CN118284778A

CN118284778A - Refrigeration cycle device and control method

Info

Publication number: CN118284778A
Application number: CN202180100693.XA
Authority: CN
Inventors: 福井孝史; 森有辉; 中井孝洋
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2021-12-07
Filing date: 2021-12-07
Publication date: 2024-07-02
Also published as: WO2023105605A1; JPWO2023105605A1; US20240263855A1

Abstract

The present invention provides a refrigeration cycle device, comprising: a refrigeration cycle including a compressor for compressing a refrigerant; an operation state detection unit that detects an operation state of the refrigeration cycle; a protection target value determination unit that determines a protection target value of a protection variable relating to the refrigeration cycle based on the operation state; and a rotation speed determination unit that determines the rotation speed of the compressor based on at least the capacity target value and the protection target value of the temperature adjusted by the refrigeration cycle. This can suppress unnecessary performance restrictions.

Description

Refrigeration cycle device and control method

Technical Field

The present invention relates to a refrigeration cycle apparatus and a control method.

Background

Conventionally, there is a control device for a refrigeration cycle device that calculates an upper limit speed of a speed command of an inverter motor based on a limit value of a high-pressure side of a refrigerant and a detected pressure on a high-pressure side (for example, refer to patent document 1). This can suppress the high-pressure of the refrigerant to an allowable value and can obtain a speed command of the inverter motor suitable for the load.

Patent document 1: japanese patent laid-open publication No. 2005-16753

However, since the limit value of the high-pressure of the refrigerant, which is a fixed value, needs to be a value that can protect the refrigeration cycle apparatus in any situation, there is a problem that the speed of the inverter motor, that is, the performance of the refrigeration cycle apparatus, may be unnecessarily limited depending on the situation.

Disclosure of Invention

The present disclosure has been made in view of such circumstances, and provides a refrigeration cycle apparatus and a control method capable of suppressing unnecessary performance restrictions.

The present disclosure has been made to solve the above-described problems, and one aspect of the present disclosure is a refrigeration cycle apparatus including: a refrigeration cycle including a compressor for compressing a refrigerant; an operation state detection unit configured to detect an operation state of the refrigeration cycle; a protection target value determining unit configured to determine a protection target value of a protection variable related to the refrigeration cycle based on the operation state; and a rotation speed determination unit that determines an operation rotation speed of the compressor based on at least a capacity target value of the temperature adjusted by the refrigeration cycle and the protection target value.

In another aspect of the present disclosure, the rotation speed determining unit includes an I (integral) controller, a PI (proportional integral) controller, or a PID (proportional integral derivative) controller that controls the protection variable to gradually approach the protection target value.

In another aspect of the present disclosure, the refrigeration cycle apparatus is characterized in that the protection variable includes any one of a discharge temperature of the refrigerant discharged from the compressor, a condensation temperature of the refrigerant, an evaporation temperature of the refrigerant, a high pressure of the refrigerant, and a low pressure of the refrigerant.

Another aspect of the present disclosure is the refrigeration cycle apparatus described above, wherein the operation state is an outside air temperature or an indoor air temperature.

In addition, another aspect of the present disclosure is the refrigeration cycle apparatus described above, wherein the refrigeration cycle apparatus further includes a storage unit that stores a correspondence between the outside air temperature or the indoor air temperature and the protection target value, and the protection target value determination unit determines the protection target value with reference to the correspondence stored in the storage unit.

Another aspect of the present disclosure is the refrigeration cycle apparatus, wherein the operation state is a condensation temperature or a high-pressure of the refrigerant and an evaporation temperature or a low-pressure of the refrigerant.

In addition, another aspect of the present disclosure is the refrigeration cycle apparatus described above, wherein the refrigeration cycle apparatus further includes a storage unit that stores an operation map indicating an operation pressure range or an operation temperature range of the refrigerant, and the protection target value determination unit determines the protection target value corresponding to the operation state with reference to the operation map stored in the storage unit.

Another aspect of the present disclosure is a control method of a refrigeration cycle apparatus including a compressor configured to compress a refrigerant, the control method including: detecting an operation state of the refrigeration cycle apparatus; determining a protection target value of a protection variable related to the refrigeration cycle device based on the operation state; and determining an operation rotation speed of the compressor based on at least a capacity target value of the temperature adjusted by the refrigeration cycle device and the protection target value.

According to the present disclosure, it is possible to suppress performance of the refrigeration cycle apparatus from being unnecessarily limited.

Drawings

Fig. 1 is a refrigerant circuit diagram showing a configuration of an air conditioner 100 according to embodiment 1 of the present disclosure.

Fig. 2 is a block diagram showing the configuration of the control unit 30 according to this embodiment.

Fig. 3 is a functional block diagram showing a functional configuration of the control unit 30 according to this embodiment.

Fig. 4 is a flowchart showing a flow of control operation of the compressor 1 of the air conditioner 100 according to the embodiment.

Fig. 5 is an operation chart showing operation pressure ranges of the air conditioner 200 according to embodiment 2 of the present disclosure.

Detailed Description

Embodiment 1

Embodiment 1 of the present disclosure will be described below with reference to the drawings. In embodiment 1, the air conditioning apparatus 100 is illustrated as the refrigeration cycle apparatus, but other apparatuses such as a heat pump type water heater may be used as long as the refrigeration cycle apparatus is used.

Fig. 1 is a refrigerant circuit diagram schematically showing an air conditioner 100 according to embodiment 1 of the present disclosure. The air conditioner 100 is a device that performs a vapor compression refrigeration cycle operation to cool and heat a room. The air conditioner 100 includes a heat source unit a and a usage unit B. The heat source unit a and the usage unit B are connected via a liquid connection pipe 6 and a gas connection pipe 9, which are refrigerant communication pipes. Further, the plurality of usage units B may be connected to the heat source unit a via the liquid connection pipe 6 and the gas connection pipe 9.

Examples of the refrigerant used in the air conditioner 100 include HFC refrigerants such as R410A, R407C, R404A, R, HFO refrigerants such as R1234yf/ze, HCFC refrigerants such as R22 and R134a, and natural refrigerants such as carbon dioxide (CO ₂), hydrocarbons, helium, and propane.

