Expansion unit for a refrigerant circuit, heat exchanger, and heat pump

Abstract

The invention in particular relates to an expansion unit (30) for a refrigerant circuit of a heat pump, to a heat exchanger (3-1), and to a heat pump. The expansion unit (30) is designed as a functional block for fluidically connecting a compressor (2), a condenser (3), and an evaporator (1) and comprises a first line (4a) with a first inlet (30a) for connection to the refrigerant circuit downstream of the compressor (2) and a first outlet (30b) for connection to the refrigerant circuit upstream of the condenser (3). The expansion unit (30) additionally comprises a second line (4b) with a second inlet (30c) for connection to the refrigerant circuit downstream of the condenser (3) and a second outlet (30d) for connection to the refrigerant circuit upstream of the evaporator (1), an expansion valve (5, 100) which is arranged in the second line (4b), and a third line (4c), by means of which the first inlet (30a) of the first line (4a) can be connected to the second outlet (30d) of the second line (4b).

Description

[0001] EXPANSION UNIT FOR A REFRIGERATING CYCLE, HEAT EXCHANGER AND HEAT PUMP

[0002] The present invention relates to an expansion unit for a refrigeration circuit of a heat pump, a heat exchanger, and a heat pump. Furthermore, the invention relates to a method for operating an expansion unit for a refrigeration circuit, a computing unit, and a computer program for implementing the method.

[0003] Modern heat pumps are characterized by their high efficiency and can therefore be used particularly attractively for heating and / or cooling a building from an ecological and economic point of view.

[0004] A generic heat pump has a circuit for a refrigerant with an evaporator, a compressor, and a condenser. The evaporator absorbs heat, for example, from the environment, which is released in the condenser at a higher temperature level to a secondary circuit, for example, to a building's heating circuit. The higher temperature level is achieved by compressing the refrigerant in the compressor, so that downstream of the compressor, the refrigerant is present as so-called hot gas. To counteract icing of the evaporator at low temperatures, the refrigerant circuit can additionally include a bypass line, through which hot gas escaping from the compressor can be fed to the evaporator if necessary.

[0005] DE 10 2005 034 826 B4 shows a heat pump whose main components are an evaporator, a compressor, a condenser, and a throttle valve, which are connected to a circuit via piping. A hot gas line branches off between the compressor and the condenser, which flows into a circuit pipe on the inlet side of the evaporator. A shut-off valve is installed in the hot gas line. This shut-off valve is closed during normal heat pump operation and opens depending on the temperature in the evaporator to defrost it. Additional valves are arranged in the pipes upstream and downstream of the condenser; these valves are open during normal operation.

[0006] It is clear that a large number of individual components and refrigerant lines are required to operate the heat pump proposed in DE 102005034826 B4, which entails considerable effort with regard to installation and maintenance of the heat pump.

[0007] The present invention is based on the object of simplifying the assembly and maintenance of a heat pump and reducing the number of required components and refrigerant lines.

[0008] This object is achieved by the invention with the features of the independent claims. Advantageous embodiments of the invention are the subject of the dependent claims and the following description.

[0009] An expansion unit for a refrigerant circuit, in particular for a refrigerant circuit of a heat pump, is proposed, which includes a compressor, a condenser, and an evaporator. Furthermore, a heat exchanger in which an expansion unit is integrated and a heat pump with an expansion unit are proposed.

[0010] The invention enables a compact design of a refrigerant circuit by combining and merging several components and functions in one component or component group.

[0011] The expansion unit is designed as a functional block for fluidly connecting the compressor, condenser and evaporator, wherein the term “functional block” is to be understood in particular in such a way that the elements described below and comprised by the expansion unit according to the invention are contained / integrated / combined in a single component or at least in a single assembly of the refrigerant circuit.

[0012] The expansion unit according to the invention comprises a first line with a first inlet for connection to the refrigerant circuit downstream of the compressor and a first outlet for connection to the refrigerant circuit upstream of the condenser. Furthermore, the expansion unit contains a second line with a second inlet for connection to the refrigerant circuit downstream of the condenser and a second outlet for connection to the refrigerant circuit upstream of the evaporator.

[0013] The first line of the expansion unit can, in particular, connect an outlet of the compressor to an inlet of the condenser, while the second line can, in particular, connect an outlet of the condenser to an inlet of the evaporator. An expansion valve is arranged in the second line, which is designed to reduce the refrigerant exiting the condenser from a first pressure level to a second pressure level.

[0014] At the first inlet, hot gas from the compressor can enter the first line of the expansion unit and from there flow to the condenser via the first outlet. At the second inlet, refrigerant from the condenser can enter the second line of the expansion unit, from where it can be expanded by the expansion valve and fed to the evaporator via the second outlet.

