JPH0236059Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention is a refrigeration system, specifically a compressor, a user-side heat exchanger, a liquid receiver, an expansion mechanism, and a heat source-side heat exchanger that are connected in sequence to perform heating. The present invention relates to a refrigeration system that can perform cycle operation and equalizes high and low pressures when the heating cycle operation is stopped.

(Prior art) The technology described in Publication of Utility Model Publication No. 55-34538 will be briefly explained based on FIG.
In a refrigeration system in which a condenser 50, a liquid receiver 52, an expansion valve 51, an evaporator 54, and an accumulator 53 are connected to form a refrigerant circuit, the gas area of the liquid receiver 52 and the suction of the compressor 55 are connected. A bypass circuit 56 is provided to connect the accumulator 53 provided on the side, and this bypass circuit 56 is equipped with an on-off valve 57.

During operation, the on-off valve 57 installed in the bypass circuit 56 is closed, and the on-off valves 58 and 59 are opened to perform the refrigeration operation, and when the operation is stopped, the on-off valve 57 is closed, and the on-off valves 58 and 59 are opened. Valve 5
7 is closed to perform pump-down operation, and at the same time, the on-off valve 57 is opened to reduce the pressure in the liquid receiver 52 via the bypass circuit 56 and recover the refrigerant.

(Problems to be Solved by the Invention) However, in this conventional system, the gas refrigerant in the liquid receiver 52 is passed through the accumulator 53 during the pump down operation at the time of the stoppage of the operation. There is a problem in that the amount of refrigerant sucked into the evaporator 54 by the compressor 55 decreases by the amount of refrigerant sucked into the compressor 55, and as a result, the pump-down operation time of the compressor 55 becomes longer.

Moreover, especially during heating operation, the outside temperature is low, so in order to evaporate the refrigerant, the evaporation temperature of the refrigerant must be lower than the outside temperature, but the pressure corresponding to this evaporation temperature must be lower than atmospheric pressure. This causes air to enter the low-pressure region of the refrigerant circuit, so there is a limit to how much the evaporation temperature can be lowered due to the design, and therefore the refrigerant in the evaporator 54 is difficult to evaporate. This prolongs the down operation, which is not desirable for the compressor 55.

The purpose of the present invention is to circulate the gas refrigerant in the liquid receiver to the inlet side of the heat exchanger that becomes the evaporator when the heating operation is stopped, and use the gas refrigerant as a heating source to heat the refrigerant in the heat exchanger. By heating and evaporating the refrigerant and performing high-low pressure balancing, the liquid refrigerant in the low-pressure side circuit can be quickly removed when the heating operation is stopped.

(Means for solving the problem) The configuration of the present invention will be explained based on Fig. 1.
A refrigeration system in which a compressor 7, a user-side heat exchanger 1, a liquid receiver 4 (hereinafter referred to as a heating expansion valve) 5, and a heat source-side heat exchanger 2 are sequentially connected to form a refrigerant circuit to perform heating cycle operation. In the device, a pressure equalization circuit 13 is provided between the connection pipe A between the heating expansion valve 5 and the heat source side heat exchanger 2 and the gas region of the liquid receiver 4, while a pressure equalization circuit 13 is provided between the heating expansion valve 5 and the heat source side heat exchanger 2, and the A two-way valve 14 that opens the pressure equalizing circuit 13 when a stop command is issued.
and a control means for continuing the operation of the compressor 7 for a certain period of time after receiving a command to stop the heating cycle operation.

In the case of FIG. 1, a four-way switching valve 8 and a cooling expansion valve 3 are provided in the refrigerant circuit so that not only heating cycle operation but also cooling cycle operation can be performed.

(Function) When the heating cycle operation is stopped, the pressure equalizing circuit 13 is opened simultaneously with the output of the operation stop command, while the compressor 7 is continuously operated for a certain period of time after the command, so that the liquid receiver 4 The high temperature gas refrigerant inside flows from the pressure equalization circuit 13 to the heat source side heat exchanger 2, and during this time, the gas refrigerant flows in a superheated state to the heat source side heat exchanger 2, so that the heat exchanger 2
As a result, when the heating cycle operation is stopped, the liquid refrigerant in the low-pressure side circuit can be heated and evaporated and quickly sucked into the compressor 7. This makes it possible to reliably prevent liquid compression from occurring when restarting cycle operation.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

What is shown in FIG. 1 is a heat pump type refrigeration system that includes a user side heat exchanger 1 consisting of a water heat exchanger and a heat source side heat exchanger 2 consisting of an air heat exchanger.

