JP3284578B2 - Operation control device for multi-room air conditioner - Google Patents

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 a multi-room air conditioner, an operating capacity of a compressor is controlled so that a saturation temperature corresponding to a suction pressure is kept constant, and an electric expansion valve corresponding to each indoor unit is opened. It is generally known that the degree is adjusted so that the capacity corresponding to the load of each room is obtained.

[0003]

However, in the case of the cooling operation in which the individual control is performed as described above, the difference of the refrigerant due to the difference depending on the shape of the branch pipe and the length of the connection pipe, and further, the difference depending on the type and the capacity of the indoor unit, etc. When the refrigerant is superheated in the indoor unit due to poor branch flow and uneven distribution, the refrigerant near the outlet of the indoor heat exchanger is thirsty due to insufficient refrigerant, and depending on the indoor air conditioning conditions, There is a problem in that wet air that is not replaced is sucked into the blower and mixed with the cold air that has been heat-exchanged, causing dew condensation on the blower and popping out.

An object of the present invention is to solve the above-mentioned problems of the conventional example and to prevent dew condensation of a blower during a cooling operation.

[0005]

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

Further, in the present invention, an upper limit 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 exceeds a first predetermined value, the opening degrees of all the electric expansion valves corresponding to the operating indoor units other than the indoor unit are controlled. Is reduced by a predetermined value, and an opening control means for repeating the above operation until the superheat degree becomes smaller than a second predetermined value is provided.

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

[0009]

The operation of the above means is as follows.

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

Further, according to the present invention, if the opening degree of the expansion valve is too large, the capacity is changed by affecting the amount of refrigerant flowing to the other indoor units, so that the upper limit value is provided for the opening degree of the expansion valve. , Minimizing the impact on other rooms.

Further, according to the present invention, when the degree of superheat of the indoor unit exceeds a first predetermined value, the opening degrees of all the electric expansion valves corresponding to the other operating indoor units other than the indoor unit are determined. By reducing the value and repeating the above operation until the superheat degree becomes smaller than the second predetermined value, the amount of refrigerant flowing to the other indoor units is reduced, and accordingly, the indoor unit whose superheat degree exceeds the predetermined value is reduced. As the amount of refrigerant flowing increases, the degree of superheat is reduced, and heat is always exchanged with air in the vicinity of the outlet of the indoor heat exchanger in a wet state, so that dew condensation does not occur in the blower.

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

[0014]

DETAILED 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, and 4 is an outdoor heat exchanger, which constitutes a main part of the air conditioner. Reference numeral 5 denotes a receiver for adjusting the amount of refrigerant, and reference numeral 6 denotes a reversible electric expansion valve driven by an electric signal for performing a throttling operation of the refrigerant. Reference numerals 7a to 7d denote electric expansion valves provided on the liquid side, which are connected to indoor heat exchangers 9a to 9d in indoor units (not shown) via connection pipes of 8a to 8d. 10a to 10d are return connection pipes. Numeral 11 denotes a saturation temperature detecting thermistor, and an accumulator 2 from a receiver 5 via a capillary tube 12.
The temperature corresponding to the low-pressure saturation temperature is detected by returning to the upstream of. Reference numeral 13 denotes a suction temperature detection thermistor. Reference numerals 14a to 14d denote thermistors for detecting intermediate temperatures (corresponding to evaporation temperatures) of the indoor heat exchangers 9a to 9d.
5d is an indoor heat exchanger outlet temperature detection thermistor. Reference numerals 16a to 16d denote humidity sensors for detecting the relative humidity of the 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. Then, the electric expansion valves 7a to 7d
And enters the indoor heat exchangers 9a to 9d and evaporates. The evaporated refrigerant returns to the outdoor unit and joins, and a cycle is formed in which the refrigerant returns to the compressor 1 via the four-way valve 3 and the accumulator 2. At this time, the compressor 1 controls the frequency so as to correspond to 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 so as to have a constant opening degree by a load in the room, for example, a difference between a set temperature and a suction temperature. With the above control, 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 reduced. , 70%, the opening of the electric expansion valves 7a to 7d is controlled, an example of which will be described with reference to the flowchart of FIG.

