Heat pump and method of controlling a heat pump

Abstract

The present invention relates to a heat pump (1) having a heating mode and a cooling mode, and a corresponding method of operation, the heat pump (1) comprising a refrigerant circle (200) and a hydraulic circle (100), the refrigerant circle (200) including a refrigerant configured to circulate through the refrigerant circle (200), a compressor (12), an internal heat exchanger (10) and a directional valve (14), in particular a 4 / 2 way valve, wherein the internal heat exchanger (10) is configured to exchange heat between the refrigerant and a hydraulic liquid configured to circulate through the hydraulic circle (100), and the directional valve (14) is configured to invert a flow direction of the refrigerant in the refrigerant circle (200) to change between the heating mode and the cooling mode, further comprising a second directional valve (50) configured to invert the flow direction of the refrigerant or the hydraulic liquid over the internal heat exchanger (10), such that the refrigerant and the hydraulic liquid flow in counter current through the internal heat exchanger (10) in the heating mode and the cooling mode.

Description

Technical Field

[0001] The present invention relates to a heat pump having a heating mode and a cooling mode and a method of controlling such a heat pump.

[0002] The present invention also relates to a computer-readable storage medium storing program code, the program code comprising instructions for carrying out such a method.Background

[0003] Heat pumps are widely known. A heat pump is a system designed to move heat from one place to another for heating or cooling purposes. It operates on the principle of thermodynamics, utilizing electricity not to generate heat but to transfer it. The process begins at the evaporator, where heat is absorbed from an external source like air, ground, or water. The compressor then increases the temperature of the refrigerant, which carries the heat to the condenser, where it is released into the desired space. The cycle is completed as the refrigerant passes through the expansion valve, reducing pressure and preparing it to absorb heat again.

[0004] Heat pumps come in different types, including air-source (extracting heat from the air), ground-source (geothermal) (using the ground as a heat source), and water-source systems. They are highly energy-efficient, delivering up to three to four times the energy they consume, making them an eco-friendly choice for both heating and cooling. Additionally, many systems can also heat water, adding to their versatility. With a lower carbon footprint and compatibility with renewable energy, heat pumps are becoming a go-to solution for residential and commercial applications.

[0005] The inversion of the flow direction in a heat pump allows it to switch between heating and cooling modes, making it a versatile system for year-round climate control. This process is enabled by a reversing valve or directional valve, a key component that changes the direction of the refrigerant flow within the system.

[0006] In heating mode, the heat pump extracts heat from an external source (like air, ground, or water) and transfers it indoors. The evaporator absorbs heat from the outside environment, the compressor increases the refrigerant's temperature, and the condenser releases the heat into the interior space.

[0007] When switched to cooling mode, the flow direction is reversed. Now, the indoor unit or indoor heat exchanger functions as the evaporator, absorbing heat from the indoor air, while the outdoor unit becomes the condenser, releasing that heat outside. The refrigerant follows the reversed path, ensuring efficient heat removal to keep the indoor environment cool.

[0008] This capability makes heat pumps a practical and energy-efficient solution for both heating during colder months and cooling during warmer seasons, seamlessly adapting to changing temperature needs.

[0009] However, the reversing of the flow direction of the refrigerant is not without difficulties. In particular, the efficiency of the internal heat exchanger deteriorates as a result of the reversal of the flow direction.

[0010] Moreover, the reversing of the flow direction is not only used to change between heating and cooling operation. For instance, it is known to be used to defrost the external heat exchanger or condenser that may accumulate ice and in certain environmental conditions.

[0011] It was therefore an object of the present invention to improve a heat pump that is capable of both heating and cooling.Summary of the Invention

[0012] The objective of the present invention is to provide a heat pump having a heating mode and a cooling mode and a method of controlling a heat pump according to any of the preceding claims, which overcome one or more of the above-mentioned problems of the prior art.

[0013] A first aspect of the invention provides a heat pump having a heating mode and a cooling mode, the heat pump comprising: a refrigerant circle and a hydraulic circle, the refrigerant circle including a refrigerant configured to circulate through the refrigerant circle, a compressor, an internal heat exchanger and a directional valve, in particular a 4 / 2 way valve, wherein the internal heat exchanger is configured to exchange heat between the refrigerant and a hydraulic liquid configured to circulate through the hydraulic circle, and the directional valve is configured to invert a flow direction of the refrigerant in the refrigerant circle to change between the heating mode and the cooling mode.

[0014] The heat pump further includes a second directional valve configured to invert the flow direction of the refrigerant or the hydraulic liquid over the internal heat exchanger, such that the refrigerant and the hydraulic liquid flow in counter current through the internal heat exchanger in the heating mode and the cooling mode.

[0015] The internal heat exchanger is preferentially operated in counter-current flow to maximize energy transfer efficiency. In this setup, the two fluids (e.g., hot and cold) flow in opposite directions, creating a continuous temperature gradient along the exchanger.

