Device for transmitting energy and data between a stationary printed circuit board and a rotatable printed circuit board, and method for transmitting data

Abstract

In particular, the invention relates to a device for transmitting energy and signals between a first stationary printed circuit board (3) and a second printed circuit board (4) which can be rotated relative to the first printed circuit board (4). The first printed circuit board (3) comprises at least one first coil (310), and the second printed circuit board (4) comprises at least one second coil (410) which can be inductively coupled to the first coil (310), wherein the first and second coils (310, 410) are part of a resonant circuit, and - a first processor unit (µC1) paired with the first printed circuit board (3) of the device is designed to transmit first data (d3) to a second processor unit (µC2) paired with the second printed circuit board (4) by changing the excitation of the resonant circuit, and - the second processor unit (µC2) is designed to change the power consumption of the resonant circuit by separating the electric connection to the second coil (410) and thereby transmit second data (d4) to the first processor unit (µC1).

Description

[0001] Device for energy and data transmission between a fixed circuit board and a rotatable circuit board and method for data transmission

[0002] Description

[0003] The proposed solution relates in particular to a device for energy and data transmission between a first, fixed circuit board and a second circuit board rotatable relative to the first circuit board.

[0004] Especially in electric bicycle drives, it is known that signals from rotating components must be transmitted to a stationary processor unit. For example, to control one or more electric motors in an electric bicycle drive, it may be necessary to record measured values ​​from the rotating bottom bracket shaft and transmit them to the stationary control electronics. For example, a torque sensor is provided on the bottom bracket shaft so that the assistance power of one or more electric motors in the electric bicycle drive can be electronically controlled based on the torque acting on the bottom bracket shaft.

[0005] For example, it is known to use an inductive method for the wireless transmission of energy to a corresponding torque sensor and the transmission of measured values ​​from the rotating torque sensor to the stationary control electronics. A magnetic field is generated via a stationary first coil wound on a support component, which supplies the electronics located on the bottom bracket spindle with electrical energy via a second coil on the bottom bracket spindle. By short-circuiting the second coil located on the bottom bracket spindle, a frequency-coded exchange of information can take place from the rotating torque sensor to the stationary control electronics located in a drive housing.

[0006] However, the use of wound coils is associated with increased production effort, comparatively high weight, a comparatively large installation space requirement, and considerable costs. Furthermore, the frequency coding is quite sensitive to phase noise, so that significant interference can occur, especially at higher motor currents. Furthermore, the information exchange between the torque sensor and the stationary control electronics is extremely limited.

[0007] The proposed solution is therefore based on the task of providing an improvement for data transmission, particularly in the proposed application scenario.

[0008] Against this background, the proposed solution provides a device for data transmission comprising first and second printed circuit boards. At least one first (printed circuit board) coil is provided on a first, stationary printed circuit board. The second printed circuit board is rotatable relative to the first printed circuit board and has at least one second (printed circuit board) coil that can be inductively coupled to the first coil. The first and second coils are part of a resonant circuit. Furthermore, it is provided that

[0009] - a first processor unit of the device (having one or more first processors) assigned to the first circuit board is provided to transmit first data - wirelessly - to a second processor unit of the device assigned to the second circuit board by changing an excitation of the resonant circuit, and

[0010] - the second processor unit (having one or more second processors) is provided to change a current consumption of the resonant circuit (detectable by the first processor unit) by electronically separating an electrical connection to the second coil and to transmit second data to the first processor unit - wirelessly.

[0011] The proposed solution is therefore based on the basic idea of ​​providing an inductive coupling between first and second coils of first and second circuit boards for data transmission and, in addition, enabling the bidirectional transmission of first and second data using a resonant circuit. This not only allows for an extremely compact design of such a device, but also allows data to be transmitted from the stationary first circuit board and the control electronics comprising it to a rotating second circuit board and the electronics provided thereon, and vice versa. For example, when used in a drive unit for an electric bicycle, this provides considerably greater flexibility for evaluating measured values ​​on a rotating component than with solutions previously implemented in practice.Of course, corresponding advantages can be achieved not only in connection with drive units for electric bicycles, but also apply to other areas of application.

[0012] First and second data, which can be transmitted between the first and second circuit boards or their first and second processor units, are understood here to mean any type of information that can be evaluated by a processor unit and is suitable for triggering a function on the processor unit. Thus, for example, the first and second data can each comprise only a single bit. However, they can also be at least one command or numerical value and thus comprise multiple bits.

