JPH08291950A - Air conditioner - Google Patents

Abstract

PURPOSE: To prevent a flowing-out of cold air from an indoor heat exchanger during a defrosting operation and further prevent a liquid back-flow to a compressor by a method wherein there are provided a first expansion valve and a second expansion valve in a bypassing circuit bypassing an indoor heat exchanger and refrigerant flowing from the second expansion valve to the compressor during the defrosting operation is heated. CONSTITUTION: A refrigerant circuit 3 is provided with an opening or closing type expansion valve 8 and a bypass circuit 3g bypassing an indoor heat exchanger 9. The bypass circuit 3g is provided with an opening or closing type expansion valve 11 constituting a second expansion valve. A heat source device 7 is arranged between the opening or closing type expansion valve 11 and a four-way valve 5. During a defrosting operation, when the four-way valve 5 is changed-over, gaseous phase refrigerant of high temperature and high pressure discharged out of a compressor 2 and flowing in a refrigerant line 3a passes through the four-way valve 5, flows in the refrigerant line 3b and is fed to an outdoor heat exchanger 6. The gaseous refrigerant of high pressure fed for a defrosting operation at the outdoor heat exchanger 6 and liquified there flows in the bypass circuit 3g, its pressure is reduced by the opening or closing type expansion valve 11, its part is gasified and the refrigerant flows in the refrigerant line 3d toward the heat source device 7.

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 a defrosting operation mode.

[0002]

2. Description of the Related Art An air conditioner is constructed by providing at least a compressor, a four-way valve, an indoor heat exchanger, an expansion valve and an outdoor heat exchanger in a refrigerant circuit for circulating a refrigerant. The refrigerant circulates in the refrigerant circuit in the order of the compressor, the four-way valve, the indoor heat exchanger functioning as a condenser, the expansion valve and the outdoor heat exchanger functioning as an evaporator. Further, during the cooling operation, the refrigerant circulates through the refrigerant circuit in the order of the compressor, the four-way valve, the outdoor heat exchanger functioning as a condenser, the expansion valve and the indoor heat exchanger functioning as an evaporator.

Here, the basic cycle during the heating operation of the engine-driven air conditioner is shown in the Mollier diagram (P in FIG. 9).
-I diagram).

When the compressor is driven by the engine,
The state shown by in FIG. 9 (pressure P ₁ , enthalpy i ₁ ).
The gas-phase refrigerant is compressed by the compressor and becomes a high-temperature high-pressure refrigerant in the state (pressure P ₂ , enthalpy i ₂ ) shown in FIG. The required power of the compressor at this time (compression heat quantity)
AL is expressed by (i ₂ -i _1).

The high-temperature and high-pressure gas-phase refrigerant is guided to an indoor heat exchanger functioning as a condenser, where it condenses heat Q ₂ into the indoor air to be liquefied. The state of the liquid-phase refrigerant passing through the indoor heat exchanger is shown in FIG. 9 (pressure P ₂ , enthalpy i ₃ ).
The room is heated by the heat radiation amount Q ₂ (= i ₂ −i ₃ ). At this time, the refrigerant is supercooled (subcooled) by Δi _c shown in the figure. The subcool is set by setting a large heat radiation area or by setting the number of rotations of the blower fan so as to increase the amount of air flowing on the heat radiation surface.

Next, the liquid-phase refrigerant in the above state is decompressed by the expansion valve to be in the state (pressure P ₁ , enthalpy i ₃ ) shown in FIG. 9 and a part thereof is vaporized to function as an evaporator. It is guided to the outdoor heat exchanger, receives the heat given from the outside air in the outdoor heat exchanger, evaporates, and is further overheated (superheated) by Δi _h shown in the figure and is in the state shown in FIG. 9 (pressure P ₁ , enthalpy i). Return to ₁ ) and repeat the same operation. The heat quantity Q ₁ given to the refrigerant in the indoor heat exchanger is represented by (i ₁ −i ₃ ).
The superheat is set by setting a large heat transfer area or by setting the rotation speed of the blower fan so as to increase the amount of air flowing through the heat absorbing surface.

By the way, in the above heating operation, when the refrigerant whose temperature has decreased by passing through the expansion valve exchanges heat with the outside air in the outdoor heat exchanger and evaporates, the water vapor contained in the outside air is frozen and It may adhere as frost to the heat absorbing fins of the heat exchanger. When frost adheres to the heat absorbing fins of the outdoor heat exchanger, the performance of the outdoor heat exchanger as an evaporator deteriorates.Therefore, perform the cooling operation temporarily to make the outdoor heat exchanger function as a condenser. In the outdoor heat exchanger, so-called reverse defrosting is performed in which condensation heat is released from the refrigerant and defrosted by the heat.

