JPH0463303B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a refrigeration system equipped with a refrigeration cycle, and relates to an improvement in a system that performs an oil recovery operation for recovering oil in a refrigerant circuit to a compressor.

(Prior Art) Conventionally, as an oil recovery operation control device for a refrigeration system, for example, as disclosed in Japanese Utility Model Publication No. 57-41416, the operating capacity of a compressor is switched between a low capacity side and a high capacity side. Equipped with a changeover switch and a timer for setting the switching time of the changeover switch, when the compressor is operated at low capacity for a certain set time, the changeover switch is switched to the high capacity side to increase the operating capacity of the compressor. There is a known system in which the oil recovery operation of the refrigeration system is performed for a predetermined period of time to increase the flow rate of the refrigerant to recover oil accumulated in the refrigeration circuit.

(Problems to be Solved by the Invention) Incidentally, the set time that determines the cycle of performing the oil recovery operation is usually as long as the actual operating time of the refrigeration system in one day. In other words, the oil recovery operation is an operation to quickly recover oil in the refrigerant circuit, and is performed under special conditions that ignore normal control conditions, so the operation cycle is, for example, the operating time of the compressor. is 8
The longer the time is, the better, such as every hour.

However, when using a timer to integrate such a long set time, if an electronic timer is used, it will be reset when the power is turned off, as shown in the time chart in Figure 8, so it will normally last about 8 hours a day. If the room is only used indoors, there is a possibility that the compressor is not operated for 8 hours and oil recovery operation is not performed for many days. To prevent this, it is possible to install a backup power supply that retains the integrated value of the electronic timer when the main power is stopped, or to use a mechanical timer, but both have the disadvantage of being expensive. .

The present invention has been made in view of the above, and its purpose is to initialize the initial value for starting timer integration to just before the set time of the timer when the main power is turned on. After waiting the minimum amount of time necessary for the equipment to stabilize, the oil recovery operation is immediately performed, and even with an inexpensive structure using an electronic timer, the oil recovery operation can be performed reliably once every day. be.

(Problems to be Solved by the Invention) In order to achieve the above object, as shown in FIG. 13 and an evaporator 6 are sequentially connected to each other in a refrigeration cycle. As an oil recovery operation control device for the refrigeration system, there is provided an operation time integration means 63 that integrates the operating time of the compressor 1 and resets the integrated value to zero when the main power source of the refrigeration system is stopped; An oil recovery operation control means 65 is provided which performs an oil recovery operation to recover oil in the refrigerant to the compressor 1 when the integrated value of the means 63 reaches a set value, and detects when the main power of the refrigeration system is turned on. Closing time detection means 62 and said closing time detection means 6
Initialization means 66 is provided which receives the signal No. 2 and initializes the initial value for starting the integration of the operation time integration means 63 to a value close to the set value when the main power is turned on.

(Function) With the above configuration, in the present invention, when the operation of the refrigeration equipment is stopped, the integrated value of the operating time integrating means 63 is reset to zero, but when the main power is turned on at the start of operation the next day. This turning-on time is detected by the turning-on detecting means 62, and the initializing means 66 initializes the initial value of the operating time integrating means 63 to a value close to the set value. Therefore, after the start of operation, the accumulated value of the operating time accumulating means 63 reaches the set value immediately, and the oil recovery operation control means 65 starts the oil recovery operation of the refrigeration system. The oil in the refrigerant circuit is recovered,
Accidents such as seizure due to lack of oil in the compressor 1 are effectively prevented.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

