WO2012114454A1

WO2012114454A1 - Refrigeration cycle apparatus

Info

Publication number: WO2012114454A1
Application number: PCT/JP2011/053839
Authority: WO
Inventors: 小山　昌喜; 小谷　正直; 遼太飯島
Original assignee: 株式会社日立製作所
Priority date: 2011-02-22
Filing date: 2011-02-22
Publication date: 2012-08-30
Also published as: EP2679930A1; EP2679930A4; CN103380334A; JPWO2012114454A1; JP5965895B2; CN103380334B

Abstract

This refrigeration cycle apparatus is provided with a compressor (1), an outdoor heat exchanger (2), an expansion valve (3) having open degree thereof controllable, and an indoor heat exchanger (4). The refrigeration cycle apparatus is also provided with: a bypass flow channel (11) that makes a cooling medium being compressed by means of the compressor bypass to the suction side of the compressor; a solenoid valve (12), which opens/closes the bypass flow channel; and a control unit (20), which controls capacity by adjusting the flow volume of the cooling medium to be discharged to the refrigeration cycle from the compressor by controlling a period of time when the solenoid valve is in the open state, and a period of time when the solenoid valve is in the closed state. The control unit performs control on the basis of a duty ratio, which is a ratio of an open period of time to a duty cycle, i.e., a sum of a period of time when the solenoid valve is opened, and a period of time when the solenoid valve is closed, and when, in the state where the solenoid valve is in the open state, suction pressure of the compressor becomes equal to or higher than an allowable deviation with respect to suction pressure before the solenoid valve is opened, the control unit controls the solenoid valve to be in the closed state, and determines the closed period of time on the basis of the duty ratio.

Description

Refrigeration cycle equipment

The present invention relates to a refrigeration cycle apparatus including a capacity control compressor capable of capacity control. In addition, the present invention is suitable for a refrigeration cycle apparatus such as an air-conditioning hot-water supply system for a new generation house having a high eco (environmental-friendly) effect, and can be operated in a wide range, and can efficiently operate even in an ultra-small capacity operation mode. It is particularly suitable for a refrigeration cycle apparatus having a scroll compressor that can be controlled.

In recent years, from the viewpoint of reducing the energy consumed in ordinary houses, that is, the energy consumed by air conditioners and the energy consumed by hot water heaters, there is a tendency to reduce the thermal load by using high thermal insulation for building insulation Is getting stronger. There is also a concept to realize a zero-fossil fuel-free house that is equipped with solar power generation and solar water heaters, so that the accumulated power consumption for one year is zero.

In such a concept, for example, a scroll compressor used in a refrigeration cycle apparatus such as an air conditioner or a water heater is required to be capable of capacity control over a wide range with a single unit. That is, in the cooling operation of the air conditioner, the room temperature is generally high at the start of operation, and thus it is necessary to operate rapidly. In such a case, high speed operation (high speed rotation) is performed at the time of start-up, but when the room is cooled to a certain degree and the state is shifted to a steady operation state, low speed operation (low speed rotation) is performed with a small capacity. In this low-speed operation in the steady-state operation state, especially when the recent energy-saving is implemented and the case where it is used in the air conditioner installed in the building where the high thermal insulation material is installed, the operation is performed at a very low rotational speed. Will be done.

However, if the scroll compressor is rotated at an excessively low speed, the oil film breakage is structurally caused by the sliding bearing and the bearing is easily damaged, and the motor driving for rotating the crankshaft is smooth because of the low speed rotation. Therefore, it is difficult to perform a stable driving operation. Therefore, in general, during small capacity operation, capacity control is performed while maintaining a certain rotational speed. For example, when the room is cooled to some extent, the scroll compressor is stopped and restarted when the room temperature rises. The driving pattern is repeated.

However, such an operation pattern that repeatedly stops and starts during small-capacity operation is not only inefficient, but also cannot comfortably perform air conditioning, and thus a technique for devising capacity control has been proposed. In general, when capacity control is performed by a scroll compressor, the rotational speed by motor drive is controlled, or a part of the structure is improved so that the rotational speed is constant and the discharge amount is variable. The method used in combination is adopted. For example, as a technique for making the discharge amount variable, a scroll-type machine (see Patent Document 1) having a capacity adjustment mechanism that releases a seal (seal) in the axial direction of the crankshaft and does not compress it is known. In addition, an air conditioner (see Patent Document 2) equipped with a scroll compressor provided with a capacity control mechanism that discharges refrigerant gas during compression to the suction side to delay the start of compression is known.

In Patent Document 1, a high pressure chamber, a discharge chamber, and a low pressure suction pipe formed between an outer shell coupling fitting provided on one end side of a compressor and a piston connected to a non-orbiting scroll member are respectively interposed with solenoid valves. When the solenoid valve is turned on (opened) by pulse width adjustment (PWM) control, the pipe from the high pressure chamber to the low pressure suction pipe communicates, and the non-orbiting scroll member is the outer shell coupling fitting. The seal in the axial direction of the crankshaft is released, and compression is no longer possible. In addition, when the solenoid valve is turned off (closed), the inside of the pipe from the high pressure chamber to the discharge chamber communicates, and the non-orbiting scroll member moves to the crankshaft side opposite to the outer shell coupling fitting. Sealing in the axial direction is performed and a normal compression operation is performed.

According to the scroll type machine according to Patent Document 1, the solenoid valve is turned off (closed) during normal capacity control, and the solenoid valve is turned on (opened) during small capacity control to suck the refrigerant gas on the low pressure side. The amount of refrigerant gas discharged is adjusted by returning it to the tube, enabling a wide range of volume control from 0 to 100%. As a result, the lower limit setting value of the motor rotation speed that cannot be actually implemented due to the problems of oil film breakage and torque fluctuation in the above-described slide bearing (the drive signal to the motor has a frequency of about 5 Hz. Compression operation with a small capacity control (ultra-small capacity operation mode) corresponding to the following ultra-low speed operation is possible, and the compressed refrigerant gas is discharged into the discharge pipe. The refrigerant gas can be circulated gently by being guided to the refrigeration cycle via the.

In Patent Document 2, a scroll compressor provided with a bypass port, a flow path that opens the bypass port to an intake pressure atmosphere, a control valve that opens and closes the flow path, and a control valve are set according to the operating load of the air conditioner And a control means that opens and closes by a plurality of control patterns based on the short-period time distribution.
According to the air conditioner equipped with the scroll compressor according to Patent Document 2, it is possible to control the capacity by 60% by discharging the refrigerant gas being compressed into the suction chamber and reducing the confined volume when the suction is completed. Furthermore, 60-100% capacity control operation is realized in stages by opening and closing a control valve for discharging refrigerant gas in the middle of compression to the suction chamber according to a plurality of patterns with a short-period time distribution. .

JP-A-8-334094 Japanese Patent Laid-Open No. 11-324951

In a capacity control operation using a compressor that variably controls the discharge amount, the discharge pressure and the suction pressure vary due to the opening and closing of a control valve such as a solenoid valve for capacity control. In particular, if the ON (open) -OFF (closed) cycle (duty cycle) in pulse width adjustment control (hereinafter referred to as PWM control) is large, the suction pressure fluctuates greatly, and this capacity control method is used for the air conditioner. In this case, the blowing temperature fluctuates and the comfort cannot be maintained. Further, in this capacity control method, a loss occurs when the control valve is opened and closed. Therefore, if the duty cycle is shortened, the fluctuation is reduced, but the loss is increased and the efficiency is lowered.
In the above-mentioned Patent Document 1, capacity adjustment is performed by PWM control of a solenoid valve to turn it on and off, and a wide range of capacity control is possible. However, Patent Document 1 only describes that the solenoid valve is subjected to PWM control and the capacity control is performed by changing the on-off time ratio (duty ratio) in order to adjust the target capacity. However, no consideration is given to improving comfort while suppressing a decrease in efficiency.

