Pedal drive with at least one force sensor for measuring the pedal force on the pedal drive

Abstract

The present invention relates to a pedal drive (1) with at least one force sensor (10) for measuring the pedal force on the pedal drive (1), wherein the force sensor (10) comprises a holding profile (101) which is designed to bear against the outer wall (112) of the bearing housing (11), wherein an activation profile (102) is arranged or formed on the holding profile (101), which extends between the holding profile (101) and a pressure profile (103) located between the holding profile (101) and the receptacle (110), wherein the force sensor (10) comprises a profile receptacle (1020) for the activation profile (102), on which the activation profile (102) is movably received, wherein the force sensor (10) is designed,that by deformation and / or movement of the pressure profile (103), the activation profile (102) is moved on its side (1021) opposite the profile holder (1020) of the activation profile (102) and the sensor system (100) is triggered by the movement (SB) of the activation profile (102).

Description

[0001] The present invention relates to a pedal drive with at least one force sensor for measuring the pedal force on the pedal drive according to the preamble of patent claim 1.

[0002] When riding a Pedelec (pedal electric cycle), the rider only receives assistance from an electric motor when the cyclist is pedaling. A natural riding experience with a Pedelec is only possible when the assistance from the electric motor adapts to the rider's pedaling force. This requires determining the cyclist's pedaling force and torque.

[0003] There are various methods for determining the cyclist's pedaling force, torque, or torque. The torque generated by pedaling on the drive shaft is often measured using magnetic sensors. This measures the magnetic field change caused by surface changes on magnetized shaft surfaces. The torques are proportional to the strength of the magnetic field changes.

[0004] Representative publications include DE 10 2014 219 336 B3 and EP 3 364 163 B1. The state of the art in this field is the measurement of the shaft's surface twist using strain gauges. The measurement method described in CA 2 426 109 A1 further describes a method in which the slight bending caused by the chain tensile force is measured at a weakened point on the rear axle's shaft surface using strain gauges.

[0005] DE 10 2020 134 254 A1 discloses a pedal drive with a force sensor for measuring pedal force. The force sensor is arranged on the side of a component of the pedal drive, the bearing housing, the bottom bracket, the bottom bracket spindle, or the drive blade that is in the direction of the tensile force or opposite thereto. The force sensor determines the tensile force exerted by the tensioned chain or belt on the component of the pedal drive, the bearing housing, the bottom bracket, the bottom bracket spindle, or the at least one drive blade by determining the tensile or compressive force exerted on the force sensor. Furthermore, a receiving area for the force sensor is formed on the bearing housing, at least in one sensor section, which extends from the central receptacle to an outer wall of the bearing housing formed on the outer circumference of the receiving area.

[0006] Because some manufacturers select very hard material for the shaft, surface twist is so minimal that measuring surface deflection is either almost impossible or very complex. The use of expansion joints is particularly difficult to repair. A defective expansion joint is very difficult to replace, especially if the joint is glued to the shaft, which is integrated into the electric motor.

[0007] From WO 2010 / 022 578 A1, a pedal torque sensor system for an electric bicycle is known, in which the outer circumference of a sprocket of a planetary group is rotatably connected to the housing of a support body, wherein the force sensor is arranged between the projection of the outer circumference of the sprocket and a housing of the support body and transmits a signal to a microprocessor connection which controls the operating parameters of the electric motor.

[0008] US 2002 / 0 173 397 A1 describes a torsion sensor device for electric bicycles, in which the torsion of the pedaling force is transmitted through the swing arm of the planetary gear system, and the absolute angular displacement of the swing arm is measured by a sensor device to further control the drive device to output power to rotate the wheels. When the crankshaft is rotated by the rider's pedaling force, a swing arm generates rotational rotation, and the sensor device detects the torsion value to control the power output of the drive motor.