[0008]

However, in the above reverse type defrosting, since the indoor heat exchanger functions as an evaporator, cold air flows out from the indoor heat exchanger into the room that is originally required to be heated. There is a problem of giving discomfort.

Therefore, at the time of defrosting, it is possible to stop the fan of the indoor heat exchanger to prevent the outflow of cold air from the indoor heat exchanger. However, when the fan is stopped, the low-temperature liquid phase passing through the expansion valve A so-called liquid bag is generated in which the refrigerant is sucked into the compressor as it is without evaporating, which causes a failure of the compressor.

The present invention has been made in view of the above problems, and an object thereof is to prevent the outflow of cold air from the indoor heat exchanger and the liquid back to the compressor during the defrosting operation. To provide a harmony device.

[0011]

In order to achieve the above object, the invention according to claim 1 has at least a compressor, a four-way valve, an indoor heat exchanger, an expansion valve and an outdoor heat exchanger in a refrigerant circuit for circulating a refrigerant. In the air conditioner configured to include the first expansion valve and the second expansion valve as the expansion valve, a detour circuit that bypasses the first expansion valve and the indoor heat exchanger is provided, and the detour circuit is provided in the detour circuit. While disposing the second expansion valve,
Heating the refrigerant flowing between the second expansion valve and the compressor during defrosting operation in which the four-way valve is switched to return the refrigerant to the compressor via the compressor, the four-way valve, the outdoor heat exchanger, the bypass and the second expansion valve. It is characterized in that a heat source device is provided for this purpose.

According to a second aspect of the invention, in the first aspect of the invention, during defrosting operation, the four-way valve is automatically switched to connect the high pressure side of the compressor to the outdoor heat exchanger. At the same time, the first expansion valve is throttled or fully closed while the second expansion valve is opened.

According to a third aspect of the invention, in the invention of the first or second aspect, the first expansion valve and the second expansion valve are
It is characterized by comprising an on-off valve type expansion valve or an on-off valve and an expansion throttle.

According to a fourth aspect of the invention, at least a compressor, a four-way valve, an indoor heat exchanger, and a refrigerant circuit for circulating the refrigerant are provided.
In an air conditioner including an expansion valve and an outdoor heat exchanger, a detour circuit that bypasses the indoor heat exchanger, and a switching unit that selectively allows the refrigerant to pass through the indoor heat exchanger or the detour circuit. For heating the refrigerant flowing between the expansion valve and the compressor during the defrosting operation in which the four-way valve is switched to return the refrigerant to the compressor via the compressor, the four-way valve, the outdoor heat exchanger, the expansion valve and the bypass. A heat source device is provided.

The invention according to claim 5 is the invention as claimed in claims 1, 2, and 3.
Alternatively, in the invention described in item 4, the compressor is driven by an engine, and the heat source device is configured by an accumulator or a double-tube heat exchanger for performing heat exchange between engine cooling water and a refrigerant. .

In the invention described in claim 6, claim 1,
In the invention described in 2, 3, or 4, the compressor is driven by an electric motor, and the heat source device is constituted by an electric heater.

Therefore, according to the present invention, even when the reverse method is adopted in the defrosting operation and the cooling operation is temporarily performed, the outdoor heat exchanger functioning as the condenser releases the heat of condensation to liquefy. After being decompressed through the expansion valve, the refrigerant is blocked or restricted from flowing to the indoor heat exchanger side, so that cold air is prevented from flowing out from the indoor heat exchanger,
No discomfort.

The low-temperature low-pressure liquid-phase refrigerant that has been decompressed via the expansion valve is completely evaporated by the heat given from the heat source device to become a gas-phase refrigerant, so that liquid back to the compressor is prevented and compressed. The cause of machine failure is removed.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 1 is a circuit diagram showing a basic configuration of an engine-driven air conditioner according to a first embodiment of the present invention.

In FIG. 1, reference numeral 1 is a water-cooled engine, 2 is a compressor driven by the engine 1, and the present air conditioner includes a refrigerant circuit 3 including the compressor 2 and the engine 1 and a closed loop. A cooling water circuit 4 for circulating cooling water for cooling is provided.

The refrigerant circuit 3 is a circuit for circulating a refrigerant such as CFC by the compressor 2, which is the compressor 2
From the discharge side to the four-way valve 5, the refrigerant line 3b from the four-way valve 5 to the outdoor heat exchanger 6, and the open-close type expansion valve 8 constituting the first expansion valve from the outdoor heat exchanger 6 The refrigerant line 3c reaching the indoor heat exchanger 9, the refrigerant line 3d reaching the four-way valve 5 from the indoor heat exchanger 9 via the heat source device 7, the refrigerant line 3e reaching the accumulator 10 from the four-way valve 5 and the accumulator 10 The refrigerant line 3f reaching the suction side of the compressor 2 is included. The accumulator 10 stores the liquid-phase refrigerant and prevents the liquid-phase refrigerant from flowing out to the compressor 2.

