Component with a heat source and a cooling device

Abstract

Component (1, 1', 1'', 1'''') with a heat source (2), wherein the component has one or more functional materials (3, 307) and one or more thermally conductive materials, wherein the functional material(s) form(s) a functional structure and wherein the thermally conductive material(s) form(s) heat conduction paths (4a, 4b, 4c, 4d, 4e, 4f, 303, 304, 404, 405) of a cooling structure or thermally conductive structure for the removal of heat by means of heat transport by conduction, wherein in a first region of the component, which extends from the heat source or a heat distribution body surrounding it to a cooling device, in particular a heat exchange surface and a cooling fluid, at a first distance from the heat source, along the heat conduction path or several parallel heat conduction paths (4a, 4b, 4c, 4d, 4e, 4f, 303, 304, 404,405) by designing the material selection and the cross-sections of the heat-conducting materials depending on the distance from the heat source (2) a thermal conductivity that decreases with distance from the heat source is available for each individual heat conduction path and / or total thermal conductivity, wherein the heat source is surrounded by a heat distribution body (6, 300) in the form of a ring made of a thermal conducting material and the total thermal conductivity is the sum of the thermal conductivities of all heat conduction paths at the respective distance from the heat source or the heat distribution body (6, 300), and wherein several heat conducting bodies (4a, 4b, 4c, 4d, 4e, 4f, 303, 304, 404, 405) made of a thermal conducting material, which form heat conduction paths, extend from the outer circumferential surface of the ring,in cross-section, their longitudinal axes extend radially from the heat source and are designed with a cross-section that tapers radially outwards, at least in sections, and are embedded in a functional material.

Description

The invention is in the field of mechanical engineering and electrical engineering and can be used with particular advantage in the design of the cooling of electrical machines. However, an application can also be used generally in the design of arrangements which have a heat source, the heat of which has to be dissipated. Since the invention is concerned with providing effective heat transport paths, application in both heating and cooling systems is conceivable.In the prior art, it is known to design structures for heating or cooling components by means of materials which have a good thermal conductivity value. This applies, for example, to the housings of electric motors or also cast components for internal combustion engines, the shape of which is often optimized for the dissipation of heat. The prior art includes, for example, the publications DE 10 2017 200 899 A1, US 2002 / 0 121 365 A1 or also DE 10 2009 014 486 A1.In electronic cooling systems, copper bodies are often used as cooling elements, and care is taken to ensure that heat conducting paths for conducting the heat from the heat source to the cooling body or to a fluid cooling device are dimensioned to a sufficient extent.It is often necessary to use materials for the production of specific mechanical or electrical functional structures whose heat conducting properties are not sufficient for effective cooling. In such cases, composite structures made of a plurality of different materials are often used, of which one or more materials predominantly serve for heat conduction, while one or more other materials serve for the construction of a functional structure of an electrical or mechanical or electromechanical or other type.Such combination structures can be produced, for example, by casting methods in which different materials are joined to one another. A force-fit connection of different materials by thermal shrinkage is also known in this connection.In principle, however, such constructions have the problem that the space which is required for the construction of functional structures is not available for the heat conduction and, on the other hand, the space which is used for the construction of heat conduction structures is not usable for the functional structures.Against the background of the prior art, the object of the present invention is to create a component with a heat source and a cooling device, in which functional materials and heat-conducting materials are combined in an optimized form for an effective dissipation of heat.The object is achieved with the features of the invention by a component according to claim 1. The dependent claims present possible embodiments of the invention.The invention accordingly relates to a component having a heat source, wherein the component has one or more functional materials (3, 307) and one or more heat-conducting materials, wherein the functional material(s) forms / form a functional structure and wherein the heat-conducting material(s) forms / form heat-conducting paths of a cooling structure or heat-conducting structure for removing heat by means of the heat transport by heat conduction, wherein in a first region of the component, which extends from the heat source or a heat distribution body surrounding the latter, up to a first distance from the heat source, Along the heat conducting path or a plurality of parallel heat conducting paths, by the configuration of the material selection and the cross sections of the heat conducting materials as a function of the distance from the heat source, a constant heat conducting value or a heat conducting value decreasing with the distance from the heat source is available for each individual heat conducting path and / or total heat conducting value, wherein the total heat conducting value is obtained as the sum of the heat conducting values of all heat conducting paths at the respective distance from the heat source or the heat distributing body.The functional structures are understood to mean designs which fulfil a