Drive arrangement for an e-bike

Abstract

The present invention relates to an electric drive arrangement, in particular for an e-bike. An inner part of the electric drive comprises a sensor, and a measurement element which can be coupled to a freewheel. The measurement element is arranged in the region of an axle of a running wheel and the sensor performs a function which measures drive support. Furthermore, the inner part of the electric drive is protected against external unwanted influences by a housing consisting of two cover bodies. This housing is screwed to a running wheel of the e-bike by means of a support element. The radial movement of the axle is ensured by two bearings. The electric drive is connected, as a complete component, to the pedals of the e-bike via a belt or chain by way of a freewheel.

Description

[0001] Drive arrangement for e-bike

[0002] The present invention relates to an electric drive with a sensor according to the preamble of patent claim 1.

[0003] Technological background

[0004] Two basic approaches to electric drive systems are known from the current state of the art. These can be mounted as a hub motor in the front or rear wheel, or as a mid-drive motor on the chain in the middle of a bicycle. Drive systems are further divided into direct drive motors and geared motors. The main difference between these two categories is that, unlike direct drive motors, geared motors have a gearbox and usually do not have a freewheel.

[0005] Electric bikes are typically equipped with either a torque or cadence sensor, which determines the rider's pedaling assistance. While cadence sensors measure whether a rider is pedaling, torque sensors measure how hard the rider is pedaling. The fundamental difference in drive control is that with a cadence sensor, the drive assistance decreases as the rider's pedaling speed increases. With electric bikes equipped with a torque sensor, the behavior is reversed: the harder the pedals are pedaled, the more torque and therefore more power the electric motor delivers. This means that riding with assistance determined by the torque sensor offers a more natural and intuitive riding experience than when using the cadence sensor.

[0006] There are documents in the state of the art that deal with torque measurement in electric drives using a torque transducer.

[0007] EP3029442A1 discloses a freewheel hub used to measure the torque applied to a bicycle wheel. It comprises a rotating hub shell attached to the wheel and a torque-transmitting element (e.g., a shaft) connected to the hub shell. The element has one or more magnetoelastic active regions that change their magnetic polarization in response to the applied torque. A magnetoelastic sensor equipped with magnetic field sensors and attached to a non-rotating axle detects the changes in the magnetic flux in these active regions to determine the torque. The hub can incorporate features such as a one-way clutch or a freewheel, with the sensors mounted in a hollow shaft for improved torque measurement accuracy.It is capable of compensating for external magnetic disturbances and is constructed of materials that enhance its magnetoelastic properties. Nevertheless, this technical solution has certain disadvantages, such as increased system complexity. The integration of multiple magnetoelastic active areas, sensors, and associated electronics can make system design and maintenance more complex and costly. Furthermore, the freewheel is not directly or exclusively coupled to the torque sensor, resulting in only indirect torque measurement. This indirect measurement could lead to delays or inaccuracies.

[0008] DE102021126910A1 describes a bicycle motor with a wheel axle, a hub shell, and a housing cover containing several through holes for the wheel axle and fastening elements. A driver absorbs the torque and transmits it via pins to a measuring disc located inside the motor. This disc transfers the torque to the hub shell, and its deformation is recorded by a torque measuring device to determine the applied torque. A disadvantage of this solution is the two-part design of the wheel axle, which represents a potential weak point in the mechanical structure, as the wheel axle is subjected to higher forces at each end, leading to an increased risk of wheel axle misalignment.

[0009] According to the state of the art, a torque sensor is mounted on the axle in conjunction with the electric drive positioned on the axle. This brings with it several disadvantages. A torque sensor located outside the electric drive is more susceptible to damage. Furthermore, the measured signal is more dynamic, as other influences determine the signal, which places greater demands on the evaluation. Last but not least, placing the torque sensor on the axle is not a compact solution, which can, for example, complicate the replacement of a brake disc. Description of the invention

[0010] One object of the invention is to avoid at least one of the disadvantages of the prior art. In particular, one object of the invention is to reliably measure the torque using a sensor, thereby enabling safe and comfortable riding of the e-bike.

[0011] It is further an object of the invention to provide a complex electric drive solution, wherein the electric drive is designed with a sensor as an overall component of the electric bicycle.

[0012] These objects are achieved by the features of independent patent claim 1.

[0013] The solution allows for better protection of the sensor from external influences and also offers a more compact appearance of the bike, which facilitates the assembly or disassembly of the components mounted around an axle.

[0014] In particular, the objects underlying the invention are achieved by an electric drive arrangement according to the invention.

