Improved version of the compact, lightweight and highly responsive mobile-side equal velocity joint [EDJ].
A high-performance product for EVs that further enhances quietness and efficiency through the use of newly developed grease.

NTN Corporation (hereinafter referred to as ‘NTN’) has developed a high-performance product for electric vehicles (EVs) by improving the EDJ*1, a spherical sliding constant velocity joint that combines compactness (compactness and lightness) with excellent responsiveness, and further enhancing both quiet performance and efficiency.

By applying the newly developed grease, the product has achieved a breakthrough in meeting the quietness and efficiency requirements unique to electric vehicles, while maintaining the existing advantages of compactness and responsiveness. This product has been added to the lineup of drive shafts for electric vehicles, and NTN will continue to promote this innovative solution that meets the specific needs of EVs in the global market.

(*1): EDJ stands for E series Double offset Joint, and is part of the E series product line of NTN's constant velocity joints, which are compact and lightweight.

Spherical Slide Type Constant Velocity Joint ‘EDJ

 

 

01Background of Development

The drive shaft of EV trams is required to transmit motor power (torque) efficiently while minimising torque loss, as EV trams promote energy conservation to extend their range. At the same time, the shift of the powertrain from an engine to an electric motor has dramatically reduced the sources of noise and vibration in EV trams, placing higher demands on NVH performance. In addition, there is a growing demand for a compact design that ensures a spacious interior and luggage space, as well as for highly responsive performance that takes full advantage of the motor's response characteristics to achieve a ‘human-vehicle’ driving experience.

NTN's EDJ series of spherical sliding isokinetic universal joints have achieved industry-leading compact design and excellent response performance. In response to the special needs of EV trams, this development combined the EDJ with a newly developed special grease to create an EV-specific high-performance model with significantly improved quiet performance and transmission efficiency, while maintaining full compatibility with conventional products. (High-performance products for EV trams)

Product characteristics

1Silence and low vibration characteristics
Structural analysis reveals that the small gap difference between the steel balls and the inner and outer wheels in the contact state is the core cause of vibration in driving, and the development team has succeeded in improving driving silence and vibration suppression by balancing and unifying the contact state and applying the newly developed grease to reduce the friction resistance.

2High Performance
Reconstruction of the grease additive formulation system reduces inter-part frictional resistance by 18%. Effectively suppresses heat generation during torque transmission, reducing torque loss by 25% compared to conventional products.

3 Compactness and High Responsiveness
In addition to maintaining the high level of compactness and responsiveness of the original EDJ, the circumferential gap (backlash) of the internal components has been reduced through structural optimisation to ensure smooth torque transmission.

NTN currently offers two types of sliding type constant velocity universal joints: the ‘EDJ’ for compactness and responsiveness, and the ‘PTJ*2’ for efficiency and low vibration. By combining these two products with the CFJ*3 fixed constant velocity joint, which boasts ultra-high efficiency, NTN is proposing a drive shaft solution that is more suitable for EVs and meets the various needs of EVs.
(*2) Abbreviation for Pillow Journal Tripod Joint.
(*3) Abbreviation for Cross groove Fixed Joint.

‘EDJ structure

 

Sliding type equal velocity universal joint using steel balls to achieve movement
Smaller clearance between the steel ball and internal parts
In addition to excellent responsiveness, it enables low-vibration start-up acceleration.