JP2003121011A - Refrigerating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently utilize the properties of a supercritical refrigerating cycle and enable various heating operation. SOLUTION: The refrigerating apparatus comprises a refrigerant circuit (10) having a compressor (21), an outdoor heat exchanger (12), an expansion mechanism (2E), and an indoor heat exchanger (11). The apparatus performs a refrigerating cycle by compressing refrigerant to a critical pressure or more of the refrigerant by the compressor (21), and then performs cooling and heating operations. A volume controller (51) for controlling the volume of the compressor (21) is provided so that the indoor air temperature becomes a target temperature. In addition, a predetermined temperature of discharging refrigerant of the compressor (21) is derived based on discharge refrigerant pressure of the compressor (21), indoor air temperature, and refrigerant evaporating temperature of the outdoor heat exchanger (12) so as to enable discharging air of the indoor heat exchanger (11) to have a target temperature. An expansion control part (52) for controlling the expansion mechanism (2E) is provided for enabling the discharging refrigerant of the compressor (21) to have a predetermined temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus for performing a vapor compression refrigerating cycle, and more particularly to a refrigerating apparatus in which the high pressure of the refrigerating cycle is equal to or higher than the critical pressure of the refrigerant.

[0002]

2. Description of the Related Art Conventionally, a refrigerating device for circulating a refrigerant in a closed circuit to perform a vapor compression refrigerating cycle has been known and is widely used as an air conditioner or the like. As a refrigerating apparatus of this type, for example, as disclosed in Japanese Patent Laid-Open No. 10-54617, a so-called super-cooling system in which carbon dioxide (CO ₂ ) is used as a refrigerant and the high pressure of the refrigeration cycle is set to be equal to or higher than the critical pressure of the refrigerant Some have a critical refrigeration cycle.

In the above refrigerating apparatus, for example, when performing a heating operation, the refrigerant compressed by the compressor is radiated by the indoor heat exchanger, the expansion mechanism decompresses the refrigerant, and the outdoor heat exchanger evaporates and compresses the refrigerant. Circulate back to the plane.

[0004]

In the above refrigeration system, how to control the operation with respect to the load, for example, the heating load becomes a problem.

That is, for example, only by controlling the capacity of the compressor based on the temperature difference between the room air temperature and the set temperature,
There is a problem that the features of the supercritical refrigeration cycle cannot be fully utilized.

In addition, there is a problem that various requests cannot be met when performing the heating operation. That is, there is a demand not only for heating the indoor air temperature to the set temperature but also for setting the blown air temperature of the indoor heat exchanger to a desired temperature. In this case, simply increasing or decreasing the capacity of the compressor
There is a problem in that blown air at a desired temperature cannot be obtained.

The present invention has been made in view of the above points, and an object thereof is to make full use of the characteristics of the supercritical refrigeration cycle and to enable various heating operations.

[0008]

Specifically, as shown in FIG. 1, the first invention comprises a refrigerant circuit (10) in which a refrigerant circulates, and the refrigerant in the refrigerant circuit (10) is compressed by a compressor ( According to 21), the refrigeration cycle is performed by compressing above the critical pressure of the refrigerant,
The target is a refrigerating apparatus that performs at least a heating operation for heating an object to be heated. Then, the compressor (2) of the refrigerant circuit (10) is adjusted so that the target temperature of the heating target becomes the target temperature.
A capacity control means (51) for controlling the capacity of 1) is provided. In addition, the discharge refrigerant pressure of the compressor (21) is adjusted by the expansion mechanism (2E) of the refrigerant circuit (10) so that the discharge refrigerant temperature of the compressor (21) based on the heating temperature of the heating object becomes a predetermined temperature. An expansion control means (52) for controlling is provided.

A second aspect of the invention is the compressor according to the first aspect, wherein the capacity control means (51) corresponds to a temperature difference between the target temperature of the object to be heated and a preset target temperature. It is configured to control the capacity of (21).
Further, the expansion control means (52) discharges the compressor (21) corresponding to the target temperature of the heating temperature of the object to be heated at the outlet of the heat exchanger (11) where the object to be heated and the refrigerant exchange heat. It is configured to determine a predetermined temperature of the refrigerant temperature.

The third aspect of the invention is directed to a compressor (21), an outdoor heat exchanger (12), an expansion mechanism (2E) and an indoor heat exchanger (11).
And a refrigerant circuit (10) having the refrigerant circuit (10), wherein the compressor (21) compresses the refrigerant to a pressure equal to or higher than the critical pressure of the refrigerant to perform a refrigeration cycle, and at least a refrigerating apparatus that performs a heating operation. There is. A capacity control means (51) is provided to control the capacity of the compressor (21) so that the room air temperature reaches the target temperature. In addition, the pressure of the refrigerant discharged from the compressor (21) is controlled by the expansion mechanism (2E) so that the temperature of the refrigerant discharged from the compressor (21) based on the temperature of the air blown from the indoor heat exchanger (11) becomes a predetermined temperature. Expansion control means (5
2) equipped.

A fourth aspect of the present invention is provided with a refrigerant circuit (10) in which a refrigerant circulates, and the refrigerant in the refrigerant circuit (10) is compressed by a compressor (21) to a pressure equal to or higher than the critical pressure of the refrigerant, thereby forming a refrigeration cycle. And a refrigerating apparatus that performs at least a heating operation for heating an object to be heated. Then, the refrigerant circuit (1
0) capacity control means (5) for controlling the capacity of the compressor (21)
1) is equipped. In addition, the heating temperature of the heating object based on the discharge refrigerant pressure of the compressor (21) in the refrigerant circuit (10), the target temperature of the heating object, and the evaporation temperature of the refrigerant in the refrigerant circuit (10). Derivates a predetermined temperature of the discharge refrigerant temperature of the compressor (21) at which is the target temperature, and the expansion mechanism (2E) of the refrigerant circuit (10) is set so that the discharge refrigerant temperature of the compressor (21) becomes the predetermined temperature. Expansion control means (52)
Is equipped with.

