JPH07180933A - Refrigerating cycle device - Google Patents

Abstract

PURPOSE:To reduce the returning amount of refrigerant solution and increase the amount of heat generation of a motor in a compressor thereby peventing the dilution of refrigerating machine oil by a method wherein the solubility of refrigerant in the refrigerating machine oil is operated by the temperature and the suction pressure of refrigerating machine oil to control the operating frequeency of the compressor. CONSTITUTION:A compressor 1, a condenser, a pressure reducer 4 and an evaporator are connected sequentially in a refrigerating cycle device. In this case, a temperature detector 15, detecting the temperature of refrigerating machine oil, is attached to the bottom unit of the compressor 1. On the other hand, a suction pressure, produced in a circuit equipped with the pressure reducer 14, is operated by an operating device 11 based on the detecting temperature of a suction pressure saturation temperature detector 14. Further, an indoor controller 10 controls a relay circuit for sending power supply to an outdoor unit, the operating condition of cooling or heating and the informations of an indoor setting temperature and the like integrally. An outdoor control unit 9 controls the operating frequency of the compressor 1, the switching of a four-way valve 2 and the like based on a signal outputted from the indoor control unit 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cost reduction and high reliability of a protection device for an inverter-driven hermetic compressor used in a refrigeration cycle device.

[0002]

2. Description of the Related Art The prevention of burn-in of a compressor caused by dilution of refrigerating machine oil due to melting of a refrigerant recognizes the degree of superheat of the refrigerant by recognizing a temperature and a pressure signal from a thermistor and a pressure sensor attached to a discharge pipe, When the degree of superheat cannot be secured above a certain temperature, it is carried out by an indirect method of entering the protection control of the compressor.

A conventional method of protecting a compressor will be described below. The sensor outer electrode and the sensor inner electrode, which are reliably insulated by Teflon, are attached to the sensor body. Lead wires are attached to both electrodes, and then inserted into the sensor guide welded to the lower part of the compressor, and the sensor body and the sensor guide are fixed with bolts. As a result, the sensor outer electrode and the sensor inner electrode are immersed in the lubricating oil of the compressor. When the compressor is operated, the liquid refrigerant dissolves in the oil depending on the operating conditions. At this time, because of the difference in dielectric constant between oil and liquid refrigerant,
The capacitance output via the lead wire changes. This capacitance is detected and it is determined whether or not it has reached a preset determination value. If the judgment value is satisfied, the compressor continues to operate as it is, and if the judgment value is not reached, protection control is entered.

As another conventional example, Japanese Patent Laid-Open No. 2-2
There is one disclosed in Japanese Patent No. 25952.

In FIG. 13, reference numeral 1 denotes an inverter-driven compressor, which has a cylinder part 2, a main bearing part 3, an auxiliary bearing part 4, a motor 5 built in a case, and a lubricating oil A.
Then, the first temperature sensor 6 for detecting the lubricating oil temperature is provided in the compressor 1. Also, for compressor 1, four-way valve 1
0, outdoor heat exchanger 11, decompressor 12, indoor heat exchanger 13
Are sequentially communicated with each other to form a heat pump type refrigeration cycle. That is, during the cooling operation, the refrigerant flows in the direction indicated by the solid line arrow to form a refrigeration cycle, and the outdoor heat exchanger 11 acts as a condenser and the indoor heat exchanger 13 acts as an evaporator. Then, a second temperature sensor 14 for detecting the temperature of the condenser is provided for the outdoor heat exchanger 13. The control circuit is shown in FIG.
Reference numeral 20 is a commercial AC power supply, to which an inverter circuit 21 is connected. The inverter circuit 21 includes an AC-DC conversion unit 22 that converts an AC power supply voltage into a DC voltage, and an output of the AC-DC conversion unit 22 is a three-phase AC of a predetermined frequency by switching according to a command from a control unit 30 described later. It is composed of a DC-AC converter 23 for converting into a voltage, and the output of the DC-AC converter 23 is supplied to the motor 5 of the compressor 1.
Is supplied as drive power to the. On the other hand, 10 is an outdoor control unit, which is composed of a microcomputer and its peripheral circuits and controls the entire air conditioner. Then, the operation unit 31, the outdoor temperature sensor 32, the first temperature sensor 6, and the second temperature sensor 14 are connected to the control unit 30. Here, the control unit 10 controls the four-way valve 10 according to the cooling operation mode or the heating operation mode set by the operation operation unit 31, the air-conditioning load (the indoor setting set by the operation operation unit 31). Functional means for controlling the output frequency f of the inverter circuit 21 according to the temperature Ts and the detected temperature Ta of the indoor temperature sensor 32, the temperature detected by the first temperature sensor 6 and the temperature detected by the second temperature sensor 14 during heating operation. Functional means for obtaining a difference ΔT (= To−Tc) from Tc, functional means for comparing the temperature difference ΔT obtained above with a preset set value ΔT ₁ during heating operation,
During heating operation, the temperature difference ΔT is the set value Δ in the above comparison.
When T ₁ or less (ΔT ≦ ΔT ₁ ), the inverter circuit 21
It has a functional means for shifting up the output frequency f of 1 to a value higher by a predetermined value a.

