Heat pump for building heating and building heating

Abstract

The invention relates to a heat pump (10; 10a) for a building heating system (100), comprising a heat pump housing (12) in which a fan (16) is arranged for at least indirectly cooling heat-generating components (28, 29) of an inverter (25; 25a), wherein the inverter (25; 25a) is arranged within an inverter housing (22), wherein the inverter (25; 25a) is at least indirectly connected to a housing wall (26; 26a) which is made at least partially of metal and which can be subjected to an air flow generated by the fan (16).

Description

Technical FieldThe invention relates to a heat pump for a building heating system, which is distinguished in particular by a relatively low noise emission with a compact construction. The invention further relates to a building heater with a heat pump designed according to the invention.Prior ArtHeat pumps as a component of modern building heaters are known from the prior art. These comprise a heat pump, which is usually arranged in an outer region of the building and has a heat pump housing in which a fan is arranged, which serves for evaporating refrigerant by means of the ambient air. The vaporized refrigerant then reaches the region of a compressor, where it is liquefied with pressure increase and is fed to a heat exchanger in order to heat the interior of the building.It is known here to use an inverter for controlling the compressor with speed regulation, which inverter first converts an alternating current of the power grid into a direct current and then back into alternating current. The inverter is arranged in the region of the heat pump housing within an inverter housing and has cooling ribs around which the air flow that can be generated by the fan under consideration flows, so that heat-generating components of the inverter arranged in thermal contact with the cooling ribs can be cooled. Such cooling ribs arranged in the air flow of the fan represent a not inconsiderable source for the noise emissions, which are relevant with regard to possible locations of the heat pump or of the heat pump housing.Disclosure of the InventionThe heat pump according to the invention for a building heater having the features of claim 1 has the advantage of a particularly low noise emission or reduced noise emission compared to the prior art, with a simultaneously particularly compact structure.The invention is based on the concept of introducing at least some of the heat generated by the heat-generating components on account of power losses via a housing wall arranged in thermal contact with the air flow of the fan and discharging it via air flow (air cooling). This achieves the advantage that the size or quantity of the cooling ribs is at least reduced compared to the prior art, and in the best case even cooling ribs or similar structures can be completely dispensed with if the thermal energy can be emitted completely via the housing wall of the inverter housing.Against the background of the above explanations, a heat pump according to the invention for a building heater having the features of claim 1 therefore has a heat pump housing in which a fan for at least indirectly cooling heat-generating components of an inverter is arranged. Furthermore, the inverter is arranged within an inverter housing, wherein the inverter is connected at least indirectly to a housing wall which is made at least in regions of metal. The housing wall can be exposed to an air flow that can be generated by the fan, wherein it is essential to the invention that at least a part of the heat-generating components is thermally connected at least indirectly by means of at least one heat-conducting element to the region of the housing wall that consists of metal.Advantageous refinements of the heat pump according to the invention for a building heater are listed in the dependent claims.A particularly simple thermal connection of the heat-generating components to the housing wall of the inverter housing is achieved in that the at least one heat-conducting element is designed as a heat-conducting adhesive.Such a heat-conducting adhesive additionally has the advantage that tolerances (gaps) between the heat-generating component or components and the housing wall, which tolerances may be part of the component or assembly, can be compensated for very easily by the heat-conducting adhesive.Additionally or alternatively, it can be provided that the at least one heat conducting element is designed as a heat transfer element made of metal and arranged in at least indirect contact with at least one heat generating component. Such a heat transfer element, which is designed, for example, as a cast part consisting of aluminum, has the advantage that it can also bridge relatively large distances (gaps) between the housing wall and the component and is therefore more flexible with regard to the layout (printed circuit board with heat-generating components). In addition, a heat conducting element of this type, which in turn can be connected to the housing wall by means of heat conducting adhesives, enables the introduction of heat into the housing wall over a large surface area if it has a geometry (spread) adapted for this purpose.To optimize the geometry of the heat pump housing and to improve the cooling effect of the housing wall of the inverter housing, it is advantageous if the housing wall is arranged at an oblique angle to the air flow that can be generated by the fan. As a result, the air flow impinges on the housing wall at an angle between 20° and 60°, for example, which enables a particularly intensive heat exchange between the housing wall and the air flow.It can also be provided that the inverter has cooling ribs for cooling the heat-generating components, and that the cooling ribs pass through an opening of the housing wall and can be supplied with the air flow that can be generated by the fan. Such cooling ribs are always used when a sufficiently good or high heat transfer to the air flow is not made possible solely via the housing wall, despite the housing wall of the inverter housing possibly arranged obliquely to the air flow. In contrast to the prior art, in which the heat dissipation takes place exclusively via the cooling ribs, however, the size of the cooling surface or the number of cooling ribs can be reduced compared to the prior art, since at least some of the heat generated by the heat-generating components is dissipated to the housing wall via the heat path.In a preferred structural arrangement of the inverter housing, it is provided that the housing wall is arranged on the suction side of the fan.With a view to as good as possible a fabrication as well as a high corrosion protection and a low weight, it is furthermore preferred that at least the housing wall consists of aluminum.As already explained at the outset, it is provided in particular that the inverter serves to actuate a compressor for compressing refrigerant.Furthermore, the invention also comprises a housing heater with a heat pump designed according to the invention as described so far.Further advantages, features and details of the invention are evident from the following description of preferred embodiments of the invention and on the basis of the drawings.Brief Description of the DrawingsFIG. 