WO2017141722A1 - 冷凍装置 - Google Patents
冷凍装置 Download PDFInfo
- Publication number
- WO2017141722A1 WO2017141722A1 PCT/JP2017/003835 JP2017003835W WO2017141722A1 WO 2017141722 A1 WO2017141722 A1 WO 2017141722A1 JP 2017003835 W JP2017003835 W JP 2017003835W WO 2017141722 A1 WO2017141722 A1 WO 2017141722A1
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- Prior art keywords
- compressor
- temperature
- rotation speed
- temperature sensor
- rotational speed
- Prior art date
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Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B6/00—Compression machines, plants or systems, with several condenser circuits
- F25B6/04—Compression machines, plants or systems, with several condenser circuits arranged in series
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B1/00—Compression machines, plants or systems with non-reversible cycle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B15/00—Sorption machines, plants or systems, operating continuously, e.g. absorption type
- F25B15/006—Sorption machines, plants or systems, operating continuously, e.g. absorption type with cascade operation
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
- F25B49/025—Motor control arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B7/00—Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
- F25B9/004—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being air
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2341/00—Details of ejectors not being used as compression device; Details of flow restrictors or expansion valves
- F25B2341/06—Details of flow restrictors or expansion valves
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- F25B2341/0683—Expansion valves combined with a sensor the sensor is disposed in the suction line and influenced by the temperature or the pressure of the suction gas
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- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
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- F25B2600/0253—Compressor control by controlling speed with variable speed
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- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
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- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
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- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
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- F25B41/34—Expansion valves with the valve member being actuated by electric means, e.g. by piezoelectric actuators
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
- Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
Definitions
- the present invention relates to a refrigeration apparatus having a cascade cycle.
- the controller starts the compressor (high temperature side compressor) constituting the primary side refrigerant circuit based on the internal temperature of the freezer output from the temperature sensor during normal operation, and then for a predetermined time. After the elapse of time, the compressor (low temperature side compressor) of the secondary side refrigerant circuit is started. When reaching the upper limit value of the target value of the internal temperature, the controller first activates the primary side refrigerant circuit including the high temperature side compressor based on the output of the temperature sensor that detects the internal temperature.
- the controller opens the solenoid valve provided between the compressor and the evaporator in the secondary refrigerant circuit, starts the low temperature compressor, and then between the cascade condenser and the expander in the secondary refrigerant circuit.
- the control which opens the solenoid valve provided in is performed.
- This type of refrigeration apparatus is required to quickly return to the target value when the internal temperature (that is, the temperature of the storage space for the object to be cooled) rises.
- an object of the present invention is to provide a refrigeration apparatus that can quickly return to a target value when the temperature of the storage space rises.
- a refrigeration apparatus includes: A first cooling section arranged such that a first compressor, a first condenser, a first expander and a first evaporator are in fluid communication with a first fluid circuit in which a first refrigerant circulates;
- the second compressor, the second condenser constituting the cascade condenser together with the first evaporator, the second expander, and the second evaporator are arranged in fluid communication with the second fluid circuit in which the second refrigerant circulates.
- a second cooling section A storage unit having a storage space for a cooling object to be cooled by the second evaporator; An internal temperature sensor for detecting the temperature of the storage space; A control unit that determines a second rotational speed of the second compressor based on a target temperature of the storage space and a detection result of the internal temperature sensor, and has a predetermined correspondence relationship with the second rotational speed.
- a first power supply unit and a second power supply unit configured to supply power to the first compressor and the second compressor based on the first rotation speed and the second rotation speed determined by the control unit; Yes.
- FIG. 1 It is a figure which shows the relationship between the cooling part of the freezing apparatus which concerns on a comparative example, and the block structure of a control system.
- FIG. 1 It is a schematic diagram which shows the heat transfer in the cooling part of FIG. 1 is a front view of a refrigeration apparatus according to a first embodiment of the present invention. It is a right view of this freezing apparatus. It is a figure which shows an example of the cooling unit with which this freezing apparatus is equipped. It is a figure which shows an example of the control system with which this freezing apparatus is equipped. It is a flowchart which shows a part of internal temperature control (1st example) of this freezing apparatus. It is a flowchart which shows the remaining part of the internal temperature control (1st example) of this freezing apparatus.
- the refrigeration apparatus 10 according to the comparative example includes a cooling unit 15.
- the cooling unit 15 includes a first cooling unit 16H and a second cooling unit 17L.
- the first compressor 161H compresses the first refrigerant and discharges a high-temperature and high-pressure gas refrigerant.
- the first pre-stage condenser 162H and the first post-stage condenser 163H cool and discharge the refrigerant discharged from the first compressor 161H.
- a fan 167H is disposed in the vicinity of both condensers 162H and 163H. Cooling of the first refrigerant passing through both the condensers 162H and 163H is promoted by the air flow by the fan 167H.
- the first expander 164H decompresses and discharges the refrigerant discharged from the first second-stage condenser 163H.
- the first evaporator 165H evaporates and discharges the refrigerant discharged from the first expander 164H.
- the second compressor 171L compresses the second refrigerant having a boiling point lower than that of the first refrigerant, and discharges the compressed second refrigerant to the high-temperature and high-pressure gas refrigerant.
- Both condensers 172L and 173L condense and discharge the refrigerant discharged from the second compressor 171L.
- the second second-stage condenser 173L constitutes the cascade condenser 18 together with the first evaporator 165H, and cools the refrigerant passing through the second second-stage condenser 173L by the endothermic action of the first refrigerant in the first evaporator 165H.
- the medium temperature and high pressure refrigerant is discharged.
- the second expander 174L decompresses and discharges the refrigerant discharged from the second second-stage condenser 173L.
- the second evaporator 175L evaporates and discharges the refrigerant discharged from the second expander 174L.
- the second evaporator 175L is affixed on the outer peripheral surface of the interior body that defines the storage space S.
- the heat of the storage space S moves to the second evaporator 175L due to the endothermic action when the second refrigerant evaporates in the second evaporator 175L, whereby the object to be cooled in the storage space S is cooled.
- the cooling unit 15 includes at least a first temperature sensor Se11 that detects the temperature in the storage space S and a second temperature sensor Se12 that detects the temperature in the cascade capacitor 18.
- the first control unit 192H constitutes a first feedback system together with the second temperature sensor Se12, and is based on a deviation between the temperature detected by the second temperature sensor Se12 and the target temperature of the cascade capacitor 18.
- the rotational speed of the first compressor 161H is controlled.
- the second control unit 202L constitutes a second feedback system together with the first temperature sensor Se11, and based on the deviation between the temperature detected by the first temperature sensor Se11 and the target temperature in the storage space S, The rotational speed of the machine 171L is controlled.
- the amount of heat Q1 enters as a disturbance to the second feedback system.
- the second control unit 202L increases the rotational speed of the second compressor 171L in order to return the temperature in the storage space S to the target temperature, whereby the second refrigerant traveling from the second compressor 171L toward the cascade condenser 18 Increase the flow rate.
- the heat quantity Q2 is generated in the cascade condenser 18 after a predetermined delay time has elapsed since the rotation speed of the second compressor 171L has increased.
- the amount of heat Q2 includes part of work W1 of the second compressor 171L in addition to the amount of heat Q1 due to disturbance.
- the first control unit 192H increases the rotation speed of the first compressor 161H.
- the flow rate of the first refrigerant flowing between the first compressor 161H and the first pre-stage condenser 162H increases, and the amount of heat Q3 is released to the outside of the refrigeration apparatus 10 from both the condensers 162H and 163H.
- the temperature of the cascade condenser 18 does not immediately follow the increase or decrease of the rotational speed of the second compressor 171L. Therefore, even if the deviation between the detected temperature of the first temperature sensor Se11 and the target temperature becomes substantially zero and the second control unit 202L restores the rotational speed of the second compressor 171L, the inside of the storage space S The temperature continues to decrease for a while. Furthermore, since the high-temperature and high-pressure second refrigerant flows through both the condensers 172L and 173L for a while, the first compressor 161H also rotates under the control of the first controller 192H in order to lower the temperature of the cascade condenser 18. Be made. As described above, in the comparative example, heat transfer delay or interference occurs between the first feedback system and the second feedback system. Therefore, once the temperature of the storage space S rises, the temperature is restored to the target temperature. It takes time.
- an object of the present embodiment is to provide a refrigeration apparatus 1 that can quickly recover the temperature in the storage space S and suppress energy waste.
- the refrigeration apparatus 1 according to each embodiment will be described in detail with reference to FIG. ⁇ 2-1.
- the X axis indicates the lateral direction of the refrigeration apparatus 1 (more specifically, the direction from the right side to the left side when the user faces the refrigeration apparatus 1).
- the Y-axis indicates the front-rear direction of the refrigeration apparatus 1 (more specifically, the direction from the back side (back side) toward the front side (front side) when facing the above-mentioned).
- the Z-axis indicates the vertical direction of the refrigeration apparatus 1 (more specifically, the direction from the lower side to the upper side of the refrigeration apparatus 1).
- the refrigeration apparatus 1 generally includes a heat insulating housing 2, a heat insulating door 3, and a machine room 4.