Next, in the configuration as described above, FIG.
The operation will be described with reference to the flowchart of FIG. The heating operation mode is set by the operation operation unit 31, a desired room temperature Ts is set, and the operation start operation is further performed. Then, the control unit 30 switches the four-way valve 10 and operates the inverter circuit 21 to start the compressor. At this time, a heating cycle is formed in the refrigeration cycle, the indoor heat exchanger 13 functions as a condenser, and the outdoor heat exchanger 11 functions as an evaporator. That is, the heating operation is started. During this heating operation, the control unit 30 causes the difference (−) between the set indoor temperature Ts and the detected temperature Ta of the indoor temperature sensor 32 (−).
Ts−Ta) is calculated, and the larger the temperature difference Td, that is, the larger the air conditioning load (heating load), the higher the output frequency F of the inverter circuit 21 and the higher the capacity of the compressor 1. Then, as the temperature difference Td becomes smaller, that is, as the air conditioning load becomes smaller, the output frequency f is lowered. By the way, when the indoor temperature is kept constant during the heating operation, the difference ΔT between the temperature To of the lubricating oil of the compressor 1 and the condenser temperature Tc of the indoor heat exchanger 13 is further increased due to the change of the outdoor temperature, and further the inverter circuit 21. The output frequency F of is changed as a parameter. That is, the temperature difference ΔT becomes smaller as the outdoor temperature is lower, and the output frequency f is lower and the capacity of the compressor 1 is smaller. Generally, when the outdoor temperature decreases, the heating load of the room increases, so the compressor operates at a high frequency and the temperature difference ΔT tends to increase. However, a heating auxiliary device such as a heater and a heat pump are used together. If so, the frequency of operation of the compressor at the lowest frequency (f _min ) increases, and the temperature difference ΔT may decrease. When the temperature difference ΔT becomes smaller, the refrigerant penetration rate in the lubricating oil C of the compressor 1 increases and the oil film thickness in the bearing portions 3 and 4 of the compressor 1 decreases. Especially, when the temperature difference ΔT ₁ or less, the life of the compressor ₁ is reduced. Will be adversely affected. Therefore, the control unit 9 controls the detected temperature To of the first temperature sensor 6 during the heating operation.
(Lubricating oil temperature) and the temperature Tc (condenser temperature) detected by the second temperature sensor 14 are taken in, and the difference ΔT (=
To-Tc). Further, the control unit 9 stores the above ΔT ₁ as a set value in advance, compares the set value ΔT ₁ with the obtained temperature difference ΔT, and if the temperature difference ΔT is less than or equal to the set value ΔT ₁ in this comparison. (ΔT ≦ ΔT ₁ ), the output frequency F of the inverter circuit 21 is shifted up by a predetermined value a. Thus, as the output frequency f of the inverter circuit 21 increases, the capacity of the compressor 1 increases and the temperature difference ΔT increases. When the temperature difference Δ becomes large, the refrigerant penetration rate in the refrigerating machine oil of the compressor 1 can be suppressed to a certain value or less, and moreover, a sufficient oil film thickness in the bearing portion of the compressor 1 can be secured, and the compressor It is possible to significantly improve the service life of 1. In particular, since the heating operation is not interrupted, the comfort and the energy saving effect originally possessed by the variable capacity operation due to the adoption of the inverter circuit are not impaired. In this case, the control unit 9 determines that the temperature difference ΔT is equal to the set value ΔT.
Until above T ₁ repeats the upshift output frequency F, thereby surely set value [Delta] T ₁ or more to reach the temperature difference [Delta] T.
Then, when the temperature difference ΔT becomes equal to or larger than the set value ΔT ₁ , the control unit 30 restarts the control of the output frequency according to the air conditioning load.

