JP2019184232A - Cooling device - Google Patents

Abstract

An object of the present invention is to provide a cooling device that can reliably protect a heat exchanger disposed in a low-pressure system with a high response to a change in pressure of a refrigerant gas. A compressor C for compressing a refrigerant gas drawn from a low-pressure system, a cooler 3 for cooling the refrigerant gas compressed by the compressor C and discharged to a high-pressure system, and a refrigerant cooled by the cooler 3 A cooling device 1 comprising: an expander E for expanding a gas; and a heat exchanger 5 for cooling an object to be cooled by a refrigerant gas expanded by the expander E and discharged to a low-pressure system, wherein the refrigerant gas is sealed. And a low-pressure on-off valve 9 for opening and closing the low-pressure connection path 6b for connecting the low-pressure connection path 6b to the low-pressure connection path 6b. It is connected to the low pressure system on the more upstream side. [Selection diagram] Fig. 1

Description

  The present invention relates to a cooling device using a refrigerant gas refrigeration cycle such as nitrogen gas.

  2. Description of the Related Art Cooling devices that are applied to cooling rooms such as warehouses for storing various materials, processed products, fresh foods, and the like are widely known. In such a cooling device, a refrigerant such as chlorofluorocarbon has been conventionally used. However, in recent years, a cooling device using a refrigerant gas such as air or nitrogen gas has been demanded from the viewpoint of environmental conservation.

  As a cooling device using a refrigerant gas, in a refrigerant gas circulation path through which the refrigerant gas circulates, a compressor that compresses the refrigerant gas in the refrigerant gas circulation path, and a high-pressure and high-temperature refrigerant gas compressed by the compressor are cooled. A cooling object is cooled by a water-cooled heat exchanger (cooler), an expander that expands the high-pressure and low-temperature refrigerant gas cooled by the water-cooled heat exchanger, and a low-temperature and low-pressure refrigerant gas expanded by the expander. A hermetic cooling device provided with a brine cooler (heat exchanger) is known. Some compressors and expanders are configured as compression / expansion units connected to a single drive shaft of a motor (see Patent Document 1).

  In such a hermetic cooling device, since the volume in the refrigerant gas circulation path through which the refrigerant gas flows is constant, the refrigerant in the compressor is smaller than in normal operation when the motor speed is low. The gas compression ratio is low, and the pressure of the refrigerant gas in the high-pressure piping equipment system (hereinafter referred to as the high-pressure system) arranged from the compressor discharge side to the expander suction side is relatively low. Further, the refrigerant gas is not sufficiently expanded (decompressed) in the expander, and the pressure of the refrigerant gas in the low-pressure piping system (hereinafter referred to as the low-pressure system) disposed from the expander discharge side to the compressor suction side is low. Since the pressure is relatively high, a load is applied to the low-pressure piping and equipment constituting the low-pressure system, and a part of the refrigerant gas in the low-pressure system may be discharged to reduce the pressure. On the other hand, in a state where the rotation speed of the motor is increased, the compression ratio of the refrigerant gas in the compressor is high, the pressure of the refrigerant gas in the high-pressure system is relatively high, and the expansion of the refrigerant gas in the expander (Pressure reduction) is performed excessively, and the pressure of the refrigerant gas in the low-pressure system becomes relatively low. In some cases, the low-pressure system is lower than the atmospheric pressure. There was a risk of getting in.

  Therefore, the hermetic cooling device of Patent Document 1 includes a hermetically sealed container in which refrigerant gas is sealed, a recovery path (high-pressure connection path) that connects the hermetic container and the high-pressure system, and a replenishment path that connects the hermetic container and the low-pressure system. A closed system refrigerant gas supply / discharge device mainly composed of (low pressure connection path), a pressure sensor for detecting the pressure of the refrigerant gas flowing through the low pressure system, and an electromagnetic valve (open / close valve) provided in each of the supply path and the recovery path And a controller for performing opening / closing control of. Therefore, for example, when the pressure of the refrigerant gas flowing through the low pressure system exceeds the upper design limit due to a decrease in the number of revolutions of the motor, the controller opens the solenoid valve provided in the recovery path, and the high pressure via the recovery path By collecting a part of the refrigerant gas in the system in a sealed container, the amount of the refrigerant gas expanded by the expander is limited to suppress an increase in pressure in the low-pressure system, thereby adjusting the pressure. In addition, when the pressure of the refrigerant gas flowing through the low-pressure system falls below the design lower limit due to the increase in the number of rotations of the motor, the controller opens the solenoid valve provided in the replenishment path and closes the sealed container via the replenishment path. By supplying the refrigerant gas in the low-pressure system, the amount of refrigerant gas flowing into the compressor and the expander is increased, and the pressure in the low-pressure system is increased to adjust the pressure.

Japanese Patent No. 5934482 (page 6, FIG. 1)

  However, in the cooling device of Patent Document 1, the supply path connecting the sealed container and the low-pressure system is connected in the vicinity of the compressor suction side downstream of the heat exchanger arranged in the low-pressure system. Installed upstream of the low-pressure system until the refrigerant gas supplied from the closed container to the low-pressure system through the replenishment path is discharged to the low-pressure system again via the compressor and the expander. However, the heat exchanger to be used continues to be affected by the change in pressure of the refrigerant gas, and there is a problem that failure or breakage is likely to occur.

  The present invention has been made paying attention to such problems, and is a cooling device that can protect a heat exchanger arranged in a low-pressure system with high responsiveness to a pressure change of refrigerant gas and with certainty. The purpose is to provide.

