Constant-Velocity Joint Shaft Angular Play NVH Reduction
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Solution Overview
Problem
Constant velocity joint shafts in motor vehicles face new NVH (noise, vibration, harshness) problems due to lightweight engine blocks and bodies, which generate higher frequency vibrations and torques, leading to unpleasant noises, especially during load changes.
Innovation Solution
A constant velocity universal joint shaft with a sliding fit connection between the ball star and connecting shaft, and controlled angular play in the plunging joint, combined with a damping element and optimized spline connections, to reduce vibrations and noises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a press fit connection is used between the ball star and connecting shaft to minimize angular play, then NVH characteristics improve, but new NVH problems arise with lightweight engines and bodies
Solution Approach 1:
The patent changes the connection parameter from a rigid press fit to a splined connection with controlled angular play (0.3° to 1.4°). This parameter modification allows the joint to accommodate high-frequency vibrations from lightweight engines while maintaining sufficient connection stability, thereby eliminating scratching noises during load changes without sacrificing overall NVH performance.
2Manufacturing precision
If a rigid press fit connection is used to eliminate angular play, then manufacturing precision is improved, but the joint shaft becomes more sensitive to high-frequency vibrations
Solution Approach 1:
The patent transitions from a static rigid press fit to a dynamic splined connection that allows controlled movement. The splined connection with 0.3° to 1.4° angular play provides dynamic adaptability, enabling the joint to absorb and dampen high-frequency vibrations from lightweight engine blocks while maintaining precise angular positioning during normal operation.
3Stability of the object's composition
If the connection between tripod star and connecting shaft is made rigid with minimal play, then rotational stability is improved, but axial movement freedom is restricted
Solution Approach 1:
The patent segments the connection functionality by using splined connections that independently handle rotational and axial movements. The spline teeth provide rotational stability through engaged profiles, while the controlled angular play (0.3° to 1.4°) between the splined connection and tulip allows necessary axial movement freedom, accommodating both requirements simultaneously.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly reduces NVH issues by altering the frequency spectrum of the joint shaft, minimizing vibrations and noises inside the passenger compartment, even under unfavorable conditions, with improved manufacturing advantages and safety features.
Implementation Method 1
the non-rotatable connection between the ball star and the connecting shaft forms a sliding fit in the axial direction
Implementation Method 2
combined with a damping element and optimized spline connections, to reduce vibrations and noises
Data Source
Figure 1
AI summary
The present invention relates to a constant-velocity joint shaft (1) for a motor vehicle, which constant-velocity joint shaft (1) comprises a constant-velocity joint (10) with an outer ball shell (12) and an inner ball star (14). Furthermore, said constant-velocity joint shaft (1) comprises a slip joint (20) with a tulip (22) which forms a plurality of raceways which are elongate in the longitudinal direction and which are distributed uniformly along the inner periphery, and having a tripod star (26) which forms a plurality of pins, wherein each raceway of the tulip is assigned a pin of the tripod star. Finally, a connecting shaft (40) is provided which is rotationally fixedly connected to the ball star of the constant-velocity joint and to the tripod star of the slip joint, wherein the rotationally fixed connection between the ball star and the connecting shaft forms a sliding fit in the axial direction, and the angular play between the connecting shaft and the tulip of the slip joint is between 0.3° and 1.4°. The present invention also relates to a method for producing a constant-velocity joint shaft with improved NVH properties.