Patent Application
20150266385
The present invention relates to an energy transmission device for a vehicle which has a wheel axle and at least one wheel, wherein a wheel rim of the wheel is mechanically coupled to the wheel axle by means of a connecting unit, and wherein the wheel is designed to roll on an underlying surface in order to propel the vehicle.
The present invention further relates to an energy transmission arrangement for a vehicle which has a wheel axle and at least one wheel, wherein the wheel is mechanically coupled to the wheel axle and is designed to roll on and underlying surface in order to propel the vehicle.
During an energy transmission, electrical energy is transmitted from an object to another one. Hence, an electrical cable can, for example, be used for the transmission. The option alternatively exists for the electrical energy to be transmitted with the aid of a wireless energy transmission. The wireless energy transmission results in a higher degree of mobility and avoids the problems of establishing an electrical contact. In so doing, user friendliness of the system can be increased.
The physical basis for the wireless energy transmission in the near-field region is either the capacitive or the inductive coupling.
In the capacitive energy transmission, sender and receiver field plates are disposed parallel to one another and thus form in each case a sheet capacitor. If an electrical load is coupled to the field plates, an alternating current can flow across the sheet capacitors that have been formed when an AC voltage is applied, and electrical power can thereby be transmitted to the electrical load. Inductive energy transmission systems are, however, for the most part significantly more efficient.
In an inductive energy transmission, an alternating magnetic field is generated on the primary side with the aid of a coil. At least a portion of this alternating magnetic field penetrates a secondary side, which likewise comprises a coil. As a result, a voltage is induced in the coil of the secondary side and therefore energy is transmitted from the primary side to the secondary side. The coupling factor of the two coupled coils forms an important characteristic variable in the inductive energy transmission. The coupling factor is defined by means of the ratio of the mutual inductances to the self-inductances of the coils. An increase in the coupling factor or, respectively, an improvement in the coupling between the coils can be achieved by the use of ferromagnetic materials, which, for example, are mounted above or below the coils and bundle the magnetic flux. As a result, the efficiency of the energy transmission can be improved.
In addition, the option exists for so-called resonance capacitors to be disposed on the primary side and the secondary side which form with the coils corresponding resonance circuits. If the capacitance values of the resonance capacitors are selected such that both resonance circuits are in resonance at the operating frequency, the effect of the inductances of the coils is cancelled. In so doing, the transmitted power can be maximized and the efficiency of the power transmission can be optimized. This resonant operation of the primary side and the secondary side is usually referred to as a magnetic resonance method. As a result of the resonance circuits used during the magnetic resonance method, the power transmission is however extremely frequency dependent.
Wireless energy transmission methods can, for example, be used for charging traction batteries of electrically driven vehicles. In known arrangements for four-wheeled vehicles (e.g. electric vehicles, hybrid vehicles), a sender coil is, for example, horizontally installed in the floor or on a mat. The receiver coil is situated horizontally in the underbody (car body) of the vehicle. It is known that the transmittable power of this system is directly dependent on the diameter of the coils and the wireless air gap to be bridged. The smaller that the coils are designed, the lower is the efficiency and therefore the smaller is the expedient bridgeable distance between the sender and the receiver coil. In addition, the coupling or, respectively, the efficiency of the energy transmission is affected by a horizontal offset of the two coils. For this reason, the sender and the receiver coil have, for example, an identical, relatively large diameter (for example 30 cm). Such an arrangement is not suitable for integration into two-wheeled vehicles having an open chassis (for example bicycles) due to the selected coil diameter.
Arrangements for two-wheeled vehicles are known, in which the sender coils are, for example, disposed in a floor mat and the receiver coil in a vehicle stand. In so doing, the receiver coils can only be implemented with a diameter of approximately 2 to 3 cm. As a result, the expedient transmission path is likewise only a few centimeters (for example 2 to 3 cm). This subsequently places high demands on the accuracy of positioning the sender and the receiver coil in both the vertical and lateral direction. If the sender and receiver coil are not positioned exactly with respect to one another, the coupling factor is reduced and with it the efficiency of the energy transmission. This exact positioning of the sender and receiver coil with respect to one another leads however to the user friendliness of the wireless energy transmission system being reduced.
