JP5165391B2 - Cooling storage - Google Patents

Description

  The present invention relates to a cooling storage of an indirect cooling type such as a constant temperature and high humidity storage.

The constant temperature and high humidity chamber is a so-called cooler that cools the interior of the storage room by natural convection by cooling the wall of the storage room so that the freshness of the fresh food can be maintained over a long period of time. An indirect cooling method is adopted. In this case, it is important to keep the cooling temperature constant over the entire area of the cooling wall in order to keep the temperature variation in the storage chamber small.
Conventionally, what was described in patent document 1 is known as an example of the constant temperature high humidity store which satisfies this point. This is because the brine pipe is meandered along the back side of the interior plate that becomes the cooling wall surface of the storage room, and the brine cooled by the freezer is circulated through the brine pipe to cool the cooling wall surface. Thus, the storage chamber is indirectly cooled.

In the case of the above brine method, if the brine circulation amount is an appropriate amount, the brine circulates at a substantially constant temperature, so that the entire cooling wall surface can be maintained at a constant temperature. However, this method requires a brine, a brine circulation pump, an evaporator for cooling the brine, and the like, which increases the number of parts and causes a problem in terms of cost.
Therefore, in consideration of cost, an evaporation pipe constituting the evaporator in the refrigeration circuit is provided instead of the brine pipe on the back side of the cooling wall of the storage room, and the latent heat due to evaporation of the refrigerant directly flowing to the evaporation pipe The thing which cools a cooling wall surface is also proposed.
JP-A-63-3156

By the way, in the method of cooling the cooling wall by piping the evaporation pipe constituting the evaporator to the cooling wall as described above, in order to make the cooling temperature constant over the entire cooling wall, the cooling pipe is connected to the cooling wall. It is necessary to evaporate the refrigerant until the end of the evaporation pipe. That is, it is necessary to control the flow rate of the refrigerant so as to eliminate the degree of superheat at the outlet of the evaporator.
When this is attempted with a control device such as a capillary tube or an expansion valve, for example, in a capillary tube, depending on the combination of the amount of restriction of the capillary tube and the amount of refrigerant charged, a specific ambient temperature and a specific compressor speed Only under these conditions, the degree of superheat can be eliminated at the outlet of the evaporator. However, when the ambient temperature or the compressor speed changes, there is a situation where the degree of superheating occurs, or conversely, the liquid refrigerant returns too much.In other words, for the entire operating range with different conditions, the control to eliminate the degree of superheating is not possible. I can't.

In the case of an expansion valve, the degree of superheat can be kept constant if it is a temperature type expansion valve or an electric expansion valve that is controlled so as to keep the degree of superheat constant. However, when these expansion valves are operated so that the degree of superheat is close to “0”, hunting in which the opening degree of the valve changes periodically is likely to occur. When hunting occurs, the evaporation temperature changes periodically, and the temperature of the cooling wall changes accordingly.
That is, in the superheat control using the capillary tube, the temperature type expansion valve or the electric expansion valve, the control to eliminate the superheat degree at the outlet of the evaporator cannot be performed stably, and as a result, the entire area of the cooling wall is not covered. There was a problem that it was not possible to make the cooling temperature constant.
The present invention has been completed based on the above circumstances, and its purpose is to cool the cooling wall surface over the entire area of the cooling wall surface using an evaporation pipe that constitutes the evaporator of the refrigeration circuit. It is in place to be able to keep the temperature constant.

  In the present invention, a condenser body, an expansion valve, and an evaporator are sequentially connected to a storage body having a heat insulation box and having an interior as a storage chamber, and a discharge side of an inverter compressor, and the outlet side of the evaporator is a high-temperature part. And a refrigeration circuit connected to the suction side of the inverter compressor through a heat exchanging section, and an evaporation pipe constituting the evaporator along the back side of the interior plate serving as a cooling wall surface of the storage chamber A cooling storage that is piped and in which the storage chamber is indirectly cooled via the cooling wall surface by latent heat accompanying the evaporation of the refrigerant in the evaporation pipe, and the expansion valve is electrically driven with a variable valve opening An expansion valve, a rotation speed sensor for detecting the rotation speed of the inverter compressor, an outside temperature sensor for detecting the outside temperature, and various conditions of the rotation speed and the outside temperature of the inverter compressor In the evaporator Storage means for storing the valve opening degree of the electric expansion valve as data so that there is no degree of superheat at the outlet and no liquid back is generated in the inverter compressor, and the number of rotations at predetermined time intervals The detection value of the sensor and the outside temperature sensor is taken in, the corresponding valve opening is acquired from the data of the storage means based on the detection value, and the valve opening of the electric expansion valve is set to the acquired valve opening. And an electric expansion valve control means for controlling.

