JPH08271100A - Air conditioner - Google Patents

Abstract

PURPOSE: To make the size of an outdoor unit smaller, and prevent a decline in heating capacity of an air conditioner without spoiling the effect of a reduction in the number of connecting wirings between indoor and outdoor units even if the air conditioner is such a type that a compressor is installed in the indoor unit, by a method wherein defrosting of an outdoor heat exchanger can be performed without providing an exclusive signal line between the indoor and outdoor units to detect frosting. CONSTITUTION: An indoor unit A is provided with a compressor 1 and a four- way valve 2 in addition to an indoor heat exchanger 11 and an indoor fan 13. An outdoor unit B is equipped with a capillary tube 6 in addition to an outdoor heat exchanger 5 and an outdoor fan 14. Frosting of the outdoor unit B is detected from operating conditions of a refrigerating cycle in the indoor unit A. When frosting is detected, defrosting operation for the outdoor heat exchanger 5 is carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having an indoor unit and an outdoor unit, the indoor unit having a compressor.

[0002]

2. Description of the Related Art An air conditioner constitutes a refrigeration cycle in which a compressor, a four-way valve, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger are sequentially connected to form a refrigerant discharged from the compressor from the four-way valve to the outdoor heat exchanger. Perform cooling operation by circulating through the exchanger, expansion mechanism, and indoor heat exchanger, and circulate the refrigerant discharged from the compressor through the four-way valve through the indoor heat exchanger, expansion mechanism, and outdoor heat exchanger. The heating operation is executed by.

The compressor and the four-way valve are provided in the outdoor unit together with the outdoor heat exchanger, the expansion mechanism, and the outdoor blower, and the indoor unit is generally provided with the indoor heat exchanger and the indoor blower.

Recently, an air conditioner in which a compressor and a four-way valve are provided in an indoor unit instead of an outdoor unit has been developed and put into practical use. In the case of this air conditioner,
The compressor and the compressor drive circuit are eliminated from the outdoor unit, and electrical parts having the same function can be integrated indoors and outdoors, so that the outdoor unit can be downsized without increasing the size of the indoor unit. There is. Also, the number of crossovers (signal lines) from the indoor unit to the compressor drive circuit can be reduced.

[0005]

When the heating operation is carried out,
Frost gradually adheres to the surface of the outdoor heat exchanger functioning as an evaporator, and if it remains as it is, the heat exchange amount of the outdoor heat exchanger decreases and the heating capacity decreases.

Therefore, control is performed to detect defrosting of the outdoor heat exchanger by, for example, attaching a temperature sensor to the outdoor heat exchanger, and execute defrosting operation for the outdoor heat exchanger at the time of detection.

However, in the case of an air conditioner in which a compressor and a four-way valve are provided in an indoor unit, it is possible to reduce the size of the outdoor unit by providing the operation control unit only in the indoor unit. The outdoor unit provided in the outdoor unit becomes large.

Further, when the control unit of the temperature sensor is not provided in the outdoor unit, the signal line of the temperature sensor is provided between the indoor unit and the outdoor unit, which impairs the great advantage that the number of crossovers can be reduced. Get lost.

The present invention takes the above circumstances into consideration,
Even if the air conditioner has a compressor installed in the indoor unit,
The outdoor unit can be made smaller, and the outdoor heat exchanger can be defrosted without providing a dedicated signal line for detecting frost formation between the indoor unit and the outdoor unit. The purpose is to prevent a decrease in heating capacity while maintaining the effect of reducing the number of crossovers to and from the unit.

[0010]

An air conditioner according to a first aspect of the invention includes a refrigeration cycle in which a compressor, a four-way valve, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger are sequentially connected, and is provided in an indoor unit. An indoor heat exchanger and an indoor blower having the compressor and a four-way valve, and an outdoor unit having an expansion mechanism together with the outdoor heat exchanger and the outdoor blower,
A control means is provided which detects frost formation on the outdoor heat exchanger from the refrigeration cycle state in the indoor unit and executes a defrosting operation on the outdoor heat exchanger.

In the air conditioner of the second invention, in the first invention, the expansion mechanism is a capillary tube, and a two-way valve for bypassing the capillary tube is connected in parallel with the capillary tube, The control means opens the two-way valve and stops the outdoor blower during the defrosting operation.

In the air conditioner of the third aspect of the present invention, in the first aspect of the present invention, the control means detects the temperature Tc at the intermediate position of the indoor heat exchanger and the indoor temperature Ta after a lapse of a predetermined time from the start of operation and detects both detected temperatures. Of the temperature difference ΔT, the maximum value ΔTmax of the temperature difference ΔT is sequentially updated and stored, and the maximum value ΔTmax
Difference D between the temperature difference ΔT and the temperature difference ΔT, and the temperature difference D is a predetermined value D
When it exceeds s, the defrosting operation is started.