[0016] This configuration ensures that the temperature difference between the fluids remains relatively high across the entire length of the heat exchanger. As a result, more heat is transferred, and the thermal exchange process is more efficient. Additionally, counter-current flow can achieve a closer approach to the desired outlet temperatures for both fluids, compared to parallel flow systems.

[0017] By maintaining an optimal temperature gradient, counter-current operation enhances performance, reduces energy waste, and is especially useful in applications requiring precise temperature control or maximum heat recovery.

[0018] By including the second directional valve, the flow through the internal heat exchanger can be counter-current flow in both heating and cooling operation of the heat pump. At the same time, the flow can be parallel flow for instance in defrost operations. In defrost mode of a heat pump, parallel flow through the internal heat exchanger is preferred to improve system performance and efficiency. During defrosting, the goal is to remove ice or frost buildup on the outdoor unit by reversing the heat pump's cycle, directing heat from the system to the outdoor coil.

[0019] In a first implementation of the heat pump according to the first aspect, the hydraulic circle includes a circulating pump circulating the hydraulic fluid between a hydraulic circle supply line and a hydraulic circle return line, wherein the second directional valve is arranged in the hydraulic circle such that the flow direction of the hydraulic fluid over the internal heat exchanger is invertible without inverting a flow direction of supply line and return line.

[0020] In a further implementation of the heat pump according to the first aspect, the second directional valve includes two 3 / 2 way valves arranged before and after the internal heat exchanger, respectively.

[0021] In a further implementation of the heat pump according to the first aspect, each of the two 3 / 2 way valves is connected to both hydraulic side inlets of the internal heat exchanger such that switching a switching position of the 3 / 2 way valves inverts the flow of the hydraulic fluid through the internal heat exchanger.

[0022] In a further implementation of the heat pump according to the first aspect, the second directional valve includes a 4 / 2 way valve connected to both hydraulic side inlets of the internal heat exchanger such that switching a switching position of the 4 / 2 way valve inverts the flow of the hydraulic fluid through the internal heat exchanger.

[0023] The 4 / 2 way valve is preferred over the 3 / 2 way valves in view of number of parts and cost. However, the 3 / 2 way valves are preferred because no heat is conducted internally within the valve between the hot and cold fluid that reduces the efficiency of the heat pump.

[0024] In a further implementation of the heat pump according to the first aspect, the second directional valve is arranged in the refrigerant circle such that the flow direction of the refrigerant over the internal heat exchanger is invertible.

[0025] In a further implementation of the heat pump according to the first aspect, the second directional valve includes a 4 / 2 way valve or two 3 / 2 way valves connected to both refrigerant side inlets of the internal heat exchanger.

[0026] In a further implementation of the heat pump according to the first aspect, the hydraulic circle further comprising at least one of: an inverter cooler configured to dissipate heat from an inverter of the heat pump, and a supplementary heater, in particular a resistance heater.

[0027] In a further implementation of the heat pump according to the first aspect, the refrigerant circle further comprising at least one of: an external heat exchanger, in particular an air-water heat exchanger including a fan, a throttling device, in particular an expansion valve, a recuperator, a hot gas injection to inject hot gas into the compressor, a defrosting coil, and a refrigerant collector.

[0028] The present invention can be combined with all implementations of different refrigerant circles known to the skilled person. The skilled person will design the refrigerant circle in conformity with the requirements of the specific application.

[0029] While the skilled person will appreciate that the present invention is particularly suitable for heat pumps using ambient air as a heat source, they will also appreciate that other forms of heat sources, such as water, are contemplated. Moreover, the invention applies to both indoor and outdoor heat pumps.

[0030] The methods according to the second aspect of the invention can be performed by the heat pump having a heating mode and a cooling mode according to the first aspect of the invention. Further features or implementations of the method according to the second aspect of the invention can perform the functionality of the heat pump having a heating mode and a cooling mode according to the first aspect of the invention and its different implementation forms.

[0031] In a further implementation of the method of the second aspect, the second directional valve is controlled to switch its operating position in accordance with at least one of: a switching position of the directional valve of the refrigerant circle, a switching position of a valve of the inverter cooling, and a heat pump manager providing an operating mode of the heat pump, the operating mode including heating and cooling.

[0032] Particularly the switching position of the valve of the inverter cooling is preferred because the inverter cooling is avoided in special operation modes, such as defrosting operation. The control of the second directional valve can thereby integrated into the control of the heat pump without difficulty.

