JP7374691B2 - Cooling device and cooling device control method - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act applies Publisher name: Japan Society of Mechanical Engineers, Society of Air-Conditioning and Hygiene Engineers, Japan Society of Refrigerating and Air-Conditioning Engineers Publication name: 53rd Air-Conditioning and Refrigeration Association Conference Lecture Proceedings Publication date: April 16, 2019

Article 30, Paragraph 2 of the Patent Act applies Publisher name: Japan Society of Air Conditioning and Sanitation Engineers, Public Interest Incorporated Association Publication name: Society of Air Conditioning and Sanitation Engineers 2019 Conference (DVD) Publication date: September 2020 4th day of the month

The present invention is a direct expansion cooling type refrigeration cycle that is installed in test equipment such as environmental test rooms and parts test rooms where load fluctuations are large, and that exchanges heat between the air in the target space and the phase change refrigerant while circulating the refrigerant. The present invention relates to a cooling device and a control method thereof.

The cooling method used in a cooling system consists of a primary cooling medium that is circulated within a refrigeration cycle in which a compressor, condenser, expansion valve, evaporator, etc. are connected via piping, and a secondary cooling medium that is circulated in a different circulation path from the refrigeration cycle. A cooling system with a built-in heat exchanger between the secondary cooling medium and air is installed, using a secondary cooling medium that exchanges heat with the cooling medium in the evaporator and is cooled by the heat exchange in the evaporator. For example, there is an indirect expansion cooling method (hereinafter referred to as an expansion method) that cools the air inside the equipment, which is the inside of the target space (for example, see Patent Document 1). In addition, the cooling medium (hereinafter sometimes referred to as refrigerant) that is circulated within the refrigeration cycle in which the compressor, condenser, expansion device, evaporator, pressure regulating valve, etc. are connected by piping, and the cooling device There is also a direct expansion cooling method (hereinafter referred to as direct expansion type) in which heat exchange between the air inside the equipment, which is the inside of the target space in which the equipment is installed, is performed using an evaporator, and the air inside the equipment is cooled. For example, see Patent Document 2). In the refrigeration cycle of a direct expansion type cooling device, the circulating refrigerant undergoes a cycle of compression stroke, condensation (heat radiation) stroke, expansion stroke, and evaporation (heat absorption) stroke. repeats the phase change between gas and liquid. In addition, in a direct expansion cooling system, the heat generated when the refrigerant condenses in the condenser is exhausted (radiated) to the air outside the target space, while the air inside the equipment is cooled by the heat absorbed by the refrigerant in the evaporator. . Therefore, direct expansion type cooling equipment has a simpler configuration and higher energy efficiency than inter-expansion type cooling equipment, which cools air using a secondary refrigerant that exchanges heat with the primary refrigerant. It is said that In addition, brine is used as a secondary cooling refrigerant when circulating at low temperatures below freezing, but it can be difficult to select a brine that is not corrosive at an appropriate temperature. There is no need to worry about this because it does not become a solid phase.

By the way, as a method of controlling a cooling device, for example, as disclosed in Patent Document 2, an electronic expansion valve is provided in a flow path between an evaporator and a compressor, and the temperature of refrigerant input to the evaporator is adjusted. It is common to perform feedback (Feed Back) control (hereinafter referred to as FB control) of the opening degree of the electronic expansion valve so that the degree of superheat calculated from the temperature of the refrigerant sent out from the evaporator reaches a target value. In addition, after determining the temperature difference between the evaporation temperature of the refrigerant and the refrigerant temperature at the outlet of the evaporator as the first temperature difference, the difference between the first temperature difference and the condensation temperature is determined as the second temperature difference. A first electrical signal obtained by multiplying the electrical signal corresponding to the obtained second temperature difference by a first proportionality constant, and a second electrical signal obtained by multiplying the value obtained by integrating the electrical signal with respect to time by a second proportionality constant. and a third electrical signal obtained by multiplying a value obtained by differentiating the electrical signal with respect to time by a third proportionality constant, and controlling the expansion valve according to the sum of these signals using PID (Proportional Integral Differential) feedback control. has also been devised (for example, see Patent Document 3).

Japanese Patent Application Publication No. 1-179866 Japanese Patent Application Publication No. 2014-119138 Special Publication No. 6-63668

For example, when controlling an electronic expansion valve using FB control, it is fine if the load fluctuation is small, but if the load fluctuation is large, the degree of superheating associated with the opening degree of the electronic expansion valve may be hunting with respect to the target value. However, as time passes, it converges to the target value. Therefore, if the load input fluctuates greatly when performing feedback control on the opening degree of the electronic expansion valve, it takes time for the degree of superheat to stabilize, making it unsuitable for equipment that requires temperature accuracy, such as a constant temperature room. In addition, when performing feedback control of an electronic expansion valve using PID control, if the integral time is set short or the derivative time is set long, it will be sensitive to load fluctuations and offset correction etc. will be overly controlled. Therefore, even if the load fluctuation is small, hunting occurs similarly to the above-mentioned FB control, and the degree of superheat becomes unstable. Further, in Patent Document 3, each of the first to third proportionality constants is changed depending on the temperature difference between the evaporation temperature and the condensation temperature of the refrigerant. Naturally, the temperature difference between the evaporation temperature and the condensation temperature fluctuates greatly, resulting in large overshoots and offsets. Therefore, even with PID control FB control in which the proportional term (P), integral term (I), and differential term (D) are devised, it takes time for the degree of superheat to stabilize, so , it is not suitable for equipment that requires temperature accuracy.

An object of the present invention is to provide a technology that can stably cool equipment that requires temperature accuracy even when the cooling load changes suddenly.

In order to solve the above-mentioned problems, the cooling device of the present invention constitutes a refrigeration cycle having a circulation path in which a compressor, a condenser, an expansion valve, an evaporator, and a pressure regulating valve are sequentially connected using piping. In a cooling device that sends air cooled by heat exchange with a cooling medium in an evaporator to a target space using a blower, an output ratio value of the compressor based on a pressure value of the cooling medium sucked into the compressor. a first control means that performs PID control on the output ratio value of the compressor using the obtained output ratio value of the compressor as a proportional term; and a temperature of the refrigerant at the inlet side of the evaporator. The opening value of the expansion valve based on the degree of superheat determined by the temperature of the cooling medium at the outlet side of the evaporator is determined using a proportional band, and the opening value of the expansion valve thus determined is set as a proportional term to calculate the opening value of the expansion valve. a second control means for performing PID control on the opening value of the pressure regulating valve based on the blowing temperature value on the outlet side of the evaporator of the air conveyed by the blower; a third control means for PID controlling the opening value of the pressure regulating valve using the opening value of the pressure regulating valve as a proportional term; air temperature output means capable of outputting respective output values of temperature and evaporator outlet air set temperature; and cooling load by the evaporator calculated based on output values from the air temperature output means at the first time. a determination unit that determines whether or not a cooling load by the evaporator has increased at a second time when a predetermined time has elapsed from time 1 ; If determined , the output ratio value of the compressor, the opening degree value of the expansion valve, and the pressure adjustment based on the multiple of the cooling load by the evaporator at the second time with respect to the cooling load by the evaporator at the first time. The opening values of the valves are each corrected by feedforward, and each corrected control value is used to control the compressor, the expansion valve, and the pressure regulating valve, and the output ratio value and each opening value are adjusted again. It is characterized by having a correction control means for performing correction control to return the output to PID control.