In detail, the use side heat exchanger 1, the cooling expansion valve 3, the liquid receiver 4, the heating expansion valve 5 as a heating expansion mechanism, the heat source side heat exchanger 2, the accumulator 6, the compressors 7 and 4. A path switching valve 8 is connected to form a refrigerant circuit. A fan 21 attached to a fan motor 22 is attached to the heat source side heat exchanger 2.

In this way, the four-way switching valve 8 is switched as shown by the broken line in FIG. 1 to circulate the refrigerant as shown in the broken line for the heating cycle, and the four-way switching valve 8 is switched as shown in the solid line to circulate the refrigerant as shown in the solid line in the heating cycle. It is possible to form a cooling cycle that circulates air.

In addition, 9 and 10 in the figure are check valves, respectively. The accumulator 6 has a cylindrical container 6a internally provided with a short refrigerant inflow pipe 6b and an outflow pipe 6e which is a U-shaped pipe having an oil return hole 6c and a gas suction hole 6d.

Further, the cooling expansion valve 3 and the heating expansion valve 5 each consist of an electric valve that electrically controls the valve opening degree, and are designed to control the degree of superheating of the intake gas in each operation cycle. .
Specifically, a temperature detector 31 and a pressure detector 3 are respectively installed on the outlet side of the user-side heat exchanger 1 during cooling.
2, and a controller 33 that calculates the degree of superheating of the intake gas based on the outputs from the respective detectors 31 and 32 and outputs the calculated degree to the cooling expansion valve 3. Similarly, a temperature detector 61, a pressure detector 62, and a controller 63 are provided corresponding to the heating expansion valve 5.
is provided to control the opening degree of the heating expansion valve 5.

Furthermore, a first pressure equalizing circuit 11 for cooling cycle operation (hereinafter referred to as cooling operation) connecting the gas region of the liquid receiver 4 and the accumulator 6 is provided, and the circuit 11 has a first pressure equalizing circuit 11 that is opened when the cooling operation is stopped. 1 on-off valve 12 is provided.

In the refrigeration system configured as described above, a heating cycle operation ( A second pressure equalizing circuit 13 for heating operation (hereinafter referred to as heating operation) is provided, and a valve device, specifically a second on-off valve 14, is provided in the circuit 13 to open this pressure equalizing circuit 13 when the heating operation is stopped. In addition, a control means is provided for causing the compressor 7 to continue operating for a certain period of time after the output of an operation stop command during heating operation.

The control means will be described in detail in the description of the electric circuit.

Moreover, means for opening the second on-off valve 14 and closing the heating expansion valve 5 at the same time as the output of the heating operation stop command is constituted by an electric circuit as described later.

Thus, when the heating operation is stopped,
Simultaneously with the output of the stop command, the second on-off valve 14 is opened, and the heating expansion valve 5 is closed, while the operation of the compressor 7 is continued for a certain period of time after the output of the command, and the heating expansion valve 5 is closed. The liquid refrigerant is prevented from flowing out to the heat source side heat exchanger 2 side through the valve 5, and the gas refrigerant in the gas region of the liquid receiver 4 is transferred to the second pressure equalizing circuit 13 for heat exchange on the heat source side. The compressor 7 is made to flow through the compressor 2, the four-way selector valve 8, and the accumulator 6, and then the compressor 7 can be stopped.

Although details will be described later, the on-off valve 12 of the first pressure equalizing circuit 11 is fully closed when the heating operation is stopped.

Also, when the cooling operation is stopped, the on-off valve 12 of the first pressure equalizing circuit 11 is opened simultaneously with the output of the stop command, while the compressor 7
The compressor 7 is operated continuously for a certain period of time, and then the compressor 7 is stopped. In this case, the gas refrigerant remaining in the liquid receiver 4 directly flows out from the liquid receiver 4 to the accumulator 3,
Almost no water flows to the user-side heat exchanger 1.

