JP6467011B2 - air conditioner - Google Patents

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner in which the valve opening of an expansion valve is increased or decreased.

  When the outside air temperature is high, the required cooling capacity in the cooling operation of the air conditioner increases, so it is required to increase the flow rate of refrigerant circulating through the air conditioner. On the other hand, when the outside air temperature is low, the required cooling capacity in the cooling operation of the air conditioner decreases, so that it is required to reduce the flow rate of the refrigerant circulating in the air conditioner. That is, in the cooling operation of the air conditioner, it is required to appropriately adjust the refrigerant flow rate circulating through the air conditioner in accordance with the outside air temperature.

  Conventionally, an air conditioner capable of adjusting the opening degree of the expansion valve has been proposed. For example, Japanese Patent Laid-Open No. 56-151858 (Patent Document 1) discloses a supercooling control device for a refrigerator as an expansion valve capable of adjusting a valve opening degree as a conventional technique. In this refrigerator subcooling control device, the refrigerant temperature at the outlet of the condenser is detected as a thermal change by a temperature sensing cylinder attached to the outlet pipe. This thermal change is converted into a change in pressure of the heated medium enclosed in the temperature sensitive cylinder. Due to the pressure change, the diaphragm is displaced, so that the valve body connected to the diaphragm is displaced. The gap between the valve body and the valve seat is adjusted by the displacement of the valve body. As a result, the throttle amount of the valve is adjusted.

JP-A-56-151858

  However, in the subcooling control device for a refrigerator described in the above publication, the throttle amount of the valve is adjusted so as to keep the degree of supercooling constant. Therefore, the throttle amount of the valve increases when the refrigerant temperature at the outlet of the condenser is high, and the throttle amount of the valve decreases when the refrigerant temperature at the outlet of the condenser is low. Since the outside air temperature and the condensation temperature are proportional, the subcooling control device for a refrigerator cannot increase the refrigerant flow rate when the outside air temperature is high, and can also decrease the refrigerant flow rate when the outside air temperature is low. Can not.

  The present invention has been made in view of the above problems, and an object of the present invention is to increase the amount of refrigerant circulating in the air conditioner when the outside air temperature is high and to circulate the air conditioner when the outside air temperature is low. It is to provide an air conditioner capable of reducing the amount.

The air conditioner of the present invention includes a compressor, a condenser, an expansion valve, an evaporator, and a temperature detection unit. The compressor can compress the refrigerant and variably control the rotation speed. The condenser condenses the refrigerant compressed by the compressor. The expansion valve depressurizes the refrigerant condensed by the condenser. The evaporator evaporates the refrigerant decompressed by the expansion valve. The temperature detector detects the temperature of the refrigerant. The expansion valve has a case, a diaphragm, a valve body connected to the diaphragm, and a valve seat attached to the case. The case has a first chamber and a second chamber partitioned by a diaphragm. The first chamber is configured to allow the refrigerant enclosed in the temperature detection unit to enter and exit. The second chamber houses the valve body and the valve seat, and is configured so that the refrigerant condensed by the condenser flows in. The diaphragm is configured to be deformable by a differential pressure between the internal pressure of the temperature detection unit, which is the pressure in the first chamber, and the pressure of the refrigerant condensed in the condenser, which is the pressure in the second chamber. The expansion valve is a temperature type expansion valve that can adjust the flow rate of the refrigerant passing through the expansion valve by adjusting the valve opening degree of the expansion valve by moving the valve body by deformation of the diaphragm . The temperature detection unit is a temperature sensitive cylinder. The temperature sensitive cylinder is accommodated in the outdoor unit. When the temperature of the refrigerant detected by the temperature detector rises, the valve opening of the expansion valve increases. When the temperature of the refrigerant detected by the temperature detector decreases, the valve opening of the expansion valve decreases. The expansion valve includes a first flow path and a second flow path having a smaller flow rate than the first flow path. The expansion valve is switched to the first flow path when the temperature of the refrigerant detected by the temperature detection unit increases, and is switched to the second flow path when the temperature of the refrigerant detected by the temperature detection unit decreases.

  According to the air conditioner of the present invention, the temperature detection unit detects the temperature of the refrigerant in the condenser. And if the temperature of the refrigerant | coolant detected by the temperature detection part rises, the valve opening degree of an expansion valve will increase, and if the temperature of the refrigerant | coolant detected by the temperature detection part falls, the valve opening degree of an expansion valve will decrease. The temperature of the refrigerant in the condenser is proportional to the outside air temperature. Therefore, when the outside air temperature is high, the temperature of the refrigerant detected by the temperature detection unit increases, and when the outside air temperature is low, the temperature of the refrigerant detected by the temperature detection unit decreases. For this reason, when the outside air temperature is high, the valve opening degree of the expansion valve can be increased, and when the outside air temperature is low, the valve opening degree of the expansion valve can be reduced. Accordingly, the amount of refrigerant circulating through the air conditioner can be increased when the outside air temperature is high, and the flow rate of refrigerant circulating through the air conditioner can be decreased when the outside air temperature is low.

