Coupled planetary gearbox

A method of transmitting rotational speed, comprising:

• providing a first epicyclical gear set that includes a first sun gear, a first ring gear surrounding the first sun gear, a first planetary gear set that mechanically couples the first sun gear to the first ring gear, and a first planetary carrier connected to the first planetary gear set;
• providing a second epicyclical gear set that includes a second sun gear, a second ring gear surrounding the second sun gear, a second planetary gear set that mechanically couples the second sun gear to the second ring gear, and a second planetary carrier connected to the second planetary gear set;
• driving from an input shaft of a transmission:
• the first ring gear, thereby driving the first planetary gear set, and the first planetary carrier;
• and the second planetary carrier, thereby driving the second planetary gear set, and the second sun gear;
• driving, from the first planetary carrier, the second ring gear;
• and
• controlling a plurality of clutches in the transmission to engage the first epicyclical gear set and the second epicyclical gear set, thereby shifting the transmission between a plurality of transmission speeds that are respectively overlapping;
• wherein controlling the plurality of clutches includes one or more of:
• shifting a first clutch of the plurality of clutches between:
• a closed state, to rotationally couple an output shaft with the second sun gear;
• and an opened state to rotationally decouple the output shaft from the second sun gear;
• shifting a second clutch of the plurality of clutches between:
• a closed state to rotationally couple the output shaft with the second ring gear and the first planetary carrier;
• and an opened state to rotationally decouple the output shaft from the second ring gear and the first planetary carrier;
• shifting a third clutch of the plurality of clutches between:
• a closed state to rotationally brake the first sun gear;
• and an opened state to rotationally release from braking the first sun gear;
• shifting a fourth clutch of the plurality of clutches between:
• a closed state to rotationally brake the second ring gear and the first planetary carrier;
• and an opened state to rotationally release from braking the second ring gear and the first planetary carrier;
• wherein the method further comprises one or more of:
• generating a first transmission speed of the plurality of transmission speeds by:
• shifting the first clutch to the closed state;
• shifting the second clutch to the opened state;
• shifting the third clutch to the opened state;
• and shifting the fourth clutch to the closed state;
• generating a second transmission speed of the plurality of transmission speeds by:
• shifting the first clutch to the closed state;
• shifting the second clutch to the opened state;
• shifting the third clutch to the closed state;
• and shifting the fourth clutch to the opened state;
• generating a third transmission speed of the plurality of transmission speeds by:
• shifting the first clutch to the closed state;
• shifting the second clutch to the closed state;
• shifting the third clutch to the opened state;
• and shifting the fourth clutch to the opened state;
• generating a fourth transmission speed of the plurality of transmission speeds by:
• shifting the first clutch to the opened state;
• shifting the second clutch to the closed state;
• shifting the third clutch to the closed state;
• and shifting the fourth clutch to the opened state;
• and
• wherein:
• the first transmission speed and the second transmission speed overlap by a first overlapping speed range;
• the second transmission speed and the third transmission speed overlap by a second overlapping speed range that is broader than three times the first overlapping speed range;
• and
• the third transmission speed and the fourth transmission speed overlap by a third overlapping speed range that is broader than five times the first overlapping speed range.