Bicycle pedal

Abstract

Bicycle Pedal The invention relates to a bicycle pedal comprising: A pedal axle (30), A pedal body (20) comprising at least one bearing face (22) on which a cyclist is capable of exerting a radial force on the pedal axle (30), At least one connecting member (50) mechanically connecting the pedal body (20) to the pedal axle (30) comprising: a mechanical bearing (60) having an inner ring (62) fixed relative to the pedal axle (30) and an outer ring (64) fixed relative to the pedal body (20), at least one piezoelectric transducer (70) extending between the mechanical bearing (60) and one of the pedal axle (30) and the pedal body (20). Figure for the abstract: Fig. 1

Description

Title of the invention: Bicycle pedal

[0001] The invention relates to a bicycle pedal and a method for measuring effort using the bicycle pedal. technical field

[0002] The invention relates to the field of cycling, more specifically to personal performance measurement tools, which encompass the tools, principles, and methods enabling individuals to measure, analyze, and share their personal data. It also relates to effort measurement, system autonomy, and mechatronic integration.

[0003] The invention aims to improve force measurement devices for cyclists, in particular those integrated into bicycle pedals that measure information on the force exerted by the cyclist on the pedal as a function of its rotation. These devices allow cyclists to monitor and optimize their performance by measuring the forces applied during pedaling. Previous technique

[0004] Such force measurement devices integrated into bicycle pedals already exist. They are offered by various manufacturers. These systems, such as those described in patents DE10158600 B4, EP2299252 Bl, FR3078158 Al, US20140273543 Al, and US20160052583, are generally based on the deformation of a test body, forming the pedal axle, with strain / stress gauges mounted on the test body. However, these systems are relatively expensive and complicated to manufacture due to the need for a pedal axle of a specific shape and material, and for individual factory calibrations. Furthermore, they require an external power source (battery) with limited autonomy (50-100 hours) and the associated wiring. Finally, their complexity, particularly in terms of structure and wiring, increases the risk of failure.

[0005] Patent DE202016000321 also uses the deformation of a test body along the pedal axis for force measurement using a strain gauge and mentions the possibility of using a piezoelectric transducer instead of the strain gauge to measure the deformation of the pedal axis. This patent does not detail how the piezoelectric transducer is integrated in place of the strain gauge on the axis.

[0006] Patent application EP2883784 describes a device for measuring force in the pedal, based on the deformation of a strain gauge extending between a first face of the pedal on which the cyclist can exert force and the axle. This system It uses a force sensor similar to a bathroom scale and directly measures the force exerted by the user on the gauge. It allows the measurement of the force applied exclusively on the axis normal to the pedal, whereas, during pedaling, this is not always entirely the case.

[0007] US patent 20140000361 Al proposes a force measurement system inserted between the crank and the pedal axle, measuring the displacement of the device to estimate the force at the pedal axle.

[0008] Patent EP4157701 A1 proposes a system based on an electromechanical device for energy recovery during pedaling, while patent CN106476971B uses piezoelectric bars for energy recovery on the pedal axle. However, these systems require friction between the piezoelectric bars and the pedal's contours, which is not recommended for use in cycling. Furthermore, this system does not allow for the measurement of the cyclist's pedaling effort.

[0009] There is therefore a need for an alternative device on a pedal allowing efficient measurement of the effort exerted by the cyclist on the pedal during pedaling at low cost, regardless of the pedaling frequency.

[0010] There is also a need for a device with long battery life and low passive discharge, which is simple to manufacture, lightweight, robust, and has a minimal impact on pedaling. It is also preferable that it be applicable to most pedals and therefore independent of the materials used.

[0011] Thus, there is a need for a measurement of effort in bicycle pedals, combining precision, energy autonomy, robustness and simplicity of integration, while being compatible with the specific requirements of cycling. Description of the invention

[0012] The invention addresses this need in particular by means of a bicycle pedal comprising: 1. A pedal axle, 2. A pedal body comprising at least one bearing surface on which a cyclist is likely to exert a radial force on the pedal axle, 3. At least one connecting element mechanically linking the pedal body to the pedal axle, comprising: • a mechanical bearing having an inner ring fixed relative to the pedal axle and an outer ring fixed relative to the pedal body, and • at least one piezoelectric transducer extending between the mechanical bearing and one of the pedal axle and pedal body.

[0013] The invention proposes an innovative solution using piezoelectric transducers for force measurement and energy generation. The transducers are integrated directly into the pedal bearings, where the force is applied, allowing for a more precise and direct measurement of the radial force. This differs from existing systems that measure force via the deformation of a test body, which can introduce measurement biases related in particular to the axle material and the variability of the bonding of strain gauges to the test body.

[0014] This configuration also allows the energy generated by the transducers to be recovered to power the reading and transmission electronics or other functions such as flashing devices, autonomous cadence sensors, anti-theft GPS trackers, etc., making the system more autonomous. Integrating the transducers inside the junction element avoids the use of a rotating collector and ensures that the force is transmitted exclusively along the axis of the bearings, thus simplifying the measurement of the force transmitted along the axis of the pedal.

[0015] Furthermore, piezoelectric transducers are robust and their deformation under load is very low due to their high rigidity. This ensures reliable and durable measurement without affecting the pedal structure. In addition, the absence of additional friction compared to a conventional pedal, due to the integration of the transducer between two fixed parts, improves the mechanical robustness and durability of the device. Their integration within bearings is facilitated by their small size and their ability to be inserted into confined spaces. This makes it possible to maintain the rigidity necessary to ensure mechanical transmission while achieving an accurate measurement of force. They are also particularly well-suited for quasi-static cyclic measurements, such as those encountered during pedaling. This allows for an accurate measurement of the force applied by the cyclist regardless of their pedaling speed.

[0016] Another advantage, and a significant one, is its low cost combined with its ease of integration. This makes it possible to consider marketing connected pedals to a wider audience.

[0017] Finally, piezoelectric transducers and the associated electronics are particularly energy efficient.

[0018] In summary, the proposed claim offers an innovative and efficient solution for measuring effort in bicycle pedals, combining energy autonomy, robustness, simplicity of integration and precision, particularly angular, while being compatible with the specific requirements of cycling.

