JPH01203850A - Air conditioner - Google Patents

Abstract

PURPOSE:To prevent the refrigerant delivery temperature and the suction temperature from rising so as to stabilize the operation at an optimum cycle temperature by providing sensors which detect the refrigerant suction temperature and the delivery temperature of compressors, and controlling the valve opening of a flow rate regulating valve in accordance with the detected temperatures from the respective temperature sensors. CONSTITUTION:While a refrigerating cycle is being performed, the refrigerant suction temperature and the delivery temperature of compressors 1, 2 are detected by suction temperature sensors 54, 55 and delivery temperature sensors 56, 57, and, if any one of the detected temperatures from the respective temperature sensors 54-57 reaches the set temperature, a pulse motor valve 52 is opened to allow part of low temperature liquid refrigerant to be supplied from the liquid refrigerant passage in the refrigerating cycle to the suction passage 44a side of the compressors 1, 2 via a bypass passage 51 for cycle cooling. By the low temperature refrigerant so supplied, the refrigerant temperature in the suction passage 44a of the compressors 1, 2 is reduced. As a result, the rise of the refrigerant suction and delivery temperature in and out of the compressors 1, 2 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) This invention relates to an improvement in an air conditioner having an improved structure of a heat pump type refrigeration cycle.

(Prior Art) Generally, air conditioners with a multi-type configuration including a plurality of indoor units are known.

FIG. 5 shows a heat pump type refrigeration cycle of this type of multi-type air conditioner, where A is an outdoor unit, B is a branch unit, and C, D, and E are indoor units. The outdoor unit A includes two variable capacity compressors 1.2, which are connected in parallel via check valves 3 and 4, respectively. Compressors 1 and 2, four-way valve 5, outdoor heat exchanger 6, heating expansion valve 7, and cooling cycle forming check valve 8
parallel body with, liquid tank 9, electric flow rate adjustment valve 11
゜21.31, parallel body of cooling expansion valve 12.22.32 and heating cycle forming check valve 13, 23.33, indoor heat exchanger 14.24.34, gas side on-off valve (electromagnetic on-off valve) ') 15. 25, 35, accumulator 10, etc. are successively connected to form a heat pump type refrigeration cycle. Note that the cooling expansion valves 12, 22, and 32 are each temperature-sensitive tubes 12a.

22a, 32a, and these temperature sensing tubes 12a,
22a and 32a are respectively attached to the gas side refrigerant piping of the indoor heat exchanger 14°24.34.

Further, the indoor heat exchangers 14, 24, and 34 are connected in parallel within the refrigeration cycle. During cooling operation, the fifth
A cooling cycle is formed in which the outdoor heat exchanger 6 functions as a condenser and the indoor heat exchangers 14, 24, and 34 function as evaporators by flowing the refrigerant in the direction shown by the solid arrow in the figure. Flow the refrigerant in the direction shown by the dotted arrow to connect the indoor heat exchangers 14, 24, and 34 to the condenser and outdoor heat exchanger 6.
A heating cycle is formed in which each of the two functions as an evaporator.

Furthermore, in this type of equipment, each indoor unit C, D
The number and capacity of the compressors 1.2 in operation are controlled so as to satisfy the required capacity of the compressors 1.2 and 11.2.
1. Each indoor heat exchanger 14 is controlled by controlling the opening degree of 31 respectively.
, 24. The refrigerant flow rate to 34 is adjusted. The cooling expansion valve 12.22.32 maintains the degree of superheat of the refrigerant in each indoor heat exchanger 14, 24.34 constant regardless of changes in the refrigerant flow rate, thereby ensuring stable and efficient operation. ing. Therefore, for example, when the required capacity of each indoor unit C, D, H is smaller than the set capacity, the required capacity is increased or decreased by increasing or decreasing the capacity of one compressor 1, and when this required capacity is greater than the set capacity, The compressor 1 and the compressor 2 are driven simultaneously. In addition, when the required capacity from each indoor unit C, D, and E decreases while the two compressors 1 and 2 are being driven simultaneously, the capacity of compressor 2 gradually decreases, and furthermore, the The operation of the compressor 2 is stopped and only one compressor 1 is operated.

By the way, in the conventional configuration described above, when the superheat of the refrigerant is large, such as when the air load of each indoor unit C, D, and E during operation is high, the compressor 1.
Since there is a risk that the refrigerant discharge temperature from the compressor 1.2 will rise significantly higher than the refrigerant discharge temperature during normal operation, the refrigerant will rapidly deteriorate inside the compressor 1.2, resulting in carbonization of the lubricating oil and There was a problem that the sliding parts of the piston, connecting rod, etc. in the 2 were likely to seize. Furthermore, if the refrigerant suction temperature of the compressor 1.2 is high, the temperature of the windings of the motor of the compressor 1.2 will rise, and there is a risk that the insulation will exceed the operating standard range of the compressor 1.2.

