Air conditioner

Abstract

To suppress dissolution of a refrigerant into compressor lubricant.SOLUTION: In an air conditioner 1, an outdoor unit control device 100 cancels a cold air prevention mode, which maintains a rotation speed of an indoor fan 33 at a predetermined rotation speed, based on a first temperature, which is a temperature of lubricant in a compressor 20, and a second temperature, which is a temperature of a refrigerant passing through an indoor heat exchanger 31. For example, the outdoor unit control device 100 cancels the cold air prevention mode when the first temperature is equal to or larger than a first threshold determined based on a concentration of the lubricant in the compressor 20, and the second temperature is less than a second threshold determined based on the concentration of the lubricant in the compressor 20 and the first temperature.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In order to prevent the user from feeling chilly due to cold air being blown out of the air outlet of the indoor unit when the heating operation is started, the heat pump type air conditioner has an operation mode (hereinafter sometimes referred to as "cold air prevention mode") in which the rotation speed of the fan (hereinafter sometimes referred to as "indoor fan") of the indoor unit is maintained at a predetermined rotation speed until the heat exchanger (hereinafter sometimes referred to as "indoor heat exchanger") of the indoor unit reaches a predetermined temperature when the heating operation is started. The air conditioner having the cold air prevention mode cancels the cold air prevention mode when the indoor heat exchanger reaches the predetermined temperature, and increases the rotation speed of the indoor fan from the predetermined rotation speed.

[0003] For example, when the cold air prevention mode executed when the heating operation is started is released under a low outdoor temperature of 0°C or less, the rotation speed of the indoor fan increases, and the overall heat transfer coefficient and heat conductance increase, and the heat exchange amount of the indoor heat exchanger during heating operation, which functions as a condenser, increases. On the other hand, in the heat exchanger of the outdoor unit (hereinafter sometimes referred to as the "outdoor heat exchanger"), the temperature and pressure on the low pressure side decrease in order to ensure a heat exchange amount corresponding to the increased heat exchange amount in the indoor heat exchanger. In addition, if liquid refrigerant is retained in the indoor heat exchanger during heating operation, the temperature and pressure on the low pressure side of the outdoor heat exchanger further decrease. As a result, the density of the refrigerant sucked into the compressor decreases and the dryness of the refrigerant increases, so that the temperature (hereinafter sometimes referred to as the "lubricating oil temperature") of the compressor (hereinafter sometimes referred to as the "compressor lubricating oil") and the ambient temperature of the sliding parts of the compressor (hereinafter sometimes referred to as the "sliding part temperature") increase. When the lubricating oil temperature or the sliding part temperature rises, the refrigerant dissolved in the compressor lubricating oil boils (i.e., a phenomenon known as oil foaming) and the compressor lubricating oil is discharged from the compressor into the refrigerant circuit together with the refrigerant.

[0004] In response to this, there is a technique for reducing the amount of compressor lubricating oil discharged from the compressor to the refrigerant circuit by shifting the timing for increasing the compressor rotation speed from the timing for releasing the cold air prevention mode. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-222136 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, while the above-mentioned techniques can reduce the amount of compressor lubricating oil discharged into the refrigerant circuit, it is still difficult to avoid a situation in which the refrigerant is easily dissolved in the compressor lubricating oil.

[0007] Therefore, the present disclosure proposes a technique that can suppress dissolution of refrigerant into compressor lubricating oil. [Means for solving the problem]

[0008] The air conditioner of the present disclosure includes a compressor, an indoor heat exchanger, an indoor fan, and a control unit. The control unit cancels a mode in which the rotation speed of the indoor fan is maintained at a predetermined rotation speed, based on a first temperature that is a temperature of lubricating oil for the compressor and a second temperature that is a temperature of a refrigerant passing through the indoor heat exchanger. Effect of the Invention

[0009] According to the present disclosure, dissolution of refrigerant into compressor lubricating oil can be suppressed. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an air conditioner according to the present disclosure. [Diagram 2] FIG. 2 is a diagram showing an example of the configuration of the outdoor unit control device of the present disclosure. [Diagram 3] FIG. 3 is a diagram showing the conditions for canceling the cold air prevention mode of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, the same components are denoted by the same reference numerals.

[0012] [Example] <Air conditioner configuration> FIG. 1 is a diagram showing an example of the configuration of an air conditioner according to the present disclosure.