[0007]

As described above, the conventional method of protecting the compressor detects the dilution of the refrigerating machine oil by incorporating the capacitance type sensor into the compressor. For this reason, the compressor must be incorporated in the manufacturing stage of the compressor, resulting in poor workability and an increase in the number of parts, resulting in an increase in cost. In another conventional technique, the heater suppresses the dissolution of the refrigerant into the refrigerating machine oil, but when the amount of liquid returned is large and a large amount of the refrigerant dissolves into the refrigerating machine oil, the heat from the heater is reduced. There is a problem in that the temperature of the refrigerating machine oil cannot be raised because it is only used as the heat of vaporization of the refrigerant in the section, and as a result, damage to the bearing and the like cannot be avoided.

The present invention has been made in order to solve the above problems, and is an air conditioner having a refrigeration cycle equipped with a variable capacity compressor, and has a simple structure, low cost and high reliability. The objective is to reliably obtain high compressor protection control.

[0009]

A refrigeration cycle apparatus according to claim 1 is a refrigeration cycle apparatus in which a compressor, a condenser, a pressure reducing device, an evaporator and the like are connected in an annular shape, and the temperature of refrigerating machine oil in the compressor is detected. Refrigerating machine oil temperature detecting means, suction pressure detecting means for detecting suction pressure of the compressor, and calculation for calculating refrigerant solubility in the refrigerating machine oil from detection results of the suction pressure detecting means and the refrigerating machine oil temperature detecting means. Means, and control means for controlling the operating frequency of the compressor based on the calculation result of the calculation means.

The refrigeration cycle apparatus of claim 2 is a compressor,
In a refrigeration cycle apparatus in which a condenser, a decompression device, an evaporator and the like are connected in an annular shape, an evaporation temperature detecting means for detecting an evaporation temperature of a refrigerant in the evaporator and an intake pressure of the compressor are calculated from the evaporation temperature. Intake pressure calculating means, refrigerating machine oil temperature detecting means for detecting the temperature of refrigerating machine oil in the compressor, calculating means for calculating a refrigerant dissolution amount of the refrigerating machine oil from the detected evaporation temperature and suction pressure, and this calculation Control means for controlling the operating frequency of the compressor based on the calculation result of the means.

The refrigeration cycle apparatus of claim 3 is a compressor,
In a refrigeration cycle device in which a condenser, a decompressor, an evaporator and the like are connected in an annular shape, refrigerating machine oil temperature detecting means for detecting the temperature of refrigerating machine oil in the compressor, and the refrigerating machine oil from the detection result of the refrigerating machine oil temperature detecting means. And a control means for controlling the operating frequency of the compressor on the basis of the calculation result of this calculation means.

The refrigeration cycle apparatus of claim 4 is the same as that of claim 1.
In the refrigeration cycle apparatus described in any one of 3 to 3, the control means controls the operating frequency of the compressor and also controls the voltage-frequency pattern.

A refrigeration cycle apparatus according to claim 5 is a compressor,
In a refrigeration cycle device in which a condenser, a decompression device, an evaporator, and the like are connected in a ring shape, in a refrigeration cycle device that detects refrigerant solubility in refrigerating machine oil in the compressor, detects refrigerant solubility in refrigerating machine oil in the compressor. A refrigerant solubility detection means and a control means for controlling the operating frequency of the compressor based on the refrigerant solubility and for setting an upper limit value of the operating frequency of the compressor are provided.

[0014]

In the refrigeration cycle apparatus of the first aspect, the solubility of the refrigerant in the refrigerating machine oil is calculated from the refrigerating machine oil temperature detected by the refrigerating machine oil temperature detecting means and the suction pressure detected by the suction pressure detecting means, and the operating frequency of the compressor is calculated. By performing the control, the return amount of the refrigerant liquid is reduced and the calorific value of the electric motor of the compressor is increased, so that the dilution of the refrigerating machine oil can be prevented.