- the heat insulation housing 2 generally includes an exterior body 21, an interior body 22, and a foam heat insulating material 23.
- the exterior body 21 and the interior body 22 are made of metal, for example, and open on the front side.
- the exterior body 21 defines the outer shape of the heat insulating housing 2.
- the interior body 22 is provided inside the exterior body 21 and defines a space S (hereinafter referred to as a storage space) S for storing the object to be cooled.
- the storage space S is also opened on the front side.
- the foam heat insulating material 23 is made of a synthetic resin foam or a vacuum heat insulating material, and is provided between the exterior body 21 and the interior body 22. 3 and 4, a configuration that cannot be visually recognized from the outside, such as the foam heat insulating material 23, is indicated by a dotted line or a one-dot chain line.
- a resin inner door 24 is preferably attached to the front side of the interior body 22 so as to be freely opened and closed.
- the inner door 24 closes the opening of the storage space S when closed.
- the inner door 24 is opened, the user can access the storage space S.
- the heat insulation effect in the storage space S is enhanced by the inner door 24.
- the heat insulating door 3 includes, for example, a metal interior body 31 and an exterior body 32, and a foam heat insulating material 33 filled in a space between the interior body 31 and the exterior body 32.
- the heat insulation door 3 opens and closes by rotating around the rotation center axis of the two hinges 34 by a user operation.
- the heat insulation door 3 closes the opening of the heat insulation housing 2 when closed.
- the heat insulating door 3 is opened, the user can open and close the inner door 24 described above.
- the heat insulating door 3 is provided with a handle 35 that is gripped by the user when opening and closing.
- the handle 35 is preferably provided with a lock mechanism (not shown). The lock mechanism locks the heat insulation door 3 in a closed state or releases the lock state so that the heat insulation door 3 can be opened.
- a control panel 36 is provided on the front surface of the exterior body 32 of the heat insulating door 3.
- the control panel 36 has a control circuit board 9 (see FIG. 6) inside, and has a keyboard 36a and a display 36b that can be operated and visually recognized by the user.
- the keyboard 36a is a device for the user to set, for example, the target temperature of the storage space S (that is, the target value SV of the internal temperature), and the display 36b is the current set temperature (the target value SV of the internal temperature). ) And the like.
- the machine room 4 is provided in the lower part of the heat insulation housing
- the machine room 4 stores a cooling unit 5 excluding a second evaporator 75L (see FIG. 5) described later.
- the cooling unit 5 includes a first cooling unit 6H and a second cooling unit 7L.
- the first cooling unit 6H is a high temperature side cooling unit in a so-called cascade cycle.
- the first fluid circuit 66H includes a first compressor 61H, a first pre-stage condenser 62H, a first post-stage condenser 63H, a first expander 64H, and a first evaporator 65H. Are connected in an annular shape so as to be in fluid communication in this order, and the first refrigerant flows.
- the first compressor 61H compresses the sucked first refrigerant and discharges it to a high-temperature and high-pressure gas refrigerant.
- the first front-stage condenser 62H and the first rear-stage condenser 63H are condensers formed by meandering copper or aluminum tubing, and cool and condense the first refrigerant discharged from the first compressor 61H. And discharge medium-temperature and high-pressure refrigerant.
- the first pre-stage condenser 62H can be used as a heat source for preventing dew condensation in each part of the refrigeration apparatus 1 in addition to the cooling of the first refrigerant.
- a fan 67H is disposed in the vicinity of the first front-stage condenser 62H and the first rear-stage condenser 63H.
- the fan 67H rotates with the driving force generated by the motor 68H, and applies air to the first front-stage condenser 62H and the first rear-stage condenser 63H.
- the first cooling unit 6H is exemplified by two condensers 62H and 63H as condensers.
- the number of condensers is not limited to two, and the number of condensers may be one or three or more as long as the first refrigerant can be cooled.
- the first expander 64H is composed of an expansion valve, a capillary tube, or the like, and expands and depressurizes the medium-temperature and high-pressure first refrigerant discharged from the first second-stage condenser 63H, and discharges the low-temperature and low-pressure first refrigerant.
- the first evaporator 65H evaporates (vaporizes) and discharges the low-temperature and low-pressure first refrigerant discharged from the first expander 64H.
- the refrigerant discharged from the first evaporator 65H is sucked into the first compressor 61H through the first fluid circuit 66H. As described above, the first refrigerant circulates through the first fluid circuit 66H.
- the first evaporator 65H constitutes a second latter-stage condenser 73L, which will be described later, and a cascade condenser 8.
- the cascade condenser 8 is configured integrally with the first evaporator 65H and the second second-stage condenser 73L so that heat exchange is possible, and the heat absorption when the first refrigerant evaporates in the first evaporator 65H.
- the second refrigerant in the second second-stage condenser 73L is cooled by the action.
- the cascade capacitor 8 described above includes, for example, any one of a liquid receiver, a double pipe, and a plate heat exchanger.
- the second cooling unit 7L is a low temperature side cooling unit in a so-called cascade cycle.
- the second fluid circuit 76L includes a second compressor 71L, a second pre-stage condenser 72L, a second post-stage condenser 73L, a second expander 74L, and a second evaporator 75L.
- a second compressor 71L a second pre-stage condenser 72L
- a second post-stage condenser 73L a second expander 74L
- a second evaporator 75L are connected in a ring shape so as to communicate with each other in this order, and a second refrigerant having a boiling point lower than that of the first refrigerant flows.
- the second compressor 71L compresses the sucked second refrigerant and discharges it to a high-temperature and high-pressure gas refrigerant.
- the second pre-stage condenser 72L has the same configuration and function as the first pre-stage condenser, condenses the refrigerant discharged from the second compressor 71L, and discharges the medium-temperature and high-pressure refrigerant. Note that the second pre-stage condenser 72 ⁇ / b> L does not need to be provided because it cools the second refrigerant upstream from the cascade condenser 8. Moreover, there may be two or more second pre-stage condensers 72L.
- the second second-stage condenser 73L constitutes the cascade condenser 8 together with the first evaporator 65H, and the refrigerant discharged from the second first-stage condenser 72L is absorbed by the endothermic action of the first refrigerant in the first evaporator 65H. Furthermore, it cools and discharges a medium temperature and high pressure refrigerant.
- the second expander 74L has the same configuration and function as the first expander 64H, and expands and depressurizes the medium-temperature and high-pressure second refrigerant discharged from the second second-stage condenser 73L, and the low-temperature and low-pressure second refrigerant. Discharge the refrigerant.
- the second evaporator 75L evaporates (vaporizes) and discharges the low-temperature and low-pressure second refrigerant discharged from the second expander 74L.
- the refrigerant discharged from the second evaporator is sucked into the second compressor 71L through the second fluid circuit 76L.
- the second refrigerant circulates through the second fluid circuit 76L.
- the second evaporator 75L is affixed to the outer peripheral surface of the interior body 22 between the exterior body 21 and the interior body 22, as indicated by a dotted line in FIG. Due to the endothermic action when the second refrigerant evaporates in the second evaporator 75L, the heat from the storage space S moves to the second evaporator 75L, whereby the object to be cooled in the storage space S is cooled. .
- Control system of the cooling unit 5 (hardware configuration) >> Pressure sensors or temperature sensors are provided at various locations of the cooling unit 5 described above. What is important in the present embodiment is that the first temperature sensor Se1, the second temperature sensor Se2, the third temperature sensor Se3, the fourth temperature sensor Se4, the fifth temperature sensor Se5, and the sixth temperature shown in FIGS. This is the sensor Se6.
- the first temperature sensor Se1 is a typical example of the internal temperature sensor, and is provided in the storage space S.
- the first temperature sensor Se1 detects the temperature of the storage space S as the internal temperature and represents a detection value PV of the internal temperature ( Hereinafter, the internal temperature detection value PV) is simply output to the control circuit board 9.
- the second temperature sensor Se2 is a typical example of the ambient temperature sensor, and is provided around the refrigeration apparatus 1 (such as the vent of the fan 67H (not shown)), detects the ambient temperature, and detects the detected value.
- a signal to be expressed (hereinafter simply referred to as an ambient temperature detection value ST) is output to the control circuit board 9.
- the second temperature sensor Se2 is also attached to the surface of the exterior body 21 (for example, inside or the surface of the control panel 36) so as not to be affected by the first second-stage condenser 63H, and detects the ambient temperature. It doesn't matter.
- the third temperature sensor Se3 is an example of a second fluid circuit temperature sensor.
- the third temperature sensor Se3 is located at an intermediate position between the second second-stage condenser 73L constituting the cascade capacitor 8 and the second expander 74L. It is attached. At such an attachment position, the third temperature sensor Se3 detects the temperature of the second refrigerant, and a signal indicating the detected value of the second refrigerant temperature (hereinafter simply referred to as the detected value of the second refrigerant temperature) is a control circuit. Output to the substrate 9.
- the third temperature sensor Se3 is attached so as to be thermally coupled to an intermediate position between the second second-stage condenser 73L and the second expander 74L in the second fluid circuit 76L.
