US20180135902A1

US20180135902A1 - Refrigerant circuit device

Info

Publication number: US20180135902A1
Application number: US15/790,547
Authority: US
Inventors: Takao Murase
Original assignee: Fuji Electric Co Ltd
Current assignee: Fuji Electric Co Ltd
Priority date: 2016-11-15
Filing date: 2017-10-23
Publication date: 2018-05-17
Also published as: CN108072211A; JP2018080861A

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2016-222116 filed in Japan on Nov. 15, 2016.

BACKGROUND

The present disclosure relates to a refrigerant circuit device.
In the related art, there has been known a refrigerant circuit device used in, for example, an automatic vending machine, the refrigerant circuit device including a refrigerant circuit which is sequentially connecting a condenser, a compressor, a heat radiator, and an electronic expansion valve.
A condenser is installed in a product container of the automatic vending machine. In the condenser, the supplied refrigerant passes through a predetermined flow channel and evaporates, thereby cooling the internal air of the product container.
The compressor is installed in a machine room that is provided in the main body of the automatic vending machine and outside the product container. The compressor absorbs the refrigerant that has evaporated in the condenser, and compresses the absorbed refrigerant into a high-temperature and high-pressure state and then discharges it.
The heat radiator is installed in the machine room along with the compressor. The refrigerant that has been compressed by the compressor is guided into the heat radiator, and the refrigerant releases heat thereby heating the ambient air, that is, the refrigerant releases heat in the ambient air.
The electronic expansion valve is installed in the machine room along with the compressor and the heat radiator. The electronic expansion valve decompresses the refrigerant, which has released heat in the radiator, and causes adiabatic expansion of the refrigerant.
In such a refrigerant circuit device, the opening of the electronic expansion valve is adjusted so that a temperature difference is set to a predetermined value between the evaporating temperature of the refrigerant that flows in the condenser and the temperature inside the product container, thereby circulating the refrigerant in the refrigerant circuit to cool the internal air of the product container (see, for example, Japanese Patent No. 5124952).

SUMMARY

According to an embodiment of the present disclosure, a refrigerant circuit device to cool a product stored in a storage room, includes: a refrigerant circuit including a condenser installed in the storage room, a compressor absorbing and compressing a refrigerant which has been evaporated in the condenser, a heat radiator causing the refrigerant, which has been compressed by the compressor, to release heat from the refrigerant, an electronic expansion valve causing an adiabatic expansion of the refrigerant which has released heat in the heat radiator, a refrigerant pipe line sequentially connecting the condenser, the compressor, the heat radiator, and the electronic expansion valve to flow the refrigerant; and a controller, in case of performing a forced cooling operation in which the product stored in the storage room is forcedly cooled, adjusting an opening of the electronic expansion valve in a manner that a temperature or a pressure of the refrigerant that has been discharged from the compressor approaches a predetermined target discharge temperature or a predetermined target discharge pressure, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view seen from the front illustrating an internal structure of an automatic vending machine including a refrigerant circuit device according to an embodiment of the present disclosure;

FIG. 2 is a cross-sectional side view of a product container present on the right-hand side of the internal structure of the automatic vending machine of FIG. 1;

FIG. 3 is a diagram schematically illustrating the refrigerant circuit device according to the embodiment of the present disclosure;

FIG. 4 is a flowchart illustrating a process of operation switching control performed by a control unit of FIG. 3; and

FIG. 5 is a graphic of a temperature change of the in-container temperature relative to a product temperature over time.

