Electrically powered vehicle with a frame and a cable duct

Abstract

An electrically powered vehicle (10), in particular an electric bicycle (12), with a frame (18) in which an electronic unit (32) and at least one drive wheel (20) spaced apart from the electronic unit (32) are accommodated, wherein a motor unit (30) with an electric motor (38) is provided in a hub (28) of the at least one drive wheel (20), which is electrically supplied with energy and / or controllable or regulated by the electronic unit (32) via a cable connection (40) for the purpose of driving the vehicle (10), characterized in that a tubular cable channel (78) is provided on the frame (18) between the motor unit (30) and the electronic unit (32) for the purpose of suppressing electromagnetic, in particular high-frequency, interference, which at least partially encloses the cable connection (40) and which galvanically connects a housing (80) of the electric motor (38) with a housing (82) of the electronic unit (32).

Description

[0001] The invention relates to an electrically powered vehicle, in particular an electric bicycle, with a frame in which an electronics unit and at least one drive wheel spaced apart from the electronics unit are accommodated. A motor unit with an electric motor is provided in a hub of the at least one drive wheel. The motor serves to propel the vehicle and is electrically supplied with energy by the electronics unit via a cable connection and / or is controllable or adjustable. State of the art

[0002] Electric bicycles, also known as pedelecs or e-bikes, are already known. These bicycles have a frame that typically houses an electronics unit containing power electronics, which control an electric motor to propel the bicycle using pulsed switching signals. If the power electronics unit is located separately from the motor unit containing the electric motor, the high-frequency switching signals are usually transmitted from the power electronics unit to the motor unit via a cable connection. Such an arrangement can often lead to unwanted electromagnetic interference, while simultaneously being particularly susceptible to such interference, as longer cable connections between the electronics unit and the motor unit act like an antenna, radiating or receiving this interference.

[0003] To comply with legal limits for electromagnetic compatibility (EMC), various measures are employed in the state of the art. A common solution is the use of a shielded cable connection. Such a cable shield encloses the current-carrying conductors and dissipates interference currents. While this solution is effective, it increases the cost and weight of the cable connection. For cost reasons, many mass-produced products therefore forgo such shielding. This necessitates artificially slowing down the switching speeds of the power semiconductors in the electronic unit to limit interference radiation. However, slower switching speeds lead to increased switching losses and reduced overall system efficiency.

[0004] The invention is therefore based on the objective of reducing the sensitivity to electromagnetic interference in an electrically driven vehicle of the type mentioned above in a cost-effective and efficient manner, so that faster switching speeds in the electronic unit and thus higher system efficiency are made possible without having to resort to an expensive, shielded cable connection. Advantages of the invention

[0005] To solve the problem, it is provided that a tubular cable channel is provided on the frame between the motor unit and the electronics unit to suppress electromagnetic, in particular high-frequency, interference, which encloses the cable connection at least partially and galvanically connects a housing of the electric motor with a housing of the electronics unit.

[0006] This design feature creates an effective shielding structure. The tubular cable duct acts as a waveguide, attenuating high-frequency interference fields emanating from or acting upon the cable connection. The galvanic connection between the cable duct and the housings of the motor unit and the electronics unit ensures a defined potential reference and a closed path for the high-frequency interference currents. These currents are thus diverted and can no longer be radiated or received via the cable connection. In this context, a galvanic connection is understood to be an electrical connection that essentially creates a common electrical potential, particularly a ground potential, for all interconnected components.The term "essentially" further implies that potential differences in the millivolt range may occur due to minor ohmic losses in the cable connection. A significant technical advantage of this solution is that a separate, shielded, and therefore expensive motor cable is no longer necessary. Instead, a simple, preferably unshielded, cable duct, which ideally also serves to mechanically guide and protect the cable on the frame, can perform this electrical function. Simultaneously, the improved interference suppression allows the use of power semiconductors with higher switching speeds in the electronic unit. This reduces switching losses, increases the efficiency of the drive system, and thus improves the vehicle's range.