1 shows a simplified longitudinal section of a first heat pump of a building heater in the region of a heat pump housing, FIG. 2 shows a perspective illustration of a heat transfer element designed as a die casting as a constituent part of the heat pump according to FIG. 1, and FIG. 3 is a partial longitudinal section of a heat pump modified from FIG. 1.Embodiments of the InventionIdentical elements or elements with the same function are provided with the same reference numbers in the figures.FIG. 1 shows a detail and greatly simplified of a heat pump 10 of a building heating device 100. The heat pump 10 has a heat pump housing 12, which is typically of cuboidal design and is located in an outer region of the housing in order to evaporate a refrigerant conveyed through the heat pump housing 12 inside pipe elements 14 by ambient air and to feed it to a heat exchanger, not illustrated.To support the evaporation, a fan 16 with a fan wheel 18 of axial construction is arranged inside the heat pump housing 12. The tube elements 14 are located in the region of an end face 19 of the heat pump housing 12 and inside the heat pump housing 12 on the suction side of the fan wheel 18. an air flow is generated during operation by means of the fan 16 or the fan wheel 18, the air flow of which is intended to be illustrated by the flow arrows 20.In the region between the tube elements 14 and the fan impeller 18, an inverter housing 22 is arranged as a component of an inverter 25 in the illustration of FIG. 1 in an upper region of the heat pump housing 12. The inverter 25, which converts alternating current into direct current and then again into alternating current, serves to operate a compressor, not shown, for compressing the refrigerant evaporated in the heat pump case 12.The inverter housing 22 can consist of plastic or of aluminum to save weight and is preferably designed in the shape of a trough. In order to prevent dirt, dust, etc. from entering the inverter case 22, the air flow side of the inverter case 22 is formed closed. In the exemplary embodiment shown, this is effected by means of a housing wall 26 which is made of metal, in particular of aluminum, at least in the region of the inverter housing 22.The housing wall 26, which is arranged at an oblique angle α, which is typically between 10° and 60° with respect to the horizontal plane 27 or the air flow, is exposed to the air flow of the fan impeller 18 and serves for the at least indirect cooling of heat-generating components 28, 29 of the inverter 25 arranged within the inverter housing 22. The printed circuit board 30 or the components 28, 29 are thermally coupled to the housing wall 26 via at least one heat-conducting element 32. In the exemplary embodiment shown, the heat-conducting element 32 is designed in the form of a heat transfer element 35 shown in FIG. 3.The heat transfer element 35 has a rib structure with domes 36 or elevated regions which are designed to be contacted in thermally conductive contact with the heat-generating components 28, 29, in the exemplary embodiment shown, with the underside 38 of the printed circuit board 30 facing away from the thermally conductive components 28, 29. Furthermore, the heat transfer element 35 is additionally thermally coupled to the housing wall 26 via a thermally conductive adhesive 40, which forms a further thermally conductive element 32.The size or the volume of the housing wall 26 and the angle α should be designed in a manner specific to the application, in such a way that thermal overloading of the inverter 25 is prevented by the heat-generating components 28, 29 during operation of the inverter 35. In particular, it is provided that with a lower power loss or a lower heat radiation via the housing wall 26, the angle α tends to be lower in order to reduce the flow resistance for the air flow within the heat pump housing 12. Thus, it can also be provided in particular that, in the case of relatively small amounts of heat to be dissipated, the angle α can also be 0°, i.e. that the housing wall 26 lies in the horizontal plane 27.FIG. 2 shows a partial region of a heat pump 10 amodified with respect to FIGS. 1 and 3. The heat pump 10 ais essentially characterized in that the housing wall 26 ahas an in particular rectangular cutout or aperture 42 through which cooling ribs 44 of a cooling body 45 of the inverter 25 aprotrude. The cooling ribs 44 are only used when relatively high power losses or amounts of heat have to be dissipated, i.e. such amounts of heat that cannot be released to the environment solely via the housing wall 26. However, it is also provided in this case that the cooling body 45 acting as heat transfer element 35 ain the exemplary embodiment is additionally thermally connected to the housing wall 26 afor heat dissipation to the environment via a heat conducting element 32 in the form of the heat conducting adhesive 40. For this purpose, the cooling body 45 protrudes beyond the aperture 42.In a modification of the exemplary embodiment shown in FIG. 2, it can of course also be provided that the housing wall 26 acan be arranged analogously to the housing wall 26 for improving the heat transfer by an angle α with respect to the horizontal plane 27.The heat pump 10, 10a described thus far can be modified or modified in various ways without departing from the inventive idea. For example, it is not absolutely necessary to use a heat transfer element 35, 35 a. Depending on the arrangement of the printed circuit board 30 or the heat-generating components 28, 29, it is also conceivable to thermally couple the printed circuit board 30 or the components 28, 29 to the housing wall 26, 26 aonly with the interposition of a preferably electrically non-conductive heat-conducting adhesive.