In order to solve the above problems, the cooling device of the present invention includes:
A compressor that compresses refrigerant gas sucked from the low-pressure system, a cooler that cools the refrigerant gas compressed by the compressor and discharged to the high-pressure system, and an expander that expands the refrigerant gas cooled by the cooler And a heat exchanger that cools an object to be cooled with a refrigerant gas that is expanded by the expander and discharged to the low-pressure system,
A sealed container in which refrigerant gas is sealed, a low-pressure connection path that connects the sealed container and the low-pressure system, and a low-pressure on-off valve that opens and closes the low-pressure connection path,
The low-pressure connection path is connected to the low-pressure system on the upstream side of the heat exchanger.
According to this feature, when the refrigerant gas in the low-pressure system exceeds the designed pressure range, the low-pressure on-off valve is opened to connect the low-pressure system and the sealed container to adjust the amount of refrigerant gas in the low-pressure system. Thus, it is possible to protect the pressure of refrigerant gas flowing into the heat exchanger installed on the downstream side of the low-pressure connection path with high response and reliability.

The low-pressure connection path is connected to the low-pressure system on the upstream side of the heat exchanger and the exhaust heat recovery heat exchanger using the return refrigerant gas from the heat exchanger.
According to this feature, in addition to the heat exchanger, it is possible to reliably and reliably protect against a change in pressure of the refrigerant gas flowing into the exhaust heat recovery heat exchanger installed downstream of the low pressure connection path. it can.

The low-pressure on-off valve is controlled to open and close based on the rotational speed of the drive shaft of the compressor.
According to this feature, the low-pressure on-off valve can be controlled to open and close based on fluctuations in the rotational speed of the compressor drive shaft, which is the beginning of the refrigerant gas pressure change. Can protect the exchanger.

The low-pressure connection path is provided with a flow rate adjusting unit that adjusts the flow rate of the refrigerant gas flowing through the low-pressure connection path.
According to this feature, the refrigerant gas of the low-pressure system is eliminated from the inside of the closed container in a short time and in large quantities via the low-pressure on-off valve, and the flow rate of the refrigerant gas is adjusted by the flow rate adjustment unit. Sudden pressure fluctuations are suppressed, and the accuracy of pressure control can be increased.

It is further provided with the high voltage | pressure connection path which connects the said airtight container and the said high voltage | pressure system, and the high voltage | pressure on-off valve which opens and closes the said high voltage | pressure connection path.
According to this feature, when the pressure of the refrigerant gas in the low-pressure system exceeds the upper design limit, the high-pressure system refrigerant gas can be quickly collected in the sealed container by opening the high-pressure on-off valve. Can do.

The high-pressure connection path is connected to the high-pressure system on the upstream side of the exhaust heat recovery heat exchanger that uses the return refrigerant gas from the heat exchanger.
According to this feature, the refrigerant gas before passing through the exhaust heat recovery heat exchanger can be recovered in the sealed container via the high-pressure connection path. By supplying it to the low-pressure system, it can be used as a part of the temperature raising bypass line.

The high-pressure on-off valve is controlled to open and close based on the rotational speed of the drive shaft of the compressor.
According to this feature, the high-pressure on-off valve can be controlled to open and close based on fluctuations in the rotational speed of the compressor drive shaft, which is the starting point of refrigerant gas pressure fluctuations. Can protect the exchanger.

A bypass channel connecting between the high-pressure system and the low-pressure system, and a balance valve capable of opening and closing the bypass channel,
The bypass flow path is connected to the high pressure system upstream of the high pressure connection path.
According to this feature, by opening the balance valve provided in the bypass flow path, the refrigerant gas can be bypassed from the high pressure system to the low pressure system upstream of the high pressure connection path. The influence of flow can be suppressed and surging can be prevented quickly.

The high-pressure connection path is provided with a flow rate adjusting unit that adjusts the flow rate of the refrigerant gas flowing through the high-pressure connection path.
According to this feature, the refrigerant gas of the high-pressure system is eliminated from flowing in a large amount in a short time into the sealed container via the high-pressure on-off valve, and the flow rate of the refrigerant gas is adjusted by the flow rate adjustment unit. Sudden pressure fluctuations are suppressed, and the accuracy of pressure control can be increased.

The high-pressure connection path is provided with a refrigerant compression section that compresses the refrigerant gas flowing through the high-pressure connection path and sends it out to the sealed container.
According to this feature, the pressure of the refrigerant existing in the high-pressure system can be forcibly increased by the refrigerant compression unit and stored in the closed container as a further high-pressure state, so that the internal capacity of the closed container can be reduced.

A cylinder for replenishing refrigerant gas is connected to the sealed container through an on-off valve.
According to this feature, when the pressure of the refrigerant gas in the sealed container decreases, the on-off valve can be opened and the refrigerant gas can be replenished from the cylinder. Can be maintained in a high state.

It is a figure which shows the cooling device using the refrigerant gas refrigerating cycle in the Example of this invention. It is a block diagram which shows the structure of the control apparatus in an Example. It is a figure which shows the flowchart of the opening / closing control of the 1st solenoid valve by the control apparatus in an Example, and a 2nd solenoid valve. It is an enlarged view which shows a part of cooling device using the refrigerant gas refrigerating cycle in the 1st modification of this invention. It is an enlarged view which shows a part of cooling device using the refrigerant gas refrigerating cycle in the 2nd modification of this invention. It is an enlarged view which shows a part of cooling device using the refrigerant gas refrigerating cycle in the 3rd modification of this invention.

  EMBODIMENT OF THE INVENTION The form for implementing the cooling device using the refrigerant gas refrigerating cycle which concerns on this invention is demonstrated below based on an Example.

  A cooling device using the refrigerant gas refrigeration cycle according to the embodiment will be described with reference to FIGS. 1 to 3.

  As shown in FIG. 1, the cooling device 1 in this embodiment is sealed in a circulation path to be described later in order to cool a cooling object such as a freezer for storing various materials, processed products, and fresh foods. The refrigerant gas refrigeration cycle using the produced refrigerant gas is configured. The cooling device 1 can be applied to refrigeration, refrigeration, air conditioning cooling, and the like depending on the temperature and pressure of the system, and is applied to a refrigeration system having a cooling temperature region suitable for the object to be cooled. Furthermore, in this embodiment, dry nitrogen gas is used as the refrigerant gas. However, the present invention is not limited to this, and various gases and air can be applied as long as the refrigerant can circulate in the closed circulation path. .