< Utilization unit B >)

The usage unit B is installed by a method of installing a ceiling in a room, suspending from a ceiling, or the like, or by a method of installing a wall surface in a room, or the like. The usage unit B is also called an indoor unit. The usage unit B is connected to the heat source unit a via the liquid connection pipe 6 and the gas connection pipe 9 as described above, and forms a part of the refrigerant circuit.

Next, the detailed configuration of the usage unit B will be described. The usage unit B constitutes an indoor-side refrigerant circuit that is a part of the refrigerant circuit, and includes an indoor blower 8 and an indoor heat exchanger 7 that is a usage-side heat exchanger.

Here, the indoor heat exchanger 7 is a fin-tube heat exchanger of a cross fin type constituted by a heat transfer tube and a plurality of fins. The indoor heat exchanger 7 functions as an evaporator of a refrigerant to cool the air in the room during the cooling operation, and functions as a condenser of the refrigerant to heat the air in the room during the heating operation.

The indoor air blowing device 8 is a fan capable of controlling the flow rate of air supplied to the indoor heat exchanger 7, and is configured by, for example, a centrifugal fan or a multi-wing fan driven by a DC motor (not shown). The indoor air blowing device 8 has a function of sucking indoor air into the usage unit B and supplying air, which has undergone heat exchange with the refrigerant by the indoor heat exchanger 7, as supply air into the room.

In addition, various sensors are provided in the utilization unit B. That is, on the liquid side of the indoor heat exchanger 7, a liquid side temperature sensor 205 is provided that detects the temperature of the refrigerant in a liquid state or a gas-liquid two-phase state (refrigerant temperature corresponding to the supercooled liquid temperature Tco during heating operation or the evaporation temperature Te during cooling operation). The indoor heat exchanger 7 is provided with a gas-side temperature sensor 207 that detects the temperature of the refrigerant in a gas-liquid two-phase state (the refrigerant temperature corresponding to the condensation temperature Tc during the heating operation or the evaporation temperature Te during the cooling operation). Further, on the side of the intake port of the indoor air of the usage unit B, an indoor temperature sensor 206 is provided that detects the temperature of the indoor air flowing into the unit (indoor air temperature). Here, the liquid-side temperature sensor 205, the gas-side temperature sensor 207, and the indoor temperature sensor 206 are each constituted by a thermistor. The liquid-side temperature sensor 205 and the gas-side temperature sensor 207 may measure the surface temperature of the heat transfer pipe or the like instead of the temperature of the refrigerant, or may directly measure the temperature of the refrigerant. The operation of the indoor air blowing device 8 is controlled by the control unit 30.

< Heat source unit A >)

The heat source unit a is installed outdoors. The heat source unit a is also called an outdoor unit. The heat source unit a is connected to the usage unit B via the liquid connection pipe 6 and the gas connection pipe 9, and constitutes a part of the refrigerant circuit.

Next, the detailed structure of the heat source unit a will be described. The heat source unit a includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 3 as a heat source side heat exchanger, an outdoor blower 4, and a pressure reducing device 5.

The pressure reducing device 5 is disposed on the liquid side of the heat source unit a for the purpose of adjusting the flow rate of the refrigerant flowing in the refrigerant circuit, and the like.

The compressor 1 is a compressor capable of controlling an operation capacity (frequency, operation rotation speed). Here, as the compressor 1, a positive displacement compressor driven by a motor (not shown) controlled by an inverter is used. Here, the number of compressors 1 is only 1, but the present invention is not limited thereto, and 2 or more compressors 1 may be connected in parallel according to the number of connection units B.

The four-way valve 2 is a valve having a function of switching the flow direction of the refrigerant. The four-way valve 2 switches the refrigerant flow path during the cooling operation such that the discharge side of the compressor 1 is connected to the gas side of the outdoor heat exchanger 3 and the suction side of the compressor 1 is connected to the gas connection pipe 9 (broken line of the four-way valve 2 in fig. 1). Thus, the four-way valve 2 causes the outdoor heat exchanger 3 to function as a condenser for the refrigerant compressed by the compressor 1, and causes the indoor heat exchanger 7 to function as an evaporator for the refrigerant condensed by the outdoor heat exchanger 3. The four-way valve 2 switches the refrigerant flow path during the heating operation so that the discharge side of the compressor 1 is connected to the gas connection pipe 9 side and the suction side of the compressor 1 is connected to the gas side of the outdoor heat exchanger 3 (solid line of the four-way valve 2 in fig. 1). Thus, the four-way valve 2 causes the indoor heat exchanger 7 to function as a condenser for the refrigerant compressed by the compressor 1, and causes the outdoor heat exchanger 3 to function as an evaporator for the refrigerant condensed by the indoor heat exchanger 7.

The outdoor heat exchanger 3 is constituted by a fin-and-tube heat exchanger of a cross fin type, which is constituted by a heat pipe and a plurality of fins, and has a gas side connected to the four-way valve 2 and a liquid side connected to the liquid connection pipe 6. The outdoor heat exchanger 3 functions as a condenser of the refrigerant during the cooling operation and functions as an evaporator of the refrigerant during the heating operation.

The outdoor air blowing device 4 is a fan capable of changing the flow rate of air supplied to the outdoor heat exchanger 3, and is configured by, for example, a propeller fan driven by a DC motor (not shown). The outdoor air-sending device 4 has a function of sucking in outdoor air into the heat source unit a by the fan and discharging the air having undergone heat exchange between the outdoor heat exchanger 3 and the refrigerant to the outside.