By the way, the refrigerant circuit 3 in the present embodiment is provided with a bypass 3g bypassing the on-off type expansion valve 8 and the indoor heat exchanger 9, and the bypass 3g is provided with a second expansion valve. And the heat source device 7 is provided between the open / close type expansion valve 11 and the four-way valve 5.

On the other hand, the cooling water circuit 4 is a circuit in which the cooling water for cooling the engine 1 is circulated by a water pump 12, which passes from the discharge side of the water pump 12 through an exhaust gas heat exchanger 13 to the engine. 1 includes a cooling water line 4a extending to the cooling water inlet 1, a cooling water line 4b extending from the cooling water outlet of the engine 1 to the heat source device 7, and a cooling water line 4c extending from the heat source device 7 to the suction side of the water pump 12. It is composed of. In the present embodiment, the heat source device 7 is composed of a double pipe heat exchanger for exchanging heat between the engine cooling water and the refrigerant, but it may be composed of a similar accumulator. .

Next, the operation of the air conditioner according to this embodiment during the heating operation will be described with reference to the Mollier diagram shown in FIG.

When the compressor 2 is driven by the engine 1, the state shown in FIG. 9 (pressure P ₁ , enthalpy i
The gas-phase refrigerant of ₁ ) is sucked into the compressor 2 through the refrigerant line 3f and compressed, and becomes a high-temperature high-pressure refrigerant in the state (pressure P ₂ , enthalpy i ₂ ) shown in FIG. The required power (compression heat quantity) AL of the compressor 2 at this time is (i ₂ −i ₁ )
It is represented by.

The high temperature and high pressure vapor phase refrigerant is the refrigerant line 3a.
To the four-way valve 5, but during heating operation, the port a and the port b and the port c and the port d of the four-way valve 5 communicate with each other, and the opening-and-closing expansion provided in the detour 3g. While the valve 11 is fully closed, the open / close type expansion valve 8 is opened and set to an appropriate opening, and the high-temperature and high-pressure gas-phase refrigerant passes through the four-way valve 5 and the heat source device 7 to the refrigerant line 3d. It flows and is guided to the indoor heat exchanger 9 which functions as a condenser.

On the other hand, the cooling water that circulates in the cooling water circuit 4 by driving the water pump 12 is discharged from the water pump 12 and flows through the cooling water line 4a. After collecting and heating the heat of the exhaust gas discharged from the engine 1, the engine 1 is cooled through the cooling water jacket 1a of the engine 1. And
The cooling water used for cooling the engine 1 is the cooling water line 4
After flowing through b and flowing from the three-way valve 53 to the radiator 25 to be cooled, it is sucked by the water pump 12.

Thus, the high-temperature and high-pressure vapor-phase refrigerant introduced into the indoor heat exchanger 9 releases the heat of condensation Q ₂ into the indoor air to be liquefied and subcooled, as shown in FIG. It becomes the liquid-phase refrigerant in the state (pressure P ₂ , enthalpy i ₃ ), and the amount of heat radiation Q _{2 at} this time heats the room.

Next, the high-pressure liquid-phase refrigerant liquefied in the indoor heat exchanger 9 is decompressed by the on-off type expansion valve 8 and is in the state shown in FIG. 9 (pressure P ₁ , enthalpy i).
₃ ) and a part thereof is vaporized and flows through the refrigerant line 3c toward the outdoor heat exchanger 6. And the refrigerant line 3c
The low-temperature refrigerant flowing through reaches the outdoor heat exchanger 6 that functions as an evaporator, where the heat of evaporation is taken from the outside air to be vaporized.
Then, the refrigerant reaches the four-way valve 5 from the outdoor heat exchanger 6 through the refrigerant line 3b, but since the port c and the port d of the four-way valve 5 communicate with each other during the heating operation as described above, the refrigerant is four-way. It flows through the valve 5 to the refrigerant line 3e side and is guided into the accumulator 10. The cooling water that has exchanged heat with the refrigerant in the heat source device 7 is the cooling water line 4
It is returned to the water pump 12 through c, and thereafter, the same operation is repeated to circulate in the cooling water circuit 4.

In the accumulator 10, the gas-liquid refrigerant is separated, and the gas-phase refrigerant is sucked by the compressor 2 through the refrigerant line 3f. The state of the gas-phase refrigerant sucked by the compressor 2 is as shown in FIG. The state (pressure P ₁ and enthalpy i ₁ ) shown in FIG. 9 has been restored, and this gas-phase refrigerant is compressed again by the compressor 2 to repeat the same operation as described above.

