Prediction apparatus, prediction method, and prediction program

Abstract

A prediction apparatus (1) comprises a storage device (3) and a calculation device (2) for predicting an output value in accordance with a prediction program (4) stored in the storage device (3). The calculation device (2): acquires a target temperature, a surrounding temperature of the surrounding of a temperature sensor (71), a first time constant of an output value represented by a first thermal resistance between the temperature sensor (71) and an object to be measured and by the heat capacity of the temperature sensor (71), and a second time constant of an output value represented by the thermal capacity and a second thermal resistance between the temperature sensor (71) and the surrounding thereof; and predicts an output value on the basis of the target temperature, the surrounding temperature, the first time constant, and the second time constant.

Description

Prediction device, prediction method, and prediction program

[0001] The present disclosure relates to a prediction device, a prediction method, and a prediction program that predict an output value of a temperature sensor that measures a target temperature of a measurement target.

[0002] Conventionally, there are known techniques for predicting the output value of a temperature sensor that measures the temperature of a measurement target. For example, Japanese Patent Application Laid-Open No. 2019-152358 discloses that in an ice maker that controls the opening degree of an expansion valve based on the output value of a temperature sensor that measures the temperature of a refrigerant flowing through an evaporator, the first-order lag of the output value of the temperature sensor is compensated based on the time constant of the temperature sensor, the ambient temperature of the temperature sensor, and the temperature sensed by the temperature sensor.

[0003] Japanese Patent Application Laid-Open No. 2019-152358

[0004] According to the ice maker disclosed in JP 2019-152358 A (Patent Document 1), it is possible to compensate for the first-order lag in the output value of the temperature sensor, but since the time constant of the temperature sensor used to compensate for the first-order lag has not been specifically considered, there is a risk that the output value of the temperature sensor after the first-order lag has been compensated for cannot be predicted with high accuracy.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a technique that can predict the output value of a temperature sensor with high accuracy.

[0006] A prediction device according to the present disclosure predicts an output value of a temperature sensor that measures the temperature of an object to be measured. The prediction device includes a storage device and a calculation device that predicts the output value according to a prediction program stored in the storage device. The calculation device acquires the object temperature, the ambient temperature around the temperature sensor, a first time constant of the output value represented by a first thermal resistance between the temperature sensor and the object to be measured and a heat capacity of the temperature sensor, and a second time constant of the output value represented by a second thermal resistance and a heat capacity between the temperature sensor and the surroundings, and predicts the output value based on the object temperature, the ambient temperature, the first time constant, and the second time constant.

[0007] A prediction method according to the present disclosure is a method for predicting an output value of a temperature sensor measuring a target temperature of a measurement target. The prediction method includes, as a process executed by a computer, the steps of acquiring the target temperature, an ambient temperature around the temperature sensor, a first time constant of the output value represented by a first thermal resistance between the temperature sensor and the measurement target and a heat capacity of the temperature sensor, and a second time constant of the output value represented by a second thermal resistance and a heat capacity between the temperature sensor and the surroundings, and predicting the output value based on the target temperature, the ambient temperature, the first time constant, and the second time constant.

[0008] A prediction program according to the present disclosure is a prediction program for predicting an output value of a temperature sensor that measures a target temperature of a measurement target. The prediction program causes a computer to execute steps of acquiring the temperature of the measurement target, an ambient temperature around the temperature sensor, a first time constant of the output value represented by a first thermal resistance between the temperature sensor and the measurement target and a heat capacity of the temperature sensor, and a second time constant of the output value represented by a second thermal resistance and a heat capacity between the temperature sensor and the surroundings, and predicting the output value based on the target temperature, the ambient temperature, the first time constant, and the second time constant.

[0009] According to the present disclosure, the output value of a temperature sensor can be predicted with high accuracy based on the object temperature of the object to be measured, the ambient temperature around the temperature sensor, the first time constant of the output value of the temperature sensor represented by the first thermal resistance between the temperature sensor and the object to be measured and the heat capacity of the temperature sensor, and the second time constant of the output value represented by the second thermal resistance and heat capacity between the temperature sensor and the surroundings.

[0010] FIG. 1 is a diagram showing the configuration of an air conditioner according to embodiment 1. FIG. 2 is a diagram showing the configuration of a prediction device and a compressor according to embodiment 1. FIG. 3 is a diagram showing the configuration of a prediction device and a compressor according to embodiment 1. FIG. 4 is a diagram for explaining various parameters used when the prediction device according to embodiment 1 calculates a predicted sensor value. FIG. 5 is a graph showing the refrigerant temperature actual measurement value, the predicted sensor value according to a comparative example, the predicted sensor value according to an embodiment, and changes over time in the actual sensor measurement value. FIG. 6 is a flowchart related to processing executed by the prediction device according to embodiment 1. FIG. 7 is a diagram for explaining various parameters used when the prediction device according to embodiment 2 calculates a predicted sensor value.

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. While multiple embodiments will be described below, it is anticipated from the beginning that the configurations described in each embodiment will be appropriately combined. Note that identical or corresponding parts in the drawings will be designated by the same reference numerals, and their description will not be repeated.

