JP2008032250A - Method and device for controlling refrigerating air-conditioning system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of controlling a refrigerating air-conditioning system and its device for stably controlling the refrigerating air-conditioning system in quick response even when its operated condition is changed. <P>SOLUTION: The method includes a temperature detecting step of detecting a temperature in an outlet portion of an evaporator and a temperature of an inlet portion, a superheat degree calculating step of calculating a degree of superheat of the evaporator using a difference between the temperature in the outlet portion and the temperature in the inlet porion, a deviation calculating step of calculating a superheat degree deviation as a difference between an instructed degree of superheat and the calculated degree of superheat, a physical quantity detecting step of detecting physical quantity on a refrigerating cycle showing the operated condition of the refrigerating air-conditioning system, an operation point information generating step of generating operation point information which specifies the operation point of the refrigerating air-conditioning system using the physical quantity, a command value calculating step of calculating a command value for the opening of an expansion valve using the superheat degree deviation and the operation point information, and an opening control step of outputting the command value for the opening of the expansion valve and controlling the opening of the expansion valve so that the superheat degree deviation falls in a predetermined permissible range. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control method and a control device for a refrigeration air conditioner, and more specifically, a refrigeration cycle in which a compressor, a condenser, an expansion valve, and an evaporator are connected by a pipe and a refrigerant is circulated through the pipe. The present invention relates to a control method and a control device for an air conditioner.

  Conventionally, a refrigerating and air-conditioning apparatus having a refrigeration cycle in which a compressor, a condenser, an expansion valve, and an evaporator are connected by a pipe and a refrigerant is circulated through the pipe has been disclosed (see Patent Documents 1 and 2).

  In this type of refrigerating and air-conditioning apparatus, first, the refrigerant that has exited the evaporator and turned into a low-temperature and low-pressure gas is compressed by the compressor into a high-temperature and high-pressure gas. Next, the refrigerant that has become the high-temperature and high-pressure gas is deprived of heat by passing through the condenser and condensed to become a high-temperature and high-pressure liquid. Next, the refrigerant that has become a high-temperature and high-pressure liquid passes through an electronic expansion valve and expands and becomes a low-temperature and low-pressure liquid. The refrigerant that has become a low-temperature, low-pressure liquid enters the evaporator and enters a gas-liquid two-phase state in which saturated liquid and saturated vapor are mixed. The ratio of saturated vapor gradually increases as heat is absorbed from the surroundings as latent heat of vaporization. At a certain position, the ratio of saturated liquid becomes zero and all becomes saturated steam. This position is called the evaporation completion point. The temperature of the refrigerant basically does not change due to the latent heat of vaporization until the evaporation completion point. However, the heat absorbed in the subsequent positions contributes to the temperature rise of the saturated vapor, and the refrigerant becomes superheated vapor. The region after this evaporation completion point is called the superheated steam region, and the temperature rise of the refrigerant in the superheated steam region is called the superheat degree. Thereafter, the refrigerant that has become low-temperature and low-pressure superheated steam exits the evaporator, enters the compressor again, and repeats the above cycle. This cycle is called a refrigeration cycle.

  In the above refrigerating and air-conditioning apparatus, the role of the electronic expansion valve is to maintain the evaporation completion point near the outlet of the evaporator, so that the refrigerant enters the compressor while containing the saturated liquid and breaks the compressor. This is to prevent the phenomenon called liquid back and to effectively use the entire evaporator. The position of the evaporation completion point is related to the length of the superheated steam region, and the degree of superheat increases as the evaporation completion point moves away from the outlet of the evaporator. That is, the evaporator is maintained at an appropriate degree of superheat by adjusting the flow rate of the refrigerant by controlling the opening of the electronic expansion valve.

