Cooling device

Abstract

The present invention provides a cooling device that can reduce the time required to create a vacuum in the refrigerant flow path. [Solution] In this cooling device 100, when the control unit 20 receives a control input to enable the refrigerant filling opening degree adjustment function for forcibly opening the first electronic expansion valve 3 and the second electronic expansion valve 5, it sets the opening degree of the first electronic expansion valve 3 and the second electronic expansion valve 5 to an opening degree greater than or equal to the opening degree normally used.

Description

Technical Field

[0001] This invention relates to a cooling device, and particularly to a cooling device including an electronic expansion valve with adjustable opening degree.

Background Art

[0002] Conventionally, a cooling device including an electronic expansion valve with adjustable opening degree has been known (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a cooling device including a compressor, a condenser, a main expansion valve, an evaporator, an intermediate heat exchanger, and an electronic expansion valve that expands the refrigerant supplied to the intermediate heat exchanger. In this cooling device, the refrigerant compressed by the compressor is condensed in the condenser, and then the refrigerant is supplied from the condenser to the intermediate heat exchanger. The intermediate heat exchanger includes a first part and a second part, and the refrigerant condensed by the condenser is supplied to the first part and the second part separately. An electronic expansion valve is provided in the flow path connecting the condenser and the first part of the intermediate heat exchanger, and heat exchange is performed between the refrigerant expanded by the electronic expansion valve and the refrigerant supplied to the second part. The refrigerant passing through the second part is supplied to the evaporator via the main expansion valve, and the refrigerant passing through the first part is supplied to the compressor. The opening degree of the electronic expansion valve can be electrically controlled.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In cooling devices like the one described in Patent Document 1, the refrigerant flow path may be made into a vacuum in order to remove air from within the refrigerant flow path. However, although not explicitly stated in Patent Document 1, the opening degree of the electronic expansion valve when the refrigerant flow path is made into a vacuum maintains the state it was in just before. Therefore, if the opening degree of the electronic expansion valve is insufficient, a refrigerant flow path is formed between the electronic expansion valve and the compressor that communicates with other parts only through the electronic expansion valve with an insufficient opening. In that case, due to the pressure loss caused by the electronic expansion valve, it takes a lot of time to make the entire refrigerant flow path into a vacuum. For this reason, there is a need for a cooling device that can reduce the time required to make the refrigerant flow path into a vacuum.

[0006] This invention was made to solve the above-mentioned problems, and one of its objectives is to provide a cooling device that can reduce the time required to create a vacuum in the refrigerant flow path. [Means for solving the problem]

[0007] To achieve the above objective, a cooling device according to one aspect of this invention comprises a compressor for compressing a refrigerant flowing through a refrigerant passage, a cooler for cooling the refrigerant supplied from the compressor, an electronic expansion valve for expanding the refrigerant cooled by the cooler and whose opening degree can be controlled, an evaporator for cooling an object by evaporating the refrigerant expanded by the electronic expansion valve, and a control unit for controlling the opening degree of the electronic expansion valve. When the control unit receives an input for forced opening control to forcibly open the electronic expansion valve, it sets the opening degree of the electronic expansion valve to an opening degree greater than or equal to the normally used opening degree.

[0008] In a cooling device according to one aspect of this invention, as described above, when the control unit receives an input for forced opening control to forcibly open the electronic expansion valve, it sets the opening of the electronic expansion valve to a degree greater than or equal to the normally used opening. This allows the electronic expansion valve to be opened to a degree greater than its current opening by inputting the forced opening control before the refrigerant flow path is brought into a vacuum state. Therefore, it is possible to suppress the formation of a refrigerant flow path communicating with other parts by only the electronic expansion valve that is not sufficiently open, thereby reducing the pressure loss due to the electronic expansion valve when bringing the refrigerant flow path into a vacuum state. As a result, the time required to bring the refrigerant flow path into a vacuum state can be reduced.

[0009] In the cooling device according to the first aspect described above, preferably, when the control unit receives input for forced opening control, it sets the opening of the electronic expansion valve to its maximum opening. With this configuration, the pressure loss by the electronic expansion valve when creating a vacuum in the refrigerant flow path can be reduced more effectively.

[0010] In the cooling device according to the first aspect described above, preferably, when the control unit receives input for forced opening control, it sets the opening of the electronic expansion valve to an opening greater than or equal to the normally used opening without performing opening control of the electronic expansion valve by other controls. With this configuration, it is possible to suppress the unintentional reduction of the opening of the electronic expansion valve due to other controls when creating a vacuum in the refrigerant flow path.

[0011] In the cooling device according to the first aspect described above, preferably, the forced opening control includes control that enables a refrigerant filling opening adjustment function for forcibly opening the electronic expansion valve when filling with refrigerant. With this configuration, by enabling the refrigerant filling opening adjustment function when filling with refrigerant, it is possible to suppress the formation of a refrigerant flow path that communicates with other parts only by an electronic expansion valve that is not sufficiently open, thereby suppressing uneven filling of the refrigerant.