Further, in Patent Document 2, a load state of a refrigeration cycle is detected based on signals from a temperature sensor and a pressure sensor provided in a condenser and an evaporator, and a capacity control operation and a full load operation are switched. In the capacity control operation, the bypass operation is performed with a predetermined time distribution. However, in this Patent Document 2, as in Patent Document 1, no consideration is given to improving comfort while suppressing a decrease in efficiency.

An object of the present invention is to obtain a refrigeration cycle apparatus capable of efficient operation control even in an ultra-small capacity operation mode and improving comfort.

To achieve the above object, the present invention provides a refrigeration cycle apparatus comprising a compressor, an outdoor heat exchanger, an opening controllable expansion valve, and an indoor heat exchanger, wherein refrigerant in the compressor is being compressed. A bypass flow path for bypassing to the suction side, a solenoid valve for opening and closing the bypass flow path, a time (τ1) for opening (ON) state and a time (τ2) for closing (OFF) the solenoid valve And a controller for controlling the capacity by adjusting the flow rate of the refrigerant discharged from the compressor to the refrigeration cycle by controlling the duty, which is the sum of the opening time and closing time of the solenoid valve Control is performed based on the duty ratio (d), which is the ratio of the opening time to the cycle (T), and when the solenoid valve is in the open state, the pressure (Ps) on the suction side of the compressor The solenoid valve is controlled to be closed when the suction pressure (Ps0) before opening the noid valve is greater than an allowable deviation (ΔP), and the closing time is determined based on the duty ratio. It is characterized by controlling to.

Another feature of the present invention is that in the refrigeration cycle apparatus including a compressor, an outdoor heat exchanger, an expansion valve capable of opening control, and an indoor heat exchanger, the refrigerant being compressed in the compressor is supplied to the suction side of the compressor A bypass flow path to be bypassed, a solenoid valve for opening and closing the bypass flow path, a time (τ1) for opening (ON) state and a time (τ2) for closing (OFF) the solenoid valve And a controller that controls the capacity by adjusting the flow rate of the refrigerant discharged from the compressor to the refrigeration cycle, and the controller controls the duty cycle (the sum of the opening time and the closing time of the solenoid valve). Control based on the duty ratio (d), which is the ratio of the opening time to T), and when the solenoid valve is in the open state, the indoor heat exchanger or outdoor heat exchanger (evaporator side) that becomes an evaporator When the evaporator temperature (Tev) of the heat exchanger becomes equal to or greater than an allowable deviation (ΔTev) with respect to the evaporator temperature (Tev0) before the solenoid valve is opened, the solenoid valve is controlled to be closed. The closing time is controlled to be determined based on the duty ratio.

According to the present invention, it is possible to obtain a refrigeration cycle apparatus capable of efficient operation control even in an ultra-small capacity operation mode and improving comfort.

The schematic block diagram which shows Example 1 of the refrigerating-cycle apparatus of this invention. The diagram explaining the fluctuation | variation of PWM control and evaporation pressure in a refrigeration cycle apparatus. The flowchart explaining the compressor rotation speed control routine in Example 1 of this invention. The flowchart explaining the expansion valve opening degree control routine in Example 1 of this invention. The schematic block diagram of the refrigerating-cycle apparatus which shows Example 2 of this invention. The flowchart explaining the compressor rotation speed control routine in Example 2 of this invention. The schematic block diagram of the refrigerating-cycle apparatus which shows Example 3 of this invention. The diagram explaining the fluctuation | variation of PWM control and evaporation temperature in the refrigerating-cycle apparatus in Example 3 of this invention. The flowchart explaining the compressor rotation speed control routine in Example 3 of this invention. The longitudinal section showing an example of the capacity control compressor used for the present invention. The principal part expanded sectional view explaining the flow of the refrigerant gas at the time of the normal driving | operation of the capacity control compressor shown in FIG. The principal part expanded sectional view explaining the flow of the refrigerant gas at the time of the bypass operation of the capacity control compressor shown in FIG.

Hereinafter, specific examples of the refrigeration cycle apparatus of the present invention will be described with reference to the drawings.

A first embodiment of the refrigeration cycle apparatus of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic configuration diagram of a refrigeration cycle apparatus showing Embodiment 1 of the present invention, in which the present invention is used for a room air conditioner (air conditioner).

The refrigeration cycle apparatus shown in FIG. 1 will be described together with the operation during cooling operation. The refrigerant compressed by the compressor 1 flows into the four-way valve 5 from the high-pressure side connection pipe 7, passes through the four-way valve 5, and flows out to the outdoor connection pipe 8. Thereafter, the refrigerant is condensed and liquefied by exchanging heat with the outdoor air in the outdoor heat exchanger 2 and dissipating heat, and is decompressed by the expansion valve 3. The refrigerant that has been decompressed to low temperature and low pressure enters the indoor heat exchanger 4, cools the indoor air and evaporates / gases itself, and flows again into the four-way valve 5 from the indoor connection pipe 9. Circulates through the low-pressure side connection port, returns to the suction side of the compressor 1 and is compressed again.

In addition, when switching from the cooling operation to the heating operation, the refrigerant pipe connection destination of the four-way valve 5 is switched. During the heating operation, the high-temperature and high-pressure refrigerant discharged from the compressor 101 passes through the four-way valve 5 from the high-pressure side connection pipe 7, flows out into the indoor connection pipe 9, flows into the indoor heat exchanger 4, and dissipates heat to the indoor air. By doing this, it heats up and condenses itself. Thereafter, the condensed refrigerant is decompressed by the expansion valve 3, exchanges heat with outdoor air in the outdoor heat exchanger 2, evaporates and gasifies, flows into the four-way valve 5 from the outdoor connection pipe 8, and then flows to the low-pressure side connection pipe 10. The circulation of returning to the suction side of the compressor 1 and being compressed again is repeated.

11 is a bypass pipe (bypass flow path) that guides the refrigerant gas at the discharge pressure to the suction side of the compressor 1, and one end of the bypass pipe 11 is connected to the low-pressure side connection pipe 10 on the compressor suction side. The bypass pipe 11 is provided with a solenoid valve 12 that is controlled to be opened (ON) and closed (OFF) by a pulse width adjustment (PWM) control signal. The communication with the pipe 10 is configured to be turned on and off.

For example, in the ultra-low load operation mode (ultra-small capacity operation mode), the solenoid valve 12 is repeatedly operated in an open state and a closed state, and ON / OFF of the discharge-side refrigerant flowing into the suction side is repeated. In addition, a capacity adjustment mechanism that performs small capacity control of refrigerant discharged from the compressor to the refrigeration cycle is realized.

Next, the control system of the refrigeration cycle apparatus shown in FIG. 1 will be described. Reference numeral 13 shown in FIG. 1 denotes a discharge temperature sensor attached to the discharge side pipe (high-pressure side connection pipe 7) of the compressor 1, and detects the refrigerant discharge temperature (refrigerant inlet temperature to the condenser) from the compressor. Reference numeral 14 denotes an indoor heat exchanger temperature sensor attached at a substantially intermediate position of the indoor heat exchanger 4, and this temperature sensor 14 is used for the refrigerant during the cooling operation in which the indoor heat exchanger 4 functions as an evaporator. Used to detect the evaporation temperature. Further, reference numeral 15 denotes an outdoor heat exchanger temperature sensor attached at a substantially intermediate position of the outdoor heat exchanger 2, and this temperature sensor 15 is used for the refrigerant during the heating operation in which the outdoor heat exchanger 2 functions as an evaporator. Used to detect the evaporation temperature. In addition, 16 is an indoor temperature sensor that detects the temperature of the room in which the indoor heat exchanger 4 is provided, and 17 is an outdoor temperature sensor that detects the outside air temperature near the installation of the outdoor heat exchanger 2.

