JP2016205643A - Cooling system - Google Patents

Abstract

A cooling device capable of suppressing a rapid increase in discharge pressure immediately after starting a compressor without using a pressure regulating valve. The cooling device includes a compressor that compresses refrigerant, a condenser that condenses the refrigerant, an electronic expansion valve that expands the refrigerant condensed by the condenser, and an electronic expansion valve. By reducing the opening degree of the evaporator 40 that evaporates the expanded refrigerant and the opening degree of the electronic expansion valve 30 at the time of starting the compressor 10 from the reference opening degree that is set during normal operation after the starting of the compressor 10, And a control unit 70 configured to perform control for suppressing the pressure of the refrigerant discharged from the compressor 10. [Selection] Figure 1

Description

  The present invention relates to a cooling device, and more particularly to a cooling device provided with an electronic expansion valve.

  Conventionally, a cooling device capable of forming a refrigeration cycle is known (see, for example, Patent Document 1).

  Patent Document 1 discloses a refrigeration apparatus (cooling apparatus) configured by sequentially connecting a compressor, a condenser, an expansion valve, and an evaporator through a refrigerant pipe. In the refrigeration apparatus described in Patent Document 1, a pressure adjusting valve is provided in a refrigerant pipe connecting the outlet of the evaporator and the inlet of the compressor, and the refrigerant pipe branched from the discharge pipe is operated in the pressure adjusting valve. It communicates with the room. Thereby, the discharge pressure of the compressor is drawn into the working chamber, and the valve body is mechanically operated according to the discharge pressure, so that the refrigerant flow on the low-pressure side is throttled and the suction pressure of the compressor becomes a predetermined value or less. Configured to be maintained. Further, by maintaining the suction pressure below a predetermined value, the discharge pressure of the compressor is prevented from rising excessively.

  Note that the compressor overload operation in which the discharge pressure increases as the suction pressure increases is a transient until the refrigeration cycle is stabilized immediately after the compressor is started, in addition to those caused by thermal load fluctuations during operation of the refrigeration system. It also occurs in situations. That is, when the refrigerant staying in the evaporator or the low-pressure side refrigerant pipe while the compressor is stopped is aspirated suddenly when the compressor is started, the compressor is overloaded. Therefore, in general, by providing a pressure adjustment valve (suction pressure adjustment valve) between the evaporator and the compressor, in addition to the thermal load fluctuation during normal operation, the pressure can be increased even in a transient state immediately after the start of the compressor. The regulating valve prevents the discharge pressure from rising excessively.

JP 2010-25453 A

  However, the refrigeration apparatus described in Patent Document 1 has a problem in that it is necessary to provide a separate pressure regulating valve in order to suppress a rapid increase in discharge pressure immediately after the start of the compressor.

  The present invention has been made in order to solve the above-described problems, and one object of the present invention is to suppress a rapid increase in discharge pressure immediately after starting a compressor without using a pressure regulating valve. It is providing the cooling device which can do.

  In order to achieve the above object, a cooling device according to one aspect of the present invention includes a compressor that compresses a refrigerant, a condenser that condenses the refrigerant, an electronic expansion valve that expands the refrigerant condensed by the condenser, An evaporator that evaporates the refrigerant expanded by the electronic expansion valve, and compression by reducing the opening of the electronic expansion valve when starting the compressor from the reference opening set during normal operation after starting the compressor. And a control unit configured to perform control for suppressing the pressure of the refrigerant discharged from the machine.

  In the cooling device according to one aspect of the present invention, as described above, by reducing the opening of the electronic expansion valve at the time of starting the compressor from the reference opening set during normal operation after starting the compressor, The control part comprised so that the control which suppresses the pressure of the refrigerant | coolant discharged from a compressor may be provided. This makes it possible to adjust the suction / discharge pressure of the compressor at the start-up of the compressor by appropriately using an electronic expansion valve for adjusting the refrigerant flow rate to the evaporator during normal operation. There is no need to provide a separate pressure regulating valve (suction pressure regulating valve) between the compressor. Thereby, it is possible to suppress a rapid increase in the discharge pressure in a transient state immediately after the start of the compressor without using a pressure regulating valve.

  In the cooling device according to the above aspect, preferably, after the compressor is started, the control unit gradually sets the opening of the electronic expansion valve to the reference opening based on the pressure of the refrigerant between the compressor and the expansion valve. It is comprised so that control which increases may be performed. With this configuration, the opening degree of the electronic expansion valve is changed to the opening degree during normal operation while ensuring the transition of the discharge pressure while ensuring rapid stabilization of the refrigeration cycle in the transient state immediately after the compressor is started. Can be restored.

  In the cooling device according to the above aspect, the compressor is preferably configured to be driven via an electromagnetic clutch by a driving force of a drive source installed externally, and between the evaporator and the compressor. The controller further includes an electromagnetic valve provided, and the controller discharges from the compressor by opening and closing the electromagnetic valve and intermittently operating the electromagnetic clutch in addition to controlling the opening of the electronic expansion valve when starting the compressor. It is comprised so that the control which suppresses the pressure of the refrigerant | coolant to be performed may be performed. If comprised in this way, in addition to the quick operation control (opening degree change control) of the electronic expansion valve by the control unit, the opening / closing operation of the electromagnetic valve by the control unit and the intermittent operation of the electromagnetic clutch are combined. The refrigerant flow rate sucked into the compressor immediately after startup can be quickly reduced. As a result, even when the compressor is started under conditions where the operating conditions (ambient temperature and thermal load) of the cooling device are more severe, it is possible to reliably avoid a sudden increase in the discharge pressure immediately after the compressor is started. Thus, the operation of the compressor can be continued.

  In the configuration in which the compressor is driven by the driving force of a drive source installed outside, the control unit preferably opens and closes the electromagnetic valve based on the temperature or pressure of the refrigerant between the compressor and the expansion valve. And it is comprised so that control which transfers to the state which operates a compressor continuously from the state which performs intermittent operation | movement of an electromagnetic clutch may be performed. With this configuration, even when the compressor is started under conditions where the operating conditions (ambient temperature and heat load) of the cooling device are more severe, the discharge pressure immediately increases immediately after the compressor starts. The compressor can be operated continuously after the refrigeration cycle is stabilized while reliably avoiding it, and the evaporator can exhibit the cooling capacity.

  In the cooling device according to the above aspect, preferably, the compressor is configured to be driven via an electromagnetic clutch by a driving force of a drive source installed externally, and the control unit is operating the compressor. When the temperature in the vicinity of the electromagnetic clutch reaches a predetermined upper limit value lower than the electromagnetic clutch protection operating temperature for disconnecting the electromagnetic clutch, the temperature of the refrigerant sucked into the compressor by increasing the opening of the electronic expansion valve It is configured to control to cool the electromagnetic clutch by lowering. With this configuration, the temperature of the electromagnetic clutch reaches a predetermined upper limit value lower than the electromagnetic clutch protection operating temperature by appropriately using the electronic expansion valve for adjusting the refrigerant flow rate to the evaporator during normal operation. When this occurs, the electromagnetic clutch can be cooled. That is, since the electromagnetic clutch can be cooled without disconnecting the electromagnetic clutch and forcibly stopping the compressor, the cooling capacity of the evaporator can be maintained. Therefore, it can be avoided that the cooling temperature of the object to be cooled such as the stored article in the freezer rises due to this influence due to the forced stop of the compressor accompanying the overheating of the electromagnetic clutch.

