JPS622228B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling a refrigeration system used in a cooling system such as a refrigerated case or a refrigerator installed in a store such as a supermarket.
The purpose is to protect the compressor and the products in the refrigerator while saving power in the device.

First, a refrigerant circuit of a refrigeration system installed in a store such as a supermarket will be explained with reference to FIG.

1 is a compressor, 2 is a condenser, 3 is a liquid receiver, 4 _a ,
4 _b and 4 _c are liquid solenoid valves that are in parallel relationship with each other; 5
_a , 5 _b , 5 _c are pressure reducing mechanisms such as expansion valves that are also in parallel relationship, 6 _a , 6 _b , and 6 _c are coolers that are also in parallel relationship, and 7 is a gas-liquid separator. The parts are connected in a ring to form a known refrigeration cycle. A, B, and C are the cooling systems of a freezer/refrigerator case or a large freezer/refrigerator installed in the store, including a liquid solenoid valve, a pressure reducing mechanism, and a cooler 4.
_a , _5a , _6a , _4b , _5b , _6b , _4c , _5c , and _6c are stored, respectively. Reference numerals _8a , _8b , and _8c are internal temperature detection devices (hereinafter referred to as internal thermostats) installed in each of the above-mentioned systems, which detect the internal temperature of each of the above-mentioned systems and take appropriate action according to the detected temperature. Liquid solenoid valve _4a , 4
_b , _4c are opened and closed to control the supply of liquid refrigerant to each cooler _6a , _6b , _6c . 9 is a protection device that detects the pressure or temperature of the refrigerant and stops the operation of the compressor 1 when the pressure or temperature becomes above or below a set value.

In such a refrigeration system, each cooling system A,
The following three controls were considered for the purpose of preventing large temperature changes in the internal temperatures of B and C and for saving power in the apparatus.

(a) A so-called "direct cut" control in which the operation of the compressor 1 is stopped at the same time as all liquid solenoid valves 4 _a , 4 _b , and 4 _c are closed. This control can eliminate the operating time until each liquid electromagnetic valve 4 _a , 4 _b , 4 _c is closed, the protection device 9 is activated, and the operation of the compressor 1 is stopped.

(b) After a certain period of time, the internal temperature of each cooling system A, B, and C gradually rises due to frost formation on the coolers 6 _a , 6 _b , and 6 _c . During this process, the operation of the compressor 1 is forcibly stopped at certain cycle times regardless of the internal thermostats 8 _a , 8 _b , and 8 _c , which is a forced intermittent operation stop control called a "duty cycle." . This control can stop the operation of the compressor 1 while preventing the temperature inside the refrigerator from increasing significantly after cool-down, that is, cooling has started and the temperature inside the refrigerator has reached the set temperature.

(c) Cooling systems A, B, and C during store business hours, that is, during the day.
The internal load of the warehouse includes heat generated by lights, etc., and during non-business hours, that is, at night and on closed days, a control system called ``night setback'' is used to turn off the lights, etc., which are part of the internal load. . This control can reduce the refrigeration load during non-business hours compared to business hours. Therefore,
As shown in FIG. 4, the stop time of the nighttime duty cycle can be made longer than the stop time of the daytime duty cycle.

The above-mentioned controls or a combination thereof are used to save power in the refrigeration system, but the stop time of the duty cycle is variable, and each cooling system A, B,
Because the load conditions of
In addition, new problems have arisen due to power saving, such as frequent starting and stopping of the compressor 1.

The present invention improves these points, and examples thereof will be described below with reference to the refrigerant circuit shown in FIG. 1, the control circuit shown in FIG. 2, and the illumination circuit shown in FIG. 3.