In addition, various sensors are provided in the heat source unit a. That is, the compressor 1 is provided with a discharge temperature sensor 201 that detects a discharge temperature Td and a compressor housing temperature sensor 208 that detects a housing temperature of the compressor 1. The outdoor heat exchanger 3 is provided with a gas-side temperature sensor 202 that detects the temperature of the refrigerant in a gas-liquid two-phase state (the refrigerant temperature corresponding to the condensation temperature Tc during cooling operation or the evaporation temperature Te during heating operation). Further, a liquid-side temperature sensor 204 that detects the temperature of the refrigerant in a liquid state or a gas-liquid two-phase state is provided on the liquid side of the outdoor heat exchanger 3. Further, an outdoor temperature sensor 203 for detecting the temperature of the outdoor air flowing into the unit, that is, the outside air temperature, is provided on the intake port side of the outdoor air of the heat source unit a. Here, the discharge temperature sensor 201, the gas side temperature sensor 202, the outdoor temperature sensor 203, the liquid side temperature sensor 204, and the compressor housing temperature sensor 208 are all constituted by thermistors. The discharge temperature sensor 201, the gas side temperature sensor 202, the outdoor temperature sensor 203, the liquid side temperature sensor 204, and the compressor housing temperature sensor 208 may measure the surface temperature of the heat transfer pipe or the like instead of the temperature of the refrigerant, or may directly measure the temperature of the refrigerant. The operations of the compressor 1, the four-way valve 2, the outdoor air blowing device 4, and the pressure reducing device 5 are controlled by the control unit 30.

The heat source unit a and the usage unit B described above are connected via the liquid connection pipe 6 and the gas connection pipe 9, and constitute a refrigerant circuit of the air conditioner 100. The lengths of the liquid connection pipe 6 and the gas connection pipe 9 may be different depending on the installation environment of the air conditioner 100, and may be short (for example, the total length is 10m or less) or long (for example, the total length is 100m or more).

The liquid connection pipe 6 and the gas connection pipe 9 connecting the heat source unit a and the usage unit B are generally constituted by copper pipes used as refrigerant pipes. Examples of the material of the copper pipe for the refrigerant piping include a material such as an o material, an OL material, an H material, and a 1/2H material. For example, the outer diameter of the piping in the copper pipe isWhen the wall thickness is 1.00mm, the highest operating pressure of the material is about 3.6MPa, and the highest operating pressure of the material H is about 6.7MPa, and even if the same size is used, the highest operating pressure varies depending on the material.

The materials of the liquid connection pipe 6 and the gas connection pipe 9 are generally selected based on the refrigerant used and the pressure used. However, when the old air conditioner installed in the past is updated, for example, when installed in a building or the like of a large-scale facility, the liquid connection pipe 6 and the gas connection pipe 9 connecting the heat source unit a and the usage unit B are inevitably long. Therefore, the construction cost for renewing the liquid connection pipe 6 and the gas connection pipe 9 increases, and thus the original pipe may be used for the liquid connection pipe 6 and the gas connection pipe 9. Therefore, even in the same air conditioner 100, the materials of the liquid connection pipe 6 and the gas connection pipe 9 may be different depending on the installation environment.

In the present embodiment, the configuration of 1 heat source unit a is described as an example, but the present disclosure is not limited to this, and a plurality of 2 or more heat source units a may be used. In the case where the heat source unit a and the usage unit B are each a plurality of units, the respective capacities may be different from large to small, or may be the same.

Fig. 2 is a block diagram showing the configuration of the control unit 30 according to the present embodiment.

Fig. 2 shows a control unit 30 for performing measurement control of the air conditioner 100 according to the present embodiment, and operation state information and an actuator connection structure connected to the control unit.

The control unit 30 is incorporated in the air conditioner 100, and includes a measurement unit 30a, a calculation unit 30b, a driving unit 30c, and a storage unit 30d.

The measurement unit 30a is an interface circuit with various sensors including a discharge temperature sensor 201, a gas side temperature sensor 202, an outdoor temperature sensor 203, a liquid side temperature sensor 204, a compressor housing temperature sensor 208, and the like. The measurement unit 30a measures the operation state indicating the operation state, such as the refrigerant pressure Pr, the refrigerant temperature Tr, the air temperature Ta, and the operation rotation speed (frequency) Rc of the compressor 1, by various sensors. The operation state quantity measured by the measuring unit 30a is input to the calculating unit 30b. The refrigerant pressure Pr includes a high pressure Pd and a low pressure Ps, the refrigerant temperature Tr includes a condensation temperature Tc and an evaporation temperature Te, and the air temperature Ta includes an outside air temperature and an indoor air temperature.

The arithmetic unit 30b is a processor such as CPU (Central Processing Unit). The arithmetic unit 30b reads and executes the program stored in the storage unit 30 d. The calculation unit 30b executes a program to calculate, for example, a physical property value (saturation pressure, saturation temperature, density, etc.) of the refrigerant based on the operation state quantity measured by the measurement unit 30a using a given formula or the like in advance. The calculation unit 30b performs a calculation process based on the operation state quantity measured by the measurement unit 30 a.

The driving unit 30c is an interface circuit for controlling the driving of the compressor 1, the four-way valve 2, the pressure reducing device 5, the outdoor blower 4, the indoor blower 8, and the like based on the operation result of the operation unit 30 b.

The storage unit 30d is a memory such as RAM (Random Access Memory) or ROM (Read Only Memory). The storage unit 30d stores the calculation result of the calculation unit 30b, predetermined constants, specification values of the equipment and its constituent elements, and a function expression and a function table (table) for calculating physical property values (saturation pressure, saturation temperature, density, etc.) of the refrigerant. These stored contents in the storage unit 30d can be referred to and rewritten as necessary. The storage unit 30d also stores a program executed by the arithmetic unit 30b, and the control unit 30 controls the air conditioner 100 in accordance with the program stored in the storage unit 30 d.

In the configuration example of the present embodiment, the control unit 30 is built in the air conditioner 100, but the present disclosure is not limited to this. The following structure is also possible: that is, the main control unit of the control unit 30 is provided in the heat source unit a, the sub-control unit having a part of the functions of the control unit 30 is provided in the usage unit B, and the data communication is performed between the main control unit and the sub-control unit, whereby the cooperation process is performed. The control unit 30 having all functions may be provided in the utilization unit B. Alternatively, the control unit 30 may be provided separately outside the heat source unit a and the usage unit B.

Operation of air conditioner 100

Next, the operation in each operation mode of the air conditioner 100 according to the present embodiment will be described. First, the operation of the cooling operation will be described with reference to fig. 1.

In the cooling operation, the four-way valve 2 is in the state shown by the broken line in fig. 1, that is, in the state in which the discharge side of the compressor 1 is connected to the gas side of the outdoor heat exchanger 3 and the suction side of the compressor 1 is connected to the gas side of the indoor heat exchanger 7.