Meanwhile, an inverter (motor drive circuit) 18 is connected to the compressor 1, and the inverter 18 is connected to a commercial AC power source 19. The inverter 18 rectifies the voltage of the commercial AC power supply 19, converts it to a voltage having a frequency according to the command, and outputs the voltage to a motor provided in the compressor 1. The inverter 18 is connected to the control unit 20 and drives the motor based on a command from the control unit 20. The control unit 20 includes the four-way valve 5, the expansion valve 3, the outdoor fan 21, the indoor fan 22, the indoor heat exchanger temperature sensor 14, the outdoor heat exchanger temperature sensor 15, and the indoor temperature sensor 16. The outdoor temperature sensor 17, the discharge temperature sensor 13, the suction pressure sensor 23, the inverter 18, and a remote control type operation device (not shown; hereinafter referred to as a remote controller) are connected to each other. The unit 20 is configured to control the entire refrigeration cycle apparatus (room air conditioner).

Next, the operation during the cooling operation in the above-described refrigeration cycle apparatus will be described. At the start of the cooling operation, the control unit 20 puts the four-way valve 5 in the state of the cooling operation, and operates the compressor 1, the outdoor fan 21 and the indoor fan 22 at a predetermined rotation speed set in advance as an initial value. . The refrigerant discharged from the compressor 1 repeats circulation such as returning to the compressor 1 through the four-way valve 5, the outdoor heat exchanger 2, the expansion valve 3, the indoor heat exchanger 4, and the four-way valve 5 again. Thus, cooling operation is performed. The expansion valve 3 is constituted by an electronic expansion valve, for example, and rotates a pulse motor built in the electronic expansion valve so as to open at an initial predetermined opening. During the cooling operation, the indoor heat exchanger (use side heat exchanger) 4 functions as an evaporator.

In the room air conditioner as the refrigeration cycle apparatus, the room temperature is detected by the room temperature sensor 16 provided in the vicinity of the ventilation passage entrance of the indoor heat exchanger 4, and according to the difference from the set temperature set by the remote controller. The controller 20 controls the inverter 18 to vary the compressor speed. Thereby, the operation of the compressor 1 according to the air conditioning load is performed.

Further, the detected temperature (discharged refrigerant temperature) of the discharge temperature sensor 13 is detected every predetermined control time, and the detected temperature, the detected temperature (evaporation temperature) of the indoor heat exchanger temperature sensor 14, and the indoor temperature sensor 16 are detected. The opening degree of the expansion valve 3 is controlled at each control time according to the difference between the detected temperature (indoor temperature) and the target discharge temperature determined from the rotational speed command values of the compressor 1 and the outdoor fan 21. By this discharge superheat degree control, the suction superheat degree on the suction side of the compressor 1 is controlled to be substantially zero, and the coefficient of performance of the refrigeration cycle apparatus is kept good.

On the other hand, when the discharge refrigerant temperature detected by the discharge temperature sensor 13 is equal to or higher than a set value, the operating frequency of the compressor 1 is reduced and the discharge refrigerant temperature is set to a set value until the detected temperature falls to a predetermined set value. The opening of the expansion valve 3 is controlled so that By this discharge temperature control, the compressor 1 is prevented from being abnormally heated, and the compressor 1 is prevented from being damaged due to seizure or the like.

Next, the operation during heating operation in the above-described refrigeration cycle apparatus will be described. During the heating operation, the control unit 20 switches the four-way valve 5 to the heating operation side, and operates the compressor 1, the outdoor fan 21, and the indoor fan 22 at a predetermined rotation speed set in advance as an initial value. The refrigerant discharged from the compressor 1 sequentially flows through the four-way valve 5, the indoor heat exchanger 4, the expansion valve 3, and the outdoor heat exchanger 2, passes through the four-way valve 5 again, and returns to the compressor 1. By repeating the above, heating operation is performed. During the heating operation, the indoor heat exchanger (use side heat exchanger) 4 functions as a condenser.

The controller 20 detects the difference between the set temperature by the remote controller and the room temperature detected by the room temperature sensor 16 as an air conditioning load, and the compressor operating frequency (the output frequency of the inverter 18) according to the air conditioning load. ) To control. Thereby, the operation of the compressor 1 according to the heating load is performed.

Further, the discharge refrigerant temperature is detected by the discharge temperature sensor 13 every predetermined control time, and the detected discharge refrigerant temperature, the detected temperature (evaporation temperature) of the outdoor heat exchanger temperature sensor 15, and the outdoor temperature sensor 17 are detected. The opening degree of the expansion valve 3 is controlled for each control time according to the difference between the detected temperature (outside air temperature) and the target discharge temperature determined from the rotational speed command values of the compressor 1 and the outdoor fan 21. By this discharge superheat degree control, the suction superheat degree on the suction side of the compressor 1 is controlled to be substantially zero, and the coefficient of performance of the refrigeration cycle apparatus is kept good.

Next, control using a capacity adjustment mechanism that performs small capacity control of refrigerant discharged from the compressor to the refrigeration cycle at an ultra low load, that is, an ultra low load operation mode (ultra low capacity operation mode) will be described. In the capacity adjustment mechanism that performs ultra-small capacity control in this ultra-low load operation mode, the solenoid valve 12 provided in the bypass pipe 11 is opened (ON) and closed (PWM) by pulse width adjustment (PWM) control. The capacity adjustment operation is performed by controlling to the OFF state.

When the solenoid valve 12 is in the open state, the check valve 121 (see FIG. 10) provided at the outlet of the compression chamber 1 is closed, and the discharged refrigerant gas flows through the bypass pipe 11 to the low-pressure side connection pipe (suction pipe). . For this reason, a refrigerant | coolant does not flow to the four-way valve 5 side, but since the refrigerant | coolant flow volume in a refrigerating cycle reduces, a capability reduces. On the other hand, when the solenoid valve 12 is closed, the refrigerant gas discharged from the compressor can flow to the four-way valve 5 side.

Therefore, in the ultra-low load operation mode in which the capacity adjusting mechanism is operated, the capacity can be adjusted by repeatedly operating the solenoid valve 12 between the open state and the closed state and repeatedly opening and closing the bypass pipe 11.

The state of fluctuation of the evaporation pressure during PWM control of the solenoid valve 12 will be described with reference to FIG. When the PWM control signal is turned on (the solenoid valve is opened), the evaporation pressure increases. Further, when the PWM control signal is turned off (the solenoid valve is closed), the evaporation pressure decreases. Thus, the fluctuation of the evaporation pressure is repeated with the ON / OFF of the solenoid valve 12.

Suppose that the fluctuation range of the evaporation pressure during the capacity adjustment operation using the bypass pipe 11 is ΔP1. Further, during this capacity adjustment operation, the evaporation pressure generally increases, and the average pressure of the fluctuating evaporation pressure increases by ΔP2 with respect to the evaporation pressure before the capacity adjustment operation. If ΔP1 during the capacity adjustment operation is large, the evaporation temperature fluctuates accordingly, and the amount of heat exchange in the evaporator fluctuates, so that the capacity of the refrigeration cycle apparatus fluctuates and the blowing temperature fluctuates. For this reason, in order to maintain comfortable air conditioning, it is desirable to reduce ΔP1. Further, if ΔP2 is large, the endothermic amount is reduced, so the heat exchange amount is also reduced. In order to reduce ΔP1 and ΔP2, the duty cycle T (= τ1 + τ2) of the PWM control signal may be reduced. However, in the PWM capacity control operation, the reverse flow of the discharged refrigerant gas when the solenoid valve 12 is opened and closed, the pressure of the bypass pipe 11 Energy loss occurs due to loss. For this reason, it is preferable not to reduce the duty cycle T in order to efficiently perform the capacity control operation.

Therefore, in this embodiment, in order to perform comfortable air conditioning with high efficiency and small fluctuations in evaporation pressure, an appropriate duty cycle is determined according to the flowcharts shown in FIGS. 3 and 4, and capacity adjustment operation control is performed. Yes.