  The cooling device 1 mainly includes a compressor C (compressor), a water-cooled heat exchanger 3 (cooler), an exhaust heat recovery heat exchanger 4, an expansion turbine E (expander), and a brine cooler 5 (heat exchanger). These devices are connected in a sealed manner by various pipes as a refrigerant gas circulation path to be described later.

  In detail about the refrigerant gas circulation path, the high temperature side pipe 3a of the water-cooled heat exchanger 3 is connected to the downstream side (discharge side) of the compressor C via the pipe 7a. The high temperature side pipe 4a of the exhaust heat recovery heat exchanger 4 is connected to the downstream side of the high temperature side pipe 3a of the water-cooled heat exchanger 3 via a pipe 7b, and the high temperature side pipe of the exhaust heat recovery heat exchanger 4 is connected. The expansion turbine E is connected to the downstream side of 4a via a pipe 7c, and the refrigerant gas pipe 5a of the brine cooler 5 is connected to the downstream side (discharge side) of the expansion turbine E via a pipe 7d. Has been. A low temperature side pipe 4b of the exhaust heat recovery heat exchanger 4 is connected to the downstream side of the refrigerant gas pipe 5a of the brine cooler 5 via a pipe 7e, and a low temperature side pipe 4b of the exhaust heat recovery heat exchanger 4 is connected. The compressor C is connected to the downstream side of this via a pipe 7f.

  In this embodiment, the pipe 7a disposed between the downstream side (discharge side) of the compressor C for compressing the refrigerant gas and the upstream side (suction side) of the expansion turbine E, the water-cooled heat exchanger 3 ( The high temperature side pipe 3a), the pipe 7b, the exhaust heat recovery heat exchanger 4 (high temperature side pipe 4a) and the pipe 7c constitute a high pressure system, and from the downstream side (discharge side) of the expansion turbine E which expands the refrigerant gas. Pipe 7d, brine cooler 5 (refrigerant gas pipe 5a), pipe 7e, exhaust heat recovery heat exchanger 4 (low temperature side pipe 4b), and pipe 7f arranged between the upstream side (suction side) of compressor C Will be described as a low-pressure system.

  Further, a bypass pipe 16 a (bypass flow path) is connected to the pipe 7 b constituting the high-pressure system, and the bypass pipe 16 a is configured to be able to open and close the flow path by the balance valve 14. On the downstream side of the balance valve 14 provided in the bypass pipe 16a, a three-way switching valve 15 is provided, and one branch bypass pipe 16b branched from the three-way switching valve 15 is connected to the pipe 7f constituting the low-pressure system, and the other A branch bypass pipe 16c is connected to a pipe 7d constituting the low-pressure system. The other branch bypass pipe 16c that branches from the three-way switching valve 15 is configured to perform defrosting of the low-pressure system by directly supplying high-temperature refrigerant gas from the pipe 7b that configures the high-pressure system to the pipe 7d that configures the low-pressure system. It functions as a temperature-increasing bypass line.

  The pipe 7b constituting the high-pressure system is connected to a connecting pipe 6a (high-pressure connection path) at a position downstream of the bypass pipe 16a, and the pipe 7d constituting the low-pressure system is connected to the three-way switching valve 15. The connection pipe 6b (low-pressure connection path) is connected via the other branch bypass pipe 16c that branches from the expansion tank, so that the expansion tank as a sealed container is connected between the high-pressure system and the low-pressure system via the connection pipes 6a and 6b. 6 is connected. The connection pipe 6a is configured to open and close the flow path by the first electromagnetic valve 8 (high pressure on-off valve), and the connection pipe 6b can be opened and closed by the second electromagnetic valve 9 (low pressure on-off valve). It is configured.

  The compressor C and the expansion turbine E are driven by the motor 10. The motor 10 includes a pair of drive shafts 10a and 10b extending on the same axis, to which a compressor C and an expansion turbine E are connected, and is generated by a high-pressure refrigerant gas upstream (suction side) of the expansion turbine E. The rotational power of the expansion turbine E is transmitted to the drive shaft 10a of the compressor C via the drive shaft 10b, so that the power is recovered.

  The motor 10 is connected to an air cooling circulation passage 12 through which air is circulated by an air cooling fan F, and the motor 10 is cooled by the fan F and the air cooling circulation passage 12. . The air cooling circulation channel 12 is connected to a radiator 13 that exchanges heat with the air in the air cooling circulation channel 12.

  Further, the motor 10 is provided with a rotation speed meter for detecting the rotation speed of the drive shaft 10a of the compressor C (hereinafter also simply referred to as the drive shaft 10a). As a method for detecting the rotational speed, there are a rotary encoder type, a pulse type and the like. In this embodiment, a rotary encoder type will be described as an example. As shown in FIG. 2, the motor 10 is provided with a rotary encoder 11 for detecting the rotational speed of the drive shaft 10 a, and the rotary encoder 11 is connected to a control device 2 that controls driving of the motor 10. Yes. The control device 2 sends a control signal to the first electromagnetic valve 8 and the second electromagnetic valve 9 described above based on the rotational speed of the drive shaft 10a detected by the rotary encoder 11, whereby the first electromagnetic valve 8 and the first electromagnetic valve 8 2 The opening / closing control of the solenoid valve 9 can be performed. Further, the control device 2 is connected to a storage unit (not shown) that stores a table of data corresponding to fluctuations in the rotational speed of the drive shaft 10a of the compressor C and fluctuations in pressure in the low-pressure system. In this embodiment, the control device 2 is also connected to pressure sensors (not shown) provided at appropriate positions in the high-pressure system and the low-pressure system, and the high-pressure system and the low-pressure system detected by these pressure sensors. Based on the internal pressure, opening / closing control of the first electromagnetic valve 8 and the second electromagnetic valve 9 can be performed.

