JP4379322B2 - Vending machine cooling system - Google Patents

Description

  The present invention relates to a cooling device for a vending machine that cools, heats, and sells a product such as a beverage in a container such as a can, a bottle, a pack, or a plastic bottle.

A refrigerant cooling circuit for cooling the inside of a heat-insulated housing (for example, inside a vending machine) forms a refrigerant circulation path by combining a compressor, radiator, throttle, and evaporator, and a series of refrigeration units. A refrigerant is circulated by executing a cycle. As a refrigerant circulating in the refrigerant cooling circuit, HF refrigerant (hydrofluorocarbon) is generally used today. However, from the viewpoint of protecting the global environment, there is a demand for the development of a refrigerant that has less influence on the global environment. Therefore, recently, the development of a refrigerant cooling circuit that uses carbon dioxide as a refrigerant that does not adversely affect the human body in terms of nonflammability, safety, noncorrosiveness, and less impact on the ozone layer has been promoted. Yes.
By the way, when carbon dioxide is used as the refrigerant in the refrigerant cooling circuit, the critical temperature of carbon dioxide is as low as about 31 ° C. Therefore, in the radiator, supercriticality that does not liquefy even if the carbon dioxide refrigerant is radiated at normal outside air temperature. May cause pressure conditions. In this case, the pressure on the high-pressure side of the refrigerant cooling circuit (the refrigerant circulation path from the compressor output to the input of the throttle) increases, and the low-pressure side of the refrigerant cooling circuit (from the output of the throttle to the compressor input). The amount of refrigerant in the refrigerant circulation path to the part decreases. That is, the compressor performs a low-efficiency overload operation, and further stops when the overload operation reaches a limit.

Therefore, as a method for solving the above-described problem, a method in which refrigerant amount adjusting means such as an accumulator and a receiver is provided in the refrigerant circulation path is known (for example, Patent Document 1).
In addition, when an electronic expansion valve is provided in the refrigerant circulation path and the high pressure side is above the critical pressure, the valve circuit is opened to increase the pressure on the low pressure side and increase the amount of refrigerant in the low pressure side pipe to increase the pressure in the high pressure side pipe. There is also a method of reducing the volume of the refrigerant (for example, Patent Document 2).
Japanese National Patent Publication No. 7-502335 JP 2004-54424 A

However, the conventional apparatus described in Patent Document 1 requires a dedicated space for disposing the refrigerant amount adjusting means, and thus there is a problem that cannot be handled by a small heat insulating casing. Further, since the refrigerant amount adjusting means is added, there is a problem that the product cost increases. Moreover, in the conventional apparatus described in Patent Document 2, since the temperature of the refrigerant rises when the pressure on the low pressure side is increased, the temperature difference between the internal air and the refrigerant becomes small, resulting in a problem that the cooling capacity is lowered.
Therefore, the present invention provides a vending machine cooling device capable of executing a stable refrigeration cycle without using the refrigerant amount adjusting means when the refrigerant is in a supercritical pressure state on the high pressure side of the refrigerant cooling circuit. The purpose is to do.

In order to achieve the above object, a vending machine cooling device according to claim 1 of the present invention is installed in each of a plurality of product storages to evaporate a refrigerant to cool the product storages. A compressor for compressing the refrigerant supplied from the evaporation means, a heat radiating means for radiating heat from the refrigerant supplied from the compressor, a throttle means for adjusting the flow rate of the refrigerant supplied from the heat radiating means, and the product It has an internal temperature detecting means for detecting the internal temperature of the storage, and a critical pressure detecting means for detecting the critical pressure of the refrigerant flowing in the heat radiating means, and evaporates according to the detection result of the internal temperature detecting means. In a vending machine cooling device having a control means for controlling the operation and suspension of the means,
In the case where a plurality of storages are cooled, if the detection result of the critical pressure detection means has reached the upper limit value of the critical pressure, the control means for operating by injecting refrigerant into the dormant evaporator It is provided with.

