Patent Application
20240263855
The present invention relates to a refrigeration cycle device, a control method, and a non-transitory computer-readable storage medium.
Conventionally, there is a control device for a refrigeration cycle device, which calculates an upper limit speed of a speed command of an inverter motor from a graph based on a limit value of a high pressure of a refrigerant and a detected pressure on a high pressure side (see, for example, Patent Document 1). Thereby, it is possible to obtain a speed command of the inverter motor that matches a load while suppressing the high pressure of the refrigerant to an allowable value.
However, the fixed limit value of the high pressure of the refrigerant must be set to such a value as to enable protection of the refrigeration cycle device under any circumstances. For this reason, there is a problem that, depending on a circumstance, the speed of the inverter motor may be unnecessarily restricted, that is, performance of the refrigeration cycle device may be unnecessarily restricted.
The present disclosure has been made in view of such circumstances, and provides a refrigeration cycle device, a control method, and a non-transitory computer-readable storage medium that can prevent the performance from being unnecessarily restricted.
The present disclosure is made in order to solve the above problem, a refrigeration cycle device according to an aspect of the present disclosure includes: a refrigeration cycle circuit including a compressor configured to compress a refrigerant; an operating state detector configured to detect an operating state of the refrigeration cycle circuit; a protection target value determinator configured to determine, based on the operating state, a protection target value of a protection variable regarding the refrigeration cycle circuit; and a rotation speed determinator configured to determine an operating rotation speed of the compressor, based at least on the protection target value and a capability target value of a temperature adjusted by the refrigeration cycle circuit.
Further, according to another aspect of the present disclosure, in the above-described refrigeration cycle device, the rotation speed determinator includes an I (integral) controller, a PI (proportional-integral) controller, or a PID (proportional-integral-derivative) controller configured to control the protection variable to be asymptotic to the protection target value.
Further, according to another aspect of the present disclosure, in the above-described refrigeration cycle device, 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.
Further, according to another aspect of the present disclosure, in the above-described refrigeration cycle device, the operating state is an outside temperature or an indoor temperature.
Further, according to another aspect of the present disclosure, the above-described refrigeration cycle device further includes a storage configured to store a correspondence between the outside temperature or the indoor temperature and the protection target value. The protection target value determinator is configured to determine the protection target value by referring to the correspondence stored in the storage.
Further, according to another aspect of the present disclosure, in the above-described refrigeration cycle device, the operating state is a condensation temperature or a high pressure of the refrigerant, and an evaporation temperature or a low pressure of the refrigerant.
Further, according to another aspect of the present disclosure, the above-described refrigeration cycle device further includes a storage configured to store an operation map indicating an operating pressure range or an operating temperature range of the refrigerant. The protection target value determinator is configured to determine the protection target value corresponding to the operating state by referring to the operation map stored in the storage.
Further, a control method according to another aspect of the present disclosure is for a refrigeration cycle device including a compressor configured to compress a refrigerant. The control method includes: a step of detecting an operating state of the refrigeration cycle device; a step of determining, based on the operating state, a protection target value of a protection variable regarding the refrigeration cycle device; and a step of determining an operating rotation speed of the compressor, based at least on the protection target value and a capability target value of a temperature adjusted by the refrigeration cycle device.
According to the present disclosure, it is possible to prevent the performance of the refrigeration cycle device from being unnecessarily restricted.
Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. Note that in the first embodiment, an air conditioner 100 is taken as a refrigeration cycle device, but other devices such as a heat pump type water heater may be used as long as they use a refrigeration cycle.
Examples of refrigerants used in the air conditioner 100 include HFC refrigerants such as R410A, R407C, R404A, and R32, HFO refrigerants such as R1234yf/ze, HCFC refrigerants such as R22 and R134a, or natural refrigerants such as carbon dioxide (CO2), hydrocarbons, helium, propane, and the like.
The usage unit B is installed by an installation method such as being embedded in an indoor ceiling or hanging from the ceiling, or by an installation method such as being hung on an indoor wall. The usage unit B is also called an indoor unit. As described above, the usage unit B is connected to the heat source unit A via the liquid connection pipe 6 and the gas connection pipe 9, and constitutes a part of the refrigerant circuit.
Next, a detailed configuration of the usage unit B will be described. The usage unit B constitutes an indoor refrigerant circuit that is a part of the refrigerant circuit, and includes an indoor air blower 8 and an indoor heat exchanger 7 that is a usage side heat exchanger.
