JPH0439591B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides an antifreeze operation control device for preventing an indoor heat exchanger that acts as an evaporator during cooling operation from freezing due to frost formation in an air conditioner. In particular, the present invention relates to improvements to so-called multi-type air conditioners that are equipped with a plurality of indoor units and can cool multiple rooms at the same time.

(Prior Art) Conventionally, in this type of multi-type air conditioner, when preventing each indoor heat exchanger from freezing due to frost formation during simultaneous cooling operation of multiple rooms, for example, Japanese Patent Application Laid-Open No. 49-38252 What is disclosed in the publication,
By making the capacity of the indoor unit variable and making the capacity of the outdoor unit approximately correspond to the total capacity of the indoor units operating simultaneously during simultaneous cooling operation of multiple rooms, the evaporation temperature can be maintained high and each indoor heat exchanger It is designed to prevent frost and freezing.

(Problem to be solved by the invention) However, the presence or absence of frost on each indoor heat exchanger is not the same in each room, and may vary depending on the unbalance in the installation status of indoor units, the temperature situation in each room, etc. In some cases, frost may form on only one of multiple indoor heat exchangers. For this reason, not only indoor heat exchangers that do not take any anti-freezing measures, but even those that do take the above-mentioned conventional anti-freezing measures have the disadvantage that the preventive measures are not reliable.

Further, when a plurality of indoor units are arranged in a room with a large floor area, only the indoor heat exchanger on the shade side may become frosted due to the degree of sunlight entering the room. In this case, it is conceivable to prevent the flow of refrigerant to the indoor unit on the frosted side and defrost the growing frost by the blowing action of the indoor fan, but this idea does not Regardless of the air conditioning in the same room, cooling operation continues on the one hand, and anti-freezing operation starts on the other, causing an imbalance in air conditioning.

The present invention has been made in view of the above, and its purpose is to have a plurality of indoor units start the antifreeze operation at the same time in a multi-type air conditioner, and to The objective is to effectively enhance the anti-freezing function of the air conditioner as a whole without causing an imbalance in air conditioning within the same room by causing the entire air conditioner to end its anti-freezing operation at the same time.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention, as shown in FIG.
The assumption here is that the antifreeze operation control device is for a multi-type air conditioner in which a plurality of indoor units Y and Y' are connected in parallel. A flow means 17 is provided for allowing and blocking the flow of refrigerant to each of the indoor units Y and Y'. Also, during cooling operation, the indoor heat exchanger 10 of each indoor unit Y, Y'
temperature sensors 35 each detecting the temperature of The temperature of all the indoor heat exchangers 10 exceeds the predetermined value in response to the outputs of the antifreeze operation start control means 45 that controls each of the circulation means 17 to prevent the circulation of the refrigerant, and the temperature sensors 35. The anti-freezing operation termination control means 46 is provided to control each circulation means 17 so as to permit the flow of refrigerant to each indoor unit Y, Y' when the temperature exceeds a set value.

(Function) With the above configuration, in the present invention, at least one
When the temperature of the indoor heat exchanger 10 of the unit falls below a predetermined value, the antifreeze operation start control means 45 controls each distribution means 17 to stop the flow of refrigerant to all indoor units Y and Y'. Antifreeze operation will begin all at once. When the temperature of all the indoor heat exchangers 10 rises and returns to the set value or higher due to this anti-freezing operation, each of the above-mentioned distribution means 17 is controlled in the opposite direction by the anti-freezing operation end control means 46 to prevent freezing. The operation will end all at once.

In this case, all of the indoor units Y, Y' start anti-freezing operation at the same time and end the anti-freezing operation at the same time, so these indoor units Y, Y' can be placed in a given room. Also when preparing
The antifreeze function of the air conditioner as a whole can be enhanced without creating an unbalanced air conditioning system, and its reliability against freezing can be improved.

