Bi-directional Overrunning Clutch in Front Differential
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Solution Overview
Problem
Current differential systems for four-wheel drive vehicles face challenges in transmitting higher torque in a compact package, as existing overrunning clutches become larger to handle increasing torque demands, occupying valuable space and requiring heavier components.
Innovation Solution
A front differential with a bi-directional overrunning clutch assembly that includes a pinion assembly, ring gear assembly, and an electromagnetic control system for indexing a roll cage relative to the clutch housing, allowing independent rotation of pinions and ring gears, and enabling efficient torque transmission and engine braking capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional overrunning clutches are used to transmit higher torque, then torque transmission capability is improved, but the size and weight of the clutch components increase
Solution Approach 1:
The patent places the overrunning clutch assembly inside the differential housing, nesting it within the existing differential structure. The clutch housing is positioned within the differential case, and the roll cage assembly is nested within the clutch housing. This nesting arrangement allows the clutch components to be integrated into the differential package without requiring additional external space, thereby maintaining compact dimensions while handling higher torque loads.
Solution Approach 2:
The patent combines the overrunning clutch function with the differential assembly into a single integrated unit. The clutch housing is formed as part of the differential housing structure, and the clutch mechanism shares common mounting points and support structures with the differential gears. This merging of functions eliminates the need for separate clutch housings and mounting structures, reducing overall component weight while maintaining torque capacity.
2Power
If conventional overrunning clutches are used to transmit higher torque, then torque transmission capability is improved, but the volume occupied by clutch components increases
Solution Approach 1:
The overrunning clutch assembly is nested within the differential housing, with the clutch housing positioned inside the differential case and the roll cage assembly nested within the clutch housing. This multi-level nesting arrangement allows the clutch components to occupy space that would otherwise be unused in the differential assembly, maintaining a compact overall volume while providing sufficient torque transmission capability.
Solution Approach 2:
The patent utilizes the radial and axial dimensions within the differential housing to accommodate the clutch assembly. The clutch housing is positioned radially within the differential case, and the roll cage assembly extends axially within the clutch housing. By efficiently utilizing all three spatial dimensions, the design maximizes torque capacity within the available volume without requiring additional external space.
3Power
If locking differentials are used to lock half shafts together, then torque transmission to both wheels is improved, but the ability to accommodate different wheel speeds during turning is lost
Solution Approach 1:
The patent employs a bi-directional overrunning clutch mechanism that dynamically adjusts its engagement state based on operating conditions. The clutch can lock the half shafts together when torque transmission to both wheels is required, and it can allow differential rotation when the wheels need to turn at different speeds. This dynamic adaptability is achieved through the roll cage assembly that can freely rotate in one direction to permit speed differences, while preventing reverse rotation to maintain locked state during acceleration.
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 efficient torque transmission and engine braking while maintaining a compact design, allowing for seamless switching between two-wheel and four-wheel drive modes without the need for manual hub engagement, reducing stress on axles and improving gear life.
Implementation Method 1
The system includes an electromechanical device, which in one embodiment is an electrically controlled coil adjacent to an armature plate that is engaged with the roll cage and rotates in conjunction with the roll cage. When the coil is energized, an electromagnetic field is produced which hinders the rotation of the armature plate, thus causing the roll cage to drag or advance into an appropriate position relative a clutch housing.
Data Source
AI summary
A front differential for a four wheel drive vehicle including a pinion assembly with first and second pinions that are engaged with a ring gear assembly with first and second ring gears. The first pinion and first ring gear combination are rotatable independent from the second pinion and second ring gear combination, thus permitting one to rotate relative to the other. The first pinion and first ring gear combination are adapted to rotate one driven shaft, and the second pinion and second ring gear combination are adapted to rotate the other driven shaft. A bi-directional overrunning clutch assembly is engaged with an end of the drive shaft and includes one set of rolls located adjacent to the first pinion shaft, and another set of rolls located adjacent to the second pinion shaft. The clutch assembly control torque transmission between the pinion shafts and the drive shaft.