JPH08219531A - Multiple type air conditioner - Google Patents

Abstract

PURPOSE: To obtain a multiple type air conditioner which can prevent the stoppage of a compressor being consequent upon reduction of the number of rooms and also can make the best use of the capacity of the compressor at the time of a steady state operation. CONSTITUTION: This air conditioner is equipped with one outdoor heat exchanger 3 and a plurality of indoor heat exchangers 8A, 8B and 8C provided for separate rooms. It is equipped with a temperature detecting means DOA for detecting an outdoor air temperature. It is equipped with a control means 1 which determines whether or not the outdoor air temperature is a reference value or above, on the basis of an output of the temperature detecting means DOA, when some of branch refrigerant routes 11A, 11B and 11C are closed and the number of rooms to be heated is reduced in the course of a heating operation, and executes a control of stopping an outdoor fan 6 or lowering a speed of rotation thereof when it determines that the outdoor air temperature is the reference value or above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-type air conditioner. More specifically, the present invention relates to a multi-type air conditioner that drives a plurality of indoor units with one outdoor unit.

[0002]

2. Description of the Related Art A multi-type air conditioner of this type has, as shown in FIG. 4, one outdoor heat exchanger 3 and a plurality of indoor heat exchangers 8A, 8B, 8C provided for each room. (A, B, and C at the end of the reference numerals correspond to rooms.). When performing heating operation for a plurality of rooms, the solenoid valves EVA, EVB, EVC corresponding to each room are opened. And the compressor 2
The high-temperature high-pressure refrigerant compressed by the four-way switching valve 4 and the branched pipes 11A, 11B, and 11C are used to heat the indoor heat exchangers 8A,
8B, 8C, and the indoor heat exchangers 8A, 8B, 8C radiate heat to condense the refrigerant. Then, from the indoor heat exchangers 8A, 8B, 8C to the solenoid valves EVA, EVB, EV
C, the low-temperature and low-pressure refrigerant is sent to the outdoor heat exchanger 3 through the joined pipe 12 and the expansion valve 9, and the outdoor heat exchanger 3 absorbs heat from the outside air while the outdoor fan 6 is rotated to remove the refrigerant. Evaporate. Further, the refrigerant is returned to the compressor 2 from the outdoor heat exchanger 3 through the four-way switching valve 4 and the accumulator 5 for separating gas and liquid. In this way, the heating operation of a plurality of rooms is performed by one outdoor unit.

Reference numeral 1 denotes a central processing unit (CPU) for controlling the operation of the entire air conditioner, DE, DA, D.
B and DC are the outdoor heat exchanger 3 and the indoor heat exchanger 8, respectively.
Temperature sensors attached to A, 8B, and 8C and DOA are outside air temperature sensors. Further, 7 is a low pressure sensor (LPS) that detects the suction pressure of the compressor, and MRD is a solenoid valve that is opened during defrost (defrosting operation).

[0004]

By the way, in a multi-type air conditioner, generally, when the number of rooms performing heating operation decreases (corresponding solenoid valve is closed), the heat radiation amount suddenly decreases. The refrigerant temperature rises as a whole, and the discharge pressure (high pressure) of the compressor 2 temporarily rises as indicated by the broken line P ₀ in FIG. This phenomenon becomes particularly noticeable when the outside air temperature is relatively high, for example, 15 ° C. or higher. As a result, a torque shortage of the compressor 2 occurs, and as shown by P ₀ in FIG. 2, the operating state of the compressor 2 deviates from the use area AA as a product (air conditioner) and is controlled by the CPU 1. There is a problem that the compressor is stopped (OFF). The use area AA as a product is set lower than the use area CA of the compressor itself in consideration of the safety factor.

In order to prevent the compressor from being stopped due to such a decrease in the number of rooms, conventionally, the steady operation area is greatly reduced with respect to the product use area AA, and the capacity of the compressor 2 is reduced during the steady operation. It is operating in a state of suppressing.