Further, the determination unit calculates a first judgment value by multiplying a temperature change of the air on the upstream side of the evaporator by a temperature change of the air on the downstream side of the evaporator, and If the determination value of 1 is a positive value, it is determined that the cooling load by the evaporator is increasing, and the correction control means determines that the cooling load by the evaporator is increasing by the determination unit. It is characterized by making a judgment.

Further, the determination unit determines a second determination value by multiplying the temperature change of the air on the upstream side of the evaporator by the temperature of the air sent to the target space and the set temperature, and The present invention is characterized in that when the determination value of No. 2 is a positive value, it is determined that the cooling load by the evaporator is increasing.

Further, the output ratio value of the compressor, the opening value of the expansion valve, and the opening value of the pressure regulating valve are determined by a coefficient for each component of a proportional component of the deviation, an integral component of the deviation, and a differential component of the deviation. It is characterized in that it is obtained by multiplying each component by a coefficient for each component, and then integrating the values of each component.

In addition to the circulation path, the refrigeration cycle has a bypass path that branches from a pipe between the compressor and the condenser and joins the pipe between the condenser and the compressor. Then, the opening value of the bypass valve disposed in the bypass passage and the bypass valve based on the pressure value of the cooling medium sucked into the compressor are determined from a proportional band, and the opening value of the bypass valve thus found is determined. and a fourth control means for PID controlling the opening degree value of the bypass valve using a proportional term, and the correction control means is configured to perform PID control when the determination unit determines that the cooling load by the evaporator is increasing. If determined , the opening degree value of the bypass valve is corrected by feedforward based on the multiple of the cooling load by the evaporator at the second time with respect to the cooling load by the evaporator at the first time, and the corrected opening value is The present invention is characterized in that the bypass valve is controlled using each of the degree values, and correction control is performed to return the opening degree value output to PID control again.

In addition, the opening value of the bypass valve is calculated by multiplying each of the proportional component of the deviation, the integral component of the deviation, and the differential component of the deviation by a coefficient for each component, and then calculating the value of each component multiplied by the coefficient for each component. It is preferable to obtain it by integrating.

Further, a proportional band of an output ratio value of the compressor based on a pressure value of the refrigerant sucked into the compressor in the first control step, and a proportional band of the output ratio value of the refrigerant sucked into the compressor in the fourth control step. Preferably, the slope of the control characteristic is opposite to the proportional band of the opening value of the bypass valve based on the pressure value of the cooling medium, and does not overlap in the pressure value of the cooling medium sucked into the compressor.

In addition, the corrected control value is the amount of air passing through the evaporator and the temperature of the air at the second time relative to the multiplication value of the amount of air passing through the evaporator and the temperature of the air at the first time. It is characterized in that it is calculated using the ratio of the multiplied values of .

In addition, the method for controlling a cooling device of the present invention includes configuring a refrigeration cycle having a circulation path in which a compressor, a condenser, an expansion valve, an evaporator, and a pressure regulating valve are sequentially connected using piping, and cooling in the evaporator. In a method for controlling a cooling device that sends air cooled by heat exchange with a medium to a target space, an output ratio value of the compressor based on a pressure value of the cooling medium sucked into the compressor is set in a proportional band. a first control step in which the output ratio value of the compressor is PID-controlled using the determined output ratio value of the compressor as a proportional term, and the temperature of the refrigerant at the inlet side of the evaporator and the The opening value of the expansion valve based on the degree of superheat determined by the temperature of the cooling medium at the outlet side of the vessel is determined using a proportional band, and the opening value of the expansion valve is converted into a proportional term to determine the opening degree of the expansion valve. a second control step in which the value is PID controlled ; and the opening value of the pressure regulating valve based on the blowing temperature value at the outlet side of the evaporator of the air conveyed by the blower is determined from a proportional band, and the determined pressure is a third control step of PID controlling the opening value of the pressure regulating valve using the opening value of the regulating valve as a proportional term; and evaporator inlet air temperature and evaporator outlet air temperature of the air conveyed by the blower . An air temperature output step capable of outputting an output value for each of the evaporator outlet air set temperatures, and a cooling load by the evaporator calculated based on the output value of the air temperature output step at the first time, from the first time. a determination step of determining whether the cooling load by the evaporator is increasing at a second time after a certain period of time has elapsed; and when it is determined by the determination step that the cooling load by the evaporator is increasing; Based on the multiple of the cooling load by the evaporator at the second time with respect to the cooling load by the evaporator at the first time, the output ratio value of the compressor, the opening degree value of the expansion valve, and the opening degree value of the pressure regulating valve are determined. Each corrected by feedforward, and each corrected control value is used to control the compressor, the expansion valve, and the pressure regulating valve, and the output ratio value and each opening value output are returned to PID control again. A correction control step for performing control.

Further, in the determination step, a first determination value is obtained by multiplying a temperature change of the air on the upstream side of the evaporator by a temperature change of the air on the downstream side of the evaporator, and The present invention is characterized in that when the determination value 1 is a positive value, it is determined that the cooling load by the evaporator is increasing.

Further, in the determination step, a second determination value is obtained by multiplying the temperature change of the air on the upstream side of the evaporator, the temperature of the air sent to the target space, and the set temperature, The present invention is characterized in that when the determination value of No. 2 is a positive value, it is determined that the cooling load by the evaporator is increasing.

Further, the output ratio value of the compressor, the opening value of the expansion valve, and the opening value of the pressure regulating valve are determined by a coefficient for each component of a proportional component of the deviation, an integral component of the deviation, and a differential component of the deviation. It is characterized in that it is obtained by multiplying each component by a coefficient for each component, and then integrating the values of each component.

In addition to the circulation path, the refrigeration cycle also includes a bypass path that branches from the piping between the compressor and the condenser and joins the piping between the condenser and the compressor; and a bypass valve disposed in the bypass passage, the opening value of the bypass valve is determined based on the pressure value of the cooling medium sucked into the compressor by taking a proportional band, and the calculated bypass valve is The method further includes a fourth control step of PID controlling the opening value of the bypass valve using the opening value as a proportional term, and the determining step determines that the cooling load by the evaporator is increasing. In this case , the opening value of the bypass valve is corrected by feedforward based on the multiple of the cooling load by the evaporator at the second time with respect to the cooling load by the evaporator at the first time, and the corrected opening value is Each of these is used to control the bypass valve and perform correction control to return the opening value output to PID control again.

In addition, the opening value of the bypass valve is calculated by multiplying each of the proportional component of the deviation, the integral component of the deviation, and the differential component of the deviation by a coefficient for each component, and then calculating the value of each component multiplied by the coefficient for each component. It is characterized by being calculated by integrating.

Further, a proportional band of an output ratio value of the compressor based on a pressure value of the refrigerant sucked into the compressor in the first control step, and a proportional band of the output ratio value of the refrigerant sucked into the compressor in the fourth control step. Preferably, the slope of the control characteristic is opposite to the proportional band of the opening value of the bypass valve based on the pressure value of the cooling medium, and does not overlap in the pressure value of the cooling medium sucked into the compressor.

In addition, the corrected control value is the amount of air passing through the evaporator and the temperature of the air at the second time relative to the multiplication value of the amount of air passing through the evaporator and the temperature of the air at the first time. It is characterized in that it is calculated using the ratio of the multiplied values of .

According to the present invention, even if the cooling load suddenly changes, stable cooling can be achieved in equipment that requires temperature accuracy.

