30 and the liquid-side connection pipe 31, preventing the refrigerant inside the gas-side connection pipe 30 and the liquid-side connection pipe 31 from being sent to the indoor heat exchanger 11. Note that the safety shut-off valve 32 may be provided outside the indoor unit 10, or may be provided on the outdoor unit 20 side from the liquid-side two-way valve 33 and the gas-side three-way valve 34.

[0017] [1-1-2. Control Configuration] Next, the control configuration of the present embodiment will be described. FIG. 2 is a block diagram showing the control configuration of the present embodiment. As shown in FIG. 2, the indoor unit 10 includes an indoor control unit 40. The outdoor unit 20 includes an outdoor control unit 41. The indoor control unit 40 and the outdoor control unit 41 are configured to be able to communicate with each other. The indoor control unit 40 includes, for example, a processor that executes programs such as a CPU or an MPU, and memories such as a ROM and a RAM. The processor reads out the control program stored in the memory and executes processes, and various processes are executed by the cooperation of hardware and software. The indoor control unit 40 controls the rotation of the indoor fan 12. In addition, the indoor control unit 40 performs opening and closing control of the safety shut-off valve 32.

[0018] The outdoor control unit 41 includes, for example, a processor that executes programs such as a CPU or an MPU, and memories such as a ROM and a RAM. The processor reads out the control program stored in the memory and executes processes, and various processes are executed by the cooperation of hardware and software. The outdoor control unit 41 controls the driving of the compressor 21 and the outdoor fan 24, and also performs switching control of the four-way valve 22.

[0019] The indoor control unit 40 transmits the rotational speed of the indoor fan 12 to the outdoor control unit 41. The outdoor control unit 41 controls the compressor 21 not to start if the rotational speed of the indoor fan 12 is below a predetermined rotational speed. This is because, if a flammable refrigerant leaks, and the rotational speed of the indoor fan 12 is below a predetermined speed, it will not be possible to secure sufficient airflow. As a result, the air in the conditioned space cannot be adequately mixed, and the flammable refrigerant may form a flammable area.

[0020] In this embodiment, the decision to start the compressor 21 is made based on the rotational speed of the indoor fan 12. However, the decision to start the compressor 21 may also be made based on the airflow from the indoor fan 12, for example. In this case, the airflow rate is calculated based on the following formula. In ETRS, the formula is as follows:

number

[0021] For non-ETRS systems, the formula is as follows:

number

[0022] If the airflow from the indoor fan 12 is less than or equal to the minimum airflow calculated by the above formula, the calculation result is transmitted to the outdoor control unit 41, which controls the compressor 21 not to start.

[0023] Furthermore, the indoor control unit 40 may control the compressor 21 not to drive and close the safety shut-off valve 32 when the rotational speed of the indoor fan 12 is below a predetermined rotational speed or when the airflow of the indoor fan 12 is below a predetermined airflow. By controlling it in this way, the amount of refrigerant on the indoor unit side can be reduced even when the indoor fan 12's rotational speed is low. Therefore, if refrigerant leaks, the amount of refrigerant flowing into the air-conditioned space can be reduced, and the flammable area in the air-conditioned space can be minimized.

[0024] Furthermore, the indoor control unit 40 may be controlled to keep the indoor fan 12 running at all times, even when the air conditioner is stopped. In this case, if a refrigerant leak occurs while the air conditioner is stopped, the flammable area caused by the refrigerant can be minimized by stirring the air in the conditioned space.

[0025] Furthermore, the air conditioner may be equipped with an auxiliary power source such as a battery (not shown). The auxiliary power supply, for example, is installed in the indoor unit and functions as a power source to drive the indoor fan 12 when the commercial power supply is interrupted, such as during a power outage. This allows the indoor fan 12 to be driven even during a power outage, so that if a refrigerant leak occurs, the flammable area caused by the refrigerant can be minimized by circulating the air in the conditioned space.