technical purpose which differs from the purpose of dissipating heat. Such functional structures can thus be mechanical supporting structures or, for example, material structures for conducting electrical current or for the conductive connection of various components or structures for conducting fluids. Other types of purposes followed by such functional structures are also conceivable. For these purposes, functional materials are used which have suitable material properties for following the respective purpose. The materials used for the functional structures are not referred to below as heat-conducting materials in order to distinguish them from the heat-conducting materials defined in connection with this invention. Of course, functional materials can also have heat-conducting properties, but it becomes clear in the analysis of a structure which of the materials are used as heat-conducting materials and which of the materials are used as functional materials.The heat conductivity value of a heat conduction path can be understood within the scope of the present description to mean the amount of heat / thermal energy which, in the case of a present temperature gradient per unit time, is transported through the total cross section of a heat conduction path, measured, for example, in watts / kelvin×meter.The thermal conductivity of a material is referred to more precisely as "specific thermal conductivity" and means the amount of heat energy transported per unit of time, per temperature gradient and per cm 2 material cross section. The thermal conductance of a thermal conduction path can thus be effected either by increasing the material cross section or by increasing the specific thermal conductance of the material.The present invention entails that, in a specific implementation, the group of functional materials and the group of heat-conducting materials are respectively disjunct. If a material is therefore used as the functional material, it is not considered as a heat-conducting material in the context of this invention. If a material were to be used simultaneously as a functional material and as a heat conducting material, the considerations underlying this invention would not be necessary to fulfil the purpose. If, for example, in the context of an electronic structure silver is used for conducting currents and copper is used for dissipating heat, the silver, despite its excellent heat-conducting properties, is considered in this context as a functional material and not as a heat-conducting material. Often, the material price decides for the distribution of the task which is fulfilled by the different materials used, so that in the stated example for the heat conduction the less expensive material copper is used and not the more expensive silver. For defining which of the materials used are functional materials and which are to be considered heat conducting materials, it is thus initially to be established in a given component which is the technical function of the component with the exception of heat conduction and which materials are used as functional materials for satisfying this aim. The remaining materials can then be understood as heat conducting materials. Usually, the material which takes over the majority of the heat transport in total away from the heat source will be understood as a heat-conducting material.The invention is based on the consideration that the path over which the heat is dissipated from the heat source is designed such that blockages are formed in heat-conducting paths by regions which have a low heat conductivity value, and thus a heat insulation is created which obstructs the transmission of the heat. Such heat conduction blockers must not be disposed in the vicinity of the heat source, because this would lead to heating and temperature increases in the stated range, which are undesirable. Therefore, care must be taken to ensure that the total heat conductance over the distance from the heat source is designed such that the heat can first be removed well in the immediate vicinity of the heat source. There, the space available for heat-conducting structures / a cooling structure is usually the smallest. In this region, care must be taken to ensure that sufficient thermal conductances of the thermal conduction paths are available. With increasing distance from the heat source, the cross section of the heat conducting material can then remain the same or be reduced in total.With radial distance from the heat source, the total space available for the functional structures and heat-conducting structures / cooling structure increases, but an increase in the heat-conducting values by using more space on the cooling structure would not bring about any substantial improvement in the cooling function. On the other hand, heat conducting materials are often particularly heavy, i.e. they have a high density / weight. Such materials are to be saved in many components and used only to the necessary extent in order to save overall weight for the component. Therefore, the invention has the advantage that the heat-conducting material used is distributed in the component in the most efficient manner possible, in order on the one hand to achieve the purpose of heat dissipation from the heat source and on the other hand to use only the necessary minimum of heat-conducting material in the component.According to the invention, it is provided that a cooling device, in particular a heat exchange surface and a cooling fluid, are arranged at the first distance from the heat source. The heat conducting paths of the cooling structure can thus lead directly from the heat source to the heat exchange surface and can conduct the heat that arises away to the heat exchange surface. The heat exchange surface is then surrounded by a cooling fluid, for example cooling water or another cooling fluid. The condition that the total heat conductance of the heat conducting paths between the heat source or a heat distributing body on