[0007] The electrically powered vehicle is preferably designed as an electric bicycle (e.g., EPAC - Electrically Power Assisted Cycle, e-bike, pedelec, e-cargo bike, etc.), an electric motorcycle, a one- or two-wheeled e-scooter, an e-moped, or the like. The invention is also applicable to other areas of micromobility applications, such as e-kick scooters, monowheels, or other non-type-approved vehicles with energy storage units permanently or interchangeably installed in the vehicle. An electrically powered vehicle is therefore also understood to be a vehicle that has a drive unit to assist the rider or an electric motor partial drive. The energy storage unit can be permanently integrated into the electrically powered vehicle or designed as a tool-free removable battery pack.In the case of a swappable battery pack, it can also be provided that it can be charged both when connected to and disconnected from the electric vehicle. The energy storage unit comprises a plurality of electrochemical energy storage cells connected in series and / or parallel to achieve a required battery voltage or capacity. The battery voltage of the energy storage unit is generally a multiple of the voltage of a single energy storage cell within the unit and results from the connection (parallel and / or series) of the individual energy storage cells. Preferably, the energy storage cells are lithium-based, e.g., Li-ion, Li-polymer, Li-metal, Na-ion, or the like.For common Li-ion energy storage cells with a cell voltage of 3.6 V, nominal battery voltages of 3.6 V, 18 V, 36 V, 54 V, etc., are possible. Furthermore, the invention is not dependent on the type and design of the energy storage unit used, the energy storage cells used therein, the motor unit, the electronic unit, or the frame of the electric vehicle.

[0008] In a further advantageous embodiment, the cable duct is made of an electrically conductive material. The use of an electrically conductive material for the cable duct ensures an effective and reliable low-resistance connection between the electric motor housing and the electronic unit housing. This maximizes the effectiveness of the shielding, as high-frequency interference currents can be dissipated via the low-resistance cable duct, resulting in improved suppression of electromagnetic interference.

[0009] Preferably, the electrically conductive material consists of carbon fibers, in particular a carbon fiber composite. The use of carbon fibers offers the advantage that, in addition to its good electrical conductivity, this material also exhibits high mechanical strength at a very low weight. Furthermore, carbon fiber composites show particularly good damping properties for high-frequency interference, similar to a ferrite, which further improves the shielding effect and reduces the overall weight of the vehicle.

[0010] Alternatively, the electrically conductive material can be a metal, in particular copper, aluminum, or steel. The use of such metals represents a particularly robust solution. Furthermore, they ensure a very good low-resistance connection and thus enable highly effective dissipation of interference currents.

[0011] In another embodiment, the cable duct is cylindrical with a substantially round or polygonal cross-section. Depending on the frame design, a corresponding cross-section of the cable duct allows for simple and cost-effective manufacturing. These standard geometries facilitate mounting on the frame and simultaneously provide sufficient space for the secure installation of the cable connection.

[0012] A particularly advantageous embodiment involves integrating the cable channel into the frame. Integrating the cable channel directly into the frame structure—for example, into a downtube or chainstay in the case of a motor unit located in the rear wheel hub—results in a particularly elegant and protected cable routing. No additional components are required, which reduces manufacturing costs, improves aerodynamics, and increases system reliability, as the cable and channel are protected from external mechanical influences.

[0013] Alternatively, the cable duct can be attached to the frame. Attaching the cable duct as a separate component to the frame allows for greater design flexibility and is particularly suitable for retrofitting existing vehicle designs. This modular design makes it easy to install the cable duct on different frame geometries and replace it as needed.

[0014] Finally, in a preferred embodiment, the drive wheel is the rear wheel of an electric bicycle. Application to an electric bicycle with a hub motor in the rear wheel is particularly advantageous, as the distance between the electronic unit, often located in the area of ​​the bottom bracket or on the down tube, and the motor unit is typically large. The long cable connection along the chainstay is particularly susceptible to interference, which is why the solution according to the invention can be especially effective in suppressing interference in this case. Likewise, the invention can also be applied to a hub motor in the front wheel of an electric bicycle, with the cable channel then running along or within a stay of a front fork. Examples of implementation Drawing

[0015] The invention is described below with reference to the Fig. 1, Fig. 2 to Fig. 3. This is explained by way of example, where identical reference symbols in the figures indicate identical components with the same function.