The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 passes through the four-way valve 2 and reaches the outdoor heat exchanger 3 as a condenser. In the outdoor heat exchanger 3, the refrigerant is condensed and liquefied by the air blowing operation of the outdoor air blowing device 4, and becomes a high-pressure low-temperature refrigerant. The condensed and liquefied high-temperature low-pressure refrigerant is decompressed by the decompressing device 5. The two-phase refrigerant decompressed by the decompressing device 5 is sent to the indoor heat exchanger 7 of the usage unit B via the liquid connection pipe 6. The two-phase refrigerant after the pressure reduction is evaporated in the indoor heat exchanger 7 serving as an evaporator by the air blowing action of the indoor air blowing device 8, and becomes a low-pressure gas refrigerant. The low-pressure gas refrigerant is then sucked into the compressor 1 again via the four-way valve 2.

Here, the pressure reducing device 5 adjusts the opening degree so that the discharge refrigerant temperature of the compressor 1 becomes a predetermined value, and controls the flow rate of the refrigerant circulating through the indoor heat exchanger 7. Therefore, the discharge gas refrigerant discharged from the compressor 1 becomes a predetermined temperature state. The discharge refrigerant temperature of the compressor 1 is detected by the discharge temperature sensor 201 or the compressor housing temperature sensor 208 of the compressor 1. In this way, the refrigerant having a flow rate corresponding to the operation load required for the air-conditioning space provided with the usage unit B flows through the indoor heat exchanger 7.

Next, the operation of the heating operation will be described with reference to fig. 1.

In the heating operation, the four-way valve 2 is in the state shown by the solid line in fig. 1, that is, in the state in which the discharge side of the compressor 1 is connected to the gas side of the indoor heat exchanger 7 and the suction side of the compressor 1 is connected to the gas side of the outdoor heat exchanger 3.

The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 is sent to the usage unit B via the four-way valve 2 and the gas connection pipe 9, and reaches the indoor heat exchanger 7 serving as a condenser. The refrigerant is condensed and liquefied by the air blowing action of the indoor air blowing device 8, and becomes a high-pressure low-temperature refrigerant. The condensed and liquefied high-temperature low-pressure refrigerant is sent to the heat source unit a via the liquid connection pipe 6, decompressed by the decompressing device 5 to become a two-phase refrigerant, and sent to the outdoor heat exchanger 3. The two-phase refrigerant after the pressure reduction is evaporated in the outdoor heat exchanger 3 serving as an evaporator by the air blowing action of the outdoor air blowing device 4, and becomes a low-pressure gas refrigerant. Then, the low-pressure gas refrigerant is again sucked into the compressor 1 via the four-way valve 2.

Here, the pressure reducing device 5 adjusts the opening degree so that the discharge refrigerant temperature of the compressor 1 becomes a specific value, and controls the flow rate of the refrigerant circulating through the outdoor heat exchanger 3. Therefore, the discharge gas refrigerant discharged from the compressor 1 is brought into a specific temperature state. The discharge refrigerant temperature of the compressor 1 is detected by the discharge temperature sensor 201 or the compressor housing temperature sensor 208 of the compressor 1. In this way, the refrigerant having a flow rate corresponding to the operation load required for the air-conditioning space provided with the usage unit B flows through the indoor heat exchanger 7.

Control Structure of air conditioner 100

Fig. 3 is a functional block diagram showing an example of the functional configuration of the control unit 30 of the air conditioner 100 according to the present embodiment.

As shown in fig. 3, the control unit 30 includes a capacity control unit 41, a protection control unit 42, a rotation speed selection unit 43, an upper and lower limit restriction unit 44, a protection target value determination unit 45, and a storage unit 30d. The capacity control unit 41, the protection control unit 42, the rotation speed selection unit 43, and the upper and lower limit restriction unit 44 constitute a rotation speed determination unit. The operation state detection unit 50 includes a discharge temperature sensor 201, gas side temperature sensors 202 and 207, an outdoor temperature sensor 203, liquid side temperature sensors 204 and 205, an indoor temperature sensor 206, and a compressor housing temperature sensor 208. The refrigeration cycle 60 further includes a compressor 1, an outdoor heat exchanger 3, a pressure reducing device 5, and an indoor heat exchanger 7.

The calculation unit 30b in fig. 2 reads and executes the program stored in the storage unit 30d, and thereby the control unit 30 functions as the capacity control unit 41, the protection control unit 42, the rotation speed selection unit 43, the upper and lower limit restriction unit 44, the protection target value determination unit 45, and the storage unit 30 d.

The capability control unit 41 includes, for example, a PI (proportional integral: proportional Integral) controller 41a as a dynamic control device. The capacity control unit 41 calculates a rotational speed command, that is, a capacity rotational speed, of the compressor 1 required to bring the indoor temperature gradually closer to (or in agreement with) the set room temperature (room temperature difference Δt=0 defined by the difference between the indoor temperature and the set room temperature). That is, the capacity control unit 41 performs PI control with the chamber temperature difference Δt as an input. At this time, the capability control section 41 defines the indoor temperature detected by the indoor temperature sensor 206 as a current capability value indicating the current capability. The capacity control unit 41 defines a set room temperature, which is set from the outside by a user of the air conditioner 100 through a user interface such as a remote controller, as a capacity target value.

The protection control unit 42 calculates a protection rotational speed, which is a rotational speed command of the compressor 1 required to gradually bring or match a predetermined protection variable with a timely or predetermined protection target value, which is required to protect equipment constituting the air conditioner 100. Here, as the protection variables, for example, the discharge temperature Td of the compressor 1, the condensation temperature Tc, the evaporation temperature Te, the high-pressure Pd, the low-pressure Ps, and the like of the refrigerant are selected. As the protection target values, for example, an upper discharge temperature limit value, an upper condensation temperature limit value, a lower evaporation temperature limit value, an upper high pressure limit value, a lower low pressure limit value, and the like are selected. The protection control unit 42 includes PI controllers 42a and 42b for the respective protection variables, and calculates a protection rotational speed for each protection variable. For example, in the case of the control configuration example shown in fig. 3, the protection control unit 42 includes a PI controller 42a that receives as input a high pressure difference Δtc that is a difference between the condensation temperature Tc of the refrigerant and the upper limit value of the condensation temperature, and a PI controller 42b that receives as input a low pressure difference Δte that is a difference between the evaporation temperature Te of the refrigerant and the lower limit value of the evaporation temperature. Each of the PI controllers 42a, 42b outputs a guard rotational speed of the condensing temperature Tc and a guard rotational speed of the evaporating temperature Te, respectively.

