Cross Shaft Joint Lubrication Layout for Torque Durability

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Solution Overview

Problem

The durability of cross shaft joints in vehicles is compromised due to the positioning of lubrication holes, which do not account for torque direction, leading to reduced rigidity and strength under torque input.

Innovation Solution

The cross shaft joint design includes lubrication holes positioned more distant from torque input points and inclined or eccentric relative to the axes, ensuring they are away from the torque transmission paths, with communication for lubricant filling to enhance durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a lubrication hole is formed inside the cross shaft, then lubrication function is provided, but the rigidity and strength of the cross shaft are reduced

Engineering Contradiction:

Improvelubrication functionVSAvoidstrength against torque input

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The lubrication hole is positioned at a specific location (more distant from the torque input position) to provide lubrication function while minimizing impact on structural strength. This local optimization ensures that the hole is placed where it is least likely to compromise the cross shaft's ability to withstand torque, thereby resolving the contradiction between providing lubrication and maintaining strength.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The position of the lubrication hole is predetermined during design based on the expected torque input direction and magnitude. By pre-placing the lubrication hole at an optimal position that is more distant from where torque is input, the design proactively prevents strength reduction rather than addressing it after the fact.

Inventive Principle:

Principle #10Preliminary action

2Strength

If the lubrication hole is positioned away from the torque input position, then the strength of the cross shaft is increased, but the ease of lubricant delivery may be reduced

Engineering Contradiction:

Improvestrength against torque inputVSAvoidease of lubricant delivery

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The lubrication hole is positioned at a specific location that balances strength requirements with lubricant delivery effectiveness. By carefully selecting the position to be more distant from torque input while still maintaining adequate lubricant flow path, the design achieves both strength enhancement and sufficient lubrication delivery.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11255384B2Cross shaft joint of vehicle

Publication Date: 2022.02.22 TOYOTA JIDOSHA KK

AI summary

A cross shaft joint of a vehicle includes: a cross shaft provided on a power transmission path; a first yoke rotatably supporting a pair of the four shaft portions; and a second yoke rotatably supporting a pair of the four shaft portions. The cross shaft includes a lubrication hole passing through the inside of each of the four shaft portions and which is in communication with a shaft end of the each of the four shaft portions. The lubrication hole is formed at a position more distant, than a corresponding one of the two axes, from a position in a corresponding one of the four shaft portions to which a torque from the drive power source is transmitted through a corresponding one of the first and second yokes.