JPH0518644A - Air conditioner - Google Patents

Abstract

PURPOSE:To reduce a fear of a vaporizer being frozen during operation at a low open air temperature and to eliminate a need for addition of a refrigeranteven when the length of a connection piping is increased and a piping is lengthened. CONSTITUTION:An air conditioner bypasses a refrigerant through an outdoor fan 6, the speed of which is variable and which is switched to a low speed at a low open air temperature period and a bypass pipe 9 in which a capillary tube 7 for bypass running from the delivery side of a compressor 1 to the outlet side of a condenser 2 at a low opening air temperature period and a two-way valve 8 are located. A change-over switch 11 is located in the middle of a wiring through which the delivery pressure of the compressor 1 is detected to feed a keying signal to a two-way valve 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner, and more particularly to an improvement of an air conditioner for low outside air temperature which can be operated without freezing of an evaporator even at a low outside air temperature.

[0002]

2. Description of the Related Art Conventionally, as an air conditioner for low outside temperature,
For example, the one shown in FIG. 5 is generally known.

In this air conditioner, a compressor 1, a condenser 2, a capillary tube 3 and an evaporator 4 are sequentially connected by pipes to form a refrigeration cycle, and the condenser 2 is operated behind the condenser 2 at a low outside temperature. An outdoor fan 5 for switching the state to a lower speed side is arranged, and an indoor fan 6 is arranged behind the evaporator 4. The discharge side of the compressor 1 and the outlet side of the condenser 2 are connected by a bypass pipe 7, and the bypass pipe 7 is provided with a capillary tube 8 and a two-way valve 9.

On the discharge side of the compressor 1, a pressure switch 10 for detecting the discharge pressure and sending a signal to the outdoor fan 5 and the two-way valve 9 is provided.

The pressure switch 10 is, for example, 13 kg / cm ²
When G or less is detected, the outdoor fan 5 is switched to the low speed side by the signal from the pressure switch 10 and the two-way valve 9 is opened to reduce the supercooling of the refrigerant at low outside air temperature. Part of the refrigerant discharged from the bypass pipe 7
It is bypassed to the outlet side of the condenser 2 via.

When the pressure of the pressure switch 10 exceeds 19 kg / cm ² G, for example, the outdoor fan 5 is switched to the high speed side and the two-way valve 9 is closed.

[0007]

However, in the conventional air conditioner, the distance a during the refrigeration cycle of FIG.
If the length of the connection pipe (transit pipe) indicated by b and the distance cd is a long pipe of, for example, 12 m or more, the pressure inside the evaporator 4 may decrease and the evaporator 4 may freeze. For this reason, the length of the connection pipe is currently limited to a certain length, for example, 12 m. When the connection pipe becomes long, the refrigerant flowing in the bypass pipe 7 becomes
Since the refrigerant flowing from the condenser 2 to the capillary tube 3 is suppressed and the refrigerant is tried to be confined in the condenser 2, the tendency of the refrigerant to stagnate in the condenser 2 becomes strong, and thus the refrigerant flowing to the evaporator 4 is small. Because it will be.

Although it is possible to prevent freezing of the evaporator 4 by adding a refrigerant, overfilling of the refrigerant causes
The compressor 1 may be damaged.

The present invention has been made in consideration of the above-mentioned circumstances, and even if the length of the connecting pipe is long, there is little risk of freezing the evaporator during operation at low outside air temperature, and the refrigeration cycle is used. An object is to provide an air conditioner that does not require the addition of a refrigerant.

[0010]

In order to achieve the above object, an air conditioner according to the present invention has an outdoor fan capable of switching the operating state according to the outside air temperature and a low outside air conditioner as described in claim 1. Detects the discharge pressure of a compressor in an air conditioner that has a bypass pipe that bypasses the refrigerant from the discharge side of the compressor to the outlet side of the condenser when operating at ambient temperature, and has a capillary tube and a two-way valve in this bypass pipe. Then, in the middle of the wiring for sending the open / close signal to the two-way valve, there is provided a changeover switch for controlling the bypass flow of the refrigerant passing through the bypass pipe according to the pipe length of the refrigeration cycle, and the air of the present invention. The harmony machine is provided with a control unit for detecting the temperature of the evaporator and controlling the opening and closing of the two-way valve as described in claim 2.

Further, the air conditioner according to the present invention is claim 3.
As described above, the condenser is divided into a plurality of parallel divisions and arranged in parallel, and a refrigeration cycle in which an inlet / outlet valve is provided in the inlet side piping of each condenser, and a blowing capacity provided so as to face each condenser. And a condensing capacity control device for controlling the operation of the outdoor fan and the opening / closing of the corresponding condenser in an interlocking manner.

[0012]

According to the present invention having the above-mentioned structure, the length of the connecting pipe set in advance is, for example, 12
Turns off the changeover switch when piping is longer than m
By setting it to (Open) so that the open / close signal is not sent to the two-way valve, the refrigerant does not flow in the bypass pipe and the refrigerant diversion is prevented, and the amount of refrigerant guided to the evaporator is secured sufficiently. However, the freezing is prevented.