It is a figure which shows roughly the structure of the refrigerating cycle of the air conditioner in Embodiment 1 of this invention. It is sectional drawing which shows schematically the structure of the expansion valve of the air conditioner in Embodiment 1 of this invention. It is sectional drawing for demonstrating operation | movement of the expansion valve of the air conditioner in Embodiment 1 of this invention. It is a figure which shows the relationship between a cooling load and external temperature. It is a figure which shows the relationship between a required refrigerant | coolant flow volume and external temperature. It is a figure which shows the relationship between required Cv value and external temperature. It is a figure which shows the relationship between Cv value of an expansion valve in Embodiment 1 of this invention, and external temperature. It is sectional drawing which shows schematically the structure of the expansion valve of the air conditioner in Embodiment 2 of this invention. It is an enlarged view which shows the P section of FIG. 8, and is sectional drawing for demonstrating a 1st flow path. It is an enlarged view which shows the P section of FIG. 8, and is sectional drawing for demonstrating a 2nd flow path. It is sectional drawing for demonstrating the state which a refrigerant | coolant flows through the 3rd hole of the expansion valve in the modification of Embodiment 2 of this invention. It is sectional drawing for demonstrating the state which a refrigerant | coolant flows through the 3rd hole and 4th hole of an expansion valve in the modification of Embodiment 2 of this invention. It is a figure which shows roughly the structure of the refrigerating cycle of the air conditioner in Embodiment 3 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a structural diagram of a refrigeration cycle of an air conditioner according to Embodiment 1 of the present invention. First, with reference to FIG. 1, the structure of the air conditioner 10 in Embodiment 1 of this invention is demonstrated.

  The air conditioner 10 of the present embodiment includes a compressor 1, a condenser 2, an expansion valve 3, an evaporator 4, a condenser blower 5, an evaporator blower 6, a temperature detection unit 7, and a pipe 8. And the pipes PI1 to PI4. The compressor 1, the condenser 2, the expansion valve 3, the condenser blower 5, the temperature detection unit 7, and the pipe 8 are accommodated in the outdoor unit 11. The evaporator 4 and the evaporator fan 6 are accommodated in the indoor unit 12.

  A compressor 1, a condenser 2, an expansion valve 3, and an evaporator 4 are communicated with each other via pipes PI <b> 1 to PI <b> 4 to constitute a refrigeration cycle. Specifically, the compressor 1 and the condenser 2 are connected to each other by a pipe PI1. The condenser 2 and the expansion valve 3 are connected to each other by a pipe PI2. The expansion valve 3 and the evaporator 4 are connected to each other by a pipe PI3. The evaporator 4 and the compressor 1 are connected to each other by a pipe PI4. The refrigeration cycle is configured such that the refrigerant circulates in the order of the compressor 1, the pipe PI1, the condenser 2, the pipe PI2, the expansion valve 3, the pipe PI3, the evaporator 4, and the pipe PI4. For example, R410a, R32, R1234yf, or the like can be used as the refrigerant.

  The compressor 1 is configured to compress the refrigerant. The compressor 1 is configured to compress and discharge the sucked refrigerant. The compressor 1 has a variable capacity. The compressor 1 of the present embodiment is configured to be able to variably control the rotational speed. Specifically, the compressor 1 adjusts the rotation speed of the compressor 1 by changing the drive frequency based on an instruction from a control device (not shown). Thereby, the capacity | capacitance of the compressor 1 changes. The capacity of the compressor 1 is an amount for sending out refrigerant per unit time. That is, the compressor 1 can perform high capacity operation and low capacity operation. In the high capacity operation, the operation is performed by increasing the flow rate of the refrigerant circulating in the refrigerant circuit by increasing the drive frequency of the compressor 1. In the low capacity operation, the operation is performed by reducing the flow rate of the refrigerant circulating in the refrigerant circuit by lowering the driving frequency of the compressor 1.

