Shock Absorber Free Piston Damping Segmentation
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Solution Overview
Problem
Current shock absorbers struggle to effectively suppress high-frequency chassis vibrations, which significantly impact vehicle ride quality, due to limitations in damping force adjustment and sensitivity mechanisms.
Innovation Solution
The shock absorber incorporates an expansion-side sensitive unit and a contraction-side sensitive unit, each with a free piston and spring element, allowing for adjustable damping forces by controlling the flow of hydraulic fluid through sensitive mechanisms, enabling better suppression of high-frequency vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a damping force variable valve is provided outside the cylinder, then the stroke length is not sacrificed and loadability is maintained, but the upper limit of dampable chassis vibration frequency is restricted to several hertzs due to responsiveness limitations
Solution Approach 1:
The damping system is segmented into two independent paths: a low-frequency damping path through the damping force variable valve controlled by ECU, and a high-frequency damping path through the sensitive units with free pistons that respond mechanically to pressure changes. This segmentation allows each path to optimize for its frequency range without compromising the other.
Solution Approach 2:
The free piston acts as an intermediary element that translates high-frequency pressure fluctuations from the hydraulic fluid into mechanical motion, which then engages the damping mechanism. This intermediary allows the system to respond to high-frequency vibrations that would otherwise be too fast for electronic control.
2Device complexity
If the damping force variable valve responds slowly, then the valve structure can be simpler, but high-frequency vibrations cannot be suppressed
Solution Approach 1:
The sensitive units with free pistons provide self-service high-frequency damping by automatically responding to pressure changes through purely mechanical means. The free piston moves in response to pressure differential, engaging the damping valve without requiring external sensing or electronic actuation, thus achieving fast response with simple structure.
3Device complexity
If only electronic control is used for damping force adjustment, then the control system is simpler, but vibrations above several hertzs cannot be suppressed
Solution Approach 1:
The control system is segmented into electronic control for low-frequency damping and mechanical control for high-frequency damping. The sensitive units with free pistons provide automatic mechanical response to high-frequency vibrations, expanding the frequency range without complicating the electronic control system.
Solution Approach 2:
For high-frequency damping, the patent replaces electronic sensing and actuation with a purely mechanical system using free pistons that automatically respond to pressure changes. This mechanical substitution enables high-frequency response without requiring complex electronic control.
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 design enhances vehicle ride quality by providing optimized damping forces across a wider frequency range, effectively reducing high-frequency vibrations and maintaining strong damping forces at low frequencies, thus improving the overall ride comfort and stability.
Implementation Method 1
an expansion-side spring element configured to bias the expansion-side free piston to compress the first expansion-side pressure chamber
Implementation Method 2
a contraction-side spring element configured to bias the contraction-side free piston to compress the first contraction-side pressure chamber
Implementation Method 3
a charge passage configured to allow only a flow of hydraulic fluid directed from the reservoir to the contraction-side chamber
Implementation Method 4
a rectification passage configured to allow only a flow of hydraulic fluid directed from the contraction-side chamber to the expansion-side chamber
Data Source
Figure 1
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AI summary
A shock absorber includes at least one of an expansion-side sensitive unit and a contraction-side sensitive unit. The expansion-side sensitive unit has an expansion-side actuating chamber (E) that communicates with an expansion-side chamber and a contraction-side chamber, an expansion-side free piston (15) that partitions the expansion-side actuating chamber into a first expansion-side pressure chamber (E1) and a second expansion-side pressure chamber (E2), and an expansion-side spring element (16) configured to bias the expansion-side free piston to compress the first expansion-side pressure chamber. The contraction-side sensitive unit has a contraction-side actuating chamber that communicates with a contraction-side chamber and a reservoir (R), a contraction-side free piston (24) that partitions the contraction-side actuating chamber into a first contraction-side pressure chamber and a second contraction-side pressure chamber, and a contraction-side spring element (25) configured to bias the contraction-side free piston to compress the first contraction-side pressure chamber.