JP4715650B2 - Refrigeration cycle equipment - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus suitable for use with, for example, carbon dioxide or the like as a refrigerant and a high pressure side pressure that exceeds a critical point.

  Conventionally, as shown in, for example, Patent Document 1, in a refrigeration cycle control apparatus in which a compressor whose discharge capacity can be changed is used and the high-pressure side pressure of a refrigerant is operated in a supercritical region, When the heat load of the compressor is larger than the predetermined heat load, there is known one that controls the discharge capacity of the compressor so as to continuously change from the minimum discharge capacity to the maximum discharge capacity over a predetermined time.

Thus, a sudden pressure increase at the start of the refrigeration cycle is avoided to eliminate the concern about breakage of the piping and the like, and the ON-OFF control is eliminated to prevent the deterioration of the cooling performance at the initial start-up.
JP 2002-71228 A

  However, in the above prior art, the concept of detailed setting of the predetermined time when changing the discharge capacity is not shown, and if this predetermined time is unnecessarily long, a cooling delay occurs, and conversely, the predetermined time is extremely shortened. As a result, the rate of change in the increase in discharge capacity increases, which may cause overshoot of the high-pressure side pressure.

  In addition, in the refrigeration cycle, it is necessary to always suppress the high-pressure side pressure below the permissible pressure regardless of the start-up to prevent problems related to pressure resistance.

  In view of the above problems, an object of the present invention is to provide a refrigeration cycle apparatus capable of controlling a discharge amount of a compressor at a target pressure or less without causing a rapid rise in pressure and a delay in cooling.

  In order to achieve the above object, the present invention employs the following technical means.

In the first aspect of the present invention, the refrigerant (110) that compresses the refrigerant to high temperature and high pressure and discharges the discharge amount in an adjustable manner, and the discharge amount of the compressor (111). In a vehicle refrigeration cycle apparatus comprising a control device (120) for controlling
In addition to the condition that the discharge pressure of the refrigerant discharged from the compressor (111) by the PI calculation does not always exceed the target discharge pressure , the control device (120)
Conditions for preventing the discharge temperature of the refrigerant discharged from the compressor (111) from exceeding the target discharge temperature,
Control for discharge amount control under the condition that the cooling temperature indicated by the air temperature, the refrigerant temperature, or the representative part temperature in the low pressure side heat exchanger (114) of the refrigeration cycle (110) does not fall below the target cooling temperature. Calculate each signal,
Among the control signals, the discharge amount of the compressor (111) is controlled by a control signal that makes the discharge amount the smallest .

  As a result, the discharge pressure is always controlled by the PI calculation so as to approach the target discharge pressure from the lower side of the target discharge pressure without providing a predetermined time as in the prior art. Therefore, the discharge pressure can be maintained below the target discharge pressure without causing a rapid increase in pressure and a delay in cooling.

And it can control reliably so that the discharge pressure and discharge temperature of a refrigerating cycle (110) may not exceed each target value, and cooling temperature may not fall below target cooling temperature.

In the invention according to claim 2 , the control device (120) is characterized in that, among the PI calculations related to the discharge pressure, the discharge temperature, and the cooling temperature, the calculation cycle of the PI calculation related to the discharge pressure is set to be the shortest. Yes.

  As a result, it is possible to apply frequent feedback to the discharge pressure, discharge temperature, and cooling temperature that reacts most sensitively with changes in the discharge amount, so reliable discharge pressure maintenance control is possible. It becomes.

The invention according to claim 3 is characterized in that the control device (120) sets the calculation cycles of the PI calculations related to the discharge pressure, the discharge temperature, and the cooling temperature to be all different.

Thereby, in addition to the effect of the invention described in claim 2 , feedback that matches each of the discharge pressure, the discharge temperature, and the cooling temperature can be applied, so that the stability of each characteristic value can be improved.

In the invention according to claim 4 , the control device (120) normally controls the discharge amount using a control signal based on PI calculation related to the cooling temperature, and when the discharge pressure is higher than a predetermined discharge pressure or When the temperature is higher than a predetermined discharge temperature, the discharge amount is controlled by a control signal that minimizes the discharge amount.

Thus, generally it can be controlled to maintain primarily to cool the temperature does not fall below the target cooling temperature, discharge pressure, discharge temperature control becomes possible in consideration depending on the situation.

