Patent Description:
In general, an air conditioner includes an outdoor unit including a compressor and an outdoor heat exchanger, an indoor unit including an indoor expansion valve and an indoor heat exchanger, and a refrigerant circuit connecting the above components to each other through a refrigerant liquid pipe and a refrigerant gas pipe. The air conditioner circulates the refrigerant filled in the refrigerant circuit through the compressor, the outdoor heat exchanger, the refrigerant liquid pipe, the indoor expansion valve, the indoor heat exchanger, the refrigerant gas pipe, and the compressor in order.

Recently, as regulations on HFC refrigerants have become a reality with the adoption of the Kigali Revision Protocol, the use of HFC refrigerants is decreasing worldwide and the price of refrigerants such as R410A is rising. Due to this background, in recent years, a technology for reducing the amount of refrigerant charged into the refrigerant circuit has been applied to an air conditioner.

<CIT> discloses an air conditioner capable of reducing the amount of refrigerant charged into a refrigerant circuit. This air conditioner reduces the amount of refrigerant used as an outdoor expansion valve is provided between an auxiliary heat exchanger provided in the outdoor unit and the indoor heat exchanger so that the refrigerant in the refrigerant liquid pipe connecting the indoor unit and the outdoor unit is in a state where gas and liquid are mixed. In a cooling operation, the refrigerant passes through the auxiliary heat exchanger and is then depressurized in the outdoor expansion valve, thereby being in a state where gas and liquid are mixed. Also, in a heating operation, the refrigerant passes through the indoor heat exchanger and is then depressurized in the indoor expansion valve, thereby being in a state where gas and liquid are mixed.

However, because in such an air conditioner, the refrigerant in a state where gas and liquid are mixed in the heating operation is depressurized by the outdoor expansion valve provided upstream of the auxiliary heat exchanger, the heat exchange rate of the refrigerant in the auxiliary heat exchanger is lowered, so that the performance of the auxiliary heat exchanger is lowered as compared with the case where a refrigerant of a liquid state flows.

Conventional air conditioners are also known from <CIT>, <CIT>, <CIT> and <CIT>. In particular <CIT> discloses an air conditioner comprising a refrigerant circuit, the refrigerant circuit including:a compressor; an outdoor heat exchanger; an outdoor expansion valve; an indoor expansion valve; a four-way valve; an indoor heat exchanger; an auxiliary heat exchanger provided on a refrigerant pipe between the outdoor heat exchanger and the indoor expansion valve, the auxiliary heat exchanger connected in series with the outdoor expansion valve; a rectifier configured to allow a refrigerant flowing from the outdoor heat exchanger toward the indoor expansion valve in a cooling operation and a refrigerant flowing from the indoor expansion valve toward the outdoor heat exchanger in a heating operation to sequentially flow through the auxiliary heat exchanger and the outdoor expansion valve; an injection passage including one end connected to an injection inlet of the compressor and the other end connected between the auxiliary heat exchanger and the receiver, and configured to allow a part of the refrigerant flowing from the auxiliary heat exchanger to the outdoor expansion valve to flow to the compressor through the auxiliary heat exchanger; and a supercooling expansion valve installed in the injection passage and configured to expand the refrigerant in the injection passage flowing toward the auxiliary heat exchanger.

It is an aspect of the invention to provide an air conditioner capable of reducing the amount of refrigerant flowing through a refrigerant circuit and preventing the performance of an auxiliary heat exchanger from being lowered in a cooling operation and a heating operation.

In accordance with an aspect of the invention, an air conditioner includes a refrigerant circuit including a compressor, an outdoor heat exchanger, an outdoor expansion valve, an indoor expansion valve, a four-way valve, and an indoor heat exchanger, wherein the refrigerant circuit includes an auxiliary heat exchanger provided on a refrigerant pipe between the outdoor heat exchanger and the indoor expansion valve and connected in series with the outdoor expansion valve, a rectifier configured to allow a refrigerant flowing from the outdoor heat exchanger toward the indoor expansion valve in a cooling operation and a refrigerant flowing from the indoor expansion valve toward the outdoor heat exchanger in a heating operation to sequentially flow through the auxiliary heat exchanger and the outdoor expansion valve, at least one bypass passage bypassing the outdoor expansion valve, at least one flow regulating valve installed on the at least one bypass passage, an injection passage including one end connected to an injection inlet of the compressor and the other end connected between the auxiliary heat exchanger and the outdoor expansion valve, and configured to allow a part of the refrigerant flowing from the auxiliary heat exchanger to the outdoor expansion valve to flow to the compressor through the auxiliary heat exchanger, and a supercooling expansion valve installed in the injection passage and configured to expand the refrigerant in the injection passage flowing toward the auxiliary heat exchanger.

