Cycloidal gear and electric bicycle drive unit with cycloidal gear

Patent metadata

Field	Value
Publication number	US-2025083769-A1
Application number	US-202418749280-A
Country	US
Kind code	A1
Filing date	Jun 20, 2024
Priority date	Jun 21, 2023
Publication date	Mar 13, 2025
Grant date	—

Abstract

A cycloidal gear, an electric bicycle drive unit with cycloidal gear, a freewheel device for the drive unit, and a tachometer sensor device for the drive unit is disclosed. The cycloidal gear comprises a drive shaft device, an cam arrangement and an output shaft device, as well as at least one cycloidal disk device with cycloidal tooth arrangements and at least one opposing cycloidal device with opposing tooth arrangements. At least one of the cycloidal tooth arrangements and/or at least one of the opposing cycloidal tooth arrangements has a relief contour that is setback in relation to the respective profile along a clearance cut area that is arranged outside a load flank sub-area of the respective profile.

First claim

What is claimed is:

1 . A cycloidal gear for an electric bicycle drive unit, the cycloidal gear comprising:
a drive shaft device with a cam arrangement, and an output shaft device, wherein the drive shaft device and output shaft device are arranged concentrically with respect to one another and with respect to a central axis of the cycloidal gear; and at least one cycloidal disk device having at least two approximately cycloidal or cylindrical cycloidal tooth arrangements, and at least one opposing cycloid device having at least two approximately cycloidal or cylindrical opposing tooth arrangements, wherein the at least one cycloidal disk device and the at least one opposing cycloidal device are configured for torque-transmitting, mutually positive-locking engagement, and wherein the at least one cycloidal disk device and/or the at least one opposing cycloidal device can be brought into an eccentric-cycloidal relative rolling motion relative to the central axis by means of the cam arrangement of a rotary drive, by means of which in contact areas of drive contact between cycloidal disk profiles of the cycloidal tooth arrangements of the at least one cycloidal disk device and opposing cycloidal profiles of the opposing tooth arrangements of the at least one opposing cycloidal disk device, driving forces can be transmitted in a circumferential direction of the cycloidal gear at least within a respective load flank sub-area of the respective profile of the respective tooth arrangement, wherein at least one of the cycloidal tooth arrangements or the opposing tooth arrangements has a relief contour that is setback relative to the profile along a clearance cut area that is arranged outside the respective load flank sub-area of the respective profile of the respective tooth arrangement.

2 . The cycloidal gear of claim 1 , wherein the relief contour forms a smooth transition at any one or both of transitions to the profile or transitions to the load flank sub-areas.

3 . The cycloidal gear of claim 1 , wherein an arc length of the relief contour, relative to the arc length of the profile, is between 60% and 85%.

4 . The cycloidal gear of claim 1 , wherein the cycloidal gear is a single-disk or a multi-disk cycloidal gear with one or more cycloidal disk devices and two opposing cycloidal devices.

5 . The cycloidal gear of claim 1 , wherein the cycloidal gear is a compur gear with at least one inner cycloidal disk device, at least one outer cycloidal disk device, and a cam disk that rotates eccentrically in a positive-locking manner with the profiles as an opposing cycloidal device between the profiles of the inner cycloidal disk device and the outer cycloidal disk device, wherein at least one of the inner cycloidal disk device and the outer cycloidal disk device is rotatable about the central axis of the cycloidal gear.

6 . The cycloidal gear of claim 1 , wherein the cycloidal gear is a cyclo-acbar transmission with at least two cycloidal disk devices, which are rotationally rigidly connected to one another, and two opposing cycloidal devices, wherein at least one of the opposing cycloidal devices is rotatable about the central axis of the cycloidal gear.

7 . The cycloidal gear of claim 4 , wherein the cycloidal gear has at least two cycloidal disk devices, wherein one of the opposing cycloidal devices forms a rotational output of the cycloidal gear, wherein the output is in engagement with a first cycloidal disk device, and a second opposing cycloidal device forms a torque opposing support which is in engagement with a second cycloidal disk device and is connected to a housing of the cycloidal gear.