In the air conditioner of the fourth invention, in the third invention, the control means corrects the obtained temperature difference ΔT according to the air volume of the indoor blower and the capacity of the compressor. In the air conditioner of a fifth aspect of the invention, in the third or fourth aspect of the invention, the control means causes the temperature T at the intermediate position of the indoor heat exchanger during the defrosting operation.
c is detected, the minimum value Tcmin of the detected temperature Tc is sequentially updated and stored, and a difference ΔTc between the minimum value Tcmin and the detected temperature Tc is obtained. The temperature difference ΔTc is a predetermined value ΔTco.
When the temperature exceeds, the defrosting operation is terminated.

In the air conditioner of the sixth invention, in the first invention, the control means detects the discharge refrigerant temperature Td of the compressor after a predetermined time from the start of operation, and sequentially detects the maximum value Tdmax of the detected temperature Td. Maximum value Tdmax
The difference D between the detected temperature Td and the detected temperature Td is obtained, and when the temperature difference D exceeds the predetermined value Ds, the defrosting operation is started.

In the air conditioner of the seventh invention, in the sixth invention, the control means detects the refrigerant discharge temperature Td of the compressor during the defrosting operation, and successively detects the minimum value Tdmin of the detected temperature Td. The minimum value Tdmin and the detected temperature T are updated and stored.
The difference ΔTd from d is obtained, and the temperature difference ΔTd is a predetermined value ΔT.
When it exceeds do, the defrosting operation is terminated.

In the air conditioner of an eighth aspect of the present invention, in the first aspect of the present invention, the control means detects the suction refrigerant temperature Ts of the compressor after a predetermined time from the start of operation, and sequentially detects the maximum value Tsmax of the detected temperature Ts. Maximum value Tsmax
The difference D between the detected temperature Td and the detected temperature Td is obtained, and when the temperature difference D exceeds the predetermined value Ds, the defrosting operation is started.

In the air conditioner of the ninth invention, in the eighth invention, the control means detects the suction refrigerant temperature Ts of the compressor during the defrosting operation, and the detected temperature Ts exceeds a predetermined value Tso. When the defrosting operation ends.

The air conditioner of the tenth invention is the air conditioner according to any one of the first to ninth inventions, wherein the four-way valve is a direct-acting four-way valve in which the flow paths are switched by changing the polarity of the applied voltage. .

[0019]

In the air conditioner of the first aspect of the present invention, frost formation on the outdoor heat exchanger is detected from the refrigeration cycle state inside the indoor unit, and when the frost formation is detected, the defrosting operation on the outdoor heat exchanger is executed.

In the air conditioner of the second aspect of the present invention, frost formation on the outdoor heat exchanger is detected from the refrigeration cycle state in the indoor unit, and when the frost formation is detected, the defrosting operation on the outdoor heat exchanger is executed. During this defrosting operation, the two-way valve is opened to bypass the capillary tube that is the expansion mechanism, and the outdoor blower is stopped.

In the air conditioner of the third invention, the temperature Tc at the intermediate position of the indoor heat exchanger and the indoor temperature Ta are detected after a predetermined time from the start of operation, the difference ΔT between the detected temperatures is obtained, and the temperature difference is obtained. While the maximum value ΔTmax of ΔT is sequentially updated and stored, the difference D between the maximum value ΔTmax and the temperature difference ΔT is obtained, and when the temperature difference D exceeds the predetermined value Ds, the defrosting operation for the outdoor heat exchanger is started. To be done.

In the air conditioner of the fourth invention, the temperature difference ΔT obtained in the third invention is corrected according to the air volume of the indoor blower and the capacity of the compressor. In the air conditioner of the fifth invention, in the third or fourth invention, the temperature Tc at the intermediate position of the indoor heat exchanger is detected during the defrosting operation,
While the minimum value Tcmin of the detected temperature Tc is sequentially updated and stored, the difference ΔTc between the minimum value Tcmin and the detected temperature Tc.
When the temperature difference ΔTc exceeds the predetermined value ΔTco, the defrosting operation is ended.

In the air conditioner of the sixth invention, the temperature Td of the refrigerant discharged from the compressor is detected after a predetermined time from the start of operation,
The maximum value Tdmax of the detected temperature Td is sequentially updated and stored, and a difference D between the maximum value Tdmax and the detected temperature Td is obtained. When the temperature difference D exceeds a predetermined value Ds, defrosting of the outdoor heat exchanger is performed. The operation is started.

In the air conditioner of the seventh invention, in the sixth invention, the refrigerant discharge temperature Td of the compressor is detected during the defrosting operation, and the minimum value Tdmin of the detected temperature Td is sequentially updated and stored. A difference ΔTd between the minimum value Tdmin and the detected temperature Td is obtained, and the temperature difference ΔTd is a predetermined value ΔTd.
When it exceeds o, the defrosting operation is terminated.

In the air conditioner of the eighth invention, the suction refrigerant temperature Ts of the compressor is detected after a lapse of a predetermined time from the start of operation,
The maximum value Tsmax of the detected temperature Ts is sequentially updated and stored, and a difference D between the maximum value Tsmax and the detected temperature Td is obtained. When the temperature difference D exceeds a predetermined value Ds, defrosting of the outdoor heat exchanger is performed. The operation is started.

