JP2014031916A - Refrigeration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration cycle capable of securing reliability of a compressor by suppressing the rise of a discharge temperature of the compressor at the time of an overload even when it comes into a state of an overload where the discharge temperature of the compressor surpasses a predetermined reference value because of the change in an environmental temperature and the like.SOLUTION: A refrigeration device has a configuration in which a capillary tube 3 and a control valve 4 which is connected in parallel to the capillary tube are used as a diaphragm device, and the control valve is driven by a shape memory alloy spring, and also a refrigeration cycle is configured by using a constant speed compressor 1. Thereby, the refrigeration device can be provided in which the rise in a discharge temperature of the compressor at the time of an overload can be suppressed with a low cost configuration without using an expensive diaphragm amount variable type electric expansion valve and a capacity variable compressor and the like, reliability of the compressor can be secured, and an operation with high cycle efficiency is possible at the time of a normal operation.

Description

  The present invention relates to a vapor compressor type refrigeration apparatus.

  Conventionally, when a refrigeration apparatus including an air conditioner is in an overload state in which the discharge temperature of the compressor exceeds a predetermined reference value due to a change in environmental temperature during operation, deterioration of the insulating material of the compressor Problems occur in terms of reliability, such as alteration of refrigeration oil. In order to solve this problem, the discharge temperature has been adjusted by using an electric expansion valve having a variable throttle amount and a variable capacity compressor as a throttle mechanism (see, for example, Patent Documents 1 and 2).

  For example, if an electric expansion valve with a variable throttle amount is used, the superheat of the compressor suction refrigerant and the discharge temperature of the compressor can be controlled, the refrigeration cycle can be operated in an optimum state, and the cycle efficiency is high. It is characterized by being able to drive.

  Further, by adopting a liquid bypass mechanism that introduces the liquid refrigerant before the throttling mechanism into the compressor suction port, it is possible to suppress an increase in discharge temperature and to ensure the reliability of the compressor.

  Against this background, recently, the adoption of HFC refrigerant as an alternative refrigerant for HCFC refrigerant has begun to be examined. This HFC-based refrigerant is effective in preventing global warming in addition to protecting the ozone layer. That is, it has a low GWP compared to conventional HCFC refrigerants (R410A, R407C, etc.). Therefore, the application of a mixed refrigerant containing R32 or R32, which is a kind of HFC-based refrigerant, is called out.

  When R32 is used in an air conditioner, the theoretical COP and heat transfer coefficient are higher than those of conventional refrigerants R22, R407C and R410A, and the pressure loss is small, so that the actual cycle efficiency is increased. . However, since the heat insulation index which is the thermophysical property of the refrigerant is larger than that of the conventional refrigerant, there is a characteristic that the discharge temperature of the compressor becomes higher by about 10 ° C. or more. In particular, the discharge temperature further increases during an overload condition where the outside air temperature is high.

Japanese Patent No. 3465654 No. 2-333110

  As described above, it is possible to prevent the discharge temperature from rising by using an electric expansion valve with variable throttle amount and variable capacity compressor. However, since the cost is greatly increased, the price is kept low in the global market. Therefore, a constant speed compressor and a capillary tube which is a fixed throttle are often used.

When such a constant speed compressor and a capillary tube with a fixed throttle are used, the superheat of the compressor suction refrigerant, the discharge temperature of the compressor, etc. are controlled under standard operating conditions and overload operating conditions. The refrigeration cycle cannot be adjusted to the optimum state for each condition. Therefore, when using a single R32 refrigerant or a mixed refrigerant containing R32 as a main component, if the flow rate of the capillary tube is set so as to be equal to or lower than the allowable discharge temperature during an overload operation, a standard operation is achieved as compared with a conventional refrigerant. Under the conditions, since the flow rate of the capillary tube is too large, the refrigeration cycle cannot be adjusted to the optimum state, and there is a problem that the refrigeration capacity and the cycle efficiency are lowered. In addition, the liquid bypass mechanism requires an electromagnetic valve that opens when the discharge temperature exceeds a certain level, and an electric circuit that operates the electromagnetic valve on the outdoor unit is required, which increases costs.

