WO2022065964A1

WO2022065964A1 - Heat pump

Info

Publication number: WO2022065964A1
Application number: PCT/KR2021/013175
Authority: WO
Inventors: 오승택; 신정섭; 강수진; 전봉길
Original assignee: 엘지전자 주식회사
Priority date: 2020-09-28
Filing date: 2021-09-28
Publication date: 2022-03-31
Also published as: KR20220043958A

Abstract

A heat pump is disclosed. The heat pump of the present disclosure comprises: a compressor for compressing a refrigerant; a heat exchanger through which the refrigerant discharged from the compressor can be introduced and which includes a first heat exchanger and a second heat exchanger; a switching valve which selectively guides the refrigerant discharged from the compressor, to the first heat exchanger or the second heat exchanger; a main expansion valve which is installed in a main pipe connecting the first heat exchanger and the second heat exchanger and expands the refrigerant flowing through a flow path of the main pipe; an injection pipe having one end connected to the main pipe between the first heat exchanger and the main expansion valve and the other end connected to the compressor; an injection valve which is installed on the injection pipe to control an opening degree of a flow path of the injection pipe; and a supercooler which is installed in the main pipe between one end of the injection pipe and the main expansion valve, wherein the main pipe includes a first heat exchange pipe positioned inside the supercooler, and the injection pipe includes a second heat exchange pipe positioned inside the supercooler and adjacent to the first heat exchange pipe.

Description

heat pump

The present disclosure relates to a heat pump. In particular, the present disclosure relates to a heat pump capable of preventing an excessive increase in the temperature of a refrigerant discharged from a compressor and increasing a refrigerant circulation amount.

In general, a heat pump refers to a device that cools and cools a room through the process of compression, condensation, expansion, and evaporation of a refrigerant. If the outdoor heat exchanger of the heat pump functions as a condenser, but the indoor heat exchanger functions as an evaporator, the room may be cooled. Conversely, when the outdoor heat exchanger of the heat pump functions as an evaporator, but the indoor heat exchanger functions as a condenser, the room may be heated.

On the other hand, when the room is heated using a heat pump in a cold region environment where the outside temperature is 0° C. or less, the compressor operates at a high compression ratio and the temperature of the refrigerant discharged from the compressor may increase excessively. As a result, internal components of the compressor may be damaged, and the amount of refrigerant circulation may be reduced, and thus heating performance may be deteriorated.

Japanese Patent Laid-Open No. 28166706 (published date: September 15, 2016) discloses a technique of injecting a refrigerant into a compressor after supercooling some of the refrigerant that has passed through a condenser. can be a huge burden on

Japanese Laid-Open Patent Publication No. 21243793 (published date: October 22, 2009) discloses a technique of supercooling by heat-exchanging a gaseous refrigerant sucked into a compressor with a first expanded liquid refrigerant through a condenser outlet, but re-evaporated refrigerant In the process of liquefaction, cycle performance is expected to decrease, and there is a problem in that the material cost increases due to the additional configuration.

SUMMARY OF THE INVENTION The present disclosure aims to solve the above and other problems.

Another object may be to provide a heat pump capable of preventing an excessive increase in the temperature of the refrigerant discharged from the compressor.

Another object may be to provide a heat pump capable of preventing deterioration of heating performance by increasing the amount of refrigerant circulating through a refrigerant pipe in a cold region environment.

Another object may be to provide a heat pump capable of preventing damage due to liquid compression of the compressor by controlling the dryness of the refrigerant injected into the compressor to a certain level or more.

Another object may be to provide a heat pump capable of improving the compression ratio between the high-pressure stage and the low-pressure stage of the compressor by increasing the pressure of the refrigerant injected into the compressor to a certain level or more.

According to an aspect of the present disclosure for achieving the above or other object, a compressor for compressing the refrigerant; a heat exchanger through which the refrigerant discharged from the compressor can be introduced and having a first heat exchanger and a second heat exchanger; a switching valve selectively guiding the refrigerant discharged from the compressor to the first heat exchanger or the second heat exchanger; a main expansion valve installed in a main pipe connecting the first heat exchanger and the second heat exchanger to expand the refrigerant flowing through the flow path of the main pipe; an injection pipe having one end connected to the main pipe between the first heat exchanger and the main expansion valve and the other end connected to the compressor; an injection valve installed on the injection pipe to control an opening degree of a flow path of the injection pipe; and a supercooler installed in the main pipe between one end of the injection pipe and the main expansion valve, wherein the main pipe includes a first heat exchange pipe positioned inside the supercooler, and the injection pipe includes the It is located inside the supercooler and provides a heat pump including a second heat exchange pipe adjacent to the first heat exchange pipe.

The effect of the heat pump according to the present disclosure will be described as follows.

According to at least one embodiment of the present disclosure, it is possible to provide a heat pump capable of preventing an excessive increase in the temperature of the refrigerant discharged from the compressor.

According to at least one embodiment of the present disclosure, it is possible to provide a heat pump capable of preventing deterioration of heating performance by increasing the amount of refrigerant circulating through a refrigerant pipe in a cold region environment.

According to at least one embodiment of the present disclosure, it is possible to provide a heat pump capable of preventing damage due to liquid compression of the compressor by controlling the dryness of the refrigerant injected into the compressor to a certain level or more.

According to at least one embodiment of the present disclosure, it is possible to provide a heat pump capable of improving the compression ratio between the high-pressure stage and the low-pressure stage of the compressor by increasing the pressure of the refrigerant injected into the compressor to a certain level or more.

Further scope of applicability of the present disclosure will become apparent from the following detailed description. However, it should be understood that the detailed description and specific embodiments such as preferred embodiments of the present disclosure are given by way of example only, since various changes and modifications within the spirit and scope of the present disclosure may be clearly understood by those skilled in the art.

1 is a diagram illustrating a configuration of a heat pump according to an embodiment of the present disclosure and a flow of a refrigerant while performing a heating operation.