Figure 2 shows the refrigerant piping system of a multi-type air conditioner to which the present invention is applied, where A is the outdoor unit and B is the outdoor unit.
-F are indoor units connected in parallel to the outdoor unit A. Inside the outdoor unit A, there is a first compressor 1a whose capacity is adjusted by an inverter 2a whose output frequency is variably switched in 10Hz increments in the range of 30 to 70Hz, and an unloader 2b which operates differentially depending on the pilot pressure. The compressor 1 is configured by connecting in parallel via a check valve 1e a second compressor 1b whose capacity is adjusted in two stages: full load (10%) and unload (50%). , an oil separator 4 that separates oil from the gas discharged from the compressor 1; a four-way switching valve 5 that switches as shown by the solid line in the figure during heating operation and as shown by the broken line in the figure during cooling operation; The outdoor heat exchanger 6 and its fan 6a serve as a condenser during operation and an evaporator during heating operation.
The main equipment includes a subcooling coil 7, an outdoor electric expansion valve 8 that adjusts the refrigerant flow rate during cooling operation and throttles the refrigerant during heating operation, a receiver 9 that stores liquefied refrigerant, and an accumulator 10. Each of the devices 1 to 10 is connected through a refrigerant communication pipe 11 so that refrigerant can flow therein. In addition, the indoor units B to F have the same configuration, and are each equipped with an indoor heat exchanger 12 that serves as an evaporator during cooling operation and a condenser during heating operation, and its fans 12a...
The liquid refrigerant branch pipes 11a of... are each provided with indoor electric expansion valves 13... that adjust the refrigerant flow rate during heating operation and perform a throttling action on the refrigerant during cooling operation,
After merging, it is connected to the outdoor unit A via a manual closing valve 17 and a connecting pipe 11b. Further, TH1... is a room temperature thermostat that detects each indoor temperature, TH2... and TH3... are temperature sensors that detect the refrigerant temperature in the liquid side and gas side piping of the indoor heat exchanger 12..., respectively, and TH4 is a temperature sensor that detects the temperature of the refrigerant in the liquid side and gas side piping of the indoor heat exchanger 12..., respectively. TH5 is a temperature sensor that detects the evaporation temperature in the outdoor heat exchanger 6 (evaporator) during heating operation, and TH6 is a temperature sensor that detects the temperature of the suction gas sucked into the compressor 1. The temperature sensor P1 is a pressure sensor that detects the pressure of discharged gas during heating operation and the pressure of intake gas during cooling operation.

In addition, in FIG. 2, various auxiliary devices are provided in addition to the above-mentioned main devices. 1f is interposed in the bypass circuit 11c of the second compressor 1b, and the second
An unloader solenoid valve that opens when the compressor 1b is stopped and unloaded and closes when fully loaded; 1g is a capillary reach tube; 1h and 1i are oil return pipes 11u from the oil separator 4; The first compressor 1a and the second compressor 1
A capillary reach tube 21 is installed in the branch pipes 11v and 11w that return lubricating oil to control the amount of oil returned;
This is a hot gas electromagnetic valve that opens when the indoor heat exchanger 12 (evaporator) is in a low load state during cooling operation and during defrosting. Further, 11e is a heating overload control bypass circuit, and the bypass circuit 11e includes an auxiliary condenser 22, a first check valve 23, and an indoor heat exchanger 12 (condenser) during heating operation when the load is low. A high-pressure control valve 24 and a second check valve 25, which open when the operation is stopped, are connected in series, and part of them includes a liquid seal prevention bypass circuit 11f for preventing liquid seal when the operation is stopped. It is provided via a valve 27 and a capillary reach tube CP3. Furthermore, 11g is a liquid injector bypass circuit that connects between the liquid refrigerant side pipe of the heating overload bypass circuit 11e and the suction gas pipe of the main pipe, and adjusts the degree of superheat of the suction gas during heating and cooling operation. The liquid injection bypass circuit 11g includes an injection extraction solenoid valve 29 that opens and closes in conjunction with the on/off of the compressor 1, and a solenoid valve 29 that opens and closes in conjunction with the on/off of the compressor 1, and a solenoid valve 29 that responds to the degree of superheat of the intake gas detected by the temperature sensing cylinder TP1. Automatic expansion valve 3 whose opening degree is adjusted by
0 is interposed.