[0012] Embodiment 1. A prediction device 1 according to embodiment 1 will be described with reference to Figures 1 to 6. First, an air conditioner 1000 to which the prediction device 1 is applied will be described with reference to Figure 1. Figure 1 is a diagram showing the configuration of the air conditioner 1000 according to embodiment 1. Note that Figure 1 functionally shows the connection relationships and arrangement of the devices in the air conditioner 1000, and does not necessarily show the physical spatial arrangement.

[0013] As shown in FIG. 1 , the air conditioner 1000 includes a refrigerant circuit 100 that circulates a refrigerant, and a control device 70 that controls the refrigerant circuit 100 .

[0014] The refrigerant circuit 100 includes an outdoor unit 200 and an indoor unit 300. The outdoor unit 200 and the indoor unit 300 are connected by extension pipes 81 and 82, and a refrigerant circulates between the outdoor unit 200 and the indoor unit 300.

[0015] The outdoor unit 200 is generally placed outdoors in an area that is not subject to air conditioning, and is equipped with a compressor 10, a four-way valve 20, an outdoor heat exchanger 30, an outdoor blower 35, and a temperature sensor 71.

[0016] The four-way valve 20 includes a connection port 21, a connection port 22, a connection port 23, and a connection port 24. The connection port 21 of the four-way valve 20 is connected to the discharge pipe 12 of the compressor 10 via a pipe 91. The connection port 22 of the four-way valve 20 is connected to the outdoor heat exchanger 30 via a pipe 92. The connection port 23 of the four-way valve 20 is connected to the indoor unit 300 via a pipe 97 and an extension pipe 82. The connection port 24 of the four-way valve 20 is connected to the suction pipe 11 of the compressor 10 via a pipe 98. The four-way valve 20 is configured to switch its internal communication state under the control of the control device 70.

[0017] The compressor 10 is configured to be driven and stopped under the control of the control device 70. Specifically, the control device 70 controls the compressor 10 to arbitrarily change the drive frequency of the compressor 10. The compressor 10 changes the number of rotations per unit time, i.e., the rotational speed, in response to the change in drive frequency, thereby changing the amount of refrigerant discharged. Various types of compressors 10 can be used, and for example, a scroll type, a rotary type, a screw type, etc. can be used as the compressor 10.

[0018] The outdoor heat exchanger 30 exchanges heat between the refrigerant and air drawn in from outside by the outdoor blower 35, i.e., outside air. One end of the outdoor heat exchanger 30 is connected to the connection port 22 of the four-way valve 20 via a pipe 92. The other end of the outdoor heat exchanger 30 is connected to the indoor unit 300 via a pipe 93 and an extension pipe 81.

[0019] The outdoor blower 35 is configured to be driven and stopped under the control of the control device 70. Specifically, the control device 70 controls the outdoor blower 35 to arbitrarily change the drive frequency of the outdoor blower 35. The outdoor blower 35 changes the number of rotations per unit time, i.e., the rotational speed, in accordance with the change in drive frequency, thereby changing the amount of air sent to the outdoor heat exchanger 30.

[0020] The temperature sensor 71 is provided in the compressor 10 and measures the temperature of the refrigerant flowing through the compressor 10. Specifically, the temperature sensor 71 is provided so as to be in contact with the outer surface (shell 13 described below) of the compressor 10 and measures the temperature of the outer surface of the compressor 10 as the temperature of the refrigerant flowing inside the compressor 10. For example, the temperature sensor 71 is formed of a thermistor whose electrical resistance changes in response to a change in the temperature of the outer surface of the compressor 10. Data indicating the output value Tth (electrical resistance value) of the temperature sensor 71 is output to the control device 70.

[0021] The indoor unit 300 is generally disposed in an indoor space to be air-conditioned, and includes an indoor heat exchanger 50 , an indoor blower 55 , and an electronic expansion valve 40 .

[0022] The indoor heat exchanger 50 exchanges heat between the refrigerant and air drawn from the room by the indoor blower 55. One end of the indoor heat exchanger 50 is connected to the electronic expansion valve 40 via a pipe 95. The other end of the indoor heat exchanger 50 is connected to the outdoor unit 200 via a pipe 96 and an extension pipe 82.

[0023] The indoor blower 55 is configured to operate and stop under the control of the control device 70. Specifically, the control device 70 controls the indoor blower 55 to arbitrarily change the drive frequency of the indoor blower 55. The indoor blower 55 changes the number of rotations per unit time, i.e., the rotational speed, in accordance with the change in drive frequency, thereby changing the amount of air sent to the indoor heat exchanger 50.

[0024] The opening degree of the electronic expansion valve 40 is adjusted under the control of the control device 70. The electronic expansion valve 40 reduces the pressure of the refrigerant that has flowed in and causes the refrigerant obtained by the reduced pressure to flow out. The control device 70 can adjust the flow rate and the amount of pressure reduction of the refrigerant by adjusting the opening degree of the electronic expansion valve 40. One end of the electronic expansion valve 40 is connected to the outdoor unit 200 via a pipe 94 and an extension pipe 81. The other end of the electronic expansion valve 40 is connected to the indoor heat exchanger 50 via a pipe 95.

[0025] The air conditioner 1000 is controlled to one of a plurality of operation modes including a heating operation mode for heating the indoor space and a cooling operation mode for cooling the indoor space.