According to the second aspect of the present invention, the two-way valve that opens and closes the bypass pipe is controlled by the evaporator temperature, so that the two-way valve is operated when the temperature of the evaporator falls below the set temperature. To prevent the refrigerant split in the bypass pipe from flowing, and thereby prevent the evaporator from freezing during low outside temperature operation even when the connection pipe is a long pipe of, for example, about 20 m.

Further, according to the invention of claim 3,
The condensation capacity can be variably controlled by the outside air temperature,
As a result, stable cooling operation can be performed from a high temperature to a low temperature.

[0015]

Embodiments of the air conditioner according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an essential part of a first embodiment of an air conditioner according to the present invention. This air conditioner has a refrigeration cycle and a structure incorporated in the conventional air conditioner shown in FIG. Since the same is applied, the same reference numerals are given and the description thereof is omitted.

In the air conditioner shown in FIG. 1, the pressure switch 10 for detecting the discharge pressure of the compressor 1, the indoor fan 6 and the two-way valve 9 are connected by a wiring l.
When a predetermined pressure is reached, the switching of the indoor fan 6 to the low speed or high speed side and the opening / closing of the two-way valve 9 are controlled. A changeover switch 11 is provided on the wiring 1 between the pressure switch 10 and the two-way valve 9.

Then, for example, the changeover switch 11 is turned off.
By setting it to (open), the open / close signal from the pressure switch 10 is not sent to the two-way valve 9, and the two-way valve 9 is maintained in the closed state. As a result, it is possible to prevent the refrigerant split in the bypass pipe 7 from flowing.

The length of the connecting pipes of the refrigeration cycle (distance ab and distance cd in FIG. 1) is, for example, 12 m.
During low outside air temperature operation with long piping as described above, the evaporator 4 may freeze due to a decrease in internal pressure. However, in this air conditioner, when long piping is used for the refrigeration cycle,
By turning off the selector switch 11 at the time of low outside temperature operation, the refrigerant is prevented from passing through the bypass pipe 7, and all the discharged refrigerant is evaporated from the condenser 2 through the capillary tube 3. The evaporator 4 is formed so as to be guided, and the evaporator 4 can be operated while being prevented from freezing due to the shortage of the refrigerant.

As described above, according to this embodiment, the changeover switch 11 provided in the wiring l connecting the pressure switch 10 and the two-way valve 9 is appropriately changed over, so that the long pipe can be used during the low outside air temperature cooling operation. There is almost no risk of freezing of the evaporator 4, and an air conditioner can be obtained in which no additional refrigerant is required in the refrigeration cycle.

2 and 3 show a second embodiment of the air conditioner. In this embodiment, the temperature sensor 1 for detecting the temperature of the evaporator 4 is added to the conventional air conditioner shown in FIG.
2 and a control unit 13 for opening and closing the two-way valve 8 according to the temperature of the temperature sensor 12.

When the pressure switch 10 senses low outside air cooling, the outdoor fan 5 is set to the low speed side, the two-way valve 8 is opened, and a part of the refrigerant flows through the bypass pipe 7. There is. As a result, the compressor 1 can be protected from the liquid bag generated when the length of the connecting pipe is, for example, a short pipe of 5 m or less. At this time, as shown in FIG. When Tc becomes lower than the set temperature k (for example, −2 ° C.), the two-way valve 9
Has been like closing.

This means that when the sensed temperature Tc becomes lower than the set temperature k, the pressure of the evaporator 4 has decreased, so that the length of the connecting pipe is long. This is because there is a risk of freezing the evaporator 4 if it is left as it is.

Further, even when the outdoor temperature is too low and the connecting pipe is short, the sensing temperature Tc may be lower than the set temperature k. Therefore, according to the following flow chart, after closing the two-way valve 9, the compressor 1 is stopped, for example, in about 5 minutes to cope with this.

Further, when the two-way valve 9 is closed, the refrigerant sunk in the condenser 2 flows smoothly, and the pressure and temperature of the evaporator 4 rise. When this operation is shown, it is not necessary to protect the compressor 1 from the liquid bag by bypass because the connecting pipe is a long pipe having a length of 12 m or more, for example.
Therefore, after closing the two-way valve 9, time S (for example, 5 minutes)
Then, when the sensed temperature Tc is lower than the set temperature k again, the outdoor temperature is too low or the indoor humidity is too low as described above, so the compressor 1 is stopped. On the other hand, when the connection pipe of the refrigeration cycle is a long pipe, for example,
Since the pressure of the evaporator 1 rises and the sensed temperature Tc satisfies the set temperature k or higher until the length of the connecting pipe reaches about 20 m,
The operation is continued with the two-way valve 9 closed.

When the compressor 1 stops operating,
Similar to the conventional freeze prevention thermostat, the operation of the compressor 1 is restarted when, for example, the sensed temperature Tc exceeds a predetermined temperature 1 (for example, 6 ° C.).

By controlling in this manner, liquid backing to the compressor 1 can be prevented when the short pipe is used, and an air conditioner with high operation efficiency that is less likely to be frozen during low outside temperature operation when the long pipe is used. can do.