[0013] In Fig. 1, the air conditioner 1 has an outdoor unit 2 installed outdoors, and an indoor unit 3 connected to the outdoor unit 2 by a liquid pipe 4 and a gas pipe 5. One end of the liquid pipe 4 is connected to an operation valve 25 of the outdoor unit 2, and the other end is connected to a liquid pipe connection part 34 of the indoor unit 3. One end of the gas pipe 5 is connected to an operation valve 26 of the outdoor unit 2, and the other end is connected to a gas pipe connection part 35 of the indoor unit 3. A refrigerant circuit 10 of the air conditioner 1 is formed by the above-mentioned connection configuration.

[0014] The outdoor unit 2 has a compressor 20, a four-way valve 22, an outdoor heat exchanger 23, an operating valve 25 to which one end of the liquid pipe 4 is connected, an operating valve 26 to which one end of the gas pipe 5 is connected, an accumulator 21, and an outdoor fan 24. In the outdoor unit 2, the components other than the outdoor fan 24 are mutually connected by refrigerant piping to form an outdoor unit refrigerant circuit 10a that forms part of the refrigerant circuit 10.

[0015] The compressor 20 is driven by a motor 201 whose rotation speed is controlled by an inverter (not shown). The refrigerant discharge side of the compressor 20 is connected to a port a of the four-way valve 22 by a discharge pipe 61, and the refrigerant suction side of the compressor 20 is connected to a refrigerant outflow side of the accumulator 21 by a suction pipe 66.

[0016] The four-way valve 22 is a valve for switching the flow direction of the refrigerant, and has four ports a, b, c, and d. Port a is connected to the refrigerant discharge side of the compressor 20 by a discharge pipe 61, port b is connected to one refrigerant inlet / outlet of the outdoor heat exchanger 23 by a refrigerant piping 62, port c is connected to the refrigerant inlet side of the accumulator 21 by a refrigerant piping 65, and port d is connected to the operation valve 26 by an outdoor unit gas pipe 64.

[0017] The outdoor heat exchanger 23 exchanges heat between the refrigerant and outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 24. One refrigerant inlet / outlet of the outdoor heat exchanger 23 is connected to port b of the four-way valve 22 by a refrigerant piping 62, and the other refrigerant inlet / outlet of the outdoor heat exchanger 23 is connected to the operation valve 25 by an outdoor unit liquid pipe 63. The outdoor heat exchanger 23 functions as a condenser during cooling operation and as an evaporator during heating operation.

[0018] The expansion valve 27 is installed in the outdoor unit liquid pipe 63 .

[0019] The outdoor fan 24 is rotated by a fan motor (not shown) to draw in outside air from an intake port (not shown) of the outdoor unit 2 into the interior of the outdoor unit 2, while discharging the outside air that has exchanged heat with the refrigerant in the outdoor heat exchanger 23 to the outside of the outdoor unit 2 from an exhaust port (not shown) of the outdoor unit 2.

[0020] The refrigerant inflow side of the accumulator 21 is connected to port c of the four-way valve 22 via a refrigerant piping 65, and the refrigerant outflow side of the accumulator 21 is connected to the refrigerant suction side of the compressor 20 via a suction pipe 66. The accumulator 21 separates the refrigerant that has flowed into the accumulator 21 from the refrigerant piping 65 into gas refrigerant and liquid refrigerant, and causes only the gas refrigerant to be sucked into the compressor 20.

[0021] A discharge temperature sensor 73 that detects the temperature of the refrigerant discharged from the compressor 20 is installed in the discharge pipe 61 .

[0022] A compressor temperature sensor 81 is provided on the surface of the shell of the compressor 20 to detect the temperature of the compressor 20 (hereinafter, may be referred to as the "compressor temperature").

[0023] Further, the compressor 20 is provided with a compressor pressure sensor 82 that detects the pressure inside the compressor 20 (hereinafter, may be referred to as "compressor pressure").

[0024] An outdoor heat exchanger temperature sensor 75 is installed in the outdoor heat exchanger 23 to detect the temperature of the refrigerant flowing out from or flowing into the outdoor heat exchanger 23. In addition, an outdoor air temperature sensor 76 is installed near the air intake (not shown) of the outdoor unit 2 to detect the temperature of the outdoor air flowing into the outdoor unit 2.

[0025] In addition, the outdoor unit 2 has an outdoor unit control device 100.