[0013] In one embodiment, the first processor unit is provided to change and thus modulate the excitation of the resonant circuit, in particular an excitation frequency, by temporarily interrupting the excitation. This allows a changing voltage signal to be generated at the inductively coupled second coil of the rotating, second circuit board during operation of the device. The first processor unit of the second circuit board, which is coupled to the second coil, can then in turn be provided to derive and thus extract the first data from the changing voltage signal or the detected changes. The first data can thus be impressed on a signal representative of the voltage at the second coil and thus transmitted in coded form.

[0014] For example, in this context, the first processor unit is provided to transmit different first data over different durations of interruptions and / or different time sequences during successive temporary interruptions in the excitation of the resonant circuit. For example, the duration of an interruption can be controllable by the first processor unit of the stationary first circuit board in order to transmit first data with mutually distinguishable information content to the second processor unit. Alternatively or additionally, a time sequence of successive temporary interruptions can be controllable by the first processor unit of the stationary first circuit board in order to transmit first data with mutually distinguishable information content to the second processor unit.The second processor unit can therefore be configured and provided to evaluate a measurable change in a voltage signal at the second coil resulting from a change in the excitation at the resonant circuit of the first printed circuit board and to derive different commands or different numerical values ​​therefrom, for example depending on the duration of a (characteristic) change and / or the temporal sequence of (characteristic) changes.

[0015] For example, the excitation of the resonant circuit can be interrupted once or multiple times via the first processor unit, resulting in a characteristic drop in a voltage signal at the second coil that can be evaluated by the second processor unit to distinguish between different commands and / or values. Depending on how long, for example, the excitation of the resonant circuit is interrupted, a longer or shorter drop in the voltage signal at the second circuit board represents a first or a second command. By modulating the excitation and in particular an excitation frequency of the resonant circuit, different commands can be sent wirelessly from the stationary circuit board and its first processor unit to the second processor unit of the circuit board rotating during operation of the device.

[0016] For the transmission of the second data from the second circuit board, which rotates during operation, to the first processor unit of the stationary circuit board, it can be provided that the second processor unit is designed to disconnect the electrical connection to the second coil in pulses. The second coil can thus be temporarily disconnected from a circuit provided on the second circuit board by the second processor unit. This results in an evaluable change in the current consumption of the resonant circuit when the first and second coils are inductively coupled. The first processor unit can then, in turn, be designed to evaluate this detectable change and derive the second data from it, in particular to extract it from a corresponding change in a signal dependent on the current consumption of the resonant circuit.The second data can thus be impressed on a signal representative of the current consumption of the resonant circuit and thus transmitted in coded form.

[0017] For example, in this context, the second processor unit can be provided to wirelessly transmit second data with distinguishable information content to the first processor unit via different time sequences during successive pulse-by-pulse disconnections of the electrical connection to the second coil on the second circuit board. In this case, the first processor unit can, for example, in turn be configured to interpret and / or evaluate successive measurable drops in the current consumption of the resonant circuit due to the temporary disconnection of the second coil from a circuit comprising the second processor unit as signal pulses, so that second data with distinguishable information content can be transmitted to the first processor unit via different sequences of such signal pulses.Using different pulse sequences, different bit sequences and thus different numerical values ​​can be transmitted wirelessly from the rotating second circuit board to the first circuit board.

[0018] In principle, the second processor unit can be provided to transmit at least one measured value for at least one component having the second circuit board using the second data. Thus, the proposed device, which is suitable for bidirectional communication, is particularly suitable as a measuring device for transmitting measured values ​​from a (rotor) component equipped with the rotating, second circuit board to a stationary first circuit board. For example, the measured value to be transmitted can be a measured value for a torque, a temperature, or another measured value recorded directly for the component or recorded for an environment surrounding the component. In particular, using the transmission methods explained above, it is of course also possible to transmit several different measured values ​​for different parameters.

[0019] For example, the second circuit board can have a measuring element for detecting the at least one measured value. In such an embodiment, the circuit board thus carries at least one measuring element connected to the second processor unit. For example, the at least one measuring element can comprise at least one strain gauge. In particular, a torque sensor can be formed on the circuit board with one or more strain gauges.