  The present invention has been made in view of the above points, and even when an overload state in which the discharge temperature of the compressor exceeds a predetermined reference value due to a change in the environmental temperature or the like, the overload is performed at low cost. It is an object of the present invention to provide a refrigeration apparatus that suppresses an increase in the discharge temperature of the compressor at the time to ensure the reliability of the compressor and can be operated with high cycle efficiency during standard operation.

  In order to achieve the above object, the present invention uses an R32 single refrigerant or a mixed refrigerant mainly composed of R32 as a refrigerant, and a refrigeration cycle in which a constant speed compressor, a condenser, a throttling device, and an evaporator are connected in an annular shape. The throttle device includes a capillary tube and a control valve arranged in parallel with the capillary tube, and the control valve is controlled by a shape memory alloy spring, or the throttle device is a capillary tube. The control valve includes a control valve connected in series with the capillary tube, and the control valve includes a flow path controlled by a shape memory alloy spring and a normally open flow path in parallel. is there.

  As a result, even when the discharge temperature of the compressor exceeds a predetermined reference value due to changes in the environmental temperature, etc., the expensive variable throttle amount type electric expansion valve, variable capacity compressor, etc. It is possible to suppress an increase in the discharge temperature of the compressor only by using a control valve driven by a capillary tube and a shape memory alloy spring without using it.

  According to the present invention, even when the discharge temperature of the compressor exceeds a predetermined reference value due to a change in environmental temperature or the like, an increase in the discharge temperature of the compressor is suppressed at a low cost. Compressor reliability is ensured, and cycle-efficient operation is possible during standard operation.

Refrigeration cycle diagram of an air conditioner to which the refrigeration apparatus according to Embodiment 1 of the present invention is applied. Cross section of control valve used in the air conditioner Temperature-strain curve (hysteresis curve) diagram of the shape memory alloy spring used for the control valve Sectional drawing explaining operation | movement of the control valve Refrigeration cycle diagram of an air conditioner to which the refrigeration apparatus in Embodiment 2 of the present invention is applied. Sectional drawing of the 2nd control valve used for the air conditioner Sectional drawing explaining operation | movement of the said 2nd control valve

  A first aspect of the present invention is a refrigeration cycle comprising a constant speed compressor, a condenser, a throttle device, and an evaporator connected in an annular shape using R32 or a mixed refrigerant mainly composed of R32 as a refrigerant. The apparatus is constituted by a capillary tube and a control valve arranged in parallel with the capillary tube, and the control valve is controlled by a shape memory alloy spring.

As a result, the compressor at the time of overload can be constructed at a low cost by using only a control valve driven by a capillary tube and a shape memory alloy spring without using an expensive variable expansion amount type electric expansion valve, variable capacity compressor, etc. Thus, it is possible to provide a refrigeration apparatus that can suppress the increase in the discharge temperature, ensure the reliability of the compressor, and can operate with high cycle efficiency during standard operation.

  A second invention is a refrigeration cycle comprising a constant speed compressor, a condenser, a throttling device, and an evaporator connected in an annular shape using R32 or a mixed refrigerant mainly composed of R32 as a refrigerant, wherein the throttling The apparatus is composed of a capillary tube and a control valve connected in series with the capillary tube, and the control valve includes a flow path controlled by a shape memory alloy spring and a normally open flow path in parallel. It is a configuration.

  As a result, as in the first aspect of the present invention, the cost can be reduced simply by using a control valve driven by a capillary tube and a shape memory alloy spring without using an expensive variable expansion amount electric expansion valve, variable capacity compressor, or the like. With this configuration, it is possible to provide a refrigeration apparatus that can suppress an increase in the discharge temperature of the compressor during an overload, ensure the reliability of the compressor, and can operate with high cycle efficiency during standard operation.

  According to a third invention, in the first and second inventions, the mixed refrigerant containing R32 as a main component is a mixed refrigerant of R32 and HFO1234yf.

  As a result, even when a mixed refrigerant of R32 and HFO1234yf is used, an increase in the discharge temperature of the compressor at the time of overload can be suppressed at a low cost, ensuring the reliability of the compressor, and the cycle efficiency during standard operation In addition, it is possible to provide a refrigeration apparatus that can be operated at a high level, can further reduce the warming coefficient of the refrigerant, has high cycle efficiency, and can reduce the effects of warming.