In addition, in FIG. 2, F1 to F6 are liquid purification filters installed in the refrigerant circuit or oil return pipe,
HPS is a high pressure switch for compressor protection, and SP is a service port.

The above-mentioned solenoid valves and sensors are connected to an outdoor control unit 15 (described later) by signal lines along with each main equipment, and the outdoor control unit 15 can send and receive signals to each indoor control unit 16 by connecting wiring. It is connected.

FIG. 3 is an electrical circuit diagram showing the interior of the indoor control unit 16 and the main wiring of each connected device. In Fig. 3, MF is the motor of the indoor fan 12a, which receives single-phase AC power and connects each relay terminal RY ₁₁ to
RY ₁₃ switches between strong and weak winds in descending order of air volume, and only when the heating operation is stopped by a signal from the room temperature thermostat TH1, a light breeze is applied. A pulse motor EV for adjusting the opening degree of the indoor electric expansion valve 13 is connected to the terminal CN of the printed circuit board of the indoor control unit 15, while a room temperature thermostat TH1, a temperature sensor TH2,
TH3 signal is input. Further, each indoor control unit 16 is connected to the outdoor control unit 15 via a signal line so that signals can be sent and received.
Connected to enable input from remote control switch RCS. The indoor control unit 16 has a built-in indoor control device 16a shown by a broken line, and the indoor electric expansion valve 13 or the indoor fan 1
The operation of 2a is controlled.

Next, FIG. 4 is an electric circuit diagram showing the interior of the outdoor control unit 15 disposed on the outdoor unit A side and the wiring relationship of each connected device. In the diagram, MC1 is the frequency conversion circuit of inverter 2
Motor of the first compressor 1a connected to INV, MC
2 is the motor of the second compressor 1b, MF is the motor of the outdoor fan 6a, 52F, 52C1 and 52C2
are electromagnetic contactors that operate the fan motor MF, frequency conversion circuit INV, and motor MC2, and each of the above devices is a fuse box FS, earth leakage breaker.
It is connected to a three-phase AC power source via the BR1, and is also connected to the outdoor control unit 15 via a single-phase AC power source. Next, inside the outdoor control unit 15, the normally open contacts RY1 to RY1 of the electromagnetic relays are
RY7) Connected in parallel to single-phase alternating current,
These are in turn connected to the electromagnetic relay 20 of the four-way switching valve 5.
S, electromagnetic contactor 52C1 of frequency conversion circuit INV,
Electromagnetic contactor 52C2 of second compressor 1b, electromagnetic contactor 52F for outdoor fan, electromagnetic valve 1f for unloader
The room temperature thermostat TH1 and the temperature sensor TH2 are connected in series to the coils of the solenoid relay SVL of the hot gas solenoid valve 21, the solenoid relay SVP of the hot gas solenoid valve 21, and the solenoid relay SVT of the injection solenoid valve 29, and input to the outdoor control unit 15.
It is opened and closed according to the signal of TH6, and the contacts of each of the above-mentioned electromagnetic contactors or electromagnetic relays are opened and closed. In addition, the outdoor electric expansion valve 8 is connected to the terminal CN.
The coil of the pulse motor EV is connected to adjust the opening degree of the EV. In the circuit on the right side of Figure 3, CH1 and CH2 are the first compressor 1a and CH2, respectively.
These are heaters for preventing oil forming of the second compressor 1c, and are connected in series with the electromagnetic contactors 52C1 and 52C2, respectively, so that current flows when the compressors 1a and 1b are stopped. Furthermore, 5
1C2 is motor MC2 overcurrent relay, 49C
1, 49C2 are temperature rise protection switches for the first compressor 1a and second compressor 1b, 63H1,
63H2 is a pressure rise protection switch for the first compressor 1a and second compressor 1b, respectively, and 51F is an overcurrent relay for the fan motor MF, which are connected in series and turn on the electromagnetic relay 30Fx when turned on. , constitutes a protection circuit that turns off the device in the event of a failure. The outdoor control unit 15 incorporates an outdoor control device 15a shown by a broken line, and the outdoor control device 15a receives input from each indoor control unit 16, whose internal wiring is shown in FIG. 3, or from each sensor. The operation of each device is controlled according to the signals received. Its internal configuration is shown in FIG.