  The water-cooled heat exchanger 3 includes a high-temperature side pipe 3a through which the refrigerant gas compressed by the compressor C flows, and a low-temperature side pipe 3b that is a separate system from the high-temperature side pipe 3a and in which cooling water circulates. By performing heat exchange between the side pipe 3a and the low temperature side pipe 3b, the refrigerant gas flowing in the high temperature side pipe 3a can be cooled. The high temperature side pipe 3a and the low temperature side pipe 3b referred to here are based on the high temperature side and the low temperature side when the temperatures of the refrigerant gases flowing through the two pipes performing heat exchange in the water-cooled heat exchanger 3 are compared. Is.

  The exhaust heat recovery heat exchanger 4 includes a high temperature side pipe 4a through which the refrigerant gas cooled by the water cooling heat exchanger 3 flows, and a low temperature side pipe 4b through which the return refrigerant gas from the brine cooler 5 flows. By performing heat exchange between the high temperature side pipe 4a and the low temperature side pipe 4b, the refrigerant gas flowing in the high temperature side pipe 4a can be cooled. The high temperature side pipe 4a and the low temperature side pipe 4b referred to here are the high temperature side and the low temperature side when the temperatures of the refrigerant gas flowing through the two pipes that perform heat exchange in the exhaust heat recovery heat exchanger 4 are compared. It is based on.

  The brine cooler 5 includes a refrigerant gas pipe 5a connected to a pipe 7d through which the low-pressure refrigerant gas expanded by the expansion turbine E flows, a brine pipe 5b that is a separate system from the refrigerant gas pipe 5a, and in which the brine circulates. The brine flowing through the brine pipe 5b can be cooled by exchanging heat between the refrigerant gas pipe 5a and the brine pipe 5b. The brine pipe 5b is connected to a heat exchange pipe disposed inside the freezer, which is a cooling target (not shown), so that the cooled brine can cool the inside of the freezer by flowing through the heat exchange pipe. It has become.

  The expansion tank 6 is hermetically sealed with a predetermined internal capacity, and has pressure resistance capable of accommodating the refrigerant gas of the high-pressure system. In the expansion tank 6, dry nitrogen gas is sealed in the same manner as the refrigerant gas supplied to the refrigerant gas circulation path of the cooling device 1. The sealed pressure of the dry nitrogen gas in the expansion tank 6 is set to be higher than the pressure of the refrigerant gas in the pipe 7d constituting at least the low pressure system connected via the connection pipe 6b.

  Next, the operation | movement at the time of the cooling operation which is the normal driving | operation of the cooling device 1 is demonstrated. In the following description, on the basis of the refrigerant gas A1 (for example, about 4 kPa, about 35 ° C.) in the pipe 7f, the high pressure means a higher pressure than the refrigerant gas A1, and the low pressure means the refrigerant gas A1 indicates substantially the same pressure (within 5 kPa error), normal temperature indicates substantially the same temperature as refrigerant gas A1 (within 5 ° C error), and high temperature and low temperature are higher than normal temperature. Refers to low temperature. Note that the numerical values of the pressure and temperature of the refrigerant gas at various points in the high-pressure / low-pressure system are merely examples, and are not limited to the numerical values. In this embodiment, the numerical value of the pressure of the refrigerant gas is a difference from the atmospheric pressure (about 101 kPa), and 0 kPa indicates the atmospheric pressure.

  When the motor 10 is driven during the cooling operation, the compressor C sucks and compresses the low-pressure, normal-temperature refrigerant gas A1 (about 4 kPa, about 35 ° C.) in the pipe 7f. The high-pressure high-temperature refrigerant gas A2 (about 81 kPa, about 119 ° C.) compressed by the compressor C and heated is discharged to the high-temperature side pipe 3a of the water-cooled heat exchanger 3 through the pipe 7a.

  During the cooling operation, since the cooling water circulates in the low temperature side pipe 3b of the water cooling heat exchanger 3, the high pressure high temperature refrigerant gas A2 discharged to the high temperature side pipe 3a of the water cooling heat exchanger 3 is the water cooling heat exchanger. The heat is exchanged with the cooling water flowing in the low temperature side pipe 3b of No. 3, and becomes high-pressure high-temperature refrigerant gas A3 (about 80 kPa, about 43 ° C.), which is discharged to the high-temperature side pipe 4a of the exhaust heat recovery heat exchanger 4.

  The high-pressure high-temperature refrigerant gas A3 discharged to the high-temperature side pipe 4a of the exhaust heat recovery heat exchanger 4 is heat-exchanged with a low-pressure low-temperature refrigerant gas A6 described later flowing in the low-temperature side pipe 4b of the exhaust heat recovery heat exchanger 4, The high-pressure and low-temperature refrigerant gas A4 (about 79 kPa, about −77 ° C.) is discharged to the expansion turbine E.

  The high-pressure and low-temperature refrigerant gas A4 discharged to the expansion turbine E is expanded by the expansion turbine E, becomes low-pressure low-temperature refrigerant gas A5 (about 7 kPa, about −100 ° C.), and is discharged to the refrigerant gas pipe 5a of the brine cooler 5. .

  During the cooling operation, since the brine is circulating in the brine pipe 5b of the brine cooler 5, the low-pressure low-temperature refrigerant gas A5 discharged to the refrigerant gas pipe 5a of the brine cooler 5 is the brine pipe 5b of the brine cooler 5. Heat is exchanged with the brine flowing in the interior, and the low-pressure low-temperature refrigerant gas A6 (about 6 kPa, about −85 ° C.) is discharged to the low-temperature side pipe 4 b of the exhaust heat recovery heat exchanger 4.

  The low-pressure low-temperature refrigerant gas A6 discharged to the low-temperature side pipe 4b of the exhaust heat recovery heat exchanger 4 is heat-exchanged with the above-described high-pressure high-temperature refrigerant gas A3 flowing in the high-temperature side pipe 4a of the exhaust heat recovery heat exchanger 4. The low-pressure room-temperature refrigerant gas A1 (about 4 kPa, about 35 ° C.) is discharged to the pipe 7f.

