Fluid Friction Clutch Scraping Element Pressure Isolation
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Solution Overview
Problem
Existing fluid friction clutches experience unstable torque transmission and rotational speed due to dynamic pressure variations caused by relative speed changes between the primary and secondary sides, leading to drift from the operating point.
Innovation Solution
A fluid friction clutch design with a scraping element positioned on the stationary clutch member, forming a radial gap and duct communicating with the reservoir chamber, which maintains dynamic pressure and pump power independently of the relative speeds, and an electromagnetic proportional valve for controlled fluid supply, creating a stable clutch engagement and meandering flow path for enhanced torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a dynamic-pressure pump with a scraping element is used to return clutch fluid from the working chamber to the reservoir chamber, then the pump system can operate with simple structure, but the dynamic pressure at the scraping element varies with relative speed between primary and secondary sides, causing instability in torque transmission and rotational speed
Solution Approach 1:
The clutch is divided into functionally independent segments: the primary side (housing with drive element) and secondary side (clutch plate with scraping element) are separated by the clutch plate itself, which acts as a physical barrier. This segmentation isolates the dynamic pressure generation at the scraping element from the fluid supply system, preventing relative speed variations from affecting pump performance and ensuring stable torque transmission
Solution Approach 2:
The clutch plate serves as an intermediary element between the primary and secondary sides. It physically separates the scraping element (which generates dynamic pressure for fluid return) from the fluid supply path, ensuring that variations in relative speed do not transmit to the pump system. This intermediary structure maintains operational stability while keeping the pump system simple
2Speed
If the relative speed between primary and secondary sides changes, then the dynamic pressure at the scraping element varies, but this causes drift from the operating point and unstable torque transmission
Solution Approach 1:
Instead of allowing the scraping element to be influenced by relative speed changes (which would cause dynamic pressure variations), the invention inverts the relationship by positioning the scraping element on the stationary clutch member. This ensures that the scraping element operates against the moving clutch plate while remaining itself stationary, thereby maintaining constant dynamic pressure and stable torque transmission regardless of speed variations
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 solution ensures a stable nominal rotational speed under all conditions by isolating dynamic pressure from relative speed changes and improving torque transmission, maintaining clutch engagement stability and quick reaction to speed variations.
Implementation Method 1
the dynamic pressure and therefore the pump power when pumping the clutch fluid back is not influenced by the relative speed of the primary and secondary sides
Implementation Method 2
the transmission of torque is dependent on the quantity of clutch fluid situated in the working chamber
Data Source
AI summary
A fluid friction clutch with improved fluid pumping system. A scraping member is provided adjacent the clutch plate and has a duct which communicates with the reservoir chamber.