First, the compressor rotation speed control routine will be described with reference to the flowchart shown in FIG. As described above, the rotation speed of the compressor is set from the remote controller by reading the indoor temperature Tea _in detected by the indoor temperature sensor 16 provided near the inlet of the ventilation passage of the indoor heat exchanger 4 (step 31). setting temperature determining a difference DerutaTea _in between (room temperature target ^value) T * _{ea in} (step 32), in response to the difference, thereby changing the rotational speed of the compressor 1 by an inverter 18 (step 33, 34). Here, as the difference between the set temperature and the detected room temperature becomes smaller, the compressor rotational speed _fz is controlled to become smaller.

In step 35, the compressor rotational speed f _z is the smaller than the rotational speed f _z opt for the capacitive control operation starts, the compressor rotational speed is fixed to f _z opt, from the difference between the indoor temperature and the indoor temperature target value The determined initial duty ratio d (d = τ1 / (τ1 + τ2)) is determined (steps 36, 37), and PWM capacity control operation for turning the solenoid valve 12 on and off is performed. At this time, the timer of the control unit is also turned on at the same time as the PWM control signal is turned on, and measurement of the elapsed time τ1 is started. Further, the suction pressure sensor 23 starts measuring the suction pressure, and the PWM control signal is compared until the measured suction pressure Ps exceeds a preset allowable deviation ΔP as compared to the suction pressure Ps0 before the PWM control signal is turned on. Remains ON and the pressure measurement is repeated (steps 38 to 41). When the difference between the measured Ps and the initial suction pressure Ps0 exceeds ΔP, the PWM control signal is turned OFF, the solenoid valve 12 is closed, the timer is turned OFF, the elapsed time measurement is finished, and τ1 is opened. The time is determined (step 42). The closing time τ2 is determined from the opening time τ1 and the current duty ratio d, and the PWM capacity control operation is performed based on this duty cycle (step 43). As a result, the fluctuation of the suction pressure due to the opening and closing of the solenoid valve is determined within the range of ΔP. Therefore, by setting the ΔP in a range that does not impair the air conditioning comfort, it is possible to operate with an optimal duty cycle. .

FIG. 4 is a flowchart for explaining an expansion valve opening control routine in the refrigeration cycle apparatus of the present embodiment. When the PWM capacity control operation is started by the compressor rotation speed control routine described in FIG. 3, the evaporation temperature rises and increases by ΔP2 (see FIG. 2) with respect to the evaporation pressure before the capacity control operation. In order to make ΔP2 as small as possible, the opening degree of the expansion valve 3 is controlled.

First, at step 45, the state quantity of the refrigeration cycle is read. That is, the indoor temperature, outdoor temperature, indoor heat exchanger temperature, outdoor heat exchanger temperature, and the like detected by each sensor are read, and the rotation speed of the compressor 1, the rotation speeds of the indoor and

outdoor fans

21, 22 and expansion The opening degree of the valve 3 is read. Next, in step 46, when the PWM control signal is OFF, the expansion valve 3 has a detected temperature (discharge refrigerant temperature) Td of the discharge temperature sensor 13 that is detected by the outdoor heat exchanger temperature sensor 15 (condensation temperature) Tao. , the detected temperature of the outdoor temperature sensor 17 (ambient temperature) Tai, is controlling the opening so as to approach the target discharge temperature Td ^* determined from the rotational speed command value fp of the rotational speed f _z and the outdoor fan 21 of the compressor 1 ( Steps 47-51).

In step 46, when the PWM control signal is ON, a corrected compressor rotational speed f _z ′ obtained by dividing the compressor rotational speed f _z opt at the start of the capacity control operation by the duty ratio d at that time is determined (step 52). The corrected compressor rotational speed f _z ′, the detected temperature (condensation temperature) Tao of the outdoor heat exchanger temperature sensor 15, the detected temperature (outside air temperature) Tai of the outdoor temperature sensor 17, and the rotational speed command value fp of the outdoor fan 21 The routine is switched to a routine for controlling the expansion valve 3 so that the detected temperature (discharge refrigerant temperature) Td of the discharge temperature sensor 13 approaches the target discharge temperature Td ^* determined from (steps 52 to 57). Since the cycle refrigerant circulation amount decreases as the duty ratio d increases during the PWM capacity control operation, the expansion valve opening degree is changed to an appropriate opening amount even with respect to the reduced refrigerant circulation amount during the PWM capacity control operation. And increase in ΔP2 can be prevented.

According to the refrigeration cycle apparatus of the present embodiment, the fluctuation of the suction pressure (evaporation pressure) due to the opening and closing of the solenoid valve 12 is determined in a range based on the allowable deviation ΔP, so that the fluctuation of the evaporation pressure is suppressed within a certain range. This makes it possible to improve comfort such as air conditioning and to prevent an increase in loss due to a too short duty cycle, thus enabling highly efficient capacity control operation. In addition, there is an effect that a wide range of capacity control of 0 to 100% can be realized with a simple structure.

Therefore, according to this embodiment, it is possible to obtain a refrigeration cycle apparatus capable of efficient operation control even in the ultra-small capacity operation mode and improving comfort.

FIG. 5 is a schematic configuration diagram of a refrigeration cycle apparatus showing a second embodiment of the present invention, which is used for a room air conditioner as in the first embodiment. In FIG. 5, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. Further, in the second embodiment, the difference from the first embodiment is that the suction pressure sensor is removed, and a blowout temperature sensor 24 is provided in the vicinity of the ventilation passage outlet of the indoor heat exchanger 4. This is the point that the blowing temperature is detected.

When performing control using a capacity adjustment mechanism that performs small capacity control, when the PWM control signal is turned on (i.e., the solenoid valve 12 is in an open state), the evaporation pressure rises and the PWM control signal is turned off (i.e., When the solenoid valve 12 is in the closed state, the evaporation pressure decreases. At this time, the evaporation temperature also fluctuates, and the amount of heat exchange in the evaporator fluctuates. Therefore, the refrigeration cycle fluctuates, and fluctuations in the blowing temperature and refrigeration capacity occur. For this reason, the temperature of the evaporator-side heat exchanger (the indoor heat exchanger 4 during the cooling operation, the outdoor heat exchanger 2 during the heating operation), and the blowout temperature of the indoor heat exchanger 4 measured by the blowout temperature sensor 24. Thus, the fluctuation of the evaporation pressure can be estimated.

A compressor rotation speed control routine in the refrigeration cycle apparatus of the second embodiment will be described with reference to FIG. Rotational speed of the compressor 1, as described above, read the indoor temperature Tea _in detected by the indoor temperature sensor 16 provided near the ventilation passage inlet of the indoor heat exchanger 4 (step 31), is set from the remote controller A difference ΔTea _in from the set temperature (target indoor temperature) T ^* ea _in is obtained (step 32), and the rotation speed of the compressor 1 is varied by the inverter 18 in accordance with this difference (steps 33 and 34). Here, as the difference between the set temperature and the detected room temperature becomes smaller, the compressor rotational speed _fz is controlled to become smaller.