[0020] In principle, the inductive coupling of the first and second coils can be provided for the transmission of electrical energy to the second circuit board for operating the second processor unit. During operation of such an embodiment of a proposed device, electrical energy is thus transmitted to the second circuit board via the inductive coupling of the first and second coils (and optionally stored in an energy storage device on the second circuit board). The first and second coils provided for bidirectional data transmission are thus also used to supply power to the electronics on the second circuit board.

[0021] In one embodiment, the first data and / or the second data contain a check value for a cyclic redundancy check. This takes advantage of the fact that the proposed solution enables bidirectional communication, so that a meaningful check value for a cyclic redundancy check (CRC for short) can be transmitted in both directions and thus evaluated. This makes it possible to determine whether a data transmission was disrupted or faulty. For example, this method can more reliably rule out the use of faulty data for a control system, such as the control of one or more electric motors on a drive unit of an electric bicycle.

[0022] In one embodiment, the first and second circuit boards are arranged at a maximum distance of 3 mm from each other. For example, this distance is measured in an axial direction, with the axial direction running parallel to a rotational axis about which the second circuit board is rotatably mounted. In one embodiment, the circuit board surfaces of the first and second circuit boards, which have the first and second coils, are located opposite each other directly along such an axis for inductive coupling.

[0023] Particularly with a view to space-saving integration into a drive unit of an electric bicycle, one embodiment provides that windings of the first coil on the first circuit board extend around an opening in the first circuit board. Alternatively or additionally, the windings of the second coil on the second circuit board can extend around an opening in the second circuit board. Openings in the circuit boards enable, for example, the rotatable component carrying the second circuit board, such as a bottom bracket spindle, to extend through both openings and the two first and second coils to be compactly integrated on the circuit boards. However, a corresponding configuration is obviously not only advantageous for a drive unit for an electric bicycle, but can also be advantageous for other applications.

[0024] For example, the resonant circuit can be excited at a frequency in the range of 1.5 MHz to 2.5 MHz, in particular 2 MHz. In principle, the resonant circuit can be an LLC resonant circuit, for example, that operates above its resonant frequency.

[0025] The proposed solution also relates to a drive unit for an electric bicycle, which includes a variant of a proposed solution. For example, the first circuit board is secured to a housing part of the drive unit, and the second circuit board is secured to a rotatable bottom bracket shaft of the drive unit, which is rotatable relative to the housing part about a bottom bracket axis.

[0026] The proposed solution also includes an electric bicycle with a variant of a proposed drive unit.

[0027] Furthermore, the proposed solution also includes a method for signal transmission between a first, stationary circuit board and a second circuit board that is rotatable relative to the first circuit board. It is provided that the first circuit board comprises at least one first coil, and the second circuit board comprises at least one second coil that can be inductively coupled to the first coil. Furthermore, it is provided that the first and second coils are part of a resonant circuit, and

[0028] - by changing an excitation of the resonant circuit, first data are transmitted (wirelessly) to a second processor unit assigned to the second circuit board and

[0029] - by separating an electrical connection to the second coil (on the second circuit board), the current consumption of the resonant circuit is changed and second data is transmitted (wirelessly) to a first processor unit assigned to the first circuit board.

[0030] An embodiment of a proposed method is particularly suitable for an embodiment of a proposed device. The advantages and features of an embodiment of a proposed device explained above and below therefore also apply to embodiments of a proposed method, and vice versa.

[0031] The attached figures illustrate possible embodiments of the proposed solution.

[0032] Here we show:

[0033] Figure 1 shows a partial version of a proposed

[0034] Drive unit for an electric bicycle with a variant of a proposed (measuring) device in the region of a bottom bracket shaft; Figures 2A-2B show the bottom bracket shaft of the drive unit of Figure 1 in various views with a second, in this case annular, circuit board;

[0035] Figure 3 shows a housing part of the drive unit, which is used to support a

[0036] electric motor of the drive unit and to which a first circuit board of the measuring device is fixed;

[0037] Figure 4 is an enlarged section of the housing part of Figure 3 with a view of the first circuit board and in particular a first coil integrated on the first circuit board;

[0038] Figure 5 schematically shows the structure and interaction of the first and second circuit boards of the drive unit of Figures 1 to 4;

[0039] Figure 6 is a diagram illustrating an exemplary

[0040] Voltage signal on the first circuit board, in which first and second data exchanged between the first and second circuit boards are visualized in coded form;

[0041] Figure 7 shows a schematic representation of an electric bicycle with a drive unit of Figures 1 to 4.