In the first to fourth aspects of the invention, the compressor (111) is an externally driven compressor (111) driven by an external drive source as in the fifth aspect of the invention. Alternatively, as in the sixth aspect of the invention, the electric compressor (111A) driven by the electric motor (111b) can be provided.

Further, the discharge amount of the compressor (111) is determined by any one of a current signal, a voltage signal, or a duty ratio signal output from the control device (120) as in the inventions of claims 7 to 9 . Can be adjusted.

Moreover, it is suitable for the refrigeration cycle apparatus in which the pressure of the refrigerant compressed by the compressor (111) exceeds the critical pressure as in the invention described in claim 10 .

As the refrigerant, carbon dioxide can be used as in the invention described in claim 11 .

  In addition, the code | symbol in the bracket | parenthesis of each said means shows a corresponding relationship with the specific means of embodiment description mentioned later.

(First embodiment)
Hereinafter, the refrigeration cycle apparatus 100 according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram showing the overall configuration of the refrigeration cycle apparatus 100, and FIG.

As shown in FIG. 1, a refrigeration cycle apparatus 100 is mounted on a vehicle using an engine (not shown) as a driving source for driving, and cools (air-conditions) the vehicle interior. 120 or the like. Here, carbon dioxide (CO ₂ ) is used as the refrigerant circulating in the refrigeration cycle 110, and the refrigerant is used in a state where the high-pressure side pressure is higher than the critical pressure.

  The refrigeration cycle 110 is formed by sequentially connecting a compressor 111, an outdoor heat exchanger 112, an expansion valve 113, an indoor heat exchanger 114, and an accumulator 115 in an annular shape. The internal heat that exchanges heat between the high-pressure side refrigerant (high-temperature refrigerant) flowing between the outdoor heat exchanger 112 and the expansion valve 113 and the low-pressure side refrigerant (low-temperature refrigerant) flowing between the accumulator 115 and the compressor 111. An exchanger 116 is provided.

  Among the devices 111 to 116 constituting the refrigeration cycle 110, the indoor heat exchanger 114 is accommodated in an air conditioning case 117 described later, and is disposed in the vehicle interior (inside the instrument panel) together with the blower unit 118. The devices (111 to 113, 115, 116) are disposed in the engine room of the vehicle.

  The compressor 111 is a fluid machine that compresses a refrigerant to a high temperature and a high pressure and discharges the refrigerant to the outdoor heat exchanger 112 side. A rank pulley of the engine crank and a pulley of the compressor 111 are connected by a belt, and the compressor 111 is an externally driven compressor driven by an engine (corresponding to an external drive source in the present invention). Further, the compressor 111 is a variable capacity compressor capable of adjusting the discharge capacity per one rotation, and here, for example, a swash plate type is adopted. In addition, the discharge amount of the refrigerant discharged from the compressor 111 is obtained by multiplying the discharge capacity per one rotation by the rotation speed of the compressor 111 (hereinafter referred to as the compressor rotation speed).

  A swash plate (not shown) of the compressor 111 is disposed in a swash plate chamber in the compressor 111 so as to rotate together with the compressor rotating shaft, and a piston sliding in the cylinder is connected to the swash plate. Yes. The compressor 111 is provided with a flow rate control valve (not shown). By adjusting the opening degree of the flow rate control valve, the pressure in the swash plate chamber (intermediate between the discharge pressure and the suction pressure) is adjusted. Pressure) is adjusted, and the inclination angle of the swash plate with respect to the compressor rotation shaft is changed. Then, the piston stroke is changed in accordance with the change of the inclination angle of the swash plate, so that the discharge capacity per revolution is almost zero to the maximum discharge capacity that can be discharged as the compressor 111 continuously. To be adjusted.

  The valve opening degree of the flow control valve is adjusted by a control signal (for example, a current signal I) output from the control device 120 described later. That is, the discharge capacity (discharge amount) of the compressor 111 is controlled by the control device 120. Here, as the current signal I is increased, the discharge capacity of the compressor 111 is increased.

  Then, on the discharge side of the compressor 111 (between the compressor 111 and the outdoor heat exchanger 112), a pressure sensor 111a as discharge pressure detecting means for detecting the pressure of the discharged refrigerant, and the temperature of the discharged refrigerant A temperature sensor 111b is provided as a discharge temperature detecting means for detecting the discharge pressure, and a discharge pressure signal detected by the pressure sensor 111a and a discharge temperature signal detected by the temperature sensor 111b are respectively described in a control device 120 described later. To be input.