In step 35, the compressor rotational speed f _z is the smaller than the rotational speed f _z opt for the capacitive control operation starts, the compressor rotational speed is fixed to f _z opt, from the difference between the indoor temperature and the indoor temperature target value The determined initial duty ratio d is determined (steps 36 and 37), and the PWM capacity control operation for turning the solenoid valve 12 on and off is performed. At this time, the timer of the control unit is also turned on at the same time as the PWM control signal is turned on, and measurement of the elapsed time τ1 is started. Further, the measurement of the evaporator side heat exchanger temperature Tev0 by the temperature sensor (14 or 15) of the heat exchanger on the evaporator side is started (step 61), and further the evaporator side heat exchanger temperature at the start of the measurement. and Tev0, from said air temperature Tea _out of the air temperature sensor 24 indoor heat exchanger 4 detected by, according to the table to hold a predetermined control constant to calculate a tolerance DerutaTev (step 62). Compared to the evaporator side heat exchanger temperature Tev0 before the PWM control signal is turned ON, the PWM control signal remains ON until the measured evaporator side heat exchanger temperature Tev exceeds the allowable deviation ΔTev, and the evaporator The measurement of the side heat exchanger temperature Tev is repeated (steps 63 to 65). When the difference between the measured evaporator side heat exchanger temperature Tev and the initial heat exchanger temperature Tev0 exceeds the allowable deviation ΔTev, the PWM control signal is turned OFF, the solenoid valve 12 is closed, and the timer is turned OFF. Then, the elapsed time measurement is finished, and τ1 is determined as the opening time. The closing time τ2 is determined from this τ1 and the current duty ratio d, and the PWM capacity control operation is performed based on this duty cycle (steps 66 and 67).

On the other hand, the opening degree control of the expansion valve 3 is controlled according to the same routine as the expansion valve opening degree control routine in the first embodiment shown in FIG.
According to this embodiment, since the fluctuation of the suction pressure (evaporation pressure) due to the opening and closing of the solenoid valve 12 is determined in a range based on the allowable deviation ΔTev, the evaporation can be performed by setting the allowable range ΔTev to an appropriate range. Even without a pressure sensor (suction pressure sensor) for measuring pressure, it is possible to suppress fluctuations in the evaporation pressure within a certain range, and it can be manufactured at a lower cost, and the capacity control operation with high air conditioning comfort and high efficiency. Can be realized.

FIG. 7 is a schematic configuration diagram of a refrigeration cycle apparatus showing a third embodiment of the present invention, which is used for a room air conditioner as in the first and second embodiments. In FIG. 7, the same reference numerals as those in FIGS. 1 and 5 denote the same or corresponding parts. Further, in the third embodiment, the difference from the first and second embodiments is that the suction pressure sensor 23 in the first embodiment and the blowout temperature provided in the vicinity of the ventilation passage outlet of the indoor heat exchanger 4 in the second embodiment. This is the point where the sensor 24 is removed.

When performing control using a capacity adjustment mechanism that performs small capacity control, when the PWM control signal is turned on (i.e., the solenoid valve 12 is in an open state), the evaporation pressure rises and the PWM control signal is turned off (i.e., When the solenoid valve 12 is in the closed state, the evaporation pressure decreases. At this time, the evaporation temperature also fluctuates, and the amount of heat exchange in the evaporator fluctuates. Therefore, the refrigeration cycle fluctuates, and fluctuations in the blowing temperature and refrigeration capacity occur. For this reason, by controlling the temperature of the evaporator side heat exchanger (the indoor heat exchanger 4 during the cooling operation and the outdoor heat exchanger 2 during the heating operation), the fluctuation of the evaporation pressure is estimated and controlled. Can do.

As described above, during normal operation, the evaporator-side heat exchanger is operated under discharge superheat control so that the suction superheat degree is zero at the outlet, that is, the dryness is 1. Since the dryness is usually about 0.1 to 0.3 at the inlet of the evaporator-side heat exchanger, the heat exchanger has a distribution in which the dryness gradually increases from the inlet toward the outlet. During capacity control operation, the amount of refrigerant circulating decreases, and the amount of refrigerant flowing out of the evaporator-side heat exchanger decreases relative to the amount of refrigerant flowing into the evaporator-side heat exchanger. Although the temperature rises and the evaporation temperature rises, the liquid refrigerant in the evaporator changes from the liquid phase to the gas phase due to heat exchange with air, and the dryness increases. Therefore, in the evaporator side heat exchanger, it gradually dries from the outlet side, and the heat exchange amount becomes extremely small from the side close to the outlet. When the heat exchanger temperature sensor (14 or 15) is arranged near the center of the heat exchanger, the evaporator side heat exchanger temperature (evaporator temperature) Tev measured by this sensor is as shown in FIG. . That is, when the PWM control signal is turned ON, the evaporator temperature Tev gradually rises and gradually dries from the outlet side of the heat exchanger, so that the heat exchanger temperature sensor (14 or 15) is installed. The measured temperature rises rapidly when the area around it is dry. For this reason, it becomes possible to grasp | ascertain the dryness distribution in an evaporator with the temperature measurement position in an evaporator side heat exchanger. Therefore, the duty cycle T is set according to the dryness at the temperature measurement position by setting the allowable deviation ΔTev of the evaporator temperature to the value after the rapid temperature rise occurs when turning off the PWM control signal. I can decide.

Although the installation position of the heat

exchanger temperature sensor

14 or 15 is set near the center of the heat exchanger in the present embodiment, the installation position may be appropriately selected so that the variation of the air conditioning capability can be appropriately allowed. .

A compressor rotation speed control routine in the refrigeration cycle apparatus of the third embodiment will be described with reference to FIG. Rotational speed of the compressor 1, as described above, read the indoor temperature Tea _in detected by the indoor temperature sensor 16 provided near the ventilation passage inlet of the indoor heat exchanger 4 (step 31), is set from the remote controller A difference ΔTea _in from the set temperature (target indoor temperature) T ^* ea _in is obtained (step 32), and the rotation speed of the compressor 1 is varied by the inverter 18 in accordance with this difference (steps 33 and 34). Here, as the difference between the set temperature and the detected room temperature becomes smaller, the compressor rotational speed _fz is controlled to become smaller.

In step 35, the compressor rotational speed f _z is the smaller than the rotational speed f _z opt for the capacitive control operation starts, the compressor rotational speed is fixed to f _z opt, from the difference between the indoor temperature and the indoor temperature target value The determined initial duty ratio d is determined (steps 36 and 37), and the PWM capacity control operation for turning the solenoid valve 12 on and off is performed. At this time, as soon as the PWM control signal is turned ON, the timer of the control unit is turned ON and measurement of the elapsed time τ1 is started. Further, the measurement of the evaporator side heat exchanger temperature (evaporator temperature) Tev0 by the temperature sensor (14 or 15) of the heat exchanger on the evaporation side is started (step 61), and further the evaporator temperature at the start of the measurement. It is preset from Tev0 and the air temperature Tai or Tao measured by the indoor temperature sensor 16 or the outdoor temperature sensor 17 provided in the vicinity of the ventilation passage entrance of the indoor heat exchanger 4 or the outdoor heat exchanger 2 serving as an evaporator. The allowable deviation ΔTev is calculated according to the table held as the control constant. This allowable deviation ΔTev is a temperature measurement position where the heat

exchanger temperature sensor

14 or 15 is installed, after the heat exchanger dries (the degree of dryness of the refrigerant increases), resulting in a rapid temperature rise. (Step 68). Compared to the heat exchanger temperature Tev0 before the PWM control signal is turned ON, the PWM control signal remains ON until the measured heat exchanger temperature Tev exceeds the allowable deviation ΔTev, and the evaporator side heat exchanger temperature Tev The measurement is repeated (steps 63 to 65). When the difference between the measured evaporator-side heat exchanger temperature Tev and the initial heat exchanger temperature Tev0 exceeds the allowable deviation ΔTev, the PWM control signal is turned OFF, the solenoid valve 12 is closed, and the timer is turned OFF. Then, the elapsed time measurement is finished, and τ1 is determined as the opening time. The closing time τ2 is determined from this τ1 and the current duty ratio d, and the PWM capacity control operation is performed by this duty cycle (steps 66 and 67).