- the periphery of the pipe constituting the intermediate position between the second second-stage condenser 73L and the second expander 74L is covered with a heat insulating material such as glass wool. Therefore, it is easy to attach the third temperature sensor Se3, and it is difficult to be influenced by the external temperature, so that there is an advantage that the temperature of the second refrigerant can be detected with high accuracy.
- the fourth temperature sensor Se4 is an example of a cascade temperature sensor.
- the fourth temperature sensor Se4 is attached to the refrigerant inlet side or the refrigerant outlet side of the first evaporator 65H and detects the temperature of the first refrigerant. Then, a signal indicating the detected value of the first refrigerant temperature (hereinafter simply referred to as the detected value of the first refrigerant temperature) is output to the control circuit board 9.
- coolant inlet side is shown.
- the third temperature sensor Se3 and the fourth temperature sensor Se4 can be attached to various places other than the above. Examples of other attachment positions are as follows. In the first fluid circuit 66H, the refrigerant inlet side, the refrigerant outlet side of the first evaporator 65H or an intermediate position thereof. In the second fluid circuit 76L, the refrigerant inlet side, the refrigerant outlet side of the second second-stage condenser 73L, or those.
- the first fluid circuit 66H and the second fluid circuit 76L are covered with glass wool or the like for heat insulation, so that the third temperature sensor Se3 and the second fluid circuit 76L
- the four temperature sensor Se4 can accurately detect the temperature of the refrigerant.
- the glass wool is used for heat insulation, the third temperature sensor Se3 and the fourth temperature sensor Se4 can be easily attached as compared with the case of hardening with foamed urethane.
- the fifth temperature sensor Se5 and the sixth temperature sensor Se6 are attached to the shell surfaces of the first compressor 61H and the second compressor 71L, and correlate with the temperatures of the first compressor 61H and the second compressor 71L.
- a signal representing the detected value (hereinafter simply referred to as a detected value of the first compressor temperature and a detected value of the second compressor temperature) is output to the control circuit board 9.
- the fifth temperature sensor Se5 and the sixth temperature sensor Se6 may be attached inside the shells of the first compressor 61H and the second compressor 71L.
- control circuit board 9 is built in the control panel 36 of FIG. As shown in FIG. 6, at least a nonvolatile memory 91, a control unit 92, and an SRAM 93 are mounted on the control circuit board 9.
- the non-volatile memory 91 is made of, for example, a flash memory and stores the program P.
- the control unit 92 is typically a microcomputer, and controls each unit of the refrigeration apparatus 1 by executing the program P using the SRAM 93 as a work area. Among such controls, what is important in the present embodiment is to control the rotational speeds of the first compressor 61H and the second compressor 71L so that the detected value PV of the internal temperature becomes the target value SV. It is. Hereinafter, this control is referred to as internal temperature control. In the present embodiment, five types of in-chamber temperature control are exemplified from the second to fifth columns and later.
- the rotational speeds of the first compressor 61H and the second compressor 71L are more specifically the rotational speeds of the first motor 611H provided in the first compressor 61H and the second compressor 71L. This is the rotational speed of the second motor 711L provided inside.
- control unit 92 sets the rotation speed of the first motor 611H and the rotation of the second motor 711L so that the deviation e between the detected value PV of the internal temperature and the target temperature is substantially zero. Determine the speed. Thereafter, the control unit 92 generates a first control signal CS1H and a second control signal CS2L that indicate frequencies correlated with the rotational speed of the first motor 611H and the rotational speed of the second motor 711L. The control unit 92 outputs the first control signal CS1H and the second control signal CS2L generated as described above to the first power supply unit 612H and the second power supply unit 712L.
- the first power supply unit 612H and the second power supply unit 712L are both inverter circuits.
- the first power supply unit 612H changes the frequency of the three-phase AC voltage based on the input first control signal CS1H and supplies it to the first motor 611H. Accordingly, the first motor 611H rotates at a rotation speed proportional to the frequency of the first control signal CS1 (that is, the rotation speed determined by the control unit 92).
- the second power supply unit 712L changes the frequency of the three-phase AC voltage based on the input second control signal CS2L and supplies it to the second motor 711L. Thus, the second motor 711L rotates at a rotation speed proportional to the frequency of the second control signal CS2 (that is, the rotation speed determined by the control unit 92).
- step S001 the controller 92 generates a first control signal CS1H indicating a frequency corresponding to the target rotational speed A0 in order to start the first compressor 61H.
- the target rotational speed A0 is preferably as large as possible, but the rotational speed is lower than the maximum rotational speed due to the load and the ability of the compressor. May be the target rotational speed A0.
- the first control signal CS1H is supplied to the first power supply unit 612H, the first motor 611H (that is, the first compressor 61H) starts (step S002).
- step S003 when a predetermined time has elapsed from the start of the first motor 611H (first compressor 61H) (step S003), the control unit 92 acquires the detected value of the first refrigerant temperature from the fourth temperature sensor Se4 (step S004). Thereafter, it is determined whether or not the detected value of the acquired first refrigerant temperature is equal to or lower than a predetermined first target temperature (step S005). If it is determined NO in the same step, the control unit 92 re-executes step S004.
- step S005 the control unit 92 causes the first cooling unit 6H to appropriately set the second refrigerant passing through the second second-stage condenser 73L when the cascade condenser 8 is lowered to an appropriate temperature. It is considered that the cooling is possible. Therefore, the control unit 92 generates the second control signal CS2L indicating the frequency corresponding to the target rotational speed B0 in order to start the second compressor 71L.
- the target rotational speed B0 is appropriately selected to be an appropriate value in order to make the internal temperature as quickly as possible to the target temperature.
- a keyboard 36a is provided for setting the target value SV of the internal temperature.
- the control unit 92 acquires the internal temperature target value SV set by the user from the keyboard 36a in parallel with the processing of FIGS. Write to the reserved storage area.
- the control unit 92 acquires the internal temperature target value SV from the nonvolatile memory 91 and the like, and also acquires the internal temperature detection value PV from the first temperature sensor Se1 after step S006. Thereafter, the control unit 92 adds a predetermined temperature to the target value SV of the internal temperature to obtain a first reference value Vref1 as an example of a temperature reference value (step S007 in FIG. 7B).
- the predetermined temperature in step S007 is a positive value, and is selected to be about + 4 ° C., for example.
- the control unit 92 determines whether or not the detected value PV of the internal temperature is equal to or less than the first reference value Vref1 obtained in step S007 (step S008). If YES is determined in the same step, the control unit 92 performs feedback control based on the target value SV and the detection value PV of the internal temperature. Specifically, the control unit 92 first obtains a deviation e between the detected value PV of the internal temperature and the target value SV (step S009). Next, the control unit 92 performs PI control (Proportional-Integral Control) in order to bring the deviation e close to zero, and calculates the target rotational speed B of the second compressor 71L. However, since the maximum rotation speed Bmax is determined for the second motor 711L, the upper limit value of the target rotation speed B is set to the maximum rotation speed Bmax (step S010).
- PI control Proportional-Integral Control
- the target rotational speed B is calculated by PI control as a preferred mode.
- the reason is as follows. With only P control (proportional control), the deviation e may remain for a long time depending on the outside air temperature. In order to remove the residual deviation e in a short time, PI control is executed by adding integral control (I control) using an integral value of the deviation e to P control.
- I control integral control
- the control unit 92 executes PID control (Proportional-Integral-Derivative Control) by adding differential control (D control) using time variation of the deviation e to the PI control. Is preferred.
- PID control Proportional-Integral-Derivative Control
- the amount of heat Q2, Q3 is determined by the amount of heat Q1. Therefore, if the target rotational speed B of the second compressor 71L is determined based on the heat quantity Q1 (that is, the deviation e) due to the disturbance, the first compressor 61H can be set to any target rotational speed in order to return the internal temperature to the target value SV.
- the target rotational speeds A and B have a predetermined correspondence relationship with each other. More specifically, it has been found that there is a positive correlation between the target rotational speeds A and B (that is, a relationship in which one of A and B increases as the other increases).
- the target rotation speed A is obtained by multiplying the target rotation speed B by a predetermined coefficient k (k is not less than 0.25 and not more than 4.00) (that is, the target rotation speed A becomes the target rotation speed).
- k is not less than 0.25 and not more than 4.00
- step S010 the control unit 92 multiplies the target rotational speed B determined in step S010 by a predetermined coefficient k to obtain a target rotational speed A that is proportional to the target rotational speed B. Calculate (step S011).
- the controller 92 determines whether or not the target rotational speed A calculated in step S011 is higher than the maximum rotational speed Amax of the first motor 611H (step S012). If YES is determined in the same step, the control unit 92 sets the maximum rotation speed Amax as the target rotation speed A (step S013).
- step S013 the controller 92 determines that either of the target rotational speeds A and B obtained up to step S013 is lower than the minimum rotational speeds Amin and Bmin of the motors 611H and 711L. It is determined whether or not (steps S014A and S014B). If YES is determined in one of steps S014A and S014B, one of the motors 611H and 711L cannot be properly operated, and as a result, the internal temperature cannot be returned to the target value SV.