According to another aspect of the refrigeration cycle apparatus of the present invention, the refrigerating machine oil is calculated from the suction pressure of the compressor calculated from the evaporating temperature detected by the evaporating temperature detecting means and the temperature of the refrigerating machine oil in the compressor detected by the refrigerating machine oil temperature detecting means. Since the amount of dissolved refrigerant is calculated and the operating frequency of the compressor is controlled, workability and cost are reduced.

In the refrigeration cycle apparatus of the third aspect, the refrigerant solubility in the refrigerating machine oil is calculated from the temperature of the refrigerating machine oil in the compressor detected by the refrigerating machine oil temperature detecting means to control the operating frequency of the compressor. Is simplified and the price is further reduced.

In the refrigeration cycle apparatus according to the present invention, when the refrigerating machine oil temperature is detected to be lower than the set temperature, the refrigerating cycle device not only controls the operating frequency but also removes the operating point from the U-F pattern. By vaporizing the refrigerant by the heat from the electric motor, it is possible to more quickly get out of the region where the refrigerating machine oil is highly diluted.

In the refrigeration cycle apparatus of the fifth aspect, when the air conditioning load is small or the set temperature and the room temperature are reversed, the increase of the operating frequency of the compressor is prohibited, so that the compressor can be protected without impairing the comfort. .

[0019]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 shows a refrigerant circuit diagram of the first embodiment. A compressor 1 for compressing a low-temperature low-pressure gas refrigerant into a high-temperature high-pressure gas refrigerant, a condenser for converting the high-temperature high-pressure gas refrigerant into a high-temperature high-pressure liquid refrigerant, and a decompressor 4 converting a high-temperature high-pressure liquid refrigerant into a low-temperature low-pressure two-phase refrigerant.
In a refrigeration cycle device in which a low-temperature low-pressure low-pressure low-pressure two-phase refrigerant is changed to a low-temperature low-pressure gas refrigerant, a compressor 1 is an inverter-driven compressor capable of shifting up to a maximum frequency of 130 Hz. Is equipped with a temperature detector 15 for detecting the temperature of the refrigerating machine oil. The circuit provided with the pressure reducer is the suction pressure measuring circuit 5, and the suction pressure generated by this circuit is calculated by calculating the suction pressure by the calculation device 11 from the temperature detected by the suction pressure saturation temperature detector 14. It has been demanded. The indoor control unit 10 also collectively controls information such as a relay circuit for sending power to the outdoor unit A, the operating status of cooling or heating, and the indoor set temperature. The outdoor control unit 9 controls the operating frequency of the compressor 1 based on the signal sent from the indoor control unit 10, and also controls the switching of the four-way valve 2 and the like.

The operation of the refrigeration cycle apparatus shown in FIG. 1 will be described. First, the flow of the refrigerant during the cooling operation will be described. The low-temperature low-pressure gas refrigerant is sucked into the compression element portion through the suction port 1b of the compressor 1, is compressed into the high-temperature high-pressure gas refrigerant here, and is guided to the four-way valve 2 through the discharge port 1a. In the case of cooling operation, the high-temperature and high-pressure gas refrigerant is guided to the outdoor heat exchanger 3,
Here, the gas refrigerant is liquefied, and at this time, heat of condensation is released to the outside of the room. Further, the liquefied high-pressure refrigerant becomes a low-temperature low-pressure gas-liquid two-phase refrigerant by the pressure reducer 4 and is guided to the indoor heat exchanger 7. Here, heat is absorbed from the air in the room and the refrigerant evaporates to become a low-temperature low-pressure gas refrigerant. In this way, the indoor temperature decreases, and the cooling operation is being performed. After that, the refrigerant is sent through the four-way valve 2 to the suction port 1a of the compressor 1 to perform the refrigeration cycle operation.
Next, the flow of the refrigerant during the heating operation will be described. In this case, by switching the four-way valve 2 and reversing the flow direction of the refrigerant, the indoor heat exchanger 7 functions as a condenser and the outdoor heat exchanger 3 functions as an evaporator. Since the operation of is similar, the description is omitted. In the arrows shown in FIG. 1, the solid line indicates the flow direction of the refrigerant during cooling operation, and the wavy line indicates the flow direction of the refrigerant during heating.