  In the cooling device according to the above aspect, preferably, the control unit estimates the amount of frost formed on the evaporator and controls the opening degree of the electronic expansion valve based on the estimated amount of frost formed. Thus, a defrosting operation for melting frost adhering to the evaporator is performed. If comprised in this way, while calculating the minimum calorie | heat amount required for melting frost based on the amount of frost formation of the evaporator estimated beforehand when defrost operation is performed, this necessary minimum calorie | heat amount is calculated. Therefore, the refrigerant can be circulated in the evaporator by adjusting the opening of the electronic expansion valve. As a result, the frost attached to the evaporator can be melted in a short time using the minimum amount of heat, so the cooling capacity of the evaporator temporarily decreases during the defrosting operation. It is possible to suppress an increase in the cold temperature of the object to a minimum level.

  ADVANTAGE OF THE INVENTION According to this invention, the cooling device which can suppress the rapid raise of the discharge pressure immediately after starting of a compressor can be provided, without using a pressure regulating valve as mentioned above.

It is the figure which showed the structure of the cooling device by 1st Embodiment of this invention. It is the block diagram which showed the control structure of the cooling device by 1st Embodiment of this invention. It is the figure which showed the opening degree reference table used for the electronic expansion valve by 1st Embodiment of this invention. It is the figure which showed the structure of the cooling device by 2nd Embodiment of this invention. It is a timing chart for demonstrating the operation | movement content at the time of the compressor restart in the cooling device by 2nd Embodiment of this invention. It is the figure which showed the processing flow of the control part at the time of the compressor restart in the cooling device by 2nd Embodiment of this invention. It is the figure which showed the structure of the cooling device by the modification of 2nd Embodiment of this invention. It is the figure which showed the structure of the cooling device by 3rd Embodiment of this invention. It is the figure which showed the structure of the cooling device by 3rd Embodiment of this invention. It is the figure which showed the processing flow of the control part at the time of the defrost operation by 3rd Embodiment of this invention.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings.

[First Embodiment]
(Configuration of cooling device)
With reference to FIGS. 1-3, the cooling device 100 by 1st Embodiment of this invention is demonstrated.

  As shown in FIG. 1, the cooling device 100 according to the first embodiment of the present invention is configured to be able to form a predetermined refrigeration cycle using a refrigerant. Specifically, the cooling device 100 includes a compressor 10, a condenser 20, an electronic expansion valve 30, an evaporator 40, a refrigerant pipe (discharge pipe 1 to suction pipe 5) that sequentially connects them, and a control. Part 70. In addition, the cooling device 100 has a function of maintaining the freezer 105 that stores articles (not shown) at a predetermined temperature. Here, the freezer 105 is a refrigerator-freezer that maintains the inside of the refrigerator at a freezing temperature (for example, about −30 ° C. to about −10 ° C.) or a refrigeration temperature (for example, about −3 ° C. to about 5 ° C.). Means. The freezer 105 is provided with an open / close door (not shown) through which workers can enter and exit.

  The compressor 10 has a role of compressing the sucked refrigerant and discharging it to the discharge pipe 1. The compressor 10 is assembled with an electromagnetic clutch 15 so that the driving force of a driving source 110 such as an engine installed outside is supplied via the electromagnetic clutch 15. The electromagnetic clutch 15 is electrically connected to the control unit 70. Therefore, when an electromagnetic coil (not shown) of the electromagnetic clutch 15 is energized (excited) based on a command from the control unit 70, the clutch mechanism is in a connected state (driving force transmission state), and the compressor 10 is actually driven. (Rotated). Further, when the electromagnetic coil is de-energized (demagnetized), it is in a cut-off state (drive force cut-off state), and the drive force to the compressor 10 is cut off.

  The condenser 20 has a function of cooling a high-temperature (high-pressure) refrigerant that circulates inside using outside air supplied by the outside-air fan 21. The refrigerant condensed (liquefied) in the condenser 20 flows through the liquid pipe 2 and flows into the electronic expansion valve 30. The liquid pipe 2 is provided with a liquid receiver (receiver tank) 22 for temporarily storing the liquefied refrigerant and adjusting the amount of the refrigerant.

  The electronic expansion valve 30 has a role of reducing the pressure of the refrigerant condensed by the condenser 20 and supplying the reduced pressure to the evaporator 40. Further, the flow rate of the refrigerant flowing into the evaporator 40 is adjusted according to the opening degree of the electronic expansion valve 30. The electronic expansion valve 30 is driven to open and close using the driving force of a stepping motor driven by pulse control. Further, the refrigerant decompressed by the electronic expansion valve 30 flows into the evaporator 40 through the refrigerant pipe 3 in a gas-liquid two-phase state.

  The evaporator 40 has a function of evaporating the gas-liquid two-phase refrigerant. The refrigerant evaporates while obtaining latent heat of evaporation in the evaporator 40, and at this time, heat is taken from the air in the freezer 105. Further, in the vicinity of the evaporator 40, an internal fan 41 that circulates air between the freezer 105 and the evaporator 40 is installed. Further, the evaporated refrigerant becomes a gas state containing a large amount of gas phase, and is returned to the compressor 10 through the suction pipe 5. Thus, in the cooling device 100, the refrigerant discharged from the compressor 10 is discharged along the direction of arrow A along the discharge pipe 1, the condenser 20, the liquid pipe 2, the electronic expansion valve 30, the refrigerant pipe 3, and the evaporator 40. And it distribute | circulates in order of the suction pipe 5, and is suck | inhaled by the compressor 10. FIG.

  The discharge pipe 1 is provided with a temperature sensor 81 that detects the temperature of the refrigerant discharged from the compressor 10 and a pressure sensor 85 that detects the pressure of the refrigerant discharged from the compressor 10. A temperature sensor 82 that detects the temperature of the refrigerant flowing out of the evaporator 40 is provided at the outlet of the evaporator 40. In the internal space of the freezer 105, an internal temperature sensor 91 that detects the air temperature in the internal space is provided. An ambient temperature sensor 92 that detects the ambient temperature is provided in the vicinity of the electronic expansion valve 30. Further, the temperature sensor 81, the temperature sensor 82, the pressure sensor 85, the internal temperature sensor 91 and the ambient temperature sensor 92 are electrically connected to the control unit 70.

  As a control configuration of the cooling device 100, as shown in FIG. 2, a ROM 71 and a RAM 72 are provided in addition to a control unit 70 including a CPU. The control unit 70 makes a predetermined determination based on input signals from the temperature sensor 81, the temperature sensor 82, the pressure sensor 85, the internal temperature sensor 91, and the ambient temperature sensor 92, and energizes (excites) / non-energizes the electromagnetic clutch 15. Energization (demagnetization) and the opening degree (increase / decrease) of the electronic expansion valve 30 are appropriately controlled.