[0019] In a conventional and known manner, the pedal axle can be configured to be connected to a central axis of rotation of the pedal by means of a crank extending in a substantially vertical plane. The crank and / or the central axis may or may not be part of the bicycle pedal. The pedal axle may include a portion for attachment to the crank at its proximal end, in particular a mounting thread. Piezoelectric transducers

[0020] The at least one transducer is in particular fixed directly or indirectly on the inner ring or on the outer ring on one side and directly or indirectly on the pedal body or the pedal axle on the other side.

[0021] At least one transducer can be configured to generate an electrical signal when subjected to stress along an axis radial to the pedal axis. The at least one transducer can be configured so that the generated signal is proportional to the stress experienced when force is exerted by the cyclist on the pedal body. This allows for a representation of the force projected along this radial axis transmitted between the pedal and the crank.

[0022] Preferably, at least one connecting member comprises a plurality of piezoelectric transducers extending between the mechanical bearing and one of the pedal axles and the pedal body, distributed around the pedal axle, in particular substantially uniformly distributed around the pedal axle. Preferably, at least two of the piezoelectric transducers are arranged around the pedal axle to generate a signal when subjected to stresses along different radial axes, in particular they are arranged around the pedal axle forming a non-planar angle between said radial axes.

[0023] Preferably, the piezoelectric transducers are all identical.

[0024] By integrating a plurality of piezoelectric transducers distributed uniformly around the pedal axle, in particular with two generating a signal under stress along different radial axes, it becomes possible to determine the forces applied by the cyclist in two dimensions. This configuration makes it possible to determine not only the magnitude of the force, but also its actual direction by combining the signals generated by the different piezoelectric transducers around the pedal axle. This provides a complete and accurate picture of the force applied by the cyclist, unlike a one-dimensional measurement that only captures one component of the force. This improves the accuracy of the measurements and allows for a more detailed analysis of the cyclist's performance. This configuration allows for a better understanding of the distribution of forces applied by the cyclist, thus providing a more complete and accurate picture of the total effort.The uniform distribution of transducers around the pedal axle allows for the capture of angular variations in the applied force. This is... particularly useful for the cyclist to assess their performance and optimize their pedaling.

[0025] Furthermore, the use of several piezoelectric transducers distributed around the pedal axle increases the robustness of the system. In the event of a transducer failure, the other transducers can continue to operate, thus ensuring continuity of measurement. This redundancy improves the overall reliability of the device.

[0026] The uniform distribution of the transducers also eliminates the need to consider their positioning around the pedal axle. Regardless of the orientation of the axle and / or pedal body, the intersection of the signals generated by the different transducers allows for the precise determination of the force. This is particularly useful when the transducers are fixed relative to the pedal axle, especially between the pedal axle and the mechanical bearing, because the pedal axle rotates around a central axis and therefore assumes all possible orientations during its rotation. In this case, an initial calibration of the bicycle pedal, particularly of a unit of measurement for the force, may be necessary to assign each piezoelectric transducer a spatial orientation relative to the pedal body or the pedal axle and to associate the measurement by each piezoelectric transducer with a pre-calibrated orientation.

[0027] Finally, the plurality of piezoelectric transducers distributed around the pedal axle allows for better recovery of the energy generated by the cyclist's effort. This configuration maximizes the contact area and the efficiency of the conversion of mechanical energy into electrical energy over a complete pedaling cycle, thus improving the system's potential range.

[0028] Preferably, the connecting element comprises three piezoelectric transducers arranged uniformly around the pedal axle. This allows for a measurement of the force in minimal two dimensions.

[0029] Alternatively, the connecting element comprises a single piezoelectric transducer or two piezoelectric transducers arranged in opposition with respect to the pedal axle. In this case, the transducer(s) can be arranged to generate a signal when subjected to stress along an axis perpendicular to the bearing face of the pedal body or along an axis perpendicular to the crank after the pedal axle is fixed to the crank.

[0030] The piezoelectric transducer(s) can be configured to generate a signal when subjected to stress along a radial axis perpendicular to the bearing surface, regardless of the pedal's position. In particular, in this case, the piezoelectric transducer(s) are arranged tangentially between the pedal body and the mechanical bearing. Indeed, the force is exerted primarily perpendicular to the bearing face. It is therefore advantageous to have the value along This direction is a priori the most important, particularly for the purpose of generating electricity and evaluating the force applied to the pedal. In this case, the pedal preferably includes a means of detecting the orientation of the pedal body relative to the pedal axle and / or the crank arm. This allows, in particular, the determination of the useful force exerted by the cyclist on the pedal in a direction perpendicular to the crank arm after the pedal axle is fixed to the crank arm.

[0031] The piezoelectric transducer(s) can be arranged tangentially between the pedal axle and the mechanical bearing. In this case, the piezoelectric transducer(s) can be oriented to generate a signal when subjected to a stress in a direction perpendicular to the crank after the pedal axle is fixed to the crank. Thus, the measurement obtained using the signal generated by said piezoelectric transducer is directly that of the useful force exerted by the cyclist on the pedal.

[0032] Preferably, the piezoelectric transducer(s) extend between the mechanical bearing and the pedal axle. In this case, the piezoelectric transducer(s) can be oriented to generate a signal when subjected to stress in a direction perpendicular to the crank after the pedal axle is fixed to the crank. This allows for direct detection of the useful force by the transducer(s).

[0033] The piezoelectric transducer(s) are preferably 5 mm or less thick, and even better, 2 mm or less, in order to maximize the internal capacity of the piezoelectric transducer and limit losses. This characteristic of thin piezoelectric transducers offers advantages in terms of reduced size, maintenance of rigidity and robustness, ease of integration, and compatibility with advanced manufacturing techniques, making the force measurement system compact and efficient. In particular, its small size is especially important in the context of integration within a bicycle pedal, where space is limited. A reduced thickness facilitates the integration of the transducers without compromising the structure and functionality of the pedal.Their small size allows them to be inserted into complex configurations without requiring major modifications to the existing structure. This simplifies the integration process and reduces manufacturing costs. Furthermore, their deformation under load is very low, ensuring that the pedal structure remains robust and reliable, and they offer high measurement sensitivity, guaranteeing accurate measurements and providing a detailed picture of the total and useful force applied by the cyclist.

[0034] The piezoelectric transducer(s) may be made of ceramic, in particular lead zirconate titanate (PZT), aluminum nitride (AIN), and zinc oxide (ZnO), or of polymer, in particular polyvinylidene fluoride (PVDF). Ceramic materials are preferred because they offer high rigidity and low deformation under load.

