JP2012207843A - Heat pump apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump apparatus capable of increasing the amount of circulation using an indoor heat exchanger (evaporator) on the utilization side during cooling operation, for a high efficient operation.SOLUTION: During a cooling operation, a bypass expansion valve 43 is controlled to be opened to form a bypass path. A part of the coolant compressed to an intermediate pressure is bypassed to flow through the bypass path from a point 31d of intermediate pressure of a compressor 31, for heat exchanging by a first internal heat exchanger 41. After being expanded by a bypass expansion valve 43, it is joined to a main coolant circuit at a connection point 43d.

Description

  The present invention relates to a heat pump apparatus including a compressor capable of injection.

  As a conventional heat pump device, for example, there is a “refrigeration device” disclosed in Japanese Patent No. 3858276. This controls the supercooling circuit and the injection circuit with low noise and low cost to improve the refrigeration efficiency. In this refrigeration system, when the injection circuit is substantially stopped, the electric expansion valve is set to a slight opening degree close to full closing to avoid a reduction in the efficiency of the compressor, and the electric expansion valve Is controlled to a desired degree of opening so that the degree of supercooling by the supercooling circuit and the injection amount by the injection circuit can be set to desired values. Further, it is possible to increase the refrigerant circulation amount during the reverse cycle defrost operation during the heating operation.

Japanese Patent No. 3858276

  By the way, in the injection refrigeration cycle in the heat pump apparatus including the compressor capable of injection including the technique disclosed in Patent Document 1 described above, the refrigerant is efficiently used in the use-side indoor heat exchanger (condenser) during heating operation. Although the amount of circulation can be increased, the amount of circulation cannot be increased by the indoor heat exchanger (evaporator) on the use side during cooling operation, which is not suitable for improving the performance during cooling operation compared to during heating operation. There was a problem of being.

  The present invention has been made in view of the above-described conventional problems, and in an injection refrigeration cycle, the amount of circulation can be increased by a use-side indoor heat exchanger (evaporator) during cooling operation, and high efficiency is achieved. It aims at providing the heat pump apparatus which can be drive | operated.

  In order to solve the above problems, a heat pump device according to the present invention includes an evaporator that absorbs heat into a refrigerant, a compressor that can be injected into an intermediate pressure, a condenser that dissipates heat from the refrigerant, and a pressure of the refrigerant. A first expansion valve to be lowered, a main refrigerant circuit connected to circulate the refrigerant, a bypass path connecting between the condenser and the evaporator of the main refrigerant circuit and an intermediate pressure part of the compressor, A first internal heat exchanger that exchanges heat between the main refrigerant between the outlet of the evaporator and the suction of the compressor and a bypass refrigerant compressed to an intermediate pressure, and the first internal heat exchange provided in the bypass path An injection circuit comprising a second expansion valve provided in the bypass path between the condenser and the main refrigerant circuit, wherein the first expansion valve and the second expansion valve are opened. Control to control the degree When the heat exchanger on the use side is an evaporator, the compressor uses the injection circuit to convert the refrigerant from the condenser toward the evaporator after being depressurized by the first expansion valve. And a part of the refrigerant compressed to the intermediate pressure is bypassed and merged.

  Further, in the above invention, a first bypass circuit comprising a four-way valve, provided in the bypass path, bypassing the first internal heat exchanger, and flowing a refrigerant from the second expansion valve toward the compressor, The bypass is performed without passing through the first bypass circuit during the cooling operation, and the bypass refrigerant (injection refrigerant) is exchanged with the first internal heat exchange through the bypass path and the first bypass circuit during the heating operation. Injecting into the compressor is performed without heat exchange in a vessel.

  In the above invention, the second internal heat exchanger provided in the bypass path, the second internal heat exchanger for exchanging heat with the main refrigerant at the outlet of the condenser and the bypass refrigerant decompressed by the second expansion valve. A second bypass circuit that bypasses the compressor and flows the refrigerant from the compressor toward the first internal heat exchanger, and bypasses the bypass path and the second bypass circuit during cooling operation. And performing the heat exchange with the second internal heat exchanger via the bypass path during the heating operation, and performing the injection into the compressor.