  When the refrigeration circuit is driven, the refrigerant flows through the evaporation pipe while evaporating, and the cooling wall surface is cooled by the latent heat, and then the refrigerant becomes superheated steam and is sucked into the inverter compressor. Here, the valve opening degree of the electric expansion valve, that is, the refrigerant flow rate, is controlled so that there is no degree of superheat at the outlet of the evaporator and no liquid back is generated with respect to the inverter compressor. The refrigerant is maintained in a gas-liquid mixed state up to the front of the provided heat exchanging section, and all the liquid refrigerant is evaporated while flowing through the heat exchanging section and is sucked into the inverter compressor as a gas refrigerant. For this reason, the inside of the evaporation pipe that is routed along the cooling wall of the storage chamber is maintained at a constant evaporation temperature until the end, and as a result, the cooling wall is maintained at a constant cooling temperature throughout the entire area. Is done.

During operation of the cooling storage, the detected internal temperature is compared with a preset target temperature, and the number of revolutions of the inverter compressor is increased or decreased according to the difference, that is, the refrigeration capacity is controlled to control the storage. Although the inside is maintained at substantially the target temperature, the change in the rotation speed of the inverter compressor affects the refrigerant flow rate and the like, and changes the evaporation state of the liquid refrigerant in the evaporator. At the same time, when the outside temperature such as the ambient temperature at the installation position of the cooling storage changes, the load changes, and this also changes the evaporation state of the liquid refrigerant in the evaporator.
Therefore, during operation of the cooling storage, the electric expansion valve control means takes in the rotation speed of the inverter compressor detected by the sensor and the outside temperature at every predetermined time interval and compares them with the data in the storage means. The valve opening degree corresponding to the rotation speed of the inverter compressor and the outside temperature is acquired, and the valve opening degree of the electric expansion valve is controlled to the acquired valve opening degree. As a result, the refrigerant flow rate is controlled so that there is no degree of superheat at the outlet of the evaporator and no liquid back is generated with respect to the inverter compressor, and as described above, the evaporation pipe piped along the cooling wall of the storage chamber The inside is maintained at a constant evaporation temperature until the end, and the cooling wall surface is maintained at a constant cooling temperature over the entire area.
That is, it becomes possible to always keep the cooling temperature constant over the entire area of the cooling wall for the entire operating range of the cooling storage with different conditions of the rotational speed of the inverter compressor and the outside temperature.

The following configuration may also be used.
(1) In the data, the valve opening degree is represented by an approximate expression using a function of the rotation speed of the inverter compressor and the outside temperature.
(2) The data is formed as table data in which the valve opening is compared with the rotation speed of the inverter compressor and the outside temperature.

(3) The outside temperature is the air temperature around the installation location of the cooling storage, and the outside temperature sensor detects the ambient temperature.
(4) The outside temperature is the condenser temperature, and the outside temperature sensor detects the temperature of the condenser.
(5) The high temperature part is formed by a refrigerant pipe on the outlet side of the condenser.

  According to the present invention, the cooling temperature can be kept constant over the entire cooling wall surface of the storage room, and the temperature variation in the storage room can be suppressed to a low level, even though the structure can cope with the low cost.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS. In this embodiment, a constant temperature and high humidity store is illustrated.
In FIG.1 and FIG.2, the code | symbol 10 is the main body of a constant temperature high humidity warehouse, Comprising: It is formed with the vertically long heat insulation box. The heat insulating box is stored in a vertically long outer box 11 having an open front surface, and two upper and lower inner boxes 12 having a substantially cubic shape having an open front surface are spaced apart from each other. It is formed by filling a heat insulating material 13 such as foamed resin between them. Both the outer box 11 and the inner box 12 are formed of, for example, a heat conductive stainless steel plate. Inside the main body 10, two upper and lower storage chambers 15A and 15B are formed, and heat insulating doors 17 are provided in front opening portions 16 of the respective storage chambers 15A and 15B so as to be opened and closed.
The main body 10 is supported by legs 18 provided at the four corners of the bottom surface, and a machine room 19 is provided on the upper surface of the main body 10, and an electrical box that stores a refrigeration apparatus 27, an operation control unit, and the like described later is provided. Equipped.