It is a figure showing an example of composition of a cooling device. (a) A PH diagram showing the refrigeration cycle when the bypass valve is closed, and (b) a PH diagram showing the refrigeration cycle when the bypass valve is open. FIG. 2 is a functional block diagram showing an example of the configuration of a control device. (a) A graph showing the relationship between the opening degree of the bypass valve, the rotation speed of the compressor, and the suction pressure, (b) A graph showing the relationship between the degree of superheating and the opening degree of the expansion valve, (c) Blow temperature, It is a graph showing the relationship with the opening degree of the pressure regulating valve. FIG. 7 is a diagram summarizing functions f(k) when calculating a correction value. It is a flowchart which shows the control procedure at the time of cooling using a cooling device.

This embodiment will be described below with reference to the drawings.

As shown in FIG. 1, the cooling device 10 of this embodiment includes a compressor 15, a condenser 16, an expansion valve 17, an evaporator 18, a blower 19, a pressure regulating valve 20, and a bypass valve 21. The cooling device 10 has a circulation path that circulates a cooling medium (refrigerant), and a bypass path that is branched from the circulation path and bypasses the refrigerant as necessary. The circulation path includes a compressor 15, a condenser 16, an expansion valve 17, an evaporator 18, a blower 19, a pressure regulating valve 20, and refrigerant pipes 25, 26, 27, 28 that connect adjacent devices among these devices. , 29, 30, and 31. The bypass path is branched from a refrigerant pipe 25 that connects the compressor 15 and the condenser 16, and is connected to a refrigerant pipe 32 that is connected to the input side of the bypass valve 21 and an output side of the bypass valve 21 for pressure adjustment. It includes a refrigerant pipe 33 that joins a refrigerant pipe 31 that connects the valve 20 and the compressor 15. That is, in the cooling device 10 of the present embodiment, when the rotation speed of the drive motor (not shown) included in the compressor 15 is set to a lower limit value or more, the refrigerant is circulated in the above-mentioned circulation path. On the other hand, when the rotation speed of the compressor 15 is set to the lower limit value, the above-mentioned bypass valve 21 opens based on the suction pressure of the compressor 15, and the air flows to the bypass path. Hereinafter, the rotation speed of the compressor 15 will be referred to as the rotation speed of the compressor 15.

Therefore, the cooling device 10 of this embodiment circulates the refrigerant in a circulation path including the compressor 15, condenser 16, expansion valve 17, evaporator 18, blower 19, and pressure regulating valve 20, or in a bypass path. A refrigeration cycle is formed to cool the air in the equipment in which the cooling device 10 is installed. In addition, the code|symbol 34 is a sending duct of the air sent into the evaporator 18, and the code|symbol 35 is a sending duct which sends out the air which passed through the evaporator 18 into the equipment.

In this embodiment, a case is taken as an example in which the blower 19 is installed on the downstream side of the evaporator 18, but it is also possible to install the blower 19 on the upstream side of the evaporator 18.

The compressor 15 sucks the refrigerant from the evaporator 18 and compresses (adiabatic compression) the sucked refrigerant (compression stroke).

The refrigerant from the compressor 15 is sent to the condenser 16 . The refrigerant sent to the condenser 16 radiates heat through heat exchange with the outside air, thereby causing the refrigerant to condense (radiate heat) (condensation process).

The expansion valve 17 throttles and expands the refrigerant sent out from the condenser 16. Due to the throttle expansion, the pressure of the refrigerant sent into the expansion valve 17 is reduced (expansion stroke).

Refrigerant from the expansion valve 17 is fed into the evaporator 18 . The refrigerant sent to the evaporator 18 absorbs heat from the air through heat exchange with the air flowing through the feed duct and evaporates (evaporation process).

The pressure regulating valve 20 receives refrigerant from the evaporator 18 . The refrigerant from the evaporator 18 is depressurized by the pressure regulating valve 20 (decompression stroke).

The bypass valve 21 opens when the rotational speed of the compressor 15 reaches a lower limit value when the compressor 15 is driven, and allows a part of the refrigerant flowing through the refrigerant pipe 25 to flow into the refrigerant pipe 31 .

Among the refrigerant pipes described above, the refrigerant pipe 28 has a temperature sensor 41 . Temperature sensor 41 detects the temperature of the refrigerant immediately before being sent to evaporator 18 .

The refrigerant pipe 29 has a temperature sensor 42 and a pressure sensor 43. Temperature sensor 42 detects the temperature of the refrigerant immediately after being sent out from evaporator 18 . Pressure sensor 43 detects the pressure of the refrigerant immediately after being sent out from evaporator 18 .

The refrigerant pipe 30 has a temperature sensor 44 . The temperature sensor 44 detects the temperature of the refrigerant after being sent out from the pressure regulating valve 20.

The refrigerant pipe 31 has a temperature sensor 45 and a pressure sensor 46. Temperature sensor 45 detects the temperature of the refrigerant immediately before it is sucked into compressor 15. The pressure sensor 46 detects the pressure of the refrigerant immediately before it is sucked into the compressor 15.

The refrigerant pipe 33 has a temperature sensor 47. Temperature sensor 47 detects the temperature of the refrigerant after being sent out from bypass valve 20 .

The inlet duct 34 also has a temperature sensor 48 . Temperature sensor 48 detects the temperature of the air before it is sent into evaporator 18. The delivery duct 35 also includes a temperature sensor 49 . Temperature sensor 49 detects the temperature of air sent to blower 19 . Note that the reference numeral 50 is a temperature sensor that detects the temperature of the air immediately after being sent out from the evaporator 16.

Detection signals from the temperature sensor and pressure sensor described above are output to the control device 51.

When the cooling device 10 is driven, the control device 51 controls the drive of the compressor 15, the expansion valve 17, the pressure adjustment valve 20, and the bypass valve 21, as well as the blower 19. . Note that drive control of the compressor 15 and each control valve in the control device 51 will be described later.

As described above, in the cooling device 10 of this embodiment, for example, when the bypass valve 21 is closed, a refrigerating cycle is formed in which the refrigerant circulates within the circulation path. FIG. 2(a) is a PH diagram (pressure P-specific enthalpy h) when the bypass valve 21 is closed. Note that each symbol in the PH diagram indicates the refrigerant piping shown in FIG. As shown in FIG. 2(a), in the compression stroke (symbol A in FIG. 2(a)) by the compressor 15, the refrigerant is pressurized and becomes superheated steam. Next, in the condensation process (symbol B in FIG. 2A) by the condenser 16, the refrigerant radiates heat and becomes a supercooled liquid. Then, in the expansion stroke (symbol C in FIG. 2A) by the expansion valve 17, the refrigerant is depressurized and becomes wet saturated vapor (a state in which liquid and gas are mixed). Then, through the evaporation process (symbol D in FIG. 2A) by the evaporator 18, the cooling medium absorbs heat and becomes superheated steam. Finally, the pressure of the refrigerant is reduced in a pressure reduction stroke (symbol E in FIG. 2(a)) by the pressure expansion valve 17.