In the air conditioner of the ninth invention, in the eighth invention, the suction refrigerant temperature Ts of the compressor is detected during the defrosting operation, and when the detected temperature Ts exceeds a predetermined value Tso, the defrosting operation is performed. Is ended.

In the air conditioner of the tenth invention, in any one of the first to ninth inventions, the flow path of the four-way valve is switched by changing the polarity of the voltage applied to the four-way valve.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 2, one end of an outdoor heat exchanger 5 is connected to the discharge port of the variable capacity compressor 1 through a four-way valve 2, an indoor packed valve 3 and an outdoor packed valve 4 by piping. One end of the indoor heat exchanger 11 is connected to the other end of the outdoor heat exchanger 5 through an expansion mechanism such as a capillary tube 6, an outdoor packed valve 9, and an indoor packed valve 10 so as to be piped. Then, the other end of the indoor heat exchanger 11 is connected to the suction port of the compressor 1 through the four-way valve 2 by piping. Thus, the heat pump type refrigeration cycle is configured.

During cooling, the refrigerant discharged from the compressor 1 flows to the four-way valve 2, the outdoor heat exchanger 5, the capillary tube 6 and the indoor heat exchanger 11 as shown by the solid arrow, and the indoor heat exchange is performed. The refrigerant having passed through the container 11 is sucked into the compressor 1 through the four-way valve 2. That is, the outdoor heat exchanger 5 functions as a condenser, and the indoor heat exchanger 11 functions as an evaporator. During heating, the flow path of the four-way valve 2 is switched, so that the refrigerant discharged from the compressor 1 is the four-way valve 2, the indoor heat exchanger 11, the capillary tube 6, the outdoor heat exchanger, as indicated by the dashed arrow. The refrigerant that has flowed to the outdoor heat exchanger 5 flows to the four-way valve 2
And is sucked into the compressor 1 through. That is, the indoor heat exchanger 11 functions as a condenser, and the outdoor heat exchanger 5 functions as an evaporator.

The four-way valve 2 is a direct-acting type in which the flow paths are switched by changing the polarity of the applied voltage, and a specific example is shown in FIG. That is, the four-way valve 2 includes a hollow main body 20, and four ports 21, 22, 2 provided in the main body 20.
3, 24, a movable valve seat 25 provided in the main body 20 for forming a two-system flow path between the ports, the movable valve seat 2
5 is composed of a permanent magnet type plunger 27 connected to the No. 5 via a rod 26 and a solenoid 28 provided around the plunger 27. When a voltage V is applied to the solenoid 28, the movable valve seat 25 moves to move between ports. The two systems of flow paths are switched.

In the illustrated state, one flow path is formed between the ports 22 and 23 through the inner space of the movable valve seat 25,
Another flow path is formed between the ports 21 and 24 through the outer space of the movable valve seat 25. The flow path between the ports 22 and 23 is the discharge port of the compressor 1 and the packed pallet 3 on the indoor side.
It is used as a high-pressure side channel that communicates with. Port 2
The flow path between 1 and 24 is used as a low pressure side flow path that connects the indoor heat exchanger 11 and the suction port of the compressor 1. This is a cooling cycle.

In this state, when the positive (+) polarity pulsed voltage V shown in FIG. 4 is applied, the movable valve seat 25 moves to the left in the drawing, and the flow path passing through the inner space of the movable valve seat 25 becomes a port. Two
A passage formed between the ports 1 and 22 and passing through the outer space of the movable valve seat 25 is formed between the ports 23 and 24. In this case, the flow path between the ports 21 and 22 serves as a high-pressure side flow path that communicates the discharge port of the compressor 1 with the indoor packed valve 3, and the flow path between the ports 23 and 24 is the indoor heat exchanger 11 and the compressor. The low pressure side flow path communicates with the suction port of No. 1 and forms a cycle during heating. In this state, when the negative (-) polarity pulsed voltage V shown in FIG. 4 is applied, the movable valve seat 25 moves to the right in the drawing, and the cycle for cooling is restored.

On the other hand, a series body of the two-way valve 7 and the check valve 8 is connected in parallel with the capillary tube 6 by piping. The two-way valve 7 and the check valve 8 are for bypassing the flow of the refrigerant to the capillary tube 6 during the defrosting operation on the outdoor heat exchanger 5.

An outdoor blower 14 is provided near the outdoor heat exchanger 5.
Is provided. The outdoor blower 14 circulates outdoor air through the outdoor heat exchanger 5. An indoor blower 13 is provided near the indoor heat exchanger 11. This indoor blower 1
3 circulates indoor air through the indoor heat exchanger 11.

A heat exchanger temperature (Tc) sensor 12 is attached at a substantially intermediate position of the indoor heat exchanger 11. A refrigerant temperature (Td) sensor 15 is attached to the discharge side pipe of the compressor 1. A refrigerant temperature (Ts) sensor 16 is attached to the suction side pipe of the compressor 1.