[0016] They show Fig. 1: a schematic representation of an electrically powered vehicle designed as a two-wheeled electric bicycle, Fig. 2: a block diagram for the energy supply of a drive unit of the electric bicycle according to Fig. 1 and Fig. 3: a schematic view of the drive unit comprising an electronic unit and a motor unit, as well as an electrical connection according to the invention between the electronic unit and the motor unit. Description of the exemplary implementations

[0017] In Fig. Figure 1 is a schematic representation of an electrically powered vehicle 10, designed as a two-wheeled electric bicycle 12. The electric bicycle 12 is supplied with energy via an energy storage unit 16 designed as a replaceable battery pack 14 and can be, for example, a pedelec, an e-bike, or the like. The electric bicycle 12 has a predominantly hollow cylindrical frame 18 with two wheels 20 mounted in the frame 18. The replaceable battery pack 14 is detachably connected via a connecting device 22 provided on the frame 18, which interacts electromechanically with an interface (not shown) attached to an outer housing 24 of the replaceable battery pack 14. Alternatively, the electric bicycle 12 can also be designed as a unicycle with only a single drive wheel 20 or as a tricycle with two rear wheels 20 arranged on a rear axle.

[0018] The electric bicycle 12 has a drive unit 26, supplied with energy via the interchangeable battery pack 14, comprising a motor unit 30 arranged in a rear wheel hub 28 of the rear wheel 20 and an electronics unit 32 located at a distance from it and arranged in the frame 18. The rear wheel hub 28 is mounted at a connection point between a fork-shaped lower stay 34 and a fork-shaped seat stay 36 of the frame 18. The electronics unit 32 is designed to control an electric motor 38 of the motor unit 30 via a multi-core cable connection 40 such that a rider of the electric bicycle 12 receives pedal assistance. Preferably, the electronics unit 32 is designed to be controllable by the rider so that the rider can adjust the level of assistance. The electric motor 38 is preferably a three-phase, electrically commutated (EC) motor.The electric bicycle 12 is equipped with a brushless (BLDC) direct current motor, which is controlled by pulse-width modulation (PWM) by a power electronics unit 42 of the electronics unit 32. The electronics unit 32 includes control electronics 44 for controlling the electric bicycle 12, in particular the electric motor 38, by means of the power electronics unit 42. The electric bicycle 12 also features a crankset 46 with a crank axle 48 and a chainring assembly 50, via which the rider can perform a pedaling motion to drive the rear wheel 20 in the manner of a conventional bicycle drive.

[0019] The pedaling motion of the crank 46 is transmitted via the chainring assembly 50 and a chain 52 to the electric motor 38 of the motor unit 30, which is located in the rear wheel hub 28 of the rear wheel 20. Using a derailleur 54 and a cassette (not shown) located on the rear wheel hub 28, the rider can select different gears depending on the desired speed and / or gradient. The intensity of the assistance provided by the drive unit 26 can be controlled or regulated by the electronic unit 32. For this purpose, the control electronics 44 of the electronic unit 32 are preferably connected to a cadence sensor 56 for measuring the pedaling frequency of the crank 46 or the crank axle 48 and a speed sensor 58 for determining the rotational speed of the rear wheel 20.Alternatively or additionally, a torque sensor for measuring the torque of the crank axle 48 and / or the electric motor 38 and / or a bearing force sensor for measuring a force acting on a bearing of the crank axle 48 and / or the electric motor 38 can be provided. Instead of the derailleur 54 and the cassette, a motor unit 30 with an integrated planetary gear in the rear wheel hub 28 can also be used.

