JP2001174075A - Refrigeration equipment - Google Patents

Abstract

(57) [PROBLEMS] To prevent excessive rise of the discharge temperature of a compressor and to prevent reduction of motor efficiency by using a refrigerant having a high discharge temperature such as R32. A compressor (121), an outdoor heat exchanger (123), an electric expansion valve (Z), and an indoor heat exchanger (131) are provided.
Then, R32 alone is used as the refrigerant. When the discharge temperature of the compressor (121) is equal to or lower than the limit value, the opening degree of the electric expansion valve (Z) is controlled so that the superheat degree of the refrigerant on the evaporation side or the suction superheat degree of the compressor (121) becomes a predetermined temperature. Meanwhile, the compressor (121)
When the discharge temperature exceeds the limit value, the opening of the electric expansion valve (Z) is controlled based on the discharge temperature of the compressor (121). The compressor (121) is a high-pressure dome type, the compressor motor is a brushless DC motor having a rare earth magnet, and the J coercivity (Hcj) of the rare earth magnet is 23 kOe (183 kA).
/ M) or more. The compressor motor is driven by reluctance torque, and the power supplied to the compressor motor is PAM controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a refrigeration apparatus,
In particular, the present invention relates to a refrigeration apparatus including a refrigerant that increases the discharge temperature of a compressor.

[0002]

2. Description of the Related Art Conventionally, various refrigeration systems including an air conditioner include a compressor, a four-way switching valve, an outdoor heat exchanger, and an expansion mechanism as disclosed in Japanese Patent Application Laid-Open No. 8-189735. And a refrigerant circuit in which an indoor heat exchanger is connected in order. An electric expansion valve is applied to the expansion mechanism.

[0003]

The refrigeration system including the above-described air conditioner requires the protection of the ozone layer and the prevention of global warming as social demands. , A conventional mixed refrigerant (R407C,
R410A) The use of a mixed refrigerant containing more R32 than that of R410A is called for. Since R32 has a relatively high theoretical COP and heat transfer coefficient and a low pressure loss of the refrigerant, it has a characteristic that energy efficiency is high when used in an air conditioner.

However, on the other hand, R32 is a conventional R22,
There is a characteristic that the discharge temperature of the compressor is about 20 ° C. higher than R407C and R410A.

[0005] Therefore, if R32 is used with the conventional air conditioner, there is a problem that the discharge temperature of the compressor becomes excessively high and that the motor efficiency is lowered. Further, there is a problem that it is difficult to improve the heating capacity.

The present invention has been made in view of the above points, and uses a refrigerant having a high discharge temperature such as R32 to prevent an excessive rise in the discharge temperature of a compressor and prevent a decrease in motor efficiency. The purpose is to do so.

[0007]

More specifically, as shown in FIG. 1, the first invention comprises a compressor (121), a heat source side heat exchanger (123), an electric expansion valve (Z), and a use side. It is intended for a refrigeration system equipped with a heat exchanger (131). R32 alone or an R32-rich mixed refrigerant in which R32 exceeds 50 wt%, or a mixed refrigerant in which the R32-rich refrigerant has a discharge temperature higher than R22 by about 10 ° C. is used. In addition, the compressor (12
Electric expansion valve (Z) so that the discharge temperature of 1) becomes a predetermined temperature
There is provided a control means (300) for controlling the degree of opening.

In the present invention, the refrigerant temperature such as R32 can be exhibited by controlling the discharge temperature of the compressor (121).

In the second invention, the control means (300)
May detect at least one of the discharge temperature of the compressor (121), the evaporation temperature of the refrigerant, and the condensation temperature of the refrigerant, and control the opening of the electric expansion valve (Z) based on the detected temperature. .

[0010] In the third invention, the compressor (121) may be a high-pressure dome type compressor (121).

In the fourth invention, the control means (300)
When the discharge temperature of the compressor (121) is below the limit value,
The opening degree of the electric expansion valve (Z) is controlled so that the refrigerant superheat degree on the evaporation side or the suction superheat degree of the compressor (121) becomes a predetermined temperature, while the discharge temperature of the compressor (121) exceeds the limit value. And the opening degree of the electric expansion valve (Z) may be controlled based on the discharge temperature of the compressor (121).

In the fifth invention, the compressor motor (220) of the compressor (121) may be constituted by a DC motor.

In the sixth invention, the compressor motor (22
The permanent magnet (222) of (0) may be composed of a ferrite magnet.