  According to the heat pump device of the present invention, during the cooling operation, the refrigerant circulation amount in the indoor heat exchanger (evaporator) on the usage side is increased, and the refrigerant in the outdoor heat exchanger (condenser) on the high pressure side is increased. Since the circulation amount is relatively reduced, a high pressure is suppressed, the compressor power can be reduced, and as a result, a high cooling efficiency can be obtained and a heat pump device capable of performing a high efficiency operation is provided. it can.

It is a refrigerant circuit figure explaining the structure of the heat pump apparatus which concerns on Example 1 of this invention. It is a Mollier diagram in the heat pump device of Example 1. It is a refrigerant circuit figure explaining the structure of the heat pump apparatus which concerns on Example 2 of this invention. It is a refrigerant circuit figure explaining the structure of the heat pump apparatus which concerns on Example 3 of this invention. It is a Mollier diagram in the heat pump apparatus of Example 3. FIG. It is a Mollier diagram in the conventional heat pump apparatus.

  Hereinafter, preferred embodiments according to the present invention will be described in detail in the order of Example 1, Example 2, and Example 3 with reference to the drawings.

  FIG. 1 is a refrigerant circuit diagram illustrating the configuration of the heat pump device according to the first embodiment of the present invention. In the same figure, the heat pump device of this embodiment is a main refrigerant circuit, which includes a compressor 31, a four-way valve 35, a condenser, and a main expansion valve 42 (first An expansion valve) and an evaporator are connected to circulate the refrigerant. The condenser corresponds to the outdoor heat exchanger 11 during the cooling operation and the indoor heat exchanger 21 during the heating operation. The evaporator corresponds to the indoor heat exchanger 21 during the cooling operation, and the outdoor heat exchanger 11 during the heating operation. Further, the evaporator is connected to the suction side of the compressor 31 via the four-way valve 35 and the accumulator 32. Furthermore, in the compressor 31, 31d in a figure becomes a location of intermediate pressure.

  In addition, the heat pump device of the present embodiment is also a circuit that can be injected and can bypass a part of the refrigerant compressed to an intermediate pressure by the compressor 31 toward the main refrigerant circuit (hereinafter referred to as a bypass circuit). A bypass path, a bypass expansion valve 43 (second expansion valve), and a first internal heat exchanger 41 are provided. Here, the bypass path is a refrigerant that is decompressed by the main expansion valve 42 from the outdoor heat exchanger 11 (condenser) and flows toward the indoor heat exchanger 21 (evaporator) during cooling operation. This is a path for bypassing and joining a part of the refrigerant compressed to the pressure, and branching off a part of the refrigerant flowing from the indoor heat exchanger 21 (condenser) toward the main expansion valve 42 during the heating operation. This is a path that can be injected into the intermediate pressure portion 31d of the compressor 31. That is, the bypass path corresponds to a path from the intermediate pressure portion 31d of the compressor 31 to the connection point 43d with the main refrigerant circuit.

  The bypass expansion valve 43 is provided in the bypass path, and reduces the pressure of the refrigerant flowing through the bypass path. The first internal heat exchanger 41 exchanges heat between the main refrigerant between the outlet of the evaporator (indoor heat exchanger 21) and the suction of the compressor 31, and the bypass refrigerant compressed to an intermediate pressure.

  Further, the heat pump device of this embodiment includes control means (not shown) for controlling the opening degrees of the main expansion valve 42 and the bypass expansion valve 43. This control means is incorporated in a controller for controlling the rotational speed of the compressor 31 and the like. During the cooling operation, for example, when the compressor 31 reaches a predetermined rotational speed, a predetermined time before or a predetermined time. After the time, the bypass expansion valve 43 is controlled to open. The suction side pressure of the compressor 31 is detected by installing a temperature sensor in the middle part of the evaporator and estimating it based on the temperature detected by the temperature sensor, or by directly installing a pressure sensor at the corresponding location. To do.

  Next, the basic operation of the heat pump apparatus having the above configuration will be described with reference to FIGS. Here, FIG. 2 is a Mollier diagram at the time of cooling operation in the heat pump apparatus of the present embodiment. Moreover, the arrow attached in FIG. 1 has shown the direction through which a refrigerant | coolant flows at the time of air_conditionaing | cooling operation, and will flow in the direction opposite to the arrow at the time of heating operation.

