Compact Differential Locking With Integrated Friction Cam Clutch
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Solution Overview
Problem
Existing differential devices for vehicles, particularly in lightweight vehicles like microcars or buggies, face challenges in size reduction and dimensional flexibility due to the volume requirements of multiplate clutches and pressure force application systems, which hinder their application in compact designs.
Innovation Solution
A differential device with a casing, differential gear set, output members featuring a friction clutch and cam mechanism, and an actuator that allows for adjustable torque transmission and differential locking, optimizing angles and structures to reduce size while maintaining functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multiplate clutch and pressure force application system are used to enable differential locking, then differential motion can be limited and locked, but the device volume increases and dimensional flexibility is reduced
Solution Approach 1:
The patent combines the friction clutch mechanism directly into the output member structure, merging functions that were previously separate. The output member includes both the friction clutch assembly and the cam mechanism in a single integrated component, eliminating the need for a separate multiplate clutch assembly and reducing overall device volume.
Solution Approach 2:
The output member serves multiple functions: it transmits torque from the side gear to the axle, provides friction clutch engagement for differential limiting, and incorporates the cam mechanism for axial movement control. This multi-functional design eliminates the need for separate dedicated components for each function.
2Reliability
If a multiplate clutch is used for differential locking, then differential motion can be controlled, but the device complexity and number of components increase
Solution Approach 1:
The friction clutch is integrated into the output member structure, combining what were previously separate components (clutch plates, clutch housing, actuation mechanism) into a single unified output member assembly. This reduces the total number of parts and simplifies the overall device architecture.
Solution Approach 2:
The patent extracts and eliminates the complex multiplate clutch assembly and its associated pressure force application system, replacing them with a simpler friction-based clutch mechanism that achieves the same differential locking function with fewer components.
3Power
If the friction face area is increased to improve torque transmission, then torque capacity increases, but the device volume and weight increase
Solution Approach 1:
The friction face is positioned locally at the interface between the output member and the casing, concentrating the torque transmission function in a specific location rather than requiring a large distributed friction surface. This localized friction engagement achieves effective torque transmission without increasing overall device volume.
Solution Approach 2:
The friction clutch mechanism utilizes axial movement of the output member relative to the casing to engage and disengage friction surfaces, transitioning from a purely radial torque transmission approach to one that incorporates axial dimension control for clutch engagement, thereby optimizing space utilization.
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 compact, flexible, and efficient torque transmission and differential motion control, ensuring traction in various conditions while minimizing the device's size, thus enhancing compatibility with lightweight vehicles.
Implementation Method 1
an oblique face forming an angle (a1) with a direction of the axis, the oblique face being in mesh with any of the side gears to constitute a cam configured to convert the torque partly into a thrust force to press the friction face onto the internal face of the casing
Implementation Method 2
a friction face pressed onto an internal face of the casing to constitute a friction clutch configured to limit the differential motion
Implementation Method 3
a differential gear set including a pinion gear and side gears in mesh with the pinion gear with a pressure angle (a4), the differential gear set being drivingly coupled with the casing to transmit the torque from the pinion gear to the side gears with allowing differential motion
Data Source
AI summary
A differential device is provided with a casing rotatable about an axis, a differential gear set coupled therewith including a pinion gear with a pressure angle (a4) and side gears in mesh therewith, output members respectively mediating torque transmission from the side gears to axles, each of which includes a friction face as a friction clutch for limiting the differential motion, dog teeth, and an oblique face forming an angle (a1) and constituting a cam for operating the friction clutch, a clutch member axially movable for functioning as a clutch to lock the differential motion and including a leg having a side face forming an angle (a2) to function as a cam and movable dog teeth each forming an angle (a3) satisfying an inequality a2≥a3; and an actuator capable of driving the clutch member toward a position where the movable dog teeth mesh with the dog teeth.