April 13, 2009
Development of ‘High efficiency and low heat generation ten ball constant velocity joint (HELJ)’ for propeller shafts,
[responding to needs for high function and low fuel consumption of FR and 4WD vehicles]
NTN Corporation (hereafter NTN) has developed a ‘High efficiency and low heat generation ten ball constant velocity joint (HELJ)’ for propeller shafts of FR and 4WD vehicles (hereafter ‘constant velocity joint’ is referred to as ‘CVJ’ )
For propeller shafts of FR and 4WD vehicles, a cross groove type CVJ (hereafter, LJ) exhibits the ability to slide axially to enhance vehicle response, with the benefit of very little backlash in the rotational direction. This type of propeller shaft joint is mainly used to enhance the propshaft and vehicle stability under high speed conditions. In recent years, a reduction in weight and an increase in efficiency have also been required for propeller shafts to improve vehicle function and fuel economy. In addition, low internal heat generation of CVJ's is required because heat dissipation performance around the propeller shaft has been reduced due to compact vehicle underbody packaging for better aerodynamics.
For this new product, the number of balls was increased from six to ten by using smaller a smaller ball size. The inclination angle of the ball rolling groove against shaft axis was decreased, compared with the conventional 6 ball HLJ (NTN's current compact cross groove LJ). By implementing these design features, reduced weight and a more compact design is achieved while maintaining strength and durability of the CVJ. Another benefit of the design is the reduction of slide resistance and torque loss during torque transmission (higher efficiency). This is accomplished by internal design optimization of the ball grooves' inclination angle relative to the sliding axis.
In response to an increasing demand of high function capability and fuel economy of vehicles, NTN will market this CVJ globally.
[ Features ]
In comparison with conventional HLJ (with a similar loading capacity)
a. High efficiency
·Torque loss reduced by 50%
b. Low heat generation
·Temperature rise reduced by 50%
c. Light weight
·Mass reduced by 5%
[ New product photo ]
[ Cross-section comparison of new product and conventional type ]