The above-described protection variables are representative variables required for protecting the device, and variables other than the above-described variables may be used as the protection variables. The protection variables employed, however, have the following characteristics: the protection target value of the protection variable is an upper limit value of the protection variable with respect to an increase in the operation rotation speed of the compressor 1, and is a lower limit value of the protection variable with respect to a decrease in the rotation speed of the compressor 1.

Here, the capacity control unit 41 and the protection control unit 42 include PI controllers 41a, 42a, and 42b, but the present invention is not limited thereto. The capacity control unit 41 and the protection control unit 42 may be provided with a dynamic controller including at least an integrator, and may be provided with a PID (proportional integral derivative) controller or an I (integral) controller, for example.

The rotation speed selecting unit 43 has a minimum rotation speed selecting unit that selects, as the control rotation speed, the minimum rotation speed of the capacity rotation speed output from the capacity control unit 41 and the guard rotation speeds output from the guard control unit 42.

All the protection variables exemplified in the present embodiment have a feature that they change in a direction away from each constraint when the rotation speed of the compressor 1 increases. For example, when the rotation speed of the compressor 1 is increased, the high pressure Pd is also increased, and the high pressure Pd is changed in a direction exceeding the upper limit value of the high pressure. Therefore, by causing the rotational speed selection unit 43 to select the minimum rotational speed of the capacity rotational speed output from the capacity control unit 41 and the guard rotational speeds output from the guard control unit 42, all the guard variables can be controlled within the upper and lower limits.

The upper and lower limit limiter 44 stores a predetermined upper limit Fmax and lower limit Fmin of the operation rotation speed of the compressor 1. The upper and lower limit limiter 44 outputs the operating speed lower limit Fmin when the control speed selected by the speed selector 43 is equal to or lower than the operating speed lower limit Fmin, outputs the operating speed upper limit Fmax when the control speed is equal to or higher than the operating speed upper limit Fmax, and outputs the control speed as it is when the control speed is not equal to or higher than the operating speed upper limit Fmax. The compressor 1 is driven at the rotation speed output from the upper and lower limit restricting unit 44.

The protection target value determining unit 45 calculates and sets the protection target value in the protection control unit 42 based on the specification information of the constituent devices constituting the air conditioner 100 stored in the storage unit 30d in advance and the operation state of the air conditioner 100 detected by the operation state detecting unit 50. The specification information of the component equipment is mainly constraint conditions for protecting the component equipment, and is information such as a pressure range in which the component equipment unit can operate according to pressure resistance performance and a temperature range in which operation can be ensured according to heat resistance performance. The operation state detection unit 50 includes various sensors provided in the heat source unit a and the usage unit B, and a sensor for detecting the operation rotation speed of the compressor 1.

The storage and preservation form of the specification information of the element device is, for example, a form of a function table (table) or a function form using the operation condition as a parameter. The protection target value determination unit 45 calculates a corresponding protection target value based on the value of the operation state detected by the operation state detection unit 50. Table 1 is an example of specification information in a table format. The example of table 1 is used in the cooling operation, the operation state is the outside air temperature detected by the outside temperature sensor 203, and the protection target value is the condensation temperature upper limit value. In the example of table 1, the outside air temperature is divided into 5 temperature ranges of less than T1, T1 or more and less than T2, T2 or more and less than T3, T3 or more and less than T4, and T4 or more, and the respective temperature ranges are associated with the condensation temperature upper limit values Tu1, tu2, tu3, tu4, and Tu 5.

TABLE 1

Outdoor air temperature	Less than T1	T1 or more and less than T2	T2 or more and less than T3	T3 or more and less than T4	T4 or more
						Upper limit value of condensation temperature	Tu1	Tu2	Tu3	Tu4	Tu5

By setting the condensation temperature upper limit value for each temperature range of the outside air temperature in this manner, it is possible to protect the constituent devices constituting the heat source unit a, such as the electronic devices of the control unit 30, the fins and the heat pipes of the outdoor heat exchanger 3, and the like, which are affected by the outside air temperature and the condensation temperature, and to exhibit the capacity of the air conditioning apparatus 100 corresponding to the outside air temperature during the cooling operation.

In the example of table 1, the specification information is the upper limit value of the condensation temperature for each temperature range of the outside air temperature, but may be a combination other than the upper limit value. For example, the specification information may be an upper limit value of the condensation temperature for each temperature range of the indoor air temperature during the heating operation. In this way, during the heating operation, the component devices constituting the utilization unit B that are affected by the indoor air temperature and the condensation temperature can be protected, and the capacity of the air conditioner 100 corresponding to the indoor air temperature can be exerted. The specification information may be the lower limit value of the evaporation temperature for each temperature range of the outside air temperature, or the lower limit value of the evaporation temperature for each temperature range of the indoor air temperature. The outside air temperature is detected by the outside air temperature sensor 203, and the indoor air temperature is detected by the indoor air temperature sensor 206.

Control operation of air conditioner 100

The control operation performed by the control unit 30 of the air conditioner 100 according to the present embodiment will be described with reference to fig. 4. Fig. 4 is a flowchart showing a flow of control operation of the compressor 1 of the air conditioner 100 according to the present embodiment.

After the start of the flow, the control unit 30 first detects the operation condition (STEP 1). Here, for example, the set room temperature set from the outside through a user interface such as a remote controller is detected.

Next, the operation state detection unit 50 detects the operation state of the air conditioner 100 (STEP 2). As the detection means of the operation state, for example, a temperature sensor provided in the heat source unit a or the usage unit B of the air conditioner 100 and measuring the refrigerant temperature or the air temperature, and a sensor (not shown) detecting the operation rotation speed of the compressor 1 are used. The operation state is detected based on these sensor detection values.

Next, the capacity control unit 41 calculates the capacity rotational speed Fq based on the detected operation state quantity and outputs (STEP 3). Here, the capacity revolution speed Fq is outputted by a controller constituting the capacity control unit 41, and is calculated using the following equation (1) in a control configuration as shown in fig. 3, for example.

