2003 Fiscal Year Final Research Report Summary
Suface Failure Prevention Method at the Start-Stop of CVT
| Project/Area Number |
14550127
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
設計工学・機械要素・トライボロジー
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| Research Institution | Saga University |
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Principal Investigator |
OHNO Nobuyoshi Saga University, Faculty of Science and Engineering, Department of Mechanical Engineering, Professor, 理工学部, 教授 (00039265)
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| Project Period (FY) |
2002 – 2003
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| Keywords | Tribology / t-CVT / EHL / Traction oil / Solidification / Rheology / High pressure / Phase diagram |
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| Research Abstract |
1.High-Pressure Rheology of Eight Synthetic Lubricants Based on Phase Diagrams
The phase diagram was first plotted for oils, up to pressure L2GPa and temperature from 303K to 353K using the high pressure density experiment results and others. The high pressure viscosity experiment was done for oils. Then the relationship between pressure=temperature with density and viscosity was proposed based on free volume theory. It was found that the new equations from these relationships could predict the high pressure rheology more closely than that of Dowson and Roelands. Moreover it was shown that the Ehrenfest equation or the gradient of the phase diagram is closely related to the expansion coefficient of free volume.
2.High-Pressure Short Time Behavior of Traction Fluids
The squeeze film formation ability of traction fluids is studied under impact load by falling bearing steel ball against a flat anvil made of mild steel. The effect of the pressure-viscosity coefficient and the viscosity is inv
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estigated for plastic impact. The difference of depth of the lubricated surface dent and the dry dent increases linearly with the product αη of the pressure-viscosity coefficient a and the viscosity η The importance of lubricant parameter αη is observed under the squeeze film formation ability from contact voltage or EHL central film thickness measurement at rolling condition. The intensity of each impact collision is measured by means of an acoustic emission (AE) sensor. The high-pressure short time solidification of traction fluids were confirmed by the analysis of dent after the impact tests and AE analysis under impact loads.
3.Surface Failure Prevention Method at Halting of t-CVT
A method based on interferometry has been developed for experimentally measuring transient, changes in EHD film thickness in non-steady state conditions. At present the method obtains 125 film thickness or film profile measurements per second by using a high speed digital video camera. In EHL shut down, the entrapments of oil form upon halting. The entrapped film thickness increases linearly with the product αη a of pressure-viscosity coefficient α, the viscosity n and the deceleration a. The subsequent leakage of oil from contact is fluid specific. The periods of squeeze out of entrapped oils are conditioned by the product α p of mean Hertzian pressure p and the pressure-viscosity coefficients α of oils. Less
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