[0033] A further aspect of the invention refers to a computer-readable storage medium storing program code, the program code comprising instructions that when executed by a processor carry out the method of the second aspect or one of the implementations of the second aspect.Brief Description of the Drawings

[0034] To illustrate the technical features of embodiments of the present invention more clearly, the accompanying drawings provided for describing the embodiments are introduced briefly in the following. The accompanying drawings in the following description are merely some embodiments of the present invention, modifications on these embodiments are possible without departing from the scope of the present invention as defined in the claims. FIG. 1is a diagram illustrating a heat pump having a heating mode and a cooling mode in the heating mode useful for understanding the present invention, FIG. 2is a diagram illustrating the heat pump of Fig. 1 in the cooling mode useful for understanding the present invention, FIG. 3Ais a diagram illustrating a heat pump in in accordance with an embodiment of the present invention, FIG. 3Bis a diagram illustrating the embodiment of Fig. 3A in the cooling mode, FIG. 4Ais a diagram illustrating a heat pump in in accordance with a further embodiment of the present invention, FIG. 4Bis a diagram illustrating the embodiment of Fig. 4A in the cooling mode, FIG. 5Ais a diagram illustrating a heat pump in in accordance with a further embodiment of the present invention, and FIG. 5Bis a diagram illustrating the embodiment of Fig. 5A in the cooling mode. DETAILED DESCRIPTION OF EMBODIMENTS

[0035] Fig. 1 illustrates a heat pump 1000 in heating mode that is useful for understanding the present invention. The heat pump 1000 includes a hydraulic circle 100 and a refrigerant circle 200.

[0036] In the hydraulic circle 100 circulates a hydraulic liquid for instance to a space heating between a feed or supply line 110 and a feed-out or return line 120 by means of a circulating pump 130. An optional supplementary heater 140 is arranged in supply line 110 that can heat the hydraulic liquid if necessary using electric energy. Moreover, an optional inverter cooler 150 for dissipating heat from an inverter of heat pump 1000 is provided, wherein a flow to inverter cooler 150 can be adjusted using a controllable valve 160.

[0037] The hydraulic liquid and the refrigerant exchange heat in an internal heat exchanger 10 that is operable as both condenser and evaporator depending on a flow direction of the refrigerant through the refrigerant cycle occurring within refrigerant circle 200.

[0038] Refrigerant circle 200 includes a compressor 12, a directional valve 14, an external heat exchanger 16 and an expansion valve 18. In the illustrated heating mode, the refrigerant circulates from external heat exchanger 16, in which heat is absorbed from the heat source, to compressor 12, which compresses the refrigerant, to internal heat exchanger 10, in which the heat is transferred to the hydraulic fluid of hydraulic circle 100. Finally, the refrigerant is relaxed by means of expansion valve 18 and the cycle is completed.

[0039] Refrigerant circle 200 further includes other elements of a heating circles that will be described in the following. It should be noted that other embodiments of heating circles can be combined with the invention, i.e., many described components are optional.

[0040] In this example, refrigerant circle 200 includes a recuperator 20 that is controllable by a valve 22 and that allows a hot gas injection 24 into compressor 12. Further, a refrigerant collector 26 and a filter dryer 28 are provided. A defrosting coil 30 is configured to defrost external heat exchanger 16 if necessary. Several further valves 32 and 34 are provided that in particular control the flow direction over some parts of hydraulic circle 100. In particular refrigerant collector 26 and filter dryer 28 are preferentially only be flowed through in one direction, i.e., should not be affected when a flow direction of the refrigerant is reversed.

[0041] In this example, heat pump 1000 is an air-to-water heat pump with a fan-driven evaporator as external heat exchanger 16, wherein also other heat sources are of course contemplated.

[0042] Fig. 2 illustrates heat pump 1000 of Fig. 1 in a cooling mode. In this example, the operating position of directional valve 14 is changed such that the flow of refrigerant through refrigerant circle 200 is reversed. It can be seen that internal heat exchanger 10 is flowed through in parallel, i.e., the direction of flow of refrigerant in refrigerant circle 200 is parallel to the direction of flow of hydraulic liquid in hydraulic circle 100.

[0043] Fig. 3A and 3B show heat pump 1 according to an embodiment of the present invention. It corresponds to heat pump 1000 illustrated in Fig. 1 and 2 except for a second directional valve 50 being provided in hydraulic circle 100. Fig. 3A illustrates the heating operation, whereas Fig. 3B illustrates the same embodiment in the cooling operation.

[0044] Second directional valve 50 in this embodiment comprises a first 3 / 2 way valve 52 and a second 3 / 2 way valve 54 being provided between internal heat exchanger 10 and controllable valve 160 or pump 130, respectively. The first and second 3 / 2 way valves 52, 54 have two operating positions. In the operating position illustrated in Fig. 3A, first 3 / 2 way valve 52 provides the hydraulic liquid to inlet 53 on the illustrated left side of internal heat exchanger 10. Correspondingly, second 3 / 2 way valve 54 is provided the hydraulic liquid from inlet 55 on the illustrated right side. The hydraulic liquid accordingly flows through internal heat exchanger 10 from left to right as illustrated.

[0045] By changing the operation position of both first and second 3 / 2 way valves 52, 54, the flow direction is reversed as illustrated in Fig. 3B. More precisely, first 3 / 2 way valve 52 now provides the hydraulic liquid to inlet 55 on the right side and second 3 / 2 way valve 54 os provided with the hydraulic liquid from inlet 53 on the left side. Accordingly, the flow direction of the hydraulic liquid is reversed and now is from right to left as illustrated.