Therefore, an object of the present invention is to provide a multi-type air conditioner which can prevent the compressor from being stopped due to a decrease in the number of rooms and can make full use of the capacity of the compressor during steady operation. is there.

[0007]

In order to achieve the above object, a multi-type air conditioner according to claim 1 has one outdoor heat exchanger and a plurality of indoor heat exchangers provided for each room. And a refrigerant compressed by a compressor is sent to each indoor heat exchanger through a branched refrigerant path, the indoor heat exchanger radiates heat to condense the refrigerant, and the refrigerant flows through a combined refrigerant path. To the outdoor heat exchanger through the expansion means, and while the outdoor fan is rotated at a predetermined rotation speed, the outdoor heat exchanger absorbs heat from the outside air to evaporate the refrigerant, and the refrigerant is heated to the outdoor heat. Returning to the compressor from the exchanger, in a multi-type air conditioner configured to perform heating operation of a plurality of rooms in parallel, temperature detection means for detecting the outside air temperature, the refrigerant path branched during heating operation Some of the routes When the number of rooms to be heated is reduced, it is determined whether the outside air temperature is equal to or higher than the reference value based on the output of the temperature detection means, and when it is determined that the outside air temperature is equal to or higher than the reference value. It is characterized in that it is provided with control means for performing control for stopping the outdoor fan or reducing the rotation speed.

The multi-type air conditioner according to claim 2 is the multi-type air conditioner according to claim 1,
The refrigerant path includes pressure detection means for detecting the pressure at any one of the converging points, and the control means stops the outdoor fan or lowers the rotation speed, and then further outputs the pressure detection means. Based on this, it is determined whether the refrigerant pressure in the merged refrigerant path is lower than or equal to a reference value, and when the refrigerant pressure is lower than or equal to the reference value, control is performed to operate the outdoor fan or increase the rotation speed. It is characterized by that.

Further, the multi-type air conditioner according to claim 3 is the multi-type air conditioner according to claim 1,
During the heating operation, the control means (1) is provided with a timer for measuring a set time from the time when the outdoor fan (6) is stopped or the rotation speed is reduced, and when the timer measures the set time. The control means (1) is characterized by performing control for operating the outdoor fan (6) or increasing the rotation speed.

[0010]

In the multi-type air conditioner according to the present invention, the control means controls the temperature when the number of rooms to be heated decreases when a part of the branched refrigerant paths are closed during the heating operation. Based on the output of the detection means, it is determined whether the outside air temperature is equal to or higher than the reference value, and when it is determined that the outside air temperature is equal to or higher than the reference value, the outdoor fan is stopped or the rotation speed is reduced.

By stopping the outdoor fan or reducing the rotation speed, the amount of heat absorbed from the outside air in the outdoor heat exchanger is reduced. Therefore, the increase in the refrigerant temperature due to the decrease in the number of rooms and the decrease in the amount of heat radiation is suppressed, and the discharge pressure (high pressure) of the compressor is less likely to increase. Therefore, the operating state of the compressor is easily accommodated within the usage area of the product, and the problem that the compressor stops is prevented. Conversely, it is possible to set the operating state of the compressor during steady operation close to the upper limit of the area used as a product. By setting in this way, the capacity of the compressor can be fully utilized during steady operation.

The reference value of the outside air temperature is set in advance according to the characteristics of the air conditioner. That is, when the number of rooms decreases and the refrigerant temperature rises, it is set to a value slightly lower than the lower limit temperature at which the compressor stops (OFF).

When the outdoor fan is stopped or the low speed operation is continued, the temperature of the refrigerant is lowered and the pressure of the refrigerant is lowered. Therefore, the outdoor heat exchanger may be erroneously detected as frosted.