[0012] In the cooling device according to the first aspect described above, preferably, the compressor includes a first compression section and a second compression section that further compresses the refrigerant compressed by the first compression section, the cooler cools the refrigerant supplied from the second compression section, the electronic expansion valve includes a first electronic expansion valve that expands a portion of the refrigerant cooled by the cooler and a second electronic expansion valve that expands the remaining refrigerant cooled by the cooler, the device further includes an evaporation section that evaporates the refrigerant expanded in the first electronic expansion valve and supplies it to the second compression section, and a cooling section where the remaining refrigerant cooled by the cooler is cooled, and further includes an intermediate heat exchanger located upstream of the second electronic expansion valve that performs heat exchange between the refrigerant in the evaporation section and the refrigerant in the cooling section, and when the control unit receives input for forced opening control, it sets the opening of at least the first electronic expansion valve to an opening greater than or equal to the normally used opening. In a case where the refrigerant flow path is divided into a refrigerant flow path between the compressor and the second electronic expansion valve upstream of the compressor (low-pressure refrigerant flow path), a refrigerant flow path between the compressor and the first or second electronic expansion valve downstream of the compressor (high-pressure refrigerant flow path), and a refrigerant flow path between the first electronic expansion valve and the second compression unit (intermediate-pressure refrigerant flow path), if the opening of at least the first electronic expansion valve is set to an opening greater than or equal to the normally used opening, the pressure loss due to the first electronic expansion valve between the intermediate-pressure refrigerant flow path and the high-pressure refrigerant flow path can be reduced, and the high-pressure refrigerant flow path and the intermediate-pressure refrigerant flow path can be quickly brought into a vacuum state through a single maintenance port. As a result, it becomes unnecessary to provide three maintenance ports corresponding to the low-pressure refrigerant flow path, the high-pressure refrigerant flow path, and the intermediate-pressure refrigerant flow path in order to bring the entire refrigerant flow path into a vacuum state, thus simplifying the overall structure of the cooling system.

[0013] In this case, preferably, the system further includes a maintenance port that can communicate the inside and outside of the refrigerant flow path, the maintenance port including a first port located in the refrigerant flow path connecting the second electronic expansion valve and the first compression unit, and a second port located in the refrigerant flow path connecting the second compression unit and either the first electronic expansion valve or the second electronic expansion valve. Even if a maintenance port is not located in the refrigerant flow path between the first electronic expansion valve and the second compression unit (intermediate-pressure side refrigerant flow path), by setting the opening of the first electronic expansion valve to at least the opening that is normally used, the pressure loss due to the first electronic expansion valve between the intermediate-pressure side refrigerant flow path and the high-pressure side refrigerant flow path can be reduced, so that the entire refrigerant flow path can be quickly brought to a vacuum state by the two maintenance ports.

[0014] In the cooling device according to the first aspect described above, preferably, when the control unit receives input for forced opening control, it controls the electronic expansion valve to reduce its opening by more than the movable stroke of the electronic expansion valve, thereby setting the electronic expansion valve to its minimum opening. After resetting the control signal for the electronic expansion valve to zero, the control unit uses the zero-reset control signal to set the electronic expansion valve to an opening greater than or equal to the normally used opening. With this configuration, even if the control unit cannot accurately recognize the opening of the electronic expansion valve at the time it receives input for forced opening control, it can accurately recognize the opening of the electronic expansion valve by setting a baseline (origin), thereby enabling it to accurately set the opening of the electronic expansion valve to an opening greater than or equal to the normally used opening.

[0015] In the cooling device according to the first aspect described above, preferably, a notification unit is further provided to notify the operator when the opening of the electronic expansion valve becomes greater than or equal to the opening that is normally used. With this configuration, the operator can easily recognize when the opening of the electronic expansion valve becomes greater than or equal to the opening that is normally used. As a result, usability (user convenience) can be improved.

[0016] In the cooling device according to the above-described one aspect, preferably, when the control unit receives an input of forced opening degree control, it changes from the normal mode to the forced opening degree control mode. In the forced opening degree control mode, the control unit is configured to set the opening degree of the electronic expansion valve to an opening degree equal to or greater than the opening degree normally used. The control unit further includes a display unit that displays that the control unit is in the forced opening degree control mode. With this configuration, the operator can easily recognize that the forced opening degree control mode has been entered. As a result, user convenience can be improved.

Advantages of the Invention

[0017] According to the present invention, as described above, the time required to bring the refrigerant flow path into a vacuum state can be reduced.

Brief Description of the Drawings

[0018] [Figure 1] It is a block diagram showing the overall configuration of a cooling device according to an embodiment of the present invention. [Figure 2] It is a graph for explaining the relationship between the opening degree of an electronic expansion valve and a pulse signal according to an embodiment of the present invention. [Figure 3] It is a diagram showing a display operation unit according to an embodiment of the present invention. [Figure 4] It is a diagram showing an alarm unit according to an embodiment of the present invention. [Figure 5] It is a flowchart showing a control process for setting the opening degree of an electronic expansion valve to the maximum opening degree according to an embodiment of the present invention. [Figure 6] It is a flowchart showing a control process for setting the opening degree of an electronic expansion valve to the maximum opening degree according to a modified example of the present invention.

Modes for Carrying Out the Invention

[0019] Hereinafter, an embodiment embodying the present invention will be described based on the drawings.

[0020] Referring to FIGS. 1 to 4, the configuration of the cooling device 100 according to the present embodiment will be described.

[0021] (Configuration of the Cooling Device) As shown in FIG. 1, the cooling device 100 includes a compressor 1, a gas cooler 2, a first electronic expansion valve 3, an intermediate heat exchanger 4, a second electronic expansion valve 5, an evaporator 6, an internal heat exchanger 7, a check valve 8, an intercooler 9, a service port 10, a refrigerant flow path 11, a control unit 20, a display operation unit 30, and an alarm unit 40. The cooling device 100 is a device that cools a cooling target with a refrigerant. The cooling device 100 is used, for example, in a showcase, and cools the space inside the showcase by cooling the cooling target. The refrigerant is, for example, carbon dioxide. The gas cooler 2 is an example of the "cooler" in the claims. The service port 10 is an example of the "maintenance port" in the claims. The alarm unit 40 is an example of the "notification unit" in the claims.

[0022] The refrigerant flow path 11 is a flow path of the refrigerant, and the refrigerant flow described later is through the refrigerant flow path 11. The detailed structure of the refrigerant flow path 11 will be described later. As shown in FIG. 1, the compressor 1 includes a first compression part 1a and a second compression part 1b. The first compression part 1a compresses the refrigerant in a low-pressure state supplied from the evaporator 6 through the internal heat exchanger 7 into a refrigerant in a medium-pressure state. The second compression part 1b further compresses the refrigerant in the medium-pressure state compressed by the first compression part 1a into a refrigerant in a high-pressure state. The refrigerant compressed by the first compression part 1a is supplied to the intercooler 9. The refrigerant compressed by the second compression part 1b is supplied to the gas cooler 2. The compressor 1 is a so-called two-stage compressor. In addition, the compressor 1 is configured to divide the upstream refrigerant flow path 11 and the downstream refrigerant flow path 11 when not in operation. "Dividing the flow path" means preventing the refrigerant from flowing from one side to the other side with respect to the compressor 1.