  During the cooling operation, the four-way valve 35 has the connection relationship shown in FIG. 1, and the bypass expansion valve 43 is controlled to open. First, in the main refrigerant circuit, the compressor 31 is compressed (A1-C1 in FIG. 2). The refrigerant is discharged, passes through the four-way valve 35, is condensed in the outdoor heat exchanger 11 (FIG. 2: C1-E1), is expanded by the main expansion valve 42 (FIG. 2: E1-F1), and the bypass flow is connected to the connection point. 43d, is evaporated in the indoor heat exchanger 21 (FIG. 2: F1-H1), is overheated by the heat exchange in the first internal heat exchanger 41 (FIG. 2: H1-A1), and the four-way valve 35 and the accumulator After 32, it returns to the suction side of the compressor 31.

  On the other hand, in the bypass circuit, a bypass path is formed from the pressure difference between the intermediate pressure portion 31d of the compressor 31 and the connection point 43d of the main refrigerant circuit. In the bypass path, a part of the refrigerant compressed to the intermediate pressure from the intermediate pressure portion 31d of the compressor 31 (FIG. 2: A1-B1) is bypassed, and heat exchange of the first internal heat exchanger 41 (FIG. 2: B1-D1) is cooled, expanded by bypass expansion valve 43 (FIG. 2: D1-F1), and joins the main refrigerant circuit at connection point 43d.

  Further, during the heating operation, the four-way valve 35 is in a connection relationship (not shown) opposite to that in FIG. 1, and when the bypass expansion valve 43 is controlled to open, that is, when injecting, first, the main refrigerant In the circuit, the refrigerant compressed by the compressor 31 is discharged, passes through the four-way valve 35, is condensed by the indoor heat exchanger 21, and a part of the main refrigerant is branched to the bypass path at the connection point 43d. It is expanded by the main expansion valve 42, evaporated by the outdoor heat exchanger 11, is superheated by heat exchange in the first internal heat exchanger 41 via the four-way valve 35, returns to the suction side of the compressor 31 via the accumulator 32, It is compressed by the compressor 31.

  On the other hand, in the bypass circuit, the refrigerant condensed in the indoor heat exchanger 21 branches to the bypass path at the connection point 43d. That is, it is expanded by the bypass expansion valve 43, cooled by heat exchange in the first internal heat exchanger 41, and injected into the intermediate pressure portion 31 d of the compressor 31.

  Here, for comparison with the present embodiment, a conventional heat pump apparatus will be described. In FIG. 6, the Mollier diagram at the time of the air_conditionaing | cooling operation in the conventional heat pump apparatus (patent document 1) is shown. (The same Mollier diagram during heating) In the following description, the names of the components in Patent Document 1 are replaced with the names of the present embodiment.

  In this conventional example, during the cooling operation, in the main refrigerant circuit, the refrigerant compressed by the compressor 31 (Q8-Q2 in FIG. 6) is discharged and condensed in the outdoor heat exchanger 11 (FIG. 6: Q2-Q3). After branching a part of the main refrigerant to the bypass path, the main refrigerant is supercooled by the heat exchange of the first internal heat exchanger 41 (FIG. 6: Q3-Q6) and expanded by the main expansion valve 42 (FIG. 6: Q6-Q7), it is evaporated by the indoor heat exchanger 21 and returns to the suction side of the compressor 31 via the accumulator 32. (FIG. 6: Q7-Q8) In the bypass path, the bypass refrigerant branched from the high-pressure main refrigerant at the outlet of the outdoor heat exchanger 11 (condenser) (FIG. 6: Q3) is expanded by the bypass expansion valve 43. (FIG. 6: Q3-Q4), after heating and evaporation by heat exchange (FIG. 6: Q4-Q5) of the first internal heat exchanger 41, the intermediate pressure of the compressor 31 is injected.