The indoor heat exchanger 7 is a cross-fin type fin-and-tube heat exchanger that is composed of heat exchanger tubes and a large number of fins. The indoor heat exchanger 7 functions as a refrigerant evaporator to cool indoor air during cooling operation, and functions as a refrigerant condenser to heat indoor air during heating operation.
The indoor air blower 8 is a fan capable of controlling a flow rate of air supplied to the indoor heat exchanger 7, and is composed of, for example, a centrifugal fan or a multi-blade fan driven by a DC motor (not shown). The indoor air blower 8 has a function of sucking indoor air into the usage unit B, and supplying the air heat exchanged with the refrigerant by the indoor heat exchanger 7 into the room as supply air.
Additionally, various sensors are installed in the usage unit B. That is, a liquid side of the indoor heat exchanger 7 is provided with a liquid side temperature sensor 205 that detects a temperature of the refrigerant in a liquid state or a gas-liquid two-phase state (the refrigerant temperature corresponding to a supercooled liquid temperature Tco during heating operation or an evaporation temperature Te during cooling operation). Further, the indoor heat exchanger 7 is provided with a gas side temperature sensor 207 that detects a temperature of the refrigerant in the gas-liquid two-phase state (the refrigerant temperature corresponding to a condensation temperature Tc during heating operation or the evaporation temperature Te during cooling operation). Further, an indoor air intake side of the usage unit B is provided with an indoor temperature sensor 206 that detects a temperature of the indoor air flowing into the unit (indoor air temperature). It should be noted here that the liquid side temperature sensor 205, the gas side temperature sensor 207, and the indoor temperature sensor 206 are all composed of thermistors. Further, the liquid side temperature sensor 205 and the gas side temperature sensor 207 may measure a surface temperature of a heat transfer tube or the like and use it as the temperature of the refrigerant, or may directly measure a temperature of the refrigerant. Operation of the indoor air blower 8 is controlled by a controller 30.
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, a detailed configuration 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 air blower 4, and a decompressor 5. The decompressor 5 is disposed on the liquid side of the heat source unit A in order to perform an adjustment of the flow rate of the refrigerant flowing in the refrigerant circuit, and the like.
The compressor 1 is a compressor whose operating capacity (frequency, operating rotation speed) can be controlled. Here, as the compressor 1, a positive displacement compressor driven by a motor (not shown) controlled by an inverter is used. Note that although there is only one compressor 1 here, the compressor 1 is not limited to this, and two or more compressors 1 may be connected in parallel depending on the number of connected units B, or the like.
The four-way valve 2 is a valve that has a function of switching a direction of a refrigerant flow. During cooling operation, the four-way valve 2 switches the refrigerant flow so as to connect a discharge side of the compressor 1 and a gas side of the outdoor heat exchanger 3, and also connect a suction side of the compressor 1 and the gas connection pipe 9 side (dotted line of the four-way valve 2 in
The outdoor heat exchanger 3 includes a cross-fin type fin-and-tube type heat exchanger, which is composed of a large number of fins and a heat transfer tube whose gas side is connected to the four-way valve 2 and whose liquid side is connected to the liquid connection pipe 6. The outdoor heat exchanger 3 functions as a condenser for the refrigerant during cooling operation, and functions as an evaporator for the refrigerant during heating operation.
The outdoor air blower 4 is a fan that can change the flow rate of air supplied to the outdoor heat exchanger 3, and is composed of, for example, a propeller fan driven by a DC motor (not shown). The outdoor air blower 4 has a function of sucking outdoor air into the heat source unit A using the fan and discharging to the outside the air heat exchanged with the refrigerant by the outdoor heat exchanger 3.
Further, various sensors are installed 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 shell temperature sensor 208 that detects a shell temperature of the compressor 1. The outdoor heat exchanger 3 is provided with a gas side temperature sensor 202 that detects a temperature of the refrigerant in the 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, the liquid side of the outdoor heat exchanger 3 is provided with a liquid side temperature sensor 204 that detects a temperature of the refrigerant in the liquid state or the gas-liquid two-phase state. Further, an outdoor air intake side of the heat source unit A is provided with an outdoor temperature sensor 203 that detects a temperature of the outdoor air flowing into the unit, that is, an outside temperature. It should be noted here that 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 shell temperature sensor 208 are all composed of thermistors. Further, 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 shell temperature sensor 208 may measure a surface temperature of the heat transfer tube or the like, and use it as a temperature of the refrigerant, or may directly measure a temperature of the refrigerant. Note that the operations of the compressor 1, the four-way valve 2, the outdoor air blower 4, and the decompressor 5 are controlled by the controller 30.