In the seventh invention, the compressor motor (22
The permanent magnet (222) of (0) may be composed of a rare earth magnet.

In the eighth invention, it is preferable that the rare earth magnet has a J coercive force (Hcj) of 23 kOe (183 kA / m) or more.

In the ninth invention, the compressor motor (22
0) may be configured to be driven by reluctance torque.

In the tenth aspect, the control means (30
0) may include a PAM control unit (310) that performs pulse amplitude modulation on the power supplied to the compressor motor (220).

Further, in the eleventh invention, the ratio between the rated heating capacity and the rated cooling capacity under the JIS standard conditions may be set to 1.2 or more so that the refrigerant operation and the heating operation can be switched. .

In the twelfth aspect, the refrigerant operation and the heating operation can be switched, and the ratio between the rated heating capacity and the rated cooling capacity under the JIS standard conditions may be set to 1.4 or more. .

Further, in the thirteenth invention, at least the heating operation is performed, and the heating low-temperature capacity and the heating standard capacity when the dry-bulb temperature of the outside air is 2 ° C. and the wet-bulb temperature is 1 ° C. May be set to 0.92 or more.

Further, in the fourteenth aspect, at least the heating operation is performed, and the heating low-temperature capacity and the heating standard capacity when the dry-bulb temperature of the outside air is 2 ° C. and the wet-bulb temperature is 1 ° C. May be set to 0.86 or more.

[0022]

Therefore, according to the present invention, R
32 and the like, and the discharge temperature of the compressor (121) is controlled by the opening degree of the electric expansion valve (Z). Therefore, when the discharge temperature becomes high, the valve opening degree is increased to increase the refrigerant flow rate. And the discharge temperature can be reduced.

As a result, it is possible to sufficiently exhibit the characteristics such as R32 that the heating capacity is easily increased. In addition, the heating efficiency can be improved and the efficiency can be improved.

In particular, according to the third aspect, in the case of the high-pressure dome type compressor (121), the discharge temperature and the motor temperature are in a proportional relationship, so that the above-mentioned effects can be further exhibited.

According to the fifth aspect of the present invention, the brushless DC motor is applied to the compressor motor (220).
The motor efficiency can be improved.

According to the seventh aspect, the brushless D
Since a rare earth magnet is used for the permanent magnet (222) of the C motor, it is possible to cope with an increase in the discharge temperature of the compressor (121), and to exhibit characteristics such as R32.

According to the eighth and ninth aspects, the reluctance torque is used for the brushless DC motor, and the J coercive force (Hcj) of the rare earth magnet is 23 kOe (1 k).
83 kA / m) or more, the characteristics such as R32 can be more reliably exhibited.

According to the tenth aspect, the brushless DC motor adopts the PAM control method.
It is possible to further improve the heating capacity while exhibiting characteristics such as 2.

[0029]

Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, the refrigerating apparatus (100) of the present embodiment is an air conditioner of a so-called separate type. The refrigeration apparatus (100) includes a refrigerant circuit (110) in which one outdoor unit (120) as a heat source side unit is connected to one indoor unit (130) as a utilization side unit. I have.

The outdoor unit (120) includes a compressor (1).
21), a four-way switching valve (122) that switches as shown by the solid line in the cooling operation cycle and as shown by the broken line in the heating operation cycle, and a heat source that functions as a condenser during the cooling operation and as an evaporator during the heating operation An outdoor heat exchanger (123), which is a side heat exchanger, and a direct-acting electric expansion valve (Z) constituting an expansion mechanism for reducing the pressure of the refrigerant are provided.

On the other hand, the indoor unit (130) is provided with an indoor heat exchanger (131) which is a use side heat exchanger that functions as an evaporator during the cooling operation and as a condenser during the heating operation.

That is, the outdoor heat exchanger (123) and the indoor heat exchanger (131) are configured one-to-one.

The outdoor heat exchanger (123) is provided with an outdoor fan (120F), while the indoor heat exchanger (131) is provided with an indoor fan (130F).

The compressor (121), the four-way switching valve (122), the outdoor heat exchanger (123), the electric expansion valve (Z), and the indoor heat exchanger (131) are sequentially connected to the refrigerant pipe (140). The refrigerant circuit (111) is connected to a closed circuit that can be reversibly operated by switching a four-way switching valve (122) between a cooling operation cycle and a heating operation cycle so as to generate heat transfer by circulation of the refrigerant. It is configured.