Therefore, in this conventional heat pump device, the increase in the refrigerant circulation amount is always the amount of the bypassed refrigerant (injection flow G _INJ ), and the refrigerant circulation amount on the outdoor heat exchanger 11 side is increased by the injection flow G _INJ . (FIG. 6: G _E + G _INJ ) evaporates due to the subcooling effect (FIG. 6: Q3-Q6) without increasing the refrigerant circulation rate in the indoor heat exchanger 21 on the use side (FIG. 6: G _E ). Enthalpy difference increases, but the dryness of the refrigerant in the increased portion is low (dryness is about 0.05 to 0.1), and the flow rate of the heat exchanger on the use side (indoor heat exchanger 21) is small. Since the flow rate of the refrigerant is low, the heat transfer coefficient of the refrigerant is lowered and the evaporation cannot be performed efficiently. Therefore, it is not suitable for improving the performance during the cooling operation as compared with the heating operation.

  In contrast, in this embodiment, as shown in FIG. 2, the increase in the refrigerant circulation amount is the amount of the bypassed refrigerant (bypass flow G2), and the refrigerant circulation in the indoor heat exchanger 21 on the usage side The amount increases by the bypass flow G2 (FIG. 2: G1 + G2), and the refrigerant circulation amount does not increase on the outdoor heat exchanger 11 side (FIG. 2: G1). Also, compared to the conventional example, the dryness of the evaporator inlet is high (0.2 to 0.3), the flow rate of the heat exchanger on the use side is increased, and the flow rate of the refrigerant is increased. The transmission rate is improved and evaporation can be performed efficiently.

  Usually, the indoor heat exchanger 21 on the use side has a smaller heat exchanger size (heat transfer area) and air volume than the outdoor heat exchanger 11, so that the refrigerant on the use side even during cooling as in the present invention. The performance can be improved more efficiently by improving the heat transfer performance. On the other hand, the outdoor heat exchanger 11 that is not on the use side during cooling is much larger in heat exchanger size (heat transfer area) and air volume than the indoor heat exchanger 21, so that the heat transfer of the refrigerant due to an increase in the flow rate. The performance improvement has less influence than the user side, and an efficient performance improvement cannot be expected.

  As an effect of the first internal heat exchanger 41 in the present invention, the degree of suction superheat is ensured to improve the reliability of the compressor 31, and the increased degree of superheat increases the condensation enthalpy difference on the condensation side and releases it. Increases heat quantity and improves heat dissipation efficiency. This corresponds to the expansion of the evaporation enthalpy due to the supercooling effect of the internal heat exchanger in the conventional example.

  As described above, in the heat pump apparatus of the present embodiment, during the cooling operation, the bypass expansion valve 43 is controlled to be opened to form a bypass path, and the intermediate pressure point 31d of the compressor 31 is intermediated in the bypass path. A part of the refrigerant compressed to the pressure is bypassed, heat is exchanged by the first internal heat exchanger 41, expanded by the bypass expansion valve 43, and then joined to the main refrigerant circuit at the connection point 43d. As a result, the refrigerant circulation amount in the indoor heat exchanger 21 on the use side increases by the bypass flow G2 (FIG. 2: G1 + G2), and the refrigerant circulation amount on the outdoor heat exchanger 11 side on the high pressure side (condensation side) Since (FIG. 2: G1) decreases relatively, high pressure is suppressed, and the power of the compressor 31 can be reduced. As a result, high cooling efficiency can be obtained.

  Further, the heat exchange by the first internal heat exchanger 41 can ensure the degree of superheat of the suction of the compressor 31, and thus the reliability of the compressor 31 can be improved.

  Next, FIG. 3 is a refrigerant circuit diagram illustrating the configuration of the heat pump device according to the second embodiment of the present invention. In FIG. 3A, the refrigerant flow during the cooling operation is indicated by an arrow, and in FIG. 3B, the refrigerant flow during the heating operation is indicated by an arrow. The heat pump device of the present embodiment is provided in a bypass path in the configuration of the heat pump device of Embodiment 1 (see FIG. 1), bypasses the first internal heat exchanger 41 during heating operation, and bypasses the bypass expansion valve 43. It is the structure further provided with the 1st detour circuit which flows a refrigerant | coolant toward the location 31d of the intermediate pressure of the compressor 31. FIG. Here, the first bypass circuit includes check valves 45 and 46. Since the other components are the same as those in the first embodiment, description thereof is omitted.