On the other hand, the opening degree control of the expansion valve 3 is controlled according to the same routine as the expansion valve opening degree control routine in the first embodiment shown in FIG.
According to this embodiment, since the fluctuation of the suction pressure (evaporation pressure) due to the opening and closing of the solenoid valve 12 is determined in a range based on the allowable deviation ΔTev, the evaporation can be performed by setting the allowable range ΔTev to an appropriate range. Even if there is no suction pressure sensor 23 (see FIG. 1) for measuring the pressure or a blowout temperature sensor 24 (see FIG. 5) for measuring the air blowing temperature into the room, the fluctuation of the evaporation pressure is kept within a certain range. In addition, it is possible to realize a refrigeration cycle apparatus that can be manufactured at a lower cost and that is capable of air-conditioning comfort and high-efficiency capacity control operation.

Next, an example of a capacity control compressor used in the refrigeration cycle apparatus of each of the above-described embodiments of the present invention will be described. 10 is a longitudinal sectional view showing a scroll compressor as an example of a capacity control compressor used in the present invention, and FIG. 11 is a diagram showing a normal operation of the scroll compressor shown in FIG. 10 (the solenoid valve 12 of the capacity adjusting mechanism is closed). FIG. 12 is an enlarged cross-sectional view of the main part for explaining the flow of the refrigerant gas in the operation mode in the state, and FIG. 12 is an operation in which the solenoid valve 12 of the capacity adjustment mechanism is in the open state during the bypass operation of the capacity control compressor shown in FIG. It is a principal part expanded sectional view explaining the flow of the refrigerant gas at the time of mode.

The scroll compressor 1 includes a fixed scroll 102 having a spiral wrap in a sealed case (chamber) 115 provided with a suction pipe 113 for sucking refrigerant gas and a discharge pipe 114 for discharging compressed refrigerant gas. And a compression mechanism portion composed of the orbiting scroll 101 having a spiral wrap meshing with the fixed scroll 102 is provided. A motor 100 including a rotor 100a and a stator 100b is provided below the compression mechanism, and a crankshaft 106 serving as a rotation main shaft is integrally connected to the rotor 100a. The crankshaft 106 is rotatably supported by a main bearing 105 a provided on the frame 105 and an auxiliary bearing 112 provided on the lower frame 111 below the sealed case 115. An orbiting bearing 130 is provided on the back of the orbiting scroll 101, and an eccentric portion 106 a provided on the upper end side of the crankshaft 106 is inserted into the orbiting bearing 130. Reference numeral 107 denotes an Oldham ring (rotation prevention member). When the crankshaft 106 is rotated by the Oldham ring 107, the orbiting scroll 101 performs a revolving motion without rotating and compresses the refrigerant gas sucked from the suction pipe 113. To do.

The spiral wraps provided on the respective end plates of the orbiting scroll 101 and the fixed scroll 102 are configured as asymmetric wraps having different winding angles, whereby the orbiting scroll 101 and the fixed scroll 102 are engaged with each other. As a result, the two sealed chambers formed on the inner line side and the outer line side of the orbiting scroll wrap have asymmetric scroll shapes with different maximum sealed volumes.

That is, by engaging the spiral wraps formed by the involute curves of the orbiting scroll 101 and the fixed scroll 102 with each other, compression chambers are formed on the outer line side and the inner line side of the wrap on the winding end side of the orbiting scroll 101, respectively. However, the compression chamber formed on the outer line side and the compression chamber formed on the inner line side have different sizes and are formed with a phase shift of about 180 degrees with respect to the shaft rotation of the crankshaft 106. .

Specifically, the discharge port 108 is opened near the center of the fixed scroll 102, and the winding end of the spiral wrap is about 180 degrees to the vicinity of the winding end of the spiral wrap of the orbiting scroll 101. It is extended. For this reason, when the spiral wraps of the orbiting scroll 101 and the fixed school 102 are combined to form a compression chamber, they are confined by the outer line side of the spiral scroll of the orbiting scroll 101 and the inner line side of the spiral wrap of the fixed scroll 102. The size of the first compression chamber formed is different from the size of the second compression chamber formed by being confined by the inner side of the spiral wrap of the orbiting scroll 101 and the outer side of the spiral wrap of the fixed scroll 102. The phase of the crankshaft 106 is shifted by about 180 degrees.

In this scroll compressor, a release port 125 communicating with the compression chamber is formed on the outer peripheral side of the discharge port 108 in the fixed scroll 102, and a release valve 124, which is an overcompression prevention valve, is formed in the release port 125. Is provided. A discharge head cover 118 attached to the top plate (upper surface of the end plate) of the fixed scroll 102 forms a discharge head space 123 so as to cover the discharge port 108 and the release valve 124, and a through hole 119 provided at a predetermined location. A discharge valve 121 を持つ having a check valve action for opening or closing the valve is provided.

Further, the bypass pipe 11 guides the refrigerant gas in the discharge head space 123 to the outside of the sealed case 115, one end side is coupled to the discharge head cover 118, passes through the sealed case 115, and the other end side is outside the sealed case 115. Has been pulled out. The other end of the bypass pipe 11 communicates with the suction pipe 113 for sucking refrigerant gas, and a solenoid valve 12 is provided in the middle of the bypass pipe 11. The solenoid valve 12 is configured to be driven and controlled to an open state and a closed state by a pulse width adjustment (PWM) control signal described in each of the above-described embodiments.

The discharge head cover 118, the bypass pipe 11, and the solenoid valve 12 provide a bypass flow path for guiding the refrigerant gas in the discharge head space 123 from the bypass pipe 11 to the suction pipe 113 when the solenoid valve 12 is opened. Forming. Further, in the ultra-small capacity operation mode, the solenoid valve 12 is repeatedly operated between an open state and a closed state, and the presence or absence of use of the bypass flow path is repeated to act as a capacity adjustment mechanism for performing small capacity control.

The suction pipe 113 is for taking in the refrigerant gas of the refrigeration cycle, and is connected to the fixed scroll 102. The lower end side of the crankshaft 106 in the sealed case 115 is an oil reservoir 116 that stores oil. Further, a flywheel 117 for stabilizing rotation is provided between the rotor 100 a and the auxiliary bearing 112 in the crankshaft 106.

In the back pressure chamber (intermediate chamber) 109 formed by the fixed scroll 102, the orbiting scroll 101 及び, and the frame 105, oil supplied from the oil reservoir 116 is provided around the eccentric portion 106 a of the crankshaft 106. Guided through slewing bearing 130. The back pressure chamber 109 is configured such that when the refrigerant gas in the oil is foamed and the pressure rises, the increased pressure is released to the suction side by a control valve (not shown) to maintain a predetermined pressure level. . This suction side passes through a fixed outer peripheral groove provided on the outer periphery of the spiral body of the fixed scroll 102. Since this fixed outer peripheral groove reaches the refrigerant gas inlet, the fixed outer peripheral groove is always inhaled. Pressure. In the orbiting scroll 101, the discharge pressure acts on the central portion, and the intermediate pressure acts on the outer peripheral portion. For this reason, the orbiting scroll 101 is pressed against the fixed scroll 102 with an appropriate pressure, and the seal in the axial direction between the scroll wraps is maintained.

In the case of this scroll compressor, when the refrigerant gas compressed in the compression chamber becomes equal to or higher than the pressure in the discharge head space 123, the refrigerant gas in the compression chamber is discharged through the release port 125 and the release valve 124 into the discharge head space. 123 is discharged. When the pressure is less than the pressure in the discharge head space 123, the release valve 124 is closed, discharged from the discharge port 108 into the discharge head space 123, and further, the discharge valve 121 is pushed away from the through hole 119 to discharge chamber. 103 is discharged. The refrigerant gas discharged into the discharge chamber 103 passes through the passage formed between the fixed scroll 102 and the frame 105 and the sealed case 115 and flows into the discharge space 104 where the motor 100 is provided. To the refrigeration cycle via the discharge pipe 114. Accordingly, the sealed case 115 has a high-pressure chamber structure in which a discharge pressure space is provided.