  The condenser 2 is configured to condense the refrigerant compressed by the compressor 1. The condenser 2 is an air heat exchanger composed of pipes and fins. The expansion valve 3 is configured to depressurize the refrigerant condensed by the condenser 2. The expansion valve 3 is configured such that the flow rate of the refrigerant passing through the expansion valve 3 can be adjusted by adjusting the valve opening degree of the expansion valve 3. The flow rate of the refrigerant passing through the expansion valve 3 is a flow rate per unit time. The evaporator 4 is configured to evaporate the refrigerant decompressed by the expansion valve 3. The evaporator 4 is an air heat exchanger composed of pipes and fins.

  The condenser blower 5 is configured to adjust the amount of heat exchange between the outdoor air and the refrigerant in the condenser 2. The condenser blower 5 includes a fan 5a and a motor 5b. The motor 5b may be configured to rotate the fan 5a with a variable number of rotations. The motor 5b may be configured to rotate the fan 5a at a constant rotation speed. The evaporator blower 6 is configured to adjust the amount of heat exchange between the indoor air and the refrigerant in the evaporator 4. The evaporator blower 6 includes a fan 6a and a motor 6b. The motor 6b may be configured to rotate the fan 6a in a variable number of rotations. The motor 6b may be configured to rotate the fan 6a at a constant rotation speed.

  The temperature detector 7 is attached to the condenser 2. The temperature detection unit 7 is configured to detect the temperature of the refrigerant in the condenser 2. The temperature detector 7 is connected to the expansion valve 3 via a pipe 8. When the temperature of the refrigerant detected by the temperature detector 7 increases, the valve opening of the expansion valve 3 increases. When the temperature of the refrigerant detected by the temperature detector 7 decreases, the valve opening of the expansion valve 3 decreases. The temperature detector 7 detects the temperature of the refrigerant in a state before the refrigerant is condensed and liquefied in the condenser 2. The temperature detector 7 is provided at a location where the condenser 2 can detect the condensation temperature of the refrigerant. Therefore, the temperature detector 7 may be provided at the inlet portion of the condenser 2 or at an intermediate portion between the inlet and the outlet of the condenser 2.

  With reference to FIG. 1 and FIG. 2, the structure of the specific example of the expansion valve 3 and the temperature detection part 7 in this Embodiment is demonstrated in detail.

  The expansion valve 3 is a temperature type expansion valve. The expansion valve 3, which is a temperature type expansion valve, is configured such that the valve opening degree is adjusted according to the temperature change of the refrigerant in the condenser 2. The temperature detection unit 7 is a temperature sensitive cylinder. A refrigerant having properties similar to those of the refrigerant used in the refrigerant cycle is sealed in the temperature detector 7 which is a temperature sensitive cylinder.

  The expansion valve 3 includes a case 31, a diaphragm 32, a valve body 33, a valve seat 34, and a spring 35. A diaphragm 32 is attached to the inside of the case 31 so as to partition the inside of the case 31. The case 31 has a first chamber S1 and a second chamber S2 partitioned by a diaphragm 32.

  A tube 8 is inserted into the first chamber S1. The first chamber S <b> 1 is configured to allow the refrigerant enclosed in the temperature detection unit 7, which is a temperature sensitive cylinder, to enter and exit via the pipe 8. That is, the refrigerant sealed in the temperature detector 7 which is a temperature sensitive cylinder enters and exits the first chamber S1 through the pipe 8 as indicated by a double arrow A1 in FIG.

  A valve body 33, a valve seat 34, and a spring 35 are accommodated in the second chamber S2. The second chamber S2 has an inflow portion 31a and an outflow portion 31b. The inflow portion 31a is connected to the pipe PI2. The outflow part 31b is connected to the pipe PI3. The second chamber S2 is configured such that the refrigerant flowing through the refrigeration cycle flows from the pipe PI2 through the inflow portion 31a into the second chamber S2, and flows out through the outflow portion 31b to the pipe PI3. That is, as indicated by an arrow A2 in FIG. 2, the refrigerant flowing through the refrigeration cycle flows into the second chamber S2 from the inflow portion 31a and out of the outflow portion 31b.

  The pressure in the first chamber S1 is the pressure of the refrigerant sealed in the temperature detector 7 that is a temperature sensitive cylinder. The pressure in the second chamber S2 becomes the pressure of the refrigerant flowing through the refrigeration cycle. The diaphragm 32 is configured to be deformable by a differential pressure between the pressure in the first chamber S1 and the pressure in the second chamber S2.

  The valve body 33 has a first end E1, a second end E2, a shaft portion 33a, and a tapered portion 33b. The first end E1 is connected to the diaphragm 32. The second end E2 is connected to the spring 35. A shaft portion 33 a and a taper portion 33 b extend in the axial direction of the valve body 33. The axial direction of the valve body 33 is a direction in which the first end E1 and the second end E2 face each other as indicated by an arrow A3 in FIG.