A refrigerant flowing between the indoor expansion valve and the outdoor expansion valve may be mixed in a gaseous state and a liquid state.

The rectifier, in the cooling operation, may be configured to allow the refrigerant passed through the outdoor expansion valve to flow to the indoor expansion valve and the refrigerant passed through the outdoor heat exchanger to flow to the auxiliary heat exchanger, and in the heating operation, may be configured to allow the refrigerant passed through the indoor expansion valve to flow to the auxiliary heat exchanger and the refrigerant passed through the outdoor expansion valve to flow to the outdoor heat exchanger.

The rectifier may include a first check valve to allow only a flow of the refrigerant from the indoor expansion valve toward the auxiliary heat exchanger in the heating operation, a second check valve to allow only a flow of the refrigerant from the outdoor expansion valve toward the outdoor heat exchanger in the heating operation, a third check valve to allow only a flow of the refrigerant from the outdoor heat exchanger toward the auxiliary heat exchanger in the cooling operation, and a fourth check valve to allow only a flow of the refrigerant from the outdoor expansion valve toward the indoor expansion valve in the cooling operation.

As is apparent from the above, an air conditioner according to an embodiment of the disclosure can reduce the amount of refrigerant flowing through a refrigerant circuit and prevent the performance of an auxiliary heat exchanger from being lowered in a cooling operation and a heating operation.

Hereinafter an air conditioner according to embodiments of the disclosure will be described in detail with reference to the accompanying drawings.

Referring to <FIG>, an air conditioner <NUM> according to a first embodiment , includes an indoor unit <NUM> installed on the inside of a structure, an outdoor unit <NUM> installed on the outside of the structure, and a refrigerant circuit <NUM> (heat pump cycle) to allow a refrigerant to flow to the indoor unit <NUM> and the outdoor unit <NUM>.

The air conditioner <NUM> may be applied to a large structure such as a building. The indoor unit <NUM> and the outdoor unit <NUM> may be disposed at the inside and outside of a structure, respectively, and then may be connected by a refrigerant gas pipe Lb and a refrigerant liquid pipe La which are installed at a site. Therefore, the amount of refrigerant charged in the refrigerant circuit <NUM> may increase according to the installation environment.

In a cooling operation or a heating operation of the air conditioner <NUM> according to the first embodiment, the refrigerant passed through the refrigerant liquid pipe La may be in a state where gas and liquid are mixed. Therefore, the amount of the refrigerant passing through the refrigerant liquid pipe La may be reduced as compared with the case of flowing in the liquid state.

The indoor unit <NUM> may include indoor expansion valves 11A and 11B connected in parallel to each other, and indoor heat exchangers 12A and 12B connected in series to the indoor expansion valves 11A and 11B, respectively.

The outdoor unit <NUM> may include a four-way valve <NUM>, an accumulator <NUM>, a compressor <NUM>, an outdoor heat exchanger <NUM>, an outdoor expansion valve <NUM>, an auxiliary heat exchanger <NUM>, and a rectifier <NUM> to rectify a flow of the refrigerant in a predetermined direction.

The refrigerant circuit <NUM> may switch the cooling operation and the heating operation as the passage connection is changed by the operation of the four-way valve <NUM>. The refrigerant circuit <NUM> may include a main circuit <NUM> in which the indoor expansion valves 11A and 11B, the indoor heat exchangers 12A and 12B, the four-way valve <NUM>, the accumulator <NUM>, the compressor <NUM>, the outdoor heat exchanger <NUM>, the rectifier <NUM>, the auxiliary heat exchanger <NUM>, and the outdoor expansion valve <NUM> are connected.

The indoor unit <NUM> and the outdoor unit <NUM> are connected by the refrigerant gas pipe Lb and the refrigerant liquid pipe La. In the refrigerant gas pipe Lb, a gaseous refrigerant or a gas-liquid mixed refrigerant close to a gaseous state may flow. In the refrigerant liquid pipe La, a gaseous refrigerant and a liquid refrigerant may flow together. The refrigerant gas pipe Lb and the refrigerant liquid pipe La are connected to connection portions P11 and P12 of the indoor unit <NUM> and connection portions P21 and P22 of the outdoor unit <NUM> at a site where the air conditioner is installed.