Reference numeral A denotes an indoor unit installed indoors, in which the compressor 1, the four-way valve 2 and the indoor heat exchanger 1 are installed.
1, and an indoor blower 13 are provided. Reference numeral B denotes an outdoor unit installed outdoors, in which the outdoor heat exchanger 5, the capillary tube 6, the two-way valve 7, and the check valve 8 are provided.
Is provided.

The control circuit is shown in FIG. Commercial AC power supply 30
In addition, the control unit 35 of the indoor unit A, the fan tap switching circuit 40, the inverter circuit 50, and the low voltage drive circuit 6
0 is connected.

The fan tap switching circuit 40 includes speed switching taps (strong wind taps) of the motor 13M of the indoor blower 13.
Switch between energization for weak wind taps and light wind taps.
The inverter circuit 50 rectifies the power supply voltage by the rectification circuit 51, chops the rectified output by the switching circuit 52, converts the rectified output into an AC voltage having a predetermined frequency and level, and outputs the AC voltage. This output consists of three phase voltages that switch at the above-mentioned predetermined frequency, and these phase voltages are sequentially applied to each phase winding U, V, W of the compressor motor 1M.

The compressor motor 1M is a brushless DC motor consisting of a rotor having permanent magnets mounted thereon and a stator having three phase windings U, V and W mounted thereon. The rotor is rotated by sequentially applying voltage to the rotor. Switching of voltage application to the phase windings U, V, W is called commutation, and the rotation of the compressor motor 1M is continued by repeating this commutation.

A drive circuit 53 is connected to the inverter circuit 50 and the compressor motor 1M. Drive circuit 5
3 adjusts the ON period of each switching element of the switching circuit 52 according to the rotation speed command from the control unit 35 (P
WM modulation) controls the level of the applied voltage to each phase winding U, V, W, and thereby controls the rotation speed (speed) of the compressor motor 1M.

The drive circuit 53 is a compressor motor 1M.
Of the respective phase windings U, V, W, the voltage induced in the non-energized phase winding is taken in, the rotational position of the rotor of the compressor motor 1M is detected from the taken-in voltage, and the detected position is determined according to the detected position. Then, the on / off timing of each switching element of the switching circuit 52, that is, the chopping frequency is controlled. By controlling the chopping frequency, each phase winding is energized at the optimum timing according to the rotation speed of the compressor motor 1M.

The low voltage drive circuit 60 comprises a step-down transformer 61.
And a rectifying circuit 62, and outputs a DC low voltage (less than 42 V) for driving the outdoor blower 14 and the two-way valve 7. A DC power supply line DCL composed of a positive side (+) line and a negative side (−) line is connected to the output terminal of the low voltage drive circuit 60. This DC power line DCL is the indoor unit A
To the outdoor unit B.

The control section 35 is equipped with a microcomputer and carries out overall control of the air conditioner. The control unit 35 includes a four-way valve 2, a heat exchanger temperature sensor 12,
Refrigerant temperature sensors 15 and 16, room temperature (Ta) sensor 3
6, the relays 31 and 32, the light receiving unit 33, the fan tap switching circuit 40, and the drive circuit 53 are connected.

The relay 32 is for controlling the drive voltage supply to the outdoor blower 14 and the two-way valve 7 of the outdoor unit B, and has normally open contacts 32a, 32a. These normally open contacts 32a, 32a extend from the indoor unit A to the outdoor unit B
Inserted into L.

In the DC power supply line DCL of the indoor unit A, the positive side (+) of the position downstream of the contacts 32a, 32a.
The control signal line CL is connected to the line, and the normally-open contact 31a of the relay 31 is connected to the control signal line CL. The control signal line CL extends from the indoor unit A to the outdoor unit B.

The light receiving section 33 receives infrared light emitted from a remote control type operation device (hereinafter, abbreviated as remote controller) 34. On the other hand, in the outdoor unit B, the movable terminal of the bidirectional contact 70a is connected to the positive (+) line of the DC power supply line DCL. One end of the blower motor 14M of the outdoor blower 14 is connected to the normally closed side fixed terminal of the bidirectional contact 70a, and the two-way valve 7 is connected to the normally open side fixed terminal.
One end of is connected. The other ends of the blower motor 14M and the two-way valve 7 are connected to the negative side (−) line of the DC power supply line DCL.

In the outdoor unit B, one end of the relay 70 is connected to the control signal line CL extending from the indoor unit A, and the other end of the relay 70 is connected to the negative side (-) line of the DC power supply line DCL. To be done.

The relay 70 has the above-mentioned bidirectional contact 70a, and alternates one of the energization paths from the low voltage drive circuit 60 to the blower motor 14M and the energization path to the two-way valve 7. Function as an energization switching means for forming the same.

The control section 31 has the following [1] as a main functional means. [1] Control for detecting frost formation on the outdoor heat exchanger 5 of the outdoor unit B from the refrigeration cycle state inside the indoor unit A during heating operation, and executing defrosting operation on the outdoor heat exchanger 5 when the frost formation is detected means.