[0046] As can be seen from Fig. 3A and 3B, the flow of the hydraulic liquid and the refrigerant is in counter current both in the heating operation, cf. Fig. 3A, and in the cooling operation, cf. Fig. 3B. Second directional valve 50 thus mirrors the reversal of the flow direction of the refrigerant by also reversing the flow direction of the hydraulic liquid through internal heat exchanger 10.

[0047] Fig. 4A and 4B show heat pump 1 according to an embodiment of the present invention. It corresponds to the embodiment of Fig. 3A and 3B except for an alternative second directional valve 50 being provided in hydraulic circle 100. Fig. 4A illustrates the heating operation, whereas Fig. 4B illustrates the same embodiment in the cooling operation.

[0048] In this embodiment, second directional valve 50 includes a single 4 / 2 way valve 60. As appreciable from a comparison of Fig. 4A and 4B, changing the operating position of 4 / 2 way valve 60 changes the flow direction of the hydraulic liquid through internal heat exchanger 10 in the same way as the embodiment of Fig. 3A and 3B.

[0049] Compared to two separate 3 / 2 way valves, a single 4 / 2 way valve is more cost efficient. Yet, the 3 / 2 way valves do not suffer from energy losses due to the direct contact of the supply line 110 and return line 120 liquid.

[0050] Fig. 5A and 5B show heat pump 1 according to a further embodiment of the present invention. It corresponds to heat pump 1000 of Fig. 1 and 2, in which second directional valve 50 is included in refrigerant circle 200 rather than hydraulic circle 100.

[0051] More specifically, an example of a 4 / 2 way valve 70 is included around internal heat exchanger 10 in refrigerant circle 200. As can be seen from the two different operating positions of 4 / 2 way valve 70 in comparison of Figs. 5A and 5B, the flow direction of refrigerant through internal heat exchanger 10 remains unchanged, even in case the flow direction of refrigerant through refrigerant circle 200 is reversed by changing the operating position of directional valve 14. Instead of one 4 / 2 way valve 70, the embodiment using two 3 / 2 way valves can be adopted accordingly.

[0052] The foregoing descriptions are only implementation manners of the present invention, the scope of the present invention is not limited to this. Any variations or replacements can be easily made through person skilled in the art. Therefore, the protection scope of the present invention should be subject to the protection scope of the attached claims.List of reference numbers

[0053] 1heat pump 10internal heat exchanger 12compressor 14directional valve 16external heat exchanger 18expansion valve 20recuperator 22, 32, 34valve 24hot gas injection 26particular refrigerant collector 26refrigerant collector 28filter dryer 30defrosting coil 50second directional valve 52, 543 / 2 way valve 53, 55inlet 60, 704 / 2 way valve 100hydraulic circle 110supply line 120return line 130circulating pump 140optional supplementary heater 150optional inverter cooler 160controllable valve 200refrigerant circle 1000heat pump

Examples

Embodiment Construction

[0035]Fig. 1 illustrates a heat pump 1000 in heating mode that is useful for understanding the present invention. The heat pump 1000 includes a hydraulic circle 100 and a refrigerant circle 200.

[0036]In the hydraulic circle 100 circulates a hydraulic liquid for instance to a space heating between a feed or supply line 110 and a feed-out or return line 120 by means of a circulating pump 130. An optional supplementary heater 140 is arranged in supply line 110 that can heat the hydraulic liquid if necessary using electric energy. Moreover, an optional inverter cooler 150 for dissipating heat from an inverter of heat pump 1000 is provided, wherein a flow to inverter cooler 150 can be adjusted using a controllable valve 160.

[0037]The hydraulic liquid and the refrigerant exchange heat in an internal heat exchanger 10 that is operable as both condenser and evaporator depending on a flow direction of the refrigerant through the refrigerant cycle occurring within refrigerant circle 200.

[0038...

Technical Field

[0001] The present invention relates to a heat pump having a heating mode and a cooling mode and a method of controlling such a heat pump.

[0002] The present invention also relates to a computer-readable storage medium storing program code, the program code comprising instructions for carrying out such a method.Background

[0003] Heat pumps are widely known. A heat pump is a system designed to move heat from one place to another for heating or cooling purposes. It operates on the principle of thermodynamics, utilizing electricity not to generate heat but to transfer it. The process begins at the evaporator, where heat is absorbed from an external source like air, ground, or water. The compressor then increases the temperature of the refrigerant, which carries the heat to the condenser, where it is released into the desired space. The cycle is completed as the refrigerant passes through the expansion valve, reducing pressure and preparing it to absorb heat again.

[0004] Heat pumps come in different types, including air-source (extracting heat from the air), ground-source (geothermal) (using the ground as a heat source), and water-source systems. They are highly energy-efficient, delivering up to three to four times the energy they consume, making them an eco-friendly choice for both heating and cooling. Additionally, many systems can also heat water, adding to their versatility. With a lower carbon footprint and compatibility with renewable energy, heat pumps are becoming a go-to solution for residential and commercial applications.