  Next, the basic operation of the heat pump apparatus of this embodiment will be described. During the cooling operation, the four-way valve 35 has the connection relationship shown in FIG. 3A. First, in the main refrigerant circuit, the refrigerant compressed by the compressor 31 is discharged, passes through the four-way valve 35, and the outdoor heat exchanger. 11, expanded by the main expansion valve 42, the bypass flow merges at the connection point 43 d, is evaporated by the indoor heat exchanger 21, is superheated by heat exchange of the first internal heat exchanger 41, and the four-way valve 35 and It returns to the suction side of the compressor 31 via the accumulator 32. On the other hand, in the bypass circuit, a part of the refrigerant compressed to the intermediate pressure from the intermediate pressure portion 31 d of the compressor 31 is bypassed, cooled by heat exchange of the first internal heat exchanger 41, and expanded by the bypass expansion valve 43. After that, it joins the main refrigerant circuit at the connection point 43d.

  Further, during the heating operation, the four-way valve 35 has the connection relationship shown in FIG. 3B, and when injection is performed, first, the refrigerant compressed by the compressor 31 is discharged in the main refrigerant circuit, and the four-way valve 35 It passes through the valve 35 and is condensed in the indoor heat exchanger 21, and part of the main refrigerant is bypassed toward the intermediate part 31 d of the compressor 31 (injection flow), and the main refrigerant is expanded by the main expansion valve 42, After being evaporated by the heat exchanger 11 and passing through the first internal heat exchanger 41 via the four-way valve 35, the accumulator 32 is returned to the suction side of the compressor 31 and the compressor 31 compresses it. On the other hand, the refrigerant branched at the connection point 43d is expanded by the bypass expansion valve 43, and then is not subjected to heat exchange by the first internal heat exchanger 41 by the first bypass circuit, so that the intermediate pressure point 31d of the compressor 31 is obtained. Liquid injection.

  Here, this example specifically assumes heating at a low outside air temperature in a cold region (for example, −10 ° C. to −25 ° C.), and Example 1 was performed under such a low outside air temperature condition. In this case, since the temperature difference of the heat exchange of the first internal heat exchanger 41 is increased, the cooling effect is increased, and the injection refrigerant (bypass refrigerant) becomes a completely supercooled liquid. When this is injected, liquid compression is caused and the reliability of the compressor is lowered. (The dryness of a normal liquid injection refrigerant is around 0.2.) That is, Example 2 aims to avoid this.

  As described above, in the heat pump device of the present embodiment, the refrigerant branched at the connection point 43d during the heating operation is expanded by the bypass expansion valve 43, and then the heat exchange effect by the first internal heat exchanger 41 is affected. In this way, the liquid injection equivalent to the conventional one can be performed during heating operation, and the refrigerant circulation amount is bypassed by the outdoor heat exchanger 11 on the use side. Thus, the reliability of the compressor 31 can be prevented from being lowered particularly during operation at a low outside temperature while improving the heating efficiency during the heating operation. In addition, about the time of air_conditionaing | cooling operation, there can exist an effect equivalent to Example 1. FIG.

  Next, FIG. 4 is a refrigerant circuit diagram illustrating the configuration of the heat pump device according to the third embodiment of the present invention. In FIG. 4A, the refrigerant flow during the cooling operation is indicated by an arrow, and in FIG. 4B, the refrigerant flow during the heating operation is indicated by an arrow. The heat pump device of the present embodiment is the same as the heat pump device of the first embodiment (see FIG. 1), and heat exchange is performed with the main refrigerant at the outlet of the condenser and the bypass refrigerant decompressed by the second expansion valve 43 of the bypass circuit during heating operation. The second internal heat exchanger 51 is provided in a bypass path, bypasses the second internal heat exchanger 51 during cooling operation, and travels from the intermediate pressure portion 31d of the compressor 31 toward the first internal heat exchanger 41. And a second bypass circuit for flowing the refrigerant. Here, the second bypass circuit includes check valves 55 and 56. Since the other components are the same as those in the first embodiment, the description thereof is omitted. Here, the check valves 55 and 56 are provided as the second bypass circuit, but a bypass may be provided using an electromagnetic valve or a three-way valve.