[0035] The piezoelectric transducer(s) can be characterized in that they are configured to generate energy by the effort of the cyclist on the pedal body.

[0036] The piezoelectric transducer(s) can be configured to generate an electrical power greater than 1 pW, preferably greater than 10 pW, in particular an energy greater than or equal to 10 pJ per pedal revolution.

[0037] The total volume of piezoelectric material of the junction element distributed over the piezoelectric transducer(s) can be between 50 mm3 and 250 mm3, preferably between 60 mm3 and 150 mm3.

[0038] The ratio between the thickness of each transducer and its surface area can be such that the voltage generated by the piezoelectric transducer or each one is between 3 and 100 V. pedal axle

[0039] The pedal axle can be substantially straight. It can be made of any material suitable for forming such an axle.

[0040] The pedal axle can be manufactured from specific materials to improve durability and performance. For example, the central axle can be made of stainless steel, titanium, or aluminum alloy to offer an optimal combination of strength and lightness.

[0041] The pedal axle can be subjected to surface treatments to improve its resistance to wear and corrosion. For example, the axle can be coated with a layer of titanium nitride (TiN) or an anodized treatment to increase its durability.

[0042] The pedal axle can be designed to facilitate the management of signals and energy generated by piezoelectric transducers. For example, the axle can include internal channels for cable passage or connectors for data and power transmission.

[0043] The pedal axle can be designed to be compatible with different types of bicycle pedals. For example, the axle can have standardized dimensions and configurations to fit road, mountain bike, city bike, or electric bike pedals. In the latter case, the cyclist's power output can be measured to control and thus improve the power delivered by the motor based on the actual effort exerted by the cyclist.

[0044] Where the transducer(s) extend between the mechanical bearing and the pedal axle, the latter can be machined to have an external face adapted for mounting the piezoelectric transducer(s) on it. This external face may include flat surfaces arranged around the pedal axle for mounting the piezoelectric transducer(s). The number of flat surfaces can be substantially equal to the number of piezoelectric transducers around the axle. Spacer

[0045] Preferably, at least one connecting member comprises an adapter spacer extending between the mechanical bearing and the piezoelectric transducer(s), configured to allow the piezoelectric transducer(s) to be attached to the mechanical bearing, in particular to allow the flat surface of the piezoelectric transducers to be connected to a cylindrical surface of the inner or outer ring. The adapter spacer may have a circular cross-sectional surface for contacting one of the bearing rings and flat platforms on the opposite surface for attaching the piezoelectric transducer(s).

[0046] The adapter spacer can be fixed to the mechanical bearing, in particular to the inner ring or outer ring, and / or to the piezoelectric transducer(s) themselves fixed to the central axis by any means, in particular by bonding or by pre-stressed assembly, in particular by thermal shrinking.

[0047] The transducer(s) and / or the spacer can extend along the pedal axle over a width at least equal to that of the mechanical bearing, preferably greater.

[0048] The bicycle pedal may also include load-bearing stops to prevent damage when the force applied to the transducer(s) exceeds a predetermined threshold, in particular corresponding to a maximum acceptable force beyond which the transducer(s) may be damaged. Such a stop may extend parallel to the transducer(s) and have a thickness less than that of the transducer(s) to correspond to the maximum force and / or deformation acceptable to the transducer(s). The stop may be part of the spacer or be an additional component mounted on the spacer, in particular a ring. Electronic processing circuit

[0049] The bicycle pedal may include an electronic processing circuit configured to receive the signal generated by the piezoelectric transducer or the signals generated by the electronic transducers and / or the energy generated and / or the electrical power generated by the piezoelectric transducer(s) when the cyclist applies force to the pedal body and to deduce at least one piece of information about the force applied by the cyclist to the pedal body or to transmit the information to an external electronic device configured to deduce at least one piece of information about the effort applied by the cyclist on the pedal body.

[0050] The electronic processing circuit or external device may include an electronic measuring unit configured to receive the signal generated by the piezoelectric transducer or the signals generated by the electronic transducers and / or information on the energy generated by the piezoelectric transducer(s).

[0051] The electronic processing circuit may include a communication unit configured to transmit to an external device the signal(s) generated by the piezoelectric transducer(s), particularly in the absence of an internal measuring unit, and / or the information on the force applied by the cyclist to the pedal body, particularly in the presence of an internal measuring unit in the bicycle pedal. The communication unit may be characterized in that it uses a wireless communication technology, such as Bluetooth, Wi-Fi, ANT, or another radio frequency communication technology, to transmit the generated data and / or signals. Communication Unit

[0052] The communication unit can be configured to send real-time data, thus enabling live monitoring of pedaling effort by the user.

[0053] Alternatively or in addition, the electronic circuit may include a temporary data storage system, allowing the data to be retained, in particular in the absence of a communication unit, in the event of data being sent by packet or in the event of loss of connection with the external device, and to be transmitted later when the connection is restored. Electrical power management unit

[0054] The electronic circuit may include an electrical power management unit configured to recover at least some of the energy generated by the piezoelectric transducer(s). It may store this energy to at least partially power the measuring unit and / or the communication unit and / or to electrically power an external electrical system, in particular a flashing light, a standalone GPS tracker, a standalone timing system, or another measuring system.

[0055] The electrical energy management unit may include a capacitive storage system intended to store at least part of the electrical energy generated by the piezoelectric transducer(s).

[0056] The energy management unit can be configured to generate energy information generated by the transducer(s). It can increment at least one binary count when the voltage across said capacitive storage element reaches a threshold value or a maximum reference value, such that said at least one The binary count represents the force applied by the cyclist to the pedal body. The power management unit can also record the time between two increments of the binary count. Alternatively, the power management unit is configured to increment the binary count at fixed intervals and to record the voltage across the storage element between two increments. These recordings are not direct measurements of the applied force. The information obtained from this binary count is related, for example, to the duration or magnitude of the applied force. Thus, the binary count can be used to estimate both the effort generated by the cyclist and its duration. The electronic processing circuit may include non-volatile memory connected to the power management unit, which is configured to store at least one binary count in its memory.