[0005] The inversion of the flow direction in a heat pump allows it to switch between heating and cooling modes, making it a versatile system for year-round climate control. This process is enabled by a reversing valve or directional valve, a key component that changes the direction of the refrigerant flow within the system.

[0006] In heating mode, the heat pump extracts heat from an external source (like air, ground, or water) and transfers it indoors. The evaporator absorbs heat from the outside environment, the compressor increases the refrigerant's temperature, and the condenser releases the heat into the interior space.

[0007] When switched to cooling mode, the flow direction is reversed. Now, the indoor unit or indoor heat exchanger functions as the evaporator, absorbing heat from the indoor air, while the outdoor unit becomes the condenser, releasing that heat outside. The refrigerant follows the reversed path, ensuring efficient heat removal to keep the indoor environment cool.

[0008] This capability makes heat pumps a practical and energy-efficient solution for both heating during colder months and cooling during warmer seasons, seamlessly adapting to changing temperature needs.

[0009] However, the reversing of the flow direction of the refrigerant is not without difficulties. In particular, the efficiency of the internal heat exchanger deteriorates as a result of the reversal of the flow direction.

[0010] Moreover, the reversing of the flow direction is not only used to change between heating and cooling operation. For instance, it is known to be used to defrost the external heat exchanger or condenser that may accumulate ice and in certain environmental conditions.

[0011] It was therefore an object of the present invention to improve a heat pump that is capable of both heating and cooling.Summary of the Invention

[0012] The objective of the present invention is to provide a heat pump having a heating mode and a cooling mode and a method of controlling a heat pump according to any of the preceding claims, which overcome one or more of the above-mentioned problems of the prior art.

[0013] A first aspect of the invention provides a heat pump having a heating mode and a cooling mode, the heat pump comprising: a refrigerant circle and a hydraulic circle, the refrigerant circle including a refrigerant configured to circulate through the refrigerant circle, a compressor, an internal heat exchanger and a directional valve, in particular a 4 / 2 way valve, wherein the internal heat exchanger is configured to exchange heat between the refrigerant and a hydraulic liquid configured to circulate through the hydraulic circle, and the directional valve is configured to invert a flow direction of the refrigerant in the refrigerant circle to change between the heating mode and the cooling mode.

[0014] The heat pump further includes a second directional valve configured to invert the flow direction of the refrigerant or the hydraulic liquid over the internal heat exchanger, such that the refrigerant and the hydraulic liquid flow in counter current through the internal heat exchanger in the heating mode and the cooling mode.

[0015] The internal heat exchanger is preferentially operated in counter-current flow to maximize energy transfer efficiency. In this setup, the two fluids (e.g., hot and cold) flow in opposite directions, creating a continuous temperature gradient along the exchanger.

[0016] This configuration ensures that the temperature difference between the fluids remains relatively high across the entire length of the heat exchanger. As a result, more heat is transferred, and the thermal exchange process is more efficient. Additionally, counter-current flow can achieve a closer approach to the desired outlet temperatures for both fluids, compared to parallel flow systems.

[0017] By maintaining an optimal temperature gradient, counter-current operation enhances performance, reduces energy waste, and is especially useful in applications requiring precise temperature control or maximum heat recovery.

[0018] By including the second directional valve, the flow through the internal heat exchanger can be counter-current flow in both heating and cooling operation of the heat pump. At the same time, the flow can be parallel flow for instance in defrost operations. In defrost mode of a heat pump, parallel flow through the internal heat exchanger is preferred to improve system performance and efficiency. During defrosting, the goal is to remove ice or frost buildup on the outdoor unit by reversing the heat pump's cycle, directing heat from the system to the outdoor coil.

[0019] In a first implementation of the heat pump according to the first aspect, the hydraulic circle includes a circulating pump circulating the hydraulic fluid between a hydraulic circle supply line and a hydraulic circle return line, wherein the second directional valve is arranged in the hydraulic circle such that the flow direction of the hydraulic fluid over the internal heat exchanger is invertible without inverting a flow direction of supply line and return line.

[0020] In a further implementation of the heat pump according to the first aspect, the second directional valve includes two 3 / 2 way valves arranged before and after the internal heat exchanger, respectively.

[0021] In a further implementation of the heat pump according to the first aspect, each of the two 3 / 2 way valves is connected to both hydraulic side inlets of the internal heat exchanger such that switching a switching position of the 3 / 2 way valves inverts the flow of the hydraulic fluid through the internal heat exchanger.

[0022] In a further implementation of the heat pump according to the first aspect, the second directional valve includes a 4 / 2 way valve connected to both hydraulic side inlets of the internal heat exchanger such that switching a switching position of the 4 / 2 way valve inverts the flow of the hydraulic fluid through the internal heat exchanger.

[0023] The 4 / 2 way valve is preferred over the 3 / 2 way valves in view of number of parts and cost. However, the 3 / 2 way valves are preferred because no heat is conducted internally within the valve between the hot and cold fluid that reduces the efficiency of the heat pump.

[0024] In a further implementation of the heat pump according to the first aspect, the second directional valve is arranged in the refrigerant circle such that the flow direction of the refrigerant over the internal heat exchanger is invertible.