As shown in FIG. 2, the compressor (121) comprises a high-pressure dome-type swing compressor (121) whose operating capacity is variably adjusted. The compressor (121)
The compressor (121) structure (21
0) and the compressor motor (220) are housed, and are configured as a completely hermetic type.

The refrigerant pipe (140) on the suction side is connected to the side of the housing (200), while the housing (2)
In the upper part of (00), a refrigerant pipe (140) on the discharge side is introduced.

The compressor (121) structure (210) comprises a cylinder (211), a front head (212) and a rear head (213).
And a piston (214), and are arranged at a lower part of the housing (200). The cylinder (211) is formed in a cylindrical shape, and a front head (211) is provided at an upper end of the cylinder (211).
12), a rear head (213) is provided at the lower end. A compression chamber (215) is formed inside the cylinder (211) by the piston (214).

The compressor motor (220) includes an electromagnet stator (221) and a permanent magnet (222) as a rotor, and the stator (221) is fixed to an upper portion of the housing (200). A drive shaft (230) is connected to the permanent magnet (222).

The drive shaft (230) extends through the cylinder (211). A large-diameter eccentric shaft portion (231) is formed below the drive shaft (230) so as to be located inside the cylinder (211). The eccentric shaft (231) has a piston (214)
Is fitted.

Although not shown, the piston (214) is formed integrally with a blade. The blade is inserted into the cylinder (211) via a bush. Then, the piston (214) swings around the bush,
The refrigerant is compressed by reducing the volume of the compression chamber (215).

On the other hand, the refrigerant circuit (110) is provided with a first temperature sensor (Th1) to a fifth temperature sensor (Th5). The first temperature sensor (Th1) is provided in the refrigerant pipe (140) on the discharge side of the compressor (121), and detects a discharge temperature that is the temperature of the refrigerant discharged from the compressor (121).

The second temperature sensor (Th2) is provided in the outdoor heat exchanger (123), and detects a condensing temperature or an evaporation temperature, which is a refrigerant temperature in the outdoor heat exchanger (123).

The third temperature sensor (Th3) is provided in the refrigerant pipe (140) on the refrigerant outlet side during the heating operation in which the outdoor heat exchanger (123) serves as an evaporator, and is connected to the outdoor heat exchanger (123). The gas temperature at the outlet side of is detected.

The fourth temperature sensor (Th4) is provided in the indoor heat exchanger (131), and detects an evaporation temperature or a condensation temperature, which is a refrigerant temperature in the indoor heat exchanger (131).

The fifth temperature sensor (Th5) is provided in the refrigerant pipe (140) on the refrigerant outlet side during the cooling operation in which the indoor heat exchanger (131) becomes an evaporator, and the indoor heat exchanger (131) The gas temperature at the outlet side of is detected.

The detection signals of the first to fifth temperature sensors (Th1) to (Th5) are input to the controller (300).

As a feature of the present invention, the refrigerant circuit (11
0) is filled with, for example, a refrigerant of R32 alone which is an HFC refrigerant. Further, the compressor motor (220) of the compressor (121) is constituted by a brushless DC motor, and is configured to be driven by reluctance torque. Further, the permanent magnet (222) of the compressor motor (220) is composed of a rare earth magnet, and the rare earth magnet has a J coercive force (Hcj) of 23 kOe (183 kA).
/ M) or more.

The controller (300) constitutes control means for controlling the opening of the electric expansion valve (Z) so that the discharge temperature of the compressor (121) becomes a predetermined temperature under predetermined operating conditions. ing.

The controller (300) includes a compressor (121)
Electric expansion valve (Z) based on at least one detected temperature among the discharge temperature of the refrigerant, the evaporation temperature of the refrigerant, and the condensation temperature of the refrigerant.
Control the opening degree. For example, the above controller (300)
When the discharge temperature of the compressor (121) is below the limit value,
The opening degree of the electric expansion valve (Z) is controlled so that the refrigerant superheat degree on the evaporation side or the suction superheat degree of the compressor (121) becomes a predetermined temperature, while the discharge temperature of the compressor (121) exceeds the limit value. And the opening degree of the electric expansion valve (Z) is controlled based on the discharge temperature of the compressor (121). This limit value is, for example, 12
It is determined within the range of 0 ° C to 140 ° C.