DETAILED DESCRIPTION

Generally, it is known that a large amount of energy is required for cooling the products when an automatic vending machine including a refrigerant circuit device is installed in a high-temperature and high-humidity environment and a forced cooling operation (i.e., a “pull-down operation”) is performed on the products stocked in the product container.
Due to the required large amount of energy, the amount of heat required in the compressor and the heat radiator also becomes greater accordingly and the compressor is out of usable range. As a result, the operation of the compressor may stop and the forced cooling operation may not be performed.
In the refrigerant circuit device proposed in Japanese Patent No. 5124952, the opening of the electronic expansion valve is adjusted so that a predetermined temperature difference is set between the evaporating temperature of the refrigerant and the temperature inside the product container. Due to this, if the automatic vending machine including such a refrigerant circuit device is installed in a high-temperature and high-humidity environment, there is a risk that the operation of the compressor stops during the forced cooling operation or the forced cooling operation cannot be performed.
There is a need for at least partially solving the problems in the related technology.
A preferred embodiment of a refrigerant circuit device according to the present disclosure is described below in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view seen from the front illustrating an internal structure of an automatic vending machine, where a refrigerant circuit device according to the embodiment of the present disclosure is used. The automatic vending machine of FIG. 1 includes a main body cabinet 1.
The main body cabinet 1 is cuboid in shape and opens at the front face. Inside the main body cabinet 1, two independent product containers (storage rooms) 3 are horizontally arranged in a segmented manner using, for example, a heat insulation divider 2. The product containers 3 are provided to keep a temperature of the products such as canned drinks or bottled drinks at a desired temperature, and have a heat-insulated structure.
FIG. 2 is a cross-sectional side view of a product container present on the right-hand side of the internal structure of the automatic vending machine of FIG. 1. Herein, although the explanation is given about the internal structure of the product container 3 on the right-hand side (hereinafter, referred to as a “right-side container 3 a”), the product container 3 on the left-hand side (hereinafter, referred to as a “left-side container 3 b”) also has the substantially same internal structure. Meanwhile, in this written description, the right-hand side implies the right-hand side when the automatic vending machine is viewed from the front side thereof, and the left-hand side implies the left-hand side when the automatic vending machine is viewed from the front side thereof.
As illustrated in FIG. 2, on the front face of the main body cabinet 1, an outer door 4 and an inner door 5 are installed. The outer door 4 is used to open and close the front-side opening of the main body cabinet 1, while the inner door 5 is used to open and close the front side of the product container 3. The inner door 5 is divided in the vertical direction, and an upper-side door 5 a is used to open and close to supply products into the product container 3 at the time of stocking the products.
The product container 3 is equipped with a product storage rack 6, a dispenser mechanism 7, and a discharging shooter 8 installed therein. The product storage rack 6 is used to store the products along the vertical direction. The dispenser mechanism 7 is disposed below the product storage rack 6, and is used to dispense, one by one, the undermost product from among the group of products stored in the product storage rack 6. The discharging shooter 8 guides the product, which has been dispensed from the dispenser mechanism 7, to a product outlet 4 a provided in the outer door 4.
FIG. 3 is a diagram schematically illustrating the refrigerant circuit device according to the embodiment of the present disclosure. The refrigerant circuit device of FIG. 3 includes a refrigerant circuit 20, which is filled with carbon dioxide which serves as the refrigerant, and a control unit (controller) 30.
The refrigerant circuit 20 includes a refrigerant pipe line 25 which sequentially connecting a compressor 21, a heat radiator 22, an electronic expansion valve 23, and condensers 24.
As illustrated in FIG. 2 as well, the compressor 21 is installed in a machine room 9. Herein, the machine room 9 is provided in the main body cabinet 1 and on the lower side of the product container 3 and is divided from the product container 3. The compressor 21 absorbs the refrigerant through a suction inlet, and compresses the absorbed refrigerant into a high-temperature and high-pressure state (into a high-pressure refrigerant) and then discharges it from a spout.
As illustrated in FIG. 2 as well, the heat radiator 22 is installed in the machine room 9 along with the compressor 21. The heat radiator 22 is made of aluminum, for example. When the refrigerant that has been compressed by the compressor 21 passes through the flow channel formed therein, the heat radiator 22 performs a heat exchange between the refrigerant and the ambient air to release heat.
The electronic expansion valve 23 is installed in the machine room 9 along with the compressor 21 and the heat radiator 22. The electronic expansion valve 23 decompresses the refrigerant passing therethrough and causes an adiabatic expansion of the refrigerant. Moreover, the opening of the electronic expansion valve 23 is adjusted according to instructions from the control unit 30.