[0057] In the case where the piezoelectric transducer(s) are fixed relative to the pedal axis, the processing unit can be arranged on the pedal axis and be electrically connected to the piezoelectric transducer(s), in particular by conductive wires.

[0058] In the case where the piezoelectric transducer(s) are fixed relative to the pedal body, the processing unit can be arranged on the pedal body and be electrically connected to the piezoelectric transducer(s), in particular by conductive wires. Unit of measurement

[0059] Where the measuring unit is external, the invention may also consist of a bicycle pedal assembly and an external data processing unit incorporating the measuring unit. The external data processing unit may then be a housing to be attached to the bicycle or a digital processing tool, preferably a computer with suitable software or an application to be installed on an external device, such as a phone or tablet, configured to communicate with the pedal's communication unit. This allows, in particular, for data analysis to be performed on an external device that may include a power supply, such as a battery. This reduces the energy consumption required for measurements at the bicycle pedal.

[0060] The unit of measurement deduces, preferably for the signal or each signal generated by the transducer or from the information of the generated energy, a value of the force measured along the radial axis corresponding to the piezoelectric transducer or each one.

[0061] The unit of measurement can be configured to determine the value of the useful force, that is, the force applied by the cyclist on the pedal along a useful axis perpendicular to the crank after the pedal axle is fixed to the crank. This determination can be carried out by direct measurement from the signal generated by a piezoelectric transducer configured to generate a signal according to the force exerted on this axis or by crossing the values ​​of the force measured along the radial axes of different transducers different from the useful axis or by analysis of the energy generated by the transducer(s).

[0062] In the case of a plurality of piezoelectric transducers positioned in a suitable way, the unit of measurement can be configured to determine the value and direction in a plane transverse to the pedal axis of the force applied by the cyclist on the pedal by crossing the values ​​of the force measured along the radial axes of the different transducers or by analyzing the energy generated by the transducers.

[0063] The unit of measurement can be configured to determine information on the force applied by the cyclist to the pedal body at a predetermined fixed or variable frequency. The predetermined frequency can be the pedaling frequency. In this case, it can be variable. Alternatively, it is fixed and greater than the maximum pedaling frequency, in particular at least 5 times, preferably at least 10 times, the maximum pedaling frequency. The maximum frequency considered can be determined according to the intended use of the bicycle pedal, in particular the type of bicycle or the user profile. The maximum frequency considered can be 2 Hz. Preferably, the predetermined frequency is chosen according to the intended use and the type of power supply for the piezoelectric transducer(s).Indeed, in the case of self-powered systems, it is preferable that the energy expenditure related to measurements be offset by the energy generated by the transducer(s) when effort is exerted. To limit the sampling frequency of measurements and therefore the energy consumption of the electronic circuit, the electronic circuit can be configured to integrate the useful and total effort values ​​determined per pedal revolution, notably by accumulating the energy charges generated by the transducers during each cycle or by accumulating the useful efforts determined over a cycle, and to transmit the information externally, particularly to the external device, only at each pedal revolution.

[0064] The bicycle pedal may include an internal clock or oscillator configured to trigger measurements. This makes it possible, in particular, to obtain a measurement of the level of effort with high angular resolution by integrating the precise orientation of the transducer(s) at the time of measurement.

[0065] The unit of measurement can be configured to determine information on the useful effort applied per pedal revolution, in particular the useful power generated during a pedal revolution from the energy generated or the signal or signals generated by the transducer(s). This makes it possible, in particular, to evaluate performance over time by comparing overall pedaling performance over a training session or over several training sessions.

[0066] The measuring unit can be configured to determine the angle of rotation of the mechanical bearing, and therefore of the pedal body, around the pedal axle, corresponding to the rotation of the bicycle pedal around the central axis. This can be done based on variations in the signals from the piezoelectric transducer(s) over time or by analyzing the energy generated by the transducers. It is then possible to track the movement of the pedal by measuring the forces exerted.

[0067] The unit of measurement can be configured to associate each measurement of effort with the position of the crank or pedal relative to a fixed axis, in particular the horizontal axis or the vertical axis.

[0068] The measuring unit can be configured to also count the number of crank revolutions, determine the pedaling frequency, the direction of rotation, and / or the pedaling speed from the signals generated by the piezoelectric transducer(s). This allows, from a single type of sensor, access to a large amount of information about pedaling through analysis of the received data.

[0069] All the measurements or determinations that can be performed by the aforementioned measuring unit can be carried out by the internal or external measuring unit as described, or by the measuring unit, particularly the internal one, and an additional external data processing unit. In this case, the invention may also consist of a bicycle pedal and an additional data processing unit. The additional processing unit may then be a box to be attached to the bicycle or, preferably, an application to be installed on an external device, such as a phone or tablet, configured to communicate with the pedal's communication unit. This makes it possible, in particular, to offload the in-depth data analysis to an external device that may include a power supply, such as a battery. This reduces the energy consumption required for measurements at the bicycle pedal. Plurality of junctional organs

[0070] The bicycle pedal may include at least one additional connecting element mechanically linking the pedal body to the pedal axle and spaced from the connecting element along the pedal axle. The additional connecting element may include a mechanical bearing having an inner ring fixed relative to the pedal axle and an outer ring fixed relative to the pedal body. Preferably, it includes one or more piezoelectric transducers extending between the mechanical bearing and one of the pedal axles and the pedal body. It may have one or more of the features of the connecting element described above. It may or may not be identical to the connecting element. The signals or energy generated by the transducer(s) may be used by the processing circuit.

[0071] Having several bearing connecting elements allows for good support of the pedal body on the pedal axle and good force transfer on the pedal axle.

[0072] Alternatively, the additional connecting element is devoid of piezoelectric transducers and only ensures a rotational connection without measurement between the pedal body and the pedal axle. Food

[0073] The bicycle pedal may include a power supply to electrically power the measuring unit for analyzing the signals generated by the piezoelectric transducer(s) and / or the communication unit to communicate the generated data to the outside.

[0074] The power supply can be a rechargeable battery or a disposable battery. Such a battery can electrically power the measuring unit for analyzing the signals generated by the piezoelectric transducer(s) and / or the communication unit for transmitting the generated data to the outside.

[0075] In this case, the signal(s) generated by the piezoelectric transducer(s) can only be used for force measurement. The generated electrical energy is lost. Alternatively, the signal(s) generated by the transducer(s) are used to partially power the measuring unit for analyzing the signals generated by the piezoelectric transducer(s) and / or the communication unit for transmitting the generated data externally, and are supplemented by the power supply.