(Problems to be Solved by the Invention) With the conventional configuration, it is not possible to prevent an extreme rise in the refrigerant discharge temperature from the compressors 1 and 2, so the refrigerant deteriorates inside the compressors 1 and 2. This causes problems such as carbonization of lubricating oil and seizure of sliding parts such as pistons and connecting rods in each compressor 1 and 2, as well as an increase in the refrigerant suction temperature of compressors 1 and 2. Accordingly, compressor 1,
The temperature of the windings of the motor 2 rises, and the temperature of the compressor 1°2 increases.
There were problems such as exceeding the usage standard range.

This invention was made by paying attention to the following situations, such as an extreme rise in the refrigerant discharge temperature from the compressor and a drop in the refrigerant suction temperature.
- It is an object of the present invention to provide an air conditioner that can prevent temperature rise, etc., and can operate stably at an optimal cycle temperature.

[Structure of the Invention] (Means for Solving the Problems) This invention provides a bypass passage for cycle cooling that connects the liquid refrigerant flow passage in the refrigeration cycle and the suction passage of the compressor, and controls the valve opening degree. A possible flow rate adjustment valve is interposed in this bypass passage, and a suction temperature sensor and a discharge temperature sensor are respectively provided to detect the refrigerant suction temperature and refrigerant discharge temperature of the compressor, and the temperature is adjusted according to the detected temperature from each temperature sensor. A cycle cooling means is provided to control the opening degree of the flow rate regulating valve.

(Function) During operation of the refrigeration cycle, when either the refrigerant suction temperature or the refrigerant discharge temperature of the compressor reaches the set temperature, the flow rate adjustment valve is opened to remove the liquid refrigerant from the flow path in the refrigeration cycle. A portion of the low-temperature liquid refrigerant is introduced into the suction passage of the compressor via a cycle cooling bypass passage to lower the refrigerant temperature within the suction passage of the compressor.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. Note that in FIGS. 1 to 4, the same parts as in FIG. 5 are given the same reference numerals, and the explanation thereof will be omitted.

In FIG. 1, 41a is a refrigerant suction pipe of one compressor 1, 41b is a refrigerant discharge pipe of this compressor 1, 42a is a suction pipe of the other compressor 2, and 42b is a pipe of this compressor 1. 2
This is the refrigerant discharge side piping.

In this case, the refrigerant suction pipe 41a of the recompressor 1.2,
42a is connected to a common refrigerant suction pipe 43a, and the refrigerant discharge side pipes 41b and 42 of the recompressor 1.2.
b is similarly connected to a common refrigerant discharge pipe 43b,
Refrigerant suction side pipes 41a, 42a and refrigerant suction pipe 4
3a, the refrigerant suction passage 44a1 of the recompressors 1 and 2
Refrigerant discharge pipes 41b, 42b and refrigerant discharge pipe 43b
A refrigerant discharge passage 44b of the recompressor 1.2 is formed by the recompressor 1.2.

Furthermore, the refrigerant discharge side pipes 41b and 42 of the recompressors 1 and 2
Oil separators 45 and 46 are interposed in each portion b. One end of oil return pipes 47, 48 is connected to these oil separators 45, 46, and the other end of these oil return pipes 47, 48 is connected to refrigerant suction side pipes 41a, 42a of recompressors 1, 2. are connected to each other.

Furthermore, one end of an oil equalizing pipe 49 is connected to the bottom of the case of the compressor 1, as shown in FIG. The other end of this oil equalizing pipe 49 is connected to the bottom of the case of the other compressor 2.

On the other hand, a refrigerant pipe (liquid refrigerant The flow path) 50 includes a bypass path 51 for cycle cooling.
One end of the is connected.

The other end of this bypass passage 51 is connected to the refrigerant suction pipe 43a. Further, a pulse motor valve (flow rate adjustment valve) 52 that can control the valve opening is interposed in the bypass passage 51.

Further, a pressure sensor 53 is attached to the refrigerant discharge pipe 43b of the refrigeration cycle, and suction temperature sensors 54, 55 for detecting the refrigerant suction temperature are attached to the refrigerant suction side pipes 41a, 42a of the compressor 1. , 2 are provided with discharge temperature sensors 56 and 57, respectively, for detecting the refrigerant discharge temperature.