  The conventional control of the electronic expansion valve detects the temperature of the outlet portion of the evaporator and the temperature of the inlet portion or the central portion, and determines the difference between the detected temperature of the outlet portion and the temperature of the inlet portion or the central portion as the superheat degree. A control device that controls by PID control or fuzzy control using a deviation between the instructed superheat degree and the calculated superheat degree so that the calculated superheat degree matches the target superheat degree instructed from outside It is done by. The electronic expansion valve can freely adjust the opening according to the opening command of the valve output from the control device, and the opening command can be controlled by the control device with an arbitrary algorithm. Control with freely setting the control range of the flow rate is possible. Patent Document 2 discloses a method for adjusting the opening degree of an electronic expansion valve for controlling the degree of superheat to be close to zero in order to maximize the operation efficiency of the evaporator.

Japanese Examined Patent Publication No. 58-47628 Japanese Patent Laid-Open No. 9-303885

  However, in the conventional control device for a refrigeration air conditioner, the control response speed becomes slow when the ambient temperature of the refrigeration air conditioner changes or the operating state changes due to the defrosting operation of the refrigeration air conditioner. Or the control becomes unstable.

  The present invention has been made in view of the above, and provides a control method and a control apparatus for a refrigerating and air-conditioning apparatus that can be stably controlled at a fast response speed even if the operating state of the refrigerating and air-conditioning apparatus changes. Objective.

  In order to solve the above-described problems and achieve the object, a control method for a refrigerating and air-conditioning apparatus according to the present invention connects a compressor, a condenser, an expansion valve, and an evaporator with a pipe and circulates the refrigerant through the pipe. A method for controlling a refrigeration air conditioner constituting a refrigeration cycle, wherein a temperature detection step of detecting a temperature of an outlet portion and a temperature of an inlet portion of the evaporator, and a difference between the temperature of the outlet portion and the temperature of the inlet portion A superheat degree calculating step for calculating the superheat degree of the evaporator using a deviation, a deviation calculating step for calculating a superheat degree deviation which is a difference between the instructed superheat degree and the calculated superheat degree, and A physical quantity detecting step for detecting a physical quantity on a refrigeration cycle indicating an operating state; an operating point information generating step for generating operating point information for defining an operating point of the refrigeration air conditioner using the physical quantity; and the superheat degree deviation. in front A command value calculating step for calculating a command value for the opening degree of the expansion valve using the operating point information; and a command value for the opening degree is output to the expansion valve, and the superheat degree deviation is within a predetermined allowable range. And an opening degree control step for controlling the opening degree of the expansion valve so as to be accommodated.

  In addition, the control device for a refrigeration air conditioner according to the present invention is a control device for a refrigeration air conditioner that configures a refrigeration cycle in which a compressor, a condenser, an expansion valve, and an evaporator are connected by a pipe and a refrigerant is circulated through the pipe. And an outlet temperature detecting means for detecting the temperature of the outlet provided at the outlet of the evaporator; and an inlet temperature detecting means for detecting the temperature of the inlet provided at the inlet of the evaporator; A superheat degree calculating means connected to the outlet temperature detecting means and the inlet temperature detecting means for calculating the superheat degree of the evaporator using a difference between the temperature of the outlet portion and the temperature of the inlet portion, and Deviation calculating means connected to the superheat degree calculating means, inputting the instructed superheat degree, and calculating a superheat degree deviation which is a difference between the instructed superheat degree and the calculated superheat degree, and Detects physical quantities on the refrigeration cycle that indicate operating conditions Using the physical quantity, operating point information generating means for generating operating point information for defining the operating point of the refrigeration air conditioner, the expansion valve using the superheat degree deviation and the operating point information Opening degree calculation means for controlling the opening degree of the expansion valve so that the command value for the opening degree is calculated and output to the expansion valve, and the deviation degree of superheat is within a predetermined allowable range. Features.

  In the control device for a refrigerating and air-conditioning apparatus according to the present invention, in the above invention, at least one of the outlet temperature detecting means and the inlet temperature detecting means also serves as the physical quantity detecting means.

  In the control device for a refrigerating and air-conditioning apparatus according to the present invention, in the above invention, the physical quantity detecting means is provided between the outlet portion and the inlet portion provided between the outlet portion and the inlet portion of the evaporator. A plurality of temperature detecting means for detecting temperatures at a plurality of positions, wherein the operating point information generating means uses a combination of the temperature of the outlet portion of the evaporator, the temperature of the inlet portion, and the temperature of the plurality of positions. The operating point information is generated.

