Viscous Fluid Clutch Venting and Valve Layout for Quiet Startup
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Solution Overview
Problem
Viscous fluid clutches often experience undesired coupling when starting due to residual fluid in the work chamber, leading to noise and energy consumption, especially when the engine does not require cooling, which is undesirable.
Innovation Solution
The design incorporates a storage chamber within the clutch plate, with valves that manage the fluid distribution using centrifugal force and pressure differentials to minimize fluid migration during rest periods, ensuring that the work chamber is largely empty at startup, and progressively fills with fluid only when needed, using a hermetic enclosure with controlled supply and return connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If viscous fluid is present in the work chamber, then coupling between housing and clutch plate is achieved, but undesired coupling and noise occur at startup due to residual fluid
Solution Approach 1:
The clutch is divided into two separate chambers: a storage chamber for holding viscous fluid and a work chamber for actual coupling operation. This segmentation allows the fluid to be stored separately and only introduced into the work chamber when coupling is needed, preventing residual fluid from causing undesired startup coupling and noise.
Solution Approach 2:
The storage chamber is prepared in advance to hold the viscous fluid in a controlled state. Valves are pre-positioned to control fluid flow, and the system is designed so that fluid migration to the work chamber occurs only when coupling is required, not during rest periods when the engine is off or cooling is unnecessary.
2Reliability
If viscous fluid is retained in the work chamber during rest periods, then coupling is maintained, but energy is consumed and cooling is unwanted when not needed
Solution Approach 1:
The system dynamically controls the quantity of viscous fluid in the work chamber using valves that respond to operational conditions. During rest periods, valves close to prevent fluid migration, decoupling the housing from the clutch plate and eliminating energy consumption. During operation, valves open to allow fluid migration, enabling coupling when needed.
Solution Approach 2:
The system uses the rotation of the clutch plate itself to generate centrifugal force that drives fluid migration from the storage chamber to the work chamber when coupling is needed. The centrifugal force created by the rotating clutch plate automatically controls fluid flow without requiring external power, making the system self-regulating based on its operational state.
3Speed
If fluid migration is allowed during rest periods, then coupling is ready for immediate operation, but noise and energy loss occur during startup
Solution Approach 1:
The storage chamber is pre-filled with viscous fluid and positioned ready for rapid deployment. When coupling is needed, the valves open and fluid quickly migrates to the work chamber due to centrifugal force, providing immediate coupling capability without requiring fluid to be continuously present in the work chamber during rest periods.
Solution Approach 2:
The viscous fluid is extracted from the work chamber and stored in a separate storage chamber during rest periods. This removes the source of noise and energy consumption from the work chamber while keeping the fluid readily available for immediate coupling when operation begins, separating the fluid storage function from the coupling function.
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 effectively reduces or prevents undesired coupling at startup, minimizing noise and energy consumption while maintaining functionality, ensuring that the clutch only engages when necessary, thus optimizing energy use and reducing unwanted cooling effects.
Implementation Method 1
a viscous fluid which is present in a work chamber through a shearing force transmitted by the viscous fluid
Implementation Method 2
the second valve (13) being movable to an open position by a centrifuge force generated by rotation of the drive shaft (1) exceeding a predetermined centrifuge force threshold
Data Source
Figure 1
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Figure 3
AI summary
A viscous fluid clutch comprising a clutch plate (101) driven by a drive shaft (102). A housing (103) surrounds the clutch plate and comprises a work chamber (105). A storage chamber (106) for the viscous fluid is in the clutch plate. Supply and return connections connect the storage and work chambers. A first valve (109) is located in the supply connection. A second valve (110) movable to an open position by a centrifuge force is located in the supply connection and closes the supply passage when the drive shaft is at rest. A third valve (111) is a one-way valve located in the return connection, permitting the passage of viscous fluid from the work chamber to the storage chamber. A vent (112) is provided for venting gas from the storage chamber to the work chamber. An enclosure comprising the connected storage and work chambers (105) is hermetic.