JP2001165547A - Apparatus and method for cooling vending machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for cooling a vending machine capable of improving a refrigerating efficiency and conducting an energy conservation by suitably maintaining a refrigerant supply amount to an evaporator. SOLUTION: Electronic expansion valves 15A to 15C are provided as flow regulating means between a condenser 4 and evaporators 2A to 2C. The valves 15A to 15C are sequentially and independently controlled so as to maintain the superheat degrees of a refrigerant at the evaporators 2A to 2C at a predetermined value. Thus, even when operating states such as the change in the number of the operating evaporators 2A to 2C are altered, suitable refrigerant supplying amounts to the respective evaporators 2A to 2C can be maintained, and respective warehouses 1A to 1C can be efficiently cooled with high refrigerating capability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vending machine cooling device and a method of cooling the same, and more particularly, to a vending machine cooling device which efficiently cools the inside of each refrigerator and contributes to energy saving, and a cooling device therefor. It relates to a cooling method.

[0002]

2. Description of the Related Art In a vending machine that stores and sells products such as canned beverages, the inside of a warehouse for storing products is thermally insulated from the outside,
Most are cooled or heated to a predetermined temperature. Especially in recent vending machines, the inside of the warehouse is divided into multiple,
Many are divided into warehouses that sell cold drinks throughout the year and warehouses that switch between cold drinks or hot drinks according to the season. FIG. 7 shows an outline of a conventional vending machine cooling device.

Referring to FIG. 7, the inside of the vending machine is divided by heat insulating material 7 into three compartments, a left compartment 1A, a middle compartment 1B and a right compartment 1C. In this example, the left warehouse 1A is configured as a warehouse that sells cold drinks throughout the year, and the middle warehouse 1B and the right warehouse 1C are configured as warehouses that sell cold drinks or hot drinks according to the season.
That is, only the evaporator 2A as a cooler is disposed in the left warehouse 1A, whereas the evaporators 2B and 2C and the heater 12 as the heater are provided in the middle warehouse 1B and the right warehouse 1C, respectively.
B and 12C are arranged.

[0004] A conventional cooling device of a vending machine will be described.
And 2C and a compressor (compressor) 3 arranged outside the refrigerator
A known refrigeration circuit is constituted by the condenser 4 and the upstream side of each of the evaporators 2A to 2C, and a solenoid flow rate adjusting means is constituted by the solenoid valves 5A, 5B and 5C and the capillary tubes 6A, 6B and 6C. I have. The solenoid valves 5A to 5C are
An on / off valve that takes only two positions, fully open and fully closed, receives the output of the control means 10 and shuts off the supply of refrigerant when the refrigerators 1A to 1C are cooled to a set temperature (for example, 5 ° C.). Perform the function.

In the drawings, reference numerals 8A, 8B and 8C
Is an in-compartment fan for circulating cooling air or heating air in the in-compartment, 9A, 9B and 9C are in-compartment temperature sensors for detecting the in-compartment temperature, and 11 is the refrigerant temperature at the outlet of the condenser 4. Outside fans are shown.

[0006]

As described above, the conventional cooling apparatus uses the capillary tubes 6A to 6C as the refrigerant flow adjusting means, so that even if the number of operating evaporators 2A to 2C fluctuates. Capillary tubes 6A-6
The flow rate adjustment amount of C is constant, and an amount of the refrigerant corresponding to the amount of the refrigerant introduced into the capillary tube is supplied to the evaporator. Therefore, when the number of operating evaporators 2A to 2C fluctuates,
Since the amount of refrigerant supplied to the remaining evaporator fluctuates, the refrigerating capacity of the evaporator becomes unstable.

In this case, for example, when the refrigerant is excessively supplied to the evaporator, the refrigerant that does not evaporate remains, and a phenomenon called a liquid bag that is sucked into the compressor 3 in a liquid state occurs. Causes damage. On the other hand, if the supply amount of the refrigerant to the evaporator is small, only a capacity lower than the original refrigerating capacity of the evaporator is obtained, and the refrigeration efficiency is deteriorated. All of these phenomena cause an increase in the power consumption of the compressor 3.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has an object to provide a cooling device and a cooling method for a vending machine capable of appropriately maintaining a supply amount of refrigerant to an evaporator to improve refrigeration efficiency and save energy. The task is to provide.