The heat source unit A and the usage unit B as described above are connected via the liquid connection pipe 6 and the gas connection pipe 9 to constitute the refrigerant circuit of the air conditioner 100. The liquid connection pipe 6 and the gas connection pipe 9 have different lengths depending on an installation environment of the air conditioner 100, and may be short in pipe length (for example, within 10 m in total length) or long (for example, over 100 m in total length).
Further, the liquid connection pipe 6 and the gas connection pipe 9 that connect the heat source unit A and the usage unit B are made of copper pipes that are generally used as refrigerant pipes. Examples of materials of copper pipes for refrigerant piping include O material, OL material, H material, and 1/2H material. For example, in a case of a copper pipe with a pipe outer diameter of ϕ19.05 and a wall thickness of 1.00 mm, the maximum working pressure is about 3.6 MPa for O material and about 6.7 MPa for H material. The maximum working pressure differs depending on a material even with the same dimension.
Normally, a material of the liquid connection pipe 6 and the gas connection pipe 9 is selected based on the refrigerant used and the working pressure. However, when updating a conventionally installed old air conditioner, for example, if it is installed in a building of a large facility, the liquid connection pipe 6 and the gas connection pipe 9 that connect the heat source unit A and the usage unit B are necessarily long. For this reason, the construction cost for updating the liquid connection pipe 6 and the gas connection pipe 9 increases, so that the existing liquid connection pipe 6 and gas connection pipe 9 are used as they are in some cases. Therefore, even in the same air conditioner 100, the materials of the liquid connection pipe 6 and the gas connection pipe 9 may differ depending on an installation environment.
Note that in the present embodiment, a configuration in which there is one heat source unit A will be described as an example, but the present disclosure is not limited to this, and there may be two or more heat source units A. Further, in a case of a plurality of heat source units A and a plurality of usage units B, the respective capacities may differ from large to small, or may all be the same capacity.
The controller 30 is built into the air conditioner 100 and includes a measurer 30a, a calculator 30b, a driver 30c, and a storage 30d.
The measurer 30a is an interface circuit with various sensors including 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 shell temperature sensor 208, and the like. The measurer 30a measures, using various sensors and the like, operating state quantities indicating an operating state, such as a refrigerant pressure Pr, a refrigerant temperature Tr, an air temperature Ta, and an operating rotation speed (frequency) Rc of the compressor 1. The operating state quantities measured by the measurer 30a are input to the calculator 30b. Note that the refrigerant pressure Pr includes a high pressure Pd and a low pressure Ps; the refrigerant temperature Tr includes the condensation temperature Tc and the evaporation temperature Te; and the air temperature Ta includes an outside temperature and an indoor temperature.
The calculator 30b is a processor such as a CPU (Central Processing Unit). The calculator 30b reads and executes a program stored in the storage 30d. By executing the program, the calculator 30b calculates, for example, refrigerant physical property values (saturation pressure, saturation temperature, density, etc.) based on the operating state quantities measured by the measurer 30a, using predetermined formulas or the like. Further, the calculator 30b performs calculation processing based on the operating state quantities measured by the measurer 30a.
The driver 30c is an interface circuit for controlling the drive of the compressor 1, the four-way valve 2, the decompressor 5, the outdoor air blower 4, the indoor air blower 8, and the like, based on results of the calculation by the calculator 30b.
The storage 30d is a memory such as RAM (Random Access Memory) or ROM (Read Only Memory). Further, the storage 30d stores the results of the calculation by the calculator 30b, predetermined constants, specification values of devices and their components, function formulas and function tables for calculating physical property values of the refrigerant (saturation pressure, saturation temperature, density, etc.), and the like. These contents stored in the storage 30d can be referenced and rewritten as necessary. The storage 30d further stores a program executed by the calculator 30b, and the controller 30 controls the air conditioner 100 according to the program in the storage 30d.