  According to a fourth invention, in the first and second inventions, the mixed refrigerant containing R32 as a main component is a mixed refrigerant of R32 and HFO1234ze.

  Thus, as in the third aspect of the invention, even when a mixed refrigerant of R32 and HFO1234ze is used, an increase in the discharge temperature of the compressor at the time of overload can be suppressed at low cost, ensuring the reliability of the compressor, and the standard It is possible to provide a refrigeration apparatus that can be operated with high cycle efficiency during a typical operation, can further reduce the warming coefficient of the refrigerant, has high cycle efficiency, and can reduce the influence of warming.

  The refrigeration apparatus of the present invention will be described below. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
In this embodiment, a case where the refrigeration apparatus of the present invention is applied to an air conditioner will be described as an example.

  FIG. 1 is a refrigeration cycle diagram of an air conditioner according to an embodiment of the present invention.

  The air conditioner of the present invention uses an R32 single refrigerant or a mixed refrigerant mainly composed of R32, and the mixed refrigerant is a mixed refrigerant of R32 and HFO1234yf or a mixed refrigerant of R32 and HFO1234ze. Therefore, although effective in preventing global warming, there is a problem that the discharge temperature becomes higher than that of the conventional refrigerant when the outside air temperature condition is overloaded. This problem is solved by the configuration described below.

  That is, the air conditioner in the present embodiment includes a constant speed compressor 1 that compresses refrigerant, an outdoor heat exchanger 2 that serves as a condenser and exchanges heat of the refrigerant and outside air, and an outdoor heat exchanger 2 in the outdoor unit side. The outdoor fan 6 that promotes heat exchange between the refrigerant flowing through the outside air and the throttle device that solves the problem of an increase in the discharge temperature of the refrigerant.

  This throttling device is connected to the capillary tube 3 in parallel with the capillary tube 3 and is closed during cooling operation at a normal outdoor temperature (for example, 40 ° C. or less) and closed during cooling operation at a high outdoor temperature. It consists of

  On the other hand, the indoor unit is provided with an indoor heat exchanger 5 that serves as an evaporator and exchanges heat between the refrigerant and room air, and an indoor fan 7 that promotes heat exchange between the refrigerant flowing in the indoor heat exchanger 5 and room air. Yes.

  The outdoor unit 8 is installed outdoors and the indoor unit 9 is installed indoors. The outdoor unit 8 and the indoor unit 9 are connected by a liquid side connection pipe 21 and a gas side connection pipe 22.

  FIG. 2 is a cross-sectional view of the control valve 4 constituting the throttle device. In FIG. 2, 10 is a valve body, 11 is a valve seat, 12 is a bias spring, 13 is a shape memory alloy spring, and 14 is a first flow path.

  FIG. 3 is a temperature-strain curve (hysteresis curve) of the shape memory alloy spring 13. There is a temperature difference between the operating temperature at the time of heating and cooling, that is, temperature hysteresis, and the shape memory alloy spring 13 has a transformation temperature T2 at the time of cooling (for example, −50 ° C.) to the transformation temperature T1 at the time of heating (for example, −50 ° C.) It is adjusted to.

  In the above configuration, the operation of the control valve 4 will be described.

  When the shape memory alloy spring 13 becomes equal to or higher than the set transformation temperature T1, it extends as shown in FIG. 2, pushes the valve body 10 against the spring force of the bias spring 12, and the first flow path 14 is opened. The refrigerant flows through the first flow path 14, and the refrigerant flowing through the capillary tube 3 decreases. On the other hand, when the shape memory alloy spring 13 becomes lower than the set transformation temperature T2, as shown in FIG. 4, the bias spring 12 pushes the valve body 10 against the valve seat 11, and the first flow path 14 is closed. Therefore, the refrigerant can only flow through the capillary tube 3.

  The operation of the air conditioner using such a control valve 4 will be described.