In the main circuit <NUM>, one ends of the indoor heat exchangers 12A and 12B are connected to the indoor expansion valves 11A and 11B, respectively, and the other ends of the indoor heat exchangers 12A and 12B may be connected to the accumulator <NUM> through the refrigerant gas pipe Lb and the four-way valve <NUM>.

One end of the compressor <NUM> may be connected to the accumulator <NUM>, and the other end of the compressor <NUM> may be connected to the outdoor heat exchanger <NUM> through the four-way valve <NUM>. One end of the outdoor heat exchanger <NUM> may be connected to the four-way valve <NUM>, and the other end of the outdoor heat exchanger <NUM> may be connected to the rectifier <NUM>.

One end of the auxiliary heat exchanger <NUM> is connected to the rectifier <NUM>, and the other end of the auxiliary heat exchanger <NUM> is connected to the outdoor expansion valve <NUM>. One end of the outdoor expansion valve <NUM> is connected to the auxiliary heat exchanger <NUM>, and the other end of the outdoor expansion valve <NUM> is connected to the rectifier <NUM>. One ends of the indoor expansion valves 11A and 11B are connected to the rectifier <NUM> through the refrigerant liquid pipe La, and the other ends of the indoor expansion valves 11A and 11B are connected to the indoor heat exchangers 12A and 12B, respectively.

The refrigerant circuit <NUM> further includes an injection passage <NUM> to branch a part of the refrigerant flowing from the auxiliary heat exchanger <NUM> toward the outdoor expansion valve <NUM> from the main circuit <NUM> to flow to the compressor <NUM>.

The injection passage <NUM> may be implemented by an injection pipe Lc, one end of which is connected to an injection inlet of the compressor <NUM> and the other end of which is connected to a refrigerant pipe between the auxiliary heat exchanger <NUM> and the outdoor expansion valve <NUM>. The injection passage <NUM> passes through the auxiliary heat exchanger <NUM> to allow the refrigerant flowing therein to exchange heat with the auxiliary heat exchanger <NUM>. The auxiliary heat exchanger <NUM> may be installed such that the main circuit <NUM> and the injection passage <NUM> pass therethrough.

A supercooling expansion valve EV is installed on the injection passage <NUM> upstream of the auxiliary heat exchanger <NUM>. The supercooling expansion valve EV expands the refrigerant in the injection passage <NUM> flowing toward the auxiliary heat exchanger <NUM> to cool the auxiliary heat exchanger <NUM>. Accordingly, the auxiliary heat exchanger <NUM> may cool the refrigerant flowing through the main circuit <NUM>.

In the refrigerant circuit <NUM>, the indoor heat exchangers 12A and 12B heat-exchange indoor air with the refrigerant flowing therein, and the outdoor heat exchanger <NUM> heat-exchanges the refrigerant flowing therein with outdoor air. The indoor expansion valves 11A and 11B, the outdoor expansion valve <NUM>, and the supercooling expansion valve EV may be motorized valves to adjust an opening degree of a passage to expand and decompress the refrigerant passing through the passage.

In the cooling operation, the rectifier <NUM> allows the refrigerant flowing from the outdoor heat exchanger <NUM> toward the indoor expansion valves 11A and 11B to flow through the auxiliary heat exchanger <NUM> and the outdoor expansion valve <NUM> sequentially.

In the heating operation, the rectifier <NUM> allows the refrigerant flowing from the indoor expansion valves 11A and 11B toward the outdoor heat exchanger <NUM> to flow through the auxiliary heat exchanger <NUM> and the outdoor expansion valve <NUM> sequentially.

That is, rectifier <NUM> operates as a flow controller for controlling the refrigerant flowing between the outdoor heat exchanger <NUM> and the indoor expansion valves 11A and 11b to flow only in a direction from the auxiliary heat exchanger <NUM> toward the outdoor expansion valve <NUM> regardless of an operating state of the air conditioner. The rectifier <NUM> includes first to fourth check valves <NUM>, <NUM>, <NUM> and <NUM> and pipes in the form of a bridge circuit to connect the check valves <NUM>, <NUM>, <NUM> and <NUM>, as illustrated in <FIG>.