(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 installed in a high-rise building, etc., where X is an outdoor unit, Y and Y' are each an indoor unit placed in a predetermined room, and Z is a similar refrigerant piping system. An indoor unit placed in another room, the upper indoor outdoor unit The degree of throttling is adjusted by sensing the evaporation temperature of the road switching valve 2, the outdoor heat exchanger 3 having an outdoor blower fan 3a, and the outdoor heat exchanger 3, which acts as an evaporator during heating operation, with a thermosensor tube 4a. A heating expansion valve 4 and an accumulator 5 are built in as main devices, and the devices 1 to 5 are connected to each other through refrigerant piping 8 so that refrigerant can flow therethrough.

On the other hand, the three indoor units Y, Y', and Z have the same configuration, and as shown in FIG. An indoor heat exchanger 10 having a blower fan 10c, a cooling capillary reach tube 11, and a cooling capillary reach tube 1 during cooling operation.
A motor-operated valve 12 that corrects the aperture opening of 1 and functions as a solenoid valve is built-in, and each device 1
0 to 12 are connected to each other through refrigerant pipes 15 . . . so that refrigerant can flow therethrough. The two indoor units Y and Y' arranged in one room have different capacities, with the "parent" indoor unit Y having a larger capacity and the "child" indoor unit Y' having a smaller capacity. When combined into one set, each indoor unit Y,
Y' and Z are connected in parallel to the one outdoor unit X through refrigerant pipes 16, respectively. During cooling operation, the refrigerant from the compressor 1 is circulated as shown by the solid line arrows in FIGS. The amount of heat absorbed from the indoor air by the indoor heat exchanger 10 is radiated to the outside air by the outdoor heat exchanger 3, thereby cooling two rooms at the same time. During heating operation, the refrigerant from the compressor 1 is transferred to the outside air as shown in Fig. 2. By circulating the refrigerant as shown by the broken line arrows in FIG. 3, the refrigerant circulation cycle is reversed to the above cycle, and two rooms are heated at the same time.

Then, the above three indoor units Y, Y', Z
By opening and closing the refrigerant pipes 15 using the electric valves 12, a flow means 17 is configured to permit and block the flow of refrigerant to the indoor units Y, Y', and Z, respectively.

In the outdoor unit , part of the refrigerant discharged from the compressor 1 is immediately unloaded into the compressor 1 to perform capacity control operation, while at the time of switching to the suction side shown by the solid line, the unloading is stopped and the refrigerant is It is designed to operate at full capacity.

Furthermore, 20 is a liquid receiver, and the liquid receiver 20
is a flow path 2 exclusively for heating with a heating expansion valve 4 interposed therein.
Electromagnetic valves 2 are disposed upstream of the heating expansion valve 4 of No. 1, and immediately upstream and downstream of the side liquid receiver 20, respectively, open the heating dedicated flow path 21 only during heating operation.
2 and 23 are arranged, and during heating operation, excess refrigerant generated due to changes in the number of indoor units in operation is stored in the liquid receiver 20, and during cooling operation, the liquid accumulated in the liquid receiver 20 is stored. Refrigerant check valve 2
4 and the capillary tube 25, the pressure is returned to the low pressure side between the four-way switching valve 2 and each of the indoor units Y, Y', and Z. In the outdoor unit It is intended to be returned. In addition, HPS is a high-pressure pressure switch for protecting the compressor 1, PS1 and PS2 are pressure switches that detect the pressure of refrigerant discharged from the compressor 1, and pressure switch PS1 has a pressure value of 19 kg (for example, 19 kg). /
cm ² ) or more, and the pressure switch PS2 turns OFF when the pressure value is set to another predetermined value (for example, 24 kg/cm 2 ) or more.
cm ² ) or more, it turns OFF.

Then, the above three indoor units Y, Y', Z
As shown in FIG. 3, a temperature sensor 35 for detecting the heat exchanger temperature Tc is installed in each of the internal heat exchangers 10 to prevent the built-in indoor heat exchanger 10 from freezing during cooling operation. As shown in FIG. 4, the output signal of each temperature sensor 35 is inputted to a control circuit 40 having a built-in CPU, etc. provided in the same indoor unit Y, Y', Z.
0, the electric valve 12 in the same indoor unit is controlled to open and close. Furthermore, indoor unit Y on the “parent” side,
The Z control circuit 40 can receive various operation control signals from a remote control device 41 having a cooling/heating changeover switch and the like.