Specifically, during the cooling operation, the evaporation temperature detected by the fourth temperature sensor (Th4) and the fifth temperature sensor (Th5)
Controls the degree of opening of the electric expansion valve (Z) based on the refrigerant superheat degree based on the gas temperature detected by the first temperature sensor and the discharge temperature detected by the first temperature sensor (Th1). Further, during the heating operation, the refrigerant superheat degree based on the evaporation temperature detected by the second temperature sensor (Th2) and the gas temperature detected by the third temperature sensor (Th3);
The opening degree of the electric expansion valve (Z) is controlled based on the discharge temperature detected by the first temperature sensor (Th1).

The gas temperature detected by the fifth temperature sensor (Th5) and the third temperature sensor (Th3) may be regarded as the suction gas temperature of the compressor (121). The suction superheat degree of the compressor (121) is derived from the Th4) and the fifth temperature sensor (Th5). During the heating operation, the suction of the compressor (121) is obtained from the second temperature sensor (Th2) and the third temperature sensor (Th3). The degree of superheat may be derived.

The controller (300) is provided with a PAM control unit (310) for pulse amplitude modulating the power supplied to the compressor motor (220). That is, the P
The AM control unit (310) controls the motor voltage according to the air conditioning load, and controls the rotation speed of the compressor motor (220).

The reason why the brushless DC motor is applied to the compressor motor (220) and the basic reason that the controller (300) controls the discharge temperature of the compressor (121) will be described.

R32, which is a refrigerant, has a characteristic that the theoretical COP and the heat transfer coefficient are relatively high and the pressure loss of the refrigerant is low, so that the energy efficiency is high. On the other hand, R32 is
The discharge temperature of the compressor (121) is almost 20 compared to R22 or the like.
There is a characteristic that the temperature is high by about ° C.

On the other hand, in order to prevent global warming, the demand for energy saving of air conditioners has been increasing. Then, considering the compressor motor (220), the compressor motor (220) includes an AC motor and a DC motor. Further, the DC motor includes a brushless DC motor. The brushless DC motor is more efficient than an AC motor. That is, in the AC motor, since an induced current flows inside the rotor, when the temperature of the rotor increases, the electric resistance increases, so that the loss increases and the motor efficiency decreases.

On the other hand, in the case of a DC motor, a permanent magnet such as ferrite or rare earth (including sintered magnets and bonded magnets of Nd-B-Fe and Sm-Co magnets) is used for the motor. For this reason, almost no induced current is generated in this permanent magnet portion, so that even if the motor temperature rises and the electric resistance of the permanent magnet portion rises, no loss occurs. Therefore, the DC motor is less likely to decrease in motor efficiency due to temperature rise.

Therefore, when a refrigerant having a high discharge temperature such as R32 is used, such a DC motor is suitable. In particular, rare-earth magnets have a small decrease in magnetic force with temperature rise. Therefore, a DC motor using a rare earth element as a magnet material is suitable for a refrigerant having a high discharge temperature.

Further, among the above DC motors, it is preferable to improve efficiency by utilizing reluctance torque. That is, while the torque of the permanent magnet decreases with an increase in temperature, the reluctance torque maintains a constant value regardless of the temperature increase. Therefore, when a refrigerant having a high discharge temperature such as R32 is used, a DC motor using reluctance torque is suitable.

As described above, with respect to the compressor motor (220), from the viewpoint of the motor efficiency, the following can be said for the refrigerant having a high discharge temperature such as R32. A DC motor is more suitable than an AC motor. Among DC motors, a motor using a rare earth magnet rather than a ferrite magnet is suitable. A motor using reluctance torque is superior to a motor using no reluctance torque.

Further, in the above-described DC motor, in the case of a ferrite magnet, if the temperature increases, the efficiency decreases. In the case of a rare earth magnet, it loses magnetic force in a high temperature region of 150 ° C. or more (demagnetization). Therefore, in the case of a rare earth magnet, its J coercive force (Hcj) is 23 kOe (183 kA).
/ M) or more is preferable because the high temperature limit for demagnetization can be further increased.

Accordingly, the present invention applies a brushless DC motor utilizing reluctance torque to the compressor motor (220), applies a rare earth magnet to the permanent magnet (222), and uses a rare earth magnet J The magnetic force (Hcj) is 23 kOe (183 kA / m) or more.