[0026] First, the operation of the air conditioner 1000 in the cooling operation mode will be described. As shown by the solid lines in Figure 1, in the cooling operation mode, the internal communication state of the four-way valve 20 is such that connection port 21 is connected to connection port 22 and connection port 23 is connected to connection port 24. In other words, in the cooling operation mode, the suction pipe 11 of the compressor 10 is connected to the indoor heat exchanger 50 side and the discharge pipe 12 of the compressor 10 is connected to the outdoor heat exchanger 30 side.

[0027] The compressor 10 draws in the low-temperature, low-pressure gas refrigerant from the indoor heat exchanger 50 and compresses the drawn gas refrigerant to increase the pressure of the gas refrigerant. The compressor 10 discharges the high-temperature, high-pressure gas refrigerant obtained by the compression to the outdoor heat exchanger 30.

[0028] In the cooling operation mode, the outdoor heat exchanger 30 functions as a condenser. The outdoor heat exchanger 30 exchanges heat between the high-temperature, high-pressure gas refrigerant from the compressor 10 and air drawn in from the outdoors by the outdoor blower 35. The gas refrigerant that has released heat into the air through this heat exchange condenses inside the outdoor heat exchanger 30 and changes into a high-temperature, high-pressure liquid refrigerant. The high-temperature, high-pressure liquid refrigerant obtained by the outdoor heat exchanger 30 flows out to the electronic expansion valve 40.

[0029] The electronic expansion valve 40 reduces the pressure of the high-temperature, high-pressure liquid refrigerant from the outdoor heat exchanger 30. The low-temperature, low-pressure gas-liquid two-phase refrigerant obtained by the pressure reduction by the electronic expansion valve 40 flows out to the indoor heat exchanger 50.

[0030] In the cooling operation mode, the indoor heat exchanger 50 functions as an evaporator. The indoor heat exchanger 50 exchanges heat between the low-temperature, low-pressure gas-liquid two-phase refrigerant from the electronic expansion valve 40 and air drawn from the room by the indoor blower 55. The gas-liquid two-phase refrigerant absorbs heat from the air through this heat exchange, evaporating inside the indoor heat exchanger 50 and changing into low-temperature, low-pressure gas refrigerant. The low-temperature, low-pressure gas refrigerant obtained by the indoor heat exchanger 50 flows out to the compressor 10. The air whose heat has been absorbed by the gas refrigerant in the indoor heat exchanger 50 is sent back into the room. This cools the room.

[0031] In this way, in the cooling operation mode, the refrigerant flows through the compressor 10, the outdoor heat exchanger 30 (condenser), the electronic expansion valve 40, and the indoor heat exchanger 50 (evaporator) in this order.

[0032] Next, the operation of the air conditioner 1000 in the heating operation mode will be described. As shown by the dashed lines in Figure 1, in the heating operation mode, the internal communication state of the four-way valve 20 is such that connection port 21 is connected to connection port 23 and connection port 22 is connected to connection port 24. In other words, in the heating operation mode, the suction pipe 11 of the compressor 10 is connected to the outdoor heat exchanger 30 side and the discharge pipe 12 of the compressor 10 is connected to the indoor heat exchanger 50 side.

[0033] The compressor 10 draws in the low-temperature, low-pressure gas refrigerant that has flowed in from the outdoor heat exchanger 30 and compresses the drawn gas refrigerant to increase the pressure of the gas refrigerant. The compressor 10 discharges the high-temperature, high-pressure gas refrigerant obtained by the compression to the indoor heat exchanger 50.

[0034] In the heating operation mode, the indoor heat exchanger 50 functions as a condenser. The indoor heat exchanger 50 exchanges heat between the high-temperature, high-pressure gas refrigerant from the compressor 10 and air drawn in from the indoor space by the indoor blower 55. The gas refrigerant that has released heat to the air through this heat exchange condenses inside the indoor heat exchanger 50 and changes into a high-temperature, high-pressure liquid refrigerant. The high-temperature, high-pressure liquid refrigerant obtained by the indoor heat exchanger 50 flows out to the electronic expansion valve 40. The air that has absorbed heat from the gas refrigerant in the indoor heat exchanger 50 is sent back into the indoor space. This heats the indoor space.

[0035] The electronic expansion valve 40 reduces the pressure of the high-temperature, high-pressure liquid refrigerant from the indoor heat exchanger 50. The low-temperature, low-pressure gas-liquid two-phase refrigerant obtained by the electronic expansion valve 40 flows into the outdoor heat exchanger 30.

[0036] In the heating operation mode, the outdoor heat exchanger 30 functions as an evaporator. The outdoor heat exchanger 30 exchanges heat between the low-temperature, low-pressure gas-liquid two-phase refrigerant from the electronic expansion valve 40 and air drawn in from the outdoors by the outdoor blower 35. The gas-liquid two-phase refrigerant absorbs heat from the air through this heat exchange, evaporating inside the outdoor heat exchanger 30 and changing into low-temperature, low-pressure gas refrigerant. The low-temperature, low-pressure gas refrigerant obtained by the outdoor heat exchanger 30 flows out to the compressor 10.

[0037] In this way, in the heating operation mode, the refrigerant flows through the compressor 10, the indoor heat exchanger 50 (condenser), the electronic expansion valve 40, and the outdoor heat exchanger 30 (evaporator) in this order.