2 is a diagram illustrating a configuration of a heat pump and a flow of a refrigerant while performing a cooling operation according to an embodiment of the present disclosure.

3 is a control system diagram of a heat pump according to an embodiment of the present disclosure.

4 is a diagram illustrating a configuration of a heat pump and a flow of a refrigerant while performing a flash gas injection operation according to an exemplary embodiment of the present disclosure.

5 is a flowchart illustrating a control method for switching from a heating operation to a flash gas injection operation of a heat pump according to an embodiment of the present disclosure.

6 is a flowchart illustrating a method of determining whether a flash gas injection condition is satisfied according to an example of the present disclosure.

7 is a flowchart illustrating a method of determining whether a flash gas injection condition is satisfied according to another example of the present disclosure.

8 is a flowchart illustrating a method for controlling a flash gas injection operation of a heat pump according to an exemplary embodiment of the present disclosure.

9 is a diagram illustrating a configuration of a heat pump according to an embodiment of the present disclosure and a flow of a refrigerant while a high-efficiency operation is performed.

10 is a flowchart illustrating a method for controlling a high-efficiency operation of a heat pump according to an exemplary embodiment of the present disclosure.

Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, but the same or similar components are assigned the same reference numbers regardless of reference numerals, and redundant description thereof will be omitted.

The suffixes "module" and "part" for components used in the following description are given or mixed in consideration of only the ease of writing the specification, and do not have distinct meanings or roles by themselves.

In addition, in describing the embodiments disclosed in the present specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in this specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in this specification, and the technical idea disclosed herein is not limited by the accompanying drawings, and all changes included in the spirit and scope of the present invention , should be understood to include equivalents or substitutes.

Terms including an ordinal number such as 1st, 2nd, etc. may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

When a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component, but it is understood that other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present application, terms such as “comprises” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Referring to FIG. 1 , the heat pump 1 includes a compressor 2 , a switching valve 3 , a first heat exchanger 4 , a second heat exchanger 5 , an accumulator 6 , an expansion valve E, It may include a subcooler (7), a pump (8) and a radiator (9).

The compressor 2 may compress the refrigerant flowing in from the accumulator 6 to discharge the refrigerant of high temperature and high pressure. In this case, the accumulator 6 may provide the gaseous refrigerant to the compressor 2 through the first pipe P1 . Meanwhile, the second pipe P2 may be installed between the compressor 2 and the switching valve 3 to provide a flow path of the refrigerant from the compressor 2 to the switching valve 3 . For example, the compressor 2 may be an inverter compressor capable of controlling the amount of refrigerant and the discharge pressure of the refrigerant by adjusting the operating frequency. For example, the refrigerant may be an R32 refrigerant.

In the switching valve 3 , the refrigerant discharged from the compressor 2 and passing through the second pipe P2 may be introduced. In addition, the switching valve 3 switches the flow path according to the operation mode of the heat pump, and selects the refrigerant introduced by spitting the second pipe P2 to the first heat exchanger 4 or the second heat exchanger 5 . can be guided by For example, the switching valve 3 may be a four-way valve. Meanwhile, the sixth pipe P6 may be installed between the switching valve 3 and the accumulator 6 to provide a flow path of the refrigerant from the switching valve 3 to the accumulator 6 .

The first heat exchanger 4 may exchange heat between the refrigerant and the heat transfer medium. The heat transfer direction between the refrigerant and the heat transfer medium in the first heat exchanger 4 may be different depending on the operation mode of the heat pump. On the other hand, the third pipe (P3) is installed between the switching valve (3) and the first heat exchanger (4), it can provide a flow path of the refrigerant connecting the switching valve (3) and the first heat exchanger (4). .

For example, the heat transfer medium is room air, and heat exchange may be performed between the refrigerant and the room air in the first heat exchanger 4 . In this case, an indoor fan (not shown) may be disposed on one side of the first heat exchanger 4 to control the amount of air provided to the first heat exchanger 4 .

For another example, the heat transfer medium is water, and heat exchange may be performed between the refrigerant and water in the first heat exchanger 4 . In this case, the water that has passed through the first heat exchanger 4 is supplied to the radiator 9 installed in the room or a pipe installed on the floor to cool the indoor space, or to heat or cool water stored in a hot water tank (not shown). It can be used to supply hot or cold water to the room. In this case, the heat pump 1 may be referred to as an air-to-water heat pump (AWHP). In addition, the first heat exchanger 4 may be referred to as a water-refrigerant heat exchanger.

In this case, the heat pump 1 may include a pump 8 and a radiator 9 . When the pump 8 is driven, water can circulate in the water pipe Q. The radiator 9 may be installed indoors, and heated or cooled water may be introduced while passing through the first heat exchanger 4 . For example, heated water passes through the radiator 9 and radiates heat to the surroundings, so that the indoor space can be heated. For example, the cooled water passes through the radiator 9 and absorbs heat from the surroundings, so that the indoor space can be cooled. On the other hand, the heat pump 1 may be provided with a water pipe or FCU (Fan Coil Unit) installed on the floor of the room instead of or together with the radiator 9 .

Meanwhile, the first water pipe Q1 may be installed between the pump 8 and the first heat exchanger 4 to provide a flow path of the refrigerant connecting the pump 8 and the first heat exchanger 4 . In addition, the second water pipe Q2 may be installed between the first heat exchanger 4 and the radiator 9 to provide a water passage connecting the first heat exchanger 4 and the radiator 9 . In addition, the third water pipe Q3 may be installed between the radiator 9 and the pump 8 to provide a water passage connecting the radiator 9 and the pump 8 .

The second heat exchanger 5 may exchange heat between the refrigerant and the heat transfer medium. The heat transfer direction between the refrigerant and the heat transfer medium in the second heat exchanger 5 may be different depending on the operation mode of the heat pump. Meanwhile, the second heat exchanger 5 may be referred to as an outdoor heat exchanger.