The fifth aspect of the invention is directed to a compressor (21), an outdoor heat exchanger (12), an expansion mechanism (2E) and an indoor heat exchanger (11).
And a refrigerant circuit (10) having the refrigerant circuit (10), wherein the compressor (21) compresses the refrigerant to a pressure equal to or higher than the critical pressure of the refrigerant to perform a refrigeration cycle, and at least a refrigerating apparatus that performs a heating operation. There is. A capacity control means (51) is provided to control the capacity of the compressor (21) so that the room air temperature reaches the target temperature. In addition, the above compressor (21)
Discharge refrigerant pressure, indoor air temperature, outdoor heat exchanger (1
Based on the refrigerant evaporation temperature of 2), the discharge air temperature of the compressor (21) at which the temperature of the air blown from the indoor heat exchanger (11) reaches the target temperature is derived, and the discharge of the compressor (21) is derived. An expansion control means (52) is provided for controlling the expansion mechanism (2E) so that the refrigerant temperature becomes a predetermined temperature.

That is, in the present invention, the capacity control means (5
1) controls the capacity of the compressor (21) of the refrigerant circuit (10) so that the target temperature of the heating target becomes the target temperature. On the other hand, the expansion control means (52) uses the expansion mechanism (2E) of the refrigerant circuit (10) so that the discharge refrigerant temperature of the compressor (21) based on the heating temperature of the object to be heated reaches a predetermined temperature. 21) Control the discharge refrigerant pressure.

That is, in the second aspect of the invention, the capacity control means (51) sets the capacity of the compressor (21) in correspondence with the temperature difference between the target temperature of the object to be heated and the preset target temperature. Control. On the other hand, the expansion control means (52) controls the discharge refrigerant temperature of the compressor (21) corresponding to the target temperature of the heating temperature of the heating object at the outlet of the heat exchanger for heat exchange between the heating object and the refrigerant. Set a predetermined temperature.

Specifically, in the third aspect of the invention, the capacity control means (51) controls the capacity of the compressor (21) so that the room air temperature reaches the target temperature. On the other hand, expansion control means (52)
The expansion mechanism (2E) controls the discharge refrigerant pressure of the compressor (21) so that the discharge refrigerant temperature of the compressor (21) based on the temperature of the air blown from the indoor heat exchanger (11) reaches a predetermined temperature.

In the fourth invention, the capacity control means (5
1) controls the capacity of the compressor (21) of the refrigerant circuit (10) so that the target temperature of the heating target becomes the target temperature. On the other hand, the expansion control means (52) is based on the discharge refrigerant pressure of the compressor (21) in the refrigerant circuit (10), the target temperature of the heating object, and the evaporation temperature of the refrigerant in the refrigerant circuit (10). Compressor (2
Derives the predetermined temperature of the discharge refrigerant temperature of 1) and
The refrigerant circuit (1
Control the expansion mechanism (2E) of 0).

Specifically, in the fifth aspect of the invention, when the indoor air temperature and the indoor set temperature are different and the indoor air temperature is lower than the indoor set temperature, the capacity control means (51) controls the capacity of the compressor (21). Increase. Conversely, when the indoor air temperature is higher than the indoor set temperature, the capacity control means (51) causes the compressor (21) to
Reduce the capacity of.

On the other hand, the expansion control means (52) includes a compressor (2
The discharge pressure, indoor air temperature, and outdoor heat exchange temperature of 1) are substituted into the pre-stored relational expression, and the discharge air temperature of the compressor (21) at which the blown air temperature of the indoor heat exchanger (11) becomes the target temperature. The predetermined temperature of is derived. Then, the control amount of the expansion mechanism (2E) is determined based on the difference between the discharge pipe temperatures and the predetermined temperature, and the expansion mechanism (2E) is controlled according to the value.

When the blowout air temperature of the indoor heat exchanger (11) is different from the target temperature and the blowout air temperature is lower than the target temperature, the expansion control means (52) controls the expansion mechanism (2E), Increase the blown air temperature. On the contrary, when the blown air temperature is higher than the target temperature, the expansion control means (52) controls the expansion mechanism (2E) to lower the blown air temperature.

[0020]

Therefore, according to the present invention, the expansion mechanism (2E) is controlled so that the temperature of the refrigerant discharged from the compressor (21) becomes a predetermined temperature based on the heating temperature of the object to be heated.
Various heating operations can be performed.

Specifically, in the third invention and the fifth invention, the temperature of the refrigerant discharged from the compressor (21) is adjusted to the expansion mechanism (2E) so that the temperature of the air blown out from the indoor heat exchanger (11) becomes the target temperature. )
Since it is controlled by, it is possible to perform various heating operations.

That is, in a refrigerating apparatus which performs a so-called supercritical refrigeration cycle, a desired discharge refrigerant temperature can be obtained by changing the discharge refrigerant pressure of the compressor (21).

For example, in the indoor heat exchanger (11), the temperature of the refrigerant changes from 100 ° C. to 35 ° C., so that the desired blown air temperature can be easily generated, and the target temperature can be changed. it can. As a result, it is possible to perform various heating operations that make full use of the characteristics of the refrigerant.

On the other hand, the suction temperature of the compressor (21) is determined by the outside air condition. Therefore, once the suction temperature is determined, the compressor (21) is controlled by the discharge refrigerant temperature based on the blown air temperature along the isentropic line. The discharge refrigerant pressure in 21) is determined. From this, in controlling the expansion mechanism (2E), it is possible to determine the control parameter and realize the control of the expansion mechanism (2E) appropriate for the operating state.