On the other hand, at a low outside air temperature, the compressor (12
When increasing the number of revolutions in 1) to increase the heating capacity, in the conventional R22, R410A and R407C, the pressure loss of the refrigerant from the evaporator and the outlet from the evaporator to the compressor inlet becomes large, which causes a decrease in efficiency. Becomes When the refrigerant is R32,
Since the pressure loss is very low, such a decrease in efficiency is small. Therefore, at a low outside air temperature, R32 has a characteristic that the capacity can be easily increased. At this time, in order to increase the heating capacity, the evaporation temperature is low, the condensation temperature is high, and the discharge temperature of the compressor (121) is high. For this reason, a refrigerant having a high discharge temperature such as R32 causes a decrease in motor efficiency or a demagnetization of a rare earth magnet. Therefore, in order to take advantage of the high efficiency characteristic at the time of the high heating capacity inherently possessed by the R32, the compressor (12
It is necessary to control the discharge temperature in 1).

Considering first the control of the brushless DC motor, the control of the brushless DC motor involves a PAM capable of increasing the torque in a high rotational speed range.
(Pulse Amplitude Modulation). This PA
The M method is characterized in that a booster circuit is provided in the converter section and the motor voltage is raised to a power supply voltage or higher in a high rotation speed range.
There are also effects of power factor improvement and harmonic reduction. Conventional PWM
In the (Pulse Width Modulation) method, since the motor voltage does not exceed the power supply voltage, the torque may be insufficient. In the PAM method, the motor voltage can be increased to the power supply voltage or more according to the rotation speed. For example, by increasing the rotation speed of the compressor (121) at a low outside air temperature, the heating capacity can be increased more than before. It can be aimed at.

From the above, according to the present invention, in order to control the compressor motor (220), the controller (300)
An M control unit (310) is provided. As described above, R32
Is also a refrigerant that can easily increase the heating capacity, and a greater effect can be expected by combining it with the PAM system.

Next, the heating capacity will be considered. Normal,
In commercial air conditioners, the ratio of the rated heating capacity / rated cooling capacity is set to around 1.15 to 1.2. In a home air conditioner, the ratio is set to about 1.4. In an air conditioner equipped with an R32 and a PAM-controlled brushless DC motor compressor (121), it is easy to make the ratio higher than the conventional ratio of rated heating capacity / rated cooling capacity.

In some cases, the low-temperature heating capacity is used as a method of expressing the heating capacity. This heating low-temperature capability refers to the heating capability in a state where the dry-bulb temperature of the outside air is 2 ° C. and the wet-bulb temperature is 1 ° C. (2DB / 1WB ° C.). In this case, the ratio of the low-temperature heating capacity / the standard heating capacity is about 0.92 for a commercial air conditioner and about 0.92 for a home air conditioner.
It is set to around 86. If the heating capacity is to be exerted above such a value, it is more important to take measures against the discharge temperature of the compressor (121) in R32.

The pressure reducing means of the refrigeration cycle will be considered. The pressure reducing means includes a capillary tube and an expansion valve. Further, the expansion valve includes a temperature-sensitive expansion valve that mechanically detects the degree of superheat at the outlet of the evaporator to control the flow rate of the refrigerant, the temperature or pressure of the evaporator or condenser, and the discharge temperature of the compressor (121). There is a motor-operated expansion valve that detects each of these and controls the opening degree by a microcomputer.

Regarding this pressure reducing means, the capillary tube cannot control the flow rate of the refrigerant. Further, the temperature-sensitive expansion valve can maintain the degree of superheat at the evaporator outlet at a certain value or more, but when the degree of superheat becomes zero, control becomes impossible. That is, the discharge temperature of the compressor (121) cannot be freely controlled with the above-mentioned capillary tube or temperature-sensitive expansion valve.

When a refrigerant having a high discharge temperature such as R32 is used, if the suction temperature of the compressor (121) increases, the temperature of the refrigerating machine oil increases, the viscosity of the refrigerating machine oil decreases, and the compressor (12)
1) The lubricity of the mechanical part decreases. Further, the deterioration of the refrigerating machine oil progresses, and sludge formation and acid generation occur. In particular, in the high-pressure dome type compressor (121) in which the compressor motor (220) is arranged in a high-pressure atmosphere, the temperature of the compressor motor (220) rises almost in proportion to the discharge temperature.
As described above, the motor efficiency is reduced. Therefore,
When the above-mentioned capillary tube or temperature-sensitive expansion valve is used, the reliability of the device and the motor efficiency are significantly reduced.