[ 1]

Fq_k＝Fq_k-1+K_p×(Δt_j-Δt_j-1)+K_I×Δt_j×T_int

···(1)

Here, Δt is a room temperature difference [ deg ] defined by a difference between the room temperature and the set room temperature. K _p、K_I is the control gain in the PI controller 41a, respectively. K _p is the proportional gain [ Hz/. Degree.C ], and K _I is the integral gain [ Hz/(. Degree.C. Sec) ]. T _int is the control period [ sec ]. The room temperature difference Δt is calculated from the room temperature detected by the room temperature sensor 206 in the operating state detected by the operating state detecting unit 50 and the set room temperature detected in STEP 1. The control gains Kp and Ki depend on the responsiveness of the operation of the actuator of the refrigeration cycle in the air conditioner 100, and the control period T _int also depends on the device specification, and therefore are stored in the storage unit 30d in advance as device specification information, and are used as calculation information when calculated by the calculation unit 30 b.

Next, the guard target value determination unit 45 sets a guard target value (STEP 4). The guard target value determining unit 45 determines and sets the guard target value of each of the PI controllers 42a and 42b constituting the guard control unit 42 based on the operation state.

Here, the correspondence relationship between the protection target value and the operation state is determined depending on the specifications of the component devices constituting the air conditioner 100, and is stored in the storage unit 30d in advance as the device specification information. The protection target value determination unit 45 uses the device specification information when determining the protection target value.

Next, the guard control unit 42 calculates and outputs the guard rotational speed Fp (STEP 5). Here, the guard rotational speed Fp is outputted from each PI controller 42a, 42b constituting the guard control unit 42, and is calculated by using the following equations (2) and (3), for example, in a control configuration as shown in fig. 3, the guard rotational speed FTc [ Hz ] of the condensation temperature and the guard rotational speed FTe [ Hz ] of the evaporation temperature, respectively.

[ 2]

FTc_k＝FTc_k-1+K_p×(ΔTc_j-ΔTc_j-1)+K_I×ΔTc_j×T_int

···(2)

[ 3] Of the following

FTe_k＝FTe_k-1+K_p×(ΔTe_j-ΔTe_j-1)+K_I×ΔTe_j×T_int

···(3)

Here, Δtc is a high pressure difference [ deg ] defined by a difference between the condensing temperature Tc and the condensing temperature upper limit value (a value obtained by subtracting the condensing temperature Tc from the condensing temperature upper limit value), and Δte is a low pressure difference [ deg ] defined by a difference between the evaporating temperature Te and the evaporating temperature lower limit value (a value obtained by subtracting the evaporating temperature lower limit value from the evaporating temperature Te). K _p、K_I is a control gain in PI control, K _p is a proportional gain [ Hz/. Degree.C ], and KI is an integral gain [ Hz/(. Degree.C.sec) ]. T _int is the control period [ sec ]. The control gain K _p、K_I depends on the responsiveness of the actuator operation of the refrigeration cycle in the air conditioning apparatus 100, and the control period T _int also depends on the equipment specification. Therefore, these values are stored in the storage unit 30d in advance as the device specification information, and are used as the calculation information when the protection control unit 42 performs the calculation.

As the condensation temperature Tc of the refrigerant, a detection value of the gas side temperature sensor 202 or the liquid side temperature sensor 204 provided in the outdoor heat exchanger 3 during the cooling operation, and a detection value of the gas side temperature sensor 207 or the liquid side temperature sensor 205 provided in the indoor heat exchanger 7 during the heating operation are used. As the evaporation temperature Te, a detection value of the gas side temperature sensor 207 or the liquid side temperature sensor 205 provided in the indoor heat exchanger 7 during the cooling operation, and a detection value of the gas side temperature sensor 202 or the liquid side temperature sensor 204 provided in the outdoor heat exchanger 3 during the heating operation are used.

Here, a temperature sensor is used to detect the condensing temperature and the evaporating temperature of the refrigerant. However, the condensing temperature Tc and the evaporating temperature Te may be obtained by directly providing pressure sensors on the suction side and the discharge side of the compressor 1, and performing saturation temperature conversion on the pressure values of the high pressure Pd detected by the pressure sensor on the discharge side and the low pressure Ps detected by the pressure sensor on the suction side. Conversely, the detected condensing temperature Tc and evaporating temperature Te may be converted into saturation temperatures to obtain the high-pressure Pd and the low-pressure Ps, respectively.

The upper limit value of the condensation temperature in the high differential pressure Δtc and the lower limit value of the evaporation temperature in the low differential pressure Δte are the protection target values calculated by the protection target value determining unit 45, and are calculated and set based on the operating conditions. For example, during the cooling operation, the upper limit value of the condensing temperature is stored as specification information in the storage unit 30d so as to be changed stepwise in accordance with the outside air temperature condition in advance. In this case, when the outside air temperature at the time of operation detected by the outside air temperature sensor 203 is high, the set value of the upper limit value of the condensation temperature is set to be high, and when the outside air temperature is low, the set value of the upper limit value of the condensation temperature is set to be low. In this way, the protection target value determining unit 45 changes the protection target value according to the operation state during operation.

For example, during the heating operation, the upper limit value of the condensing temperature is stored as specification information in the storage unit 30d so as to be changed stepwise in accordance with the indoor air temperature condition. In this case, when the indoor air temperature at the time of operation detected by the indoor temperature sensor 206 is high, the set value of the upper limit value of the condensing temperature is set to be high, and when the indoor air temperature is low, the set value of the upper limit value of the condensing temperature is set to be low. In this way, the protection target value determining unit 45 changes the protection target value according to the operation state during operation.

Next, the rotation speed selecting unit 43 selects the minimum rotation speed of the capacity rotation speed Fq output from the capacity control unit 41 and the guard rotation speed Fp output from the guard control unit 42. For this purpose, first, the rotational speed selecting unit 43 determines whether or not the guard rotational speed Fp < the capacity rotational speed Fq is satisfied (STEP 6). When the condition is satisfied (STEP 6: yes), the rotational speed selecting unit 43 selects the guard rotational speed Fp (STEP 7), and when the condition is not satisfied (STEP 6: no), the rotational speed selecting unit 43 selects the capacity rotational speed Fq (STEP 8). As shown in fig. 3, when there are a plurality of protection variables, in STEP7, the rotation speed selecting unit 43 selects the rotation speed having the smallest value among the protection rotation speeds Fp corresponding to the respective protection variables.