Note that in the configuration example of the present embodiment, the controller 30 is built into the air conditioner 100, but the present disclosure is not limited to this. A configuration may be such that a main controller of the controller 30 is provided in the heat source unit A, a sub-controller having a part of the functions of the controller 30 is provided in the usage unit B, and data communication is performed between the main controller and the sub-controller to perform cooperative processing. Another configuration may be such that the controller 30 having all the functions is installed in the usage unit B. Alternatively, a configuration may be such that the controller 30 is separately disposed outside the heat source unit A and the usage unit B.
Next, operation of the air conditioner 100 of the present embodiment in each operation mode will be described. First, operation of the cooling operation will be described using
During cooling operation, the four-way valve 2 is in the state shown by the broken line in
A high-temperature high-pressure gas refrigerant discharged from the compressor 1 passes through the four-way valve 2 and reaches the outdoor heat exchanger 3 which is a condenser. In the outdoor heat exchanger 3, the refrigerant is condensed and liquefied by the air blowing action of the outdoor air blower 4, and becomes a high-pressure low-temperature refrigerant. The high-temperature low-pressure refrigerant that has been condensed and liquefied is decompressed by the decompressor 5. The two-phase refrigerant decompressed by the decompressor 5 is sent to the indoor heat exchanger 7 of the usage unit B via the liquid connection pipe 6. The decompressed two-phase refrigerant is evaporated in the indoor heat exchanger 7 which is an evaporator, by the air blowing action of the indoor air blower 8 to become a low-pressure gas refrigerant. Then, the low-pressure gas refrigerant is sucked into the compressor 1 again via the four-way valve 2.
Here, the decompressor 5 adjusts an opening degree so that the temperature of the refrigerant discharged from the compressor 1 becomes a predetermined value, thereby controlling the flow rate of the refrigerant circulating through the indoor heat exchanger 7. Therefore, the discharged gas refrigerant discharged from the compressor 1 is in a predetermined temperature state. The discharge refrigerant temperature of the compressor 1 is detected by the discharge temperature sensor 201 or the compressor shell temperature sensor 208 of the compressor 1. In this way, the refrigerant flows through the indoor heat exchanger 7 at a flow rate that corresponds to an operating load required in the air-conditioned space in which the usage unit B is installed.
Next, operation of the heating operation will be described using
During heating operation, the four-way valve 2 is in the state shown by the solid line in
A high-temperature 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 then reaches the indoor heat exchanger 7 which is a condenser. The refrigerant is condensed and liquefied by the air blowing action of the indoor air blower 8 to become 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, is decompressed by the decompressor 5 to become a two-phase refrigerant, and is sent to the outdoor heat exchanger 3. The decompressed two-phase refrigerant is evaporated in the outdoor heat exchanger 3 which is an evaporator, by the air blowing action of the outdoor air blower 4 to become a low-pressure gas refrigerant. Then, the low-pressure gas refrigerant is sucked into the compressor 1 again via the four-way valve 2.
Here, the decompressor 5 adjusts the opening degree so that the temperature of the refrigerant discharged from the compressor 1 becomes a specific value, thereby controlling the flow rate of the refrigerant circulating through the outdoor heat exchanger 3. Therefore, the discharged gas refrigerant discharged from the compressor 1 is in a specific temperature state. The discharge refrigerant temperature of the compressor 1 is detected by the discharge temperature sensor 201 or the compressor shell temperature sensor 208 of the compressor 1. In this way, the refrigerant flows through the indoor heat exchanger 7 at a flow rate that corresponds to the operating load required in the air-conditioned space in which the usage unit B is installed.
As shown in
Note that when the calculator 30b in
The capability controller 41 includes, for example, a PI (Proportional-Integral) controller 41a, which is a dynamic control device. The capability controller 41 calculates a capability rotation speed, which is a rotation speed command of the compressor 1 necessary to make an indoor temperature asymptotic (room temperature difference defined as a difference between the indoor temperature and the set room temperature Δt≤0) or identical (room temperature difference Δt=0) to a set room temperature. That is, the capability controller 41 performs PI control using the room temperature difference Δt as an input. At this time, the capability controller 41 defines the indoor temperature detected by the indoor temperature sensor 206 as a current capability value representing the current capability. Further, the capability controller 41 defines as a capability target value, the set room temperature that is externally set by a user of the air conditioner 100 using a user interface such as a remote control.