The present invention therefore provides an energy transmission device for a vehicle which has a wheel axle and at least one wheel, wherein a wheel rim of the wheel is mechanically coupled to the wheel axle by means of a connecting unit, and wherein the wheel is designed to roll on an underlying surface in order to propel the vehicle, wherein the energy transmission device has a connecting unit for connecting an electrical energy source or an electrical energy sink, and at least one transmission element which is electrically coupled to the connecting unit and is designed to exchange, by means of wireless transmission of energy, electrical energy between the electrical energy source or energy sink and an external energy transmission unit arranged outside the vehicle, wherein the energy transmission device is connected to the wheel of the vehicle in a rotationally fixed fashion.
The present invention furthermore provides an energy transmission arrangement for a vehicle which has a wheel axle and at least one wheel, wherein the wheel is mechanically coupled to the wheel axle and the wheel is designed to roll on an underlying surface in order to propel the vehicle, wherein the energy transmission arrangement comprises an inventive energy transmission device and an external energy transmission unit which is arranged outside the vehicle and is coupled inductively, capacitively or in a magnetically resonant manner to the energy transmission device for the purpose of transmitting electrical energy.
In contrast to the known energy transmission systems, the wheels or, respectively, the wheel rims of the vehicle are used for the disposal of the transmission element. In so doing, the option exists for, for example, even fraction batteries of two-wheeled vehicles with a high transmission capacity to be charged, wherein said vehicles do not have a floor assembly for accommodating larger receiver coils.
In addition, the energy transmission between the external energy transmission unit and the transmission element that is connected to the wheel of the vehicle in a rotationally fixed fashion can also be carried out when the wheels are rotating.
If the energy transmission device is mounted to a plurality of wheels of the vehicle, the transmittable power can be multiplied due to the larger effective total coil surface compared to a simply designed receiver coil in an underbody of the vehicle. In this regard, it is irrelevant whether the wheel used relates to a drive wheel of the vehicle or not.
Furthermore, the energy transmission device can be very universally used because said device is suited to all wheeled vehicles. Installation spaces of the vehicle are used for the energy transmission device which up until now were not intended for a disposal of transmission elements. By means of the inventive disposal of the transmission element in the wheel of the vehicle, a very compact design of the energy transmission device can be achieved.
In one embodiment, the connecting unit comprises a wheel hub, wherein the connecting unit for connecting an electrical energy source or an electrical energy sink is disposed on the wheel hub.
The connecting element is used for connecting the electrical energy source or the electrical energy sink. For example, the traction battery of an electrically driven vehicle can be connected to the connecting unit in order to charge said traction battery with electrical energy. By disposing the connecting unit on the wheel hub, the electrical contact to the traction battery, which is installed in a frame or a body of the vehicle, can be very easily established.
In a further embodiment, the connecting unit has a plurality of spokes, wherein the energy transmission device has an electrical line which is disposed in one of the spokes and electrically couples the transmission element to the connecting unit.
The disposal of the electrical line in one of the spokes provides a solution that is constructively very simple and reliable for the electrical contacting between the transmission element and the connecting unit. No additional mechanical elements, which would increase the weight of the wheel, are thereby necessary for guiding electrical lines.
The energy transmission device can also comprise a plurality of electrical lines, which are disposed in the plurality of spokes, for the electrical contacting between the transmission element and the connecting unit.
According to a further embodiment, the transmission element can be coupled inductively, capacitively or in a magnetically resonant manner to the external energy transmission unit for the purpose of transmitting energy.
Because the transmission element can be configured in various geometries in the wheel of the vehicle, an inductive, magnetic resonant or capacitive transmission method can be implemented using the energy transmission device according to the invention.
In a further embodiment, the transmission element is disposed on or in the wheel rim.
By arranging, for example, coils in a bicycle wheel rim having a rim diameter of 28 inches (622 mm), a high power output can be transmitted due to the large coil surface. Besides the inductive transmission method, transmission methods with a lower energy density (for example magnetic resonance methods) can furthermore also be implemented for a two-wheeled vehicle. In the known systems, the application of such methods fail because larger coils have to be used, which to date could not be installed in two-wheeled vehicles, due to the lower energy density.
The generally higher power density of the energy transmission device according to the invention furthermore enables the distance between the transmission element and the external energy transmission unit to be greater, whereby the user friendliness is increased for the user.
According to a further embodiment, the transmission element is disposed on the connecting unit in the vicinity of the wheel axle.
By means of such a disposal, the inertia forces caused by the transmission element can be reduced.
In a further embodiment, the transmission element is disposed in a cross-sectional plane of the wheel, wherein the wheel axle lies in the cross-sectional plane.