[0026] On the other hand, the indoor unit 3 has an indoor heat exchanger 31, a liquid pipe connection part 34 to which the other end of the liquid pipe 4 is connected, a gas pipe connection part 35 to which the other end of the gas pipe 5 is connected, and an indoor fan 33. In the indoor unit 3, the components other than the indoor fan 33 are mutually connected by refrigerant piping to form an indoor unit refrigerant circuit 10b that forms part of the refrigerant circuit 10.

[0027] The indoor heat exchanger 31 exchanges heat between the refrigerant and indoor air taken into the indoor unit 3 from an inlet (not shown) of the indoor unit 3 by the indoor fan 33. In the indoor heat exchanger 31, one refrigerant inlet / outlet is connected to the liquid pipe connection part 34 by an indoor unit liquid pipe 68, and the other refrigerant inlet / outlet is connected to the gas pipe connection part 35 by an indoor unit gas pipe 69. The indoor heat exchanger 31 functions as an evaporator during cooling operation, and as a condenser during heating operation.

[0028] The indoor fan 33 is installed near the indoor heat exchanger 31 and rotated by a fan motor (not shown) to draw indoor air into the indoor unit 3 from an intake port (not shown) of the indoor unit 3, while blowing the indoor air that has exchanged heat with the refrigerant in the indoor heat exchanger 31 out into the room from an exhaust port (not shown) of the indoor unit 3.

[0029] An indoor heat exchanger temperature sensor 78 is installed in the indoor heat exchanger 31 to detect the temperature of the refrigerant passing through the indoor heat exchanger 31 (hereinafter may be referred to as the "indoor heat exchanger temperature"). Also, an indoor temperature sensor 79 is installed near the air intake (not shown) of the indoor unit 3 to detect the temperature of the indoor air flowing into the indoor unit 3.

[0030] <Refrigerant flow during heating operation> The arrows in Fig. 1 indicate the flow of refrigerant during heating operation. During heating operation, the outdoor unit control device 100 connects ports a and d, and connects ports b and c, in the four-way valve 22. This causes the outdoor heat exchanger 23 to function as an evaporator, and the indoor heat exchanger 31 to function as a condenser.

[0031] The high-pressure refrigerant discharged from the compressor 20 flows through the discharge pipe 61 and into the four-way valve 22, and then flows from the four-way valve 22 through the outdoor unit gas pipe 64 and into the gas pipe 5 via the operation valve 26. The refrigerant that has flowed through the gas pipe 5 flows into the indoor unit gas pipe 69 of the indoor unit 3 through the gas pipe connection part 35. The refrigerant flowing through the indoor unit gas pipe 69 flows into the indoor heat exchanger 31 and is condensed by heat exchange with the indoor air taken into the inside of the indoor unit 3 by the rotation of the indoor fan 33. In this way, during heating operation, the indoor heat exchanger 31 functions as a condenser, and the indoor air that has been heat exchanged with the refrigerant by the indoor heat exchanger 31 is blown out into the room from the air outlet (not shown) of the indoor unit 3, thereby heating the room in which the indoor unit 3 is installed. The refrigerant that flows out of the indoor heat exchanger 31 flows through the indoor unit liquid pipe 68 and flows into the liquid pipe 4 through the liquid pipe connection part 34.

[0032] The refrigerant that flows through the liquid pipe 4 and enters the outdoor unit 2 via the operating valve 25 flows into the expansion valve 27 installed in the outdoor unit liquid pipe 63. The refrigerant that passes through the expansion valve 27 is decompressed to become a low-pressure refrigerant. The refrigerant that passes through the expansion valve 27 flows into the outdoor heat exchanger 23. The refrigerant that flows into the outdoor heat exchanger 23 evaporates by heat exchange with the outside air that is taken into the outdoor unit 2 by the rotation of the outdoor fan 24. The refrigerant that flows out of the outdoor heat exchanger 23 flows in order through the refrigerant pipe 62, the four-way valve 22, the refrigerant pipe 65, the accumulator 21, and the suction pipe 66, and is sucked into the compressor 20 and compressed again. The refrigerant circulates through the refrigerant circuit 10 as described above, thereby performing the heating operation of the air conditioner 1.

[0033] <Configuration of outdoor unit control device> 2 is a diagram showing an example of the configuration of an outdoor unit control device according to the present disclosure. In FIG. 2, the outdoor unit control device 100 has a communication unit 101, a storage unit 102, and a control unit 103.

[0034] The communication unit 101 communicates with the indoor unit 3. An example of the communication unit 101 is a wired communication module.

[0035] The storage unit 102 stores parameters and the like necessary for various controls performed by the control unit 103. An example of the storage unit 102 is a memory.

