Method for operating a drive assembly of an electric bicycle
A method of operating a drive assembly of an electric bicycle is disclosed, wherein the drive assembly has a drive unit and a shift control which can be actuated in a controlled manner. The method includes (i) determining a current drive load of the drive unit, (ii) increasing a motor speed of the drive unit in a controlled manner to an engagement speed at which the drive load reaches a predetermined engagement load, and (iii) performing controlled shifting via the shift control while operating the drive unit at a maximum of the engagement speed.
1 . A method of operating a drive assembly of an electric bicycle, wherein the drive assembly includes a drive unit and a shift control which is configured to be actuated in a controlled manner, comprising:
determining a current drive load of the drive unit;
increasing a motor speed of the drive unit in a controlled manner to an engagement speed at which the drive load reaches a predetermined engagement load;
determining a shift speed such that the shift speed is less than the engagement speed by a predetermined shift offset; and
shifting in a controlled manner using the shift control while the drive unit is in operation at the shift speed.
2 . The method according to claim 1 , wherein:
the predetermined shift offset is at least 5% and at most 30% of the engagement speed, or
the predetermined shift offset is at least 5 rpm and at most 30 rpm.
3 . The method according to claim 1 , further comprising:
operating the drive unit at the shift speed in a controlled manner for at least a predetermined period of time and/or for at least a predetermined number of revolutions.
4 . The method according to claim 1 , wherein the predetermined engagement load is:
a maximum of 15 Nm, and
at least 3 Nm.
5 . The method according to claim 1 , further comprising determining a target speed, wherein the motor speed is increased in a controlled manner by continuously increasing the target speed.
6 . The method according to claim 5 , further comprising:
limiting the target speed to maximum target speed, wherein the maximum target speed is determined based on a determined rear wheel speed and a determined current gear ratio.
7 . The method according to claim 5 , wherein a determined current motor speed, or the determined current motor speed minus a predetermined speed offset, or a predefined speed, or a determined rear wheel speed multiplied by a determined current gear ratio minus an offset, is initially set as the target speed.
8 . The method according to claim 5 , further comprising:
increasing the target speed in response to an end of a predetermined period of time, and/or in response to a predetermined sensor signal.
9 . The method according to claim 8 , wherein increasing of the target speed is stopped when the drive load reaches or exceeds a predetermined load threshold.
10 . The method according to claim 5 , further comprising resetting the target speed when at least one of:
a sensed cadence is greater than or equal to the current motor speed,
the motor speed is less than or equal to a predetermined threshold for at least a predetermined period of time,
the motor speed is equal to zero for at least a predetermined period of time, and/or
the motor speed remains at a value less than the target speed for at least a predetermined period of time.
11 . The method according to claim 1 , wherein determining the current drive load is based on an actuation signal and/or an actuation current for actuation of the drive unit and/or based on a rotor position signal of a rotor position sensor of a sensor unit of the drive unit.
12 . The method according to claim 1 , wherein the method is carried out during travel of the electric bicycle.
13 . A drive assembly of an electric bicycle, comprising:
a drive unit;
a shift system; and
a controller configured to operate the drive unit and the shift system,
wherein the controller is further configured to perform the method according to claim 1 .
14 . An electric bicycle comprising a drive assembly according to claim 13 .
15 . The method according to claim 1 , wherein the shift speed is always greater than 0 rpm.
16 . The method according to claim 1 , wherein:
the predetermined shift offset is at least 10% and at most 30% of the engagement speed, or
the predetermined shift offset is at least 10 rpm and at most 30 rpm.
17 . The method according to claim 1 , wherein the predetermined engagement load is:
a maximum of 5 Nm, and
at least 3 Nm.
18 . The method according to claim 5 , further comprising:
increasing the target speed in response to an end of a predetermined period of time, and/or in response to a revolution signal of a rotational speed sensor and/or a speed sensor.
19 . The method according to claim 1 , wherein the method is carried out during forward movement of the electric bicycle.
20 . A method of operating a drive assembly of an electric bicycle, wherein the drive assembly includes a drive unit and a shift control which is configured to be actuated in a controlled manner, comprising:
determining a current drive load of the drive unit;
determining a target speed;
increasing a motor speed of the drive unit in a controlled manner to an engagement speed at which the drive load reaches a predetermined engagement load, wherein the motor speed is increased in the controlled manner by continuously increasing the target speed in response to an end of a predetermined period of time and/or in response to a predetermined sensor signal, wherein increasing of the target speed is stopped when the drive load reaches or exceeds a predetermined load threshold; and
shifting in a controlled manner using the shift control while the drive unit is in operation at a maximum of the engagement speed.