According to the first to third inventions,
For example, without detecting the discharge refrigerant pressure of the compressor (21), the indoor air temperature, and the outdoor heat exchange temperature, the expansion mechanism (2E)
Can be controlled, so that the control can be simplified.

[0026]

Embodiment 1 of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, the first embodiment is an air conditioner composed of a refrigerating apparatus according to the present invention. This air conditioner includes a refrigerant circuit (10) and a controller (50), and is configured to switch between cooling operation and heating operation.

The refrigerant circuit (10) includes an indoor heat exchanger.
(11), outdoor heat exchanger (12), first four-way switching valve (13),
Second four-way switching valve (14), compressor (21), expander (22),
Expansion valve (23), and receiver tank (31)
There is. In the refrigerant circuit (10), the expander (22) and the expansion valve
(23) are arranged in series, and these are refrigerant expanders.
Structure (2E). Also, in the refrigerant circuit (10)
Is carbon dioxide (CO ₂) Is filled as a refrigerant
It

The indoor heat exchanger (11) is a utilization side heat exchanger and is constituted by a so-called cross fin type fin-and-tube heat exchanger. Although not shown, the indoor heat exchanger (11) is supplied with indoor air by an indoor fan. The indoor heat exchanger (11) exchanges heat between the supplied indoor air and the refrigerant in the refrigerant circuit (10). One end of the indoor heat exchanger (11) is pipe-connected to the first port of the first four-way switching valve (13), and the other end is the first port of the second four-way switching valve (14). Piped to the port.

The outdoor heat exchanger (12) is a heat source side heat exchanger, and is constituted by a so-called cross fin type fin-and-tube heat exchanger. Although not shown, the outdoor heat exchanger (12) is supplied with outdoor air by an outdoor fan. The outdoor heat exchanger (12) exchanges heat between the supplied outdoor air and the refrigerant in the refrigerant circuit (10). One end of the outdoor heat exchanger (12) is pipe-connected to the second port of the first four-way switching valve (13), and the other end is the second port of the second four-way switching valve (14). Piped to the port.

The compressor (21) is, for example, a rolling piston type fluid machine. The compressor (21) compresses the sucked refrigerant (CO ₂ ) up to its critical pressure or higher. The discharge side of the compressor (21) is connected to the third port of the first four-way switching valve (13) by piping, and the suction side thereof is the fourth port of the first four-way switching valve (13). Piped to the port.

The expander (22) is composed of, for example, a scroll type fluid machine. That is, the expander (22) is composed of, for example, a positive displacement fluid machine with a constant internal volume ratio. The inflow side of the expander (22) is connected to the third port of the second four-way switching valve (14) by piping, and the outflow side thereof is connected to the receiver tank (31) by piping. The fluid machine forming the expander (22) is not limited to the scroll type as long as the internal volume ratio is constant, and may be, for example, a screw type, a gear type, or a roots type.

The receiver tank (31) is a vertically long and cylindrical hermetic container, and is configured to store an intermediate pressure refrigerant. The receiver tank (31) is connected to the inflow side of the expansion valve (23) by piping. Thus, in the refrigerant circuit (10), the expansion valve (23) is provided on the downstream side of the expander (22).

The expansion valve (23) is constructed so that its opening can be changed by rotating the valve body with a pulse motor or the like. The outflow side of the expansion valve (23) is connected to the fourth port of the second four-way switching valve (14) by piping.

As described above, the first four-way switching valve (13)
Has a first port for the indoor heat exchanger (11), a second port for the outdoor heat exchanger (12), and a third port for the compressor (2).
On the discharge side of 1), the fourth port is connected to the suction side of the compressor (21). This 1st four way switching valve (13)
Indicates that the first port is in communication with the third port and the second port is in communication with the fourth port (the state shown by the solid line in FIG. 1), and the first port is in communication with the fourth port. In addition, the second port is configured to switch to a state in which the second port communicates with the third port (state shown by a broken line in FIG. 1).

On the other hand, the second four-way switching valve (14) has the first
Port to the indoor heat exchanger (11), the second port to the outdoor heat exchanger (12), the third port to the inflow side of the expander (22), and the fourth port to the expansion valve (23). ) Are connected to the outflow side, respectively. In the first four-way switching valve (13), the first port communicates with the third port and the second port has the fourth port.
The state of communicating with the port of (the state shown by the solid line in FIG. 1),
The first port communicates with the fourth port and the second port communicates with the third port (state shown by a broken line in FIG. 1).

In this embodiment, the expander (22) and the compressor motor (24) are connected to the drive shaft of the compressor (21). This compressor (21) is an expander (22)
It is rotatably driven by both the power obtained by the expansion of the refrigerant in (1) and the power obtained by energizing the compressor motor (24). Further, the compressor motor (24) is supplied with AC power of a predetermined frequency from an inverter (not shown). Then, the compressor (21) changes the frequency of the electric power supplied to the compressor motor (24),
The capacity is variable.

The air conditioner of this embodiment is provided with temperature and pressure sensors. The pipe connected to the discharge side of the compressor (21) has a discharge pipe temperature T _d which is the discharge refrigerant temperature.
A discharge pipe temperature sensor (61) for detecting the discharge pressure and a discharge pressure sensor (62) for detecting the discharge pressure p _d which is the discharge refrigerant pressure are provided. The indoor heat exchanger (11) is provided with an indoor heat exchange temperature sensor (63) for detecting the indoor heat exchange temperature T _hi . The outdoor heat exchanger (12) is provided with an outdoor heat exchange temperature sensor (64) for detecting the outdoor heat exchange temperature T _ho .