  The pressure and temperature in the air refrigeration cycle during the cooling operation of the cooling device 1 described above are described as an example under the condition that the rotational speed of the motor 10 (drive shaft 10a of the compressor C) is about 19000 rpm.

  During the cooling operation, the control device 2 constantly monitors the number of rotations of the motor 10 detected by the rotary encoder 11, and detects the change in the number of rotations of the drive shaft 10 a of the compressor C and the change in the pressure of the low-pressure system. Inquiries are made with the storage unit that stores the table of corresponding data, and the fluctuation value of the rotational speed of the drive shaft 10a of the compressor C detected by the rotary encoder 11 exceeds the upper limit reference value or falls below the lower limit reference value. In this case, the first electromagnetic valve 8 or the second electromagnetic valve 9 can be opened by transmitting a control signal.

  In a state where the increase value of the rotation speed of the motor 10 exceeds the upper limit reference value, the compression ratio of the refrigerant gas in the compressor C becomes high, the refrigerant gas sucked into the compressor C from the pipe 7f is excessively compressed, and the high pressure system The refrigerant gas in the expansion turbine E is excessively expanded (decompressed), the pressure of the refrigerant gas in the low-pressure system is relatively low, and the refrigerant gas flowing through the low-pressure system is relatively high. The pressure of the water drops relatively greatly. At this time, when the pressure of the refrigerant gas in the low-pressure system falls below a design lower limit value (for example, atmospheric pressure), there is a possibility that outside air may enter the pipes and equipment constituting the low-pressure system.

  Therefore, when the increase value of the rotation speed of the motor 10 detected by the rotary encoder 11 exceeds the upper limit reference value, the control device 2 opens the second electromagnetic valve 9 to configure the expansion tank 6 and the low pressure system. The piping 7d communicates with the connecting piping 6b and the other branch bypass piping 16c, and the refrigerant gas sealed in the expansion tank 6 is supplied to the piping 7d constituting the low-pressure system, and the refrigerant gas flowing through the low-pressure system The pressure can be increased and adjusted to a pressure greater than atmospheric pressure (0 kPa <pressure of refrigerant gas in the low-pressure system).

  On the other hand, in a state where the lowering value of the rotational speed of the motor 10 is lower than the lower limit reference value, the refrigerant gas compression ratio in the compressor C becomes low, and the refrigerant gas sucked into the compressor C from the pipe 7f is sufficiently compressed. However, the pressure of the refrigerant gas in the high-pressure system is relatively low, the refrigerant gas is not sufficiently expanded (decompressed) in the expansion turbine E, and the pressure of the refrigerant gas flowing through the low-pressure system is relatively large. Since the pressure resistance performance of the pipes and equipment constituting the low-pressure system is a low-pressure specification, there is a risk of damage if the pressure of the refrigerant gas in the low-pressure system exceeds a design upper limit (for example, 10 kPa).

  Therefore, when the lowering value of the rotational speed of the motor 10 detected by the rotary encoder 11 falls below the lower limit reference value, the first electromagnetic valve 8 is opened by the control device 2, thereby constituting the expansion tank 6 and the high pressure system. And the piping 7b to be communicated via the connecting piping 6a, and the refrigerant gas is recovered from the high pressure system into the expansion tank 6, thereby limiting the amount of refrigerant gas sucked and discharged in the expansion turbine E, and the low pressure system. Can be adjusted to a pressure satisfying the pressure resistance performance (for example, the pressure of the refrigerant gas in the low-pressure system <10 kPa).

  Next, a system flow relating to pressure adjustment by opening and closing the first electromagnetic valve 8 and the second electromagnetic valve 9 in the control device 2 will be described with reference to FIG. As shown in FIG. 3, when the control device 2 first acquires the rotational speed data (variation value of the rotational speed) of the motor 10 from the rotary encoder 11 in step SA1, the control device 2 proceeds to step SA2 and stores the acquired rotational speed data. It is determined whether or not the value (increased value) is greater than the upper limit reference value. If the value (increased value) is greater than the upper limit reference value, the process proceeds to step SA3, where a control signal is transmitted to open the first electromagnetic valve 8. If the rotational speed data of the motor 10 is acquired from the rotary encoder 11 again, the process proceeds to step SA4, and the process proceeds to step SA5, where the value (increase value) of the acquired rotational speed data is equal to or less than a predetermined set value near the upper limit reference value. If it is determined that the value is equal to or less than the set value, the process proceeds to step SA6, where a control signal is transmitted to close the first electromagnetic valve 8. Note that the upper limit reference value itself may be set as the predetermined set value.

  Furthermore, in step SA5, when the value (increase value) of the acquired rotation speed data is larger than the set value, it is determined that the fluctuation value of the rotation speed of the motor 10 has not returned within the set range, and the process proceeds to step SA4. Return.

  If it is determined in step SA2 that the acquired value (decrease value) of the rotational speed data is smaller than the upper limit reference value, the process proceeds to step SA2 ′, where the acquired value (decrease value) of the rotational speed data is the lower limit reference value. If it is smaller than the lower limit reference value, the process proceeds to step SA3 ′, where a control signal is transmitted to open the second electromagnetic valve 9. Then, the process proceeds to step SA4 ′, and when the rotational speed data of the motor 10 is acquired again from the rotary encoder 11, the process proceeds to step SA5 ′, where the value (decrease value) of the acquired rotational speed data is a predetermined set value near the lower limit reference value. It is determined whether or not the value is equal to or greater than the set value. If the value is equal to or greater than the set value, it is determined that the fluctuation value of the rotation speed of the motor 10 is within the set range, and the process proceeds to Step SA6 ′. 9 is closed. Note that the lower limit reference value itself may be set as the predetermined set value.

  In step SA5 ', if the value (decrease value) of the acquired rotation speed data is smaller than the set value, it is determined that the rotation speed of the motor 10 has not returned within the set range, and the flow returns to step SA4'.