In the suction pressure generation circuit 5, the characteristic that the temperature of the two-phase refrigerant is constant when the pressure is constant is utilized, and the arithmetic unit 11 operates on the basis of the suction pressure saturation temperature detected by the suction pressure saturation temperature detector 14. It is calculated by calculating the suction pressure. Further, from the refrigerating machine oil temperature detected by the refrigerating machine oil temperature detector 15 and the suction pressure, the computing unit 11 calculates the solubility of the refrigerant in the refrigerating machine oil. Further, the outdoor control unit 9 stores in advance a limit value φo of the solubility of the refrigerant in the refrigerating machine oil. next,
The operation frequency control of the compressor 1 will be described based on the flowchart of FIG. Normally, the air conditioner has an indoor control unit 10
Then, the indoor temperature To is set, and when the temperature difference ΔT between this value and the actual indoor temperature Tr is small, the operating frequency is lowered, and when ΔT is large, the operating frequency is judged to be high and the operating frequency is increased. (Step 100). However, depending on various operating conditions at that time, the so-called liquid back operation in which the two-phase refrigerant reaches the suction port 1a as it is and is compressed by the compressor 1 by the control by ΔT is performed.
When the amount of the liquid refrigerant returning increases, a large amount of the liquid refrigerant melts into the refrigerating machine oil, and the refrigerating machine oil becomes in a diluted state, and it becomes impossible to secure a sufficient oil film on the main shaft 20 of the compressor as shown in FIG. . At this time, the solubility is determined by the arithmetic unit 11 from the suction pressure detected by the suction pressure measuring circuit 5 (step 102) and the refrigerating machine oil temperature detected by the temperature detector 15 (step 101) (step 103). If the value is smaller than the solubility limit value φo stored in the outdoor control unit, the compressor 1 operates under normal control, and φo
If larger, protection control is entered and the frequency is increased by a (step 105). This a is set at a level of several Hz depending on the operating frequency band and the solubility. Then, when the calculated solubility exceeds the limit value φo, the normal control is resumed. As a result, the compressor 1 can be protected without being damaged or stopped.

Example 2. In the first embodiment, the suction pressure generation circuit 5 as shown in FIG. 1 is provided to obtain the suction pressure. However, as shown in FIG. 4, the suction pressure generation circuit is not provided, and the heat exchange temperature of the evaporator is detected to be detected. Arithmetic unit 11
The suction pressure may be calculated by

In FIG. 4, during the cooling operation in which the refrigerant flows in the direction of the solid line arrow, the outdoor heat exchanger 3 functions as a condenser and the indoor heat exchanger 7 functions as an evaporator. At this time, the indoor heat exchanger temperature detector 13 becomes an evaporation temperature detector. The evaporation temperature CT of the indoor heat exchanger 7, which is an evaporator, is detected. The calculation device 11 calculates the suction pressure based on this value. Further, during the heating operation in which the refrigerant flows in the direction of the dashed arrow, the outdoor heat exchanger 3
Is an evaporator, and the indoor heat exchanger 7 is a condenser. At this time, the outdoor heat exchanger temperature detector 12g serves as an evaporation temperature detector and detects the evaporation temperature CT. The suction pressure is calculated by the calculation device 11 according to this value. The compressor operating frequency control of the second embodiment is shown in the flowchart of FIG. Compared with the first embodiment, the suction pressure generating circuit 5 in FIG. 1 can be omitted, so that the workability at the time of manufacturing is improved, and the cost is also reduced. The following description is the same as that of the first embodiment, and the description thereof is omitted.

Example 3. In Example 1 and Example 2, the solubility of the refrigerant in the refrigerating machine oil was obtained from the suction pressure and the refrigerating machine oil temperature, but the solubility can be estimated from the temperature of the refrigerating machine oil for control.

Next, the third embodiment will be described. By comparing the relationship between the solubility of the refrigerant and the refrigerating machine oil as shown in FIG. 6 and the range of the suction pressure which is considered to occur when the air conditioner is actually operated, the refrigerating machine oil temperature and the solubility are The relational expression can be obtained approximately. The relational expression of the refrigerating machine oil and the solubility is stored in advance in the computing device 11, and the limit value φo of the solubility in the refrigerant and the refrigerating machine oil to be controlled in advance is stored in the outdoor control unit 9. The compressor operating frequency control of the third embodiment is shown in FIG.
During operation of the air conditioner, the refrigerator oil temperature detector 15 detects the refrigerator oil temperature (step 101). The solubility φ is calculated by the calculation device 11 based on this temperature (step 10).
3). The difference from the first and second embodiments is that the detection and calculation of the suction pressure can be omitted. This simplifies the control and facilitates the control of the compressor without performing complicated calculation. . The following description is the same as that of the first embodiment, and the description thereof is omitted.