Further, the air conditioner has an indoor air temperature T _r.
A room temperature sensor for detecting (65), the outdoor air temperature T _o
Outdoor temperature sensor (66) for detecting
An outlet temperature sensor (66) for detecting the outlet air temperature T _s which is the temperature of the air blown out from 1) is provided. The indoor temperature sensor (65) detects the indoor air temperature _Tr, which is the target temperature, because the indoor air temperature _Tr , which is the temperature of the indoor air, is the target temperature of the heating target.
The outlet temperature sensor (66), since the outlet air temperature T _s is the heating temperature of the heating object, for detecting the outlet air temperature T _s is the heating temperature.

The detection values of the above-mentioned sensors are input to the controller (50). In addition, the indoor set temperature T _r.set set by the user is input to the controller (50) and the outlet set temperature T _{s.set is} set.
Has been entered. And the controller (50)
Is configured to adjust the capacity of the compressor (21) and the opening degree of the expansion valve (23) based on the detection value of each sensor, the indoor set temperature T _r.set and the blowout set temperature T _s.set. Has been done. The indoor set temperature T _r.set is the target temperature of the target temperature of the heating target, and the blowout set temperature T _s.set is the target temperature of the heating temperature of the heating target.

The controller (50) uses the indoor heat exchange temperature T _hi as the refrigerant evaporation temperature during cooling and the outdoor heat exchange temperature T _ho as the refrigerant evaporation temperature during heating, thereby performing a predetermined operation. Is configured to do. Therefore, the indoor heat exchange temperature sensor (63) is
The indoor heat exchanger (11) is installed at a position where the refrigerant is not superheated during cooling. The outdoor heat exchange temperature sensor (64) is installed at a position in the outdoor heat exchanger (12) where the degree of superheat of the refrigerant does not occur during heating.

The controller (50) includes a capacity control section (51) which is capacity control means (51) and an expansion control means (52).
And an expansion control section (52).

The capacity control section (51) is an indoor temperature sensor.
Indoor air temperature T detected by (65) _rAnd indoor set temperature T
_r.setIncrease or decrease the capacity of the compressor (21) based on the temperature difference between
It is configured to control.

The expansion control section (52) is arranged so that the discharge pressure of the compressor (21), the target temperature of the object to be heated, and the refrigerant circuit (10).
Derives a predetermined temperature of the discharge refrigerant temperature of the compressor (21) at which the heating temperature of the object to be heated becomes the target temperature based on the evaporation temperature of the refrigerant in, and the discharge refrigerant temperature of the compressor (21) becomes the predetermined temperature. To control the expansion mechanism (2E) of the refrigerant circuit (10).

Specifically, the expansion control section (52) is based on the discharge pressure p _d of the compressor (21), the indoor air temperature _Tr, and the outdoor heat exchange temperature T _ho during the heating operation. Discharge pipe temperature T _d of the compressor (21) at which the blown air temperature T _{s of the} indoor heat exchanger (11) becomes a blowout set temperature T _s.set which is a target temperature.
Of the discharge pipe temperature T _d of the compressor (21)
Expansion valve (23) of the expansion mechanism (2E) so that the temperature becomes a predetermined temperature.
To control the opening.

-Driving operation- <Heating operation> Regarding the heating operation of the air conditioner,
This will be described with reference to FIGS. 1 and 2. Note that FIG. 2 shows the refrigeration cycle in the air conditioner on a Mollier diagram (pressure-enthalpy diagram).

First, during the heating operation, the first four-way switching valve (13) and the second four-way switching valve (14) are switched to the state shown by the solid line in FIG. When the compressor (21) is driven in this state, the refrigerant circulates in the refrigerant circuit (10) to perform the refrigeration cycle. At that time, the indoor heat exchanger (11) functions as a radiator, and the outdoor heat exchanger (12) functions as an evaporator.

Specifically, the compressor (21) discharges the high-pressure refrigerant in the state of the point in FIG. The pressure P _H of this high-pressure refrigerant is higher than its critical pressure P _C.
The refrigerant discharged from the compressor (21) is introduced into the indoor heat exchanger (11) through the first four-way switching valve (13).

In the indoor heat exchanger (11), the introduced high pressure refrigerant exchanges heat with indoor air. Due to this heat exchange, the high-pressure refrigerant radiates heat to the room air, and its enthalpy decreases from the point state to the point state. The high-pressure refrigerant in the point state is introduced into the expander (22) through the second four-way switching valve (14). On the other hand, the indoor air heated by the high-pressure refrigerant in the indoor heat exchanger (11) is sent back to the room as conditioned air.

The refrigerant in the point state after radiating heat in the indoor heat exchanger (11) expands in the expander (22), and its pressure and enthalpy decrease to the point state. That is, in the expander (22), the high pressure refrigerant expands to become an intermediate pressure refrigerant having a pressure P _M. This intermediate pressure refrigerant has a critical pressure P
_It is at a lower pressure than _C and is in a gas-liquid two-phase state. Then, the intermediate-pressure refrigerant in the gas-liquid two-phase state flows out from the expander (22) and is sent to the expansion valve (23) through the receiver tank (31).

In the expansion valve (23), the intermediate pressure refrigerant is decompressed, and the pressure thereof decreases from the point state to the point state. That is, by passing through the expansion valve (23), the intermediate pressure refrigerant is decompressed and becomes a low pressure refrigerant having a pressure P _L. The low-pressure refrigerant in the point state is introduced into the outdoor heat exchanger (12) through the second four-way switching valve (14).

In the outdoor heat exchanger (12), the introduced low pressure refrigerant exchanges heat with outdoor air. By this heat exchange, the low-pressure refrigerant absorbs heat from the outdoor air, and its enthalpy increases from the point state to the point state. The low-pressure refrigerant in the point state flows out from the outdoor heat exchanger (12) and is sent to the compressor (21) through the first four-way switching valve (13).