- the unit 92 generates the first control signal CS1H and the second control signal CS2L in order to temporarily stop both the motors 611H and 711L. When the control signals CS1H and CS2L are supplied to the power supply units 612H and 712L, the motors 611H and 711L are stopped (step S015).
- the control unit 92 acquires the internal temperature detection value PV from the first temperature sensor Se1 (step S016 in FIG. 7A), and then the internal temperature detection value PV acquired in step S016 is the target value SV. It is determined whether or not it exceeds (step S017). Steps S016 and S017 are repeated until YES is determined in step S017. If it is determined YES in step S017, the controller 92 starts the first motor 611H to operate at the target rotational speed A0 by the same method as in step S002 (step S018). Thereafter, the control unit 92 re-executes step S004.
- control unit 92 If NO is determined in both steps, the control unit 92 generates a first control signal CS1H and a second control signal CS2L for operating the motors 611H and 711L at the target rotational speeds A and B.
- the control signals CS1H and CS2L are supplied to the power supply units 612H and 712L, the motors 611H and 711L eventually operate at the target rotational speeds A and B (step S019).
- the control unit 92 preferably changes the rotation speed of the motor 68H for the fan 67H according to the target rotation speed A or the target rotation speed B.
- the control part 92 performs step S020.
- control unit 92 acquires the detection value PV of the internal temperature from the first temperature sensor Se1, updates the detection value PV (step S020), and then re-executes step S008.
- step S008 If NO is determined in step S008, since the deviation e between the detected value PV of the internal temperature and the target value SV is still large, the control unit 92 sets the first motor 611H and the second 711L to the maximum rotational speed. A first control signal CS1H and a second control signal CS2L for operating at Amax and Bmax are generated. When the first control signal CS1H and the second control signal CS2L are supplied to the first power supply unit 612H and the second power supply unit 712L, the first motor 611H and the second motor 711L will eventually reach the maximum rotational speeds Amax and Bmax. (Step S021). Next, after performing step S020, the control unit 92 re-executes step S008.
- the control unit 92 determines the target rotational speeds A and B (steps S010 and S011 in FIG. 7B), and both the compressors 61H and 71L. Is basically (basically) operated at the target rotational speeds A and B (step S019).
- the target rotational speed B is determined by PI control based on the deviation e between the detected value PV of the internal temperature and the target value SV, but the target rotational speed A corresponds to the target rotational speed B determined by PI control. The value to be determined.
- the target rotation speed A is calculated by multiplying the target rotation speed B by a predetermined coefficient k.
- the deviation e is removed by the internal temperature control as described above, and the internal temperature returns to the target value SV.
- the target rotational speeds A and B are determined by a single feedback system as shown in FIG.
- the target rotational speed A is determined based on the target rotational speed B calculated by the PI control regardless of the temperature of the cascade capacitor 8.
- the first compressor 61H is operated without being affected by the heat transfer delay or interference as described in the section 1-2, so that the detected value PV of the internal temperature is higher than the target value SV. Too much lowering is suppressed (see after time t2 in FIG. 8).
- efficient operation of the compressors 61H and 71L becomes possible, and according to the refrigeration apparatus 1, energy waste can be suppressed.
- the rotational speeds of the compressors 61H and 71L are the maximum rotational speeds Amax and Bmax while the detected value PV of the internal temperature has not reached the first reference value Vref1 (see times t1 to t2 in FIG. 8). After reaching (see time t2 and after in FIG. 8), the target rotational speeds A and B determined by a single feedback system are changed to the heat transfer as described in the first and second columns. Both compressors 6H and 7L are operated without being affected by delay or interference. Thus, it is possible to provide the refrigeration apparatus 1 that can quickly return to the target value SV even if the temperature in the storage space S rises.
- the target rotational speed A is obtained by multiplying the target rotational speed B by a coefficient k.
- the present invention is not limited to this, and a table describing the correspondence relationship (positive correlation) between the target rotational speeds A and B (that is, the target rotational speed A appropriate for each target rotational speed B) is stored in the nonvolatile memory 91 in advance.
- the control unit 92 may read the target rotational speed A corresponding to the target rotational speed B obtained in step S010 from the table in step S011 and determine the target rotational speed A.
- FIGS. 10A and 10B differ from FIGS. 7A and 7B in that steps S101 to S105 are included instead of steps S004 to S006. Other than that, there is no difference between the two flow diagrams. Therefore, in FIG. 10A and FIG. 10B, the same step numbers are assigned to the steps corresponding to the steps shown in FIG. 7A and FIG. 7B, and detailed descriptions thereof are omitted.
- step S101 the control unit 92 performs the same operation as step S006 described above so that the second motor 711L (that is, the second compressor 71L) rotates at the target rotational speed B0. 711L is started (step S101).
- a time (delay time) after a predetermined time has elapsed from the start of the first compressor 61H in step S003 of FIG. 10A, that is, until the second compressor 71L is started in step S101 after the first compressor 61H is started.
- This time may be determined according to the second refrigerant temperature or the elapsed time since the second compressor 71L was stopped.
- the value is ⁇ 20 ° C. or less and 2 hours after the second compressor 71L is stopped. If it is within, the delay time is shortened. Specifically, the delay time may be set to 1 minute, for example.
- the delay time is lengthened.
- the delay time may be set to 8 minutes, for example.
- step S101 when the second refrigerant temperature is lower than a predetermined value or when the second compressor 71L has not been stopped for a longer time than the predetermined time, the second compression is performed in step S101. It is good to shorten the time until the machine 71L is started.
- control unit 92 acquires a detected value of the second refrigerant temperature from the third temperature sensor Se3 (step S102), and the acquired detected value of the second refrigerant temperature is equal to or lower than a predetermined second target temperature. It is judged whether it is (step S103). If YES is determined in the same step, the control unit 92 executes step S007 and subsequent steps (described above) in FIG. 10B.
- step S103 the control unit 92 stops the operation of the second compressor 71L for a certain period of time in order to stop the operation in the high load state on the second cooling unit 7L side. Then, it restarts (steps S104 and S105). Thereafter, the control unit 92 re-executes step S102 in order to reconfirm the second refrigerant temperature.
- steps S101 to S105 can prevent the second cooling unit 7L from operating in a high load state immediately after the power is turned on. The amount of heat generated by opening the heat insulating door 3 and the inner door 24 during the operation of the refrigeration apparatus 1 or putting a warm object to be cooled is sequentially transmitted from the second cooling unit 7L to the first cooling unit 6H.
- the internal temperature control can be performed more quickly and accurately.
- control unit 92 starts the second compressor 71L in step S101 of FIG. 10A, acquires the second refrigerant temperature detection value from the third temperature sensor Se3 in step S102, and then starts the second compressor 71L.
- the second compressor 71L may be stopped according to the second refrigerant temperature after a predetermined time has elapsed since the start.
- the second compressor 71L may be stopped.
- the second compressor 71L is not operated in a state where the second refrigerant temperature is higher than the predetermined temperature, so that the second cooling unit 7L becomes in a high load state immediately after the power is turned on. Can be suppressed.
- the predetermined time after starting the second compressor 71L may be changed according to the conditions.
- the condition in this case is that when the second refrigerant temperature is higher than a predetermined value and the second refrigerant temperature is decreasing, a predetermined time after starting the second compressor 71L, It is better to make it longer than.
- the predetermined time is set to 120 seconds after starting the second compressor 71L. Good.
- the internal temperature control can be performed more efficiently by changing the predetermined time from the start of the second compressor 71L to the stop of the second compressor 71L according to the conditions. .
- the second compressor 71L is started again.
- the second compressor 71L may be started again.
- the control unit 92 temporarily increases the rotation speed of the first compressor 61H for a predetermined time according to the outside air temperature after a predetermined time has elapsed. May be.
- the rotational speed of the first compressor 61H may be increased from 3600 rpm (an example of the target rotational speed A0) to 4000 rpm. That is, when the outside air temperature is higher than a predetermined value, the rotational speed of the first compressor 61H may be temporarily made higher than the target rotational speed A0.
- the rotational speed of the first compressor 61H is increased after 20 seconds, for example.
- the 1st compressor 61H in the state which made the rotation speed high, when a high temperature peak value is detected in the 2nd refrigerant temperature, and the 2nd refrigerant temperature becomes below a predetermined value, the 1st compression
- the rotational speed of the machine 61H is returned to the target rotational speed A0.
- the rotational speed of the first compressor 61H may be returned to the target rotational speed A0.
- the rotational speed of the first compressor 61H is temporarily increased after a predetermined time has elapsed, and the rotational speed is increased. After operating the first compressor 61H, the rotational speed of the first compressor 61H may be returned to the target rotational speed A0 according to the second refrigerant temperature.
- the rotational speed of the first compressor 61H can be increased and the performance of the first cooling unit 6H can be improved in a state where the outside air temperature is excessively high, so that the second cooling unit 7L is high immediately after the power is turned on. It can suppress becoming a load state.
