JPH0510185Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a refrigeration system suitable for a refrigeration unit or the like for transporting articles by sea or land in a frozen or refrigerated state.

(Prior Art) A system diagram of a conventional refrigeration system of this type is shown in FIG.

The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 enters the condenser 2, where it is condensed and liquefied. This liquid refrigerant is adiabatically expanded by being throttled by an electric motor expansion valve 5 (hereinafter referred to as EEV), and then enters the evaporator 3, where it cools the indoor air sent by the evaporator fan 4. It is evaporated and returned to the compressor 1.

During this period, EEV5 is the temperature of the refrigerant gas at the outlet of the evaporator 3 detected by the temperature sensor 8 and the saturation of the refrigerant corresponding to the temperature of the refrigerant gas at the outlet of the evaporator 3 detected by the pressure sensor 7. The degree of opening is adjusted according to the difference in pressure, and the degree of superheating of the refrigerant at the outlet of the evaporator 3 (the difference between the temperature of the refrigerant and the saturation temperature corresponding to its evaporation pressure, hereinafter referred to as
SH) is always kept constant.

On the other hand, the internal air temperature is detected by the temperature detector 9 and inputted to the controller 10, where the temperature setting device 1
2 is compared with its set temperature set by No.2. Then, when the detected temperature of the air inside the refrigerator is lower than the set temperature, that is, when the cooling load is small, the capacity control operation is started.

During capacity control operation, the opening degree of the electric motor type hot gas control valve 6 (hereinafter referred to as MV) provided in the bypass path 15 is increased by the output from the controller 10. Then, the amount of high-temperature, high-pressure gas refrigerant that enters the evaporator 3 via the bypass path 15 and MV6 increases, so the cooling capacity of the evaporator 3 decreases and the temperature of the air inside the refrigerator increases. On the other hand, when the detected temperature of the air inside the refrigerator is higher than the set temperature, the opening degree of MV6 becomes smaller, and the amount of high-temperature, high-pressure gas refrigerant entering the evaporator 3 decreases, so the cooling capacity of the evaporator 3 decreases. The temperature of the air inside the refrigerator decreases. By repeating the above steps, the temperature of the air inside the refrigerator can be adjusted using the temperature setting device 12.
The set temperature is maintained at the set temperature.

During this capacity control operation, the operation switch 13 is
When set to OFF, the controller 10 outputs EEV5 and
Output a fully close command to MV6 to fully close them,
The refrigerant on the downstream side of EEV5 and MV6 is forcibly fed into condenser 2 by compressor 1. (This operation is called pump-down.) When the refrigerant pressure detected by the pressure sensor 7 drops below a predetermined value due to this pump-down, a command from the controller 10 causes the pump-down to end. , After that, the supply of main power to the refrigeration system is stopped. In addition, 11 is an AC main power supply, and this AC power supply is exchanged to DC in the controller 10, and EEV5 and
Supplied to the stepping motor for driving the MV6.

(Problem to be solved by the invention) This type of transportation refrigeration equipment is frequently cut off from the main power supply during loading and unloading of ships and trailers, and as a result, it undergoes pump-down operation. The main power supply to the refrigeration equipment is immediately stopped, and the refrigeration equipment immediately stops. In addition, the stepping motor that drives EEV5 and MV6 has a characteristic that when the current is cut off, the opening state remains at that point, so the high-pressure liquid refrigerant and high-pressure gas refrigerant in the refrigerant circuit After that, it flows into the evaporator 3. And if left in this state for a while,
Since the high-pressure refrigerant gas also condenses, the inside of the evaporator 3 is filled with refrigerant liquid. Therefore, when the refrigeration system is restarted, refrigerant liquid flows into the compressor 1, causing a liquid compression state and causing damage to the compressor 1.

(Means for solving the problem) The present invention was proposed to solve the above problem, and its gist is that the refrigerant discharged from the compressor is transferred to a condenser, an electric motor The refrigerant gas is circulated through the expansion valve and the evaporator in this order to the compressor, and during capacity control operation, a part of the refrigerant gas discharged from the compressor is passed through a hot gas bypass circuit having an electric motor type hot gas control valve to the evaporator. In a refrigeration system that leads to
It is characterized by providing a control means for guiding the current from the auxiliary battery to the electric motor type expansion valve and the hot gas control valve to fully close them when the current supply from the main power supply is stopped during the capacity control operation. It is in the refrigeration equipment.

(Function) Since the present invention has the above configuration, when the current supply from the main power supply stops during capacity control operation, the electric motor expansion valve and the hot gas The control valve is fully closed.