  In the control device for a refrigerating and air-conditioning apparatus according to the present invention as set forth in the invention described above, the operating point information generating means includes an average of the temperature of the outlet portion of the evaporator, the temperature of the inlet portion, and the temperature of the plurality of positions. The operating point information is generated using a value.

  In the refrigeration / air-conditioning apparatus control device according to the present invention as set forth in the invention described above, the physical quantity detection means is pressure detection means provided in a low-pressure portion of the refrigeration cycle.

  Further, in the control device for a refrigerating and air-conditioning apparatus according to the present invention, in the above invention, the opening calculation means calculates an initial command value for calculating an initial command value for the opening of the expansion valve using the superheat degree deviation. And a correction unit that calculates a correction parameter using the operating point information and corrects an initial command value for the opening to a command value for the opening using the correction parameter. .

  According to the present invention, since the command value for the opening degree of the expansion valve is calculated using not only the superheat deviation of the evaporator but also the operating point information of the refrigeration air conditioner, the operation state of the refrigeration air conditioner has changed. However, the opening degree of the expansion valve can be appropriately controlled according to the changed operating state. As a result, the degree of superheat of the evaporator quickly converges toward the instructed value, so that there is an effect that the refrigeration air conditioner can be stably controlled at a fast response speed.

  Embodiments of a control method and a control device for a refrigeration air-conditioning apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a refrigerating and air-conditioning apparatus including a control device according to Embodiment 1 of the present invention. FIG. 2 is a control block diagram of the control device shown in FIG. As shown in FIGS. 1 and 2, the control device 10 a connects the compressor 2, the condenser 3, the electromagnetic valve 4, the electronic expansion valve 5, and the evaporator 6 through a pipe 13 and circulates a refrigerant through the pipe 13. This is provided in the refrigeration air conditioner 1a constituting the same refrigeration cycle as in the prior art. The control device 10a includes a temperature sensor 9 as outlet temperature detecting means for detecting θo, which is the temperature of the outlet provided at the outlet of the evaporator 6, and an inlet provided at the inlet of the evaporator 6. A temperature sensor 8 as an inlet temperature detecting means for detecting θi, which is the temperature of the temperature, and a controller 7a.

The controller 7a includes a subtractor 71 as superheat degree calculation means, a subtracter 72 as superheat degree deviation calculation means, an operating point information generation section 73a, and an opening degree calculation section 74. The subtractor 71 is connected to the temperature sensors 8 and 9 and calculates θ _SH = θo−θi, which is the degree of superheat of the evaporator 6, using the difference between the outlet temperature θo and the inlet temperature θi. Originally, the superheat degree of the evaporator 6 is an increase in the temperature of the refrigerant in the superheated steam region, but the temperature θi at the inlet of the evaporator 6 is substantially equal to the temperature at the completion point of evaporation, so θ _SH = θo−θi. As good as

The subtractor 72 is connected to the subtractor 71 and inputs the instructed target superheat degree θ _SHr to input the difference between the target superheat degree θ _SHr and the calculated superheat degree θ _SH , that is, the superheat degree deviation θ _SHe = θ _SHr −θ _SH is calculated. The target superheat degree θ _SHr is instructed from the main controller of the refrigeration air conditioner according to, for example, the temperature of the refrigeration air conditioner set by the user.

  The operating point information generator 73a generates operating point information that defines the operating point of the refrigeration air conditioner 1a using the temperature θi at the inlet of the evaporator 6. The operating point information is information that defines the operating point of the refrigeration air conditioner 1a. For example, the operating point information is the temperature θi of the inlet portion itself, but is not particularly limited as long as it is information that defines the operating point of the refrigeration air conditioner 1a. In the first embodiment, the operating point information generating unit 73a uses the temperature θi at the inlet of the evaporator 6 to generate operating point information, but the temperature θi indicates the operating state of the refrigeration air conditioner 1a. It is a physical quantity on the refrigeration cycle shown. The temperature sensor 8 also serves as physical quantity detection means for detecting a physical quantity.