8 . The cycloidal gear of claim 1 , wherein contact areas of at least one of the opposing tooth arrangements comprise polymer material to increase an elasticity in a torque transmission between the cycloidal disk device and the opposing cycloidal device.

9 . An electric bicycle drive unit for arrangement in a bottom bracket area of a bicycle frame, the drive unit comprising:
a bottom bracket shaft for mounting pedal cranks; an electric motor device with a stator device and a rotor assembly arranged on a rotor shaft, wherein the rotor shaft is arranged coaxially to the bottom bracket shaft; a freewheel arrangement with at least one freewheel device; a sensor arrangement with at least one sensor device; at least one electronics assembly for controlling the motor device and/or for processing signals from the sensor device; an output shaft for transmitting drive power to a bicycle power train; and a gear device with a cycloidal gear having at least one cycloidal disk device having at least two approximately cycloidal or cylindrical cycloidal tooth arrangements, and at least one opposing cycloid device having at least two approximately cycloidal or cylindrical opposing tooth arrangements, wherein at least one of the cycloidal tooth arrangements or the opposing tooth arrangements has a relief contour that is setback relative to a profile along a clearance cut area that is arranged outside a respective load flank sub-area of a respective profile of the respective tooth arrangement, wherein the cycloidal gear is encapsulated in a liquid-tight manner with respect to the motor device.

10 . The drive unit of claim 9 , wherein the cycloidal gear is encapsulated in an at least liquid-tight manner with respect to any combination of the motor device, freewheel arrangement, sensor arrangement and electronics assembly.

11 . The drive unit of claim 9 , wherein the rotor shaft is mounted exclusively in the cycloidal gear, and the rotor assembly is arranged on the rotor shaft in a region of a flying end of the rotor shaft.

12 . The drive unit of claim 11 , wherein a gear-side end of the rotor shaft is mounted inside a gearbox output shaft.

13 . The drive unit of claim 9 , further comprising:
an axial freewheel device with coupling elements for decoupling the output shaft from the gear device, wherein the axial freewheel device is disk-shaped and is configured so as to transmit a gearbox torque through the coupling elements in an axial direction, relative to the bottom bracket shaft.

14 . The drive unit of claim 13 , wherein at least one of the coupling elements of the axial freewheel device is a polymer material.

15 . The drive unit of claim 13 , wherein the axial freewheel device comprises a control device for active movement of the coupling elements depending on the direction of rotation.

16 . The drive unit of claim 13 , the drive unit further comprising:
a tachometer sensor device having a tachometer sensor element and a tachometer element connected to the bottom bracket shaft for contactless measurement of a speed of the bottom bracket shaft, wherein the tachometer element and the tachometer sensor element are arranged on opposite sides of a wall of an output shaft section through which a gearbox torque of the drive unit can flow.

17 . The drive unit of claim 16 , wherein the tachometer element is arranged in an inner area of the axial freewheel device.

18 . The drive unit of claim 9 , wherein one of the electronics assemblies comprises at least two of: a tachometer sensor device with a tachometer sensor element for measuring a speed of the bottom bracket shaft; a torque sensor device with a torque sensor element for measuring an elastic deformation of a deformation element of an output shaft section; and a tachometer sensor device with a tachometer sensor element for measuring a speed of a bicycle wheel.

19 . The drive unit of cla

Assignees

• Sram De Gmbh

Inventors

• Braedt Henrik
• Heyna Sebastian

Classifications

• B62M6/55

  power-driven at crank shafts parts · CPC title

• B62M6/50

  characterised by detectors or sensors, or arrangement thereof · CPC title

• B62M11/145 Primary

  built in, or adjacent to, the bottom bracket · CPC title

• B62J45/421

  at the pedal crank · CPC title

• B62J45/413

  Rotation sensors · CPC title