Therefore, in the multi-type air conditioner according to the second aspect, the control means stops the outdoor fan or reduces the rotation speed, and then the combined refrigerant is based on the output of the pressure detection means. It is determined whether or not the refrigerant pressure in the path is equal to or lower than a reference value, and when the refrigerant pressure is equal to or lower than the reference value, the outdoor fan is operated or the rotation speed is increased. This reference value is set to be slightly higher than the pressure value when it is determined that the outdoor heat exchanger has frosted. With this setting, it is possible to shift to the normal heating operation before erroneously detecting that the outdoor heat exchanger has frosted.

Further, in the multi-type air conditioner of claim 3, during the heating operation, the set time is measured from the time when the control means (1) stops the outdoor fan (6) or reduces the rotation speed. It is equipped with a timer. This set time is set, for example, to the time required for the pressure of the merged refrigerant paths to fall to the above reference value. Then, when the timer measures the set time, the control means (1) controls the outdoor fan (6) to operate or increase the rotation speed. With this setting, it is possible to shift to the normal heating operation before erroneously detecting that the outdoor heat exchanger has frosted.

[0016]

EXAMPLES The multi-type air conditioner of the present invention will be described in detail below with reference to examples.

In this embodiment, a multi-type air conditioner having the same piping system as that of the multi-type air conditioner shown in FIG. 4 will be described.

That is, this multi-type air conditioner has one
Outdoor heat exchanger 3 and a plurality of indoor heat exchangers 8A, 8B, 8C provided for each room (A, B, C at the end of the reference numeral)
Corresponds to the room. ) Is provided. The central processing unit (CPU) 1 serves as a control unit to control the operation of the entire air conditioner.

When performing heating operation for a plurality of rooms, the solenoid valves EVA, EVB, EVC corresponding to each room are opened. Then, the high-temperature high-pressure refrigerant compressed by the compressor 2 is sent to the indoor heat exchangers 8A, 8B, 8C through the four-way switching valve 4 and the branched refrigerant pipes 11A, 11B, 11C, and the indoor heat exchangers 8A, 8B, Heat is radiated at 8C to condense the refrigerant. Subsequently, the low-temperature low-pressure refrigerant is sent to the outdoor heat exchanger 3 from the indoor heat exchangers 8A, 8B, 8C through the solenoid valves EVA, EVB, EVC, the joined refrigerant pipe 12, and the expansion valve 9, and the outdoor fan 6 is turned on. Outdoor heat exchanger 3 in the rotated state
Absorbs heat from the outside air to evaporate the refrigerant. Further, the refrigerant is returned to the compressor 2 from the outdoor heat exchanger 3 through the four-way switching valve 4 and the accumulator 5 for separating gas and liquid. In this way, the heating operation of a plurality of rooms is performed by one outdoor unit.

The temperature sensors DE, DA, DB and DC are respectively the outdoor heat exchanger 3 and the indoor heat exchangers 8A, 8B and 8C.
Detects the temperature of. The outside air temperature sensor DOA detects the outside air temperature as a temperature detecting means. In addition, the low pressure sensor (L
PS) 7 is a combined refrigerant pipe 1 as pressure detecting means.
The refrigerant pressure (suction pressure (low pressure) of the compressor) at a portion between 2 between the accumulator 5 and the compressor 2 is detected. The solenoid valve MRD is opened during defrosting (defrosting operation) to bypass the refrigerant from the expansion valve 9 to the four-way switching valve 4.

Now, as shown in FIG. 1, during heating operation (S
In 1), when, for example, the solenoid valves EVB, EVC among the solenoid valves EVA, EVB, EVC are closed and the number of rooms to be heated decreases (S2), the CPU 1 causes the outdoor temperature sensor D
OA output is sampled to detect the outside air temperature (S
3), it is determined whether the outside air temperature is equal to or higher than the reference value (S4). The reference value of the outside air temperature is 15 ° C. in this example. Then, when it is determined that the outside air temperature is lower than 15 ° C., it is determined that the compressor 2 will not be stopped due to insufficient torque, and the process returns to step S1 to continue the normal heating operation.