  Here, detouring of the second internal heat exchanger 51 will be described. When the bypass is not performed, the main refrigerant and the bypass refrigerant once exchange heat, and then the refrigerant joins again. Therefore, the heat exchange is not substantially performed. However, when the loss of merging is taken into account, for example, the merging loss becomes large when the dryness of the main refrigerant and the bypass refrigerant is greatly different due to heat exchange, or when the flow aspect changes greatly. In some cases, more efficient operation control can be expected without unnecessary heat exchange.

  Contrary to the above, when the influence of the merging loss between the main refrigerant and the bypass refrigerant is small, the second bypass circuit is not provided. As described above, the bypass of the second internal heat exchanger is appropriately selected in accordance with various refrigeration cycle conditions including capacity and use environment conditions such as a refrigerator, an air conditioner, and a water heater.

  Next, the basic operation of the heat pump apparatus of this embodiment will be described. During the cooling operation, the four-way valve 35 has a connection relationship shown in FIG. 4A. First, in the main refrigerant circuit, refrigerant compressed by the compressor 31 is discharged, condensed in the outdoor heat exchanger 11, and main expansion. After being expanded by the valve 42 and passing through the second internal heat exchanger 51 with little heat exchange, the bypass flow merges at the connection point 43d, is evaporated by the indoor heat exchanger 21, passes through the four-way valve 35, and the first internal It is overheated by heat exchange of the heat exchanger 41 and returns to the suction side of the compressor 31 via the accumulator 32. On the other hand, in the bypass circuit, a part of the refrigerant compressed to the intermediate pressure from the intermediate pressure portion 31d of the compressor 31 is bypassed, and the second bypass circuit is bypassed without performing heat exchange by the second internal heat exchanger 51. After passing, it is cooled by heat exchange of the first internal heat exchanger 41, expanded by the bypass expansion valve 43, and then merges with the main refrigerant circuit at the connection point 43d.

  Further, the basic operation during the heating operation will be described with reference to FIG. Here, FIG. 5 is a Mollier diagram at the time of injection of the heating operation in the heat pump apparatus of the present embodiment. At the time of heating operation, the four-way valve 35 has a connection relationship shown in FIG. 4B. When injection is performed, the main refrigerant circuit is first compressed by the compressor 31 (A2-B2- in FIG. 5). C2-D2) The refrigerant is discharged, passes through the four-way valve 35, is condensed in the indoor heat exchanger 21 (FIG. 5: D2-E2), and a part of the main refrigerant is bypassed toward the intermediate part 31d of the compressor 31. (FIG. 5: E2), the main refrigerant is expanded by the main expansion valve 42 after being supercooled by heat exchange (FIG. 5: E2-F2) of the second internal heat exchanger 51 (FIG. 5: F2-L2). Evaporated in the outdoor heat exchanger 11 (FIG. 5: L2-M2), passed through the four-way valve 35, overheated by the heat exchange in the first internal heat exchanger 41 (FIG. 5: M2-A2), and compressed through the accumulator 32 It returns to the suction side of the machine 31 and is compressed by the compressor 31.

  On the other hand, in the bypass circuit, the refrigerant branched at the connection point 43d (FIG. 5: E2) is expanded by the bypass expansion valve 43 (FIG. 5: E2-H2), and then the heat exchange of the first internal heat exchanger 41 ( FIG. 5: After being cooled by H2-J2), after being further heated and evaporated by heat exchange (FIG. 5: J2-K2) of the second internal heat exchanger 51, the degree of dryness is increased. It is injected into the intermediate pressure point 31d. Since the second internal heat exchanger 51 can avoid the injection of the supercooled liquid described in the second embodiment ([0032]), the first bypass circuit (see FIG. 3) becomes unnecessary. Yes.

  As described above, in the heat pump device of the present embodiment, during the cooling operation, the heat exchange by the second internal heat exchanger 51 is not performed, a bypass path equivalent to that of the first embodiment is formed, and the heating operation is performed. At the time of injection, the refrigerant branched at the connection point 43 d is expanded by the bypass expansion valve 43, and then subjected to heat exchange by the first internal heat exchanger 41 and heat exchange by the second internal heat exchanger 51, and the compressor 31. The intermediate pressure portion 31d is injected. That is, in both the cooling and heating operations, the refrigerant circulation rate can be increased by the use-side heat exchanger, so that a more efficient heat pump device can be obtained.