the one hand and a heat exchange surface on the other hand remains the same or decreases leads to a minimal use of heat conducting material and also to a minimization of the space consumption by heat conducting material in the component in the case of an optimized cooling structure.For example, the component can be provided with a spherical, cubic, cuboidal or cylindrical heat source, in particular an electric motor, an internal combustion engine, a transformer or a generator, wherein a plurality of separate heat-conducting paths consisting of a heat-conducting material extend radially away from the heat source. In an internal combustion engine, the cast component, for example, in which the pistons move, or the immediate vicinity of the steel sleeves used for guiding the pistons, can be considered as a heat source, since the combustion energy is converted into motion there and the pistons rub against the walls of the cylinders. In an electric motor or a generator, the stator surrounding a rotor can be understood as a heat source. In a transformer, the windings are usually understood as a heat source.It can further advantageously be provided that one or more or all functional materials have a lower specific weight than the heat-conducting materials used. Overall, the total weight of the component can then be reduced by using the heat-conducting materials as efficiently as possible. The higher the proportion of rather heavier heat-conducting materials in the component, the more the overall weight increases.It can also be provided and will in many cases be such that the heat-conducting materials have a higher specific heat conductivity than the functional materials. In this case, it can be the result that each of the heat-conducting materials has a higher specific heat conductivity value than each individual one of the functional materials.It can also be provided within the scope of the invention that one or more or all functional materials used have a higher mechanical strength, in particular a higher breaking strength and / or a greater stiffness, than the heat-conducting materials used. Thus, a mechanically load-bearing functional structure, for example, can be formed from the functional materials, or a functional structure that performs mechanical dynamic functions.In a particular embodiment, it can further be provided that a functional material, in particular the only functional material, is aluminum or an aluminum alloy. Aluminum can form functional structures with high mechanical strength, particularly in certain alloys with a low structural weight. This is utilized in engine construction or, for example, also in aircraft construction. The mechanical strength properties can be understood to mean, for example, the breaking strength and / or the toughness and / or the elasticity / stiffness.Furthermore, it can be provided that a heat conducting material, in particular the only heat conducting material, is copper or a copper alloy. Despite a relatively high specific weight, copper is suitable as a heat-conducting material because of its good heat-conducting properties and also because of the relatively low price.Furthermore, in a component, it can be provided that the heat source is surrounded by at least two different heat conducting materials in a solid angle region which corresponds to at least half of the total solid angle, in particular on all sides, wherein a first heat conducting material has a higher specific heat conduction value than the second heat conducting material, characterized in that the proportion of the first heat conducting material becomes smaller as the distance from the heat source increases. This provides a construction in which the objects of the invention are achieved by a combination of a plurality of heat-conducting materials, wherein, in addition, these two heat-conducting materials can be combined with one another in a suitable manner for optimizing heat-conducting properties and / or for optimizing the overall material price or for other reasons. For example, when the material price of the first heat conductive material is higher than that of the second heat conductive material, the aforementioned structure can reduce the price of the cooling structure in the component.According to the invention, it is provided that the heat source is surrounded by a heat distribution body in the form of a ring made of a heat-conducting material, and that, starting from the outer circumferential surface of the ring, a plurality of heat-conducting bodies made of a heat-conducting material, which form heat-conducting paths, extend radially starting from the heat source in cross section with their longitudinal axes. The ring acts as a heat distribution body and ensures optimized heat distribution in the immediate vicinity of the heat source. It also forms a heat sink by balancing the storage of thermal energy at power peaks of the heat source.In the design of the heat-conducting bodies which form corresponding heat-conducting paths, it is provided according to the invention that the heat-conducting bodies are designed in the form of a strand, plate and / or with a cross section which narrows at least in sections radially outwards with increasing distance from the heat source. Simple heat-conducting bodies can thus be constructed, which are also simple to produce and which can be connected to the functional materials, for example, in a casting process. In this case, for example, aluminum as functional material and copper as heat-conducting material or alloys of these two materials can be bonded to one another in a materially bonded manner by first producing a copper element and then casting it with aluminum or an aluminum alloy under a protective gas atmosphere or in a vacuum, wherein oxidation of the copper element by the protective gas or vacuum is prevented, so that a direct connection of the two materials is made possible.In principle, for the production of a component of the type explained above, it is