The first check valve <NUM> allows only a flow of the refrigerant from the indoor expansion valves 11A and 11B toward the auxiliary heat exchanger <NUM> in the heating operation. The second check valve <NUM> allows only a flow of the refrigerant from the outdoor expansion valve <NUM> toward the outdoor heat exchanger <NUM> in the heating operation. The third check valve <NUM> allows only a flow of the refrigerant from the outdoor heat exchanger <NUM> toward the auxiliary heat exchanger <NUM> in the cooling operation. The fourth check valve <NUM> allows only a flow of the refrigerant from the outdoor expansion valve <NUM> toward the indoor expansion valves 11A and 11B in the cooling operation.

The operation during the cooling operation and the operation during the heating operation of the air conditioner <NUM> according to the first embodiment will be described below.

In the cooling operation, the refrigerant charged in the refrigerant circuit <NUM> circulates through the compressor <NUM>, the outdoor heat exchanger <NUM>, the third check valve <NUM>, the auxiliary heat exchanger <NUM>, the outdoor expansion valve <NUM>, the fourth check valve <NUM>, the refrigerant liquid pipe La, the indoor expansion valves 11A and 11B, the indoor heat exchangers 12A and 12B, the refrigerant gas pipe Lb, the accumulator <NUM>, and the compressor <NUM> in order.

The refrigerant in in a high-temperature gaseous state delivered from the compressor <NUM> is liquefied through heat exchange with the outdoor air of low temperature in the outdoor heat exchanger <NUM>. Thereafter, the liquefied refrigerant flows through the third check valve <NUM> of the rectifier <NUM> to the auxiliary heat exchanger <NUM> and then is cooled through heat exchange with the refrigerant flowing through the injection passage <NUM> while passing through the auxiliary heat exchanger <NUM>.

The refrigerant in a liquid state passed through the auxiliary heat exchanger <NUM> is depressurized and expanded while passing through the outdoor expansion valve <NUM> and flows to the rectifier <NUM> in a state where gas and liquid are mixed. Thereafter, the refrigerant flows to the indoor unit through the fourth check valve <NUM> of the rectifier <NUM> and the refrigerant liquid pipe La.

In the cooling operation, because the refrigerant flowing from the outdoor expansion valve <NUM> to the rectifier <NUM> during the cooling operation has a lower pressure than the refrigerant at an outlet side of the outdoor heat exchanger <NUM>, the refrigerant flows to the fourth check valve <NUM> without flowing toward the second check valve <NUM>, and the refrigerant passed through the fourth check valve <NUM> flows to the refrigerant liquid pipe La without flowing toward the first check valve <NUM> according to the same principle.

The refrigerant introduced into the indoor unit <NUM> through the refrigerant liquid pipe La is cooled by being further depressurized in the indoor expansion valves 11A and 11B and then evaporated by heat exchange with the indoor air in the indoor heat exchangers 12A and 12B. The refrigerant in a gaseous state (strictly close to gas but mixed with gas and liquid) passed through the indoor heat exchangers 12A and 12B flows to the outdoor unit <NUM> through the refrigerant gas pipe Lb and then is sucked into the compressor <NUM> after passing through the accumulator <NUM>.

In the cooling operation, the rectifier <NUM> allows the refrigerant passed through the outdoor heat exchanger <NUM> to flow to the auxiliary heat exchanger <NUM> and allows the refrigerant passed through the outdoor expansion valve <NUM> to flow to the indoor expansion valves 11A and 11B. Accordingly, the refrigerant delivered from the outdoor heat exchanger <NUM> passes through the auxiliary heat exchanger <NUM> and the outdoor expansion valve <NUM> in order and then flows to the indoor expansion valves 11A and 11B.

In the heating operation, the refrigerant charged in the refrigerant circuit <NUM> circulates through the compressor <NUM>, the refrigerant gas pipe Lb, the indoor heat exchangers 12A and 12B, the indoor expansion valves 11A and 11B, the refrigerant liquid pipe La, the first check valve <NUM>, the auxiliary heat exchanger <NUM>, the outdoor expansion valve <NUM>, the second check valve <NUM>, the outdoor heat exchanger <NUM>, the accumulator <NUM>, and the compressor <NUM> in order.