[0076] Alternatively, the power supply includes one or more piezoelectric transducers of the additional junction element. It may also include the power management unit, which is configured to recover at least some of the energy generated by the piezoelectric transducer(s) of the additional junction element and store it to at least partially power the measuring unit and / or the communication unit. In this case, the junction element is used to measure the force applied by the cyclist to the pedal body, and the additional junction element is used to power the pedal, thus making the pedal energy-independent.

[0077] Alternatively, the measuring unit and / or the communication unit are electrically powered by the piezoelectric transducer(s) of the junction member and / or the additional junction member when they are subjected to a stress along an axis radial to the axis of the pedal. Thus, the junction member and / or the additional junction member act as both a sensor and an energy generator. Bike

[0078] The invention also relates to a bicycle comprising at least one pedal as described above.

[0079] The bicycle may have two pedals as described above.

[0080] The invention also relates to an assembly of a bicycle comprising at least one pedal as described above and an external processing unit comprising the measuring unit. Process

[0081] The invention also relates to a method for measuring the effort exerted by a cyclist on a bicycle pedal as described above, comprising the analysis of the electrical signals generated by the piezoelectric transducer(s) and / or the energy generated by the piezoelectric transducer(s).

[0082] The process includes the features described above independently or in combination with each other.

[0083] The method may include determining the total and / or useful effort applied by the cyclist on the pedal body from the electrical signals generated by the piezoelectric transducer(s) and / or the energy generated by the piezoelectric transducer(s).

[0084] The method may include the transmission to an external device of the total and / or useful forces determined.

[0085] The method may include the transmission of the total and / or useful force determined to an electric assistance system and the control of the electric assistance to the pedal to the total and / or useful force, determined.

[0086] The invention will be better understood upon reading the following non-limiting examples of embodiments. Brief description of the drawings

[0087] [Fig-1] schematically represents an example of a bicycle pedal according to the invention,

[0088] [Fig.2] is a view along the pedal axis of the bicycle pedal of [Fig.1],

[0089] [Fig.3] is a schematic perspective view of the bicycle pedal of [Fig.1],

[0090] [Fig.4] shows in cross-section the connecting element of the bicycle pedal of [Fig.1],

[0091] [Fig.5] is a schematic representation of the bicycle pedal electronics of [Fig.1],

[0092] [Fig.6] is a schematic view of a variant of a bicycle pedal,

[0093] [Fig.7] is a schematic view of a variant of a bicycle pedal,

[0094] [Fig.8] is a schematic view of a variant of a bicycle pedal,

[0095] [Fig.9] is a schematic view of a variant of a bicycle pedal, and

[0096] [Fig. 10] is a schematic view of a variant of a bicycle pedal. Detailed description

[0097] Figures 1 to 5 illustrate an example of a bicycle pedal 10 according to the invention.

[0098] The bicycle pedal 10 comprises a pedal axle 30, a pedal body 20 against which the cyclist exerts force during pedaling and a connecting member 50 between the pedal body 20 and the pedal axle 30 to allow the rotation of the pedal body 20 around the pedal axle 30 during pedaling. The pedal axle 30 is configured to be mounted on a crank 102 itself connected to a central axis 104 of rotation, so that the pedal axle is configured to rotate around the central axis 104 via the crank 102. The crank 102 extends in a substantially vertical plane. The pedal axle 30 is fixed to the crank by any known means. It may, for example, include a proximal fixing portion 32, in particular threaded, configured to be mounted on the crank 102, as illustrated in [Fig. 1].

[0099] The connecting member 50 includes a mechanical bearing 60 and piezoelectric transducers 70 extending between the pedal body 20 and the pedal axle 30, being fixed relative to one or the other depending on their positioning.

[0100] The mechanical bearing 60 is a circular component enabling the rotation of the pedal body 20 around the pedal axle 30. The mechanical bearing 60 comprises an inner ring 62, which is fixed relative to the pedal axle 30, here with the piezoelectric transducers between them, an outer ring 64, which is fixed relative to the pedal body 20, and rolling elements 66, such as balls or rollers, between the inner ring 62 and the outer ring 64 to allow smooth rotation between the two rings 62 and 64 and thus between the pedal body 20 and the pedal axle 30. The bearing can be of any known shape suitable for such use.

[0101] The piezoelectric transducers 70 allow the force applied by the cyclist to be measured and / or electrical energy to be generated from this force. The piezoelectric transducers 70 are fixed directly or indirectly to the inner ring 62 or to the outer ring 64 on one side, and to the pedal body 20 or the pedal axle 30 on the other side. In the example illustrated in [Fig. 1], the piezoelectric transducers 70 are arranged between the mechanical bearing 60 and the pedal axle 30 and are fixed relative to the pedal axle 30 and the inner ring 62. They can be configured to generate an electrical signal proportional to the stress experienced when force is exerted by the cyclist on the pedal body 20 and / or to generate electrical energy when force is exerted by the cyclist on the pedal body 20.

[0102] The piezoelectric transducers 70 can be fixed to the corresponding ring, here the inner ring 62, by means of a fixing spacer 80 illustrated in [Fig. 4]. The fixing spacer 80 has a circular cross-sectional surface 82 to come into contact with one of the bearing rings, here the inner ring 62, and flat platforms 85 on its opposite surface 84 to fix the flat piezoelectric transducers 70 to the circular surface of the inner ring 62.

[0103] The pedal axle 30 may have a longitudinal cylindrical shape. It may have, at least at the level of the piezoelectric transducers 70, flat faces 36 allowing the piezoelectric transducers 70 to be fixed, the latter themselves having a flat contact surface with the pedal axle 30. The pedal axle may have these flat faces only at the level of the transducers 70 and be circular in cross-section elsewhere. It should be noted that the invention is obviously not limited to transducers with a flat face or to the configuration mentioned. The transducers 70 may be connected to the pedal axle 30 by any means, in particular by direct contact of the transducers 70 with the pedal axle 30, with or without special machining of the latter, or by means of an intermediate fixing piece.

[0104] The fixing spacer 80 and the transducers 70 can be fixed between the bearing 60 and the shaft 30 by any means, in particular by bonding between them and to the inner ring 62 and to the shaft 30 or by pre-stressed assembly, in particular by thermal shrink fitting.

