FIELD

The invention relates to a contactless charging device for arrangement on an underside of a motor vehicle, wherein the charging device is configured such that energy is contactlessly transferable to the charging device. The charging device then also has a first side facing away from the motor vehicle in a state in which the charging device is arranged on the underside of the motor vehicle, and a second side opposite the first side, facing towards the motor vehicle in a state in which the charging device is arranged on the underside of the motor vehicle. The invention also includes a motor vehicle having such a contactless charging device.

BACKGROUND

Contactless charging devices, such as inductive charging devices, are known from the prior art. The onboard charging device is usually referred to as a secondary charging device, and an infrastructure-side charging device is usually referred to as a primary charging device. By inductively coupling the primary charging device and the secondary charging device, energy can be transferred from the primary charging device to the secondary charging device, by means of which a motor vehicle battery can be charged.

In the event of an accident, it is important to protect relevant components of a motor vehicle as well as possible. As an example, DE 10 2016 014 964 A1 describes a vehicle having an inductive charging plate in the area of the vehicle bottom, secured to the vehicle bottom by means of a number of flexible retaining elements. Thus, by means of the retaining elements, the charging plate is resiliently mounted and can yield when driving from a curb, which is supposed to at least substantially exclude the risk of damage to the charging plate.

Furthermore, U.S. Pat. No. 6,478,106 B2 describes a transmission housing with a crash case arranged at an underside, the crash case having a suitable surface. This is to enable the transmission unit, in the event of an impact, to move against the direction of travel without damage and obstruction, if possible.

However, even more important than the protection of a charging plate or a transmission is the protection of a high-voltage battery of a motor vehicle as it poses a particularly high risk when damaged, in particular to occupants of the motor vehicle, such as because of a fire. Typically, in order to protect the battery, sophisticated bracing elements, deformable elements or the like are used and installed to protect the high-voltage battery as well as possible during an impact. However, this requires a lot of installation space and greatly increases the weight of the motor vehicle.

SUMMARY

The object of the present invention is to propose a possibility of how to provide protection for a high-voltage battery of a motor vehicle in a manner which is as simple, cost-effective, efficient in terms of installation space and weight-saving as possible.

In a contactless charging device according to the invention for arrangement on an underside of a motor vehicle, the charging device is configured such that energy is contactlessly transferable to the charging device, wherein the charging device has a first side facing away from the motor vehicle in a state in which the charging device is arranged on the underside of the motor vehicle, and a second side opposite the first side, facing towards the motor vehicle in a state in which the charging device is arranged on the underside of the motor vehicle. In addition, the second side is configured to be ramp-shaped so that a thickness of the charging device increases in a first direction, pointing towards the rear of the vehicle in a state in which the charging device is arranged on the underside of the motor vehicle, over a part of a length of the charging device in the first direction.

In this respect, the invention is based on the following findings: first, it is advantageous, in terms of installation space, to position the drive unit of the motor vehicle as flatly or deeply within the front end as possible to generate as much installation space there as possible, which may be used for maximizing a front trunk, for example. This results in the drive unit then being arranged in front of the high-voltage battery in the direction of travel, the latter in turn being preferably arranged in the underfloor of the motor vehicle. However, to then prevent, in the event of a frontal impact, such as an accident, the drive unit from being pushed or striking backwards against the high-voltage battery, very sophisticated measures have had to be taken so far, for example, the provision of additional bracing elements for intercepting the drive unit, also adding a lot of weight. Furthermore, the invention is based on the finding that a contactless charging device, which has not been used actively for crash design so far, can at least partially be arranged between the drive unit and the high-voltage battery to actively use it for crash kinematics. Now, this is advantageously accomplished by the invention by the second side of the charging device being configured to be ramp-shaped. Advantageously, this ramp shape enables the charging device to deflect a drive unit of the motor vehicle moving in the direction of the high-voltage battery such that the drive unit does not impact the high-voltage battery. Hence, the charging device fulfills a dual function of contactlessly receiving energy from a primary charging device and charging the high-voltage battery of the motor vehicle with the energy received, on the one hand, and that of a protective function for the high-voltage battery, on the other hand. Advantageously, additional components for protecting the high-voltage battery, especially with respect to a possible frontal impact, can thus be eliminated, therefore allowing to save both installation space and weight and additionally also costs.

Moreover, the thickness preferably increases over at least 25 percent of the total length of the charging device. For example, the thickness may increase over a partial length of between a fourth and half of the total length. This offers the great advantage that this ramp effect can be provided over a large part of the length of the charging device. The longer the distance which can be used for deflecting a drive unit impacting the second side, the smaller the stresses which the charging device has to withstand, and accordingly, the more efficient it becomes to cause a diversion of the drive unit. The risk of damaging the charging device or even the high-voltage battery can be further reduced thereby. Accordingly, it is preferred that the thickness does not only increase over most of half the length of the charging device, but preferably even over most of the total length of the charging device in the first direction.

Accordingly, it is a further particularly advantageous design of the invention if the second side is formed such that a force acting on the second side of the charging device in the first direction is at least partially, in particular for the most part, divertible into a second direction perpendicular to the first one, wherein the second direction represents a direction from the first side of the charging device to the second side of the charging device. In the intended installation position of the charging device, a force diversion of a force acting against the direction of travel on the second side occurs in an upward direction, that is in the direction of the motor vehicle and not in the direction of the ground on which the motor vehicle currently resides. This offers the great advantage, for example, that a drive unit can be intercepted considerably easier by other components of the motor vehicle, such as by a part of the body frame of the motor vehicle. Hence, in a frontal crash, the drive unit can be moved upwards by the charging device kinematically and supported by the body frame. Hence, advantageously, the drive does not impinge on the high-voltage battery without sophisticated measures being required.