Outside the scroll compressor 1, an inverter 18 that is a motor drive circuit for driving the motor 100 and a pulse width adjustment control signal for driving and controlling the open state and the closed state of the solenoid valve 12 are generated. And a control unit 20 as operation instruction control means for controlling operations of the inverter 18 and the solenoid drive circuit 12a according to operation instructions.

The compression operation of the scroll compressor is divided into a first operation mode when the solenoid valve 12 is closed and a second operation mode when the solenoid valve 12 is open.
FIG. 11 shows the flow of the refrigerant gas in the first operation mode in which the solenoid valve 12 of the capacity adjustment mechanism provided in the scroll compressor is in the closed state.

In the first operation mode, the solenoid drive circuit 12a closes the solenoid valve 12 at the period τ2 of the falling edge of the rectangular wave of the pulse width adjustment control signal, and the inverter 18 drives the motor 100 to drive the rotor 100a. And the crankshaft 106 is rotated. Along with this, the orbiting scroll 101 starts the orbiting motion. By this operation, the first compression chamber and the second compression chamber formed by the engagement of the spiral bodies of the orbiting scroll 101 and the fixed scroll 102 move toward the center while reducing their volumes.

Thereby, the refrigerant gas flowing in from the suction pipe 113 is compressed in the first compression chamber and the second compression chamber, and the high-pressure refrigerant gas is discharged from the discharge port 108 formed in the fixed scroll 102. The ink is discharged into the head space 123. When the pressure in the compression chamber becomes higher than the pressure in the discharge head space 123 during the compression process, the refrigerant gas whose pressure has been increased through the release port 125 and the release valve 124 as described above enters the discharge head space 123. Discharged.

The release valve 124 indicates a valve plate portion attached to the tip of a coil spring 127 attached to the tip side of the holding portion 126, but a release valve mechanism including the holding portion 126 and the coil spring 127. The entire part is sometimes called a release valve.

When the refrigerant gas pressure in the discharge head space 123 is slightly higher than the discharge pressure and higher than the pressure in the discharge chamber 103, the discharge valve 121 covering the through hole 119 of the discharge head cover 118 is pushed open, and the refrigerant gas is discharged into the discharge chamber 103. Discharged.

In the first operation mode, the solenoid valve 12 is closed and the refrigerant gas is allowed to flow to the refrigeration cycle side without using the bypass pipe 11, so it may be called a load operation.

FIG. 12 shows the flow of the refrigerant gas in the second operation mode in which the solenoid valve 12 of the capacity adjustment mechanism provided in the scroll compressor is in the open state.

In the second operation mode, the solenoid drive circuit 12a opens the solenoid valve 12 at the period τ1 of the rising edge of the rectangular wave of the pulse width adjustment control signal, and the inverter 18 drives the motor 100 to drive the rotor 100a and the crank. The shaft 106 is rotated. Along with this, the orbiting scroll 101 starts the orbiting motion. By this operation, as in the first operation mode, the first compression chamber and the second compression chamber formed by the engagement of the spiral bodies of the orbiting scroll 101 and the fixed scroll 102 are reduced in volume while being reduced in the center direction. Move to.

In this second operation mode, since the solenoid valve 12 is in an open state, the refrigerant gas in the discharge head space 123 causes the bypass pipe 11 connecting the discharge head space 123 and the suction pipe 113. Through the suction pipe 113. For this reason, the pressure in the discharge head space 123 is reduced to almost the suction pressure that is slightly higher than the suction pressure.

For this reason, the pressure in the discharge head space 123 is lower than the pressure in the discharge chamber 103 and the discharge valve 121 covering the through hole 119 of the discharge head cover 118 is closed, so that the refrigerant gas is not discharged into the discharge chamber 103. In the state of the second operation mode, when the refrigerant gas flowing in from the suction pipe 113 is compressed in the first compression chamber and the second compression chamber, the pressure becomes higher than the pressure in the discharge head space 123. Therefore, the refrigerant gas is discharged into the discharge head space 123 through the release port 125 and the release valve 124. The refrigerant gas in the compression chamber that has moved further to the center side than the release port 125 is discharged from the discharge port 108 into the discharge head space 123. The refrigerant gas discharged into the discharge head space 123 flows to the suction pipe 113 through the bypass pipe 11 and the opened solenoid valve 12.

In the second operation mode, the solenoid valve 12 is opened, the refrigerant gas is returned from the bypass pipe 11 to the suction pipe 113 side, and the refrigerant gas is not discharged to the refrigeration cycle side. .

Note that it is desirable that the release port 125 and the release valve 124 are provided at a position where they are communicated with the compression chambers in all rotation angle regions. The reason is that the internal compression at the scroll wrap can be avoided and the compression operation at the unload operation becomes small.

In the scroll compressor according to the first embodiment, the motor 100 is driven by the inverter 18 and the solenoid valve 12 is closed at the period τ2 of the rectangular wave falling section of the pulse width adjustment control signal from the solenoid drive circuit 12a. The capacity control can be performed by switching between the load operation (first operation mode) and the unload operation (second operation mode) in which the solenoid valve 12 is opened at the period τ1 of the rectangular wave rising section. it can.

Even in the high-speed operation mode in which the scroll compressor is operated at a relatively high speed, the capacity can be controlled by opening and closing the solenoid valve 12. However, the high-speed rotation is slightly higher than the lower limit set value of the rotation speed driven by the motor. In the rotation range up to the set value, the rotation speed control of the motor 100 is performed by the inverter 18, and when it is necessary to further reduce the capacity in the low speed rotation range below the predetermined set value, the small capacity control is performed. It is preferable to operate by changing the ratio of the load operation and the unload operation as an ultra-small capacity operation mode by operating the capacity adjusting mechanism (control of opening and closing of the bypass passage by a solenoid valve).

In the scroll compressor provided with the capacity adjusting mechanism as described above, the capacity adjusting mechanism having a simple structure can efficiently perform the small capacity control even in the ultra-small capacity operation mode. That is, the compression operation in the ultra-small capacity control (ultra-small capacity operation mode) corresponding to the ultra-low speed operation below the lower limit set value of the rotation speed by the motor drive (frequency about 5 Hz in the drive signal to the motor 100). Can be executed without degrading the efficiency of motor drive, and an excellent scroll compressor capable of realizing a wide capacity control of 0 to 100% can be obtained. Further, since the capacity adjusting mechanism provided in the scroll compressor of this embodiment has a simple structure, the scroll compressor can be easily reduced in cost, size, weight and mass production.

As described above, according to the refrigeration cycle apparatus of the present embodiment, the duty cycle, which is the cycle of the switching time between the load operation and the unload operation, is controlled so that the deviation of the evaporation pressure is within a certain value. In addition, it is possible to suppress the rise and fluctuation of the suction pressure within a threshold value, and it is possible to improve comfort such as comfortable air conditioning. In addition, according to the present embodiment, an increase in loss due to an excessively short duty cycle can also be prevented, so that highly efficient operation can be realized, and excellent capacity control is possible with a wide range of 0 to 100% with high efficiency. A refrigeration cycle apparatus with performance can be realized. In addition, according to the present embodiment, high-efficiency and wide-range capacity control can be realized with a simple configuration, so that the cost can be reduced.

1: compressor,
2: Outdoor heat exchanger,
3: expansion valve,
4: Indoor heat exchanger,
5: Four-way valve,
7: High-pressure side connection piping, 8: Outdoor connection piping, 9: Indoor connection piping, 10: Low-pressure side connection piping,
11: Bypass piping (bypass flow path),
12: Solenoid valve, 12a: Solenoid drive circuit,
13: Discharge temperature sensor, 14: Indoor heat exchanger temperature sensor,
15: Outdoor heat exchanger temperature sensor,
16: Indoor temperature sensor, 17: Outdoor temperature sensor,
18: Inverter, 19: Commercial AC power supply,
20: control unit,
21: Outdoor fan, 22: Indoor fan,
23: Suction pressure sensor, 24: Blowing temperature sensor,
100: motor (100a: rotor, 100b: stator),
101: Orbiting scroll, 102: Fixed scroll, 103: Discharge chamber,
104: discharge space, 105: frame, 105a: main bearing,
106: Crankshaft, 106a: Eccentric part, 107: Oldham ring,
108: discharge port, 109: back pressure chamber (intermediate chamber),
111: Lower frame, 112: Secondary bearing,
113: suction pipe, 114: discharge pipe,
115: Sealed case, 116: Oil storage,
117: Flywheel,
118: Discharge head cover, 119: Through hole,
121: discharge valve,
123: Discharge head space
124: Release valve, 125: Release port, 126: Holding part,
127: coil spring,
130: Slewing bearing.