The refrigerant in the point state sucked into the compressor (21) is compressed into the point state. That is, in the compressor (21), the low-pressure refrigerant having the pressure P _L is compressed to generate the pressure P _H.
It becomes a high pressure refrigerant. This high-pressure refrigerant is transferred to the compressor (2
It is sent from 1) to the indoor heat exchanger (11).

As described above, in the expander (22), the pressure and enthalpy of the refrigerant decrease from point to point. Then, in the expander (22), power corresponding to the enthalpy difference between the points is obtained, and the obtained power is used to drive the compressor (21).

<Cooling Operation> The operation of the air conditioner during the cooling operation will be described with reference to FIGS. 1 and 2.

During the cooling operation, the first four-way selector valve (1
3) and the second four-way switching valve (14) are switched to the state shown by the broken line in FIG. When the compressor (21) is driven in this state, the refrigerant circulates in the refrigerant circuit (10) to perform the refrigeration cycle. At that time, the outdoor heat exchanger (12) functions as a radiator, and the indoor heat exchanger (11) functions as an evaporator.

Specifically, the high pressure refrigerant in the state of the point in FIG. 2 is discharged from the compressor (21). The pressure P _H of this high-pressure refrigerant is higher than its critical pressure P _C.
The refrigerant discharged from the compressor (21) is introduced into the outdoor heat exchanger (12) through the first four-way switching valve (13).

In the outdoor heat exchanger (12), the introduced high pressure refrigerant exchanges heat with outdoor air. By this heat exchange, the high-pressure refrigerant radiates heat to the outdoor air, and its enthalpy decreases from the point state to the point state. The high-pressure refrigerant in the point state is introduced into the expander (22) through the second four-way switching valve (14).

The refrigerant in the point state after radiating heat in the outdoor heat exchanger (12) expands in the expander (22), and its pressure and enthalpy decrease to the point state. That is, in the expander (22), the high pressure refrigerant expands to become an intermediate pressure refrigerant having a pressure P _M. This intermediate pressure refrigerant has a critical pressure P
_It is at a lower pressure than _C and is in a gas-liquid two-phase state. Then, the intermediate-pressure refrigerant in the gas-liquid two-phase state flows out from the expander (22) and is sent to the expansion valve (23) through the receiver tank (31).

In the expansion valve (23), the intermediate pressure refrigerant is decompressed, and the pressure thereof decreases from the point state to the point state. That is, by passing through the expansion valve (23), the intermediate pressure refrigerant is decompressed and becomes a low pressure refrigerant having a pressure P _L. The low-pressure refrigerant in the point state is introduced into the indoor heat exchanger (11) through the second four-way switching valve (14).

In the indoor heat exchanger (11), the introduced low pressure refrigerant exchanges heat with indoor air. By this heat exchange, the low-pressure refrigerant absorbs heat from the indoor air, and its enthalpy increases from the point state to the point state. The low-pressure refrigerant in the state of point flows out from the indoor heat exchanger (11) and is sent to the compressor (21) through the first four-way switching valve (13). On the other hand, the indoor air cooled by the low-pressure refrigerant in the indoor heat exchanger (11) is sent back to the room as conditioned air.

The refrigerant in the point state sucked into the compressor (21) is compressed into the point state. That is, in the compressor (21), the low-pressure refrigerant having the pressure P _L is compressed to generate the pressure P _H.
It becomes a high pressure refrigerant. This high-pressure refrigerant is transferred to the compressor (2
It is sent from 1) to the outdoor heat exchanger (12).

As described above, in the expander (22), the pressure and enthalpy of the refrigerant decrease from point to point. Then, in the expander (22), power corresponding to the enthalpy difference between the points is obtained, and the obtained power is used to drive the compressor (21).

-Control operation of controller-During the heating operation or the cooling operation, the controller (50) performs a predetermined control operation as shown below to operate the operating frequency of the compressor (21) and the expansion valve (23). ) Is adjusted. Accordingly, the values of the high pressure P _H and the low pressure P _L of the refrigeration cycle fluctuate during the heating operation and the cooling operation. In other words, during operation of the air conditioner, the high pressure P in the refrigeration cycle
The ratio P _H / P _L of _H and the low pressure P _L is changed.

In this embodiment, since the expander (22) is composed of a scroll type fluid machine, the expander (22)
, The pressure ratio P _H / P _M of the refrigerant at the inlet and outlet of the expander (22) is constant and does not change. On the other hand, when the opening degree of the expansion valve (23) is changed, the pressure ratio P _M / P _L of the refrigerant at the inlet and outlet of the expansion valve (23) changes. Therefore, even if the expansion ratio of the expander (22) is constant, by adjusting the opening degree of the expansion valve (23), the high pressure P _H and the low pressure P _L of the refrigeration cycle are set to values suitable for the operating state. To be done.

<Control Operation During Heating Operation> During heating operation, the controller (50) performs a predetermined control operation to adjust the capacity of the compressor (21) and the opening degree of the expansion valve (23). Therefore, the control at the time of heating activation will be described based on FIG.

In step ST1, control regions are divided based on the input indoor air temperature T _r and outdoor air temperature T _o, and the compressor (21) is operated from the table stored in advance according to the divided regions. Determine the initial value of the frequency F _comp.set .

[0068] Subsequently, the flow proceeds to step ST2, the pre-stores an initial value F _Comp.Set the determined operating frequency and the outdoor air temperature T _o is substituted into equation, the initial opening of the expansion valve (23) Determine the value Ev _set .

Then, the process proceeds to step ST3, and the opening degree of the expansion valve (23) is _set to the initial value Ev _set . Then, the process proceeds to step ST4 and the frequency F is sent to the compressor motor (24).
AC power of _comp.set is supplied to start the compressor (21).

