CN111263872A

CN111263872A - Control device and control method for air extractor

Info

Publication number: CN111263872A
Application number: CN201880068580.4A
Authority: CN
Inventors: 结城启之; 上田宪治; 栂野良枝; 和岛一喜
Original assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Current assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Priority date: 2017-10-25
Filing date: 2018-10-12
Publication date: 2020-06-09
Also published as: US20200340722A1; JP2019078482A; JP6971776B2; WO2019082702A1

Abstract

The invention aims to provide a control device of an air extraction device, which can estimate the total amount of air invasion with higher precision and optimize the operation of the air extraction device. A control device (7) for controlling an air extraction device (6) provided in a refrigerator (1), comprising: an estimation unit that estimates the total amount of air entering the refrigerator (1); a determination unit that determines whether or not the total amount of air intrusion is equal to or greater than a preset allowable value; a start control unit that determines the start-up duration of the air extraction device (6) on the basis of the total amount of air intrusion when the total amount of air intrusion is equal to or greater than an allowable value, and starts up the air extraction device (6) only for the start-up duration; a discharged air amount calculation unit that calculates a discharged air amount, which is an amount of air actually discharged by the air extractor (6); and a correcting unit for correcting at least one of the total amount of air intrusion and the start-up duration when the difference between the total amount of air intrusion and the amount of discharged air is equal to or greater than a predetermined amount.

Description

Control device and control method for air extractor

Technical Field

The invention relates to a refrigerator, in particular to a control device and a control method of an air extraction device.

Background

In a refrigerator using a low-pressure refrigerant, a negative pressure may be generated in the refrigerator depending on an operation condition, and therefore, particularly when the sealing property is deteriorated, there is a possibility that a noncondensable gas (mainly air) enters the refrigerator and stays in a condenser or the like. In this state, the condensing pressure may be increased due to non-condensation of the gas, and the condenser may not operate normally. Therefore, conventionally, the noncondensable gas introduced into the apparatus is discharged to the atmosphere by an air extractor.

Low pressure refrigerants, i.e., low GWP refrigerants, are required to be used in refrigerators according to the correction of the method of recovering and destroying freon, the european union greenhouse gas fluoride regulation, and the like. However, low GWP refrigerants are susceptible to decomposition by oxygen and may generate byproducts that affect stable operation of the refrigerator. In a refrigerator using a low GWP refrigerant, when intrusion of non-condensable gas is caused, there is a possibility that the low GWP refrigerant is decomposed and the operation of the refrigerator becomes unstable. Therefore, in order to maintain stable operation in a refrigerator using a low GWP refrigerant, it is necessary to estimate the amount of noncondensable gas (total amount of air entering) in the refrigerator with high accuracy and to appropriately extract the noncondensable gas.

Patent document 1 discloses that the total amount of air entering the refrigerator is estimated based on the structure and pressure state of the refrigerator, and the activation of the air extraction device is controlled based on the estimated total amount of air entering.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-65673

Disclosure of Invention

Technical problem to be solved by the invention

However, since the total amount of air intrusion varies depending on various conditions such as humidity and outside air temperature, it is difficult to estimate the total amount of air intrusion with high accuracy. Therefore, even in a situation where the possibility of intrusion of the non-condensation gas is low, the amount of intrusion of air is estimated to be large, and the air extracting device may be unnecessarily operated.

The present invention has been made in view of such circumstances, and an object thereof is to provide a control device and a control method for an air extraction device, which can estimate the total amount of air intrusion with higher accuracy and optimize the operation of the air extraction device more.

Means for solving the technical problem

The 1 st aspect of the present invention is a control device for controlling an air-extracting device provided in a refrigerator, the control device including: an estimation unit that estimates a total amount of air entering the refrigerator; a determination unit that determines whether or not the total amount of air intrusion is equal to or greater than a preset allowable value; a start control unit that determines a start-up duration of the air extraction device based on the total amount of air intrusion when the total amount of air intrusion is equal to or greater than the allowable value, and starts up the air extraction device only for the start-up duration; a discharged air amount calculation unit that calculates a discharged air amount, which is an amount of air actually discharged by the air extractor; and a correcting unit that corrects at least one of the total amount of air intrusion and the activation duration when a difference between the total amount of air intrusion and the discharge air amount is equal to or greater than a predetermined amount.

According to the above configuration, the total amount of air intrusion can be corrected with higher accuracy in accordance with the actual operating condition of the refrigerator by calculating the amount of exhaust air, which is the amount of air actually extracted, and correcting at least one of the total amount of air intrusion and the activation duration of the air extracting device using the amount of exhaust air. Since the duration of the activation of the air extraction device is determined based on the total amount of air intrusion, the total amount of air intrusion is indirectly corrected even when the duration of the activation is corrected. That is, the total amount of air intrusion according to the operating condition can be estimated with higher accuracy. For example, even when a low GWP refrigerant is used as the refrigerant of the refrigerator, the total amount of air intrusion can be estimated with higher accuracy, and therefore, more stable operation can be maintained.

In the control device, the correction unit may correct at least one of the total amount of air intrusion and the activation duration by multiplying a correction constant corresponding to a difference between the total amount of air intrusion estimated by the estimation unit and the amount of exhaust air.

According to the above configuration, when the difference between the estimated total amount of air intrusion and the actual discharge air amount is large, the correction can be performed by a simple calculation of multiplying the air intrusion amount and/or the activation duration time by the correction constant. Therefore, correction can be performed without imposing a processing load.

In the above control device, the correction constant may be a value obtained by dividing the discharged air amount by the total amount of air intrusion.