Each of the storage chambers 15 </ b> A and 15 </ b> B is basically indirectly cooled by the cold heat of the cooling wall surface 14 cooled by the refrigeration circuit 20.
The refrigeration circuit 20 includes a variable capacity compressor 21 (hereinafter referred to as an inverter compressor 21) driven by an inverter motor, an air-cooled condenser 22, a dryer 23, an electric expansion valve 24, and an evaporator 25. Are circulated through a refrigerant pipe 26. Among these, the inverter compressor 21, the condenser 22, the dryer 23, and the electric expansion valve 24 constitute a refrigeration device 27, and is installed in the machine room 19 as described above.
More specifically, the inverter compressor 21 can control the number of rotations in a plurality of stages. Further, the electric expansion valve 24 can be controlled in a plurality of stages by using a stepping motor or the like as a drive source.

The evaporator 25 is formed by bending a copper evaporation pipe 30 into a predetermined shape, and is a wall surface of the upper and lower storage chambers 15A and 15B, that is, a back surface (a heat insulating material 13) on a predetermined surface of the inner box 12 constituting the wall surface. The pipes are closely attached along the side surface.
The evaporating pipe 30 is continuously piped from the upper storage chamber 15A to the lower storage chamber 15B. Specifically, as shown in FIG. 2, the upper right corner viewed from the front on the back surface of the upper storage chamber 15A is used as a starting point 31AS. , Piped in a serpentine shape with the back side facing down, then in a serpentine shape with the right side from the bottom up, the top side from the right to the left, and the left side from the top to the bottom. A pipe is linearly formed from the bottom to the top along the upper end, and the upper end thereof is the end point 31AE in the upper storage chamber 15A.
A relay portion 32 is connected to the end point 31AE of the upper storage chamber 15A, and is piped through the heat insulating material 13 to reach the upper right corner of the back surface of the lower storage chamber 15B. On the lower storage chamber 15B side, the upper right corner of the back surface is set as the starting point 31BS, and the back surface, the right side surface, the upper surface, and the left side surface are respectively meandered like the upper storage chamber 15A. Piping is performed linearly from bottom to top along the edge, and the upper end thereof is the end point 31BE in the lower storage chamber 15B.

In this way, in the upper and lower storage chambers 15A and 15B, the evaporating pipe 30 is closely attached to the back, right side, top and left side wall surfaces, and the wall surface on which these evaporating pipes 30 are provided is cooled. It becomes the wall surface 14.
Further, the outlet connection portion 34 protruding from the end point 31BE of the lower storage chamber 15B on the outlet side of the evaporation pipe 30 is connected to the suction pipe 21A of the inverter compressor 21, and is close to the suction pipe 21A in the outlet connection portion 34. A predetermined range of the position is in close contact with the refrigerant pipe 26 on the output side of the dryer 23 in the refrigeration circuit 20, and this close contact portion serves as a heat exchanging portion 35. A high-temperature liquid refrigerant flows through the refrigerant pipe 26 on the output side of the dryer 23 that is in close contact with the heat exchanging section 35 of the evaporation pipe 30, so that the portion becomes the high-temperature section 36.

  The basic operation of the constant temperature and high humidity chamber is that when the refrigeration apparatus 27 is driven, it evaporates while the refrigerant flows through the evaporation pipe 30 constituting the evaporator 25, and the upper and lower storage chambers 15A are caused by the latent heat associated therewith. 15B is cooled, and the inside of each storage chamber 15A, 15B is indirectly cooled by the cold heat. During this time, the temperature (internal temperature) in the storage chambers 15A and 15B is detected by, for example, an internal temperature sensor 40 provided in the upper storage chamber 15A, and the inverter compressor control unit 41 detects the internal temperature. The value is compared with the target value of the internal temperature set by the target temperature setting unit 42, and the number of revolutions of the inverter compressor 21 is controlled to increase / decrease based on the comparison result, and the evaporation temperature is controlled. The internal temperature is maintained at the target temperature.