[0009] DE 10 2013 220 871 A1 further describes a method for measuring a torque applied by a rider to the pedals of an electric bicycle, in which the force acting on the chain of the electric bicycle is determined by measuring the elastic deformation / deflection of the bottom bracket and / or wheel hub fastening and the applied torque is determined therefrom; it is preferably provided that the deformation / deflection measurement is carried out magnetically.

[0010] DE 10 2021 003 644 B3 describes an electric auxiliary drive for a bicycle, in particular a pedelec, in which the torque transmitted to a rotor is determined by means of a sensor device having a magnetostrictive sensor positioned and configured to measure a torque-induced magnetic flux at the magnetostrictive region in a contactless manner.

[0011] DE 10 2023 204 926 A1 describes an arrangement for detecting a bearing force of a bottom bracket of a bicycle. The bearing support comprises a bearing receptacle that at least partially surrounds the bottom bracket in a ring-shaped manner, wherein a radially bendable bending beam is formed on the bearing receptacle. To detect the bearing force, a bearing force sensor is configured to detect the deformation of the bending beam, and a detection unit is further configured to detect a bearing force at the bottom bracket based on the deformation of the bending beam detected by the bearing force sensor.

[0012] Finally, WO 2021 / 031 887 A1 discloses a sensor for determining pedaling force on an electric bicycle. It is hinged to the bottom bracket at one end and to the frame at the other. The sensor, a frame, and the bottom bracket form a triangular structure.

[0013] Measuring torque by changing a magnetic field requires magnetizing the material at the measured point. These external magnetic fields can interfere with the measurement results. Furthermore, if the measuring points themselves are mounted on rotating components, the measurement signals must be transmitted wirelessly. This, in turn, requires a local power supply, which complicates the process.

[0014] The present invention is based on the object of creating a pedal drive by means of which the pedal force on a pedal drive, in particular on a pedelec, can be measured using a force sensor and which simultaneously optimizes existing systems. According to the invention, the above object is achieved according to the preamble of claim 1 in conjunction with the characterizing features. Advantageous embodiments and further developments of the pedal drive according to the invention are specified in the dependent subclaims.

[0015] The pedaling forces, which are alternately transferred from the rotating cranks on both sides to the bottom bracket spindle, drive the drive gear (preferably a chainring) connected to the bottom bracket spindle. The drive gear uses this force to pull the chain. In the example of a pedelec, the rear wheel is driven by the chain's tensile force via a chainring attached to the rear wheel. Whenever pedaling force is applied, the chain must be taut to transmit the power.

[0016] The tensioned chain in turn exerts a tensile force on the chainring or further on the bottom bracket spindle or further on the bottom bracket or further on the bearing housing of the pedal drive according to the invention, which has the effect that the pressure profile of the force sensor is acted upon and deformed accordingly, that the activation profile of the sensor or the sensor approaches or moves away and thereby activates the sensor, whereby for example the output voltage of the sensor, which is preferably designed as a Hall sensor, changes from 1-3V, for example, depending on how heavily the pedal is loaded.

[0017] This force is measured by the force sensor, which in a preferred embodiment of the invention is advantageously arranged in the bearing housing at the point where the force is applied. The forces measured here are proportional to the pedal forces.

[0018] The force sensor outputs the measurement result, preferably as an electrical signal in ohms, which can be converted into electrical voltage values using a converter. The motor control unit receives these values and controls the electric motor accordingly.

[0019] The present invention eliminates the need for measurements on the surface of the drive shaft. Handling and mounting the force sensor are also significantly easier than, for example, using strain gauges. Since the force sensor is preferably housed in the bearing housing, and the bearing housing is not a rotating part, it is possible to transmit the measurement results to the controller via cable. Signal transmission via Bluetooth or a local power supply is therefore not required, but is of course possible.

[0020] Further objects, features, advantages and possible applications of the pedal drive according to the invention will become apparent from the following description of exemplary embodiments with reference to the drawing.