A plurality of condensers 24 (in the example, only two condensers 24) is provided, and each condenser 24 is installed in the lower area of the corresponding product container 3 and on the front side of a backside duct 10. The condensers 24 are made of aluminum, for example.
The refrigerant pipe line 25 that connects the condensers 24 and the electronic expansion valve 23 is branched into two pipe lines by a distributor 26 installed in the midway of the refrigerant pipe line 25; and the branched pipe lines are connected to the inlet side of the condenser 24 installed in the right-side container 3 a (hereinafter, also referred to as a “right-side condenser 24 a”) and the inlet side of the condenser 24 installed in the left-side container 3 b (hereinafter, also referred to as a “left-side condenser 24 b”). The condensers 24 cause evaporation of the refrigerant passing therethrough, and cool the internal air of the product containers 3.
In the refrigerant pipe line 25, in the midway of the paths from the distributor 26 to the condensers 24, there are provided solenoid valves 27 a and 27 b and capillary tubes 28 a and 28 b. The solenoid valves 27 a and 27 b are openable and closable valving elements that, when an instruction to open is issued by the control unit 30, open up and allow the flow of the refrigerant but, when an instruction to close is issued, close and restrict the flow of the refrigerant. The capillary tubes 28 a and 28 b decompress the refrigerant passing therethrough and cause adiabatic expansion of the refrigerant.
The refrigerant pipe lines 25 connected on the outlet side of the condensers 24 is connected to the compressor 21 in a manner that the refrigerant pipe lines 25 converge at a joining point P and are communicated with the suction inlet of the compressor 21.
The symbols “H”, “29”, “F1”, and “F2” in FIG. 3 denote a heater, an internal heat exchanger, in-container blast fans, and an out-container blast fan, respectively. The heater H is installed in the left-side container 3 b, and serves as a heating unit that, when driven to carry electrical current, heats the internal air of the left-side container 3 b. The internal heat exchanger 29 causes a heat exchange between the high-pressure refrigerant that has passed through the heat radiator 22 and the refrigerant (the low-pressure refrigerant) that has passed through the condensers 24. The in-container blast fans F1 are installed near the condensers 24 inside the product containers 3, and serve as in-container blowers that, when driven, blow the internal air of the respective product containers 3. The out-container blast fan F2 is installed near the heat radiator 22, and serves as a blower that, when driven, enables circulation of the external air around the out-container blast fan F2.
Moreover, in FIG. 3 are also illustrated a discharge temperature sensor S1, evaporating temperature sensors S2, and in-container temperature sensors S3.
The discharge temperature sensor S1 is installed in the refrigerant pipe line 25 that is communicated to the spout of the compressor 21, and detects the temperature (the discharge temperature) of the refrigerant discharged from the compressor 21. The discharge temperature sensor S1 sends the detected discharge temperature as a discharge temperature signal to the control unit 30.
Evaporating temperature sensors S2 are installed in the respective refrigerant pipe lines 25 at the inlet side of the corresponding condenser 24, and detect the temperatures (the evaporating temperatures) of the refrigerant flowing in the corresponding condensers 24. The evaporating temperature sensors S2 send the respective detected evaporating temperature as evaporating temperature signals to the control unit 30.
In-container temperature sensors S3 are installed inside the respective product containers 3, and detect the internal temperatures (the in-container temperatures) of the corresponding product containers 3. The in-container temperature sensors S3 send the detected in-container temperatures as in-container temperature signals to the control unit 30.
The control unit 30 comprehensively controls the operations of the refrigerant circuit device according to computer programs and data stored in a memory (not illustrated). The control unit 30 may be integrated with an automatic-vending-machine control unit (not illustrated) that controls the driving of the automatic vending machine, or may be independently separated from the automatic-vending-machine control unit. Moreover, for example, the control unit 30 may be realized by causing a processor such as a central processing unit (CPU) to execute a computer program, that is, may be realized by using software; or may be realized by using hardware such as an integrated circuit (IC); or may be realized by using a combination of software and hardware.
In the refrigerant circuit device having such a configuration as described above, the refrigerant is circulated in the refrigerant circuit 20 and the products stocked in the product containers 3 are cooled in the following manner. The following explanation is given regarding the cooling of the internal air of all product containers 3.
In this case, the control unit 30 opens the solenoid valves 27 a and 27 b. As a result, the refrigerant that has been compressed by the compressor 21 reaches the heat radiator 22. Then, the refrigerant that has reached the heat radiator 22 performs heat exchange with the ambient air (the external air) and releases heat while passing through the heat radiator 22. Subsequently, the refrigerant that has released heat in the heat radiator 22 passes through the internal heat exchanger 29 and then undergoes adiabatic expansion in the electronic expansion valve 23.