[0009]

SUMMARY OF THE INVENTION The above objects are attained by an evaporator disposed in a plurality of compartments which are thermally partitioned, a compressor and a condenser disposed outside the compartment, and each of the evaporators. A vending machine provided with flow rate control means for controlling the amount of refrigerant supplied from the condenser to each of the evaporators, respectively, disposed on the upstream side of the evaporator. Superheat detecting means for detecting the superheat of the refrigerant in the heat exchanger, electronic expansion valves respectively arranged as the flow control means, and adjusting the opening of each of the electronic expansion valves based on the detection result of the superheat detecting means. Vending machine cooling device comprising:

That is, in the cooling device for a vending machine according to the first aspect of the present invention, an electronic expansion valve is provided as flow control means, and the opening of each electronic expansion valve is adjusted based on the degree of superheat of the refrigerant in the evaporator. In this way, a proper flow rate of the refrigerant is supplied to each evaporator to efficiently cool the inside of the refrigerator.

Another object is to circulate a refrigerant between an evaporator disposed in a thermally partitioned storage and a compressor and a condenser disposed outside the storage, thereby forming a refrigerant in the storage. In the method of cooling a vending machine for cooling, an electronic expansion valve capable of adjusting a flow rate of a refrigerant is provided on the upstream side of the evaporator, and the degree of opening of the electronic expansion valve is fixed to supply the refrigerant to the evaporator. One step, and after the first step, a second step of sequentially controlling the opening of the electronic expansion valve to supply the refrigerant to the evaporator so that the degree of superheat of the refrigerant in the evaporator becomes a predetermined value. And a method of cooling a vending machine.

[0012] Alternatively, the above-mentioned problem is solved by circulating a refrigerant between an evaporator disposed in a plurality of thermally partitioned compartments and a compressor and a condenser disposed outside the compartment. In a cooling method of a vending machine for cooling an inside of a refrigerator, an electronic expansion valve capable of adjusting a flow rate of a refrigerant is provided on an upstream side of each of the evaporators. A first step of supplying a refrigerant to the evaporator, and after this first step, sequentially and independently controlling the opening degree of each of the electronic expansion valves so that the degree of superheat of the refrigerant in each of the evaporators becomes a predetermined value. And a second step of supplying a refrigerant to each of the evaporators.

That is, in the cooling method for a vending machine according to the sixth and seventh aspects of the present invention, when controlling the opening of the electronic expansion valve provided as the flow rate adjusting means, the opening of the electronic expansion valve is performed as a first step. After the refrigerant is circulated at a fixed temperature, as a second step, the refrigerant is circulated by sequentially controlling the degree of opening of the electronic expansion valve so that the degree of superheat of the refrigerant in the evaporator becomes a predetermined value. In this case, appropriate flow rate control of the refrigerant is always performed.

Here, in the configuration in which the inside of the storage is divided into a plurality of parts and the evaporators are arranged in each of the storages, the opening degree of the electronic expansion valve of each evaporator is determined in the first step. In the second step, the opening degree of each of the electronic expansion valves is sequentially and independently controlled so that the degree of superheat becomes a predetermined value. This makes it possible to efficiently cool the inside of each storage.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a piping system of a cooling device of a vending machine according to a first embodiment of the present invention. In the figure, parts corresponding to those of the cooling device of the conventional vending machine described with reference to FIG. 7 are denoted by the same reference numerals.

The interior of the compartment is divided into three compartments, a left compartment 1A, a middle compartment 1B, and a right compartment 1C, with a heat insulating material 7 interposed therebetween. In the present embodiment, the left warehouse 1A is configured as a warehouse that sells cold drinks throughout the year, and the middle warehouse 1B and the right warehouse 1C are configured as warehouses that sell cold drinks or hot drinks according to the season. That is, only the evaporator 2A as a cooler is disposed in the left warehouse 1A, whereas the evaporators 2B, 2
C and heaters 12B and 12C as heaters are arranged.