In the present embodiment, when the cooling wall surfaces 14 set in both the storage chambers 15A and 15B are cooled in accordance with the cooling operation, there is no temperature difference over the entire cooling wall surfaces 14 and further over the entire cooling wall surfaces 14. It is intended to be cooled to a certain temperature.
For example, in the above structure, when the liquid refrigerant is completely evaporated and becomes saturated vapor at the outlet side of the evaporation pipe 30 constituting the evaporator 25, more specifically, at the position upstream of the end point 31BE on the lower storage chamber 15B side. From then on, the steam rises in temperature and becomes superheated steam, which has superheat. Therefore, the cooling wall surface 14 on the back surface of the lower storage chamber 15B to which the region of the evaporation pipe 30 having the same superheat degree is in close contact, particularly the region along the left edge thereof, has a relatively high temperature.

In order to eliminate such uneven cooling temperature, it is only necessary to prevent the degree of superheating up to the end point 31BE on the lower storage chamber 15B side in the evaporation pipe 30, but it becomes saturated steam. If the location is shifted too far downstream, a liquid back may occur in the inverter compressor 21 this time.
Therefore, in the present embodiment, in order to ensure that the degree of superheat is eliminated up to the end point 31BE on the lower storage chamber 15B side in the evaporation pipe 30 and that no liquid back is generated in the inverter compressor 21, the evaporation pipe 30 The refrigerant is maintained in a gas-liquid mixed state up to the front of the heat exchanging unit 35 provided in the outlet connection unit 34, and all the liquid refrigerant can be evaporated into a gas refrigerant while flowing through the heat exchanging unit 35. The valve opening degree of the electric expansion valve 24, that is, the flow rate of the refrigerant is controlled.

  Here, the inverter compressor 21 is used for the compressor of the refrigeration circuit 20 like the constant temperature and high humidity store of this embodiment, and the internal temperature is controlled to the target temperature by changing the rotation speed of the inverter compressor 21. In this type, the change in the rotational speed of the inverter compressor 21 affects the refrigerant flow rate and the like, and changes the evaporation state of the liquid refrigerant in the evaporation pipe 30. In addition, when the ambient temperature at the installation position of the constant temperature and high humidity chamber changes, the load changes, and this also changes the evaporation state of the liquid refrigerant in the evaporation pipe 30. When controlling the valve opening of the expansion valve 24, that is, the refrigerant flow rate, it is necessary to consider the conditions of the rotational speed of the inverter compressor 21 and the ambient temperature.

The control mechanism of the electric expansion valve 24 of the present embodiment taking the above points into consideration is as follows.
First, in order to obtain basic data, the evaporative pipe 30 is respectively operated when the inverter compressor 21 is operated at the maximum rotation speed and at the minimum rotation speed under a plurality of ambient temperature conditions. An electric expansion valve satisfying that the outlet connecting portion 34 (strictly before the heat exchanging portion 35) is not superheated and the inverter compressor 21 has no liquid back (all is evaporated in the heat exchanging portion 35). The valve opening of 24 is obtained.
As for “the outlet connection part 34 of the evaporation pipe 30 is not superheated”, the saturation temperature (evaporation temperature) and the temperature of the outlet connection part 34 of the evaporation pipe 30 are measured, and there is no difference between the two measured values. It can be confirmed that there is no degree of superheat.
On the other hand, regarding “the inverter compressor 21 has no liquid back”, the temperature of the suction pipe 21A of the inverter compressor 21 is measured, and when the measured value is higher than the saturation temperature, the suction pipe 21A is overheated. It can be assumed that all of the steam is evaporated and becomes superheated steam, and as a result, it can be determined that the inverter compressor 21 has no liquid back.