  During the cooling operation when the control valve 4 is not operating, the refrigerant compressed by the constant speed compressor 1 becomes a high-temperature and high-pressure refrigerant, flows into the outdoor heat exchanger 2, and promotes heat exchange with the outside air by the outdoor fan 6. Then, the heat is dissipated to form a high-pressure liquid refrigerant, which is sent to the capillary tube 3. At this time, the control valve 4 is closed.

  Therefore, the liquid refrigerant passes through the capillary tube 3, where the liquid refrigerant is decompressed to become a low-temperature and low-pressure two-phase refrigerant, and is sent to the indoor heat exchanger 5 through the liquid side connection pipe 21.

  The low-temperature and low-pressure two-phase refrigerant sent to the indoor heat exchanger 5 exchanges heat with the indoor air sucked by the indoor fan 7, and the refrigerant absorbs the heat of the indoor air and evaporates and becomes a low-temperature gas refrigerant. On the other hand, the indoor air absorbed by the refrigerant is lowered in temperature and humidity and blown out into the room by the indoor fan 7 to cool the room. Further, the gas refrigerant passes through the gas side connecting pipe 22 and returns to the constant speed compressor 1.

  Here, during the cooling operation, when the outdoor air temperature is high and the temperature of the refrigerant flowing through the control valve 4 is higher than the set transformation temperature T2, the shape memory alloy spring 13 of the control valve 4 resists the spring force of the bias spring 12. Since the valve body 10 is pushed and the bias spring 12 is compressed, the first flow path 14 is opened and the refrigerant flowing through the capillary tube 3 decreases, but the refrigerant flow path is the first flow path 14 and the capillary tube 3. Therefore, the pressure reduction in the expansion device decreases, and the discharge temperature decreases.

  On the other hand, when the outdoor air temperature decreases and the temperature of the refrigerant flowing through the control valve 4 becomes lower than the set transformation temperature T2 of the shape memory alloy spring 13, the shape memory alloy spring 13 is pushed by the bias spring 12 as shown in FIG. The body 10 is pressed against the valve seat 11, and the first flow path 14 is closed. Therefore, the refrigerant can only flow through the capillary tube 3, the pressure difference before and after the expansion device becomes large, an optimum refrigeration cycle is realized, and the cycle efficiency is improved.

  Thus, when the outdoor air temperature is very high and the compressor discharge temperature becomes high, the refrigerant flow rate of the throttle device increases, the discharge temperature is reduced, and when the outdoor temperature is normal temperature, the normal throttle device Therefore, the cooling operation with high cycle efficiency is possible.

  Such operation can be realized only by using the control valve 4 driven by the capillary tube 3 and the shape memory alloy spring 13, and the newly added control valve 4 is driven by the shape memory alloy spring 13. Therefore, it is cheaper than a conventional variable expansion amount type electric expansion valve, and can be realized at low cost.

(Embodiment 2)
FIG. 5 is a refrigeration cycle diagram of the refrigeration apparatus in Embodiment 2 of the present invention.

  In the second embodiment, the throttling device is composed of a capillary tube 3 and a second control valve 19 in which the capillary tube 3 is connected in series, and the second control valve 19 is described below. It differs from the said Embodiment 1 by a point with such a structure. Other points are the same as those of the first embodiment, and the same parts are denoted by the same reference numerals and the description thereof is omitted.

  FIG. 6 is a sectional view showing the second control valve 19, wherein 10 is a valve body, 11 is a valve seat, 12 is a bias spring, 13 is a shape memory alloy spring, 14 is a first flow path, and 20 is a valve body. 10 is a normally open second flow path, which is in parallel with the first flow path 14.

  The temperature-strain curve (hysteresis curve) of the shape memory alloy spring 13 of the second control valve 19 is the same as that of the second embodiment of FIG.

  In the above configuration, the operation of the second control valve 19 will be described.

  When the shape memory alloy spring 13 becomes equal to or higher than the set transformation temperature T1, it expands as shown in FIG. 6, pushes the valve body 10 against the spring force of the bias spring 12, and the first flow path 14 is opened. The refrigerant flows through the first flow path 14 and the normally open second flow path 20.

  On the other hand, when the shape memory alloy spring 13 becomes lower than the set transformation temperature T2, as shown in FIG. 7, it is pushed by the bias spring 12, the valve body 10 hits the valve seat 11, and the first flow path 14 is closed. Therefore, the refrigerant can only flow through the second flow path 20, and the flow path is narrowed, so the pressure is reduced.