[0042] Figure 7 schematically shows an electric bicycle 1 with an electric motor drive unit A. The electric bicycle 1 has a frame 10, which here, for example, comprises a top tube, a down tube, and a seat tube, and to which the drive unit A is attached in the region of an intersection point of the seat tube and the down tube. Part of the drive unit A are control electronics SE and a sensor device 15, for example designed with a torque sensor and / or a position sensor, for sensorically detecting a torque introduced into a bottom bracket shaft AT of the drive unit A by muscle power. The sensor device 15 can alternatively or additionally comprise a speed sensor, via which the speed of the bottom bracket shaft AT can be detected.

[0043] An output element of the drive unit A, here in the form of a hollow output shaft mounted coaxially to the bottom bracket shaft AT, is connected to a rear wheel 12 of the electric bicycle via a belt or chain 13 as a power transmission link in order to drive the electric bicycle 1. A wheel sensor 14 for determining a travel speed of the electric bicycle 1 is assigned to this rear wheel 12, for example. Of course, the wheel sensor 14 can also be provided on a front wheel 11 of the electric bicycle 1 instead.

[0044] The drive unit A is part of a drive system of the electric bicycle 1, which further comprises an operating unit 2. The operating unit 2 is, for example, fastened in the area of ​​a handlebar of the electric bicycle 1 in Figure 7 and is connected to the control electronics SE of the drive unit A. A user input can be recorded via the operating unit 2 and used to control the drive unit A. For example, the operating unit 2 comprises a display to inform a user of the electric bicycle 1 about

[0045] - the current operating status of the drive unit A, for example with regard to a set support level,

[0046] - a charge state of a battery unit 3 supplying the drive unit A with electrical energy, which contains at least one (rechargeable) battery, and / or

[0047] - a set gear which specifies the ratio with which a drive torque introduced by muscle power at the bottom bracket shaft AT is transmitted to the output element of the drive unit A.

[0048] Figures 1 to 5 show details of the drive unit A. In particular, a variant of a proposed (measuring) device is shown, which comprises first and second printed circuit boards 3, 4 as part of the control electronics SE and the sensor device 15.

[0049] Figure 1 shows, with a view into the interior of a housing of the drive unit A, a first housing part G on which the bottom bracket shaft AT is rotatably mounted and an electric motor E and a transmission device GE (see Figure 3) are arranged in order to be able to transmit a drive torque applied to the bottom bracket shaft AT by muscle power, with an assistance torque applied by the electric motor E, to the output element for driving the rear wheel 12. The housing part G shown here is, for example, a first housing half of the housing of the drive unit A, which is connected to a second housing half in order to define a housing interior in which, in particular, the electric motor E, the transmission device GE and the control electronics SE are protectively accommodated.

[0050] In order to effectively control the assistance torque by the electric motor E during operation of the drive unit A, the control unit SE can evaluate measured values ​​that are representative of a torque applied to the bottom bracket shaft AT. However, a measurement of the torque can be carried out during operation of the drive unit A on the rotating bottom bracket shaft AT. The corresponding measured values ​​must then be transmitted to a stationary part of the control electronics SE in order to be able to control the electric motor E depending on these measured values. In the measuring device shown, it is provided that the control electronics SE has the first circuit board 3, which is fixed to the housing part G and is therefore also referred to as the stator-side circuit board

[0051] 3. Furthermore, the control electronics SE comprises a second circuit board 4, in this case annular, which is attached to the bottom bracket shaft AT and is therefore also referred to as the rotor-side circuit board 4.

[0052] In the properly assembled state of the drive unit A, the first and second circuit boards 3 and 4 are positioned opposite each other with circuit board surfaces spaced 1 to 3 mm apart along the rotational axis of the bottom bracket shaft AT. Thus, facing coils 310 and 410 provided on the first and second circuit boards 3, 4 can be inductively coupled to each other, as will be explained in more detail below, particularly with reference to Figure 5.

[0053] Figures 2A and 2B first show the bottom bracket spindle AT in a single view with the second circuit board 4 attached thereto. The bottom bracket spindle AT extends through an opening in the annular second circuit board 4. The second circuit board

[0054] 4 comprises a top side 40 and a bottom side 41 facing away from this top side 40. Measuring electronics are provided on the top side 40 of the second, shaft-side circuit board 4. In this case, this measuring electronics comprises several strain gauges SG and evaluation electronics for encoding and decoding the measured values ​​for wireless transmission to the stationary first circuit board 3. Part of the measuring electronics is, in particular, a second processor unit in the form of a second microcontroller pC2 according to Figure 5.