[0015] The first pressure level can essentially correspond to a pressure downstream of the compressor at which the refrigerant enters the expansion unit. The compressor can be used to adjust the first pressure level, in particular, such that the refrigerant can condense in the condenser at a required refrigerant temperature to release heat to a secondary circuit. The second pressure level can be adjusted by the expansion valve such that the refrigerant can evaporate in the evaporator at a required refrigerant temperature to absorb heat, e.g., from the environment. Specific values ​​for the first and second pressure levels depend, in particular, on the refrigerant used.

[0016] The expansion valve can also be configured to provide the required amount of refrigerant to be evaporated in the evaporator at a current operating point of the heat pump. In particular, the expansion valve can ensure superheating of the refrigerant downstream of the evaporator, thus preventing liquid refrigerant from entering the compressor. The expansion valve can be a thermostatic or an electronic expansion valve. The latter can be controlled, for example, by a processing unit, which can in particular be a controller of the heat pump, depending on the pressure and temperature of the refrigerant downstream of the evaporator.

[0017] The first outlet of the first line and the second inlet of the second line can in particular be arranged on a first side of the expansion unit which, in the assembled state, faces the condenser. The first inlet of the first line and the second outlet of the second line can be arranged on a second side of the expansion unit opposite the first side which, in the assembled state, faces away from the condenser. In particular, the first outlet and the second inlet of the expansion unit can be connected to the condenser, i.e., can be connected directly to it. In this way, line routing between the expansion unit and the condenser can be avoided and a compact design of the refrigerant circuit can be realized.

[0018] The expansion unit also has a third line, by means of which the first inlet of the first line can be connected to the second outlet of the second line. Thus, hot gas from the compressor can be fed directly to the evaporator through the third line in the expansion unit, e.g., to carry out a defrosting process in the event of icing on the evaporator. To supply hot gas to the evaporator via the third line only when needed, the third line can contain a shut-off device. This can be a mechanically or electrically / electronically actuated shut-off device. Alternatively, the expansion valve can be configured to serve as a shut-off device.

[0019] The lines of the expansion unit (first, second, and third lines) can be designed, for example, as rigid lines, e.g., as pipelines, with the first and second lines being connected to one another via the third line in such a way that the three lines, including the expansion valve and an optional shut-off device, form a single unit. The lines can have a round or rectangular flow cross-section and any desired external shape. In particular, the first, second, and third lines can be formed as a single piece. For this purpose, they can be manufactured, for example, from a blank or formed as a cast part.

[0020] For example, screw connections can be installed at the inlets and outlets of the first and second lines to connect the expansion unit to the compressor, condenser, and evaporator. Other suitable connections are also possible. If the lines are not integral, the third line can be welded to the first and second lines or connected to them using screw connections.

[0021] The expansion unit thus makes it possible to combine several functions and components required in a refrigerant circuit into a single unit. In particular, the expansion unit represents a compact connection between the compressor and the evaporator, which includes the condenser during regular operation of the heat pump and allows for bypassing the condenser if necessary. With the exception of a connecting line from the compressor to the expansion unit, this contains all lines subjected to the second pressure level. This essentially reduces the pressure resistance requirements of the refrigerant circuit to the expansion unit, enabling an efficient and cost-optimized design of the refrigerant circuit.

[0022] According to one embodiment, a bypass valve can be arranged in the third line as a shut-off device, which is designed to control a refrigerant flow through the third line. The bypass valve can, for example, be a solenoid valve that can be actuated, for example, depending on a state variable of the evaporator in order to carry out a defrosting process of the evaporator. For example, the state variable can be an ambient temperature that can be measured using a temperature element. Alternatively or additionally, a temperature of the refrigerant at the inlet of the evaporator can be measured. In particular, a defrosting process can be initiated depending on the ambient temperature and the temperature of the refrigerant at the inlet of the evaporator, wherein a speed of the compressor can also be taken into account.For this purpose, predetermined values ​​of the temperature of the refrigerant at the inlet of the evaporator and the ambient temperature can be stored in a map depending on the compressor speed, and this map can be used to determine whether a defrosting process is necessary.

[0023] The bypass valve can be actuated / controlled in particular by means of a computing unit, which can be the heat pump control system. The bypass valve can be designed as a 2 / 2-way valve in order to completely open and / or close a cross-section of the third line. Alternatively, a proportional or servo valve can be used as a bypass valve in order to continuously adjust a hot gas volume flow through the third line. Alternatively, the expansion valve can be arranged at the second outlet and additionally be configured to control a refrigerant flow through the third line. In other words, in this case the expansion valve can not only serve to expand the refrigerant escaping from the condenser, but can also, if necessary, direct the hot gas flow from the compressor to the evaporator.By arranging the expansion valve at the second outlet of the expansion unit, it is connected to both the second line, which connects the condenser to the evaporator, and the third line, which connects the compressor to the evaporator, and can therefore be used as a combined expansion and bypass valve (combination valve) by means of a suitable adjusting element.