For example, the heat transfer medium is outdoor air, and heat exchange may be performed between the refrigerant and outdoor air in the second heat exchanger 5 . In this case, an outdoor fan (not shown) may be disposed on one side of the second heat exchanger 5 to control the amount of air provided to the second heat exchanger 5 . On the other hand, the fifth pipe (P5) is installed between the switching valve (3) and the second heat exchanger (5), it can provide a flow path of the refrigerant connecting the switching valve (3) and the second heat exchanger (5). .

The expansion valve (E) may include a first expansion valve (E1) and a second expansion valve (E2). The first expansion valve E1 and the second expansion valve E2 may be installed on the fourth pipe P4 to adjust the degree of opening of the flow path of the fourth pipe P4 . Here, the fourth pipe (P4) is installed between the first heat exchanger (4) and the second heat exchanger (5), the refrigerant flow path connecting the first heat exchanger (4) and the second heat exchanger (5) can provide Meanwhile, the fourth pipe P4 may be referred to as a main pipe.

For example, the first expansion valve (E1) is disposed closer to the first heat exchanger (4) than the second heat exchanger (5), and the second expansion valve (E2) is second to the first heat exchanger (4). It may be disposed close to the heat exchanger 5 . For example, the first expansion valve E1 and the second expansion valve E2 may be Electronic Expansion Valves (EEVs). Meanwhile, the first expansion valve E1 may be referred to as a sub-expansion valve, and the second expansion valve E2 may be referred to as a main expansion valve.

The supercooler 7 may be installed in the fourth pipe P4 between the first expansion valve E1 and the second expansion valve E2 . In addition, the first heat exchange pipe P4a and the second heat exchange pipe P7a may be positioned inside the supercooler 7 . The first heat exchange pipe P4a and the second heat exchange pipe P7a may be adjacent to each other. For example, the first heat exchange pipe P4a and the second heat exchange pipe P7a may face each other.

Here, the first heat exchange pipe P4a may be a part of the fourth pipe P4 described above, and the second heat exchange pipe P7a may be a part of a seventh pipe P7 to be described later. At this time, one end of the seventh pipe (P7) is connected to the first point (a1) of the fourth pipe (P4) between the first expansion valve (E1) and the supercooler (7), the seventh pipe (P7) The other end may be connected to the compressor (2). Meanwhile, the seventh pipe P7 may be referred to as an injection pipe.

In addition, the injection valve V1 may be installed in the seventh pipe P7 to adjust the opening degree of the flow path of the seventh pipe P7 . In this case, the second heat exchange pipe P7a may be located between the injection valve V1 and the other end of the seventh pipe P7. For example, the injection valve V1 may be a solenoid valve or an Electronic Expansion Valve (EEV).

Meanwhile, the eighth pipe P8 may provide a flow path for guiding the refrigerant discharged from the compressor 2 to the seventh pipe P7 . Specifically, one end of the eighth pipe (P8) is connected to the second point (a2) of the second pipe (P2) between the compressor (2) and the switching valve (3), and the other end of the eighth pipe (P8) is It may be connected to the third point a3 of the seventh pipe P7 between the supercooler 7 and the compressor 2 . Meanwhile, the eighth pipe P8 may be referred to as a bypass pipe.

In addition, the bypass valve V2 is installed in the eighth pipe P8 to adjust the opening degree of the flow path of the eighth pipe P8. For example, the bypass valve V2 may be a solenoid valve or an Electronic Expansion Valve (EEV).

The controller C (not shown) may control the operation of the heat pump 1 . The control unit C may be electrically connected to each component of the heat pump 1 . The control unit C may control each configuration of the heat pump 1 according to the operation mode of the heat pump 1 .

Hereinafter, for a brief description, the heat pump 1 as an AWHP will be described as an example, but the type of heat pump applicable to the present disclosure is not limited thereto, and the refrigerant and the indoor air in the first heat exchanger 4 are The type of heat pump with which the is heat-exchanged can also be applied to the present disclosure.

1 and 2 , the controller C may control the operation of the heat pump 1 to perform a heating operation or a cooling operation.

Referring to FIG. 1 , when a heating operation signal is received by the heat pump 1 , the control unit C adjusts the flow path of the switching valve 3 so that the refrigerant discharged from the compressor 2 is transferred to the first heat exchanger 4 . , the first expansion valve E1 may be fully opened, but the second expansion valve E2 may be opened at an initial opening degree. In addition, the control unit C may close the injection valve V1 and the bypass valve V2. In addition, the control unit (C) may drive the compressor (2) to circulate the refrigerant in the refrigerant pipe (P), and drive the pump (8) to circulate water in the water pipe (Q).

For example, the heating operation signal may be a signal arbitrarily input by the user. For another example, the heating operation signal is provided to the controller C by a thermostat provided in the indoor space when the indoor temperature sensed by the indoor temperature sensor is lower than the desired temperature set by the user by a certain level or more. It may be a signal to

Specifically, the low-temperature, low-pressure refrigerant flowing into the compressor 2 from the accumulator 6 through the first pipe P1 may be compressed in the compressor 2 and discharged in a high-temperature and high-pressure state. The refrigerant discharged from the compressor 2 may flow into the first heat exchanger 4 through the second pipe P2 , the switching valve 3 , and the third pipe P3 in sequence. In addition, water may be introduced from the pump 8 into the first heat exchanger 4 through the first water pipe Q1 .

As thermal energy is transferred from the refrigerant to the water in the first heat exchanger 4 , the refrigerant may be condensed. In this case, the first heat exchanger 4 may function as a condenser. And, according to the heat exchange between the refrigerant and water, the temperature of the water introduced into the first heat exchanger 4 through the first water pipe Q1 may be increased. Water heated while passing through the first heat exchanger 4 may flow into the radiator 9 through the second water pipe Q2 to heat the indoor space. And, the water passing through the radiator 9 and the temperature is lowered may return to the pump 8 through the third water pipe (Q3).