On the other hand, when it is determined that the outside air temperature is 15 ° C. or higher, the CPU 1 controls to stop the outdoor fan 6 (S5). By stopping the outdoor fan 6, the amount of heat absorbed from the outside air in the outdoor heat exchanger 3 decreases. Therefore, the increase in the refrigerant temperature due to the decrease in the number of rooms and the decrease in heat radiation is suppressed, and the solid line P in FIG.
_As indicated by ₁ , the discharge pressure (high pressure) of the compressor 2 is less likely to rise. Therefore, as shown by the solid line P ₁ in FIG. 2, the operating state of the compressor 2 is the use area A as a product.
It can be easily accommodated in A, and it is possible to prevent a problem that leads to a stop. Conversely speaking, the operating state of the compressor 2 during steady operation can be set close to the upper limit of the area used as a product. By making such a setting, the capacity of the compressor 2 can be fully utilized during steady operation.

Here, if the state where the outdoor fan 6 is stopped is continued, the temperature of the refrigerant is lowered as a whole, and the pressure of the refrigerant is also lowered. For this reason, there is a possibility that the outdoor heat exchanger 3 may be erroneously detected as frosted.

Therefore, the CPU 1 further includes the low pressure sensor 7
Is sampled to detect the suction pressure of the compressor 2 (S6), and it is determined whether this suction pressure is equal to or lower than a reference value (S7). When this suction pressure falls below the standard value,
Control of operating the outdoor fan 6 is performed (S8). This reference value is set to be slightly higher than the pressure value when it is determined that the outdoor heat exchanger has frosted. With this setting, it is possible to shift to the normal heating operation (S1) before erroneously detecting that the outdoor heat exchanger 3 has frosted. It should be noted that it is desirable to shift to the normal heating operation when the time from the maximum value of the operating frequency before the decrease in the number of rooms to the initial frequency after the decrease in the number of rooms has elapsed.

The reference value of the outside air temperature is not limited to 15 ° C., and when the number of rooms decreases and the refrigerant temperature rises, the compressor stops (OF) depending on the characteristics of the air conditioner.
It may be set to a value slightly lower than the lower limit temperature reaching F).

Further, in this embodiment, step S in FIG.
The outdoor fan 6 is stopped at 5, and the outdoor fan 6 is stopped at step S8.
However, the rotation speed of the outdoor fan 6 may be reduced in step S5 without stopping the outdoor fan 6 in step S5, and the rotation speed of the outdoor fan 6 may be increased in step S8.

In order to prevent the outdoor heat exchanger 3 from being erroneously detected as frosted, the CPU 1 sets the outdoor fan 6
A timer may be provided to measure the set time from the time when the rotation speed is stopped or the rotation speed is decreased. This set time is set to a time required for the pressure of the merged refrigerant paths to fall to the above reference value (the pressure value in a state where it is determined that the outdoor heat exchanger has frosted). Then, when the timer measures the set time, the CPU 1 controls the outdoor fan 6 to operate or increase the rotation speed. With this setting, it is possible to shift to the normal heating operation before erroneously detecting that the outdoor heat exchanger has frosted.

[0028]

As is clear from the above, in the multi-type air conditioner according to the first aspect, the control means should be heated by closing some of the branched refrigerant paths during the heating operation. When the number of rooms decreases, it is determined whether the outside air temperature is equal to or higher than a reference value based on the output of the temperature detection means, and when the outside air temperature is determined to be equal to or higher than the reference value, the outdoor fan is stopped or Since the control for reducing the rotation speed is performed, it is possible to suppress the increase in the refrigerant temperature due to the decrease in the number of rooms and the decrease in the amount of heat radiation, and prevent the problem that the compressor is stopped. Conversely speaking, the operating state of the compressor during steady operation can be set close to the upper limit of the usage area as a product, and the capacity of the compressor can be fully utilized during steady operation.