[0015] The inventive solution comprises an electric drive, in particular for an e-bike, comprising a housing with two cover bodies. An axle guided through the two cover bodies, as well as at least one bearing and a support with a bearing seat, are also part of the design. Furthermore, the disclosure includes a sensor arranged in the region of the axle of a wheel to measure drive assistance, as well as a measuring element that can be coupled to a freewheel by means of a connection pattern. A transmitted force at the measuring element can be detected by the sensor. Furthermore, the at least one bearing can be placed on an outer surface of the bearing seat.

[0016] The described technical solution for an electric drive, specifically for an e-bike, offers several advantages that can improve the system's performance, reliability, and maintainability. The two-cover design simplifies the assembly and disassembly of the electric drive. This is particularly advantageous for maintenance work or component replacement, as the housing can be easily opened to access internal parts such as the axle, bearings, and carrier.

[0017] In addition, the integration of a torque sensor, which measures the force acting on the measuring element, allows for an exact determination of the required support from the electric drive that should be provided to the e-bike.

[0018] The way the bearing is mounted on the outer surface of the bearing seat also represents a significant advantage. Traditional designs tend to position the bearing around the axle, which, while functional, can lead to uneven loading and increased wear. By mounting the bearing on the bearing seat instead, a more even force distribution is achieved. To further increase force distribution, a second bearing can be advantageously integrated into the electric drive design.

[0019] Finally, the connection pattern is advantageously a toothed connection. The toothed connection enables high precision in power transmission, as the interlocking teeth ensure a stable and non-slip connection. Furthermore, the toothed connection offers improved durability and longevity, as the load is distributed more evenly across the contact surfaces, minimizing wear.

[0020] However, other connection technologies, such as threads or magnetic couplings, can also be used. Magnetic couplings offer the advantage of contactless power transmission, which reduces mechanical wear and can extend the service life of components.

[0021] The solution according to the invention can be supplemented and further improved as desired by the following additional, each advantageous embodiment.

[0022] According to one embodiment, it is provided that the sensor is positioned together with the measuring element in a housing of the electric drive.

[0023] By positioning the sensor together with the measuring element within the electric drive housing, a high degree of integration is achieved. This approach protects the critical sensor elements from external influences such as dust, water, and mechanical stress, improving the reliability and longevity of the sensor. Furthermore, the internal arrangement helps maintain functionality under harsh operating conditions and ensures consistent performance throughout the entire service life of the electric drive.

[0024] The proximity of the sensor to the measuring element within the protected housing also minimizes potential interference and signal loss that can occur with longer transmission paths. This ensures high signal integrity and enables more precise and reliable measurement data acquisition, which is important for fine-tuning the drive assistance and improving the overall performance of the electric drive.

[0025] According to a preferred embodiment, the measuring element is motor-integrated and has the shape of a sleeve.

[0026] The sleeve-shaped design of the measuring element allows for uncomplicated mounting around the impeller's axis. This concept ensures simplified installation and enables seamless integration with other drive system components, for example, through the use of a threaded mechanism for precise and secure coupling. This significantly increases the efficiency of the assembly process, resulting in reduced production times and costs.

[0027] Furthermore, the measuring element is advantageously made of a material of exceptional strength, which promotes the accuracy and repeatability of measurements. The use of high-strength material minimizes deformation under load, ensuring consistent measurement accuracy throughout the product's lifetime.

[0028] Finally, the sleeve-shaped construction is designed to be resistant to external disturbances such as vibrations, temperature fluctuations, and other physical influences. This resilience ensures that such influences do not affect measurement accuracy, improving the reliability and stability of the sensor data under varying operating conditions.

[0029] According to a further embodiment, the measuring element is magnetized. The magnetization of the measuring element enables contactless measurement. This represents a significant advance, as the elimination of mechanical contact points drastically reduces susceptibility to wear. The longevity of the measuring element and the reliability of the measurement are thereby significantly improved. Furthermore, this configuration minimizes the need for direct physical interactions between the measuring element and other components of the drive system, reducing potential interference and sources of error during measurement.

[0030] A further advantage of magnetization is that measurements are possible from a greater distance. This allows for flexible positioning of the measuring element relative to the sensor detection units, which increases design freedom and enables adaptation to different designs and requirements of the electric drive system.

[0031] Finally, selecting a suitable material for the magnetized measuring element is essential. Using an NdFeB alloy (neodymium-iron-boron) is advantageous due to its strong magnetic properties and high energy density. This material enables the generation of a stable magnetic field for precise, contactless measurements. NdFeB also offers good corrosion resistance and temperature resistance, ensuring the reliability of the measuring element under various operating conditions.