[0021] The drawing shows Fig. 1 shows the pedal drive according to the invention in a preferred embodiment of the invention in a side view, broken open.

[0022] As from Fig. 1, the pedal drive 1 according to the invention comprises at least one force sensor 10 for measuring the pedal force on the pedal drive 1, wherein the pedal drive 1 comprises at least one bearing housing 11 with a central receptacle 110 for a bottom bracket 2.

[0023] The force sensor 10 comprises a sensor system 100 which is designed to determine the tensile force K exerted on the bearing housing 11 by a tensioned chain or a belt by determining the tensile or compressive force exerted on the force sensor 10, wherein a receiving area 111 for the force sensor 10 is formed on the bearing housing 11 at least in one sensor section SA, which receiving area extends from the central receptacle 110 to an outer wall 112 of the bearing housing 11 formed on the outer circumference U of the receiving area 111.

[0024] The pedal drive 1 according to the invention is characterized in that a) the force sensor 10 comprises a holding profile 101 which is designed to bear against the outer wall 112 of the bearing housing 11, wherein b) an activation profile 102 is arranged or formed on the holding profile 101, which extends between the holding profile 101 and a pressure profile 103 located between the holding profile 101 and the receptacle 110, wherein c) the force sensor 10 comprises a profile receptacle 1020 for the activation profile 102, on which the activation profile 102 is movably received, wherein d) the force sensor 10 is designed such that by deformation and / or movement of the pressure profile 103 in the direction of the activation profile 102, the activation profile 102 on its side 1021 opposite the profile receptacle 1020 of the activation profile 102 in the direction of the outer wall 112 of the bearing housing 11 is moved and the sensor 100 is triggered by the movement SB of the activation profile 102.

[0025] With regard to feature d), the activation profile 102 can be arranged on the force sensor 10, for example by means of the profile holder 1020, in such a way that the activation profile 102 is moved on its side 1021 opposite the profile holder 1020 of the activation profile 102 by deformation and / or movement of the pressure profile 103 (for example, in the direction of the activation profile 102). It is also advantageous that the activation profile 102 is moved in or opposite the direction of the outer wall 112 of the bearing housing 11.

[0026] As from Fig. As can be seen in Figure 1, in a particularly advantageous embodiment of the invention, the force sensor 10 is formed from a single molded body 104, which comprises the holding profile 101 and the pressure profile 103, and on which the activation profile 102 is pivotally mounted. The sensor bearing housing 11 is preferably made of aluminum and is screwed, for example, on the left side into the bottom bracket mount of the bicycle frame instead of the original bearing shell from well-known manufacturers. In this preferred example, the thread is 1.37×24 tpi×22mm, the shell has an outer diameter of 70mm, and the shell has an inner diameter of 66mm.

[0027] Within the sensor section SA, a profile receptacle 1040 can advantageously be formed on the molded body 104, within which the activation profile 102 is pivotably received. This profile receptacle 1040, which borders the pressure profile 103, is designed to provide sufficient space for the activation profile 102 to perform the described movement.

[0028] A recess 1041 for the bottom bracket 2 is advantageously formed on the shaped body 104, wherein the pressure profile 103 extends at least partially from the recess 1041 in the direction of the profile receptacle 1040.

[0029] The activation profile 102 can - as can be seen from Fig.1 - for example, it can be elongated and / or lever-like and preferably extend in its longitudinal direction from the profile receptacle 1020 of the activation profile 102 in the direction of the sensor system 100. Furthermore, all other conceivable shapes are also possible.

[0030] The sensor system 100 is preferably accommodated on and / or within the recess 1041 to effectively ensure correspondence with the activation profile 102.

[0031] The sensor system 100 advantageously comprises an element that corresponds to the activation profile 102 and further comprises an electronic system by means of which the signal of the element is converted into an electrical signal that can be further processed by an electronic system.

[0032] The element can comprise at least one haptic, capacitive, inductive, optical and / or magnetic sensor, wherein it is particularly advantageous that the activation profile 102 comprises at least one magnet.