  The outdoor heat exchanger 112 is disposed in front of the engine room of the vehicle (for example, behind the grill), and performs heat exchange between the refrigerant discharged from the compressor 111 and the outside air flowing into the engine room. It is a heat exchanger that cools.

  The expansion valve 113 is a pressure reducing means for reducing the pressure of the refrigerant flowing out of the outdoor heat exchanger 112 (internal heat exchanger 116) (making the temperature low and low pressure). This expansion valve 113 is a mechanical expansion valve in which the valve opening degree of the expansion valve 113 is adjusted according to the temperature of the refrigerant flowing out of the outdoor heat exchanger 112. Specifically, the temperature of the refrigerant flowing out of the outdoor heat exchanger 112 is detected, and the high pressure is controlled so that the refrigerant pressure becomes closer to the optimum efficiency.

  The indoor heat exchanger (corresponding to the low pressure side heat exchanger in the present invention) 114 is disposed so as to cross the entire flow path in the air conditioning case 117, and the refrigerant decompressed by the expansion valve 113 and the inside of the air conditioning case 117 are disposed. It is a heat exchanger that cools conditioned air by exchanging heat with circulated conditioned air. A thermistor 114a as a cooling temperature detecting means for detecting the cooled air temperature (corresponding to the cooling temperature in the present invention) is provided on the downstream side of the conditioned air flow of the indoor heat exchanger 114, and is detected by the thermistor 114a. The cooled cooling air temperature signal is inputted to the control device 120 described later.

  The accumulator 115 receives the refrigerant that has flowed out of the indoor heat exchanger 114, separates the gas-liquid of the refrigerant, stores the liquid refrigerant, and internally heats the gas refrigerant and a small amount of liquid refrigerant (oil is dissolved) near the bottom. This is a receiver that sucks the compressor 111 through the exchanger 116.

  The internal heat exchanger 116 supercools the high-temperature refrigerant that flows out of the outdoor heat exchanger 112, and superheats the low-temperature refrigerant that flows out of the indoor heat exchanger 114 (accumulator 115). It is a heat exchanger that increases enthalpy and increases cooling capacity.

  Note that a blower unit 118 including a blower 118 b is provided on one end side of the air conditioning case 117, and the conditioned air is supplied to the indoor heat exchanger 114 by the blower unit 118. In addition, the conditioned air intake portion of the blower unit 118 is provided with an inside / outside air switching door 118a as inside / outside air selection means. The inside / outside air switching door 118a is rotationally controlled by a control device 120, which will be described later, and by changing the opening position of the conditioned air intake portion, either the inside air or the outside air of the vehicle can be selected as the conditioned air. ing.

  In the air conditioning case 117, in addition to the indoor heat exchanger 114, a heater core 117a as a heater is disposed. The heater core 117a is disposed downstream of the conditioned air flow with respect to the indoor heat exchanger 114. The heater core 117a is a heat exchanger that heats conditioned air flowing through itself using hot water circulated with the engine as a heating source. A bypass passage 117b is formed between the heater core 117a and the air conditioning case 117 so as to bypass the heater core 117a and allow the conditioned air to flow therethrough.

  The heater core 117a is provided with an air mix door 117c. Here, the air mix door 117c is a rotary door, and the flow rate ratio between the heated air flowing through the heater core 117a and the cooling air flowing through the bypass flow passage 117b is adjusted according to the opening degree of the air mix door 117c. Thus, the temperature of the conditioned air on the downstream side of the heater core 117a (correlation with the inside air temperature in the passenger compartment) is adjusted. For example, when the air mix door 117c is fully closed so as to cover the entire surface of the heater core 117a, the maximum heat (Maxcool) mode by the indoor heat exchanger 114 is set, and conversely, the air mix door 117c is switched from the fully closed state to the bypass flow path 117b. When the heater core 117a is fully opened so as to close the heater, the maximum heating (Maxhot) mode by the heater core 117a is set. The opening degree of the air mix door 117c is controlled by the control device 120 described later.

  The most downstream side of the heater core 117a of the air conditioning case 117 is connected to a plurality of air outlets that open toward the vehicle interior. It has come to be blown out.