[0018] Evaporators 2A to 2C arranged in each of the storages 1A to 1C.
2C is connected in parallel to a compressor (compressor) 3 and a condenser 4 arranged outside the storage, respectively, and each storage 1A to 1C
A refrigeration circuit for cooling the inside is configured. Therefore, in the present embodiment, electronic expansion valves 15A, 15B and 1 are provided between the condenser 4 and the evaporators 2A to 2C as flow rate adjusting means.
5C is provided. Each of the electronic expansion valves 15A to 15C has a pulse motor (or stepping motor) 1
6A, 16B and 16C are provided, and an electronic expansion valve 15 is provided by pulse motors 16A to 16C driven based on a pulse signal supplied from the control means 20 as described later.
The opening degrees of A to 15C are adjusted.

Inlet and outlet temperature sensors 17A, 17B, 17C and outlet temperature sensors 18 for detecting the temperature of the refrigerant are provided at the inlet and outlet of each of the evaporators 2A to 2C.
A, 18B and 18C are installed respectively. The outputs of these temperature sensors 17A to 17C and 18A to 18C are supplied to the control means 20, and the temperature difference of the refrigerant at the entrance and exit of the evaporator, that is, the degree of superheat, is calculated for each of the evaporators 2A to 2C.

In the present embodiment, each electronic expansion valve 15
A to 15C function as shutoff valves for shutting off the outflow of the refrigerant when fully closed, respectively, when the inside temperature sensors 9A, 9B and 9C detect that the warehouses 1A to 1C have been cooled below the set temperature. , Corresponding electronic expansion valve 15A
To 15C are completely closed, the supply of the refrigerant to the evaporators 2A to 2C is stopped, and the cooling operation in the refrigerator is stopped. In addition, 1A-1
When C is cooled below the set temperature, the operation of the compressor 3 is stopped as described later. Although not shown, it is assumed that a check valve for preventing a backflow of the refrigerant from the compressor 3 to the evaporators 2A to 2C is provided upstream of the compressor 3.

Next, the operation of the present embodiment will be described. In the present embodiment, a case will be described in which all the refrigerators 1A to 1C are cooled.

Referring to FIG. 4, after the compressor 3 is started, first, the refrigerant is supplied to each of the evaporators 2A to 2C in a state where the opening of each of the electronic expansion valves 15A to 15C is fixed to a predetermined opening. One step is performed (step S1).
At this time, the opening degree of each of the electronic expansion valves 15A to 15C is fixed to a predetermined opening ratio with respect to the total opening degree of all the electronic expansion valves, and the total of these opening degrees is the refrigerant at the outlet of the condenser 4. Determined based on temperature. This refrigerant temperature is detected by a temperature sensor 19 installed on the outlet side pipe portion of the condenser 4.

The predetermined opening ratio of each of the electronic expansion valves 15A to 15C described above is calculated in advance by each of the evaporators 2A to 2C.
Is determined by the ideal simulation result of the refrigerating capacity. This takes into account the fact that the form of the evaporator is determined from the volume in the refrigerator, the number, shape, size, and the like of the stored products. In addition, the sum of the degrees of opening of the electronic expansion valves 15A to 15C is determined as a function of the refrigerant temperature at the outlet of the condenser 4. As a tendency, when the outlet temperature of the condenser 4 is high (the outside temperature and the refrigerant pressure are high), the total opening is reduced, and when the outlet temperature is low (the outside temperature and the refrigerant pressure is low), the total opening is small. To increase.

Next, in the fixed opening degree operation of each of the electronic expansion valves 15A to 15C, when the inlet temperature (Sin) of the refrigerant evaporators 2A to 2C falls below the predetermined temperature Sp, as a second step, each of the evaporators 2A to 15C is operated. Feedback control is performed to sequentially adjust the opening of each of the electronic expansion valves 15A to 15C so that the degree of superheat of 2C becomes a predetermined value (FIG. 3A, steps S2, S).
3). At this time, the opening degree of each of the electronic expansion valves 15A to 15C is
They are adjusted independently of each other based on the degree of superheat of the refrigerant in the corresponding evaporators 2A to 2C (FIG. 3B). In the present embodiment, R-407C is applied as a refrigerant, and the predetermined degree of superheat is set to, for example, 5 ° C. However, it goes without saying that the set degree of superheat is changed depending on the type of the applied refrigerant. .