Claims

In a refrigeration cycle apparatus comprising a compressor, an outdoor heat exchanger, an expansion valve capable of opening control, and an indoor heat exchanger,
A bypass flow path for bypassing the refrigerant being compressed in the compressor to the suction side of the compressor;
A solenoid valve for opening and closing the bypass flow path;
A controller for controlling the capacity by adjusting the flow rate of the refrigerant discharged from the compressor to the refrigeration cycle by controlling the time of opening (ON) and the time of closing (OFF) of the solenoid valve. ,
The control unit performs control based on a duty ratio that is a ratio of an opening time to a duty cycle that is a sum of the opening time and the closing time of the solenoid valve,
When the solenoid valve is in an open state, when the pressure on the suction side of the compressor is equal to or larger than an allowable deviation with respect to the suction pressure before the solenoid valve is opened, the solenoid valve is controlled to be in a closed state, The refrigeration cycle apparatus is controlled such that the closing time is determined based on the duty ratio.
2. The refrigeration cycle apparatus according to claim 1, wherein the duty ratio is determined based on a difference between an indoor temperature and a set indoor temperature target value.
2. The refrigeration cycle apparatus according to claim 1, wherein the control unit controls an opening degree of the expansion valve so that a discharge refrigerant temperature discharged from the compressor approaches a target discharge temperature. Refrigeration cycle equipment.
4. The refrigeration cycle apparatus according to claim 3, wherein when the solenoid valve is controlled to be in a closed state, the target discharge temperature is the temperature of the outdoor heat exchanger (condensation temperature), the outside air temperature, and the rotation of the compressor. When the solenoid valve is controlled to be in an open state, the duty ratio at that time is multiplied by the compressor rotational speed at the start of the solenoid valve opening / closing control. The refrigeration cycle is determined based on the corrected compressor rotational speed, the outdoor heat exchanger temperature (condensation temperature), the outdoor air temperature, and the outdoor fan rotational speed command value. apparatus.
2. The refrigeration cycle apparatus according to claim 1, wherein the pressure on the suction side of the compressor is detected by a suction pressure sensor provided on the suction side of the compressor.
2. The refrigeration cycle apparatus according to claim 1, wherein the pressure on the suction side of the compressor exceeds an allowable deviation with respect to the suction pressure before the solenoid valve is opened, the indoor heat serving as an evaporator. A refrigeration cycle apparatus characterized in that it is determined by estimating a fluctuation in evaporation pressure based on a temperature of an exchanger or an outdoor heat exchanger and a blowing temperature of the indoor heat exchanger.
The refrigeration cycle apparatus according to claim 1, further comprising a temperature sensor that detects a temperature near a center of the indoor heat exchanger or the outdoor heat exchanger that serves as an evaporator, and evaporates based on the temperature detected by the temperature sensor. A refrigeration cycle apparatus characterized by estimating a pressure fluctuation and determining that the pressure on the suction side of the compressor is equal to or greater than an allowable deviation with respect to the suction pressure before the solenoid valve is opened.
In a refrigeration cycle apparatus comprising a compressor, an outdoor heat exchanger, an expansion valve capable of opening control, and an indoor heat exchanger,
A bypass flow path for bypassing the refrigerant being compressed in the compressor to the suction side of the compressor;
A solenoid valve for opening and closing the bypass flow path;
A controller for controlling the capacity by adjusting the flow rate of the refrigerant discharged from the compressor to the refrigeration cycle by controlling the time of opening (ON) and the time of closing (OFF) of the solenoid valve. ,
The control unit performs control based on a duty ratio that is a ratio of an opening time to a duty cycle that is a sum of the opening time and the closing time of the solenoid valve,
When the solenoid valve is in the open state, the evaporator temperature of the indoor heat exchanger or the outdoor heat exchanger (evaporator side heat exchanger) serving as an evaporator becomes the evaporator temperature before the solenoid valve is opened. On the other hand, when the deviation exceeds an allowable deviation, the solenoid valve is controlled to be in a closed state, and the closing time is controlled based on the duty ratio.
9. The refrigeration cycle apparatus according to claim 8, wherein a blowout temperature sensor is provided in the vicinity of a ventilation path outlet of the indoor heat exchanger, and the allowable deviation is calculated based on an evaporator temperature before the solenoid valve is opened, and the blowout temperature. A refrigeration cycle apparatus that is calculated from a blowout temperature of an indoor heat exchanger detected by a sensor according to a table that is preset and held as a control constant.
9. The refrigeration cycle apparatus according to claim 8, wherein an evaporator temperature sensor that detects a temperature near a center of the evaporator-side heat exchanger, and a temperature sensor that is provided near a ventilation passage inlet of the evaporator-side heat exchanger. And the allowable deviation is measured by an evaporator temperature at the start of measurement detected by the evaporator temperature sensor and an air measured by a temperature sensor provided in the vicinity of the ventilation passage inlet of the evaporator-side heat exchanger. A refrigeration cycle apparatus which is calculated from a temperature according to a table which is set in advance and held as a control constant.
9. The refrigeration cycle apparatus according to claim 8, wherein the duty ratio is determined based on a difference between an indoor temperature and a set indoor temperature target value.
9. The refrigeration cycle apparatus according to claim 8, wherein the control unit controls the opening degree of the expansion valve so that a discharge refrigerant temperature discharged from the compressor approaches a target discharge temperature. Refrigeration cycle equipment.
13. The refrigeration cycle apparatus according to claim 12, wherein the target discharge temperature is the temperature of the outdoor heat exchanger (condensation temperature), the outside air temperature, and the rotation of the compressor when the solenoid valve is controlled to be closed. When the solenoid valve is controlled to be in an open state, the duty ratio at that time is multiplied by the compressor rotational speed at the start of the solenoid valve opening / closing control. The refrigeration cycle is determined based on the corrected compressor rotational speed, the outdoor heat exchanger temperature (condensation temperature), the outdoor air temperature, and the outdoor fan rotational speed command value. apparatus.
2. The refrigeration cycle apparatus according to claim 1, wherein the compressor is configured such that a spiral body of the orbiting scroll and a spiral body of the fixed scroll are meshed with each other in a sealed case to form a compression chamber. The present invention is a scroll compressor in which a discharge port is formed in a portion, a release port communicating with the compression chamber is provided on the outer peripheral side of the discharge port, and a release valve that opens and closes the release port. Refrigeration cycle equipment.
15. The refrigeration cycle apparatus according to claim 14, wherein the bypass flow path is a bypass pipe that connects a release port provided in the scroll compressor and a suction pipe provided on a suction side of the scroll compressor. The refrigeration cycle apparatus is characterized in that the bypass valve is provided with the solenoid valve.
16. The refrigeration cycle apparatus according to claim 15, wherein the scroll compressor includes a discharge head cover that is attached to a top plate of the fixed scroll and covers the discharge port and the release valve to form a discharge head space. Includes a through hole communicating with the discharge chamber in the sealed case and a discharge valve for opening and closing the through hole, and the bypass pipe is provided to connect the discharge head space and the suction pipe. The refrigeration cycle apparatus is configured so that the solenoid valve is driven and controlled to an open state and a closed state by a pulse width adjustment (PWM) control signal.