Two speed transmission and belt drive system
View Patent ↗A two speed transmission and belt drive system utilizing the transmission. The two speed transmission comprises a planetary gear train comprising an input pulley connected to an input carrier, and a sun gear and a ring gear. The input carrier also comprises a plurality of planetary gears disposed between the sun gear and the ring gear. The sun gear is engaged with an electromagnetic brake member. The ring gear is engaged with an output pulley. A one-way clutch is disposed between the input carrier and the output shaft. The brake member is engaged at engine idle and is disengaged at engine speeds above idle. When the brake member is engaged the sun gear does not rotate, thereby driving the ring gear and output pulley at a greater speed than the input pulley. An accessory pulley operates with the transmission output pulley resulting in an accessory speed that is proportional to an engine speed at idle. At engine speeds above idle the transmission is disengaged and the output pulley to accessory pulley ratio drives the belt driven accessory at a speed less then an engine speed. An accessory can also be directly connected to the output shaft in conjunction with the output pulley. The transmission can be used with a motor generator system by providing a speed reducing unit disposed between an engine and the motor generator.
1. An accessory belt drive system comprising:
transmission means having a transmission ratio and an input means and an output means, the transmission ratio selected by braking operation of a sun gear, the output means comprising a ring gear;
the transmission means driven by a driver engaged through the input means;
the output means drivingly connected to a first accessory drive means;
the output means and the first accessory drive means having a ratio;
a second accessory coaxially connected to and driven by the output means;
the transmission ratio and the ratio combined drive the first accessory at a first speed for a first driver speed;
the transmission ratio disengagable at a second driver speed such that a final drive ratio at the second speed is less than the final drive ratio at the first speed, the second driver speed greater than the first driver speed.
2. The accessory belt drive system as in claim 1 , wherein the transmission means comprises an electromagnetic brake means for controlling the transmission ratio.
3. The system as in claim 1 , wherein the transmission means has a duty cycle in the range of approximately 5% to 25%.