[0032] According to a further embodiment, it is provided that the two cover bodies are coupled to spokes of the wheel by a spoke connection.

[0033] The spoke connection design is advantageous because it allows the wheel's spokes to be easily connected to the shell. They remain straight and require no bending in the spoke connection. Therefore, it can be argued that this solution also simplifies manufacturing. Furthermore, it makes the shell more stable, as the spoke connection acts as an additional support structure. Another advantage is that the shell has a uniform shape, which is easy to maintain and repair.

[0034] According to a further embodiment, the housing can be coupled to the wheel by a support element. The support element is firmly connected to the housing and the wheel, for example, by screws. This ensures that the entire electric drive is firmly anchored in the wheel and cannot move. Furthermore, both the support element and the entire housing can be made of plastic or metal, for example. Last but not least, it is also advantageous for the housing to be attached directly to the wheel of the e-bike by one of the cover bodies and the support element.

[0035] According to a further embodiment, it is provided that the support element has a sleeve shape.

[0036] This design allows for easy connection to the housing. This can be achieved, for example, with screws. Additionally, the support element can have a number of additional features, such as a handle, a groove, a clip, or a similar component to facilitate handling of the housing. Furthermore, the support element can be made of a suitable material such as metal or plastic.

[0037] Furthermore, it is particularly advantageous if radial movement of the axle relative to the radially fixed housing is enabled by a first bearing A and a second bearing B. Bearings A and B ensure the transmission of a force acting on the axle from the axle to the electric drive, as they hold the electric drive in position while the axle and thus the impeller rotate. It is advantageous to place bearings A and B on or around the axle and to position the cover bodies on their outer sides. Furthermore, it is possible to use different types of bearings, such as ball, roller, or cylindrical bearings. Last but not least, regular inspection and lubrication are recommended to ensure their proper function.

[0038] According to a further embodiment, the sensor is provided on the carrier.

[0039] This ensures that the sensor cannot move freely along the axis. Without this fixation, measurement inaccuracies could occur, leading to incorrect determination of the electric drive assistance. Furthermore, even if only one screw is required for fixation, it is recommended to use at least two to achieve a more robust design. According to another embodiment, the force generated by pedaling is transmitted to the measuring element via the freewheel, also known as the overrunning clutch.

[0040] When a rider pedals, the power generated by this movement is transferred to the freewheel via a belt or chain, for example. The freewheel function and the connection between the belt / chain and the axle must be decoupled. This has the advantage that the pedals do not continue to rotate when cycling without pedaling.

[0041] According to a further embodiment, it is provided that a transmitting force can be measured on the measuring element.

[0042] As already mentioned, the measuring element is located inside the electric drive housing. This is advantageous not only for protection against external influences, but also for signal measurement. Because the force can be measured inside the housing, the signal corresponding to the force being measured is not as dynamic as if measured outside the housing. This makes the electric drive assistance easier and more accurate to determine.

[0043] According to a further embodiment, it is provided that the transmitted force in the form of a magnetic field strength can be detected by the sensor.

[0044] The change in magnetic field strength corresponds to the force with which a rider pedals. This determines how much assistance the electric drive should provide to the rider while pedaling. It is also advantageous if the axle is magnetized directly, allowing the magnetic field strength to be measured directly at the axle. This enables quick and precise recording of the pedaling force without the need for an additional measuring element.

[0045] According to a further embodiment, the sensor is designed as a force sensor and advantageously as a torque sensor.

[0046] The solution presented uses a sensor that measures the strength of the magnetic field, which is converted into torque. Based on this measurement and conversion, the degree of electric drive assistance is then determined. Measurement accuracy can be further improved by using special sensors, such as angle or speed sensors. The use of special software algorithms can also further increase accuracy and precision.

[0047] According to a further embodiment, the sensor is calibratable.

[0048] During sensor calibration, the sensor output is adjusted so that it matches the actual value of the parameter being measured. This calibration is essential for consistently correct and error-free sensor function, thus ensuring safe and comfortable driving. Furthermore, calibration is recommended at least every six months, but preferably every three months. It is advantageous to automate the calibration process using software that allows it to be performed continuously or regularly.

[0049] According to a further embodiment, it is provided that the coupling between the freewheel and the measuring element takes place directly or exclusively intermediately.

[0050] This solution offers significant advantages. Such couplings ensure precise power transmission from the wheel to the measuring element, which can increase the accuracy of the sensor. In the context of an e-bike, this enables more precise measurement of the drive assistance, potentially leading to optimized control of the electric drive. This can reduce energy consumption and increase the range of the e-bike.

