JPH11337234A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve comfortability by preventing a sucking pressure of a compressor from dropping below an allowable value during the defrosting to shorten the defrosting time while securing the reliability of the compressor. SOLUTION: A frequency computation control means is provided for an operating compressor. During the defrosting operation, if a sucking pressure detected by a sucking pressure sensor 22 is higher than a predetermined sucking pressure value, the operation frequency of a variable speed compressor 1 is computed with a predetermined discharge pressure value as target. If the sucking pressure detected by the absorption pressure sensor 22 is lower than the predetermined sucking pressure value, the operation frequency of the variable speed compressor 1 is computed with the predetermined sucking pressure value as target.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling and heating apparatus, and more particularly to a reverse cycle defrost operation.

[0002]

2. Description of the Related Art The prior art is disclosed in Japanese Patent Application Laid-Open No. 5-7183.
There is the one disclosed in Japanese Patent Publication No.

Hereinafter, description will be made with reference to the drawings. FIG.
At 0, 1 is a variable speed compressor, 2 is a four-way valve, 3 is an accumulator, 4 is an outdoor heat exchanger, 5 is an outdoor expansion valve, 6 is an indoor heat exchanger, and 7 is an indoor expansion valve via a refrigerant pipe. To form a connected refrigeration cycle.

[0004] The reference numeral 20 denotes an outdoor heat exchanger 4 during a heating operation.
Is a temperature sensor for detecting the refrigerant temperature on the downstream side of the compressor, and 22 is a suction pressure sensor for detecting the suction pressure of the variable speed compressor 1.

Reference numeral 10 denotes a defrost start / end control means for starting or ending the defrosting operation by switching the four-way valve 2 according to the refrigerant temperature detected by the temperature sensor 20. Reference numeral 11 denotes a suction pressure detected by the suction pressure sensor 22 below a predetermined value. The frequency reduction means reduces the capacity of the variable speed compressor 1 when the refrigerant temperature detected by the temperature sensor 20 becomes equal to or higher than a predetermined value. The defrosting start / end control means 10 and the frequency reduction means 11 constitute a control device 19.

[0006] The operation of the air conditioner thus configured will be described. During the cooling operation, the high-temperature and high-pressure gas compressed by the variable speed compressor 1 is supplied to the outdoor heat exchanger 4 through the four-way valve 2.
The refrigerant exchanges heat with the outdoor air to condense into a high-pressure liquid refrigerant, passes through the outdoor expansion valve 5, is decompressed by the indoor expansion valve 7, is sent to the indoor heat exchanger 6 as a low-temperature, low-pressure two-phase refrigerant, and The heat is absorbed and cooled to evaporate. The evaporated refrigerant gas is supplied to the four-way valve 2
The gas is separated into gas and liquid by the accumulator 3 and returned to the variable speed compressor 1.

During the heating operation, the high-temperature and high-pressure refrigerant gas compressed by the variable speed compressor 1 is sent to the indoor heat exchanger 6 via the four-way valve 2 to radiate heat to the indoor air to be condensed.

Then, the refrigerant passes through the indoor expansion valve 7 and is decompressed by the outdoor expansion valve 5 to become a high-temperature and low-pressure two-phase refrigerant. The gas is separated into gas and liquid by the accumulator 3 and the low-temperature low-pressure gas returns to the variable speed compressor 1.

At this time, when the refrigerant temperature detected by the temperature sensor 20 becomes equal to or lower than a predetermined value, the defrost start / end control means 10 switches the four-way valve 2 and operates the variable speed compressor 1 at a predetermined frequency. Then, the defrosting operation for the outdoor heat exchanger 4 is started.

During the defrosting operation, when the pressure detected by the suction pressure sensor 22 becomes lower than a predetermined value and the refrigerant temperature detected by the temperature sensor 20 becomes higher than a predetermined value, the frequency of the variable speed compressor 1 is reduced by a certain frequency to reduce the capacity. To reduce.

In this way, the low-pressure side pressure is prevented from lowering and a vacuum operation state is avoided, and the defrosting operation is performed without difficulty while protecting the variable speed compressor 1.

[0012]

In the above-described conventional configuration, the width of frequency reduction is constant regardless of the suction pressure.
The effect of preventing the reduction of the suction pressure due to the frequency reduction cannot catch up with the speed of the reduction of the suction pressure, resulting in a control delay, and the suction pressure may be lower than the allowable value. There was a problem to say.

Further, in the conventional configuration, since there is no means for increasing the frequency of the variable speed compressor 1 during the defrosting operation, the defrosting performance is reduced while the defrosting time is prolonged and the comfort is deteriorated. There was a problem to call.

Furthermore, in the conventional configuration, immediately after the start of defrosting, the inside of the variable speed compressor 1 is in a forming state, and the amount of oil discharged from the variable speed compressor 1 is increased by the forming. Depending on the setting of the frequency, the oil level decreases and the required minimum oil amount cannot be secured, and the variable speed compressor 1
There was a problem that the reliability of the system could not be secured.

An object of the present invention is to prevent the suction pressure of a compressor from falling below an allowable value during defrosting, to ensure compressor reliability, and to shorten the defrosting time to improve comfort. It is to provide a device.

It is another object of the present invention to prevent the suction pressure of the compressor from falling below an allowable value during defrosting, to secure a necessary minimum oil amount and to ensure the reliability of the compressor. It is an object of the present invention to provide a cooling and heating device which can improve the comfort by shortening the air conditioner.

Still another object of the present invention is to prevent the suction pressure of the compressor from falling below an allowable value during defrosting, to secure a necessary minimum oil amount to ensure compressor reliability, and to improve the defrosting time. Is to provide a cooling and heating device capable of improving the comfort by further reducing the temperature.

Still another object of the present invention is to prevent the suction pressure of the compressor from falling below an allowable value during defrosting under all installation conditions and temperature conditions, and to secure a necessary minimum oil amount to prevent the compressor from decompressing. An object of the present invention is to provide a cooling and heating device that can ensure reliability and further reduce defrost time to improve comfort.

[0019]

To achieve this object, a cooling and heating apparatus according to the present invention comprises a variable speed compressor, a four-way valve, an accumulator, an outdoor heat exchanger, an outdoor expansion valve, an indoor heat exchanger, and an indoor expansion valve. A refrigeration cycle, a temperature sensor mounted on the upstream side of the outdoor heat exchanger during a heating operation, a discharge pressure sensor for detecting a discharge pressure of the variable speed compressor, and a suction pressure of the variable speed compressor. A suction pressure sensor for detecting the temperature, and when the detected temperature of the temperature sensor becomes lower than a set value during the heating operation, the four-way valve is switched to start the defrosting operation, and the detected temperature after the start of the defrosting operation is higher than the set value. When the four-way valve is switched over, the defrosting operation is terminated and the heating operation is performed. When the input pressure is higher than a predetermined suction pressure value, the operating frequency of the variable speed compressor is calculated so that the discharge pressure detected by the discharge pressure sensor becomes a predetermined discharge pressure value. If the suction pressure detected in step S is lower than a predetermined suction pressure value, the operation frequency of the variable speed compressor is calculated so that the suction pressure detected by the suction pressure sensor becomes a predetermined suction pressure. Operating compressor frequency calculation control means.

This prevents the suction pressure of the compressor from falling below the allowable value during defrosting, thereby ensuring compressor reliability and shortening the defrosting time to improve comfort.