In FIG. 5, 60 is an input device for inputting set values of operating conditions of the refrigeration system, 61 is a memory circuit for storing set times, and 62 is for sampling the operating state of the compressor 1 and detecting the turning on of the main power supply. sampling device as means for detecting when inputting; 6
3 is an electronic integration timer as an operation time integration means that integrates the operating time of the compressor 1 in accordance with the signal from the sampling device 62 and is reset when the main power supply is stopped; 64 is a CPU; and 65 is an integrated timer in the refrigeration circuit. This is an operation control device as an oil recovery operation control means that controls the operation of each device. Setting conditions input by the input device 60 by the CPU 64, that is, the setting time of the integration timer 63 (8 hours in this embodiment) that determines the cycle for oil recovery operation, or various conditions for performing oil recovery operation. is controlled so that it is stored in the storage circuit 61 in advance. and,
When the cumulative value of the cumulative timer 63 reaches the set value, the operation control device 65 causes the storage circuit 61 to
During heating operation, the four-way selector valve 5 is switched to the cooling cycle side, the operating capacity of the compressor 1 is maximized, the outdoor electric expansion valve 8 is fully opened, and the outdoor motorized expansion valve 8 is fully opened. The ventilation fan 6a is operated and the opening degree of the indoor electric expansion valve 13 is controlled to a large degree on the wet side.

The procedure of the oil recovery operation performed by the above indoor control device 15a will be explained based on the flowchart of FIG. 6.

In FIG. 6, when the main power of the air conditioner is turned on, the integration timer 63 is activated in step S1.
The initial value for starting the integration is set to 1 from the set time of 8 hours.
Initialize to a short period of time, for example 7 hours, and perform normal operation, and in step S2 compressor 1 is operating.
Wait for YES and activate the integration timer 63. Next, the process proceeds to step S3, where it is determined whether or not defrost operation is being performed, and if NO, indicating that defrost operation is not being performed, the process proceeds to step S4. Then, in step S4, it is determined whether the cumulative value of the cumulative timer 63 has reached 8 hours or not. If NO, the procedures of steps S2 and S3 are repeated, and when the cumulative value has reached 8 hours, the determination is YES.
Then, the process moves to step S5. In step S5, the four-way selector valve 5 is switched to the cooling side to perform oil recovery operation, and the capacity of the compressor 1 is set to the maximum (the first
The compressor 1a is set to 70 Hz, the second compressor 1b is fully loaded), the outdoor blower fan 6a is operated, the outdoor electric expansion valve 8 is fully opened, and the indoor electric expansion valves 13 are set to the open side. (note that the injection solenoid valve 29 and the hot gas solenoid valve 21 are closed). Next, in step S6, it is determined whether or not the heating operation was in progress before this oil recovery operation, and if YES indicates that the oil recovery operation was in the heating operation, the indoor fan 12a that is in operation is stopped in step S7 to blow cold air. prevent it from being blown into the room.
Also, if NO during cooling operation, the indoor fan 1
With 2a running, the process moves to step S8, and in step S8 it is determined whether or not the oil recovery operation has been performed for 3 minutes.If the answer is YES after 3 minutes, the oil recovery operation is ended and normal operation begins. Return to step S2 to perform the following steps. If the determination in step S3 is YES that the defrost operation is being performed, the defrost operation has the same oil recovery effect as the oil recovery operation in steps S5 to S8, so the integration timer 63 is reset in step S9 and the process continues. Return to S2.