[0023] As shown in FIG. 1, the gas cooler 2 cools the refrigerant in a high-pressure state in the second compression part 1b into a refrigerant in a low-temperature and high-pressure state. The refrigerant cooled by the gas cooler 2 is supplied to the intermediate heat exchanger 4 and the first electronic expansion valve 3.

[0024] As shown in Figure 1, the first electronic expansion valve 3 receives a portion of the refrigerant cooled by the gas cooler 2 and expands the supplied refrigerant. As a result, the refrigerant that passes through the first electronic expansion valve 3 becomes refrigerant in a low-temperature, low-pressure state.

[0025] As shown in Figure 1, the intermediate heat exchanger 4 includes an evaporation section 4a and a cooling section 4b. The evaporation section 4a is supplied with refrigerant expanded by the first electronic expansion valve 3. The cooling section 4b is supplied with the remaining refrigerant that was not supplied to the first electronic expansion valve 3 after being cooled by the gas cooler 2. The intermediate heat exchanger 4 performs heat exchange between the refrigerant in the evaporation section 4a and the refrigerant in the cooling section 4b. The refrigerant supplied to the evaporation section 4a is refrigerant that has been expanded by the first electronic expansion valve 3 and is in a medium temperature and medium pressure state. On the other hand, the refrigerant supplied to the cooling section 4b has not passed through the first electronic expansion valve 3 and is therefore at a higher temperature than the refrigerant supplied to the evaporation section 4a. As a result, heat exchange occurs between the refrigerant in the evaporation section 4a and the refrigerant in the cooling section 4b, causing the refrigerant in the evaporation section 4a to evaporate and the refrigerant in the cooling section 4b to cool. The refrigerant cooled in the cooling section 4b is supplied to the internal heat exchanger 7. The refrigerant evaporated in the evaporation section 4a is supplied to the second compression section 1b.

[0026] Here, the larger the opening of the first electronic expansion valve 3, the greater the flow rate of refrigerant supplied to the evaporation section 4a. Conversely, the smaller the opening of the first electronic expansion valve 3, the smaller the flow rate of refrigerant supplied to the evaporation section 4a. Furthermore, the smaller the opening of the first electronic expansion valve 3, the lower the evaporation temperature of the refrigerant in the evaporation section 4a.

[0027] The second electronic expansion valve 5 expands the refrigerant that has passed through the cooling section 4b and been cooled by the internal heat exchanger 7 (described later), thereby converting it into a low-temperature, low-pressure refrigerant.

[0028] The evaporator 6 cools the object to be cooled by exchanging heat between the refrigerant, which is in a low-temperature, low-pressure state supplied from the second electronic expansion valve 5, and the object to be cooled, thereby evaporating the refrigerant. In the evaporator 6, the refrigerant becomes superheated and low-pressure and is supplied to the internal heat exchanger 7. Here, the larger the opening of the second electronic expansion valve 5, the greater the flow rate of refrigerant supplied to the evaporator 6, and the greater the amount of cooling of the object to be cooled. Conversely, when the opening of the second electronic expansion valve 5 decreases, the flow rate of refrigerant supplied to the evaporator 6 decreases, and the amount of cooling of the object to be cooled decreases. Therefore, the opening of the second electronic expansion valve 5 affects the cooling capacity of the evaporator 6. A check valve 8 is provided in the refrigerant flow path 11 connecting the downstream side (outlet side) of the evaporator 6 and the internal heat exchanger 7. The check valve 8 is provided to prevent the refrigerant from flowing back from the internal heat exchanger 7 side to the evaporator 6 side, which will be described later.

[0029] The internal heat exchanger 7 performs heat exchange between the refrigerant supplied from the cooling unit 4b and the refrigerant that has passed through the evaporator 6. This cools the refrigerant supplied from the cooling unit 4b and increases the degree of superheating of the refrigerant that has passed through the evaporator 6. The superheated, low-pressure refrigerant that has passed through the internal heat exchanger 7 is supplied to the first compression unit 1a.

[0030] The intercooler 9 cools the refrigerant, which has been brought to an intermediate pressure by the first compression unit 1a. As shown in Figure 1, the refrigerant cooled by the intercooler 9 is supplied to the second compression unit 1b.

[0031] As shown in Figure 1, the service port 10 includes a first port 10a and a second port 10b. The first port 10a is provided in the refrigerant flow path 11 between the internal heat exchanger 7 and the first compression unit 1a. The first port 10a is also provided downstream of the check valve 8. The second port 10b is provided in the refrigerant flow path 11 between the second compression unit 1b and the gas cooler 2. The service port 10 is configured to communicate the inside and outside of the refrigerant flow path 11 and is used when creating a vacuum in the refrigerant flow path 11, when discharging refrigerant from the refrigerant flow path 11, and when filling the refrigerant flow path 11 with refrigerant.

[0032] As shown in Figure 1, the refrigerant flow path 11 includes a high-pressure side refrigerant flow path 11a, shown by a solid line, a low-pressure side refrigerant flow path 11b, shown by a dashed line, and an intermediate-pressure side refrigerant flow path 11c, shown by a dotted line. The high-pressure side refrigerant flow path 11a is the refrigerant flow path 11 through which refrigerant at high pressure flows during cooling operation. The low-pressure side refrigerant flow path 11b is the refrigerant flow path 11 through which refrigerant at low pressure flows during cooling operation. The intermediate-pressure side refrigerant flow path 11c is the refrigerant flow path 11 through which refrigerant at intermediate pressure flows during cooling operation. The first port 10a is provided in the low-pressure side refrigerant flow path 11b. The second port 10b is provided in the high-pressure side refrigerant flow path 11a.