For example, the first heat exchanger 4 may be a plate heat exchanger including a plurality of heat transfer plates stacked on each other. In this case, the refrigerant and water may flow through a flow path formed between the plurality of heat transfer plates and exchange heat with each other in a non-contact manner. As another example, the first heat exchanger 4 may be a water tank in which a port through which water is introduced or discharged is formed. In this case, water is stored in the water tank, and a pipe through which a refrigerant flows is provided in a coil shape along an outer circumferential surface of the water tank, so that the refrigerant and water can exchange heat with each other in a non-contact manner.

Meanwhile, the refrigerant condensed while passing through the first heat exchanger 4 may pass through the fourth pipe P4 . At this time, the first expansion valve E1 may be completely opened, so that the refrigerant passing through the first expansion valve E1 may not be expanded. However, the second expansion valve E2 may be opened to a predetermined opening degree to expand the refrigerant passing through the second expansion valve E2 . The refrigerant expanded through the second expansion valve E2 may be introduced into the second heat exchanger 5 through the distributor 5a.

As thermal energy of outdoor air is transferred from the second heat exchanger 5 to the refrigerant, the refrigerant may be evaporated. In this case, the second heat exchanger 5 may be referred to as an evaporator. The refrigerant evaporated through the second heat exchanger (5) is the header (5b), the fifth pipe (P5), the switching valve (3), the sixth pipe (P6), the accumulator (6), and the first pipe (P1) It may be introduced into the compressor (2) through in turn. Accordingly, the cycle for the heating operation of the above-described heat pump can be completed.

Referring to FIG. 2 , when a cooling operation signal is received by the heat pump 1 , the controller C adjusts the flow path of the switching valve 3 so that the refrigerant discharged from the compressor 2 is transferred to the second heat exchanger 5 . , and the second expansion valve E2 is fully opened, but the first expansion valve E1 may be opened at an initial opening degree. In addition, the control unit C may close the injection valve V1 and the bypass valve V2. In addition, the control unit (C) may drive the compressor (2) to circulate the refrigerant in the refrigerant pipe (P), and drive the pump (8) to circulate water in the water pipe (Q).

For example, the cooling operation signal may be a signal arbitrarily input by the user. For another example, the cooling operation signal is provided to the controller C by a thermostat provided in the indoor space when the indoor temperature detected by the indoor temperature sensor is higher than the desired temperature set by the user. It may be a signal to

Specifically, the low-temperature, low-pressure refrigerant flowing into the compressor 2 from the accumulator 6 through the first pipe P1 may be compressed in the compressor 2 and discharged in a high-temperature and high-pressure state. The refrigerant discharged from the compressor 2 may be introduced into the second heat exchanger 5 through the second pipe P2 , the switching valve 3 , the fifth pipe P5 and the header 5b in sequence.

As heat energy is transferred from the refrigerant to the outdoor air in the second heat exchanger 5, the refrigerant may be condensed. In this case, the second heat exchanger 5 may function as a condenser. The refrigerant condensed while passing through the second heat exchanger 5 may pass through the fourth pipe P4. In this case, the second expansion valve E2 may be completely opened, so that the refrigerant passing through the second expansion valve E2 may not be expanded. However, the first expansion valve E1 may be opened to a predetermined opening degree to expand the refrigerant passing through the first expansion valve E1. The refrigerant expanded through the first expansion valve E1 may be introduced into the first heat exchanger 4 . In addition, water may be introduced from the pump 8 into the first heat exchanger 4 through the first water pipe Q1 .

As thermal energy of water is transferred from the first heat exchanger 4 to the refrigerant, the refrigerant may be evaporated. In this case, the first heat exchanger 4 may function as an evaporator. And, according to the heat exchange between the refrigerant and water, the temperature of the water introduced into the first heat exchanger 4 through the first water pipe Q1 may be decreased. Water cooled while passing through the first heat exchanger 4 may flow into the radiator 9 through the second water pipe Q2 to cool the indoor space. And, the water passing through the radiator 9 and having an increased temperature may return to the pump 8 through the third water pipe Q3.

Meanwhile, the refrigerant evaporated while passing through the first heat exchanger 4 passes through the third pipe P3, the switching valve 3, the sixth pipe P6, the accumulator 6, and the first pipe P1 in order. may be introduced into the compressor (2). Accordingly, the cycle for the cooling operation of the above-described heat pump may be completed.

3, the control unit (C) is electrically connected to the temperature sensor (Sa) and the pressure sensor (Sb), information about the temperature or pressure of the refrigerant flowing through the refrigerant pipe (P) of the heat pump (1) can be obtained. On the other hand, the control unit (C) is electrically connected to the above-described compressor (2), the switching valve (3), the first expansion valve (E1), the second expansion valve (E2), the injection valve (V1) and the bypass valve (V2). connected to each other to control their respective operations.

For example, the temperature sensor Sa may include a first temperature sensor Sa1, a second temperature sensor Sa2, a third temperature sensor Sa3, a fourth temperature sensor Sa4, a fifth temperature sensor Sa5 and At least one of the sixth temperature sensors Sa6 may be included.

The first temperature sensor Sa1 may be installed in the first pipe P1 to detect the temperature of the refrigerant sucked into the compressor 2 . The second temperature sensor Sa2 may be installed in the second pipe P2 to detect the temperature of the refrigerant discharged from the compressor 2 . The third temperature sensor Sa3 may be installed in the first heat exchanger 4 to detect the temperature of the refrigerant passing through the first heat exchanger 4 . The fourth temperature sensor Sa4 may be installed in the second heat exchanger 5 to detect the temperature of the refrigerant passing through the second heat exchanger 5 . The fifth temperature sensor Sa5 is installed in the seventh pipe P7 between the injection valve V1 and the supercooler 7 to detect the temperature of the refrigerant flowing into the second heat exchange pipe P7a. The sixth temperature sensor Sa6 may be installed in the seventh pipe P7 between the supercooler 7 and the compressor 2 to detect the temperature of the refrigerant passing through the second heat exchange pipe P7a.