  The control device 120 as a control means is composed of a microcomputer and its peripheral circuits, and according to a preset program, a discharge pressure signal from the pressure sensor 111a, a discharge temperature signal from the temperature sensor 111b, and a cooling air temperature from the thermistor 114a. Signals, an inside air temperature signal from an inside air sensor (not shown), an outside air temperature signal from an outside air temperature sensor (not shown), and a setting signal set by an occupant on an operation panel (not shown), and operation of the compressor 111 and discharge amount control The position control of the inside / outside air switching door 118a of the blower unit 118 and the opening degree control of the air mix door 117c are performed.

  Next, the operation based on the above configuration will be described.

  The control device 120 operates the refrigeration cycle 110 based on a cooling request from the occupant. The control device 120 calculates a target blowing temperature for the conditioned air temperature on the downstream side of the heater core 117a from the set temperature set by the occupant, the inside air temperature, the outside air temperature, and the like. Then, while controlling the position of the inside / outside air switching door 118a according to the inside air selection or outside air selection by the occupant, the cooling air temperature in the indoor heat exchanger 114 is set to a predetermined temperature (eg, 3 ° C.). Control the discharge rate. Furthermore, the opening degree of the air mix door 117c is controlled so that the temperature of the conditioned air downstream of the heater core 117a becomes the target blowing temperature.

  Here, in the refrigeration cycle 110 in which the high-pressure side pressure exceeds the critical pressure, the control device 120 controls the discharge pressure and the discharge temperature so as not to increase excessively in order to avoid problems related to pressure resistance. To do. Moreover, in order not to cause the performance fall by the frost formation in the indoor heat exchanger 114, the control apparatus 120 is controlled so that cooling air temperature does not fall from predetermined temperature. Hereinafter, the control point of discharge pressure, discharge temperature, and cooling air temperature will be described in detail with reference to FIG.

  First, in step S100, the control device 120 sets a target discharge pressure PDO, a target discharge temperature TDO, and a target cooling air temperature TEO as target values for the discharge pressure PD, the discharge temperature TD, and the cooling air temperature TE, respectively. Each target value can be set to a predetermined value (allowable discharge pressure value, allowable discharge temperature value, allowable cooling air temperature value), for example.

  Next, in step S110, the discharge pressure PD obtained from the pressure sensor 111a, the discharge temperature TD obtained from the temperature sensor 111b, and the cooling air temperature TE obtained from the thermistor 114a are read.

  Next, feedback calculation by PI control is performed in step S120, and a control current signal IPD for adjusting the discharge amount of the compressor 111 is calculated so that the discharge pressure PD becomes equal to or less than the target discharge pressure PDO. Here, the above calculation is performed at a calculation cycle of once every 0.5 seconds.

  Similarly, feedback calculation by PI control is performed in step S130, and a control current signal ITD for adjusting the discharge amount of the compressor 111 is calculated so that the discharge temperature TD is equal to or lower than the target discharge temperature TDO. Here, the above calculation is performed at a calculation cycle of once per second.

  Further, in step S140, feedback calculation by PI control is performed, and a control current signal ITE for adjusting the discharge amount of the compressor 111 is calculated so that the cooling air temperature TE becomes equal to or higher than the target cooling air temperature TEO. Here, the above calculation is performed at a calculation cycle of once per second.

  Next, in step S150, the smallest current signal is selected from the three current signals IPD, ITD, and ITE obtained in steps S120 to S140. That is, the current signal that minimizes the discharge amount of the compressor 111 adjusted by the three current signals IPD, ITD, and ITE is selected.

  In step S160, the current signal selected as described above is output to control the discharge amount of the compressor 111. Thereafter, step S100 to step S160 are repeated.

  With the above control, in the present embodiment, the discharge pressure and the discharge temperature of the refrigeration cycle 110 are not always exceeded the target discharge pressure and the target discharge temperature by the PI calculation without providing a predetermined time as in the prior art. In addition, the cooling air temperature can be reliably controlled so as not to fall below the target cooling air temperature. Therefore, there is no occurrence of a sudden rise in pressure and a delay in cooling, and it is possible to reliably prevent the occurrence of problems relating to pressure resistance and the occurrence of frost formation in the indoor heat exchanger 114.