[0024] For this purpose, the combination valve can comprise two refrigerant inlets, a first of which can be connected to the second line of the expansion unit and a second of which can be connected to the third line of the expansion unit. In addition, the combination valve can have a refrigerant outlet that can be connected to or opens into the second outlet of the expansion unit. The two refrigerant inlets and the refrigerant outlet of the combination valve can be arranged in a valve housing that can be mounted in / on the expansion unit. Furthermore, the combination valve can contain an adjusting element that, in a first position, connects the first refrigerant inlet to the refrigerant outlet and, in a second position, connects the second refrigerant inlet to the refrigerant outlet. The adjusting element can be configured to serve both as a throttling element and as a shut-off and flow control element.In order to implement throttling, the adjusting element can, for example, contain a valve needle which, in conjunction with a corresponding valve seat, can form a valve gap through which refrigerant to be evaporated can be metered and made available at the second outlet of the expansion unit. In addition, the adjusting element can, for example, comprise a recess by means of which an opening in the third line of the expansion unit can be released. The recess can be attached to the adjusting element in such a way that the third line is closed when the combination valve is operated as an expansion valve. The combination valve can also be designed as a solenoid valve in order to be able to specifically adjust the throttling for expanding a required amount of refrigerant depending on the pressure and temperature of the refrigerant downstream of the evaporator.In addition, the combi valve, in its function as a bypass valve, can be adjusted depending on the state of the evaporator, e.g., the ambient temperature and / or the temperature of the refrigerant upstream of the evaporator, to open the third line, allowing hot gas to be directed to the evaporator for defrosting. Using the combi valve, a cross-section of the third line can be fully or partially opened. In the latter case, the combi valve can continuously adjust the opening cross-section to control the hot gas flow rate as needed.

[0025] According to one embodiment, the expansion unit can further comprise a refrigerant collector arranged between the second inlet and the expansion valve. The refrigerant collector can thus be arranged in the second line of the expansion valve, in particular integrated therein. For this purpose, the collector can be designed as a single piece with the second line. In particular, all lines of the expansion unit can be designed as a single piece together with the collector. However, it is also possible for the lines of the expansion unit to be designed separately or as a separate unit and to be attached to or in the refrigerant collector. Unneeded refrigerant can be stored in the refrigerant collector when the boundary conditions of the refrigerant circuit vary and can be released again when needed.

[0026] According to one embodiment, one or more sensors and / or one or more actuators can be installed in the first line of the expansion unit. In particular, at least one pressure sensor and / or at least one temperature sensor can be installed in the first line connecting the compressor to the condenser, with which a condensation pressure and / or a condensation temperature can be monitored. Furthermore, a safety high-pressure switch can be installed in the first line, which switches off a compressor drive if the pressure upstream of the condenser is excessively high. For installing the individual sensors / actuators, the first line can have corresponding connection options, e.g., screw threads, adapters, etc. Alternatively or additionally, the one or more sensors / actuators can be installed in the third line of the expansion unit.In this way, all sensors / actuators required in the high-pressure area of ​​the refrigerant circuit can be arranged centrally, which simplifies the assembly of the refrigerant circuit.

[0027] According to one embodiment, the expansion unit may further comprise a housing in which the first, second, and third lines are integrated. The expansion valve contained in the second line, as well as the bypass valve or combination valve, may also be contained, at least partially, in the housing. For example, electrical connections of the valves may be attached to an exterior of the housing, while the mechanical / hydraulic components may be arranged in the housing or in the lines. The housing may enclose the lines and / or the housing and the lines may be formed integrally.

[0028] The refrigerant collector can also be integrated into the housing. For example, the expansion unit can be constructed as a block, with the individual lines and the refrigerant storage unit mounted inside. Alternatively, the first, second, and third lines can run inside the refrigerant storage unit, thus simultaneously serving as the housing.

[0029] A heat exchanger according to the invention contains a condenser and an expansion unit with the features described above. The expansion unit can, in particular, be integrated into the heat exchanger, i.e., the expansion unit and the condenser can be designed as a single component. The heat exchanger can, in particular, be designed as a plate heat exchanger, and the expansion unit can be arranged between individual plates of the heat exchanger or integrated into them.

[0030] According to one embodiment, a third line of the expansion unit, by means of which a first inlet and a second outlet of the expansion unit can be connected, can be installed in a heat transfer element of the heat exchanger. In the case of a plate heat exchanger, the third line can, for example, be incorporated in one or more of its plates.

[0031] A heat pump according to the invention contains a refrigerant circuit with a compressor, a condenser, an evaporator, and an expansion unit with the features described above. In particular, the heat pump can comprise a heat exchanger into which the condenser and the expansion unit are integrated as described above. In other words, the condenser and the expansion unit of the heat pump can be designed as a common component.