On the other hand, when the bypass valve 21 is open, a part of the refrigerant sent out from the compressor 15 and flowing toward the condenser 16 is sent into the bypass path. Therefore, the refrigerant cycle becomes a refrigeration cycle in which the refrigerant circulates not only in the circulation path but also in the bypass path. FIG. 2(b) is a PH diagram when the bypass valve 21 is open. In this refrigeration cycle, the condensation stroke, expansion stroke, evaporation stroke, and pressure reduction stroke are the same as when the bypass valve 21 is open. When the bypass valve 21 is open, the refrigerant sent out from the pressure regulating valve 20 joins the refrigerant sent out from the bypass valve 21 (the refrigerant flowing through the bypass path), and when the bypass valve 21 is closed. It differs from For example, when the rotation speed of the compressor 15 is fixed at the lower limit value, the refrigerant sent out from the bypass valve 21 is high-temperature, low-pressure superheated steam (reference numeral 33 in FIG. 2(b)). On the other hand, the refrigerant whose pressure has been reduced by the pressure expansion valve 17 is superheated steam at low temperature and low pressure (reference numeral 30 in FIG. 2(b)). At this time, the pressure of the refrigerant sent out from the bypass valve 21 and the pressure of the refrigerant reduced in pressure by the pressure regulating valve 20 are the same value. Therefore, since the refrigerant sent out from the bypass valve 21 is combined with the refrigerant whose pressure has been reduced by the pressure regulating valve 20, the temperature of the refrigerant after the combination is reduced (reference numeral 31 in FIG. 2(b)). Note that the temperature of the refrigerant is determined, for example, based on the mass flow rate of the refrigerant sent out from the bypass valve 21 and the mass flow rate of the refrigerant whose pressure has been reduced by the pressure regulating valve 20.

The basic principle of feedforward control in the above-mentioned cooling device 10 when the air-side heat load of the evaporator changes suddenly, that is, when the load fluctuation is large, will be explained.

In a refrigeration cycle, the degree of superheat or the suction pressure in the compressor 15 is generally controlled to be constant. The cooling load when the cooling device 10 is driven is proportional to the mass flow rate of the refrigerant. For example, when the cooling load is W (kW) and the mass flow rate of the refrigerant in the circulation path is Q _m (kg/sec), it is expressed by equation (1).

W ∝ Q _m ...(1)

Therefore, when the cooling load W at time t (sec) after a certain time Δt (sec) has passed is α times the cooling load before the certain time Δt has elapsed, the degree of superheat and the suction pressure in the compressor 15 must be varied. For example, the mass flow rate of the refrigerant in the evaporator 18 is multiplied by α, as shown in equation (2) below.

Q _m(t) = α・Q _m(t-Δt) ...(2)

Here, α can be determined using the following equation (3). Note that the symbol V in Equation (3) is the amount of air passing through the evaporator 18 (unit: m ³ /sec), and the symbol T is the temperature (unit: ° C.). Further, the symbol ΔT is the temperature difference (unit: °C) between the air before and after the evaporator 18.

Note that if the air volume passing through the evaporator 18 is constant, there is no need to consider the air volume V in the above equation (3).

For example, consider a case where the bypass valve 21 is closed and the rotation speed of the compressor 15 is controlled. In this case, the mass flow rate of the refrigerant passing through the compressor 15, the expansion valve 17, and the pressure regulating valve 20 is the same as the mass flow rate of the refrigerant passing through the evaporator 18. Therefore, the mass flow rates of the refrigerant in the compressor 15, expansion valve 17, and pressure regulating valve 20 are expressed by the following equations (4-1), (4-2), and (4-3). Hereinafter, the symbols for the compressor 15, expansion valve 17, and pressure regulating valve 20 will be referred to as co, ex, and ep.

Q _co(t) = α・Q _co(t-Δt) ...(4-1)
Q _ex(t) = α・Q _ex(t-Δt) ...(4-2)
Q _{ep (t)} = α・Q _{ep (t - Δt)} (4-3)

On the other hand, a case will be considered in which the opening degree of the bypass valve 21 and the rotation speed of the compressor 15 are controlled. In this case, the mass flow rate of the refrigerant passing through the expansion valve 17 and the pressure regulating valve 20 is the same as the mass flow rate of the refrigerant flowing through the evaporator 18 . Further, the mass flow rate of the refrigerant passing through the bypass valve 21 is the difference between the mass flow rate of the refrigerant flowing through the compressor 15 and the mass flow rate of the refrigerant flowing through the evaporator 18 . Therefore, the mass flow rates Q _{ex (t)} , Q _{ep (t)} , and Q _{b (t)} of the refrigerant in the expansion valve 17, pressure regulating valve 20, and bypass valve 21 are calculated using the following equations (5-1) and (5- 2) and equation (5-3). Here, the mass flow rate of the refrigerant in the bypass valve 21 is the same as the mass flow rate of the refrigerant in the bypass path. Therefore, the mass flow rate of the refrigerant in the bypass valve 21 is defined as Q _{b (t)} .

Q _ex(t) = α・Q _ex(t-Δt) ...(5-1)
Q _{ep (t)} = α・Q _{ep (t - Δt)} (5-2)
Q _b(t) = {γ・(1-α)+1}・Q _b(t-Δt) ...(5-3)

Here, the symbol γ is the ratio between the mass flow rate of the refrigerant flowing through the evaporator 18 and the mass flow rate of the refrigerant flowing through the bypass valve 21.

For example, the ratio γ is determined as follows.

For example, consider a case where the rotation speed of the compressor 15 is driven at the lower limit value. At this time, assuming that the mass flow rate of the refrigerant in the compressor 15 is constant, it is expressed by the following equations (6) and (7). Note that the mass flow rate Q _b of the refrigerant is the mass flow rate of the refrigerant flowing through the bypass path.

Q _co =Q _m(t-Δt) +Q _b(t-Δt) ...(6)
Q _co =Q _m(t) +Q _b(t) ...(7)

Therefore, the following equation (8) is obtained from equations (6) and (7).

Q _b(t) =Q _m(t-Δt) -Q _m(t) +Q _b(t-Δt) ...(8)
By converting the equation (8) into an equation that calculates the ratio of the mass flow rate of the refrigerant flowing through the bypass valve 21, the following equation (9) can be obtained.

Here, the coefficient α and the coefficient γ in Equation (9) are expressed by Equation (10) below.

Therefore, the mass flow rate Q _b(t) of the refrigerant in the bypass valve 21 can be obtained as the above-mentioned equation (5-3) using equation (9).

Incidentally, the above-mentioned coefficient γ is the ratio between the mass flow rate of the refrigerant in the evaporator 18 and the mass flow rate of the refrigerant in the bypass valve 21. The ratio γ can also be expressed as a ratio of specific enthalpy h (J/kg). Furthermore, when the change in the degree of superheating is not large, the specific enthalpy h and the temperature T are in a proportional relationship. Therefore, the coefficient γ can also be approximately expressed as a temperature ratio, as shown in equation (11) below. Here, the enthalpies h ₃₀ , h ₃₁ , and h ₃₃ are the enthalpies inside the refrigerant pipes 30, 31, and 33. Further, temperatures T ₃₀ , T ₃₁ , and T ₃₃ indicate temperatures inside the refrigerant pipes 30 , 31 , and 33 .

Here, in the compressor 15, when the suction pressure is constant, the rotation speed R (rpm) of the drive motor is proportional to the mass flow rate of the refrigerant, as shown in equation (12).

R ∝ Q _co ...(12)

Furthermore, if the pressures before and after each control valve are the same, the Cv value of the control valve is as shown in the following equations (13-1), (13-2), and (13-3): Proportional to mass flow rate.

Cv _ex ∝ Q _ex ... (13-1)
Cv _ep ∝ Q _ep ... (13-2)
Cv _bv ∝ Q _bv ... (13-3)

Therefore, when the mass flow rate of the refrigerant in the evaporator 18 is multiplied by α, the following equations (14-1), (14-2), and (14-3) hold true. In addition, in the following formula, the number of rotations of the compressor 15 (specifically, the number of rotations of the drive motor included in the compressor) is represented by the symbol R.

