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TNT improved hollow ball screw


NTN Corporation  has developed a thin, lightweight hollow ball screw designed for actuators of various vehicle electrification.
After the variable transmission (CVT, × 1) has been increasingly used as a vehicle gearbox in recent years, and the characteristics of the oil of the hydraulic pump drive mechanism to adjust the width of the pulley. Hydraulic CVT, however, suffer from the main energy loss during the operation, and suffer from the problems when trying to use a more compact design. Electrically controlled continuously variable transmission to provide more precise control of the gear drive mechanism than the oil hydraulic continuously variable transmission and use a sliding screw, but these sliding screw power consumption due to its low efficiency of thrust conversion large.
The hollow ball screw unit developed "NTN ball screw and low rolling resistance dual-thrust conversion efficiency, and hollow screw shaft means that they can be located along the same axis as the CVT pulley mechanism. A hollow screw shaft of the spiral groove and the ball circulation groove is cut out at the same time, eliminating the need for a separate "dialing" of the material, including the S-shaped mounted in the side surface of the nut, the ball circulation groove. Nut can design thinner, lighter "dial".
Because of these improvements, the use of a transmission mechanism of the electrically controlled continuously variable transmission of the "hollow ball screw, and helps to reduce the energy and operation because the pulley electron loss and allows the CVT to use is arranged on the same axis to become more compact. It also contributes to a lighter weight and vehicle fuel efficient operation.
The NTN will actively put forward hollow ball screw and actuator unit, hollow ball screw installed in the car and motorcycle CVT and the electrification of the various implementing agencies are expected to increase in the future.
 "CVT": Abbreviation of the CVT. Clutch pulley width is used to help improve the fuel efficiency of the best gear ratio adjustment of the pulley drive mechanism.
(1) 70% or more of the conversion efficiency of the rotational force (i.e., sliding screw double)
(2) thin, light weight: thin design compared to the loop slot with the screw axis integration (20% Qingbo cycle method)
Electronically controlled CVT belt drive wheel drive electric actuator
Ball screw drive vehicles and motorcycles