[0105] The transducers 70 of the junction member 50 may all be identical. They may have a thickness e of 5 mm or less, or even better, 2 mm or less. The piezoelectric transducers 70 are preferably configured to generate an electrical power greater than 10 pW, in particular an energy greater than or equal to 10 pJ per pedal revolution. The total volume of piezoelectric material of the junction member 50 distributed over the piezoelectric transducers 70 may be between 50 mm³ and 250 mm³, or more preferably between 60 mm³ and 150 mm³. The ratio between the thickness of each transducer and its surface area is such that the voltage generated by each piezoelectric transducer is between 3 and 50 V.

[0106] In the illustrated example, the transducers 70 have a width along the axis 30 substantially equal to that of the bearing 60 along this axis. However, this could not be the case. They could, for example, be wider than the bearing 60. The same could be true for the spacer 80.

[0107] The transducers 70 are each configured and arranged around the axis 30 to emit a signal when compressed along a radial axis of the axis 30.

[0108] The transducers 70 of the junction member 50 can be made of ceramic, in particular lead zirconate titanate (PZT), aluminium nitride (AIN) and zinc oxide (ZnO), or of polymer, in particular polyvinylidene fluoride (PVDF).

[0109] The pedal axle 30 can be made from materials conventionally used for such an axle. The pedal axle 30 may have internal channels for the passage Cables or connectors for data and power transmission. It can be designed to be compatible with different types of bicycle pedals, such as road, mountain bike, or city bike pedals.

[0110] In the illustrated example, the connecting member 50 comprises three piezoelectric transducers 70 uniformly distributed around the pedal axle 30. They form an angle α of 120° with each other. This configuration allows for force measurement regardless of the orientation of the pedal axle 3. It is thus possible, by combining the signals generated by the piezoelectric transducers 70, to precisely determine the direction and magnitude of the force exerted, regardless of the pedal's orientation. In this case, the piezoelectric transducers 70 do not need to be positioned in any particular way relative to the crank 102.

[0111] The pedal 10 may include, as illustrated, an additional connecting member 150 forming another mechanical connecting component between the pedal body 20 and the pedal axle 30 and spaced from the connecting member 50 along the axle 30. It may be similar to the main connecting member 50, as illustrated in [Fig. 1]. Such an additional connecting member allows, in particular, smooth rotation of the pedal body 20 on the axle 30.

[0112] The electronic transducer(s) 70 are electrically connected to an electronic circuit 90, illustrated in [Fig. 5], configured to process the signals generated by the piezoelectric transducers 70 and / or collect the energy they generate. The electronic circuit 90 is preferably fixed to an element fixed relative to the piezoelectric transducers, in particular, fixed, in the example illustrated in [Fig. 1], to the pedal axle 30, here between the two connecting members 50 and 150. It may be in the form of an electronic circuit board. It may include a measuring unit 92 for analyzing the signals and / or energy generated by the transducers 70, a communication unit 94 for transmitting the generated data externally, and / or an electrical energy management unit 96 for recovering and storing the energy generated by at least some of the piezoelectric transducers 70.

[0113] The energy management unit 96 can manage the energy generated by the piezoelectric transducers 70. It can include a capacitive storage system, not shown, in which it can store at least part of the electrical energy generated by the piezoelectric transducers 70 before its use to power at least partially the measuring unit and / or the communication unit 94 and / or to electrically power an additional electrical element, in particular a flasher, an autonomous GPS tracker, an autonomous timing device or another measuring system.

[0114] The energy management unit 96 can be configured to increment a binary count when the voltage across the storage element reaches a threshold value predetermined. In this case, the energy management unit can also record the time between two successive increments of the threshold value. Alternatively, the management unit increments the binary count at predefined constant time intervals and records the voltage across the storage element at each increment. Thus, the binary count can be used to estimate both the effort generated by the cyclist and the duration of that effort. The electronic processing circuit may include non-volatile memory connected to said energy management unit, said energy management unit being configured to store said binary count in memory. This recorded information constitutes information about the energy generated by the piezoelectric transducers and therefore the stress and / or force applied to them.

[0115] The communication unit 94 is configured to transmit data collected or generated on the effort applied by the cyclist to the pedal body to an external device 110. The communication unit may be characterized in that it uses a wireless communication technology, such as Bluetooth, Wi-Fi, or another radio frequency communication technology, to transmit the generated data and / or signals. It may be configured to send data in real time, thus enabling live monitoring of pedaling effort by the user. Alternatively or in addition, the electronic circuit 90 may include a temporary data storage system, allowing the data to be retained in the absence of the communication unit or in the event of a loss of connection with the external device 110, and to be transmitted later when the connection is restored.

[0116] The measuring unit 92 is configured to receive signals generated by the electronic transducers 70 and / or information on the energy generated by the piezoelectric transducer(s) 70.

[0117] The electronic circuit 90 may include an additional power supply not shown to provide at least partial power to the measuring unit 92 and the communication unit 94. The power supply 97 may be a rechargeable battery or a battery.

[0118] The bicycle pedal 10 may include additional sensors or functional elements not shown. Such sensors / elements may be electrically powered by the energy generated by the transducer(s) 70 or by the additional power supply. Such a sensor is, for example, a sensor for the orientation of the crank 102 or the pedal body 20 relative to the pedal axle 30 or the crank 102, a counter for the number of pedal revolutions, or a sensor for the rotational speed of the pedal. Such a functional element is, for example, a light, a flashing light, or a GPS.

[0119] In the context of the bicycle pedal shown in Figures 1 to 4, when the cyclist pedals, they apply pressure to the pedal body 20 via the contact surface 22, applying a force that varies over one rotation cycle of the pedal 10 around the central axis 104. Specifically, the cyclist exerts force on the pedal 10 when it is in the downward phase of the rotation cycle and exerts no force, or less force, when the pedal 10 is in the upward phase. Furthermore, during this effort, the cyclist exerts a force comprising a useful component that enables the movement of the pedal around the central axis 104, perpendicular to the crank 102, and a useless component radial to the crank 102. Having information on these two components is valuable because it allows the cyclist to gain insight into their pedaling performance.It is therefore beneficial for cyclists to have information on the effort exerted during a pedaling cycle, particularly the distribution of effort between the upstroke and downstroke phases, and the distribution of effort between useful and useless components. Furthermore, it is useful for cyclists to have an average assessment of their pedaling per cycle, specifically the average useful and / or useless power per pedal revolution.