Further, the cooling and heating device of the present invention includes a refrigeration cycle including a variable speed compressor, a four-way valve, an accumulator, an outdoor heat exchanger, an outdoor expansion valve, an indoor heat exchanger, and an indoor expansion valve; A temperature sensor mounted on the upstream side of the heat exchanger, a discharge pressure sensor for detecting a discharge pressure of the variable speed compressor, a suction pressure sensor for detecting a suction pressure of the variable speed compressor, and a heating operation. The defrosting operation is started by switching the four-way valve when the temperature detected by the temperature sensor becomes equal to or lower than the setting, and the defrosting operation is started by switching the four-way valve when the detected temperature becomes higher than the set value after the defrosting operation is started. When the defrost operation is started by the defrost start / end control means, the suction pressure detected by the suction pressure sensor is set to a predetermined suction pressure value. When it is high, the operating frequency of the variable speed compressor is calculated so that the discharge pressure detected by the discharge pressure sensor becomes a predetermined discharge pressure value, and the suction pressure detected by the suction pressure sensor is predetermined. A compressor frequency calculating means for calculating an operating frequency of the variable speed compressor so that the suction pressure detected by the suction pressure sensor becomes a predetermined suction pressure when the suction pressure is lower than the suction pressure value; When the frequency of the variable speed compressor calculated by the calculating means is higher than a predetermined upper limit frequency, the compressor is operated at the upper limit frequency and the frequency calculated by the compressor frequency calculating means is equal to or less than the predetermined upper limit frequency. In this case, a compressor upper limit frequency monitoring operation means for operating the variable speed compressor at the frequency of the calculation result is provided.

This prevents the suction pressure of the compressor from dropping below the allowable value during defrosting, further secures the necessary minimum oil amount to ensure compressor reliability, and shortens the defrosting time. Comfort can be improved.

Further, the cooling / heating device of the present invention comprises a refrigeration cycle including a variable speed compressor, a four-way valve, an accumulator, an outdoor heat exchanger, an outdoor expansion valve, an indoor heat exchanger, and an indoor expansion valve; A temperature sensor mounted on the upstream side of the heat exchanger, a discharge pressure sensor for detecting a discharge pressure of the variable speed compressor, a suction pressure sensor for detecting a suction pressure of the variable speed compressor, and a heating operation. The defrosting operation is started by switching the four-way valve when the temperature detected by the temperature sensor becomes equal to or lower than the setting, and the defrosting operation is started by switching the four-way valve when the detected temperature becomes higher than the set value after the defrosting operation is started. And a defrost start / end control unit for performing a heating operation, and a suction pressure detected by the suction pressure sensor when the defrost operation is started by the defrost start / end control unit. If it is higher, the operating frequency of the variable speed compressor is calculated so that the discharge pressure detected by the discharge pressure sensor becomes a predetermined discharge pressure value, and the suction pressure detected by the suction pressure sensor is predetermined. Compressor frequency calculating means for calculating an operating frequency of the variable speed compressor so that the suction pressure detected by the suction pressure sensor becomes a predetermined suction pressure when the suction pressure is lower than the suction pressure value. When the frequency of the variable speed compressor calculated by the frequency calculation means is higher than a predetermined upper limit frequency, the compressor is operated at the upper limit frequency and the frequency calculated by the compressor frequency calculation means is equal to or less than the predetermined upper limit frequency. In the case of, the compressor upper limit frequency monitoring control means for operating the variable speed compressor at the frequency of the calculation result, and when a predetermined time has elapsed since the start of the defrosting operation, The upper limit frequency set by compressor upper limit frequency monitoring control unit and a defrosting time monitoring means for the permissible maximum frequency of the variable speed compressor.

This prevents the suction pressure of the compressor from dropping below the allowable value during defrosting, further secures the required minimum oil amount to ensure compressor reliability, and further increases the defrosting time. It can be shortened to improve comfort.

Further, the cooling and heating apparatus of the present invention comprises a refrigeration cycle comprising a variable speed compressor, a four-way valve, an accumulator, an outdoor heat exchanger, an outdoor expansion valve, an indoor heat exchanger, and an indoor expansion valve; A discharge temperature sensor for detecting a discharge temperature of the compressor, a temperature sensor mounted on a side upstream of the outdoor heat exchanger during a heating operation, a discharge pressure sensor for detecting a discharge pressure of the variable speed compressor, A suction pressure sensor that detects the suction pressure of the variable-speed compressor, and the four-way valve is switched to start the defrosting operation when the detected temperature of the temperature sensor becomes equal to or lower than the set value during the heating operation, and the detection is performed after the defrosting operation starts. When the temperature becomes higher than a set value, the four-way valve is switched to terminate the defrosting operation and perform the heating operation. When the suction pressure detected by the input pressure sensor is higher than a predetermined suction pressure value, the operating frequency of the variable speed compressor is adjusted so that the discharge pressure detected by the discharge pressure sensor becomes a predetermined discharge pressure value. When the suction pressure detected by the suction pressure sensor is lower than a predetermined suction pressure value, the variable speed compression is performed so that the suction pressure detected by the suction pressure sensor becomes a predetermined suction pressure. Compressor frequency calculating means for calculating the operating frequency of the machine, superheat degree calculating means for calculating the degree of superheat from the discharge temperature detected by the discharge temperature sensor and the discharge pressure detected by the discharge pressure sensor, and the superheat degree When the degree of superheat calculated by the calculation means is large, the upper limit frequency is set low, and when the degree of superheat is small, the upper limit frequency is set high. When the frequency of the high-speed compressor is higher than the set upper limit frequency, the compressor operates at the set upper limit frequency, and when the frequency calculated by the compressor frequency calculator is equal to or lower than the set upper limit frequency, the frequency of the calculation result is obtained. And a compressor frequency determination control means for operating the variable speed compressor.

This prevents the suction pressure of the compressor from dropping below the allowable value during defrosting under all installation conditions and temperature conditions, and secures the necessary minimum oil amount to improve compressor reliability. In addition to ensuring the comfort, the defrosting time can be further reduced to improve comfort.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, when the defrosting operation is started by the defrosting start / end control means, the suction pressure detected by the suction pressure sensor becomes larger than a predetermined suction pressure value. If it is high, the operation frequency of the variable speed compressor is calculated so that the discharge pressure detected by the discharge pressure sensor becomes a predetermined discharge pressure value, and the suction pressure detected by the suction pressure sensor is determined by the predetermined suction pressure. A compressor frequency calculation control means for calculating and operating the operating frequency of the variable speed compressor so that the suction pressure detected by the suction pressure sensor becomes a predetermined suction pressure when the pressure is lower than the value.

For this reason, when the suction pressure detected by the suction pressure sensor is lower than the predetermined suction pressure value, the defrosting operation is performed while calculating the operating frequency at which the suction pressure becomes the predetermined suction pressure value. ing. When the suction pressure detected by the suction pressure sensor is higher than a predetermined suction pressure value, the defrosting operation is performed while calculating the operation frequency so that the discharge pressure becomes a predetermined discharge pressure value.

Therefore, the variation width of the frequency differs depending on the calculation result. Further, when the suction pressure detected by the suction pressure sensor is lower than a predetermined suction pressure value, the frequency is mainly reduced, and when the suction pressure detected by the suction pressure sensor is higher than the predetermined suction pressure value, It mainly has the effect of increasing the frequency.

According to a second aspect of the present invention, when the defrosting operation is started by the defrosting start / end control means, the suction pressure sensor detects that the suction pressure detected by the suction pressure sensor is higher than a predetermined suction pressure value. Calculates the operating frequency of the variable speed compressor so that the discharge pressure detected in step 2 becomes a predetermined discharge pressure value. If the suction pressure detected by the suction pressure sensor is lower than the predetermined suction pressure value, suction Compressor frequency calculating means for calculating the operating frequency of the variable speed compressor so that the suction pressure detected by the pressure sensor becomes a predetermined suction pressure; and the frequency of the variable speed compressor calculated by the compressor frequency calculating means. If the frequency calculated by the compressor frequency calculation means is lower than the predetermined upper limit frequency, the operation is performed at the upper limit frequency when the frequency is higher than the predetermined upper limit frequency. Equipped with a compressor upper limit frequency monitoring operation means for operating a variable speed compressor by the number.

For this reason, when the suction pressure detected by the suction pressure sensor is lower than the predetermined suction pressure value, the defrosting operation is performed while calculating the operating frequency at which the suction pressure becomes the predetermined suction pressure value. ing. When the suction pressure detected by the suction pressure sensor is higher than a predetermined suction pressure value, the defrosting operation is performed while calculating the operation frequency so that the discharge pressure becomes a predetermined discharge pressure value.