Next, the operation of the above structure will be described. It is assumed that the cooling mode and the desired room temperature are set by the remote controller 34 and the operation start operation is performed.

In this case, if the detected temperature (indoor temperature) Ta of the indoor temperature sensor 36 is higher than the set indoor temperature based on the operation of the remote controller 34, the inverter circuit 50 is driven to start the operation of the compressor 1 and the compressor 1 The refrigerant discharged from 1 flows to the four-way valve 2, the outdoor heat exchanger 5, the capillary tube 6, and the indoor heat exchanger 11, and the refrigerant passing through the indoor heat exchanger 11 is sucked into the compressor 1 through the four-way valve 2. Get caught

Further, the fan tap switching circuit 40 energizes an arbitrary speed switching tap of the blower motor 13M to start the operation of the indoor blower 13. In this case, if the air volume "strong" is set by the remote controller 34, the speed switching tap for strong wind is energized, the blower motor 13M operates at a high rotation speed, and the indoor blower 13 operates in strong wind. If the air volume "weak" is set by the remote controller 34, the speed changing tap for the weak wind is energized, the blower motor 13M operates at a medium rotation speed, and the indoor blower 13 is operated in the weak wind. . When the air volume "fine" is set by the remote controller 34, the speed change tap for the slight wind is energized, the blower motor 13M operates at a low rotation speed, and the indoor blower 13 operates in a slight wind.

Further, the relay 32 is energized to contact the contact 32.
a and 32a are closed, the relay 31 is de-energized and the contact 31a
Is opened, whereby an energization path is formed from the low voltage drive circuit 60 of the indoor unit A to the blower motor 14M of the outdoor unit B, and the operation of the outdoor blower 14 is started.

In this way, the outdoor heat exchanger 5 functions as a condenser and the indoor heat exchanger 11 functions as an evaporator, and the outdoor blower 14 and the indoor blower 1 are provided for each heat exchanger.
The air-conditioning operation is started by blowing the air of 3.

During this cooling operation, the difference between the detected temperature Ta of the indoor temperature sensor 36 and the set indoor temperature is obtained, and the operating frequency of the compressor 1 (the inverter circuit 50 is determined according to the temperature difference.
Output frequency) F is controlled. By this capacity control of the compressor 1, the cooling capacity corresponding to the air conditioning load is exerted.

When the heating mode is set by the remote controller 34, the four-way valve 2 is switched. If the detected temperature (indoor temperature) Ta of the indoor temperature sensor 36 is lower than the set indoor temperature based on the operation of the remote controller 34, the inverter circuit 50 is driven to start the operation of the compressor 1 and the compressor 1
The discharged refrigerant flows to the four-way valve 2, the indoor heat exchanger 11, the capillary tube 6, and the outdoor heat exchanger 5, and the refrigerant passing through the outdoor heat exchanger 5 is sucked into the compressor 1.

Further, the fan tap switching circuit 40 energizes an arbitrary speed switching tap of the blower motor 13M to operate the indoor blower 13. Moreover, the relay 32 is energized, the relay 31 is deenergized, and the outdoor blower 14 is operated.

In this way, the indoor heat exchanger 11 functions as a condenser and the outdoor heat exchanger 5 functions as an evaporator, and the outdoor blower 14 and the indoor blower 1 are provided for each heat exchanger.
The heating operation is started by blowing the air of 3.

During this heating operation, the difference between the detected temperature Ta of the indoor temperature sensor 36 and the set indoor temperature is obtained, and the operating frequency F of the compressor 1 is controlled according to the temperature difference. By controlling the capacity of the compressor 1, the heating capacity corresponding to the air conditioning load is exhibited.

By the way, as the heating operation progresses, frost gradually adheres to the surface of the outdoor heat exchanger 5 functioning as an evaporator, and if the frost is left as it is, the heat exchange amount of the outdoor heat exchanger 5 decreases and the heating capacity is increased. Will decrease. In order to prevent this problem, the control shown in FIGS. 5 and 6 is executed.

At the same time when the heating operation is started, the time count t
Is started, and a predetermined time t based on the time count t
After _one , the temperature detected by the heat exchanger temperature sensor 12 (the temperature at the intermediate position of the indoor heat exchanger 11) Tc and the temperature detected by the indoor temperature sensor 36 (room temperature) Ta are taken in, and the difference ΔTca (= Tca (= Tc-Ta) is required. Predetermined time t
₁ is the time until the heating operation stabilizes (for example, 10 minutes)
Is.

Maximum value ΔTc of the obtained temperature difference ΔTca
While amax is updated and stored sequentially, the maximum value ΔTcam
difference between x and temperature difference ΔTca D (= ΔTcamax −ΔTc
a) is required. The temperature difference D is compared with the predetermined value Ds, and when the temperature difference D exceeds the predetermined value Ds, it is determined that the outdoor heat exchanger 5 is frosted.