Next, the upper and lower limit limiter 44 performs processing so that the rotation speed selected by the rotation speed selector 43 does not deviate from the upper and lower limit values. First, the upper and lower limit limiter 44 determines whether or not the value of the operating rotation speed F selected from STEP6 to STEP 8 is smaller than the operating rotation speed upper limit Fmax (STEP 9). If the condition is not satisfied (STEP 9: no), the upper and lower limit limiter 44 updates the selected operation rotation speed F to the operation rotation speed upper limit Fmax (STEP 10) and outputs the updated operation rotation speed as the control rotation speed F (STEP 13).

The upper and lower limit limiter 44 determines whether or not the value of the operating rotation speed F selected in STEP6 to STEP 8 is greater than the operating rotation speed lower limit Fmin (STEP 11). If the condition is not satisfied (STEP 11: no), the upper and lower limit limiter 44 updates the selected operation rotation speed F to the operation rotation speed lower limit Fmin (STEP 12), outputs the operation rotation speed as the control rotation speed F (STEP 13), and thereafter ends the control flow.

In the present embodiment, the case where the protection target value is changed according to the operation state has been described, but the parameter for changing the protection target value is not limited to the operation condition, and the protection target value may be changed according to the installation condition of the air conditioner 100, for example. For example, the protection target value may be changed according to the installation conditions of the refrigeration cycle such as the material, shape, and length of the refrigerant piping (the liquid connection piping 6 and the gas connection piping 9 shown in fig. 1) connecting the heat source unit a and the usage unit B. In this case, since the maximum use pressure varies depending on the material and shape of the refrigerant piping, for example, the upper limit value of the condensation temperature is stored as specification information so as to be changed depending on the material of the refrigerant piping, and when the material of the refrigerant piping connecting the heat source unit a and the usage unit B is a material with a high maximum use pressure, the set value of the upper limit value of the condensation temperature is raised, and when the material with a low maximum use pressure is lowered, the set value of the upper limit value of the condensation temperature is lowered.

In this case, for example, the storage unit 30d stores a plurality of correspondence tables of the outside air temperature and the condensation temperature upper limit value, as shown in table 1, which correspond to the material or shape of the refrigerant piping. When the constructor of the air conditioner 100 sets the materials, shapes, or lengths of the liquid connection pipe 6 and the gas connection pipe 9 in the control unit 30, the protection target value determining unit 45 determines the protection target value using a correspondence table corresponding to the set materials, shapes, or lengths, from among the plurality of correspondence tables stored in the storage unit 30 d.

In the present embodiment, the case where the protection target value is changed according to the outside air temperature condition has been described, but the operation state of the parameter that changes the protection target value is not limited to this, and the protection target value may be changed in time based on other operation states such as the operation pressure (high-pressure refrigerant pressure, low-pressure refrigerant pressure) of the refrigerant circuit in the air conditioner 100, for example. Specific control operation examples will be described in the following embodiments.

< Embodiment 2 >

A configuration of an air conditioner 200 according to embodiment 2 of the present disclosure will be described. Note that the air conditioner 200 according to the present embodiment is described around the differences between embodiment 2 and embodiment 1, and the description of the same parts is omitted. The refrigerant circuit of the air conditioner 200 and the control unit 30 have the same configuration and operation as those of embodiment 1. However, the method for determining the protection target value by the protection target value determining unit 45 is different from the specification information stored in the storage unit 30 d.

Control operation of air conditioner 200

The control operation of the air conditioner 200 according to the present embodiment will be described with reference to fig. 4 and 5. Fig. 5 is a diagram showing the operation pressure ranges of the air conditioner 200 according to the present embodiment (hereinafter referred to as an operation diagram). The vertical axis of fig. 5 represents the high pressure Pd of the refrigerant, and the horizontal axis represents the low pressure Ps of the refrigerant. The range surrounded by the solid line connecting points a to F in fig. 5 means: if the combination of the high pressure Pd and the low pressure Ps of the refrigerant falls within this range, the normal operation of the air conditioner 200 can be ensured as a range of the equipment. In the present embodiment, the operation rotation speed of the compressor 1 is controlled so that the pressure zone within the range surrounded by the solid line operates.

In the present embodiment, data (for example, values of points a to F) on the operation chart shown in fig. 5 are stored in the storage unit 30d as specification information. The pressure value on the operation map is used for control after saturation temperature conversion. For conversion from pressure to saturation temperature, for example, a functional equation is prepared in advance, in which the pressure based on the physical properties of the refrigerant is used as a variable, and temperature conversion is performed using the functional equation.

After the flow starts, first, each unit of the air conditioner 200 performs STEP1 to STEP3 as in embodiment 1. Next, the protection target value determining unit 45 detects the position on the operation map of fig. 5, which is read from the storage unit 30d, at which position on the operation map the operation pressure is to be performed, based on the values of the condensation temperature Tc and the evaporation temperature Te detected in STEP2 as the operation state of the air conditioner 200. The protection target value determining unit 45 calculates and sets the condensation temperature upper limit value and the evaporation temperature lower limit value, which are the protection target values of the protection control unit 42, based on the position of the detected operating pressure (STEP 4). For example, when the operating pressure is at the position of point X shown in fig. 5 based on the detected values of the condensation temperature Tc and the evaporation temperature Te, the protection target value determining unit 45 sets the saturation temperature equivalent value of the pressure value Pd1 at the upper limit value of the high pressure on the operation map, that is, the intersection point intersecting the horizontal line formed by the connection point C and the point D, as the condensation temperature upper limit value, and sets the saturation temperature equivalent value of the pressure value Ps1 at the lower limit value of the low pressure on the operation map, that is, the intersection point intersecting the straight line formed by the connection point B and the point C, as the evaporation temperature lower limit value.

Thereafter, using the condensation temperature upper limit value and the evaporation temperature lower limit value set in STEP4, the guard control unit 42 calculates and outputs the guard rotation speed Fp (STEP 5). Hereinafter, STEP6 to STEP13 are similar to those of embodiment 1.