10 is a three-phase power supply, and this power supply line includes a defrosting heater 11 provided in each of the coolers, a contact _16a of a heater electromagnetic contactor to be described later, and a compressor 1.
and a contact _13a of a compressor electromagnetic contactor, which will be described later, are connected. 12 is a power switch for the control circuit, 13 is an electromagnetic contactor for the compressor, 14 is a delay timer, 15 is a defrost timer, 16 is an electromagnetic contactor for the heater, 17 is a daytime duty cycler, and 18 is a nighttime device. Utei Cycler, 19 _A , 19 _B , 19 _C
are first, second, and third auxiliary relays; 20 is a power switch for the lighting circuit; 21 is a fourth auxiliary relay provided in the lighting circuit; 22 is a fluorescent lamp; 23 is a ballast;
24 is a glow lamp. The operating line of the compressor 1 provided with the compressor electromagnetic contactor includes the compressor protection device 9 and the defrost timer reverse contact 1.
5 _b , the second reverse contact 17 _b2 of the daytime duty cycler, the first positive contact 21 of the fourth auxiliary relay
_a1 , the positive contact _14a of the delay timer, and the first positive contact _19Aa1 of the first auxiliary relay are connected in series,
Further, the second reverse contact point 1 of the daytime duty cycler
7 _b2 and the first positive contact 21 _a1 of the fourth auxiliary relay are connected to one of the parallel lines, which has the second reverse contact 18 _b2 of the night duty cycler 18 and the first reverse contact 21 _b1 of the fourth auxiliary relay 21. are connected in series, and the other parallel lines are connected to each cooling system A, B, and C, respectively, to detect the temperature of the product stored in the warehouse or the temperature of a dummy similar to the product, and to detect the temperature of a dummy product similar to the product, and to detect the temperature of a dummy product similar to the product. Override thermostats _25a , _25b , _25c for canceling the utility cycle are connected, and the first positive contact _19Aa1 of the first auxiliary relay _19A is connected.
The first positive contacts 19B _a1 and 19C _a1 of the second and third auxiliary relays 19 _B and 19 _C are connected to each parallel line that shortens the
is connected. The delay timer is connected to a parallel line that short-circuits the compressor electromagnetic contactor 13 to the tangent point 14a of the operating line, and the defrosting tire tangent point _15a is connected in series with the heater electromagnetic contactor 16. . Both duty cyclers are provided with first reverse contacts 17 _b1 and 18 _b1 , respectively, and second positive contacts 21 _a2 of the fourth auxiliary relay 21 are connected to the respective reverse contacts.
The second reverse contacts 21 _b2 are connected in series.
Further, each of the first, second and third auxiliary relays is connected in series to the corresponding internal thermostat 8 _a , 8 _b , 8 _c , and the second positive contact points 19A _a2 , 19B _a2 , 19C _a2 are connected to each cooling system A , B, C are connected in series to liquid solenoid valves 4 _a , 4 _b , 4 _c .

Next, control of the refrigeration system will be explained. Note that when the power switch 20 of the lighting circuit is closed, the fourth auxiliary relay 21 is energized, its first and second positive contacts 21a ₁ and 21a ₂ are open, and the first and second reverse contacts 21 are energized.
b ₁ and 21b ₂ are closed, and daytime duty cycler 17 is activated. Conversely, when the power switch 20 is open, the night duty cycler 18 operates.

When the power switch 12 of the control circuit is turned on, the compressor electromagnetic contactor 13 is energized, and its contact 13 _a
is closed, the compressor 1 is operated, and cooling down of each cooling system A, B, and C is started. Upon completion of the cooldown of each system, the internal thermostat 8
_a , 8 _b , and 8 _c open sequentially and unevenly depending on the load conditions, and the first to third auxiliary relays 19 follow this.
_A , 19 _B , 19 _C are de-energized, and their first and second tangent points 19A _a1 , 19B _a1 , 19C _a1 , 19
A _a2 , 19B _a2 , and 19C _a2 are opened to close the liquid electromagnetic valves 4 _a , 4 _b , and 4 _c , and at the same time, the operation of the compressor 1 is stopped. For example, if the internal temperature of system A rises above the set value after a certain period of time has elapsed since the operation was stopped, internal thermostat 8 _a closes and first auxiliary relay 1
9 _A is excited, and its first and second tangent points 19A _a
1 , 19A _a2 is closed, and at the same time, the liquid electromagnetic valve 4 _a is opened and the delay timer 14 is activated. Several minutes after activation of this delay timer, the tangent contact _14a closes and the compressor 1 is operated again. When the duty cycle time is reached during such operation, for example, the first and second reverse contacts 17b ₁ and 17b ₂ of the daytime duty cycler 17 are opened, and the internal thermostats 8 _a and 8 are opened.
_b , 8 closed at _c , that is, the first to third auxiliary relays 19
First tangent points _{19A a1} , 18B _a of _A , 19 B, 19 _C
1 , 19C The operation of the compressor 1 is stopped regardless of the closed state of _a1 . If, for example, the internal temperature of system A rises above the set value of override thermostat _25a during this stop time, override thermostat _25a is closed, the duty cycle is canceled, and compressor 1 is operated. let Note that if one of the override thermostats 25 _a , 25 _b , and 25 _c continues to be closed within the set time of the duty cycle, the duty cycle is not performed.