[0120] With the invention, when the cyclist applies force to the pedal, at least part of the transducers 70 of the connecting member 50 and the additional connecting member 150, in the present case, are compressed along a radial axis between the bearing 60 and the pedal axle 30. They then each generate an electrical signal, in particular proportional to the force exerted, which is recovered for each transducer 70 by the electronic circuit 90.

[0121] With each signal, the electronic circuit 90 has several possibilities for the electrical signal generated by each transducer 70: 1. store at least part of the energy generated by the transducer 70 in the capacitive storage system for later use and / or 2. Obtain information on the energy generated, notably via the incrementation of the binary count and related data, 3. Analyze the received signal to obtain information on the force projected onto the corresponding radial axis.

[0122] With the device of Figures 1 to 4, comprising transducers 70 in both the junction member 50 and the additional junction member 150, the electronic circuit can, as illustrated in [Fig. 5], use the transducers 70 of the junction member 50 for the analysis of force data via the measuring unit 92 and the transducers 70 of the additional junction member 150 to electrically power the electronic circuit 90 via the power management unit 96. The measuring unit 94 can, for example, determine the direction of the force F applied to the body of The pedal 20 and its force are measured by combining the signals generated by the transducers 70 of the junction unit 50 to deduce, for example, the useful effort Fu and the useless effort Fi. The energy management unit 96 can store the energy from the transducers 70 of the additional junction unit 150 and distribute it within the electronic circuit 90 according to the needs of the various components. If the stored energy is insufficient, the electronic circuit can supply the remaining power with the additional electrical supply. Alternatively, the energy management unit can also store the energy generated by the transducers 70 of the junction unit 50 and / or generate information about this energy, which it can transmit to the measuring unit 92 to determine information about the cyclist's effort, including an average useful power generated per pedal stroke.All the information generated by the measuring unit 92 can be transmitted to the external device 110 via the communication unit 94 using wireless communication. This communication can occur in real time at each measurement, at the end of each pedal revolution, or periodically by internally storing the information before transmission. Alternatively, the information is stored in an internal storage system, and the electronic circuit 90 lacks a communication unit. The cyclist can then regularly retrieve the information by connecting the external device to the storage system. Alternatively, the electronic circuit lacks a measuring unit 92 for extracting the effort information. It may, however, include a processing unit for the information received by the piezoelectric transducer(s), allowing for preprocessing of the signals or information before transmission. The communication unit 94 and / or the internal storage system are configured to transmit / record the information to be transmitted from the signals generated by the transducers 70 and / or information on the energy generated.

[0123] The measuring unit is here presented as being internal to the electronic circuit. However, it could be relocated to the external device 110.

[0124] Figures 6 to 10 illustrate variant embodiments of bicycle pedal 10.

[0125] The bicycle pedal of [Fig. 6] differs from that of [Fig. 1] in that the organ of The additional junction 150 does not include a piezoelectric transducer. In this case, it is not possible to harvest energy on one side and use the data on the other. The electronic circuit can be configured to use only the signals generated by the transducers 70 of the junction element 50 to measure the force, without storing the corresponding energy. It can also store the generated energy in parallel in the storage system and use it to power the electronic circuit and / or external or additional elements / sensors. Alternatively, the circuit 90 can include a power supply such as a rechargeable battery or a battery pack.

[0126] The bicycle pedal of [Fig. 10] differs from that of [Fig. 1] in that the transducers have a particular positioning. One of the transducers 70 is positioned to generate a signal when a force perpendicular to the crank 102 is applied to it. This transducer then allows a direct determination of the useful force applied regardless of the orientation of the pedal body or the pedal.

[0127] The bicycle pedal of [Fig. 7] differs from that of [Fig. 1] in that the connecting member 50 has only one piezoelectric transducer 70. In this case, it is preferable for the latter to be positioned around the axis at a particular position. It is preferably positioned to measure the force corresponding to the useful force, that is, along a radial axis Ru perpendicular to the crank 102, as is one of the transducers of [Fig. 10]. This makes it possible, in particular, to retrieve the information of the useful force and / or the energy generated by the corresponding transducer to measure the useful force over the pedaling cycle or averaged over pedaling cycles, as described previously.

[0128] The bicycle pedal in Figures 8 and 9 differs from that in [Fig. 1] in that the additional connecting member 150 does not include a piezoelectric transducer and in that the transducers 70 of the connecting member 50 are arranged between the pedal body 20 and the bearing 60, in particular the outer ring 64. In this case, the electronic circuit 90 is preferably fixed to the pedal body 20 so that it does not rotate relative to the transducers. The signal and / or energy processing is substantially identical to that described in relation to Figures 1 and 6. At least one of the transducers 70 can be positioned relative to the pedal body 20 so that it is perpendicular to the contact surface 22. It then allows, directly, by the signal or energy it generates, the determination of a measurement of the force applied by the cyclist along this axis.In this configuration, knowledge of the orientation of the pedal body 20 relative to the crank 102, particularly with the help of a sensor for this orientation, makes it possible to determine a useful applied force from, for example, only the measurement of said transducer 70. The other transducers positioned around the axis can allow the measurement to be adjusted if the applied force is not perpendicular to the support surface 22. However, the invention is not limited to such positioning of one of the transducers and, as in the cases described above, the transducers 70 could be in any orientation.

[0129] In an alternative not shown, the connecting element may include a single transducer between the pedal body and the bearing. The latter is advantageously positioned to measure a force perpendicular to the bearing surface 22, as explained previously. In this case, the bicycle pedal may include, as described previously, a sensor for the orientation of the pedal body 20 relative to the pedal axle 30 or the crank 102. Thus, the signal generated by the transducer coupled with The orientation of the pedal body 20 allows for a meaningful measurement of the effort. Indeed, the cyclist applies pressure to the pedal body primarily perpendicular to the contact surface. It is therefore also possible to determine the useful effort by correlating the measurement with the orientation of the pedal body 20 relative to the crank arm 102 or the pedal axle 30.

[0130] The bicycle is not described. However, the bicycle pedal is mounted in the conventional manner on the crank.