The refrigerant that has undergone adiabatic expansion and turned into gas in the electronic expansion valve 23 is branched in two paths at the distributor 26; undergoes further adiabatic expansion in the capillary tubes 28 a and 28 b and reaches the right-side condenser 24 a and the left-side condenser 24 b; evaporates in the condensers 24 and draws heat from the internal air of the product containers 3; and thus cools the internal air. Then, the internal air that has cooled down circulates in the inside due to the driving of the in-container blast fans F1. As a result, the products that are stocked in the product containers 3 are cooled by the circulating internal air.
The refrigerant that evaporated in the condensers 24 comes together at the joining point P and gets absorbed into the compressor 21 via the internal heat exchanger 29, and then gets compressed in the compressor 21 and is again circulated as described above.
In the meantime, in the automatic vending machine, in the case of performing the forced cooling operation (the “pull-down operation”) in which the products stocked in the product containers 3 are forcedly cooled to a predetermined temperature, the control unit 30 performs control to adjust the opening of the electronic expansion valve 23 in a manner that the discharge temperature, which is indicated by the discharge temperature signal sent from the discharge temperature sensor S1, approaches a predetermined target discharge temperature stored in the memory or the like. That control is performed using Proportional-Integral-Differential (PID) control, for example. Herein, the target discharge temperature is empirically obtained in view of maximizing the cooling capability of the compressor 21.
In the automatic vending machine, in the case of performing a normal cooling operation in which, after the forced cooling operation is performed, the products stocked in the product containers 3 are maintained within a cooling temperature range set in advance; if the in-container temperature that is indicated by the in-container temperature signal sent from each in-container temperature sensor S3 becomes equal to or lower than the lower limit temperature of the cooling temperature range, the control unit 30 stops driving the compressor 21 and, if the in-container temperature becomes equal to or higher than the upper limit temperature of the cooling temperature range, the control unit 30 drives the compressor 21. As a result, a temperature of the products stocked in the product containers 3 are maintained within the above cooling temperature range.
Moreover, in the case of performing the normal cooling operation, the control unit 30 performs control to adjust the opening of the electronic expansion valve 23 in a manner that the evaporating temperature, which is indicated by the evaporating temperature signal sent from each evaporating temperature sensor S2, approaches a predetermined target evaporating temperature stored in the memory or the like. That control is performed using the PID control, for example. Herein, the target evaporating temperature is empirically obtained in view of achieving an excellent cooling efficiency.
Moreover, in the case of performing the forced cooling operation, the control unit 30 further performs operation switching control in the following manner. FIG. 4 is a flowchart illustrating a process of operation switching control performed by the control unit 30 of FIG. 3.
In the operation switching control, when the in-container temperature signals are input from the in-container temperature sensors S3 (Yes in Step S101), the control unit 30 reads a temperature for switching from the memory (Step S102). Herein, the temperature for switching refers to a temperature lower than the lower limit temperature of the cooling temperature range, and is set in a manner that the products stocked in the product containers 3 have the temperature equal to or lower than the upper limit temperature of the cooling temperature range.
Upon reading the temperature for switching, the control unit 30 determines whether the in-container temperature is equal to or lower than the temperature for switching (Step S103). If the in-container temperature is not equal to or lower than the temperature for switching (No in Step S103), the control unit 30 again performs the operations from Steps S101 to S103.
On the other hand, if the in-container temperature is equal to or lower than the temperature for switching (Yes in Step S103), then the control unit 30 switches to the normal cooling operation (Step S104). Subsequently, the system control returns to the start, and the operations are ended.
FIG. 5 is a graphic of a temperature change of the in-container temperature relative to a product temperature over time. As illustrated in FIG. 5, as a result of performing the operation switching control, a switching to the normal cooling operation can be performed at a timing (t1) at which an in-container temperature (A) becomes equal to or lower than a temperature for switching (s0), and the temperature of the products can be shifted to the intermediate position between a lower limit temperature (s1) and an upper limit temperature (s2) within the cooling temperature range.
On the other hand, if the operation switching control is not performed and if the switching to the normal cooling operation is performed at a timing (t2) at which the in-container temperature (A) becomes equal to or lower than the lower limit temperature (s1) of the cooling temperature range, a product temperature (B) is equal to or higher than the upper limit temperature (s2) of the cooling temperature range and, as a result, the product temperature (B) reaches the intermediate position between the lower limit temperature (s1) and the upper limit temperature (s2) within the cooling temperature range at a timing (t3) that is later than the timing (ti). Thus, by performing the operation switching control, it becomes possible to shorten the period of time taken for cooling the products in the cooling temperature range.