Therefore, the width of change of the frequency differs depending on the calculation result. Further, when the suction pressure detected by the suction pressure sensor is lower than a predetermined suction pressure value, the frequency is mainly reduced, and when the suction pressure detected by the suction pressure sensor is higher than the predetermined suction pressure value, It mainly has the effect of increasing the frequency.

Further, the oil discharge amount of the variable speed compressor changes according to the capacity of the oil pump. The oil discharge amount increases as the operating frequency increases and decreases as the operating frequency decreases. Therefore, setting the upper limit frequency of the variable speed compressor has the effect of limiting the oil discharge amount.

According to a third aspect of the present invention, when the defrosting operation is started by the defrosting start / end control means, when the suction pressure detected by the suction pressure sensor is higher than a predetermined suction pressure value, the discharge pressure is reduced. Calculates the operating frequency of the variable speed compressor so that the discharge pressure detected by the sensor becomes a predetermined discharge pressure value, and when the suction pressure detected by the suction pressure sensor is lower than the predetermined suction pressure value A compressor frequency calculating means for calculating an operating frequency of the variable speed compressor so that the suction pressure detected by the suction pressure sensor becomes a predetermined suction pressure; and a variable speed compressor calculated by the compressor frequency calculating means. When the frequency is higher than the predetermined upper limit frequency, the operation is performed at the upper limit frequency, and when the frequency calculated by the compressor frequency calculating means is lower than the predetermined upper limit frequency, the calculation result is obtained. A compressor upper limit frequency monitoring and control means for operating the variable speed compressor at the frequency, and an upper limit frequency set by the compressor upper limit frequency monitoring and control means when a predetermined time elapses from the start of the defrosting operation. A defrosting time monitoring means for setting the highest frequency is provided.

For this reason, when the suction pressure detected by the suction pressure sensor is lower than the predetermined suction pressure value, the defrosting operation is performed while calculating the operating frequency at which the suction pressure becomes the predetermined suction pressure value. ing. When the suction pressure detected by the suction pressure sensor is higher than a predetermined suction pressure value, the defrosting operation is performed while calculating the operation frequency so that the discharge pressure becomes a predetermined discharge pressure value.

Therefore, the width of change of the frequency differs depending on the calculation result. Further, when the suction pressure detected by the suction pressure sensor is lower than a predetermined suction pressure value, the frequency is mainly reduced, and when the suction pressure detected by the suction pressure sensor is higher than the predetermined suction pressure value, It mainly has the effect of increasing the frequency.

Further, the oil discharge amount of the variable speed compressor changes according to the capacity of the oil pump. The oil discharge amount increases as the operating frequency increases and decreases as the operating frequency decreases. Therefore, setting the upper limit frequency of the variable speed compressor has the effect of limiting the oil discharge amount.

Further, after a predetermined time elapses after switching the four-way valve and starting defrosting, the refrigerating machine oil discharged from the variable speed compressor reaches the accumulator. At this time, since the refrigerating machine oil returned to the accumulator is supplied to the variable speed compressor, the oil does not run out even if the frequency is higher than the upper limit frequency. Therefore, there is an effect that a frequency band between the upper limit frequency having a large defrosting capacity and the allowable frequency can be used while preventing oil shortage.

According to a fourth aspect of the present invention, when the defrosting operation is started by the defrosting start / end control means, if the suction pressure detected by the suction pressure sensor is higher than a predetermined suction pressure value, a discharge pressure sensor is provided. Calculates the operating frequency of the variable speed compressor so that the discharge pressure detected in step 2 becomes a predetermined discharge pressure value. If the suction pressure detected by the suction pressure sensor is lower than the predetermined suction pressure value, suction Compressor frequency calculating means for calculating the operating frequency of the variable speed compressor so that the suction pressure detected by the pressure sensor becomes a predetermined suction pressure, and the discharge temperature detected by the discharge temperature sensor and the discharge pressure detected by the discharge pressure sensor The superheat degree calculating means for calculating the degree of superheat from the discharge pressure is set, and the upper limit frequency is set lower when the superheat degree calculated by the superheat degree calculator is larger, and the upper limit frequency is set higher when the superheat degree is smaller. If the frequency of the variable speed compressor calculated by the compressor frequency calculation means is higher than the set upper limit frequency, the compressor is operated at the set upper limit frequency, and the frequency calculated by the compressor frequency calculation means is set. A compressor frequency determination control means for operating the variable speed compressor at the calculated frequency when the frequency is equal to or lower than the upper limit frequency.

For this reason, when the suction pressure detected by the suction pressure sensor is lower than the predetermined suction pressure value, the defrosting operation is performed while calculating the operating frequency at which the suction pressure becomes the predetermined suction pressure value. ing. When the suction pressure detected by the suction pressure sensor is higher than a predetermined suction pressure value, the defrosting operation is performed while calculating the operation frequency so that the discharge pressure becomes a predetermined discharge pressure value.

Therefore, the width of change of the frequency differs depending on the calculation result. Further, when the suction pressure detected by the suction pressure sensor is lower than a predetermined suction pressure value, the frequency is mainly reduced, and when the suction pressure detected by the suction pressure sensor is higher than the predetermined suction pressure value, It mainly has the effect of increasing the frequency.

Further, the oil discharge amount of the variable speed compressor changes according to the capacity of the oil pump. The higher the operating frequency, the smaller the oil discharge amount. Therefore, setting the upper limit frequency of the variable speed compressor has the effect of limiting the oil discharge amount.

Further, at the time of defrosting, the refrigerating machine oil in the variable speed compressor is in a mixture state with the refrigerant, and the variable speed compressor sucks this mixture. Therefore, the amount of mixture in the variable speed compressor decreases, and if the oil runs out, the degree of discharge superheat of the variable speed compressor increases, so that oil shortage can be detected in advance by the degree of discharge superheat.

Therefore, by using the discharge superheat degree, which is the state quantity of the cycle, for detecting the out-of-oil condition, all the installation conditions,
Even under temperature conditions, it has the effect of changing the upper limit frequency and maximizing the defrosting ability while preventing oil shortage.

[0045]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cooling and heating apparatus according to the present invention will be described below with reference to the drawings. Note that the same components as those of the related art are denoted by the same reference numerals, and detailed description thereof will be omitted.

(Embodiment 1) FIG. 1 is a refrigeration cycle diagram of a cooling and heating apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a control block diagram of the air conditioner according to the first embodiment at the time of defrosting, and shows details of the flow of control signals.

In FIG. 1, reference numeral 21 denotes a discharge pressure sensor for detecting the discharge pressure of the variable speed compressor 1, 22 denotes a suction pressure sensor for detecting the suction pressure of the variable speed compressor 1, and 23 denotes an outdoor heat exchanger during a heating operation. Reference numeral 30 denotes a temperature sensor mounted on the upstream side of 4, and reference numeral 30 denotes a control device.

In FIG. 2, 40 is a Ps0 storage means for storing a predetermined suction pressure, 41 is a pressure comparison means for comparing suction pressures, 42 is a Pd0 storage means for storing a predetermined discharge pressure, and 43 is a Pd0 storage means. A suction pressure main frequency calculating means 44 for calculating the frequency of the variable speed compressor 1 so as to have a predetermined suction pressure, 44 is a discharge pressure main body for calculating the frequency of the variable speed compressor 1 so as to have a predetermined discharge pressure. It is a frequency calculating means.

45 is a frequency output means for outputting a frequency,
Reference numeral 46 denotes a compressor driving means for operating the variable speed compressor 1 with the frequency signal of the frequency output means 45.

The Ps0 storage means 40, the pressure comparison means 41, the Pd0 storage means 42, the suction pressure main frequency calculation means 43, the discharge pressure main frequency calculation means 44, the frequency output means 45, and the compressor drive means 46 determine the compressor frequency. It constitutes the arithmetic control means 12.