Moreover, FIG. 3 shows a control circuit of the air conditioner main body. In this FIG. 3, 60 is an outdoor control section attached to the outdoor unit A. This outdoor control section 60 is composed of a microcomputer and its peripheral circuits, and has a pulse motor valve 52, a pressure sensor 53, a suction temperature sensor 54, 55, a discharge temperature sensor 56, 57, and an inverter circuit 61, 62 connected to the outside. There is. In this case, the inverter circuits 61 and 62 rectify the voltage of the AC power supply 63, convert it into an AC voltage of a predetermined frequency by switching according to a command from the outdoor control unit 60, and convert it into an AC voltage of a predetermined frequency.
This is to supply driving power to M and 2M, respectively.

Further, 70 is a multi-control unit attached to the branch unit B. This multi-control unit 70 consists of a microcomputer and its peripheral circuits, and includes externally connected flow rate adjustment valves 11, 21.31 and on-off valves 15, 25.3.
5, respectively.

Furthermore, 80, 90.100 are indoor units C1D, H
This is an indoor control unit installed in each.

These indoor control units 80, 90, and 100 are composed of a microcomputer and its peripheral circuits, and are externally equipped with operating operation parts 81, 91, and 101, and an indoor temperature sensor 82.
, 92, and 102 are connected to each other. Each indoor control unit 80, 90° 100 receives a frequency setting signal f1. f
2. f3 is transferred to the multi-control unit 70 as the required capacity of each indoor unit C, D, and H. Also,
The multi-control unit 70 receives the transferred frequency setting signal f1.
．． f2. The total required capacity of each indoor unit C1D and E is determined based on f3, and the corresponding frequency setting signal f is determined. is transferred to the outdoor control section 60.

Next, the operation of the above configuration will be explained. For example, when all the indoor units C, D, and E are performing cooling operation, the indoor control section 80 of the indoor unit C uses the indoor temperature sensor 82.
calculates the difference between the detected temperature and the set temperature set by the operation unit 81, and generates a frequency setting signal f1 corresponding to the temperature difference.
is transferred to the multi-control unit 70 as the required cooling capacity. Similarly, the indoor control sections 90 and 100 of the indoor units D and H also receive the frequency setting signal f2. f3 is transferred to the multi-control unit 70 as the required cooling capacity.

Furthermore, the multi-control unit 70 receives the frequency setting signal f7. f2. Each indoor unit C based on f3
, D, and H, and transmits the frequency setting signal f corresponding to this sum to the outdoor control unit 60.

This outdoor control unit 60 controls the number of operating compressors 1.2 and the operating frequency (output frequency of the inverter circuits 61, 62) F in accordance with the transferred frequency setting signal fo. In this case, the outdoor control unit 60 drives only one compressor 1 when the total required cooling capacity is smaller than the set cooling capacity, and drives only one compressor 1 when the total required cooling capacity is larger than the set cooling capacity. Compressors 1 and 2 are driven simultaneously.

On the other hand, during the operation of the air conditioner (cooling, heating, and defrosting operations), the refrigerant suction temperature and refrigerant discharge temperature of the compressor 1.2 are detected by the suction temperature sensors 54, 55 and the discharge temperature sensors 56, 57, respectively. ing. As shown by zone A in FIG. 4, each temperature sensor 54.
55.56.If it is detected that all of the detected temperatures from 57 are lower than the predetermined set temperature TI, the outdoor control unit 60 causes the pulse motor valve 52 to
is held fully closed. In addition, each lH degree sensor 54,
When any of the detected temperatures from 55, 56, and 57 reaches a predetermined set temperature T1, the outdoor control section 60 controls the opening degree of the pulse motor valve 52 as follows.

When controlling the opening degree of the pulse motor valve 52, priority is given to the detected value of the temperature sensor that reaches the set temperature Tl first among the detected temperatures from the respective temperature sensors 54, 55, 56, and 57. Based on the temperature detected by the temperature sensor that has reached the set temperature T, the pulse motor valve 52
The opening degree is controlled. Then, when the temperature detected by the reference temperature sensor exceeds the set temperature Tl and reaches the temperature in zone B, the outdoor control section 60 causes the pulse motor valve 52 to open to the initial set opening degree. Therefore, as the pulse motor valve 52 is opened, the low-temperature refrigerant in the refrigerant pipe 50 can be caused to flow into the refrigerant suction pipe 43a through the cycle cooling bypass passage 51, so that the inflow refrigerant in the low-temperature state Accordingly, the temperature of the refrigerant on the side of the refrigerant suction pipe 43a can be effectively lowered.