[0036] The control unit 103 performs switching control of the four-way valve 22, switching control of the operation mode, etc. An example of the control unit 103 is a processor such as an MPU (Micro Processing Unit).

[0037] <Air conditioner operation> A signal indicating the operation mode of the indoor unit 3 (hereinafter sometimes referred to as an "operation mode signal") and the indoor heat exchanger temperature are input from the indoor unit 3 to the control unit 103 via the communication unit 101. A user of the air conditioner 1 can set the operation mode for the indoor unit 3 using, for example, a remote controller or the like, and can switch the operation mode, for example, between cooling operation, dehumidification operation, and heating operation.

[0038] The control unit 103 determines whether or not the heating operation has been started based on the operation mode signal, and when the heating operation has been started, sets the operation mode to the cold air prevention mode and transmits an operation mode signal indicating that the operation mode is the cold air prevention mode to the indoor unit 3 via the communication unit 101. The indoor unit 3 that has received the operation mode signal indicating that the operation mode is the cold air prevention mode operates in the cold air prevention mode when the heating operation is started, and maintains the rotation speed of the indoor fan 33 at a predetermined rotation speed.

[0039] Moreover, the control unit 103 receives the compressor temperature from the compressor temperature sensor 81 and the compressor pressure from the compressor pressure sensor 82 at regular intervals.

[0040] When the heating operation is started, the control unit 103 calculates the lubricant temperature [°C] according to the formula (1). In the formula (1), "α" is a fixed value that is preset according to the installation position of the compressor temperature sensor 81 on the surface of the shell of the compressor 20. The value of α is set to a larger value as the installation position of the compressor temperature sensor 81 is farther away from the place where the compressor lubricant oil accumulates in the compressor 20. Since the place where the compressor lubricant oil accumulates in the compressor 20 is the bottom of the shell of the compressor 20, it is preferable that the compressor temperature sensor 81 is installed, for example, on the surface of the bottom of the shell of the compressor 20. Note that the formula (1) is an example of a calculation formula when the compressor temperature sensor 81 is installed near the bottom of a vertical compressor having a place where the compressor lubricant oil accumulates (oil reservoir) at the bottom. When the installation position of the compressor temperature sensor 81 or the type of compressor is different, a calculation formula different from the formula (1) may be used. Lubricating oil temperature = compressor temperature - α …(1)

[0041] Here, the concentration of the compressor lubricant (hereinafter sometimes referred to as "lubricant concentration") decreases as the amount of refrigerant dissolved in the compressor lubricant (hereinafter sometimes referred to as "refrigerant dissolution amount") increases. In other words, the higher the lubricant concentration, the smaller the amount of refrigerant dissolved. Furthermore, the amount of refrigerant dissolved decreases as the lubricant temperature increases under a constant compressor pressure, and increases as the compressor pressure increases under a constant lubricant temperature. The memory unit 102 stores in advance a predetermined function or table showing the relationship between the compressor pressure, the lubricant temperature, and the lubricant concentration, and the control unit 103 calculates the lubricant concentration based on the compressor pressure and the compressor temperature according to the predetermined function or table stored in the memory unit 102.

[0042] Then, the control unit 103 uses a first threshold value TH1 as the lubricant temperature determined based on the lubricant concentration, and a second threshold value TH2 as the indoor heat exchanger temperature determined based on the lubricant concentration and the lubricant temperature to determine whether or not to cancel the cold air prevention mode based on the lubricant temperature and the indoor heat exchanger temperature as follows. Figure 3 is a diagram showing the conditions for canceling the cold air prevention mode of the present disclosure. The following description will be given by taking an example where the lubricant reference concentration is 55%.

[0043] As shown in FIG. 3, the control unit 103 determines the first threshold value TH1 to be 42[°C] so that the temperature of the indoor heat exchanger 31 does not become less than 35°C in order to prevent cold air from being blown out from the indoor unit 3. When the lubricant standard concentration is more than 55%, the slope of the graph becomes smaller than that of the graph of the lubricant standard concentration of 55%, and when the lubricant standard concentration is less than 55%, the slope of the graph becomes larger than that of the graph of the lubricant standard concentration of 55%. For this reason, it is preferable to set the first threshold value TH1 so that the higher the lubricant standard concentration is, the higher the first threshold value TH1 is, and the lower the lubricant concentration is, the lower the first threshold value TH1 is. In addition, it is preferable to set the lubricant standard concentration according to the amount and viscosity grade of the lubricant in the compressor 20. For example, in an air conditioner in which the lubricant in the compressor 20 is likely to be insufficient due to a long piping length, etc., it is preferable to set the lubricant standard concentration high, and when a lubricant with a low viscosity grade is used, it is preferable to set the lubricant standard concentration low.