A cooling device for a vending machine according to claim 2 of the present invention is the above claim 1,
The throttle means is an electronic expansion valve that controls the opening of the throttle, and the compressor is an inverter compressor that controls the rotational speed, and the detection result of the critical pressure detection means has reached the upper limit value of the critical pressure. lever, opening the opening of the electronic expansion valve, and / or characterized by comprising a control means for reducing the rotational speed of the inverter compressor.
A cooling device for a vending machine according to claim 3 of the present invention is characterized in that in any one of claims 1 and 2, carbon dioxide is used as a refrigerant.

According to the cooling device according to claim 1 of the present invention, when the pressure of the radiator on the high pressure side exceeds the critical pressure, the piping volume on the low pressure side is increased by flowing the refrigerant through the evaporator that is at rest. The refrigerant volume on the high-pressure side is reduced and the rise in pressure can be suppressed. As a result, the compressor can be stopped and damaged, and the lowering of the evaporation temperature in the evaporator during operation can be suppressed. Can be maintained.
Further, according to the cooling device according to claim 2 of the present invention, when the pressure of the radiator on the high pressure side exceeds the critical pressure, the refrigerant volume on the low pressure side is expanded by opening the opening of the electronic expansion valve. Moreover, since the refrigerant volume on the high pressure side is reduced by reducing the number of revolutions of the inverter compressor, it is possible to suppress an increase in the pressure in the radiator, so that the refrigerant in the radiator has a critical point. The compressor can be prevented from being stopped and damaged, and a stable cooling capacity can be maintained.

  In addition, according to the cooling device according to claim 3 of the present invention, by using carbon dioxide as a refrigerant, a cooling device for a vending machine excellent in nonflammability and safety without affecting the ozone layer is provided. it can.

Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments.
(Embodiment 1) FIGS. 1 to 5 are explanatory views of an embodiment showing a form of a cooling device according to the present invention according to claims 1 to 3. FIG. 1 is a front view of a vending machine equipped with a cooling device, FIG. 2 is a cross-sectional view of the vending machine, FIG. 3 is a refrigerant circuit of the cooling device, FIG. 4 is a control block diagram of the vending machine, and FIG. The principal part flowchart of a control apparatus is shown.
1 and 2, the vending machine includes a main body cabinet 1. The main body cabinet 1 is formed as a rectangular heat insulator having an open front surface. The main body cabinet 1 is provided with an outer door 2 and inner doors 3a and 3b on the front surface thereof, and three independent commodity containers 5a partitioned by, for example, two heat insulating partition plates 4a and 4b. 5b and 5c are provided in a side-by-side manner. More specifically, the outer door 2 is for opening and closing the front opening of the main body cabinet 1, and the inner doors 3a and 3b are for opening and closing the front surfaces of the product containers 5a, 5b and 5c. is there. The inner doors 3a and 3b are divided into upper and lower parts, and the upper door 3a opens and closes when a product is replenished. The product storage 5a, 5b, 5c is for storing the product W such as a canned beverage or a beverage containing a plastic bottle while maintaining the desired temperature, and the capacity of the storage is 5a, 5c, 5b. It is small in order of.

The product storage 5a, 5b, 5c is provided with a product storage rack 6, a carry-out mechanism 7 and a product carry-out shooter 8, respectively. The product storage rack 6 is for storing the products W in a manner of being arranged along the vertical direction. The carry-out mechanism 7 is provided at the lower part of the product storage rack 6, and is used to carry out the products W at the bottom of the product group stored in the product storage rack 6 one by one. The product carry-out shooter 8 is for guiding the product W carried out from the carry-out mechanism 7 on the surface thereof to the product take-out port 3c, and a large number of holes are formed in the surface to allow the cooling and heating air to pass therethrough. It is like that.
In the machine cabinet 9 which is the exterior of the product storage 5a, 5b, 5c inside the main body cabinet 1, cooling configured with the evaporation units 50a, 50b, 50c installed at the bottom of the product storage 5a, 5b, 5c. A device 10 is provided.