The operation of the cooling / heating apparatus configured as described above during defrosting, which is a problem, will be described here. Note that the detailed description of the same operation as that in the related art is omitted.

FIG. 3 is a flow chart of the operation of the air conditioner at the time of defrosting according to the first embodiment of the present invention.

During the heating operation in STEP 1, the defrost start / end control means 10 sets the temperature detected by the temperature sensor 23 to the set value (t
0) When it becomes equal to or less than the predetermined value, the four-way valve 2 is switched, the frequency of the variable speed compressor 1 is controlled to a predetermined set value, and the defrosting operation is started.

In STEP 2, the discharge pressure (Pd) is detected by the discharge pressure sensor 21 and the suction pressure (Ps) is detected by the suction pressure sensor 22, and the pressure data is transferred to the control device 30.

In STEP 3, the compressor frequency calculation control means 12 determines whether the suction pressure (Ps) transferred in STEP 2 is higher or lower than a predetermined suction pressure value (Ps0).

In STEP4, when it is determined in STEP3 that the suction pressure (Ps) is higher than the predetermined suction pressure value (Ps0), the discharge pressure (Pd) detected in STEP2 is changed to the predetermined discharge pressure (Pd). The frequency of the variable speed compressor 1 which is Pd0) is calculated. For example, at time intervals of 10 seconds, the discharge pressure of the control target value and the discharge pressure
The operating frequency is determined by a combination of the floor difference and the second floor difference. On the other hand, if it is determined in STEP 3 that the suction pressure (Ps) is lower than the predetermined suction pressure value (Ps0), the suction pressure (Ps) detected in STEP 2 becomes the predetermined suction pressure (Ps0). The frequency of the variable speed compressor 1 is calculated.

In STEP 5, the variable speed compressor 1 is operated at the frequency calculated in STEP 4.

Further, a detailed signal flow will be described with reference to FIG. When the detected temperature of the temperature sensor 23 is sent to the defrost start / end control means 10 and becomes equal to or less than the set value (t0), the defrost start / end control means 10 switches the four-way valve 2,
The defrosting operation is started by controlling the frequency of the variable speed compressor 1 to a predetermined set value, and at the same time, a defrosting start signal is sent to the pressure comparing means 41.

In the pressure comparing means 41, the suction pressure sensor 2
Pressure (Ps) sent from 2 and Ps0 storage means 40
Is compared with a predetermined suction pressure (Ps0) stored in the storage unit.

The suction pressure (P
If s) is lower than the predetermined suction pressure value (Ps0), a signal is sent to the suction pressure main frequency calculating means 43,
The suction pressure (Ps) is a predetermined suction pressure value (Ps
If it is higher than 0), a signal is sent to the discharge pressure main frequency calculation means 44.

When a signal is sent to the suction pressure main frequency calculating means 43, the suction pressure main frequency calculating means 43 sets the suction pressure (Ps) sent from the suction pressure sensor 22 to a predetermined suction pressure (Ps0). Variable speed compressor 1
Is calculated. For example, at a time interval of every 10 seconds, the frequency is determined by the combination of the first-order difference and the second-order difference between the discharge pressure of the control target value and the discharge pressure, and the calculation result is sent to the frequency output means 45.

When a signal is sent to the discharge pressure main frequency calculation means 44, the discharge pressure main frequency calculation means 44 determines that the discharge pressure (Pd) sent from the discharge pressure sensor 21 is equal to the predetermined discharge pressure (Pd0). Variable speed compressor 1
Is calculated. For example, at a time interval of every 10 seconds, the frequency is determined by the combination of the first-order difference and the second-order difference between the discharge pressure of the control target value and the discharge pressure, and the calculation result is sent to the frequency output means 45.

The frequency output means 45 is connected to the compressor drive means 4
6, the compressor drive means 46 operates the variable speed compressor 1 at the transmitted frequency.

As described above, in the air conditioner of the first embodiment, when the defrosting operation is started by the defrosting start / end control means 10, the suction pressure detected by the suction pressure sensor 22 is higher than a predetermined suction pressure value. In this case, the operating frequency of the variable speed compressor 1 is calculated so that the discharge pressure detected by the discharge pressure sensor 21 becomes a predetermined discharge pressure value, and the suction pressure detected by the suction pressure sensor 22 is predetermined. When the pressure is lower than the suction pressure value, the compressor frequency calculation control means 12 calculates and operates the operating frequency of the variable speed compressor 1 so that the suction pressure detected by the suction pressure sensor 22 becomes a predetermined suction pressure. Have been.

Therefore, when the suction pressure detected by the suction pressure sensor 22 is lower than the predetermined suction pressure value, the defrosting operation is performed while calculating the operation frequency at which the suction pressure becomes the predetermined suction pressure value. Is going. When the suction pressure detected by the suction pressure sensor 22 is higher than a predetermined suction pressure value, the defrosting operation is performed while calculating the operation frequency so that the discharge pressure becomes the predetermined discharge pressure value. .

Therefore, the width of change of the frequency differs depending on the calculation result. When the suction pressure detected by the suction pressure sensor 22 is lower than the predetermined suction pressure value, the frequency is mainly reduced, and the suction pressure detected by the suction pressure sensor 22 is higher than the predetermined suction pressure value. In this case, the frequency can be mainly increased, so that the suction pressure of the variable speed compressor 1 is prevented from falling below the allowable value during the defrosting,
Compressor reliability can be ensured, and defrosting time can be shortened to improve comfort.

(Embodiment 2) FIG. 4 is a refrigeration cycle diagram of a cooling and heating apparatus according to Embodiment 2 of the present invention.

FIG. 5 is a control block diagram at the time of defrosting of the cooling and heating device according to the second embodiment of the present invention, and shows details of the flow of control signals.

The same components as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 4, reference numeral 31 denotes a control device. In FIG. 5, reference numeral 47 denotes a frequency comparison unit, 48 denotes an upper limit frequency storage unit that stores a predetermined upper limit frequency of the variable speed compressor 1, and 49 denotes a frequency determination unit.

Ps0 storage means 40, pressure comparison means 41,
Pd0 storage means 42, suction pressure main frequency calculation means 4
3. The compressor frequency calculating means 13 is constituted by the discharge pressure main frequency calculating means 44.

The frequency output means 45, the compressor drive means 46, the frequency comparison means 47, the upper limit frequency storage means 4
8. The compressor upper limit frequency monitoring operation means 14 is constituted by the frequency determination means 49.

The operation of the cooling / heating device configured as described above during defrosting, which is a problem, will now be described. The detailed description of the same operation as that of the first embodiment is omitted.

FIG. 6 is a flowchart showing the operation of the air conditioner according to the second embodiment of the present invention at the time of defrosting, and a schematic operation will be described.

In STEP 5, the frequency (Hzc) calculated by the compressor frequency calculating means 13 in STEP 4 is compared with a predetermined upper limit frequency (Hz0).

In step 6, as a result of the comparison in step 5, if the calculated frequency (Hzc) is higher than the predetermined upper limit frequency (Hz0), the upper limit frequency (Hz0)
0) is the operating frequency of the variable speed compressor 1, and the calculated frequency (Hzc) is higher than the predetermined upper limit frequency (Hz).
If it is lower than 0), the calculated frequency (Hzc) is set as the operating frequency of the variable speed compressor 1.

In STEP 7, the variable speed compressor 1 is operated at the frequency determined in STEP 6.

Further, a detailed signal flow will be described with reference to FIG. The frequency comparing means 47 compares the frequency (Hzc) calculated by the compressor frequency calculating means 13 with a predetermined upper limit frequency (Hz0) stored in the upper limit frequency storing means 48, and compares the result with the frequency determining means 49. To send to.

In the frequency determination means 49, the calculated frequency (Hzc) is set to a predetermined upper limit frequency (Hz
0), the upper limit frequency (Hz0) is set as the operating frequency of the variable speed compressor 1, and if the calculated frequency (Hzc) is lower than the predetermined upper limit frequency (Hz0), the calculated frequency (Hz0) is used. Hzc) is sent to the frequency output means 45 as the operating frequency of the variable speed compressor 1.

