JPH05280817A - Operation control device for multichamber type air conditioner - Google Patents

Abstract

PURPOSE:To prevent a dew formation at a blower by controlling a degree of opening of each of expansion valves. CONSTITUTION:Sensing means 14a to 14d for detecting an over-heating degree of refrigerant within each of indoor devices are provided. There is provided a controlling means for increasing a degree of opening of each of electric expansion valves 7a to 7d corresponding to each of indoor devices in the case that the over-heating degree value exceeds a predetermined value and for repeating its operation until the over-heating degree is lower than the second predetermined value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for a multi-room air conditioner in which a plurality of indoor units are connected to one outdoor unit.

[0002]

2. Description of the Related Art Conventionally, as a control of an air conditioner for multiple rooms, the operating capacity of the compressor is controlled so that the saturation temperature corresponding to the suction pressure is kept constant, and the electric expansion valve corresponding to each indoor unit is opened. It is generally known that the ability is adjusted according to the load of each room by adjusting the degree.

[0003]

However, in the cooling operation in which the individual control is performed as described above, the difference in the refrigerant due to the difference in the shape of the branch pipe and the length of the connecting pipe, and the difference in the type and capacity of the indoor unit, etc. When the refrigerant flow in the indoor unit becomes unbalanced and becomes uneven, and the degree of refrigerant superheat in the indoor unit increases, the amount of refrigerant becomes insufficient and the area near the outlet of the indoor heat exchanger becomes dry. There was a problem that the unreplaced moist air was sucked into the blower and mixed with the heat-exchanged cold air, causing dew condensation on the blower and flying out.

The present invention solves the above-mentioned problems of the prior art, and an object thereof is to prevent dew condensation of the blower during the cooling operation.

[0005]

In order to solve the above-mentioned problems, the present invention relates to a liquid pipe and a gas pipe of an outdoor unit constituted by a compressor, an outdoor heat exchanger, an outdoor fan, a four-way valve, etc., respectively. A branch pipe is provided, an electric expansion valve is provided in each liquid pipe branch pipe, and a refrigerant for each indoor unit is added to the multi-room air conditioner that connects a plurality of indoor units to the branch pipe via a connection pipe. A superheat detection means for detecting the degree of superheat is provided, and when the value of the degree of superheat exceeds a first predetermined value, the opening degree of the electric expansion valve corresponding to the indoor unit is increased by a predetermined value to increase the degree of superheat. Is provided with an opening control means for repeating the above-mentioned operation until becomes smaller than the second predetermined value.

Further, according to the present invention, an upper limit value of the opening of the electric expansion valve is added to the opening control means.

Further, according to the present invention, when the degree of superheat detected by the degree of superheat detection means exceeds a first predetermined value, the opening degree of all the electric expansion valves corresponding to the indoor units other than the indoor unit in operation. Is decreased by a predetermined value, and an opening control means for repeating the operation until the degree of superheat becomes smaller than a second predetermined value is provided.

Further, according to the present invention, a lower limit value of the opening of the electric expansion valve is added to the opening control means.

[0009]

The operation of the above means is as follows.

According to the present invention, when the value of the degree of superheat of the indoor unit exceeds the first predetermined value during the cooling operation, the opening degree of the electric expansion valve corresponding to the indoor unit is increased by the predetermined value to increase the degree of superheat. Is the second
By repeating the above operation until it becomes smaller than the predetermined value, the amount of refrigerant flowing into the indoor unit increases and the degree of superheat decreases, so that heat is constantly exchanged with air even near the indoor heat exchanger outlet in a wet state. Therefore, no condensation occurs on the blower.

Further, according to the present invention, if the expansion valve opening becomes too large, the capacity changes by affecting the amount of refrigerant flowing to other indoor units. Therefore, by setting an upper limit value for the expansion valve opening. , Minimize the effect on other rooms.