[0051] Further embodiments are also possible. For example, the sensor can consist of at least two measuring discs, a torsion bar, and a measuring sleeve. The torsion bar is held to the carrier by at least one cylindrical pin, and the sensor is positioned as a complete component in the housing of the electric drive. The measuring sleeve is coupled to a bicycle belt or chain via the freewheel. Furthermore, both the measuring sleeve and the at least two measuring discs are magnetized. The intensity of the magnetic field measured between the at least two magnetized measuring discs can be evaluated by a Hall sensor. Furthermore, the measuring sleeve has a thread that transmits the measured force transmitted to the measuring sleeve to the electric drive. This force corresponds to the pedaling intensity of a rider.Within the electric drive system, it is also possible to measure not only the torque but also the speed of a bicycle using Hall sensors. The Hall sensors can be installed in the stator between the coils. In addition to the speed, they can also determine the direction of travel. The sensors detect the position of the rotor and measure the speed and direction. This information can then be transmitted to the electronic controller, which then releases or transmits the required current to the motor.

[0052] The maximum level of electric assistance, for example, can be adjusted in the following three steps. First, the e-bike's control unit should be checked and replaced if necessary. This control unit is the brain of the entire e-bike and connects all electronically controlled parts by supplying them with power. It also determines the maximum current that can be transferred from a battery to the electric motor. By replacing the control unit, the maximum current can potentially be changed. The second aspect that determines the maximum level of electric assistance is the battery. More specifically, the capacity of a battery management system, as this system determines the maximum current the battery can deliver.Even if the battery is replaced with one with a higher capacity, this does not automatically increase the level of electric assistance, as the maximum current allowed by the battery management system may remain the same or even be lower. The final step to increasing power and thus the maximum electric assistance delivered is to ensure that the electrical wiring of the electric drive is rated for the increased current. If this is not the case, a wiring upgrade is required.

[0053] To prevent riders from having to remember to perform regular calibration, it is particularly advantageous to automatically warn them via a message on the display when the e-bike is started. The rider can also be alerted to the need for calibration via a smartphone app connected to the e-bike's control unit. Using an application with an internet connection could also enable the exchange of calibration data, which would provide valuable data for optimizing the riding experience. To further increase safety, the e-bike's next ride can be made dependent on the sensor being calibrated. This means that the electric drive can only be switched on again after regular calibration. It is also possible to automate the sensor calibration process by automatically calibrating the sensor each time the electric drive is switched on. However, calibration takes some time.During this calibration phase, the power supply is turned off to ensure rider safety and allow for error-free calibration of the sensor. Furthermore, it is important that the rider does not pedal during the calibration phase.

[0054] The accuracy of the electric assistance level depends not only on the accuracy of the torque measurement by the sensor, but also on the condition of the electric drive. Condition in this sense refers, for example, to its temperature or the aging of the materials used, for example, for the stator windings. These parameters change over time or during on / off mode. However, the condition of the electric drive or its deviation from the optimal operating point is usually not taken into account, and optimal parameters such as new material or room temperature are assumed. However, this does not correspond to reality, and it is precisely these parameters that cause the power output of the electric motor to fluctuate. Therefore, it is possible to use a system that determines the actual operating point of the electric drive based on the input current and / or input voltage and the torque measured by a torque sensor.Such a feedback system would compensate for inaccuracies caused by the electric drive operating at a suboptimal operating point. As already mentioned, this could be due to material aging or increased temperature inside the electric drive. This would not only lead to a precise determination of the degree of electric assistance but also to energy savings by changing the electric drive's operating point.

[0055] The data obtained by the sensor, which primarily serves to determine the level of electric assistance required by a rider, can also be used for other purposes. For example, it is advantageous for this data to be linked to the rider's age and physical condition, or to the average terrain traveled by the rider. This would allow a more personalized selection of electric drive power and / or battery capacity for a potential buyer, based on the riding experience of other riders. As a result, the value for money would improve, as the potential buyer could choose a bike with parameters appropriate to their performance level and / or the terrain they ride in, or the average distance they intend to cover.It's also conceivable to list these recommendations online, where no qualified dealer is available, so that a potential buyer is warned that they're about to purchase an e-bike that may exceed their capabilities. This would also increase overall safety for both e-bike users and all other road users.

[0056] Torque measurement can be used to monitor the condition of the electric drivetrain. By tracking the torque acting on the drivetrain, the drivetrain can be monitored for signs of wear. This could help prevent failures and extend the drivetrain's lifespan. Furthermore, torque measurement can help calculate various electric motor parameters such as speed, power, efficiency, and power factor. Using these parameters, the motor's operating conditions can be monitored and optimized, leading to improved performance. It is also beneficial to use torque measurement to optimize the bicycle's algorithm.

