Inductive charging system for motor vehicles

Abstract

The following description relates to a system for inductively charging a motor vehicle battery, comprising: a charging plate (12) consisting of a secondary coil (14) for receiving a magnetic field generated by a primary coil and for inductively generating electrical energy; a ferrite screen (16) arranged adjacent to the secondary coil (14) for concentrating the magnetic field; a cooling plate (18) arranged adjacent to the ferrite screen (16) for cooling the ferrite screen (16) and for reflecting the magnetic field towards the secondary coil (14); and a shielding plate (20) laterally surrounding the charging plate (12) for reducing the lateral radiation of the magnetic field;wherein the shielding plate (20) has a recess (22) for at least partially receiving the loading plate (12), wherein the end sections of the shielding plate (20) forming the recess (22) have a collar (24) formed by means of a forming process to induce a circulating eddy current that opposes the magnetic field.

Description

[0001] The following descriptions concern a system for the inductive charging of a motor vehicle battery, which improves energy transfer between the primary and secondary coils and shields adjacent vehicle components from the effects of the magnetic field. Furthermore, the following descriptions concern a motor vehicle equipped with this inductive charging system.

[0002] German patent DE 10 2018 004 479 A1 discloses a vehicle underbody that shields against electromagnetic radiation and incorporates a secondary coil for inductive charging. The underbody consists of different layers, one of which is made of a plastic material, and in its installed state, the underbody is flush with the secondary coil.

[0003] There is a constant need to improve inductive energy conversion in motor vehicles, especially in terms of safety, material usage, space requirements and efficiency.

[0004] Based on this situation, the task at hand is to propose a system for the inductive charging of a motor vehicle battery, enabling optimization of safety, material usage, space requirements and efficiency.

[0005] The present problem is solved by the features of the independent claim. Advantageous embodiments are specified in the dependent claims, the description, and the drawing. Where technically feasible, the teachings of the dependent claims can be combined arbitrarily with those of the main and dependent claims.

[0006] In particular, the task is solved by a system for inductively charging a motor vehicle battery comprising: - a charging plate comprising a secondary coil for receiving a magnetic field generated by a primary coil and for the inductive generation of electrical energy; a ferrite screen arranged adjacent to the secondary coil for concentrating the magnetic field, in particular to minimize stray losses and increase the efficiency of energy transfer; a cooling plate arranged adjacent to the ferrite screen for cooling the ferrite screen and for reflecting the magnetic field towards the secondary coil, in particular to improve the efficiency of energy transfer; - a shielding plate laterally surrounding the charging plate to reduce the lateral radiation of the magnetic field, in particular to improve the electromagnetic compatibility of the charging plate and to increase the efficiency and positioning tolerance of the energy transfer; wherein the shielding plate has a recess for at least partially receiving the charging plate, wherein the recess-forming end sections of the shielding plate have a collar drawn up by means of a forming process to induce an eddy current circulating in opposition to the magnetic field.

[0007] The system concentrates, reflects, and directs the electromagnetic field (hereinafter referred to as the magnetic field) generated by the primary coil beneath the vehicle. This improves energy transfer between the primary and secondary coils and shields adjacent vehicle components from the effects of the magnetic field using the shielding plate. The shielding plate also influences the self-inductance of the primary coil within the floor plate, resulting in a similar self-inductance for different vehicles despite varying designs. This significantly enhances the system's versatility in various vehicle applications. The use of the shielding plate enables safe, space-saving, and cost-effective energy transfer between the primary and secondary coils.

[0008] The following sections explain advantageous aspects and subsequently describe preferred modified embodiments. Explanations, particularly regarding advantages and definitions of features, are essentially descriptive and preferred, but not limiting, examples. If an explanation is limiting, this will be explicitly stated.

[0009] The shielding plate can be designed as a flat metal plate made of at least one metal alloy that exhibits good shielding properties for electromagnetic fields. The thickness of the shielding plate is significantly smaller than its other dimensions, namely length and width. In particular, the thickness of the shielding plate can be less than 20 mm, less than 10 mm, or less than 6 mm, while the length and width are many times greater, making the shielding plate appear thin and flat. The shielding plate can have contours, especially indentations and raised areas. These contours can be produced by at least one forming process, such as compression forming, tensile forming, tensile-compressive forming, bending, and shear forming.The collar located at the recess can be formed from the shielding plate using a forming process and, in particular, can laterally overlap at least the secondary coil and the ferrite shield of the charging plate when installed. Specifically, it is provided that the shielding plate is stiffened by connecting it to adjacent vehicle components. This enables the use of a cost-effective, space-saving, and lightweight shielding plate.