[0038] In the air conditioner 1000 configured as described above, the control device 70 measures the temperature of the refrigerant flowing through the refrigerant circuit 100, and determines control data for controlling the controlled object based on the measured refrigerant temperature.

[0039] For example, the control device 70 determines control data for controlling the compressor 10 based on the output value Tth of the temperature sensor 71. The control device 70 adjusts the drive frequency of the compressor 10 by outputting the determined control data to the compressor 10. In this way, the control device 70 can adjust the temperature of the refrigerant flowing inside the compressor 10 to an appropriate temperature.

[0040] Alternatively, the control device 70 may control the controlled object using feedback control such as proportional integral differential (PID) control or proportional integral (PI) control. PID control is a control method that controls the input value of the controlled object based on the deviation between a value that changes in response to a change in the input value of the controlled object and a target value, the integral of that deviation, and the derivative of that deviation. In PI control, the derivative of the deviation is not taken into account, and the input value of the controlled object is controlled based on the deviation and the integral of that deviation. The control device 70 determines control data for PID control or PI control based on the output value Tth of the temperature sensor 71. The control device 70 can feedback control the controlled object by outputting the determined control data to the controlled object.

[0041] The control targets controlled by the control device 70 may include at least one actuator of the compressor 10 , the outdoor blower 35 , the indoor blower 55 , and the electronic expansion valve 40 .

[0042] During the design stage (or testing stage) before the air conditioner 1000 described above is shipped to the market, a designer determines in advance control parameters (for example, proportional gain, differential gain, or integral gain used in PID control or PI control) for determining control data for controlling a controlled object such as the compressor 10. For example, during the design stage, the designer determines in advance optimal control parameters so that optimal control data is determined based on the temperature of the refrigerant flowing through the compressor 10. The air conditioner 1000 is released to the market after the control parameters determined as described above are applied. Once the air conditioner 1000 is released to the market, the control device 70 uses the control parameters to determine control data for controlling the compressor 10 based on the output value Tth of the temperature sensor 71.

[0043] Here, conventionally, the method of measuring the temperature of the refrigerant flowing through the compressor 10 differs between the air conditioner 1000 used when the control parameters are determined in the design phase and the air conditioner 1000 released to the market. Specifically, in the air conditioner 1000 released to the market, the temperature of the outer surface of the compressor 10 is measured using the temperature sensor 71 configured as a thermistor as described above, whereas in the air conditioner 1000 used when the control parameters are determined in the design phase, the temperature of the outer surface of the compressor 10 is measured using a thermocouple soldered to the outer surface of the compressor 10. Because thermocouples have a smaller thermal capacity than thermistors, there is almost no time lag (first-order lag) in the response of the output value to changes in the temperature of the outer surface of the compressor 10. Therefore, by determining the control parameters in the design phase based on the output value (electromotive force) of the thermocouple, the designer can determine the control parameters without considering the first-order lag.

[0044] However, the temperature sensor 71 (thermistor) used in the air conditioner 1000 released on the market is larger in size and has a larger heat capacity than a thermocouple. Furthermore, because the temperature sensor 71 contacts the outer surface of the compressor 10 using a leaf spring-shaped holder, a thermal resistance (hereinafter also referred to as a "first thermal resistance") occurs between the temperature sensor 71 and the compressor 10. Furthermore, the output value of the temperature sensor 71 is affected by the temperature around the temperature sensor 71 (hereinafter also referred to as the "ambient temperature"), and a thermal resistance (hereinafter also referred to as a "second thermal resistance") also occurs between the temperature sensor 71 and the surroundings.

[0045] For this reason, the response of the output value of the temperature sensor 71 (thermistor) to temperature changes on the outer surface of the compressor 10 has a longer time delay (first-order lag) than the response of the output value of a thermocouple. Furthermore, the saturation value of the output value of the temperature sensor 71 is smaller than the saturation value of the output value of a thermocouple. Therefore, in an air conditioner 1000 that has been released to the market using control parameters determined using a thermocouple at the design stage, if the control device 70 determines control data for controlling the compressor 10 based on the output value of the temperature sensor 71, the control device 70 may not be able to determine appropriate control data due to the first-order lag of the temperature sensor 71.

[0046] Therefore, in the first embodiment, the designer determines control parameters based on the output value of the temperature sensor 71, which is configured as a thermistor, even during the design stage of the air conditioner 1000, just as with air conditioners 1000 used on the market. Furthermore, the designer uses the prediction device 1 to accurately predict the time change in the output value of the temperature sensor 71, taking into account a first-order lag in the output value of the temperature sensor 71, and determines control parameters based on the predicted output value of the temperature sensor 71 (hereinafter also referred to as the "sensor predicted value"). This allows the designer to determine appropriate control parameters from the design stage, taking into account the fact that a first-order lag will occur in the output value of the temperature sensor 71 in air conditioners 1000 released on the market.

[0047] 2 and 3 are diagrams illustrating the configurations of a prediction device 1 and a compressor 10 according to the first embodiment. In the example illustrated in FIGS. 2 and 3, it is assumed that the prediction device 1 predicts the output value of a temperature sensor 71 provided in the compressor 10 at the design stage. Note that FIG. 2 illustrates the compressor 10 arranged such that the intake pipe 11 extends in the X-axis direction on an X-Y plane extending in the X-axis direction and the Y-axis direction. FIG. 3 illustrates the compressor 10 arranged such that the intake pipe 11 extends in the X-axis direction on an X-Y plane extending in the Y-axis direction and the Z-axis direction.