Further, the opening degree of the pulse motor valve 52 is gradually increased by a predetermined number of steps (n pulses) every predetermined time unit after the opening operation is performed to the initial setting opening degree. When it is detected that the temperature detected by the reference temperature sensor has reached zone C, which is lower than the set temperature T, the opening increasing operation of the pulse motor valve 52 is stopped at that point. The pulse motor valve 52 is held at a certain temperature. Also,
When the temperature detected by the reference temperature sensor falls from the C zone to the D zone, the opening degree of the pulse motor valve 52 is gradually reduced by a predetermined number of steps (n pulses) every predetermined time unit. Then, by this operation of reducing the opening degree of the pulse motor valve 52, the opening degree of the pulse motor valve 52 returns to 0, that is, when the pulse motor valve 52 is fully closed, the initial state is returned.

Note that each temperature sensor 54, 55, 56, and 57 is
Temperature detection values from are ignored.

Therefore, in the case of the above configuration, during the refrigeration cycle operation, the suction temperature sensor 54,55 and the discharge temperature sensor 5
6 and 57 to detect the refrigerant suction temperature and refrigerant discharge temperature of the compressor 1.2, respectively, and each temperature sensor 54,
55, 56, and 57 reaches the set temperature T1, by opening the pulse motor valve 52, the bypass passage 51 for cycle cooling is removed from the liquid refrigerant flow passage in the refrigeration cycle. Compressor 1 through
Since a part of the low temperature liquid refrigerant is introduced into the suction passage 44a of the compressor 1.2, the refrigerant temperature within the suction passage 44a of the compressor 1.2 can be lowered by this low temperature introduced refrigerant.

Therefore, during the refrigeration cycle operation, the compressor 1
Since it is possible to prevent an extreme rise in the refrigerant discharge temperature from , 2 and a rise in the refrigerant suction temperature, it is possible to prevent deterioration of the refrigerant, carbonization of lubricating oil, and piston inside each compressor 1.2. It is possible to prevent seizure of sliding parts such as connecting rods and an extreme rise in the temperature of the windings of the motor of the compressor 1.2, thereby allowing stable operation at an optimal cycle temperature. Furthermore, even if variations in the refrigerant port occur during operation of the refrigeration cycle, these variations can be corrected in a relatively short time, thereby preventing extreme pressure fluctuations during the refrigeration cycle. Can be done.

It should be noted that this invention is not limited to the embodiments described above, and it goes without saying that various modifications can be made without departing from the gist of the invention.

[Effects of the Invention] According to the present invention, a cycle cooling bypass passage connecting the liquid refrigerant flow passage in the refrigeration cycle and the suction passage of the compressor is provided, and a flow rate adjustment valve that can control the valve opening is provided in this bypass passage. A suction temperature sensor and a discharge temperature sensor are installed in the bypass passage and detect the refrigerant suction temperature and refrigerant discharge temperature of the compressor, respectively, and the flow is controlled by the opening of the regulating valve according to the detected temperature from each temperature sensor. Since a cycle cooling means is provided to control the temperature, extreme rises in the refrigerant discharge temperature from the compressor and -L rises in the refrigerant suction temperature can be prevented.
This allows for stable operation at the optimum cycle temperature.

[Brief explanation of the drawing]

Figures 1 to 4 show an embodiment of the present invention.
Figure 1 is a schematic diagram of the overall configuration of the refrigeration cycle inside the air conditioner, Figure 2 is a schematic diagram of the installation of the oil equalizing pipe between the two compressors, and Figure 3 is the control of the refrigeration cycle. FIG. 4 is a temperature characteristic diagram for explaining the control state of the flow rate regulating valve, and FIG. 5 is an overall schematic diagram showing the refrigeration cycle in a conventional air conditioner. 1.2... Compressor, 44... Refrigerant suction passage, 50
... refrigerant pipe (liquid refrigerant flow path), 51 ... bypass passage, 52 ... pulse motor valve (flow rate adjustment valve),
54゜55...Suction temperature sensor, 56.57...
Discharge temperature sensor, 60... outdoor control section. Applicant's Representative Patent Attorney Takehiko Suzue Figure 2 Time Figure 4

Claims (1)

[Claims] A bypass passage for cycle cooling is provided that connects the liquid refrigerant flow passage in the refrigeration cycle and the suction passage of the compressor,
A flow regulating valve whose opening degree can be controlled is interposed in this bypass passage, and a suction temperature sensor and a discharge temperature sensor are respectively provided to detect the refrigerant suction temperature and refrigerant discharge temperature of the compressor, and from each of the temperature sensors. An air conditioner comprising cycle cooling means for controlling the opening degree of the flow rate regulating valve according to the detected temperature.