[0025] In a further implementation of the heat pump according to the first aspect, the second directional valve includes a 4 / 2 way valve or two 3 / 2 way valves connected to both refrigerant side inlets of the internal heat exchanger.

[0026] In a further implementation of the heat pump according to the first aspect, the hydraulic circle further comprising at least one of: an inverter cooler configured to dissipate heat from an inverter of the heat pump, and a supplementary heater, in particular a resistance heater.

[0027] In a further implementation of the heat pump according to the first aspect, the refrigerant circle further comprising at least one of: an external heat exchanger, in particular an air-water heat exchanger including a fan, a throttling device, in particular an expansion valve, a recuperator, a hot gas injection to inject hot gas into the compressor, a defrosting coil, and a refrigerant collector.

[0028] The present invention can be combined with all implementations of different refrigerant circles known to the skilled person. The skilled person will design the refrigerant circle in conformity with the requirements of the specific application.

[0029] While the skilled person will appreciate that the present invention is particularly suitable for heat pumps using ambient air as a heat source, they will also appreciate that other forms of heat sources, such as water, are contemplated. Moreover, the invention applies to both indoor and outdoor heat pumps.

[0030] The methods according to the second aspect of the invention can be performed by the heat pump having a heating mode and a cooling mode according to the first aspect of the invention. Further features or implementations of the method according to the second aspect of the invention can perform the functionality of the heat pump having a heating mode and a cooling mode according to the first aspect of the invention and its different implementation forms.

[0031] In a further implementation of the method of the second aspect, the second directional valve is controlled to switch its operating position in accordance with at least one of: a switching position of the directional valve of the refrigerant circle, a switching position of a valve of the inverter cooling, and a heat pump manager providing an operating mode of the heat pump, the operating mode including heating and cooling.

[0032] Particularly the switching position of the valve of the inverter cooling is preferred because the inverter cooling is avoided in special operation modes, such as defrosting operation. The control of the second directional valve can thereby integrated into the control of the heat pump without difficulty.

[0033] A further aspect of the invention refers to a computer-readable storage medium storing program code, the program code comprising instructions that when executed by a processor carry out the method of the second aspect or one of the implementations of the second aspect.Brief Description of the Drawings

[0034] To illustrate the technical features of embodiments of the present invention more clearly, the accompanying drawings provided for describing the embodiments are introduced briefly in the following. The accompanying drawings in the following description are merely some embodiments of the present invention, modifications on these embodiments are possible without departing from the scope of the present invention as defined in the claims. FIG. 1is a diagram illustrating a heat pump having a heating mode and a cooling mode in the heating mode useful for understanding the present invention, FIG. 2is a diagram illustrating the heat pump of Fig. 1 in the cooling mode useful for understanding the present invention, FIG. 3Ais a diagram illustrating a heat pump in in accordance with an embodiment of the present invention, FIG. 3Bis a diagram illustrating the embodiment of Fig. 3A in the cooling mode, FIG. 4Ais a diagram illustrating a heat pump in in accordance with a further embodiment of the present invention, FIG. 4Bis a diagram illustrating the embodiment of Fig. 4A in the cooling mode, FIG. 5Ais a diagram illustrating a heat pump in in accordance with a further embodiment of the present invention, and FIG. 5Bis a diagram illustrating the embodiment of Fig. 5A in the cooling mode. DETAILED DESCRIPTION OF EMBODIMENTS

[0035] Fig. 1 illustrates a heat pump 1000 in heating mode that is useful for understanding the present invention. The heat pump 1000 includes a hydraulic circle 100 and a refrigerant circle 200.

[0036] In the hydraulic circle 100 circulates a hydraulic liquid for instance to a space heating between a feed or supply line 110 and a feed-out or return line 120 by means of a circulating pump 130. An optional supplementary heater 140 is arranged in supply line 110 that can heat the hydraulic liquid if necessary using electric energy. Moreover, an optional inverter cooler 150 for dissipating heat from an inverter of heat pump 1000 is provided, wherein a flow to inverter cooler 150 can be adjusted using a controllable valve 160.

[0037] The hydraulic liquid and the refrigerant exchange heat in an internal heat exchanger 10 that is operable as both condenser and evaporator depending on a flow direction of the refrigerant through the refrigerant cycle occurring within refrigerant circle 200.

[0038] Refrigerant circle 200 includes a compressor 12, a directional valve 14, an external heat exchanger 16 and an expansion valve 18. In the illustrated heating mode, the refrigerant circulates from external heat exchanger 16, in which heat is absorbed from the heat source, to compressor 12, which compresses the refrigerant, to internal heat exchanger 10, in which the heat is transferred to the hydraulic fluid of hydraulic circle 100. Finally, the refrigerant is relaxed by means of expansion valve 18 and the cycle is completed.

[0039] Refrigerant circle 200 further includes other elements of a heating circles that will be described in the following. It should be noted that other embodiments of heating circles can be combined with the invention, i.e., many described components are optional.