[0033] The control unit 20 includes a CPU (Central Processing Unit) and controls the operation of the cooling device 100 so that the temperature inside the showcase to be cooled reaches the set temperature. The control unit 20 adjusts the flow rate of the refrigerant by controlling the operation of the compressor 1, thereby adjusting the cooling capacity of the cooling device 100. The control unit 20 also adjusts the cooling capacity of the cooling device 100 by adjusting the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5.

[0034] When the control unit 20 receives a control input via the operation unit 30b, described later, to enable the refrigerant-filled opening degree adjustment function for forcibly opening the first electronic expansion valve 3 and the second electronic expansion valve 5, it is configured to set the opening degree of at least the first electronic expansion valve 3 to an opening degree equal to or greater than the normally used opening degree. In this embodiment, when the control unit 20 receives a control input to enable the refrigerant-filled opening degree adjustment function for forcibly opening the first electronic expansion valve 3 and the second electronic expansion valve 5, it is configured to set the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 to their maximum opening degrees. The refrigerant-filled opening degree adjustment function is an example of "forced opening degree control" in the claims. The control process by which the control unit 20 sets the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 to their maximum opening degrees will be described later.

[0035] This refrigerant filling opening adjustment function is used to forcibly open the first electronic expansion valve 3 and the second electronic expansion valve 5 when creating a vacuum in the entire refrigerant flow path 11 before refrigerant filling, when filling with refrigerant, and when discharging refrigerant that is already present in the refrigerant flow path 11 before refrigerant filling.

[0036] The normal operating range for the first electronic expansion valve 3 is 0 to approximately 10%, with the maximum operating range being 100%. Similarly, the normal operating range for the second electronic expansion valve 5 is 0 to approximately 100%, with the maximum operating range being 100%.

[0037] The display and operation unit 30 includes a display unit 30a and an operation unit 30b, and is configured to allow changes to the settings and confirmation of the status of the cooling device 100. The display unit 30a displays the setting items and status of the cooling device 100. The operation unit 30b is provided for performing operations to change the settings and confirm the status of the cooling device 100. The detailed structure of the display and operation unit 30 will be described later.

[0038] The alarm unit 40 displays alarm information for the cooling device 100. The detailed structure of the alarm unit 40 will be described later.

[0039] As shown in Figure 2, the first electronic expansion valve 3 and the second electronic expansion valve 5 are configured to change their opening degree in response to a pulse signal. The first electronic expansion valve 3 and the second electronic expansion valve 5 are configured so that the opening degree increases as the pulse signal increases. As shown in Figure 2, the first electronic expansion valve 3 and the second electronic expansion valve 5 are configured to remain at the minimum opening degree (0%) when a pulse signal is applied to decrease the opening degree from the minimum opening degree (0%) state. Also, the first electronic expansion valve 3 and the second electronic expansion valve 5 are configured to remain at the maximum opening degree (100%) when a pulse signal is applied to increase the opening degree from the maximum opening degree (100%) state.

[0040] As shown in Figure 3, the display unit 30a is configured to display the letters "RF" when the control unit 20 receives a control input to enable the refrigerant charging opening adjustment function. The display unit 30a is also configured to display the temperature inside the showcase during cooling operation. The operation unit 30b includes a plurality of operation switches 30c. When cooling is stopped (non-cooling), the display unit 30a displays "OFF". The display operation unit 30 (display unit 30a and operation unit 30b) is positioned so that it can be seen and operated by the operator.

[0041] As shown in Figure 4, the alarm unit 40 includes lamps 40a, 40b, and 40c, each indicating a different type of alarm. Lamp 40a is configured to light up when any malfunction occurs. Lamp 40b is configured to light up during defrosting operation. Lamp 40c is configured to light up when it is time to replace the filter. The alarm unit 40 is positioned in a location visible to the operator. Defrosting operation is a function that stops the operation of the compressor 1 (see Figure 1) in order to remove frost from inside the cooling device 100. During defrosting operation, the control unit 20 is configured to control the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 (see Figure 1) so as to set them to approximately their minimum opening to prevent backflow of refrigerant.

[0042] (Control process to set the electronic expansion valve opening to its maximum opening) Next, with reference to Figure 5, the control process for setting the opening degree of the first electronic expansion valve 3 and the second electronic expansion valve 5 in this embodiment to their maximum opening degree will be described.

[0043] As shown in Figure 5, in step S1, the control unit 20 receives the input "Refrigerant charging opening adjustment function: Enabled". Specifically, the control unit 20 receives a control input via the operation unit 30b to enable the refrigerant charging opening adjustment function. Upon receiving the control input to enable the refrigerant charging opening adjustment function, the control unit 20 switches from normal mode to forced opening control mode and displays the letters "RF" on the display unit 30a (see Figure 3) to indicate that it is in forced opening control mode. The normal mode is a mode that performs cooling operations and defrosting operations other than forced opening control mode.

[0044] Next, in step S2, the control unit 20 controls the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to the minimum opening (0%) by reducing the opening degree by more than the movable stroke of the first electronic expansion valve 3 and the second electronic expansion valve 5. As shown in Figure 2, the movable stroke of the first electronic expansion valve 3 and the second electronic expansion valve 5 is the difference between the minimum opening degree (0%) and the maximum opening degree (100%), which is 500 pls when converted to a pulse signal. In other words, the control that reduces the opening degree by more than the movable stroke of the first electronic expansion valve 3 and the second electronic expansion valve 5 is the control that provides the first electronic expansion valve 3 and the second electronic expansion valve 5 with a pulse signal of -500 pls. As mentioned above, if the first electronic expansion valve 3 and the second electronic expansion valve 5 are given a pulse signal that further reduces the opening degree from the minimum opening degree (0%), the opening degree will remain at the minimum opening degree (0%). Therefore, regardless of the opening degree of the first electronic expansion valve 3 and the second electronic expansion valve 5 after step S1, the minimum opening degree can be achieved by applying a pulse signal of -500 pls.