[0032] Furthermore, a method for operating an expansion unit for a refrigerant circuit having the features described above, a computing unit, and a computer program for implementing the method are proposed. The refrigerant circuit contains a compressor, a condenser, and an evaporator and is included, in particular, in a heat pump.

[0033] In the method according to the invention, the expansion unit is initially operated in a first operating mode, in which a refrigerant is conducted via a first line of the expansion unit from the compressor to the condenser and through the condenser, and is fed to the evaporator via an expansion valve in a second line of the expansion unit. The first operating mode thus represents regular operation of the heat pump, in which, in accordance with its intended use, it absorbs heat via the evaporator and releases the absorbed heat via the condenser to a secondary circuit, e.g., a building's heating circuit.

[0034] This determines the value of a state variable of the evaporator, which can be used to determine whether the evaporator is iced up and a defrosting process needs to be initiated. For example, the state variable can be an ambient temperature, which can be measured with a temperature element. Alternatively or additionally, the temperature of the refrigerant at the evaporator inlet can be measured with another temperature element. In particular, a defrosting process can be initiated depending on the ambient temperature and the temperature of the refrigerant at the evaporator inlet.

[0035] The value of the state variable can be determined continuously or at predetermined intervals. In particular, the value of the state variable can be determined under predetermined boundary conditions, e.g., at a constant operating point of the heat pump. For this purpose, the compressor speed can also be taken into account.

[0036] If the determined value of the state variable(s) of the evaporator lies within a predetermined value range, the first operating mode of the expansion unit is maintained. In particular, the heat pump can continue to operate normally in this case and no defrosting process is required. When using the ambient temperature as the state variable, the predetermined range can be, for example, above 5°C to 8°C. In particular, predetermined values ​​of the temperature of the refrigerant at the inlet of the evaporator and the ambient temperature can be stored in a characteristic map as a function of the compressor speed, and this characteristic map can be used to determine whether a defrosting process is necessary. If the value of the state variable(s) of the evaporator lies outside the predetermined value range, the expansion unit is operated in a second operating mode.In particular, the expansion unit is switched to the second operating mode by opening a third line, in which mode at least a portion of the refrigerant is conducted from the compressor to the evaporator. In particular, the third line can be opened if it is determined that the value of the state variable leaves the predetermined range. In this way, icing of the evaporator can be counteracted. A computing unit according to the invention comprises a processor which is configured such that it carries out a method with the features described above. The computing unit can in particular be a controller of a heat pump. A method according to the invention is also designed as a computer program with program code for carrying out all of the method steps, so that it can be implemented, for example, in an existing controller of a heat pump.

[0037] BRIEF DESCRIPTION OF THE CHARACTERS

[0038] Figure la shows schematically a refrigerant circuit of a heat pump not according to the invention; and

[0039] Figure 1b shows schematically a refrigerant circuit of a heat pump according to an embodiment of the invention.

[0040] Figures 2a to 2c each schematically show an expansion unit according to an embodiment of the invention in a sectional view.

[0041] Figures 3a and 3b each show an expansion unit according to a further embodiment of the invention in a spatial representation.

[0042] Figures 4a to 4c show the expansion unit shown in Figure 3a in a plan view and in two different sectional views.

[0043] Figures 5a to 5d show the expansion unit shown in Figure 3b in a plan view and in three different sectional views.

[0044] Figure 6 shows schematically a plate heat exchanger in an exploded view, into which an expansion unit according to an embodiment of the invention can be integrated.

[0045] Figures 7a and 7b show a heat pump module into which an expansion unit according to an embodiment of the invention can be integrated. Detailed description of preferred embodiments

[0046] In the following, exemplary embodiments of the present invention are described in detail using exemplary figures. The features of the exemplary embodiments can be combined in whole or in part, and the present invention is not limited to the described exemplary embodiments. In the figures, identical elements are provided with identical reference numerals, so that a repeated description of the elements is omitted unless necessary.

[0047] Figure 1a schematically shows a refrigerant circuit of a heat pump not according to the invention. The refrigerant circuit contains a compressor 2, which is driven by a motor 2a, e.g., an electric motor 2a, a condenser 3, a refrigerant receiver 4, an expansion valve 5, an evaporator 1, and a bypass valve 6, which is arranged between the compressor 2 and the evaporator 1. The individual components of the refrigerant circuit are connected by refrigerant lines (not further designated), which are indicated by arrows that mark a flow direction.