Therefore, heat is given to the refrigerant from the outside air in the outdoor heat exchanger 6 until the refrigerant decompressed by the open-close type expansion valve 8 is sucked into the compressor 2, so that the refrigerant has a heat quantity Q ₁ (= I ₁ −i ₃ ) is received, evaporated, and further superheated.

In the heating operation described above, when the refrigerant that has passed through the open-close type expansion valve 8 exchanges heat with the outside air in the outdoor heat exchanger 6 and evaporates, the water vapor contained in the outside air freezes and the outside heat is removed. It may adhere to the heat absorption fins of the exchanger 6 as frost.

In such a case, the reverse type defrosting operation is performed. In this defrosting operation, the cooling operation is temporarily performed so that the outdoor heat exchanger 6 functions as a condenser. Defrosting is performed by the heat of condensation released from the refrigerant in the outdoor heat exchanger 6.

That is, in the defrosting operation, the four-way valve 5 is switched so that the port a and the port c are communicated with each other and the port b and the port d are communicated with each other as shown in FIG. Opened and the other open-close type expansion valve 8
Is fully closed or squeezed.

Therefore, the high-temperature high-pressure gas-phase refrigerant discharged from the compressor 2 and flowing in the refrigerant line 3a flows through the four-way valve 5 to the refrigerant line 3b side and is guided to the outdoor heat exchanger 6 functioning as a condenser. Get burned. Then, the high-temperature and high-pressure vapor-phase refrigerant guided to the outdoor heat exchanger 6 releases the condensation heat to melt and remove the frost adhering to the heat absorbing fins.

All or most of the high-pressure liquid-phase refrigerant that has been liquefied by being defrosted in the outdoor heat exchanger 6 flows through the bypass 3g and is decompressed by the on-off expansion valve 11. Part of it is vaporized and flows through the refrigerant line 3d toward the heat source device 7. Then, in the heat source device 7, the low temperature refrigerant flowing through the refrigerant line 3d is provided with the waste heat of the engine 1, the refrigerant receives the waste heat of the engine 1 and is completely evaporated, and then is overheated (superheated) to generate the four-way valve 5. Flow toward the refrigerant line 3e, and are guided into the accumulator 10. At this time, the three-way valve 53 is switched so that the hot water from the engine 1 is circulated to the heat source device 7 instead of the radiator 25.

In the accumulator 10, the gas-liquid refrigerant is separated, and the gas-phase refrigerant is sucked into the compressor 2 through the refrigerant line 3f. The gas-phase refrigerant is compressed again by the compressor 2 and The same operation as described above is repeated.

In the above defrosting operation, the refrigerant liquefied by releasing the heat of condensation in the outdoor heat exchanger 6 functioning as a condenser is prevented or restricted from flowing to the indoor heat exchanger 9 side. Prevents cold air from flowing out from the indoor heat exchanger 9,
The user does not feel uncomfortable.

The low-temperature low-pressure liquid-phase refrigerant decompressed through the open-close type expansion valve 11 is completely evaporated by the heat given from the heat source device 7 to become a gas-phase refrigerant, so that the liquid back to the compressor 2 is It is prevented and the cause of the failure of the compressor 2 is removed.

Here, a specific example of the engine-driven air conditioner to which the present invention is applied will be described based on the circuit diagram shown in FIG.

The engine driven air conditioner shown in FIG. 2 comprises an outdoor air conditioning unit 20 and an indoor air conditioning unit 30, and the indoor air conditioning unit 30 includes an indoor heat exchanger 9 and a first expansion valve 8. It is configured.

Further, the outdoor air conditioning unit 20 has an engine room 21 in which the engine 1, the compressor 2, etc. are arranged, a main accumulator 10, a sub accumulator 22, an electrical equipment box 23, and a conduit for connecting each device. It is provided with a piping chamber 24 arranged therein, an outdoor heat exchanger 6, an outdoor heat exchanger chamber 26 in which a radiator 25 as a hot water heat exchanger and the like are arranged.

The engine 1 is a water-cooled gas engine, and its intake port is connected to a gas mixer 28 and an air cleaner 29 via an intake pipe 27. The intake pipe 27 is connected to the top wall of the engine room 21. It penetrates the ceiling wall of the outdoor heat exchanger chamber 26 and opens to the outside.

The gas mixer 28 is connected to a gas fuel source (not shown) through a fuel pipe 31, and the fuel pipe 31 has a flow rate control valve 32, a zero governor (pressure reducing valve) 33, and two units which are integrated with the gas mixer 28. A solenoid valve 34 is provided. An exhaust gas heat exchanger 13, an exhaust silencer 36, and a mist separator 37 are connected to the exhaust port of the engine 1 via an exhaust pipe 35, and the exhaust pipe 35 is located above the outdoor heat exchanger chamber 26. It is open.