  The shaft portion 33a has a first end E1. The tapered portion 33b has a second end E2. The shaft portion 33a is connected to the taper portion 33b on the opposite side of the first end E1 in the axial direction A3. The tapered portion 33b is configured such that the cross-sectional area continuously increases from the shaft portion 33a toward the second end E2. The valve body 33 is configured to move in the axial direction A <b> 3 by the deformation of the diaphragm 32.

  A gap is provided between the tapered portion 33 b of the valve body 33 and the valve seat 34. The expansion valve 3 is configured such that the size of the gap between the taper portion 33b and the valve seat 34 continuously changes as the valve element 33 moves in the axial direction A3 due to the deformation of the diaphragm 32. . That is, the expansion valve 3 is configured such that the throttle amount of the expansion valve 3 changes in proportion to the amount of movement of the valve body 33 in the axial direction A3.

  Specifically, the expansion valve 3 is configured such that when the valve element 33 moves toward the first end E1 in the axial direction A3, the gap between the tapered portion 33b and the valve seat 34 becomes small. That is, the expansion valve 3 is configured such that when the valve element 33 moves toward the first end E1 in the axial direction A3, the throttle amount of the expansion valve 3 increases. On the other hand, the expansion valve 3 is configured such that when the valve element 33 moves to the second end E2 side in the axial direction A3, the gap between the tapered portion 33b and the valve seat 34 becomes large. That is, the expansion valve 3 is configured such that when the valve element 33 moves to the second end E2 side in the axial direction A3, the throttle amount of the expansion valve 3 becomes small.

  The valve seat 34 is attached to the inside of the case 31. The valve seat 34 is disposed between the inflow portion 31a and the outflow portion 31b in the flow path from the inflow portion 31a to the outflow portion 31b. The valve seat 34 is disposed outside the tapered portion 33 b of the valve body 33.

  The spring 35 is connected to the second end E <b> 2 of the valve body 33 and the bottom of the case 31. The spring 35 is configured to urge the valve body 33 by an elastic force.

Next, the flow of the refrigerant in the refrigeration cycle of the air conditioner 10 of the present embodiment will be described.
With reference to FIG. 1, the refrigerant flowing into the compressor 1 is compressed by the compressor 1 to become a high-temperature high-pressure gas refrigerant. The high-temperature high-pressure gas refrigerant discharged from the compressor 1 flows into the condenser 2 that is a radiator through the pipe PI1. The refrigerant flowing into the condenser 2 exchanges heat with air in the condenser 2. Specifically, in the condenser 2, the refrigerant is condensed by heat dissipation into the air, and the air is heated by the refrigerant. The high-pressure liquid refrigerant condensed in the condenser 2 flows into the expansion valve 3 through the pipe PI2.

  The refrigerant flowing into the expansion valve 3 is decompressed by the expansion valve 3 and becomes a low-pressure gas-liquid two-phase refrigerant. The refrigerant depressurized by the expansion valve 3 flows into the evaporator 4 through the pipe PI3. The refrigerant that has flowed into the evaporator 4 exchanges heat with air in the evaporator 4. Specifically, in the evaporator 4, air is cooled by a refrigerant, and the refrigerant becomes a low-pressure gas refrigerant. The refrigerant that has been depressurized in the evaporator 4 to become low-pressure gas flows into the compressor 1 through the pipe PI4. The refrigerant that has flowed into the compressor 1 is compressed again and pressurized, and then discharged from the compressor 1.

  Next, with reference to FIG. 2 and FIG. 3, the operation of specific examples of the expansion valve 3 and the temperature detector 7 in the present embodiment will be described in detail.

  The diaphragm 32 has a difference between the pressure in the first chamber S1 of the case 31 (internal pressure of the temperature detecting unit 7 as a temperature sensing cylinder) A4 and the pressure in the second chamber S2 (pressure of the refrigerant condensed in the condenser 2) A5. Deforms due to pressure.

  When the temperature of the refrigerant sealed in the temperature detection unit 7 which is a temperature sensitive cylinder becomes high, the pressure in the first chamber S1 of the case 31 becomes higher than the pressure in the second chamber S2. When the pressure in the first chamber S1 of the case 31 becomes higher than the pressure in the second chamber S2, the diaphragm 32 is deformed so as to be convex toward the second chamber S2. Due to the deformation of the diaphragm 32, the valve element 33 moves to the second end E2 side in the axial direction A3. For this reason, the clearance gap between the taper part 33b and the valve seat 34 becomes large. That is, the throttle amount of the expansion valve 3 is reduced. Thereby, the amount of refrigerant flowing through the expansion valve 3 increases.