When the electric expansion valve (Z) is used, for example, since the discharge temperature is detected and the valve opening is controlled, it is possible to increase the valve opening when a certain discharge temperature is exceeded. . As a result, the discharge temperature can be lowered by sucking the wet refrigerant into the compressor (121).

Conventional R22, R407C and R410A
Such a control of the discharge temperature was possible even when such a refrigerant was used. However, in the case of a normal air conditioner, the discharge temperature does not often exceed 130 ° C. during a steady operation. In particular, when using a DC motor,
The reduction in motor efficiency was not a major problem.

However, when a refrigerant having a high discharge temperature such as R32 is used, the discharge temperature may exceed 150 ° C. depending on the operating conditions. In such a high temperature state, the efficiency of the DC motor is reduced, and the permanent magnet (222) is demagnetized, so that the operation becomes impossible. Therefore, in order to use a refrigerant having a high discharge temperature such as R32 while maintaining high efficiency and high reliability, the opening temperature of the electric expansion valve (Z) is controlled to control the discharge temperature of the compressor (121). There is a need.

As described above, the present invention relates to the compressor (12
If the discharge temperature of 1) is equal to or lower than the limit value, the opening degree of the electric expansion valve (Z) is controlled so that the refrigerant superheat degree on the evaporation side or the suction superheat degree of the compressor (121) becomes a predetermined temperature, When the discharge temperature of the compressor (121) exceeds the limit value, the compressor (121)
The opening degree of the electric expansion valve (Z) is controlled based on the discharge temperature of the motor.

In the present invention, the ratio between the rated heating capacity and the rated cooling capacity is set to 1.2 or more, or 1.4 or more. Alternatively, in the present invention, the ratio between the heating low-temperature capacity and the heating standard capacity is set to 0.92 or more, or 0.86 or more.

<Effects of Embodiment> As described above, according to the present embodiment, R32 is applied to the refrigerant, and the discharge temperature of the compressor (121) is controlled by the opening of the electric expansion valve (Z). For this reason, when the discharge temperature increases, the valve opening can be increased to increase the refrigerant flow rate and lower the discharge temperature.

As a result, it is possible to sufficiently exhibit the characteristic of R32 that the heating capacity is easily increased. In addition, the heating efficiency can be improved and the efficiency can be improved.

Particularly, in the case of the high-pressure dome type compressor (121), since the discharge temperature and the motor temperature are in a proportional relationship,
The above effects can be further expected.

Further, since a brushless DC motor is applied to the compressor motor (220), motor efficiency can be improved.

Further, since a rare earth magnet is used for the permanent magnet (222) of the brushless DC motor, the compressor (12
It is possible to cope with the rise in the discharge temperature of 1), and it is possible to further exhibit the characteristics of R32.

Further, since the reluctance torque is used in the brushless DC motor and the J coercive force (Hcj) of the rare earth magnet is set to 23 kOe (183 kA / m) or more, the characteristics of R32 can be more reliably exhibited. .

The brushless DC motor has a PAM
Since the control method is adopted, the heating capacity can be further improved while exhibiting the characteristics of R32.

[0083]

In another embodiment of the present invention,
Although 32 single refrigerants were used, the present invention provides a refrigerant circuit (11
0) In addition to R32 alone, 50% by weight of R32
R32 rich mixed refrigerant may be used.
It is also possible to use a mixed refrigerant which is a rich refrigerant and whose discharge temperature is higher than R22 by about 10 ° C.

The mixed refrigerant containing a large amount of R32 is, for example, R
32/125 (R32 is 70% or more), R32 / 134
a (R32 is 50% or more), R32 / propane (R32
Is 80% or more), R32 / butane (R32 is 80% or more) and R32 / isobutane (R32 is 80% or more).

Further, according to the present invention, the first temperature sensor (Th)
Only 1) may be provided to control the opening degree of the electric expansion valve (Z) and control the discharge temperature of the compressor (121) to a predetermined temperature.

Further, only the second temperature sensor (Th2) and the fourth temperature sensor (Th4) are provided, and only the condensation temperature of the refrigerant is detected, and the discharge temperature of the compressor (121) is estimated to determine the discharge temperature. The opening degree of the motor-operated expansion valve (Z) may be controlled so as to be a value, or only the evaporation temperature of the refrigerant is detected, and the discharge temperature of the compressor (121) is estimated to reduce the discharge temperature. The opening of the electric expansion valve (Z) may be controlled so as to be a predetermined value.