R _(t) = α・R _(t−Δt) (14-1)
Cv _ex(t) = α・Cv _ex(t-Δt) ...(14-2)
Cv _{ep (t)} = α・Cv _{ep (t - Δt)} (14-3)
Cv _bv(t) = {γ・(1-α)+1}・Cv _bv(t-Δt) ...(14-4)

Note that equation (14-1) holds true when the bypass valve 21 is closed. Furthermore, equation (14-4) holds true when the rotational speed of the compressor 15 is at the lower limit.

Here, the control valves used in the cooling device 10, such as the expansion valve 17, the pressure regulating valve 20, and the bypass valve 21, will be considered. Examples of the control valve include a control valve with linear characteristics and a control valve with equal percentage characteristics.

For example, when the control valve is a control valve with linear characteristics, the relationship between the opening degree of the control valve and the Cv value is expressed by the following equation (15).

The symbol Cv _H in the above equation (15) indicates the value of CV with respect to the rated value of the control valve. Further, the symbol φ _H is the opening degree of the control valve with respect to the rated value of the control valve, and the symbol φ _L is the opening degree of the control valve with respect to the cutoff value of the control valve.

Further, when the control valve is a control valve with equal percentage characteristics, the relationship between the opening degree of the control valve and the Cv value is expressed by the following equation (16).

The symbol Ra in the above equation (16) is the range ability of the control valve.

When the expansion valve 17, pressure regulating valve 20, and bypass valve 21 are control valves with linear characteristics, the opening degree of each control valve is determined by the following equations (17-1), (17-2), and (17-2). 3).

On the other hand, when the expansion valve 17, pressure regulating valve 20, and bypass valve 21 are control valves with equal percentage characteristics, the opening degree of each control valve is determined by the following equations (18-1), (18-2), and equations It is expressed as (18-3).

Therefore, the opening degree of each control valve can be determined by either equation (17) or equation (18) described above based on the characteristics of the control valve.

In this way, regarding the cooling load W in the evaporator 18, when the cooling load W at time t (sec) after a certain period of time Δt (sec) is α times the cooling load before the certain period of time Δt has elapsed, When the above assumptions change, the Cv values of the control valves such as the expansion valve 17, the pressure regulating valve 20, and the bypass valve 21 are expressed in relational formulas. 20 and the bypass valve 21 can be derived from a multiple of α times the cooling load, it can be seen that if the opening degrees are used for feedforward control, the control point can be brought to a nearby control point faster than FB control.

Then, not only the opening degrees of the expansion valve 17, pressure regulating valve 20, and bypass valve 21 are derived from multiples of α times the cooling load, but also the compressor 15 is controlled for a certain period of time Δt (sec) with respect to the cooling load W in the evaporator 18. When the cooling load W at the elapsed time t (sec) is α times the cooling load before the elapse of a certain time Δt, the mass flow rate is derived from the relationship of equation (4-1), and the flow rate is feedforward controlled. It is preferable.

As shown in FIG. 3, the control device 51 includes a CPU 55, a ROM 56, and a RAM 57. By executing the control program 58 stored in the ROM 56, the CPU 55 controls the first control section 61, the second control section 62, the third control section 63, the fourth control section 64, the fifth control section 65, and the determination section 66. It has the following functions.

The first control unit 61 drives and controls the rotation speed of the compressor 15 using PID (Proportional Integral Differential) control. Note that the PID control will be described later. The first control unit 61 performs calculation using the deviation between the pressure value (suction pressure) P _co obtained from the output signal of the pressure sensor 46 and the target pressure value P ₀ , and rotates the input value as the obtained pressure value. Convert input value as a number. In other words, the output ratio value (%) of the compressor 15 based on the pressure value P _co of the refrigerant sucked into the compressor 15 is determined in a proportional band, and the determined output ratio value (%) of the compressor is converted into a proportional term. The output ratio value (%) of the compressor is controlled by PID. As shown in FIG. 4A, for example, if the pressure value P _co obtained from the output signal of the pressure sensor 46 is less than the predetermined pressure value P1, the first control unit 61 sets the rotation speed to the lower limit value R _L is the input value. Further, if the suction pressure value to the compressor 15 is equal to or higher than the predetermined pressure value P1, the pressure value P _co and the rotation speed of the compressor 15 can be expressed as a linear function, and the suction pressure value to the compressor 15 As the number of rotations of the compressor 15 increases, the rotation speed of the compressor 15 increases.

The second control unit 62 drives and controls the opening degree of the expansion valve 17 using PID control. The second control unit 62 determines the degree of superheating SH _ex from the difference between the temperature T _in obtained from the output signal of the temperature sensor 41 and the temperature T _ev obtained from the output signal of the temperature sensor 42 . Then, calculation is performed using the deviation between the obtained degree of superheat SH _ex and the target degree of superheat SH ₀ to obtain the opening degree of the expansion valve 17 . That is, the expansion is based on the degree of superheat SH _ex determined by the temperature value T _in of the coolant temperature sensor 41 on the inlet side of the evaporator 18 and the temperature value T _ev of the coolant temperature sensor 42 on the outlet side of the evaporator 18. The opening value of the valve 17 is determined using a proportional band, and the opening value of the expansion valve 17 is PID controlled using the determined opening value of the expansion valve 17 as a proportional term. As shown in FIG. 4(b), the opening degree of the expansion valve 17 and the degree of superheat SH _ex can be expressed by a linear function that can be taken in a proportional band, and as the degree of opening of the expansion valve 17 increases, the degree of superheat SH _ex also becomes larger. Note that, as shown in FIG. 4(b), the opening degree of the expansion valve 17 and the degree of superheat SH _ex can be expressed by a linear function, and as the degree of opening of the expansion valve increases, the degree of superheat SH _ex also increases.

The third control unit 63 drives and controls the opening degree of the pressure regulating valve 20 by PID control. The third control unit 63 performs calculation using the deviation between the temperature T _sa obtained from the output signal of the temperature sensor 49 and the set temperature T ₀ and converts the obtained input value (temperature) into a pressure value. Then, the third control unit 63 calculates the opening degree of the pressure regulating valve 20 by performing calculation using the deviation between the pressure value obtained by the conversion and the pressure _Pep obtained from the output signal of the pressure sensor 43. . That is, the opening value of the pressure regulating valve 20 is determined based on the blast temperature T _sa of the blast temperature sensor 49 on the outlet side of the evaporator 18 of the air conveyed by the blower 19 in a proportional band, and the opening value of the pressure regulating valve 20 determined is The opening value of the pressure regulating valve 20 is controlled by PID using the opening value as a proportional term. As shown in FIG. 4(c), the opening degree of the pressure regulating valve 20 and the blowing temperature _Tsa have a proportional relationship that can be taken into a proportional band, and as the opening degree of the pressure regulating valve 20 increases, the blowing temperature _Tsa also increases. It gets expensive.

The fourth control unit 64 drives and controls the opening degree of the bypass valve 21 by PID control. The fourth control unit 64 performs calculation using the deviation between the pressure value (suction pressure) P _co obtained from the output signal of the pressure sensor 46 and the target pressure value P ₀ and bypasses the input value as the obtained pressure value. The input value is converted into an input value as the opening degree value of the valve 21. Then, the fourth control unit 64 calculates the opening degree of the bypass valve 21 by performing calculation using the deviation between the calculated difference and the target difference. In other words, the opening value of the bypass valve 21 is determined based on the pressure value P _co of the refrigerant sucked into the compressor 15 obtained from the output signal of the pressure sensor 46 in a proportional band, and the opening value of the bypass valve 21 is calculated based on the proportional band. The opening value of the bypass valve 21 is controlled by PID using the proportional term. The bypass valve 21 opens when the suction pressure in the compressor 15 becomes less than or equal to a predetermined pressure value P1. Note that the suction pressure P _co and the opening degree of the bypass valve can be expressed as a linear function, and as the suction pressure P _co increases, the opening degree of the bypass valve 21 decreases.