Example 4. Next, a fourth embodiment will be described. When detecting the excessive dissolution of the refrigerant in the refrigerating machine oil, in Examples 1 to 3, the operating frequency of the compressor 1 is changed to perform the protection control from the seizure of the compressor caused by the dilution of the refrigerating machine oil. However, by changing the voltage-frequency operation pattern (hereinafter referred to as Vf pattern) of the compressor 1 to this, the amount of heat generated from the motor can be increased, and a dilute state due to the penetration of the refrigerant into the refrigerating machine oil can be avoided earlier. .

Motor 1 of compressor 1 normally driven by an inverter
The function of voltage and frequency is determined so that the operation of 8 is the most efficient, and the frequency during operation is stored in the outdoor control unit 9 as the graph of FIG. Has been done. At this time, electric power of the motor is converted into mechanical motion and loss is minimized, so that heat generation from the motor is minimized. In addition, in the present embodiment, the outdoor control unit 9 also stores Vf patterns such as b in FIG. 8 other than the optimum Vf pattern. In this Vf pattern b, the amount of heat generated from the motor increases as compared with the pattern a. Further, the outdoor control unit 9 stores in advance a limit value φo of the solubility of the refrigerant in the refrigerating machine oil. Next, the operation frequency control of the compressor will be described based on the flowchart of FIG. The air conditioner sets the indoor temperature To by the indoor control unit 10, and lowers the operating frequency when the temperature difference ΔT between this value and the actual indoor temperature Tr is smaller than a preset value Ta, and ΔT
When is large, it is determined that the air conditioning load is high, and control is performed to raise the operating frequency (step 100). However, when the refrigerant dissolves in the refrigerating machine oil, an oil film cannot be secured on the main shaft 20 of the compressor 1 and seizure due to friction may occur. At this time, when the solubility value calculated by the method as in Examples 1 to 3 satisfies the limit value φo, the normal frequency control by the air conditioning load is performed, and when the solubility value is exceeded, the operation is performed. The frequency is increased by a Hz (step 105), and the operation is performed by changing the Vf pattern from a to b in FIG. 8 (step 108). When the value of the detected solubility satisfies the limit value φo, the operation frequency control by the normal air conditioning load is resumed. According to this protection control, the temperature of the refrigerating machine oil rises faster because the temperature of the motor rises due to the rise of the frequency and the amount of backing-up liquid decreases and the heat generated from the loss of the motor gives more heat to the compressor. Since the solubility of the refrigerant in the refrigerating machine oil can be reduced, seizure of the compressor due to dilution of the refrigerating machine oil can be prevented with higher reliability while maintaining comfort.

Example 5. In a normal air conditioner, the set temperature (T
The air conditioning load ΔT is detected from the temperature difference between the set temperature and the room temperature (Troom), and the operation control of the compressor is performed based on this value. However, depending on the operating conditions such as the temperature conditions at that time, in the control by ΔT, the two-phase refrigerant is sucked into the compressor between the two-phase refrigerant, and so-called liquid back operation is performed. When the return amount of the liquid refrigerant increases, a large amount of the liquid refrigerant dissolves in the refrigerating machine oil, the refrigerating machine oil is in a diluted state, and a sufficient oil film cannot be secured on the main shaft of the compressor or the like. At this time, based on the refrigerant solubility φ in the refrigerating machine oil detected by the method as in Examples 1 to 3, when this value is larger than φset, the frequency is increased by a. This a is set at a level of several Hz depending on the operating frequency band and the solubility. However, if the operating frequency is increased as it is, the decrease in solubility is delayed with respect to the increase in the operating frequency and the frequency will increase more than necessary. Since it rises more than necessary at times, the phenomenon of being too cold and too hot will occur. As a countermeasure against this, the lower limit value of the air conditioning load is set to ΔTset2, and when the air conditioning load becomes smaller than this value, the increase in frequency is stopped, so comfort is not impaired.