Here, the indoor heat exchanger 9a will be described. When the flow starts, in Step 17, the indoor heat exchanger intermediate temperature t1 and the outlet temperature t2 are detected, and in Step 18, the indoor superheat degree Sha is calculated as a difference between these temperatures. In step 19, it is determined whether or not the degree of indoor superheating Sha is 5 ° C. or more, and if NO, the process returns to step 17,
In the case of YES, in step 20, the opening of the electric expansion valve 7a corresponding to the indoor heat exchanger 9a is changed to the opening direction.
Thereafter, again, at steps 21 and 22, t1 and t2 are detected to determine the degree of indoor superheat SHa.
° C or less, and if YES, the electric expansion valve 7a
Is returned to the original opening, and the process returns to step S17. NO
In this case, the process returns to step 20, and the opening of the electric expansion valve 7a is further increased. That is, the opening degree of the electric expansion valve 7a is changed until the degree of superheat in the room becomes 5 ° C. or more and 2 ° C. or less. In FIG. 3, a hatched portion is the opening change area.

According to this flow, the degree of indoor superheat 7a does not become extremely large, and the vicinity of the outlet of the indoor heat exchanger 7a becomes dry,
Through this, the humid air in the room is sucked into the blower and no condensation forms.

Further, in the second embodiment, an upper limit value is provided for the opening of the electric expansion valve 7a, and even if the indoor superheat degree Sha is in the opening change region, if the upper limit value is reached, a further upper limit is set. The change in the opening is not performed, 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, if the vehicle enters the opening change range, the electric expansion valves 7b to 7 of the other operating indoor units are operated.
The change is repeated in the direction in which the opening degree of d is closed. As a result, the amount of the refrigerant flowing to the target indoor heat exchanger 7a increases, and the same result as in the first embodiment can be obtained.

In the fourth embodiment, the electric expansion valves 7b-7
A lower limit value is provided for the opening degree of d, and even if the indoor superheat degree SHA is in the opening degree change area, if the lower limit value has been reached, no further opening degree change is performed. The effects of the other indoor heat exchangers 7b to 7d are minimized.

[0022]

According to the present invention, as is apparent from the above description,
When the degree of superheat increases, the degree of superheat can be reduced by increasing the degree of opening of the electric expansion valve to prevent dew condensation of the blower. By setting the upper limit of the opening, the influence on other rooms can be minimized.

Further, according to the present invention, when the degree of superheat of a certain indoor unit increases, the degree of opening of the electric expansion valve corresponding to the other indoor unit is reduced to reduce the degree of superheat of the indoor unit. In addition, the dew condensation of the blower can be prevented, and the influence on the other room can be minimized by setting the lower limit of the opening when the opening of the electric expansion valve is reduced.

[Brief description of the 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 diagram showing a relationship between a degree of superheat and an opening degree of an expansion valve of the multi-room air conditioner.

[Explanation of symbols]

 DESCRIPTION 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)

(57) [Claims] 1. An outdoor unit comprising a compressor, an outdoor heat exchanger, an outdoor fan, a four-way valve, etc., is provided with parallel branch pipes for liquid pipes and gas pipes respectively, and each liquid pipe branch pipe is electrically expanded. A multi-room air conditioner for connecting a plurality of indoor units via a connection pipe to the branch pipe, and a superheat degree detection means for detecting a refrigerant superheat degree of each of the indoor units, When the value of the degree exceeds the first predetermined value, the operation of increasing the opening degree of the electric expansion valve corresponding to the indoor unit by a predetermined value is started, and until the degree of superheat becomes smaller than the second predetermined value. The above operation is repeated , and the superheat degree is smaller than a second predetermined value.
If it becomes too long, change the opening of the electric expansion valve before starting the operation.
An operation control device for a multi-room air conditioner, comprising an opening control means for returning to an opening. 2. An operation for increasing the opening of the electric expansion valve by a predetermined value.
Even if you repeat, the opening will not increase any more
2. An upper limit opening as described above.
Operation control device for multi-room air conditioner . 3. A compressor, an outdoor heat exchanger, an outdoor fan, four-way
Parallel to the liquid pipe and gas pipe of the outdoor unit composed of valves, etc.
A row of branch pipes is provided, and an electric expansion valve is
A plurality of indoor units provided through a connection pipe to the branch pipe.
To the multi-room air conditioner that connects the
Providing superheat detection means for detecting heat, when the superheat detected by the superheat detection means exceeds a first predetermined value,
Except for the indoor units whose degree of superheat exceeds the first predetermined value, the openings of all the electric expansion valves corresponding to the operating indoor units are reduced by a predetermined value, and the degree of superheat is smaller than a second predetermined value. Multi-room air with opening control means that repeats the above operation until
Harmonic machine operation control device. 4. An operation for reducing the opening of the electric expansion valve by a predetermined value.
Even if it repeats, the opening will not decrease any more
4. A lower limit opening as described above.
Operation control device for multi-room air conditioner .