The opening degree calculation unit 74 calculates a command value ν for the opening degree of the electronic expansion valve 5 using the superheat degree deviation θ _SHe and the operating point information, and outputs the command value ν to the electronic expansion valve 5, and the superheat degree deviation θ _SHe is predetermined. The degree of opening of the electronic expansion valve 5 is controlled so as to be within the permissible range. The opening calculation unit 74 calculates a command value for the opening of the electronic expansion valve 5 using not only the superheat degree deviation θ _SHe of the evaporator 6 but also the operating point information of the refrigeration air conditioner 1a. An appropriate command value can be calculated according to changes in the operating state.

  Next, a control method for the refrigerating and air-conditioning apparatus will be described with reference to a control block diagram of the control apparatus shown in FIG.

First, the temperature sensors 9, 8 detect the temperature θo at the outlet of the evaporator 6 and the temperature θi at the inlet, and output them to the controller 7a. Next, in the controller 7 a, the subtractor 71 receives the outlet temperature θo and the inlet temperature θi, calculates the superheat degree of the evaporator 6, which is θ _SH = θo−θi, and sends it to the subtractor 72. Output. Next, the subtractor 72 receives the target superheat degree θ _SHr instructed from the main controller of the refrigeration air conditioner 1a and the like, and also receives the superheat degree θ _SH calculated by the subtractor 71, and θ _SHe = superheat degree deviation. θ _SHr −θ _SH is calculated and output to the opening calculation unit 74.

  On the other hand, the temperature θi at the inlet of the evaporator 6 detected by the temperature sensor 8 is also input to the operating point information generator 73a. The operating point information generating unit 73a generates operating point information of the refrigerating and air-conditioning apparatus 1a using the received temperature θi and outputs the operating point information to the opening degree calculating unit 74.

Next, the opening degree calculation unit 74 calculates a command value ν for the opening degree of the electronic expansion valve 5 using the superheat degree deviation θ _SHe and the operating point information. Since this command value ν is calculated using not only the superheat degree deviation θ _SHe but also the operating point information, it is an appropriate command value according to the change in the operating state of the refrigeration air conditioner 1a. Then, the opening degree calculation unit 74 outputs a command value ν for the opening degree to the electronic expansion valve 5 and controls the opening degree of the electronic expansion valve 5 so that the superheat degree deviation θ _SHe falls within a predetermined allowable range. As described above, since the opening degree of the electronic expansion valve 5 is feedback-controlled by the command value ν calculated using not only the superheat degree deviation θ _SHe but also the operating point information, the superheat degree of the evaporator 6 is set to the indicated value. Converge quickly toward. As a result, the refrigeration air conditioner can be controlled stably with a fast response speed. Note that PID control, fuzzy control, or the like can be used for the feedback control. In addition, the allowable range is, for example, ± of the target superheat degree θ _SHr so as to realize a desired control response speed and stability in accordance with the operating state of the refrigeration air conditioner 1a, the calculated superheat degree deviation θ _SHe, and the like. The range is about 1 to 5%.

Next, the first embodiment will be described more specifically with reference to FIGS. When the ambient temperature is different, the refrigeration air conditioner 1a operates at different operating points even if the calculated superheat degree of the evaporator 6 is the same. When the operating points are different, the relationship between the superheat degree deviation and the command value for the opening degree of the electronic expansion valve is different due to the non-linearity of the refrigeration cycle, so that the optimum control law is different. For example, as shown in FIG. 3, when the operating state is at the operating point A, the relationship between the superheat degree deviation and the command value is represented by the control law indicated by the curve L1, and when the operating state is at the operating point B, the overheating is performed. It is assumed that the relationship between the degree deviation and the command value is expressed by a control law indicated by the curve L2. When the operating state is the operating point A or B, the temperature at the inlet of the evaporator 6 is assumed to be θiA or θiB. In the first embodiment, the operating point information generating unit 73a determines whether the operating point is the operating point A or the operating point B depending on whether the temperature of the inlet is θiA or θiB. Information is generated and output to the opening calculation unit 74. The opening calculation unit 74 selects the control law indicated by the curve L1 or L2 based on the received operating point information, and when the received superheat degree deviation is θ _SHe 1, the opening degree calculation unit 74 uses the selected control law as a command value. ν _A or ν _B is calculated. That is, as shown in FIG. 4, the opening degree calculation unit 74 calculates the command value ν _A or ν _B using the superheat degree deviation θ _SHe 1 and the operating point information A or B and outputs it to the electronic expansion valve 5. Therefore, the electronic expansion valve 5 can be controlled based on the optimal control law according to the operating state.

