| 摘要 |
A two-speed gear ratio shifting mechanism in the driveline of an automotive vehicle, e.g. in a rear-axle differential, is constituted by planet gears 44, a planet carrier 46 and a sun gear 52, integral with a coupling sleeve 50, which is movable axially to connect the carrier to, or disconnect the carrier from, the planet gears to provide "direct drive" and "overdrive or underdrive". To assist synchronisation, the sun gear comprises alternating shorter and longer spline teeth 51, 53 which mesh with spline teeth on the carrier, and the engaging ends of the spline teeth have a complimentary frusto-conical shape. The sleeve is moved axially by a motor driven shift fork 62 via compression springs 64, 66, and when the rotational speeds are synchronised ball 68 snaps into groove 70. When the planet carrier is disconnected, teeth 54 on the coupling sleeve engage with fixed teeth on housing 34. The speeds of members 44, 46, 50 may be computer-controlled to assist synchronisation. |