Next, an electric circuit for controlling the operation of the refrigeration system will be schematically explained based on FIG. 2.

The electric circuit shown in FIG. 2 includes a heating/cooling switch SSX and auxiliary relays WX, SX for heating and cooling mainly for switching the four-way switching valve 8 to the heating cycle position and the cooling cycle position. , a heating/cooling switching circuit 15 for switching between heating operation, a temperature adjustment circuit 16 including a thermostat WEX for adjusting the temperature on the heat exchanger 1 side on the user side and a switch SS for starting operation, and an electromagnetic opening/closing circuit for the motor of the compressor 7. a compressor start/stop circuit 17 including a compressor MC; a solenoid relay 20EP1, 20EP2 for each energized opening type on-off valve 12, 14 interposed in the first and second pressure equalizing circuits 11, 13; 1
Equalizing circuit control circuit 1 that controls the opening and closing of 1 and 12
8. Fan 21 attached to the heat source side heat exchanger 2
a fan start/stop circuit 19 including an electromagnetic switch 88FX for the motor 22; each motorized part M of the cooling and heating expansion mechanisms 3 and 5 having a closing coil C1 and an opening coil C2;
2. Expansion valve opening degree control circuit 20 comprising M1 and the respective controllers 33 and 63 for superheat degree control, mainly operation commands for the compressor start/stop circuit 17 and the fan start/stop control circuit 19 It mainly consists of a compressor start/stop command circuit 23 that outputs the following.

In the electric circuit, the temperature adjustment circuit 16
The thermostat WEX is configured to open when the hot water temperature of the user-side heat exchanger 1 reaches or exceeds a set temperature during heating operation, closes when the temperature drops below the set temperature, and operates in the opposite manner during cooling operation. and thus the thermostat
When the WEX is opened, the circuit 16 outputs a command to stop the refrigeration system.

In the above embodiment, the compressor start/stop command circuit 23 includes a timer IT1 that counts a certain period of time (40 seconds) from the issuance of the operation stop command, a time limit b contact IT1-1 of the timer IT1, and the It is equipped with a parallel circuit with a series circuit with an auxiliary relay IT1X that outputs a command to start and stop the compressor 7 and fan 21, and by this circuit, the operation of the compressor 7 is continued for a certain period of time after the command to stop operation is issued. It constitutes a control means.

Next, the operation of the above-mentioned refrigeration system will be explained in Figures 1 and 2.
The operation of the electric circuit shown in the figure will be explained.

First, a case will be described in which the hot water temperature in the user-side heat exchanger 2 is lower than the set temperature during heating operation performed by switching the cooling/heating changeover switch SSX to the heating side.

[] By switching the switch SSX to the heating side, before turning on the operation switch SS,
The heating auxiliary WX is energized, the four-way switching valve 8 is switched to the heating side position (broken line position in Figure 1), and the normally open contact of the expansion valve opening control circuit 20 is turned on.
WX-2 is closed, auxiliary relay 74SX is demagnetized as described later, and normally open contact 74SX-2
is open and the normally closed contact 74SX-1 is closed, so the controller 63 is energized and controls the opening degree of the heating expansion valve 5, while the electric part M2 The cooling expansion valve 3 is held fully open (control state during heating operation), and the normally open contact WX-1 of the pressure equalization opening/closing control circuit 18 is closed. The solenoid relay 20EP2 of the 2 on-off valve 14 is energized,
The second on-off valve 14 is in the open state, and the second pressure equalizing circuit 13 is opened, while the normally open contact
SX-1 is opened, the solenoid relay 20EP1 of the first on-off valve 12 is demagnetized, the first on-off valve 12 is closed, and the first pressure equalizing circuit 11 is closed.