[0040] In this example, refrigerant circle 200 includes a recuperator 20 that is controllable by a valve 22 and that allows a hot gas injection 24 into compressor 12. Further, a refrigerant collector 26 and a filter dryer 28 are provided. A defrosting coil 30 is configured to defrost external heat exchanger 16 if necessary. Several further valves 32 and 34 are provided that in particular control the flow direction over some parts of hydraulic circle 100. In particular refrigerant collector 26 and filter dryer 28 are preferentially only be flowed through in one direction, i.e., should not be affected when a flow direction of the refrigerant is reversed.

[0041] In this example, heat pump 1000 is an air-to-water heat pump with a fan-driven evaporator as external heat exchanger 16, wherein also other heat sources are of course contemplated.

[0042] Fig. 2 illustrates heat pump 1000 of Fig. 1 in a cooling mode. In this example, the operating position of directional valve 14 is changed such that the flow of refrigerant through refrigerant circle 200 is reversed. It can be seen that internal heat exchanger 10 is flowed through in parallel, i.e., the direction of flow of refrigerant in refrigerant circle 200 is parallel to the direction of flow of hydraulic liquid in hydraulic circle 100.

[0043] Fig. 3A and 3B show heat pump 1 according to an embodiment of the present invention. It corresponds to heat pump 1000 illustrated in Fig. 1 and 2 except for a second directional valve 50 being provided in hydraulic circle 100. Fig. 3A illustrates the heating operation, whereas Fig. 3B illustrates the same embodiment in the cooling operation.

[0044] Second directional valve 50 in this embodiment comprises a first 3 / 2 way valve 52 and a second 3 / 2 way valve 54 being provided between internal heat exchanger 10 and controllable valve 160 or pump 130, respectively. The first and second 3 / 2 way valves 52, 54 have two operating positions. In the operating position illustrated in Fig. 3A, first 3 / 2 way valve 52 provides the hydraulic liquid to inlet 53 on the illustrated left side of internal heat exchanger 10. Correspondingly, second 3 / 2 way valve 54 is provided the hydraulic liquid from inlet 55 on the illustrated right side. The hydraulic liquid accordingly flows through internal heat exchanger 10 from left to right as illustrated.

[0045] By changing the operation position of both first and second 3 / 2 way valves 52, 54, the flow direction is reversed as illustrated in Fig. 3B. More precisely, first 3 / 2 way valve 52 now provides the hydraulic liquid to inlet 55 on the right side and second 3 / 2 way valve 54 os provided with the hydraulic liquid from inlet 53 on the left side. Accordingly, the flow direction of the hydraulic liquid is reversed and now is from right to left as illustrated.

[0046] As can be seen from Fig. 3A and 3B, the flow of the hydraulic liquid and the refrigerant is in counter current both in the heating operation, cf. Fig. 3A, and in the cooling operation, cf. Fig. 3B. Second directional valve 50 thus mirrors the reversal of the flow direction of the refrigerant by also reversing the flow direction of the hydraulic liquid through internal heat exchanger 10.

[0047] Fig. 4A and 4B show heat pump 1 according to an embodiment of the present invention. It corresponds to the embodiment of Fig. 3A and 3B except for an alternative second directional valve 50 being provided in hydraulic circle 100. Fig. 4A illustrates the heating operation, whereas Fig. 4B illustrates the same embodiment in the cooling operation.

[0048] In this embodiment, second directional valve 50 includes a single 4 / 2 way valve 60. As appreciable from a comparison of Fig. 4A and 4B, changing the operating position of 4 / 2 way valve 60 changes the flow direction of the hydraulic liquid through internal heat exchanger 10 in the same way as the embodiment of Fig. 3A and 3B.

[0049] Compared to two separate 3 / 2 way valves, a single 4 / 2 way valve is more cost efficient. Yet, the 3 / 2 way valves do not suffer from energy losses due to the direct contact of the supply line 110 and return line 120 liquid.

[0050] Fig. 5A and 5B show heat pump 1 according to a further embodiment of the present invention. It corresponds to heat pump 1000 of Fig. 1 and 2, in which second directional valve 50 is included in refrigerant circle 200 rather than hydraulic circle 100.

[0051] More specifically, an example of a 4 / 2 way valve 70 is included around internal heat exchanger 10 in refrigerant circle 200. As can be seen from the two different operating positions of 4 / 2 way valve 70 in comparison of Figs. 5A and 5B, the flow direction of refrigerant through internal heat exchanger 10 remains unchanged, even in case the flow direction of refrigerant through refrigerant circle 200 is reversed by changing the operating position of directional valve 14. Instead of one 4 / 2 way valve 70, the embodiment using two 3 / 2 way valves can be adopted accordingly.