[0131] The invention is not limited to the examples just described. The embodiments can be combined with each other when they are compatible.

[0132] For example, the transducers 70 can be distributed around the pedal axis on the connecting member and the additional connecting member, with different orientations. Thus, it is possible to obtain measurements with both the connecting member and the additional connecting member.

Claims

Demands

1. Bicycle pedal comprising: - A pedal axle (30), - A pedal body (20) comprising at least one bearing face (22) on which a cyclist is likely to exert a radial force on the pedal axle (30), - At least one linking member (50) mechanically connecting the pedal body (20) to the pedal axle (30) comprising: • a mechanical bearing (60) having an inner ring (62) fixed relative to the pedal axle (30) and an outer ring (64) fixed relative to the pedal body (20), • at least one piezoelectric transducer (70) extending between the mechanical bearing (60) and one of the pedal axle (30) and the pedal body (20).

2. Pedal according to claim 1, wherein at least one piezoelectric transducer (70) is configured to generate an electrical signal when it undergoes stress along an axis radial to the axis of the pedal (30), the at least one piezoelectric transducer (70) being configured so that the generated signal is proportional to the stress experienced when a force is exerted by the cyclist on the pedal body (20).

3. Pedal according to claim 1 or 2, wherein at least one connecting member (50) comprises a plurality of piezoelectric transducers (70) extending between the mechanical bearing (60) and one of the pedal axle (30) and the pedal body (20) being distributed around the pedal axle (30), in particular substantially uniformly distributed around the pedal axle (30)

4. Pedal according to the preceding claim, wherein at least two of the piezoelectric transducers (70) are arranged around the pedal axle (30) to generate a signal when subjected to stresses along different radial axes.

5. A pedal according to any one of the preceding claims, wherein the or at least one of the piezoelectric transducers (70) is configured to emit a signal when subjected to stress along a radial axis perpendicular to the bearing surface (22), regardless of the position of the pedal (10), the piezoelectric transducer(s) (70) being arranged tangentially between the pedal body (20) and the mechanical bearing (60).

6. Pedal according to any one of claims 1 to 4, wherein the piezoelectric transducer(s) (70) extend between the mechanical bearing (60) and the pedal axle (30) and the or at least one of the piezoelectric transducers (70) is oriented to generate a signal when subjected to stress in a direction perpendicular to the crank (102) after the pedal axle (30) is fixed to the latter.

7. Pedal according to any one of the preceding claims, wherein the piezoelectric transducer(s) (70) are of a thickness less than or equal to 5 mm, or even better less than or equal to 2 mm.

8. Pedal according to any one of the preceding claims, wherein the piezoelectric transducer(s) (70) are configured to generate an electrical power greater than 1 pW, preferably greater than 10 pW, in particular an energy greater than or equal to 1 OpJ per pedal revolution (10).

9. Pedal according to any one of the preceding claims, wherein the total volume of piezoelectric material of the junction member (50) distributed over the piezoelectric transducer(s) (70) can be between 50 mm3 and 250 mm3, preferably between 60 mm3 and 150 mm3.

10. Pedal according to any one of the preceding claims, wherein at least one connecting member (50) comprises an adapter spacer (80) extending between the mechanical bearing (60) and the piezoelectric transducer(s) (70) configured to allow the piezoelectric transducer(s) (70) to be fixed to the mechanical bearing (60), in particular to be able to connect the flat surface (72) of the piezoelectric transducers (70) to a cylindrical surface (63, 65) of the inner ring (62) or of the outer ring (64), the adapter spacer (80) comprising in particular a circular cross-section surface (82) for contacting one of the rings of the bearing (60) and flat platforms (85) on the opposite surface (84) for fixing the piezoelectric transducer(s) (70).

11. Pedal according to any one of the preceding claims, comprising an electronic processing circuit (90) configured to receive the signal generated by the piezoelectric transducer (70) or the signals generated by the electronic transducers (70) and / or the energy generated by the piezoelectric transducer(s) (70) when a force is applied by the cyclist on the pedal body (20) and to deduce at least one piece of information on the force applied by the cyclist on the pedal body (20) or to transmit the information to an external electronic device configured to deduce at least one piece of information on the force applied by the cyclist on the pedal body (20).

12. Pedal according to the preceding claim, wherein the electronic processing circuit (90) comprises an electronic measuring unit (92) configured to receive the signal generated by the piezoelectric transducer (70) or the signals generated by the piezoelectric transducers (70) and / or information on the energy generated by the piezoelectric transducer(s) (70) and to deduce for the signal or each signal generated by the transducer(s) (70) or from the information on the energy generated a value of the force measured along the radial axis corresponding to the piezoelectric transducer(s) (70).

13. Pedal according to the preceding claim, wherein the unit of measurement (92) is configured to determine the value of the useful effort, i.e. the effort applied by the cyclist on the pedal (10) along a useful axis perpendicular to the crank (102) after fixing the pedal axle (30) on the crank (102) and / or information on the useful effort applied over one pedal revolution (10), in particular the useful power generated during one pedal revolution (10) from the energy or signal or signals generated by the piezoelectric transducer(s) (70).

14. Pedal according to any one of claims 11 to 13, wherein the electronic processing circuit (90) may include a communication unit (94) configured to transmit to an external device the signal(s) generated by the piezoelectric transducer(s) (70), in particular in the absence of an internal measuring unit, and / or the information(s) on the effort applied by the cyclist to the pedal body (20), in particular in the presence of an internal measuring unit (92) in the bicycle pedal (10).

15. Pedal according to any one of the preceding claims, comprising at least one additional connecting member (150) mechanically connecting the pedal body (20) to the pedal axle (30) and spaced from the connecting member (50) along the pedal axle (30), the additional connecting member (150) comprising a mechanical bearing (60) having an inner ring (62) fixed relative to the pedal axle (30) and an outer ring (64) fixed relative to the pedal body (20), the additional connecting member (150) preferably comprising one or more piezoelectric transducers (70) extending between the mechanical bearing (60) and one of the pedal axle (30) and the pedal body (20).

16. Bicycle comprising at least one pedal (10) according to any one of the preceding claims.

17. Method for measuring the effort exerted by a cyclist on a bicycle pedal (10) according to any one of claims 1 to 15, comprising the analysis of the electrical signals and / or energy generated by the piezoelectric transducer(s) (70).

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