conceivable that at least one functional material is or is connected to at least one heat-conducting material by casting, pressing, shrink-fitting or by an additive manufacturing method. In particular during casting, but also in additive manufacturing methods, very complex combination structures of functional materials and heat-conducting materials can be realized.The invention is shown below on the basis of exemplary embodiments in figures of a drawing and explained below. This shows FIG. 1 shows the schematic representation of a component with a heat source and two heat conducting paths, FIG. 2 shows another schematic illustration of a component with a heat source and two heat conducting paths, FIG. 3 shows a further illustration of a component with a heat source and two heat conducting paths, FIG. 4 shows a cross-sectional illustration of a stator of an electric motor with a cooling device of conventional design, FIG. 5 schematically shows an electric motor in cross section with a somewhat more detailed illustration of the heat flows, FIG. 6 is a cross-sectional view of an electric motor with a cooling device according to the invention; and FIG. 7 shows a perspective illustration of a stator of an electric motor with heat conducting paths, illustrated by way of example, which are formed by heat conducting plates.FIG. 1 schematically illustrates a component 1 which is not necessarily of rotationally symmetrical design and which has a heat source 2 embedded in a functional material 3. The functional material 3 can, for example, fulfil the function of mechanically holding the heat source 2. Embedded in the functional material 3 and connected to it are two heat conducting paths 4 a, 4 bwhich are each formed as strand-shaped heat conducting bodies made of a heat conducting material. The strands 4 a, 4 bmay have a round, elliptical or rectangular cross section, for example.The arrangement from FIG. 1 has a constant cross section between the heat source 2 and a heat exchange surface 5, which is arranged at a first distance from the heat source 2. This provides that the thermal conductances of the individual thermal conduction paths 4 a, 4 bare each constant over the distance from the heat source. In addition, the total heat conductance, which results as the sum of the heat conductances of the strands 4 a, 4 bat each distance from the heat source 2, is constant as a function of this distance up to the heat exchange surface 5 a. The heat exchange surface 5a is formed on a heat exchange body 5 which can be made of a similar material to the heat conducting paths 4a, 4b; however, the heat exchange body 5 which has the heat exchange surface 5a can also be made of another material which conducts the heat better or less than the heat conducting paths / heat exchange bodies 4a, 4b. It is advantageous if the thermal conductances of the different materials do not differ too much.FIG. 2 schematically shows a component 1' with a heat source 2 which is directly connected to a heat distribution body 6. Proceeding from the heat distribution body 6, the heat conducting paths 4 c, 4 d, which are designed as heat conducting bodies, extend as far as a body 5, which provides a heat exchange surface 5 a. The heat exchange surface 5 amay be surrounded by a cooling fluid. The heat conducting path 4 cherein has a cross section decreasing with increasing distance from the heat source 2, so that for this heat conducting path the heat conducting value also decreases with increasing distance from the heat source 2. The heat conducting path 4 d, on the other hand, has a constant cross section, so that the heat conducting value is also constant as a function of the distance from the heat source 2 as far as the body 5. The sum of the thermal conductances of the thermal conduction paths 4 c, 4 dis decreased as the distance from the heat source 2 increases to the body 5.In FIG. 3, a component 1" is shown with a heat source 2 embedded in a functional material 3. Two heat conducting paths 4 e, 4 fwhich are designed as heat conducting bodies and which each have a constant cross section and thus also a constant heat conduction value between the heat source 2 and a first distance E 1 from the heat source 2 are illustrated. Between the distance E 1 and the distance E 2 from the heat source, the cross section and thus the thermal conductance of the thermal conduction path 4f decreases, while the thermal conductance of the thermal conduction path 4e first increases as a result of the increasing cross section and then decreases to zero, since the thermal conduction path 4e ends between the distances E 1 and E 2 from the heat source. Overall, it follows that the sum of the conductances of the routing paths 4e, 4f between the heat source 2 and the first distance E 1 is constant and firstly increases between the distance E 1 and E 2.It becomes clear in particular on the basis of FIG. 2 that according to the invention, heat conducting paths, such as the heat conducting path 4 c, can have a large cross section and thus a high heat conductivity value in the vicinity of the heat source 2, in order to initially transport the heat away from the heat source 2 effectively. As the distance from the heat source 2 increases, the cross section of the heat conducting paths and thus the heat conductance can decrease, since heat can increasingly also be emitted to the functional materials 3 or even be dissipated by thermal radiation. Temperature fluctuations can also be compensated more easily at a greater distance from the heat source. Consequently, as the distance from the heat source 2 increases, the heat is less likely to build up and this may also result in a lower reaction on the heat source.In principle, the different heat conducting paths of a component can consist of the same heat conducting material; however, they can also consist of different materials depending on the specific costs and the space requirement. For example, the two heat conducting paths 4 c, 4 dfrom FIG. 2 can