As described above, the first control section 61, the second control section 62, the third control section 63, and the fourth control section 64 perform PID control on the compressor 15, the expansion valve 17, the pressure regulation valve 20, and the bypass valve 21. . PID control uses coefficients associated with each component to the proportional component of the deviation between the output value (detected value) of the device to be controlled and the target output value, the integral component of the deviation, and the differential component of the deviation. After multiplication, a value obtained by integrating the multiplied values is used as an input value to control the target device. Specifically, the following equation (19) is used in PID control. Note that e(t) in equation (19) is the deviation between the output value (detected value) of the device to be controlled and the target output value.

Here, the coefficient K _p , the coefficient K _i , and the coefficient K _d are determined, and these coefficients are determined so that the control is stable under the condition that the cooling load in the cooling device 10 is stable. Specifically, these coefficients are obtained from the control results when the cooling device 10 is actually driven.

The fifth control section 65 functions based on the determination result of the determination section 66, which will be described later. For example, when the determination unit 66 (described later) determines that the cooling load is large, the fifth control unit 65 controls the cooling load W in the evaporator 18 at a time t (sec) after a certain period of time Δt (sec) has elapsed. ) when the cooling load W becomes α times the cooling load before the elapse of a certain period of time Δt, the value of α is large, and if it changes in a short time, the Cv value of the control valves such as the expansion valve 17, pressure regulating valve 20, and bypass valve 21 increases. If we proceed further with the relational expression, the opening degrees of the expansion valve 17, pressure regulating valve 20, and bypass valve 21, which can be derived from the characteristics of the control valve, can be derived from a multiple of α times the cooling load, so the opening degrees can be corrected as feedforward control. As input values, the rotational speed of the compressor 15, which is a direct operating device, and the correction value of the opening degree of each control valve of the expansion valve 17, the pressure regulating valve 20, and the bypass valve 21 are input for each device.

Here, the corrected input value u _{ALL (t) when} the correction control functions is calculated by the following _formula ( 20).

Further, the formula for determining the correction value u _FF(t) is the following formula (21).

As shown in FIG. 5, f(k) in equation (21) is selected according to the type of control valve for which the correction value is sought and the characteristics of the control valve used.

The determination unit 66 determines whether the cooling load on the cooling device 10 is large. This determination is performed every time a certain period of time (Δt) has elapsed. Note that Δt is set to, for example, 1 to 10 (sec).

The determination unit 66 determines the temporal change in the temperature on the upstream side of the evaporator 18 (temperature obtained from the detection signal of the temperature sensor 48) _Tei , the temperature on the downstream side of the evaporator 18 (the temperature obtained from the detection signal of the temperature sensor 50) ) Determination value D _{1 (kΔt)} is determined from the time change of T _eo . The determination unit 66 also determines the temporal change in the temperature on the upstream side of the evaporator 18 (temperature obtained from the detection signal of the temperature sensor 48) _Tei and the temperature inside the delivery duct 35 (the temperature obtained from the detection signal of the temperature sensor 49). The determination value D _{2 (kΔt)} is determined from the difference between the set temperature T _sasp and the set temperature T _sasp . Note that the equations for determining the determination values D _{1 (kΔt)} and D _{2 (kΔt)} are the following equations (22) and (23).

In this embodiment, since the blower 19 is located downstream of the evaporator 18, the temperature _Teo is detected by the temperature sensor 50, and the temperature _Tsa is detected by the temperature sensor 49. 18, the temperature T _eo and the temperature T _sa have the same value. Therefore, if the blower 19 is arranged upstream of the evaporator 18, it is possible to arrange one temperature sensor.

The determination unit 66 determines whether the cooling load on the cooling device 10 is large based on the calculated determination values D _{1 (kΔt)} and D _{2 (kΔt)} . Note that the determination unit 66 performs determination using the determination value D _{1 (kΔt)} and, if necessary, performs determination using the determination value D _{2 (kΔt)} .

For example, when the judgment value D _{1 (kΔt)} is 0 or more, the time change in the temperature T _ei on the upstream side of the evaporator 18 and the time change in the temperature T _eo on the downstream side of the evaporator 18 when the predetermined time Δt has elapsed. indicates that both are positive or negative. In other words, the temperature T _ei on the upstream side of the evaporator 18 and the temperature T _eo on the downstream side of the evaporator 18 change over time when the predetermined time Δt has elapsed, and these temperatures are rising or falling. It is shown that. That is, for example, when the cooling load increases, the temperature _Tei on the upstream side of the evaporator 18 increases. Moreover, although the air is cooled by passing through the evaporator 18, the temperature T _eo on the downstream side of the evaporator 18 also increases. Therefore, in this case, the determination unit 66 determines that it is necessary to perform the above-described correction control.

On the other hand, when the determination value D _{1 (kΔt)} is less than 0, it indicates that the temporal change in the temperature T _eo on the downstream side of the evaporator 18 after the predetermined time Δt has elapsed is negative. In other words, this indicates that the cooling load on the cooling device 10 has decreased and the temperature T _eo on the downstream side of the evaporator 18 has decreased. That is, when the cooling load is decreasing, the determination unit 66 determines that there is no need to perform the above-described correction control. Note that in this case, only PID control is executed.

In addition, when the judgment value D _{2 (kΔt)} is 0 or more, the time change of the temperature T _ei on the upstream side of the evaporator 18 when the predetermined time Δt has passed, the temperature T _sa inside the delivery duct 35, and the set temperature This indicates that both the difference from T _sasp is positive or negative. In other words, the temperature increases or decreases based on the time change in the temperature T _ei on the upstream side of the evaporator 18 when the predetermined time Δt has elapsed, and the difference between the temperature T _sa inside the blower duct 35 and the set temperature T _sasp . It shows that you are doing it. For example, when the cooling load increases, the temperature T _ei on the upstream side of the evaporator 18 increases. Further, the temperature inside the air duct 35 is higher than the set temperature T _sasp . Therefore, in this case, the determination unit 66 determines that it is necessary to perform the above-described correction control.

On the other hand, although the temperature T _ei on the upstream side of the evaporator 18 increases, the temperature T _sa inside the blower duct 35 may be lower than the set temperature T _sasp . In this case, the determination value D _{2 (kΔt)} is less than 0. Therefore, the determination unit 66 determines that there is no need to perform the above-described correction control. Note that in this case, feedforward control is not executed and only PID control is executed.

Next, a method of controlling the cooling device 10 of this embodiment will be explained based on the flowchart of FIG. 6. Note that the flowchart shown in FIG. 6 is based on the premise that the cooling conditions for the cooling device 10 have already been set. Note that the cooling conditions are set using an operation panel (not shown), and the driving conditions for the compressor 15 and each control valve are set based on the operation using the operation panel.

Step S101 is a process of driving and controlling the compressor 15 and each control valve using PID control. The control device 51 drives and controls the compressor 15, the expansion valve 17, the pressure regulating valve 20, and the bypass valve 21 using PID control.