- the control unit 92 After the power is turned on, the control unit 92 first acquires the target value SV of the internal temperature from the nonvolatile memory 91 or the like, and acquires the detection value PV of the internal temperature from the first temperature sensor Se1 (step S201 in FIG. 11A). ). Next, the control part 92 calculates
- the control unit 92 determines whether or not the current deviation e is equal to or greater than a predetermined second reference value Vref2 (step S203).
- the second reference value Vref2 is an example of a second deviation reference value, and is a reference temperature for starting both the compressors 61H and 71L, and is selected to be about 5 ° C., for example. If it is determined NO in the same step, the control unit 92 re-executes step S201.
- step S203 the control unit 92 controls the control signals CS1H and CS2L so that both the motors 611H and 711L (that is, both the compressors 61H and 71L) are operated at the target rotational speeds A0 and B0. Is supplied to the power supply units 612H and 712L. Thereby, the control part 92 starts both motors 611H and 711L simultaneously (step S204). At this time, the target rotational speeds A0 and B0 are appropriately set appropriately so that the cascade capacitor 8 and the like reach an appropriate temperature as soon as possible.
- control unit 92 acquires a detected value of the second refrigerant temperature from the third temperature sensor Se3 (step S205), and the acquired detected value of the second refrigerant temperature becomes equal to or lower than a predetermined second target temperature. It is determined whether or not (step S206).
- step S206 the control unit 92 assumes that the second cooling unit 7L is in a high load operation, stops the second compressor 71L for a predetermined time, and then restarts (step S207, S208). Thereafter, the control unit 92 re-executes step S205 to reconfirm the second refrigerant temperature.
- the control unit 92 acquires the detection value PV of the internal temperature from the first temperature sensor Se1, and also acquires the target value SV stored in the nonvolatile memory 91 or the like. (Step S209 in FIG. 11B). Next, the control unit 92 obtains a deviation e between the detection value PV acquired in step S209 and the target value SV, and then adds a predetermined temperature to the deviation e to obtain a first deviation reference value as an example. Three reference values Vref3 are obtained (step S210).
- the predetermined temperature in step S210 is a positive value, and is selected to be, for example, about + 4 ° C.
- step S211 determines whether or not the current deviation e is equal to or less than the third reference value Vref3 obtained in step S210 (step S211). If NO is determined in step S211, the control unit 92 operates the first motor 611H and the second motor 711L at the maximum rotation speeds Amax and Bmax in the same manner as in step S021 described above (step S212). Next, the control unit 92 acquires the detection value PV of the internal temperature from the first temperature sensor Se1, obtains and updates the deviation e from the acquired detection value PV and the target value SV (step S213), and then step S211 is executed again.
- control unit 92 calculates the target rotational speed B of the second compressor 71L in the same manner as the above-described steps S010 and S011, and then determines the target rotational speed B and A target rotational speed A having a correspondence relationship is calculated (steps S214 and S215).
- the control unit 92 sets the target rotational speed A to the maximum rotational speed Amax (step S216, S216). S217). If NO is determined in step S216 or after step S217, the control unit 92 determines whether or not the obtained target rotation speed A is less than the minimum rotation speed Amin in the same manner as steps S014A and S014B. It is determined whether or not the obtained target rotational speed B is less than the minimum rotational speed Bin (steps S218A and S218B).
- step S218A and S218B If YES is determined in one of steps S218A and S218B, the motors 611H and 711L are stopped in the same manner as in step S015 (step S219). Thereafter, the control unit 92 re-executes step S201 of FIG. 11A.
- control unit 92 operates the motors 611H and 711L at the target rotational speeds A and B in the same manner as in step S019 described above (step S220). In the same step, the controller 92 preferably changes the rotational speed of the motor 68H for the fan 67H in accordance with the target rotational speed A in the same manner as in step S019 described above. Thereafter, the control unit 92 executes Step S213.
- the detection value PV of the internal temperature is 20 ° C.
- the target value SV of the internal temperature is ⁇ 80 ° C.
- the deviation e at this time is 100 ° C.
- step S203 If the second reference value Vref2 is 5 ° C., it is determined in step S203 that the current deviation e (100 ° C.) is greater than or equal to the second reference value Vref2, and in step S204, both compressors 61H and 71L are targeted.
- the engine is started to operate at the rotational speeds A0 and B0. Thereby, the first refrigerant and the second refrigerant start to circulate in the first fluid circuit 66H and the second fluid circuit 76L.
- step S206 If it is determined in step S206 that the second refrigerant temperature is higher than the second target temperature, in steps S207 and S208, as described above, the second compressor 71L is stopped for a predetermined time and then restarted. In addition, the second compressor 71L may be operated at a low rotational speed for a predetermined time.
- step S206 If it is determined in step S206 that the second refrigerant temperature is equal to or lower than the second target temperature, the compressors 61H and 71L are at the highest level as shown at times t1 to t2 in FIG. 8 until YES is determined in step S211.
- the engine is operated at the rotational speeds Amax and Bmax. If YES is determined in step S211, the target rotational speed B of the second compressor 71L is calculated by PI control shown in and after step S214, and the target rotational speed A is calculated by multiplying the target rotational speed B by a coefficient k. Is also calculated.
- the target rotational speed A is a broken line connecting (4) and (5) in FIG. 12 by the processing of steps S216 and S217. As shown in minutes, the maximum rotational speed Amax (for example, 4500 min ⁇ 1 ) is suppressed.
- the first compressor 61H has the target rotational speed as shown by the broken line segments connecting (3) and (4) in FIG.
- the second compressor 71L is operated at the target rotational speed B as indicated by the solid line connecting (6) and (5) in FIG.
- FIG. 12 the case where k is 1.2 is illustrated.
- steps S205 to S208 can prevent the second cooling unit 7L from operating in a high load state immediately after the power is turned on.
- the detected value of the second refrigerant temperature is acquired from the third temperature sensor Se3, and it is determined whether or not the acquired second refrigerant temperature is equal to or lower than the second target temperature. It was.
- the present invention is not limited to this, and the detected value of the first refrigerant temperature is acquired from the fourth temperature sensor Se4 as described in parentheses in steps S205 and S206 of FIG. 11A, and the acquired first refrigerant temperature is the first target. It may be determined whether or not the temperature is below. This also makes it possible to determine whether or not the second cooling unit 7L is in a high load operation.
- both compressors 61H and 71L are stopped in step S219 of FIG. 11B.
- the present invention is not limited to this, and only the second compressor 71L may be stopped and the first compressor 61H may be operated at the minimum rotational speed Amin. In short, the first compressor 61H may be operated at a lower speed than before.
- the target rotational speed A is calculated by multiplying the target rotational speed B by the coefficient k in step S215 of FIG. 11B.
- the control unit 92 repeats the loop of steps S205 to S208 of FIG. 11A at most several times, so that the second refrigerant temperature becomes equal to or lower than the second target temperature, and step S206. To Step S209. Using this characteristic, if the number of executions of this loop is equal to or greater than the predetermined number, the control unit 92 assumes that an abnormality has occurred in the refrigeration apparatus 1 and displays message information indicating that fact on the display 36b. good.
- FIGS. 13A and 13B differ from FIGS. 11A and 11B in that steps S301 to S304 are included instead of steps S204 to S208. Other than that, there is no difference between the two flow diagrams. Therefore, in FIG. 13A and FIG. 13B, the steps corresponding to the steps shown in FIG. 11A and FIG.
- the control unit 92 determines YES in step S203, the control unit 92 generates the first control signal CS1H and supplies the first control signal CS1H to the first power supply unit 612H in order to operate the first compressor 61H at the predetermined target rotational speed A0. .
- the target rotational speed A0 is selected, for example, 4000 min ⁇ 1 .
- the control unit 92 generates the first control signal CS1H so as to increase the rotation speed of the first motor 611H to the target rotation speed A0 according to a predetermined acceleration sequence (step S301).
- the actual rotation speed of the first compressor 61H is detected by the first power supply unit 612H, which is an inverter circuit, and is output to the control unit 92.
- the control unit 92 performs the first control while referring to the actual rotation speed. It is desirable to output the signal CS1H. However, the controller 92 does not necessarily generate the first control signal CS1H based on the actual rotation speed. If there is no rotation abnormality signal of the first compressor 61H, the first compression is performed according to a predetermined acceleration sequence. The rotational speed of the machine 61H may be adjusted to the target rotational speed A0.
- the control unit 92 When the rotation speed of the first compressor 61H reaches the target rotation speed A1 (A1 is a number satisfying A1 ⁇ A0) (that is, when a predetermined time has elapsed) (step S302), the control unit 92 then In order to operate the two compressors 71L at a predetermined target rotational speed B0, the second control signal CS2L is generated and supplied to the second power supply unit 712L according to a predetermined acceleration sequence.
- the target rotation speed B0 is set to, for example, 2000 min ⁇ 1 so that the cascade capacitor 8 reaches an appropriate temperature as soon as possible (step S303).
- step S304 When the rotational speed of the second compressor 71L reaches the target rotational speed B0 (that is, when a predetermined time has elapsed) (step S304), the control unit 92 executes step S209 and subsequent steps (described above) in FIG. 13B.