[0048] 2 and 3 , the compressor 10 includes a shell 13, a suction pipe 11, and a discharge pipe 12. The suction pipe 11 is connected to a suction port (not shown) provided on the lower side surface of the shell 13. The discharge pipe 12 is connected to a discharge port (not shown) provided on the upper surface of the shell 13.

[0049] The temperature sensor 71, which is a thermistor, is provided in contact with the outer surface (side surface) of the shell 13 by a leaf spring-shaped holder (not shown). The output value Tth corresponds to the temperature of the outer surface of the compressor 10 measured by the temperature sensor 71 at a certain timing n (n is a natural number). ｎ The data indicating the above is output to the prediction device 1.

[0050] The compressor 10 is provided with a temperature sensor 72 that measures the temperature of the refrigerant (hereinafter also referred to as the "target temperature") that is the measurement target and present inside the shell 13. The temperature sensor 72 is, for example, a thermocouple soldered to the outer surface of the compressor 10. Data indicating the output value Tref corresponding to the target temperature measured by the temperature sensor 72 is output to the prediction device 1. Note that the temperature sensor 72 is a sensor that is used by the prediction device 1 to predict the output value of the temperature sensor 71 during the design stage, and therefore is not typically provided in air conditioners 1000 released to the market.

[0051] A temperature sensor 73 is provided around the temperature sensor 71 to measure the temperature around the temperature sensor 71 (hereinafter also referred to as the "ambient temperature"). Specifically, a temperature sensor 73 is provided around the shell 13 of the compressor 10 to measure the temperature in the atmosphere surrounding the shell 13 and the temperature sensor 71 (for example, the outside air temperature) as the "ambient temperature." Data indicating an output value Tair corresponding to the ambient temperature measured by the temperature sensor 73 is output to the prediction device 1.

[0052] The prediction device 1 includes a calculation device 2 and a storage device 3. The storage device 3 stores a prediction program 4 and prediction data 5. The calculation device 2 executes the prediction program 4 stored in the storage device 3 and uses the prediction data 5 to predict the time change in the output value of the temperature sensor 71 while taking into account a first-order lag in the output value of the temperature sensor 71, thereby obtaining a sensor prediction value.

[0053] The arithmetic device 2 is a computing entity (computer) that executes various processes by executing various programs. The arithmetic device 2 may be configured, for example, as a microcontroller, a central processing unit (CPU), a micro processing unit (MPU), a tensor processing unit (TPU), or a graphics processing unit (GPU). The arithmetic device 2 has the function of executing various processes by executing programs, but some or all of these functions may be implemented using dedicated hardware circuits such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). The arithmetic device 2 is not limited to processors in the narrow sense that execute processes using stored programs, such as a CPU, MPU, TPU, or GPU, but may also include hardwired circuits such as an ASIC or FPGA. Furthermore, the arithmetic device 2 is not limited to von Neumann computers such as a CPU or GPU, but may also be configured as non-von Neumann computers such as a quantum computer or an optical computer. The arithmetic device 2 may also be interpreted as a processing circuit that executes predetermined processes. The computing device 2 may be configured as a single chip or multiple chips. Furthermore, the computing device 2 and related processing circuits may be configured as multiple computers interconnected by wire or wirelessly via a local area network or a wireless network. The computing device 2 and related processing circuits may be configured as a cloud computer that performs remote calculations based on input data and outputs the calculation results to other devices located at a distance.

[0054] The storage device 3 stores various programs (e.g., the prediction program 4) or various data (e.g., the prediction data 5) executed by the arithmetic device 2. The storage device 3 may be one or more non-transitory computer-readable media, or one or more computer-readable storage media. Examples of the storage device 3 include a hard disk drive (HDD) and a solid state drive (SSD).

[0055] Although not shown, the arithmetic unit 2 may include a storage area (e.g., a working area) for storing program code or work memory when executing various programs. Examples of the storage area include volatile memory such as DRAM (Dynamic Random Access Memory) and SRAM (Static Random Access Memory), and non-volatile memory such as ROM (Read Only Memory) and flash memory.

[0056] In the prediction device 1, the calculation device 2 executes the prediction program 4 and predicts the output value (sensor prediction value) of the temperature sensor 71 by using the following formula (1) included in the prediction data 5.

[0057] In formula (1), Tth ｎ is a sensor predicted value at a certain timing n. Timing n is an example of a "first timing." ｎ＋１is the sensor predicted value at timing n+1, which is later than timing n. Timing n+1 is an example of a "second timing." Tref is the temperature of the refrigerant present inside the shell 13 (target temperature). Tair is the temperature around the temperature sensor 71 (ambient temperature). Cth is the heat capacity of the temperature sensor 71. R1 is the thermal resistance (first thermal resistance) between the temperature sensor 71 and the compressor 10. R2 is the thermal resistance (second thermal resistance) between the temperature sensor 71 and the periphery. Δt is the time between timing n and timing n+1. Multiplying Cth by R1 expresses a first time constant related to a first-order lag that occurs in the output value of the temperature sensor 71 due to the first thermal resistance. Multiplying Cth by R2 expresses a second time constant related to a first-order lag that occurs in the output value of the temperature sensor 71 due to the second thermal resistance.