That is, when frost forms on the outdoor heat exchanger 5,
The amount of heat pumped up from the outdoor heat exchanger 5 is reduced. The decrease in the amount of heat pumped up due to this frost is indirectly caught from the decrease in the temperature of the indoor heat exchanger 11.

However, considering that the temperature of the indoor heat exchanger 11 is affected by the air volume of the indoor blower 13 and the capacity of the compressor 1, the temperature difference ΔTca is the rotation speed of the blower motor 13M as shown in the following equation. And is corrected according to the rotation speed of the compressor motor 1M. This correction value ΔTca ′ is actually used. C is a constant.

ΔTca ′ = ΔTca · C · (Blower motor rotation speed / Compressor motor rotation speed) When frost formation is determined, the relay 31 is energized. When the relay 31 is energized, the contact 31a is closed and the relay 70 of the outdoor unit B is energized. When the relay 70 is energized, the bidirectional contact 70a is switched, and the blower motor 14
The power supply path to M is cut off and a new power supply path to the two-way valve 7 is formed.

In this way, the two-way valve 7 is opened, a bypass passage for the capillary tube 6 is formed, and the indoor heat exchanger 11 and the outdoor heat exchanger 5 are directly connected through the bypass passage. At the same time, the outdoor blower 14 is stopped and the air blow to the outdoor heat exchanger 5 is stopped. In the indoor unit A, the operating frequency F of the compressor ₁ is set to the predetermined value Fd ₁ for defrosting, and the indoor blower 13 is stopped to stop the air blow to the room.

Therefore, the high-temperature refrigerant discharged from the compressor 1 flows to the outdoor heat exchanger 5 without being deprived of much heat by the indoor heat exchanger 11, and the heat of the high-temperature refrigerant is defrosted by the outdoor heat exchanger 5. As effectively used.

Even during the defrosting operation, the temperature Tc detected by the heat exchanger temperature sensor 12 is taken in, and the minimum value T of the detected temperature Tc is obtained.
The difference ΔTc (= Tc-Tcmin) between the minimum value Tcmin and the detected temperature Tc is obtained while cmin is sequentially updated and stored.

This temperature difference ΔTc is compared with a predetermined value ΔTco, and when the temperature difference ΔTc exceeds the predetermined value ΔTco,
Relay 31 is de-energized. When the relay 35 is de-energized,
The contact 35a is opened and the relay 70 of the outdoor unit B is deenergized. When the relay 70 is de-energized, the bidirectional contact 70
a is restored, the power supply path to the two-way valve 7 is cut off, and the power supply path to the blower motor 14M is formed again. That is,
The defrosting operation ends and the normal heating operation is resumed.

Thereafter, when an instruction to stop the operation is given by the remote controller 34, or the detected temperature Ta of the indoor temperature sensor 36.
Has reached the set room temperature, the drive of the inverter circuit 50 is stopped and the operation of the compressor 1 is stopped.

In this way, by detecting the frost formation of the outdoor heat exchanger 5 on the indoor unit A side, a dedicated signal line for defrost detection is provided between the indoor unit A and the outdoor unit B. Therefore, the outdoor heat exchanger 5 can be reliably defrosted. Therefore, it is possible to prevent a decrease in heating capacity while maintaining the advantage of providing the compressor 1 in the indoor unit A, that is, the effect of reducing the number of connecting wires between the indoor unit A and the outdoor unit B.

Moreover, since the compressor 1 is present in the indoor unit A, the amount of heat leaked to the outside through the case of the compressor 1 is smaller than that in the outdoor unit B, and that amount is effectively used as defrosting heat. Therefore, the defrosting time can be shortened. The shorter the defrosting time, the longer the heating operation execution time.

By the way, as a defrosting method, reverse cycle defrosting (the same cycle as during cooling) in which the four-way valve is reversed to reverse the flow of the refrigerant is generally used. In that case, the freezing is performed when the four-way valve is reversed. High-pressure gas flows from the high-pressure side to the low-pressure side of the cycle, and a large refrigerant noise is generated.

However, in this embodiment, considering that the four-way valve 2 exists in the indoor unit A, the two-way valve 7 is opened and the capillary tube 6 is opened without switching the four-way valve 2 while keeping the flow direction of the refrigerant. Quiet defrosting that only bypasses is performed, and the loud refrigerant noise that occurs during reverse cycle defrosting is not generated. This silent defrosting does not make people indoors feel uncomfortable.

Since the flow direction of the refrigerant does not change even after the defrosting is completed, the return to the heating is smooth and the heating rise thereafter becomes good. Further, since the four-way valve 2 is a direct-acting type in which the flow path is switched by changing the polarity of the applied voltage V, that is, a type that does not operate unless the voltage V is applied, the power is turned off when the heating operation is stopped. However, the flow path of the four-way valve 2 is not switched, and the generation of refrigerant noise can be prevented in this respect as well.