- steps S301 to S304 can prevent the second cooling unit 7L from operating in a high load state immediately after the power is turned on.
- FIGS. 14A and 14B differ from FIGS. 11A and 11B in that steps S401 to S404 are included instead of steps S204 to S208. Other than that, there is no difference between the two flow diagrams. Therefore, in FIGS. 14A and 14B, the steps corresponding to the steps shown in FIGS. 11A and 11B are denoted by the same step numbers, and detailed descriptions thereof are omitted.
- step S203 If the determination is YES in step S203, the control unit 92 starts the first compressor 61H so that the first compressor 61H operates at the target rotational speed A0 in the same manner as in step S301 described above (step S401). ).
- the control unit 92 acquires a detected value of the second refrigerant temperature from the third temperature sensor Se3 (step S402), and the acquired detected value of the second refrigerant temperature becomes equal to or lower than a predetermined second target temperature. It is determined whether or not (step S403). As described in the column 2-15, as described in parentheses in steps S402 and S403 in FIG. 14A, the detected value of the first refrigerant temperature is acquired from the fourth temperature sensor Se4, and the acquired second value is acquired. It may be determined whether one refrigerant temperature is equal to or lower than a first target temperature. If NO is determined in step S403, the control unit 92 re-executes step S402.
- step S403 the controller 92 determines that the second refrigerant passing through the second second-stage condenser 73L can be appropriately cooled, and starts the second compressor 71L.
- a second control signal CS2L indicating a frequency corresponding to the target rotation speed B0 is generated and supplied to the second power supply unit 712L.
- the 2nd motor 711L namely, 2nd compressor 71L
- control unit 92 executes step S209 and subsequent steps (described above) in FIG. 14B.
- steps S401 to S404 can prevent the second cooling unit 7L from operating in a high load state immediately after the power is turned on.
- the coefficient k is preferably a fixed value as long as it is within the range of 0.25 to 4.00.
- both compressors 61H , 71L in order to minimize the total power consumption (hereinafter simply referred to as total power consumption), the ratio of the target rotational speeds A and B (that is, k) is variable depending on the target value SV of the internal temperature and the ambient temperature. It turned out to be preferable.
- a curve C1 represents a correspondence relationship between the rotation speeds A and B suitable for obtaining an internal temperature of ⁇ 70 ° C. under a condition where the ambient temperature is 15 ° C.
- the point where the total power consumption is minimum on the curve C1 is the point (1) (that is, the target rotational speeds A and B are about 1900 min ⁇ 1 and 2000 min ⁇ 1 ).
- FIG. 15 also shows curves C2, C3, and C4.
- a curve C2 shows the correspondence relationship between the rotational speeds A and B for obtaining the internal temperature of ⁇ 70 ° C. when the ambient temperature is 30 ° C.
- Curves C3 and C4 show the correspondence between the rotational speeds A and B for obtaining the internal temperature of ⁇ 80 ° C. under conditions where the ambient temperature is 15 ° C. and 30 ° C.
- Points (2), (3), and (4) have the minimum total power consumption on the curves C2, C3, and C4.
- the above points (1) to (4) are the total power consumption in the design and development stage of the refrigeration system 1 by changing the rotational speeds of the compressors 61H and 71L while appropriately changing the ambient temperature and the internal temperature It is obtained by measuring.
- the target rotation speed A at the point (2), B is at 2300min -1, 2000min -1
- target rotation speed A of the point (3), B is at 2400min -1, 2250min -1
- the point (4 ) Target rotational speeds A and B were 3000 min ⁇ 1 and 2250 min ⁇ 1 .
- Table 1 below the coefficient k when the ambient temperature is 23 ° C. is an interpolation value of the coefficient k when the ambient temperature is 15 ° C. and 30 ° C.
- the control unit 92 holds in advance a table (the above table 1) in which the optimum coefficient k is described for each combination of the ambient temperature and the internal temperature (target value).
- the control unit 92 obtains the detected value ST of the ambient temperature from the second temperature sensor Se2.
- the internal temperature target value SV stored in the non-volatile memory 91 or the like is acquired, and a coefficient k corresponding to the combination of the acquired ambient temperature detection value ST and the internal temperature target value SV (in other words, rotation The correspondence relationship between the speeds A and B) is acquired from the table and determined.
- the control unit 92 obtains the coefficient k by the interpolation process as described above.
- control unit 92 calculates the target rotational speed A in step S011 in FIGS. 7B and 10B or in step S215 in FIGS. 11B, 13B, and 14B. As a result, the total power consumption in the internal temperature control can be minimized.
- the first power supply unit 612H and the second power supply unit 712L include inverter circuits.
- Such an inverter circuit may have a built-in protection function.
- the first electric power supply unit 612H and the second electric power supply unit 712L are not connected to the first electric power supply unit 612H and the second electric power supply unit 712L when the first motor 61H and the second motor 72L fail to start, during abnormal operation such as overload, or when a large current flows.
- the one abnormal signal and the second abnormal signal are output to the control unit 92.
- the control unit 92 outputs both control signals CS1H and CS2L to both the power supply units 612H and 712L, and instructs the compressors 61H and 71L to operate, thereby causing the first abnormality from the first power supply unit 612H.
- the control unit 92 sets the operation speed of the second compressor 71L, which is a cause of high load, to be lower than before, and after a certain time has elapsed or that the abnormal signal has been canceled. Confirm and return to the original operating speed, or temporarily stop the operation of the second compressor 71L and restart it after a certain period of time.
- control unit 92 when the control unit 92 receives the second abnormality signal, the control unit 92 sets the operation speed of the second compressor 71L to be lower than before, confirms that the abnormality signal has been released after a certain time has elapsed, The original operation speed is restored, or the operation of the second compressor 71L is temporarily stopped and restarted after a predetermined time has elapsed.
- the controller 92 periodically detects the temperature of the cascade capacitor 8 from at least one of the third temperature sensor Se3 and the fourth temperature sensor Se4. When it is determined that the acquired detection value is out of the predetermined temperature range, control is performed so that the acquired detection value returns to the predetermined temperature range.
- the predetermined temperature range is a temperature range that the cascade capacitor 8 wants to protect in order to protect the compressor.
- the control unit 92 at least one of the rotational speed of the first compressor 61H and the rotational speed of the second compressor 71L. Is changed to zero.
- the control unit 92 periodically performs the first operation by the third temperature sensor Se3.
- the control unit 92 determines at least one of the rotational speed of the first compressor 61H and the rotational speed of the second compressor 71L. Change or zero.
- the control unit 92 in addition to the above, in the first to fifth examples of the internal temperature control, while the first compressor 61H and the second compressor 71L are in operation, the control unit 92 periodically performs the fifth temperature sensor Se5 and the fifth temperature sensor Se5. The detected value of the first compressor temperature and the detected value of the second compressor temperature are acquired from the six temperature sensor Se6. When the control unit 92 determines that at least one of the acquired detection values is equal to or higher than the predetermined temperature, it is determined that at least one of the first compressor 61H and the second compressor 71L is abnormally overheated, and the first compressor 61H and The rotational speed of at least one or both of the second compressor 71L is reduced or zero. If it is determined that at least one of the acquired detection values is equal to or higher than the predetermined temperature, the control unit 92 may change the rotation speed of the motor 68H for the fan 67H at a higher speed than before.
- the refrigeration apparatus according to the present invention can quickly return the temperature of the storage space, and is suitable for an ultra-low temperature freezer or the like.