[] When the operation switch SS of the temperature control circuit 16 is closed, the thermostat WEX is closed, so the auxiliary relay is closed.
4X, timer 4XT is energized. As a result, the normally closed contact of the pressure equalization opening/closing control circuit 18
4X-1 is opened, the solenoid relay 20EP2 of the second on-off valve 14 is demagnetized, the on-off valve 14 is closed, the second pressure equalizing circuit 13 is also closed, and the expansion valve opening control is performed. The normally closed contact 4X-2 of the circuit 20 is also opened, but the normally open contact
Since IT1X-4 is open, the auxiliary relay
74SX maintains a demagnetized state, and each expansion valve 3,
5 holds the control state during heating operation.

[] Also, due to the excitation of the timer 4XT,
After 30 seconds, the time-limited operation contact 4XT-1 closes, the auxiliary relay 4XTX is energized, and the normally open contact 4XTX-1 of the compressor start/stop command circuit 23 opens, while the normally closed contact 4XT-1 closes. Contact 4XTX-2 is closed and the auxiliary relay
IT1X is excited. As a result, the normally open contact IT1X-1 is closed, the auxiliary relay IT1X is self-held, and the normally open contact IT1X of the compressor start/stop circuit 17 is closed.
-2 is also closed and the switch MC is energized,
The compressor 7 starts, and the normally open contact IT1X of the fan start/stop circuit 19
-3 is also closed, and the fan 21 of the heat source side heat exchanger 2 is also started, while the normally open contact IT1X-4 of the expansion valve opening control circuit 20 is also closed, but the normally closed contact 4X
-2 is open, so the auxiliary relay
74SX continues the demagnetization state, and each expansion valve 3,
5 is also maintained in the control state during heating operation.

As described above, when the four-way switching valve 8 and the expansion valves 3 and 5 are maintained in the control state during heating operation, and the pressure equalization circuits 11 and 13 are closed, the compressor 7 and the fan 21 is driven and heating operation is started.

Next, a case will be described in which the temperature of the hot water in the user-side heat exchanger 1 rises due to the continuation of this heating operation and reaches the set temperature.

[] When the set temperature is reached, the thermostat WEX of the temperature adjustment circuit 16 opens,
The auxiliary relay 4X, timer 4XT, and auxiliary relay 4XTX are each demagnetized and an operation stop command is output. As a result, the normally closed contact 4X-1 of the pressure equalizing circuit opening/closing control circuit 18 is closed, the solenoid relay 20EP2 is energized, the second opening/closing valve 14 is opened, and the second pressure equalizing circuit 13 is opened. At the same time, the normally closed contact 4X-2 of the expansion valve opening degree control circuit 20 is also closed, the auxiliary relay 74SX is energized, each of the normally closed contacts 74SX-1 is opened, and the normally open contact 74SX- 2 closes, the heating expansion valve 5 is fully closed. On the other hand, [] By demagnetizing the auxiliary relay 4XTX, the normally open contact of the compressor start/stop command circuit 23
At the same time as 4XTX-2 opens, the normally closed contact
4XTX-1 is closed, the timer IT1 is excited, and starts counting a certain period of time (40 seconds). During this time, the time-limited operation b contact IT1-1 maintains the closed state, so the auxiliary relay IT1X
continues to be in an excited state. Therefore, the normally open contact IT1X-2 of the compressor start/stop circuit 18 and the normally open contact IT1X-3 of the fan start/stop circuit 19 continue to be closed, and the drive of the compressor 7 and fan 22 is stopped. Continued.

As described above, by closing the heating expansion valve 5, the liquid receiver 4 is transferred from the heat source side heat exchanger 2 to the heat source side heat exchanger 2.
While the supply of liquid refrigerant to the liquid refrigerant is stopped, the liquid refrigerant remaining in the heat source side heat exchanger 2 is evaporated by driving the fan 21, and the liquid refrigerant remaining in the liquid receiver 4 is evaporated.
The high-temperature, high-pressure gas remaining in the gas region of the second
Since it flows in a superheated state to the heat source side heat exchanger 2 via the pressure equalization circuit 13, the evaporation of the liquid refrigerant staying in the heat exchanger 2 is further promoted, and these refrigerants flow out to the compressor 7. It is. As a result, the amount of liquid refrigerant remaining in the low-pressure side circuit during the heating operation is significantly reduced during a certain period of time (40 seconds) during which the compressor 7 continues to operate.