[0045] Next, in step S3, the control unit 20 performs a base point setting (origin setting). Specifically, in the state after step S2 (when the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 are at their minimum opening), the pulse signal is reset to zero. Note that the pulse signal is an example of the "control signal" in the claims. At the end of step S3, the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 are at their minimum opening (0%), and the pulse signal is 0 pls.

[0046] Next, in step S4, the control unit 20 sets the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to the maximum opening (100%). Specifically, the control unit 20 sets the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to the maximum opening (100%) by supplying a pulse signal of +500 pls to the first electronic expansion valve 3 and the second electronic expansion valve 5. In other words, the control unit 20 uses the pulse signal that was reset to zero in step S3 to set the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to the maximum opening (100%).

[0047] The opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 are transmitted to the control unit 20 via control lines (not shown). The control unit 20 is configured to simultaneously flash lamps 40a, 40b, and 40c (see Figure 4) when the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 reach their maximum opening degrees in step S4. At any other timing besides step S4, lamps 40a, 40b, and 40c will not flash simultaneously.

[0048] In this embodiment, when the control unit 20 receives a control input to enable the refrigerant filling opening adjustment function, in steps S2 to S4, it sets the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to their maximum opening without performing opening control of the first electronic expansion valve 3 and the second electronic expansion valve 5 by other controls. Other controls include temperature adjustment control during normal cooling operation and defrosting operation. In temperature adjustment control during normal cooling operation, the control unit 20 adjusts the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to reach the set temperature. In defrosting operation, as described above, the control unit 20 controls the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to approximately the minimum opening in order to prevent backflow of refrigerant.

[0049] Furthermore, the real-time opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 can be displayed on the display unit 30a (see Figure 3) by the operator operating the control unit 30b. In other words, in addition to the simultaneous flashing of lamps 40a, 40b, and 40c, the operator can recognize that the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 have reached their maximum by visually checking the real-time opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 displayed on the display unit 30a.

[0050] In step S4, after the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 reach their maximum opening degrees, the operator turns off the power to the cooling device 100 and performs the desired operation (vacuuming, refrigerant charging, etc.). At this time, the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 are maintained at the maximum opening degrees they were at when the power was turned off. After the desired operation is completed, the operator turns on the power to the cooling device 100 and performs the subsequent operation. Note that when the power is turned on, the refrigerant charging opening degree adjustment function remains active, so the operator can start the cooling operation by inputting a control to disable the refrigerant charging opening degree adjustment function via the operation unit 30b (see Figure 3). When the control unit 20 receives a control input to disable the refrigerant charging opening degree adjustment function, it releases the forced opening degree control mode and sets the base point for the first electronic expansion valve 3 and the second electronic expansion valve 5.

[0051] (Effects of the embodiment) Next, the effects of this embodiment will be described.

[0052] In this embodiment, as described above, when the control unit 20 receives a control input to enable the refrigerant filling opening degree adjustment function for forcibly opening the first electronic expansion valve 3 and the second electronic expansion valve 5, it sets the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 to an opening degree greater than or equal to the normally used opening degree. As a result, by inputting a control input to enable the refrigerant filling opening degree adjustment function before the refrigerant flow path 11 is brought into a vacuum state, the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 can be opened to an opening degree greater than or equal to the opening degree at that time. Therefore, it is possible to suppress the formation of a refrigerant flow path 11 that communicates with other parts only by electronic expansion valves that are not sufficiently open (first electronic expansion valve 3 and second electronic expansion valve 5), thereby reducing the pressure loss due to the first electronic expansion valve 3 and the second electronic expansion valve 5 when the refrigerant flow path 11 is brought into a vacuum state. As a result, the time required to bring the refrigerant flow path 11 into a vacuum state can be reduced.

[0053] Furthermore, in this embodiment, as described above, when the control unit 20 receives a control input to enable the refrigerant filling opening adjustment function, it sets the opening of the first electronic expansion valve and the second electronic expansion valve 5 to their maximum opening. This makes it possible to more effectively reduce the pressure loss caused by the first electronic expansion valve and the second electronic expansion valve 5 when the refrigerant flow path 11 is brought into a vacuum state.

[0054] Furthermore, in this embodiment, as described above, when the control unit 20 receives a control input to enable the refrigerant filling opening adjustment function, it sets the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to an opening greater than or equal to the normally used opening (maximum opening) without performing opening control of the first electronic expansion valve 3 and the second electronic expansion valve 5 by other controls. This prevents the opening of the first electronic expansion valve and the second electronic expansion valve 5 from unintentionally becoming smaller due to other controls when the refrigerant flow path 11 is brought into a vacuum state.

[0055] Furthermore, in this embodiment, as described above, the control that enables the refrigerant filling opening adjustment function is used to forcibly open the electronic expansion valve when filling with refrigerant. By enabling the refrigerant filling opening adjustment function when filling with refrigerant, it is possible to suppress the formation of a refrigerant flow path 11 that communicates with other parts only through electronic expansion valves that are not sufficiently open (first electronic expansion valve 3 and second electronic expansion valve 5), thereby suppressing uneven filling of the refrigerant.

