JPH01203856A - Air conditioner - Google Patents

Abstract

PURPOSE:To perform an optimum refrigerant flow rate regulation that meets the cooling capacity demand for the indoor units regardless of the length of the refrigerant piping or head by detecting the degree of overheating of refrigerant in regard to each indoor unit, and, based on the detection results, correcting the opening of the respective refrigerant flow rate regulating valves. CONSTITUTION:The detected temperature from a temperature sensor 48a and the detected temperature from a temperature sensor 47 are taken in to compute their difference DELTAT. This differential temperature DELTAT is an apparent degree of overheating of refrigerant in an indoor unit C1. In the case where the temperature differential DELTAT is in the L zone which is below a set level, a normal opening control is performed without any correction. If the temperature differential DELTAT, however, is in the M zone which is above a set level, the opening correction pi is computed by the following equation, and the opening of a refrigerant flow rate regulating valve 11 is increased by that amount. theta=E.(capacity of indoor unit C1) where K is a constant. In this case, the temperature differential DELTAT is computed at regular intervals, and, if it is still in the M zone, the opening is increased each time. If the temperature differential DELTAT drops to the N zone which is below a set level, the opening existing before the correction is retained. If the temperature differential DELTAT further drops to the L zone, the normal opening control is resumed without any correction.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a multi-type air conditioner comprising an outdoor unit and a plurality of indoor units.

(Prior Art) Generally, as this type of air conditioner, there is a super multi type in which a plurality of branch units are connected to an outdoor unit, and a plurality of indoor units are connected to each of these branch units. - An example is shown in FIG.

In FIG. 4, A is an outdoor unit, B is a branch unit, and CI*C2103 is an indoor unit.

The outdoor unit A includes two variable capacity compressors 1 and 2, which are connected in parallel via check valves 3 and 4, respectively.

A parallel body of compressors 1 and 2, a four-way valve 5, an outdoor heat exchanger 6, a heating expansion valve 7 and a cooling cycle forming check valve 8,
Liquid tank 9, Soda ■, Electric refrigerant flow rate adjustment valve () (Rusmotano (Lube) 11.21.31, Expansion valve for cooling 12, 22゜32 and Check valve for forming heating cycle 13, 23゜33 parallel bodies, indoor heat exchangers 14, 24,
34, Gas side/on-off valve (electromagnetic on-off valve) 15, 25, 35
, header H1 accumulator 10, etc. are sequentially communicated,
It consists of a heat pump type refrigeration cycle.

That is, during cooling operation, the refrigerant flows in the direction of the solid arrow shown in the figure to form a cooling cycle, and the outdoor heat exchanger 6 is converted into a condenser,
The indoor heat exchanger 14, 24, 34 acts as an evaporator.

During heating operation, the four-way valve 5 is switched to flow the refrigerant in the direction of the dashed arrow in the figure to form a heating cycle, with the indoor heat exchanger 14, 24, 34 acting as a condenser and the outdoor heat exchanger 6 acting as an evaporator. let

Branch unit B is indoor unit CI + C2 + C
3, the liquid side refrigerant pipe and the gas side refrigerant pipe communicate with each other, and the refrigerant flow rate adjustment valve 11°21.31, the cooling expansion valve 12.22.32, and the heating cycle forming check valve 13.23. .33, gas side on-off valve 15.25.35.

Note that an oil separator 4 is installed in the refrigerant pipe on the discharge side of the compressor 1.
1 is provided, and an oil bypass pipe 42 is provided from the oil separator 41 to the suction side refrigerant pipe of the compressor 1. Similarly, an oil separator 41 and an oil bypass pipe 4 are installed in the discharge side refrigerant pipe and the suction side refrigerant pipe of the compressor 2.
2 are provided.

The respective reference oil level positions of the cases of the compressors 1 and 2 are communicated with each other through oil equalizing pipes 43, allowing the flow of lubricating oil between the two.

In such an air conditioner, the number and capacity of compressors 1.2 in operation are controlled according to the total required capacity of each indoor unit.

Furthermore, the opening degrees of the refrigerant flow rate regulating valves 11, 21, and 31 are controlled according to the required capacity of the corresponding indoor unit.

(Problem to be solved by the invention) However, branch unit B and indoor unit C1+C2+C
Although the length and head of the refrigerant piping between the indoor units C1, C2, and C3 usually vary depending on the installation situation, the required capacity is determined based on the capacity (horsepower) of the indoor units C1, C2, and C3. (also referred to as )), and does not take into account pressure loss in the refrigerant piping between the branch unit B and the indoor units c11, C2+, and C3.

For this reason, it is difficult to optimally adjust the refrigerant flow rate to match the required capacity of each indoor unit.

For example, if the refrigerant piping is long, the cycle will be too hot.

This invention was made in view of the above circumstances,
The objective is to provide a highly reliable air conditioner that can optimally adjust the refrigerant flow rate to match the required capacity of each indoor unit without being affected by the length or head of the refrigerant piping. There is a particular thing.