[0020] An on-board computer 62 is arranged on the handlebar 60 of the electric bicycle 12. The on-board computer 62 can be detachably connected to the handlebar 60 and has a human-machine interface (HMI) for displaying information and controlling the drive unit 26 of the electric bicycle 12 in the manner described above. The HMI is preferably designed as a touchscreen or the like. Alternatively or additionally, the on-board computer 62 may also have hardware buttons (not shown) for operation. The on-board computer 62 is preferably connected to the drive unit 26 via a bus system 64, comprising the cable connection 40, for exchanging information and commands.For example, the HMI can display and / or adjust the speed of the electric bicycle 12 (determined via the speed sensor 58 and / or a GPS sensor), the selected level of assistance of the electric motor 38, the selected gear ratio between a sprocket of the chainring set 50 and a pinion of the cassette, route information from a navigation unit integrated into the on-board computer 62, the charge level of the removable battery pack 14, or similar information. This list is intended to be exemplary and not exhaustive. It should be noted that the cable connection 40 between the motor unit 30 and the electronic unit 32, as well as the bus system 64, are shown only schematically and as examples. They are intended to indicate the electrical connections and should therefore not be interpreted as limiting.

[0021] In Fig. 2 is a simplified block diagram for the power supply of the electric bicycle 12 according to Fig. 1 integrated drive unit 26 via the energy storage unit 16 with the battery voltage U Batt As previously described, the electronics unit 32 of the drive unit 26 comprises the control electronics 44, the power electronics 42, and an intermediate circuit electronics 66. The power electronics 42 are used to adjust a rotational speed n and / or a torque T. q a rotor 68 of the electric motor 38 is controlled via the control electronics 44 and the bus system 64 in such a way that a pulse width modulated motor voltage signal U generated by it MThe three phases U, V, W of a stator winding 72 wound on a stator or stator core 70 set the rotor 68, which is rigidly connected to a motor shaft 74 and equipped with permanent magnets, into a rotational movement. A gearbox (not shown) of the drive unit 26 for assisting the movement of the electric bicycle 12 is driven via the motor shaft 74. The motor unit 30 also includes a sensor unit 76 for determining the speed, torque, and / or position of the rotor 68, which provides a corresponding sensor signal S via the bus system 64 or the cable connection 40 for the control electronics 44. The invention is not explicitly limited to three-phase, brushless DC motors 38, but can also be applied to other types of electric motors 38, such as synchronous motors or universal motors.

[0022] The battery voltage U is determined by means of the intermediate circuit electronics 66. Battinto an intermediate circuit voltage U IC converted, which in the case of the electric bicycle 12 is typically between 20 and 60 VDC. The intermediate circuit electronics 66 are connected via the bus system 64 to the control unit 44 such that, firstly, the discharge current I of the energy storage unit 16 is detected and, secondly, its maximum value I max and a maximum engine torque T q,max are predeterminable. By means of an inverter circuit of the downstream power electronics 42, which can be implemented, for example, as an H- or B6-bridge, the intermediate circuit voltage U is IC into the pulse-width modulated motor voltage U M for controlling the electric motor 38 via the cable connection 40, wherein the control or regulating unit 44 is used via the bus system 64 to vary the motor speed n and / or the motor torque T qa corresponding duty cycle is specified. The discharge current I of the energy storage unit 16 is typically approximately 20 to 25 A and can briefly reach a maximum value I max up to 40 A. Additionally, the sensor unit 76 can also include a temperature sensor, for example in the form of an NTC, for measuring the motor temperature of the electric motor 38.