[0057] It is also possible to integrate a sensor into a pedal to determine the level of electric drive assistance. A strain gauge, for example, could be used for this purpose. Additionally, it is also advantageous to use an accelerometer to measure the rotational speed of the pedal. The sensor can be calibrated to measure the strength and frequency of the force applied by a rider when pedaling. To ensure accurate measurement of the applied force, the sensor should be mounted in the center of the pedal and securely connected to the e-bike pedal. The sensor should then be connected to the battery and the electric motor so that its measurement can be used to determine the level of electric drive assistance a rider receives. Specifically, the analog signal from the strain gauge is converted into a readable digital signal via an amplifier.This signal can then be interpreted using a microprocessor, which is also programmed to determine the power the electric motor should deliver at each point of pedaling. A force sensor integrated into a pedal is a cost-effective solution that could be more accurate than a torque sensor integrated into the motor housing, as it measures the force closer to its source, namely the pedal. It's worth mentioning that the sensor should be well sealed to prevent water ingress and dust accumulation. Finally, the sensor should be connected or wired to the electric motor, battery, and control unit.

[0058] The data measured by the sensor can be used to detect when a rider loses traction and adjust power accordingly to help the rider maintain control of the e-bike. By using sensors that measure torque, the system can analyze the forces exerted by the rider on the pedals and determine when an increase in rider effort could indicate slipping or tire spin. If slipping is detected, the system can react by reducing the power output of the electric motor, allowing the rider to regain control. This system could be useful for novice riders who are new to adjusting the power output of their electric motor to maintain control.By adapting power output to changes in traction, the system can help the rider maintain control of the e-bike even in difficult conditions.

[0059] The performance of an electric motor should depend not only on the force with which a rider pedals, but also on the terrain they are on. By adapting the electric motor's power output to the specific terrain, the rider can better optimize the e-bike's performance. With a better understanding of the terrain and the correct torque measurements, the rider can enjoy a safer and more efficient ride. An e-bike drive system should take into account when the rider is riding on a dirt path, rough terrain, or mud, as these are diametrically different conditions for an e-bike than on a paved road. For this purpose, software can be used to determine the optimal motor power depending on a selected variety of different terrain.It's also beneficial for the driver to communicate their position so that the terrain they're traveling on can be identified. Then, with the help of the software, the drive system would already switch on the optimized mode suitable for the given terrain.

[0060] One of the features of an e-bike that can lead to inaccurate torque measurements is a poorly tensioned bicycle chain. For example, a poorly tensioned bicycle chain can cause uneven power transfer from a master link to a sprocket. Furthermore, such a bicycle chain increases friction between the chain components and leads to excessive wear on the e-bike. If the bicycle chain is too loose, the chain can wear out, impairing optimal performance. Conversely, if the bicycle chain is too tight, it increases the risk of breakage. Furthermore, unnecessary stress can be placed on the bolts or screws, which can also lead to inaccurate measurements. To correctly tension the bicycle chain, you must first check the upper and lower chain on the chainring and cassette.The upper chainring should be parallel to the side of the bike frame, while the lower chainring should be aligned with a slight incline toward the center of the chainring. Correct chain tension can be automatically checked using a torque sensor and a strain gauge. When the rider pedals with a certain force, measured by the strain gauge, this force should be transmitted to the wheel axle within a certain range—i.e., with a certain loss—which is then measured by the torque sensor. If these two readings are within a preset range, the chain tension is correct; otherwise, the rider can be alerted that the chain needs to be adjusted. This can also be done automatically using an automatic chain tensioner.

[0061] A torque sensor can be used to develop a brake-assist system. One possible solution is for the sensor to send information to a control unit, which then uses this information to determine how much braking force should be applied. The control unit could be configured to apply more braking force when a rider pedals harder, providing more assistance. This would help make braking more comfortable for the rider, as they wouldn't have to apply as much force to the brakes to achieve the desired braking effect. Furthermore, this system could also be used for smoother braking, which could be helpful for riders who are unaccustomed to riding an e-bike. The torque sensor can also be used to develop a driver assistance system.Here, the sensor could be used to capture information about the bicycle's torque. This information can then be passed on to a control unit, which is able to give specific instructions to the rider. For example, the control unit could prompt the rider to apply more torque if necessary to reach a certain speed. An optical sensor is an alternative to a sensor that measures the strength of the magnetic field and can be used to measure the force with which a cyclist pedals. For this purpose, an optical sensor is mounted around the bicycle axle. When an axle is subjected to torque, this results in a strain on the axle surface. The optical sensor can detect these surface movements, from which the torque can be calculated. Furthermore, such a sensor can also be used to determine a rider's cadence.This requires an additional light source directed at a static point on the axle. The sensor can then count the occurrence of this point per time window and thus determine the cadence.