[Structure of the Invention] (Means for Solving the Problems) Means for controlling the operating frequency of the compressor according to the total required capacity of each indoor unit, and means provided in each branch unit to control the flow rate of refrigerant to each indoor unit. A refrigerant flow rate adjustment valve to be adjusted, a means for controlling the opening degree of these refrigerant flow rate adjustment valves according to the required capacity of the corresponding indoor unit, a means for detecting the degree of refrigerant superheat of each indoor unit, and a means according to the detection results. means for correcting the opening degree of each refrigerant flow rate regulating valve.

(Function) First, the opening degree of each refrigerant flow rate regulating valve is controlled according to the required capacity of each indoor unit. In this state, the refrigerant superheat degree of each indoor unit is detected, and the opening degree of each refrigerant flow rate adjustment valve is corrected according to these detection results.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. In the drawings, the same parts as in FIG. 4 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

As shown in Fig. 1, in branch unit B, a non-return check is installed from the gathering point of the liquid side refrigerant piping communicating with the indoor unit cll C21C3 to the gathering point of the gas side refrigerant piping communicating with the indoor units CI rC2, C3. A bypass pipe 46 is sequentially passed through a valve 44 and a capillary tube 45.
will be established.

A first temperature sensor 47 is provided on the outlet side of the bypass pipe 46.
Install.

Further, in each of the gas side refrigerant pipes, an on-off valve 15.
25. The second position is located closer to the indoor unit than 35.
Temperature sensors 48a, 48b.

Install 48c.

The other branch unit B also has the same configuration.

The control circuit is shown in FIG.

The outdoor unit A includes an outdoor control section 50.

This outdoor control section 50 is composed of a microcomputer and its peripheral circuits, and has an external inverter circuit 51.
52 is connected. The inverter circuits 51 and 52 rectify the voltage of the AC power supply 53, convert it into an AC voltage of a predetermined frequency by switching according to a command from the outdoor control unit 50, and supply it as driving power to the compressor motors IM and 2M, respectively. It is something to do.

Branching unit B includes a multi-control unit 60. This multi-control unit 60 consists of a microcomputer and its peripheral circuits, and has external refrigerant flow rate regulating valves 11 and 21.
, 31, on-off valve 15.25° 35, and temperature sensor 4
7, 48a, 48b.

48c is connected.

The indoor units c, , c21 c3 are the indoor control unit 7
It is equipped with 0.80.90.

These indoor control units consist of a microcomputer and its peripheral circuits, and external operation units 71, 81, and 91.
and an indoor temperature sensor 72°82.92, respectively.

Then, each indoor control unit receives frequency setting signals f1°f2. f
3 is transferred to the multi-control unit 60 as the required capacity. The multi-control unit 60 determines the required capacity of each indoor unit from the transferred frequency setting signal, and transfers the frequency setting signal fo corresponding to the sum total to the outdoor control unit 50.

Next, the operation of the above configuration will be explained with reference to FIG.

It is assumed that all indoor units are currently performing cooling operation.

At this time, the indoor control section 70 of the indoor unit C1 calculates the difference between the temperature detected by the indoor temperature sensor 72 and the set temperature determined by the operation operation section 71, and requests a frequency setting signal fl corresponding to the temperature difference. Multi-control unit 60 as cooling capacity
Transfer to.

Similarly, indoor control section 80.9 of indoor unit C2+C3
0 also transfers the frequency setting signal f2+f3 to the multi-control unit 60 as the required cooling capacity.

The multi-control unit 60 determines the required cooling capacity of each indoor unit based on the transferred frequency setting signal, and generates a frequency setting signal f corresponding to the sum total.

is transferred to the outdoor control unit 50.

In this case, the multi-control unit 60 holds data regarding the capacity of each indoor unit in advance, and uses this data as a criterion for determining the required cooling capacity.

The outdoor control unit 50 receives the frequency setting signal f transferred from each branch unit B. Based on this, the total required cooling capacity of the indoor unit is determined, and the number of operating compressors 1.2 and the operating frequency (output frequency of the inverter circuits 51 and 52) are controlled.

In this case, the outdoor control unit 50 shifts from operating one compressor 1 to operating two compressors 1 and 2 as the total required cooling capacity increases.

By the way, the refrigerant discharged from the compressor 1.2 contains lubricating oil, and most of the lubricating oil is in the oil separator 41.
The oil is collected in the compressor 1 through the oil bypass and pass pipe 42.
, 2. The unrecovered refrigerant goes through the refrigeration cycle and returns to the compressor 1.2.

On the other hand, the multi-control unit 60 controls the refrigerant flow rate adjustment valve 11.21.
．． The opening degree of 31 is controlled according to the required cooling capacity of the corresponding indoor unit, and the refrigerant flow rate is adjusted. Then, on top of this opening degree control, the following correction is added as appropriate.