As described above, the control device 10a of the refrigerating and air-conditioning apparatus according to the first embodiment includes the refrigerating and air-conditioning apparatus 1a generated using not only the superheat degree deviation θ _SHe but also the temperature θi of the inlet portion of the evaporator 6. Since the command value ν for the opening degree of the electronic expansion valve 5 is also calculated using the operating point information, even if the operating state of the refrigeration air conditioner 1a is changed, the electronic expansion valve 5 is changed according to the changed operating state. The opening degree can be appropriately controlled. As a result, quickly converged toward the degree of superheat theta _SH is instructed target superheating degree theta _SHr of the evaporator 6 can be stably controlled refrigerating and air-conditioning apparatus 1a at a fast response speed. Further, the control unit 10a, even when changing the target superheat degree theta _SHr, quickly converged toward the degree of superheat theta _SH is instructed target superheating degree theta _SHr of the evaporator 6, stable at a high response speed Thus, the refrigeration air conditioner 1a can be controlled. Furthermore, since the degree of superheat θ _SH can be stably controlled to a low value, the utilization efficiency of the evaporator 6 can be stably increased, and the effect of saving energy of the refrigeration air conditioner 1a can be achieved.

(Embodiment 2)
Next, a control device for a refrigerating and air-conditioning apparatus according to Embodiment 2 of the present invention will be described. In the control device for the refrigerating and air-conditioning apparatus according to Embodiment 2, the operating point information generating unit generates the operating point information of the refrigerating and air-conditioning apparatus using the temperature at the outlet of the evaporator.

  FIG. 5 is a control block diagram of the control device for the refrigerating and air-conditioning apparatus according to the second embodiment. The refrigerating and air-conditioning apparatus control device 10b is provided in the refrigerating and air-conditioning apparatus 1a and has the same configuration as that of the refrigerating and air-conditioning apparatus control device 10a. However, the controller 7b replaces the operating point information generating unit 73a with operating points. An information generation unit 73b is provided. The operating point information generating unit 73b generates operating point information that defines the operating point of the refrigeration air conditioner using the temperature θo at the outlet of the evaporator 6. The operating point information is, for example, the temperature θo at the outlet, but is not particularly limited. In the second embodiment, the temperature θo at the outlet of the evaporator 6 is used as a physical quantity for the operating point information generation unit 73b to generate the operating point information, and the temperature sensor 9 detects the physical quantity. It also serves as a detection means.

Similarly to the control device 10a of the refrigeration air conditioner, the control device 10b of the refrigeration air conditioner _uses not only the superheat degree deviation θ _SHe but also the operating point information of the refrigeration air conditioner 1a to provide a command value ν for the opening degree of the electronic expansion valve 5. Therefore, even when the operating state of the refrigeration air conditioner 1a changes, the opening degree of the electronic expansion valve 5 can be appropriately controlled according to the changed operating state. As a result, quickly converged toward the degree of superheat theta _SH is instructed target superheating degree theta _SHr of the evaporator 6 can be stably controlled refrigerating and air-conditioning apparatus 1a at a fast response speed.