For example, the pressure sensor Sb may include at least one of a first pressure sensor Sb1 , a second pressure sensor Sb2 , a third pressure sensor Sb3 , and a fourth pressure sensor Sb4 .

The first pressure sensor Sb1 may be installed in the first pipe P1 to detect the pressure of the refrigerant sucked into the compressor 2 . The second pressure sensor Sb2 may be installed in the third pipe P3 to sense the pressure of the refrigerant passing through the third pipe P3 . The third pressure sensor Sb3 may be installed in the fifth pipe P5 to detect the pressure of the refrigerant passing through the fifth pipe P5. The fourth pressure sensor Sb4 may be installed in the seventh pipe P7 between the injection valve V1 and the supercooler 7 to detect the pressure of the refrigerant passing through the injection valve V1 .

4 and 5 , the controller C may or may not inject the flash gas into the compressor 2 by determining whether the flash gas injection condition is satisfied during the heating operation.

As described above with reference to FIG. 1, when a heating operation signal is received (S10), the control unit (C) fully opens the first expansion valve (E1) and opens the second expansion valve (E2) to the initial opening degree, The injection valve V1 and the bypass valve V2 may be closed (S11). Then, the control unit C may drive the compressor 2 (S12) to perform a heating operation of the heat pump.

After S12, the controller C may determine whether the flash gas injection condition is satisfied (S20). Here, the flash gas refers to a refrigerant of two phases, which will be described in more detail later. When the flash gas injection condition is satisfied in S20 (Yes in S20), the controller C may control the flash gas to be injected into the compressor 2 (S30). If the flash gas injection condition is not satisfied in S20 (No in S20), the controller C may maintain a state in which the flash gas is not injected into the compressor 2 (S40).

5 and 6 , whether the flash gas injection condition is satisfied in the aforementioned S20 may be determined based on the compressor suction superheat degree.

Specifically, the controller C may obtain information about the compressor suction temperature Ti, which is the temperature of the refrigerant sucked into the compressor 2 from the first temperature sensor Sa1 (S21). Then, the control unit C may obtain information on the evaporation temperature Te, which is the saturation temperature of the refrigerant evaporated in the second heat exchanger 5 functioning as an evaporator, from the fourth temperature sensor Sa4 (S22) .

Then, the controller C may determine whether the compressor suction superheat, which is the difference between the compressor suction temperature Ti and the evaporation temperature Te, is less than the first reference temperature a1 ( S23 ). For example, the first reference temperature a1 may be 0 °C. In this case, since the compressor suction temperature Ti is smaller than the evaporation temperature Te, the heat pump is operated in a cold region environment, the amount of refrigerant sucked into the compressor 2 is insufficient, and the compressor 2 has a high compression ratio. The operation may cause a problem in that the temperature of the refrigerant discharged from the compressor 2 is excessively increased.

If it is determined in S23 that the compressor suction superheat is less than the first reference temperature a1 (Yes in S23), it may be determined that the flash gas injection condition is satisfied (S24). If it is determined in S23 that the compressor suction superheat is equal to or higher than the first reference temperature a1 (No in S23), it may be determined that the flash gas injection condition is unsatisfactory (S25).

5 and 7 , whether the flash gas injection condition is satisfied in the aforementioned S20 may be determined based on the compressor discharge superheat degree.

Specifically, the controller C may obtain information about the compressor discharge temperature To, which is the temperature of the refrigerant discharged from the compressor 2, from the second temperature sensor Sa2 (S21'). Then, the control unit C may obtain information about the condensation temperature Tc, which is the saturation temperature of the refrigerant condensed in the first heat exchanger 4 functioning as a condenser from the third temperature sensor Sa3 (S22') ).

Then, the controller C may determine whether the compressor discharge superheat, which is the difference between the compressor discharge temperature To and the condensing temperature Tc, exceeds the second reference temperature a2 ( S23 ′). For example, the second reference temperature a2 may be a temperature of 10 to 30 °C. In this case, a problem in that the temperature of the refrigerant discharged from the compressor 2 is excessively high may occur.

If it is determined in S23' that the compressor discharge superheat has exceeded the second reference temperature a2 (Yes in S23'), it may be determined that the flash gas injection condition is satisfied (S24'). If it is determined in S23' that the compressor discharge superheat is equal to or less than the second reference temperature a2 (No in S23'), it may be determined that the flash gas injection condition is unsatisfactory (S25').

5 and 8 , in S30 described above, the controller C may control the flash gas to be injected into the compressor 2 .

Specifically, the controller C may open the injection valve V1 to the initial opening degree (S31) and decrease the opening degree of the second expansion valve E2 (S32). As a result, the injection refrigerant which is a part of the refrigerant flowing through the flow path of the fourth pipe P4 may be bypassed from the first point a1 to the seventh pipe P7 (see FIG. 4 ). In addition, the injection refrigerant may be expanded while passing through the injection valve V1 and may pass through the supercooler 7 through the second heat exchange pipe P7a.

At this time, the main refrigerant, which is the remaining refrigerant except for the injection refrigerant, among refrigerants flowing through the flow path of the fourth pipe P4 may pass through the supercooler 7 through the first heat exchange pipe P4a. In this case, in the supercooler 7, thermal energy is transferred from the main refrigerant flowing through the first heat exchange pipe P4a to the injection refrigerant flowing through the second heat exchange pipe P7a, and the main refrigerant is supercooled , at least a portion of the injection refrigerant may be evaporated.

And, the injection refrigerant that has passed through the supercooler 7 may be injected into the compressor 2 . In this case, the injection refrigerant may be injected into the compressor 2 at an intermediate pressure corresponding to a pressure between the pressure of the refrigerant sucked into the compressor 2 and the pressure of the refrigerant discharged from the compressor 2 .