[0010] The secondary coil may, in particular, have a housing to accommodate the coil windings. The housing makes it easier to stack the secondary coil with the ferrite shield and the cooling plate.

[0011] The ferrite shield concentrates the magnetic field to minimize stray losses and increase the efficiency of energy transfer in the vehicle. It also protects other electronic components of the vehicle from magnetic interference. The ferrite shield can consist of a composition of iron oxide and other metal oxides such as zinc, manganese, or nickel. Ferrites typically exhibit high magnetic permeability, enabling them to conduct magnetic fields effectively without weakening them. Additionally, ferrites have high electrical resistance, preventing the flow of eddy currents that would otherwise occur in metallic materials and could cause energy losses.

[0012] The system is connected to at least one rectifier, a control unit, and / or the vehicle's battery. The alternating current generated by the secondary coil can be converted into direct current via the rectifier and stored in the battery. The control unit can manage the charging process and switch it on or off as needed.

[0013] Alternatively or additionally, the secondary coil, the ferrite shield, and / or the cooling plate may have at least one contact surface. In particular, it is provided that the contact surfaces of the secondary coil, the ferrite shield, and / or the cooling plate are arranged substantially parallel to each other. Parallel here means that the normal vectors of the contact surfaces are parallel to each other. In particular, it is provided that the secondary coil, the ferrite shield, and the cooling plate are stacked in the loading plate. In particular, it is provided that the ferrite shield is arranged on a top surface of the secondary coil and the cooling plate is arranged on the top surface of the ferrite shield.A magnetic field generated by a primary coil can thus penetrate through the underbody of the vehicle to the underside of the secondary coil and be concentrated behind the surface of the secondary coil by the ferrite screen and reflected at least partially, and in particular completely, by the cooling plate to improve the efficiency of energy transfer.

[0014] Alternatively or additionally, the collar can be designed as a continuous collar in the area of ​​the recess. This prevents the magnetic field from heating adjacent vehicle components. In particular, the collar is designed to extend continuously around the side surfaces of the charging plate, overlapping at least partially, and preferably completely, the secondary coil and the ferrite shield laterally. This increases the coupling factor between the charging plate and the magnetic field and improves the system's efficiency.

[0015] Alternatively or additionally, the charging plate can be positioned within the recess by means of a relative movement between the shielding plate and the charging plate. Specifically, it is envisaged that, in a first assembly step, the charging plate is initially positioned and attached to the underbody of the vehicle. Subsequently, the shielding plate can be positioned and attached to the underbody. The charging plate extends at least partially through the recess of the shielding plate. The collar of the shielding plate and the charging plate are positioned relative to each other. The distance between the shielding plate and the charging plate plays a crucial role in the coupling factor and the efficiency of the inductive energy transfer. This distance significantly influences the strength of the coupling between the primary and secondary coils and how much energy can actually be transferred from the primary coil to the secondary coil.The distance between the collar and the charging plate can vary along the recess due to complex geometries of the charging plate. A preferred distance between the collar and the charging plate is essentially 5 to 25 millimeters. "Essentially" means that, due to the geometric design of the charging plate along the length of the circumferential collar, this distance is achievable to at least 80%. This distance allows for a good balance between shielding and coupling efficiency. In particular, the collar is designed, at least in certain areas, to be directly or indirectly connected and / or in contact with the cooling plate.

[0016] Alternatively or additionally, the collar's end face(s) can extend substantially in the direction of the side surfaces of the loading plate. This allows the collar's end face(s) to terminate substantially perpendicular to the adjacent side surfaces and / or perpendicular to the normal vector of the contact surfaces. In particular, it is provided that the collar's end face(s) can be arranged flush with the cooling plate. This allows the magnetic field to penetrate laterally, at least partially, to the cooling plate of the loading plate. Specifically, it is provided that the shielding plate in the collar area has a Z-shaped cross-section. This reduces the distance between the shielding plate and the secondary coil, allowing the magnetic field to penetrate deeper laterally into the loading plate. This has a positive effect on the system's coupling factor with the magnetic field.

