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EP-4741788-A2 - EXTERNAL FORCE MEASUREMENT UNIT, MEASUREMENT METHOD, MOTOR UNIT AND ELECTRICALLY ASSISTED BICYCLE

EP4741788A2EP 4741788 A2EP4741788 A2EP 4741788A2EP-4741788-A2

Abstract

The invention relates to a motor unit for an electrically assisted bicycle, the motor unit having only one freewheeling device, and to an electrically assisted bicycle.

Inventors

  • HORNUNG, HEINZ

Assignees

  • TQ-Systems GmbH

Dates

Publication Date
20260513
Application Date
20220726

Claims (15)

  1. Motor unit (1) for an electric bicycle, the motor unit comprising - an electric motor (2), being configured to drive a driving element, - a spindle (10) being connectable to pedals, - a sprocket carrier (340), that is drivable in a drive direction by the driving element and by the spindle (10), and - an evaluation unit (8) being configured to detect rotation of the spindle (10) and/or a force or torque applied to the spindle (10) and rotation of the electric motor (2), and to energize the electric motor (2) to drive in a direction against the drive direction if the spindle (10) rotates against the drive direction, - wherein the motor unit (1) comprises only one single freewheeling device in the torque flow between the electric motor (2) and the spindle (10), and - wherein the spindle (10) is connected to the sprocket carrier (340) such that the spindle (10) and the sprocket carrier (340) have a fixed rotational relationship, - the motor unit (1) further comprising a gear that provides for a fixed rotational relationship with a transmission ratio between the electric motor (2) and the driving element.
  2. Motor unit (1) according to claim 1, - wherein the gear is arranged concentrically with the electric motor (2).
  3. Motor unit (1) according to one of the preceding claims, - wherein the freewheeling device is an overrunning clutch being embodied as a clamping roller free-wheel, allowing disengaging a driveshaft from a driven shaft.
  4. Motor unit (1) according to claim 3, - wherein the driven shaft is the spindle (10), and/or - wherein the driveshaft is the driving element.
  5. Motor unit (1) according to one of the preceding claims, - wherein the freewheeling device comprises a freewheel clutch having spring-loaded rollers inside a driven cylinder.
  6. Motor unit (1) according to one of the preceding claims, - wherein the gear is a pin-ring-gear.
  7. Motor unit (1) according to claim 6, - wherein the pin-ring-gear comprises an inner ring (313), a pin-ring (311), and an outer ring (312), which are arranged concentrically with the electric motor (2).
  8. Motor unit (1) according to one of the preceding claims, - wherein the freewheeling device comprises an inner part and an outer part, the inner part being form-fitted connected to the spindle to transfer force from the outer part to the spindle.
  9. Motor unit (1) according to one of the preceding claims, - wherein the freewheeling device allows faster rotation of the sprocket carrier (340) with respect to the driving element.
  10. Motor unit (1) according to one of the preceding claims, - wherein the evaluation unit (8) is configured to energize the electric motor (2) to compensate for a drag moment of the electric motor (2) when rotating against the drive direction.
  11. Motor unit (1) according to one of the preceding claims, - the motor unit (1) further comprising an external force measurement unit (4), and - the evaluation unit (8) being configured to measure the force or torque applied on the spindle (10) using the external force measurement unit (4).
  12. Motor unit (1) according to claim 11, wherein the external force measurement unit (4) comprises - a load cell (5) with a support ring (61), - wherein a first flap (62) and a second flap (65) are arranged on the support ring (61), wherein the second flap (65) is arranged opposite to the first flap (62) on the support ring (61), - wherein each flap (62, 65) is arranged in a radial direction to the outside of the support ring (61), - and a first flap end (63) and a second flap end (66) being arranged at respective ends of the first flap (62) and the second flap (64), - a first strain gauge (64), which is arranged on the first flap (62) and a second strain gauge (67), which is arranged on the second flap (65), wherein depending on a change of length of the first flap (62) or the second flap (65) due to a material expanding the first strain gauges (64) and/or the second strain gauge (67) is adapted to change their respective resistance.
  13. Motor unit (1) according to claim 12, - further comprising a motor housing (3), wherein the first flap end (63) and the second flap end (66) are adapted to mount the load cell (5) to a load cell carrier seat (51) on the motor housing (3) of the motor unit (1), and a second outer ring (91) is mounted to a second rolling support of the motor housing (3).
  14. Motor unit (1) according to one of the preceding claims, - further comprising an angular encoder (11) to determine a radial position of the spindle (10), - wherein the evaluation unit (8) is configured to determine the rotation of the spindle (10) using the angular encoder (11).
  15. Electrically assisted bicycle, comprising a motor unit (1) according to one of the preceding claims.