[0062] One of the aspects that negatively impacts not only torque measurement but also motor performance is its heating within the drive housing. The heat generated by an electric motor can cause thermal expansion, which can lead to inaccurate torque measurements and suboptimal power output, as parts of the motor expand or contract at different rates. Furthermore, excessive heat can increase friction between moving parts, resulting in inaccurate torque readings and potentially damaging components. A rise in temperature within the electric drive also reduces its efficiency due to higher electrical resistance, resulting in lower power output. Furthermore, high temperatures can disrupt other electronic components used to measure torque values, exciting inaccurate readings.In extreme cases, high temperatures in the housing can cause the motor to overheat, rendering it inoperable. For these reasons, it is important that the housing or motor is cooled and that the optimal temperature is maintained. This can be achieved through the use of various cooling systems. For example, installing a fan inside the housing has the advantage of being inexpensive. The disadvantage, however, is low efficiency and the required power supply. Another option is heat sinks, which can passively cool the electric drive. These do not require power. On the other hand, their efficiency is not high enough to cool down high temperatures. Finally, a water cooling system can also be considered, which can cool the electric drive better than the other alternatives presented.However, it is a complex device that must be waterproof to avoid damaging the components inside the housing.

[0063] A key factor for a safe and comfortable ride is the proper functioning of all components, especially the electric drive, battery, and control unit with a display. To ensure good and improved communication between the battery and the electric drive, it is important to update the e-bike's software. To alert riders to an available update, either a message could be sent from an e-bike application or it would also be possible to regularly trigger a notification on an e-bike display that a software update is available. In addition, data could be collected on how often the e-bike is ridden, allowing personalized instructions to be given on when the bike should be serviced, for example to check the condition of the battery, sensors, and electric drive.Finally, such maintenance could also involve replacing mechanical parts such as the gears or freewheel if wear and tear affects the performance of the e-bike or riding safety.

[0064] It is self-evident to the person skilled in the art that all described embodiments can be implemented in an inventive embodiment of the present invention, provided they do not explicitly exclude each other.

[0065] In the following, the present invention will now be explained in more detail using specific embodiments and figures, without, however, being limited to these.

[0066] By studying these particular embodiments and figures, further advantageous embodiments of the present invention may become apparent to a person skilled in the art.

[0067] Character description

[0068] Embodiments of the invention are described with reference to the following figures, wherein like reference symbols designate like or similar parts.

[0069] Shown are: Fig. 1 : a schematic perspective view of an e-bike;

[0070] Fig. 2: a schematic perspective view of an electric drive;

[0071] Fig. 3: an exploded view of an electric drive;

[0072] Fig. 4A: a detailed exploded view of a first sensor;

[0073] Fig. 4B: a detailed exploded view of a second sensor; and

[0074] Fig. 5: a schematic diagram of a torque signal measured inside and outside a housing.

[0075] Implementation of the invention

[0076] Fig. 1 shows a schematic perspective view of an e-bike 1 and Fig. 2 shows a schematic perspective view of an electric drive 3. Such an e-bike differs from a conventional bicycle in that it is equipped with an electric drive that assists a rider when pedaling, thus saving energy and generally increasing riding comfort. Furthermore, this concept represents a more environmentally friendly and less noisy alternative to the conventional moped or motorcycle. The e-bike has an electric drive 3 in or on the rear wheel and this is positioned around an axis 5 of the e-bike 1. The electric drive 3 is designed as an external rotor and is connected to a wheel 2 of the e-bike 1 via spokes 6 and a rim 4. It is advantageous that the spokes 6 in the present case are straight and therefore do not require any bending.

[0077] On the electric drive 3, around the axle 5 of the wheel 2, there are additional components, such as a brake disc 7 or a pulley. The pulley consists of a specific number of teeth and serves to transmit the belt power to the freewheel 43. Furthermore, the pulley is positioned on a freewheel 43 and coupled to pedals 17 via a belt 18.

[0078] Furthermore, the electric drive 3 is electrically connected to a battery 29 via a cable 41 (not shown here), and relevant information such as speed or battery charge level is transmitted via a display 28. This display 28 can also be used to calibrate a sensor or torque sensor 12 or to lock the e-bike 1.