The protection controller 42 calculates a protection rotation speed, which is a rotation speed command of the compressor 1 necessary to make a predetermined protection variable asymptotic or identical to a protection target value timely determined or predetermined, where the predetermined protection variable is necessary to protect the devices constituting the air conditioner 100. Here, examples of the protection variables include the discharge temperature Td of the compressor 1, the condensation temperature Tc, the evaporation temperature Te, the high pressure Pd, and the low pressure Ps of the refrigerant, and the like. Further, examples of the protection target values include a discharge temperature upper limit value, a condensation temperature upper limit value, an evaporation temperature lower limit value, a high pressure upper limit value, a low pressure lower limit value, and the like. The protection controller 42 has PI controllers 42a and 42b for the respective protection variables, and calculates a protection rotation speed for each protection variable. For example, in a case of the control configuration example shown in
Note that the above-described protection variables are examples of typical variables necessary to protect the devices, and variables other than those described above may be adopted as the protection variables. However, protection variables to be adopted have characteristics that a protection target value for a protection variable which increases when the operating speed of the compressor 1 is increased is the upper limit value of that protection variable, and that a protection target value for a protection variable which decreases when the operating speed of the compressor 1 is increased is the lower limit value of that protection variable.
Further, although the capability controller 41 and the protection controller 42 include the PI controllers 41a, 42a, and 42b here, the present embodiment is not limited to this. The capability controller 41 and the protection controller 42 only need to be equipped with a dynamic controller including at least an integrator, for example, they may be equipped with a PID (proportional-integral-derivative) controller or an I (integral) controller.
The rotation speed selector 43 has a minimum rotation speed selector, and selects, as a control rotation speed, the lowest rotation speed from among a capability rotation speed output from the capability controller 41 and each protection rotation speed output from the protection controller 42.
All the protection variables exemplified in the present embodiment have a characteristic that they change in a direction that deviates from each constraint as the rotation speed of the compressor 1 increases. For example, regarding the high pressure Pd, when the rotation speed of the compressor 1 is increased, the high pressure Pd also increases and changes in a direction exceeding the high pressure upper limit value. Therefore, by the rotation speed selector 43 selecting the smallest rotation speed from among the capability rotation speed output from the capability controller 41 and each protection rotation speed output from the protection controller 42, all the protection variables can be controlled within their upper and lower limits.
The upper and lower limit limiter 44 stores a predetermined operating rotation speed upper limit value Fmax and an operating rotation speed lower limit value Fmin of the compressor 1. The upper and lower limit limiter 44 outputs the operating rotation speed lower limit value Fmin when the control rotation speed selected by the rotation speed selector 43 is equal to or lower than the operating rotation speed lower limit value Fmin; outputs the operating rotation speed upper limit value Fmax when the control rotation speed is equal to or higher than the operating rotation speed upper limit value Fmax; and at other times, outputs the control rotation speed as it is. The compressor 1 is driven according to the rotation speed output from the upper and lower limit limiter 44.
The protection target value determinator 45 calculates and sets a protection target value for the protection controller 42 based on specification information of the constituent devices constituting the air conditioner 100, which is previously stored in the storage 30d, and an operating state of the air conditioner 100 detected by the operating state detector 50. Here, the specification information of the constituent devices is mainly constraint conditions for protecting the constituent devices, for example, information such as a pressure range in which the operation is guaranteed from the pressure resistance performance of each constituent device, and a temperature range in which the operation is guaranteed from the heat resistance performance of each constituent device. Further, the operating state detector 50 includes various sensors installed in the heat source unit A and the usage unit B, and a sensor that detects an operating rotation speed of the compressor 1.
An example of a storing format of the specification information of the constituent devices includes a function formula or a function table (table) with operating conditions as parameters. The protection target value determinator 45 calculates a corresponding protection target value based on the value of the operating state detected by the operating state detector 50. Table 1 is an example of the specification information in table format. The example of Table 1 is used during cooling operation, the operating state is the outside temperature detected by the outdoor temperature sensor 203, and the protection target value is the condensation temperature upper limit value. In the example of Table 1, the outside temperature is grouped into five temperature ranges: 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. Further, the condensation temperature upper limit values Tu1, Tu2, Tu3, Tu4, and Tu5 are associated with the respective temperature ranges.
By setting the condensation temperature upper limit value for each temperature range of the outside temperature in this way, it is possible for the air conditioner 100 to exercise its capabilities in accordance with the outside temperature, while protecting the constituent devices constituting the heat source unit A, which are affected by the outside temperature and the condensation temperature during cooling operation, for example, electronic devices of the controller 30, the fins and the heat transfer tubes of the outdoor heat exchanger 3, and the like.