FIG. 3 is a refrigerant circuit diagram conceptually showing the cooling device (cooling device according to the embodiment of the present invention) shown in FIGS. 1 and 2. In the figure, the cooling device 10 includes a compressor 20, a heat radiating unit 30, electronic expansion valves 40a, 40b, and 40c (hereinafter also simply referred to as electronic expansion valves 40), and evaporation units 50a, 50b, and 50c (hereinafter referred to as electronic expansion valves 40). Simply referred to as an evaporation unit 50) and an internal heat exchanger 60. In this cooling device 10, as a refrigerant, carbon dioxide is used which has non-flammability, safety and non-corrosion properties and has little influence on the ozone layer.
The compressor 20 compresses the refrigerant (carbon dioxide) from the evaporation unit 50 to a high temperature and high pressure state. The compressor 20 is a two-stage inverter compressor that performs a compression operation in two steps. More specifically, the compressor 20 includes a first compressor 21 that performs a first (first) compression operation and a second compressor 22 that performs a second (last) compression operation. An intermediate heat exchanger 23 is provided between them. The intermediate heat exchanger 23 cools the refrigerant compressed by the first compression operation by the first compressor 21, that is, releases the heat to return the refrigerant to the second compressor 22.

Thus, the compressor 20 can compress the refrigerant to a desired high temperature and high pressure state with low power consumption by executing the compression operation twice through the intermediate heat exchanger 23. In the present embodiment, under operating conditions below the critical pressure of the refrigerant, the refrigerant is compressed to about 4.9 MPa by the first compression by the first compressor 21 and the second time by the second compressor 22. Compress the refrigerant to about 9.8 MPa. Under operating conditions that exceed the upper limit of the critical pressure of the refrigerant, the number of revolutions of the compressor is reduced to enable an appropriately stable cooling operation.
An oil separator 24 is connected to the compressor 20. The oil separator 24 is for returning the refrigeration oil sent from the compressor 20 (second compressor 22) to the compressor 20 (first compressor 21). The refrigerating machine oil prevents friction and refrigerant leakage inside the compressor 20, but it is difficult to completely seal the refrigerating machine oil inside the compressor 20. In particular, as described above, the compressor 20 compresses the refrigerant to a high pressure, and this pressure is much higher than when a conventional refrigerant (for example, HFC (hydrofluorocarbon)) is used. The amount of refrigeration oil delivered from 20 increases. Therefore, in the present embodiment, an oil separator 24 is connected between the outlet side of the second compressor 22 and the inlet side of the first compressor 21, and the refrigerating machine oil sent from the second compressor 22 is supplied. The first compressor 21 is returned. Reference numeral 25 in FIG. 3 is a capillary tube for reducing the pressure of the refrigerating machine oil and the refrigerant returning to the compressor 20.

Here, as the compressor 20, a reciprocating compressor, a rotary compressor, or a scroll compressor may be used as a compressor commensurate with an object, environment, or cost required for the entire apparatus. .
The heat dissipation unit 30 liquefies the refrigerant by radiating heat from the refrigerant compressed to a high temperature and high pressure state by the compressor 20. The heat dissipation unit 30 in the present embodiment uses a fin tube type composed of copper tubes and aluminum fins. In addition, a radiator temperature sensor 110 as a critical pressure detecting means is installed at the inlet of the heat radiating unit 30 to monitor the critical pressure of the heat radiating unit 30 and detects the critical pressure of the heat radiating unit 30 as the critical temperature of the refrigerant. To do. The critical pressure detecting means may be a pressure sensor.
The electronic expansion valve 40 adiabatically expands the refrigerant radiated by the heat radiating unit 30, that is, adjusts the refrigerant to a low temperature and low pressure state by reducing the pressure. One electronic expansion valve 40 is connected to each evaporation unit 50, and its opening degree is changed by a control command to control the refrigerant circulation amount.