(Embodiment) An embodiment of the present invention is shown in FIGS. 1 to 3.

A system diagram is shown in FIG. 1, and the auxiliary battery 14
This differs from the conventional one shown in FIG. 4 in that current is supplied from the controller 16 to the controller 16, and corresponding members are given the same reference numerals.

FIG. 2 shows a controller function block diagram, and FIG. 3 shows a control flowchart.

When the operation switch 13 is turned on, the current from the AC main power supply 11 is supplied to the DC conversion means 24 of the controller 16, where it is converted to DC, and then supplied to the control means 23 and the valve drive power supply switching means 25. Ru.
The temperature deviation detection means 20 detects a temperature deviation between the set temperature set by the temperature setting device 12 and the temperature detected by the temperature detector 9. The superheat degree deviation detection means 21 detects the superheat degree deviation between the detected superheat degree SH calculated from the refrigerant temperature detected by the temperature sensor 8 and the refrigerant pressure detected by the pressure sensor 7 and the target superheat degree. The detected temperature deviation and superheat degree deviation are input to the control means 23. If the temperature deviation is within a predetermined range, the control means 23 outputs an operation command to the compressor 1 and the evaporator fan 4, and determines the opening degree of the MV 6 according to the temperature deviation and controls the opening degree according to the superheat degree deviation.
The opening degree of the EEV 5 is determined and an opening degree signal is output to the valve driving means 26. The valve driving means 26 sends the DC power from the DC converting means 24 to the EEV 5 and MV 6, and sets them to a predetermined opening degree. Through this series of operations, the refrigeration system enters cooling capacity control operation, and the MV
6 and EEV5 are adjusted in opening to achieve the set temperature and target degree of superheat.

During the cooling capacity control operation, when the current from the main AC power source 11 is interrupted while the EEV 5 and MV 6 are in a predetermined opening state, the main power source detection means 22 notifies the control means 23 of this fact. The control means 23 stops the compressor 1 and the evaporator fan 4, outputs a switching signal to the valve drive power supply switching means 25, and outputs a fully close signal for EEV5 and MV6 to the valve opening degree driving means 26. Then, the valve drive power source switching means 25 switches the valve drive power source to the auxiliary battery 14, and the valve drive means 26 sends the current from the auxiliary battery 14 to the EEV5 and MV6 to bring them into a fully closed state. Further, the control means 23 is driven by the current from the auxiliary battery 14 when the main AC power source is cut off.

In FIG. 3, when the control starts, it is checked in step whether or not the main power supply has been cut off, and if not, cooling capacity control operation is performed in step; The compressor 1 and the evaporator fan 4 are stopped. Next, in a step, the power source for driving the EEV5 and MV6 is switched to the auxiliary battery 14. Then,
In step it is checked whether EEV5 and MV6 are fully closed, and if not, the process returns to step, but if so, the control ends.

(Effects of the invention) In the present invention, when the current supply from the main power supply stops during capacity control operation, the current from the auxiliary battery is guided to the electric motor expansion valve and the hot gas control valve to fully close them. It is possible to prevent a large amount of liquid refrigerant from accumulating in the evaporator, and as a result, it is possible to prevent the liquid from being compressed when the refrigeration system is restarted, thereby preventing damage to the compressor.

[Brief explanation of the drawing]

1 to 3 show one embodiment of the present invention, in which FIG. 1 is a system diagram, FIG. 2 is a control function block diagram, and FIG. 3 is a control flowchart. FIG. 4 is a system diagram of a conventional refrigeration system. Compressor...1, Condenser...2, Electric motor expansion valve...5, Evaporator...3, Hot gas bypass circuit...15, Electric motor hot gas control valve...
...6, Main power supply...11, Auxiliary battery...14,
Main power supply detection means...22, Valve drive power supply switching means...
...25.

Claims (1)

[Scope of utility model registration request] The refrigerant discharged from the compressor is circulated through the condenser, the electric motor type expansion valve, and the evaporator in this order to the compressor, and during capacity control operation, a part of the refrigerant gas discharged from the compressor is circulated to the electric motor type expansion valve. In a refrigeration system that leads hot gas to the evaporator via a hot gas bypass circuit having a hot gas control valve, an auxiliary battery is used, and when the current supply from the main power supply stops during capacity control operation, the current from the auxiliary battery is transferred to the electric motor. A refrigeration system comprising a control means for guiding an expansion valve and a hot gas control valve to completely close them.