Next, the control circuit 4 of indoor unit Y on the “parent” side
The operation of 0 will be explained based on the flowchart of FIG. After starting, in step _S1 , it is determined whether or not the cooling operation is being performed based on the operation status of the cooling/heating selector switch.If YES is the cooling operation, the process proceeds to step _S2 and thereafter, and the indoor heat exchanger 10 is switched on and off. Opening/closing control of the electric valve 12 is started in order to prevent freezing of the electric valve 12.

That is, in step _S2 , it is determined whether the indoor heat exchanger temperature Tc from the temperature sensor 35 in the same indoor unit is below a predetermined value (for example, -7°C) near the temperature just before freezing, and if Tc≦-7°C. In the case of a freezing situation (YES), first count the duration time TM1 of the situation in step _S3 to prevent malfunction, and then proceed to step S3.
In _S4 , it is further determined whether or not this freezing condition duration time TM1 has elapsed for a predetermined time (for example, 10 minutes), and only when YES has elapsed, the freezing prevention flag TBFp on the "parent" side is set to "1" in step _S5 . ” and proceed to step _S13 .

On the other hand, if there is no NO freezing condition with Tc > -7°C in step _S2 , the freezing condition duration time TM1 is reset in step _S6 , and then in step _S7 the indoor heat exchanger temperature Tc is set to the above level. exceeding the specified value,
It is determined whether the temperature is above the set value (for example, 7℃) at which there is no risk of freezing, and if there is no risk of freezing (YES, Tc ≥ 7℃), the temperature is set in step _S8 to prevent malfunctions in the same way as above. The situation duration time TM2 is counted, and in step _S9 it is determined whether or not this safety situation duration time TM2 has elapsed a predetermined time (for example, 10 minutes).If YES, the above-mentioned "safe situation duration time TM2" has elapsed in step _S10 . Set the freeze prevention flag TBFp on the "parent" side to "0". On the other hand, if the safe condition duration time TM2 is determined to be NO after 10 minutes in step _S9 , it is determined in step _S11 whether or not the oil return condition is satisfied, that is, the capacity of the compressor 1 is determined. Whether or not the continuation of the control operation for a predetermined period of time (for example, 3 hours) causes a shortage of lubricating oil in the compressor 1 and requires collection of the lubricating oil is determined based on the condition fulfillment signal for the oil return operation from the outdoor unit X. It is determined based on the presence or absence of reception, and when the oil return condition is satisfied (YES), the compressor ₁ is operated at full capacity.
In the case of NO, the safety situation duration time TM2 is reset in step _S12 , and then the process proceeds to step _S13 , while in the case of NO, where the oil return condition is not satisfied, the process immediately proceeds to step _S13 .

Then, in step _S13 , the above steps _S1 to _S12 are performed.
In the same process as above, the value of the "child" side freeze prevention flag TBFc set in the "child" side control circuit 40 is determined, and in step _S14 , the "parent" side freeze prevention flag TBFp is set to "1". Determine whether or not TBFc
= "1" or TBFp = "1", the freeze prevention flag TBF of the "parent and child" is set to "1" in step _S15 , and as a result, the indoor Each electric expansion valve 12 of units Y, Y' or Z, Z' is operated to close. On the other hand, in step _S14 above, the freeze prevention flag TBF for "parent and child" is set to "0".
This allows the “parent” side and the “child” side to
The side electric expansion valve 12 is opened.

On the other hand, the determination in step _S1 above is during heating operation.
In the case of NO, it is determined that frosting and freezing of the indoor heat exchanger 10 will not occur, and in step _S17 , the antifreeze flags TBFp and TBF of the "parent" and "parent and child" are each set to "0". At the same time, in step _S18 , the freezing situation duration TM1 and the safe situation duration time are determined.
Reset each TM2.