The refrigerant in a high-temperature gaseous state delivered from the compressor <NUM> flows to the indoor heat exchangers 12A and 12B through the refrigerant gas pipe Lb and is liquefied by heat exchange with the indoor air in the heat exchangers 12A and 12B. The refrigerant in a liquid state passed through the indoor heat exchangers 12A and 12B is depressurized and expanded in the indoor expansion valves 11A and 11B and then flows to the outdoor unit <NUM> through the refrigerant liquid pipe La in a state where gas and liquid are mixed.

Thereafter, the refrigerant flows to the auxiliary heat exchanger <NUM> through the first check valve <NUM> of the rectifier <NUM> and then is cooled by heat exchange with the refrigerant flowing through the injection passage <NUM> in the auxiliary heat exchanger <NUM>. The gas-liquid mixed refrigerant passed through the auxiliary heat exchanger <NUM> is further depressurized and cooled in the outdoor expansion valve <NUM> and then flows to the outdoor heat exchanger <NUM> through the second check valve <NUM> of the rectifier <NUM>.

In the heating operation, because the refrigerant flowing from the outdoor expansion valve <NUM> to the rectifier <NUM> has a lower pressure than the refrigerant at outlet sides of the indoor expansion valves 11A and 11B, the refrigerant flows to the second check valve <NUM> without flowing toward the fourth check valve <NUM>, and the refrigerant passed through the second check valve <NUM> flows to the outdoor heat exchanger <NUM> without flowing toward the third check valve <NUM> according to the same principle.

The gas-liquid mixed refrigerant is heated by heat exchange with a high-temperature outdoor air in the outdoor heat exchanger <NUM> and then sucked into the compressor <NUM> through the accumulator <NUM>.

In the heating operation, the rectifier <NUM> allows the refrigerant passed through the indoor expansion valves 11A and 11B to flow to the auxiliary heat exchanger <NUM> and allows the refrigerant passed through the outdoor expansion valve <NUM> to flow to the outdoor heat exchanger <NUM>. Accordingly, the gas-liquid mixed refrigerant delivered from the indoor expansion valves 11A and 11B passes through the auxiliary heat exchanger <NUM> and the outdoor expansion valve <NUM> in order and then flows to the outdoor heat exchanger <NUM>.

The air conditioner <NUM> according to the first embodiment may reduce the amount of refrigerant flowing through the refrigerant circuit <NUM>, and may prevent a decrease in operating efficiency in both the cooling operation and the heating operation.

Specifically, the air conditioner <NUM> according to the first embodiment may reduce the amount of refrigerant charged in the refrigerant circuit <NUM> because the refrigerant flowing through the refrigerant liquid pipe La between the outdoor unit <NUM> and the indoor unit <NUM> is maintained in a state where gas and liquid are mixed (two-phase state). In addition, the air conditioner <NUM> according to the first embodiment may suppress the lowering of the performance of the auxiliary heat exchanger <NUM> in both the cooling operation and the heating operation because the rectifier <NUM> rectifies the refrigerant to flow only in a direction from the auxiliary heat exchanger <NUM> toward the outdoor expansion valve <NUM> in both the cooling operation and the heating operation.

In the cooling operation, because the refrigerant passing through the auxiliary heat exchanger <NUM> is maintained in a liquid state having a high density, the performance of the auxiliary heat exchanger <NUM> may be sufficiently exhibited. In the heating operation, because the refrigerant flowing from the indoor unit <NUM> to the outdoor unit <NUM> also flows toward the outdoor expansion valve <NUM> after passing through the auxiliary heat exchanger <NUM>, the performance of the auxiliary heat exchanger <NUM> may be sufficiently exhibited.

<FIG> illustrates a refrigerant circuit of an air conditioner according to a second embodiment.

The air conditioner according to the second embodiment further includes one or more bypass passages bypassing the outdoor expansion valve <NUM> and one or more flow regulating valves <NUM> installed on the one or more bypass passages. One end of the bypass passage <NUM> is connected to an upstream side of the outdoor expansion valve <NUM> and the other end of the bypass passage is connected to a downstream side of the outdoor expansion valve <NUM>. The flow regulating valve <NUM> may be a motorized valve and is connected in parallel with the outdoor expansion valve <NUM>.

When proper heating degree control of the outdoor heat exchanger <NUM> is not possible in an opening degree range of the outdoor expansion valve <NUM> in the heating operation, the air conditioner of the second embodiment may increase an opening degree of the flow regulating valve <NUM> to reduce a flow rate of the refrigerant passing through the outdoor expansion valve <NUM>, thereby properly adjusting the heating degree in the outdoor heat exchanger <NUM>.