[0055] The second coil 410 is provided on the underside 41 of the second circuit board 4, which, in the properly assembled state of the drive unit A, lies opposite an upper side 31 of the first circuit board 3 fixed to the housing. The second coil 410 extends with its windings in paths around the opening for the bottom bracket spindle A and thus on the second circuit board 4 around the axis of rotation of the bottom bracket spindle AT. According to the illustrations in Figures 3 and 4, the first circuit board 3 fixed to the housing has an annular circuit board section which carries the first coil 310 on its upper side 31. The first coil 310 thus extends with its windings in paths around an opening in the first circuit board 3 for the bottom bracket spindle AT.The opening in the first circuit board 3 is provided coaxially to a bearing opening O in the housing part G, through which one end of the bottom bracket shaft AT is led outwards in the properly assembled state of the drive unit A.

[0056] A transmitting and receiving electronics unit of the first circuit board 3 is provided on a circuit board section 32 of the first circuit board 3 that projects radially relative to the rotational axis of the bottom bracket spindle AT. Part of this transmitting and receiving electronics unit is, in particular, a first processor unit in the form of a first microcontroller pC1. The first measuring electronics unit pC1 is provided, in particular, for transmitting control commands to the shaft-side, second circuit board 4, as well as for forwarding and / or processing the measured values ​​received from the second circuit board 4.

[0057] When properly assembled, the first and second circuit boards 3, 4 are arranged concentrically with their annular spacings from one another but slightly spaced axially from one another. The axial spacing between the first and second circuit boards 3, 4 in the region of the opposing circuit board surfaces carrying the coils 310, 410 lies in the aforementioned range of 1 mm to 3 mm, so that the facing circuit board sections with the openings for the bottom bracket spindle AT are spaced from one another by 1 mm to 3 mm.

[0058] The coils 310, 410 are integrated into a respective printed circuit board 3 or 4. As illustrated in the schematic representation of Figure 5, the first coil 310 of the housing-side printed circuit board 3 is part of an LLC resonant circuit, which in this case is excited via a half-bridge with a frequency of approximately 2 MHz during operation of the drive unit A. For this purpose, a half-bridge with a coupling capacitor LLC and a measuring and decoding unit LDU are provided on the first printed circuit board 3, which are connected to the first microcontroller pC1. The interaction of the two coils 310, 410 and the half-bridge with a coupling capacitor LLC forms an LLC converter during operation. A supply voltage Sv is applied to the microcontroller pC1. Furthermore, the microcontroller pC1 can communicate with other components of the control electronics SE via communication signals Sc.During operation, the LLC resonant circuit generates a nearly sinusoidal current, which in turn creates a magnetic field at the first coil 310. This magnetic field, in turn, permeates the second coil 410 of the shaft-side second circuit board 4, so that the two coils 310 and 410 are inductively coupled to one another. Via this inductive coupling, energy can be transferred from the first circuit board 3 to the second circuit board 4 to supply the measuring electronics. This energy transfer is symbolized in Figure 5 by the reference symbol "e." Due to the nearly sinusoidal (at certain operating points possibly triangular) alternating field, interference with the measuring electronics of the second circuit board 4 is minimal in the illustrated embodiment, despite the magnetic field.

[0059] The measuring electronics of the second circuit board 4 comprise, in particular, strain gauges SG, whose measured values ​​can be converted into a voltage that can be evaluated by the second microcontroller pC2 and into a digital word via a Wheatstone bridge and a subsequent amplifier circuit. In particular, to supply the second microcontroller pC2 on the second circuit board 4, the second circuit board 4 has an energy storage device EN, which is connected to the second coil 410 via a rectifier and voltage doubler RF.

[0060] Furthermore, via the second microcontroller pC2 of the second circuit board 4, in the case of an existing inductive coupling with the first coil 310, a voltage signal measurable at the second coil 410 of the second circuit board 4 can be evaluated with the aid of a decoding unit DU of the second circuit board 4 for receiving data from the first circuit board 3. Furthermore, the microcontroller pC2 is coupled to a switching element SW of the second circuit board 4, via which an electrical connection of the second coil 410 to a circuit comprising, in particular, the energy storage device EN and the second microcontroller pC2 and the measuring bridge can be broken.