Further, the engine 1 is provided with a lubricating oil tank 38, and when the amount of lubricating oil decreases, the solenoid valve 39 opens, and the lubricating oil is replenished to the engine 1 by gravity.

Further, the compressor 2 is connected to the output shaft of the engine 1 via a clutch 40.
Of the refrigerant line 3a, the four-way valve 5 and the refrigerant line 3
It is connected to the outdoor heat exchanger 6 via b. The outdoor heat exchanger 6 is connected to the indoor heat exchanger 9 via a refrigerant line 3e, a joint, a heat exchange section in the main accumulator 10 and a refrigerant line 3d. The line 3c, the joint, the refrigerant line 3f, the four-way valve 5, the refrigerant line 3h, and the main accumulator 10 and the sub accumulator 22 on the refrigerant line 3h are connected to the suction port of the compressor 2.

In FIG. 2, reference numeral 41 denotes the refrigerant line 3e.
A dryer 42 provided in the middle of the path is a filter that bypasses the dryer 41. 43 is a capillary tube, and 44
Is a combination of a temperature sensor and a capillary tube,
These are for detecting the level in the main accumulator 10 by detecting the refrigerant temperature.
Further, 45 is an opening / closing valve, 46 is an oil discharge passage, and 47 is a throttle for returning lubricating oil. When the amount of lubricating oil accumulated in the lower portion of the main accumulator 10 becomes large, the opening / closing valve 45 is opened manually or automatically to release the lubricating oil. The flow is made to flow from the main accumulator 10 to the sub accumulator 22.

Further, an oil separator 48 for separating the lubricating oil contained in the refrigerant is provided in the middle of the refrigerant line 3a, and the lubricating oil separated by this oil separator 48 passes through the capillary tube 43 and is constantly in the refrigerant line 3h. When the amount of the lubricating oil reaches a predetermined value or more while being returned to the side, the lubricating oil is returned to the main accumulator 10 and the sub accumulator 22 via the oil strainer 49 and the electromagnetic valve 50. The refrigerant line 3a is connected to the main accumulator 10 via an oil strainer 49 and a solenoid valve 50 that opens when the refrigerant pressure in the refrigerant line 3a is equal to or higher than a predetermined value, thereby preventing an abnormal pressure rise in the refrigerant circuit. There is.

On the other hand, the outdoor air conditioning unit 20 is provided with a cooling water circulation system S. This cooling water circulation system S includes a first circulation path for circulating the cooling water jacket 1a of the engine 1, the thermostat 51, and the first cooling water pump 52 when the cooling water temperature is equal to or lower than a predetermined value, and when the engine is cold. , The exhaust gas heat exchanger 13, the linear three-way valve 53, the radiator 25 on the one hand, the heat exchange section in the main accumulator 10 on the other hand, and the second cooling water pump 54.
And a second circulation path that circulates the exhaust gas heat exchanger 13, the exhaust gas heat exchanger 13, the first cooling water pump 52, the cooling water jacket 1a, and the thermostat 51 when the engine warm-up is completed when the cooling water temperature exceeds a predetermined value. , Linear three-way valve 53, one radiator 25, the other main accumulator 1
It has the 3rd circulation path which circulates in order of the heat exchange part in 0, and the 2nd cooling water pump 54.

A cooling water reservoir tank 55 is connected to the radiator 25 via an injection port 56, and one port of the thermostat 51 is also connected to the injection port 56. The port of the thermostat 51 is the engine 1
The cooling water jacket 1a is always communicated with the cooling water jacket 1a, and it is possible to bleed air in the first circulation path when the engine is cold.

When the linear three-way valve 53 is switched, the engine cooling water is supplied to the heat exchange section in the main accumulator 10 by the cooling water line 4d, so that heat is given to the refrigerant.

Thus, also in the air conditioner according to the present embodiment, the detour 3g that bypasses the first expansion valve 8 and the indoor heat exchanger 9 is provided, and the detour 3g includes the second detour 3g. An expansion valve 11 is provided. In the present embodiment, the main accumulator 10 constitutes a heat source device.

Therefore, also in this air conditioner, during the defrosting operation, the outdoor heat exchanger 6 is made to function as a condenser by temporarily performing the cooling operation and discharged from the refrigerant in the outdoor heat exchanger 6. Defrosting is performed by the condensed heat.

That is, in the defrosting operation, the four-way valve 5 is switched, the second expansion valve 11 is opened, and the other first expansion valve 8 is fully closed or throttled.

Therefore, the high-temperature high-pressure vapor-phase refrigerant discharged from the compressor 2 and flowing through the refrigerant line 3a flows through the four-way valve 5 to the refrigerant line 3b side and is guided to the outdoor heat exchanger 6 functioning as a condenser. Get burned. Then, the high-temperature and high-pressure vapor-phase refrigerant guided to the outdoor heat exchanger 6 releases the condensation heat to melt and remove the frost adhering to the heat absorbing fins.