[0048] A filter 5a, 6a is installed upstream of the expansion valve 5 and the bypass valve 6, protecting the valves from any particles. Furthermore, a first pressure and temperature sensor 42 is installed upstream of the compressor 2, and a second pressure sensor 41 and a safety high-pressure switch 40 are installed downstream of the compressor. The first pressure and temperature sensor 42 is signal-connected to the expansion valve 5, and the safety high-pressure switch 40 is signal-connected to the compressor motor 2a (indicated by the thin dashed lines between these elements). Instead of combined pressure and temperature sensors, separate sensors can also be used to measure pressure and temperature. During normal operation of the heat pump, gaseous refrigerant, which has absorbed heat in the evaporator 1, e.g., from the environment, flows from the evaporator 1 to the compressor 2.There the refrigerant is compressed and flows as hot gas from the compressor 2 into the condenser 3.

[0049] The temperature and pressure of the hot gas flowing from compressor 2 can be measured by the second pressure sensor 41. If the pressure downstream of compressor 2 rises to an unacceptably high value, compressor motor 2a can be shut down by the safety high-pressure switch 40.

[0050] In the condenser 3, the refrigerant is liquefied and releases the heat absorbed in the evaporator 1, for example, to a heating circuit (see arrows VL, RL, which indicate a flow and return line, e.g., of a heating circuit). The condensed refrigerant then flows from the condenser into the refrigerant receiver 4 and from there via the filter 5a to the expansion valve 5.

[0051] By means of the expansion valve 5, the refrigerant can be expanded to an initial pressure, allowing it to return to a gaseous state in the evaporator 1 and absorb heat in the process. To supply a suitable amount of refrigerant to the evaporator at each operating point of the heat pump, the expansion valve 5 can receive a signal from the first pressure and temperature sensor 42 and adjust the amount of refrigerant to be introduced into the evaporator according to the measured pressure and temperature upstream of the compressor 2.

[0052] The bypass valve 6 with the upstream filter 6a is arranged between an outlet of the compressor 2 and an inlet of the evaporator 1. This can be used to direct hot gas from the compressor 2 directly into the evaporator 1 in the event of icing on the evaporator, thus defrosting it. Figure 1b schematically shows a refrigerant circuit of a heat pump according to an exemplary embodiment of the invention, which differs from the refrigerant circuit shown in Figure 1a in that it comprises an expansion unit 30 that incorporates all the functions of the components 4, 5, 5a, 6, 6a, 40, 41 outlined in dashed lines in Figure 1a. In other words, all components except the evaporator, the compressor, and the condenser are contained in the expansion unit. As a result, the refrigerant circuit comprises only four central components, which significantly simplifies its assembly and maintenance.

[0053] Detailed embodiments of the expansion unit according to the invention are shown in Figures 2a to 6 and are explained in more detail in connection with these figures.

[0054] Figures 2a to 2c each schematically show an expansion unit 30-1 to 30-3 according to an embodiment of the invention in a sectional view.

[0055] Figure 2a shows an example of an expansion unit 30-1 for use in the refrigerant circuit shown in Figure 1b, which is formed essentially in one piece. The expansion unit 30-1 comprises a first line 4a with a first inlet 30a and a first outlet 30b. The first inlet 30a can be connected to an outlet of the compressor 2 and the first outlet 30b to an inlet of the condenser 3 (see Fig. 1b). Behind the first inlet 30a, the filter 6a is arranged, which prevents particles and moisture from the compressor 2 from entering the expansion unit. The second pressure sensor 41 and the high-pressure safety switch 40 for monitoring the high-pressure region of the refrigerant circuit are mounted in the first line. The expansion unit 30-1 shown also contains a second line 4b with a second inlet 30c and a second outlet 30d.The second inlet 30c can be connected to an outlet of the condenser 3, and the second outlet can be connected to an inlet of the evaporator 1 (see Fig. 1b). Behind the second inlet 30c, the filter 5a is arranged, which prevents the entry of particles and moisture from the condenser 5. The refrigerant collector 4 is integrated into the second line 4b in such a way that phase separation can occur by gravity, and liquid refrigerant is present at the outlet of the refrigerant collector 4. The expansion valve 5 is arranged there, with which the refrigerant can be supplied to the evaporator 1 via the second outlet 30d. The expansion valve 5 can be a thermostatic or an electronic expansion valve.The latter can be controlled, for example, by means of a computing unit (not shown), which can in particular be a controller of the heat pump, depending on a pressure and a temperature of the refrigerant after the evaporator 1.