consist of different heat conducting materials.FIG. 4 shows a conventional electric motor 100 that is a heat source, including an engine housing 101 and an integrated water jacket 102. The outer surface of the housing 101 thus forms a heat exchange surface. The water jacket is formed by one or more water-flown through cooling channels which run along the housing 101 radially on the outside. The arrows 104 indicate the thermal energy transported by thermal conduction. The arrows 103 indicate the heat generated within the stator, which is transferred to the motor housing 101. By using the invention, heat conduction paths in the housing 101 can be optimized.FIG. 5 illustrates the energy flux densities of the heat energy in a more detailed manner by means of a more detailed illustration of the heat transport. Radially on the inside, an electric motor 100 (radially outer stator) is shown in cylindrical form, which has a housing 101 which surrounds the stator. The arrows 103 represent the heat transport to the motor housing. Depicted within the motor housing material are the heat flux arrows 201 that are very closely distributed radially inward near the motor / stator 100, indicating a high energy flux density in this radially inner region of the motor housing 101. Toward the outer periphery of the motor housing 101, the energy flux density of the heat energy decreases. This is indicated by the more distributed energy flow arrows 202. 200 schematically indicates a radially outer water cooling at a heat exchange surface which surrounds the housing 101 of the electric motor radially on the outside.The finding that is drawn from the consideration of FIG. 5 is that the energy flux density of the thermal energy is greater in the radially inner region around a heat source than in the regions that are further away from the heat source.FIG. 6 shows, with reference to a component 1''' in the form of an electric motor in cross section, clearly that a number of functionally parallel heat conducting paths 304, 305 are provided in the material 302 of the housing, which extend from a heat source 100, which represents the actual electric motor, through the material 302 of the housing as far as a heat exchange surface 303. In this case, the material cross section and thus also the thermal conductivity value of the individual thermal conduction paths decreases with increasing distance from the heat source 100. In addition, as the distance from the heat source 100 increases, the total heat conductance of the heat conduction paths also decreases.In the example mentioned, a ring 300 as a heat distribution body is initially arranged directly surrounding the electric motor 100 and in thermal contact therewith. Wedge-shaped strands 304, 305 in cross section, which form heat conducting paths, issue radially outwards from the heat distribution body 300 and each decrease in cross section with increasing distance from the heat source 100. The heat conducting paths 304, 305 can be designed as conical tips; however, they can also merely form the cross section of plate-shaped heat conducting bodies which extend perpendicular to the plane of the drawing along the axis of the electric motor 100. The axis of rotation of the electric motor is denoted by the reference numeral 106.The cooling structure / heat-conducting structure with the heat distribution body 300 and the heat conducting paths or heat conducting lines 304, 305 can consist, for example, of copper, while the material of the component 1''', in which the cooling structure / heat-conducting structure is embedded according to the invention, is denoted by 307 and is not hatched for the sake of clarity. This functional material 307 can form the supporting mechanical structure of the housing of the electric motor 100 and consist of aluminum or an aluminum alloy.The arrows 103 represent the heat transport within the electric motor / stator, while the arrows 301 represent the heat transport in the heat distribution body 300. There, in relative proximity to the stator of the electric motor 100, the heat flux density is relatively high. Heat peaks are compensated for by the heat distribution body 300 and sufficient cross section is available for the heat transport. The heat conducting paths 304, 305 are connected radially outside the heat distribution body 300, the material cross section and heat conductivity of which decrease radially outwards through the star shape. However, the heat flux density indicated by arrows 301 decreases radially outward. Heat transfer can take place on the outer surfaces of the heat conducting paths 304, 305 at the transition from the heat conducting material copper to the functional material aluminum, so that the heat is at least partially dissipated to the functional material in the radially outer, less critical regions. The required cross section of the heat conducting material can thus decrease radially outwards in the cooling structure without a build-up of heat occurring.In FIG. 7, a component in the form of an electric motor is shown in a perspective view, which is denoted by 100 and has heat conducting paths 404, 405 on its radially outer circumferential surface, which are formed by copper plates. These copper plates can be designed as plane-parallel plates; however, they can also have a cross section which tapers radially outwards in a wedge-shaped manner. The functional material embedding the heat conducting paths 404, 405 is not shown in FIG. 7 in order to achieve better clarity. In principle, in this construction as well, the functional material can consist of aluminum or an aluminum alloy or another mechanically stable, easily processable and light material. The heat-conducting material can be, for example, copper or a copper alloy or another material with good heat conductivity. The material bond between the copper plates and the functional material can be created by a combined metal casting process. Production by means of a multicomponent 3D printing is also possible.