According to the above configuration, since the correction can be performed by a simple calculation, the correction can be performed without imposing a processing load.

In the control device, the refrigerator may be divided into a plurality of sections, an air intrusion influence degree may be set for each of the sections, the estimating unit may estimate an air intrusion amount for each of the sections, the total amount of air intrusion in the entire refrigerator may be estimated from the estimated air intrusion amount for each of the sections, and the correcting unit may correct the air intrusion amount for each of the sections based on the air intrusion influence degree when correcting the total amount of air intrusion.

According to the above configuration, the air intrusion amount can be corrected for each section according to the influence of air intrusion, and therefore, more accurate correction can be performed according to the operating state of the refrigerator and the configuration in each section. Since the sections are different in structure in the number of joints, the susceptibility to air intrusion (the influence of air intrusion) is different. Therefore, by performing the correction according to the influence of air intrusion, the amount of air intrusion in the section where air easily intrudes can be effectively corrected. Therefore, the total amount of air intrusion can be estimated with higher accuracy.

The invention according to claim 2 is a refrigerator using a low-pressure low-GWP refrigerant, and includes an air-extracting device and the control device.

A 3 rd aspect of the present invention is a method for controlling an air-extracting device provided in a refrigerator, the method including: an estimation step of estimating a total amount of air entering the refrigerator; a determination step of determining whether or not the total amount of air intrusion is equal to or greater than a preset allowable value; a start control step of determining a start-up duration of the air extraction device based on the total amount of air intrusion when the total amount of air intrusion is equal to or greater than the allowable value, and starting up the air extraction device only for the start-up duration; an exhaust air amount calculation step of calculating an exhaust air amount which is an amount of air actually exhausted by the air exhauster; and correcting at least one of the total amount of air intrusion and the activation duration when a difference between the total amount of air intrusion and the discharge air amount is a predetermined amount or more.

Effects of the invention

According to the present invention, the total amount of air intrusion can be estimated with higher accuracy, and the operation of the air extraction device can be optimized.

Drawings

Fig. 1 is a diagram showing a schematic configuration of a refrigerator according to embodiment 1 of the present invention.

Fig. 2 is a diagram showing functional blocks of the control device according to embodiment 1 of the present invention.

Fig. 3 is a flowchart showing a method for controlling the air extractor according to embodiment 1 of the present invention.

Fig. 4 is a flowchart illustrating a method of calculating the amount of exhaust air performed by the control device according to embodiment 1 of the present invention.

Fig. 5 is a flowchart showing a correction method executed by the control device according to embodiment 1 of the present invention.

Fig. 6 is a diagram showing the amount of noncondensable gas in the condenser of the refrigerator according to embodiment 1 of the present invention.

Fig. 7 is a diagram showing the amount of noncondensable gas in the air extractor of the refrigerator according to embodiment 1 of the present invention.

Detailed Description

[ 1 st embodiment ]

Hereinafter, embodiment 1 of a control device and a control method for an air extractor according to the present invention will be described with reference to the drawings.

Fig. 1 is a diagram showing a schematic configuration of a refrigerator 1 according to embodiment 1 of the present invention. As shown in fig. 1, the refrigerator 1 according to the present embodiment is a compression-type refrigerator, and includes, as main components, a compressor 2 that compresses a refrigerant, a condenser 3 that condenses a high-temperature and high-pressure gas refrigerant compressed by the compressor 2, an expansion valve 4 that expands a liquid refrigerant from the condenser 3, an evaporator 5 that evaporates the liquid refrigerant expanded by the expansion valve 4, an air-extracting device 6 that discharges non-condensed gas (mainly air) that has entered the refrigerator 1 into the atmosphere, and a control device 7 that controls each unit included in the refrigerator 1.

As the refrigerant, a low-pressure refrigerant, i.e., a low GWP refrigerant is used. The air-extracting device 6 according to the present embodiment can estimate the amount of noncondensable gas entering the machine with high accuracy by performing the calibration described below, and therefore can use various refrigerants without being limited to low GWP refrigerants.

The compressor 2 is, for example, a multistage centrifugal compressor driven by a constant speed motor or a variable speed motor. The air-extracting device 6 is connected to the condenser 3 via a pipe 8, and the refrigerant gas (including the noncondensable gas) from the condenser 3 is guided to an air-extracting tank 16 in the air-extracting device 6 via the pipe 8. The pipe 8 is provided with a valve 9 and a check valve 10 for controlling the flow and the shutoff of the refrigerant gas. The control device 7 controls the opening and closing of the valve 9 to control the starting and stopping of the air-extracting device 6. The check valve 10 prevents the refrigerant gas (including the non-condensable gas) from flowing backward from the gas suction tank 16 in the gas suction device 6 to the condenser 3.

The air-extracting device 6 includes, for example, an air-extracting tank 16 that cools and condenses the refrigerant gas (including the noncondensable gas) supplied through the pipe 8 by the peltier element and separates the refrigerant gas from the noncondensable gas, and a pump 11 that extracts the noncondensable gas stored in the air-extracting tank 16 into the atmosphere. In the evacuation tank 16, the noncondensable gas is discharged to the atmosphere, and the refrigerant gas separated from the noncondensable gas by controlling the valve 12 is returned to the evaporator 5 through the pipe 13. The configuration of the air extractor 6 is an example, and is not limited to this configuration. The cooling method for condensing the refrigerant gas in the extraction tank 16 is also exemplified by cooling using a peltier element, and is not limited to this configuration.