Further, a ferrite magnet may be used as the permanent magnet (222) in the brushless DC motor of the compressor motor (220). That is, the temperature rise is suppressed by controlling the electric expansion valve (Z).

The present invention also relates to a pair air conditioner shown in FIG.
In addition to multi air conditioners, refrigeration systems for binary refrigeration cycle (10
The present invention may be applied to various types of refrigerating devices (100), such as a refrigerating device (100) of a two-stage compression refrigerating cycle.

The present invention can be applied to various types of refrigerating devices such as freezers, in addition to cooling only devices and heating only devices.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a compressor provided in a refrigerant circuit.

[Explanation of symbols]

 Z Electric expansion valve X Drive motor 4 Permanent magnet 100 Refrigerator 110 Refrigerant circuit 121 Compressor 123 Outdoor heat exchanger (heat source side heat exchanger) 131 Indoor heat exchanger (use side heat exchanger) 220 Compressor motor 222 Permanent magnet 300 Controller (control means) 310 PAM controller

Claims (14)

[Claims] 1. A compressor (121) and a heat source side heat exchanger (123)
And a motor-operated expansion valve (Z) and a use-side heat exchanger (131), wherein R32 is a single R32 or R32-rich mixed refrigerant in which R32 exceeds 50 wt%, or R32-rich refrigerant and the discharge temperature is R
While a mixed refrigerant that is higher than about 10 ° C. with respect to 22 is used, the opening of the electric expansion valve (Z) is adjusted so that the discharge temperature of the compressor (121) becomes a predetermined temperature under predetermined operating conditions. A refrigeration apparatus comprising a control means (300) for controlling. 2. The control means (300) according to claim 1, wherein the control means (300) detects at least one of a discharge temperature of the compressor (121), an evaporation temperature of the refrigerant, and a condensation temperature of the refrigerant, and based on the detected temperature. A refrigeration system characterized by controlling the opening of an electric expansion valve (Z). 3. The refrigeration system according to claim 1, wherein the compressor (121) is a high-pressure dome compressor. 4. The refrigerant superheat degree on the evaporation side or the compressor (121) when the discharge temperature of the compressor (121) is equal to or lower than a limit value.
Electric expansion valve (Z) so that the suction superheat degree of the air reaches a predetermined temperature
Controlling the opening of the electric expansion valve (Z) based on the discharge temperature of the compressor (121) when the discharge temperature of the compressor (121) exceeds the limit value while controlling the opening of the compressor (121). Refrigeration equipment. 5. The refrigeration apparatus according to claim 1, wherein the compressor motor (220) of the compressor (121) is constituted by a DC motor. 6. The refrigeration apparatus according to claim 5, wherein the permanent magnet (222) of the compressor motor (220) is made of a ferrite magnet. 7. The refrigeration apparatus according to claim 5, wherein the permanent magnet (222) of the compressor motor (220) is made of a rare earth magnet. 8. The rare earth magnet according to claim 7, wherein the rare earth magnet has a J coercive force (Hcj) of 23 kOe.
(183 kA / m) or more. 9. The refrigeration apparatus according to claim 5, wherein the compressor motor (220) is configured to be driven by reluctance torque. 10. The refrigeration system according to claim 5, wherein the control means (300) includes a PAM control section (310) for pulse-amplitude-modulating the power supplied to the compressor motor (220). 11. The method according to claim 1, wherein the ratio between the rated heating capacity and the rated cooling capacity under the JIS standard conditions is 1.2 or more. A refrigeration apparatus characterized by being set. 12. The air conditioner according to claim 1, wherein the ratio between the rated heating capacity and the rated cooling capacity under JIS standard conditions is 1.4 or more. A refrigeration apparatus characterized by being set. 13. The heating device according to claim 1, wherein at least a heating operation is performed, and the dry-bulb temperature of the outside air is 2 ° C. and the wet-bulb temperature is 1 ° C. The ratio of low temperature capacity to heating standard capacity is 0.92
A refrigeration apparatus characterized by being set as described above. 14. The heating system according to claim 1, wherein at least a heating operation is performed, and the dry-bulb temperature of the outside air is 2 ° C. and the wet-bulb temperature is 1 ° C. The ratio of low temperature capacity to heating standard capacity is 0.86
A refrigeration apparatus characterized by being set as described above.