In the above embodiment, the indoor blower 13 was stopped during the defrosting operation. However, as shown in FIG. 7, the indoor blower 13 is operated during the defrosting operation so that the indoor ventilation is continued. May be. In this case, considering that the heat of the refrigerant is released not only as defrosting heat in the outdoor heat exchanger 5 but also as heating heat in the indoor heat exchanger 11, the operating frequency F of the compressor 1 is set to the above predetermined value. It is set to Fd ₂ which is higher than Fd ₁ to enhance the compression function force. Further, in this case, after the operating frequency F reaches the high Fd ₂ , the two-way valve 7 is opened to start the substantial defrosting, and the outdoor blower 14 is stopped to moderate the pressure fluctuation in the refrigeration cycle. Is delayed by a predetermined time to.

Next, a second embodiment of the present invention will be described. In the second embodiment, the control shown in FIG. 8 is performed. Other configurations and operations are the same as those in the first embodiment.

At the same time when the heating operation is started, the time count t
Is started, and a predetermined time t based on the time count t
After ₁ , the temperature detected by the refrigerant temperature sensor 15 (the discharged refrigerant temperature)
The maximum value ΔTdma of the detected temperature Td is obtained by taking in Td.
While x is sequentially updated and stored, the difference D (= ΔTdmax-ΔTd) between the maximum value ΔTdmax and the detected temperature Td is obtained. The predetermined time t ₁ is the time until the heating operation stabilizes.

The obtained temperature difference D and the predetermined value Ds are compared, and when the temperature difference D exceeds the predetermined value Ds, it is determined that the outdoor heat exchanger 5 is frosted. That is, when frost forms on the outdoor heat exchanger 5, the amount of heat pumped up by the outdoor heat exchanger 5 decreases. The decrease in the pumping heat amount due to the frost formation is indirectly caught from the decrease in the refrigerant discharge temperature Td of the compressor 1.

When the frost formation is determined, the relay 31 is energized to start the defrosting operation for the outdoor heat exchanger 5. Even during the defrosting operation, the detected temperature Td of the refrigerant temperature sensor 15 is taken in, and the minimum value Tdmin of the detected temperature Td is sequentially updated and stored, while the difference ΔTd (= Td-Tdmin) between the minimum value Tdmin and the detected temperature Td. Is required.

This temperature difference ΔTd is compared with a predetermined value ΔTdo, and when the temperature difference ΔTd exceeds the predetermined value ΔTdo,
Relay 31 is de-energized. As a result, the defrosting operation ends and the normal heating operation is resumed.

The effect is the same as that of the first embodiment.
A third embodiment of the present invention will be described. In the third embodiment, the control shown in FIG. 9 is performed. Other configurations and operations are the same as those in the first embodiment.

At the same time when the heating operation is started, the time count t
Is started, and a predetermined time t based on the time count t
After ₁ , the temperature detected by the refrigerant temperature sensor 16 (suction refrigerant temperature)
Ts is taken in and the maximum value ΔTsma of the detected temperature Ts is obtained.
While x is sequentially updated and stored, the difference D (= ΔTsmax-ΔTs) between the maximum value ΔTsmax and the detected temperature Ts is obtained. The predetermined time t ₁ is the time until the heating operation stabilizes.

The obtained temperature difference D and the predetermined value Ds are compared, and when the temperature difference D exceeds the predetermined value Ds, it is determined that the outdoor heat exchanger 5 is frosted. That is, when frost forms on the outdoor heat exchanger 5, the amount of heat pumped up by the outdoor heat exchanger 5 decreases. The decrease in the pumping heat amount due to the frost is indirectly caught from the decrease in the suction refrigerant temperature Ts of the compressor 1.

When the frost formation is determined, the relay 31 is energized to start the defrosting operation for the outdoor heat exchanger 5. Even during the defrosting operation, the temperature Ts detected by the refrigerant temperature sensor 16 is taken in and the detected temperature Ts is compared with the predetermined value Tso. When the detected temperature Ts exceeds a predetermined value Tso, the relay 3
1 is deactivated. As a result, the defrosting operation ends and the normal heating operation is resumed. The effect is the same as in the first embodiment.

[0086]

As described above, according to the present invention, the frost formation of the outdoor heat exchanger is detected from the refrigeration cycle state in the indoor unit, and the defrosting operation for the outdoor heat exchanger is executed. Even if the air conditioner has a compressor installed in the indoor unit, it is possible to defrost the outdoor heat exchanger without providing a dedicated signal line for detecting frost formation between the indoor unit and the outdoor unit. As a result, it is possible to further reduce the size of the outdoor unit and prevent the decrease in heating capacity while maintaining the effect of reducing the number of connecting wires between the indoor unit and the outdoor unit.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a control circuit of each embodiment.

FIG. 2 is a diagram showing a configuration of a refrigeration cycle of each example.

3 is a cross-sectional view showing a specific configuration of the four-way valve in FIG.

FIG. 4 is a time chart for explaining the operation of the four-way valve in FIG.

FIG. 5 is a time chart for explaining the operation during the defrosting operation of the first embodiment.

FIG. 6 is a flowchart for explaining the operation of the first embodiment.