The evacuation tank 16 of the evacuation device 6 is provided with a pressure sensor 14 and a temperature sensor 15 for monitoring the state of the noncondensable gas stored therein (the presence or absence of the noncondensable gas, the storage amount, and the like). The measured values of these sensors are sent to the control device 7 and used for the control of the suction device 6.

The configuration of the refrigerator 1 shown in fig. 1 is an example, and is not limited to this configuration. For example, an air heat exchanger may be disposed in place of the condenser 3, and heat may be exchanged between the cooled outside air and the refrigerant. The refrigerator 1 is not limited to a case of having only a cooling function, and may have only a heating function, or both a cooling function and a heating function, for example.

The control device 7 has a function of controlling the compressor 2 and a function of controlling the air-extracting device 6 based on the measurement values received from the sensors and the load factor transmitted from the upper system.

The control device 7 includes memories such as a CPU (central processing unit) and a RAM (Random Access Memory), and a computer-readable recording medium, which are not shown. The procedure of a series of processes for realizing various functions described later is recorded in a recording medium or the like in the form of a program, and the program is read out to a RAM or the like by a CPU to execute processing and arithmetic processing of information, thereby realizing various functions described later.

Fig. 2 is a functional block diagram showing a control function of the air extractor 6 among functions provided in the extraction control device 7. As shown in fig. 2, the control device 7 includes an estimation unit 21, a determination unit 22, a start control unit 23, a storage unit 24, a discharged air amount calculation unit 25, and a correction unit 26.

The estimating unit 21 estimates the total amount of air intrusion using the influence of air intrusion indicating the ease of air intrusion specified by the structural surface of the refrigerator 1 and a function including the pressure as a parameter.

The air intrusion influence degree is an index indicating a degree of a gap where air (oxygen) may intrude into the refrigerator 1, for example, and is stored in the storage unit 24 in advance. The influence of air intrusion is determined by, for example, the structure, size, number, and the like of joints for connecting pipes and the like. In consideration of the case where air penetrates through the resin material and enters, the degree of influence of air penetration may be set in consideration of information on the resin material.

In the present embodiment, the refrigerator 1 is divided into a plurality of sections, and the degree of influence of air intrusion is set for each section.

Here, the segments can be divided appropriately. For example, the segments may be divided so that the portions indicating the same tendency become one segment, depending on the operating conditions (for example, during operation or during stoppage) or in winter or summer, from the viewpoint of whether or not the negative pressure is likely to be generated. For example, in summer, the pressure around the evaporator 5 tends to become negative, and in winter, the pressure tends to become negative in the portions other than the oil supply system both during operation and during stoppage. According to this tendency, for example, the periphery of the evaporator 5 may be set as one zone, and the other portions, for example, the periphery of the compressor 2 and the periphery of the condenser 3, may be set as one zone.

The estimation unit 21 estimates the air intrusion amount for each zone, for example, using the air intrusion influence amount set for each zone, and the pressure and atmospheric pressure in each zone. Specifically, when the pressure in the section is higher than the atmospheric pressure, that is, the positive pressure, the air intrusion amount becomes zero. On the other hand, when the pressure in the section is lower than the atmospheric pressure, that is, the negative pressure, the value obtained by multiplying the square root of the difference between the pressure and the atmospheric pressure by the degree of influence of air intrusion is estimated as the air intrusion amount. When expressed by the expression, the expression is expressed by the following expression (1) or (2).

[ numerical formula 1]

P(s) -Pat ≧ 0 (positive pressure)

M(s)＝0 (1)

[ numerical formula 2]

P(s) -Pat < 0 (negative pressure)

M(s)＝E(s)×f(P(s)，Pat)

＝E(s)×√|P(s)-Pat| (2)

In the above formulas (1) and (2), P(s) is the pressure [ Pa (abs) ] in the section s]Pat is atmospheric pressure [ Pa (abs) ]]M(s) is the amount of air intrusion [ m ] in the section s³]E(s) is the influence of air intrusion in section s [ m³/Pa]. The unit of the air intrusion amount is not limited to [ m ] described above³]For example, kg, mol, etc. may be used.

The air intrusion amount m(s) of the section s is estimated as an amount of air intruding into the section s per unit time (corresponding to one control cycle) in a state where the pressure and the atmospheric pressure in the section s are maintained.

In this way, when the air intrusion amount m(s) into each zone is estimated, the air intrusion amount m(s) is corrected by the correction unit 26, and the air intrusion amount ma(s) is calculated. The estimation unit 21 calculates the integrated value of the air intrusion amount, that is, the total amount of the air intrusion amount (hereinafter, referred to as "total amount of air intrusion") of the entire refrigerator 1 at present, by adding the value (the air intrusion amount ms (s)) obtained by summing up the air intrusion amounts ma(s) of the respective zones to the last integrated value of the air intrusion amounts. The arithmetic expression is as the following expression (3).

[ numerical formula 3]

M(t)＝M(t-1)+∑Ma(s) (3)

In the formula (3), M (t) is the total air intrusion amount, M (t-1) is the last integrated value of the air intrusion amount, and Σ ma(s) is the total value of the air intrusion amount for each section calculated this time.

The determination unit 22 determines whether or not the total amount of air intrusion m (t) estimated by the estimation unit 21 is equal to or greater than a preset allowable value Mc.

The allowable value Mc is set, for example, by a chemical stability test or an operation performance of the refrigerant. For example, the total amount of air intrusion for which decomposition of the refrigerant occurs or the total amount of air intrusion which does not hinder stable operation of the refrigerator 1 is obtained by a test or an operation performance, and is set to a value smaller than the total amount of air intrusion.

