Fluid Coupling Speed Control via Magnetic Differential Signal
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Solution Overview
Problem
Current electrically actuated viscous fan drives face durability issues due to tether limitations and resonance problems, and there is a need for improved control over fan drive speed to meet fuel economy and cooling requirements.
Innovation Solution
A speed monitoring system using a hub and ring magnet with a magnetic sensor to generate a differential speed signal, allowing for precise control of the fluid-coupling device's output speed, and an operational control system that includes a valve for fluid communication to adjust engagement based on the differential speed signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rear mount actuators are used, then tether durability is improved, but axial length increases limiting narrow package applications
Solution Approach 1:
By eliminating the tether through direct mounting of the actuator to the housing, the patent achieves the durability benefits of rear-mount designs without requiring the additional axial space that tethered rear-mount configurations demand.
2Ease of operation
If electrically actuated viscous fan drives are used, then precise speed control is achieved, but durability issues arise from tether and bearing limitations
Solution Approach 1:
The patent eliminates the tether component that causes durability issues, and relocates the actuator mounting to reduce bearing load stresses. This maintains the precise electrical speed control capability while removing the primary sources of durability failure.
Solution Approach 2:
The patent changes the mounting dimension by attaching the actuator directly to the housing structure rather than through a tether, fundamentally altering the mechanical arrangement to eliminate wear components while preserving control functionality.
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 solution enhances durability, reduces costs, and provides precise control over fan speed, improving fuel economy and emissions reduction by accurately monitoring and controlling the fluid-coupling device's output speed.
Implementation Method 1
A magnetic sensor generates a differential speed signal of the ring magnet relative to the first speed
Implementation Method 2
The present invention provides a speed sensor that measures the speed differential between the clutch output and the clutch input of a fluid-coupling device using an electromagnetic circuit
Data Source
AI summary
A speed monitoring system (6) for a fluid-coupling device (10) includes a hub (44) and a ring magnet (220). The hub (44) rotates at a first speed that is proportional to an input clutch speed of a fluidically engageable input member. The ring magnet (220) rotates at a second speed that is proportional to an output clutch speed of a fluidically engageable output member. A magnetic sensor (232) generates a differential speed signal of the ring magnet (220) relative to the first speed. A controller (54) generates an actual speed signal indicative of the second speed in response to said differential speed signal.