FIG. 7 is a time chart for explaining a modified example of the operation during the defrosting operation of the first embodiment.

FIG. 8 is a flowchart for explaining the operation of the second embodiment.

FIG. 9 is a flowchart for explaining the operation of the third embodiment.

[Explanation of symbols]

1 ... Variable capacity compressor, 2 ... Four-way valve, 5 ... Outdoor heat exchanger,
6 ... Capillary tube (expansion mechanism), 7 ... Two-way valve, 8
... Check valve, 11 ... Indoor heat exchanger, 12 ... Heat exchanger temperature sensor, 13 ... Indoor blower, 14 ... Outdoor blower, 15, 1
6 ... Refrigerant temperature sensor, 31, 32 ... Relay, 35 ... Control part, 36 ... Indoor temperature sensor, 40 ... Fan tap switching circuit, 50 ... Inverter circuit, 51 ... Rectifier circuit, 52 ... Switching circuit, 53 ... Drive circuit, 60 ... Low voltage drive circuit, 70 ... Relay, 70a ... Bidirectional contact, A ... Indoor unit, B ... Outdoor unit.

Front page continued (72) Inventor Ueda K.K., 336 Tatehara, Fuji City, Shizuoka Prefecture, Toshiba Corporation Fuji Factory (72) Inventor Hidenori Ashikawa, 336, Tatehara, Fuji City, Shizuoka Prefecture Toshiba A & V Co., Ltd.

Claims (10)

[Claims] 1. A refrigeration cycle in which a compressor, a four-way valve, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger are sequentially connected,
An air conditioner having the indoor heat exchanger and the indoor blower together with the compressor and the four-way valve in the indoor unit, and the outdoor unit having the expansion mechanism together with the outdoor heat exchanger and the outdoor blower in the indoor unit. The air conditioner, comprising: a control unit that detects frost formation on the outdoor heat exchanger from the refrigeration cycle state and executes defrosting operation on the outdoor heat exchanger. 2. The air conditioner according to claim 1,
The expansion mechanism is a capillary tube, and a two-way valve for bypassing the capillary tube is connected in parallel with the capillary tube, and the control means opens the two-way valve during defrosting operation and the outdoor blower. An air conditioner characterized by stopping. 3. The air conditioner according to claim 1,
The control means detects the temperature Tc at the intermediate position of the indoor heat exchanger and the indoor temperature Ta after a lapse of a predetermined time from the start of operation, obtains a difference ΔT between the detected temperatures, and sequentially obtains the maximum value ΔTmax of the temperature difference ΔT. Same maximum value ΔTmax while updating and storing
Difference D between the temperature difference ΔT and the temperature difference ΔT, and the temperature difference D is a predetermined value D
An air conditioner characterized by starting defrosting operation when the temperature exceeds s. 4. The air conditioner according to claim 3,
The air conditioner, wherein the control means corrects the obtained temperature difference ΔT according to the air volume of the indoor blower and the capacity of the compressor. 5. The air conditioner according to claim 3 or 4, wherein the control means detects a temperature Tc at an intermediate position of the indoor heat exchanger during the defrosting operation, and detects the detected temperature Tc. An air conditioner characterized by terminating the defrosting operation when the difference ΔTc between the minimum value Tcmin and the detected temperature Tc is obtained while successively updating and storing the minimum value Tcmin, and the temperature difference ΔTc exceeds a predetermined value ΔTco. Machine. 6. The air conditioner according to claim 1,
The control means detects the discharge refrigerant temperature Td of the compressor after a predetermined time from the start of operation, and sequentially updates and stores the maximum value Tdmax of the detected temperature Td while maintaining the maximum value Tdmax.
And a detection temperature Td, and a defrosting operation is started when the temperature difference D exceeds a predetermined value Ds. 7. The air conditioner according to claim 6,
The control means detects the refrigerant discharge temperature Td of the compressor during the defrosting operation, and sequentially updates and stores the minimum value Tdmin of the detected temperature Td, and the minimum value Tdmin and the detected temperature Td.
The difference ΔTd from d is obtained, and the temperature difference ΔTd is a predetermined value ΔT.
An air conditioner characterized by terminating the defrosting operation when it exceeds do. 8. The air conditioner according to claim 1,
The control means detects the suction refrigerant temperature Ts of the compressor after a predetermined time from the start of the operation, and sequentially updates and stores the maximum value Tsmax of the detected temperature Ts while keeping the maximum value Tsmax.
And a detection temperature Td, and a defrosting operation is started when the temperature difference D exceeds a predetermined value Ds. 9. The air conditioner according to claim 8, wherein:
An air conditioner characterized in that the control means detects the suction refrigerant temperature Ts of the compressor during the defrosting operation and terminates the defrosting operation when the detected temperature Ts exceeds a predetermined value Tso. 10. The air conditioner according to any one of claims 1 to 9, wherein the four-way valve is a direct-acting four-way valve in which the flow paths are switched by changing the polarity of the applied voltage. A characteristic air conditioner.