For example, the injection refrigerant injected into the compressor 2 may be a flash gas as a two-phase refrigerant. In comparison, when the supercooled refrigerant is injected into the compressor (2), damage to the compressor (2) by droplets is concerned, and when the overheated refrigerant is injected into the compressor (2), the temperature of the refrigerant discharged from the compressor (2) It can be difficult to lower. On the other hand, when the injection refrigerant is injected into the compressor 2 as a flash gas, the injection refrigerant will be vaporized while flowing into the compression chamber, so that the risk of damage to the compressor by the above-mentioned droplets can be reduced.

Accordingly, when the flash gas is injected into the compressor 2 , the amount of refrigerant sucked into the compressor 2 may be increased and the temperature of the refrigerant discharged from the compressor 2 may be lowered.

Meanwhile, after S32 , the control unit C may obtain information about the compressor discharge temperature To, which is the temperature of the refrigerant discharged from the compressor 2 , from the second temperature sensor Sa2 ( S33 ). Then, the controller C may determine whether the compressor discharge temperature To is less than the target discharge temperature Ttarget (S34). Here, the target discharge temperature Ttarget is a temperature determined in response to a demand load of the heat pump 1 or the compressor 2 , and may increase in proportion to the demand load. For example, the target discharge temperature Ttarget may be 75°C.

If it is determined in S34 that the compressor discharge temperature To is equal to or greater than the target discharge temperature Ttarget (No in S34), the controller C may return to S32. Accordingly, while the opening degree of the injection valve V1 is maintained, the opening degree of the second expansion valve E2 is reduced than before, so that the amount of refrigerant bypassed from the first point a1 to the seventh pipe P7 is increased. can be increased. As a result, the amount of the injected refrigerant injected into the compressor (2) increases, so that the temperature of the refrigerant discharged from the compressor (2) can be lowered.

If it is determined in S34 that the compressor discharge temperature To is less than the target discharge temperature Ttarget (Yes in S34), the controller C may determine whether the compressor discharge temperature To is less than the minimum temperature Tm ( S35). Here, the minimum temperature Tm is a temperature determined in response to a required load of the heat pump 1 or the compressor 2 , and may be defined as a minimum temperature for achieving the required load. For example, the minimum temperature Tm may be 1 to 3°C smaller than the target discharge temperature Ttarget.

If it is determined in S35 that the compressor discharge temperature To is equal to or higher than the minimum temperature Tm (Yes in S35), the controller C may return to S33. Accordingly, the opening degree of the injection valve V1 and the opening degree of the second expansion valve E2 are maintained, so that the same flash gas injection as before can be performed.

If it is determined in S35 that the compressor discharge temperature To is less than the minimum temperature Tm (No in S35), the controller C may increase the opening degree of the second expansion valve E2. Accordingly, while the opening degree of the injection valve V1 is maintained, the opening degree of the second expansion valve E2 is increased than before, so that the amount of refrigerant bypassed from the first point a1 to the seventh pipe P7 is increased. can be reduced. As a result, the amount of the injected refrigerant injected into the compressor (2) is reduced, so that the temperature of the refrigerant discharged from the compressor (2) can be increased.

9 and 10 , after the aforementioned S30 , the controller C adjusts the opening degree of the bypass valve V2 according to the required load of the heat pump 1 , and the refrigerant discharged from the compressor 2 . It can be controlled so that a part of it is injected into the compressor (2) together with the injection refrigerant that has passed through the above-described supercooler (7).

After S30, the control unit C may determine whether the required load of the heat pump 1 exceeds the reference load (S50). For example, S50 is the compressor (2) to satisfy the indoor heating requirements (ie, heating temperature), such as when the outside air is minus 35 ° C or the target discharge temperature of the refrigerant discharged from the compressor 2 is 75 ° C or higher. This can be satisfied when it is necessary to compress the refrigerant at a high compression ratio.

When it is determined in S50 that the required load of the heat pump 1 exceeds the reference load (Yes in S50), the bypass valve V2 may be opened at a predetermined opening according to the size of the required load to be described later. In this case, the bypass refrigerant, which is a part of the refrigerant flowing through the flow path of the second pipe P2, may be bypassed from the second point a2 to the eighth pipe P8. In addition, the bypass refrigerant passes through the bypass valve V2, expands, and may be introduced into the seventh pipe P7 at the third point a3. On the other hand, the operation having such a flow of the refrigerant may be referred to as a high-efficiency operation of the heat pump.

Accordingly, the bypass refrigerant may be mixed with the injection refrigerant that has passed through the supercooler 7 at the third point a3 of the seventh pipe P7 to be injected into the compressor 2 . At this time, compared to the case where only the injection refrigerant is injected into the compressor 2 , the pressure of the refrigerant injected into the compressor 2 increases due to the bypass refrigerant, and the pressure between the high-pressure end and the low-pressure end of the compressor 2 increases. Compression ratio may be improved to improve compression efficiency or heating performance.

In addition, as the bypass refrigerant is mixed with the injection refrigerant, at least a portion of the injection refrigerant is evaporated, and thus the dryness of the refrigerant injected into the compressor 2 may be increased. In other words, by mixing the bypass refrigerant with the injection refrigerant, the dryness of the refrigerant injected into the compressor 2 can be controlled to a certain level or higher, and as a result, the compressor reliability can be secured by preventing liquid compression of the compressor. there is. In addition, as the refrigerant having a dryness greater than or equal to a certain level is injected into the compressor 2 , the temperature of the refrigerant discharged from the compressor 2 may be stably managed.

Specifically, when it is determined in S50 that the required load of the heat pump 1 exceeds the reference load (Yes in S50), the controller C determines that the required load of the heat pump 1 exceeds the first load L1. It can be determined whether or not (S61).

If it is determined in S61 that the required load exceeds the first load L1 (Yes in S61), the controller C may open the bypass valve V2 to the first opening (S62). As a result, the bypass refrigerant, which is a part of the refrigerant flowing through the flow path of the second pipe P2, may be bypassed from the second point a2 to the eighth pipe P8. In addition, the bypass refrigerant passes through the bypass valve V2 opened to the first opening degree, expands, and flows into the seventh pipe P7 at the third point a3, thereby discharging the supercooler 7 described above. It can be injected into the compressor (2) together with the injection refrigerant that has passed.