As described above, in the air conditioner of the second embodiment, when the defrosting operation is started by the defrosting start / end control means 10, the suction pressure detected by the suction pressure sensor 22 is higher than a predetermined suction pressure value. In this case, the operating frequency of the variable speed compressor 1 is calculated so that the discharge pressure detected by the discharge pressure sensor 21 becomes a predetermined discharge pressure value, and the suction pressure detected by the suction pressure sensor 22 is predetermined. When the suction pressure is lower than the suction pressure value, the compressor frequency calculating means 13 calculates the operating frequency of the variable speed compressor 1 so that the suction pressure detected by the suction pressure sensor 22 becomes a predetermined suction pressure.
If the frequency of the variable speed compressor 1 calculated by the compressor frequency calculation means 13 is higher than a predetermined upper limit frequency, the compressor operates at the upper limit frequency, and the frequency calculated by the compressor frequency calculation means 13 When the frequency is equal to or lower than the determined upper limit frequency, the upper limit frequency monitoring operation means 14 for operating the variable speed compressor 1 at the frequency of the calculation result.

Therefore, when the suction pressure detected by the suction pressure sensor 22 is lower than the predetermined suction pressure value, the defrosting operation is performed while calculating the operating frequency at which the suction pressure becomes the predetermined suction pressure value. Is going. When the suction pressure detected by the suction pressure sensor 22 is higher than a predetermined suction pressure value, the defrosting operation is performed while calculating the operation frequency so that the discharge pressure becomes the predetermined discharge pressure value. .

Therefore, the variation width of the frequency differs depending on the calculation result. When the suction pressure detected by the suction pressure sensor 22 is lower than the predetermined suction pressure value, the frequency is mainly reduced, and the suction pressure detected by the suction pressure sensor 22 is higher than the predetermined suction pressure value. In this case, the frequency can be increased mainly.

Further, the oil discharge amount of the variable speed compressor 1 changes according to the capacity of the oil pump. The oil discharge amount increases as the operation frequency increases and decreases as the operation frequency decreases. Therefore, the oil discharge amount can be limited by setting the upper limit frequency of the variable speed compressor 1, so that the suction pressure of the variable speed compressor 1 is prevented from falling below an allowable value during defrosting, It is possible to secure the compressor reliability by securing the amount, and to improve the comfort by shortening the defrosting time.

(Embodiment 3) FIG. 7 is a refrigeration cycle diagram of a cooling and heating apparatus according to Embodiment 3 of the present invention.

FIG. 8 is a control block diagram at the time of defrosting of the cooling and heating apparatus according to the third embodiment of the present invention, and shows details of the flow of control signals.

The same components as those of the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 7, reference numeral 32 denotes a control device. In FIG. 8, reference numeral 50 denotes an output selection means for selecting whether to send a signal to the frequency output means 45 or a signal to the frequency comparison means 47, 51 is a time comparison means, and 52 is a T0 storage means for storing a predetermined time. And 53, a defrosting time integration timer for integrating the time from the start of defrosting.

The output selecting means 50 and the time comparing means 5
1. The defrosting time monitoring means 16 is constituted by the T0 storage means 52 and the defrosting time integration timer 53, and the compressor upper limit frequency monitoring and controlling means 15 is constituted by the frequency comparing means 47, the upper limit frequency storing means 48, and the frequency determining means 49. doing.

The operation of the cooling / heating device configured as described above during defrosting, which is a problem here, will be described.

Note that detailed description of the same operations as in the second embodiment is omitted. FIG. 9 is an operation flowchart at the time of defrosting of the cooling and heating device in the third embodiment of the present invention,
The general operation will be described.

In STEP 5, the elapsed time (T) from the start of defrosting is compared with the time (T0) for releasing the restriction of the upper limit frequency, and as a result of the comparison, the elapsed time (T) from the start of defrosting is higher than the upper limit. If it is longer than the time (T0) for releasing the restriction of the frequency, the process proceeds to STEP8, and if it is shorter, the process proceeds to STEP6.

In STEP 6, the frequency (Hzc) calculated in STEP 4 and a predetermined upper limit frequency (Hz
0).

In STEP 7, as a result of the comparison in STEP 6, when the calculated frequency (Hzc) is higher than the predetermined upper limit frequency (Hz0), the upper limit frequency (Hz
0) is the operating frequency of the variable speed compressor 1, and the calculated frequency (Hzc) is higher than the predetermined upper limit frequency (Hz).
If it is lower than 0), the calculated frequency (Hzc) is set as the operating frequency of the variable speed compressor 1.

In STEP 8, STEP 4 or STEP 4
The variable speed compressor 1 is operated at the frequency determined in Step 7.

Further, a detailed signal flow will be described with reference to FIG. The time comparison means 51 compares the predetermined time (T0) stored in the T0 storage means with the time (T) integrated by the defrosting time integration timer 53, and sends which is larger to the output selection means 50. I do.

In the output selecting means 50, if the predetermined time (T0) stored in the T0 storage means is longer than the time (T) integrated by the defrosting time integrating timer 53, a signal is sent to the frequency comparing means 47. When the predetermined time (T0) stored in the T0 storage means is shorter than the time (T) integrated by the defrosting time integration timer 53, a signal is transmitted to the frequency output means 45. .

When a signal is sent to the frequency comparing means 47, the frequency determined by the frequency determining means 49 is sent to the frequency output means 45.

When a signal is sent to the frequency output means 45, the frequency output means 45 outputs
The frequency calculated in step 3 is received.

FIG. 10 is a diagram showing the relationship between the compressor frequency at which the oil level can be secured and the elapsed time from the start of defrosting.

As shown in FIG. 10, after the start of defrosting, it takes time T0 for the refrigerating machine oil discharged from the variable speed compressor 1 to circulate in the system and be returned. Therefore, after the time T0, even if the frequency of the variable speed compressor 1 is increased to the allowable frequency (Hzm), the amount of oil in the variable speed compressor 1 can be increased.

As described above, when the defrosting operation is started by the defrosting start / end control means 10, the suction pressure detected by the suction pressure sensor 22 is higher than the predetermined suction pressure value. In the case, the discharge pressure sensor 21
Calculates the operating frequency of the variable speed compressor 1 so that the discharge pressure detected in the above becomes a predetermined discharge pressure value. When the suction pressure detected by the suction pressure sensor 22 is lower than the predetermined suction pressure value, Is a compressor frequency calculating means 1 for calculating the operating frequency of the variable speed compressor 1 so that the suction pressure detected by the suction pressure sensor 22 becomes a predetermined suction pressure.
3 and when the frequency of the variable speed compressor 1 calculated by the compressor frequency calculating means 13 is higher than a predetermined upper limit frequency, the compressor is operated at the upper limit frequency.
If the calculated frequency is equal to or less than the predetermined upper limit frequency, the compressor upper limit frequency monitoring control means 15 for operating the variable speed compressor 1 at the calculated frequency, and a predetermined time from the start of the defrosting operation. After elapse, the upper limit frequency set by the compressor upper limit frequency monitoring control means 15 is changed to the variable speed compressor 1.
And a defrosting time monitoring means 16 for setting the maximum allowable frequency.

For this reason, when the suction pressure detected by the suction pressure sensor 22 is lower than the predetermined suction pressure value, the defrosting operation is performed while calculating the operating frequency at which the suction pressure becomes the predetermined suction pressure value. Is going. When the suction pressure detected by the suction pressure sensor 22 is higher than a predetermined suction pressure value, the defrosting operation is performed while calculating the operation frequency so that the discharge pressure becomes the predetermined discharge pressure value. .

Therefore, the width of change of the frequency differs depending on the calculation result. When the suction pressure detected by the suction pressure sensor 22 is lower than the predetermined suction pressure value, the frequency is mainly reduced, and the suction pressure detected by the suction pressure sensor 22 is higher than the predetermined suction pressure value. In this case, the frequency can be increased mainly.