Note that in the example of Table 1, the specification information is the condensation temperature upper limit value for each temperature range of the outside temperature, but other combinations may be used. For example, the specification information may be the condensation temperature upper limit value for each temperature range of the indoor air temperature during heating operation. Thereby, during heating operation, it is possible for the air conditioner 100 to exercise its capabilities in accordance with the indoor temperature while protecting the constituent devices constituting the usage unit B, which are affected by the indoor temperature and the condensation temperature. Further, the specification information may be an evaporation temperature lower limit value for each temperature range of the outside temperature, or may be an evaporation temperature lower limit value for each temperature range of the indoor air temperature. Note that the outside temperature is detected by the outdoor temperature sensor 203, and the indoor temperature is detected by the indoor temperature sensor 206.
Control operations by the controller 30 of the air conditioner 100 of the present embodiment will be described based on
After starting the flow, the controller 30 first detects an operating condition (STEP 1). Here, a set room temperature that is set from the outside using a user interface such as a remote control is detected.
Next, the operating state detector 50 detects an operating state of the air conditioner 100 (STEP 2). Examples of means for detecting an operating state include the use of a temperature sensor that is installed in the heat source unit A or the usage unit B of the air conditioner 100 and measures a refrigerant temperature or an air temperature, and a sensor (not shown) that detects an operating rotation speed of the compressor 1. The operating state is detected based on these sensor detection values.
Subsequently, the capability controller 41 calculates and outputs a capability rotation speed Fq based on the detected operating state quantities (STEP 3). Here, the capability rotation speed Fq is output by a controller constituting the capability controller 41, and is calculated using the following formula (1), for example, in the control configuration shown in
Here, Δt is a room temperature difference [deg] defined by the difference between the indoor temperature and the set room temperature. Each of Kp and KI is a control gain in the PI controller 41a. Kp is a proportional gain [Hz/° C.], and KI is an integral gain [Hz/(° C.·sec)]. Tint is a control period [sec]. The room temperature difference Δt is calculated from the indoor temperature detected by the indoor temperature sensor 206 among the operating states detected by the operating state detector 50 and the set room temperature detected in STEP 1. The control gains Kp and KI are determined by the responsiveness to actuator operation of the refrigeration cycle system in the air conditioner 100, and the control period Tint is also determined by the device specifications. For this reason, they are previously stored in the storage 30d and used as calculation information when calculation is performed by the calculator 30b.
Next, the protection target value determinator 45 sets a protection target value (STEP 4). Based on the operating state, the protection target value determinator 45 determines and sets a protection target value for each of the PI controllers 42a and 42b constituting the protection controller 42.
Here, since a correspondence between the protection target value and the operating state is determined depending on the specifications of the constituent devices constituting the air conditioner 100, it is previously stored in the storage 30d as the device specification information. The protection target value determinator 45 uses this device specification information when determining the protection target value.
Subsequently, the protection controller 42 calculates and outputs a protection rotation speed Fp (STEP 5). Here, the protection rotation speed Fp is output by each of the PI controller 42a and 42b constituting the protection controller 42. For example, in the control configuration shown in
Here, ΔTc is a high pressure difference [deg] defined by a difference between the condensation temperature Tc and the condensation temperature upper limit value (value obtained by subtracting the condensation temperature Tc from the condensation temperature upper limit value), and ΔTe is a low pressure difference [deg] defined by a difference between the evaporation temperature Te and the evaporation temperature lower limit value (value obtained by subtracting the evaporation temperature lower limit value from the evaporation temperature Te). Each of Kp and KI is the control gain for the PI control, where Kp is the proportional gain [Hz/° C.] and Kr is the integral gain [Hz/(° C.·sec)]. Tint is the control period [sec]. The control gains Kp and KI are determined by the responsiveness to actuator operation of the refrigeration cycle system in the air conditioner 100, and the control period Tint is also determined by the device specifications. For this reason, these values are previously stored in the storage 30d and used as calculation information when calculation is performed by the calculator 30b.
