Differential Gear Thrust Force Generation via Spline Segmentation
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Solution Overview
Problem
Conventional differential gear mechanisms face limitations in increasing differential limiting force due to the difficulty in enhancing helical angles of gears, which restricts the generation of thrust force and subsequently the frictional resistance, hindering improved vehicle traveling ability.
Innovation Solution
The differential gear mechanism incorporates a thrust force generating mechanism between separate portions of the sun gears, ensuring thrust forces act parallel to the rotational axis, enhancing friction resistance and differential limiting force by utilizing helical teeth in spline bores and spline portions to transmit torque while preventing relative rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the helical angle of the external gear portion and planetary gear is increased to increase thrust force, then the differential limiting force increases, but the gear strength is compromised and manufacturing becomes difficult
Solution Approach 1:
The sun gear is divided into two separate portions: a first portion with the external gear portion and a second portion without external gear teeth. These portions are connected via a thrust force generating mechanism (spline connection), allowing the thrust force to be generated and transmitted without requiring a single monolithic gear structure with excessively large helical angles.
Solution Approach 2:
A thrust force generating mechanism comprising spline bores in the first portion and spline portions in the second portion acts as an intermediary to transmit the thrust force. The helical teeth in the spline connection generate thrust force that is transmitted to press the axial end surface against the housing, thereby increasing differential limiting force without compromising gear strength.
2Force
If the helical angle of the external gear portion and planetary gear is increased to increase thrust force, then the differential limiting force increases, but the manufacturing precision and assembly become difficult
Solution Approach 1:
Dividing the sun gear into separate portions with spline connections allows each component to be manufactured with standard helical angles, avoiding the need for precision manufacturing of single high-helical-angle gears. The spline portions and bores can be manufactured with conventional precision standards.
3Force
If the thrust force is increased to increase differential limiting force, then the friction resistance increases, but the gear structure becomes more complex
Solution Approach 1:
The thrust force generating mechanism is integrated into the existing sun gear structure by adding spline bores and spline portions to the respective portions. This merging approach generates additional thrust force without requiring completely separate mechanisms, thereby increasing differential limiting force while minimizing structural complexity.
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 design increases the differential limiting force, thereby enhancing the vehicle's traveling ability by generating additional friction resistance during sun gear rotation, improving torque transmission and wheel rotation.
Implementation Method 1
The external gear portions of the sun gears and the planetary gears include helical teeth, respectively. Thus, a thrust force is generated at an engagement portion between each of the external gear portions of the sun gears and each of the planetary gears.
Implementation Method 2
An axial end surface of each of the sun gears is pressed against each contact surface provided inside of the housing. Accordingly, at the time of differential rotation of the sun gears, a frictional resistance is generated between the end surface of each of the sun gears and the contact surface of the housing for restricting the rotation of the sun gears.
Data Source
AI summary
A differential gear mechanism includes a housing, first and second sun gears each including an external gear portion, and first and second planetary gears. The first and second sun gears include axial end surfaces pressed against contact surfaces provided at the housing by the first and second sun gears by means of thrust forces generated at engagement surfaces between the external gear portions and the planetary gears. Each of the sun gears includes a first portion having the external gear portion, a second portion, and a thrust force generating mechanism for generating thrust forces at the first portion and the second portion. A direction of the thrust force generated at the first portion by the thrust force generating mechanism is specified to be equal to a direction of the thrust force generated at the first portion by means of the engagement between the external gear portion and the planetary gear.