Speed Changing Transmission Apparatus

A speed changing transmission apparatus having an input shaft for inputting drive force from an engine and an output rotational body, wherein the drive force is provided in a plurality of stages of speeds, and in the range of each speed stage, the drive force steplessly speed changed being outputted from the output rotational shaft, said apparatus comprising:

• a stepless speed changing section inputting a drive force from an electric motor or an engine;
• a composite planetary transmission section having a downstream planetary transmission mechanism, the transmission section synthesizing output from said stepless speed changing section with an engine drive force not subjected to any speed changing action by said stepless speed changing section or synthesizing output from said electric motor with the drive force of the engine;
• a clutch section including a first clutch mechanism having an input side rotational member operably coupled to a ring gear included in said downstream planetary transmission mechanism and a second clutch mechanism having an input side rotational member operably coupled to a sun gear included in said downstream planetary transmission mechanism;
• a speed-reducing planetary transmission mechanism having a sun gear operably coupled to an output side rotational member each one of said first clutch mechanism and said second clutch mechanism and having also a carrier operably coupled to said output side rotational member;
• a brake mechanism switchable between an engaged state for applying a braking action to the ring gear of said speed-reducing planetary transmission mechanism and a disengaged state for releasing the braking action to said ring gear;
• an operable coupling clutch mechanism switchable between an engaged stage for operably coupling said ring gear and said carrier of said speed-reducing planetary transmission mechanism for rotating these together in unison and a disengaged state for disengaging the operable coupling between said ring gear and said carrier;
• and
• an output clutch mechanism for engaging/disengaging a drive force from said carrier of said planetary transmission section to said output rotational body;
• wherein said sun gear of the planetary transmission section, said input side rotational member of the first clutch mechanism, said input side rotational member of the second clutch mechanism, said sun gear of the speed-reducing planetary transmission mechanism, and said input side rotational member of the output clutch mechanism are arranged to be rotatable about a common rotational axis;
• and
• wherein a rotational shaft for operably coupling said carrier of the planetary transmission section to said output rotational body is arranged to be inserted through said downstream planetary transmission mechanism, said first clutch mechanism, said second clutch mechanism, and said speed-reducing planetary transmission mechanism.