Here, the unit of the allowable value Mc and the total amount of air intrusion needs to be the same. For example, when the unit of the allowable value is [ mol ] and the total amount of air intrusion is a unit other than [ mol ], the unit of the total amount of air intrusion may be converted into the unit of the allowable value [ mol ] and the converted total amount of air intrusion may be compared with the allowable value.

When the total amount of air intrusion M (t) is equal to or greater than the allowable value Mc, the start control unit 23 starts the air extraction device 6. For example, the start controller 23 opens the valve 9 provided in the pipe 8 and starts the air extractor 6. The duration of activation of the air extraction device 6 is determined in real time based on the ratio of the total amount of air intrusion m (t) of the entire refrigerator 1 to the refrigerator capacity.

When the activation duration is determined instantaneously based on the ratio of the total amount of air intrusion m (t) of the entire refrigerator 1 to the refrigerator capacity, for example, the following equation (4) may be used.

[ numerical formula 4]

tc＝f[Vnc/Vc](4)

[ numerical formula 5]

Vnc＝M(t)+α (5)

In the formula (4), tc is the duration of activation [ s ] of the air-extracting means 6]Vnc is the volume of gas to be pumped [ m ]³]The calculation is performed by the above expression (5). Vc is the internal volume [ m ] of the refrigerator³]In the formula (5), the total amount of air intrusion m (t) is added with a predetermined margin α, and the volume of gas to be extracted is set to be slightly larger than the actual total amount of air intrusion m (t) so that the calculated start-up duration time has a margin.

The activation duration tc of the evacuation device 6 may be calculated by the following equation (6) in which the volume of the gas to be evacuated and the pumping capacity of the evacuation device 6 are parameters.

[ numerical formula 6]

tc＝f[Vnc/va](6)

In the formula (6), va represents the pumping capacity [ m ] of the pumping device 6³/s]。

The start control unit 23 does not start the air extracting device 6 when the total amount of air intrusion is less than the allowable value.

The storage unit 24 stores information to be referred to in the processing of the estimation unit 21 and the determination unit 22 in advance. For example, constants included in the respective equations (1) to (6) are registered in advance in addition to the air intrusion influence degree e(s) and the allowable value Mc in each section. The storage unit 24 stores a table in which the estimated difference between the total amount of air intrusion m (t) and the amount of exhaust air md (t) and the correction constant c are set in correspondence with each other. The correction constant is set to a value greater than 1 when the total amount of air intrusion m (t) is less than the discharge air amount md (t), and the correction constant c is set to a value less than 1 when the total amount of air intrusion m (t) is greater than the discharge air amount md (t). The correction constant c is set based on the difference between the estimated total amount of air intrusion m (t) and the estimated exhaust air amount md (t), and is, for example, a value obtained by dividing the exhaust air amount md (t) by the total amount of air intrusion m (t). Even if the correction constant c is not stored in the storage unit 24 as a table, a calculation formula may be stored and the correction constant c may be calculated when performing the correction.

The exhaust air amount calculation section 25 calculates an exhaust air amount md (t), which is an amount of air actually extracted by the air extractor 6. When the evacuation device 6 is actually operated, the noncondensable gas is gradually stored in the evacuation tank 16 of the evacuation device 6. When the noncondensable gas stored in the gas suction tank 16 reaches a predetermined amount (a single discharge amount D1), the valve 9 is closed to stop the supply of the refrigerant gas from the condenser 3, and the pump 11 provided in the gas suction tank 16 is operated to discharge the noncondensable gas into the atmosphere. When the discharge of the noncondensable gas is completed, the valve 9 is opened again, the noncondensable gas is gradually stored in the evacuation tank 16, and the above-described discharge operation is repeated until the discharge of the noncondensable gas is completed. During the set start-up duration, the discharge operation is performed one or more times in accordance with the amount of noncondensable gas actually stored in the refrigerator 1. Since the discharge operation is performed one or more times during the activation duration of the air extracting device 6, the discharge air amount md (t), which is the actual amount of air to be discharged, can be calculated by measuring the discharge amount D1 once and the number n of times the discharge operation is performed.

The primary discharge amount D1 is determined according to the capacity of the air-extracting device 6 (mainly the air-extracting tank 16). That is, when the non-condensation gas of the capacity of the evacuation tank 16 is stored in the evacuation device 6 (when the evacuation tank 16 is filled with the non-condensation gas), the stored non-condensation gas is discharged. When the noncondensable gas stored in the refrigerator 1 is to be discharged in a short time, it is preferable to use the gas suction tank 16 having a large capacity in order to increase the discharge amount once. When the discharged air amount, which is the amount of air actually extracted, is calculated with higher accuracy, it is preferable to increase the estimated resolution of the discharged air amount md (t) while reducing the discharge amount once. In this case, it is sufficient to use the small-capacity evacuation tank 16.

The primary discharge amount D1 may be arbitrarily determined by setting the capacity of the air extractor 6 (mainly, the air extractor tank 16) to the upper limit. In this case, the amount of noncondensable gas in the evacuation tank 16 may be estimated by the pressure sensor 14 and the temperature sensor 15 provided in the evacuation device 6, and the estimated amount of noncondensable gas may be compared with an arbitrarily determined amount (the primary discharge amount D1).

The correction unit 26 corrects at least one of the estimated total amount of air intrusion m (t) and the activation duration when the difference between the total amount of air intrusion m (t) and the discharge air amount md (t) is equal to or greater than the predetermined amount β, and therefore, the correction unit 26 includes the correction necessity determining unit 31, the correction constant updating unit 32, and the correction executing unit 33.

