Spherical Differential Gear Support for Limited Slip Torque Bias
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Solution Overview
Problem
Conventional differential apparatuses without differential action limiting functions face challenges in transmitting driving force evenly between wheels with different frictional resistances, and existing solutions with such functions require complex machining and increased size or parts, leading to high costs and durability issues.
Innovation Solution
A differential apparatus with a simple construction and low cost, featuring spherically depressed pinion and side gear supporting surface portions on the case, allowing for a larger effective friction radius and effective differential action limiting function, achieved through concentric spherical surfaces and sliding frictional support, eliminating the need for tapered surfaces and additional parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tapered surfaces are formed on the case and side gears to provide differential action limiting function, then the differential apparatus achieves limited slip differential action, but the machining accuracy requirement increases and manufacturing complexity increases
Solution Approach 1:
The patent replaces tapered surfaces with spherically depressed supporting surface portions formed on the inner surface of the case. These spherical surfaces engage with spherically projecting portions on the side gears through sliding contact, providing differential action limiting function without requiring high-precision taper machining. The spherical geometry simplifies manufacturing while maintaining the desired mechanical function.
2Reliability
If tapered surfaces are formed on the external side of side gears to provide differential action limiting function, then the differential apparatus achieves limited slip differential action, but the radial and axial dimensions increase
Solution Approach 1:
The patent embeds the differential action limiting mechanism within the existing structure of the case and side gears. The spherically depressed supporting surface portions are formed on the inner surface of the case, and the spherically projecting portions are integrated into the side gears themselves. This nested arrangement eliminates the need for external tapered surfaces, maintaining compact radial and axial dimensions while providing the required limited slip differential action.
3Reliability
If multi-plate clutch is used as differential action limiting function device, then the differential apparatus achieves limited slip differential action, but the number of parts increases and device complexity increases
Solution Approach 1:
The patent merges the differential action limiting function with the existing gear support structure. The spherically depressed supporting surface portions on the case and the spherically projecting portions on the side gears are integrated into the basic differential mechanism, eliminating the need for separate multi-plate clutch assemblies. This consolidation reduces the number of parts and simplifies the overall device structure while maintaining the limited slip differential action.
4Ease of manufacture
If conventional differential apparatus without differential action limiting function is used, then the construction is simple and cost is low, but the driving force transmission is insufficient when wheel frictional resistances differ
Solution Approach 1:
The patent modifies the support surface geometry from conventional flat or tapered surfaces to spherically depressed surfaces. This parameter change in the supporting surface shape enables the side gears to slide on the spherical surfaces, generating friction-based differential action limiting effect. The modification maintains construction simplicity and manufacturing ease while significantly improving driving force transmission capability under varying wheel friction conditions.
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 good-response limited slip differential action linked with the drive system, enhancing starting and hill-climbing properties while maintaining durability and reducing costs, with a torque bias ratio of 1.4 to 1.8 and stable frictional properties, similar to or better than conventional differentials.
Implementation Method 1
a spherically depressed pinion gear supporting surface portion (9, 11) which is formed on an inner surface of the case (3) and adapted to support a spherically projecting back side portion (17a) of the pinion gear (17) so that the pinion gear (17) is slidingly rotatable about its own axis
Implementation Method 2
spherically depressed side gear supporting surface portions (13, 15) which are formed on the inner surface of the case (3) and adapted to respectively support spherically projecting back side portions (23a, 25a) of the side gears (23a, 25a) so that the side gears (23a, 25a) are slidingly rotatable about their own axes
Data Source
AI summary
A differential apparatus is provided with a case; a pinion gear; a pair of side gears meshing with the pinion gear; a spherically depressed pinion gear supporting surface portion formed on an inner surface of the case to support a spherically projecting back side portion of the pinion gear; and spherically depressed side gear supporting surface portions formed on the inner surface of the case to respectively support spherically projecting back side portions of the side gears. The projecting back side portions of the side gears which are slidable on the depressed side gear supporting surface portions are formed on tooth portions of the side gears.