In this second step, referring to FIG.
Refrigerant temperature Sout at the entrance and exit of each evaporator 2A-2C,
The PID of the opening degree of each of the electronic expansion valves 15A to 15C so that the superheat degree y _SH which is the difference between Sin and the target value (predetermined value) yref.
Control (a control method including three operations of a proportional operation, an integral operation, and a differential operation of the deviation e) is performed (Step S).
3) In order to further improve the responsiveness, the disturbance compensation signal calculated based on the outlet temperature Sout of the evaporator is added to the PID control signal to adjust the opening of the electronic expansion valves 15A to 15C (step S4). .

As described above, the fixed opening degree operation of each of the electronic expansion valves 15A to 15C is performed as the first step before the second step because feedback control is performed from the beginning when there is almost no refrigerant and when the refrigerant is not cooled. In view of the fact that the degree of superheat may be the same when the amount is large,
After the refrigerant is circulated to the steady state in the step, the process proceeds to the second step.

Further, in the second step, disturbance compensation is added to the PID control, but the PID control alone follows the PID control with sufficient responsiveness when the evaporator outlet temperature Sout of the refrigerant suddenly starts dropping due to disturbance. Therefore, the temperature of the evaporator outlet of the refrigerant is separately monitored and a compensation signal is added to the PID signal to maintain a predetermined degree of superheat (see FIG. 3A). Thereby, the so-called liquid back phenomenon can be suppressed, and damage to the compressor 3 can be prevented.

Therefore, according to the present embodiment, the superheat degree of the refrigerant in the evaporators 2A to 2C can be maintained at a predetermined temperature by the electronic expansion valves 15A to 15C, so that the supply amount of the refrigerant can be adjusted. It is possible to continue supplying an appropriate amount of refrigerant to the units 2A to 2C, and it is possible to significantly reduce the power consumption of the compressor 3. Also, since the occurrence of the liquid back is prevented as much as possible, the cooling capacity is slightly reduced by the amount of the coolant supply, but the power consumption is reduced as a whole. Cooling system coefficient of performance (COP = cooling capacity /
Power consumption) (see FIG. 3C).

By continuing the above operation, when the temperature of the refrigerators 1A to 1C becomes equal to or lower than the set temperature R, the electronic expansion valves 15A to 15C are fully closed to stop the cooling operation, and the evaporators 2A to 2C are operated. The supply of the refrigerant is stopped (steps S5 and S6).

Note that not all of the refrigerators 1A to 1C always reach the set temperature R at the same time, and the supply of the refrigerant is shut off in order from the refrigerator which has reached the temperature. In this case, the amount of the refrigerant flowing toward the remaining evaporator increases due to the change in the number of operating evaporators, but the cooling capacity of the remaining evaporator varies because the appropriate amount of refrigerant is maintained by the electronic expansion valve. Will not occur.

When all the refrigerators 1A to 1C reach the set temperature R, the operation of the compressor 3 is stopped. Therefore, in the present embodiment, the compressor operation time tc counted after the fully-closed operation of the electronic expansion valve whose opening degree has been controlled to the end is counted, and after the predetermined time t (for example, 60 seconds) elapses, the compressor 3 Is stopped (steps S7 and S8). Thereby, each evaporator 2A
2C can be removed, the responsiveness of the superheat degree of the refrigerant can be improved when the compressor 3 is restarted, the cooling efficiency can be increased, and the load on the compressor 3 can be reduced to save power. Energy can be achieved.

When the temperature in the refrigerator rises and exceeds the set temperature, the compressor 3 is started again, and the above-described operations (steps S1 to S8) are repeated.

FIG. 5 shows a second embodiment of the present invention. In the figure, the same reference numerals are given to portions corresponding to the above-described first embodiment, and the detailed description thereof will be omitted.