[0023] Fig. Figure 3 shows a schematic view of the drive unit 26 of the electric bicycle 12, comprising the electronic unit 32 and the motor unit 30, as well as the cable connection 40 between the electronic unit 32 and the motor unit 30 for controlling the electric motor 38 in the manner described above. The cable connection 40 includes corresponding conductors for transmitting the pulse-width modulated motor voltage U generated by the power electronics 42. M or the motor currents I V , I W , I Vfor the motor phases U, V, W of the electric motor 38 and for transmitting the sensor signal S from the sensor unit 76 to the control electronics 44. Furthermore, the cable connection 40 can have additional conductors for supplying power to the sensor unit 76 and / or for transmitting a temperature signal from the motor unit 30 measured by means of a temperature-dependent resistor. To suppress any electromagnetic, in particular high-frequency, interference, according to the invention, a [missing information] is provided on the frame 18 (in Fig. 3 is not explicitly shown for the sake of clarity; see also Fig. (Referring to Figure 1) a tubular cable channel 78 is provided between the motor unit 30 and the electronics unit 32. This channel encloses the cable connection 40 and galvanically connects a housing 80 of the electric motor 38 to a housing 82 of the electronics unit 32. This improves the performance and efficiency of the electric motor 38, as the reduced electromagnetic emissions allow for shorter switching times of any power transistors in the power electronics 42 used to control the electric motor 38. This enables shorter and faster PWM switching cycles with correspondingly higher switching frequencies. Furthermore, improved shielding against electromagnetic interference enhances the signal quality of the transmitted signals.The tubular cable duct 78 is essentially cylindrical with a round or polygonal cross-section and consists of an electrically conductive material that is galvanically connected to the housings 80, 82 via corresponding conductors 84. These connections can be implemented, for example, by soldering, screwing, or cold welding. Preferably, the electrically conductive material of the cable duct 78 consists of carbon fibers, in particular a carbon fiber composite. However, metals such as copper, aluminum, or steel are also conceivable. The cable duct 78 is attached to the frame 18 by means of appropriate fastening or fixing devices, such as clamps, a tongue-and-groove system, screws, or the like.If the frame 18 itself is electrically conductive, the additional lines 84 for the electrical connection of the cable duct 78 to the housings 80, 82 of the motor unit 30 and the electronic unit 32, which are connected to the frame 18, for example, by screws, can be omitted, since the electrical connection then takes place directly via the frame 18. Alternatively, the cable duct 78 can also be integrated directly into the frame 18, as shown in . Fig. 1 is indicated. It should also be mentioned that the cable channel 78 can be provided in a front drive of the electric bicycle 12 with a motor unit 30 integrated in a hub of the front wheel 20 or in a front fork 86 that functionally belongs to the frame 18.

[0024] Finally, it should be noted that the illustrated embodiment does not refer to the Fig. 1, Fig. 2 to Fig.3 is still limited to the shapes, arrangements and size ratios of the individual components shown therein.

Claims

[1] Electrically powered vehicle (10), in particular electric bicycle (12), with a frame (18) in which an electronic unit (32) and at least one drive wheel (20) spaced apart from the electronic unit (32) are accommodated, wherein a motor unit (30) with an electric motor (38) is provided in a hub (28) of the at least one drive wheel (20), which is electrically supplied with energy and / or controllable or regulating from the electronic unit (32) via a cable connection (40) for the purpose of driving the vehicle (10), characterized by , that a tubular cable channel (78) is provided on the frame (18) between the motor unit (30) and the electronic unit (32) to suppress electromagnetic, in particular high-frequency, disturbances, which at least partially encloses the cable connection (40) and galvanically connects a housing (80) of the electric motor (38) with a housing (82) of the electronic unit (32). [2] Electrically powered vehicle (10) according to claim 1, characterized by , that the cable duct (78) is made of an electrically conductive material. [3] Electrically powered vehicle (10) according to claim 2, characterized by that the electrically conductive material consists of carbon fibers, in particular a carbon fiber composite material. [4] Electrically powered vehicle (10) according to claim 2, characterized by that the electrically conductive material is a metal, especially copper, aluminum or steel. [5] Electrically powered vehicle (10) according to any one of the preceding claims, characterized by , that the cable duct (78) is cylindrical with a substantially round or polygonal cross-section. [6] Electrically powered vehicle (10) according to any one of the preceding claims, characterized by , that the cable duct (78) is integrated into the frame (18). [7] Electrically powered vehicle (10) according to any one of the preceding claims 1 to 5, characterized by , that the electronic unit (32), the motor unit (30) and the cable duct (78) are attached to the frame (18) in such a way that they are galvanically connected to each other via the frame (18). [8] Electrically powered vehicle (10) according to any one of the preceding claims, characterized by , that the drive wheel (20) is a rear wheel (20) of an electric bicycle (12).

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