The evaporation unit 50 evaporates the refrigerant adiabatically expanded to a low temperature and low pressure state by the electronic expansion valve 40. As the refrigerant evaporates, the area around the evaporation unit 50 is deprived of heat and cooled.
As shown in FIG. 2, the evaporating unit 50 is disposed inside the plurality of commodity storages 5a, 5b, 5c and independently cools each of the commodity storages 5a, 5b, 5c. It is. The evaporation unit 50 includes an evaporator 51, a solenoid valve 52, and an internal fan 53. Each of the evaporation units 50a, 50b, and 50c has an electronic expansion valve 40a on each path branched in three directions from the internal heat exchanger 60. , 40b, 40c. Furthermore, electromagnetic valves 52a, 52b, and 52c are provided in the respective paths, and by selectively opening the electromagnetic valves 52a, 52b, and 52c, the electronic expansion valve 40a is connected to the corresponding evaporation units 50a, 50b, and 50c. , 40b, 40c are sent out. On the other hand, the paths on the outlet side of the respective evaporation units 50 a, 50 b, 50 c are gathered together and connected to the first compressor 21 of the compressor 20.

The internal fan 53 supplies air cooled by the evaporator 51 (cold air) or air heated by the heater H (warm air) to produce cold heat from the evaporator 51 or high heat from the heater H. Heat is transferred to W. The air blown by the internal fan 53 is circulated through the circulation duct D. The internal fan 53 can control the air volume by changing the number of rotations according to a control command. The internal temperature sensor 72 is for detecting the temperature in the commodity storage 5, and is installed on the upper part of the fan cover 71 that covers the internal fan 53. A refrigerant circulation path L for circulating the refrigerant is formed by the compressor 20, the heat radiating unit 30, the electronic expansion valve 40 and the evaporation unit 50, the path connecting them, and the like. The refrigerant circulation path L is provided with an internal heat exchanger 60. The internal heat exchanger 60 exchanges heat between the high-pressure refrigerant from the heat radiating unit 30 and the low-pressure refrigerant from the evaporation unit 50 . More specifically, inside the internal heat exchanger 60, a refrigerant pipe 61 through which the refrigerant radiated by the heat radiating unit 30 flows and a refrigerant pipe 62 through which the refrigerant evaporated by the evaporation unit 50 flows are mutually connected. They are arranged in a non-contact countercurrent manner with a heat exchangeable distance.

  FIG. 4 is a diagram showing a control block in the control device of the vending machine. The control device 100 detects the temperature of the radiator 31 and the temperature of the product storage 5 by the operation mode set to cool or heat the product storage 5a, 5b, 5c, and operates the cooling device 10 and the heater H. And the product W in the product storage 5 is set to a desired temperature. The control device 100 will be described in more detail. An operation mode selection switch 105 that sets an operation mode for cooling or heating the product storage 5a, 5b, 5c, a radiator temperature sensor 110 that detects an inlet temperature of the radiator 31, Inputs are internal temperature sensors 72a, 72b, 72c for detecting the internal temperature of the product storage 5a, 5b, 5c, and the compressor 20 is started and stopped, the number of rotations, the heater H is started and stopped, and the electronic expansion valves 40a and 40b. , 40c, opening / closing of the solenoid valves 52a, 52b, 52c, and the rotational speed of the internal fans 53a, 53b, 53c.

The cooling device 10 having the above-described configuration can cool the internal atmosphere of the commodity storage 5a, 5b, 5c of the vending machine as follows. Here, the operation | movement is demonstrated as what cools the internal atmosphere of all the merchandise storage 5.
When cooling all the internal atmospheres of the commodity storages 5a, 5b, 5c, all the electromagnetic valves 52a, 52b, 52c are opened, and all the heaters H are turned off.
The refrigerant in the refrigerant circuit L is compressed in two by the compressor 20. More specifically, the refrigerant is compressed (compressed to about 4.9 MPa) by the first compressor 21 and then sent to the intermediate heat exchanger 23. The refrigerant sent to the intermediate heat exchanger 23 is cooled by releasing heat in the intermediate heat exchanger 23. The refrigerant cooled by the intermediate heat exchanger 23 is sent again to the second compressor 22 and is compressed (compressed to about 9.8 MPa) by the second compressor 22 to be in a high temperature and high pressure state. In this case, the refrigeration oil sent together with the refrigerant from the second compressor 22 returns to the inlet side of the first compressor 21 by the oil separator 24.