[0056] Furthermore, in this embodiment, as described above, the compressor 1 includes a first compression section 1a and a second compression section 1b that further compresses the refrigerant compressed by the first compression section 1a, the gas cooler 2 cools the refrigerant supplied from the second compression section 1b, the electronic expansion valve includes a first electronic expansion valve 3 that expands a portion of the refrigerant cooled by the gas cooler 2 and a second electronic expansion valve 5 that expands the remaining refrigerant cooled by the gas cooler 2, the evaporator 4a that evaporates the refrigerant expanded in the first electronic expansion valve 3 and supplies it to the second compression section 1b, and the cooling section 4b that cools the remaining refrigerant cooled by the gas cooler 2, and further includes an intermediate heat exchanger 4 that performs heat exchange between the refrigerant in the evaporator 4a and the refrigerant in the cooling section 4b and is located upstream of the second electronic expansion valve 5, and the control unit 20, when it receives a control input to enable the refrigerant filling opening adjustment function, sets the opening of at least the first electronic expansion valve 3 to its maximum opening. In this case, where the refrigerant flow path 11 is divided into a refrigerant flow path 11 between the compressor 1 and the second electronic expansion valve 5 on the upstream side of the compressor 1 (low-pressure refrigerant flow path 11b), a refrigerant flow path 11 between the compressor 1 and the first electronic expansion valve 3 or the second electronic expansion valve 5 on the downstream side of the compressor 1 (high-pressure refrigerant flow path 11a), and a refrigerant flow path 11 between the first electronic expansion valve 3 and the second compression section 1b (intermediate-pressure refrigerant flow path 11c), by setting the opening of at least the first electronic expansion valve 3 to its maximum opening, the pressure loss due to the first electronic expansion valve 3 between the intermediate-pressure refrigerant flow path 11c and the high-pressure refrigerant flow path 11a can be reduced, and the high-pressure refrigerant flow path 11a and the intermediate-pressure refrigerant flow path 11c can be quickly brought to a vacuum state through a single maintenance port (second port 10b). As a result, it becomes unnecessary to provide three maintenance ports corresponding to the low-pressure refrigerant flow path 11b, the high-pressure refrigerant flow path 11a, and the medium-pressure refrigerant flow path 11c, respectively, in order to create a vacuum in the entire refrigerant flow path 11, thus simplifying the overall structure of the cooling device 100.

[0057] Furthermore, in this embodiment, as described above, a service port 10 capable of communicating the inside and outside of the refrigerant flow path 11 is further provided. The service port 10 includes a first port 10a located in the low-pressure side refrigerant flow path 11b connecting the second electronic expansion valve 5 and the first compression unit 1a, and a second port 10b located in the high-pressure side refrigerant flow path 11a connecting the second compression unit 1b and the first electronic expansion valve 3 or the second electronic expansion valve 5. In this way, even if the service port 10 is not located in the intermediate-pressure side refrigerant flow path 11c between the first electronic expansion valve 3 and the second compression unit 1b, the pressure loss due to the first electronic expansion valve 3 between the intermediate-pressure side refrigerant flow path 11c and the high-pressure side refrigerant flow path 11a can be reduced by setting the opening degree of the first electronic expansion valve 3 to its maximum opening degree. Therefore, the entire refrigerant flow path 11 can be quickly brought to a vacuum state by the two service ports 10 (first port 10a and second port 10b).

[0058] Furthermore, in this embodiment, as described above, when the control unit 20 receives a control input to enable the refrigerant filling opening adjustment function, it controls the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to the minimum opening by reducing the opening by more than the movable stroke of the first electronic expansion valve 3 and the second electronic expansion valve 5. After resetting the pulse signals of the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to zero, it performs a base point setting, and then uses the pulse signals reset to zero to set the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to the maximum opening. As a result, even if the control unit 20 cannot accurately recognize the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 at the time it receives a control input to enable the refrigerant filling opening adjustment function, it can accurately recognize the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 by performing a base point setting (origin setting), and thus can accurately set the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to the maximum opening.

[0059] Furthermore, in this embodiment, as described above, an alarm unit 40 is further provided to notify the operator when the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 reaches its maximum opening. This allows the operator to easily recognize when the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 has reached its maximum opening. As a result, usability (user convenience) can be improved.

[0060] Furthermore, in this embodiment, as described above, the control unit 20 switches from normal mode to forced opening control mode when it receives a control input to enable the refrigerant filling opening adjustment function, and in forced opening control mode, it is configured to set the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to their maximum opening. The control unit 20 is further provided with a display unit 30a that indicates that it is in forced opening control mode. This allows the operator to easily recognize that it has entered forced opening control mode. As a result, usability (user convenience) can be improved.

[0061] [Differentiation] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and further includes all modifications (exceptions) within the meaning and scope equivalent to the claims.

[0062] In the above embodiment, the control unit 20 is shown to set the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to their maximum opening when it receives a control input to enable the refrigerant filling opening adjustment function, but the present invention is not limited to this. For example, the control unit 20 may be configured to set the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to an opening greater than or equal to the opening that is normally used when it receives a control input to enable the refrigerant filling opening adjustment function. Even with this configuration, where the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 is greater than or equal to the opening that is normally used, the time required to bring the refrigerant flow path 11 into a vacuum state can be reduced.

[0063] Furthermore, in the above embodiment, when the control unit 20 receives a control input to enable the refrigerant filling opening degree adjustment function, it is shown as an example in which it does not perform opening degree control of the first electronic expansion valve 3 and the second electronic expansion valve 5 by other controls. However, the present invention is not limited to this. For example, when the control unit 20 receives a control input to enable the refrigerant filling opening degree adjustment function, it may be possible to perform opening degree control of the first electronic expansion valve 3 and the second electronic expansion valve 5 by other controls. However, in that case, it is preferable to turn off other control functions that perform opening degree control of the first electronic expansion valve 3 and the second electronic expansion valve 5 by operation by an operator. Furthermore, in the above embodiment, the other controls are shown as examples such as temperature adjustment control during normal cooling operation and defrosting operation. However, the present invention is not limited to this. For example, the other controls may be any controls that perform opening degree control of the first electronic expansion valve 3 and the second electronic expansion valve 5.

[0064] Furthermore, although the above embodiment shows an example where the compressor 1 is a two-stage compressor, the present invention is not limited to this. For example, the compressor 1 may be a single-stage compressor. In that case, the first electronic expansion valve 3, the intermediate heat exchanger 4, and the intercooler 9 may be omitted.