[0061] During operation of the drive unit A and with existing inductive coupling between the first and second coils 310, 410, it is possible in the illustrated embodiment variant to wirelessly transmit first data da from the first microcontroller pC1 of the first circuit board 3 to the second microcontroller pC2 of the second circuit board 4 and, conversely, to transmit second data d4 from the second microcontroller pC2 of the second circuit board 4 to the first microcontroller pC1 of the first circuit board 3 without additional components. The first microcontroller pC1 of the first circuit board 3 can send the first data da to the shaft-side circuit board 4 via a modulation of the excitation of the LLC resonant circuit.A modulation of the excitation of the LLC resonant circuit controlled by the first microcontroller pC1 results in a corresponding change in the voltage across the second coil 410, which can be detected by the measuring electronics of the second circuit board 4 with the decoding unit DU and the second microcontroller pC2. It is provided here that the first data d3 is transmitted via this change in the voltage across the second coil 410, encoded in a voltage signal representing the voltage.

[0062] The second microcontroller pC2, in turn, sends the second data d4 to the housing-mounted circuit board 3 by interrupting the electrical connection of the second coil 410 in pulses using the switching element SW, which can be controlled by the second microcontroller pC2. The measuring and decoding unit LDU on the first circuit board 3 can provide the first microcontroller pC1 with digital signals resulting from the changed current consumption of the LLC resonant circuit due to the pulsed disconnection of the second coil 410. Such an interruption also changes the current consumption of the LLC resonant circuit on the first circuit board 3 in pulses.Thus, signal pulses generated by the second microcontroller pC2 can be detected and evaluated by the first microcontroller pC1 on the first circuit board 3, with which the first data d3 can be transmitted in coded form in a signal representing the current consumption of the LLC resonant circuit.

[0063] The embodiment variant shown thus enables bidirectional, half-duplex communication between the two circuit boards 3, 4 and their microcontrollers pC1, pC2, in order to transmit, on the one hand, (second) data d4 with measured values ​​recorded on the bottom bracket shaft AT using the measuring electronics provided on the second circuit board 4 to the circuit board 3 fixed to the housing and, on the other hand, to transmit (first) data d3, for example in the form of control commands, to the second circuit board 4 rotating with the bottom bracket shaft AT.

[0064] In principle, it can also be provided to transmit test values ​​for a cyclic redundancy test as part of the transmitted first and second data d3, d4 in order to be able to detect any disturbances or errors during data transmission. The possibility provided within the scope of the embodiment variant of Figures 1 to 5 of providing bidirectional communication between the circuit boards 3 and 4 effectively and with comparatively few components is illustrated in more detail using the diagram in Figure 6. Here, a voltage signal f(t) is plotted against a time curve that can be detected at the microcontroller pC1 or the measuring and decoding unit LDU of the fixed circuit board 3.This voltage signal f(t) can be influenced both by the modulation of the excitation frequency of the resonant circuit by the first microcontroller pC1 and by the temporary, pulse-by-pulse disconnection of the electrical connection to the second coil 410 on the bottom bracket-side circuit board 4 when the first and second coils 310 and 410 are inductively coupled. The voltage signal f(t) shown can, in particular, correspond to a signal provided to the first microcontroller pC1 by the measuring and decoding unit LDU.

[0065] From the voltage signal f(t) shown in Figure 6, for example, a characteristic drop is representative of a signal sequence sf1 that was generated by a modulation of the excitation frequency of the resonant circuit on the first circuit board 3, controlled by the first microcontroller pC1. This characteristic drop is measurable on the second circuit board 4 with the measuring electronics comprising the second microcontroller pC2 due to the inductive coupling between the first and second coils 310, 410. There, the signal sequence sf1 is assigned - for example, by a lookup table, a register, or otherwise - to a specific command to the second microcontroller pC2, which is made available to the second microcontroller pC2 by the decoding unit DU.For example, the command transmitted wirelessly with the signal sequence sf1 to the second microcontroller pC2 requests or triggers the transmission of current measured values ​​to the first microcontroller pC1.

