Eight-Ball CV Joint Grease and Pocket Gap for Low NVH
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Solution Overview
Problem
Existing fixed type constant velocity universal joints do not adequately meet the performance requirements of electric vehicles, particularly in terms of backlash, torque loss, and NVH performance.
Innovation Solution
An eight-ball fixed type constant velocity universal joint with specific grease characteristics (consistency number 1 to 2 and mixing stability of 390 to 440) is designed, with a pocket gap range of -21 μm to -6 μm, to minimize backlash, torque loss, and rotation fluctuation, ensuring excellent NVH performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the pocket gap is set to reduce backlash and improve NVH performance, then noise and vibration are reduced, but torque loss increases due to excessive fastening allowance
Solution Approach 1:
The invention changes the parameter of pocket gap from conventional negative values (-50 to -10 μm) to a specific positive range (0 to +20 μm). This parameter change reduces the fastening allowance between the ball and pocket, thereby reducing torque loss while maintaining acceptable NVH performance through the synergistic effect of the grease formulation
Solution Approach 2:
The invention changes the physical and chemical parameters of the grease by specifying consistency number (1 to 2) and mixing stability (390 to 440). These parameter changes optimize the grease's lubrication properties, allowing it to compensate for the increased clearance and reduce torque loss without sacrificing noise and vibration control
2Loss of energy
If the pocket gap is set to reduce torque loss, then energy efficiency improves, but backlash increases and NVH performance deteriorates
Solution Approach 1:
The invention introduces grease with specific properties (consistency number 1 to 2, mixing stability 390 to 440) as an intermediary substance between the ball and pocket. This intermediary compensates for the increased pocket gap, maintaining adequate ball retention while reducing fastening allowance, thereby achieving both reduced torque loss and acceptable backlash control
Solution Approach 2:
The invention optimizes the pocket gap parameter to a positive range (0 to +20 μm) that balances torque loss reduction with acceptable backlash. The specific grease parameters (consistency number and mixing stability) are adjusted to work synergistically with this pocket gap setting, ensuring that the increased clearance does not lead to excessive backlash or NVH deterioration
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 provides a fixed type constant velocity universal joint suitable for electric vehicles with reduced torque loss, backlash, and improved NVH performance.
Implementation Method 1
grease having consistency number 1 to 2 and mixing stability of 390 to 440 is used
Data Source
AI summary
In a fixed type constant velocity universal joint 1 having eight balls rotationally driven by an electric motor, grease G having an initial consistency of consistency number 1 to 2 and mixing stability of 390 to 440 is used. An initial pocket gap δ represented by a difference (H−DBALL) between an axial width H of a pocket 5a and a diameter DBALL of a torque transmitting ball 4 is set to −21 μm or more and −6 μm or less.