NTN Corporation (hereafter, NTN) has developed “High Speed and Low Torque Deep Groove Ball Bearing” for EV/HEV that can be used at greater rotational speeds and efficiency for use in motors and reducers mounted in electric vehicles (EV) and hybrid vehicles (HEV).
There is an increasing need for higher speed and lower torque in deep groove ball bearings that are currently used in EV/HEV motors and reducers. The reason for this is that power output of these motors has being designed by increasing their rotational speed to counter the drop in power output as more compact EV/HEV motors are used. In order to decrease the power consumption of motors, a lower torque is required of bearings. Conventional deep groove ball bearings suffer from issues related to damage to the bearing itself, including distortion to the cage due to centrifugal forces when operating at high rotational speeds, and significant increases in temperature due to stirring resistance of the grease flowing into the bearing.
The newly developed “High Speed and Low Torque Deep Groove Ball Bearing” for EV/HEV uses a “Low Torque Plastic Retainers Capable of High Speeds” to maintain reliable, low torque operation at high speeds under oil lubrication. This new type of retainer consists of two retainers of the same shape in a layout that helps limit distortion in the other retainer due to centrifugal forces, allowing high speed operation up to 1.2 million DN. The use of a shield shape on the side of the retainer limits the quantity of grease flowing into the bearing to drastically reduce stirring resistance. The internal design of the bearing has also been optimized to reduce rolling viscosity resistance, which helps to reduce torque by 50% or more compared to conventional deep groove ball bearings.
NTN will be exhibiting the newly developed product at the “Automotive Engineering Exposition 2012” to be held at Pacifico Yokohama between May 23 and 25, and plans to market the product globally as a product that contributes to lower power consumption, higher efficiency and more compact size in EV/HEV applications.
*: DN = d (bearing internal diameter, mm) × n (rotational speed, min-1)
|(1)||High speed rotation||:||1.2 million DN
Rotational speed of 30,000 min-1 with a bearing internal diameter of 40 mm
|(2)||Rotational torque||:||50% or more reduction compared to NTN's standard deep groove ball bearing with oil lubrication|