Abstract
Description
第一冷媒が循環する第一流体回路に、第一圧縮機、第一凝縮器、第一膨張器および第一蒸発器が流体連通するように配置された第一冷却部と、
第二冷媒が循環する第二流体回路に、第二圧縮機、前記第一蒸発器と共にカスケードコンデンサを構成する第二凝縮器、第二膨張器および第二蒸発器が流体連通するよう配置された第二冷却部と、
前記第二蒸発器により冷却される冷却対象物の収納スペースを有する収納部と、
前記収納スペースの温度を検出する庫内温度センサと、
前記収納スペースの目標温度と、前記庫内温度センサの検出結果とに基づき、前記第二圧縮機の第二回転速度を決定する制御部であって、前記第二回転速度と所定の対応関係にある前記第一圧縮機の第一回転速度を決定する制御部と、
前記制御部が決定した第一回転速度および第二回転速度に基づき、前記第一圧縮機および前記第二圧縮機に電力供給を行う第一電力供給部および第二電力供給部と、を備えている。
本発明の冷凍装置1を説明する前に、比較例に係る冷凍装置10における庫内温度制御の技術的課題を詳説する。
図1において、比較例に係る冷凍装置10は、冷却部15を備える。冷却部15は、第一冷却部16Hと、第二冷却部17Lと、を含む。
例えば、目標温度(約-80℃)に冷却された収納スペースSに、扉を開く等して暖かい負荷が投入されることがある。この場合、比較例の庫内温度制御では、収納スペースS内の温度を目標温度に素早く復帰させることが難しいという第一問題点があった。第一問題点に加え、比較例に係る庫内温度制御では、第一圧縮機と第二圧縮機の各回転速度が不必要に増減し、エネルギーを浪費してしまうという第二問題点があった。以下、図1,図2を参照して、両問題点について詳細に説明する。
以下、図3以降を参照して、各実施形態に係る冷凍装置1を詳説する。
≪2-1.定義≫
図3,図4において、X軸は、冷凍装置1の横方向(より具体的には、ユーザが冷凍装置1に正対した時に右側から左側に向かう方向)を示す。Y軸は、冷凍装置1の前後方向(より具体的には、上記正対時に奥側(背面側)から手前側(前面側)に向かう方向)を示す。また、Z軸は、冷凍装置1の上下方向(より具体的は、冷凍装置1の下側から上側に向かう方向)を示す。
冷凍装置1は、図3,図4に示すよう、大略的には、断熱筐体2と、断熱扉3と、機械室4と、を備えている。
冷却部5は、図5に示すように、第一冷却部6Hと、第二冷却部7Lと、を備えている。
上述の冷却部5の様々な箇所には圧力センサまたは温度センサが設けられている。本実施形態で重要であるのは、図5,図6に示す第一温度センサSe1、第二温度センサSe2、第三温度センサSe3、第四温度センサSe4、第五温度センサSe5および第六温度センサSe6である。
・第一流体回路66Hにおける、第一蒸発器65Hの冷媒入口側、冷媒出口側またはそれらの中間位置
・第二流体回路76Lにおける、第二後段凝縮器73Lの冷媒入口側、冷媒出口側またはそれらの中間位置
・第二流体回路76Lにおける第二膨張器74Lの冷媒入口近傍
第一流体回路66H,第二流体回路76Lを断熱のためにガラスウール等で覆うことで、第三温度センサSe3および第四温度センサSe4は精度良く冷媒の温度を検出できる。また、ガラスウールで断熱を行うため、第三温度センサSe3および第四温度センサSe4の取り付けも、発泡ウレタンで固める場合と比較して容易に行える。
次に、図7A,図7Bを参照して庫内温度制御の第一例を説明する。
主電源の投入により制御部92等が起動する。制御部92は、まず、主電源投入から所定時間が経過すると(ステップS001)、第一圧縮機61Hを始動させるべく、目標回転速度A0に対応する周波数を示す第一制御信号CS1Hを生成する。ここで、カスケードコンデンサ8を極力早く適切な温度に低下させるべく、目標回転速度A0は、極力大きな回転速度であることが好ましいが、負荷や圧縮機の能力により最大の回転速度より下げた回転速度を目標回転速度A0としてもよい。この第一制御信号CS1Hが第一電力供給部612Hに供給されると、第一モータ611H(即ち、第一圧縮機61H)は始動する(ステップS002)。
次に、制御部92は、ステップS011で算出した目標回転速度Aが第一モータ611Hの最高回転速度Amax超であるか否かを判断する(ステップS012)。同ステップでYESと判断すると、制御部92は、目標回転速度Aとして最高回転速度Amaxを設定する(ステップS013)。
以上の通り、本庫内温度制御(第一例)によれば、庫内温度の検出値PVが第一基準値Vref1を上回っている間(即ち、ステップS008でNOと判断している間)、制御部92は、両圧縮機61H,71Lを最高回転速度Amax,Bmaxで運転する(図7BのステップS021)。それ故、内扉24が開く等して収納スペースS内の温度が上昇したとしても、庫内温度の目標値SVよりも若干高い温度(第一基準値Vref1)に庫内温度を素早く到達させることが出来る(図8の時刻t1から時刻t2までの間を参照)。
また、本庫内温度制御によれば、電源投入直後には第一冷却部6Hのみが運転させられるため、第二冷却部7Lが高負荷状態で運転することを防止できる。
なお、上記庫内温度制御(第一例)の説明では、目標回転速度Aは、目標回転速度Bに係数kを乗算することで求めていた。しかし、これに限らず、目標回転速度A,Bの対応関係(正相関の関係)(即ち、目標回転速度B毎に適切な目標回転速度A)を記述したテーブルが不揮発性メモリ91に予め格納される場合、制御部92は、ステップS011において、ステップS010で得られた目標回転速度Bに対応する目標回転速度Aをテーブルから読み出して、目標回転速度Aを決定しても構わない。
次に、図10A,図10Bを参照して庫内温度制御の第二例を説明する。ここで、図10A,図10Bは、図7A,図7Bと比較すると、ステップS004~S006に代えてステップS101~S105を含む点で相違する。それ以外に両フロー図の間に相違点は無い。それゆえ、図10A,図10Bにおいて、図7A,図7Bに示すステップに相当するものには同一のステップ番号を付け、それぞれの詳説を控える。
以上の庫内温度制御(第二例)でも、庫内温度制御(第一例)と同様に、両圧縮機61H,71Lの回転速度が制御されるため、第2-6欄で説明した作用・効果を奏する。さらに、ステップS101~S105により、電源投入直後に、第二冷却部7Lが高負荷状態で運転することを防止できる。本冷凍装置1の運転中における断熱扉3や内扉24を開けたり、暖かい冷却対象物を投入したりすることによる熱量は、第二冷却部7Lから、第一冷却部6Hへと順に伝わる。それゆえ、庫内温度制御(第二例)のように第二冷媒の温度を検出することにより、第一冷媒の温度変動より早く上記の熱量変動状況を検知することができる。よって、庫内温度制御をより早く精度よく行うことが可能となる。
なお、上記庫内温度制御(第二例)の説明では、ステップS104,S105において、制御部92は、第二圧縮機71Lを一定時間停止させた後、再始動するとして説明した。しかし、ステップS002で設定された第一圧縮機61Hの目標回転速度A0が最高回転速度Amax以下であれば、制御部92は、ステップS104,S105の代わりに、第一圧縮機61Hの回転速度をステップS002で設定した目標回転速度A0よりも高速にしても構わない。これによって、電源投入直後に第二冷却部7Lが高負荷状態になることを抑制できる。
次に、図11A,図11Bを参照して庫内温度制御の第三例を説明する。
電源投入後、制御部92はまず、庫内温度の目標値SVを不揮発性メモリ91等から取得すると共に、第一温度センサSe1から庫内温度の検出値PVを取得する(図11AのステップS201)。次に、制御部92は、取得した検出値PVと目標値SVとの偏差eを求めて、SRAM93等に格納する(ステップS202)。
ステップS211でNOと判断された場合、制御部92は、前述のステップS021と同じ要領で、第一モータ611Hおよび第二モータ711Lを最高回転速度Amax,Bmaxで動作させる(ステップS212)。
次に、制御部92は、第一温度センサSe1から庫内温度の検出値PVを取得し、取得した検出値PVと目標値SVとから偏差eを求めて更新した後(ステップS213)、ステップS211を再実行する。
次に、図12を参照して、上記庫内温度制御(第三例)を所定条件下で実行した時の第一圧縮機61H,第二圧縮機71Lの回転速度の変化の一例について説明する。
以上の庫内温度制御(第三例)でも、庫内温度制御(第一例)と同様に、両圧縮機61H,71Lの回転速度が制御されるため、第2-6欄で説明した作用・効果を奏する。さらに、ステップS205~S208により、電源投入直後に、第二冷却部7Lが高負荷状態で運転することを防止できる。
上記では、図11AのステップS205,S206において、第三温度センサSe3から第二冷媒温度の検出値が取得され、取得された第二冷媒温度が第二目標温度以下であるか否かが判断されていた。しかし、これに限らず、図11AのステップS205,S206の括弧内に記載の通り、第四温度センサSe4から第一冷媒温度の検出値が取得され、取得された第一冷媒温度が第一目標温度以下であるか否かが判断されても良い。これによっても、第二冷却部7Lが高負荷運転になっているか否かを判断できる。
次に、図13A,図13Bを参照して庫内温度制御の第四例を説明する。
図13A,図13Bは、図11A,図11Bと比較すると、ステップS204~S208に代えてステップS301~S304を含む点で相違する。それ以外に両フロー図の間に相違点は無い。それゆえ、図13A,図13Bにおいて、図11A,図11Bに示すステップに相当するものには同一のステップ番号を付け、それぞれの詳説を控える。