In this embodiment, the inlet-side temperature sensors 17B, 1B installed at the inlet-side pipes of the evaporators 2B, 2C.
The difference from the configuration of the above-described first embodiment is that 7C is omitted. That is, the inlet side temperature sensor 17A installed on the side of the evaporator 2A is shared by the other evaporators 2B and 2C, and the number of installed temperature sensors is reduced.

That is, if the degree of opening of each of the electronic expansion valves 15A to 15C is different, the amount of refrigerant flowing into each of the evaporators 2A to 2C is, of course, different.
It has been experimentally confirmed that the pressures (i.e., temperatures) on the inlet sides of A to 2C are almost equal. This allows
The temperature of the refrigerant flowing into the other evaporators 2B and 2C can be estimated only by the inlet-side temperature sensor 17A on the side of the evaporator 2A, and it is possible to contribute to energy saving by omitting the temperature sensor.

However, since the inlet temperature of the plurality of evaporators 2A to 2C is detected only by the inlet-side temperature sensor 17A, the chamber 1A reaches the set temperature R, the electronic expansion valve 15A is fully closed, and the evaporator 2A is moved to the evaporator 2A. When the supply of the refrigerant is interrupted, the degree of superheat of the refrigerant in the other evaporators 2B and 2C cannot be detected, and there is a possibility that control of the electronic expansion valves 15B and 15C may be hindered.

Therefore, in the present embodiment, the electronic expansion valve 15
A is configured such that a minimum flow rate of refrigerant that can be detected by the inlet-side temperature sensor 17A at the minimum opening is allowed to flow out of the other evaporators 2B, 2B
While the inlet-side refrigerant temperature of C can be estimated, the cooling operation of the refrigerator 1A is hardly generated.

As another configuration example, the electronic expansion valve 15A is provided with a function as a shut-off valve when the electronic expansion valve 15A is fully closed, and the minimum flow rate at which the temperature can be detected by the inlet-side temperature sensor 17A at predetermined time intervals. The opening may be adjusted to allow the refrigerant to flow out. The predetermined time is set, for example, at a timing at which the temperature is detected by the temperature sensor 17A.

Since the cooling method of the cooling device according to the present embodiment is the same as that of the first embodiment, the description thereof will be omitted.

Next, a third embodiment of the present invention will be described. In the present embodiment, the compressor 3 is configured to be driven by inverter control. That is,
The driving speed of the compressor 3 is made variable so that the discharge amount of the refrigerant can be changed in accordance with the operating conditions.

As a specific control method, for example, as shown in FIG. 6, predetermined rotational speeds F1, F2 and F3 (F1 <F2 <F3) are prepared for each number of operating evaporators 2A to 2C. The number of rotations of the compressor 3 is controlled in accordance with the number of operating evaporators 2A to 2C. The number of operating evaporators 2A to 2C can be detected based on the total value of the opening degrees of electronic expansion valves 15A to 15C.

When the number of operating evaporators 2A to 2C is one, the amount of refrigerant circulating in the refrigeration circuit may be equivalent to one evaporator, so the rotation speed is adjusted to the lowest F1. Similarly to the embodiment, the opening degree of the corresponding electronic expansion valve is controlled so as to maintain the predetermined degree of superheat (steps T1, T2, T
3). On the other hand, the number of operating evaporators 2A to 2C is two or three.
If so, the rotation speed of the compressor 3 is adjusted to F2 or F3 to increase the refrigerant discharge amount accordingly (steps T6, T7, T8).

As described above, according to the present embodiment, the discharge amount of the refrigerant can be changed according to the number of operating evaporators 2A to 2C, so that the driving power of the compressor 3 can be suppressed. , Electronic expansion valves 15A to 15
The load applied to the opening control of C can be reduced, and the control means 20 can be simplified and the durability of the electronic expansion valve can be improved.

It should be noted that all of the storages 1A to 1C are set at the set temperature R.
Is reached, the operation of the compressor 3 is stopped through the same compressor stop flow (step T5) as in steps S7 and S8 (see FIG. 4) described in the first embodiment.