Claims

Heat pump (10; 10a) for a building heater (100), having a heat pump housing (12) in which a fan (16) for at least indirectly cooling heat-generating components (28, 29) of an inverter (25; 25a) is arranged, wherein the inverter (25; 25a) is arranged within an inverter housing (22), wherein the inverter (25; 25a) is at least indirectly connected to a housing wall (26; 26a) which is made at least in regions of metal and on which an air stream which can be generated by the fan (16) can flow, and wherein at least some of the heat-generating components (28, 29) is at least indirectly thermally connected to the region of the housing wall (26; 26a) which is made of metal by means of at least one heat-conducting element (32).Heat pump according to Claim 1, characterized in that the at least one heat-conducting element (32) is designed as a heat-conducting adhesive (40).Heat pump according to Claim 1 or 2, characterized in that the at least one heat-conducting element (32) is designed as a heat-transfer element (35; 35a) which consists of metal and is arranged in at least indirect bearing contact with at least one heat-generating component (28, 29).Heat pump according to one of Claims 1 to 3, characterized in that the housing wall (26) is arranged at an oblique angle (α) to the air stream which can be generated by the fan (16).Heat pump according to one of Claims 1 to 4, characterized in that the inverter (25a) or a cooling body (45) thermally coupled to the inverter (25a) has cooling ribs (44) for cooling the heat-generating components (28, 29), and in that the cooling ribs (44) pass through an opening (42) in the housing wall (26a) and can be acted upon by the air stream.Heat pump according to one of Claims 1 to 5, characterized in that the housing wall (26; 26a) is arranged on the suction side of the fan (16).Heat pump according to one of Claims 1 to 6, characterized in that at least the housing wall (26; 26a) consists of aluminium.Heat pump according to claim 7, characterised in that the inverter housing (22) consists of aluminium.Heat pump according to one of Claims 1 to 8, characterized in that the inverter (25; 25a) serves to actuate a compressor for compressing refrigerant.Building heater (100) having a heat pump (10; 10a) which is designed according to one of Claims 1 to 9.

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