  In addition to a control program executed by the control unit 70 and an opening degree table (not shown) used for controlling the electronic expansion valve 30, the ROM 71 includes an opening range of the electronic expansion valve 30 as shown in FIG. The opening degree reference table 75 in which the reference value is set is stored. Here, in the opening degree reference table 75, the electronic expansion valve 30 when the cooling device 100 (see FIG. 1) is operated in a normal state according to a combination of a plurality of internal temperatures and a plurality of ambient temperatures. A reference value of the opening range (number of pulses) is stored. For example, when the internal temperature is −10 ° C. and the ambient temperature is 30 ° C. or higher, fine adjustment control (superheat control) is started from the state where the electronic expansion valve 30 is opened at an opening corresponding to 200 pulses. An opening degree table (not shown) used for controlling the electronic expansion valve 30 corresponds to the degree of superheat of the refrigerant at the outlet of the evaporator 40 calculated from the temperature sensor 82 (see FIG. 1). A change amount (number of pulses) of the opening degree of the electronic expansion valve 30 is defined. The RAM 72 is used as a working memory for temporarily storing control variables when the control program is executed.

  For example, when the internal temperature detected by the internal temperature sensor 91 is higher than the set temperature during operation of the cooling device 100, the compressor 10 is driven by energization of the electromagnetic clutch 15 and the electronic expansion valve 30 is controlled ( The control of the degree of superheat of the refrigerant at the outlet of the evaporator 40) is continued and the inside of the freezer 105 is cooled. When the internal temperature reaches the set temperature, the cooling capacity of the evaporator 40 is adjusted by releasing the energization of the electromagnetic clutch 15 and stopping the compressor 10.

  Here, when the drive source 110 is driven, the cooling device 100 is energized by the electromagnetic clutch 15 based on a command from the control unit 70, so that the compressor 10 is started (restarted) from the previous stopped state. Is done. In addition, when the compressor 10 is started (restarted), the refrigerant accumulated in the evaporator 40 and the suction pipe 5 is sucked into the compressor 10 and discharged to the discharge pipe 1. At this time, a phenomenon occurs in which the pressure of the high-pressure side refrigerant rapidly increases due to the discharge of the low-pressure side refrigerant to the high-pressure side. Then, when the control unit 70 determines that a protection operation is necessary based on the detection result of the pressure sensor 85, it may be assumed that the compressor 10 is forcibly stopped (high-pressure abnormal stop). .

(Control of electronic expansion valve when compressor starts)
Therefore, in the first embodiment, in order to avoid such a phenomenon (high-pressure abnormal stop), the electromagnetic clutch 15 is energized after a predetermined protection time has elapsed from the initial stage of the cooling operation or after the thermo-off during the cooling operation. When the compressor 10 is restarted, control is performed in which the opening of the electronic expansion valve 30 is changed to an initial opening that is reduced by a predetermined amount from the reference opening. For example, when the internal temperature is −10 ° C. and the ambient temperature is 30 ° C. or higher, the reference opening is 200 pulses according to FIG. On the other hand, the initial opening at the time of restart is set to 160 pulses in which the opening is reduced by 20% from the reference opening. As a result, the flow rate of the refrigerant flowing into the evaporator 40 is reduced by the amount that the electronic expansion valve 30 becomes more restrictive than usual. Therefore, the flow rate of the refrigerant sucked into the compressor 10 through the suction pipe 5 is reduced. Therefore, the discharge pressure is also reduced by the amount that the load on the compressor 10 is reduced. It should be noted that the decrease in the opening degree of the electronic expansion valve 30 is preferably adjusted to about 10% or more and about 20% or less of the reference opening degree at that time.

  In the first embodiment, after the compressor 10 is started in the state of the initial opening, the high-pressure side pressure (discharge pressure) detected by the pressure sensor 85 settles below a predetermined value (for example, 2.3 MPa). In the case of (decrease), control is performed to increase the opening degree of the electronic expansion valve 30 by 5% every predetermined time (for example, 2 minutes) and return it to the reference opening degree. In the above example, when the opening degree of the electronic expansion valve 30 is set to 160 pulses when the compressor 10 is started (restarted), it corresponds to 5% of the 200 pulses of the reference opening degree every two minutes. The valve opening is increased by 10 pulses. And it is comprised so that control which returns to 200 pulses of reference | standard opening after 8 minutes may be performed.

  After the opening degree of the electronic expansion valve 30 is returned to the reference opening degree, the superheat degree of the refrigerant at the outlet of the evaporator 40 calculated from the temperature sensor 82 is maintained at a predetermined value as normal superheat degree control. Thus, the opening degree of the electronic expansion valve 30 is finely controlled (flow rate adjustment). Further, when the internal temperature reaches the set temperature, the electromagnetic clutch 15 is de-energized, the compressor 10 is stopped, and the cooling capacity of the evaporator 40 is adjusted. Maintained within temperature range.

  Further, in the cooling device 100, the electromagnetic coil itself is heated by energization of the electromagnetic clutch 15 after the compressor 10 is started. Therefore, the electromagnetic clutch 15 is provided with a protective device (not shown). Thereby, when the temperature of the electromagnetic coil reaches the electromagnetic clutch protection operating temperature set in the protection device, the energization to the electromagnetic coil is forcibly cut off and the electromagnetic coil is cooled. However, in a state where the energization to the electromagnetic coil is interrupted, the electromagnetic clutch 15 is in the driving force interrupted state and the compressor 10 is not driven. For this reason, the freezer 105 is not cooled, and the internal temperature cannot be maintained at the set value.

(Cooling of electromagnetic clutch by controlling electronic expansion valve)
Therefore, in the first embodiment, during operation of the cooling device 100, a predetermined upper limit value (the temperature near the electromagnetic clutch 15 (electromagnetic coil) is lower than the electromagnetic clutch protection operation temperature for disconnecting (disconnecting) the electromagnetic clutch 15 ( For example, when the temperature reaches 30 ° C., control is performed to increase the opening of the electronic expansion valve 30 by a predetermined amount. As a result, a large amount of refrigerant is circulated through the evaporator 40 and refrigerant that does not sufficiently evaporate in the evaporator 40 is circulated to the suction pipe 5 so that the refrigerant is in the liquid phase return state (liquid back state). It is configured to be inhaled. Thus, the compressor 10 is cooled by lowering the temperature of the refrigerant sucked into the compressor 10, and the electromagnetic clutch 15 (electromagnetic coil) is cooled by the cooled compressor 10. . In other words, the electromagnetic coil of the electromagnetic clutch 15 is cooled by the refrigerant sucked into the compressor 10 while the energization of the electromagnetic coil is continued without operating the protection device of the electromagnetic clutch 15. . Therefore, cooling of the freezer 105 is also continued.

