Shock Absorber Lubricant Composition for Stability and Ride Comfort
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Solution Overview
Problem
Shock absorbers face a challenge in balancing steering stability and ride comfort, as reducing frictional force to prioritize ride comfort leads to decreased vibration damping and worsened steering stability, especially on well-maintained roads with more minute amplitude vibrations.
Innovation Solution
A lubricant composition for shock absorbers containing a base oil and pentaerythritol esters, with a specific frictional property formula (RI > 1.75×Fave - 0.05) that enhances responsiveness and average frictional force at minute amplitude, ensuring high frictional force during minute vibrations without increasing it during normal vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the frictional force of lubricant is reduced to prioritize ride comfort, then ride comfort is improved, but steering stability deteriorates
Solution Approach 1:
The lubricant composition dynamically adjusts frictional force based on vibration amplitude: at minute amplitudes (good road conditions), the pentaerythritol esters maintain higher frictional force to ensure steering stability, while at normal amplitudes, the frictional force is reduced to improve ride comfort. This dynamic behavior resolves the contradiction between steering stability and ride comfort.
Solution Approach 2:
The invention changes the frictional parameter characteristics by using pentaerythritol esters with specific molecular weight ranges (500-2000) and controlling their content (0.1-10 mass%). This parameter optimization enables the lubricant to exhibit different frictional behaviors at different vibration amplitudes, simultaneously achieving steering stability and ride comfort.
2Force
If the frictional force of lubricant is reduced to decrease vibration damping force, then vibration damping force is decreased, but steering stability deteriorates
Solution Approach 1:
The lubricant exhibits dynamic frictional characteristics that adapt to different operating conditions. At minute vibrations, the pentaerythritol esters provide sufficient frictional force to maintain steering stability, while at normal vibrations, the overall vibration damping force is reduced, achieving both goals simultaneously.
3Reliability
If frictional force is increased during minute vibrations, then steering stability is improved, but ride comfort worsens
Solution Approach 1:
The lubricant composition applies different frictional characteristics to different vibration conditions: at minute amplitudes, the pentaerythritol esters provide locally enhanced frictional force to improve steering stability, while at normal amplitudes, the frictional force is controlled to maintain ride comfort. This localized differentiation resolves the contradiction.
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 lubricant composition achieves both enhanced steering stability and improved ride comfort by maintaining high frictional force during minute vibrations while suppressing frictional force during normal vibrations, thus satisfying both requirements.
Implementation Method 1
a frictional force generated at a sliding part between a piston rod and an oil seal
Data Source
AI summary
Provided are a lubricant composition for shock absorbers, a lubricant additive, and a method of adjusting frictional property of a lubricant composition for shock absorbers, each capable of satisfying both the steering stability and ride comfort. The lubricant composition for shock absorbers contains a base oil and pentaerythritol esters and having frictional property represented by the following formula (1):RI>1.75×Fave−0.05 (1)supposing that a ratio ({Fsa−Fave}/Fave) of a difference, at the time of minute amplitude, between a peak frictional force Fsa in transition from a stationary state to a sliding state and an average frictional force Fave to the average frictional force Fave at the time of minute amplitude is responsiveness RI.