Further, according to the present invention, when the degree of superheat of the indoor unit exceeds the first predetermined value, the opening degrees of all the electric expansion valves corresponding to the other indoor units in operation other than the indoor unit are predetermined. By decreasing the value and repeating the above operation until the degree of superheat becomes smaller than the second predetermined value, the amount of refrigerant flowing to another indoor unit decreases, and the indoor unit whose degree of superheat exceeds the predetermined value is reduced by that amount. Since the amount of flowing refrigerant increases, the degree of superheat decreases, and even in the vicinity of the outlet of the indoor heat exchanger, heat is exchanged with air in a constantly moist state, so that no condensation occurs on the blower.

Further, according to the present invention, when the expansion valve opening corresponding to another indoor unit becomes too small, the amount of the refrigerant flowing into those indoor units becomes extremely small and the capacity suddenly changes. By setting a lower limit on the room, the effect on other rooms is minimized.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A multi-room air conditioner according to an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a compressor, 2 is an accumulator, 3 is a four-way valve, 4 is an outdoor heat exchanger, and constitutes a main part of an air conditioner. Reference numeral 5 is a receiver for adjusting the amount of refrigerant, and 6 is a reversible electric expansion valve driven by an electric signal for restricting the refrigerant. Electric expansion valves 7a to 7d are provided on the liquid side, and are connected to indoor heat exchangers 9a to 9d in an indoor unit (not shown) via connection pipes 8a to 8d. 10a to 10d are return connection pipes. Reference numeral 11 denotes a saturation temperature detecting thermistor, which is connected to the accumulator 2 from the receiver 5 via the capillary tube 12.
The temperature corresponding to the low-pressure saturation temperature is detected by returning the temperature to the upstream side of. Reference numeral 13 is an intake temperature detecting thermistor. Further, 14a to 14d are thermistors for detecting the intermediate temperature (equivalent to the evaporation temperature) of the indoor heat exchangers 9a to 9d, and 15a to 1d.
5d is an indoor heat exchanger outlet temperature detection thermistor. Further, 16a to 16d are humidity sensors that detect the relative humidity of indoor air.

Next, the operation will be described. During cooling, the high-pressure gas refrigerant discharged from the compressor 1 passes through the four-way valve 3, is liquefied by the outdoor heat exchanger 4, passes through the receiver 5, and is depressurized by the electric expansion valve 6. After that, the electric expansion valves 7a to 7d
Is split in, enters the indoor heat exchangers 9a to 9d, and evaporates. The evaporated refrigerant returns to the outdoor unit, merges with each other, and returns to the compressor 1 via the four-way valve 3 and the accumulator 2 to form a cycle. At this time, the compressor 1 controls the frequency so as to match the total load in the room, and controls the electric expansion valve 6 so that the difference between the suction temperature detection thermistor 13 and the saturation temperature detection thermistor 11 becomes constant. Further, the electric expansion valves 7a to 7d are controlled to have a constant opening degree by a load inside the room, for example, a difference between a set temperature and a suction temperature. By the control as described above, the balance is lost, the degree of superheat of the indoor unit, that is, the difference between the intermediate temperature and the outlet temperature of the indoor heat exchanger becomes too large, and the relative humidity of the indoor air detected by the humidity sensors 16a to 16d is , 70%, the opening degree of the electric expansion valves 7a to 7d is controlled, and an example thereof will be described with reference to the flowchart of FIG.

Here, the indoor heat exchanger 9a will be described. When the flow starts, the indoor heat exchanger intermediate temperature t1 and the outlet temperature t2 are detected in step 17, and the indoor superheat degree SHa is calculated as the temperature difference between them in step 18. In step 19, it is determined whether the indoor superheat degree SHa is 5 ° C. or higher. If NO, the process returns to step 17,
If YES, in step 20, the opening degree of the electric expansion valve 7a corresponding to the indoor heat exchanger 9a is changed to the opening direction.
Then, again, in steps 21 and 22, t1 and t2 are detected to obtain the indoor superheat degree SHa, and in step 23, SHa is 2
It is determined whether the temperature is ℃ or less, and if YES, the electric expansion valve 7a
The opening degree of is returned to the original opening degree, and the process returns to step 17. NO
In the case of, the process returns to step 20 and the opening degree of the electric expansion valve 7a is further opened. That is, the opening degree of the electric expansion valve 7a is changed until the indoor superheat becomes 5 ° C. or more and 2 ° C. or less. In FIG. 3, the hatched portion is the opening degree change region.