  In the first embodiment, control is performed to increase the opening of the electronic expansion valve 30 by a predetermined amount based on the detection result of the temperature sensor 82 that detects the discharge temperature of the compressor 10. That is, the temperature of the electromagnetic clutch 15 is estimated based on the detection result of the temperature sensor 82, and when the estimated temperature of the electromagnetic clutch 15 reaches the upper limit temperature, the opening degree of the electronic expansion valve 30 is increased by a predetermined amount. Control is performed. As a result, even if the compressor 10 is continuously operated under conditions of high ambient temperature (outside air temperature) such as in summer, the compressor 10 is activated when the energized electromagnetic clutch 15 exceeds the electromagnetic clutch protection operating temperature (overheats). Is forcibly stopped so that it becomes impossible to keep the internal temperature at the set value. The cooling device 100 in the first embodiment is configured as described above.

(Effect of 1st Embodiment)
In the first embodiment, the following effects can be obtained.

  In the first embodiment, the opening degree of the electronic expansion valve 30 at the time of starting the compressor 10 is discharged from the compressor 10 by reducing the opening degree of the electronic expansion valve 30 from the reference opening degree set at the time of normal operation after the starting of the compressor 10. The control part 70 which performs the control which suppresses the pressure of the refrigerant | coolant to be provided. As a result, the electronic expansion valve 30 for adjusting the refrigerant flow rate to the evaporator 40 during normal operation can be appropriately used to adjust the suction / discharge pressure of the compressor 10 when the compressor 10 is started. There is no need to provide a separate pressure regulating valve (suction pressure regulating valve) between the evaporator 40 and the compressor 10. Thereby, it is possible to suppress a sudden increase in the discharge pressure in a transient state immediately after the compressor 10 is started without using a pressure regulating valve.

  Moreover, in 1st Embodiment, the refrigerant | coolant flow rate suck | inhaled by the compressor 10 immediately after starting of the compressor 10 is rapidly utilized using the quick operation control (opening degree change control) of the electronic expansion valve 30 by the control part 70. FIG. Therefore, a rapid increase in the discharge pressure can be avoided quickly. As a result, the refrigeration cycle in the transient state immediately after startup can be quickly stabilized.

  In the first embodiment, after the compressor 10 is started, the opening degree of the electronic expansion valve 30 is gradually increased toward the reference opening degree based on the pressure of the refrigerant between the compressor 10 and the electronic expansion valve 30. The control unit 70 is configured to perform control. Thereby, the opening degree of the electronic expansion valve 30 is returned to the opening degree during the normal operation while the transition of the discharge pressure is surely grasped while the refrigeration cycle is quickly stabilized in the transient state immediately after the start of the compressor 10. Can be made.

  In the first embodiment, when the temperature in the vicinity of the electromagnetic clutch 15 reaches a predetermined upper limit value lower than the electromagnetic clutch protection operating temperature for disconnecting the electromagnetic clutch 15 during the operation of the compressor 10, the electronic expansion valve The controller 70 is configured to perform control to cool the electromagnetic clutch 15 by increasing the opening degree of 30 and lowering the temperature of the refrigerant sucked into the compressor 10. As a result, the temperature of the electromagnetic clutch 15 has reached a predetermined upper limit value lower than the electromagnetic clutch protection operating temperature by appropriately using the electronic expansion valve 30 for adjusting the refrigerant flow rate to the evaporator 40 during normal operation. In this case, the electromagnetic clutch 15 can be cooled. That is, since the electromagnetic clutch 15 can be cooled without disconnecting the electromagnetic clutch 15 and forcibly stopping the compressor 10, the cooling capacity of the evaporator 40 can be maintained. Therefore, it can be avoided that the cold temperature of the articles stored in the freezer 105 is increased due to the forced stop of the compressor 10 due to the overheating of the electromagnetic clutch 15.

[Second Embodiment]
The second embodiment will be described with reference to FIGS. In the second embodiment, unlike the first embodiment, after the compressor 10 is stopped as a protective operation after the pressure of the refrigerant on the high-pressure side becomes equal to or higher than a predetermined value during the operation of the cooling device 200, the compressor 10 The control of the electronic expansion valve 30 when restarting will be described. In the figure, components having the same configuration as in the first embodiment are denoted by the same reference numerals.

(Configuration of cooling device)
In the cooling device 200 according to the second embodiment of the present invention, as shown in FIG. 4, an accumulator 45 for preventing liquid back operation is provided between the evaporator 40 and the compressor 10. The evaporator 40 and the accumulator 45 are connected by the refrigerant pipe 4, and the accumulator 45 and the compressor 10 are connected by the suction pipe 5.

  Here, in the second embodiment, the refrigerant pipe 4 is provided with an electromagnetic valve 51 that can switch the flow path between an open state and a closed state based on a command from the control unit 70. During normal operation, the solenoid valve 51 is kept open. A temperature sensor 83 that detects the temperature of the refrigerant flowing into the evaporator 40 is provided in the vicinity of the inlet of the evaporator 40. The solenoid valve 51 and the temperature sensor 83 are electrically connected to the control unit 70.

  During operation of the cooling device 200, the pressure of the high-pressure side refrigerant may exceed a predetermined value due to ambient temperature (outside air temperature) or the like. In this case, the pressure on the high pressure side detected by the pressure sensor 85 becomes equal to or higher than a predetermined value, and it is determined that there is a high pressure abnormality based on a command from the control unit 70 and the compressor 10 is forcibly stopped. When the high pressure detected by the pressure sensor 85 falls below a predetermined value, the compressor 10 is restarted based on a command from the control unit 70.

(Control of the electronic expansion valve when the compressor is restarted)
When the compressor 10 is restarted from a state where the compressor 10 has been forcibly stopped due to a high pressure abnormality, in the second embodiment, as in the first embodiment, the opening degree of the electronic expansion valve 30 is set to the reference opening. The initial opening is reduced by a predetermined amount from the degree. In the cooling device 200, in addition to this control, the electromagnetic clutch 15 is periodically energized and de-energized in a state in which the open / close control is periodically applied to the electromagnetic valve 51 that has been in the open state. The control is repeated so as to be repeated.

  This point will be described in detail. Specifically, as shown in FIG. 5, first, as a premise, it is assumed that the pressure on the high pressure side is equal to or higher than a predetermined value, the electromagnetic clutch 15 is deenergized, and the compressor 10 is forcibly stopped.

  At time t0, the solenoid valve 51 that has been in the open state is switched to the closed state. Thereafter, the electromagnetic clutch 15 is energized at time t1, and after the period L1 has elapsed, the electromagnetic clutch 15 is de-energized at time t2. After the period L3 has elapsed from the time t2, the electromagnetic valve 51 is switched to the open state at the time t3, and after the period L4 has elapsed, the electromagnetic valve 51 is switched to the closed state at the time t4. Thereafter, the electromagnetic clutch 15 is energized again at time t5, and after the period L1 has elapsed, the electromagnetic clutch 15 is de-energized at time t6. After the period L3 has elapsed from time t6, the electromagnetic valve 51 is switched to the open state at the time t7, and after the period L4 has elapsed, the electromagnetic valve 51 is switched to the closed state at the time t8. As described above, in the second embodiment, the electromagnetic valve 51 is energized for a short time to drive the compressor 10 while the electromagnetic valve 51 is closed, and the compressor 10 is stopped (period L2). Is controlled to be opened for a short time (period L4) alternately and periodically. The period L1 is about 1 second and the period L4 is about 4 seconds.