The correction necessity determining unit 31 determines whether or not the difference between the total amount of air intrusion m (t) and the discharge air amount md (t) is equal to or greater than a predetermined amount β, thereby determining whether or not the total amount of air intrusion m (t) needs to be corrected, and when the total amount of air intrusion m (t) needs to be corrected, the total amount of air intrusion m (t) is corrected by updating the correction constant c for correcting the estimated air intrusion amount m(s) for each section as described later, and as a result, the predetermined amount β used in the correction necessity determining unit 31 is set within the range of the error of the estimated total amount of air intrusion m (t) that is allowable for the discharge air amount md (t).

The correction constant updating unit 32 updates the correction constant if the difference between the total amount of air intrusion m (t) and the total amount of discharged air md (t) is determined to be equal to or greater than the predetermined amount β by the correction necessity determining unit 31, and updates the correction constant every time the total amount of air intrusion m (t) is determined to be necessary to be corrected by the correction necessity determining unit 31, specifically, if the total amount of air intrusion m (t) is determined to be necessary to be corrected, the correction constant updating unit 32 reads out the correction constant corresponding to the difference between the estimated total amount of air intrusion m (t) and the total amount of discharged air md (t) from the storage unit 24, and updates the correction constant by multiplying the correction constant set up so far by the read-out correction constant, for example, if a correction constant of 1.1 is read out from the storage unit 24 by the correction constant updating unit 32 in a state where the correction constant is set to 1.2 × 1.1.32, the correction constant is updated by multiplying the correction constant of the total amount of air intrusion m (t) by the new correction constant (t).

The correction execution unit 33 calculates the air intrusion amount ma(s) by multiplying the air intrusion amount m(s) of each zone estimated by the estimation unit 21 by a correction constant. The estimation unit 21 calculates the total air infiltration amount m (t) using the air infiltration amount ma(s) calculated by the correction execution unit 33.

Next, a method of controlling the air extractor 6 by the control device 7 will be described with reference to fig. 3. The correction constant c is set to an initial value of 1, and when the correction constant is updated by the correction unit 26, the updated correction constant c is used.

First, measurement values of the pressure p (S) and the atmospheric pressure Pat in each zone are acquired from various sensors (for example, a pressure sensor and a temperature sensor (not shown in fig. 1)) provided in the refrigerator 1 and in the periphery of the refrigerator 1 (S301).

Next, the air intrusion amount m (S) for each zone is calculated using the pressure p (S) in each zone and the atmospheric pressure Pat (S302).

Subsequently, the air intrusion amount m (S) estimated for each section is corrected (S303). Specifically, the air intrusion amount ma(s) is calculated by multiplying the air intrusion amount m(s) by a correction constant. The initial value of the correction constant c is set to 1, and if the correction constant has not been updated, m(s) ma(s) is obtained. When the correction constant is updated, the updated correction constant (≠ 1) is used, and therefore m(s) ≠ ma(s) is obtained.

Next, the total air intrusion amount M (t) is calculated by adding a value Σ ma (S) obtained by adding the air intrusion amount ma (S) for each segment to the last integrated value M (t-1) of the air intrusion amount (S304).

Next, it is determined whether or not the total amount of air intrusion m (t) is equal to or greater than the allowable value Mc (S305). Here, when the units of both do not match, the two are compared after the process of converting one of the units into the other is performed.

In S305, when the total amount of air intrusion m (t) is equal to or greater than the allowable value Mc (yes in S305), the activation duration is calculated from the total amount of air intrusion m (t) (S306). Then, the air extracting device 6 is started (S307). Next, it is determined whether or not the start-up duration has elapsed (S308), and when the start-up duration has elapsed, the air extraction device 6 is stopped (S309).

Next, the last integrated value M (t-1) of the air intrusion amount is set to zero (S310).

On the other hand, in S305, when the total amount of air intrusion M (t) is smaller than the allowable value Mc, the previous integrated value M (t-1) of the amount of air intrusion is set to the currently calculated total amount of air intrusion M (t) (S311).

The above-described processing is continued at a constant time interval, for example, regardless of whether the refrigerator 1 is in operation or stopped.

Next, a method of calculating the amount of air discharged from the air extractor 6 by the control device 7 will be described with reference to fig. 4.

When the air extractor 6 is started by the start controller 23, the flowchart shown in fig. 4 starts to operate.

First, when the air extractor 6 is started by the start controller 23, the number of discharge operations n is set to 0 (S401).

Next, it is determined whether or not the startup duration has elapsed (S402), and if the startup duration has not elapsed (no in S402), it is determined whether or not the discharge operation by the air extractor 6 has been performed (S403). When it is determined that the discharge operation has not been performed (no in S403), it is determined again whether or not the start-up duration has elapsed (S402). Whether or not the discharge operation has been performed within the activation duration is determined by the operations of S402 and S403.

When it is determined that the discharge operation of the air extractor 6 is performed (yes determination at S403), the number of discharge operations n is added (S404). When the accumulation of the number of times n of the discharge operation is completed, the process returns to S402 and repeats the above-described process.

When it is determined that the activation duration has elapsed (yes in S402), the discharged air amount md (t), which is the amount of air actually extracted, is calculated (S405). Specifically, in S405, the discharge air amount md (t) is calculated by multiplying the discharge amount D1 of the noncondensable gas in one discharge operation of the air extractor 6 by the number n of discharge operations.