  On the other hand, when the temperature of the refrigerant sealed in the temperature detection unit 7 which is a temperature sensing tube is lowered, the pressure in the first chamber S1 of the case 31 is lower than the pressure in the second chamber S2. When the pressure in the first chamber S1 of the case 31 is lower than the pressure in the second chamber S2, the diaphragm 32 is deformed so as to be convex toward the first chamber S1. Due to the deformation of the diaphragm 32, the valve element 33 moves toward the first end E1 in the axial direction A3. For this reason, the clearance gap between the taper part 33b and the valve seat 34 becomes small. That is, the throttle amount of the expansion valve 3 is increased. Thereby, the refrigerant | coolant amount which flows through the expansion valve 3 reduces.

  Further, the amount of movement of the valve body 33 in the axial direction A3 includes the pressure of the refrigerant sealed in the temperature detection unit 7 flowing into the first chamber S1, and the pressure of the refrigerant in the refrigeration cycle flowing into the second chamber S2. It is determined by the urging force A6 of the spring 35 connected to the valve element 33.

Next, the relationship between the operating state of the refrigeration cycle and the throttle amount will be described.
The cooling capacity required for the refrigeration cycle is determined by the outside air temperature. This is because as the outside air temperature increases, the room air temperature increases in proportion to the increase in the outside air temperature, so that more cooling capacity is required. Therefore, as shown in FIG. 4, the outside air temperature and the cooling capacity (cooling load = necessary capacity) are in a proportional relationship. Since the rise in the outside air temperature and the rise in the condensation temperature are in a proportional relationship, the horizontal axis in FIG. 4 can be used as the condensation temperature. This also applies to FIGS. 5 and 6.

  The cooling capacity is proportional to the refrigerant flow rate Gr flowing through the refrigeration cycle. This can also be explained by the fact that the cooling capacity Qe is expressed as Qe = Gr × Δhe using the specific enthalpy difference Δhe of the refrigerant at the inlet and outlet of the evaporator. Therefore, as shown in FIG. 5, the outside air temperature and the circulation flow rate (required refrigerant flow rate) are in a proportional relationship.

  Further, the amount of throttle required for the temperature type expansion valve can be expressed by a flow coefficient (Cv value). This Cv is expressed by the following equation (1) using the refrigerant circulation flow rate Gr, the condensation pressure P1, the evaporation pressure P2, and the refrigerant density ρl at the inlet of the expansion valve.

  As shown in Expression (1), the refrigerant flow rate and the Cv value are in a proportional relationship. Therefore, as shown in FIG. 6, the refrigerant flow rate and the Cv value (necessary Cv value) are in a proportional relationship.

  In the air conditioner 10 of the present embodiment, the flow coefficient of the expansion valve 3 increases when the temperature of the refrigerant detected by the temperature detector 7 increases, and expands when the temperature of the refrigerant detected by the temperature detector 7 decreases. The flow coefficient of the valve 3 decreases.

Next, the effect of this Embodiment is demonstrated.
According to the air conditioner 10 of the present embodiment, the temperature detector 7 detects the temperature of the refrigerant in the condenser 2. When the temperature of the refrigerant detected by the temperature detector 7 increases, the valve opening of the expansion valve 3 increases. When the temperature of the refrigerant detected by the temperature detector 7 decreases, the valve opening of the expansion valve 3 decreases. To do. The temperature of the refrigerant in the condenser 2 is proportional to the outside air temperature. Therefore, when the outside air temperature is high, the temperature of the refrigerant detected by the temperature detecting unit 7 becomes high, and when the outside air temperature is low, the temperature of the refrigerant detected by the temperature detecting unit 7 becomes low. For this reason, the valve opening degree of the expansion valve 3 can be increased when the outside air temperature is high, and the valve opening degree of the expansion valve 3 can be decreased when the outside air temperature is low. Thereby, when the outside air temperature is high, the amount of refrigerant circulating through the air conditioner 10 can be increased, and when the outside air temperature is low, the refrigerant flow rate circulating through the air conditioner 10 can be reduced. Therefore, in the cooling operation of the air conditioner 10, the refrigerant flow rate circulating through the air conditioner 10 can be appropriately adjusted according to the outside air temperature.

  Further, in the air conditioner 10 of the present embodiment, the throttle amount of the expansion valve 3 can be changed according to the temperature of the refrigerant in the condenser 2. For this reason, an increase in the refrigerant discharge temperature of the compressor 1 can be suppressed as compared with a case where a capillary with a fixed throttle amount is used as the expansion valve. Therefore, failure of the compressor 1 due to an increase in the refrigerant discharge temperature of the compressor 1 can be suppressed.