  Thus, the refrigerant in the suction pipe 5 from the electromagnetic valve 51 to the compressor 10 including the accumulator 45 is returned to the compressor 10 and discharged to the high pressure side using the period L1. Further, the refrigerant staying in the evaporator 40 is moved to the suction pipe 5 using the period L4. Then, the solenoid valve 51 is closed again and the compressor 10 is driven, whereby the refrigerant in the suction pipe 5 is returned to the compressor 10. In this way, by returning the refrigerant staying on the low-pressure side to the compressor 10 little by little, even if the compressor 10 is restarted, the pressure on the high-pressure side becomes less than the predetermined value set for the protection operation to work. Continue to maintain the state. Thereby, even when the compressor 10 is restarted, the pressure on the high pressure side detected by the pressure sensor 85 due to the ambient temperature or the like becomes a predetermined value or more in a short time, and the compressor 10 is forcibly forced. It is configured not to repeat the phenomenon of stopping.

  Moreover, in 2nd Embodiment, it is comprised so that it may transfer to the continuous operation from the intermittent operation | movement of the compressor 10 based on the detection result of the temperature sensor 83 which detects the temperature of the refrigerant | coolant which flows into the evaporator 40. FIG. Yes. In this case, as shown in FIG. 5, the temperature of the refrigerant flowing into the evaporator 40 is grasped by the temperature sensor 83 at the time t4 and the time t8 when the electromagnetic valve 51 is closed. That is, when the operation is repeated for a short period of time, the temperature of the refrigerant flowing into the evaporator 40 by the temperature sensor 83 decreases. This is due to the temperature of the refrigerant flowing into the evaporator 40 and the refrigerant on the low pressure side of the compressor 10. Since the pressure has a correlation, it is possible to grasp that the pressure enough to continuously operate the compressor 10 (the refrigerant pressure on the low pressure side) has been reached because the refrigerant temperature has decreased to a predetermined value. is there. Then, when the temperature of the refrigerant detected by the temperature sensor 83 becomes less than a predetermined temperature (for example, 20 ° C.), the control according to the timing chart shown in FIG. It is comprised so that electricity supply may be continued. Thereby, the compressor 10 is also driven continuously.

  Next, a processing flow of the control unit 70 when the compressor 10 is restarted when the cooling operation is performed by the cooling device 200 according to the second embodiment will be described.

  As shown in FIG. 6, first, in step S21, an initial stage in which the opening degree of the electronic expansion valve 30 (see FIG. 4) is reduced by a predetermined amount from the reference opening degree based on a command from the control unit 70 (see FIG. 4). Set to the opening. This is the same as in the first embodiment. In step S22, the electromagnetic valve 51 (see FIG. 4) is closed. In step S23, the outside air fan 21 (see FIG. 4) and the internal fan 41 (see FIG. 4) are driven.

  In step S24, the electromagnetic clutch 15 (see FIG. 4) is energized for the period L1 based on a command from the control unit 70, and the energization of the electromagnetic clutch 15 is stopped after the period L1 has elapsed. In step S25, the electromagnetic valve 51 is opened for the period L4, and the electromagnetic valve 51 is closed after the period L4 has elapsed. In step S26, the control unit 70 determines whether or not the temperature of the refrigerant by the temperature sensor 83 (see FIG. 4) is less than 20 ° C. In step S26, when it is determined by the temperature sensor 83 that the temperature of the refrigerant is not less than 20 ° C., the processes in steps S24 to S26 are repeated. That is, as shown in FIG. 5, the compressor 10 is driven for the period L1 while the electromagnetic valve 51 is closed, and then stopped. After the period L3, the electromagnetic valve 51 is switched to the open state for the period L4 and closed. . Then, after the compressor 10 is stopped for the time L2, the electromagnetic valve 51 is driven again for the period L1 while the electromagnetic valve 51 is closed. The opening / closing operation of the electromagnetic valve 51 and the intermittent operation of the electromagnetic clutch 15 (compressor 10) are repeated until the temperature of the refrigerant becomes less than 20 ° C.

  If it is determined in step S26 that the temperature of the refrigerant by the temperature sensor 83 is less than 20 ° C., the electromagnetic valve 51 is opened in step S27. In step S28, the electromagnetic clutch 15 is energized continuously. Thereby, the compressor 10 (refer FIG. 4) is driven continuously. In step S29, the opening degree of the electronic expansion valve 30 is returned to the normal reference opening degree from the state where the opening degree of the electronic expansion valve 30 has been set to the initial opening degree based on the command of the control unit 70. Thereby, this control flow is complete | finished.

  Thus, in 2nd Embodiment, the operation control for restart after the discharge pressure becomes high too much and the compressor 10 stops (high-pressure abnormal stop) is performed. Further, when the compressor 10 is restarted, the refrigerant 10 in the evaporator 40 is gradually sucked into the compressor 10 to reduce the accumulated refrigerant, thereby reducing the suction pressure and suppressing the increase in the discharge pressure. Is configured to restart. In addition, the other structure of the cooling device 200 by 2nd Embodiment is the same as that of the said 1st Embodiment.

(Effect of 2nd Embodiment)
In the second embodiment, the following effects can be obtained.

  In the second embodiment, an electromagnetic valve 51 is provided between the evaporator 40 and the compressor 10, and when the compressor 10 is started, in addition to the opening degree control of the electronic expansion valve 30, the opening / closing operation of the electromagnetic valve 51 and the electromagnetic valve The controller 70 is configured to perform control to suppress the pressure of the refrigerant discharged from the compressor 10 by performing the intermittent operation of the clutch 15. Thus, in addition to the rapid opening degree change control of the electronic expansion valve 30 by the control unit 70, the opening / closing operation of the electromagnetic valve 51 and the intermittent operation of the electromagnetic clutch 15 by the control unit 70 are combined, and immediately after the start of the compressor 10. In addition, the flow rate of the refrigerant sucked into the compressor 10 can be quickly reduced. Thereby, even when the operating condition (ambient temperature and thermal load) of the cooling device 200 is started under severe conditions, the discharge pressure is surely increased immediately after the compressor 10 is started. The operation of the compressor 10 can be continued while avoiding.

  Moreover, in 2nd Embodiment, based on the temperature of the refrigerant | coolant between the compressor 10 and the electronic expansion valve 30 detected by the temperature sensor 83, the state which performs the opening / closing operation | movement of the electromagnetic valve 51, and the intermittent operation of the electromagnetic clutch 15 Therefore, the control unit 70 is configured to perform control for shifting to a state in which the compressor 10 is continuously operated. As a result, even when the compressor 10 is started under conditions where the operating conditions (ambient temperature and thermal load) of the cooling device 200 are severer, the discharge pressure can be reliably increased immediately after the compressor 10 is started. Thus, after the refrigeration cycle is stabilized, the compressor 10 can be continuously operated to allow the evaporator 40 to exhibit the cooling capacity. The remaining effects of the second embodiment are similar to those of the aforementioned first embodiment.