[0065] Furthermore, although the above embodiment shows an example in which the cooling device 100 includes an intermediate heat exchanger 4, the present invention is not limited to this. For example, the cooling device 100 does not have to include an intermediate heat exchanger 4. In that case, the first electronic expansion valve 3 also does not have to be included.

[0066] Furthermore, although the above embodiment shows an example in which one evaporator 6 is provided, the present invention is not limited to this. For example, when cooling multiple showcases with one compressor 1, multiple evaporators 6 may be provided to correspond to each showcase. In that case, multiple second electronic expansion valves 5 will also be provided to correspond to the multiple evaporators 6.

[0067] Furthermore, although the above embodiment shows an example in which two service ports 10 are provided, the present invention is not limited thereto. For example, one service port 10 may be provided, or three or more may be provided, as long as at least one is provided in each of the high-pressure side refrigerant flow path 11a, the low-pressure side refrigerant flow path 11b, and the intermediate-pressure side refrigerant flow path 11c.

[0068] Furthermore, although the above embodiment shows an example in which the intermediate-pressure refrigerant flow path 11c does not have a service port 10, the present invention is not limited thereto. For example, a service port 10 may be provided in the intermediate-pressure refrigerant flow path 11c, as long as at least one is not provided in each of the high-pressure refrigerant flow path 11a, low-pressure refrigerant flow path 11b, and intermediate-pressure refrigerant flow path 11c.

[0069] Furthermore, in the above embodiment, when the control unit 20 receives a control input to enable the refrigerant-filling opening degree adjustment function, it performs control to reduce the opening degree of the first electronic expansion valve 3 and the second electronic expansion valve 5 by more than the movable stroke of the first electronic expansion valve 3 and the second electronic expansion valve 5, thereby setting the opening degree of the first electronic expansion valve 3 and the second electronic expansion valve 5 to the minimum opening degree, then performs a baseline reset by resetting the pulse signals of the opening degree of the first electronic expansion valve 3 and the second electronic expansion valve 5 to zero, and then uses the reset pulse signals to set the opening degree of the first electronic expansion valve 3 and the second electronic expansion valve 5 to the maximum opening degree. However, the present invention is not limited to this. For example, as shown in the flowchart of the modified example in Figure 6, when the control unit 20 receives a control input to enable the refrigerant-filling opening degree adjustment function, it may perform control to increase the opening degree of the first electronic expansion valve 3 and the second electronic expansion valve 5 by more than the movable stroke of the first electronic expansion valve 3 and the second electronic expansion valve 5, thereby setting the opening degree of the first electronic expansion valve 3 and the second electronic expansion valve 5 to the maximum opening degree.

[0070] As shown in Figure 6, in step S11, the control unit 20 receives the input "Refrigerant charging opening adjustment function: Enabled". Specifically, the control unit 20 receives the input to enable the refrigerant charging opening adjustment function via the operation unit 30b. Next, in step S12, the control unit 20 controls the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 to the maximum opening (100%) by increasing the opening by more than the movable stroke of the first electronic expansion valve 3 and the second electronic expansion valve 5. As shown in Figure 2, the movable stroke of the first electronic expansion valve 3 and the second electronic expansion valve 5 is the difference between the minimum opening (0%) and the maximum opening (100%), which is 500 pls when converted to a pulse signal. In other words, the control that increases the opening by more than the movable stroke of the first electronic expansion valve 3 and the second electronic expansion valve 5 is the control that provides the first electronic expansion valve 3 and the second electronic expansion valve 5 with a pulse signal of +500 pls. As mentioned above, if the first electronic expansion valve 3 and the second electronic expansion valve 5 are given a pulse signal that increases their opening degree further from the maximum opening degree (100%), their opening degree will remain at the maximum opening degree (100%).

[0071] By controlling the valves as shown in steps S11 and S12 in Figure 6, the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 can be quickly set to their maximum opening.

[0072] Furthermore, in the above embodiment, the alarm unit 40 is shown to notify the user that the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 have reached their maximum opening. However, the present invention is not limited to this. For example, the alarm unit 40 does not need to notify the user that the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 have reached their maximum opening. Even in that case, the operator can recognize that the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 have reached their maximum opening by checking the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 displayed on the display unit 30a.

[0073] Furthermore, in the above embodiment, the alarm unit 40 flashes all three lamps 40a, 40b, and 40c simultaneously when notifying the user that the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 has reached its maximum opening. However, the present invention is not limited to this. For example, lamps 40a, 40b, and 40c may be lit one by one in sequence. In addition, a separate lamp may be provided to notify the user that the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 has reached its maximum opening, and this lamp may be lit. Moreover, the means for notifying the user that the opening of the first electronic expansion valve 3 and the second electronic expansion valve 5 has reached its maximum opening is not limited to lamps; it may also be done by generating sound using a buzzer or by notification from a higher-level management system.

[0074] Furthermore, although the above embodiment shows an example in which the control unit 20 is equipped with a display unit 30a that indicates that the control unit 20 is in forced opening control mode, the present invention is not limited thereto. For example, the display unit 30a does not have to indicate that the control unit 20 is in forced opening control mode. Also, when the control unit 20 is in forced opening control mode, it may display "OFF" on the display unit 30a, similar to the case when cooling is stopped (not cooling).

[0075] Furthermore, although the above embodiment shows an example where the pulse signal corresponding to the movable stroke of the first electronic expansion valve 3 and the second electronic expansion valve 5 is 500 pls, the present invention is not limited to this. For example, the pulse signal corresponding to the movable stroke of the first electronic expansion valve 3 and the second electronic expansion valve 5 may be other than 500 pls.

[0076] Furthermore, in the above embodiment, Figure 2 shows an example where the relationship between the pulse signal and the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 is linear (straight-line), but the present invention is not limited to this. For example, the relationship between the pulse signal and the opening degrees of the first electronic expansion valve 3 and the second electronic expansion valve 5 may include a curve.