As described above, in the refrigerant circuit device according to the present embodiment, in the case of performing the forced cooling operation in which the products stocked in the product containers 3 are forcedly cooled, the control unit 30 adjusts the opening of the electronic expansion valve 23 in a manner that the discharge temperature becomes closer to the target discharge temperature. Hence, even if the automatic vending machine in which the refrigerant circuit device is implemented is installed in a high-temperature and high-humidity environment, the compressor 21 can be driven at the maximum capability thereof and can be prevented from exceeding the usage limits. Since the compressor 21 can be driven at the maximum capability thereof, the products can be cooled in a stable manner. Thus, in the case of performing the forced cooling operation in a high-temperature and high-humidity environment, the products can be cooled in a successful manner.
Besides, in the case of performing a normal cooling operation in which the products stocked in the product containers 3 are maintained within the cooling temperature range, the control unit 30 controls the opening of the electronic expansion valve 23 in a manner that the evaporating temperature approaches the target evaporating temperature. As a result, the products can be cooled by preventing excessive decline in the evaporating temperature, and frost can be prevented from forming on the condensers 24. Thus, in the case of performing the normal cooling operation in a high-temperature and high-humidity environment, the products can be cooled in a successful manner.
In the refrigerant circuit device, when the in-container temperature becomes equal to or lower than the temperature for switching, the control unit 30 switches from the forced cooling operation to the normal cooling operation, thereby enabling shortening of the period of time taken for cooling the products stocked in the cooling temperature range.
In the refrigerant circuit device, since the condensers 24 are made of aluminum, they have an excellent heat conductivity. For that reason, in the case of maintaining the heat-transfer capability equivalent to prior and existing condensers, it becomes possible to increase the inter-pitch dimensions of the fins of the condensers 24. For that reason, even if there is frost formation, because of an increase in the inter-pitch dimensions, the flow of air is maintained and the internal air of the product containers 3 can be cooled in a successful manner.
Although a preferred embodiment of the present disclosure is described, the present disclosure is not limited to that embodiment and it is possible to have various modifications.
In the embodiment described above, a case is described where the temperature (the discharge temperature) of the refrigerant that has been discharged by the compressor 21 is detected by using the discharge temperature sensor S1, and the opening of the electronic expansion valve 23 is adjusted in accordance with the temperature. Alternatively, in the present disclosure, the pressure (the discharge pressure) of the refrigerant discharged by the compressor may be detected, and the opening of the electronic expansion valve can be adjusted in a manner that the discharge pressure approaches a target discharge pressure.
In the embodiment described above, a case is described where the temperature for switching is lower than the lower limit temperature of the cooling temperature range and is set in a manner that the temperature of the product containers 3 becomes equal to or lower than the upper limit temperature of the cooling temperature range. Alternatively, in the present disclosure, it is sufficient if the temperature for switching is lower than the lower limit temperature of the cooling temperature range. By doting this as well, it becomes possible to shorten the period of time taken for cooling the products in the cooling temperature range.
According to the present disclosure, in the case of performing the forced cooling operation in which the products stocked in the storage rooms are forcedly cooled, the controller adjusts the opening of the electronic expansion valve in a manner that the temperature or the pressure of the refrigerant that has been discharged from the compressor approaches a predetermined target discharge temperature or a predetermined target discharge pressure, respectively. Hence, even if the installation is made in a high-temperature and high-pressure environment, the compressor can be driven at the maximum capability thereof and can be prevented from exceeding the usage limits. Since the compressor can be driven at the maximum capability thereof, the products can be cooled in a stable manner. Thus, in the case of performing the forced cooling operation in a high-temperature and high-humidity environment, the products can be cooled in a successful manner.
Moreover, according to the present disclosure, in the case of performing the normal cooling operation in which the products stocked in the storage rooms are maintained within a cooling temperature range set in advance, the controller adjusts the opening of the electronic expansion valve in a manner that the temperature of the refrigerant that flows into the condensers approaches a predetermined target evaporating temperature. As a result, the products can be cooled by preventing excessive decline in the evaporating temperature, and frost can be prevented from forming on the condensers.
Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.