[Modification of Second Embodiment]
A modification of the second embodiment will be described with reference to FIGS. 6 and 7. In the modification of the second embodiment, unlike the second embodiment, the compressor 10 is restarted based on the detection result of the pressure sensor 86 provided in the suction pipe 5 instead of the temperature sensor 83. explain.

  In the cooling device 250, as shown in FIG. 7, a pressure sensor 86 is provided at the outlet of the evaporator 40. In step S26, the controller 70 determines whether or not the pressure of the refrigerant by the pressure sensor 86 is less than a predetermined value (for example, 1 MPa). In step S26, when it is determined that the pressure of the refrigerant by the pressure sensor 86 is not less than the predetermined value (1 MPa), the processes of steps S24 to S26 are repeated. If it is determined in step S26 that the pressure of the refrigerant by the pressure sensor 86 has become less than a predetermined value (1 MPa), the electromagnetic valve 51 is opened based on a command from the control unit 70 in step S27.

  In the modification of the second embodiment, the opening / closing operation of the electromagnetic valve 51 and the intermittent operation of the electromagnetic clutch 15 are performed based on the refrigerant pressure between the compressor 10 and the electronic expansion valve 30 detected by the pressure sensor 86. The control unit 70 is configured to perform control for shifting from the state to a state in which the compressor 10 is continuously operated. Thereby, the control regarding the restart of the compressor 10 can be performed more correctly, detecting the pressure of the refrigerant | coolant of the low pressure side of the compressor 10 directly. The remaining effects of the modification of the second embodiment are similar to those of the aforementioned first and second embodiments.

[Third Embodiment]
The third embodiment will be described with reference to FIGS. 2 and 8 to 10. In the third embodiment, the control of the electronic expansion valve 30 is applied to the defrosting operation of the evaporator 40 in addition to the control of the electronic expansion valve 30 applied to the suppression of the discharge pressure when the compressor 10 is started. An example will be described. In the figure, components having the same configuration as in the first embodiment are denoted by the same reference numerals.

(Configuration of cooling device)
In the cooling device 300 according to the third embodiment of the present invention, as shown in FIG. 8, the discharge pipe 1 is provided with an electromagnetic valve 52 that can be switched between an open state and a closed state based on a command from the control unit 70. Yes. A refrigerant pipe (hot gas pipe) 6 that connects the discharge pipe 1 and the refrigerant pipe 3 is provided, and the refrigerant pipe 6 is an electromagnetic that can be switched between an open state and a closed state based on a command from the control unit 70. A valve 53 is provided. During normal operation, the solenoid valve 52 is maintained in the open state, and the solenoid valve 53 is maintained in the closed state. Further, the suction pipe 5 is provided with a temperature sensor 84 for detecting the temperature of the refrigerant sucked into the compressor 10 and a pressure sensor 87 for detecting the pressure.

  The cooling device 300 is controlled so that the refrigerant flowing through the evaporator 40 in order to cool the freezer 105 evaporates at a temperature lower than the temperature of the air circulating in the refrigerator. Further, when the circulating air is cooled, moisture (water vapor) contained in the circulating air is also cooled. At this time, the cooled water (water vapor) adheres to the heat transfer surface (fin surface) of the evaporator 40 and freezes (freezes), and gradually adheres to a wide area to generate frost (ice). Moreover, generation | occurrence | production of frost (ice) becomes ventilation resistance (fin clogging), and the heat exchange performance (heat transfer performance) of the evaporator 40 falls remarkably. Therefore, a defrosting operation is performed in which frost and ice adhering to the heat transfer surface (fin surface) of the evaporator 40 are periodically melted.

  In the defrosting operation, as shown in FIG. 9, the solenoid valve 52 is switched to the closed state and the solenoid valve 53 is switched to the open state. While the operation of the outside air fan 21 is continued, the operation of the internal fan 41 is stopped. Then, the high-temperature (high-pressure) refrigerant gas (hot gas) discharged from the compressor 10 flows into the evaporator 40 via the refrigerant pipe 6. Further, the refrigerant in the condenser 20 and the liquid receiver 22 also flows into the evaporator 40 via the electronic expansion valve 30. Frost (ice) adhering to the evaporator 40 when the hot gas from the refrigerant pipe 6 and the gas-liquid two-phase refrigerant that has passed through the electronic expansion valve 30 are circulated in the evaporator 40 in a mixed state. Is melted.

  Here, in 3rd Embodiment, while estimating the frost formation amount of the frost adhering to the evaporator 40, the evaporator 40 is controlled by controlling the opening degree of the electronic expansion valve 30 based on the estimated ice formation amount. The defrosting operation for melting the frost (ice) adhering to is performed. Hereinafter, the processing flow of the control unit 70 when the defrosting operation is performed by the cooling device 300 will be described.

(Calculation processing of the control unit during defrosting operation)
During the operation of the cooling device 300, the defrosting operation is started when the refrigeration cycle state satisfies a predetermined condition. As shown in FIG. 10, first, in step S31, the removal of the opening degree of the electronic expansion valve 30 (see FIG. 8) decreased by a predetermined amount from the reference opening degree based on the command of the control unit 70 (see FIG. 8). It is set to the initial opening during frost operation. Then, the compressor 10 (see FIG. 8) is continuously driven to perform the pump down operation. That is, when the electronic expansion valve 30 is throttled, the refrigerant in the evaporator 40 (see FIG. 8) and the suction pipe 5 (see FIG. 8) is recovered by the compressor 10 and is discharged to the high pressure side (the discharge pipe 1, the condenser 20 and the receiver). It is moved (collected) to the liquid container 22).

  In step S <b> 32, the control unit 70 estimates (estimates) the amount of frost (ice) attached to the evaporator 40. In estimating the amount of frost formation, the number of times the open / close door of the freezer 105 (see FIG. 8) is opened / closed between the end of the previous defrost operation and the start of the current defrost operation, the outside air temperature, the inside temperature, It is estimated based on the cold air speed (wind speed passing through the evaporator 40) and the like.

  In step S33, the necessary heat amount W for melting frost (ice) is calculated based on the estimated amount of frost formation. The required heat amount W is calculated by multiplying the estimated ice amount by the ice melting latent heat. In step S <b> 34, the refrigerant condition (refrigerant temperature and dryness X) at the inlet of the evaporator 40 for obtaining the necessary heat quantity W is calculated by the control unit 70.