Further, in the multi-type air conditioner according to a second aspect of the invention, the control means stops the outdoor fan or lowers the rotation speed, and then the combined refrigerant is based on the output of the pressure detection means. It is determined whether or not the refrigerant pressure in the path is equal to or lower than the reference value, and when the refrigerant pressure is equal to or lower than the reference value, the outdoor fan is operated or the control for increasing the rotation speed is performed. By setting the pressure value slightly higher than the pressure value at which the outdoor heat exchanger is determined to have frosted, it is possible to shift to normal heating operation before the outdoor heat exchanger is erroneously detected as frosted. it can.

Further, in the multi-type air conditioner of claim 3, during the heating operation, the set time is measured from the time when the control means (1) stops the outdoor fan (6) or reduces the rotation speed. Since the control means (1) controls the operation of the outdoor fan (6) or the increase of the rotation speed, the set time is reduced by, for example, the pressure of the merged refrigerant path to the reference value. By setting the time required to do so, it is possible to shift to the normal heating operation before erroneously detecting that the outdoor heat exchanger has frosted.

[Brief description of drawings]

FIG. 1 is a diagram showing an operation flow of an air conditioner of an embodiment of the present invention.

FIG. 2 is a diagram showing operating characteristics of the air conditioner.

FIG. 3 is a diagram showing a lapse of time of a discharge pressure of a compressor of an air conditioner.

FIG. 4 is a diagram showing a piping system of an air conditioner.

[Explanation of symbols]

 1 CPU 2 Compressor 3 Outdoor heat exchanger 6 Outdoor fan 7 Low pressure sensor 8A, 8B, 8C Indoor heat exchanger

Claims (3)

[Claims] 1. An outdoor heat exchanger (3) and a plurality of indoor heat exchangers (8A, 8B, 8C) provided for each room.
And the refrigerant compressed by the compressor 2 is sent to the indoor heat exchangers (8A, 8B, 8C) through the branched refrigerant paths (11A, 11B, 11C), and the indoor heat exchangers (8A, 8B) are provided. , 8C) to radiate heat to condense the refrigerant, and send the refrigerant to the outdoor heat exchanger (3) through the converging refrigerant path (12) through the expansion means (9) to set the outdoor fan (6) to a predetermined position. The outdoor heat exchanger (3) absorbs heat from the outside air to evaporate the refrigerant, and the refrigerant is returned from the outdoor heat exchanger (3) to the compressor (2) while being rotated at the rotational speed of In a multi-type air conditioner configured to perform heating operation of a plurality of rooms in parallel, temperature detecting means (DOA) for detecting the outside air temperature, and the branched refrigerant paths (11A, 11B,
11C), when some of the paths are closed and the number of rooms to be heated is reduced, it is determined whether the outside air temperature is equal to or higher than a reference value based on the output of the temperature detection means (DOA), A multi-type air conditioner comprising control means (1) for controlling the outdoor fan (6) to stop or to reduce the rotation speed when it is determined that the outside air temperature is equal to or higher than a reference value. 2. The multi-type air conditioner according to claim 1, further comprising pressure detection means (7) for detecting the pressure at any of the merged points in the refrigerant path, and the control means (1). After stopping the outdoor fan (6) or reducing the rotation speed, it is further determined whether the refrigerant pressure in the combined refrigerant path is equal to or lower than a reference value based on the output of the pressure detection means (7). A multi-type air conditioner characterized by performing a control to operate the outdoor fan (6) or increase the rotation speed when the determination is made and the refrigerant pressure becomes equal to or lower than a reference value. 3. The multi-type air conditioner according to claim 1, wherein during the heating operation, the control unit (1) stops the outdoor fan (6) or reduces the rotation speed for a set time. A multi-function timer characterized by comprising a timer for measuring the time, and at the time when the timer measures the set time, the control means (1) controls the outdoor fan (6) to operate or increase the rotation speed. Type air conditioner.