The high-temperature and high-pressure refrigerant is sent to the radiator 31 and is radiated and cooled by the radiator 31. The refrigerant cooled by the radiator 31 is sent to the electronic expansion valve 40 through the internal heat exchanger 60, and is decompressed and adiabatically expanded by the electronic expansion valve 40 to be in a low temperature and low pressure state.
The low-temperature and low-pressure refrigerant is sent to the evaporator 51 through the open electromagnetic valve 52. The refrigerant sent to the evaporator 51 evaporates by being given heat from the peripheral area of the evaporator 51. In other words, the peripheral region of the evaporator 51 is cooled by taking heat away from the evaporation of the refrigerant, thereby generating cold air. The generated cold air is blown out as indicated by the arrow in FIG. 2 by the action of the internal fan 53, whereby the internal atmosphere of the commodity storage 5 is cooled. When the internal atmosphere of the product storage 5 is thus cooled, the product W stored in the product storage rack 6 disposed in the product storage 5 is in a desired temperature state (for example, about 5 ° C. ) Will be cooled.

The refrigerant evaporated in the evaporation unit 50 is sent to the compressor 20 (first compressor 21) through the internal heat exchanger 60, compressed by the compressor 20, and the above cycle is repeated.
The control device 100 reads the operation mode (all cooling operations in this case) set by the operation mode selection SW, and rotates the rotation speed of the internal fan 53, the rotation speed of the inverter compressor 20, and the opening degree of the electronic expansion valve 40. Is set to a predetermined initial value, and a command for cooling operation is issued. If the temperature of the internal temperature sensor 72 reaches a predetermined internal cooling lower limit temperature (for example, 5 ° C.) in each product storage 5, the product W in the product storage 5 is sufficiently cooled. 52 is closed to stop the operation of the evaporator 51. Further, when the internal temperature rises due to external heat intrusion or the like and the internal temperature sensor 72 reaches the internal temperature upper limit (for example, 10 ° C.), the electromagnetic valve 52 is opened and the evaporator is opened. The operation is resumed at 51. The product W in the product storage 5 is held at a constant cooling temperature while repeating the on / off operation.

FIG. 5 is a flowchart showing the processing contents of control by the control device 100 when the temperature of the radiator temperature sensor 110 exceeds the critical temperature of the refrigerant, for example, when the outside air temperature is high. The processing contents of the control means 100 will be described in detail below with reference to this flowchart.
First, the control device 100 constantly monitors whether or not the compressor 20 of the cooling unit 10 is driven (step S1). When the compressor 20 is driven, that is, the vending machine is in an operating state. If there is, a process of detecting the current temperature of the radiator 31 is performed (step S2).
Based on the detection result, the control device 100 that has detected the current temperature of the radiator 31 determines that the radiator 31 reaches the critical pressure, and the temperature of the radiator temperature sensor 110 reaches the critical pressure upper limit (for example, 25 ° C.). If it has reached, a determination process is performed (step S3), and if it has reached, a process of lowering the temperature of the radiator 31 is performed (step S3 branch Y).

In the process of lowering the temperature of the radiator 31, first, the presence / absence of the evaporator 51 that is currently out of operation is determined (step S4). If there is an evaporator 51 that is not in operation (step S4 branch Y), the electromagnetic valve 52 is opened so that the refrigerant flows through the evaporator 51 (step S5). If the evaporator 51 is not in operation (step S4 branch N), the air volume of the cooling fan 53 during cooling is decreased (step S6). Next, in order to expand the refrigerant volume on the low pressure side, a process of opening the opening of the electronic expansion valve 40 in accordance with the internal temperature sensor 72 is performed (step S7). Next, in order to reduce the refrigerant volume on the high pressure side, a process for reducing the rotational speed of the compressor 20 is performed (step S8), and the process returns to the beginning. As a result, the refrigerant volume on the low-pressure side increases and the refrigerant volume on the high-pressure side decreases, so that the temperature of the radiator 31 decreases and the high-pressure pressure rise is suppressed. The control device 100 executes this control operation, and gradually opens the opening of the electronic expansion valve 40 until the temperature of the radiator temperature sensor 110 becomes equal to or lower than the critical pressure upper limit value (step S7), and gradually the compressor. The rotational speed of 20 is reduced (step S8).