(Embodiment 3)
Next, a control device for a refrigerating and air-conditioning apparatus according to Embodiment 3 of the present invention will be described. In the control device for the refrigerating and air-conditioning apparatus according to Embodiment 3, the physical quantity detection means detects temperatures at a plurality of positions between the outlet portion and the inlet portion provided between the outlet portion and the inlet portion of the evaporator. A plurality of temperature detecting means, and the operating point information generating means generates operating point information using a combination of the temperature at the outlet of the evaporator, the temperature at the inlet, and the temperatures at the plurality of positions.

  FIG. 6 is a control block diagram of the control device of the refrigerating and air-conditioning apparatus according to Embodiment 3. The refrigerating and air-conditioning apparatus control device 10 c is provided in the refrigerating and air-conditioning apparatus 1 a, but is a temperature sensor 11-1 to 11-11 as a plurality of temperature detecting means provided between the outlet and the inlet of the evaporator 6. -N and the controller 7c includes an operating point information generation unit 73c.

  The temperature sensors 11-1 to 11-n are physical quantity detection means for detecting temperatures θ1 to θn, which are physical quantities on the refrigeration cycle indicating the operating state of the refrigeration air conditioner 1a. Then, the operating point information generating unit 73c generates operating point information of the refrigerating and air-conditioning apparatus 1a using a combination of the temperature θo at the outlet of the evaporator 6, the temperature θi at the inlet, and the temperatures θ1 to θn.

FIG. 7 is an explanatory diagram for explaining an example of positions where the temperature sensors 11-1 to 11-n are attached. As shown in FIG. 7, the temperature sensors 11-1 to 11-n are attached to positions separated from each other in an evaporation pipe 61 in which a refrigerant provided in the evaporator 6 circulates. As a result, the temperature distribution of the refrigerant in the evaporator 6 can be detected by the combination of the outlet temperature θo, the inlet temperature θi, and the temperatures θ1 to θn. Therefore, the operating point information generated by the operating point information generating unit 73c using the combination of these temperatures is more accurate reflecting the temperature distribution of the refrigerant in the evaporator 6. As a result, the opening degree control unit 74 calculates a command value ν for the opening degree of the electronic expansion valve 5 using the superheat degree deviation θ _SHe and the above operating point information, and outputs the command value ν to the electronic expansion valve 5 to output it. By controlling the opening degree of 5, a more appropriate opening degree can be controlled. Note that the operation information generated using the combination of temperatures is, for example, the combination of temperatures itself, but is not particularly limited.

  As a modification of the third embodiment, the operating point information generation unit 73c uses (θo + θi + θ1 +... + Θn) / (n + 2), which is the average value of the temperatures θo, θi, and θ1 to θn. You may produce | generate the operating point information of the refrigeration air conditioner 1a. In this case, the operating point information generating unit 73c receives the temperatures θo, θi, and θ1 to θn, calculates (θo + θi + θ1 +... + Θn) / (n + 2), and generates operating point information by using it. Further, a low-pass filter may be provided in the operating point information generation unit 73c, and moving average processing, first-order lag processing, and the like may be performed when calculating the above average value.

(Embodiment 4)
Next, a control device for a refrigerating and air-conditioning apparatus according to Embodiment 4 of the present invention will be described. The control device for the refrigerating and air-conditioning apparatus according to Embodiment 4 is different from the control apparatus for the refrigerating and air-conditioning apparatus according to Embodiments 1 to 3 described above. It is.

  FIG. 8 is a block diagram illustrating an example of a configuration of a refrigerating and air-conditioning apparatus including the control device according to the fourth embodiment. FIG. 9 is a control block diagram of the control device shown in FIG. As shown in FIGS. 8 and 9, the control device 10 d is provided in a refrigeration air conditioner 1 b having the same configuration as the refrigeration air conditioner 1 a according to the first embodiment. The control device 10d includes a temperature sensor 9 provided at the outlet of the evaporator 6, a temperature sensor 8 provided at the inlet of the evaporator 6, an outlet of the electronic expansion valve 5, and an inlet of the evaporator 6. The pressure sensor 12 which is a pressure detection means provided in the predetermined position of the piping 13 between and the controller 7d is provided. Moreover, the controller 7d includes an operating point information generation unit 73d. The low pressure part of the refrigeration cycle of the refrigeration air conditioner 1b is a part between the outlet of the electronic expansion valve 5 and the inlet of the compressor 2, and the pressure sensor 12 is the refrigeration cycle of the refrigeration air conditioner 1b. It is provided in the low pressure part.