[0058] For example, Fig. 4 is a diagram illustrating various parameters used when the prediction device 1 according to the first embodiment calculates a sensor prediction value. As shown in Fig. 4, an output value corresponding to the target temperature measured by the temperature sensor 72 is used for Tref. An output value corresponding to the ambient temperature measured by the temperature sensor 73 is used for Tair. A thermal capacity of the temperature sensor 71 is used for Cth. A thermal resistance (first thermal resistance) between the temperature sensor 71 and the compressor 10 is used for R1. A thermal resistance (second thermal resistance) between the temperature sensor 71 and the ambient is used for R2. It is difficult to theoretically model Cth, R1, and R2. Therefore, the designer determines (identifies) the first time constant represented by Cth and R1 and the second time constant represented by Cth and R2 by comparing the past measured refrigerant temperature values ​​measured by a thermocouple soldered to the outer surface of the compressor 10 and the past measured refrigerant temperature values ​​measured by the temperature sensor 72. The first time constant and the second time constant are included in the prediction data 5 and are stored in advance in the storage device 3.

[0059] The calculation device 2 of the prediction device 1 acquires Tref using the temperature sensor 72, acquires Tair using the temperature sensor 73, and acquires the first time constant and the second time constant from the storage device 3. The prediction device 1 calculates a sensor predicted value (Tth) according to equation (1) based on the acquired Tref, Tair, first time constant, and second time constant. ｎ＋１ ) is calculated. The calculation device 2 first calculates the sensor predicted value (Tth ｎ＋１ ) when calculating Tth ｎ Then, the calculation device 2 calculates Tth at timing n+1. ｎ＋１ When calculating Tth calculated at timing n before timing n+1, ｎ＋１ Tth ｎ Just substitute in.

[0060] Furthermore, the time term (Cth·(Tth ｎ＋１ -Tth ｎ ) / Δt) to 0, the following equation (2) can be obtained. The calculation device 2 executes the prediction program 4 and uses the following equation (2) included in the prediction data 5, thereby being able to predict the saturation value Tth that the output value (sensor predicted value) of the temperature sensor 71 will reach.

[0061] 5 is a graph showing changes over time in the measured refrigerant temperature, the predicted sensor value according to the comparative example, the predicted sensor value according to embodiment 1, and the measured sensor value. In FIG. 5, the graph, with time on the horizontal axis and temperature on the vertical axis, shows changes over time in the measured refrigerant temperature, the predicted sensor value according to the comparative example, the predicted sensor value according to embodiment 1, and the measured sensor value.

[0062] The actual refrigerant temperature measurement value is the temperature of the outer surface of the compressor 10 measured using a thermocouple soldered to the outer surface of the compressor 10. The sensor prediction value in the comparative example is a sensor prediction value calculated based on an equation in which the second time constant expressed by the multiplication of Cth and R2 in equation (1) is not used, that is, the multiplication of Cth and R2 is set to 0. The sensor prediction value in the first embodiment is a sensor prediction value calculated based on equation (1). The actual sensor measurement value is the temperature of the outer surface of the compressor 10 measured using the temperature sensor 71.

[0063] As shown in Figure 5, the sensor measurement value has a first-order lag compared to the refrigerant temperature measurement value. Furthermore, the saturation temperature of the sensor measurement value is lower than the saturation temperature of the refrigerant temperature measurement value. Therefore, in an air conditioner 1000 that has been released to the market using control parameters determined using a thermocouple during the design stage, if the control device 70 determines control data for controlling the compressor 10 based on the output value of the temperature sensor 71, the control device 70 may not be able to determine appropriate control data due to the first-order lag of the temperature sensor 71.

[0064] In contrast, the predicted sensor value calculated according to equation (1) changes over time at the same or approximately the same rate as the actual sensor value. Furthermore, the predicted sensor value according to embodiment 1 is calculated according to equation (1) that takes into account not only the first time constant expressed by the multiplication of Cth and R2 but also the second time constant expressed by the multiplication of Cth and R2, and therefore can be closer to the actual sensor value with higher accuracy than the predicted sensor value according to the comparative example that is calculated according to an equation that does not take into account the second time constant.

[0065] Therefore, if the prediction device 1 calculates the sensor predicted value according to equation (1) during the design stage of the air conditioner 1000 and determines the control parameters based on the calculated sensor predicted value, the optimal control parameters that match the actual sensor values ​​measured in the air conditioner 1000 released on the market can be applied to the air conditioner 1000.

[0066] Furthermore, if the prediction device 1 calculates the saturation value of the sensor predicted value according to equation (2) during the design stage of the air conditioner 1000 and determines the control parameters based on the calculated saturation value of the sensor predicted value, it is possible to apply to the air conditioner 1000 the optimal control parameters that match the actual sensor values ​​measured in the air conditioner 1000 released on the market.

[0067] An example of a process in which the prediction device 1 calculates a sensor predicted value during the design stage will be described with reference to Fig. 6. The calculation device 2 of the prediction device 1 executes the prediction program 4 to perform the process of the flowchart shown in Fig. 6. In Fig. 6, "S" is used as an abbreviation for "STEP."