When the temperature of the radiator temperature sensor 110 becomes equal to or lower than the critical pressure upper limit value (step S3 branch N), a process for determining whether the temperature of the radiator temperature sensor 110 is lower than the critical pressure lower limit value (for example, 20 ° C.) is performed. (Step S9). If the temperature of radiator temperature sensor 110 is higher than the critical pressure lower limit value (step S9 branch N), control device 100 keeps cooling unit 10 operating as it is and returns to the beginning of the process. If the temperature of the radiator temperature sensor 110 becomes lower than the critical pressure lower limit value (step S9 branch Y), the air volume of the internal fan 53, the opening degree of the electronic expansion valve 40, and the rotational speed of the compressor 20 are returned to the initial values. Return to the beginning of the process.
Note that only one of the opening control of the electronic expansion valve 40 in step S7 and the rotation speed control of the compressor 20 in step S8 may be performed. What is necessary is just to select suitably in consideration of the environmental conditions and cost in which the cooling device 10 of a vending machine is used.

  Accordingly, by repeatedly performing the above-described processing, when the pressure of the radiator 31 on the high-pressure side exceeds the critical pressure, the pipe volume on the low-pressure side is expanded by flowing the refrigerant through the evaporator 51 that is at rest. As a result of reducing the refrigerant volume on the side and suppressing the pressure rise, it is possible to avoid the stop and damage of the compressor 20, and to suppress the lowering of the evaporation temperature in the evaporator 51 during operation. Can be maintained in a state.

  As described above, the present invention is useful as, for example, a cooling device and a vending machine for cooling the internal atmosphere of a heat insulating housing.

It is front sectional drawing which showed typically the vending machine which concerns on embodiment of this invention. 1 is a cross-sectional side view schematically showing a vending machine according to an embodiment of the present invention. It is the refrigerant circuit figure which showed notionally the cooling device which concerns on embodiment of this invention. It is a control block diagram of the vending machine which concerns on Embodiment 1 of this invention. It is a principal part flowchart of the thermal radiation temperature process in control of the vending machine which concerns on Embodiment 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Cooling device 20 Compressor 21 1st compressor 22 2nd compressor 23 Intermediate heat exchanger 30 Radiation unit 31 Radiator 33 Auxiliary radiator 34 Solenoid valve 35 Solenoid valve 40 Electronic expansion valve 40 Evaporating unit 51 Evaporator 52 Solenoid valve 53 Internal fan 60 Internal heat exchanger 100 Control device 110 Radiator temperature sensor

Claims (3)

An evaporating unit that is installed in each of the plurality of product storage units to evaporate the refrigerant to cool the product storage unit, a compressor that compresses the refrigerant supplied from the evaporating unit, and a refrigerant supplied from the compressor Heat dissipation means for radiating heat, throttle means for adjusting the flow rate of the refrigerant supplied from the heat dissipation means, internal temperature detection means for detecting the internal temperature of the product storage, and critical pressure of the refrigerant flowing through the heat dissipation means In a vending machine cooling device having a control means for controlling the operation and suspension of the evaporation means according to the detection result of the internal temperature detection means,
In the case where a plurality of storages are in a cooling operation, the control means causes the refrigerant to flow into the evaporating means that is not in operation if the detection result of the critical pressure detection means has reached the upper limit value of the critical pressure. Vending machine cooling device, characterized by comprising control means for operating the vehicle. The throttle means is an electronic expansion valve that controls the opening of the throttle, and the compressor is an inverter compressor that controls the rotational speed, and the detection result of the critical pressure detection means has reached the upper limit value of the critical pressure. lever, opening the opening of the electronic expansion valve, and / or cooling device for the automatic vending machine according to claim 1, further comprising a control means for reducing the rotational speed of the inverter compressor is characterized. 3. The vending machine cooling apparatus according to claim 1, wherein carbon dioxide is used as the refrigerant.

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