  In step SA2 ′, it is determined whether or not the value (decrease value) of the acquired rotation speed data is smaller than the lower limit reference value. If the value is larger than the lower limit reference value, the fluctuation value of the rotation speed of the motor 10 is , It is determined that it is within the set range, and the process returns to step SA1.

  As described above, the control device 2 acquires the rotation speed data of the motor 10 from the rotary encoder 11, and the first electromagnetic valve 8 and the second electromagnetic valve 9 until the fluctuation value of the rotation speed of the motor 10 falls within the set range. Therefore, the pressure of the refrigerant gas flowing through the low-pressure system can be adjusted within a predetermined setting range (0 kPa <pressure of the refrigerant gas of the low-pressure system <10 kPa).

  In the control device 2, the pressure of the refrigerant gas in the low-pressure system detected by the pressure sensor provided at an appropriate position in the low-pressure system is within a predetermined setting range (0 kPa <pressure of the refrigerant gas in the low-pressure system <10 kPa). In this case, the first electromagnetic valve 8 and the second electromagnetic valve 9 may be closed by transmitting a control signal.

  Furthermore, the control device 2 is configured so that the pressure of the refrigerant gas in the low-pressure system detected by a pressure sensor provided at an appropriate position in the low-pressure system exceeds the design upper limit value of the low-pressure system, or the design lower limit value. It may be configured to open the first electromagnetic valve 8 or the second electromagnetic valve 9 by transmitting a control signal when the value is lower than.

  As described above, according to the cooling device 1 according to the present invention, when the pressure of the refrigerant gas in the low-pressure system exceeds the design upper limit value, the first electromagnetic valve 8 (high-pressure on-off valve) is opened. By collecting the refrigerant gas of the high-pressure system in the expansion tank 6 (sealed container), it is possible to limit the amount of refrigerant gas in the low-pressure system and suppress an increase in pressure in the low-pressure system. Is lower than the design lower limit value, the second solenoid valve 9 (low-pressure on-off valve) is opened and the refrigerant gas in the expansion tank 6 is supplied to the low-pressure system, thereby connecting pipe 6b (low-pressure connection). The pressure of the refrigerant gas flowing into the brine cooler 5 (heat exchanger) installed on the downstream side of the path) can be quickly increased, so that the brine cooler 5 disposed in the low-pressure system and the exhaust heat The refrigerant gas flowing into the recovered heat exchanger 4 To force changes, it is possible to protect responsive high and reliably.

  The first solenoid valve 8 (high pressure on-off valve) and the second solenoid valve 9 (low pressure on-off valve) are controlled to open and close based on the rotational speed of the drive shaft 10a of the compressor C (compressor), so that the refrigerant gas Since the first electromagnetic valve 8 and the second electromagnetic valve 9 can be controlled to open and close based on fluctuations in the rotational speed of the drive shaft 10a of the compressor C, which is the starting point of the pressure fluctuation, the responsiveness to the pressure change of the refrigerant gas is extremely high. The brine cooler 5 and the exhaust heat recovery heat exchanger 4 can be protected.

  Further, the connection pipe 6a (high-pressure connection path) is connected to the high-pressure system on the upstream side of the exhaust heat recovery heat exchanger 4 using the return refrigerant gas from the brine cooler 5 (heat exchanger). Since the relatively high-temperature refrigerant gas before passing through the exhaust heat recovery heat exchanger 4 can be recovered in the expansion tank 6 through the connection pipe 6a, the refrigerant gas in the expansion tank 6 is connected to the connection pipe 6b. By supplying to the low-pressure system via the (low-pressure connection path) and the other branch bypass pipe 16c, it can be used as a part of the temperature-rising bypass line used for defrosting of the low-pressure system.

  In addition, the bypass pipe 16a (bypass flow path) connecting the high pressure system and the low pressure system is connected to the high pressure system upstream of the connection pipe 6a (high pressure connection path), so that the bypass pipe 16a By opening the balance valve 14 provided, the refrigerant gas can be detoured upstream of the connection pipe 6a, so that the influence of the refrigerant gas flow by the expansion tank 6 can be suppressed and surging can be prevented quickly. it can.

  Further, the expansion tank 6 is connected to the high-pressure system downstream of the high-temperature side pipe 3a of the water-cooled heat exchanger 3 (cooler) by the connection pipe 6a (high-pressure connection path), so that the water-cooled heat exchanger 3 Since the refrigerant gas A3 (about 43 ° C.) cooled in the step can be recovered, the refrigerant gas can be easily managed by the expansion tank 6.

  Next, a cooling device according to a first modification will be described with reference to FIG. Since the cooling apparatus of this modification is the same as that of the above-described embodiment except for the equipment connected to the expansion tank 6 described later, description thereof will be omitted. The expansion tank 6 of this modification is connected to the connection pipe 6a, the first electromagnetic valve 8, the connection pipe 6b, and the second electromagnetic valve 9 as in the above-described embodiment, and also dried nitrogen gas via the supply pipe 17a. Is connected to a cylinder 17. The supply pipe 17a is configured to be able to open and close the flow path by an electromagnetic valve 18 (open / close valve). Furthermore, the expansion tank 6 is connected to a pressure sensor 19 that detects the pressure inside the expansion tank 6. The solenoid valve 18 and the pressure sensor 19 are connected to the control device 2.

  When the pressure in the expansion tank 6 detected by the pressure sensor 19 falls below a predetermined value, the control device 2 sends dry nitrogen gas in the cylinder 17 by sending a control signal for opening the electromagnetic valve 18. The inside is replenished and control which raises the pressure in this expansion tank 6 is performed.

  As described above, when the refrigerant gas refill cylinder 17 is connected to the expansion tank 6 via the electromagnetic valve 18 (open / close valve), when the pressure of the refrigerant gas in the expansion tank 6 decreases, Since the solenoid valve 18 can be opened and the refrigerant gas can be replenished from the cylinder 17, the pressure of the refrigerant gas in the expansion tank 6 can be maintained higher than that of the low pressure system.