[0026] [1-3. Operation, action] The operation of the air conditioner 1, configured as described above, will now be explained. Figure 3 is a flowchart showing the operation of the air conditioner in Embodiment 1. As shown in Figure 3, when the power to the air conditioner is turned ON (ST1), the indoor control unit 40 controls the drive of the indoor fan 12. The indoor control unit 40 detects the rotational speed of the indoor fan 12 and determines whether this rotational speed is below a predetermined speed (ST2).

[0027] If the indoor control unit 40 determines that the indoor fan 12's rotational speed is below a predetermined speed (ST2:YES), it transmits the rotational speed information of the indoor fan 12 to the outdoor control unit 41. As a result, the outdoor control unit 41 controls the compressor 21 not to start (ST3). At this time, the indoor control unit 40 controls the safety shut-off valve 32 to close (ST4).

[0028] On the other hand, if it is determined that the rotational speed of the indoor fan 12 is higher than a predetermined rotational speed (ST2:NO), this rotational speed information is transmitted to the outdoor control unit 41, which then drives the compressor 21 and the outdoor fan 24 (ST5), and switches the four-way valve 22 to either cooling or heating operation. This will enable normal cooling or heating operation.

[0029] [1-4. Effects, etc.] As described above, in this embodiment, the system comprises an outdoor unit 20 having a compressor 21, an outdoor heat exchanger 23, an outdoor fan 24, and an expansion mechanism 25, and an indoor unit having an indoor heat exchanger 11 and an indoor fan 12. The outdoor unit 20 and the indoor unit are connected by refrigerant piping to form a refrigeration cycle circuit. The refrigeration cycle circuit uses a flammable refrigerant and controls the system so that the compressor 21 does not start when the rotational speed of the indoor fan 12 is below a predetermined rotational speed. As a result, the compressor 21 is activated only when the rotational speed of the indoor fan 12 is higher than a predetermined rotational speed, ensuring a sufficient airflow. Even if a flammable refrigerant leaks, the air in the conditioned space can be sufficiently agitated, suppressing the formation of a flammable region by the flammable refrigerant.

[0030] Furthermore, in this embodiment, the compressor 21 is controlled not to start if the airflow from the indoor fan 12 is below a predetermined airflow. As a result, the airflow rate and rotational speed of the indoor fan 12 are proportional, and if the airflow rate of the indoor fan 12 is greater than a predetermined airflow rate, a sufficient airflow rate can be secured. Even if a flammable refrigerant leaks, the air in the conditioned space can be sufficiently stirred, and the formation of a flammable region by the flammable refrigerant can be suppressed.

[0031] Furthermore, in this embodiment, a safety shut-off valve 32 is installed in the refrigeration cycle circuit, and the safety shut-off valve 32 is controlled to close when the rotational speed of the indoor fan 12 is below a predetermined rotational speed. This allows the amount of refrigerant in the indoor unit to be reduced even when the indoor fan 12 is driven at a low rotational speed. Therefore, in the event of a refrigerant leak, the amount of refrigerant released into the air-conditioned space can be reduced, and the flammable area in the air-conditioned space can be minimized.

[0032] Furthermore, in this embodiment, the indoor fan 12 is controlled to operate when the air conditioner is stopped. This allows for minimizing the flammable area caused by the refrigerant by circulating the air in the conditioned space if a refrigerant leak occurs while the air conditioner is stopped.

[0033] Furthermore, in this embodiment, an auxiliary power supply is provided to supply power to the indoor fan 12 when power is not supplied to the air conditioner. This allows the indoor fan 12 to be driven even during a power outage, so that if a refrigerant leak occurs, the flammable area caused by the refrigerant can be minimized by circulating the air in the conditioned space.

[0034] (Note) Based on the above description of embodiments, the following technologies are disclosed.

[0035] (Technology 1) An air conditioner comprising an outdoor unit having a compressor, an outdoor heat exchanger, an outdoor fan, and an expansion mechanism, and an indoor unit having an indoor heat exchanger and an indoor fan, wherein the outdoor unit and the indoor unit are connected by refrigerant piping to form a refrigeration cycle circuit, characterized in that the refrigeration cycle circuit uses a flammable refrigerant and controls the compressor so as not to start when the rotational speed of the indoor fan is below a predetermined rotational speed. This configuration ensures sufficient airflow because the compressor is only activated when the indoor fan's rotational speed is higher than a predetermined speed. This allows for adequate air circulation in the conditioned space even if a flammable refrigerant leaks, preventing the flammable refrigerant from forming a flammable region.