  Next, the operation at the time of operation of the refrigeration apparatus provided with such a second control valve 19 will be described.

  During the cooling operation, when the outdoor air temperature is high and the temperature of the refrigerant flowing through the second control valve 19 is higher than the set transformation temperature T2, the shape memory alloy spring 13 resists the spring force of the bias spring 12 as shown in FIG. As a result, the valve body 10 is pushed and the bias spring 12 is compressed, so that the first flow path 14 is opened. Therefore, the refrigerant is not decompressed by the second control valve 19, and there is no difference in refrigerant temperature before and after the second control valve 19.

  However, when the outdoor air temperature decreases and the temperature of the refrigerant flowing through the second control valve 19 becomes lower than the set transformation temperature T2 of the shape memory alloy spring 13, the shape memory alloy spring 13 pushes against the bias spring 12 as shown in FIG. The valve body 10 is pressed against the valve seat 11 and the first flow path 14 is closed. Therefore, the refrigerant can only flow through the second flow path 20, and the flow path is narrowed, so that a pressure difference occurs between the front and rear of the second control valve 19.

  In addition, when the outdoor temperature rises while the second control valve 19 is operating, the refrigerant temperature of the second control valve 19 becomes higher than the set transformation temperature T1 of the shape memory alloy spring 13, and the like. 6, the shape memory alloy spring 13 is transformed and stretched, the bias spring 12 is compressed, the valve body 10 is separated from the valve seat 11, and the first flow path 14 is opened. As a result, since the refrigerant is not depressurized, there is no difference in refrigerant temperature before and after the second control valve 19.

  As described above, by using the second control valve 19 having the pressure reducing mechanism, an overload state is achieved in which the discharge temperature of the constant speed compressor 1 exceeds a predetermined reference value due to a change in the environmental temperature at a low cost. Even in this case, an increase in the discharge temperature of the compressor can be suppressed to ensure the reliability of the constant speed compressor 1, and an operation with high cycle efficiency is possible.

  Further, the second control valve 19 is driven by the shape memory alloy spring 13 like the control valve of the first embodiment, so that it is cheaper and lower in cost than the conventional variable expansion amount type electric expansion valve. can do.

  The present invention suppresses an increase in the discharge temperature of the compressor at a low cost even when the discharge temperature of the compressor exceeds a predetermined reference value due to a change in the environmental temperature or the like, thereby suppressing the increase in the discharge temperature of the compressor. This ensures high cycle efficiency during standard operation, and can be applied to a wide range of refrigeration equipment for industrial use as well as general use.

DESCRIPTION OF SYMBOLS 1 Constant speed compressor 2 Outdoor heat exchanger 3 Capillary tube 4 Control valve 5 Indoor heat exchanger 10 Valve body 13 Shape memory alloy spring 14 1st flow path 19 2nd control valve 20 2nd flow path of a normally open type

Claims (4)

A refrigeration cycle in which a constant-speed compressor, a condenser, a throttling device, and an evaporator are connected in a ring shape using a single R32 refrigerant or a mixed refrigerant containing R32 as a main component as a refrigerant, the throttling device being a capillary A refrigeration apparatus comprising a tube and a control valve arranged in parallel with the capillary tube, wherein the control valve is controlled by a shape memory alloy spring. A refrigeration cycle in which a constant-speed compressor, a condenser, a throttling device, and an evaporator are connected in a ring shape using a single R32 refrigerant or a mixed refrigerant containing R32 as a main component as a refrigerant, the throttling device being a capillary A tube and a control valve connected in series with the capillary tube, and the control valve includes a flow channel that is controlled to open and close by a shape memory alloy spring and a normally open flow channel in parallel. A refrigeration apparatus characterized by that. The refrigeration apparatus according to claim 1 or 2, wherein the mixed refrigerant containing R32 as a main component is a mixed refrigerant of R32 and HFO1234yf. The refrigeration apparatus according to claim 1 or 2, wherein the mixed refrigerant containing R32 as a main component is a mixed refrigerant of R32 and HFO1234ze.

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