Used as the condensation temperature Tc of the refrigerant is the value detected during cooling operation by the gas side temperature sensor 202 or the liquid side temperature sensor 204 provided in the outdoor heat exchanger 3, and the value detected during heating operation by the gas side temperature sensor 207 or the liquid side temperature sensor 205 provided in the indoor heat exchanger 7. Used as the evaporation temperature Te is the value detected during cooling operation by the gas side temperature sensor 207 or the liquid side temperature sensor 205 provided in the indoor heat exchanger 7, and the value detected during heating operation by the gas side temperature sensor 202 or the liquid side temperature sensor 204 provided in the outdoor heat exchanger 3.
Note that the temperature sensors are used here to detect the condensation temperature and the evaporation temperature of the refrigerant. However, by installing pressure sensors directly on the suction side and the discharge side of the compressor 1, a pressure value of the high pressure Pd detected from the pressure sensor on the discharge side and a pressure value of the low pressure Ps detected from the pressure sensor on the suction side may be converted into saturation temperatures to obtain the condensation temperature Tc and the evaporation temperature Te, respectively. Conversely, the detected condensation temperature Tc and evaporation temperature Te may be converted into saturation temperatures to obtain the high pressure Pd and the low pressure Ps, respectively.
Further, the condensation temperature upper limit value for the high pressure difference ΔTc and the evaporation temperature lower limit value for the low pressure difference ΔTe are the protection target values calculated by the protection target value determinator 45, and are calculated and set based on the operating conditions. For example, for cooling operation, the storage 30d previously stores the specification information such that the condensation temperature upper limit value is changed in stages according to outside temperature conditions. In this case, the setting is made so that when the outside temperature during operation detected by the outdoor temperature sensor 203 is high, the set value of the condensation temperature upper limit value becomes high, and when the outside temperature is low, the set value of the condensation temperature upper limit value becomes low. In this way, the protection target value determinator 45 changes the protection target value according to the operating state during operation.
Further, for example, for heating operation, the storage 30d previously stores the specification information such that the condensation temperature upper limit value is changed in stages according to indoor temperature conditions. In this case, the setting is made so that when the indoor temperature during operation detected by the indoor temperature sensor 206 is high, the set value of the condensation temperature upper limit value becomes high, and when the indoor temperature is low, the set value of the condensation temperature upper limit value becomes low. In this way, the protection target value determinator 45 changes the protection target value according to the operating state during operation.
Next, the rotation speed selector 43 selects the minimum rotation speed between the capability rotation speed Fq output from the capability controller 41 and the protection rotation speed Fp output from the protection controller 42. For this purpose, first, the rotation speed selector 43 determines whether protection rotation speed Fp<capability rotation speed Fq is met (STEP 6). If the condition is met (STEP 6; YES), the rotation speed selector 43 selects the protection rotation speed Fp (STEP 7). If the condition is not met (STEP 6; NO), the rotation speed selector 43 selects the capability rotation speed Fq (STEP 8). Note that if there are a plurality of protection variables as shown in
Subsequently, 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 the value of the operating rotation speed F selected in STEPs 6 to 8 is smaller than the operating rotation speed upper limit value Fmax (STEP 9). If the condition is not met (STEP 9; NO), the upper and lower limit limiter 44 updates the selected operating rotation speed F to the operating rotation speed upper limit value Fmax (STEP 10), and outputs it as the control rotation speed F (STEP 13).
Further, the upper and lower limit limiter 44 determines whether the value of the operating rotation speed F selected in STEPs 6 to 8 is larger than the operating rotation speed lower limit value Fmin (STEP 11). If the condition is not met (STEP 11; NO), the upper and lower limit limiter 44 updates the selected operating rotation speed F to the operating rotation speed lower limit value Fmin (STEP 12), outputs it as the control rotation speed F (STEP 13), and then ends the control flow.
Note that, in the present embodiment, the case where the protection target value is changed according to the operating state has been described, but the parameter for changing the protection target value is not limited to the operating condition, and for example, the protection target value may be changed according to an installation condition of the air conditioner 100. For example, the protection target value may be changed depending on installation conditions of the refrigeration cycle circuit, such as the material, shape, and length of the refrigerant pipes (liquid connection pipe 6 and gas connection pipe 9 shown in
In this case, for example, the storage 30d stores a plurality of correspondence tables between the outside temperature and the condensation temperature upper limit value, as shown in Table 1, each of which corresponds to a material or shape of the refrigerant pipes. When an installer of the air conditioner 100 sets a material, shape, or length of the liquid connection pipe 6 and the gas connection pipe 9 in the controller 30, the protection target value determinator 45 determines a protection target value, using the correspondence table corresponding to the set material, shape, or length among the plurality of correspondence tables stored in the storage 30d.