Therefore, the "parent" side control circuit 40 in FIG.
In the operation flow, steps S ₁₃ , S ₁₄ , S ₁₅
As a result, the temperature Tc of at least one indoor heat exchanger 10 is below a predetermined value (for example, -7°C) near the freezing temperature based on the output of each temperature sensor 35 of the "parent and child" indoor units Y, Y'. At times, an antifreeze operation start control means 45 is configured to close each electric valve 12 to prevent the flow of refrigerant to each indoor unit Y, Y'. In addition, in steps S ₁₃ , S ₁₄ , and S ₁₆ , two temperature sensors 35 of the "parent-child" indoor units Y and Y'
When the temperature Tc of the heat exchanger 10 of each indoor unit Y,
An anti-freeze operation termination control means 46 is configured to allow the flow of refrigerant to Y'.

Therefore, in the above embodiment, the anti-freezing operation is performed on the frosted indoor heat exchanger 10, and this anti-freezing operation is performed on the "parent and child" indoor units Y and Y' in the same room. Since they are performed and finished at the same time, the anti-freeze function of the air conditioner as a whole is increased without creating an imbalance in air conditioning within the same room, thereby improving the reliability of the indoor heat exchanger against freezing. be able to.

In the above embodiment, the antifreeze operation was performed simultaneously for the "parent and child" indoor units Y and Y' in the same room, but the antifreeze operation was performed for all other indoor units Y, Y', and Z. It goes without saying that anti-freeze operation can be performed at the same time, but the relationship between multiple indoor units may not be "parent-child" but rather independent of each other, and the number of indoor units installed can be limited to four. The number is not limited to two, or may be four or more.

(Effects of the Invention) As explained above, according to the present invention, in a multi-type air conditioner, at the same time as the antifreeze operation for one indoor unit starts, the antifreeze operation for other indoor units is started. Since all anti-freezing operations are continued until defrosting of all indoor units is completed, the anti-freezing function of the indoor heat exchanger of the air conditioner as a whole during cooling operation can be increased. It is possible to improve the reliability of the indoor heat exchanger against freezing. In particular, when a plurality of indoor units are arranged in the same room, reliability against freezing can be improved without creating an unbalanced air conditioning system.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. Figures 2 to 5 show embodiments of the present invention, with Figure 2 being a refrigerant piping system diagram, Figure 3 being a refrigerant piping system diagram showing the internal configuration of the indoor unit, and Figure 4 being the electrical system provided in the indoor unit. A block diagram of the equipment, FIG. 5 is a flowchart showing the operation of the "parent" side control circuit. X... Outdoor unit, Y, Y', Z... Indoor unit, 10... Indoor heat exchanger, 12... Electric valve, 17... Distribution means, 35... Temperature sensor, 4
0...Control circuit, 45...Anti-freeze operation start control means, 46...Anti-freeze operation end control means.

Claims (1)

[Claims] 1. Multiple indoor units Y connected in parallel to one outdoor unit X and operated at the same time,
This is an antifreeze operation control device for an air conditioner equipped with an air conditioner Y', and a distribution means 17 for allowing and blocking the flow of refrigerant to each of the indoor units Y and Y', respectively.
and a temperature sensor 35 that detects the temperature of the indoor heat exchanger 10 of each indoor unit Y, Y' during cooling operation, and receives the output of each temperature sensor 35 and detects the temperature of at least one indoor heat exchanger 10. anti-freeze operation start control means 45 for controlling each of the circulation means 17 to prevent the flow of refrigerant to each indoor unit Y, Y' when the temperature is below a predetermined value, and receiving the output of each of the temperature sensors 35; All indoor heat exchangers 10
anti-freezing operation termination control means 46 for controlling each distribution means 17 to permit the flow of refrigerant to each indoor unit Y, Y' when the temperature of Freeze prevention operation control device for air conditioners.