Electric drive for bicycles

• US 9,242,698 B2
• Filed: 03/25/2013
• Issued: 01/26/2016
• Est. Priority Date: 04/03/2012
• Status: Active Grant

• Current Assignee: Velogical Engineering GmbH
• Original Assignee: Velogical Engineering GmbH
• Inventors: Frieden, Peter
• Primary Examiner(s): Rocca, Joseph
• Assistant Examiner(s): STABLEY, MICHAEL R
• Application Number:
  US14/384,601
• Publication Number:
  US 20150041234A1
• Time in Patent Office: 1,037 Days
• Field of Search: 180/206.8
• US Class Current: 1/1
• CPC Class Codes: B62M 13/04 with means for moving roller into driving contact with ground wheel
• CPC Class Codes: B62M 6/75 power-driven by friction rollers or gears engaging the ground wheel
• CPC Class Codes: B62M 7/12 with the engine beside or within the driven wheel

Abstract

The invention relates to an electric drive for bicycles, comprising two symmetrically arranged external-rotor type counter-rotating motors which are fed via two separate motor actuators/regulators that obtain the same control signal for power regulation purposes. The motors are mounted in an oscillating manner about an axis which is parallel, in particular substantially parallel, to the motor axis but offset with respect to the motor axis in a lateral manner, in particular in a parallel manner.

Claims

1. A drive for a bicycle adapted to move in a travel direction and having a frame and a wheel rotatable about a wheel axis on the frame and having a rim and a tire on the rim, the drive comprising:

two symmetrically arranged counter-rotating motors flanking the wheel and each having an external rotor that rotates an elastic friction ring engageable with a respective flank of the rim about a respective motor axis;

respective mounts secured to the frame and each carrying a respective one of the motors for pivoting of the motors about swing axes spaced rearwardly in the direction from and generally parallel to the respective motor axes, each motor axis and the respective swing axis forming a plane extending at an angle of less than 45°

to the wheel axis such that the ring presses against the rim with a force F_a greater than a transmitted force F_u.

2. The bicycle drive defined in claim 1, wherein the mounts and motors symmetrically flank the wheel.

3. The bicycle drive defined in claim 1, wherein each motor axis intersects the wheel axis and each rim flank is frustoconical and centered on the respective wheel axis.

4. The bicycle drive defined in claim 1, wherein the motors are between the rim and the wheel axis.

5. The electric drive according to claim 1, wherein the external rotor of each motor is formed with an annular groove or recess for accommodating the respective elastic friction ring under tension.

6. The electric drive for a bicycle according to claim 1, further comprising:

a respective stop on the frame limiting a maximum possible spacing between each elastic friction ring and the rim in an idling position.

7. The electric drive for a bicycle according to claim 1, wherein each external rotor is provided with radial air channels that generate a stream of cooling air through the respective motor as a result of centrifugal action.

8. The electric drive for a bicycle according to claim 1, wherein each motor has:

a winding and stator packet impregnated or coated with a temperature-resistant plastic resin or lacquer, and

encapsulated ball bearings, each elastic ring consisting of material resistant to abrasion, ozone and UV light.

9. The electric drive for a bicycle according to claim 1, further comprising:

a flexible fastening system for retrofitting on different bicycle types, with an exact tangential alignment of the rotors being adjustable.

10. The electric drive for a bicycle according to claim 1, wherein the swing axes are fixed relative to the forks or, in the case of a rear-wheel drive, in the seat or chain stays.

11. The electrical drive for a bicycle according to claim 1, wherein each motor has a housing and a stiff, one-sided, asymmetrical motor support as an extension arm to accommodate the swing axis and that is equipped with cooling fins and/or a one-piece die-cast part.

12. The electric drive according to claim 1, wherein a coefficient of friction between each elastic ring and the rim is raised by the surface treatments or surface coatings of the respective rim flank in order to achieve a reduction of a contact pressure and an increase in a tilt/wedge angle.

13. The electric drive for a bicycle according to claim 1, further comprising:

a respective adjustable spring element for raising or balancing out a weight of each of the motors, when mounted on a rear wheel with a diagonal axis of swing.

14. The electric drive for a bicycle according to claim 1, further comprising:

a respective electromagnet for augmenting a swinging motion of each of the motors from an idling position into a working position and for increasing a contact pressure of the motor onto the rim.

15. The electric drive for a bicycle according to claim 1, further comprising:

a rechargeable battery or holder therefor fastened to the frame.

16. The electric drive for a bicycle according to claim 1, wherein one of the two motors can be adjusted by spring tension and works permanently or intermittently as a dynamo.