  Further, in the air conditioner 10 of the present embodiment, the throttle amount of the expansion valve 3 can be changed according to the temperature of the refrigerant in the condenser 2. Therefore, the refrigerant at the outlet of the evaporator 4 is close to the saturated gas by adjusting the degree of superheat determined by the difference between the refrigerant temperature at the outlet of the evaporator 4 and the refrigerant temperature inside the evaporator 4 to about 1K to 5K. Can be controlled. Therefore, the refrigerant sucked into the compressor 1 can be controlled in a state close to saturated gas. For this reason, the performance of the compressor 1 can be improved compared with the case where a capillary with a fixed throttle amount is used as the expansion valve.

  Further, in the air conditioner 10 of the present embodiment, the throttle amount of the expansion valve 3 can be changed according to the temperature of the refrigerant in the condenser 2. For this reason, the degree of supercooling at the outlet of the condenser 2 can be ensured. Therefore, it is possible to reduce noise generated when the gas phase flows into the inlet of the expansion valve 3.

  Further, in the air conditioner 10 of the present embodiment, the throttle amount of the expansion valve 3 can be changed according to the temperature of the refrigerant in the condenser 2. For this reason, the high pressure of the condenser 2 can be controlled. Therefore, in order to control the high pressure of the condenser 2, it is not necessary to make the rotation speed of the fan 5a of the condenser blower 5 variable. Therefore, a constant speed machine with a constant rotation speed of the fan 5a can be used as the condenser blower 5.

  Further, when a refrigerant having a high discharge temperature (for example, R410a, R32, R1234yf, etc.) is used, when the temperature detector 7 is attached to the outlet of the evaporator 4, the degree of superheat is kept constant, so The temperature cannot be lowered under conditions where the discharge temperature becomes high. On the other hand, in the air conditioner 10 of the present embodiment, the temperature detection unit 7 is attached to the condenser 2, and the refrigerant sucked into the compressor 1 can be operated in a gas-liquid two phase. Therefore, the discharge temperature can be lowered. As a result, failure of the compressor 1 can be prevented even when a refrigerant having a high discharge temperature is used.

  In the air conditioner 10 of this Embodiment, the expansion valve 3 is a temperature type expansion valve, and the temperature detection part 7 is a temperature sensing cylinder. For this reason, a temperature type expansion valve can be used as the expansion valve 3, and a temperature sensitive cylinder can be used as the temperature detection unit 7. Therefore, the size and cost of the air conditioner 10 can be reduced as compared with the case where an electronic expansion valve is used. That is, when an electronic expansion valve is used, an electronic board for driving the electronic expansion valve is required, and thus it is necessary to secure a space for installing the electronic board. For this reason, the size of the air conditioner 10 becomes large. Further, since an actuator for driving the electronic expansion valve is required, the cost of the air conditioner 10 increases. On the other hand, in the air conditioner 10 according to the present embodiment, a temperature type expansion valve can be used as the expansion valve 3 and a temperature sensing cylinder can be used as the temperature detection unit 7. Therefore, an electronic type expansion valve is used. Compared to the case, the size and cost of the air conditioner 10 can be reduced.

  In the air conditioner 10 of the present embodiment, the compressor 1 can control the rotation speed variably. For this reason, the cooling capacity can be changed by variably controlling the rotation speed of the compressor 1. Therefore, the amount of refrigerant circulating through the air conditioner 10 can be increased when the outside air temperature is high and the amount of refrigerant circulating in the air conditioner 10 can be increased when the outside air temperature is high while the rotation speed of the compressor 1 is variably controlled. The flow rate of the refrigerant circulating through the air conditioner 10 can be reduced.

  In the air conditioner 10 of this embodiment, the flow coefficient of the expansion valve 3 increases when the temperature of the refrigerant detected by the temperature detector 7 increases, and the expansion valve when the temperature of the refrigerant detected by the temperature detector 7 decreases. The flow coefficient of 3 decreases. For this reason, the expansion valve 3 can be adjusted by the change of the flow coefficient.

  In the air conditioner 10 of the present embodiment, the temperature detection unit 7 detects the temperature of the refrigerant in a state before the refrigerant is condensed and liquefied in the condenser 2. For this reason, the temperature of the refrigerant proportional to the outside air temperature can be accurately detected. Therefore, the flow rate of the refrigerant circulating through the air conditioner 10 can be adjusted accurately according to the outside air temperature.

(Embodiment 2)
Hereinafter, unless otherwise described, the same reference numerals are given to the same components as those in the first embodiment, and description thereof will not be repeated.