Next, a correction method by the control device 7 will be described with reference to fig. 5.

The flowchart shown in fig. 5 is executed after all the discharge operations of the air extractor 6 are completed and the discharge air amount md (t) is calculated. The flowchart shown in fig. 5 is executed each time the discharge operation of the air extractor 6 is completed.

First, it is determined whether or not the difference (absolute value) between the total amount of air intrusion m (t) and the discharged air amount md (t) is equal to or greater than a predetermined amount β (S501), and when the difference (absolute value) between the total amount of air intrusion m (t) and the discharged air amount md (t) is less than a predetermined amount β (no determination in S501), the correction constant is not updated (S502).

When the difference (absolute value) between the total amount of air intrusion m (t) and the discharged air amount md (t) is equal to or greater than the predetermined amount β (yes in S501), a correction constant corresponding to the difference between the estimated total amount of air intrusion m (t) and the discharged air amount md (t) is read from the storage unit 24 (S503), and the correction constant set up so far is multiplied by the read correction constant to update the correction constant (S504).

Next, the operation of discharging the noncondensable gas by the control device 7 will be described with reference to fig. 6 and 7. Fig. 6 is a diagram showing the amount of noncondensable gas in the condenser 3 of the refrigerator 1 according to the present embodiment. Fig. 7 is a diagram showing the amount of noncondensable gas in the air extraction device 6 of the refrigerator 1 according to the present embodiment.

As shown in fig. 6, the non-condensing gas is gradually stored in the refrigerator 1 due to the operating state of the refrigerator 1 and the external environment. The amount of noncondensable gas gradually stored is estimated by the estimating portion 21, and is estimated with high accuracy by being corrected by the correcting portion 26. When the amount of noncondensable gas (total amount of air intrusion m (t)) stored in the condenser 3 exceeds the allowable value Mc, the air-extracting device 6 is started up, and the noncondensable gas stored in the condenser 3 is gradually sucked into the air-extracting device 6.

On the air extraction device 6 side, as shown in fig. 7, when the amount of noncondensable gas (total amount of air invasion m (t)) stored in the condenser 3 exceeds the allowable value Mc, the air extraction device 6 is activated to suck the noncondensable gas from the condenser 3. Therefore, the non-condensing gas is gradually stored in the gas exhaust means 6. When the noncondensable gas stored in the gas-extracting device 6 reaches a predetermined discharge amount D1, the valve 9 is closed and the noncondensable gas is discharged to the atmosphere by the pump 11. By this discharge operation, most of the noncondensable gas stored in the evacuation device 6 is discharged. Then, by opening the valve 9 again, the noncondensable gas is sucked from the condenser 3 to the air-extracting device 6, and the noncondensable gas is gradually stored in the air-extracting device 6. Then, as described above, the discharge operation is repeated. In the example shown in fig. 7, the case where the evacuation operation is performed twice by the evacuation device 6 in order to entirely evacuate the noncondensable gas stored in the condenser 3 has been described, but the present invention is not limited to this example.

The correction unit 26 calculates the air intrusion amount ma(s) by correcting the air intrusion amount m(s) for each zone estimated by the estimation unit 21, and the estimation unit 21 calculates the value of the total air intrusion amount ma(s) (the air intrusion amount ms (s)) but the value corrected by the correction unit 26 is not limited to the air intrusion amount m(s) for each zone estimated by the estimation unit 21. For example, when the air intrusion amount m(s) for each zone is estimated, the estimating unit 21 calculates a value (air intrusion amount ms (s)) obtained by summing up the air intrusion amounts m(s) for each zone. The correction by the correction unit 26 may be performed on the value (air intrusion amount ms (s)) obtained by summing up the air intrusion amounts m(s) of the respective zones. Specifically, the correction unit 26 multiplies the value (air intrusion amount ms (s)) obtained by summing the air intrusion amounts M(s) of the respective zones estimated by the estimation unit 21 by a correction constant to correct the air intrusion amount ms(s), and adds the last integrated value M (t-1) of the air intrusion amounts to the value to calculate the total air intrusion amount M (t). The total amount of air intrusion m (t) thus calculated is determined by the determination unit 22 as to whether or not the total amount is equal to or greater than the preset allowable value Mc.

Next, a modification of the calibration target in the present embodiment will be described. In the above-described embodiment 1, the total amount of air intrusion is corrected, but instead or in addition, in the present modification, the activation duration set by the activation control unit 23 is corrected. The start-up duration is determined on the basis of the total amount of air intrusion m (t), and therefore, by correcting the start-up duration, the total amount of air intrusion m (t) is also corrected indirectly.

In the present modification, the storage unit 24 stores a table in which the difference between the total amount of air intrusion m (t) and the amount of exhaust air md (t) and a correction constant c' for correcting the activation duration are set in association with each other. When the correction necessity determining unit 31 determines that the total amount of air intrusion m (t) needs to be corrected, the correction necessity updating unit 32 reads out the correction constant c' for correcting the activation duration according to the difference between the total amount of air intrusion m (t) and the discharged air amount md (t) from the storage unit 24, and sets and updates the correction constant thus read out as a new correction constant. Then, the start-up duration is multiplied by a new correction constant by the correction execution unit 33 to perform correction.

Next, a modified example of the correction constant in the present embodiment will be described. In the present modification, the air intrusion influence degree is set for each section, and when correcting the total amount of air intrusion, the correction unit 26 corrects the amount of air intrusion for each section based on the air intrusion influence degree.