[0056] Between the first inlet 30a and the second outlet 30d, a third line 4c is arranged, via which hot gas can flow directly from the compressor 2 to the evaporator in order to defrost it if necessary. The bypass valve 6, with which the amount of hot gas through the third line can be controlled, is arranged in the third line 4c. The bypass valve can be, for example, a solenoid valve that can be actuated, for example, depending on a state variable of the evaporator 1 in order to carry out a defrosting process of the evaporator 1. For example, the state variable can be a temperature of the refrigerant at the inlet of the evaporator 1, which can be measured with a temperature sensor at this point (not shown). In particular, an ambient temperature can also be measured with a further temperature sensor (not shown), and icing can be determined based on both temperature values.The speed of the compressor 2 can also be taken into account. In a first operating mode of the heat pump, in which it is in regular operation, the bypass valve 6 closes the third line 4c, and liquid refrigerant escaping from the refrigerant collector 4 is metered into the evaporator via the expansion valve 5 and the second outlet 30d. If, for example, the ambient temperature sensor detects a temperature below a predetermined value, e.g., between 5°C and 8°C, the expansion valve 5 can be closed and the bypass valve 6 opened instead (second operating mode). This allows hot gas to flow directly from the compressor 2 to the evaporator 1, which can counteract icing of the evaporator 2.

[0057] It becomes clear that the exemplary expansion unit 30-1 shown in Figure 2a combines a large number of components and functions of a refrigerant circuit in one component and thus enables a compact design of the same.

[0058] The exemplary expansion unit 30-2 shown in Figure 2b differs from that shown in Figure 2a only by the use of a combination valve 100, which performs the functions of the expansion valve 5 and the bypass valve 6.

[0059] For this purpose, the combination valve 100 is arranged at the second outlet 30d and borders the refrigerant collector 4 with a first refrigerant inlet 5aa and the third line with a second refrigerant inlet 5ab. Furthermore, the combination valve 100 comprises a refrigerant outlet 5ac, which opens into the second outlet 30d of the expansion unit. The adjusting element 100a of the combination valve 100 is designed such that, in a first position, it closes the line 4c and, by means of a small stroke, opens a valve gap to the refrigerant collector 4 (not shown in detail). The refrigerant is significantly throttled in this valve gap, so that the combination valve functions as an expansion valve in this case. The height of the valve gap can be varied in order to provide the required amount of refrigerant to be evaporated, depending on the operating point of the heat pump.In a second position of the adjusting element 100a, it can release the third line 4c, allowing hot gas to flow through the combination valve 100 and the second outlet 30d to the evaporator 1. For this purpose, the adjusting element 100a can, for example, comprise a recess (not shown) by means of which an opening in the third line 4c of the expansion unit 30-2 can be released.

[0060] The combination valve 100 can be designed, for example, as a solenoid valve in order to be able to adjust the throttling for the expansion of a required amount of refrigerant in a targeted manner depending on the pressure and temperature of the refrigerant during its evaporation. In addition, the combination valve 100, in its function as a bypass valve, can be adjusted by means of the electromagnet, for example, depending on the temperature of the refrigerant at the inlet of the evaporator 1 and / or the ambient temperature, such that the third line 4c is opened and a hot gas volume flow required for defrosting the evaporator 1 is directed to it.

[0061] The expansion unit 30-3 shown in Figure 2c essentially corresponds to the one shown in Figure 2b, although in this case, the condenser 3 is directly connected to the expansion unit 30-3. In this way, piping between the expansion unit 30-d and the condenser 3 can be avoided, and the refrigerant circuit can be made even more compact.

[0062] Figures 3a and 3b each show an expansion unit 30-4, 30-5 according to a further embodiment of the invention in a spatial representation, which is connected to a capacitor 3.

[0063] In the expansion unit 30-4 shown in Figure 3a, the first line 4a and the second line 4b are designed as pipelines. The first line 4a comprises the first inlet 30a, which can be connected to the compressor 2, and the first outlet 30b, which is directly connected to an unspecified inlet of the condenser 3, which is arranged at its upper end. The second line 4b comprises the inlet 30c, which is directly connected to an unspecified outlet of the condenser 3, which is arranged at its lower end, and the second outlet 30d, which can be connected to the evaporator 1. The second line 4b is connected to the refrigerant collector 4, inside which the third line 4c is arranged, by means of which the first inlet 30a can be connected to the second outlet 30d (see Fig. 4b).At an upper end of the refrigerant receiver, two screw-in points 40a, 41a are visible for the safety high-pressure switch 40 and the second pressure sensor 41. These are mounted in a branch line inside the refrigerant receiver 4, which is connected to the third line 4c (see Figure 4b). The expansion valve 5 is located at a lower end of the refrigerant receiver 4, and the bypass valve 6 is located in the third line 4c inside the refrigerant receiver 4.

[0064] The expansion unit 30-5 shown in Figure 3b differs from the one shown in Figure 3b in that the third line is provided outside the refrigerant collector 4, between the connection 4ca attached to the first line 4a and the connection 4cb attached to the second line. Furthermore, the safety high-pressure switch 40 and the second pressure sensor 41 are connected to the first line 4a, and an expansion valve 5 is arranged at the second outlet 3d of the expansion unit 30-4. The expansion valve 5 is connected to the refrigerant collector 4 by a first line 5aa as the first refrigerant inlet and to the connection 4cb of the third line by a second line 5ab as the second refrigerant inlet.