[] However, after the certain period of time has elapsed,
The time-limited operation b of the compressor start/stop command circuit 23
Contact IT1-1 opens, and the auxiliary relay IT1X
is demagnetized. As a result, the normally open contact IT1X-1 for self-holding opens, and the normally open contact IT1X of the compressor start/stop circuit 17 opens.
-2 is opened, the switch MC is demagnetized, the compressor 7 is stopped, and the normally open contact of the fan start/stop circuit 19 is opened.
IT1X-3 is opened, the switch 88FX is demagnetized, and the fan 21 is stopped.

Thus, by stopping the compressor 7, the second
High pressure balancing of the refrigerant circuit is performed via the pressure equalization circuit 13.

As described above, in performing pressure equalization when the heating operation is stopped, the compressor 7 continues to operate for a certain period of time after the operation stop command, and the high-pressure gas refrigerant in the liquid receiver 4 is circulated to the low-pressure side circuit. As a result, the amount of liquid refrigerant remaining in the low-pressure side circuit can be reduced. Therefore, upon restart, a large amount of liquid refrigerant from the accumulator 6 flows into the compressor 7, and the liquid level rises, causing the liquid refrigerant to rise. This prevents the refrigerant from flowing into the outflow pipe 6e from the gas suction hole 6d of the outflow pipe 6e and causing a liquid compression problem.

In this embodiment, even when the cooling operation is stopped, the compressor 7 and the fan 21 continue to operate for a certain period of time (40 seconds) after the operation stop command is issued. The difference is that according to the operation stop command, the first on-off valve 12 is opened and the first pressure equalizing circuit 11 is opened, while the second on-off valve 14 is closed and the second pressure equalizing circuit 13 is closed. This is the point. In this way, the high pressure gas refrigerant in the liquid receiver 4 is transferred to the first pressure equalizing circuit 11.
However, since the ambient temperature is high during cooling operation, a large amount of liquid refrigerant does not remain in the low pressure side circuit, which may cause liquid compression problems when restarting. There isn't.

(Effect of the invention) As described above, the invention provides a pressure equalizing circuit 13 between the connection pipe A between the expansion valve 5 and the heat source side heat exchanger 2 and the gas region of the liquid receiver 4. On the other hand, since the valve device 14 that opens the pressure equalizing circuit 13 when the heating cycle operation is instructed to stop, and the control means that continues the operation of the compressor 7 for a certain period of time after the heating cycle operation stop instruction is provided, the above-mentioned receiver The liquid refrigerant in the heat source side heat exchanger 2 is heated and evaporated by the high-temperature gas refrigerant from the liquid container 4, quickly flows out of the heat exchanger 2, and is sucked into the compressor 7. A large amount of liquid refrigerant does not accumulate in the low-pressure side circuit during heating operation, and the high and low pressures are balanced. As a result, the compressor 7 can be started easily when restarting, and the compressor 7 can This can prevent liquid compression from occurring.

[Brief explanation of the drawing]

FIG. 1 is a refrigerant circuit diagram of an embodiment of the present invention, FIG. 2 is an electric circuit diagram of the same embodiment, and FIG. 3 is a refrigerant circuit diagram of a conventional example. 1... User side heat exchanger, 2... Heat source side heat exchanger, 4... Liquid receiver, 5... Expansion mechanism for heating, 7...
...Compressor, 13...Second pressure equalization circuit, 14...Valve device (second on-off valve).

Claims (1)

[Scope of utility model registration request] In a refrigeration system in which a compressor 7, a utilization side heat exchanger 1, a liquid receiver 4, an expansion mechanism 5, and a heat source side heat exchanger 2 are sequentially connected to perform a heating cycle operation, the expansion mechanism 5 and the heat source A pressure equalizing circuit 13 is provided between the connecting pipe A between the side heat exchanger 2 and the gas region of the liquid receiver 4, and a valve device opens the pressure equalizing circuit 13 when a heating cycle operation stop command is issued. 14
A refrigeration system comprising: and a control means for continuing the operation of the compressor 7 for a certain period of time after receiving a command to stop the heating cycle operation.