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited to these embodiments.
Various modifications are possible based on the technical idea of the present invention.

For example, in each of the above-described embodiments, the cooling device of the vending machine including the three refrigerators 1A to 1C has been described, but the number of refrigerators is not limited to this.

In each of the above embodiments, the evaporator 2A
To control the degree of superheating of the refrigerant to a predetermined value
Although the ID control method is applied, a PD control method excluding the integration operation or another control method can be adopted.

Further, in the third embodiment described above, the driving speed of the compressor 3 is made variable in accordance with the number of operating evaporators 2A to 2C. ), The driving speed may be changed. The temperature outside the refrigerator can be estimated from the output of the temperature sensor 19 installed at the outlet side pipe portion of the condenser 4.

[0049]

As described above, according to the present invention, the following effects can be obtained.

According to the vending machine cooling device of the present invention,
A proper flow rate of refrigerant can be supplied to each evaporator to efficiently cool the inside of the refrigerator and reduce power consumption. According to the second to fifth aspects of the present invention, the degree of superheating of the refrigerant in the evaporator can be properly detected, and the number of installed sensors can be reduced to reduce the apparatus cost.

Further, according to the method for cooling a vending machine of the present invention, it is possible to always perform appropriate flow control of the refrigerant to the evaporator. The effect can be obtained quickly, which can greatly contribute to improvement of cooling efficiency and reduction of power consumption.

According to the twelfth and thirteenth aspects of the present invention, the compressor can be operated in accordance with the operation state of the vending machine. And claim 1
According to the invention of the fourth aspect, an excellent cooling capacity can be obtained quickly from the start of the start of the compressor, which can greatly contribute to energy saving.

[Brief description of the drawings]

FIG. 1 is a piping diagram of a cooling device of a vending machine according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a cooling method of the vending machine.

FIG. 3 is a time chart of each parameter according to the same method, where A is the relationship between the outlet temperature and the inlet temperature of the evaporator of the refrigerant, B is an example of adjusting the opening degree of the electronic expansion valve, and C is the cooling capacity and consumption. The relationship with power is shown.

FIG. 4 is a flowchart illustrating an operation of the first exemplary embodiment of the present invention.

FIG. 5 is a piping diagram of a cooling device of a vending machine according to a second embodiment of the present invention.

FIG. 6 is a flowchart for explaining the operation of the third embodiment of the present invention.

FIG. 7 is a piping diagram of a cooling device of a conventional vending machine.

[Explanation of symbols]

 1A Left warehouse 1B Middle warehouse 1C Right warehouse 2A Evaporator 2B Evaporator 2C Evaporator 3 Compressor 4 Condenser 15A Electronic expansion valve 15B Electronic expansion valve 15C Electronic expansion valve 17A Inlet temperature sensor 17B Inlet temperature sensor 17C Inlet temperature sensor 18A Outlet temperature sensor 18B Outlet temperature sensor 18C Outlet temperature sensor 20 Control means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuaki Nagayama 5-6-6 Koyodai, Ryugasaki-shi, Ibaraki Pref. VM-PT within Kubota Ryugasaki Plant (72) Inventor Nobuhiko Tanaka 5-6-koyodai, Ryugasaki-shi, Ibaraki Inside the Kubota Ryugasaki Plant VM-PT (72) Inventor Hiromitsu Kowada 5--6 Koyodai, Ryugasaki City, Ibaraki Prefecture Inside the VM-PT Kubota Ryugasaki Plant VM-PT (72) Inventor Tanewa Chiba, Koyodai, Ryugasaki City, Ibaraki Prefecture 5th-6th F-term in the Kubota Ryugasaki Plant VM-PT (reference) 3E044 AA01 CC08 DB16 FB11 3L045 AA02 AA03 JA13 JA14 LA05 LA06 MA04 MA12 NA01 NA16

Claims (14)