  The pressure sensor 12 is a physical quantity detection means for detecting the pressure P of the refrigerant in the low-pressure part, which is a physical quantity on the refrigeration cycle indicating the operating state of the refrigeration air conditioner 1b. And the operating point information production | generation part 73d produces | generates the operating point information of the refrigeration air conditioner 1b using the pressure P. FIG. Here, the temperature at the inlet of the evaporator 6 is an approximation of the evaporation temperature of the refrigerant, and the evaporation temperature of the refrigerant is determined by the pressure of the refrigerant in the low-pressure part of the refrigeration cycle. Therefore, the pressure P has a predetermined relationship with the temperature of the inlet portion of the evaporator 6. As a result, the control device 10d can perform the same control as the control device 10a according to the first embodiment that generates the operating point information using the temperature θi at the inlet of the evaporator 6. Further, the pressure sensor 12 can be installed at a predetermined position of the pipe 13 between the outlet of the evaporator 6 and the inlet of the compressor 2. The detected pressure value in this case is a value reflecting the effect of pressure loss in the evaporator 6 and the pipe 13.

  In the first to fourth embodiments, the opening calculation unit calculates the initial command value for the opening of the electronic expansion valve using the superheat degree deviation and calculates the correction parameter using the operating point information. The correction parameter can be used to correct the initial command value for the opening to the command value for the opening.

FIG. 10 is a block diagram showing an example of the configuration of the combination of the opening degree calculation unit and the operating point information generation unit. The opening degree calculation unit 75 is connected to an operating point information generation unit 73a that generates operating point information of the refrigeration air conditioner using the temperature θi of the inlet of the evaporator provided in the refrigeration air conditioner. A correction parameter is calculated using an initial command value calculation unit 751 that calculates an initial command value ν ₀ for the opening of the electronic expansion valve using the deviation θ _SHe , and operating point information output from the operating point information generation unit 73a, A correction unit 752 that corrects the initial command value ν ₀ for the opening to the command value ν for the opening using the correction parameter is provided. The correction parameter is a correction parameter for the proportional gain when the control device performs PID control, for example.

  The configuration shown in FIG. 10 adds an operating point information generation unit and a correction unit to the opening calculation unit provided in the control device of the existing refrigeration air conditioner that controls the opening of the electronic expansion valve only by the superheat degree deviation. Therefore, the existing control device for the refrigeration air conditioner can be easily upgraded to the control device for the refrigeration air conditioner according to the present invention.

It is a block diagram which shows the structure of the refrigerating air conditioning apparatus provided with the control apparatus which concerns on Embodiment 1 of this invention. It is a control block diagram of the control apparatus shown in FIG. It is explanatory drawing which demonstrates Embodiment 1 of this invention more concretely. It is explanatory drawing which demonstrates Embodiment 1 of this invention more concretely. It is a control block diagram of the control apparatus of the refrigeration air conditioning apparatus which concerns on Embodiment 2 of this invention. It is a control block diagram of the control apparatus of the refrigeration air conditioning apparatus which concerns on Embodiment 3 of this invention. It is explanatory drawing explaining an example of the position which attaches a temperature sensor in Embodiment 3 of this invention. It is a block diagram which shows an example of a structure of the refrigerating air conditioning apparatus provided with the control apparatus which concerns on Embodiment 4 of this invention. It is a control block diagram of the control apparatus shown in FIG. It is a block diagram which shows an example of a structure of the combination of an opening calculating part and an operating point information generation part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b Refrigeration air conditioner 10a-10d Control apparatus of refrigeration air conditioner 2 Compressor 3 Condenser 4 Electromagnetic valve 5 Electronic expansion valve 6 Evaporator 61 Evaporating pipe 7a-7d Controller 71, 72 Subtractor 73a-73d Operating point information Generation unit 74, 75 Opening calculation unit 751 Initial command value calculation unit 752 Correction unit 8, 9, 11-1 to 11-n Temperature sensor 12 Pressure sensor 13 Piping