Due to this flow, the indoor superheat degree 7a does not become extremely large, and the vicinity of the outlet of the indoor heat exchanger 7a becomes dry,
Through it, the moist air in the room will not be sucked into the blower and will not condense.

In the second embodiment, an upper limit value is set for the opening degree of the electric expansion valve 7a, and even if the indoor superheat degree SHa is in the opening degree change region, if it reaches the upper limit value, it is more than that value. The opening degree is not changed, and the influence of the other indoor heat exchangers 7b to 7d due to the change in the amount of refrigerant is minimized.

In the third embodiment, when the opening degree change region is entered, the electric expansion valves 7b to 7b of the other operating indoor units.
The change is repeated in the direction to close the opening of d, and as a result, the target amount of the refrigerant flowing to the indoor heat exchanger 7a increases, and the same result as in the first embodiment is obtained.

In the fourth embodiment, the electric expansion valves 7b-7b are used.
A lower limit value is set for the opening degree of d, and even if the indoor superheat degree SHa is in the opening degree change region, if the lower limit value is reached, no further change of the opening degree is made, and the change in the refrigerant amount causes The effect of the other indoor heat exchangers 7b to 7d is minimized.

[0022]

As is apparent from the above description, the present invention has the following advantages.
When the degree of superheat becomes large, it is possible to prevent the dew condensation of the blower by increasing the opening degree of the electric expansion valve to reduce the degree of superheat, and when increasing the opening degree of the electric expansion valve. By setting the upper limit value of the opening degree, it is possible to minimize the influence on other rooms.

Further, according to the present invention, when the superheat degree of a certain indoor unit becomes large, the opening degree of the electric expansion valve corresponding to the other indoor unit is made small to reduce the superheat degree of the indoor unit. The dew condensation of the blower can be prevented, and the lower limit of the opening of the electric expansion valve can be set when the opening of the electric expansion valve is reduced, so that the influence on other rooms can be minimized.

[Brief description of drawings]

FIG. 1 is a refrigerant system diagram of a multi-room air conditioner according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a control operation of the multi-room air conditioner.

FIG. 3 is an explanatory view showing a relationship between a superheat degree and an expansion valve opening degree of the multi-room air conditioner.

[Explanation of symbols]

 1 Compressor 3 Four-way valve 4 Outdoor heat exchanger 5 Receiver 6,7a-7d Electric expansion valve 9a-9d Indoor heat exchanger 14a-14d Thermistor 15a-15d Thermistor 16a-16d Humidity sensor

Claims (4)

[Claims] 1. A liquid pipe and a gas pipe of an outdoor unit composed of a compressor, an outdoor heat exchanger, an outdoor fan, a four-way valve, etc. are provided with parallel branch pipes, and each liquid pipe branch pipe is electrically expanded. A multi-room air conditioner that is provided with a valve and connects a plurality of indoor units to the branch pipe via a connection pipe is provided with superheat detection means for detecting the degree of refrigerant superheat of each indoor unit, When the degree value exceeds a first predetermined value, the opening degree of the electric expansion valve corresponding to the indoor unit is increased by a predetermined value, and the superheat degree is set to the second degree.
An operation control device for a multi-room air conditioner, comprising an opening control means for repeating the above-mentioned operation until the value becomes smaller than a predetermined value. 2. The operation control device according to claim 1, wherein an upper limit value of the opening of the electric expansion valve is added to the opening control means so that the opening does not become larger than the upper limit. 3. When the superheat degree detected by the superheat degree detecting means exceeds a first predetermined value, it corresponds to an operating indoor unit other than the indoor unit whose superheat degree exceeds the first predetermined value. The operation control device according to claim 1, wherein the operation control device is an opening control unit that reduces the opening degrees of all the electric expansion valves to a predetermined value and repeats the operation until the superheat degree becomes smaller than a second predetermined value. 4. The operation control device according to claim 3, wherein a lower limit value of the opening of the electric expansion valve is added to the opening control means, and the opening does not become smaller than the lower limit value.