Bicycle drive unit
A bicycle drive unit basically has a transmission, a motor and a resultant force member. The motor is configured to transmit rotation to the transmission, and a resultant force member to which rotation from the transmission and from the manual drive force is transmitted. The transmission has a first sun gear, a second sun gear, a first ring gear, a second ring gear, a first planetary gear, a second planetary gear and a third planetary gear. The first, second and third planetary gears are separate individual gears. The first planetary gear is engaged with the first sun gear and the first ring gear. The second planetary gear is engaged with the second sun gear and the third planetary gear. The third planetary gear is engaged with the second planetary gear and the second ring gear.
1. A bicycle drive unit comprising:
a transmission;
a motor configured to transmit rotation to the transmission; and
a resultant force member to which rotation is transmitted from the transmission and to which rotation by a manual drive force is transmitted,
the transmission comprising a first sun gear, a second sun gear, a first ring gear, a second ring gear, a first planetary gear, a second planetary gear and a third planetary gear, the first, second and third planetary gears being separate individual gears,
the first planetary gear being engaged with the first sun gear and the first ring gear,
the second planetary gear being engaged with the second sun gear and the third planetary gear, and
the third planetary gear being engaged with the second planetary gear and the second ring gear.
2. The bicycle drive unit according to claim 1 , wherein
the resultant force member is provided around a rotational axis of a crankshaft, and is configured to be rotated around the rotational axis of the crankshaft.
3. The bicycle drive unit according to claim 1 , further comprising
a transmitting member configured to transmit rotation of the motor to the first sun gear and the second sun gear.
4. The bicycle drive unit according to claim 3 , wherein
the transmitting member further comprises an output shaft of the motor.
5. The bicycle drive unit according to claim 3 , wherein
the transmission further comprises a first one-way clutch and a second one-way clutch;
the first one-way clutch is configured to transmit rotation of the transmitting member to the first sun gear while the transmitting member is rotated in a first rotational direction, and uncouple the transmitting member from the first sun gear so as to not transmit rotation of the transmitting member to the first sun gear while the transmitting member is rotated in a second rotational direction that is opposite the first rotational direction; and
the second one-way clutch is configured to transmit rotation of the transmitting member to the second sun gear while the transmitting member is rotated in the second rotational direction and uncouple the transmitting member from the second sun gear so as to not transmit rotation of the transmitting member to the second sun gear while the transmitting member is rotated in the first rotational direction.
6. The bicycle drive unit according to claim 1 , wherein
the first sun gear and the second sun gear rotate around a common axis.
7. The bicycle drive unit according to claim 1 , wherein
the first sun gear and the second sun gear are integrally formed.
8. The bicycle drive unit according to claim 1 , wherein
a total number of teeth on the first ring gear and a total number of teeth on the second ring gear are equal.
9. The bicycle drive unit according to claim 1 , wherein
a total number of teeth on the first sun gear and a total number of teeth on the second sun gear are equal,
a total number of teeth on the first planetary gear and a total number of teeth on the second planetary gear are different, and,
a total number of teeth on the first planetary gear and a total number of teeth on the third planetary gear are different.
10. The bicycle drive unit according to claim 1 , wherein
the third planetary gear is arranged so that the entirety of the teeth on the third planetary gear mesh with the second ring gear in a direction along a rotational axis of the second sun gear.
11. The bicycle drive unit according to claim 1 , wherein
the second planetary gear is arranged so that the entirety of the teeth on the secondary planetary gear mesh with the third planetary gear in a direction along a rotational axis of the second sun gear.
12. The bicycle drive unit according to claim 1 , wherein
the first planetary gear is arranged closer to the motor than the second planetary gear and the third planetary gear with respect to a direction along a rotational axis of the first sun gear.
13. The bicycle drive unit according to claim 1 , wherein
the transmission further comprises a carrier that rotatably supports the first planetary gear, the second planetary gear and the third planetary gear; and
the resultant force member is coupled to the carrier.
14. The bicycle drive unit according to claim 1 , further comprising
a housing supporting the transmission, and
the first ring gear and the second ring gear being non-rotatable with respect to the housing.
15. The bicycle drive unit according to claim 1 , further comprising
a speed reducer configured to reduce a rotational output speed of the transmission and transmit the rotational output speed of the transmission to the resultant force member.
16. The bicycle drive unit according to claim 1 , further comprising
a controller configured to control the motor.
17. The bicycle drive unit according to claim 16 , wherein
the controller is configured to control the motor according to a manual drive force and a rotational speed of a crank.
18. The bicycle drive unit according to claim 17 , wherein
the controller is configured to control the motor so that the motor rotates in a first rotational direction while the rotational speed of the crank is less than a prescribed rotational speed, and control the motor so that the motor rotates in a second rotational direction while the rotational speed of the crank is greater than or equal to the prescribed rotational speed.
19. The bicycle drive unit according to claim 3 , further comprising
a crankshaft and the resultant force member being provided around a rotational axis of the crankshaft and configured to be rotated around the rotational axis of the crankshaft.