  Next, a cooling device according to a second modification will be described with reference to FIG. Since the cooling apparatus of this modification is the same as that of the above-described embodiment except for the equipment connected to the expansion tank 6 described later, description thereof will be omitted. The expansion tank 6 of this modification is connected to the connection pipe 6a, the first electromagnetic valve 8, the connection pipe 6b, and the second electromagnetic valve 9 in the same manner as in the above embodiment, and in the connection pipe 6a (high pressure connection path). A first orifice flange 21 for adjusting the flow rate of the refrigerant is interposed between the flange of the first electromagnetic valve 8 and the flange of the expansion tank 6, and these are fastened by a fastening member 25. Further, a second orifice flange 22 for adjusting the flow rate of the refrigerant is interposed between the flange of the second electromagnetic valve 9 and the flange of the expansion tank 6 in the connection pipe 6b (low pressure connection path). It is concluded with. That is, the first orifice flange 21 and the second orifice flange 22 constitute a flow rate adjusting unit of the present invention.

  The first orifice flange 21 is a substantially circular flange plate made of a steel material such as SUS, a plurality of bolt holes for fastening members that are fastened to the flanges of the first electromagnetic valve 8 and the expansion tank 6, and the center of the flange plate. And a small-diameter orifice hole 21a formed through the portion. The hole diameter of the orifice hole 21a is sufficiently smaller than the inner diameter of the connection pipe 6a, and is preferably set appropriately in a range of about 5% to 15% with respect to the outer diameter of the flange plate connected to the pipe. For example, in the case of a flange plate having an outer diameter of φ100, the hole diameter of the orifice hole 21a may be selected from φ5, φ7.5, φ10, or φ12.5.

  The second orifice flange 22 has the same configuration as the first orifice flange 21 described above, and is formed through the center portion of the flange plate and has an orifice hole 22a having a diameter sufficiently smaller than the inner diameter of the connection pipe 6b. However, the orifice hole 22a of the second orifice flange 22 may have a hole diameter different from that of the orifice hole 21a of the first orifice flange 21, for example, the second orifice flange 22 for adjusting the flow rate of the refrigerant in the low-pressure system. The orifice hole 22a may be formed with a larger diameter than the orifice hole 21a of the first orifice flange 21 that adjusts the flow rate of the refrigerant in the high-pressure system.

  In this way, the first orifice flange 21 for adjusting the flow rate of the refrigerant is interposed between the first electromagnetic valve 8 and the expansion tank 6, and as described in the above embodiment, the control device 2. However, when the rotational speed data of the motor 10 is acquired from the rotary encoder 11 and the first electromagnetic valve 8 is opened until the fluctuation value of the rotational speed of the motor 10 falls within the set range, the refrigerant gas of the high-pressure system 1 eliminates the possibility of a large amount flowing into the expansion tank 6 through the solenoid valve 8 in a short time, and the flow rate of the refrigerant gas is adjusted at the orifice hole 21a of the first orifice flange 21 so that the amount of the refrigerant gas is small over a certain period of time. It flows into the expansion tank 6 one by one. Therefore, rapid pressure fluctuations are suppressed, and the accuracy of pressure control based on the number of rotations of the motor 10 can be increased.

  Further, as described in the above embodiment, the control device is provided with the second orifice flange 22 for adjusting the flow rate of the refrigerant interposed between the second electromagnetic valve 9 and the expansion tank 6 as described above. 2 acquires the rotation speed data of the motor 10 from the rotary encoder 11, and when the second electromagnetic valve 9 is opened until the fluctuation value of the rotation speed of the motor 10 falls within the set range, the refrigerant gas of the low-pressure system The possibility of flowing out of the expansion tank 6 through the second electromagnetic valve 9 in a short time and in a large amount is eliminated, and the flow rate of the refrigerant gas is adjusted in the orifice hole 22a of the second orifice flange 22 over a certain period of time. A small amount is discharged from the expansion tank 6. Therefore, rapid pressure fluctuations are suppressed, and the accuracy of pressure control based on the number of rotations of the motor 10 can be increased.

  In this modification, a first orifice flange 21 as a flow rate adjusting unit is provided in the connection pipe 6a (high pressure connection path), and a second orifice flange as a flow rate adjustment unit in the connection pipe 6b (low pressure connection path). However, it is not necessarily limited to these, and the flow rate adjusting unit may be provided only in the connection pipe 6a (high pressure connection path), or only in the connection pipe 6b (low pressure connection path). A flow rate adjusting unit may be provided. Further, the flow rate adjusting unit is not necessarily limited to that provided between the first and second electromagnetic valves 8 and 9 and the expansion tank 6, and may be appropriately selected as long as it is a piping unit that constitutes the high pressure connection path and the low pressure connection path. It can be provided at a location. Further, the configuration of the flow rate adjustment unit according to the second modification and the configuration according to the cylinder 17 and the electromagnetic valve 18 according to the first modification may be provided side by side.

  Next, a cooling device according to a third modification will be described with reference to FIG. In the cooling device of this modification, the expansion tank 26 has a smaller capacity than the expansion valve 6 of the above-described embodiment, and other components are the same as those described above except for the device connected to the expansion tank 26 described later. Since it is the same as that of an example, the description is abbreviate | omitted. The expansion tank 26 of this modification is connected to the connection pipe 6a, the first electromagnetic valve 8, the connection pipe 6b, and the second electromagnetic valve 9 in the same manner as in the above embodiment, and in the connection pipe 6a (high pressure connection path). Between the flange of the 1st solenoid valve 8 and the flange of the expansion tank 26, the 2nd compressor 27 which compresses the refrigerant | coolant of a high voltage | pressure system, raises a pressure further, and sends it out to the expansion tank 26 is interposed, These are fastening members. It is concluded with. That is, this 2nd compressor 27 comprises the refrigerant | coolant compression part of this invention.