Claims

What is claimed is:

1. A refrigerant circuit device to cool a product stored in a storage room, the refrigerant circuit device comprising:

a refrigerant circuit including

a condenser installed in the storage room,

a compressor configured to absorb and compress a refrigerant which has been evaporated in the condenser,

a heat radiator configured to cause the refrigerant, which has been compressed by the compressor, to release heat from the refrigerant,

an electronic expansion valve configured to cause an adiabatic expansion of the refrigerant which has released heat in the heat radiator,

a refrigerant pipe line sequentially connecting the condenser, the compressor, the heat radiator, and the electronic expansion valve to flow the refrigerant; and

a controller configured to, in case of performing a forced cooling operation in which the product stored in the storage room is forcedly cooled, adjust an opening of the electronic expansion valve in a manner that a temperature or a pressure of the refrigerant that has been discharged from the compressor approaches a predetermined target discharge temperature or a predetermined target discharge pressure, respectively.

2. The refrigerant circuit device according to claim 1, wherein, the controller is configured to, in a case of performing a normal cooling operation in which the product stored in the storage room is cooled to have temperature thereof maintained within a cooling temperature range set in advance, control the opening of the electronic expansion valve in a manner that a temperature of the refrigerant that flows into the condenser approaches a predetermined target evaporating temperature.

3. The refrigerant circuit device according to claim 2, wherein, the controller is configured to, when an internal temperature of the storage room is equal to or lower than a temperature for switching which is lower than a lower limit temperature of the cooling temperature range, switch from the forced cooling operation to the normal cooling operation.

4. The refrigerant circuit device according to claim 3, wherein the temperature for switching is set in a manner that the product in the storage room has temperature to be equal to or lower than an upper limit temperature of the cooling temperature range.

5. The refrigerant circuit device according to claim 1, wherein carbon dioxide is used as the refrigerant.