  Referring to FIGS. 7 and 8, the configuration of expansion valve 3 is different in the second embodiment of the present invention than in the first embodiment.

  In the first embodiment, the expansion valve 3 is used in which the refrigerant temperature and the flow coefficient (Cv value) detected by the temperature detector 7 are linear. As shown in FIGS. 7 and 8, the expansion valve 3 of the second embodiment is configured so that the flow coefficient (Cv value) changes stepwise when the valve element 33 moves to a predetermined position.

  In the expansion valve 3 of the present embodiment, the valve element 33 has a shaft portion 33a and a tubular portion 33c. The tubular portion 33c has a peripheral wall, an internal space surrounded by the peripheral wall, and a first hole H1 and a second hole H2 provided in the peripheral wall. The second hole H2 has an opening area smaller than that of the first hole H1. The first hole H1 and the second hole H2 communicate with the internal space. The valve seat 34 is inserted from the second end E2 into the internal space of the tubular portion 33c. The valve seat 34 extends in the axial direction A3. The expansion valve 3 is configured such that the refrigerant flows from the inflow portion 31a to the outflow portion 31b through either the first hole H1 or the second hole H2. The spring 35 has a first spring 35a and a second spring 35b. The first spring 35 a and the second spring 35 b are connected to the second end E <b> 2 of the valve element 33 and the bottom of the valve seat 34.

  With reference to FIGS. 8 to 10, the expansion valve 3 has a first flow path F1 and a second flow path F2. Referring to FIGS. 8 and 9, the first flow path F1 is a flow path from the inflow portion 31a to the outflow portion 31b through the first hole H1. The first flow path F1 has a large refrigerant flow rate and a large flow coefficient (Cv value). With reference to FIGS. 8 and 10, the second flow path F2 is a flow path from the inflow portion 31a to the outflow portion 31b through the second hole H2. The second flow path F2 has a smaller flow rate than the first flow path F1. The second flow path F2 has a small refrigerant flow rate and a small flow coefficient (Cv value).

  9 and 10, the expansion valve 3 is switched to the first flow path F1 when the temperature of the refrigerant detected by the temperature detection unit 7 rises, and the temperature of the refrigerant detected by the temperature detection unit 7 is changed. If it falls, it will switch to the 2nd flow path F2. Specifically, as shown in FIG. 7, the first flow path F1 and the second flow path F2 are switched at a predetermined temperature A (for example, an outside air temperature of 35 ° C. based on the ISO standard).

  In the air conditioner 10 of the present embodiment, the expansion valve 3 is switched to the first flow path F1 when the temperature of the refrigerant detected by the temperature detection unit 7 rises, and the temperature of the refrigerant detected by the temperature detection unit 7 is changed. If it falls, it will switch to the 2nd flow path F2. For this reason, the 1st flow path F1 and the 2nd flow path F2 can be switched based on the temperature of the refrigerant | coolant detected by the temperature detection part 7. FIG.

  Further, in the air conditioner 10 of the present embodiment, the flow coefficient (Cv value) can be increased when, for example, the discharge temperature becomes the outside air temperature or the condensation temperature exceeding the upper limit temperature of the compressor 1. Therefore, it is possible to operate the refrigerant in a gas-liquid two-phase state at the inlet of the compressor 1. For this reason, since discharge temperature reduces, it is possible to drive | operate safely.

  Moreover, in the air conditioner 10 of this Embodiment, since the valve body 33 is easy to process compared with a normal valve body, the cost of the expansion valve 3 can be reduced. Therefore, the cost of the air conditioner 10 can also be reduced.

  Further, a normal air conditioner is provided with a mechanism that can change the rotation speed of the fan of the condenser blower in order to control the condensation temperature. For example, a DC fan is mounted. Usually, when discharge temperature rises, in order to protect a compressor, the operation | movement which raises the rotation speed of the fan of the fan for condensers, and reduces condensation temperature is performed. On the other hand, in the present embodiment, when the discharge temperature has risen, it is possible to perform an operation with an increased flow coefficient (Cv value), so that the refrigerant at the inlet of the compressor 1 is gas-liquid two-phase. In this state, the discharge temperature decreases. For this reason, it is possible to supplement the protection operation of the condenser blower 5 with the expansion valve 3. Therefore, the air conditioner 10 of this Embodiment is useful when the rotation speed of the fan 5a of the condenser blower 5 is constant.