  The second compressor 27 of the present modification is a so-called rotary blower type compressor, and a pair of rotors 29 and 29 disposed in the casing 28 rotate in opposite directions while being in contact with each other. The refrigerant of the high-pressure system sucked from the intake port 28a is forcibly sent toward the exhaust port 28b through the region formed in the inner wall of the casing 28 and the mutual rotors 29, 29, and is connected to the exhaust port 28b. The refrigerant in the expansion tank 26 is structured to gradually become a higher pressure state.

  By doing so, the pressure of the refrigerant existing in the high-pressure system can be forcibly increased by the second compressor 27 and accumulated in the expansion tank 26 as a further high-pressure state. Can be made smaller than the expansion tank 6 of the embodiment described above, that is, the expansion tank 26 of the present modification can be reduced in size.

  The refrigerant compressor of the present invention is not necessarily limited to the rotary blower type compressor, and various types of compressors belonging to, for example, a displacement type rotary type or a reciprocating type can be applied.

  In addition, the configuration of the refrigerant compression unit according to the third modification, the configuration according to the cylinder 17 and the electromagnetic valve 18 according to the first modification, and / or the configuration of the flow rate adjusting unit according to the second modification are also provided. It doesn't matter.

  Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments, and modifications and additions within the scope of the present invention are included in the present invention. It is.

  For example, in the above-described embodiment, the expansion tank 6 has been described as being connected to the pipe 7b constituting the high-pressure system via the connection pipe 6a. However, the expansion tank 6 constitutes the high-pressure system by the connection pipe 6a. What is necessary is just to be connected to either piping 7a, 7b, 7c.

  In the above embodiment, the expansion tank 6 is described as being connected to the pipe 7d constituting the low-pressure system via the connection pipe 6b and the other branch bypass pipe 16c. 6b may be directly connected to the pipe 7d constituting the low-pressure system.

  In the above embodiment, the control device 2 has been described as a mode for controlling both the driving of the motor 10 and the opening and closing of the first electromagnetic valve 8 and the second electromagnetic valve 9, but the driving of the motor 10 and the first electromagnetic valve are described. The control devices that control the opening and closing of the 8 and the second electromagnetic valve 9 may be configured separately.

  Further, the expansion tank 6 is connected only to the low-pressure system by the connection pipe 6b (low-pressure connection path), and may not be connected to the high-pressure system. In this case, the expansion tank 6 is provided with a cylinder for refilling the refrigerant gas. It is preferable to be connected.

1 Cooling device 2 Control device 3 Water-cooled heat exchanger (cooler)
4 Waste heat recovery heat exchanger 5 Brine cooler (heat exchanger)
6 Expansion tank (sealed container)
6a Connection piping (high pressure connection path)
6b Connection piping (low pressure connection path)
7a-7c piping (high-pressure piping)
7d-7f piping (low pressure system piping)
8 First solenoid valve (high pressure on-off valve)
9 Second solenoid valve (low pressure on-off valve)
DESCRIPTION OF SYMBOLS 10 Motor 10a, 10b Drive shaft 11 Rotary encoder 14 Balance valve 16a Bypass piping (bypass flow path)
17 cylinder 18 solenoid valve (open / close valve)
21 First orifice flange (flow rate adjustment part)
21a Orifice hole 22 Second orifice flange (flow rate adjusting part)
22a Orifice hole 26 Expansion tank (sealed container)
27 Second compressor (refrigerant compressor)
C Compressor
E Expansion turbine (expander)

Claims (11)

A compressor that compresses refrigerant gas sucked from the low-pressure system, a cooler that cools the refrigerant gas compressed by the compressor and discharged to the high-pressure system, and an expander that expands the refrigerant gas cooled by the cooler And a heat exchanger that cools an object to be cooled with a refrigerant gas that is expanded by the expander and discharged to the low-pressure system,
A sealed container in which refrigerant gas is sealed, a low-pressure connection path that connects the sealed container and the low-pressure system, and a low-pressure on-off valve that opens and closes the low-pressure connection path,
The cooling apparatus, wherein the low-pressure connection path is connected to the low-pressure system on the upstream side of the heat exchanger.   The low-pressure connection path is connected to the low-pressure system on the upstream side of the heat exchanger and an exhaust heat recovery heat exchanger that uses return refrigerant gas from the heat exchanger. The cooling device according to 1.   The cooling device according to claim 1 or 2, wherein the low-pressure on-off valve is controlled to open and close based on the number of rotations of the drive shaft of the compressor.   The cooling device according to any one of claims 1 to 3, wherein a flow rate adjusting unit for adjusting a flow rate of the refrigerant gas flowing through the low pressure connection channel is provided in the low pressure connection channel.   The cooling device according to any one of claims 1 to 4, further comprising a high-pressure connection path that connects the sealed container and the high-pressure system, and a high-pressure on-off valve that opens and closes the high-pressure connection path.   The cooling apparatus according to claim 5, wherein the high-pressure connection path is connected to the high-pressure system on the upstream side of the exhaust heat recovery heat exchanger using the return refrigerant gas from the heat exchanger.   The cooling apparatus according to claim 5 or 6, wherein the high-pressure on-off valve is controlled to open and close based on the rotational speed of the drive shaft of the compressor. A bypass channel connecting between the high-pressure system and the low-pressure system, and a balance valve capable of opening and closing the bypass channel,
The cooling device according to any one of claims 5 to 7, wherein the bypass flow path is connected to the high-pressure system upstream of the high-pressure connection path.   The cooling device according to any one of claims 5 to 8, wherein a flow rate adjusting unit for adjusting a flow rate of the refrigerant gas flowing through the high pressure connection channel is provided in the high pressure connection channel.   The cooling according to any one of claims 5 to 9, wherein the high-pressure connection path is provided with a refrigerant compression section that compresses the refrigerant gas flowing through the high-pressure connection path and sends the compressed gas to the sealed container. apparatus.   The cooling device according to any one of claims 1 to 10, wherein a cylinder for replenishing refrigerant gas is connected to the sealed container via an on-off valve.

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