Compact Limited Slip Differential via Nested Planetary Clutch
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Solution Overview
Problem
Modern automotive vehicles require improved limited slip differentials that are complex or too large for certain applications, necessitating a more efficient power transmitting component.
Innovation Solution
A power transmitting component comprising a differential case, internal gear, sun gear, planet carrier, planet gears, output members, friction plates, and a planet pin with a lip to inhibit rotation, along with an actuator to compress friction plates for torque transmission, providing a compact and effective limited slip mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a limited slip differential is designed to be compact, then it can be suitable for certain automotive applications, but it may become too complex or insufficient in torque transmission capability
Solution Approach 1:
The patent employs a planetary gear arrangement where planet gears are nested within the differential case, and a clutch mechanism is integrated within the planetary gear structure. This nesting allows multiple functional components to occupy overlapping spatial volumes, achieving a compact overall size while maintaining the necessary complexity for limited slip functionality. The sun gear, planet gears, and clutch plates are arranged concentrically around the output axis, maximizing space utilization.
Solution Approach 2:
The differential is segmented into distinct functional modules: a planetary gear set for torque distribution, a clutch mechanism for limited slip control, and friction plates for torque modulation. This segmentation allows each module to be optimized independently for its specific function while contributing to the overall compact design. The planet carrier, sun gear, and clutch basket are separate components that can be manufactured and assembled independently.
2Volume of moving object
If a limited slip differential is designed to be compact, then it can be suitable for certain automotive applications, but it may have insufficient torque transmission capability
Solution Approach 1:
The patent utilizes a composite friction material system consisting of multiple friction plates (both stationary and rotating) made from friction-optimized materials. This composite friction interface allows for efficient torque transmission through friction engagement between the clutch plates, enabling the compact differential to transmit adequate torque despite its reduced size. The friction materials are selected to provide high coefficient of friction and thermal stability.
Solution Approach 2:
The patent replaces traditional mechanical torque transmission elements (such as large gear sets or torque arms) with a friction-based clutch mechanism. This substitution allows torque to be transmitted and modulated through friction engagement between clutch plates, which is more space-efficient than conventional mechanical elements. The clutch mechanism can transmit torque through frictional contact without requiring large mechanical leverage arms or bulky gear teeth.
3Reliability
If a limited slip differential uses a planetary gear arrangement with clutch mechanism, then it can achieve limited slip functionality, but it increases manufacturing complexity
Solution Approach 1:
The planetary gear arrangement serves multiple functions simultaneously: it provides torque distribution to the left and right outputs, enables the clutch mechanism to engage and disengage, and allows for limited slip operation. The sun gear, planet gears, and planet carrier collectively perform both differential action and clutch mounting functions. This multi-functionality reduces the need for separate components, thereby simplifying manufacturing compared to designs that require dedicated elements for each function.
Solution Approach 2:
The patent merges the clutch mechanism with the planetary gear structure by integrating the clutch basket onto the planet carrier and positioning friction plates between components of the planetary set. This merging eliminates the need for separate clutch housings and mounting structures, reducing the number of parts and assembly steps. The clutch plates are interleaved with each other and with the planetary components, creating a unified structure that combines both mechanisms.
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 enables a compact and efficient limited slip differential that effectively transmits torque while minimizing complexity, suitable for various automotive applications.
Implementation Method 1
an actuator configured to compress the first and second friction plates to transmit torque between the first and second friction plates
Data Source
AI summary
A power transmitting component can include a planetary differential including a differential case. The planet carrier can be disposed within the differential case and rotatable about the output axis relative thereto. The first output member can be coupled to the planet carrier for common rotation about the output axis. The second output member can be coupled to the sun gear for common rotation about the output axis. A clutch basket can be fixedly coupled to the planet carrier and disposed within the differential case. A set of first friction plates can be coupled to the clutch basket for common rotation about the output axis therewith and for axial translation relative to the clutch basket. A set of second friction plates can be coupled to the sun gear for common rotation about the output axis and for axial translation relative to the sun gear.