  Moreover, the valve body 33 and the valve seat 34 should just be comprised so that a flow rate coefficient (Cv value) may be changed by changing a flow path not only in said structure. A modified example of the present embodiment will be described with reference to FIGS. 11 and 12. In this modification, the valve body 33 has a third hole H3 and a fourth hole H4. The third hole H3 is provided in the upper part of the valve body 33. The third hole H3 is configured such that the refrigerant can always flow therethrough. When the refrigerant flows only through the third hole H3, the refrigerant flow rate becomes small and the flow coefficient (Cv value) becomes small. The fourth hole H4 is provided in the side portion of the valve body 33. The fourth hole H4 is configured such that the refrigerant flows when the valve body 33 is lowered. When the refrigerant flows through the fourth hole H4 in addition to the third hole H3, the refrigerant flow rate increases and the flow coefficient (Cv value) increases.

(Embodiment 3)
Referring to FIG. 13, air conditioner 10 according to the third embodiment of the present invention is different from air conditioner 10 according to the first embodiment in that it includes capillary 9.

  The air conditioner 10 according to the present embodiment further includes a capillary 9. The capillary 9 is connected to the expansion valve 3 and the evaporator 4. For this reason, the refrigerant can be condensed by the capillary 9.

  Since the capillary 9 is disposed after the expansion valve 3, even when the expansion valve 3 fails, the capillary 9 can ensure a minimum amount of restriction. For example, although the required flow coefficient (Cv value) is small, if the expansion valve 3 fails and is fixed where the flow coefficient (Cv value) is large, more refrigerant flow flows. The refrigerant is in a gas-liquid two-phase state at the inlet of the compressor 1. In the present embodiment, since the capillary 9 is provided after the expansion valve 3, it is possible to operate in a state where the capillary 9 is throttled at a minimum. Therefore, even when the expansion valve 3 fails, the safety of the compressor 1 can be ensured.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Condenser, 3 Expansion valve, 4 Evaporator, 5 Blower for condenser, 6 Blower for evaporator, 7 Temperature detection part, 8 pipe, 9 Capillary, 10 Air conditioner, 11 Outdoor unit, 12 Indoor unit, 31 Case, 31a Inflow part, 31b Outflow part, 32 Diaphragm, 33 Valve body, 33a Shaft part, 33b Taper part, 33c Tubular part, 34 Valve seat, 35 Spring, F1 1st flow path, F2 2nd flow path.

Claims (4)

A compressor that compresses the refrigerant and can variably control the rotational speed;
A condenser for condensing the refrigerant compressed by the compressor;
An expansion valve for decompressing the refrigerant condensed by the condenser;
An evaporator for evaporating the refrigerant decompressed by the expansion valve;
A temperature detection unit for detecting the temperature of the refrigerant,
The expansion valve has a case, a diaphragm, a valve body connected to the diaphragm, and a valve seat attached to the case.
The case has a first chamber and a second chamber partitioned by the diaphragm,
The first chamber is configured to allow the refrigerant enclosed in the temperature detection unit to enter and exit,
The second chamber contains the valve body and the valve seat, and is configured such that the refrigerant condensed by the condenser flows in,
The diaphragm is configured to be deformable by a differential pressure between an internal pressure of the temperature detection unit, which is a pressure of the first chamber, and a pressure of the refrigerant condensed by the condenser, which is a pressure of the second chamber. And
The expansion valve is capable of adjusting a flow rate of the refrigerant passing through the expansion valve by adjusting a valve opening degree of the expansion valve by moving the valve body due to deformation of the diaphragm , and a temperature type expansion valve. And
The temperature detector is a temperature sensitive cylinder,
The temperature sensing cylinder is accommodated in an outdoor unit,
When the temperature of the refrigerant detected by the temperature detector increases, the valve opening of the expansion valve increases. When the temperature of the refrigerant detected by the temperature detector decreases, the valve opening of the expansion valve decreases. And
The expansion valve includes a first flow path and a second flow path having a smaller flow rate than the first flow path,
The expansion valve is switched to the first flow path when the temperature of the refrigerant detected by the temperature detection unit increases, and to the second flow path when the temperature of the refrigerant detected by the temperature detection unit decreases. Switched air conditioner.   When the temperature of the refrigerant detected by the temperature detector increases, the flow coefficient of the expansion valve increases, and when the temperature of the refrigerant detected by the temperature detector decreases, the flow coefficient of the expansion valve decreases. The air conditioner according to claim 1. Further comprising a capillary,
The air conditioner according to claim 1 or 2 , wherein the capillary is connected to the expansion valve and the evaporator. The air conditioner according to any one of claims 1 to 3 , wherein the temperature detection unit detects a temperature of the refrigerant in a state before the refrigerant is condensed and liquefied in the condenser.

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