  At the time of the injection of the heating operation, as shown in FIG. 5, the dryness of the injection (FIG. 5: K2) is reduced by the amount of heat exchange (FIG. 5: H2-J2) by the first internal heat exchanger 41, The effect of reducing the discharge temperature can be enhanced as compared with normal gas injection and high-dryness two-phase injection. In addition, about the time of air_conditionaing | cooling operation, there can exist an effect equivalent to Example 1. FIG.

  Although the preferred embodiments of the present invention have been described in detail above, the heat pump device according to the present invention is not limited to the above-described embodiments, and is within the scope of the gist of the present invention described in the claims. Various modifications and changes are possible. For example, in the description of the embodiment, the compressor 31 is not particularly limited, but the present invention can be applied to a heat pump apparatus having various compressors 31 such as a rotary type, a scroll type, or a reciprocating type. For example, as a scroll compressor capable of injection, an injection port is provided that can discharge the refrigerant into a compression chamber having a refrigerant compressed to an intermediate pressure among a plurality of compression chambers partitioned by a fixed scroll and a turning scroll. There is. The refrigerant compressed to the intermediate pressure may be discharged from the injection port and bypassed to the main refrigerant circuit to increase the refrigerant circulation amount. The compressor 31 may be a multistage compression mechanism having two or more stages. Furthermore, although it demonstrated with the Example supposing the air conditioner, the indoor heat exchanger 21 may be a chiller etc. which used the refrigerant | coolant-water heat exchanger, and it is not limited about a refrigerant | coolant. In addition to chlorofluorocarbon refrigerants, CO2 and HFO refrigerants may be used.

DESCRIPTION OF SYMBOLS 11 Outdoor heat exchanger 21 Indoor heat exchanger 31 Compressor 32 Accumulator 35 Four-way valve 41 1st internal heat exchanger 41a-41d, 51a-51d Entrance / exit 42 Main expansion valve (1st expansion valve)
43 Bypass expansion valve (second expansion valve)
45, 46, 55, 56 Check valve 51 Second internal heat exchanger

Claims (3)

An evaporator that absorbs heat into the refrigerant, a compressor that can inject the intermediate pressure, a condenser that dissipates the heat of the refrigerant, and a first expansion valve that reduces the pressure of the refrigerant are connected to circulate the refrigerant. Main refrigerant circuit,
Compressed to a main refrigerant and intermediate pressure between the condenser and the evaporator of the main refrigerant circuit and a bypass path connecting the intermediate pressure portion of the compressor, and between the outlet of the evaporator and the suction of the compressor. A first internal heat exchanger in which the bypass refrigerant exchanges heat, and a second expansion valve provided in the bypass path and provided in the bypass path between the first internal heat exchanger and the main refrigerant circuit. A configured injection circuit; and
A heat pump device comprising:
Control means for controlling the opening degree of the first expansion valve and the second expansion valve;
When the heat exchanger on the user side is an evaporator,
Using the injection circuit, the refrigerant flowing from the condenser toward the evaporator after being depressurized by the first expansion valve is joined by bypassing a part of the refrigerant compressed to the intermediate pressure by the compressor. A heat pump device characterized by that. Means for switching a refrigerant flow path between heating and cooling; provided in the bypass path; bypassing the first internal heat exchanger; and flowing the refrigerant from the second expansion valve toward the compressor Further comprising a bypass circuit,
2. The heat pump device according to claim 1, wherein during the heating operation, the compressor is injected through the bypass path and the first bypass circuit. A second internal heat exchanger that exchanges heat with the main refrigerant at the outlet of the condenser and the bypass refrigerant decompressed by the second expansion valve;
A second bypass circuit that is provided in the bypass path, bypasses the second internal heat exchanger, and flows a refrigerant from the compressor toward the first internal heat exchanger;
During cooling operation, bypass is performed via the bypass path and the second bypass circuit, and during heating operation, heat exchange is performed by the second internal heat exchanger via the bypass path to perform injection to the compressor. The heat pump device according to claim 1, wherein the heat pump device is performed.

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