<FIG> illustrates a refrigerant circuit of an air conditioner according to a third embodiment.

The air conditioner of the third embodiment may exclude the rectifier <NUM> of the first embodiment. The air conditioner of the third embodiment includes a first outdoor expansion valve <NUM> and a second outdoor expansion valve <NUM> sequentially installed on a refrigerant pipe directing to the indoor expansion valves 11A and 11B from the outdoor heat exchanger <NUM>. The auxiliary heat exchanger <NUM> is provided on a refrigerant pipe between the first outdoor expansion valve <NUM> and the second outdoor expansion valve <NUM>. Accordingly, the indoor expansion valves 11A and 11B, the indoor heat exchangers 12A and 12B, the four-way valves <NUM>, the outdoor heat exchanger <NUM>, the first outdoor expansion valve <NUM>, the auxiliary heat exchanger <NUM>, and the second outdoor expansion valve <NUM> may be connected on the main circuit <NUM> constituting the refrigerant circuit <NUM> in order.

A flow controller according to a third embodiment includes one or more first bypass passages <NUM> bypassing the first outdoor expansion valve <NUM>, one or more first flow regulating valves <NUM> installed on the one or more first bypass passages <NUM>, one or more second bypass passages <NUM> bypassing the second outdoor expansion valve <NUM>, and one or more second flow regulating valves <NUM> installed on the one or more second bypass passages <NUM>.

One end of the first bypass passage <NUM> is connected to an upstream side of the first outdoor expansion valve <NUM> and the other end of the first bypass passage <NUM> is connected to a downstream side of the first outdoor expansion valve <NUM>. The first flow regulating valve <NUM> may be a motorized valve connected in parallel with the first outdoor expansion valve <NUM>. One end of the second bypass passage <NUM> is connected to an upstream side of the second outdoor expansion valve <NUM> and the other end of the second bypass passage <NUM> is connected to a downstream side of the second outdoor expansion valve <NUM>. The second flow regulating valve <NUM> may be a motorized valve connected in parallel with the second outdoor expansion valve <NUM>.

The air conditioner of the third embodiment opens the first flow regulating valve <NUM> in the cooling operation. Accordingly, the refrigerant condensed in the outdoor heat exchanger <NUM> passes through the first outdoor expansion valve <NUM> and the first flow regulating valve <NUM> and then is cooled in the auxiliary heat exchanger <NUM>. The refrigerant cooled in the auxiliary heat exchanger <NUM> becomes in a state where gas and liquid are mixed by being depressurized and expanded in the second outdoor expansion valve <NUM>, and the gas-liquid mixed refrigerant flows to the indoor unit <NUM> through the refrigerant liquid pipe La. Because in the cooling operation the refrigerant passes through the first bypass passage <NUM> connected in parallel with the first outdoor expansion valve <NUM> and then flows to the auxiliary heat exchanger <NUM>, pressure loss of the refrigerant due to the resistance of the first outdoor expansion valve <NUM> may be reduced. Therefore, the lowering of the performance of the auxiliary heat exchanger <NUM> may be suppressed.

The air conditioner of the third embodiment opens the second flow regulating valve <NUM> in the heating operation. Accordingly, the refrigerant condensed in the indoor heat exchangers 12A and 12B passes through the second outdoor expansion valve <NUM> and the second flow regulating valve <NUM> and then is cooled in the auxiliary heat exchanger <NUM>. The refrigerant passed through the auxiliary heat exchanger <NUM> is depressurized and expanded in the first outdoor expansion valve <NUM> and then flows to the outdoor heat exchanger <NUM>. Because in the heating operation the refrigerant passes through the second bypass passage <NUM> connected in parallel with the second outdoor expansion valve <NUM> and then flows to the auxiliary heat exchanger <NUM>, pressure loss of the refrigerant due to the resistance of the second outdoor expansion valve <NUM> may be reduced, and thus, the lowering of the performance of the auxiliary heat exchanger <NUM> may be suppressed.

When proper heating degree control of the outdoor heat exchanger <NUM> is not possible in an opening degree range of the first outdoor expansion valve <NUM> in the heating operation, the air conditioner of the third embodiment may increase an opening degree of the flow regulating valve provided on the first bypass passage <NUM> to reduce a flow rate of the refrigerant passing through the first outdoor expansion valve <NUM>, thereby properly adjusting the heating degree in an outlet of the outdoor heat exchanger <NUM>.