[0036] (Technical 2) The air conditioner according to Technical 1, characterized in that the compressor is controlled not to start when the airflow from the indoor fan is less than or equal to a predetermined airflow. With this configuration, the airflow rate and rotational speed of the indoor fan are proportional. If the airflow rate of the indoor fan is greater than a predetermined airflow rate, sufficient airflow can be secured. Even if a flammable refrigerant leaks, the air in the conditioned space can be sufficiently stirred, and the formation of a flammable region by the flammable refrigerant can be suppressed.

[0037] (Technology 3) An air conditioner according to Technology 1 or Technology 2, characterized in that a safety shut-off valve is installed in the refrigeration cycle circuit, and the safety shut-off valve is controlled to close when the rotational speed of the indoor fan is less than or equal to a predetermined rotational speed. This configuration allows for a reduced amount of refrigerant in the indoor unit, even when the indoor fan's rotational speed is low. Therefore, in the event of a refrigerant leak, the amount of refrigerant released into the conditioned space can be reduced, minimizing the flammable area within the conditioned space.

[0038] (Technical 4) An air conditioner according to any one of Technical 1 to 3, characterized in that it is controlled to drive the indoor fan when the air conditioner is stopped. This configuration allows for minimizing the flammable area caused by the refrigerant by agitating the air in the conditioned space in the event of a refrigerant leak while the air conditioner is stopped.

[0039] (Technical 5) An air conditioner according to any one of Technical 1 to Technical 4, characterized in that it is provided with an auxiliary power supply that supplies power to the indoor fan when power is not supplied to the air conditioner. This configuration allows the indoor fan to operate even during a power outage, and in the event of a refrigerant leak, the flammable area caused by the refrigerant can be minimized by circulating the air in the conditioned space. [Industrial applicability]

[0040] This disclosure is suitably applicable to air conditioners that can improve safety in the event of a flammable refrigerant leak. [Explanation of Symbols]

[0041] 1. Air conditioner 10 Indoor unit 11 Indoor heat exchanger 12 Indoor Fans 20 Outdoor unit 21 Compressor 22 Four-way valve 23 Outdoor heat exchanger 24 Outdoor fan 25. Expansion Mechanism 30 Gas side connection piping 31 Liquid-side connection piping 32 Safety shutoff valve 33 Liquid-side two-way valve 34. Gas-side three-way valve 40 Indoor Control Unit 41 Outdoor control unit

Claims

1. An outdoor unit having a compressor, an outdoor heat exchanger, an outdoor fan, an expansion mechanism, and an outdoor control unit, The indoor unit comprises an indoor heat exchanger, an indoor fan, and an indoor control unit. In an air conditioner in which the outdoor unit and the indoor unit are connected by refrigerant piping to form a refrigeration cycle circuit, The aforementioned refrigeration cycle circuit uses a flammable refrigerant, The indoor control unit transmits the rotational speed of the indoor fan to the outdoor control unit, and the outdoor control unit controls the compressor so that it does not start if the rotational speed of the indoor fan is below a predetermined rotational speed. An air conditioner characterized by the following features.

2. If the airflow from the indoor fan is below a predetermined airflow, the compressor is controlled not to start. The air conditioner according to feature 1.

3. A safety shutoff valve is installed in the aforementioned refrigeration cycle circuit. When the rotational speed of the indoor fan is below a predetermined rotational speed, the safety shut-off valve is controlled to close. An air conditioner according to claim 1 or 2.

4. The system controls the indoor fan to operate when the air conditioner is stopped. The air conditioner according to feature 1.

5. The air conditioner is equipped with an auxiliary power supply to provide power to the indoor fan when power is not supplied to the air conditioner. The air conditioner according to feature 1.

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