[0052] The foregoing descriptions are only implementation manners of the present invention, the scope of the present invention is not limited to this. Any variations or replacements can be easily made through person skilled in the art. Therefore, the protection scope of the present invention should be subject to the protection scope of the attached claims.List of reference numbers

[0053] 1heat pump 10internal heat exchanger 12compressor 14directional valve 16external heat exchanger 18expansion valve 20recuperator 22, 32, 34valve 24hot gas injection 26particular refrigerant collector 26refrigerant collector 28filter dryer 30defrosting coil 50second directional valve 52, 543 / 2 way valve 53, 55inlet 60, 704 / 2 way valve 100hydraulic circle 110supply line 120return line 130circulating pump 140optional supplementary heater 150optional inverter cooler 160controllable valve 200refrigerant circle 1000heat pump

Examples

Embodiment Construction

[0035]Fig. 1 illustrates a heat pump 1000 in heating mode that is useful for understanding the present invention. The heat pump 1000 includes a hydraulic circle 100 and a refrigerant circle 200.

[0036]In the hydraulic circle 100 circulates a hydraulic liquid for instance to a space heating between a feed or supply line 110 and a feed-out or return line 120 by means of a circulating pump 130. An optional supplementary heater 140 is arranged in supply line 110 that can heat the hydraulic liquid if necessary using electric energy. Moreover, an optional inverter cooler 150 for dissipating heat from an inverter of heat pump 1000 is provided, wherein a flow to inverter cooler 150 can be adjusted using a controllable valve 160.

[0037]The hydraulic liquid and the refrigerant exchange heat in an internal heat exchanger 10 that is operable as both condenser and evaporator depending on a flow direction of the refrigerant through the refrigerant cycle occurring within refrigerant circle 200.

[0038...

Claims

1. A heat pump (1) having a heating mode and a cooling mode, the heat pump (1) comprising: a refrigerant circle (200) and a hydraulic circle (100), the refrigerant circle (200) including a refrigerant configured to circulate through the refrigerant circle (200), a compressor (12), an internal heat exchanger (10) and a directional valve (14), in particular a 4 / 2 way valve, wherein the internal heat exchanger (10) is configured to exchange heat between the refrigerant and a hydraulic liquid configured to circulate through the hydraulic circle (100), and the directional valve (14) is configured to invert a flow direction of the refrigerant in the refrigerant circle (200) to change between the heating mode and the cooling mode, characterized in that the heat pump (1) further comprises a second directional valve (50) configured to invert the flow direction of the refrigerant or the hydraulic liquid over the internal heat exchanger (10), such that the refrigerant and the hydraulic liquid flow in counter current through the internal heat exchanger (10) in the heating mode and the cooling mode.

2. The heat pump (1) according to claim 1, the hydraulic circle (100) including a circulating pump (130) circulating the hydraulic fluid between a hydraulic circle supply line (110) and a hydraulic circle return line (120), wherein the second directional valve (50) is arranged in the hydraulic circle (100) such that the flow direction of the hydraulic fluid over the internal heat exchanger (10) is invertible without inverting a flow direction of supply line (110) and return line (120).

3. The heat pump (1) according to claim 2, wherein the second directional valve (50) includes two 3 / 2 way valves (52, 54) arranged before and after the internal heat exchanger (10), respectively.

4. The heat pump (1) according to claim 3, wherein each of the two 3 / 2 way valves (52, 54) is connected to both hydraulic side inlets (53, 55) of the internal heat exchanger (10) such that switching a switching position of the 3 / 2 way valves (52, 54) inverts the flow of the hydraulic fluid through the internal heat exchanger (10).

5. The heat pump (1) according to claim 2, wherein the second directional valve (50) includes a 4 / 2 way valve (60) connected to both hydraulic side inlets (53, 55) of the internal heat exchanger (10) such that switching a switching position of the 4 / 2 way valve (60) inverts the flow of the hydraulic fluid through the internal heat exchanger (10).

6. The heat pump (1) according to claim 1, wherein the second directional valve (50) is arranged in the refrigerant circle (200) such that the flow direction of the refrigerant over the internal heat exchanger (10) is invertible.

7. The heat pump (1) according to claim 6, wherein the second directional valve (50) includes a 4 / 2 way valve (70) or two 3 / 2 way valves connected to both refrigerant side inlets of the internal heat exchanger (10).

8. The heat pump (1) according to any of the preceding claims, the hydraulic circle (100) further comprising at least one of: - an inverter cooler (150) configured to dissipate heat from an inverter of the heat pump (1), and - a supplementary heater (140), in particular a resistance heater.

9. The heat pump (1) according to any of the preceding claims, the refrigerant circle (200) further comprising at least one of: - an external heat exchanger (16), in particular an air-water heat exchanger including a fan, - a throttling device, in particular an expansion valve (18), - a recuperator (20), - a hot gas injection (24) to inject hot gas into the compressor (12), - a defrosting coil (30), and - a refrigerant collector (26).

10. A method of controlling a heat pump (1) according to any of the preceding claims, wherein the second directional valve (50) is controlled to switch its operating position in accordance with at least one of: - a switching position of the directional valve (14) of the refrigerant circle (200), - a switching position of a valve (160) of the inverter cooler (150), and - a heat pump manager providing an operating mode of the heat pump (1), the operating mode including heating and cooling.

Images