  In addition, the calculation cycle of the feedback calculation by PI control related to the discharge pressure is made the shortest compared to other calculation cycles (0.5 seconds with respect to 1 second), so that the discharge pressure, the discharge temperature, and the cooling are reduced. Of the air temperatures, since frequent feedback can be applied to the discharge pressure that reacts most sensitively with the change in the discharge amount, reliable maintenance control of the discharge pressure is possible.

(Second Embodiment)
A second embodiment of the present invention is shown in FIGS. In the second embodiment, the control flow executed by the control device 120 is changed with the configuration of the refrigeration cycle apparatus 100 being the same as that of the first embodiment.

  In the flowchart of the second embodiment shown in FIG. 3, steps S151 to S156 are added between step S150 and step S160 with respect to the flowchart described in the first embodiment (FIG. 2).

  Hereinafter, the contents of the control will be described focusing on the changes in the flow. After calculating current signals IPD, ITD, and ITE related to the discharge pressure, discharge temperature, and cooling air temperature in steps S100 to S140, the current signal ITE is set as the control current signal ctlI in step S150.

  Next, in step S151, it is determined whether or not the discharge pressure PD is higher than a predetermined pressure P1 (P1 <PDO). If it is determined that the discharge pressure PD is lower than the predetermined pressure P1 (FIG. 4). If the comparison is not in progress), the process proceeds to step S152. Similarly, in step S152, it is determined whether or not the discharge temperature TD is higher than a predetermined temperature T1 (T1 <TDO). If not, that is, if it is determined that the discharge temperature TD is lower than the predetermined temperature T1 (FIG. 5). In the case where the comparison target is not included), the process proceeds to step S160, and the control current signal ctlI set in step S150 is output to control the discharge amount of the compressor 111. That is, when both the discharge pressure PD and the discharge temperature TD are away from the target values (target discharge pressure PDO, target discharge temperature TDO), the discharge amount of the compressor 111 is controlled using the current signal ITE.

  On the other hand, when the determination in step S151 is affirmative, that is, when it is determined that the discharge pressure PD is higher than the predetermined pressure P1 (in the case of comparison in FIG. 4), the current signal IPD is compared with the control current signal ctlI in step S153. If the current signal ctlI is larger, the control current signal ctlI is replaced with the current signal IPD in step S154, and the process proceeds to step S152. If the current signal IPD is larger in step S153 (in the case of NO), the process proceeds to step S152 as it is.

  Further, if the determination in step S152 is affirmative, that is, the discharge temperature TD is higher than the predetermined temperature T1 (in the case of comparison in FIG. 5), the current signal ITD is compared with the control current signal ctlI in step S155, and the control current signal ctlI is compared. If is larger, the control current signal ctlI is replaced with the current signal ITD in step S156, and the process proceeds to step S160. When the current signal ITD is larger in step S155 (in the case of NO), the process proceeds to step S160 as it is.

  That is, in step S153 to step 156, when the discharge pressure PD is higher than the predetermined pressure P1, a smaller current signal is adopted as compared with the current signal ITE and the current signal IPD, and the discharge temperature TD is set to the predetermined temperature. In the case where it is higher than T1, the smaller current signal is compared with the current signal ITD in steps S153 and 154, and the smaller current signal is adopted, that is, the conditions of the discharge pressure PD and the discharge temperature TD. Accordingly, the smaller current signal is selected as a control current signal.

  As a result, it is usually possible to control mainly to maintain the cooling air temperature TE at or above the target cooling air temperature TEO, and it is possible to perform control in consideration of the discharge pressure PD and the discharge temperature TD according to the situation.

(Other embodiments)
In each of the above embodiments, the discharge amount control of the compressor 111 is performed based on feedback calculation by PI control related to the discharge pressure PD, the discharge temperature TD, and the cooling air temperature TE. It is good also as discharge amount control based on this feedback calculation.

  In addition, in the feedback calculation by PI control, the calculation cycle related to the discharge pressure PD is made the shortest (0.5 seconds) and the other two calculation cycles are the same (1 second), but the calculation related to the discharge pressure PD is performed. The cycle may be made the shortest and the other two computation cycles may be different. As a result, feedback that matches each of the discharge pressure PD, the discharge temperature TD, and the cooling air temperature TE can be applied, so that the stability of each characteristic value can be improved.

  The compressor 111 is an externally driven compressor driven by an engine as an external drive source. However, the compressor 111 is not limited to this, and may be an electric compressor driven by an electric motor.