[0017] Alternatively or additionally, the shielding plate can be designed to at least reduce the lateral radiation of magnetic fields in the frequency range between 79 and 90 kHz. In particular, the lateral radiation of the magnetic field can be completely prevented by the shielding plate. Adjacent vehicle components can be protected from the influence of the magnetic field by the shielding plate. In particular, this can prevent unwanted heating of the adjacent vehicle components.

[0018] Alternatively or additionally, the charging plate and / or the shielding plate can be arranged on the underbody of the vehicle. This arrangement on the underbody allows for inductive energy transfer from the underside of the vehicle. The magnetic field generated by the primary coil against a surface can be guided by the shielding plate attached to the underbody in such a way that a similar self-inductance of the primary coil is ensured even in different vehicles. In particular, the shielding plate can be designed such that the primary-side self-inductance and the system-side mutual inductance vary only slightly with changes in the vehicle's position.

[0019] Alternatively or additionally, the collar can extend from the underbody of the vehicle at least partially in the vertical and horizontal directions. This allows adjacent vehicle components to be reliably shielded from the magnetic field and improves the coupling with the magnetic field, or the coupling factor of the system. In particular, the magnetic flux emerging laterally from the ferrite is less disturbed than would be the case with a continuously flat shielding plate. Specifically, the collar is designed to form an angle between 10° and 80° with the underbody, particularly 20° to 70°, and most preferably 30° to 60°. This allows the shielding plate to be positioned further away from the secondary coil laterally. The distance between the shielding plate and the charging plate decreases towards the side surface of the cooling plate.

[0020] Alternatively or additionally, the cooling plate can be made of aluminum, copper, or another suitable material. This avoids or reduces heating of the cooling plate by induction. The cooling plate material also exhibits good thermal conductivity and is therefore suitable for cooling the ferrite shield and adjacent components. In particular, the cooling plate is designed to act as an electromagnetic reflector. The reflector directs the magnetic field in a desired direction to maximize energy transfer efficiency.

[0021] The problem is further solved by a motor vehicle with a system for inductively charging a battery, which can be designed and further developed as described above. In particular, the motor vehicle has an underbody for arranging and attaching the charging plate and the shielding plate. The motor vehicle is designed such that it enables inductive charging of the vehicle's battery via the underbody.

[0022] A preferred technical solution is explained in more detail below with reference to the accompanying drawing and a preferred embodiment. The term "figure" is abbreviated as "Fig." in the drawing.

[0023] The drawing shows Fig. 1 A schematic side view of a first embodiment of the system for inductively charging a motor vehicle battery.

[0024] The described embodiment is merely an example that can be modified and / or supplemented in various ways within the scope of the claims. Each feature described for a particular embodiment can be used independently or in combination with other features in any other embodiment. Each feature described for an embodiment of a particular claim category can also be used accordingly in an embodiment of a different claim category.

[0025] Fig.Figure 1 shows a schematic side view of a first embodiment of the system 10 for inductively charging a motor vehicle battery, wherein the system 10 comprises a charging plate 12 consisting of a secondary coil 14 for receiving a magnetic field 36 generated by a primary coil 34 and for inductively generating electrical energy; a ferrite screen 16 arranged adjacent to the secondary coil 14 for concentrating the magnetic field 36; a cooling plate 18 arranged adjacent to the ferrite screen 16 for cooling the ferrite screen 16 and for reflecting the magnetic field 36 in the direction of the secondary coil 14; and a shielding plate 20 laterally surrounding the charging plate 12 for reducing the lateral radiation of the magnetic field 36.The shielding plate 20 has a recess 22 for at least partially receiving the loading plate 12, wherein the end sections of the shielding plate 20 forming the recess 22 have a collar 24 formed by a forming process to induce a circulating eddy current that opposes the magnetic field 36. The loading plate 12 and the shielding plate 20 are arranged on an underbody 32 of the vehicle. The distance 28 between the shielding plate 20 and the loading plate 12 is selected such that a coupling factor is optimized and, at the same time, the adjacent vehicle components 38 are shielded from the magnetic field 36. The distance 28 is located, in particular, between the side surfaces 26 of the loading plate 12 and the end faces 30 of the collar 24. The end face(s) 30 of the collar 24 are arranged flush with the cooling plate 18. This improves the lateral coupling of the ferrite layer 16 and the secondary coil 14 with the magnetic field 36.Due to the Z-shaped cross-section of the collar 24, the lateral distance between the shielding plate 20 and the secondary coil 14 is greater than the distance 26 between the end faces 30 of the collar 24 and the cooling plate 18. This allows the magnetic field 36 to penetrate deeper into the charging plate 12 laterally. The shielding plate 20 influences the self-inductance of the primary coil 34 in a base plate, resulting in a similar self-inductance of the primary coil 34 for different vehicles despite different designs. This particularly benefits the universal applicability of the system 10 in motor vehicles. The use of the shielding plate 20 enables safe, space-saving, and cost-effective energy transfer between the primary coil 34 and the secondary coil 14. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 004 479 A1

