Bi-directional Overrunning Clutched Differential Unit Design
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Solution Overview
Problem
Conventional bi-directional overrunning clutched differential units face issues with durability due to decentering and torsion of the clutch housing and output shafts, leading to insufficient lubrication and wear at spline meshing portions.
Innovation Solution
A bi-directional overrunning clutched differential unit design featuring a cylindrical clutch housing and output shafts with coaxial hubs and bearings, ensuring stable journaling without decentering or torsion, and a friction mechanism with a rotary and fixture friction member to prevent expansion and ensure lubrication, enhancing durability and assembly efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single bush is used to journal the clutch housing at an axial intermediate portion, then the device complexity is reduced, but the clutch housing deviates during rotation leading to insufficient lubrication and wear
Solution Approach 1:
The single bush journaling component is segmented into multiple bearing components: a first ball bearing at one axial end, a second ball bearing at the other axial end, and a third ball bearing at the axial intermediate portion. This segmentation provides multiple support points that prevent clutch housing deviation while ensuring sufficient lubrication and reducing wear at spline meshing portions.
2Ease of manufacture
If the output shafts are independently separated in the cage, then the ease of manufacture is improved, but the decentering and torsion force are insufficiently eliminated leading to reduced durability
Solution Approach 1:
The right and left output shafts are merged through a common support structure where the third ball bearing journals both output shafts at their axially proximal end portions. This merging eliminates decentering and torsion forces between the output shafts while maintaining ease of manufacture through standardized bearing components.
3Device complexity
If the axially proximal end portions of the output shafts are adjacent to each other, then the device complexity is reduced, but the lubrication is insufficient causing wear and rust at meshing portions
Solution Approach 1:
The third ball bearing acts as an intermediary component between the axially proximal end portions of the right and left output shafts. It provides a journaling surface that separates the output shafts by a sufficient distance to allow lubricant oil to reach the spline meshing portions, preventing wear and rust while maintaining structural simplicity.
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 design stabilizes the clutch housing and output shafts, preventing decentering and torsion, ensuring sufficient lubrication and improving durability by maintaining the integrity of spline meshing portions, thus enhancing the overall performance and longevity of the differential unit.
Implementation Method 1
a friction mechanism for applying a frictional rotation resistance onto the cage. As a result of the frictional rotation resistance, the rotation of the cage is delayed relative to the rotation of the clutch housing so that the rollers contact the respective cams.
Implementation Method 2
when the rotation speed of the output shafts becomes less than the rotation speed of the clutch housing and ring gear, the rollers are wedged up between the respective cams and the hubs or output shafts, thereby engaging the overrunning clutch of the differential unit so as to transmit the input rotary force of the ring gear to the output shafts.
Data Source
AI summary
In a bi-directional overrunning clutched differential unit, a pair of coaxial hubs are relatively unrotatably fitted on respective coaxial output shafts, and are relatively rotatably inserted into a cage holding rollers. A pair of second bearings journal a clutch housing disposed around the cage is diametrically larger than a pair of first bearings journaling the respective hubs, and are disposed between the first bearings in the axial direction of the output shafts. An axial end portion of the cage and the second bearing on the same axial side are distant from the first bearing on the same axial side so as to have a space where a friction mechanism for applying a frictional rotation resistance onto the cage is disposed.