In the present embodiment, the operation map stored in the storage unit 30d is an operation pressure range of high pressure and low pressure, but may be an operation temperature range of condensation temperature Tc and evaporation temperature Te.

The storage unit 30d may store a plurality of operation maps corresponding to respective ranges of the operation rotational speeds of the compressor 1. The protection target value determining unit 45 determines protection target values such as a condensation temperature upper limit value and an evaporation temperature lower limit value using an operation map corresponding to a range to which the operation rotational speed of the compressor 1 belongs.

The air conditioning apparatuses 100 and 200 according to the above embodiments include: a refrigeration cycle including a compressor 1 for compressing a refrigerant; an operation state detection unit 50 that detects an operation state of the refrigeration cycle; a protection target value determination unit 45 that determines a protection target value of a protection variable relating to the refrigeration cycle based on the operation state; and a rotation speed determination unit that determines the operation rotation speed of the compressor 1 based on at least the capacity target value of the temperature adjusted by the refrigeration cycle and the protection target value.

Accordingly, since the protection target value for satisfying the constraint condition of the component equipment can be changed according to the operation state, unnecessary limitation of the performance of the air conditioner 100 or 200 can be suppressed, and the performance of the air conditioner 100 or 200 can be improved.

The air conditioning apparatuses 100 and 200 according to the above embodiments can prevent excessive protection operation of the limit value of the component equipment by appropriately setting the protection target value and performing the operation control according to not only the constraint condition based on the specification of the component equipment but also the installation condition and the operation state of the air conditioning apparatuses 100 and 200. As a result, the air conditioning apparatuses 100 and 200 can expand the operating range in which normal operation is possible, as compared with the conventional apparatuses.

The air conditioning apparatuses 100 and 200 according to the above embodiments perform highly accurate operation control of the protection target value according to not only the constraint conditions based on the specifications of the component devices but also the installation condition and the operation state of the air conditioning apparatuses 100 and 200. This can further improve the reliability of the air conditioning apparatuses 100 and 200.

The features of the present disclosure have been described in the embodiments, but, for example, the flow path structure (piping connection) of the refrigerant, the structure of the refrigerant circuit elements such as the compressor, the heat exchanger, the expansion valve, and the like are not limited to those described in the embodiments, but can be appropriately modified within the technical scope of the present disclosure.

The functional blocks of the control unit 30 in fig. 3 may be individually chipped, or may be partly or entirely integrated and chipped. The method of forming the integrated circuit is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. Or may be any of hybrid and monolithic. The structure may be as follows: some of which are implemented in hardware and some of which are implemented in software.

In addition, when a technology such as integration of an integrated circuit that replaces LSI has been developed due to progress in semiconductor technology, an integrated circuit based on the technology can also be used.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the embodiments, and design changes and the like without departing from the scope of the present invention are also included.

Description of the reference numerals

1 … Compressors; 2 … four-way valve; 3 … outdoor heat exchangers; 4 … outdoor air supply devices; 5 … pressure relief devices; 6 … liquid connecting piping; 7 … indoor heat exchangers; 8 … indoor air supply devices; 9 … gas connection piping; 30 … control units; 30a … measuring unit; 30b … operation unit; 30c … driving part; 30d … storage part; 41 … capability control section; 41a … PI controller; 42 … protection control section; 42a … PI controller; 42b … PI controller; 43 … rotation speed selection unit; 44 … upper and lower limit restrictions; 45 … guard target value determining unit; 50 … an operation state detection unit; 60 … refrigeration cycle; 201 … exhaust temperature sensor; 202 … gas side temperature sensor; 203 … outdoor temperature sensor; 204 … liquid side temperature sensor; 205 … liquid side temperature sensor; 206 … indoor temperature sensor; 207 … gas side temperature sensor; 208 … compressor housing temperature sensor; a … heat source unit; b … utilize units.

Claims

1. A refrigeration cycle apparatus, wherein,

The device is provided with:

a refrigeration cycle including a compressor for compressing a refrigerant;

an operation state detection unit that detects an operation state of the refrigeration cycle;

a protection target value determination unit that determines a protection target value of a protection variable relating to the refrigeration cycle based on the operation state; and

And a rotation speed determining unit that determines an operation rotation speed of the compressor based on at least a capacity target value of the temperature adjusted by the refrigeration cycle and the protection target value.

2. The refrigeration cycle apparatus according to claim 1, wherein,

The rotation speed determination unit includes an I (integral) controller, a PI (proportional integral) controller, or a PID (proportional integral derivative) controller that controls the guard variable to gradually approach the guard target value.

3. The refrigeration cycle apparatus according to claim 1, wherein,

The protection variable includes any one of a discharge temperature of the refrigerant discharged from the compressor, a condensation temperature of the refrigerant, an evaporation temperature of the refrigerant, a high pressure of the refrigerant, and a low pressure of the refrigerant.

4. A refrigeration cycle apparatus according to any one of claim 1 to 3, wherein,

The operation state is an outside air temperature or an indoor air temperature.

5. The refrigeration cycle apparatus according to claim 4, wherein,

Comprises a storage unit for storing a correspondence between the outside air temperature or the indoor air temperature and the protection target value,

The protection target value determining unit refers to the correspondence stored in the storage unit to determine the protection target value.

6. A refrigeration cycle apparatus according to any one of claim 1 to 3, wherein,

The operation state is a condensation temperature or a high-pressure of the refrigerant, and an evaporation temperature or a low-pressure of the refrigerant.

7. The refrigeration cycle apparatus according to claim 6, wherein,

A storage unit for storing an operation map indicating an operation pressure range or an operation temperature range of the refrigerant,

The protection target value determination unit refers to the operation map stored in the storage unit to determine the protection target value corresponding to the operation state.

8. A control method of a refrigeration cycle device provided with a compressor for compressing a refrigerant, wherein,

The control method comprises the following steps:

detecting an operation state of the refrigeration cycle apparatus;

Determining a protection target value of a protection variable related to the refrigeration cycle device based on the operation state; and

And determining an operation rotation speed of the compressor based on at least a capacity target value of the temperature adjusted by the refrigeration cycle device and the protection target value.