[0079] Further components of the e-bike 1 are a frame 20 in which the display 28 is integrated and which also contains the battery 29. Furthermore, the e-bike is equipped with a handlebar 22 where the brake and gear levers 23, 24 are attached. In addition, a second display can be installed, which shows information such as average and current speed, percentage of battery charge, calorie consumption and kilometers traveled. The e-bike 1 also has an adjustable saddle 21 and a front brake disc 19. In addition, the e-bike 1 is equipped with front 25 and rear 26 mudguards as well as safety features such as a license plate holder with reflector 27 or a bell. Fig. 2 shows a schematic perspective view of an electric drive 3. This is positioned around an axis 5 of an e-bike 1 and assists a rider when pedaling.More precisely, it is located in a rear wheel 2 and is connected to a rim 4 via spokes 6. A housing 11 of the electric drive 3 consists of two cover bodies 8, 9, which are made of metal or plastic, for example. Furthermore, together they form a closed component that protects its interior from mechanical damage and other undesirable external influences. This makes the housing 11 water- and splash-proof, which is essential for protecting the electric drive 3 and for using the e-bike 1 in rainy weather.

[0080] The housing 11 is bolted to the wheel 2 via a support element 14, and the axle 5 is connected to the wheel 2 via a thru-axle 42. Furthermore, the housing 11 is connected to pedals 17 via a freewheel 43 and a belt 18. Finally, the electric drive 3 is connected to a battery 29 of the e-bike 1 via a cable 41.

[0081] Fig. 3 shows an exploded view of an electric drive 1. The electric drive 3 comprises a sensor 12 and a measuring element 13, which can be coupled to a freewheel 43. The sensor 12 measures the drive assistance and is arranged in the area of ​​an axle 5 of the impeller 2. Furthermore, the sensor 12 is designed as a torque sensor and is firmly connected to a carrier 15. The measuring element 13 is magnetized, and the strength of the magnetic field is measured thereon by the sensor 12.

[0082] As soon as the rider pedals, the magnetic field of the magnetized measuring element 13, which can be made of ferromagnetic material, changes. This change, measured by the sensor 12, can be referred to as the strength of the magnetic field.

[0083] This measurement is then evaluated to determine the level of electric assistance provided to the rider. It is beneficial that the higher the rider pedals, the greater the assistance provided, providing a natural riding feel.

[0084] Furthermore, two bearings A and B, here 30A, 30B, are visible. Ball bearings are shown in Fig. 3, but other bearing types such as tapered or cylindrical bearings are also possible. The first bearing 30A is in contact with the carrier 15 via its outer ring. Furthermore, the second bearing 30B is coupled to the carrier 15 via its inner ring, thus it is mounted on an outer surface AO of a bearing seat 44 (see Fig. 4B).

[0085] Finally, a rotor 39 and coils 40 are shown, which together with the carrier 15 are basic components of the electric drive 3 and serve to convert electrical energy into mechanical energy.

[0086] Fig. 4A shows a detailed exploded view of a sensor 12 and other components. A measuring element 13 is coupled to a freewheel 43 by means of a connection pattern 16, here a thread, and a connecting element 36. Furthermore, the magnetized measuring element 13 is positioned on the sensor 12 to enable contactless measurement of the strength of the magnetic field thereon. All three components are arranged around an axis 5. The freewheel 43 contains various parts such as two toothed discs 35, 36, a spring 37, and a freewheel body 10. Finally, a sealing element 34, a spacer element 38, and a washer element 32 are also illustrated, with the sealing element 34 ensuring the tightness of the connection. The spacer element 38 and the washer element 32 ensure the appropriate axial positioning of the components.

[0087] Fig. 4B illustrates a detailed exploded view of a second possible arrangement of a sensor 12 for measuring torque in an electric drive. The sensor 12 is designed to detect the measurable force at a magnetized sensing element 13, which records the pedal force exerted by the driver. The sensing element 13 is strategically placed to enable the direct transmission of the force, which is routed through a freewheel 43.

[0088] There is a carrier 15 with a bearing seat 44 having an outer surface A0. A bearing 30, 30B is arranged on this surface A. The torque is measured by sensor 12, which measures the measurable force on a magnetized measuring element 13.

[0089] The carrier 15 is also arranged around an axis 5 and has a second bearing 30, 30A. The measurable force is transmitted to the measuring element 13 via the freewheel 43, which corresponds to the force exerted by a rider pedaling. Furthermore, the freewheel 43 is coupled to the measuring element 13 via a connecting element 33, specifically by means of a threaded connection pattern 16.