Further, the oil discharge amount of the variable speed compressor 1 changes according to the capacity of the oil pump. The higher the operation frequency, the lower the oil discharge amount. Therefore, by setting the upper limit frequency of the variable speed compressor 1, the oil discharge amount can be limited.

Further, after a predetermined time elapses after the four-way valve 2 is switched to start defrosting, the refrigerating machine oil discharged from the variable speed compressor 1 reaches the accumulator 3. At this time, since the refrigerating machine oil returned to the accumulator 3 is supplied to the variable speed compressor 1, even if the frequency exceeds the upper limit frequency, the oil does not run out. Therefore, it is possible to use the frequency band between the upper limit frequency and the permissible frequency of the large defrosting capacity while preventing the oil from running out, so that the suction pressure of the variable speed compressor 1 is prevented from falling below the permissible value during the defrosting. In addition, the minimum oil amount can be secured to ensure compressor reliability, and the defrosting time can be further shortened to improve comfort.

(Embodiment 4) FIG. 11 is a refrigeration cycle diagram of a cooling and heating apparatus according to Embodiment 4 of the present invention.

FIG. 12 is a control block diagram at the time of defrosting of the cooling and heating device according to the third embodiment of the present invention, and shows details of the flow of control signals.

The same components as those of the third embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 11, reference numeral 24 denotes a discharge temperature sensor for detecting the discharge temperature of the variable speed compressor 1, and reference numeral 33 denotes a control device.

In FIG. 12, reference numeral 54 denotes an upper limit frequency calculating means. The frequency comparing means 47, the upper limit frequency calculating means 54, and the frequency determining means 49 constitute the compressor frequency determining control means 18.

The operation of the cooling / heating device configured as described above during defrosting, which is a problem, will be described here.

The detailed description of the same operation as that of the third embodiment is omitted. FIG. 13 is an operation flowchart at the time of defrosting of the cooling and heating device in the fourth embodiment of the present invention, and a schematic operation will be described.

In STEP 5, the superheat calculating means 15 calculates the superheat of the refrigerant discharged from the variable speed compressor 1.

In STEP 6, if the degree of superheat calculated in STEP 5 is large, the upper limit frequency is set low, and if the degree of superheat is small, the upper limit frequency is determined according to the degree of superheat.

At STEP 7, the upper limit frequency (Hz0) determined at STEP 6 is compared. In STEP8, S
Computed frequency (Hzc) as a result of comparison in TEP7
Is higher than the upper limit frequency (Hz0) determined in STEP 6, the upper limit frequency (Hz0) is set as the operating frequency of the variable speed compressor 1, and the calculated frequency (Hzc) is S
When the frequency is lower than the upper limit frequency (Hz0) determined in TEP6, the calculated frequency (Hzc) is set as the operating frequency of the variable speed compressor 1.

At STEP 9, the variable speed compressor 1 is operated at the frequency determined at STEP 8.

The detailed signal flow will be described with reference to FIG. The superheat degree calculating means 17 calculates the superheat degree of the refrigerant discharged from the variable speed compressor 1 using the discharge pressure detected by the discharge pressure sensor 21 and the discharge temperature detected by the discharge temperature sensor 24.

The calculated degree of superheat is determined by the upper limit frequency calculating means 5.
4 to calculate an upper limit frequency suitable for the degree of superheat.

The upper limit frequency calculated by the upper limit frequency calculating means 54 is sent to the frequency comparing means 47.

FIG. 14 is a diagram showing the degree of superheat of the refrigerant at the compressor discharge part during defrosting and the compressor frequency at which the oil level can be ensured.

As shown in FIG. 14, when the degree of superheat of the refrigerant at the compressor discharge portion is small, the compressor frequency at which the oil level can be secured is large.
If the degree of superheat of the refrigerant at the compressor discharge part is large, the compressor frequency at which the oil level can be ensured decreases.

As described above, when the defrosting operation is started by the defrosting start / end control means 10, the suction pressure detected by the suction pressure sensor 22 is higher than the predetermined suction pressure value. In this case, the operating frequency of the variable speed compressor 1 is calculated so that the discharge pressure detected by the discharge pressure sensor 21 becomes a predetermined discharge pressure value, and the suction pressure detected by the suction pressure sensor 22 is predetermined. When the suction pressure is lower than the suction pressure value, the compressor frequency calculating means 13 calculates the operating frequency of the variable speed compressor 1 so that the suction pressure detected by the suction pressure sensor 22 becomes a predetermined suction pressure.
A superheat degree calculating means 17 for calculating a superheat degree from the discharge temperature detected by the discharge temperature sensor 24 and the discharge pressure detected by the discharge pressure sensor 21; and an upper limit when the superheat degree calculated by the superheat degree calculation means 17 is large. If the frequency is lowered and the degree of superheat is small, the upper limit frequency is set higher. If the frequency of the variable speed compressor 1 calculated by the compressor frequency calculator 13 is higher than the set upper limit frequency, the set upper limit frequency is used. When the frequency calculated by the compressor frequency calculation means 13 is equal to or lower than the set upper limit frequency, the compressor frequency determination control means 18 operates the variable speed compressor 1 at the calculated frequency. .

For this reason, when the suction pressure detected by the suction pressure sensor 22 is lower than the predetermined suction pressure value, the defrosting operation is performed while calculating the operating frequency at which the suction pressure becomes the predetermined suction pressure value. Is going. When the suction pressure detected by the suction pressure sensor 22 is higher than a predetermined suction pressure value, the defrosting operation is performed while calculating the operation frequency so that the discharge pressure becomes the predetermined discharge pressure value. .

Therefore, the variation width of the frequency differs depending on the calculation result. When the suction pressure detected by the suction pressure sensor 22 is lower than the predetermined suction pressure value, the frequency is mainly reduced, and the suction pressure detected by the suction pressure sensor 22 is higher than the predetermined suction pressure value. In this case, the frequency can be increased mainly.

Further, the oil discharge amount of the variable speed compressor 1 changes according to the capacity of the oil pump. The oil discharge amount increases as the operating frequency increases and decreases as the operating frequency decreases. Therefore, by setting the upper limit frequency of the variable speed compressor 1, the oil discharge amount can be limited.

Further, when defrosting, the inside of the variable speed compressor 1
Is in a mixture state with the refrigerant, and the variable speed compressor 1 sucks this mixture. Therefore, the amount of mixture in the variable speed compressor 1 decreases, and if the oil runs out, the degree of discharge superheat of the variable speed compressor 1 increases.

Therefore, by using the degree of discharge superheat, which is the state quantity of the cycle, for detecting oil shortage, all installation conditions,
Even under temperature conditions, the upper limit frequency can be changed to prevent oil depletion while maximizing defrosting capacity. This prevents the suction pressure of the compressor from falling below the allowable value during defrosting even under a wide range of installation and temperature conditions. Further, the required minimum oil amount can be ensured to ensure the reliability of the compressor, and the defrosting time can be further shortened to improve the comfort.

[0129]

As described above, according to the present invention, the variable speed compressor, the four-way valve, the accumulator, the outdoor heat exchanger,
A refrigeration cycle is constituted by an outdoor expansion valve, an indoor heat exchanger, and an indoor expansion valve, and detects a temperature sensor mounted on the upstream side of the outdoor heat exchanger during a heating operation and a discharge pressure of the variable speed compressor. A discharge pressure sensor, a suction pressure sensor for detecting the suction pressure of the variable speed compressor, and a defrosting operation by switching the four-way valve when a temperature detected by the temperature sensor becomes equal to or lower than a set value during a heating operation. When the detected temperature becomes higher than the set value after the start of the defrosting operation, the four-way valve is switched to terminate the defrosting operation and perform the heating operation. When the operation is started, if the suction pressure detected by the suction pressure sensor is higher than a predetermined suction pressure value, the discharge pressure detected by the discharge pressure sensor becomes the predetermined discharge pressure value. When the operating frequency of the variable speed compressor is calculated and the suction pressure detected by the suction pressure sensor is lower than a predetermined suction pressure value, the suction pressure detected by the suction pressure sensor is determined by the predetermined suction pressure. And a compressor frequency calculation control means for calculating and operating the operation frequency of the variable speed compressor.

