Electromagnetic Clutch Actuator Geometry for Faster, Higher Force Shift
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Solution Overview
Problem
Electromagnetic actuators in drivetrain systems face challenges in achieving rapid response times and sufficient forces without increasing component size and weight, which is undesirable for space-constrained applications like clutches and differentials.
Innovation Solution
A rotary power transmission device with a magnetically responsive plunger and a coil, where the plunger has a radially tapered nose portion and an axially inclined front face, allowing for increased magnetic force and reduced air gap as it moves, enabling efficient engagement and disengagement of the clutch ring with gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the actuator component size and weight are increased to achieve sufficient forces, then the actuation force is improved, but the space constraint is worsened
Solution Approach 1:
The plunger incorporates a nose portion with a radially tapered outer surface and an axially inclined front face, creating local geometric variations that concentrate magnetic flux and enhance actuation force at critical engagement points without increasing overall plunger size
Solution Approach 2:
The front face of the plunger is axially inclined rather than perpendicular to the axis, and the outer surface is radially tapered, introducing angular dimensions to the geometry that optimize magnetic field interaction and force generation within the constrained axial space
2Loss of time
If the actuator component size and weight are increased to achieve rapid response time, then the response time is improved, but the space constraint is worsened
Solution Approach 1:
The nose portion with its tapered outer surface and axially inclined front face creates localized geometric features that reduce the air gap and concentrate magnetic flux, enabling faster magnetic field establishment and quicker plunger response without increasing overall actuator size
Solution Approach 2:
The radially tapered nose portion geometry is designed to minimize the initial air gap between the plunger and clutch ring, preparing the magnetic circuit for rapid flux establishment and reducing the time required for actuation
3Force
If the air gap between plunger and clutch ring is reduced to increase magnetic force, then the actuation force is improved, but the manufacturing precision requirement is worsened
Solution Approach 1:
The plunger geometry features asymmetric elements including a radially tapered outer surface and an axially inclined front face, which create favorable magnetic flux distribution and reduce sensitivity to small variations in air gap dimensions
Solution Approach 2:
The nose portion geometry with its specific taper angle and axial inclination modifies the magnetic circuit parameters, optimizing flux density and reducing the criticality of precise gap control while maintaining high magnetic force
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
This design enhances the actuation force and response time of the electromagnetic actuator, allowing for effective engagement and disengagement of the clutch ring while maintaining a compact size, thus addressing the space and weight constraints in drivetrain systems.
Implementation Method 1
an actuator having a coil and a plunger driven for movement along an axis and relative to the clutch ring
Implementation Method 2
The plunger includes a first body formed at least partially from a first material that is magnetically responsive
Data Source
AI summary
A rotary power transmission device includes a device housing having an interior in which multiple gears are received for rotation, a clutch received within the device housing and having a clutch ring selectively engageable with one of the multiple gears, and an actuator having a coil and a plunger driven for movement along an axis and relative to the clutch ring. The plunger has a first position and a second position in which the clutch ring is engaged with one of the multiple gears. The plunger includes a first body formed at least partially from a magnetically responsive material, and includes a radially outer surface, a radially inner surface and a front face that is axially variable and arranged so that a radially outer portion of the front face is axially forward of a radially inner portion of the front face.