Therefore, in the present modification, the storage unit 24 stores an addition constant corresponding to the influence degree of air intrusion in each zone, and the correction execution unit 33 multiplies the air intrusion amount m(s) in each zone estimated by the estimation unit 21 by the correction constant, and calculates the air intrusion amount ma(s) by adding the addition constants corresponding to each zone. When the correction constants have not been updated by the correction constant updating unit 32 (when c is 1), the addition constants are not added.

The addition constant is a constant that is more effectively corrected in consideration of the influence of air intrusion in each section. Therefore, the addition constant is set in advance by experiments or the like according to the influence of air intrusion.

Therefore, in the present modification, the air intrusion amount m(s) in each zone is corrected in consideration of the influence of air intrusion in each zone, and therefore the air intrusion amount m(s) in each zone can be corrected with higher accuracy. That is, the total air invasion amount m (t) calculated from the air invasion amount m(s) in each section can also be corrected with higher accuracy.

In the present modification, the correction unit 26 (correction execution unit 33) multiplies the air intrusion amount m(s) of each zone estimated by the estimation unit 21 by the correction constant, and adds the addition constants corresponding to the respective zones to correct the air intrusion amount m(s) (calculated air intrusion amount ma (s)) of each zone, but the correction performed by the correction unit 26 is not limited to the above. For example, the correcting unit 26 first adds an addition constant corresponding to each zone to the air intrusion amount m(s) of each zone estimated by the estimating unit 21, and corrects (weights) the air intrusion amount m(s) of each zone. The correction unit 26 may perform correction by multiplying the total value of the corrected air intrusion amounts m(s) for each section by a correction constant (calculating the air intrusion amount ma (s)). That is, the correcting unit 26 may perform the correction (multiplication by a correction constant) after weighting (addition constant) the air intrusion amount m(s) estimated for each section according to the influence of the air intrusion.

As described above, according to the control device and control method of the air extraction device according to the present embodiment, the total amount of air intrusion of the noncondensable gas intruding into the refrigerator 1 is estimated, and the estimated total amount of air intrusion and/or the activation duration of the air extraction device 6 are corrected based on the amount of air actually discharged by the air extraction device 6, that is, the amount of air discharged. Therefore, the amount of air intrusion and the duration of activation of the air extraction device 6 can be appropriately corrected according to the actual operating conditions of the refrigerator 1. Since the duration of activation of the air extraction device 6 depends on the amount of air intrusion, the total amount of air intrusion is indirectly corrected even when the duration of activation is corrected. That is, the total amount of air intrusion according to the operating condition can be estimated with higher accuracy. For example, even when a low GWP refrigerant is used as the refrigerant of the refrigerator 1, the amount of air intrusion can be estimated with higher accuracy, and therefore, more stable operation can be maintained. Since the air intrusion amount can be estimated with higher accuracy, the start-up of the air extracting device 6 can be optimized, and unnecessary power consumption can be suppressed.

Further, since the correction is performed by a simple calculation of multiplying the air intrusion amount and/or the activation duration by the correction constant, the correction can be performed without imposing a processing load.

[ 2 nd embodiment ]

Next, a control device and a control method for an air extractor according to embodiment 2 of the present invention will be described.

In the above-described embodiment 1, the air intrusion amount is estimated for each section, but the present embodiment is different in that the total amount of air intrusion m (t) into the entire refrigerator 1 is directly estimated without dividing the sections. That is, the refrigerator 1 in the present embodiment is different from embodiment 1 in the calculation method of the total amount of air intrusion m (t) by the estimation unit 21. Hereinafter, the refrigerator 1 according to the present embodiment will be described mainly with respect to differences from embodiment 1.

The estimation unit 21 according to the present embodiment calculates the current total amount of air intrusion m (t) using the following expression (7).

[ number formula 7]

M(t)＝f(Mb×f(Ec′/Vc)×f(Pet，Pct))+M(t-1)

(7)

In the above equation (7), Mb is an air intrusion amount of the reference refrigerator, f (Ec '/Vc) is a function having an air intrusion influence degree and a refrigerator internal volume as parameters, Ec' is an air influence degree of the entire refrigerator 1 relatively determined according to a structural difference from the reference refrigerator, Vc is a refrigerator internal volume, and f (Pet, Pct) is a function having an evaporation pressure Pet and a condensation pressure Pct as parameters. That is, Mb × f (Ec'/Vc) × f (Pet, Pct) in the equation (7) represents the amount of air estimated to intrude into the entire refrigerator 1 per unit time (corresponding to one control cycle). f (Mb × f (Ec '/Vc) × f (Pet, Pct)) is a function having Mb × f (Ec'/Vc) × f (Pet, Pct) as a parameter. Specifically, f (Mb × f (Ec '/Vc) × f (Pet, Pct)) indicates correction of the amount of air (Mb × f (Ec'/Vc) × f (Pet, Pct)) estimated to intrude into the entire refrigerator 1.

As shown in equation (7), the current total amount of air intrusion M (t) is calculated by adding the last integrated value of air intrusion M (t-1) to the corrected value of the amount of air (Mb × f (Ec'/Vc) × f (Pet, Pct)) estimated to intrude into the entire refrigerator 1.

Here, the function f (Ec'/Vc) having the influence of air intrusion and the refrigerator internal volume is a parameter, and functions as a coefficient relatively indicating the ease of air intrusion in the structural plane. That is, the larger the value representing the function is, the more likely the air enters from the structural surface than the reference refrigerator. From the viewpoint of pressure (pressure difference from atmospheric pressure), the function f (Pet, Pct) of the evaporation temperature and the condensation temperature functions as a coefficient indicating the easiness of the air invasion. That is, the more negative the evaporator 5 pressure and the condenser 3 pressure are, the more air easily enters. Therefore, from the viewpoint of pressure, it is indicated that the larger the function value becomes, the more easily air enters.