[0029]

The refrigeration cycle apparatus according to the first aspect of the present invention is a refrigeration cycle apparatus in which a compressor, a condenser, a decompression device, an evaporator and the like are connected in an annular shape, and a refrigeration oil temperature for detecting the temperature of the refrigeration oil in the compressor. Detection means, suction pressure detection means for detecting the suction pressure of the compressor, calculation means for calculating the refrigerant solubility in the refrigeration oil from the detection results of the suction pressure detection means and the refrigeration oil temperature detection means, and Since the control means for controlling the operating frequency of the compressor based on the calculation result of the calculation means is provided, the refrigerating machine oil temperature detected by the refrigerating machine oil temperature detecting means and the suction pressure detected by the suction pressure detecting means. By calculating the solubility of the refrigerant in the refrigerating machine oil and controlling the operating frequency of the compressor, the amount of refrigerant liquid returned can be reduced and the calorific value of the compressor motor can be increased. From, it is possible to prevent the dilution of the refrigerator oil.

The refrigeration cycle apparatus of claim 2 is a compressor,
In a refrigeration cycle apparatus in which a condenser, a decompression device, an evaporator and the like are connected in an annular shape, an evaporation temperature detecting means for detecting an evaporation temperature of a refrigerant in the evaporator and an intake pressure of the compressor are calculated from the evaporation temperature. Intake pressure calculating means, refrigerating machine oil temperature detecting means for detecting the temperature of refrigerating machine oil in the compressor, calculating means for calculating a refrigerant dissolution amount of the refrigerating machine oil from the detected evaporation temperature and suction pressure, and this calculation Since the control means for controlling the operating frequency of the compressor based on the calculation result of the means is provided, the suction pressure of the compressor calculated from the evaporation temperature detected by the evaporation temperature detecting means and the refrigerator oil temperature. Since the refrigerant dissolution amount of the refrigerating machine oil is calculated from the temperature of the refrigerating machine oil in the compressor detected by the detecting means to control the operating frequency of the compressor, workability and cost are reduced.

The refrigeration cycle apparatus of claim 3 is a compressor,
In a refrigeration cycle device in which a condenser, a decompressor, an evaporator and the like are connected in an annular shape, refrigerating machine oil temperature detecting means for detecting the temperature of refrigerating machine oil in the compressor, and the refrigerating machine oil from the detection result of the refrigerating machine oil temperature detecting means. Since it is configured to include a calculating means for calculating the refrigerant solubility in the refrigerant, and a control means for controlling the operating frequency of the compressor based on the calculation result of this calculating means, the compression detected by the refrigerating machine oil temperature detecting means. Since the refrigerant solubility in the refrigerating machine oil is calculated from the temperature of the refrigerating machine oil in the machine to control the operating frequency of the compressor, the control is simplified and the price is further reduced.

The refrigeration cycle apparatus of claim 4 is the same as that of claim 1.
In the refrigeration cycle apparatus according to any one of claims 1 to 3, the control means controls the operating frequency of the compressor and also controls the voltage-frequency pattern, so that the refrigerating machine oil temperature is detected at a temperature lower than the set temperature. Not only control the operating frequency but also vaporize the refrigerant by the heat from the electric motor that is generated to remove the operating point from the U-F pattern, so that the refrigerator oil is quickly removed from the highly diluted region. To enable that.

The refrigeration cycle apparatus of claim 5 is a compressor,
In a refrigeration cycle device in which a condenser, a decompression device, an evaporator, and the like are connected in an annular shape, a refrigerant solubility detection unit that detects a refrigerant solubility in refrigerating machine oil in the compressor, and an operating frequency of the compressor based on the refrigerant solubility. To control
Since the control means for setting the upper limit value of the operating frequency of the compressor is provided, in order to prohibit the increase of the operating frequency of the compressor when the air conditioning load is small or the set temperature and the room temperature are reversed. Protects the compressor without sacrificing comfort.

[Brief description of drawings]

FIG. 1 is a refrigerant piping system diagram of a refrigeration cycle apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a compressor of the refrigeration cycle device according to the first embodiment of the present invention.

FIG. 3 is a flowchart of control contents of the refrigeration cycle apparatus according to the first embodiment of the present invention.

FIG. 4 is a refrigerant piping system diagram of a refrigeration cycle apparatus according to Embodiment 2 of the present invention.