[0068] 6 is a flowchart illustrating processing executed by the prediction device 1 according to the first embodiment. As shown in FIG. 6, the prediction device 1 acquires the temperature (target temperature) Tref of the refrigerant present inside the shell 13 based on the output value of the temperature sensor 72 (S1). The prediction device 1 acquires the temperature (ambient temperature) Tair around the temperature sensor 71 based on the output value of the temperature sensor 73 (S2). The prediction device 1 acquires a first time constant pre-stored in the storage device 3 (S3) and acquires a second time constant pre-stored in the storage device 3 (S4).

[0069] The prediction device 1 substitutes Tref, Tair, the first time constant, and the second time constant acquired in steps S1 to S4 into equation (1) to obtain the sensor predicted value Tth ｎ＋１ (S5). The prediction device 1 calculates the calculated sensor predicted value Tth ｎ＋１ Based on this, the control parameters are determined (S6), and the process ends.

[0070] The control parameters determined by the prediction device 1 are used by the control device 70 to determine control data based on the output value of the temperature sensor 71 after the air conditioner 1000 is released to the market.

[0071] As described above, the prediction device 1 according to the first embodiment can accurately predict the output value of the temperature sensor 71 according to Equation (1) based on the target temperature Tref of the refrigerant to be measured that is present inside the shell 13 of the compressor 10, the ambient temperature Tair around the temperature sensor 71, the first time constant of the output value of the temperature sensor 71 represented by the first thermal resistance R1 between the temperature sensor 71 and the refrigerant and the heat capacity Cth of the temperature sensor 71, and the second time constant of the output value represented by the second thermal resistance R2 between the temperature sensor 71 and the surroundings and the heat capacity Cth. This allows the designer to determine control parameters based on the accurately predicted output value of the temperature sensor 71 (sensor predicted value) during the design stage, and therefore allows the control device 70 to determine appropriate control data based on the output value of the temperature sensor 71 after the air conditioner 1000 is released to the market.

[0072] Second Embodiment A prediction device 1 according to a second embodiment will be described with reference to Fig. 7 . Fig. 7 is a diagram illustrating various parameters used when the prediction device 1 according to the second embodiment calculates a predicted sensor value. The prediction device 1 according to the first embodiment calculates a predicted sensor value using a first time constant represented by a first thermal resistance R1 between the temperature sensor 71 and the compressor 10 and a second time constant represented by a second thermal resistance R2 between the temperature sensor 71 and the surroundings. However, the prediction device 1 according to the second embodiment is configured to calculate a predicted sensor value by further using a third time constant represented by a third thermal resistance R3 between the temperature sensor 71 and a heat source.

[0073] 7, a heat source (not shown) may be provided around the temperature sensor 71. Examples of the heat source include a component or a pipe that secures the temperature sensor 71. In the prediction device 1 according to the second embodiment, the calculation device 2 executes the prediction program 4 and predicts the output value (sensor prediction value) of the temperature sensor 71 by using the following formula (3) included in the prediction data 5.

[0074] In equation (3), "Other" is the temperature of the heat source (hereinafter also referred to as "heat source temperature"). "R3" is the thermal resistance (third thermal resistance) between the temperature sensor 71 and the heat source. "Other" uses the output value of the temperature sensor 74, which measures the heat source temperature. "Cth" is multiplied by "R3" to express a third time constant related to the first-order delay that occurs in the output value of the temperature sensor 71 due to the third thermal resistance.

[0075] It is difficult to theoretically model Cth and R3. For this reason, the designer determines (identifies) the third time constant represented by Cth and R3 by comparing the past measured values ​​of the refrigerant temperature measured by a thermocouple soldered to the outer surface of the compressor 10 with the past measured values ​​of the refrigerant temperature measured by the temperature sensor 72. The third time constant is included in the prediction data 5 and is stored in advance in the storage device 3.

[0076] The calculation device 2 of the prediction device 1 acquires Tref using the temperature sensor 72, acquires Tair using the temperature sensor 73, acquires Other using the temperature sensor 74, and acquires the first time constant, the second time constant, and the third time constant from the storage device 3. The prediction device 1 calculates a sensor predicted value (Tth) according to equation (3) based on the acquired Tref, Tair, Other, the first time constant, the second time constant, and the third time constant. ｎ＋１ ) is calculated.

[0077] As described above, the prediction device 1 according to the second embodiment can accurately predict the output value of the temperature sensor 71 according to Equation (3) based on the target temperature Tref of the refrigerant to be measured that is present inside the shell 13 of the compressor 10, the ambient temperature Tair around the temperature sensor 71, the first time constant of the output value of the temperature sensor 71 represented by the first thermal resistance R1 between the temperature sensor 71 and the refrigerant and the heat capacity Cth of the temperature sensor 71, the second time constant of the output value represented by the second thermal resistance R2 between the temperature sensor 71 and the ambient and the heat capacity Cth, the heat source temperature Tother of the heat source in contact with the temperature sensor 71, and the third time constant of the output value represented by the third thermal resistance R3 between the temperature sensor 71 and the heat source. This allows the designer to determine control parameters based on the accurately predicted output value of the temperature sensor 71 (sensor predicted value) during the design phase. Therefore, after the air conditioner 1000 is released to the market, the control device 70 can determine appropriate control data based on the output value of the temperature sensor 71.