The temperature detected by the temperature sensor 48a (outflow refrigerant temperature from the indoor unit C1) and the temperature detected by the temperature sensor 47 (pseudo-saturated refrigerant temperature) are taken in, and the difference ΔT between the two temperatures is calculated. This temperature difference ΔT is the pseudo refrigerant superheat degree in the indoor unit C1.

However, if the temperature difference ΔT is in the range shown in FIG. 3 below the set value, normal opening control without correction is performed.
When the temperature difference ΔT exceeds the set value and reaches the M region shown in FIG. 3, the corrected opening degree θ is calculated by the formula below, and the opening degree of the refrigerant flow rate regulating valve 11 is increased by that amount.

θ−K・(capacity of indoor unit C1) K is a constant.

In this case, the temperature difference ΔT is calculated at regular intervals, and if it is in the M region, the opening degree is increased each time.

If the temperature difference ΔT decreases and shifts to the N range below the set value, the opening degree before the shift is maintained.

When the temperature difference ΔT further decreases and shifts to the L region, normal opening control without correction is resumed.

Similarly, the temperature detected by the temperature sensor 48b (indoor unit C
2) and the temperature detected by the temperature sensor 47 (pseudo refrigerant superheat degree), and appropriately corrects the opening degree of the refrigerant flow rate regulating valve 21 according to the temperature difference.

Furthermore, the detected temperature of the temperature sensor 48c (indoor unit C
1) and the temperature detected by the temperature sensor 47 (pseudo refrigerant superheat degree), and appropriately adjusts the opening degree of the refrigerant flow rate regulating valve 31 according to the temperature difference.

In this way, the degree of refrigerant superheating for each indoor unit is detected,
By correcting the opening degree of each refrigerant flow rate adjustment valve according to these detection results, regardless of the length or head of the refrigerant piping,
It is possible to perform optimal refrigerant flow rate adjustment that matches the required cooling capacity of the indoor unit.

In other words, in situations where, for example, the refrigerant piping between branch unit B and the indoor unit is long, or the height of the refrigerant piping increases from branch unit B to the indoor unit, the pressure loss in the refrigerant piping is large and the normal If only the opening is controlled, the refrigerant flow rate to the indoor unit will decrease, resulting in a cycle that is too hot, but since the refrigerant flow rate is immediately increased at that time, the indoor unit can exert the necessary and sufficient cooling capacity.

From another perspective, restrictions on the installation of refrigerant piping can be relaxed.

Moreover, since the degree of superheating of the refrigerant is stabilized, it is possible to prevent the phenomenon of misting from the outlet of each indoor unit.

In the above embodiment, the case where there are three indoor units for each branch unit has been described, but it is also possible to implement the case with more than three indoor units or two indoor units.

[Effects of the Invention] As described above, according to the present invention, there is provided a means for controlling the operating frequency of the compressor according to the total required capacity of each indoor unit, and a means for controlling the operating frequency of the compressor according to the total required capacity of each indoor unit, and a means for controlling the operating frequency of the compressor in accordance with the total required capacity of each indoor unit, and a means for controlling the operating frequency of the compressor in accordance with the total required capacity of each indoor unit. A refrigerant flow rate adjustment valve that adjusts the refrigerant flow rate, a means for controlling the opening degree of these refrigerant flow rate adjustment valves according to the required capacity of the corresponding indoor unit, a means for detecting the degree of refrigerant superheating of each indoor unit, and a means for detecting the refrigerant superheat degree of each indoor unit. Since it is equipped with a means to correct the opening degree of each refrigerant flow rate adjustment valve according to the result, the optimal refrigerant flow rate adjustment that matches the required capacity of each indoor unit can be made without being affected by the length or head of the refrigerant piping. It is possible to provide an air conditioner with excellent reliability.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of a refrigeration cycle in an embodiment of the present invention, Fig. 2 is a diagram showing the configuration of a control circuit in the same embodiment, and Fig. 3 is a diagram showing the configuration of a control circuit in the same embodiment. Figure 1 is a diagram for explaining the operation of the refrigeration cycle in a conventional air conditioner. A...Outdoor unit, B...Branch unit, C1r
C2, C3... Indoor unit, 1.2... Variable capacity compressor, 47-... First temperature sensor, 48a, 48b. 48c... second temperature sensor, 50... outdoor control section,
60...Multi control unit, 70.80.90...Indoor control unit. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] In an air conditioner consisting of an outdoor unit having a variable capacity compressor, a plurality of branch units connected to this outdoor unit, and a plurality of indoor units connected to each of these branch units, according to the total required capacity of each indoor unit, means for controlling the operating frequency of the compressor; a refrigerant flow rate adjustment valve provided in each branch unit for adjusting the refrigerant flow rate to each indoor unit; and a means for controlling the opening of the refrigerant flow rate adjustment valve for the corresponding indoor unit It is characterized by comprising means for controlling according to the required capacity, means for detecting the degree of refrigerant superheating of each of the indoor units, and means for correcting the opening degree of each of the refrigerant flow rate regulating valves according to the detection results. air conditioner.