[0065] Figures 4a to 4c show the expansion unit 30-4 shown in Figure 3a in a plan view and in two different sectional views.

[0066] Figure 4a shows a top view of the expansion unit 30-4, in which the two sectional planes AA and BB shown in Figures 4b and 4c are marked. The sectional plane AA runs through a center point of the refrigerant collector 4 and intersects the third line 4c, which is arranged inside the refrigerant collector 4. The sectional plane BB lies on a side of the expansion unit 30-4 facing away from the condenser 3, in front of the sectional plane AA and intersects a line 5ba running from the refrigerant collector 4 to the expansion valve 5.

[0067] Figure 4b shows a longitudinal section through the third line 4c, which runs from the first inlet 30a to the second outlet 30d of the expansion unit 30-4. Perpendicular to the third line, at an upper end of the refrigerant collector 4, a branch line (not shown in more detail) is attached, to which the second pressure sensor 41 and the safety high-pressure switch 40 can be connected. A connection 6b for attaching the bypass valve 6 can also be seen in the third line 4c.

[0068] The section plane BB shown in Figure 4c is located on a side of the expansion unit 30-4 facing away from the condenser 3, in front of the third line 4c, and shows a line 5ba running from the refrigerant collector 4 to a connection point 5b of the expansion valve. The connection 6b for the bypass valve 6 as well as the first inlet and second outlet of the expansion unit 30-4 are also visible in this section plane.

[0069] Based on the expansion unit 30-4 shown as an example, it becomes clear that the arrangement of the third line 4c within the refrigerant collector 4 enables a very compact arrangement of the individual valves and sensors.

[0070] Figures 5a to 5d show the expansion unit 30-5 shown in Figure 3b in a plan view and in three different sectional views.

[0071] Figure 5a shows a top view of the expansion unit 30-5, in which the three sectional planes AA, BB, and CC shown in Figures 5b to 5d are marked. The sectional plane AA shown in Figure 5b runs through a center point of the refrigerant collector 4 and intersects a section of the second line 4b, which is designed as a riser and connects the outlet of the condenser 3 to an upper end of the refrigerant collector 4.

[0072] The sectional plane BB shown in Figure 5c is arranged on a side of the expansion unit 30-5 facing away from the condenser 3 in front of the sectional plane AA and intersects a line (not shown in more detail) running from the refrigerant collector 4 to the first refrigerant inlet 5aa of the expansion valve 5.

[0073] The sectional plane CC shown in Figure 5d is arranged on the side of the expansion unit facing away from the condenser 3 in front of the sectional plane BB and intersects a line (not designated in more detail) running from the lower connection 4cb of the third line to the second refrigerant inlet 5ab of the expansion valve 5.

[0074] It is clear that the expansion unit 30-5 shown in this embodiment also has a very compact structure due to the arrangement of the first to third lines and the connection of the expansion valve 5 to the refrigerant collector 4 and the third line 4c.

[0075] Figure 6 schematically shows a plate heat exchanger 3-1 into which an expansion unit according to an embodiment of the invention can be integrated.

[0076] The plate heat exchanger 3-1 contains a plurality of plates 3a to 3e, which form the condenser s and the expansion unit 30-6. In other words, the expansion unit 30-6 is integrated into the plate heat exchanger 3-1 as a plate.

[0077] The plate heat exchanger 3-1 has a pressure-resistant front and rear plate 3a, 3e, respectively. The front plate 3a contains connections for the first inlet 30a and the second outlet 30d of the expansion unit 30-6. Additional connection ports for attaching the second pressure sensor 41 and the high-pressure safety switch 40 in the third line 4c may be provided on the front plate 3a (not shown).

[0078] The heat transfer plates 3d are arranged between the front and rear plates 3a, 3e, followed by a refrigerant collector 4 of the expansion unit 30-6, which can be formed using specially shaped plates. In the present embodiment, thermal insulation 3c is also arranged between the refrigerant collector 4 and the heat transfer plates 3d. A further plate 3b, which contains the third line 4c, is arranged between the refrigerant collector 4 and the front plate 3a. This plate connects the first inlet 30a to the second outlet 30d of the expansion unit 30-6. It is also possible for the thermal insulation 3c to be arranged between the refrigerant collector 4 and the plate 3b.

[0079] In the manner shown, the condenser 3 and the expansion unit 30-6 can form an integral component, whereby the number of components in the refrigerant circuit can be further reduced.

[0080] Figures 7a and 7b show a module of a heat pump into which an expansion unit 30 according to an embodiment of the invention can be integrated.