[0090] Fig. 5 shows a schematic diagram of a measured torque signal. The lower part of the diagram shows the signal curve when the measurable force is measured outside the housing. The upper part of the diagram, however, shows the signal curve measured when a sensor 12 is mounted in a housing 11.

[0091] The sensor 12 is advantageously positioned inside an electric drive 1 to protect it from adverse external influences such as weather or mechanical damage. At the same time, the signal measured inside is less dynamic and therefore easier to evaluate. A reliable and accurate measurement is the basis for correctly determining the level of electrical assistance a rider requires when pedaling, ensuring a comfortable ride with a natural feel.

[0092] The present invention shows an electric drive for an e-bike with an integrated sensor. It goes without saying that numerous other embodiments are conceivable for a person skilled in the art based on the exemplary embodiments described.

[0093] List of reference symbols

[0094] 1 E-Bike | Electric Bicycle

[0095] 2 wheels

[0096] 3 Electric drive

[0097] 4 rim

[0098] 5 axis

[0099] 6 spokes

[0100] 7 Rear brake disc

[0101] 8, 9 lid body

[0102] 10 freehub bodies

[0103] 11 housings

[0104] 12 Sensor

[0105] 13 Measuring element

[0106] 14 Support element

[0107] 15 carriers

[0108] 16 connection patterns

[0109] 17 pedals

[0110] 18 belts

[0111] 19 Front brake disc

[0112] 20 frames

[0113] 21 Saddle

[0114] 22 Handlebar

[0115] 23 brake levers

[0116] 24 gear levers

[0117] 25 Front mudguard

[0118] 26 Rear mudguard

[0119] 27 License plate holder with reflector

[0120] 28 Display

[0121] 29 Battery

[0122] 30 warehouses

[0123] 30A Warehouse A or first warehouse

[0124] 30B Warehouse B or second warehouse

[0125] 32 Washer element

[0126] 33 Connecting element

[0127] 34 Sealing element

[0128] 35, 36 toothed disc

[0129] 37 spring

[0130] 38 spacer element

[0131] 39 Rotor 40 Coil

[0132] 41 cables

[0133] 42 thru axle

[0134] 43 Freewheel 44 Bearing seat

[0135] 45 spoke connection

[0136] AO exterior surface

Claims

Patent claims 1. An electric drive (3), in particular for an e-bike (1), comprising: a housing (11) comprising two cover bodies (8, 9); an axle (5) guided through the two cover bodies (8, 9); a carrier (15) with a bearing seat (44); at least one bearing (30); a sensor (12) arranged in the region of the axle (5) of a wheel (2) to measure drive assistance; and a measuring element (13) that can be coupled to a freewheel (43) by means of a connection pattern (16), wherein a transmitted force on the measuring element (13) can be detected by the sensor (12), and wherein the at least one bearing (30) can be placed on an outer surface (AO) of the bearing seat (44).

2. Electric drive (3) according to claim 1, wherein the sensor (12) is positioned together with the measuring element (13) in the housing (11) of the electric drive (3).

3. Electric drive (3) according to claim 1 or 2, wherein the measuring element (13) has the shape of a sleeve when integrated into the motor.

4. Electric drive (3) according to one of the preceding claims, wherein the measuring element (13) is magnetized.

5. Electric drive (3) according to one of the preceding claims, wherein the two cover bodies (8, 9) are coupled to spokes (6) of the impeller (2) by a spoke connection (45).

6. Electric drive (3) according to one of the preceding claims, wherein the housing (11) can be coupled to the impeller (2) by a support element (14).

7. Electric drive (3) according to claim 6, wherein the support element (14) has a sleeve shape.

8. Electric drive (3) according to one of the preceding claims, wherein the sensor (12) is provided on the carrier (15).

9. Electric drive (3) according to one of the preceding claims, wherein a force generated by pedaling can be transmitted to the measuring element (13) via the freewheel (43).

10. Electric drive (3) according to one of the preceding claims, wherein a transmitted force is measurable on the measuring element (13).

11. Electric drive (3) according to claim 10, wherein the transmitted force in the form of a magnetic field strength can be detected by the sensor (12).

12. Electric drive (3) according to one of the preceding claims, wherein a measured force can be transmitted to the electric drive (3) and can be used to monitor a state of the electric drive (3).

13. Electric drive (3) according to one of the preceding claims, wherein the sensor (13) is designed as a force sensor and preferably as a torque sensor.

14. Electric drive (3) according to one of the preceding claims, wherein the sensor (13) is calibrated.

15. Electric drive (3) according to one of the preceding claims, wherein the coupling between the freewheel (43) and the measuring element (13) takes place directly or exclusively intermediately.

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