Thus, the valve opening degree calculated | required about several ambient temperature conditions and two rotation speed conditions is plotted like the graph of FIG. 3, and ambient temperature (at) and compressor rotation speed (R) are plotted from this graph. An approximate expression (1) of the valve opening (P) is obtained as a function.
P = f (at, R) (1)
As shown in FIG. 4, the control mechanism is provided with an electric expansion valve control unit 50 that is equipped with a microcomputer, a timer, etc. and executes a predetermined program, and is provided in the electric expansion valve control unit 50. The storage unit 51 stores the approximate expression (1) for calculating the valve opening degree (P).
An ambient temperature sensor 45 that detects the ambient temperature of the constant temperature and high humidity chamber is provided on the outer wall of the machine room 19. The inverter compressor control unit 41 is connected to a rotation speed sensor 46 that detects the rotation speed of the inverter compressor 21 during operation. The ambient temperature sensor 45 is also input to the electric expansion valve control unit 50. Connected to the side.

  The electric expansion valve control unit 50 is provided with a detection value capturing unit 52 that captures and outputs the detection values of the ambient temperature sensor 45 and the rotation speed sensor 46 at predetermined time intervals (for example, 30 seconds). A valve opening calculation unit 53 is provided for calculating the valve opening by substituting both detection values output from the detection value fetching unit 52 into the approximate expression (1) stored in the storage unit 51. Yes. Further, a valve drive unit 54 is provided that receives the valve opening instruction value, which is the calculation result of the valve opening calculation unit 53, and drives and controls the electric expansion valve 24 so that the valve opening becomes the instruction value. Yes.

The operation of this embodiment will be described with reference to the flowchart of FIG.
During the cooling operation, the refrigeration device 27 is driven to cool the cooling wall surfaces 14 of the upper and lower storage chambers 15A and 15B via the evaporation pipe 30 that constitutes the evaporator 25, and each of the storage chambers 15A and 15A, The inside of 15B is indirectly cooled, and during this time, the number of revolutions of the inverter compressor 21 is controlled to increase or decrease based on the difference between the internal temperature detected by the internal temperature sensor 40 and the target temperature, and the internal temperature becomes almost the target temperature. Maintained.
At the same time, control of the electric expansion valve 24 is executed. In the electric expansion valve control unit 50, as shown in FIG. 5, the detected value of the ambient temperature (at) by the ambient temperature sensor 45 and the detected value of the rotational speed (R) of the inverter compressor 21 by the rotational speed sensor 46 are obtained. (Step S1), the valve opening calculation unit 53 executes a calculation for substituting both detected values into the approximate expression (1) {P = f (at, R)} stored in the storage unit 51. The valve opening (P) is obtained (step S2). The calculation result is output to the valve drive unit 54 as the updated valve opening instruction value, and the stepping motor or the like is driven to control the electric expansion valve 24 so that the valve opening becomes the instruction value (step). S3).

  In this way, when the valve opening degree of the electric expansion valve 24 is controlled, that is, the refrigerant flow rate is controlled, the outlet connection portion 34 of the evaporation pipe 30 (up to the front of the heat exchanging portion 35) has no degree of superheat, and the inverter is compressed. The machine 21 has no liquid back (evaporates in the heat exchange unit 35), in other words, the evaporation pipe 30 piped along the cooling wall surface 14 of the storage chambers 15A and 15B has a constant evaporation until the end. The temperature is maintained, and each cooling wall surface 14 is maintained at a constant cooling temperature including the inside of each region.

  During this time, as described above, the rotational speed of the inverter compressor 21 may change or the ambient temperature may change. However, the above steps S1 to S3 related to the control of the electric expansion valve 24 are performed for 30 seconds. When the rotational speed of the inverter compressor 21 and the ambient temperature are changed, the optimum valve opening corresponding to the change is calculated, the valve opening instruction value is updated, and the valve The electric expansion valve 24 is driven and controlled so that the opening degree becomes the same indicated value. As a result, similarly, the outlet connection portion 34 of the evaporation pipe 30 is not superheated, and the inverter compressor 21 is not in a liquid back state.

  As described above, according to the present embodiment, the cooling temperature can always be kept constant over the entire cooling wall 14 for the entire operating range of the constant temperature and high humidity chamber in which the rotational speed and ambient temperature of the inverter compressor 21 are different. As a result, the temperature variation in the storage chambers 15A and 15B can be reduced. Of course, compared to the brine type, the number of parts can be greatly reduced and the cost can be reduced.

