Automatic transmissions and methods therefor
View Patent ↗Systems and methods for controlling transmissions and associated vehicles, machines, equipment, etc., are disclosed. In one case, a transmission control system includes a control unit configured to use a sensed vehicle speed and a commanded, target constant input speed to maintain an input speed substantially constant. The system includes one or more maps that associate a speed ratio of a transmission with a vehicle speed. In one embodiment, one such map associates an encoder position with a vehicle speed. Regarding a specific application, an automatic bicycle transmission shifting system is contemplated. An exemplary automatic bicycle includes a control unit, a shift actuator, various sensors, and a user interface. The control unit is configured to cooperate with a logic module and an actuator controller to control the cadence of a rider. In one embodiment, a memory of, or in communication with, the control unit includes one or more constant cadence maps that associate transmission speed ratios with bicycle speeds.
1. A method of automatically controlling a ball-planetary continuously variable transmission mounted in a wheel of a bicycle, the method comprising:
receiving an input associated with a target user pedaling speed;
determining a speed of the bicycle;
determining a target transmission ratio based at least in part on the target user pedaling speed and the determined speed of the bicycle;
providing a reversible motor configured for adjusting a transmission ratio of the transmission to be substantially equal to the target transmission ratio, wherein adjusting the transmission ratio is characterized by rotating a shift rod of the transmission; and
adjusting the transmission ratio of the transmission to maintain a user pedaling speed within a band of the target user pedaling speed based upon the target user pedaling speed and the determined speed of the bicycle, wherein the band comprises the target user pedaling speed plus or minus 10 revolutions-per-minute (rpm).
2. The method of claim 1 , further comprising the step of determining an encoder position associated with the target user pedaling speed.
3. The method of claim 1 , wherein adjusting a transmission ratio comprises commanding the reversible motor to move to the determined encoder position.
4. The method of claim 1 , wherein the band comprises the target user pedaling speed in the range of about +/−5 rpm.
5. The method of claim 1 , wherein the band comprises the target user pedaling speed in the range of +/−2 rpm.
6. The method of claim 1 , wherein adjusting a transmission ratio of the transmission comprises the step of determining an encoder position associated with the target user pedaling speed and the determined speed of the bicycle.
7. The method of claim 1 , wherein adjusting a transmission ratio of the transmission comprises the step of commanding the reversible motor to move to the determined encoder position.
8. The method of claim 1 , wherein adjusting a transmission ratio of the transmission comprises the step of adjusting a shift rod of the transmission.
9. A system for automatically adjusting a transmission ratio of a bicycle transmission having a plurality of tiltable power transmitting balls, the transmission mounted in a wheel of a bicycle, the system comprising:
a speed sensor configured to detect a speed of the bicycle;
a control unit configured to receive input from the speed sensor;
a data input interface configured to provide cadence data to the control unit, the cadence data indicative of a desired, constant input pedaling speed;
a memory in communication with the control unit, the memory having stored therein one or more data structures correlating bicycle speeds with speed ratios, wherein the control unit is configured to determine from the one or more data structures a target speed ratio based on the speed of the bicycle and the cadence data; and
a reversible motor configured to selectively tilt the power transmitting balls of the transmission, in communication with the control unit, the reversible motor configured to adjust the transmission ratio of the bicycle transmission to maintain a user pedaling speed within a band of the desired, constant, input pedaling speed based upon the desired, constant input pedaling speed and the detected speed of the bicycle, wherein the band comprises the desired, constant input pedaling speed plus or minus 10 revolutions-per-minute (rpm).
10. The system of claim 9 , wherein the control unit comprises at least one of a processor, an application specific integrated circuit, or a programmable logic array.
11. The system of claim 9 , wherein the data input interface comprises a display and at least one button.
12. The system of claim 9 , wherein the band comprises the desired, constant input pedaling speed in the range of about +/−5 rpm.
13. The system of claim 9 , wherein the band comprises the desired, constant input pedaling speed in the range of +/−2 rpm.
14. The system of claim 9 , further comprising the step of determining an encoder position associated with the cadence.
15. The system of claim 14 , wherein adjusting the transmission ratio comprises commanding the reversible motor to move to the determined encoder position.
16. The system of claim 9 , wherein adjusting the transmission ratio of the bicycle transmission comprises the step of adjusting a shift rod of the transmission.