[0033] In a particularly advantageous embodiment of the invention, the receiving area 111 for the force sensor 10 extends over the entire circumference of the bearing housing 11. List of reference numbers 1 pedal drive 2 bottom brackets 10 force sensor 11 Bearing housing 100 Sensors 101 Holding profile 102 Activation profile in activation position 102' activation profile in starting position 103 Pressure profile 104 molded bodies 110 central mount for bottom bracket 111 Mounting area on the bearing housing 112 Outer wall of the bearing housing 1020 Profile recording of the activation profile 1021 opposite page 1040 Profile holder on the mold body 1041 Recess on the molded body K Tensile force / direction SA sensor section on the bearing housing SB Swivel movement of the activation profile U Outer circumference of the bearing housing

Claims

[1] Pedal drive (1) with at least one force sensor (10) for measuring the pedal force on the pedal drive (1), wherein the pedal drive (1) comprises at least one bearing housing (11) with a central receptacle (110) for a bottom bracket (2), and the force sensor (10) comprises a sensor system (100) designed to determine the tensile force (K) exerted on the bearing housing (11) by a tensioned chain or belt by determining the tensile or compressive force exerted on the force sensor (10), wherein a receiving area (111) for the force sensor (10) is formed on the bearing housing (11) at least in one sensor section (SA), which receiving area extends from the central receptacle (110) to an outer wall (112) of the bearing housing (101) formed on the outer circumference (U) of the receiving area (111), characterized by , that a) the force sensor (10) comprises a holding profile (101) which is designed to bear against the outer wall (112) of the bearing housing (11), wherein b) an activation profile (102) is arranged or formed on the holding profile (101), which extends between the holding profile (101) and a pressure profile (103) located between the holding profile (101) and the receptacle (110), wherein c) the force sensor (10) comprises a profile holder (1020) for the activation profile (102), on which the activation profile (102) is movably received, wherein d) the force sensor (10) is designed such that the activation profile (102) is moved on its side (1021) opposite the profile holder (1020) of the activation profile (102) by deformation and / or movement of the pressure profile (103) and the sensor system (100) is triggered by the movement (SB) of the activation profile (102). [2] Pedal drive (1) according to claim 1, characterized bythat the force sensor (10) is formed from a single shaped body (104) which comprises the holding profile (101) and the pressure profile (103) and on which the activation profile (102) is pivotally received. [3] Pedal drive (1) according to claim 1 or 2, characterized by that within the sensor section (SA) on the shaped body (104) a profile receptacle (1040) is formed, within which the activation profile (102) is pivotably received. [4] Pedal drive (1) according to claim 3, characterized by that a recess (1041) for a bottom bracket (2) is formed on the shaped body (104), wherein the pressure profile (103) extends at least partially from the recess (1041) in the direction of the profile receptacle (1040). [5] Pedal drive (1) according to one of the preceding claims, characterized bythat the activation profile (102) is elongated and / or lever-like and extends in its longitudinal direction from the profile receptacle (1020) of the activation profile (102) in the direction of the sensor system (100). [6] Pedal drive (1) according to claim 4 or 5, characterized by that the sensor (100) is accommodated on and / or within the recess (1041). [7] Pedal drive (1) according to one of the preceding claims, characterized by that the sensor system (100) comprises an element which corresponds to the activation profile (102) and further comprises an electronic system by means of which the signal of the element is converted into an electrical signal which can be further processed by an electronic system. [8] Pedal drive (1) according to claim 7, characterized by that the element comprises at least one haptic, capacitive, inductive, optical and / or magnetic sensor. [9] Pedal drive (1) according to claim 8, characterized by that the activation profile (102) comprises at least one magnet. [10] Pedal drive (1) according to one of the preceding claims, characterized by that the receiving area (111) for the force sensor (10) extends over the entire circumference of the bearing housing (11).

Images