Thus, during defrosting, the suction pressure of the compressor is prevented from falling below the allowable value, compressor reliability is secured, and defrosting time is shortened to improve comfort.

A refrigeration cycle comprises a variable speed compressor, a four-way valve, an accumulator, an outdoor heat exchanger, an outdoor expansion valve, an indoor heat exchanger, and an indoor expansion valve. A temperature sensor attached to the variable speed compressor, a discharge pressure sensor for detecting a discharge pressure of the variable speed compressor, a suction pressure sensor for detecting a suction pressure of the variable speed compressor, and a detection of the temperature sensor during a heating operation. When the temperature falls below the setting, the four-way valve is switched to start the defrosting operation, and when the detected temperature is higher than the set value after the start of the defrosting operation, the four-way valve is switched to end the defrosting operation and the heating operation is started. When the defrost operation is started by the defrost start / end control means and the defrost operation is started by the defrost start / end control means, when the suction pressure detected by the suction pressure sensor is higher than a predetermined suction pressure value, the discharge is started. When the operating frequency of the variable speed compressor is calculated so that the discharge pressure detected by the pressure sensor becomes a predetermined discharge pressure value, and the suction pressure detected by the suction pressure sensor is lower than a predetermined suction pressure value. The compressor frequency calculating means for calculating the operating frequency of the variable speed compressor so that the suction pressure detected by the suction pressure sensor becomes a predetermined suction pressure, and the compressor frequency calculating means calculates the operating frequency. When the frequency of the variable speed compressor is higher than a predetermined upper limit frequency, the compressor operates at the upper limit frequency, and when the frequency calculated by the compressor frequency calculator is equal to or lower than the predetermined upper limit frequency, the calculation result is obtained. A compressor upper limit frequency monitoring operation means for operating the variable speed compressor at a frequency is provided.

This prevents the suction pressure of the compressor from dropping below the allowable value during defrosting, further secures the necessary minimum oil amount to ensure compressor reliability, and shortens the defrosting time. Comfort can be improved.

Further, a refrigeration cycle is constituted by a variable speed compressor, a four-way valve, an accumulator, an outdoor heat exchanger, an outdoor expansion valve, an indoor heat exchanger, and an indoor expansion valve. A temperature sensor attached to the variable speed compressor, a discharge pressure sensor for detecting a discharge pressure of the variable speed compressor, a suction pressure sensor for detecting a suction pressure of the variable speed compressor, and a detection of the temperature sensor during a heating operation. When the temperature falls below the setting, the four-way valve is switched to start the defrosting operation, and when the detected temperature is higher than the set value after the start of the defrosting operation, the four-way valve is switched to end the defrosting operation and the heating operation is started. When the defrost operation is started by the defrost start / end control means, and the suction pressure detected by the suction pressure sensor is higher than a predetermined suction pressure value when the defrost operation is started by the defrost start / end control means, The operating frequency of the variable speed compressor is calculated so that the discharge pressure detected by the output pressure sensor becomes a predetermined discharge pressure value, and the suction pressure detected by the suction pressure sensor is lower than a predetermined suction pressure value. In this case, the compressor frequency calculating means for calculating the operating frequency of the variable speed compressor so that the suction pressure detected by the suction pressure sensor becomes a predetermined suction pressure, and the compressor frequency calculating means calculates the operating frequency. When the frequency of the variable speed compressor is higher than a predetermined upper limit frequency, the compressor operates at the upper limit frequency, and when the frequency calculated by the compressor frequency calculator is equal to or lower than the predetermined upper limit frequency, the calculation result is obtained. A compressor upper limit frequency monitoring control means for operating the variable speed compressor at a frequency of, and the compressor upper limit frequency monitoring when a predetermined time has elapsed since the start of the defrosting operation. The upper limit frequency set by control means having a defrosting time monitoring means for the permissible maximum frequency of the variable speed compressor.

This prevents the suction pressure of the compressor from dropping below the allowable value during defrosting, further secures the required minimum oil amount to ensure compressor reliability, and further increases the defrosting time. It can be shortened to improve comfort.

Further, a refrigeration cycle is constituted by a variable speed compressor, a four-way valve, an accumulator, an outdoor heat exchanger, an outdoor expansion valve, an indoor heat exchanger, and an indoor expansion valve, and the discharge temperature of the variable speed compressor is controlled. A discharge temperature sensor for detecting, a temperature sensor mounted on the upstream side of the outdoor heat exchanger during a heating operation, a discharge pressure sensor for detecting a discharge pressure of the variable speed compressor, and a suction of the variable speed compressor A suction pressure sensor for detecting pressure, and during a heating operation, when the detected temperature of the temperature sensor becomes equal to or less than a set value, the four-way valve is switched to start a defrosting operation. When the temperature becomes high, the four-way valve is switched to end the defrosting operation and perform the heating operation. Defrosting start / end control means, and when the defrosting operation is started by the defrosting start / end control means, the suction pressure sensor detects When the known suction pressure is higher than a predetermined suction pressure value, the operating frequency of the variable speed compressor is calculated so that the discharge pressure detected by the discharge pressure sensor becomes a predetermined discharge pressure value. When the suction pressure detected by the suction pressure sensor is lower than a predetermined suction pressure value, the operating frequency of the variable speed compressor is adjusted so that the suction pressure detected by the suction pressure sensor becomes the predetermined suction pressure. Compressor frequency calculating means for calculating the number;
Superheat degree calculating means for calculating the superheat degree from the discharge temperature detected by the discharge temperature sensor and the discharge pressure detected by the discharge pressure sensor, and the superheat degree calculated by the superheat degree calculation means is set to lower the upper limit frequency if the superheat degree is large. If the degree of superheat is small, the upper limit frequency is set higher, and if the frequency of the variable speed compressor calculated by the compressor frequency calculator is higher than the set upper limit frequency, the compressor operates at the set upper limit frequency. When the frequency calculated by the compressor frequency calculation means is equal to or lower than the set upper limit frequency, the compressor frequency determination control means for operating the variable speed compressor at the calculated frequency is provided.

This prevents the suction pressure of the compressor from falling below the allowable value during defrosting even under a wide range of installation conditions and temperature conditions, and secures the necessary minimum oil amount to improve compressor reliability. In addition to ensuring the comfort, the defrosting time can be further reduced to improve comfort.

[Brief description of the drawings]

FIG. 1 is a refrigeration cycle diagram of a cooling and heating apparatus according to a first embodiment of the present invention.

FIG. 2 is a control block diagram at the time of defrosting of the air conditioner of the embodiment.

FIG. 3 is an operation flowchart at the time of defrosting of the air conditioner of the embodiment.

FIG. 4 is a refrigeration cycle diagram of Embodiment 2 of the air conditioner according to the present invention.

FIG. 5 is a control block diagram at the time of defrosting of the air conditioner of the embodiment.

FIG. 6 is an operation flowchart at the time of defrosting of the air conditioner of the embodiment.

FIG. 7 is a refrigeration cycle diagram of Embodiment 3 of the cooling and heating device according to the present invention.

FIG. 8 is a control block diagram at the time of defrosting of the air conditioner of the embodiment.

FIG. 9 is an operation flowchart at the time of defrosting of the air conditioner of the embodiment.

FIG. 10 is a diagram showing the relationship between the compressor frequency at which the oil level can be secured during defrosting and the elapsed time from the start of defrosting in the air conditioner of the embodiment.

FIG. 11 is a refrigeration cycle diagram of a cooling and heating apparatus according to a fourth embodiment of the present invention.

FIG. 12 is a control block diagram at the time of defrosting of the air conditioner of the embodiment.