[0066] The voltage signal f(t) in Figure 6 also shows the response to the (query) command sent with the signal sequence sf1. Thus, in response to the received command of the signal sequence sf1, the second microcontroller pC2 transmits one or more measured values, for example, for a torque measured with the torque sensor of the strain gauges SG on the bottom bracket spindle AT, by pulse-by-pulse disconnection of the second coil 410. The wireless transmission of the measured value or values ​​takes place via several mutually distinguishable signal sequences sf2 to sf7. The signal sequences sf2 to sf7 can differ from one another, for example, in the frequency and / or length with which drops in the voltage signal f(t) are detected, i.e., for example, how long corresponding drops in the voltage signal f(t) last and how long the pauses between two consecutive drops are.In this way, second data encoded in the voltage signal can be wirelessly transmitted to the housing-mounted first circuit board 3 and its first microcontroller pC1 via the pulsed separation of the second school 410. For example, each signal sequence sf2 to sf7, alone or in combination with at least one further signal sequence sf3 to sf6, can represent a specific bit sequence and thus a numerical value, a response, or a correspondingly coded command.

[0067] Deviating from the representation in Figure 6, in an embodiment variant of the proposed solution it can also be provided that the second microcontroller pC2 transmits measured values ​​to the first microcontroller pC1, e.g. with signal sequences sf1 to sf7, without prior request from the first microcontroller pC1, for example at fixed times and here in particular cyclically.

[0068] Compared to previously known solutions, particularly in the field of electric bicycle drives, the proposed solution is distinguished by the elimination of winding bodies and explicit coils, allowing for a smaller installation space for a corresponding measuring device. Eliminating separate winding bodies also results in significant cost advantages and reduced production effort. The number of components required is comparatively small.

[0069] Due to the complete separation of the second coil 410 during data transmission, the described embodiment is also characterized by a very high signal-to-noise ratio. A placement in close proximity to an electric motor E in the drive unit A is therefore uncritical. The use of an LLC resonant circuit also results in low switching losses and feedback of the supply voltage of the bottom bracket-side measuring electronics, so that the power consumption of the measuring device during operation is very low.

[0070] In addition, the enabled bidirectional communication between the microcontrollers pC1, pC2 allows for the easy detection of disturbed or faulty data transmissions using a CRC check value.

[0071] The illustrated embodiment focuses on use in a drive unit A for an electric bicycle 1, and in particular on communication between a first circuit board 3 fixed to the housing and a second circuit board 4 located on the bottom bracket shaft. However, the illustrated solution with an LLC resonant circuit is also suitable for other applications, in particular when power levels of less than 100 mW must be transmitted to rotating electronics and the circuit boards 3, 4 provided for this purpose can be arranged at a maximum distance of 3 mm from one another. Furthermore, the described solution is also generally considered advantageous in the case of high electromagnetic loads, such as when located close to one or more converters and one or more motors.

[0072] List of reference symbols

[0073] 1 electric bike

[0074] 10 (bicycle) frames

[0075] 11 Front wheel

[0076] 12 rear wheel

[0077] 13 Belts I Chain

[0078] 14 Wheel sensor

[0079] 15 Sensor device

[0080] 2 Control panel

[0081] 4 Second, shaft-side circuit board

[0082] 40 Top with measuring electronics as well as transmitting and

[0083] Receiving electronics

[0084] 41 Bottom with second coil

[0085] 410 Second coil

[0086] 3 First, housing-side circuit board

[0087] 31 Top with first coil

[0088] 310 first coil

[0089] 32 circuit board sections with transmitting and receiving electronics

[0090] A drive unit

[0091] AT bottom bracket spindle

[0092] DU decoding unit d3, d4 data signal

[0093] E electric motor e energy

[0094] EN Energy storage

[0095] G Housing part

[0096] GE gear unit

[0097] LDU measuring and decoding unit

[0098] LLC LLC Converter

[0099] O Warehouse opening

[0100] R1 request signal

[0101] R2 response signal

[0102] RF rectifiers and voltage doublers

[0103] Sc communication signal

[0104] SE control electronics sf 1 - sf7 signal sequence / SG strain gauge

[0105] Sv supply voltage

[0106] SW switching element pC1, pC2 microcontroller (processor unit)

Claims

Claims 1. A device for energy and data transmission between a first, stationary circuit board (3) and a second circuit board (4) rotatable relative to the first circuit board (4), characterized in that the first circuit board (3) comprises at least one first coil (310) and the second circuit board (4) comprises at least one second coil (410) inductively coupled to the first coil (310), wherein the first and second coils (310 and 410) are part of a resonant circuit, and a first processor unit (pC1) of the device, associated with the first circuit board (3), is provided to transmit first data (da) to a second processor unit (pC2) of the device, associated with the second circuit board (4), by changing an excitation of the resonant circuit, and the second processor unit (pC2) is provided,to change a current consumption of the resonant circuit by electronically separating an electrical connection to the second coil (410) and to transmit second data (d4) to the first processor unit (pC1) via this.