By disposing the transmission element in the cross section of the wheel, the external energy transmission unit can be variously positioned with respect to the vehicle. Depending on the wheel position, the external energy transmission unit can, for example, be disposed under the vehicle, on the side of the vehicle or in front of/behind the vehicle. In addition, further transmission elements can also be disposed in further cross-sectional planes of the wheels. For example, a second coil can be provided as a transmission element, which is disposed perpendicularly to a first coil. These leads to a plurality of wheel positions in which an efficient energy transmission can take place,
In a further embodiment, the transmission element comprises a coil.
Various geometries can be implemented for the coil. The coil can, for example, have a round or a rectangular cross-sectional surface. Ferromagnetic materials can furthermore be used which are, for example, mounted above or below the coils and which bundle the magnetic flux in order to thereby achieve an improvement in the coupling between the coil of the transmission element and a coil of the external energy transmission unit.
In a further embodiment, a longitudinal axis of the coil is disposed parallel to the wheel axis.
In this embodiment, the coil is disposed radially symmetrically on/in the wheel rim. In so doing, ferrite plates or cores for reinforcing the magnetic field can be disposed on/in the wheel rim. A large power output can be transmitted due to the large cross-sectional surface of the coil of the transmission element.
In a further embodiment, a longitudinal axis of the coil is disposed tangentially to a circle around the wheel axis.
The option thereby exists for one or a plurality of coils to be used for the energy transmission. The coils can, for example, be implemented on/in the wheel rim. In so doing, an installation space between the rim and the tire, which is already present and unused until now, is used for the disposal of the coils. The coils can also alternatively be disposed in the vicinity of the hub in order to reduce the inertia forces of the wheel.
According to a further embodiment, the energy transmission device comprises a magnetic sensor, which is designed to detect an orientation and/or a strength of a magnetic field.
With the aid of the magnetic sensor, the magnetic field formed for the energy transmission can be exactly determined. As a result, the option, for example, exists for the orientation of the energy transmission device to change in order to increase the efficiency of the energy transmission.
According to a further embodiment, the transmission element comprises a capacitor plate.
In this embodiment, the transmission element is capacitively coupled to the external energy transmission unit. The capacitor plate is preferably disposed in the vicinity of the hub/rotational axis of the wheel in order to reduce the inertia forces. In order to increase the capacitance, a plurality of capacitor plates can also be provided, which are connected in parallel.
According to a further embodiment, the energy transmission device has a position sensor which is designed to detect a position of the wheel.
With the aid of the position sensor, a precise positioning of the transmission element with respect to the external energy transmission unit can be ensured. As a result, a high degree of efficiency of the energy transmission is achieved.
In a further embodiment, the energy transmission device has a control unit which is electrically coupled to the connecting unit and is designed to control the energy transmission.
A very compact design of the energy transmission device is achieved by means of the additional integration of the control unit. Said control unit is preferably positioned in the vicinity of the hub in order to minimize the inertia forces of the wheel. Said control unit can furthermore be coupled to the position sensor and to the magnetic sensor, which determines the strength of the magnetic field, in order to control the energy transmission as a function of signals of both sensors.
In one embodiment of the energy transmission arrangement, the energy transmission device is electrically coupled to a traction battery of the vehicle and the energy transmission unit to an electrical energy supply network. The external energy transmission unit is designed to transmit electrical energy to the energy transmission device in order to charge the traction battery.
This constitutes a preferred embodiment of the energy transmission arrangement according to the invention. The power density of the transmission is increased by the inventive disposal of the energy transmission device in the wheel of the vehicle. This makes a greater distance possible between the energy transmission device and the external energy transmission unit. As a result, the user friendliness of the energy transmission arrangement is improved. In addition, the higher power density ensures a faster charging process of the traction battery.
It goes without saying that the features, characteristics and advantages of the inventive energy transmission device also correspondingly relate to or can be applied to the inventive energy transmission arrangement.
a, 1b, 2, 3, 4a, 4b, 5, 6, 7a, 7b, 8 and 9 show different embodiments of an energy transmission device for an electrically driven vehicle which can be coupled inductively or in a magnetically resonant manner to an external energy transmission unit; and
An embodiment of an inventive energy transmission device 10 for an electrically driven vehicle 12 is depicted in
Because the present example relates to an electrically driven bicycle 12, the bicycle 12 has a traction battery 24 which provides electrical energy for driving said bicycle 12. To this end, the traction battery 24 is connected via a wiring harness 26 to a connecting unit 28 which establishes the electrical contact to a wheel hub motor 30. The wheel hub motor 30 drives the bicycle 12 with the aid of energy supplied by the traction battery 24.