[0002]

Claims

[1] System comprising inductive charging of a motor vehicle battery: - a charging plate (12) consisting of a secondary coil (14) for receiving a magnetic field generated by a primary coil and for inductively generating electrical energy; a ferrite screen (16) arranged adjacent to the secondary coil (14) for concentrating the magnetic field; a cooling plate (18) arranged adjacent to the ferrite screen (16) for cooling the ferrite screen (16) and for reflecting the magnetic field towards the secondary coil (14); - a shielding plate (20) laterally surrounding the loading plate (12) to reduce the lateral radiation of the magnetic field; wherein the shielding plate (20) has a recess (22) for at least partial reception of the loading plate (12), wherein the end sections of the shielding plate (20) forming the recess (22) have a collar (24) raised by means of a forming process to induce an eddy current circulating in the opposite direction to the magnetic field. [2] System according to claim 1, wherein the secondary coil (14), the ferrite screen (16) and / or the cooling plate (18) have at least one contact surface, wherein in particular the contact surfaces of the secondary coil (14), the ferrite screen (16) and / or the cooling plate (18) are arranged substantially parallel to each other, wherein in particular the secondary coil (14), the ferrite screen (16) and the cooling plate (18) are arranged stacked in the charging plate (12). [3] System according to claims 1 and 2, wherein the collar (24) is designed as a continuous collar (24) in the area of ​​the recess (22), wherein in particular the collar (24) extends continuously around the side surfaces (26) of the loading plate (12). [4] System according to one of the preceding claims, wherein the loading plate (12) can be arranged within the recess (22) by means of a relative movement of the shielding plate (20) and the loading plate (12), wherein in particular the collar (24) of the shielding plate (20) and the loading plate (12) are arranged in a manner contrary to each other, wherein in particular the distance between the collar (24) and the loading plate (12) is essentially 5 to 25 millimeters, wherein in particular the collar (24) is designed at least in places such that it is directly or indirectly connected and / or in contact with the cooling plate (18). [5] System according to one of the preceding claims, wherein the end face(s) (30) of the collar (24) extends substantially in the direction of the side surfaces (26) of the loading plate (12), in particular the front face(s) (30) of the collar (24) can be arranged flush with the cooling plate (18), wherein in particular the shielding plate (20) in the area of ​​the collar (24) is Z-shaped in cross-section. [6] System according to one of the preceding claims, wherein the shielding plate (20) is designed to at least reduce the lateral radiation of magnetic fields in the frequency range between 79 and 90 kHz. [7] System according to one of the preceding claims, wherein the loading plate (12) and / or the shielding plate (20) can be arranged on an underbody (32) of the motor vehicle. [8] System according to claim 7, wherein the collar (24) extends from the underbody (32) of the motor vehicle at least partially in the vertical and horizontal directions, wherein in particular the collar (24) forms an angle between 10° and 80° with the underbody (32), in particular 20° to 70°, and most preferably 30° to 60°. [9] System according to one of the preceding claims, wherein the cooling plate (18) is made of aluminium or copper, wherein in particular the cooling plate (18) is designed as an electromagnetic reflector. [10] Motor vehicle with a system for inductively charging a battery according to any one of claims 1 to 9.

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