As another method for controlling the valve opening degree of the electric expansion valve 24 so that the outlet connection portion 34 of the evaporation pipe 30 is not superheated, the saturation temperature (evaporation temperature) and the outlet connection portion of the evaporation pipe 30 are used. 34, and a method of controlling the valve opening so that the degree of superheat, which is the difference between them, is “0”, in other words, a method of directly controlling the degree of superheat and controlling the valve opening. Though conceivable, this method requires two temperature sensors for detecting the saturation temperature and the temperature of the outlet connection portion 34 of the evaporation pipe 30 respectively, and further controls the inverter compressor 21 so that there is no liquid back. In addition, another temperature sensor for detecting the temperature of the suction pipe 21A of the inverter compressor 21 is also required.
On the other hand, in the present embodiment, it is necessary when the opening degree of the electric expansion valve 24 is controlled so that the outlet connection portion 34 of the evaporation pipe 30 is not superheated and the inverter compressor 21 has no liquid back. Since only one ambient temperature sensor 45 that detects the ambient temperature is required, the temperature sensor can be provided at low cost.

Further, in the method of controlling the valve opening degree so that the degree of superheat becomes “0”, hunting in which the valve opening degree changes periodically is likely to occur, and the evaporation temperature and thus the temperature of the cooling wall surface 14 change unnecessarily. There is a fear.
On the other hand, in this embodiment, the valve opening degree is controlled by the ambient temperature and the rotation speed of the inverter compressor 21, and the valve opening degree is unnecessary except when the operating condition changes. Therefore, the cooling temperature itself of the cooling wall surface 14 can be stabilized.

<Embodiment 2>
In the second embodiment of the present invention, data of a suitable valve opening (P) in each condition of the ambient temperature (at) and the rotation speed (R) of the inverter compressor 21 is formed as the table data 60 shown in FIG. And stored in the storage unit 51.
Regarding the control of the electric expansion valve 24, the detected value of the ambient temperature (at) by the ambient temperature sensor 45 and the detected value of the rotational speed (R) of the inverter compressor 21 by the rotational speed sensor 46 are taken in every 30 seconds. Both detected values are illuminated with table data 60 stored in the storage unit 51 to obtain a valve opening, which is output to the valve driving unit 54 as an updated valve opening instruction value, The electric expansion valve 24 is controlled so that becomes the same indicated value.

<Embodiment 3>
In the third embodiment, the condenser temperature is selected as a condition for controlling the valve opening degree of the electric expansion valve 24 instead of the ambient temperature exemplified in the first embodiment. The condenser temperature, that is, the condensation temperature, is related to the ambient temperature, and is considered suitable as a condition that reflects load fluctuations.
Then, similarly to the first embodiment, a graph is created from the valve opening obtained for a plurality of condenser temperature conditions and two rotational speed conditions, and from this graph, the condenser temperature (ct) and the inverter compressor rotation are obtained. An approximate expression (2) of the valve opening (P) as a function of the number (R) is obtained and stored in the storage unit 51.
P = f (ct, R) (2)
On the other hand, as a temperature sensor for controlling the electric expansion valve 24, a condenser temperature sensor 62 for detecting the temperature of the outlet portion of the condenser 22 is provided in place of the ambient temperature sensor 45 as shown by a chain line in FIG. Yes.

Regarding the control of the electric expansion valve 24, the detected value of the condenser temperature (ct) by the condenser temperature sensor 62 and the detected value of the rotational speed (R) of the inverter compressor 21 by the rotational speed sensor 46 are every 30 seconds. An operation is performed in which both detected values are substituted into the approximate expression (2) {P = f (ct, R)} stored in the storage unit 51 to obtain the valve opening (P). The calculation result is output to the valve drive unit 54 as the updated valve opening instruction value, and the electric expansion valve 24 is controlled so that the valve opening becomes the same instruction value.
Normally, the constant temperature and high humidity chamber is equipped with a condenser temperature sensor 62 of this type for monitoring the condensation temperature and detecting the presence or absence of a failure of the refrigeration apparatus 27, and a temperature for controlling the electric expansion valve 24. Since existing sensors can be used as sensors, further cost reduction can be achieved.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In the above embodiment, the valve opening degree of the electric expansion valve is controlled at intervals of 30 seconds. However, this is merely an example, and the control time interval can be arbitrarily set.
(2) In the first embodiment, the graph is created to obtain an approximate expression for obtaining the valve opening. However, the number of samples is limited to eight. However, the larger the number of samples, the more accurate the approximation. It is possible to obtain an expression.
(3) As shown in the third embodiment, even when the condenser temperature is selected as a condition instead of the ambient temperature, the table data as shown in the second embodiment is created as the valve opening data. Good.