Step S102 is a process of determining whether a predetermined time (Δt) has elapsed. The control device 51 has a timer function (not shown), and determines whether the time Δt has elapsed. For example, if the time Δt has elapsed, the control device 51 determines Yes as a result of the determination process in step S102. In this case, the process advances to step S103. On the other hand, if the time Δt has not elapsed, the control device 51 sets the result of the determination process in step S102 to No. In this case, the process advances to step S109.

Step S103 is a process for calculating determination values D _{1 (kΔt)} and D _{2 (kΔt)} . The control device 51 calculates the determination value D _{1 (kΔt} ) and the determination value D _{2 (kΔt)} using the above-mentioned equations (22) and (23).

Step S104 is a process of determining whether the determination value D _{1 (kΔt)} ≧0. If the determination value D _{1 (kΔt)} obtained in step S103 is D _{1 (kΔt)} ≧0, the result of the determination process in step S104 is Yes. In this case, the process advances to step S105.

On the other hand, if the determination value D _{1 (kΔt)} obtained in step S103 is D _{1 (kΔt)} <0, the result of the determination process in step S104 is No. In this case, the process returns to step S101. Therefore, when D _{1 (kΔt)} <0, the compressor 15 and each control valve continue to be driven and controlled by PID control.

Step S105 is a process of determining whether the determination value D _{2 (t)} ≧0. If the determination value D _{2 (kΔt)} obtained in step S103 satisfies D _{2 (kΔt)} ≧0, the result of the determination process in step S105 is Yes. In this case, the process advances to step S106.

On the other hand, if the determination value D _{2 (kΔt)} obtained in step S103 is D _{2 (kΔt)} <0, the result of the determination process in step S105 is No. In this case, the process returns to step S101. Therefore, even when D _{2 (kΔt)} <0, the compressor 15 and each control valve continue to be driven and controlled by PID control.

Step S106 is a process of calculating a corrected input value. First, the control device 51 calculates the coefficient α and the coefficient γ. After determining the coefficient α and the coefficient γ, the control device 51 determines the corrected input value using the above-mentioned equation (20). Note that the correction input value is calculated for the rotation speed of the compressor 15 and the opening degree of each control valve.

Step S107 is a process of controlling the drive of the compressor 15 and each control valve using the corrected input value. The control device 51 drives and controls the compressor 15, the expansion valve 17, the pressure regulating valve 20, and the bypass valve 21 using the corrected input value calculated in step S106.

Step S108 is a process of determining whether a predetermined time (Δt) has elapsed. The control device 51 has a timer function (not shown), and determines whether the time Δt has elapsed. For example, if the time Δt has elapsed, the control device 51 determines Yes as a result of the determination process in step S108. In this case, the process returns to step S103. On the other hand, if the time Δt has not elapsed, the control device 51 sets the result of the determination process in step S108 to No. In this case, the process advances to step S110.

If the result of the determination process in step S102 described above is No, the process advances to step S109.

Step S109 is a process of determining whether or not to stop the operation of the cooling device 10. When the control device 51 receives a signal to stop the operation of the cooling device 10, the control device 51 makes the determination result in step S109 Yes. In this case, the process of the flowchart shown in the figure ends. In other words, the driving of the cooling device 10 is stopped. On the other hand, when the control device 51 has not received the signal to stop the operation of the cooling device 10, the control device 51 sets the determination result in step S109 to No. In this case, the process returns to step S101. That is, in this case, the cooling device 10 is continuously driven and controlled by PID control.

If the result of the determination process in step S108 described above is No, the process advances to step S110.

Step S110 is a process of determining whether or not to stop the operation of the cooling device 10. When the control device 51 receives a signal to stop the operation of the cooling device 10, the control device 51 makes the determination result in step S110 Yes. In this case, the process of the flowchart shown in the figure ends. In other words, the driving of the cooling device 10 is stopped. On the other hand, when the control device 51 has not received the signal to stop the operation of the cooling device 10, the control device 51 sets the determination result of step S110 to No. In this case, the process returns to step S107. That is, in this case, the cooling device 10 continues to control the drive of the compressor 15 and each control valve using the input correction value.

In this way, in the cooling device, when the fluctuation in the cooling load is small (coefficient α≈1), the compressor and each control valve are controlled by PID control. On the other hand, when the fluctuation in the cooling load increases, the cooling device executes correction control. Note that the correction control is executed using a correction input value obtained by adding a correction value to the input value obtained by PID control. Since this correction control works to suppress fluctuations in cooling load, it is possible to perform stable temperature management through stable cooling in equipment that requires temperature accuracy, such as a thermostatic room.

Further, since the correction value obtained during the correction control uses the parameters used in the PID control, no new parameters are used, and no setting items are added in conjunction with the new parameters.

In this embodiment, the rotation speed of the compressor and the opening degree of each control valve are controlled by PID control in the control device, but these controls do not need to be limited to PID control, and can be controlled by PD control. It is also possible to do so.

In this embodiment, a cooling system is taken as an example, which has a refrigeration cycle in which a bypass path is provided in addition to a circulation path in which a compressor, a condenser, an expansion valve, an evaporator, and a pressure expansion valve are connected by piping. It is also possible to implement the present invention even in a refrigeration cycle in which the configuration of a bypass path is omitted.

10... Cooling device, 15... Compressor, 16... Condenser, 17... Expansion valve, 18... Evaporator, 19... Air blower, 20... Pressure expansion valve, 21... Bypass valve, 41, 42, 44, 45, 47, 48, 49, 50... Temperature sensor, 43, 46... Pressure sensor, 51... Control device

Claims (16)