  Further, as the variable capacity type compressor 111, the discharge capacity of the compressor 111 is increased as the current signal is increased. However, the reverse characteristic may be obtained.

  Further, when the discharge amount (discharge capacity) of the compressor 111 is adjusted, the control device 120 uses a current signal, but it may be a voltage signal instead. Further, the signal for controlling the discharge amount may be output with a duty ratio.

  Further, the cooling temperature in the indoor heat exchanger 114 may be the temperature of the refrigerant flowing through the heat exchanger 114 before or after the indoor heat exchanger 114 instead of the cooling air temperature, or the representative part temperature of the indoor heat exchanger 114. And so on.

  Further, the high-pressure side pressure of the refrigeration cycle 110 is not limited to being used in a region exceeding the critical pressure, and may be used below the critical pressure. Furthermore, the refrigerant used is not limited to carbon dioxide, but may be other chlorofluorocarbon refrigerants such as HFC134a.

It is a mimetic diagram showing the whole refrigeration cycle device for vehicles in a 1st embodiment. It is a control flowchart which the control apparatus in 1st Embodiment performs. It is a control flowchart which the control apparatus in 2nd Embodiment performs. It is a map which determines whether to compare a current signal according to discharge pressure. It is a map which determines whether to compare a current signal according to discharge temperature.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Refrigeration cycle apparatus 110 Refrigeration cycle 111 Compressor 114 Indoor heat exchanger (low pressure side heat exchanger)
120 controller

Claims (11)

A refrigeration cycle (110) having as a component a compressor (111) that compresses the refrigerant to high temperature and pressure and discharges the discharge amount in an adjustable manner;
In a vehicle refrigeration cycle apparatus comprising a control device (120) for controlling the discharge amount of the compressor (111),
In addition to the condition that the discharge pressure of the refrigerant discharged from the compressor (111) by the PI calculation does not always exceed the target discharge pressure , the control device (120)
Conditions for preventing the discharge temperature of the refrigerant discharged from the compressor (111) from exceeding the target discharge temperature;
For the discharge amount control under the condition that the cooling temperature indicated by the air temperature, the refrigerant temperature, or the representative part temperature in the low pressure side heat exchanger (114) of the refrigeration cycle (110) does not fall below the target cooling temperature. Control signal for each
The refrigerating cycle apparatus characterized by controlling the discharge amount of the said compressor (111) with the control signal which makes the said discharge amount the smallest among each said control signal . The said control apparatus (120) sets the calculation period of PI calculation regarding the said discharge pressure among the said PI calculations regarding the said discharge pressure, the said discharge temperature, and the said cooling temperature to the shortest. refrigeration cycle apparatus according to 1. The refrigeration cycle apparatus according to claim 2 , wherein the control device (120) sets the calculation cycles of the PI calculations related to the discharge pressure, the discharge temperature, and the cooling temperature to be all different. . The controller (120) normally controls the discharge amount using the control signal by the PI calculation related to the cooling temperature,
If the discharge pressure is higher than a predetermined discharge pressure, or claim 1, wherein the discharge temperature is higher than the predetermined discharge temperature, and controls the ejection amount by a control signal to reduce most of the discharge amount The refrigeration cycle apparatus according to any one of claims 3 to 4. The refrigeration cycle apparatus according to any one of claims 1 to 4 , wherein the compressor (111) is an externally driven compressor (111) driven by an external drive source. The refrigeration cycle apparatus according to any one of claims 1 to 4 , wherein the compressor (111) is an electric compressor driven by an electric motor. The refrigeration cycle apparatus according to any one of claims 1 to 6 , wherein a discharge amount of the compressor (111) is adjusted by a current signal output from the control device (120). . The refrigeration cycle apparatus according to any one of claims 1 to 6 , wherein a discharge amount of the compressor (111) is adjusted by a voltage signal output from the control device (120). . The refrigeration cycle according to any one of claims 1 to 6 , wherein a discharge amount of the compressor (111) is adjusted by a duty ratio signal output from the control device (120). apparatus. The refrigeration cycle apparatus according to any one of claims 1 to 9 , wherein a pressure of the refrigerant compressed by the compressor (111) exceeds a critical pressure. The refrigeration cycle apparatus according to claim 10 , wherein the refrigerant is carbon dioxide.

Images