Description

The present application relates to an external force measurement system and measurement method as well as to a motor unit and an electrically assisted bicycle. It is an object of the present application to provide an improved external force measurement unit and measurement method. According to a first aspect, an external force measurement unit for measuring an external force applied to a spindle is provided. The external force measurement unit comprises a load cell with a support ring, wherein a first flap and a second flap are arranged on the support ring, wherein the second flap is arranged opposite to the first flap on the support ring, wherein each flap is arranged in a radial direction to the outside of the outer ring, and a first flap end and a second flap end being arranged at respective ends of the first flap and the second flap. The external force measurement unit further comprises a first strain gauge which is arranged on the first flap and a second strain gauge, which is arranged on the second flap, wherein depending on a change of length of the first flap or the second flap due to a material expand the first strain gauges and/or the second strain gauge is adapted to change their respective resistance. The external force measurement unit further comprises an evaluation unit, which is adapted to measure a resistance of the first strain gauge and the second strain gauge, which is further adapted to determine an offset of the external force being induced by the weight of the spindle, and which is further adapted to determine a position of a lever arm of the spindle and to determine the external force, which is applied to the adapted spindle based on the measured resistance and the determined offset of the first force. The external force measurement unit further comprises a first bearing support to take up a first bearing in a first bearing seat, the first bearing with a first outer ring, wherein the first outer ring is mounted to the first bearing seat to transmit a first force, wherein the external force comprises the first force, which is transmitted to the first bearing from the spindle to a first inner ring and a second force, which is absorbed by an adapted second bearing, and the first inner ring is connected to the first outer rolling ring through a first bearing element to transmit the first force from the adapted spindle. The external force measurement unit can be a system to measure a force that is applied from external. The external force measurement unit measures a change of resistance. Depending on the measured resistance the external force is calculated. The external force is applied to the external force measurement from outside of the unit. Mainly the external force can be applied by a human. For example, the external force is applied to the pedal of a bike by the foot of a person. The pedal can be part of a bike and can rotate. So, the external force is mostly applied perpendicular to the pedal. The spindle can be a shaft, a hollow shaft or a cylinder. The first bearing and the second bearing receive the spindle. The bearing is a machine element that constrains relative motion to only the desired motion and reduces friction between moving parts. The bearings can for example be a rolling-element bearing, a plain bearing, a ball bearing, a roller bearing, a jewel bearing, a fluid bearing, a magnetic bearing or a flexure bearing. The load cell with the support ring is a device to receive the bearing, for example, by an engineering fit. The load cell can be made of aluminum or steel or any other suitable material. The engineering fits are used as part of geometric dimensioning and tolerancing when a part or assembly is designed. A fit is a clearance between two mating parts, and the size of this clearance determines whether the parts can, at one end of the spectrum, move or rotate independently from each other or, at the other end, are temporarily or permanently joined. The bearing can be taken up in the first bearing seat of the support ring by fixed-lot bearing arrangement, where one of the bearings is movable and the other is fixed. The fixed bearing is mounted on the element to be supported in such a way that it cannot move in the axial direction. The locating bearing thus absorbs both radial and axial forces. The fit can also be a load-bearing support bearing, the axial force is divided between both bearings. Each of the two bearings absorbs axial force in one direction so that both bearings together can absorb all axial forces. The first flap and the second flap are elements arranged on the load cell. Each flap can also be named a tongue or a bracket. At least the flap can transfer a force in a predefined direction. The radial direction, in which the flap is arranged, is pointing from the center of the load cell to the outside. Both flaps can be arranged on each side on the ends of a line through the center. So, the flaps are on opposite sides of the load cell. The flaps can partl