All or most of the high-pressure liquid-phase refrigerant that has been liquefied by being defrosted in the outdoor heat exchanger 6 flows through the bypass 3g and is decompressed by the second expansion valve 11. Part of the gas is vaporized and flows toward the main accumulator 10, which is a heat source device. Then, in the main accumulator 10, the waste heat of the engine 1 is given to the low-temperature refrigerant, the refrigerant receives the waste heat of the engine 1 and completely evaporates, and then is overheated (superheated) and guided into the sub accumulator 22. In the sub accumulator 22, the gas-liquid refrigerant is separated, and the gas-phase refrigerant is sucked into the compressor 2.

In the above defrosting operation, the refrigerant liquefied by releasing the condensation heat in the outdoor heat exchanger 6 functioning as a condenser is prevented or restricted from flowing to the indoor heat exchanger 9 side. Prevents cold air from flowing out from the indoor heat exchanger 9,
The user does not feel uncomfortable.

The low-temperature low-pressure liquid-phase refrigerant decompressed through the on-off type expansion valve 11 is completely evaporated by the engine waste heat provided in the main accumulator 10 to become a gas-phase refrigerant. Back is prevented,
The cause of the failure of the compressor 2 is removed.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG. 3 is a circuit diagram showing the basic configuration of the motor-driven air conditioner according to Embodiment 2 of the present invention. In this figure, the same elements as those shown in FIG. 1 are assigned the same reference numerals. .

In this embodiment, the electric motor 14 is used as the drive source of the compressor 2, the first expansion valve is composed of the on-off valve 15 and the expansion throttle 16, and the second expansion valve provided in the bypass 3g is used. The heat source device 7 is composed of the electric heater 19 and the detour 3g.
The configuration is different from that of the first embodiment, and other configurations are the same as those of the first embodiment.

Thus, in the defrosting operation of the air conditioner according to the present embodiment, the four-way valve 5 is switched to the state shown in FIG.
Port a and port c, port b and port d
And the other opening / closing valve 17 is opened and the other opening / closing valve 15 is fully closed or throttled.

Therefore, the high-temperature and high-pressure gas-phase refrigerant discharged from the compressor 2 and flowing through the refrigerant line 3a flows through the four-way valve 5 to the refrigerant line 3b side and is guided to the outdoor heat exchanger 6 functioning as a condenser. Get burned. Then, the high-temperature and high-pressure vapor-phase refrigerant guided to the outdoor heat exchanger 6 releases the condensation heat to melt and remove the frost adhering to the heat absorbing fins.

All or most of the high-pressure liquid-phase refrigerant that has been liquefied by being defrosted in the outdoor heat exchanger 6 flows through the bypass 3g and is decompressed by the on-off valve 17 and the expansion throttle 18. Then, a part thereof is vaporized and flows through the refrigerant line 3d toward the heat source device 7. Then, in the heat source device 7, the low-temperature refrigerant flowing in the refrigerant line 3d is the electric heater 1
After being heated by 9 and evaporated, it is superheated and flows through the four-way valve 5 to the refrigerant line 3e side,
It is introduced into the accumulator 10, the gas-liquid is separated in the accumulator 10, and the gas-phase refrigerant is the refrigerant line 3
It is sucked into the compressor 2 through f. Then, this gas-phase refrigerant is compressed again by the compressor 2 and the same operation as described above is repeated.

In the above defrosting operation, the refrigerant liquefied by releasing the heat of condensation in the outdoor heat exchanger 6 functioning as a condenser, as in the first embodiment, flows to the indoor heat exchanger 9 side. Since it is blocked or limited, cold air is prevented from flowing out from the indoor heat exchanger 9, and the user does not feel uncomfortable.

Further, the low-temperature low-pressure liquid-phase refrigerant decompressed via the on-off valve 17 and the expansion throttle 18 is completely evaporated by the heat given from the heat source device 7 to become a gas-phase refrigerant, so that the liquid to the compressor 2 is The back is prevented, and the cause of the failure of the compressor 2 is removed.

When the defrosting operation is automated and the defrosting operation mode is selected, the four-way valve is automatically switched to connect the high pressure side of the compressor to the outdoor heat exchanger and the first expansion valve is turned on. The second expansion valve may be opened while the valve is throttled or fully closed.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a circuit diagram showing the basic configuration of the motor-driven air conditioner according to the third embodiment of the present invention. In this figure, the same elements as those shown in FIG. 3 are designated by the same reference numerals. .

The present embodiment is different from the second embodiment in that an expansion valve 8 and an on-off valve 15 are provided in the refrigerant line 3c and an on-off valve is provided in the bypass 3g, and other configurations are the same as those of the second embodiment. Similar to that of 2.