2. Device according to claim 1, characterized in that the first processor unit (pC1) is provided to temporarily interrupt the excitation of the resonant circuit in order to generate a changing voltage signal at the second coil (410), and the second processor unit (pC2) is provided to derive the first data (da) from the changing voltage signal.

3. Device according to claim 2, characterized in that the first processor unit (pC1) is provided to transmit different first data over different durations of an interruption and / or different time sequences during successive temporary interruptions.

4. Device according to claim 3, characterized in that the duration of an interruption by the first processor unit (pC1) of the fixed first printed circuit board (3) is controllable in order to transmit first data with mutually distinguishable information content to the second processor unit (pC2).

5. Device according to claim 3 or 4, characterized in that the temporal sequence of successive temporary interruptions is controllable by the first processor unit (pC1) of the fixed first printed circuit board (3) in order to transmit first data with mutually distinguishable information content to the second processor unit (pC2).

6. Device according to one of the preceding claims, characterized in that the second processor unit (pC2) is provided to disconnect the electrical connection to the second coil (410) in pulses, and the first processor unit (pC1) to derive the second data (da) via changes in the current consumption of the resonant circuit resulting therefrom.

7. Device according to claim 6, characterized in that the second processor unit (pC2) is provided to transmit second data with mutually distinguishable information content to the first processor unit (pC1) via different time sequences during successive pulse-wise separations of the electrical connection to the second coil (410).

8. Device according to claim 7, characterized in that the first processor unit (pC1) is configured to interpret successive measurable drops in the current consumption of the resonant circuit as signal pulses, so that second data (d4) with distinguishable information content can be transmitted to the first processor unit (pC1) via different sequences of signal pulses.

9. Device according to one of the preceding claims, characterized in that the second processor unit (pC2) is provided to transmit with the second data (d4) at least one measured value for at least one component (AT) having the second circuit board (4).

10. Device according to claim 9, characterized in that the second circuit board (4) has at least one measuring element (SG) for detecting the at least one measured value.

11. Device according to claim 10, characterized in that the at least one measuring element comprises at least one strain gauge (SG).

12. Device according to claim 10 or 11, characterized in that the at least one measuring element (SG) is part of a torque sensor or is designed as a torque sensor.

13. Device according to one of the preceding claims, characterized in that the inductive coupling of the first and second coils (310, 410) is provided for the transmission of electrical energy for operating the second processor unit (pC2) to the second circuit board (4).

14. Device according to one of the preceding claims, characterized in that the first data (da) and / or the second data (d4) contain a check value for a cyclic redundancy check.

15. Device according to one of the preceding claims, characterized in that the first and second circuit boards (3, 4) are arranged at a distance of maximum 3 mm from one another.

16. Device according to one of the preceding claims, characterized in that the windings of the first coil (310) on the first circuit board (310) extend around an opening in the first circuit board (3) and / or the windings of the second coil (410) on the second circuit board (410) extend around an opening in the second circuit board (4).

17. Drive unit for an electric bicycle (1), with a device according to one of the preceding claims, wherein the first circuit board (3) is fixed to a housing part (G) of the drive unit (A) and the second circuit board (4) is fixed to a rotatable bottom bracket shaft (AT) of the drive unit (A).

18. Electric bicycle with a drive unit according to claim 17.

19. Method of transferring data between a first, fixed circuit board (3) and a second circuit board (4) rotatable relative to the first circuit board (3), characterized in that the first circuit board (3) has at least one first coil (310) and the second circuit board (4) comprise at least one second coil (410) which can be inductively coupled to the first coil (310), wherein the first and second coils (310, 410) are part of a resonant circuit and by changing an excitation of the resonant circuit, first data (da) are transmitted to a second processor unit (pC2) associated with the second circuit board (4) and by separating an electrical connection to the second coil (410), the current consumption of the resonant circuit is changed and second data (d4) are transmitted via this to a first processor unit (pC1) assigned to the first printed circuit board (3).

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