Composite Drive Member for Vehicle Differential Actuator
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Solution Overview
Problem
Conventional vehicle differential systems face challenges in maintaining optimal torque transmission when one wheel encounters a surface with a lower coefficient of friction than the others, leading to undesired vehicle performance due to differential wheel spin rates.
Innovation Solution
A drive member for a vehicle differential lock mechanism, comprising a coil and a movable drive member responsive to a magnetic field, formed from magnetically responsive and non-responsive materials, with a third body having a lower coefficient of thermal expansion, allowing for controlled engagement and disengagement of the locking mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single magnetically conductive material is used for the movable plate, then the manufacturing process is simple, but the thermal expansion mismatch causes binding or seizing under temperature variations
Solution Approach 1:
The movable plate is constructed as a composite assembly comprising a first magnetically conductive plate, a second non-magnetically conductive plate, and a third magnetically conductive plate. This composite structure allows selection of materials with matched thermal expansion coefficients, eliminating binding or seizing under temperature variations while maintaining manufacturability through modular assembly.
Solution Approach 2:
The movable plate is divided into multiple segmented components (first, second, and third plates) that can be independently selected and assembled. This segmentation enables optimization of each component's material properties, particularly thermal expansion characteristics, to match corresponding stationary components and prevent operational binding.
2Force
If the drive member is made entirely from magnetically responsive material, then the magnetic field actuation is effective, but thermal expansion mismatch with the housing causes binding under temperature variations
Solution Approach 1:
Different regions of the drive member have different material properties: the first and third plates are magnetically responsive for effective magnetic actuation, while the second plate is non-magnetic and can be selected to have thermal expansion characteristics that match the housing, preventing binding at the interface.
3Adaptability or versatility
If conventional differential systems are used, then the wheels can turn at different rates during normal operation, but torque transmission fails when one wheel encounters a surface with lower friction coefficient
Solution Approach 1:
The system dynamically transitions between open and locked states based on operating conditions. The electromagnetic actuator enables the differential to switch from allowing different wheel speeds (open state) to forcing uniform wheel speeds (locked state), adapting to varying traction conditions and ensuring reliable torque transmission when needed.
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
Enables effective locking and unlocking of the differential, ensuring uniform torque distribution between wheels, improving vehicle performance by adapting to varying traction conditions.
Implementation Method 1
a coil and a drive member movable in response to a magnetic field generated by application of electricity to the coil
Data Source
Figure 1
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Figure 3~4
AI summary
A system for a vehicle differential includes a coil (49) and a drive member (54) movable between a first position and a second position. The drive member has an axis and includes a first body (74) that is magnetically responsive, a second body (76) formed at least partially from a second material that is not magnetically responsive and a third body (78) that defines a radially inner surface of the drive member. The first body, second body and third body are coupled together with the third body being formed from a material having a lower coefficient of thermal expansion than the second body. The system may also include a lock member (56) driven by the drive member to engage a gear of the differential in at least one position of the lock member.