Further, in the present embodiment, the case has been described in which the protection target value is changed according to the outside temperature condition, but the operating state of the parameter for changing the protection target value is not limited to this. For example, the protection target value may be timely changed based on other operating conditions such as the operating pressure of the refrigerant circuit (high pressure of the refrigerant, low pressure of the refrigerant) in the air conditioner 100. A specific example of control operation will be described in the next embodiment.
A configuration of an air conditioner 200 according to a second embodiment of the present disclosure will be described. The air conditioner 200 according to the present embodiment will be mainly described with respect to differences from the first embodiment, and a description of similar parts will be omitted. The refrigerant circuit of the air conditioner 200, the configuration of the controller 30, and the operation are the same as in the first embodiment. However, a method of determining a protection target value by the protection target value determinator 45 and specification information stored in the storage 30d are different.
Control operation of the air conditioner 200 in the present embodiment will be described based on
In the present embodiment, data on the operation map as shown in
After starting the flow, each unit of the air conditioner 200 first performs the operations in STEP 1 to STEP 3, similarly to the first embodiment. Next, based on the values of the condensation temperature Tc and the evaporation temperature Te detected in STEP 2 as the operating state of the air conditioner 200, the protection target value determinator 45 detects which position on the operation map of
Thereafter, using the condensation temperature upper limit value and the evaporation temperature lower limit value set in STEP 4, the protection controller 42 calculates and outputs a protection rotation speed Fp (STEP 5). Thereafter, STEP 6 to STEP 13 are the same operations as in the first embodiment.
Note that, in the present embodiment, the operation map stored in the storage 30d is the operating pressure range of the high pressure and the low pressure, but the operation map may be an operating temperature range of the condensation temperature Tc and the evaporation temperature Te.
Further, the storage 30d may store a plurality of operation maps corresponding to the respective ranges of the operating rotation speed of the compressor 1. The protection target value determinator 45 determines protection target values such as the condensation temperature upper limit value and the evaporation temperature lower limit value, using an operation map corresponding to the range to which the operating rotation speed of the compressor 1 belongs.
The air conditioners 100 and 200 of the above-described respective embodiments include: a refrigeration cycle circuit including the compressor 1 configured to compress a refrigerant; the operating state detector 50 configured to detect an operating state of the refrigeration cycle circuit; the protection target value determinator 45 configured to, based on the operating state, determine a protection target value of a protection variable regarding the refrigeration cycle circuit; and the rotation speed determinator configured to determine an operating rotation speed of the compressor 1, based at least on the protection target value and a capability target value of a temperature adjusted by the refrigeration cycle circuit.
As a result, the protection target value for satisfying the constraint conditions of the constituent devices can be changed according to the operating state, so that the performance of the air conditioners 100 and 200 is prevented from being unnecessarily restricted, thereby making it possible to achieve the high performance of the air conditioners 100 and 200.
The air conditioners 100 and 200 of the above-described respective embodiments timely set protection target values and control operations based not only on the constraint conditions based on the constituent device specifications, but also on the installation condition and the operating state of the air conditioners 100 and 200. This makes it possible to avoid excessive protection operations for the limit values of the constituent devices. As a result, the air conditioners 100 and 200 can expand the operating range in which normal operation is possible, compared to the conventional air conditioners.
The air conditioners 100 and 200 of the above-described respective embodiments can perform highly accurate operation control with respect to protection target values based not only on the constraint conditions based on the constituent device specifications, but also on the installation condition and the operating state of the air conditioners 100 and 200. This makes it possible to more increase the reliability of the air conditioners 100 and 200.
Although the features of the present disclosure have been described in each embodiment, the contents, such as the refrigerant flow path configuration (pipe connections), the configurations of the refrigerant circuit elements such as the compressor, the heat exchangers, and the expansion valve, and the like, are not limited to those described in each embodiment, and can be modified as appropriate within the scope of the technology of the present disclosure.
Further, each functional block of the controller 30 in
Further, when an integrated circuit technology that replaces the LSI appears due to advances in semiconductor technology, an integrated circuit based on that technology may be used.
Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and may include design changes without departing from the gist of the present invention.
This application is a U.S. national stage application of International Application No. PCT/JP2021/044840, filed on Dec. 7, 2021, the contents of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/044840 | 12/7/2021 | WO |