On the other hand, during the heating operation, the capacity control section (51) of the controller (50) controls the compressor (21), and the expansion control section (52) controls the expansion mechanism (2E).

Therefore, the control of the compressor (21) will be described with reference to FIG. 4. In step ST11, it is determined whether the indoor air temperature T _r is the same as the indoor set temperature T _r.set . When the indoor air temperature T _r is equal to the indoor set temperature T _r.set , the current compressor (21)
Since the capacity is satisfied, the determination in step ST11 is YES and the determination in step ST11 is repeated.

The indoor air temperature T_rAnd indoor set temperature T
_r.setIf and are different temperatures,
The determination is NO, the process proceeds to step ST12, and the indoor air
Temperature T _rIs the indoor set temperature T_r.setDetermine if higher
It The indoor air temperature T_rIs the indoor set temperature T_r.setHigher
If not, that is, the indoor air temperature T_rIs the indoor set temperature
T_r.setIf lower, the determination in step ST12 is NO
Then, the process proceeds to step ST13. And the above capacity system
The control section (51) outputs a frequency up command for the compressor (21).
Then, the capacity of the compressor (21) is increased, and the step ST
Returning to 11, the above operation is repeated.

The indoor air temperature T _r is the indoor set temperature T
_When it is higher than _r.set , the determination in step ST12 is YES.
Then, the process proceeds to step ST14. Then, the capacity control section (51) outputs a frequency down command of the compressor (21) to reduce the capacity of the compressor (21), and the step ST
Returning to 11, the above operation is repeated.

Next, regarding the control of the expansion valve (23),
Explaining based on FIG. 5, in step ST21, it is determined whether or not the _blown air temperature T _s of the indoor heat exchanger (11) is the same as the blowout set temperature T _s.set which is the target temperature. When the blowout air temperature T _s and the blowout set temperature T _s.set are the same, since the current opening of the expansion valve (23) is satisfied, the determination in step ST21 is YES and the determination in step ST21 is Repeat the judgment.

The blown air temperature T_sAnd outlet set temperature T
_s.setIf and are different temperatures,
The determination is NO, the process proceeds to step ST22, and the blown air
Temperature T _sIs the outlet set temperature T_s.setDetermine if higher
It The blown air temperature T_sIs the outlet set temperature T_s.setHigher
If not, that is, the blown air temperature T_sIs the set temperature
T_s.setIf lower, the determination in step ST22 is NO
Then, the process proceeds to step ST23. And the expansion system
The control part (52) outputs a throttle command for the expansion valve (23) and expands it.
Reduce the valve (23) opening and return to step ST21 above.
Then, the above operation is repeated.

The outlet air temperature T _s is the outlet set temperature T
_If higher than _s.set , the determination in step ST22 is YES
Then, the process proceeds to step ST24. Then, the expansion control section (52) outputs an opening command for the expansion valve (23) to increase the opening degree of the expansion valve (23), returns to step ST21, and repeats the above operation.

Therefore, the change control of the expansion valve (23) will be described. The discharge pressure p _d of the compressor (21), the indoor air temperature T _r , and the outdoor heat exchange temperature T _ho are substituted into a relational expression stored in advance. Then, the temperature T _s of the air blown out from the indoor heat exchanger (11)
_Of the discharge pipe temperature T _d of the compressor (21) at which the discharge set temperature T _s.set is derived. Then, the opening degree operation amount ΔEv of the expansion valve (23) is determined based on the difference between the discharge pipe temperature T _{d and the} predetermined temperature T _d.set , and the expansion valve (23) is determined according to the value.
Change the opening of.

<Control Operation During Cooling Operation> During the cooling operation, the controller (50) performs a predetermined control operation to adjust the capacity of the compressor (21) and the opening degree of the expansion valve (23).

When the cooling operation is started, when the cooling operation is started,
Be conducted in a manner similar to the heating, performs control regions divided based on the room air temperature T _r and the outside air temperature T _o, in accordance with the area division, the operating frequency of the compressor (21) from the table stored in advance Determine the initial value F _comp.set . Subsequently, pre-stores an initial value F _Comp.Set and the outdoor air temperature T _o of the determined operation frequency substituted into equation to determine the initial value Ev _{The set} of opening of the expansion valve (23). After that, the opening degree of the expansion valve (23) is _set to the initial value Ev _set , and AC power having the frequency F _comp.set is supplied to the compressor motor (24) to start the compressor (21).

On the other hand, during the cooling operation, the control of the compressor (21) is performed in the same manner as during heating. That is, when the indoor air temperature T _r and the indoor set temperature T _r.set are the same, since the current capacity of the compressor (21) is satisfied, the capacity is maintained as it is. Indoor air temperature T _r
Is lower than the indoor set temperature _Tr.set , the capacity control section (51) increases the capacity of the compressor (21). Conversely, when the indoor air temperature T _r is higher than the room temperature setting T _R.Set, the capacity control section (51) reduces the capacity of the compressor (21).

The control of the expansion valve (23) is performed by substituting the discharge pressure p _d of the compressor (21), the indoor air temperature T _r , and the indoor heat exchange temperature T _hi into a relational expression which is stored in advance to perform compression. Machine (2
The predetermined temperature T _d.set of the discharge pipe temperature T _d of 1) is derived. Then, the opening degree operation amount ΔEv of the expansion valve (23) is determined based on the difference between the discharge pipe temperature T _{d and the} predetermined temperature T _d.set , and the opening degree of the expansion valve (23) is changed according to the value.

-Effects of First Embodiment- As described above, according to the present embodiment, the blown air temperature T _s.
Since the discharge pipe temperature T _d is controlled so that the temperature becomes the blowout set temperature T _{ss et} , various heating operations can be performed.