[Claims] An evaporator disposed in each of a plurality of compartments thermally partitioned; a compressor and a condenser disposed outside the compartment; and a condenser disposed upstream of each of the evaporators. A vending machine provided with flow control means for controlling the amount of refrigerant supplied to each of the evaporators from each of the evaporators, wherein the superheat degree of the refrigerant in each of the evaporators is detected by being disposed in each of the evaporators. A vending machine comprising superheat detection means, an electronic expansion valve arranged as the flow control means, and control means for adjusting the opening of each of the electronic expansion valves based on the detection result of the superheat detection means. Cooling system. 2. The automatic heating apparatus according to claim 1, wherein said superheat degree detecting means comprises an inlet-side temperature sensor and an outlet-side temperature sensor installed at each of pipes at an inlet and an outlet of said evaporator. Vending machine cooling system. 3. The method according to claim 1, wherein the inlet side temperature sensor and the outlet side temperature sensor are provided in at least one of the plurality of evaporators, and only the outlet side temperature sensor is provided in the remaining evaporators. The cooling device of a vending machine according to claim 2, wherein 4. The electronic expansion valve on the one evaporator side is configured to allow a refrigerant having a flow rate that can be detected by the inlet-side temperature sensor to flow out at the time of the minimum opening degree, and the remaining electronic expansion valve is a refrigerant when fully closed. The cooling device for a vending machine according to claim 3, wherein the cooling device is configured to be able to block outflow of water. 5. Each of the electronic expansion valves has a function as a shut-off valve, and the electronic expansion valve on the one evaporator side supplies a refrigerant having a flow rate detectable by the inlet side temperature sensor at predetermined time intervals. The cooling device for a vending machine according to claim 3, wherein the opening is adjusted so that the opening can flow out. 6. An automatic vending machine for cooling the interior of a refrigerator by circulating a refrigerant between an evaporator arranged in a thermally partitioned warehouse and a compressor and a condenser arranged outside the warehouse. In the method for cooling the machine, a first step of providing an electronic expansion valve capable of adjusting the flow rate of the refrigerant upstream of the evaporator, supplying the refrigerant to the evaporator with the opening of the electronic expansion valve fixed, After the first step, a second step of sequentially controlling the opening degree of the electronic expansion valve to supply the refrigerant to the evaporator so that the degree of superheat of the refrigerant in the evaporator becomes a predetermined value. Characteristic cooling method for vending machines. 7. The inside of the refrigerator is cooled by circulating a refrigerant between an evaporator disposed in each of a plurality of thermally partitioned refrigerators and a compressor and a condenser disposed outside the refrigerator. In the vending machine cooling method, electronic expansion valves capable of adjusting the flow rate of the refrigerant are provided on the upstream side of each of the evaporators, and the opening degree of each of the electronic expansion valves is fixed, and the refrigerant is supplied to each of the evaporators. A first step of supplying, and after this first step, sequentially and independently controlling the opening degree of each of the electronic expansion valves so that the degree of superheat of the refrigerant in each of the evaporators becomes a predetermined value. To supply refrigerant to the second
And v. Cooling the vending machine. 8. The automatic operation according to claim 7, wherein in the first step, the opening degree of each of the electronic expansion valves is fixed to a predetermined opening ratio with respect to the total opening degree. Vending machine cooling method. 9. The cooling method for a vending machine according to claim 8, wherein a total of the opening degrees of the electronic expansion valves is determined based on a refrigerant temperature at an outlet of the condenser. 10. The electronic expansion valve according to claim 2, wherein a disturbance compensation signal calculated based on a refrigerant temperature at an outlet of the evaporator is added to a PID or PD control signal having the predetermined value as a target value. 8. The cooling method for a vending machine according to claim 6, wherein an opening of the vending machine is adjusted. 11. The method according to claim 6, wherein the switching from the first step to the second step is performed when a refrigerant temperature at an inlet of the evaporator falls below a set value. The vending machine cooling method according to any one of the above. 12. The method for cooling a vending machine according to claim 6, wherein said compressor is driven by inverter control. 13. The vending machine cooling method according to claim 12, wherein the number of revolutions of the compressor is controlled based on the total opening of the electronic expansion valves. 14. The compressor according to claim 6, wherein the operation of the compressor is stopped a predetermined time after all the electronic expansion valves are fully closed. Vending machine cooling method.