FIG. 5 is a flowchart of control contents of the refrigeration cycle device according to the second embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between pressure / temperature and solubility of a refrigeration cycle apparatus according to Example 2 of the present invention.

FIG. 7 is a flowchart of control contents of the refrigeration cycle apparatus according to the third embodiment of the present invention.

FIG. 8 is a diagram showing an operation Vf pattern of the refrigeration cycle device according to the third embodiment of the present invention.

FIG. 9 is a control flowchart of the refrigeration cycle device according to the fourth embodiment of the present invention.

FIG. 10 is a control flowchart of the refrigeration cycle device according to the fifth embodiment of the present invention.

FIG. 11 is a cross-sectional view of a capacitance type sensor added to a compressor of a conventional refrigeration cycle device.

FIG. 12 is a flowchart of control contents of a conventional refrigeration cycle apparatus.

FIG. 13 is a refrigerant circuit diagram of another conventional refrigeration cycle apparatus.

FIG. 14 is a control circuit diagram of another conventional refrigeration cycle apparatus.

FIG. 15 is a flow chart for explaining the operation of another conventional refrigeration cycle apparatus.

[Explanation of symbols]

 A outdoor unit B indoor unit 1 compressor 2 four-way valve 4a pressure reducer 4b pressure reducer 5 suction pressure measurement circuit 6a stop valve (liquid side) 6b stop valve (gas side) 8 accumulator 9 indoor control unit 10 outdoor control unit 11 arithmetic unit 12 Outdoor heat exchanger temperature detector 13 Indoor heat exchanger temperature detector 14 Suction pressure saturation temperature detector 15 Refrigerator oil temperature detector 17 Compressor compression element part 18 Motor (electric motor) 19 Bearing 20 Main shaft 21 Oil pump 22 Terminal part

Claims (5)

[Claims] 1. A refrigeration cycle apparatus in which a compressor, a condenser, a decompression device, an evaporator, etc. are connected in an annular shape, and a refrigerating machine oil temperature detecting means for detecting a temperature of refrigerating machine oil in the compressor, and suction of the compressor. Suction pressure detecting means for detecting the pressure, calculating means for calculating the refrigerant solubility in the refrigerating machine oil from the detection results of the suction pressure detecting means and the refrigerating machine oil temperature detecting means, and the compression based on the calculating result of the calculating means. A refrigeration cycle apparatus comprising: a control unit that controls the operating frequency of the machine. 2. A refrigeration cycle apparatus in which a compressor, a condenser, a decompression device, an evaporator and the like are connected in an annular shape, and an evaporation temperature detecting means for detecting an evaporation temperature of a refrigerant in the evaporator, and the evaporation temperature detecting means for detecting the evaporation temperature of the refrigerant. From the suction pressure calculation means for calculating the suction pressure of the compressor, the refrigerating machine oil temperature detecting means for detecting the temperature of the refrigerating machine oil in the compressor, and the evaporation temperature and the suction pressure thus detected, the refrigerant dissolution amount of the refrigerating machine oil is calculated. A refrigeration cycle apparatus comprising: arithmetic means for performing arithmetic operation; and control means for controlling the operating frequency of the compressor based on the arithmetic result of the arithmetic means. 3. A refrigeration cycle apparatus in which a compressor, a condenser, a decompression device, an evaporator, etc. are connected in an annular shape, and a refrigeration oil temperature detection means for detecting the temperature of refrigeration oil in the compressor, and the refrigeration oil temperature detection means. A refrigeration cycle apparatus comprising: a computing unit that computes the solubility of the refrigerant in the refrigerating machine oil from the detection result of the unit; and a control unit that controls the operating frequency of the compressor based on the computation result of the computing unit. 4. The refrigeration cycle apparatus according to claim 1, wherein the control unit controls the operating frequency of the compressor and also controls the voltage-frequency pattern. 5. A refrigeration cycle apparatus in which a compressor, a condenser, a decompression device, an evaporator and the like are connected in an annular shape, and a refrigerant solubility detecting means for detecting a refrigerant solubility in refrigerating machine oil in the compressor, and the refrigerant solubility. A refrigeration cycle apparatus comprising: a control unit that controls the operating frequency of the compressor based on the control unit and sets an upper limit value of the operating frequency of the compressor.