Claims

Component (1, 1', 1", 1"') having a heat source (2), wherein the component has one or more functional materials (3, 307) and one or more heat-conducting materials, wherein the functional material(s) forms / form a functional structure and wherein the heat-conducting material(s) forms / form heat-conducting paths (4a, 4b, 4c, 4d, 4e, 4f, 303, 304, 404, 405) of a cooling structure or heat-conducting structure for removing heat by means of the heat transport by heat conduction, wherein in a first region of the component, which extends from the heat source or a heat distribution body surrounding the latter, as far as a cooling device, in particular a heat exchange surface and a cooling fluid, at a first distance from the heat source, along the heat-conducting path or a plurality of parallel heat-conducting paths (4a, 4b, 4 c, 4 d, 4 e, 4 f, 303, 304, 404, 405), by configuring the selection of material and the cross sections of the heat-conducting materials as a function of the distance from the heat source (2), a heat conduction value decreasing with the distance from the heat source is available for each individual heat conduction path and / or total heat conduction value, wherein the heat source is surrounded by a heat distribution body (6, 300) in the form of a ring of a heat-conducting material and the total heat conduction value is obtained as the sum of the heat conduction values of all heat conduction paths at the respective distance from the heat source or the heat distribution body (6, 300), and wherein, starting from the outer circumferential surface of the ring, a plurality of heat-conducting bodies (4 a, 4 b, 4 c, 4 d, 4 e, 4 f, 303, 304, 404, 405) of a heat-conducting material, the heat conducting paths form, extend radially from the heat source in cross section with their longitudinal axes and are formed with a cross section tapering radially outwards at least in sections and are embedded in a functional material.Component (1, 1', 1", 1"') according to claim 1 with a spherical, cubic, cuboidal or cylindrical heat source (2), in particular electric motor (100), internal combustion engine, transformer or generator, in which a plurality of separate heat-conducting paths consisting of a heat-conducting material extend radially away from the heat source.Component (1, 1', 1", 1"') according to claim 2, characterised in that one or more or all functional materials (3, 307) have a lower specific weight than the heat conducting materials used.Component (1, 1', 1", 1"') according to one of Claims 1 to 3, characterized in that one or more or all of the functional materials (3, 307) used have a higher mechanical strength, in particular a higher breaking strength, than the heat-conducting materials used.Component (1, 1', 1", 1"') according to one of Claims 1 to 4, characterized in that a functional material, in particular the only functional material (3, 307), is aluminium or an aluminium alloy.Component (1, 1', 1", 1"') according to one of Claims 1 to 5, characterized in that a heat-conducting material, in particular the only heat-conducting material, is copper or a copper alloy.Component (1, 1', 1", 1"') according to one of claims 1 to 6, in which the heat source (2) is surrounded by at least two different heat conducting materials in a solid angle region which corresponds to at least half the total solid angle, in particular on all sides, wherein a first heat conducting material has a higher specific heat conduction value than the second heat conducting material, characterized in that the proportion of the first heat conducting material becomes lower as the distance from the heat source increases.Component (1, 1', 1", 1"') according to one of Claims 1 to 7, characterized in that the heat-conducting bodies (4a, 4b, 4c, 4d, 4e, 4f, 303, 304, 404, 405) are of strand-shaped or plate-shaped design.Component (1, 1', 1", 1"') according to one of Claims 1 to 8, characterized in that at least one functional material is connected to at least one heat-conducting material by casting, pressing, shrink-fitting or by an additive manufacturing method.

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