That is, in a refrigerating apparatus for performing a so-called supercritical refrigeration cycle, as shown in FIG.
A desired discharge pipe temperature p _d can be obtained by changing the discharge pressure p _d in 1).

That is, in the Mollier diagram of FIG. 6, the isotherms are as shown by A1 to A4, and the discharge pressure p _d of the compressor (21) is changed to change the discharge pipe temperature T of the compressor (21). _d changes from B3 to B1.

When the discharge pipe temperature T _d, which is the refrigerant temperature on the inlet side of the indoor heat exchanger (11), is B3 to B1, the refrigerant and the indoor air exchange heat, and the indoor heat exchanger (11) is heated. The refrigerant temperature on the outlet side greatly changes to C3 to C1.

For example, if the isotherm A1 is 100 ° C. and the isotherm A3 is 35 ° C., the refrigerant in the indoor heat exchanger (11) changes from 100 ° C. to 35 ° C. Therefore, it is possible to easily generate a desired blowout air temperature T _s, and it is possible to deal with a change in the blowout set temperature T _s.set . As a result, it is possible to perform various heating operations that make full use of the characteristics of the refrigerant.

[0087] On the other hand, the suction temperature D1 and D2 of the compressor (21) is located on the line S that superheat is constant, determined by the refrigerant in the outdoor heat exchanger (12) and the outside air temperature T _o. That is, the suction temperatures D1 and D2 of the compressor (21) are determined by the outside air conditions. And
In the compressor (21), the refrigerant undergoes isentropic change, so when the suction temperature D1 or D2 of the compressor (21) is determined, the isentropic line E1 or E2 is determined. As a result, when the outlet air temperature T _s in based discharge pipe temperature T _d (B1 to B3) is determined, so that the discharge pressure p _d of the compressor (21) is determined. From this, in controlling the opening degree of the expansion valve (23), the parameters can be set, and the opening degree control of the expansion valve (23) appropriate for the operating state can be realized.

[0088]

Second Embodiment Next, a second embodiment of the present invention will be described in detail with reference to the drawings.

In this embodiment, the refrigerant circuit (1
The bypass pipe (35) is provided in (0).

One end of the bypass pipe (35) is connected between the third port of the second four-way switching valve (14) and the inflow side of the expander (22), and the other end is connected to the expansion valve. It is connected between (23) and the fourth port of the second four-way switching valve (14). That is, the inflow side and the outflow side of the expansion mechanism (2E) including the expander (22) and the expansion valve (23) can communicate with each other through the bypass pipe line (35).

The bypass pipe (35) is provided with a bypass valve (36) which is a flow control valve. The bypass valve (36) is configured so that its opening can be changed by rotating the valve body with a pulse motor or the like.
When the opening degree of the bypass valve (36) is changed, the flow rate of the refrigerant flowing through the bypass pipe line (35) changes. Further, when the bypass valve (36) is fully closed, the bypass pipe line (35) is shut off and all the refrigerant is sent to the expander (22).

Further, the displacement volumes of the compressor (21) and the expander (22) in this embodiment are set so that the displacement ratio of both becomes a value suitable for the standard cooling condition. . That is, under the standard cooling condition, the compressor (21) is configured so that the refrigeration cycle can be performed with the expansion valve (23) fully opened and the bypass valve (36) fully closed.
And the expander (22) is designed.

Therefore, during the heating operation, the expansion valve (2
The opening degree of 3) is appropriately adjusted, the bypass valve (36) is fully closed, and the same operation as in the first embodiment is performed.

On the other hand, during the cooling operation, the expander (22)
When the displacement volume of is too small with respect to the required value, the expansion valve (23) is fully opened and the opening degree of the bypass valve (36) is adjusted appropriately.

Further, during the cooling operation, if the displacement required for the expander (22) matches the design value, the bypass valve (36) is fully closed. In this case, all of the refrigerant flowing out of the outdoor heat exchanger (12) passes through the expander (22) and the expansion valve (23) and flows into the indoor heat exchanger (11). Other configurations, operations, and effects are similar to those of the first embodiment.

[0096]

Third Embodiment Next, a third embodiment of the present invention will be described in detail with reference to the drawings.

In this embodiment, the expansion control unit (52) of the first and second embodiments uses the discharge pressure p _d of the compressor (21), the indoor air temperature T _r, and the outdoor heat exchange temperature T _{ho. Instead} of controlling the expansion mechanism (2E), the expansion mechanism (2E) is controlled by the temperature difference between the _blown air temperature T _s and the blowout set temperature T _s.set which is the target temperature. is there.

The expansion control means (52) controls the expansion mechanism (2E) of the refrigerant circuit (10) so that the discharge refrigerant temperature of the compressor (21) based on the heating temperature of the object to be heated becomes a predetermined temperature. The discharge refrigerant pressure of (21) is controlled. That is, the expansion control means (52) sets the predetermined temperature of the refrigerant discharged from the compressor (21) in correspondence with the target temperature of the heating temperature of the object to be heated at the outlet of the heat exchanger indoor heat exchanger (11). It has established.

Specifically, the expansion control means (52) includes a compressor (2) based on the temperature T _s of air blown from the indoor heat exchanger (11).
The discharge pressure p _d of the compressor (21) is controlled by the expansion mechanism (2E) so that the discharge pipe temperature T _d of 1) becomes a predetermined temperature.

Therefore, according to this embodiment, the expansion mechanism (2E) is controlled without detecting the discharge pressure p _d of the compressor (21), the indoor air temperature T _r, and the outdoor heat exchange temperature T _ho. Therefore, the control can be simplified. Other configurations, operations and effects are the same as those of the first and second embodiments.
Is the same as.

[0101]

Other Embodiments of the Invention In the above embodiment, the expansion mechanism (2E) is provided with the expansion valve (23) and the expander (22). However, the present invention does not include the expansion mechanism (2E). Expansion valve (2
You may comprise only 3).

