Electric vehicles are being more used and can be seen more frequently in our daily lives. The heart of electric vehicles is the planetary geared motor. This type of motor is also included in automatic transmission vehicles as well as in other applications that require transmission of high torque to weight ratios (lifting machines, cranes, heavy machinery, etc.).
Compared to other types of motors, planetary geared motors are more complex and are composed of three main components:
- two or more planetary gears,
- a sun gear, and
- a ring gear.
They are basically conventional motors with shaft drives that have an externally-toothed pinion. The toothing meshes of planetary geared motor uses an externally-toothed gear wheel that features a running gear. A conventional electric vehicle uses an electric motor and a battery. The motor is able to change the electric power that is stored in the battery into a rotational output and rotate the driving wheels.
To reduce the extremely high motor speed, the vehicles use a differential gear unit, located between the driving wheels and the electric motor. The unit also controls the traveling speed of the electric vehicles. Other types of electrical vehicles use parallel shift geared motors, which use a planetary geared motor as a deceleration means. These units are able to efficiently take advantage of the inside space of the driving wheel. One common type of planetary geared motor unit used for these vehicles is oriented relative to a motor drive unit case secured to electrical vehicle’s body.
A simple planetary transmission system is consisted of transmission housing, output means, input means, parallel shaft helical gearbox/es (with each gearbox is interconnected between the output and input means) and a number of selectively operable friction drives (with at least 2 clutch means that provide drive paths from input means to planetary gear means). The friction drive establishing means is connected with planetary gear means for establishing forward drive ratios, as well as a reverse drive ratio between input and output means.
The other components of planetary geared motors are:
- a ring gear (fixed to the motor drive unit case), and
- a carrier (which has at least one pinion meshing both with the ring and sun gear and is connected to a vehicle drive wheel’s axle).
The axle for the electric vehicle’s drive wheel is supported at a rotational central portion by bearings positioned in the motor drive unit case. The motor speed is reduced by the planetary geared motor unit, so it can be transmitted to the vehicle drive wheel at the right rotary speed and move the vehicle.