According to such control, the internal thermostats 8a, 8b, 8c of the cooling systems A, B, and C with different load conditions are all opened in random order, resulting in a "direct cut" state in which the operation of the compressor 1 is stopped. Immediately after the internal thermostat, for example _8c , which was initially opened, returns to closed, the operation of the compressor 1 is delayed by the delay timer 14, so frequent starting and stopping of the compressor 1 can be prevented. . Further, even when the compressor 1 is stopped by the duty cyclers 17 and 18, the override thermostat _25a , which corresponds to the internal temperature of any one of the cooling systems A, B, and C, is activated. 25
If the temperature rises above the set values of _b and 25 _c , the duty cycle is canceled and the compressor 1 is forced to operate, so the temperature can be controlled according to the products stored in the warehouse, and the temperature of the products can be controlled. Quality deterioration can be prevented.

As described above, the present invention can perform temperature control that protects the compressor and prevents deterioration of the quality of products in the refrigerator while saving power in the device.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant circuit diagram showing an embodiment of the refrigeration system of the present invention, Fig. 2 is a control circuit diagram thereof, Fig. 3 is a lighting circuit diagram thereof, and Fig. 4 is a duty cycle during business hours and non-business hours. FIG. 1...Compressor, _4a , _4b , _4c ...Liquid solenoid valve,
5 _a , 5 _b , 5 _c ... pressure reduction mechanism, 6 _a , 6 _b , 6 _c ...
Cooler, _8a , _8b , _8c ...interior temperature detection device,
14... Delay timer, 17, 18... Duty cycler, 25 _a , 25 _b , 25 _c ... Override thermostat, A, B, C... Cooling system.

Claims (1)

[Scope of Claims] 1. A plurality of cooling systems equipped with a liquid solenoid valve opened and closed by an internal temperature detection device, a pressure reduction mechanism that reduces the pressure of the liquid refrigerant, and a cooler that evaporates the reduced pressure liquid refrigerant are connected to the compressor in parallel. In a refrigeration system that controls the supply of liquid refrigerant to each corresponding cooler by opening and closing each liquid solenoid valve, the operation of the compressor is stopped at the same time as all the liquid solenoid valves are closed, and 1. A method of controlling a refrigeration system, comprising delaying operation of a compressor after at least one liquid electromagnetic valve is opened. 2 A plurality of cooling systems are connected in parallel to the compressor, each equipped with a liquid solenoid valve that is opened and closed by an internal temperature detection device, a pressure reducing mechanism that reduces the pressure of the liquid refrigerant, and a cooler that evaporates the reduced pressure liquid refrigerant. In a refrigeration system that controls the supply of liquid refrigerant to each corresponding cooler by opening and closing liquid solenoid valves, when all liquid solenoid valves are closed, compressor operation is stopped and at least one liquid solenoid valve is closed. After opening, the compressor is operated with a delay, and while the cooling operation of each cooling system is being performed based on the internal temperature detection device, the duty cycler is used to perform the cooling operation at certain cycle times. If the compressor is forcibly stopped and the internal temperature of at least one cooling system rises above the set value of the override thermostat during this operation stop, the override thermostat will stop the duty cycle. A method for controlling a refrigeration system, characterized in that the operation of the compressor is restarted by canceling the stoppage of operation by the cycler, and the operation is performed based on the internal temperature detection device.