Patent Application
20240286508
The present invention relates to a floor assembly for an inductive charging device for inductive charging of a motor vehicle.
In the case of at least partially electrically powered vehicles, regular charging of the vehicle's electrical energy storage system is necessary. In principle, a direct electrical connection can be established between the vehicle and an external electrical energy source, such as a power connection. However, this requires manual action by a user.
It is also known to charge the vehicle, i.e. in particular the electrical energy storage unit, inductively. A primary coil is located in a ground assembly outside the vehicle, which interacts inductively with a secondary coil (“vehicle assembly”) in the vehicle to charge the energy storage unit.
During operation of the loading device, the motor vehicle to be loaded is located on a surface above the floor assembly, which is why the floor assembly must be designed in such a way that it can bear the load of the motor vehicle to be loaded. Furthermore, during operation of the charging device, heat can be generated in the base assembly by the charging power to be provided, which can lead to an undesirable rise in temperature of the base assembly and thus also to a failure of the electrical and/or electromagnetic components.
The present invention therefore deals with the problem of providing an improved or at least different embodiment for a base assembly for an inductive charging device of the type mentioned at the beginning, which in particular overcomes the disadvantages known from the prior art.
According to the invention, this problem is solved by the object of the independent claim(s). Advantageous embodiments are the subject matter of the dependent claim(s).
The present invention is based on the general idea of increasing mechanical load capacity and power transmission when charging an electric vehicle by means of a floor assembly according to the invention with a base plate and a core arrangement with core bodies and a flat coil supported above it via at least one support by using the base plate in particular as a cooling plate and the at least one support is designed as a heat-conducting element made of a material with a thermal conductivity of λ>5 W/(mK) in order to dissipate heat from, for example, the flat coil or the core arrangement via the at least one support to the cooling plate and thus heat dissipation or to improve cooling of the flat coil, the core arrangement with the ferrite plates, which enables a higher charging power with the same conductor cross section or the same charging power with a smaller conductor cross section. In order to increase the mechanical load capacity and at the same time not or only marginally influence the magnetic field of the flat coil, the at least one support is arranged transverse to the spacing direction within a central area of an associated core body of the core arrangement. The central area is thereby limited by, for example, 80% of a diameter of the individual core bodies in the longitudinal direction and width direction, preferably 70% of the diameter of the individual core bodies in the longitudinal direction and width direction, particularly preferably 50% of the diameter of the individual core bodies in the longitudinal direction and width direction and very particularly preferably 30% of the diameter of the individual core bodies in the longitudinal direction and width direction. The flat coil has a Wire carrier which has at least one pressure platform arranged coaxially to an associated support, via which the Wire carrier rests on an associated core body of the core arrangement. This arrangement causes a central loading of the respective core body by the pressure platform and the support arranged under the core body, whereby the respective core body is only subjected to pressure, but not to bending. As ferrite is very pressure-resistant, such a core body can absorb a pure compressive load very well. This eliminates the need for an additional support structure and enables direct supporting and heat-dissipating contact between the core body and the support. The core arrangement has at least one such core body, which extends transversely to the spacing direction in the shape of a plate and has the middle area essentially in the middle and an edge area surrounding it at the edge. In the middle area of the respective core body, the magnetic flux density generated there by the current flowing in the conductor of the flat coil is sufficiently low, so that an arrangement of the heat-conducting support in this area, even if it is made of metal, is not critical with regard to the impairment of the magnetic flux density. With the floor assembly according to the invention, it is thus possible to operate it with a comparatively high charging power due to the heat-dissipating supports, so that undesirable heating, in particular overheating, which would have to reduce the charging power, can be avoided. At the same time, the pressure platforms, the supports and the core bodies, which are only loaded in compression, enable a high load-bearing capacity to be achieved with a small size, as load-distributing support structures can be omitted.
The floor assembly according to the invention for an inductive charging device for inductive charging of a motor vehicle parked on an underground, for example an electric vehicle, thus has in detail the base plate, which is designed in particular as a cooling plate and extends transversely to the spacing direction in the form of a plate. The spacing direction is the surface normal of the base plate and is usually vertical when installed. In addition, the floor assembly according to the invention has at least one flat coil which is designed as a primary coil or field coil and which has a conductor which is wound in a spiral shape and at the same time is spaced apart from the base plate in the spacing direction. Also provided is the core arrangement for magnetic flux guidance, which is spaced apart from the base plate and the flat coil and arranged between the base plate and the flat coil. A lower cavity is formed between the core body and the base plate, in which the at least one support is arranged, so that this at least one support preferably extends through the lower cavity in the spacing direction. The ferrite plate and thus the core arrangement is supported on the base plate via the at least one support. The at least one support is now designed as a heat-conducting element made of a material with a thermal conductivity of λ>5 W/(mK) and at the same time arranged transverse to the spacing direction within the central area of an associated core body, for example a ferrite plate. Seen in the spacing direction, the support therefore lies within the middle area, which spans in a plane transverse to the spacing direction. The supports serve to support the core arrangement or the flat coil arranged thereon and at the same time to control its temperature by connecting the flat coil or the core arrangement and its core body in a heat-transferring manner to the base plate, which is designed in particular as a cooling plate. If the flat coil and thus also the core arrangement heats up during operation of the base assembly according to the invention, uniform cooling of the core arrangement and the flat coil can be made possible via the core bodies and via several such supports, whereby the same charging power can be achieved with a smaller cross-section of the conductor of the flat coil and/or the ferrites of the core arrangement or a higher charging power can be achieved with the same cross-section of the conductor of the flat coil and/or the ferrites of the core arrangement. The arrangement of the respective support in the central region of the associated core body in accordance with the invention, as well as a pressure pedestal arranged coaxially to the respective axis of the support on the wire carrier, also allows the support to be positioned in relation to the associated core body in a range in which eddy current losses or hysteresis losses cannot occur, even when metallic materials are used for the support. The individual core bodies, for example the ferrite plates, are spaced apart from each other transversely to the spacing direction, wherein the magnetic flux density is significantly greater both between the individual core bodies and in their edge area than in the respective middle area of the core body. This also makes it possible to transfer loads, for example from vehicles traveling on the floor assembly, preferably exclusively as compressive loads and not as bending loads via the pressure platforms into the core bodies and from these into the supports.
The floor assembly according to the invention can be arranged recessed in a substrate, in particular flush with the surface thereof, although alternatively it is of course also conceivable to arrange it on the substrate.
The at least one support has a thermal resistance Rth between a connection surface to the core body and a connection surface to the base plate of Rth<0.5 K/W, preferably Rth<0.3 K/W, particularly preferably Rth<0.1 K/W.
In an advantageous further development of the solution according to the invention, the at least one support is made of a material with a thermal conductivity of λ>10 W/(m K), in particular a thermal conductivity of λ>50 W/(m K) or λ>100 W/(mK). For example, iron with a thermal conductivity λ of approx. 80 W/(m K) or aluminum with a thermal conductivity λ of 235 W/(mK) can be used as the material for the respective supports. In purely theoretical terms, it is even conceivable that plastics with corresponding metal particles are used, which can provide the heat transfer or thermal conductivity of λ>5 WZ(mK) required for the desired cooling effect.
In an advantageous further development of the solution according to the invention, the at least one support is at least partially made of metal, in particular aluminum. Alternatively, it is also conceivable that the at least one support is partially made of graphite or ceramic, in particular aluminum nitride or aluminum silicide. Graphite has a thermal conductivity λ of 15 to 20 W/(m K), while an aluminum nitride ceramic can even have a conductivity λ of 180 W/(m K). The use of such aluminum nitride ceramics in particular is of great interest where a lot of heat has to be dissipated, but where a material may not be electrically conductive under certain circumstances.
With the positioning according to the invention, it is thus possible for the first time to use metallic supports both for load dissipation and for heat dissipation and thus for heat dissipation or cooling of the flat coil or the core arrangement without or with only marginal influence on the magnetic field.
In an advantageous further development, the base plate has at least one cooling channel for a coolant. This enables active cooling of the base plate during operation, wherein the heat-conducting supports also cool the core arrangement or the core body and the flat coil arranged above it in the installed state. In addition, the actively cooled base plate in turn cools the air inside the lower cavity, making it possible to cool the electronics located there as well as the core arrangement or core body located above the lower cavity. Areas on which the respective supports rest on the base plate preferably have no cooling channels in order to ensure sufficient pressure stability.
The base plate itself is advantageously made of a metal or metal alloy, such as aluminum, to improve heat transfer between the coolant, base plate, air, and supports. The spaced arrangement of the base plate relative to the flat coil and the core arrangement also minimizes or at least reduces electromagnetic interaction between the base plate and the flat coil and the core arrangement. The distance between the base plate and the core arrangement in the spacing direction can be between several millimeters and several centimeters. By manufacturing the base plate from metal or a metal alloy, the floor assembly is also electromagnetically shielded from the ground below.
In a further advantageous embodiment of the floor assembly according to the invention, at least one support is circular, oval, star-shaped, rectangular with or without rounded corners or spiral-shaped in cross-section. The preferably metallic support can be made of solid material (in particular solid cylinders) or sheet material (in particular tubes or cups) or solid material with hollow chambers. In addition to a circular shape, the cross-sectional shape can also assume any other shape (e.g. rectangle, ellipse, etc.) and be variable in height, e.g. to make it easier to accommodate other components (e.g. circuit boards for the power or control electronics, support elements for the ferrites, etc.). Preference should be given to lightweight structures. Further advantages can result from optimizing the weight of the supports, e.g. hollow chamber profiles of the supports can contribute significantly to reducing the overall weight.
The support with a thermal resistance RT<500 mm2K/W, in particular with a thermal resistance RT<300 mm2K/W und and especially preferably with a thermal resistance RT<100 mm2K/W, is connected to the associated core body in a thermally conductive manner, for example with a material bond, in particular glued or soldered. Additionally or alternatively, the at least one support has a thermal resistance Rth between a connection surface to the core body and a connection surface to the base plate of Rth<0.5 K/W, preferably Rth<0.3 K/W, particularly preferably Rth<0.1 K/W. This enables significantly improved heat transfer and thus heat dissipation from the core bodies.
A retaining structure in the form of a plastic structure is provided for fixing at least one core body, with the plastic structure being connected to the core body and the support via a respective form-fit connection. The form-fit connection can be formed as a tongue and groove connection and/or by a conical head of the associated support and a complementary conical opening on the plastic structure. The conical head of the support and the corresponding conical opening in the plastic structure can result in a centering positive fit, which makes assembly easier. Chamfers in the joining area of the support or the plastic structure can also be helpful in this respect. In the assembled state, an upper edge of the plastic structure corresponds at least approximately to an upper edge of the support, or the plastic structure lies slightly below the upper edge of the support, so that it is ensured that a reliable heat-transferring contact, in particular also via a distribution plate (heat spreader, aluminum sheet, copper sheet, graphite foil), which is located between the core body on the one hand and the support and the plastic structure on the other hand, contacts the support. If the bonding or the thermal contacting of the distributor plate becomes loose over time and/or the distributor plate sags/bends downwards in the lateral area, the plastic structure ensures that the distributor plate remains directly attached to the core body.
To ensure that the alignment and position of the plastic structure remains constant and that it does not rotate around the axis of the support, the plastic structure and the support can still be connected via a positioning form-fit connection (e.g. tongue-and-groove), which is arranged in the area of the opening of the plastic structure or in the upper area of the support. Such a distributor plate can ensure improved heat transfer and thus improved cooling of the core arrangement, whereby it is of course clear that the distributor plate is also arranged within the central area, in particular to at least minimize any influence on the magnetic field and thus the generation of eddy current losses. In addition, the distributor plate is very flat with a thickness of <2 mm and is arranged closely below the core arrangement. In this area directly below and at a distance from the spacer areas of the core arrangement, the magnetic flux density is also significantly reduced compared to the area between the individual core bodies, as well as in their edge area, so that the use of electrically conductive materials for the distributor plate does not result in any major additional losses due to eddy currents or hysteresis effects, and the influence on the magnetic field is very low and therefore negligible.
In a particularly advantageous embodiment of the floor assembly according to the invention, the distribution plate is connected to the core arrangement via an adhesive layer with a thermal conductivity of λ>0.8 W/(mK) and/or a shear modulus of G<10 MPa. As the adhesive layer, for example an adhesive layer, is extremely thin, a reduced thermal conductivity λ of λ>0.8 W/(m K) is also sufficient here. In order to also be able to compensate for different thermal expansion coefficients between the core bodies, for example a ferrite plate, and the distributor plate, it is advantageous to provide the adhesive layer or the adhesive layer in general with a shear modulus G<10 MPa.
Other important features and advantages of the invention can be seen from the dependent claims, from the drawings and from the associated description of the figure based on the drawings.
It is understood that the above-mentioned features and those yet to be explained below can be used not only in the combination indicated in each case, but also in other combinations or on their own, without deviating from the scope of the present invention.
Preferred exemplary embodiments of the invention are shown in the drawings by way of example and will be explained in more detail in the following description, wherein identical reference signs refer to identical or similar or functionally identical elements.
They show, schematically in each case,
A floor assembly 1 according to the invention, as shown for example in
The floor assembly 1 has a base plate 8 that is designed in particular as a cooling plate 30. The spacing direction 7 runs parallel to a normal of the underground 6 and in particular along the perpendicular direction. As shown in
The core arrangement 10, in particular the at least one core body 11, is supported directly on a support 15, for example (see
The plastic structure 12 can hold several core bodies 11 (see also
As can be seen in particular from
As can also be seen in
As can be seen in particular from
The respective support 15 can in principle be solid (cf.
According to
Spacer elements 46 can protrude from the lower wire carrier 39 in the direction of the core bodies 11, allowing the core bodies 11 to be positioned transversely to the spacing direction 7.
The core body 11 also has a central region 18 and at least one edge region 22 (cf.
The support 15 only partially fills the lower cavity 14, leaving a flow space 16 for a fluid, in the embodiment examples shown for air, whereby the core arrangement 10 can transfer heat to the base plate 8 via the air and cooling of the core arrangement 10 and the flat coil 5 can be improved and consequently the efficiency of the base assembly 1 can be increased. It is therefore also possible to operate the floor assembly 1 with high power levels, particularly several kW, and consequently to charge the vehicle 3 to be charged more quickly or not to cause derating at any operating point.
In
Conveniently, a distributor plate 23 is arranged between the at least one support 15 and the core arrangement 10 or the retaining structure 13. Such a distributor plate 23 can ensure improved heat transfer and thus improved cooling of the core arrangement 10, wherein it is of course clear that the distributor plate 23 is also preferably arranged within the middle area 18, in particular in order to at least minimize an influence on the magnetic field and thus the generation of eddy current losses. Since the distributor plate 23 with a thickness <2 mm is arranged very flat and close below the core arrangement 10, the central area 18a associated with the distributor plate 23 can be larger and the edge area 22a associated with the distributor plate 23 can be smaller than the central area 18 or edge area 22 associated with the support 15, without large additional losses due to eddy currents or hysteresis effects in an electrically conductive material of the distributor plate 23 that cannot be tolerated (see
The manifold plate 23 can also be connected to the core arrangement 10 via an adhesive layer 24 made of a material with a thermal conductivity of λ>0.8 W/(mK) and/or a shear modulus of G<10 MPa. Since the adhesive layer 24, for example an adhesive layer, is extremely thin and has a large bonding surface to the core arrangement 10, a reduced thermal conductivity λ of λ>0.8 WZ(m K) is also sufficient here. Furthermore, in order to be able to compensate for different thermal expansion coefficients between the core bodies 11, for example a ferrite plate 27 and the distributor plate 23, it is advantageous to provide the adhesive layer or generally the adhesive layer 24 with a shear modulus G<10 MPa. The adhesive layer 24 can, of course, also be provided directly between the support 15 and the core body 11 if, for example, no distributor plate 23 is provided. An additional adhesive layer 24a can also be provided between the distributor plate 23 and the support 15 if a distributor plate 23 is present.
A thickness of the distributor plate 23 or the distributor layer 23a is in the range of 0.2 to 2.0 mm. In addition to increasing the heat-transferring contact surface between the core body 11 and the support 15, the at least one distributor plate 23 can also fulfill a support function. An insulating layer 58 can also be provided between the electrically conductive distributor plate 23 and the core body 11 and/or between this and the support 15.
As shown in
The distribution layer 23a has a lateral thermal conductivity λ>20 W/(m K), preferably λ>50 W/(m K), particularly preferably λ>100 W/(m K)). Such a distribution layer 23a may, for example, consist of graphite, i.e. be a graphite foil. Such a graphite foil is characterized by an anisotropic thermal conductivity due to its production, which has 5 W/(mK)<λ<10 W/(m K) in the thickness direction and λ>100 W/(m K) in the lateral direction. Due to this high lateral thermal conductivity, the heat can be conducted very well from the edge areas of the core body 11 to the support 15, which homogenizes the temperature distribution in the core body 11 during operation and reduces the risk of thermo-mechanical failure. Alternatively, a sheet made of a thermally conductive material (e.g. aluminum, copper) can be used. Since these materials have an electrical conductivity which leads to an interaction with an alternating magnetic field, care must be taken to ensure that such an electrically conductive distributor layer 23a or such a distributor plate 23 is used in an area, namely the central area 18 or a larger central area 18a, in which the existing field strength is sufficiently low (e.g. <1 mT) in order to avoid a significant influence on the magnetic field and associated losses. Such a position is given, for example, directly below the core body 11 if the outer edge 43 of the distributor layer 23a or distributor plate 23 is sufficiently recessed (e.g. 5 . . . 25 mm) in relation to the edge of the magnetic conductor, i.e. the core body 11. The distance must be matched to the strength of the magnetic stray field at the ferrite edge and can vary within a core body 11 over the circumference or may not apply at all.
According to
This avoids losses that can be concentrated at sharp edges.
In the exemplary embodiments shown, the floor assembly 1 has a cover plate 17. Cavities 41 are provided between the cover plate 17 and the upper wire carrier 39, in which, for example, a circuit board 42 can be arranged. In the exemplary embodiments shown, the base plate 8 is designed as a cooling plate 30, through which cooling channels 25 for a coolant run. The coolant actively cools the base plate 8 during operation. The actively cooled base plate 8 cools the core assembly 10 or the core body 11 and the flat coil 5 via the supports 15 and also the air and consequently the flat coil 5 and the core assembly 10 via the air. The base plate 8 is advantageously made of a metal or a metal alloy, in particular aluminum, in order to improve the heat transfer between the coolant, base plate 8 and air. The spaced arrangement of the base plate 8 relative to the flat coil 5 and core arrangement 10 minimizes or at least reduces magnetic or electromagnetic interaction of the base plate 8 with the flat coil 5 and the core arrangement 10. The distance between the base plate 8 and the core body 11 can be between 20 and 80 mm. By manufacturing the base plate 8 from a metal or metal alloy, the floor assembly 1 is also electromagnetically shielded.
The support 15 is preferably connected to the associated core body 11 and the base plate (8) in a thermally conductive manner with a thermal resistance RT<500 mm2K/W, in particular with a thermal resistance RT<300 mm2K/W and particularly preferably with a thermal resistance RT<100 mm2K/W. In particular, soldering or bonding can be used here, which enables a mechanical connection on the one hand and a heat-transferring connection on the other. Additionally or alternatively, the at least one support 15 has a thermal resistance Rth between a connection surface to the core body 11 and a connection surface to the base plate 8 of Rth<0.5 K/W, preferably Rth<0.3 K/W, particularly preferably Rth<0.1 K/W.
Several advantages can be achieved with the floor assembly 1 according to the invention:
| Number | Date | Country | Kind |
|---|---|---|---|
| 102021205980.5 | Jun 2021 | DE | national |
This application claims priority to International Patent Application No. PCT/EP2022/064082, filed May 24, 2022, and German Patent Application No. DE 10 2021 205 980.5, filed Jun. 11, 2021, the contents of both of which are hereby incorporated by reference in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/064082 | 5/24/2022 | WO |