Thus, during the normal cooling or heating operation of the air conditioner according to the present embodiment, one opening / closing valve 15 is opened and the other opening / closing valve 17 is closed. The high-pressure liquid-phase refrigerant that has passed through the heat exchanger 6 is decompressed by the expansion valve 8 and part of it vaporizes, and all of it passes through the indoor heat exchanger 9 and condenses. One on-off valve 15 is closed and the other on-off valve 17 is opened, and all the refrigerant decompressed by the expansion valve 8 is guided to the heat source device 7 through the bypass 3g. When allowing the flow of cold air from the indoor heat exchanger 9 to the extent that the user does not feel uncomfortable, the indoor heat is passed through the on-off valve 15 in which a part of the refrigerant decompressed by the expansion valve 8 is slightly opened. Send to the exchanger 9. As a result, the capacity of the electric heater 19 can be reduced.

In the heat source device 7, the refrigerant line 3
The low-temperature refrigerant flowing in d is heated by the electric heater 19 and evaporated, and then overheated (superheated) to cause the four-way valve 5 to flow.
Flow toward the refrigerant line 3e through the accumulator 1
0, the gas-liquid is separated in the accumulator 10, and the gas-phase refrigerant passes through the refrigerant line 3f and the compressor 2
Is sucked.

Therefore, in the defrosting operation, as in the second embodiment, the outdoor heat exchanger 6 functioning as a condenser.
Since the refrigerant liquefied by releasing the condensation heat is blocked or restricted from flowing toward the indoor heat exchanger 9 side, cold air is prevented from flowing out from the indoor heat exchanger 9 and the user feels uncomfortable. Never.

Further, since all of the low-temperature low-pressure liquid-phase refrigerant that has been decompressed through the expansion 8 is completely evaporated by the heat given from the heat source device 7 to become a gas-phase refrigerant, liquid back to the compressor 2 is prevented. The cause of the failure of the compressor 2 is removed.

The on-off valves 15 and 17 are respectively set to 3 in FIG.
You may install in d1 point and 3g1 point. Further, the heat source device 7 may be arranged not in the bypass 3g but in the low pressure side refrigerant line from the junction 3q of the bypass 3g and the refrigerant line 3d to the compressor 2 via the four-way valve 5 and the accumulator 10.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIGS. 5 and 6 are circuit diagrams showing the basic configuration of the motor-driven air conditioner according to Embodiment 4 of the present invention. In these figures, the same elements as those shown in FIG. Attached.

The present embodiment differs from the third embodiment in that a three-way valve 100 is provided at a branch point 3p where the bypass 3g branches from the refrigerant line 3c, and other configurations are similar to those of the third embodiment. Is.

Thus, during the normal cooling or heating operation of the air conditioner according to the present embodiment, the three-way valve 100 is switched as shown in FIG. 6, and all the refrigerant flows through the indoor heat exchanger 9. Although it passes through and condenses or evaporates, the three-way valve 100 is switched as shown in FIG. 5 during the defrosting operation, and like the third embodiment, all the refrigerant decompressed by the expansion valve 8 passes through the bypass 3g. It is led to the heat source device 7 through the heat source device 7 and is heated by the electric heater 19 in the heat source device 7 to be evaporated. If the three-way valve 100 is a linear three-way valve, a part of the refrigerant in the indoor heat exchanger 9 can be circulated during the defrosting operation.

Therefore, also in the present embodiment, the same effect as in the first to third embodiments can be obtained.

The three-way valve 100 may be installed at the confluence 3q of the bypass 3g to the refrigerant line 3d. Further, as in the third embodiment, the heat source device 7 is not the bypass 3g but the low pressure side refrigerant line from the confluence 3q of the bypass 3g and the refrigerant line 3d to the compressor 2 via the four-way valve 5 and the accumulator 10. It may be placed inside.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described with reference to FIGS. 7 and 8 are circuit diagrams showing the basic configuration of the motor-driven air conditioner according to Embodiment 5 of the present invention. In these figures, the same elements as those shown in FIGS. 5 and 6 are not shown. The same reference numerals are attached.

The present embodiment is different from the fourth embodiment in that a bypass 3g that bypasses the indoor heat exchanger 9 and the four-way valve 5 is provided between the three-way valve 100 and the refrigerant line 3e, and other configurations are provided. Is the same as that of the fourth embodiment.

Thus, during the normal cooling or heating operation of the air conditioner according to the present embodiment, the three-way valve 100 is switched as shown in FIG. 8, and all the refrigerant flows through the indoor heat exchanger 9. Although not passing through to the heat source device 7, the three-way valve 100 is switched as shown in FIG. 7 during the defrosting operation, and all of the refrigerant decompressed by the expansion valve 8 is bypassed by the detour 3.
It is guided to the heat source device 7 through g and is heated by the electric heater 19 in the heat source device 7 to be evaporated. The three-way valve 100 can be a linear three-way valve as in the fourth embodiment.