In the above flow, step S1
Initialization means 6 that initializes the initial value for starting integration of the integration timer 63 to a value close to the setting when the main power is turned on.
6 are configured.

Therefore, while the air conditioner is stopped after one day's operation, the integrated value of the integrated timer 63 is reset to 0 regardless of the value before the stop. As shown in the time chart in Figure 7, the integration timer 63 starts immediately after the main power is turned on.
Since the initial value of is initialized to 7 hours, when the total operating time of the compressor 1 reaches 1 hour after the main power is turned on and the operating condition becomes stable, the oil recovery operation is performed in step S5. That is, unlike the conventional method using only a timer as shown in Fig. 8, oil recovery operation is performed reliably once a day, and if the oil recovery operation is continued for a long time depending on the user's conditions, the compression Since the oil recovery operation is performed every 8 hours of the total operating time of the machine 1, the oil is discharged from the compressor 1 along with the refrigerant into the refrigerant pipe 11 or into the refrigerant circuit of the indoor heat exchanger 12... or the outdoor heat exchanger 6, etc. Accumulated lubricating oil can be reliably collected into the compressor 1, and accidents such as seizure of the compressor 1 due to oil shortage can be effectively prevented.

In addition, an electronic integration timer can be used as the integration timer, which is cheaper than a mechanical integration timer.
The size is compact and the configuration of the control device is simple. Further, a backup power supply is not required, and the cost is lower than a method in which an electronic integration timer is provided with a backup power supply.

(Effects of the Invention) As explained above, the present invention provides a refrigeration system that performs an oil recovery operation in which oil in the refrigerant circuit is recovered to the compressor when the total operating time of the compressor reaches a set value. When the main power is turned on, the initial value of the adjustment means for accumulating the operating time of the compressor is initialized to a value close to the above set value, so oil recovery operation is performed immediately after turning on the power, ensuring that oil is collected every time. Recovery operation can be performed, and accidents such as seizure due to lack of oil in the compressor can be effectively prevented. Moreover, the cost for this is also low.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention. Figures 2 to 7 show embodiments of the present invention, with Figure 2 being a refrigerant system diagram, Figure 3 being an electric circuit diagram of the outdoor control unit, Figure 4 being an electric circuit diagram of the indoor control unit, and Figure 4 being an electric circuit diagram of the indoor control unit. Figure 5 is a schematic diagram of the internal configuration of the indoor control device, Figure 6 is a flowchart showing the oil recovery operation control procedure, Figure 7 is a time chart of the integration timer, and Figure 8 is a diagram showing the flowchart when using the conventional timer alone. It is a time chart. 1...Compressor, 6...Outdoor heat exchanger (evaporator),
12... Indoor heat exchanger (condenser), 13... Indoor electric expansion valve (pressure reducing mechanism), 62... Sampling device (detection means when turned on), 63... Integration timer (operation time integration means), 65... ...operation control device (oil recovery operation control means), 66... initialization means.

Claims (1)

[Claims] 1. In a refrigeration system equipped with a refrigeration cycle in which a compressor 1 whose operating capacity is variably adjusted, a condenser 12, a pressure reducing mechanism 13, and an evaporator 6 are sequentially connected, the operation time of the compressor 1 is integrated, and An operating time integrating means 63 whose integrated value is reset to zero when the main power supply of the refrigeration equipment is stopped, and when the integrated value of the operating time integrating means 63 reaches a set value, oil in the refrigerant is recovered to the compressor 1. and an oil recovery operation control means 65 that performs an oil recovery operation, and a power-on detection means 62 that detects when the main power of the refrigeration system is turned on.
and initialization means 66 for receiving the signal from the power-on detection means 62 and initializing the initial value for starting the integration of the operation time integration means 63 to a value close to the set value when the main power is turned on. An oil recovery operation control device for a refrigeration system, characterized in that: