Stationary bottom assembly for inductive charging device

Abstract

The present invention relates to a stationary bottom assembly (1), a housing (12) having a bottom (14) spaced apart from a ground surface (31) in a spacing direction (5); At least one flat coil (6) having a conductor (7) disposed within the housing (12); A core assembly (8) having at least one core body (9) having a central region (10) and at least one edge region (11); Equipped with At least one support (15) is provided, the support (15) being arranged in the central region (10) of the corresponding core body (9) and thermally connecting the core assembly (8) and the bottom (14); At least one support (15) extends through the bottom (14) and supports the housing (12) above the ground (31); A cooling air passage (16) extends below the bottom (14), particularly between the bottom (14) and the ground (31). It concerns a bottom assembly (1), which allows for the placement of the supports (15) without compromising the magnetic field and for improved cooling.

Description

[Technical field]

[0001] The present invention relates to a stationary bottom assembly for an inductive charging device for inductive charging of automobiles.

[0002] In at least partially electrically powered vehicles, a direct plug-in based electrical connection can be made between the vehicle and an external source of electrical energy for charging, but this requires manual intervention by the user.

[0003] It is further known to charge an electric energy storage device of a motor vehicle by induction. For this purpose, a corresponding charging device has an assembly inside the motor vehicle (vehicle assembly) and a stationary assembly outside the motor vehicle (ground assembly). In the assembly outside the motor vehicle, a primary coil is present, which cooperates by induction with a secondary coil of the assembly inside the motor vehicle to charge the energy storage device.

[0004] During operation of the charging device, heat may be generated within each assembly, particularly the stationary bottom assembly, due in particular to the charging capacity procured, which may result in an undesirable temperature increase in the bottom assembly and / or adjacent objects, and ultimately cause derating during charging (reduced charging capacity due to excessive heat in the system) or system failure.

[0005] The object of the present invention is therefore to propose an improved or at least further embodiment of a base assembly for an inductive charging device of the type mentioned at the beginning, which is characterized in particular by the fact that the rated power is achieved sustainably in as many operating points as possible (in particular at high outside temperatures, high humidity, high currents in the system).

[0006] The above problem is solved according to the invention by the subject matter of the independent claim 1. Advantageous embodiments are the subject matter of the respective dependent claims.

[0007] The invention is based on the general idea of ​​using a stationary bottom assembly according to the invention with a housing supported on the ground, with a flat coil arranged therein and a core assembly arranged likewise therein, to extend a cooling air passage between the housing and the ground, to allow active ventilation of said cooling air passage and to cool both the core assembly and the flat coil, thereby improving the energy transmission, in particular during charging of electric vehicles, where the stationary bottom assembly can be passed above by the vehicle to be charged. The housing has a bottom and is arranged at a distance from the ground in a separation direction. A flat coil with a conductor is arranged in the housing and at a distance from the bottom in the separation direction. Also arranged in the housing at a distance from the bottom, the conductor and the flat coil is a core assembly for guiding magnetic flux, which has at least one core body extending in a plate-like manner transverse to the separation direction and having a central region and at least one edge region. At least one support is provided for the support, which is arranged inside the central region of the corresponding core body and thermally connects the core assembly and the bottom, with the at least one support penetrating the bottom and the housing being supported directly or indirectly via a base plate on the ground. Below the bottom, in particular between the bottom and the ground, a cooling air passage extends, which allows a particularly effective cooling of the flat coil or the core assembly. In this case, particularly effective cooling is achieved on the one hand in that the cooling air flowing in the cooling air passage cools the bottom and through the bottom the closed interior of the housing in which both the flat coil and the core assembly are arranged is cooled. On the other hand, the core assembly or the flat coil is cooled via the at least one support, which supports the core assembly directly or indirectly on the ground and thus crosses the cooling air passage and is thus likewise cooled by the cooling air flowing in the cooling air passage.In this case, at least one support is used to support the core assembly or the flat coil and the cover plate arranged thereon, on which, for example, a vehicle can run. The stationary bottom assembly according to the invention allows the bottom assembly to be driven with high power, since particularly effective cooling of the core assembly, i.e., for example, the ferrite plate and the flat coil, is possible via the cooling air passages and the heat dissipation of the support or of the bottom.

[0008] In an advantageous development of the invention, a base plate is provided that extends in a plate-like manner in a direction transverse to the separation direction, where at least one support connects the core assembly and the base plate in a heat-transferable manner, and a cooling air passage extends between the bottom and the base plate. The flat coil is spaced apart from the base plate at its conductor in the separation direction. The magnetic flux is guided through the core assembly, where the core assembly is arranged between the base plate and the flat coil at a distance from the base plate and the flat coil in the separation direction. In this case, the core assembly and the flat coil are arranged above the base plate in a closed housing, where the housing is closed by a bottom to the base plate. The housing together with the core assembly and the flat coil is then supported on the base plate via at least one support that penetrates the bottom, and at the same time the core assembly and the base plate are connected in a heat-transferable manner. The above-mentioned cooling air passage then extends between the bottom and the base plate, which allows for an effective cooling of the flat coil or the core assembly.

[0009] To further support this effect, the supports or at least one of the supports can be made of a thermally conductive material with a thermal conductivity of λ>5 W / (m·K). However, purely theoretically, the base plate and / or the bottom of the housing can also be made of a thermally conductive material and have their own cooling passages, so that they are cooled not only by the cooling air flowing in the cooling air passages, but also by the coolant flowing in the cooling passages. The at least one support thus has a double role, namely, on the one hand, to support the core assembly or the flat coil arranged thereover, and on the other hand, to cool the flat coil or the core assembly and its core body by thermally connecting these components to the cooling air passages or the base plate. Thus, when the core assembly heats up during the operation of the stationary bottom assembly according to the invention, the heat can be dissipated via at least one support into the cooling air passages or into the base plate, in particular formed as a cooling plate, which allows a uniform cooling of the core assembly and the flat coils in a number of such supports, which in turn allows the same charging capacity to be achieved with conductors of the flat coils having a smaller cross-sectional area or a higher charging capacity with conductors of the flat coils having the same cross-sectional area. Furthermore, by arranging each support according to the invention below the central area of ​​the corresponding core body in the separation direction, the support can be positioned relative to the corresponding core body in an area where the magnetic flux density is sufficiently low that there is no or at least only a negligible risk of eddy current or hysteresis losses occurring even if a metallic material is used for the support.

[0010] This prevents distortion of the magnetic field of the coil system and thus other operating characteristics, and also prevents additional heating of the metal material indirectly by the magnetic field. In a flat coil formed as a primary coil in a stationary bottom assembly, such a central region is, for example, explicitly located in the center of the corresponding ferrite plate or the corresponding core body, where the distance to the edge of the core body, for example to the edge of the ferrite plate, may be different depending on the expected orientation of the primary magnetic field direction. That is, the edge region of each core body, for example each ferrite plate, can be set individually depending on the expected magnetic flux direction or shape of the magnetic flux density.

[0011] In an advantageous development of the stationary bottom assembly according to the invention, at least one support has a cavity, which is designed in such a way that the cooling air flowing into the cooling air passages is guided towards the core body, thus acting as an air cooling duct and enabling an effective cooling of the core assembly and the flat coils.

[0012] In an advantageous development of the stationary bottom assembly according to the invention, a deflection element is arranged on the base plate, which engages in the hollow space of the support, and serves to deflect the cooling air flowing in the cooling air passages, guide it in a comb-like manner upwards in the support and then downwards again. This allows for uniform cooling of the at least one support over its entire height, so that the support exerts its cooling effect not only on the connection area with the corresponding core body, but also on the inner space of the housing, which is closed through the bottom towards the base plate, in which both the core assembly and the at least one flat coil are arranged. This allows for particularly effective cooling of the stationary bottom assembly according to the invention and therefore for high-power operation.

[0013] In an advantageous development, the bottom and / or the base plate have at least one cooling passage for a coolant, which allows for active cooling of the bottom of the housing and / or the base plate during operation, which simultaneously results in cooling of the core assembly or core body and the flat coil arranged on top of the thermally conductive support in an assembled state. Furthermore, the actively cooled base plate or the actively cooled bottom cools the cooling air flowing in the cooling air passage.

[0014] The bottom and / or base plate itself is advantageously made of a metal or metal alloy, for example aluminum, which allows for improved heat transfer between the coolant, the cooling air, the bottom, possibly the base plate, the air and the support. By arranging the bottom and / or base plate at a distance from the flat coil and the core assembly, the electromagnetic interaction of the bottom or base plate with the flat coil and the core assembly is further minimized or at least reduced. In this case, the distance from the bottom and / or base plate to the core assembly in the distance direction may be in the range of a few millimeters to a few centimeters. At the same time, by manufacturing the bottom and / or base plate from a metal or metal alloy, magnetic or electromagnetic shielding of the stationary bottom assembly towards the ground below is performed.

[0015] In an advantageous development of the solution according to the invention, the at least one support is at least partially made of metal, in particular aluminum. Alternatively, the at least one support can be made partially of graphite or of ceramic, in particular aluminum nitride or aluminum silicide. Here, graphite has a thermal conductivity λ of 15-20 W / (m·K), whereas aluminum nitride ceramics can have a conductivity λ of up to about 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 removed, but where the material is not electrically conductive, in particular in certain circumstances.

[0016] Advantageously, a fan is provided for forcing cooling air into the cooling air passages, by means of which a cooling air flow in the cooling air passages can be forced, so that an active and thus particularly effective cooling of the stationary bottom assembly according to the invention can be achieved. Such a fan can be an internal fan, but in this case such a fan can of course also include an external fan.

[0017] In another advantageous embodiment of the stationary bottom assembly according to the invention, heat exchanger elements are arranged in the bottom and / or base plate, which protrude into the cooling air passages. Such heat exchanger elements can be embodied, for example, as cooling ribs or cooling rods and can provide a relatively large surface suitable for heat transfer, which allows in particular the removal of heat from the bottom and / or base plate and also from the supports connected to it via the bottom and / or base plate. Of course, purely theoretically, it is also possible for the individual supports to have further heat exchanger elements, which at least enlarge the surface of the support in the cooling air passages, but also the surface of the support in the housing and thus improve the heat transfer.

[0018] Advantageously, a distribution plate (heat spreader) is arranged between the at least one support and the core assembly or the holding structure. Such a distribution plate can ensure improved heat transfer and thus improved cooling of the core assembly. Of course, if the distribution plate is metallic, it is also arranged in the central region, which obviously at least minimizes, in particular, the effects of magnetic fields and thus the occurrence of eddy current losses.

[0019] In a particularly advantageous embodiment of the stationary bottom assembly according to the invention, the distribution plate is connected to the core assembly via an adhesive layer having a thermal conductivity of λ>0.8 W / (m·K) and / or a shear modulus of G<10 MPa. Since the adhesive layer, for example the glue layer, is very thin, a reduced thermal conductivity of λ>0.8 W / (m·K) is sufficient here. Furthermore, it is advantageous to provide an adhesive layer, or an adhesive layer in general, with a shear modulus of G<10 MPa in order to be able to compensate for the different thermal expansion coefficients between the core body, for example the ferrite plate, and the distribution plate.

[0020] Important further features and advantages of the invention are evident from the respective dependent claims, the drawings and the corresponding figure description based on the drawings.

[0021] It is understood that the features mentioned above, and those further described below, can be used not only in the respective combinations described, but also in other combinations or alone, without departing from the scope of the invention.

[0022] Preferred embodiments of the invention are illustrated in the drawings and will be explained in detail in the following description, where like reference numbers refer to identical or similar or functionally identical components. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a cross-sectional view showing a stationary bottom assembly according to the present invention. [Diagram 2] 11A-11C are further cross-sectional views showing the bottom assembly at different cutting planes. [Diagram 3] FIG. 3 is a cross-sectional view similar to FIG. 2 but showing yet another cross-section. [Figure 4] 11 is a cross-sectional view showing another embodiment of a bottom assembly according to the present invention.

[0024] 1 to 4, a stationary bottom assembly 1 according to the invention for an inductive charging device 2, for example for inductive charging of a motor vehicle 3, has a closed housing 12 with a bottom 14, the housing 12 being arranged at a distance from the ground 31 in the distance direction 5. The bottom assembly 1 furthermore has at least one flat coil 6 with a conductor 7 arranged in the housing 12 and spaced from the bottom 14 in the distance direction 5. Furthermore, a core assembly 8 for guiding the magnetic flux is provided, which is arranged inside the housing 12 between the bottom 14 and the conductor 7 at a distance from the bottom 14 and the flat coil 6, and has at least one core body 9 which extends in a plate-like manner transverse to the distance direction 5 and has a central region 10 and at least one edge region 11. At least one support 15 is provided for direct or indirect support against the ground 31, the support 15 being arranged in the central region 10 of the corresponding core body 9 and thermally connecting the core assembly 8 with the bottom 14. Here, the at least one support 15 penetrates the bottom 14, with the cooling air passages 16 extending between the bottom 14 and the ground 31 (see Figures 1 to 3) or between the bottom 14 and the base plate 4 (see Figure 4). The base plate 4 at least partially abuts against the ground 31.

[0025] The housing 12 has an upper housing part 13 tightly connected to a bottom 14, which can be formed as a plastic bottom 14' or as a metal bottom 14''. Cooling air 17 flows through the cooling air passages 16, in particular driven by a fan 18, for cooling the stationary bottom assembly 1 according to the invention during operation of the stationary bottom assembly 1.

[0026] Above the core assembly 8 or each core body 9 there is arranged a support element 30, which supports the upper housing part 13. A support plate (not shown) can also be arranged above the upper housing part 13, in which case it is also possible, purely theoretically, for the car 3 to drive directly over the upper housing part 13. In this case the stationary bottom assembly 1 is arranged in or on the ground 31, over which the car 3 to be charged can pass, for example.

[0027] The stationary bottom assembly 1 according to the invention thus allows for an effective cooling and thus a high-power operation of the stationary bottom assembly 1, where the support of the core assembly 8 in the central region 10 of each core body 9 also allows the support 15 to be arranged in the region where the magnetic flux density generated by the flat coil 6 is at a minimum, so that there is no or only a very small risk of disturbance of the magnetic field or magnetic flux density. This offers the great advantage that a metallic material can be used for the support 15, i.e. a material which is supportable and has favorable thermal conductivity, without causing eddy currents or hysteresis losses due to the material. In the stationary bottom assembly 1 according to the invention, the removal of heat and thus the cooling of the flat coil 6 or the core body 9 is possible not only via the thermally conductive support 15, but also entirely by arranging both the core body 9 and the flat coil 6 in a closed internal chamber 19 which is heat-transferably connected to the cooling air passage 16 via the bottom 14.

[0028] At least one support 15 may also have a hollow space 20, as shown in FIG. 2, which provides a relatively large surface area available for heat transfer inside the support 15, which surface can be used both for directly cooling the corresponding core body 9 and for cooling the closed internal chamber 19.

[0029] According to FIG. 2, a deflection element 21 can be arranged on the base plate 4, which engages in the cavity 20 and deflects the cooling air 17. According to the section AA in FIG. 2, the deflection element 21 has a circular cross section with lateral blades 22 connected to the bottom 14 or the plastic bottom 14'. According to the section BB, the cooling air passage 16 has a semicircular cross section. In this configuration, the cavity 20 arranged in the support 15 and divided by the deflection element 21 forms part of the cooling air passage 16, which improves the heat transfer from the flat coil 6 and the core body 9 to the cooling air 17. The bottom 14 is connected to the support 15 via a watertight adhesive 23. This allows a perfect sealing of the inner chamber 19.

[0030] The at least one support 15 may here at least partially be made of metal, for example aluminum, and / or preferably have a thermal conductivity of λ>5 W / (m·K), so that an effective heat removal of the core body 9 and the flat coil 6 can be achieved.

[0031] For the pumping of the cooling air 17 in the cooling air passage 16, the aforementioned fan 18 can be provided, connected to the surroundings and / or to an additional cooling device (not shown), for example a heat exchanger. The means for setting the power of the fan 18 furthermore allows for an open-loop or closed-loop control of the cooling power and thus also indirectly of the condition-dependent callable charging capacity of the stationary bottom assembly 1 according to the invention.

[0032] The bottom 14 or base plate 4 can also be made of aluminum and can further have cooling passages 24 through which a coolant can be conducted for additional cooling, which allows for a further improvement in the cooling effect and thus a significant increase in the charging capacity of the stationary bottom assembly 1.

[0033] Furthermore, a distribution plate 25 can be arranged between the at least one support 15 and the core assembly 8. The distribution plate 25 contributes to an improved heat transfer and thus to an improved cooling of the core assembly 8. It is clear that in this case, the distribution plate 25 is also preferably arranged inside the central region 10, in order to at least minimize the influence of magnetic fields and thus the occurrence of eddy current losses, especially in configurations of the distribution plate 25 made of metallic materials. Furthermore, the distribution plate 25 can be connected to the core assembly 8 via an adhesive layer having a thermal conductivity of λ>0.8 W / (m·K) and / or a shear modulus of elasticity G<10 MPa. Since the adhesive layer 26, for example the adhesive layer, is for example very thin, a reduced thermal conductivity λ of λ>0.8 W / (m·K) is sufficient here. Furthermore, it is advantageous to provide an adhesive layer or generally an adhesive layer 26 with a shear modulus of elasticity G<10 MPa, in order to be able to compensate for the different thermal expansion coefficients between the core body 9, for example the ferrite plate, and the distribution plate 25.

[0034] 1 in particular, it can be seen that a heat exchanger element 27 is arranged on the base plate 4, which projects into the cooling air passage 16 and further increases the surface area available for heat transfer. Corresponding to FIG. 4, a heat exchanger element 27 which projects into the cooling air passage 16 can also be arranged on the bottom 14.

[0035] 3, it can be seen that the bottom 14 or the plastic bottom 14' has individual webs 28 in the region below the support 15, which divide the continuous cooling air passage 16 located below the support 15 into individual passage sections 29. This allows a problem-free support of the support 15 on the base plate 4. As an alternative embodiment (not shown here), the webs 28 can be replaced by a number of individual rods, for example with a cylindrical cross section, arranged in an offset arrangement known to the expert, which promote heat transfer and offer only a small resistance to the air flow.

[0036] With the stationary bottom assembly 1 according to the invention, it is therefore possible to achieve a particularly effective cooling of the core assemblies 8 or the flat coils 6 via the hollow supports 15 formed as air ducts, which allow the core assemblies 8 or the flat coils 6 to transmit a higher charge energy. By arranging the supports 15 in the substantially central region 10 of each core assembly 8 and by forming them thermally conductive, the supports 15 can likewise contribute to the removal of heat and thus the cooling of the corresponding flat coils 6 with the conductors 7 or the respective corresponding core bodies 9, for example core assemblies 8 with ferrite plates, without risk of damage due to hysteresis effects or eddy current losses. In this case, the cooling air 17 flowing in the cooling air passages 16 can be adapted by the fan 18 in terms of its flow rate in accordance with the desired cooling power and / or can be supported by additional cooling of the base plate 4 via the coolant flowing in the cooling passages 24.

Claims

1. A stationary bottom assembly (1) for an inductive charging device (2) for inductive charging of a motor vehicle (3), comprising: a closed housing (12) having a bottom (14) spaced apart from the ground (31) in a spacing direction (5); At least one flat coil (6) having a conductor (7) disposed within the housing (12) and spaced apart from the bottom (14) in a spacing direction (5); a core assembly (8) arranged inside the housing (12) between the bottom (14) and the conductor (7) at a distance from the bottom (14) and the flat coil (6) in the separation direction (5) for guiding magnetic flux, the core assembly further comprising at least one core body (9) extending in a plate-like shape in a direction transverse to the separation direction (5) and having a central region (10) and at least one edge region (11); Equipped with At least one support (15) is provided, the support (15) being arranged in the central region (10) of the corresponding core body (9) and thermally connecting the core assembly (8) and the bottom (14); the at least one support (15) penetrates the bottom (14) and supports the housing (12) on the ground (31); a cooling air passage (16) extends below the bottom (14), in particular between the bottom (14) and the ground (31); Bottom assembly (1).

2. a base plate (4) extending in a plate-like manner in a direction transverse to the separation direction (5); the at least one support (15) stands on the base plate (4) and thermally connects the core assembly (8) and the base plate (4); The cooling air passage (16) extends between the bottom (14) and the base plate (4). The bottom assembly of claim 1 .

3. 3. The bottom assembly according to claim 1, wherein the at least one support (15) has a hollow chamber (20) in which the cooling air (17) flowing in the cooling air passage (16) can be guided to the core body (9).

4. 4. A bottom assembly according to claim 3, wherein the base plate (4) is provided with a deflection element (21) which engages in the cavity (20).

5. 3. A bottom assembly according to claim 1 or 2, wherein the at least one support (15) is at least partially made of metal, in particular aluminum.

6. 3. The bottom assembly of claim 1, further comprising a fan (18) for pumping the cooling air (17) flowing through the cooling air passage (16).

7. The bottom assembly of claim 1 or 2, wherein the bottom (14) comprises at least one cooling passage (24) for a coolant.

8. The bottom assembly of claim 2, wherein the base plate (4) comprises at least one cooling passage (24) for a coolant.

9. The base plate (4) is at least partially made of aluminum. The bottom assembly of claim 2 .

10. 3. The bottom assembly according to claim 1, wherein a distribution plate (25) is arranged between at least one support (15) and the core assembly (8).

11. 11. The bottom assembly according to claim 10, wherein the distribution plate (25) is connected to the core assembly (8) via an adhesive layer (26).

12. The bottom assembly of claim 11, wherein the adhesive layer (26) has a thermal conductivity of λ>0.8 W / (m·K) and / or a shear modulus of G<10 MPa.

13. 3. A bottom assembly according to claim 1, wherein a heat exchanger element (27) is arranged in the bottom (14) and projects into the cooling air passage (16).

14. 3. The bottom assembly of claim 2, wherein the base plate (4) is provided with a heat exchanger element (27) projecting into the cooling air passage (16).

15. 3. The bottom assembly according to claim 1, wherein the bottom (14) is formed as a plastic bottom (14') or a metal bottom (14'').

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