[0081] The individual components of the module are shown in Figure 7a, and the module is shown in an assembled state in Figure 7b. The module has a carrier plate 300, a hydraulic block 200, a fan 210, and a refrigeration circuit assembly 220, the latter comprising the evaporator 1, the compressor 2, the condenser 3, and the expansion unit 30. The hydraulic block 200 contains the components for connecting the condenser 3 to a secondary circuit, for example, to a heating circuit of a building, and the fan 210 supports the heat transfer at the evaporator 1. Due to the compact design of the expansion unit 30 and its direct connection to the condenser 3, the refrigeration circuit assembly 220 contains only a few central components and can be designed as a coherent unit. As a result, the refrigeration circuit assembly 220 can be very easily removed from the module and reinstalled as a whole, thus facilitating maintenance and repair of the

[0082] Heat pump is significantly simplified.

Claims

PATENT CLAIMS 1. Expansion unit (30) for a refrigerant circuit, in particular for a refrigerant circuit of a heat pump, which contains a compressor (2), a condenser (3), and an evaporator (1), wherein the expansion unit (30) is designed as a functional block for fluidly connecting the compressor (2), condenser (3), and evaporator (1) and comprises the following: a first line (4a) with a first inlet (30a) for connecting to the refrigerant circuit downstream of the compressor (2) and a first outlet (30b) for connecting to the refrigerant circuit upstream of the condenser (3); a second line (4b) with a second inlet (30c) for connecting to the refrigerant circuit downstream of the condenser (3) and a second outlet (30d) for connecting to the refrigerant circuit upstream of the evaporator (1);and an expansion valve (5, 100) arranged in the second line (4b) and configured to reduce refrigerant exiting the condenser (3) from a first pressure level to a second pressure level; and a third line (4c) by means of which the first inlet (30a) of the first line (4a) can be connected to the second outlet (30d) of the second line (4b).

2. Expansion unit (30) according to claim 1, wherein a bypass valve (6) is arranged in the third line (4c), which is configured to control a refrigerant flow through the third line (4c).

3. Expansion unit (30) according to claim 1, wherein the expansion valve (5, 100) is arranged at the second outlet (30d) and is configured to control a refrigerant flow through the third line (4c).

4. Expansion unit (30) according to at least one of the preceding claims, wherein the first output (30b) and the second input (30c) are connectable to the capacitor (3).

5. Expansion unit (30) according to at least one of the preceding claims, further comprising a refrigerant collector (4) arranged between the second inlet (30c) and the expansion valve (5, 100).

6. Expansion unit (30) according to at least one of the preceding claims, wherein one or more sensors (41, 42) and / or one or more actuators (40) can be mounted in the first line (4a) and / or the third line (4c).

7. Expansion unit (30) according to at least one of the preceding claims, further comprising a housing in which the first, second and third lines (4a - 4c) are integrated.

8. Expansion unit (30) according to claim 5 to 7, wherein the refrigerant collector (4) is also integrated in the housing.

9. Heat exchanger (3-1) containing a condenser (3) and an expansion unit (30) according to at least one of the preceding claims.

10. Heat exchanger (3-1) according to claim 9, wherein the expansion unit (30) is integrated into the heat exchanger (3-1).

11. Heat exchanger (3-1) according to claim 9 or 10, wherein a third line (4c) of the expansion unit (30), by means of which a first inlet (30a) and a second outlet (30d) of the expansion unit (30) can be connected, is mounted in a heat transfer element of the heat exchanger (3-1).

12. Heat pump with a refrigerant circuit containing a compressor (2), a condenser (3), an evaporator (1) and an expansion unit (30) according to at least one of claims 1 to 8.

13. Heat pump with a refrigerant circuit containing a compressor (2), an evaporator (1) and a heat exchanger (3-1) according to at least one of claims 8 to 10.

14. A method for operating an expansion unit for a refrigerant circuit according to at least one of claims 1 to 7, the refrigerant circuit comprising a compressor (2), a condenser (3) and an evaporator (1), the method comprising the steps: - Operating the expansion unit (30) in a first operating mode in which a refrigerant is passed via a first line (4a) of the expansion unit (30) from the compressor (2) to the condenser (3) and through the condenser (3), and is fed to the evaporator (1) via an expansion valve (5, 100) in a second line (4b) of the expansion unit (30); - Determining a state variable of the evaporator (1); - Maintaining the first operating mode if the value of the state variable is within a predetermined range of values; and - Operating the expansion unit (30) in a second operating mode in which a third line (4c) of the expansion unit (30) is opened and at least part of the refrigerant is conducted from the compressor (2) to the evaporator (1) when the value of the state variable of the evaporator (1) lies outside the predetermined value range.

15. A computing unit comprising a processor configured to carry out the method according to claim 13.

16. A computer program comprising instructions which, when executed by a computer, cause the computer to carry out the method according to claim 13.

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