(4) You may select other high temperature parts, such as the discharge side piping of an inverter compressor, as a high temperature part closely_contact | adhered piping with the heat exchange part provided in the evaporation pipe.
(5) The number of storage rooms is not limited to the two rooms exemplified in the above embodiment, and may be one room or three or more rooms.
(6) Regarding the wall surface on which the evaporation pipe in the storage chamber is piped, that is, the cooling wall surface, the number and position thereof can be arbitrarily set.
(7) The present invention can be applied to all types of cooling storages that indirectly cool the storage chamber by cooling the wall surface of the storage chamber from the back side.

The longitudinal cross-sectional view of the constant temperature high humidity chamber which concerns on Embodiment 1 of this invention Explanatory drawing of piping structure of control mechanism and evaporation pipe Graph showing optimum valve opening under various conditions Block diagram showing control mechanism of electric expansion valve Flow chart showing control operation of electric expansion valve The figure which shows the table data which concerns on Embodiment 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Main body (storage main body) 12 ... Inner box (interior board) 14 ... Cooling wall surface 15A, 15B ... Storage chamber 20 ... Refrigeration circuit 21 ... Inverter compressor 21A ... Suction pipe 22 ... Condenser 24 ... Electric expansion valve 25 ... Evaporation Equipment 26 ... Refrigerant piping 30 ... Evaporation pipe 34 ... Outlet connection part 35 ... Heat exchange part 36 ... High temperature part 45 ... Ambient temperature sensor (outside temperature sensor) 46 ... Rotational speed sensor 50 ... Electric expansion valve control part (electric expansion valve) Control means) 51 ... Storage section (storage means) 52 ... Detection value fetching section 53 ... Valve opening calculation section 54 ... Valve drive section 60 ... Table data 62 ... Condenser temperature sensor (outside chamber temperature sensor)

Claims (6)

A storage body consisting of a heat insulating box and having a storage chamber inside;
A condenser, an expansion valve, and an evaporator are sequentially connected to a discharge side of the inverter compressor, and an outlet side of the evaporator is connected to a suction side of the inverter compressor through a heat exchanging portion with a high temperature portion. A circuit is provided,
An evaporation pipe constituting the evaporator is provided along the back side of the interior plate serving as a cooling wall surface of the storage chamber, and the latent heat generated when the refrigerant evaporates in the evaporation pipe through the cooling wall surface. Is a cold storage that is indirectly cooled,
The expansion valve is an electric expansion valve with a variable valve opening,
A rotational speed sensor for detecting the rotational speed of the inverter compressor;
An outside temperature sensor for detecting the outside temperature;
The electric expansion valve for achieving no state of superheat at the outlet of the evaporator and no liquid back to the inverter compressor under various conditions of the rotational speed of the inverter compressor and the outside temperature. Storage means for storing the valve opening of
The detection values of the rotation speed sensor and the outside temperature sensor are taken at predetermined time intervals, the corresponding valve opening is obtained from the data of the storage means based on the detection values, and the valve opening of the electric expansion valve is opened. Electric expansion valve control means for controlling the degree to the acquired valve opening;
The cooling storage characterized by being provided. 2. The cooling storage according to claim 1, wherein the data indicates the valve opening degree as an approximate expression using a function of the rotation speed of the inverter compressor and the outside temperature. The cooling storage according to claim 1, wherein the data is formed as table data in which the valve opening degree is compared with the rotation speed of the inverter compressor and the outside temperature. The outside temperature is the air temperature around the installation position of the cooling storage, and the outside temperature sensor detects the ambient temperature. The cooling storage according to one item. The cooling according to any one of claims 1 to 3, wherein the outside temperature is a condenser temperature, and the outside temperature sensor detects a temperature of the condenser. Storage. The said high temperature part is formed of the refrigerant | coolant piping by the side of the outlet of the said condenser, The cooling storehouse as described in any one of Claim 1 thru | or 5 characterized by the above-mentioned.

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