Electromagnetic Differential Locking Structure for Wheel Slip Traction
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Solution Overview
Problem
Existing differentials fail to provide sufficient traction when one wheel slips on uneven or muddy roads due to equal torque distribution, leading to vehicles getting stuck.
Innovation Solution
A locking structure for differentials using a bi-stable electromagnetic clutch with a movable and fixed locking disc, enabling the output axle shafts to have the same rotational speed and torque by engaging face teeth, and incorporating a position sensor for state monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional differential is used to enable different wheel speeds, then the differential can accommodate turning and uneven road conditions, but insufficient traction occurs when one wheel slips on muddy roads
Solution Approach 1:
The patent implements a bi-stable electromagnetic clutch that can dynamically switch between two states: engaged (locked) and disengaged (unlocked). This dynamic capability allows the differential to adapt between locked differential mode for traction and unlocked mode for normal operation, resolving the contradiction between adaptability and reliability
Solution Approach 2:
The patent changes the torque distribution parameter by using electromagnetic force to alter the mechanical connection state. When the electromagnetic clutch is energized, it creates a magnetic field that engages the locking discs, changing the torque distribution from equal (unlocked) to forced equal (locked), thereby improving traction reliability
2Reliability
If a locking mechanism is added to the differential, then traction is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical actuation mechanisms with an electromagnetic field-based clutch system. The electromagnetic clutch uses magnetic fields generated by coils to engage and disengage the locking discs, eliminating the need for complex mechanical linkages, cables, or hydraulic systems while maintaining reliable locking functionality
Solution Approach 2:
The electromagnetic clutch serves multiple functions: it acts as both a locking mechanism for traction control and a controllable coupling device. The same electromagnetic system that engages the locking discs also provides the force necessary to maintain the locked state, reducing the need for separate actuation and holding mechanisms
3Volume of moving object
If electromagnetic clutch dimensions are minimized, then space is saved, but leakage losses increase
Solution Approach 1:
The patent employs asymmetric magnetic circuit design where the magnetic flux paths are optimized to concentrate field lines within the clutch structure. The armature disc and yoke are positioned and dimensioned asymmetrically to maximize magnetic coupling efficiency, reducing leakage flux while maintaining compact dimensions
Solution Approach 2:
The patent converts potential magnetic leakage losses into beneficial effects by positioning the armature disc with magnets close to the yoke with cylindrical iron elements. The leakage flux that would normally be lost is redirected to provide additional magnetic attraction force, enhancing the holding capability while maintaining compact size
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 locking structure ensures stable and energy-efficient operation with a compact design, allowing the differential to maintain equal wheel speeds and improve traction, enhancing vehicle mobility in challenging conditions.
Implementation Method 1
the electromagnetic clutch drives the movable locking disc to move axially after being energized
Implementation Method 2
the armature disc carries with a number of magnets, the yoke carries with a number of cylindrical iron, and each of the cylindrical iron carries with a coil, consist a solenoid
Data Source
Figure 1
Figure 2
AI summary
The present disclosure discloses a locking structure of a differential. The locking structure comprises a bi-stable electromagnetic clutch sleeved on an output axle shaft (1) on one side of the differential. The bi-stable electromagnetic clutch comprises a movable locking disc and a fixed locking disc; the fixed locking disc is fixedly connected to a differential housing (4) or integrated with differential housing (4), and the movable locking disc and the fixed locking disc have face teeth that can engage with each other. The movable locking disc is sleeved on the output axle shaft (1), the bi-stable electromagnetic clutch drives the movable locking disc to move axially after being energized, the output axle shaft (1) and the differential housing (4) are locked when the movable face teeth (5) engaged with the fixed face teeth (6) so that the output axle shaft (1) on either side of the differential and the differential housing (4) have a same rotational speed and output torque. The locking structure has the advantages of bi-stable or bi-state, controllability, and a long service life.