If it is determined in S61 that the required load is less than or equal to the first load L1 (No in S61), the control unit C may determine whether the required load of the heat pump 1 exceeds the second load L2 (S63). ). Here, the second load L2 is smaller than the first load L1, and for example, the compression ratio required for the compressor 2 in the second load L2 is from the first load L1 to the compressor 2 It may be smaller than the required compression ratio.

If it is determined in S63 that the required load is less than or equal to the first load L1 but exceeds the second load L2 (Yes in S63), the control unit C may open the bypass valve V2 to the second opening. There is (S64). As a result, the bypass refrigerant, which is a part of the refrigerant flowing through the flow path of the second pipe P2, may be bypassed from the second point a2 to the eighth pipe P8. In addition, the bypass refrigerant passes through the bypass valve V2 opened to the second opening degree, expands, and flows into the seventh pipe P7 at the third point a3, thereby discharging the supercooler 7 described above. It can be injected into the compressor (2) together with the injection refrigerant that has passed.

When it is determined in S63 that the required load is less than or equal to the second load L2 but exceeds the reference load (No in S63), the control unit C may open the bypass valve V2 to the third opening (S65). . As a result, the bypass refrigerant, which is a part of the refrigerant flowing through the flow path of the second pipe P2, may be bypassed from the second point a2 to the eighth pipe P8. In addition, the bypass refrigerant passes through the bypass valve V2 opened to the third opening degree, expands, and flows into the seventh pipe P7 at the third point a3, thereby discharging the supercooler 7 described above. It can be injected into the compressor (2) together with the injection refrigerant that has passed.

Meanwhile, as the size of the required load increases, the opening degree of the bypass valve V2 may be increased, thereby increasing the amount of the bypass refrigerant mixed with the injection refrigerant. That is, the second opening degree may be smaller than the first opening degree, and the third opening degree may be smaller than the second opening degree. In this case, the amount of the bypass refrigerant passing through the bypass valve V2 opened to the second opening may be smaller than the amount of the bypass refrigerant passing through the bypass valve V2 opened to the first opening. there is. In addition, the amount of the bypass refrigerant passing through the bypass valve V2 opened to the third opening may be smaller than the amount of the bypass refrigerant passing through the bypass valve V2 opened to the second opening. . Accordingly, the pressure of the refrigerant injected into the compressor 2 at a relatively large demand load increases, and compression efficiency can be further increased.

According to an aspect of the present disclosure, a compressor for compressing a refrigerant; a heat exchanger through which the refrigerant discharged from the compressor can be introduced and having a first heat exchanger and a second heat exchanger; a switching valve selectively guiding the refrigerant discharged from the compressor to the first heat exchanger or the second heat exchanger; a main expansion valve installed in a main pipe connecting the first heat exchanger and the second heat exchanger to expand the refrigerant flowing through the flow path of the main pipe; an injection pipe having one end connected to the main pipe between the first heat exchanger and the main expansion valve and the other end connected to the compressor; an injection valve installed on the injection pipe to control an opening degree of a flow path of the injection pipe; and a supercooler installed in the main pipe between one end of the injection pipe and the main expansion valve, wherein the main pipe includes a first heat exchange pipe positioned inside the supercooler, and the injection pipe includes the It is located inside the supercooler and provides a heat pump including a second heat exchange pipe adjacent to the first heat exchange pipe.

According to another aspect of the present disclosure, further comprising a control unit for controlling an opening degree of the main expansion valve and an opening degree of the injection valve, wherein the control unit, when a heating operation signal is received, the refrigerant discharged from the compressor The heating operation may be performed by forming a flow path of the switching valve to guide the heat exchanger to the first heat exchanger, opening the main expansion valve to an initial opening degree, and closing the injection valve.

According to another aspect of the present disclosure, when the flash gas injection condition is satisfied during the heating operation, the control unit opens the injection valve to an initial opening degree, and reduces the opening degree of the main expansion valve. to perform a flash gas injection operation.

Further, according to another aspect of the present disclosure, the controller may include a compressor suction superheat degree that is a difference between a compressor suction temperature, which is a temperature of the refrigerant sucked into the compressor, and an evaporation temperature, which is a saturation temperature of the refrigerant passing through the second heat exchanger. When is less than the first reference temperature, it may be determined that the flash gas injection condition is satisfied.

Also, according to another aspect of the present disclosure, the control unit, the compressor discharge superheat which is the difference between the compressor discharge temperature, which is the temperature of the refrigerant discharged from the compressor, and the condensation temperature, which is the saturation temperature of the refrigerant passing through the first heat exchanger When ? exceeds the second reference temperature, it may be determined that the flash gas injection condition is satisfied.

According to another aspect of the present disclosure, when it is determined that, in the flash gas injection operation, the compressor discharge temperature, which is the temperature of the refrigerant discharged from the compressor, is equal to or higher than the target discharge temperature, the control unit determines the opening degree of the injection valve. maintained, and the degree of opening of the main expansion valve can be reduced.

According to another aspect of the present disclosure, when it is determined that, in the flash gas injection operation, the compressor discharge temperature is less than the target discharge temperature and is equal to or greater than a minimum temperature smaller than the target discharge temperature, the The opening degree of the injection valve and the opening degree of the main expansion valve may be maintained.

According to another aspect of the present disclosure, when it is determined that the compressor discharge temperature is less than the target discharge temperature and less than the minimum temperature in the flash gas injection operation, the control unit maintains the opening degree of the injection valve And, it is possible to increase the opening degree of the main expansion valve.

According to another aspect of the present disclosure, a bypass pipe having one end connected to a discharge pipe connecting the compressor and the switching valve and the other end connected to the injection pipe between the supercooler and the compressor; The bypass valve may further include a bypass valve installed on the bypass pipe to adjust an opening degree of a flow path of the bypass pipe.

