Engine timing drive with fixed and variable phasing

A timing drive for an engine camshaft and an accessory both timed with a driving crankshaft and all having parallel axes wherein the drive provides variable phasing of the camshaft and constant phase driving of the accessory, said timing drive comprising

• a drive sprocket drivably connected with the crankshaft for rotation with the crankshaft on the crankshaft axis,
• a driven sprocket mounted for rotation on the camshaft axis and drivably connected with the drive sprocket to be driven thereby at a first drive ratio,
• a drive gear connected with the driven sprocket for rotation therewith on the camshaft axis,
• a driven gear drivably connected with the accessory for rotation on the accessory axis and drivably connected with the drive gear to be driven thereby at a second drive ratio, and
• a planetary drive train drivably connected between the driven sprocket and the camshaft for driving the camshaft at a third drive ratio,
• the planetary drive train including a ring gear connected with the driven sprocket for rotation therewith on the camshaft axis, a carrier connected with the camshaft for rotation therewith on the camshaft axis, and a plurality of planet gears rotatably supported by the carrier, the planet gears engaging the ring gear to thereby drive the carrier and the camshaft,
• the carrier further rotatably supporting the drive gear, the driven sprocket and the ring gear,
• the planetary drive train further including a sun gear coaxial with the ring gear and engaging the planet gears, the rotative position of the sun gear being adjustable to vary the phasing of the camshaft relative to the crankshaft.