[0077] Furthermore, in the above embodiment, the refrigerant filling opening adjustment function was shown to be used to forcibly open the first electronic expansion valve 3 and the second electronic expansion valve 5 when creating a vacuum state in the entire refrigerant flow path 11 before refrigerant filling, when filling the refrigerant, and when discharging refrigerant already present in the refrigerant flow path 11 before refrigerant filling, but the present invention is not limited to this. For example, the refrigerant filling opening adjustment function may be used when discharging refrigerant present in the refrigerant flow path 11 before discarding the cooling device 100.

[0078] Furthermore, although the above embodiment shows an example in which an operator inputs a control to disable the refrigerant filling opening degree adjustment function via the operation unit 30b (see Figure 3), the present invention is not limited to this. For example, if a certain amount of time has elapsed since the control unit 20 received a control input to enable the refrigerant filling opening degree adjustment function, the control unit 20 may automatically disable the refrigerant filling opening degree adjustment function. Also, if a certain amount of time has elapsed since the control unit 20 received a control input to enable the refrigerant filling opening degree adjustment function, the control unit 20 may notify the operator via the display unit 30a and the alarm unit 40, etc., that a certain amount of time has elapsed since the control input to enable the refrigerant filling opening degree adjustment function was received. In addition, the control unit 20 may automatically disable the refrigerant filling opening degree adjustment function when the power is turned on from an off state.

[0079] Furthermore, although the above embodiment shows an example where the control input for enabling the refrigerant filling opening degree adjustment function is performed via the display operation unit 30, the present invention is not limited to this. For example, the control input for enabling the refrigerant filling opening degree adjustment function may be performed via a maintenance terminal connected to the cooling device 100 by wire or wireless, a higher-level management system, and a hard switch.

[0080] Furthermore, although the above embodiment shows an example in which a gas cooler 2 for cooling a refrigerant is applied as the "cooler" in the claims, the present invention is not limited to this. For example, a condenser for cooling and condensing a refrigerant may be applied as the "cooler" in the claims. [Explanation of Symbols]

[0081] 1. Compressor 1a First compression section 1b Second Compression Section 2. Gas cooler (cooler) 3. First Electronic Expansion Valve 4 Intermediate heat exchanger 4a Evaporation section 4b Cooling section 5. Second Electronic Expansion Valve 6. Evaporator 10. Service Port (Maintenance Port) 10a Port 1 10b Port 2 11 Refrigerant flow path 20 Control Unit 30a Display section 40. Alarm Department (Notification Department) 100 Cooling device

Claims

1. A compressor that compresses the refrigerant flowing through the refrigerant passage, A cooler for cooling the refrigerant supplied from the compressor, An electronic expansion valve expands the refrigerant cooled by the aforementioned cooler, and its opening degree can be controlled. An evaporator that cools the object to be cooled by evaporating the refrigerant expanded by the aforementioned electronic expansion valve, The system includes a control unit that controls the opening degree of the electronic expansion valve, The cooling device, when the control unit receives an input for forced opening control to forcibly open the electronic expansion valve, sets the opening of the electronic expansion valve to an opening greater than or equal to the normally used opening.

2. The cooling device according to claim 1, wherein the control unit, upon receiving input for the forced opening control, sets the opening of the electronic expansion valve to its maximum opening.

3. The cooling device according to claim 1, wherein when the control unit receives an input for the forced opening control, it sets the opening of the electronic expansion valve to an opening greater than or equal to the normally used opening without performing opening control of the electronic expansion valve by other control methods.

4. The cooling apparatus according to claim 1, wherein the forced opening control includes control that enables a refrigerant filling opening adjustment function for forcibly opening the electronic expansion valve when a refrigerant is filled.

5. The compressor includes a first compression section and a second compression section that further compresses the refrigerant compressed by the first compression section. The cooler cools the refrigerant supplied from the second compression unit, The electronic expansion valve includes a first electronic expansion valve that expands a portion of the refrigerant cooled by the cooler, and a second electronic expansion valve that expands the remaining refrigerant cooled by the cooler. The system includes an evaporation section that evaporates the refrigerant expanded in the first electronic expansion valve and supplies it to the second compression section, and a cooling section in which the remaining refrigerant from the refrigerant cooled by the cooler is cooled, and further includes an intermediate heat exchanger located upstream of the second electronic expansion valve, which performs heat exchange between the refrigerant in the evaporation section and the refrigerant in the cooling section. The cooling device according to claim 1, wherein when the control unit receives an input for the forced opening control, it sets the opening of the first electronic expansion valve to at least an opening greater than or equal to the opening normally used.

6. The refrigerant flow path is further provided with a maintenance port that allows communication between the inside and outside of the refrigerant flow path. The cooling apparatus according to claim 5, wherein the maintenance port includes a first port disposed in the refrigerant flow path connecting the second electronic expansion valve and the first compression unit, and a second port disposed in the refrigerant flow path connecting the second compression unit and the first electronic expansion valve or the second electronic expansion valve.

7. The cooling device according to claim 1, wherein when the control unit receives the input for the forced opening control, it controls the electronic expansion valve to reduce its opening by more than the movable stroke of the electronic expansion valve, thereby setting the opening of the electronic expansion valve to its minimum opening, resets the control signal for the opening of the electronic expansion valve to zero, and then uses the zero-reset control signal to set the opening of the electronic expansion valve to an opening greater than or equal to the normally used opening.

8. The cooling device according to claim 1, further comprising a notification unit that notifies the user when the opening of the electronic expansion valve becomes greater than or equal to the opening used under normal circumstances.

9. The control unit, When the input for the forced opening control is received, the mode changes from normal mode to forced opening control mode. In the forced opening control mode, the opening of the electronic expansion valve is configured to be greater than or equal to the opening used under normal circumstances. The cooling device according to claim 1, further comprising a display unit that indicates that the control unit is in the forced opening control mode.

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