In the air conditioner of the third embodiment, at least one of the first flow regulating valves <NUM> provided on the first bypass passage <NUM> may be replaced with a check valve allowing only a flow of the refrigerant from the outdoor heat exchanger <NUM> toward the auxiliary heat exchanger <NUM>. In addition, in the air conditioner of the third embodiment, at least one of the second flow regulating valves <NUM> provided on the second bypass passage <NUM> may be replaced with a check valve allowing only a flow of the refrigerant from the indoor heat exchangers 12A and 12B toward the auxiliary heat exchanger <NUM>.

<FIG> illustrates a refrigerant circuit of an air conditioner according to a fourth embodiment.

The air conditioner of the fourth embodiment includes a passage changer <NUM> as a passage controller capable of replacing the rectifier <NUM> of the first embodiment. The other configurations of the fourth embodiment are the same as those of the first embodiment.

The passage changer <NUM> may change passages such that the refrigerant flowing from the outdoor heat exchanger <NUM> toward the indoor expansion valves 11A and 11B in the cooling operation or the refrigerant flowing from the indoor expansion valves 11A and 11B toward the outdoor heat exchanger <NUM> in the heating operation sequentially passes through the auxiliary heat exchanger <NUM> and the outdoor expansion valve <NUM>. The passage changer <NUM> may be a motorized type four-way valve changing the passages according to the switching of the cooling operation or the heating operation.

The passage changer <NUM> configured as a motorized type four-way valve may, in the cooling operation, allow the refrigerant passed through the outdoor expansion valve <NUM> to flow to the indoor expansion valves 11A and 11B and allow the refrigerant passed through the outdoor heat exchanger <NUM> to flow to the auxiliary heat exchanger <NUM>. In addition, the passage changer <NUM> may, in the heating operation, allow the refrigerant passed through the indoor expansion valves 11A and 11B to flow to the auxiliary heat exchanger <NUM> and allow the refrigerant passed through the outdoor expansion valve <NUM> to flow to the outdoor heat exchanger <NUM>.

As such, the passage changer <NUM> may perform substantially the same function as the rectifier <NUM> of the first embodiment. Therefore, like the air conditioner of the first embodiment, the air conditioner of the fourth embodiment may also reduce the amount of refrigerant flowing through the refrigerant circuit <NUM> and may prevent the operation efficiency from being lowered in both the cooling operation and the heating operation.

Claim 1:
An air conditioner (<NUM>) comprising a refrigerant circuit (<NUM>), the refrigerant circuit (<NUM>) including:
a compressor (<NUM>);
an outdoor heat exchanger (<NUM>);
an outdoor expansion valve (<NUM>);
an indoor expansion valve (11a, 11b);
a four-way valve (<NUM>);
an indoor heat exchanger (12a, 12b);
an auxiliary heat exchanger (<NUM>) provided on a refrigerant pipe between the outdoor heat exchanger (<NUM>) and the indoor expansion valve (11a, 11b), the auxiliary heat exchanger (<NUM>) connected in series with the outdoor expansion valve (<NUM>);
a rectifier (<NUM>) configured to allow a refrigerant flowing from the outdoor heat exchanger (<NUM>) toward the indoor expansion valve (11a, 11b) in a cooling operation and a refrigerant flowing from the indoor expansion valve (11a, 11b) toward the outdoor heat exchanger (<NUM>) in a heating operation to sequentially flow through the auxiliary heat exchanger (<NUM>) and the outdoor expansion valve (<NUM>);
at least one bypass passage bypassing the outdoor expansion valve (<NUM>);
at least one flow regulating valve (<NUM>) installed on the at least one bypass passage);
an injection passage (<NUM>) including one end connected to an injection inlet of the compressor (<NUM>) and the other end connected between the auxiliary heat exchanger (<NUM>) and the outdoor expansion valve (<NUM>), and configured to allow a part of the refrigerant flowing from the auxiliary heat exchanger (<NUM>) to the outdoor expansion valve (<NUM>) to flow to the compressor (<NUM>) through the auxiliary heat exchanger (<NUM>); and
a supercooling expansion valve (EV) installed in the injection passage (<NUM>) and configured to expand the refrigerant in the injection passage (<NUM>) flowing toward the auxiliary heat exchanger (<NUM>).