A refrigeration cycle having a circuit in which a compressor, a condenser, an expansion valve, an evaporator, and a pressure regulating valve are sequentially connected using piping, and the air is cooled by heat exchange with the cooling medium in the evaporator. In a cooling device that uses a blower to send air into the target space,
The output ratio value of the compressor based on the pressure value of the refrigerant sucked into the compressor is determined in a proportional band, and the output ratio value of the compressor is determined using the determined output ratio value of the compressor as a proportional term. a first control means for PID control;
The expansion valve obtained by determining the opening value of the expansion valve based on the degree of superheat determined by the temperature of the cooling medium at the inlet side of the evaporator and the temperature of the cooling medium at the outlet side of the evaporator using a proportional band. a second control means for PID controlling the opening value of the expansion valve using the opening value as a proportional term;
The opening value of the pressure regulating valve based on the blowing temperature value at the outlet side of the evaporator of the air conveyed by the blower is determined using a proportional band, and the opening value of the pressure regulating valve thus determined is converted into a proportional term. third control means for PID controlling the opening value of the pressure regulating valve;
an air temperature output means capable of outputting respective output values of an evaporator inlet air temperature, an evaporator outlet air temperature, and an evaporator outlet air set temperature of the air conveyed by the blower;
The cooling load by the evaporator at a second time when a certain period of time has elapsed from the first time increases with respect to the cooling load by the evaporator calculated based on the output value from the air temperature output means at the first time. a determination unit that determines whether or not the
When the determination unit determines that the cooling load by the evaporator is increasing, the compressor The output ratio value, the opening value of the expansion valve, and the opening value of the pressure regulating valve are each corrected by feedforward, and the corrected control values are used to control the compressor, the expansion valve, and the pressure regulating valve. Correction control means that controls the valve and performs correction control to return the output ratio value and each opening value output to PID control again;
A cooling device characterized by having: The cooling device according to claim 1,
The determination unit determines a first determination value by multiplying the temperature change of the air on the upstream side of the evaporator by the temperature change of the air on the downstream side of the evaporator, and A cooling device characterized in that when the determination value is a positive value, it is determined that the cooling load by the evaporator is increasing. The cooling device according to claim 2,
The determination unit determines a second determination value by multiplying the temperature change of the air on the upstream side of the evaporator by the temperature of the air sent to the target space and the set temperature, and A cooling device characterized in that when the determination value is a positive value, it is determined that the cooling load by the evaporator is increasing. The cooling device according to any one of claims 1 to 3,
The output ratio value of the compressor, the opening value of the expansion valve, and the opening value of the pressure regulating valve are determined by applying a coefficient for each component to each of the proportional component of the deviation, the integral component of the deviation, and the differential component of the deviation. A cooling device characterized in that the cooling device is obtained by multiplying and integrating the values of each component multiplied by a coefficient for each component. The cooling device according to any one of claims 1 to 4,
In addition to the circulation path, the refrigeration cycle has a bypass path that branches from the piping between the compressor and the condenser and joins the piping between the condenser and the compressor,
a bypass valve disposed in the bypass passage;
The opening value of the bypass valve based on the pressure value of the cooling medium sucked into the compressor is determined using a proportional band, and the opening value of the bypass valve is set as a proportional term using the PID. a fourth control means for controlling;
has
The correction control means is configured to calculate a multiple of the cooling load by the evaporator at the second time with respect to the cooling load by the evaporator at the first time, when the determination unit determines that the cooling load by the evaporator is increasing. Based on this, the opening value of the bypass valve is corrected by feedforward, the corrected opening value is used to control the bypass valve, and the opening value output is again controlled to be corrected by returning to PID control. A cooling device characterized by: The cooling device according to claim 5,
The opening value of the bypass valve is determined by multiplying each of the proportional component of the deviation, the integral component of the deviation, and the differential component of the deviation by a coefficient for each component, and then integrating the values of each component multiplied by the coefficient for each component. A cooling device characterized by the following requirements. The cooling device according to claim 5 or 6,
a proportional band of the output ratio value of the compressor based on the pressure value of the cooling medium sucked into the compressor in the first control means; and a proportional band of the output ratio value of the compressor based on the pressure value of the cooling medium sucked into the compressor in the fourth control means. A cooling device characterized in that the slope of the control characteristic is opposite to the proportional band of the opening value of the bypass valve based on the pressure value of , and does not overlap in the pressure value of the cooling medium sucked into the compressor. The cooling device according to any one of claims 1 to 7,
The corrected control value is the product of the volume of air passing through the evaporator and the temperature of the air at the second time to the product of the volume and temperature of the air passing through the evaporator at the first time. A cooling device characterized in that the calculation is performed using a ratio of values. A refrigeration cycle having a circuit in which a compressor, a condenser, an expansion valve, an evaporator, and a pressure regulating valve are sequentially connected using piping, and the air is cooled by heat exchange with the cooling medium in the evaporator. In a method of controlling a cooling device that sends
The output ratio value of the compressor based on the pressure value of the refrigerant sucked into the compressor is determined in a proportional band, and the output ratio value of the compressor is determined using the determined output ratio value of the compressor as a proportional term. A first control step of PID control;
The expansion valve obtained by determining the opening value of the expansion valve based on the degree of superheat determined by the temperature of the cooling medium at the inlet side of the evaporator and the temperature of the cooling medium at the outlet side of the evaporator using a proportional band. a second control step of PID controlling the opening value of the expansion valve using the opening value as a proportional term ;
The opening value of the pressure regulating valve based on the blowing temperature value at the outlet side of the evaporator of the air conveyed by the blower is determined using a proportional band, and the opening value of the pressure regulating valve thus determined is converted into a proportional term. a third control step of PID controlling the opening value of the pressure regulating valve;
an air temperature output step capable of outputting respective output values of an evaporator inlet air temperature, an evaporator outlet air temperature, and an evaporator outlet air set temperature of the air conveyed by the blower ;
Is the cooling load by the evaporator at a second time when a certain period of time has elapsed from the first time increased with respect to the cooling load by the evaporator calculated based on the output value of the air temperature output step at the first time? a determination step of determining whether or not the
If it is determined in the determination step that the cooling load by the evaporator is increasing, the compressor is The output ratio value, the opening value of the expansion valve, and the opening value of the pressure regulating valve are each corrected by feedforward, and the corrected control values are used to control the compressor, the expansion valve, and the pressure regulating valve. A correction control step of controlling the valve and performing correction control to return the output ratio value and each opening value output to PID control again;
A method for controlling a cooling device, comprising: The method for controlling a cooling device according to claim 9,
In the determination step, a first determination value is obtained by multiplying the temperature change of the air on the upstream side of the evaporator by the temperature change of the air on the downstream side of the evaporator. A method for controlling a cooling device, characterized in that when the determination value is a positive value, it is determined that the cooling load by the evaporator is increasing. The method for controlling a cooling device according to claim 10,
In the determination step, a second determination value is obtained by multiplying the temperature change of the air on the upstream side of the evaporator, the temperature of the air sent to the target space, and the set temperature, and A method for controlling a cooling device, characterized in that when the determination value is a positive value, it is determined that the cooling load by the evaporator is increasing. The method for controlling a cooling device according to any one of claims 9 to 11,
The output ratio value of the compressor, the opening value of the expansion valve, and the opening value of the pressure regulating valve are determined by applying a coefficient for each component to each of the proportional component of the deviation, the integral component of the deviation, and the differential component of the deviation. A method for controlling a cooling device, characterized in that the value is obtained by multiplying and integrating the values of each component multiplied by a coefficient for each component. The method for controlling a cooling device according to any one of claims 9 to 12,
In addition to the circulation path, the refrigeration cycle includes a bypass path that branches off from the piping between the compressor and the condenser and joins the piping between the condenser and the compressor, and the bypass path. a bypass valve disposed in the passage;
The opening value of the bypass valve based on the pressure value of the cooling medium sucked into the compressor is determined using a proportional band, and the opening value of the bypass valve is set as a proportional term using the PID. further comprising a fourth control step for controlling,
If it is determined in the determination step that the cooling load by the evaporator is increasing, the bypass is performed based on the multiple of the cooling load by the evaporator at the second time with respect to the cooling load by the evaporator at the first time. Cooling characterized by correcting the opening value of the valve by feedforward, controlling the bypass valve using each corrected opening value, and performing correction control to return the opening value output to PID control again. How to control the device. The method for controlling a cooling device according to claim 13,
The opening value of the bypass valve is determined by multiplying each of the proportional component of the deviation, the integral component of the deviation, and the differential component of the deviation by a coefficient for each component, and then integrating the values of each component multiplied by the coefficient for each component. A method for controlling a cooling device characterized by: The method for controlling a cooling device according to claim 13 or 14,
a proportional band of the output ratio value of the compressor based on the pressure value of the cooling medium sucked into the compressor in the first control step; and a proportional band of the output ratio value of the compressor based on the pressure value of the cooling medium sucked into the compressor in the fourth control step. The proportional band of the opening value of the bypass valve based on the pressure value of the cooling device is characterized in that the slope of the control characteristic is opposite and does not overlap in the pressure value of the cooling medium sucked into the compressor . Control method . The method for controlling a cooling device according to any one of claims 9 to 15,
The corrected control value is the product of the volume of air passing through the evaporator and the temperature of the air at the second time to the product of the volume and temperature of the air passing through the evaporator at the first time. A method for controlling a cooling device, characterized in that calculation is performed using a ratio of values.