According to a further advantageous design of the invention, it is preferred that the thickness of the charging device at least doubles, preferably even triples, over the course in the first direction from its minimum to its maximum. As an example, the minimum of the thickness can then be one centimeter. Due to this sizing and, above all, due to this significant increase in thickness, a particularly efficient diversion of the drive unit can occur so that it can be ensured that it does not strike the high-voltage battery even without sophisticated measures.

In general, the contactless charging device can be configured as a capacitive charging device, however, preferably, it is configured as an inductive charging device, thus being configured to draw energy from a primary charging device through inductive coupling with the primary charging device. Furthermore, the charging device is designed such that it is de-energized prior to an accident-related impingement, in particular de-energized in a state in which it is arranged on the motor vehicle already prior to the motor vehicle driving. As an example, this can be accomplished by switching off the charging device or decoupling it from the remaining onboard motor vehicle network or at least from the high-voltage battery immediately after a charging operation performed upon standstill of the motor vehicle prior to the motor vehicle driving. Furthermore, the contactless charging device can be configured as a charging plate, for example. The upper side of this charging plate, that is the second side, is configured with the described ramp function.

In order to provide this ramp function, there are in turn several configuration options for this second side of the charging device.

In general, it is preferred, that the thickness then increases continuously over the part of the length of the charging device in the first direction. Thus, the thickness should not be able to decrease again in sections in the first direction as this would diminish the efficiency of the force diversion or at least not contribute to it in an advantageous manner.

As an example, according to an albeit less preferred design, it can be contemplated that the thickness increases linearly over the part of the length of the charging device in the first direction. Thus, the second side of the charging device can be configured to be wedge-shaped in its cross section, for example. Thus, due to the linear increase in thickness, the second side is accordingly partially provided by a plane having a constant slope. This enables a particularly simple configuration of the charging device.

However, the thickness may also increase non-linearly over the part of the length of the charging device in the first direction, which is preferred. Hence, according to a further advantageous design of the invention, the second side is at least partially curved concavely. Thus, as an example, the slope of the second side can increase against the direction of travel. With such a shape of the second side, a continuous and less abrupt force diversion can be provided which is considerably more gentle and thus, in turn, reduces the risk of damaging the charging device and/or the high-voltage battery. It is then particularly preferred if the second side can be divided into at least two, preferably three, subsections in the first direction. In the first subsection, the thickness is at its minimum value and constant over the first subsection in the first direction. In the second subsection, following the first subsection in the first direction, the thickness increases up to is maximum value, in particular continuously and in a ramp shape and also advantageously with a slope increasing in the first direction. In the optional further third subsection, which may, however, also be omitted and which follows the second subsection in the first direction, the thickness maintains its maximum value, thus being constant again. The first side of the charging device and the second side in the first subsection and in the optional third subsection are then configured to be substantially flat, and the second side extends parallel to the first side in the first and third subsections.

Moreover, the invention also relates to a motor vehicle having a contactless charging device according to the invention or one of its designs. Hence, the advantages described for the contactless charging device according to the invention and its designs apply to the motor vehicle according to the invention in the same manner.

In a further advantageous design of the motor vehicle according to the invention, the charging device is arranged on the underside of the motor vehicle such that the first side of the charging device faces towards a ground underneath the motor vehicle, and the first direction extends from the vehicle front to the rear of the motor vehicle. In other words, the charging device is installed in the motor vehicle as already described above.

Now it is particularly advantageous, as also already described, if the motor vehicle has a drive unit, in particular an electric drive, and a high-voltage battery, wherein the charging device is arranged at least partially between the drive unit and the high-voltage battery, wherein the drive unit is arranged between the vehicle front and at least one part of the charging device, and the high-voltage battery is arranged between the charging device and the rear of the motor vehicle. Accordingly, the charging device can advantageously provide a protective function for the high-voltage battery in the event of a frontal impact by deflecting an electric drive upwards moving in the direction of the high-voltage battery and thus protecting the high-voltage battery from an impact of the electric drive even without sophisticated measures which would require additional weight.

Accordingly, it is a further particularly advantageous design of the motor vehicle if the motor vehicle is configured such that, upon the drive unit moving in the first direction due to an accident and the drive unit striking the charging device, the movement of the drive unit is partially redirected into the second direction, and the drive unit strikes a part of a body frame of the motor vehicle, and in particular not the charging device. In other words, the drive unit is diverted to a part of the body frame of the motor vehicle and can be intercepted thereby in a particularly efficient manner. In turn, a collision of the drive unit with the high-voltage battery can be avoided efficiently, even without any sophisticated measures.

In a further advantageous design of the invention, the charging device and/or the high-voltage battery are secured such that the charging device and/or the high-voltage battery partially move against the second direction during the spatial deflection of the drive unit moving in the first direction.

In other words, if the drive unit impacts the charging device due to an accident, the charging device is partially moved against the second direction, that is downwards, while the drive unit is moved upwards at the same time due to the ramp-shaped surface of the second side. Then it is preferred that not only the charging device, but also the high-voltage battery are somewhat moved together with the charging device against the second direction. As an example, the charging device and the high-voltage battery can be secured such that they somewhat swivel or tilt about a common pivot point while the drive unit is diverted in its course of movement. Advantageously, this downward movement can intercept a part of the impact energy.

Preferably, the motor vehicle according to the invention is designed as a motorized vehicle, in particular as a passenger car or truck, or as a passenger bus or motorcycle.

The invention also comprises combinations of features of the embodiments described.

