NTN Develops Compact "EPTJ" Constant Velocity Joint
No. 1 Worldwide for Low Vibration!
NTN Corporation has successfully developed a new, high Efficiency Pillow Journal Tripod Joint (EPTJ). This joint type drastically reduces vibration in plunging constant velocity joints (CVJs) (Note 1), thus improving NVH (Noise, Vibration, Harshness) in vehicles. The high efficiency E-series PTJ is also lighter and more compact than conventional joints. The EPTJ maintains the good vibration characteristics of the ultra-low vibration plunging joint that NTN brought to the market in 2002, yet it is smaller (4% reduction in outer diameter of outer race) and lighter (weight reduced by 8%) than the standard PTJ.
Both the shudder that can occur when a car is accelerating from a stop and the idle vibration that results with an automatic transmission are greatly affected by the induced cyclic axial load (Note 2) and plunging resistance (Note 3) of CVJs.
To eliminate these phenomena, NTN developed the innovative, ultra-low vibration PTJ. This reduced vibration by more than 50 percent compared to conventional joints and since going on the market in 2002 has rapidly grown in production volume.
In the PTJ, internal roller cassettes glide smoothly in grooves in the outer race, even when an external force acts on the joint. This means vibration is maintained at low, stable levels and plunging resistance is reduced regardless of joint angle. The PTJ therefore cuts by approximately 50 percent the induced cyclic axial load compared to conventional CVJs; and the shudder is vastly improved as well. The PTJ also drastically reduces plunging resistance and greatly improves the idling vibration in automatic transmission vehicles.
The EPTJ mechanism was designed using finite element analysis (FEA) and advanced dynamic analysis method software (ADAMS), as was NTN's original PTJ. Optimizing the component clearances and heat treatment make the EPTJ lighter and more compact while maintaining the same vibration characteristics, durability, and strength as the original PTJ.
FEATURES
Small and light-weight
- EPTJ outer race outer diameter is reduced about 4% compared to the original PTJ
- EPTJ weight is about 8% less than the PTJ
Low vibration
- Low vibration rivaling that of the PTJ
Maximum operating angle
- Same 26° maximum operating angle as the PTJ
| Note 2: | Induced cyclic axial load: Axial force due to internal frictional forces in the CVJ during rotation while the outer race and shaft are at relative angles. |
| Note 3: | Plunging resistance: Force interfering with the plunge function (smooth axial linear movement) that absorbs engine vibrations. |
Note: E-series Constant Velocity Joints
E-series constant velocity joints are a new type of CVJ from NTN Corporation, offering special features such as lighter weight, compact package size, and high efficiency. The E-series CVJ has received wide acclaim from automotive manufacturers as a product contributing to improved fuel efficiency and a better environment. Commercialization of this new EPTJ will help NTN offer an even more complete product lineup of E-series CVJs.
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EPTJ: compact - low vibration constant velocity joint |
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