Viscous Clutch Eddy Current Reduction and Response Time
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Solution Overview
Problem
Existing viscous clutches face challenges in maintaining rotational capabilities while efficiently controlling fluid flow, particularly due to difficulties in designing a suitable valve assembly that can rotate with the rotor and be effectively controlled by an electromagnetic coil, which often results in large, heavy, and costly coil configurations that exceed engine parameters.
Innovation Solution
An electromagnetically actuated viscous clutch assembly with a rotor, housing, and valve assembly that allows for selective fluid flow control, featuring a rotating fluid reservoir, a channel in the rotor for simultaneous fluid delivery to both sides, and a flux path with a magnetic insert and conductive housing insert to reduce eddy currents, enabling efficient magnetic flux transmission and minimizing air gaps for improved response time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the reservoir is attached to the rotor to improve fluid delivery speed, then the response time is improved, but it becomes difficult to provide a suitable valve assembly that can rotate with the rotor and be effectively controlled by the coil
Solution Approach 1:
The valve assembly is segmented into a stationary coil assembly and a rotating valve body. The coil assembly remains stationary while the valve body rotates with the rotor, allowing independent optimization of each component's function and simplifying the overall design.
Solution Approach 2:
A magnetic coupling mechanism serves as an intermediary between the stationary coil and the rotating valve body, transmitting magnetic force across the air gap to actuate the valve without requiring direct mechanical connection or complex rotating electrical contacts.
2Reliability
If large coils are used to generate sufficient magnetic flux for valve control, then the valve control effectiveness is improved, but the weight, cost, and power requirements increase beyond allowable engine parameters
Solution Approach 1:
The magnetic circuit parameters are optimized by using high-permeability magnetic materials and designing efficient flux paths with minimized air gaps. This increases the magnetic flux density for a given coil current, allowing smaller, lighter coils to achieve the required valve actuation force.
Solution Approach 2:
The magnetic circuit employs composite construction with different magnetic materials strategically placed to guide and concentrate flux where needed. This enhances the overall magnetic circuit efficiency and reduces the coil size required to generate sufficient flux.
3Stability of the object's composition
If the housing, reservoir, and fan blades are kept stationary or rotating slowly in disengaged condition, then the structural stability is improved, but the kinetic energy imparted to shear fluid is reduced, slowing response time
Solution Approach 1:
The system transitions from a static/discrete control mode to a dynamic continuous control mode. The viscous clutch allows the housing to rotate at variable speeds continuously between 0 and the rotor speed, enabling smooth transitions and faster response while maintaining stability through controlled viscous coupling rather than mechanical engagement.
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 design enhances clutch response time by delivering shear fluid to the working chamber simultaneously from both sides of the rotor, reduces eddy current effects, and maintains efficient magnetic flux transmission, facilitating dynamic control and reducing the size and weight of the electromagnetic coil, thus addressing the limitations of existing clutches.
Implementation Method 1
an electromagnetic coil for generating magnetic flux
Implementation Method 2
an insert extending through the housing and configured to conduct magnetic flux from the electromagnetic coil along a flux path
Implementation Method 3
a plurality of recesses defined in a portion of the housing located at an interior of the flux path to reduce eddy currents
Implementation Method 4
introducing a shear fluid to a working chamber to frictionally engage two components, such as a rotor connected to a drive input and a housing connected to a fan, by transmitting rotational energy via the shear fluid
Data Source
AI summary
An electromagnetically actuated viscous clutch assembly includes a rotor arranged relative to an axis of rotation, an electromagnetic coil for generating magnetic flux, a housing positioned adjacent to the rotor to create a fluid working chamber therebetween with the housing and the rotor being selectively rotatable relative to one another, an insert extending through the housing and configured to conduct magnetic flux from the electromagnetic coil along a flux path, a valve assembly electromagnetically linked to the insert along the flux path for selectively controlling fluid flow into the working chamber to selectively engage the rotor and the housing, and a plurality of recesses defined in a portion of the housing located at an interior of the flux path to reduce eddy currents.