  Specifically, based on the temperature of the refrigerant sucked into the compressor 10 by the temperature sensor 84 (see FIG. 8) and the pressure of the refrigerant sucked into the compressor 10 by the pressure sensor 87 (see FIG. 8). The density of the refrigerant sucked in is calculated. Note that a table (not shown) in which refrigerant physical property values are stored is stored in the ROM 71 (see FIG. 2), and the density of the refrigerant sucked into the compressor 10 is acquired by referring to this table. . Then, the refrigerant flow rate G sucked into the compressor 10 is obtained by multiplying the obtained refrigerant density by the cylinder volume (excluded volume) of the compressor 10 and the rotational speed of the compressor 10 (both are known values). Calculated.

  Here, the required heat quantity W is determined by the difference Δh (Δh = h2−h1) between the specific enthalpy h1 of the refrigerant at the inlet of the evaporator 40 and the specific enthalpy h2 of the refrigerant at the outlet of the evaporator 40, and It is equal to the product of the circulating refrigerant flow rate G (W = G × Δh). Since the specific enthalpy h2 is approximately grasped from the refrigerant physical property value at the inlet of the compressor 10, the specific enthalpy h1 of the refrigerant at the inlet of the evaporator 40 is calculated from the relationship of h1 = h2−Δh. And the dryness degree X corresponding to the specific enthalpy h1 of the refrigerant | coolant at the inlet_port | entrance of the evaporator 40 is acquired with reference to the table where the refrigerant | coolant physical property value was memorize | stored. For example, as an example of the calculation condition, when the hot gas passing through the refrigerant pipe 6 is 40 ° C. and the gas-liquid two-phase refrigerant passing through the electronic expansion valve 30 is 0 ° C., the calculation by the control unit 70 in step S34 As a result, when the refrigerant temperature at the inlet of the evaporator 40 (temperature of the gas-liquid two-phase refrigerant flowing through the evaporator 40) is controlled (set) to 10 ° C. with the refrigerant flow rate G, the evaporator 40 If the degree of dryness X of the gas-liquid two-phase refrigerant at the inlet is set to “0.3”, the result is that the necessary heat quantity W corresponding to the difference Δh can be obtained. That is, the calculation result in step S34 is that the required amount of heat W is supplied to the evaporator 40 when a gas-liquid two-phase refrigerant having a dryness of 10 ° C. and 0.3 under the refrigerant flow rate G flows from the inlet of the evaporator 40. This shows that frost attached to the evaporator 40 can be melted.

  In step S35, the opening degree of the electronic expansion valve 30 for realizing the refrigerant condition (refrigerant temperature = 10 ° C. and dryness X = 0.3) at the inlet of the evaporator 40 obtained in step S34 is calculated. Is done. That is, out of the refrigerant flow rate G sucked into the compressor 10, a refrigerant flow rate of 40 ° C. hot gas passing through the refrigerant pipe 6, and a refrigerant flow rate of 0 ° C. gas-liquid two-phase refrigerant passing through the electronic expansion valve 30 The control unit 70 calculates whether the refrigerant conditions at the inlet of the evaporator 40 (refrigerant flow rate G, refrigerant temperature = 10 ° C., and dryness X = 0.3) are satisfied in which ratio is mixed. In determining the opening degree of the electronic expansion valve 30, since it is necessary to consider the influence of the internal temperature and the ambient temperature, the opening degree reference table 75 (see FIG. 3) stored in the ROM 71 (see FIG. 2). Reference). Then, the opening degree of the electronic expansion valve 30 is changed to the opening degree determined in step S35.

  In step S36, as shown in FIG. 9, the open electromagnetic valve 52 is switched to the closed state and the closed electromagnetic valve 53 is switched to the open state. At this time, the operation of the outside air fan 21 is continued, while the operation of the internal fan 41 is stopped. Thereby, the high-temperature (high-pressure) refrigerant gas (hot gas) discharged from the compressor 10 flows into the evaporator 40 via the refrigerant pipe 6. And the opening degree of the electronic expansion valve 30 is finely controlled so that the refrigerant | coolant which distribute | circulates the evaporator 40 maintains about 10 degreeC. During this time, the frost attached to the evaporator 40 is melted.

  Thereafter, in step S <b> 37, the control unit 70 determines whether or not the temperature of the refrigerant at the outlet of the evaporator 40 is higher than 1 ° C. based on the detection result of the temperature sensor 82. When the temperature of the refrigerant at the outlet of the evaporator 40 is 1 ° C. or lower, the process returns to step S36 and the defrosting operation (frost melting) is continued. If it is determined in step S37 that the temperature of the refrigerant at the outlet of the evaporator 40 is higher than 1 ° C., in step S38, the closed electromagnetic valve 52 is switched to the open state, and the open state is set. The electromagnetic valve 53 is switched to the closed state.

  In step S39, the electromagnetic coil of the electromagnetic clutch 15 is controlled to be de-energized (demagnetized), and the compressor 10 is stopped. In step S40, it is determined whether or not a predetermined time (for example, 3 minutes) has elapsed, and this determination is repeated until the predetermined time has elapsed. During this time, the water flowing down (dropped) from the evaporator 40 is almost discharged. When it is determined in step S40 that the predetermined time (3 minutes) has elapsed, in step S41, the electromagnetic coil of the electromagnetic clutch 15 is energized (excited) and the compressor 10 is started (restarted). In step S42, when the normal cooling operation is resumed, the compressor 10 is restarted. Therefore, the opening degree control of the electronic expansion valve 30 described in the first embodiment (the initial value to be reduced below the reference opening degree). Control to change the opening degree) is performed. In addition, the other structure of the cooling device 300 by 3rd Embodiment is the same as that of the said 1st Embodiment.

(Effect of the third embodiment)
In the third embodiment, the following effects can be obtained.

  In the third embodiment, as described above, the amount of frost (ice formation) of frost (ice) adhering to the evaporator 40 is estimated, and the electronic expansion valve 30 is opened based on the estimated amount of frost formation. By controlling the degree, the control unit 70 is configured to perform a defrosting operation for melting frost adhering to the evaporator 40. As a result, the minimum amount of heat necessary for melting the frost based on the amount of icing of the evaporator 40 estimated in advance when the defrosting operation is performed (the inlet of the evaporator 40 under the refrigerant flow rate G). In addition to calculating the temperature and dryness X) of the refrigerant mixed with the hot gas, the degree of opening of the electronic expansion valve 30 is adjusted in order to obtain the necessary minimum amount of heat, and the refrigerant is circulated in the evaporator 40. be able to. As a result, the frost adhering to the evaporator 40 can be melted in a short time using the minimum necessary amount of heat (refrigerant flow rate), so that the cooling capacity of the evaporator 40 temporarily decreases during the defrosting operation. It is possible to suppress a rise in the cold temperature of the articles stored in the freezer 105 due to the above to a minimum level.

  Moreover, in 3rd Embodiment, the control part 70 is comprised so that the opening degree of the electronic expansion valve 30 may be decreased only predetermined amount from the reference opening degree at the time of a defrost operation start. Thereby, at the start of the defrosting operation, the refrigerant in the evaporator 40 and the suction pipe 5 is recovered by the compressor 10 and moved (recovered) to the high pressure side (discharge pipe 1, condenser 20 and liquid receiver 22). Therefore, it is possible to prevent the compressor 10 from being damaged due to the liquid phase return state (liquid back state) refrigerant returned from the evaporator 40 during the subsequent defrosting operation. The remaining effects of the third embodiment are similar to those of the aforementioned first embodiment.