以上の庫内温度制御(第四例)でも、庫内温度制御(第一例)と同様に、両圧縮機61H,71Lの回転速度が制御されるため、第2-6欄で説明した作用・効果を奏する。さらに、ステップS301~S304により、電源投入直後に、第二冷却部7Lが高負荷状態で運転することを防止できる。
次に、図14A,図14Bを参照して庫内温度制御の第五例を説明する。
図14A,図14Bは、図11A,図11Bと比較すると、ステップS204~S208に代えてステップS401~S404を含む点で相違する。それ以外に両フロー図の間に相違点は無い。それゆえ、図14A,図14Bにおいて、図11A,図11Bに示すステップに相当するものには同一のステップ番号を付け、それぞれの詳説を控える。
以上の庫内温度制御(第五例)によっても、第2-6欄で説明した作用・効果を奏する。さらに、ステップS401~S404により、電源投入直後に、第二冷却部7Lが高負荷状態で運転することを防止できる。
上記庫内温度制御において、係数kは好ましくは0.25以上4.00以下の範囲内であれば固定値であって構わないが、本件発明者が鋭意検討を重ねた結果、両圧縮機61H,71Lの合計消費電力(以下、単に合計消費電力という)を最小にするには、目標回転速度A,Bの比(即ち、k)は、庫内温度の目標値SVおよび周囲温度により可変にすることが好ましいことが判明した。
前述の通り、第一電力供給部612Hおよび第二電力供給部712Lはインバータ回路を含む。かかるインバータ回路には保護機能が内蔵されている場合がある。例えば、第一モータ61Hおよび第二モータ72Lの始動失敗時や、過負荷等の異常動作時、大電流が流れた時などに、第一電力供給部612Hおよび第二電力供給部712Lは、第一異常信号および第二異常信号を制御部92に出力する。
また、庫内温度制御の第一例から第五例において、制御部92は、定期的に、第三温度センサSe3および第四温度センサSe4の少なくともいずれか一方からカスケードコンデンサ8の温度の検出値を取得して、取得した検出値が所定温度範囲から外れたと判断すると、取得した検出値が所定温度範囲内に復帰するように制御する。ここで、所定温度範囲は、圧縮機の保護のために、カスケードコンデンサ8が守りたい温度範囲である。具体例を挙げると、カスケードコンデンサ8の温度の検出値が所定温度範囲の下限値を下回ると、制御部92は、第一圧縮機61Hの回転速度および第二圧縮機71Lの回転速度の少なくとも一方を変更したりゼロにしたりする。
上記以外にも、庫内温度制御の第一例から第五例において、第一圧縮機61Hおよび第二圧縮機71Lが運転中、制御部92は、定期的に、第三温度センサSe3による第二冷媒温度の検出値を取得して、取得した検出値が所定温度範囲から外れたと判断すると、取得した検出値が所定温度範囲内に復帰するように制御する。具体例を挙げると、第二冷媒温度の検出値が所定温度範囲の下限値を下回ると、制御部92は、第一圧縮機61Hの回転速度および第二圧縮機71Lの回転速度の少なくとも一方を変更したりゼロにしたりする。
上記以外にも、庫内温度制御の第一例から第五例において、第一圧縮機61Hおよび第二圧縮機71Lが運転中、制御部92は、定期的に、第五温度センサSe5および第六温度センサSe6から、第一圧縮機温度の検出値および第二圧縮機温度の検出値を取得する。制御部92は、取得した検出値の少なくとも一方が所定温度以上であると判断すると、第一圧縮機61Hおよび第二圧縮機71Lの少なくとも一方が異常過熱しているとして、第一圧縮機61Hおよび第二圧縮機71Lの少なくとも一方または両方の回転速度を低速にしたりゼロにしたりする。取得した検出値の少なくとも一方が所定温度以上であると判断すると、制御部92は他にも、ファン67H用のモータ68Hの回転速度をそれまでよりも高速に変更しても良い。
S 収納スペース
6H 第一冷却部
61H 第一圧縮機
611H 第一モータ
612H 第一電力供給部
62H 第一前段凝縮器
63H 第一後段凝縮器
64H 第一膨張器
65H 第一蒸発器
66H 第一流体回路
67H ファン
68H モータ
7L 第二冷却部
71L 第二圧縮機
711L 第二モータ
712L 第二電力供給部
72L 第二前段凝縮器
73L 第二後段凝縮器
74L 第二膨張器
75L 第二蒸発器
76L 第二流体回路
8 カスケードコンデンサ
92 制御部
Se1 第一温度センサ(庫内温度センサ)
Se2 第二温度センサ(周囲温度センサ)
Se3 第三温度センサ(第二流体回路温度センサ)
Se4 第四温度センサ(カスケード温度センサ)
Claims (14)
- 第一冷媒が循環する第一流体回路に、第一圧縮機、第一凝縮器、第一膨張器および第一蒸発器が流体連通するように配置された第一冷却部と、
第二冷媒が循環する第二流体回路に、第二圧縮機、前記第一蒸発器と共にカスケードコンデンサを構成する第二凝縮器、第二膨張器および第二蒸発器が流体連通するよう配置された第二冷却部と、
前記第二蒸発器により冷却される冷却対象物の収納スペースを有する収納部と、
前記収納スペースの温度を検出する庫内温度センサと、
前記収納スペースの目標温度と、前記庫内温度センサの検出結果とに基づき、前記第二圧縮機の第二回転速度を決定する制御部であって、前記第二回転速度と所定の対応関係にある前記第一圧縮機の第一回転速度を決定する制御部と、
前記制御部が決定した第一回転速度および第二回転速度に基づき、前記第一圧縮機および前記第二圧縮機に電力供給を行う第一電力供給部および第二電力供給部と、を備える冷凍装置。 - 前記第一回転速度は、前記第二回転速度と正相関の関係にある、請求項1に記載の冷凍装置。
- 前記制御部は、前記収納スペースの目標温度と、前記庫内温度センサの検出結果とに基づく比例制御、比例及び積分制御および比例、積分及び微分制御のいずれか一つにより前記第二回転速度を決定すると共に、前記第二回転速度と比例関係にある第一回転速度を決定する、請求項1または2に記載の冷凍装置。
- 前記制御部は、前記庫内温度センサの検出結果が所定の温度基準値以下、または前記庫内温度センサの検出結果と前記収納スペースの目標温度との偏差が第一偏差基準値以下になると、前記第一回転速度および前記第二回転速度を決定する、請求項1~3のいずれかに記載の冷凍装置。
- 自装置の周囲温度を検出する周囲温度センサをさらに備え、
前記制御部は、前記収納スペースの目標温度と、前記周囲温度センサの検出結果とに基づき、前記所定の対応関係を決定する、請求項1~4のいずれかに記載の冷凍装置。 - 前記第一電力供給部および前記第二電力供給部はさらに、自身が異常状態であること示す第一異常信号および第二異常信号を前記制御部に出力し、
前記制御部は、前記第一回転速度および前記第二回転速度の決定後、前記第一異常信号または前記第二異常信号を受け取ると、前記第二回転速度を一時的に低減する、請求項1~5のいずれかに記載の冷凍装置。 - 前記第二流体回路の温度を検出する第二流体回路温度センサをさらに備え、
前記制御部は、少なくとも前記第一圧縮機または前記第二圧縮機が動作中、前記第二流体回路温度センサの検出結果が所定温度範囲になるように、前記第一回転速度および前記第二回転速度の少なくとも一方を変更する、請求項1~6のいずれかに記載の冷凍装置。 - 前記第二流体回路温度センサは、前記カスケードコンデンサを構成する前記第二凝縮器における第二冷媒の出口温度を検出し、
前記制御部は、少なくとも前記第一圧縮機または前記第二圧縮機が動作中、前記第二流体回路温度センサの検出結果が所定温度範囲になるように、前記第一回転速度および前記第二回転速度の少なくとも一方を変更する、請求項7に記載の冷凍装置。 - 前記第一回転速度または前記第二回転速度に応じた回転数で回転して、前記第一凝縮器に空気流を送るファンをさらに備える、請求項1~8のいずれかに記載の冷凍装置。
- 少なくとも前記第一圧縮機または前記第二圧縮機の温度に応じた回転数で回転して、前記第一凝縮器に空気流を送るファンをさらに備える、請求項1~8のいずれかに記載の冷凍装置。
- 前記第一圧縮機および前記第二圧縮機の少なくともいずれか一方の温度が所定温度以上になると、前記制御部は、前記第一圧縮機および前記第二圧縮機の少なくともいずれか一方の回転速度を小さな値に決定する、請求項1~10のいずれかに記載の冷凍装置。
- 前記第一圧縮機および前記第二圧縮機の両方が停止した状態において、前記第一電力供給部は、前記第一圧縮機に電力供給を行って、第一目標回転速度で動作するよう前記第一圧縮機を始動させ、前記第二電力供給部は、前記第一圧縮機の始動後所定時間が経過すると、前記第二圧縮機に電力供給を行って、第二目標回転速度で動作するよう前記第二圧縮機を始動させる、請求項1~3のいずれかに記載の冷凍装置。
- 前記第一圧縮機および前記第二圧縮機の両方が停止した状態において、前記第一電力供給部は、前記庫内温度センサの検出結果と前記収納スペースの目標温度との偏差が第二偏差基準値以上となると、前記第一圧縮機に電力供給を行って前記第一圧縮機を始動させ、
前記第二電力供給部は、前記第一圧縮機の始動後所定時間遅延後に、前記第二圧縮機に電力供給を行って前記第二圧縮機を始動させる、請求項1~3のいずれかに記載の冷凍装置。 - 前記第二流体回路温度センサをさらに備え、
前記第一圧縮機および前記第二圧縮機の両方が停止した状態において、前記第一電力供給部は、前記第一圧縮機に電力供給を行って前記第一圧縮機を始動させ、
前記第二電力供給部は、前記第二流体回路温度センサの検出結果が所定温度以下になると、前記第二圧縮機に電力供給を行って前記第二圧縮機を始動させる、請求項1~3のいずれかに記載の冷凍装置。
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