The storage unit 24 in the present embodiment stores a correction constant c ″ based on a difference between the total amount of air intrusion m (t) and the amount of exhaust air md (t) for correcting the amount of air (Mb × f (Ec'/Vc) × f (Pet, Pct)) estimated to intrude into the entire refrigerator 1. The correction unit 26 performs correction by multiplying Mb × f (Ec'/Vc) × f (Pet, Pct) in the equation (7) by the correction constant c ″. That is, specifically, f (Mb × f (Ec '/Vc) × f (Pet, Pct)) represents multiplication of Mb × f (Bc'/Vc) × f (Pet, Pct) by a correction constant c ″. The determination unit 22 compares the total amount of air intrusion m (t) calculated by equation (7) with the allowable value Mc.

According to the control device 7 and the control method of the air extraction device 6 of the refrigerator 1 according to the present embodiment, as in embodiment 1, division into sections is not necessary, and therefore the processing load in calculating the air intrusion amount can be reduced. Further, since the air intrusion influence degree is also a value relatively determined using a difference in structure from the reference refrigerator, labor for determining the air intrusion influence degree can be reduced. Further, since the total amount of air intrusion m (t) estimated by the estimation unit 21 is corrected based on the amount of discharged air, the amount of noncondensable air intruding into the refrigerator 1 can be estimated with higher accuracy.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

For example, in each embodiment, a case where the control device 7 of the refrigerator 1 has a function of controlling the air-extracting device 6 has been described, but the present invention is not limited to this example, and for example, a control device dedicated to the air-extracting device 6 may be separately provided from the control device 7 in order to control the air-extracting device 6.

In each embodiment, the air-extracting device 6 is connected to the condenser 3 by the pipe 8, but as long as there is a portion where air is likely to stagnate in addition to the condenser 3, the portion may be connected by another pipe. In this way, by connecting the portion where air is likely to be trapped and the air extractor 6, the air in the machine can be efficiently discharged.

Further, in each embodiment, the air extraction device 6 is activated according to the amount of air intrusion, but the refrigerant may be adversely affected by other substances such as moisture. Therefore, in addition to the amount of air intrusion, the amount of intrusion can be estimated for other substances such as moisture, and the start and stop of the mechanism for removing or reducing the substances based on the estimated amount of intrusion can be controlled. The other substances may be removed at all times by providing a structure (such as moisture removal by a dry filter) that enables the other substances to be removed at all times.

Description of the symbols

1-refrigerator, 2-compressor, 3-condenser, 4-expansion valve, 5-evaporator, 6-air extractor, 7-control device, 8, 13-piping, 9, 12-valve, 10-check valve, 11-pump, 14-pressure sensor, 15-temperature sensor, 16-air extractor, 21-estimation portion, 22-determination portion, 23-start control portion, 24-storage portion, 25-exhaust air amount calculation portion, 26-correction portion, 31-correction/non-correction determination portion, 32-correction constant update portion, 33-correction execution portion.

Claims

1. A control device for controlling an air-extracting device provided in a refrigerator, the control device comprising:

an estimation unit that estimates a total amount of air entering the refrigerator;

a determination unit that determines whether or not the total amount of air intrusion is equal to or greater than a preset allowable value;

a start control unit that determines a start-up duration of the air extraction device based on the total amount of air intrusion when the total amount of air intrusion is equal to or greater than the allowable value, and starts up the air extraction device only for the start-up duration;

a discharged air amount calculation unit that calculates a discharged air amount, which is an amount of air actually discharged by the air extractor; and

and a correction unit that corrects at least one of the total amount of air intrusion and the activation duration when a difference between the total amount of air intrusion and the discharge air amount is equal to or greater than a predetermined amount.

2. The control device according to claim 1,

the correction unit corrects at least one of the total amount of air intrusion and the activation duration by multiplying a correction constant corresponding to a difference between the total amount of air intrusion estimated by the estimation unit and the discharge air amount.

3. The control device according to claim 2,

the correction constant is a value obtained by dividing the discharged air amount by the total amount of air intrusion.

4. The control device according to claim 1,

the refrigerator is divided into a plurality of sections,

an air intrusion influence degree is set for each of the sections,

the estimating unit estimates an air intrusion amount for each of the zones, estimates the total amount of air intrusion in the entire refrigerating machine from the estimated air intrusion amount for each of the zones,

when correcting the total amount of air intrusion, the correcting section corrects the amount of air intrusion for each of the sections in accordance with the air intrusion influence degree.

5. A refrigerator using a low-pressure low-GWP refrigerant, comprising:

an air extraction device; and

the control device of any one of claims 1 to 4.

6. A control method for an air-extracting device provided in a refrigerator, the method comprising:

an estimation step of estimating a total amount of air entering the refrigerator;

a determination step of determining whether or not the total amount of air intrusion is equal to or greater than a preset allowable value;

a start control step of determining a start-up duration of the air extraction device based on the total amount of air intrusion when the total amount of air intrusion is equal to or greater than the allowable value, and starting up the air extraction device only for the start-up duration;

an exhaust air amount calculation step of calculating an exhaust air amount which is an amount of air actually exhausted by the air exhauster; and

and a correcting step of correcting at least one of the total amount of air intrusion and the activation duration when a difference between the total amount of air intrusion and the discharge air amount is equal to or greater than a predetermined amount.