After a certain operating time of the bicycle 12, the fraction battery 24 has to be recharged with electrical energy. To this end, the bicycle 12 has the energy transmission device 10 according to the invention which is designed to feed transferred electrical energy into the wiring harness 26 by means of a wireless energy transmission and thereby charge the traction battery 24. The energy transmission device 10 is connected to the wheel 14 of the bicycle 12 in a rotationally fixed fashion. The energy transmission device 10 comprises a transmission element 32, in the present case a coil 32. The coil 32 is coupled via at least one electrical line 34 to the connecting unit 28 which is disposed on the wheel hub 20.
The electrical line 34 is advantageously configured in one of the spokes 18. A voltage induced in the coil 32 due to an alternating magnetic field or a current induced in the coil 32 can therefore be transmitted further via the electrical line 34, the connecting unit 28 and the wiring harness 26 to the traction battery 24. As a result, the traction battery 24 can be charged with electrical energy due to a magnetic field acting on the coil 32. In this exemplary embodiment, the coil 32 is radially symmetrically disposed on the wheel rim 16. In other words, a longitudinal axis of the coil 32 is disposed parallel to the wheel axle 22.
In order to strengthen or, respectively bundle the magnetic field, ferrite plates/cores 36 are disposed on the wheel rim 16. By means of the inventive disposal of the coil 32 on the wheel rim 16, the coil 32 has a larger diameter. As a result, a high power density can be achieved during the energy transmission. The energy transmission illustrated in
In the following figures, further embodiments of the energy transmission device 10 according to the invention are depicted, which are all based on the principle that the energy transmission device 10 is connected to the wheel 14 of the vehicle 12 in a rotationally fixed fashion. Identical elements with regard to preceding embodiments are therefore denoted by the same reference signs. The differences are substantially explained in regard to the sequential figures.
A further embodiment of the energy transmission device 10 is depicted in
In an alternative embodiment, the coils 32a, 32b and/or the ferrite plates 36 can be designed in the wheel rim 16.
An energy transmission arrangement 40, which comprises the energy transmission device 10 and an external energy transmission unit 42a, 42b arranged outside the vehicle 12, is depicted in
In order to transmit a large amount of energy, the energy transmission device 10 and the energy transmission unit 42 are designed symmetrically to a plane of symmetry 52 depicted in
In
a illustrates a further embodiment of the energy transmission arrangement 40 and the energy transmission device 10. In this embodiment, the coils 32 are disposed tangentially on/in the wheel rim 16. In other words, a longitudinal axis of the respective coil 32 is disposed tangentially to a circle around the wheel axle 22. In order to increase the magnetic field, ferrite plates 36 can be installed in the vicinity of the coils 32. The energy transmission of the energy transmission arrangement 40 is based on an inductive or magnetic resonant coupling between the energy transmission unit 42 and the energy transmission device 10.
In
A further embodiment of the energy transmission device 10 is depicted in
Due to the disposal of the coil 32 in the cross section of the wheel rim 16 and the wheel position detection using the position sensor 56, the energy transmission unit 42 can be disposed at different positions relative to the vehicle 12. This is depicted in
A further embodiment of the energy transmission arrangement 40 is depicted in
b shows a cross section of the wheel 14 to illustrate a further embodiment of the energy transmission arrangement 40. As can be seen in
In the embodiment of the energy transmission arrangement 40 depicted in
In
In
Instead of the one field plate 32a shown in
In order to increase the transmittable power of the energy transmission arrangement 40, the energy transmission device 10 and the energy transmission unit 42 can be designed symmetrically to the plane of symmetry 52 shown in
Although preferred embodiments of the inventive energy transmission device 10 and the inventive energy transmission arrangement 40 have thus been shown, it goes without saying that different variations and modifications can be undertaken without departing from the scope of the invention.
The energy transmission device 10 can, for example, be installed in any vehicles which have at least one wheel.
In addition, electrical energy from the vehicle 12 can also, for example, be fed into an energy supply network 46 using the energy transmission device 10.
With regard to the energy transmission device 10, a plurality of different embodiments can furthermore be combined with one another.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102012219062.7 | Oct 2012 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2013/068608 | 9/9/2013 | WO | 00 |