[Modification]
It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is shown not by the description of the above-described embodiment but by the scope of claims for patent, and further includes all modifications (modifications) within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the first to third embodiments, the opening degree of the electronic expansion valve 30 is set to the reference opening degree when the pressure on the high pressure side detected by the pressure sensor 85 drops below a predetermined value after the compressor 10 is started. However, the present invention is not limited to this. For example, after the compressor 10 is started and the electronic expansion valve 30 is made to be squeezed, control for increasing the opening of the electronic expansion valve 30 toward the reference opening is started after a predetermined time has elapsed. May be.

  Moreover, in the said 1st-3rd embodiment, although the reference value (opening degree reference | standard table 75) of the opening degree of the electronic expansion valve 30 was set according to the combination of several internal temperature and several ambient temperature, this book The invention is not limited to this. That is, the opening degree reference table based on ambient environment information such as the internal temperature, the ambient temperature, the temperature of each part of the refrigeration cycle device (cooling device), the outside air temperature, the number of times the door is opened and closed, the wind speed around the refrigeration cycle device, and the solar radiation. May be created.

  In the first to third embodiments, the opening degree of the electronic expansion valve 30 is increased by a predetermined amount when the electromagnetic clutch 15 is cooled. However, the present invention is not limited to this. For example, the electromagnetic clutch 15 (electromagnetic coil) may be cooled by forcibly deenergizing it. Alternatively, the electromagnetic clutch 15 may be forcibly deenergized and the internal fan 41 may be forcibly stopped. Further, when the operation of the compressor 10 is continued (the energization of the electromagnetic clutch 15 is continued), the temperature in the refrigerator kept at a constant temperature (frequency once per hour, etc.) is set. At least one of the electromagnetic clutch 15 and the internal fan 41 may be forcibly stopped for a time that does not affect the time (about 2 minutes). Note that this control may be performed only when the ambient temperature of the electromagnetic clutch 15 exceeds a predetermined upper limit value lower than the electromagnetic clutch protection operating temperature.

  Moreover, in the said 3rd Embodiment, although the control part 70 computed the refrigerant | coolant conditions (refrigerant temperature and dryness X) of the evaporator 40 based on the estimated value of the amount of frost formation, The invention is not limited to this. If the cooling capacity of the cooling device (the size of the evaporator 40) is known, refer to a table (several tables) in which refrigerant conditions at the inlet of the evaporator 40 corresponding to the amount of frost formation are experimentally obtained in advance. The refrigerant conditions (the refrigerant temperature and the dryness) at the inlet of the evaporator 40 may be determined.

  Moreover, in the said 3rd Embodiment, the dryness X at the time of controlling (setting) the temperature of the refrigerant | coolant which distribute | circulates the evaporator 40 to 10 degreeC was calculated, and the opening degree of the electronic expansion valve 30 which satisfied this was determined. Although an example has been shown, the present invention is not limited to this. The temperature at which the frost of the evaporator 40 is melted (the temperature of the refrigerant flowing through the evaporator 40) is set to a temperature other than 10 ° C. (the temperature of the refrigerant flowing through the evaporator 40) according to the operating state of the cooling device (use conditions such as summer or winter and the amount of frost formation). For example, the degree of dryness X for obtaining the necessary heat amount W for melting the frost of the evaporator 40 may be calculated.

  In the first to third embodiments, the example in which the drive source 110 is an engine installed outside is shown, but the present invention is not limited to this. As long as the compressor 10 can be driven at a constant speed, the drive source 110 may be an electric motor (motor) installed outside.

  Moreover, although the said 1st-3rd embodiment showed about the example which applied the "cooling apparatus" of this invention to the freezer 105, this invention is not limited to this. Other than the freezer, for example, for a showcase using an external drive source for a compressor, a commercial refrigerator, an air conditioner (especially an air conditioning system for a facility that requires cooling operation throughout the year such as a computer room), etc. A “cooling device” may be applied. In addition, the present invention may be applied to a refrigerator car having a freezer compartment.

Moreover, although the said 1st-3rd embodiment showed about the example which operates the cooling devices 100-300 using an alternative CFC refrigerant, this invention is not limited to this. The present invention may be applied to a cooling device to which a natural refrigerant such as a carbon dioxide (CO ₂ ) refrigerant is applied.

DESCRIPTION OF SYMBOLS 10 Compressor 20 Condenser 30 Electronic expansion valve 40 Evaporator 51, 52, 53 Solenoid valve 70 Control part 100, 200, 250, 300 Cooling device 105 Freezer

Claims (6)

A compressor for compressing the refrigerant;
A condenser that condenses the refrigerant;
An electronic expansion valve for expanding the refrigerant condensed by the condenser;
An evaporator for evaporating the refrigerant expanded by the electronic expansion valve;
The pressure of the refrigerant discharged from the compressor is suppressed by reducing the opening of the electronic expansion valve at the time of starting the compressor from a reference opening set at the time of normal operation after starting the compressor. And a control unit configured to perform control.   The control unit is configured to gradually increase the opening of the electronic expansion valve toward the reference opening based on a refrigerant pressure between the compressor and the electronic expansion valve after the compressor is started. The cooling device according to claim 1, wherein the cooling device is configured to perform. The compressor is configured to be driven through an electromagnetic clutch by a driving force of an externally installed driving source,
A solenoid valve provided between the evaporator and the compressor;
The controller is configured to perform the opening / closing operation of the electromagnetic valve and the intermittent operation of the electromagnetic clutch, in addition to the opening degree control of the electronic expansion valve, at the time of starting the compressor, thereby discharging the compressor. The cooling device according to claim 1, wherein the cooling device is configured to perform control for suppressing the pressure of the refrigerant.   The controller continuously moves the compressor from a state in which the electromagnetic valve is opened and closed and the electromagnetic clutch is intermittently operated based on the temperature or pressure of the refrigerant between the compressor and the electronic expansion valve. The cooling device according to claim 3, wherein the cooling device is configured to perform control for shifting to a state in which the vehicle is operated. The compressor is configured to be driven through an electromagnetic clutch by a driving force of an externally installed driving source,
The control unit opens the electronic expansion valve when the temperature in the vicinity of the electromagnetic clutch reaches a predetermined upper limit value lower than the electromagnetic clutch protection operating temperature for disconnecting the electromagnetic clutch during operation of the compressor. The control according to any one of claims 1 to 4, wherein the electromagnetic clutch is controlled to be cooled by increasing a degree of cooling and lowering a temperature of a refrigerant sucked into the compressor. Cooling system.   The controller estimates the amount of frost deposited on the evaporator, and controls the opening of the electronic expansion valve based on the estimated amount of frost, whereby the frost deposited on the evaporator. The cooling device according to any one of claims 1 to 5, wherein the cooling device is configured to perform a defrosting operation that melts the water.

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