FIG. 13 is an operation flowchart at the time of defrosting of the air conditioner of the embodiment.

FIG. 14 is a diagram showing the relationship between the degree of superheat of the refrigerant at the compressor discharge portion and the compressor frequency at which the oil level can be secured during defrosting of the air conditioner of the embodiment.

FIG. 15 is a refrigeration cycle diagram of a conventional air conditioner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Variable speed compressor 2 Four-way valve 3 Accumulator 4 Outdoor heat exchanger 5 Outdoor expansion valve 6 Indoor heat exchanger 7 Indoor expansion valve 10 Defrosting start / end control means 12 Compressor frequency calculation control means 13 Compressor frequency calculation means 14 Compression Upper limit frequency monitoring and operating means 15 compressor upper limit frequency monitoring and control means 16 defrosting time monitoring means 17 superheat degree calculating means 18 compressor frequency determination control means 21 discharge pressure sensor 22 suction pressure sensor 23 temperature sensor 24 discharge temperature sensor

Claims (4)

[Claims] 1. A refrigeration cycle comprising a variable speed compressor, a four-way valve, an accumulator, an outdoor heat exchanger, an outdoor expansion valve, an indoor heat exchanger, and an indoor expansion valve, and a refrigeration cycle upstream of the outdoor heat exchanger during heating operation. Temperature sensor attached to the side
A discharge pressure sensor for detecting the discharge pressure of the variable speed compressor, a suction pressure sensor for detecting the suction pressure of the variable speed compressor, and when a temperature detected by the temperature sensor becomes lower than a set value during a heating operation. Defrosting start end control means for switching the four-way valve to start the defrosting operation, and for switching the four-way valve to end the defrosting operation and perform the heating operation when the detected temperature after the start of the defrosting operation becomes higher than a set value, and When the defrost operation is started by the defrost start / end control means, if the suction pressure detected by the suction pressure sensor is higher than a predetermined suction pressure value, the discharge pressure detected by the discharge pressure sensor is predetermined. An operation frequency of the variable speed compressor is calculated so as to be a predetermined discharge pressure value. When the suction pressure detected by the suction pressure sensor is lower than a predetermined suction pressure value, the suction pressure sensor is operated. Air conditioner comprising a compressor frequency calculation control means sensed suction pressure chromatography is operated to calculate the operating frequency of the predetermined suction pressure and comprising as the variable speed compressor. 2. A refrigeration cycle including a variable speed compressor, a four-way valve, an accumulator, an outdoor heat exchanger, an outdoor expansion valve, an indoor heat exchanger, and an indoor expansion valve, and a refrigeration cycle upstream of the outdoor heat exchanger during a heating operation. Temperature sensor attached to the side
A discharge pressure sensor that detects a discharge pressure of the variable speed compressor, a suction pressure sensor that detects a suction pressure of the variable speed compressor, and the temperature sensor detects a temperature below a set temperature during a heating operation. Defrosting start control means for switching the four-way valve to start the defrosting operation and for switching the four-way valve to end the defrosting operation and perform the heating operation when the detected temperature after the start of the defrosting operation becomes higher than a set value, When the defrosting operation is started by the defrosting start / end control means, if the suction pressure detected by the suction pressure sensor is higher than a predetermined suction pressure value, the discharge pressure detected by the discharge pressure sensor is predetermined. Calculating the operating frequency of the variable speed compressor so as to obtain the discharge pressure value, and when the suction pressure detected by the suction pressure sensor is lower than a predetermined suction pressure value, the suction pressure sensor A compressor frequency calculating means for calculating an operating frequency of the variable speed compressor so that the suction pressure detected in step S becomes a predetermined suction pressure; and a variable frequency compressor calculated by the compressor frequency calculating means. If the frequency is higher than a predetermined upper limit frequency, the compressor is operated at the upper limit frequency, and if the frequency calculated by the compressor frequency calculator is equal to or lower than the predetermined upper limit frequency, the variable speed compression is performed at the calculated frequency. A cooling and heating device comprising: a compressor upper limit frequency monitoring operation means for operating a compressor. 3. A refrigeration cycle comprising a variable speed compressor, a four-way valve, an accumulator, an outdoor heat exchanger, an outdoor expansion valve, an indoor heat exchanger, and an indoor expansion valve, and a refrigeration cycle upstream of the outdoor heat exchanger during heating operation. Temperature sensor attached to the side
A discharge pressure sensor that detects a discharge pressure of the variable speed compressor, a suction pressure sensor that detects a suction pressure of the variable speed compressor, and the temperature sensor detects a temperature below a set temperature during a heating operation. Defrosting start control means for switching the four-way valve to start the defrosting operation and for switching the four-way valve to end the defrosting operation and perform the heating operation when the detected temperature after the start of the defrosting operation becomes higher than a set value, When the defrosting operation is started by the defrosting start / end control means, when the suction pressure detected by the suction pressure sensor is higher than a predetermined suction pressure value, the discharge pressure detected by the discharge pressure sensor is predetermined. The operating frequency of the variable speed compressor is calculated so as to obtain a discharge pressure value, and when the suction pressure detected by the suction pressure sensor is lower than a predetermined suction pressure value, the suction pressure sensor A compressor frequency calculating means for calculating an operating frequency of the variable speed compressor so that the suction pressure detected in step S becomes a predetermined suction pressure; and a variable frequency compressor calculated by the compressor frequency calculating means. If the frequency is higher than a predetermined upper limit frequency, the compressor is operated at the upper limit frequency, and if the frequency calculated by the compressor frequency calculator is equal to or lower than the predetermined upper limit frequency, the variable speed compression is performed at the calculated frequency. Compressor upper limit frequency monitoring and control means for operating the compressor, and when a predetermined time has elapsed from the start of the defrosting operation, the upper limit frequency set by the compressor upper limit frequency monitoring and control means is set to the maximum allowable frequency of the variable speed compressor A cooling and heating device provided with a defrosting time monitoring means. 4. A refrigerating cycle comprising a variable speed compressor, a four-way valve, an accumulator, an outdoor heat exchanger, an outdoor expansion valve, an indoor heat exchanger, and an indoor expansion valve, and detecting a discharge temperature of the variable speed compressor. A discharge temperature sensor, a temperature sensor attached to the upstream side of the outdoor heat exchanger during a heating operation, a discharge pressure sensor for detecting a discharge pressure of the variable speed compressor, and a suction pressure of the variable speed compressor. The suction pressure sensor to be detected and the four-way valve are switched to start the defrosting operation when the detected temperature of the temperature sensor becomes equal to or lower than the set value during the heating operation, and the detected temperature becomes higher than the set value after the start of the defrosting operation. When the four-way valve is switched to end the defrosting operation and perform the heating operation, the defrosting start / end control means, and when the defrosting start / end control means starts the defrosting operation, the suction detected by the suction pressure sensor When the pressure is higher than a predetermined suction pressure value, the operating frequency of the variable speed compressor is calculated so that the discharge pressure detected by the discharge pressure sensor becomes a predetermined discharge pressure value, and the suction pressure sensor calculates When the detected suction pressure is lower than a predetermined suction pressure value, the compression for calculating the operating frequency of the variable speed compressor so that the suction pressure detected by the suction pressure sensor becomes the predetermined suction pressure. Machine frequency calculating means, superheat degree calculating means for calculating the superheat degree from the discharge temperature detected by the discharge temperature sensor and the discharge pressure detected by the discharge pressure sensor, and the superheat degree calculated by the superheat degree calculation means If the frequency is large, the upper limit frequency is lowered, and if the degree of superheat is small, the upper limit frequency is set high, and the frequency of the variable speed compressor calculated by the compressor frequency calculation means is set. If the frequency is higher than the frequency, the compressor operates at the set upper limit frequency, and if the frequency calculated by the compressor frequency calculator is lower than the set upper limit frequency, the compressor operates the variable speed compressor at the calculated frequency. A cooling and heating device comprising a machine frequency determination control means.