Fixed CV Joint Torque Loss Reduction via Cage Gap and Grease

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Solution Overview

Problem

Existing fixed type constant velocity universal joints face challenges in reducing transmission torque loss and improving durability for drive shafts with small normal operating angles without compromising strength, load capacity, and compactness, especially in sedan vehicles where NVH properties are critical.

Innovation Solution

The solution involves optimizing the design by creating a positive gap between the cage and the ball, using grease with initial consistency equivalent to consistency number 1 or 2 and mixture stability from 390 to 440, and incorporating a paraffin-based mineral oil with a urea compound thickener to reduce friction and enhance flowability, thereby minimizing torque loss and improving durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the basic shape configuration of an eight-ball fixed type constant velocity universal joint is used to secure strength, load capacity, and durability, then transmission torque loss increases and durability decreases for drive shafts with small normal operating angles

Engineering Contradiction:

Improvetransmission torque lossVSAvoiddurability

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The invention changes the geometric parameters of the joint by introducing a positive gap between the cage and balls, and by optimizing the curvature radius ratio (R1/R2) between track grooves. These parameter changes reduce friction and torque loss while maintaining durability through proper dimensional relationships.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention applies different local characteristics to different parts of the joint. Specifically, a positive gap is introduced only in the cage-ball interface region, while the track groove curvature and other components maintain their traditional design. This localized modification reduces torque loss without compromising overall structural integrity.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If the basic shape configuration of an eight-ball fixed type constant velocity universal joint is used, then strength, load capacity, and durability are secured, but the joint is not optimized for drive shafts with small normal operating angles in sedan vehicles

Engineering Contradiction:

Improveadaptability to small normal operating anglesVSAvoidtransmission torque loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The invention optimizes the joint for small operating angles by changing key parameters: introducing a positive gap between cage and balls (0.01-0.05 times ball diameter), and setting the curvature radius ratio R1/R2 between 0.95-1.05. These parameter changes adapt the joint to sedan vehicle drive shafts with small normal operating angles while reducing torque loss.

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If grease with higher flowability is used to reduce friction, then torque loss decreases, but grease leakage increases

Engineering Contradiction:

Improvetorque lossVSAvoidgrease leakage

Core Design Contradiction:

Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The invention changes the physical parameters of the grease by specifying a consistency number of 1 or 2 (corresponding to specific viscosity ranges). This parameter selection achieves optimal balance: the grease has sufficient flowability to reduce friction and torque loss, while maintaining thick enough consistency to prevent leakage from the joint.

Inventive Principle:

Principle #35Parameter changes

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

This configuration effectively reduces transmission torque loss and enhances durability of the fixed type constant velocity universal joint for drive shafts with small normal operating angles, maintaining strength, load capacity, and compactness while improving NVH properties and reducing the risk of abnormal noise and vibration.

Implementation Method 1

using grease with initial consistency equivalent to consistency number 1 or 2 and mixture stability from 390 to 440, and incorporating a paraffin-based mineral oil with a urea compound thickener to reduce friction

Methodology Applied

Scientific EffectLubrication: Lubrication

Implementation Method 2

incorporating a paraffin-based mineral oil with a urea compound thickener to reduce friction and enhance flowability

Methodology Applied

Scientific EffectRheology:

Data Source

PatentUS10309464B2Fixed constant velocity universal joint

Publication Date: 2019.06.04 NTN CORP

AI summary

A fixed type constant velocity universal joint includes an outer joint member having eight curved track grooves, an inner joint member having eight curved track grooves, eight torque transmission balls, and a cage configured to hold the torque transmission balls in pockets. A curvature center of each of the track grooves of the outer joint member and a curvature center of each of the track grooves of the inner joint member are offset from a joint center by an equal distance to opposite sides in the axial direction. The joint has grease sealed therein. Initial pocket gaps between the pockets and the balls each have a positive value. The grease has an initial consistency equivalent to consistency number 1 or 2, and a mixture stability of from 390 to 440.