[0078] [Modification] A modification of the above-described embodiment will be described below. Note that only the differences from the above-described embodiment will be described below.

[0079] In the prediction device 1 according to the second embodiment described above, it is assumed that there is one heat source in contact with the temperature sensor 71. However, if there are two or more heat sources in contact with the temperature sensor 71, the prediction device 1 only needs to predict the output value of the temperature sensor 71 based on the heat source temperature of each of the two or more heat sources in contact with the temperature sensor 71 and the time constant of the output value represented by the thermal resistance and heat capacity between the temperature sensor 71 and each of the two or more heat sources.

[0080] In the prediction device 1 according to each of the first and second embodiments described above, the temperature of the refrigerant present inside the shell 13 of the compressor 10 is listed as the object to be measured by the temperature sensor 71. However, the object to be measured is not limited to the temperature of the refrigerant in the compressor 10. For example, the object to be measured may be the temperature of the refrigerant flowing through at least one of the compressor 10, the indoor heat exchanger 50, and the outdoor heat exchanger 30. Furthermore, the refrigerant to be measured may be at least one of a single-phase liquid, a single-phase gas, and a two-phase gas-liquid. Furthermore, the object to be measured may be the temperature of a heat sink of an inverter.

[0081] Furthermore, the prediction device 1 may be mounted on an air conditioner 1000. That is, the air conditioner 1000 may include a refrigerant circuit 100, a control device 70, and a prediction device 1. In the air conditioner 1000, the prediction device 1 may predict a sensor predicted value and determine a control parameter, and the control device 70 may use the control parameter predicted by the prediction device 1 to determine control data for controlling the compressor 10 based on the output value Tth of the temperature sensor 71.

[0082] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0083] 1 Prediction device, 2 Arithmetic device, 3 Storage device, 4 Prediction program, 5 Prediction data, 10 Compressor, 11 Intake pipe, 12 Discharge pipe, 13 Shell, 20 Four-way valve, 21, 22, 23, 24 Connection port, 30 Outdoor heat exchanger, 35 Outdoor blower, 40 Electronic expansion valve, 50 Indoor heat exchanger, 55 Indoor blower, 70 Control device, 71, 72, 73, 74 Temperature sensor, 81, 82 Extension pipe, 91, 92, 93, 94, 95, 96, 97, 98 Pipe, 100 Refrigerant circuit, 200 Outdoor unit, 300 Indoor unit, 1000 Air conditioner.

Claims

1. A prediction device that predicts an output value of a temperature sensor that measures the temperature of an object to be measured, comprising: a storage device; and a calculation device that predicts the output value in accordance with a prediction program stored in the storage device, wherein the calculation device acquires the object temperature, the ambient temperature around the temperature sensor, a first time constant of the output value represented by a first thermal resistance between the temperature sensor and the object to be measured and the heat capacity of the temperature sensor, and a second time constant of the output value represented by a second thermal resistance between the temperature sensor and the surroundings and the heat capacity, and predicts the output value based on the object temperature, the ambient temperature, the first time constant, and the second time constant.

2. The calculation device predicts the output value according to the following formula (1):

2. The prediction device of claim 1, wherein, in the formula (1), Tthn is the output value at a first timing, Tthn+1 is the output value at a second timing after the first timing, Tref is the target temperature, Tair is the ambient temperature, Cth is the heat capacity, R1 is the first thermal resistance, and R2 is the second thermal resistance.

3. The calculation device predicts a saturated value at which the output value is saturated according to the following formula (2): The prediction device according to claim 2 , wherein in the formula (2), Tth is the saturation value.

4. A prediction device according to any one of claims 1 to 3, wherein the calculation device predicts the output value further based on a heat source temperature of a heat source in contact with the temperature sensor, a third thermal resistance between the temperature sensor and the heat source, and a third time constant of the output value represented by the heat capacity.

5. A prediction device according to any one of claims 1 to 4, wherein the calculation device determines control parameters for controlling the controlled object based on the predicted output value.

6. A prediction device according to any one of claims 1 to 5, wherein the measurement object includes a refrigerant flowing through at least one of a compressor included in a refrigerant circuit and a heat exchanger included in the refrigerant circuit.

7. The prediction device according to any one of claims 1 to 6, wherein the temperature sensor includes a thermistor.

8. A prediction method for predicting an output value of a temperature sensor that measures the temperature of an object to be measured, comprising the steps of: acquiring the object temperature, the ambient temperature around the temperature sensor, a first time constant of the output value represented by a first thermal resistance between the temperature sensor and the object to be measured and the heat capacity of the temperature sensor, and a second time constant of the output value represented by a second thermal resistance between the temperature sensor and the surroundings and the heat capacity; and predicting the output value based on the object temperature, the ambient temperature, the first time constant, and the second time constant.

9. A prediction program for predicting an output value of a temperature sensor that measures the temperature of an object to be measured, the prediction program causing a computer to execute the steps of: acquiring the temperature of the object to be measured, the ambient temperature around the temperature sensor, a first time constant of the output value represented by a first thermal resistance between the temperature sensor and the object to be measured and the heat capacity of the temperature sensor, and a second time constant of the output value represented by a second thermal resistance between the temperature sensor and the surroundings and the heat capacity; and predicting the output value based on the object temperature, the ambient temperature, the first time constant, and the second time constant.

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