Claims (7)

A control method for a refrigeration air conditioner comprising a refrigeration cycle in which a compressor, a condenser, an expansion valve, and an evaporator are connected by piping and a refrigerant is circulated through the piping,
A temperature detecting step for detecting the temperature of the outlet portion of the evaporator and the temperature of the inlet portion;
A superheat degree calculating step of calculating a superheat degree of the evaporator using a difference between the temperature of the outlet portion and the temperature of the inlet portion;
A deviation calculating step for calculating a superheat degree deviation which is a difference between the instructed superheat degree and the calculated superheat degree;
A physical quantity detection step of detecting a physical quantity on a refrigeration cycle indicating an operating state of the refrigeration air conditioner;
An operating point information generating step for generating operating point information that defines an operating point of the refrigeration air conditioner using the physical quantity;
A command value calculating step for calculating a command value for the opening of the expansion valve using the superheat degree deviation and the operating point information;
An opening degree control step for outputting a command value for the opening degree to the expansion valve, and controlling the opening degree of the expansion valve so that the superheat deviation is within a predetermined allowable range;
The control method of the refrigerating air-conditioning apparatus characterized by including. A control device for a refrigerating and air-conditioning apparatus comprising a refrigeration cycle in which a compressor, a condenser, an expansion valve, and an evaporator are connected by piping and a refrigerant is circulated through the piping,
Outlet part temperature detection means for detecting the temperature of the outlet part provided at the outlet part of the evaporator;
An inlet temperature detecting means for detecting the temperature of the inlet provided at the inlet of the evaporator;
A superheat degree calculating means connected to the outlet temperature detecting means and the inlet temperature detecting means to calculate the superheat degree of the evaporator using a difference between the temperature of the outlet portion and the temperature of the inlet portion;
Deviation calculating means connected to the superheat degree calculating means, inputting the instructed superheat degree, and calculating a superheat degree deviation which is a difference between the instructed superheat degree and the calculated superheat degree;
Physical quantity detection means for detecting a physical quantity on a refrigeration cycle indicating the operating state of the refrigeration air conditioner;
Operating point information generating means for generating operating point information that defines the operating point of the refrigeration air conditioner using the physical quantity;
Using the superheat degree deviation and the operating point information, a command value for the opening of the expansion valve is calculated and output to the expansion valve, and the expansion valve is adjusted so that the superheat degree deviation falls within a predetermined allowable range. Opening calculation means for controlling the opening of
A control device for a refrigerating and air-conditioning apparatus, comprising:   The control device for a refrigerating and air-conditioning apparatus according to claim 2, wherein at least one of the outlet temperature detecting means or the inlet temperature detecting means also serves as the physical quantity detecting means. The physical quantity detection means is a plurality of temperature detection means for detecting temperatures at a plurality of positions between the outlet portion and the inlet portion provided between the outlet portion and the inlet portion of the evaporator,
The operating point information generating means generates the operating point information using a combination of an outlet temperature of the evaporator, an inlet temperature, and temperatures of the plurality of positions. The control apparatus of refrigerating air-conditioning apparatus of description.   5. The operating point information generating means generates the operating point information using an average value of an outlet temperature of the evaporator, an inlet temperature, and temperatures of the plurality of positions. The control apparatus of the refrigerating air-conditioning apparatus described in 1.   The control apparatus for a refrigerating and air-conditioning apparatus according to claim 2, wherein the physical quantity detection means is pressure detection means provided in a low-pressure part of a refrigeration cycle. The opening degree calculation means is
An initial command value calculation unit that calculates an initial command value for the opening of the expansion valve using the superheat degree deviation;
A correction unit that calculates a correction parameter using the operating point information, and corrects an initial command value for the opening to a command value for the opening using the correction parameter;
The control device for a refrigerating and air-conditioning apparatus according to any one of claims 2 to 6, further comprising:

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