Therefore, also in the present embodiment, the same effect as in the first to fourth embodiments can be obtained.

The three-way valve 100 may be installed at the confluence 3r of the bypass 3g to the refrigerant line 3e. Further, the heating device 7 may be arranged not in the bypass 3g but in the low pressure side refrigerant line from the confluence 3r to the compressor 2 via the accumulator 10.

[0085]

As is apparent from the above description, according to the present invention, the outdoor heat exchange functioning as a condenser even when the reverse method is adopted in the defrosting operation and the cooling operation is temporarily performed. The refrigerant liquefied by releasing the heat of condensation in the heat exchanger is depressurized through the expansion valve and then blocked or restricted from flowing to the indoor heat exchanger side, preventing the cold air from flowing out from the indoor heat exchanger. It does not cause discomfort.

The low-temperature low-pressure liquid-phase refrigerant that has been decompressed through the expansion valve is completely evaporated by the heat given from the heat source device to become a gas-phase refrigerant, so that liquid back to the compressor is prevented and compressed. The cause of machine failure is removed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a basic configuration of an engine-driven air conditioner according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific configuration of an engine-driven air conditioner (actual machine) according to the first embodiment of the present invention.

FIG. 3 is a circuit diagram showing a basic configuration of a motor-driven air conditioner according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a basic configuration of a motor-driven air conditioner according to a third embodiment of the present invention.

FIG. 5 is a circuit diagram showing a basic configuration (during defrosting operation) of a motor-driven air conditioner according to a fourth embodiment of the present invention.

FIG. 6 is a circuit diagram showing a basic configuration (during cooling or heating operation) of a motor-driven air conditioner according to a fourth embodiment of the present invention.

FIG. 7 is a circuit diagram showing a basic configuration (during defrosting operation) of a motor-driven air conditioner according to a fifth embodiment of the present invention.

FIG. 8 is a circuit diagram showing a basic configuration (during cooling or heating operation) of a motor-driven air conditioner according to a fifth embodiment of the present invention.

FIG. 9 is a Mollier diagram showing changes in the state of the refrigerant.

[Explanation of symbols]

 1 Engine 2 Compressor 3 Refrigerant circuit 3g Detour 5 Four-way valve 6 Outdoor heat exchanger 7 Heat source device 8 Open / close type expansion valve (1st expansion valve) 9 Indoor heat exchanger 11 Open / close type expansion valve (2nd expansion valve) 14 Electric motor 15,17 Open / close valve (switching means) 16,18 Expansion throttle 19 Electric heater 100 Three-way valve (switching means)

Claims (6)

[Claims] 1. An air conditioner configured by providing at least a compressor, a four-way valve, an indoor heat exchanger, an expansion valve and an outdoor heat exchanger in a refrigerant circuit for circulating a refrigerant, wherein the expansion valve is a first expansion valve. And a second expansion valve, and a detour for bypassing the first expansion valve and the indoor heat exchanger is provided.
During the defrosting operation, the second expansion valve is arranged in the bypass and the four-way valve is switched to return the refrigerant to the compressor through the compressor, the four-way valve, the outdoor heat exchanger, the bypass and the second expansion valve. An air conditioner comprising a heat source device for heating a refrigerant flowing between the second expansion valve and the compressor. 2. During defrosting operation, the four-way valve is automatically switched to connect the high pressure side of the compressor to the outdoor heat exchanger, and the first expansion valve is throttled or fully closed. On the other hand, the air conditioner according to claim 1, wherein the second expansion valve is opened. 3. The air conditioner according to claim 1, wherein the first expansion valve and the second expansion valve are constituted by an on-off valve type expansion valve or an on-off valve and an expansion throttle. 4. An air conditioner having at least a compressor, a four-way valve, an indoor heat exchanger, an expansion valve and an outdoor heat exchanger provided in a refrigerant circuit for circulating a refrigerant, bypassing the indoor heat exchanger. A bypass circuit and switching means for selectively passing the refrigerant through the indoor heat exchanger or the bypass circuit are provided, and the four-way valve is switched to transfer the refrigerant to the compressor, the four-way valve, the outdoor heat exchanger, the expansion valve and the bypass circuit. An air conditioner comprising a heat source device for heating a refrigerant flowing between the expansion valve and the compressor during a defrosting operation for returning to the compressor. 5. The compressor is driven by an engine, and the heat source device is composed of an accumulator or a double tube heat exchanger for exchanging heat between engine cooling water and a refrigerant. Item 1, 2, 3 or 4 of the air conditioner. 6. The air conditioner according to claim 1, 2, 3, or 4, wherein the compressor is driven by an electric motor, and the heat source device is an electric heater.