The refrigerant circuit (10) of the present invention is not limited to the first and second embodiments.

The refrigerant in the refrigerant circuit (10) is not limited to carbon dioxide (CO ₂ ), and may be any refrigerant that constitutes a supercritical refrigeration cycle.

Further, the air conditioner of the present embodiment is assumed to perform the heating / cooling operation, but the present invention may be a heating machine for performing only the heating operation.

In addition to the air conditioner, the refrigerating apparatus of the present invention is
It may be applied such as a water heater.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of an air conditioner according to a first embodiment of the present invention.

FIG. 2 is a Mollier diagram showing a refrigeration cycle of the air conditioner according to the first embodiment.

FIG. 3 is a control flow diagram showing start-up control of the air conditioner according to the first embodiment.

FIG. 4 is a control flow chart showing capacity control of the compressor during heating operation of the air conditioner according to the first embodiment.

[Fig. 5] Fig. 5 is a control flow diagram showing opening degree control of an expansion valve during heating operation of the air conditioner according to the first embodiment.

FIG. 6 is a Mollier diagram for explaining a discharge pipe temperature control picture of the air conditioner according to the first embodiment.

FIG. 7 is a refrigerant circuit diagram of the air conditioner according to the second embodiment of the present invention.

[Explanation of symbols]

10 Refrigerant circuit 11 Indoor heat exchanger 12 outdoor heat exchanger 13 1st four-way switching valve 14 Second four-way switching valve 21 compressor 22 expander 23 Expansion valve 35 bypass line 50 controller 51 Capacity control unit (Capacity control means) 52 Expansion control unit (expansion control means)

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F25B 1/00 371 F25B 1/00 371F 395 395Z 9/06 9/06 J

Claims (5)

[Claims] 1. A refrigerant circuit (10) in which a refrigerant circulates,
A refrigerating apparatus for performing at least a heating operation of heating a heating target by performing a refrigeration cycle by compressing the refrigerant of the refrigerant circuit (10) by a compressor (21) to a critical pressure of the refrigerant or higher, The capacity control means (51) for controlling the capacity of the compressor (21) of the refrigerant circuit (10) so that the target temperature of the object becomes the target temperature, and the compressor (21) based on the heating temperature of the heating target object. An expansion control means (52) for controlling the discharge refrigerant pressure of the compressor (21) by the expansion mechanism (2E) of the refrigerant circuit (10) so that the discharge refrigerant temperature becomes a predetermined temperature. Refrigeration equipment. 2. The capacity control means (51) according to claim 1, wherein the target temperature of the object to be heated is:
Depending on the temperature difference from the preset target temperature, the compressor (2
1) is configured to control the capacity, and the expansion control means (52) sets the target temperature of the heating temperature of the heating object at the outlet of the heat exchanger (11) for heat exchange between the heating object and the refrigerant. Correspondingly, the refrigerating apparatus is configured to determine a predetermined temperature of the refrigerant discharged from the compressor (21). 3. A refrigerant circuit (10) comprising a compressor (21), an outdoor heat exchanger (12), an expansion mechanism (2E) and an indoor heat exchanger (11), and a refrigerant of the refrigerant circuit (10). The compressor (21)
Is a refrigeration apparatus that performs a refrigeration cycle by compressing the refrigerant to a pressure equal to or higher than the critical pressure, and performs at least heating operation, and capacity control means for controlling the capacity of the compressor (21) so that the indoor air temperature reaches a target temperature. (51) and the discharge refrigerant pressure of the compressor (21) by the expansion mechanism (2E) so that the discharge refrigerant temperature of the compressor (21) based on the blown air temperature of the indoor heat exchanger (11) becomes a predetermined temperature. An expansion control means (52) for controlling the refrigeration system. 4. A refrigerant circuit (10) for circulating a refrigerant,
A refrigerating apparatus for performing at least a heating operation of heating a heating target by performing a refrigeration cycle by compressing the refrigerant of the refrigerant circuit (10) by a compressor (21) to a critical pressure of the refrigerant or higher, Capacity control means (51) for controlling the capacity of the compressor (21) of the refrigerant circuit (10) so that the target temperature of the object becomes the target temperature, and the refrigerant discharged from the compressor (21) in the refrigerant circuit (10). Based on the pressure, the target temperature of the heating target, and the evaporation temperature of the refrigerant in the refrigerant circuit (10), the predetermined temperature of the discharge refrigerant temperature of the compressor (21) at which the heating temperature of the heating target becomes the target temperature is set. And an expansion control means (52) for controlling the expansion mechanism (2E) of the refrigerant circuit (10) so that the refrigerant discharged from the compressor (21) reaches a predetermined temperature. Refrigeration equipment. 5. A refrigerant circuit (10) comprising a compressor (21), an outdoor heat exchanger (12), an expansion mechanism (2E) and an indoor heat exchanger (11), and a refrigerant of the refrigerant circuit (10). The compressor (21)
Is a refrigeration apparatus that performs a refrigeration cycle by compressing the refrigerant to a pressure equal to or higher than the critical pressure, and performs at least heating operation, and capacity control means for controlling the capacity of the compressor (21) so that the indoor air temperature reaches a target temperature. (51), the discharge refrigerant pressure of the compressor (21), the room air temperature,
Based on the refrigerant evaporation temperature of the outdoor heat exchanger (12), the predetermined temperature of the refrigerant discharged from the compressor (21) at which the temperature of the air blown out from the indoor heat exchanger (11) reaches the target temperature is derived, and the compressor is discharged. A refrigeration system comprising: an expansion control means (52) for controlling the expansion mechanism (2E) so that the discharge refrigerant temperature of (21) becomes a predetermined temperature.