According to another aspect of the present disclosure, when the required load of the compressor exceeds a reference load while the flash gas injection operation is being performed, the control unit may include the bypass valve in proportion to the size of the required load. can increase the degree of

According to another aspect of the present disclosure, when the required load exceeds a first load while the flash gas injection operation is being performed, the control unit opens the bypass valve to a first opening degree, and When the demand load exceeds a second load smaller than the first load, the bypass valve is opened to a second opening degree smaller than the first opening degree, and when the demand load is less than or equal to the second load but exceeds the reference load , the bypass valve may be opened at a third opening degree smaller than the second opening degree.

Also, according to another aspect of the present disclosure, the injection valve and the bypass valve may be an Electronic Expansion Valve (EEV).

According to another aspect of the present disclosure, the first heat exchanger may be a water-refrigerant heat exchanger for exchanging a refrigerant and water in a non-contact manner, and the second heat exchanger may be an outdoor heat exchanger for exchanging a refrigerant and outdoor air. there is.

Any or other embodiments of the present disclosure described above are not mutually exclusive or distinct. Certain embodiments or other embodiments of the present disclosure described above may be combined or combined with respective configurations or functions.

For example, it means that configuration A described in a specific embodiment and/or drawings may be combined with configuration B described in other embodiments and/or drawings. That is, even if the coupling between the components is not directly described, it means that the coupling is possible except for the case where it is described that the coupling is impossible.

The above detailed description should not be construed as restrictive in all respects and should be considered as exemplary. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present invention are included in the scope of the present invention.

Claims

a compressor that compresses the refrigerant;

a heat exchanger through which the refrigerant discharged from the compressor can be introduced and having a first heat exchanger and a second heat exchanger;

a switching valve selectively guiding the refrigerant discharged from the compressor to the first heat exchanger or the second heat exchanger;

a main expansion valve installed in a main pipe connecting the first heat exchanger and the second heat exchanger to expand the refrigerant flowing through the flow path of the main pipe;

an injection pipe having one end connected to the main pipe between the first heat exchanger and the main expansion valve and the other end connected to the compressor;

an injection valve installed on the injection pipe to control an opening degree of a flow path of the injection pipe; And,

and a supercooler installed in the main pipe between one end of the injection pipe and the main expansion valve,

The main pipe includes a first heat exchange pipe located inside the supercooler,

The injection pipe is located inside the supercooler, and the heat pump includes a second heat exchange pipe adjacent to the first heat exchange pipe.
According to claim 1,

Further comprising a control unit for controlling an opening degree of the main expansion valve and an opening degree of the injection valve,

The control unit is

When a heating operation signal is received,

forming a flow path of the switching valve so that the refrigerant discharged from the compressor is guided to the first heat exchanger;

Open the main expansion valve to the initial opening,

A heat pump for performing a heating operation by closing the injection valve.
3. The method of claim 2,

The control unit is

During the heating operation, if the flash gas injection condition is satisfied,

open the injection valve to the initial opening,

A heat pump for performing a flash gas injection operation by reducing an opening degree of the main expansion valve.
4. The method of claim 3,

The control unit is

If the compressor suction superheat, which is the difference between the compressor suction temperature, which is the temperature of the refrigerant sucked into the compressor, and the evaporation temperature, which is the saturation temperature of the refrigerant passing through the second heat exchanger, is less than the first reference temperature,

A heat pump that determines that the flash gas injection condition is satisfied.
4. The method of claim 3,

The control unit is

When the compressor discharge superheat, which is the difference between the compressor discharge temperature, which is the temperature of the refrigerant discharged from the compressor, and the condensation temperature, which is the saturation temperature of the refrigerant passing through the first heat exchanger, exceeds the second reference temperature,

A heat pump that determines that the flash gas injection condition is satisfied.
4. The method of claim 3,

The control unit is

In the flash gas injection operation,

When it is determined that the compressor discharge temperature, which is the temperature of the refrigerant discharged from the compressor, is equal to or higher than the target discharge temperature,

The heat pump maintains the opening degree of the injection valve and reduces the opening degree of the main expansion valve.
7. The method of claim 6,

The control unit is

In the flash gas injection operation,

When it is determined that the compressor discharge temperature is less than the target discharge temperature and is higher than or equal to the minimum temperature smaller than the target discharge temperature,

A heat pump for maintaining an opening degree of the injection valve and an opening degree of the main expansion valve.
8. The method of claim 7,

The control unit is

In the flash gas injection operation,

When it is determined that the compressor discharge temperature is less than the target discharge temperature and less than the minimum temperature,

The heat pump maintains the opening degree of the injection valve and increases the opening degree of the main expansion valve.
4. The method of claim 3,

a bypass pipe having one end connected to a discharge pipe connecting the compressor and the switching valve, and the other end being connected to the injection pipe between the supercooler and the compressor; And,

The heat pump further comprising a bypass valve installed on the bypass pipe to control an opening degree of a flow path of the bypass pipe.
10. The method of claim 9,

The control unit is

During the flash gas injection operation, if the required load of the compressor exceeds the reference load,

A heat pump for increasing an opening degree of the bypass valve in proportion to the size of the required load.
11. The method of claim 10,

The control unit is

While performing the flash gas injection operation,

When the required load exceeds the first load, the bypass valve is opened to a first opening,

When the demand load exceeds a second load smaller than the first load, opening the bypass valve to a second opening degree smaller than the first opening degree;

When the required load is equal to or less than the second load but exceeds the reference load, the heat pump opens the bypass valve at a third opening degree smaller than the second opening degree.
12. The method of claim 11,

The injection valve and the bypass valve,

A heat pump that is an Electronic Expansion Valve (EEV).
According to claim 1,

The first heat exchanger,

It is a water-refrigerant heat exchanger that heat-exchanges refrigerant and water in a non-contact manner,

The second heat exchanger,

A heat pump, an outdoor heat exchanger that exchanges heat between refrigerant and outdoor air.