[0044] Also, in FIG. 3, the control unit 103 determines the second threshold value TH2 to be a smaller value as the lubricant concentration becomes higher, and determines the second threshold value TH2 to be a larger value as the lubricant temperature becomes higher at the same lubricant concentration.

[0045] Furthermore, at the same indoor heat exchanger temperature, the lower the lubricant temperature, the greater the amount of refrigerant dissolved and the lower the lubricant concentration, so the control unit 103 cancels the cold air prevention mode in the shaded range of Figure 3, that is, when the lubricant temperature is equal to or greater than the first threshold value TH1 and the indoor heat exchanger temperature is less than the second threshold value.

[0046] For example, when the lubricant concentration is 55% of the reference lubricant concentration, the lubricant temperature is equal to or higher than the first threshold TH1 of 42°C, and the indoor heat exchanger temperature is lower than the second threshold, the control unit 103 cancels the cold air prevention mode. When the lubricant concentration is 55%, the second threshold TH2 is determined to be 43°C when the lubricant temperature is 50°C.

[0047] The control unit 103, which has cancelled the cold air prevention mode, transmits a signal indicating cancellation of the cold air prevention mode (hereinafter, may be referred to as a "cold air prevention mode cancellation signal") to the indoor unit 3 via the communication unit 101. The indoor unit 3, which has received the cold air prevention mode cancellation signal, cancels the cold air prevention mode and increases the rotation speed of the indoor fan 33 from a predetermined rotation speed.

[0048] The above describes the embodiment.

[0049] As described above, the air conditioner of the present disclosure (air conditioner 1 of the embodiment) has a compressor (compressor 20 of the embodiment), an indoor heat exchanger (indoor heat exchanger 31 of the embodiment), an indoor fan (indoor fan 33 of the embodiment), and a control unit (control unit 103 of the embodiment). The control unit releases a mode in which the rotation speed of the indoor fan is maintained at a predetermined rotation speed (cold air prevention mode of the embodiment) based on a first temperature (lubricating oil temperature in the embodiment) which is the temperature of the lubricating oil of the compressor, and a second temperature (indoor heat exchanger temperature in the embodiment) which is the temperature of the refrigerant passing through the indoor heat exchanger.

[0050] This makes it possible to suppress dissolution of the refrigerant into the compressor lubricating oil.

[0051] The air conditioner of the present disclosure also has a temperature sensor (compressor temperature sensor 81 in the embodiment) that is installed on the surface of the compressor shell and detects a third temperature (compressor temperature in the embodiment) that is the temperature of the compressor. The control unit calculates the first temperature based on the third temperature.

[0052] In this way, the first temperature can be calculated with high accuracy.

[0053] In addition, the control unit releases the mode in which the rotation speed of the indoor fan is maintained at a predetermined rotation speed when the first temperature is equal to or greater than a first threshold value (first threshold value TH1 in the embodiment) determined based on the concentration of the lubricating oil in the compressor and the second temperature is less than a second threshold value (second threshold value TH2 in the embodiment) determined based on the concentration of the lubricating oil in the compressor and the first temperature.

[0054] This can further suppress dissolution of the refrigerant into the compressor lubricating oil. [Explanation of symbols]

[0055] 1. Air conditioner 20 Compressor 31 Indoor heat exchanger 33 Indoor fan 103 Control section 81 Compressor temperature sensor

Claims

1. A compressor; An indoor heat exchanger; Indoor fan and a control unit that releases a mode in which a rotation speed of the indoor fan is maintained at a predetermined rotation speed, based on a first temperature that is a temperature of a lubricating oil of the compressor and a second temperature that is a temperature of a refrigerant passing through the indoor heat exchanger; An air conditioner equipped with the above.

2. a temperature sensor disposed on a surface of the compressor shell to detect a third temperature, the third temperature being a temperature of the compressor; The control unit calculates the first temperature based on the third temperature. The air conditioner according to claim 1.

3. The control unit releases the mode when the first temperature is equal to or greater than a first threshold determined based on a concentration of the lubricant and the second temperature is less than a second threshold determined based on the concentration and the first temperature. The air conditioner according to claim 1.

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