Further, in the low outside air temperature cooling operation at the time of short piping,
By the conventional bypass, the liquid back is prevented and the compressor 1 is protected, and in the low outside air temperature cooling operation at the time of long piping, the freezing of the evaporator 4 is reduced to improve the operation efficiency. The cooling capacity is obtained, and the length of the connecting pipe is 3 to 20.
It is possible to provide an air conditioner that can perform a low outside air temperature cooling operation ranging from a short pipe of about m to a long pipe.

FIG. 4 shows a third embodiment of the air conditioner, in which the condenser 2a,
2b are divided into a plurality of units, for example, two units, and are installed in parallel, and indoor fans 4a and 4b having different air-blowing capacities are provided so as to face the condensers 2a and 2b, while the inlet side pipes of the condensers 2a and 2b are provided. For example, solenoid valves EV1 and EV2 are provided as opening / closing valves. With this configuration, the condenser 2a,
The condensation capacity in 2b is variably controlled in multiple stages.

The two outdoor fans 4a, 4b are arranged vertically, and the rotation speed of the fan motor FM1 is larger than that of the fan motor FM2 so that the rotation speeds of the respective fan motors FM1, FM2 are different. FM1 rotation speed> FM2 rotation speed), and solenoid valves EV1 and EV that can be opened and closed are provided behind each of the outdoor fans 4a and 4b.
The condensers 2a and 2b having 2 on the inlet side are arranged to face each other, and the upper and lower outdoor fans 4a and 4b are partitioned by a partition plate 14 having an open hole.

The two outdoor fans 4a, 4
By controlling ON / OFF of b and the condensers 2a and 2b in combination as shown in the table below, the condensing capacity is varied in multiple stages.

[0032]

[Table 1]

That is, the gun motors FM1 and F1 are controlled by the level of the outside air noise detected by the outside air temperature sensor (not shown).
By controlling the operation of M2 and the opening / closing of solenoid valves EV1 and EV2, the condensation capacity of the outdoor unit can be varied in multiple stages.

According to this embodiment, the condensing capacity can be varied in multiple stages depending on the outside air temperature, which enables stable cooling operation from high temperature to low temperature.

[0035]

Since the present invention has the above-mentioned structure,
According to the first aspect of the present invention, with a simple configuration such as simply adding a changeover switch, there is little risk of freezing of the evaporator and the addition of refrigerant into the refrigeration cycle during low ambient temperature operation in long piping. It can be used as an unnecessary air conditioner.

According to the second aspect of the present invention, in the low outside air cooling during short piping, the conventional bypass prevents liquid back and protects the compressor, and in the low outside air cooling during long piping. In addition, the freezing of the evaporator is reduced and the addition of a refrigerant is not required to improve the operating efficiency, thereby obtaining the conventional cooling capacity, and the length of the connecting pipe is about 3 to 20 m, which is low from short pipe to long pipe. The air conditioner can be used for cooling the outside air temperature.

Further, according to the invention of claim 3,
The condensing capacity can be varied in multiple stages depending on the outside air temperature, which enables stable cooling operation from high temperature to low temperature.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle diagram showing a main part of a first embodiment.

FIG. 2 is a refrigeration cycle diagram showing a main part of a second embodiment.

FIG. 3 is also a flowchart.

FIG. 4 is a refrigeration cycle diagram showing a main part of a third embodiment.

FIG. 5 is a refrigeration cycle diagram showing a conventional example.

[Explanation of symbols]

1 compressor 2 condenser 3 capillary tubes 4 evaporator 5 outdoor fans 7 Capillary tube for bypass 8 two-way valve 9 Bypass pipe 10 Pressure switch 11 Changeover switch 12 Temperature sensor 13 Control unit

Claims (3)

[Claims] 1. An outdoor fan capable of switching the operating state according to the outside air temperature, and a bypass pipe for bypassing the refrigerant from the discharge side of the compressor to the outlet side of the condenser during low outside air temperature operation. In an air conditioner provided with a capillary tube and a two-way valve, a bypass pipe is passed in the middle of the wiring that detects the discharge pressure of the compressor and sends an open / close signal to the two-way valve, depending on the length of the refrigeration cycle pipe. An air conditioner having a changeover switch for controlling a bypass flow of a refrigerant. 2. An outdoor fan capable of switching the operating state according to the outside air temperature, and a bypass pipe for bypassing the refrigerant from the discharge side of the compressor to the outlet side of the condenser during low outside temperature operation, the bypass pipe being provided. An air conditioner provided with a capillary tube and a two-way valve in which a controller for detecting the temperature of the evaporator and controlling the opening and closing of the two-way valve is provided. 3. A refrigeration cycle in which a plurality of condensers are divided in parallel and arranged in parallel, and an opening / closing valve is provided in each inlet side pipe of each condenser, and a blowing capacity provided so as to face each condenser. And an outdoor fan of different types, and an air conditioner comprising a condensing capacity control device for controlling the operation of the outdoor fan and opening / closing of a corresponding condenser opening / closing valve in conjunction with each other.