Frequency-Sensitive Piston Valve Assembly for Variable Shock Damping
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Solution Overview
Problem
Conventional shock absorbers in vehicles have constant damping force characteristics across high, medium, and low speeds, making it difficult to simultaneously achieve ride quality and stability adjustments, as the damping force changes with piston speed rather than frequency or stroke, leading to inadequate performance in various road conditions.
Innovation Solution
A frequency-sensitive piston valve assembly that varies damping force based on frequency and speed by using a piston valve main body, piston main retainer, piston main valve, piston pilot housing, and pilot valve, with a piston inlet disk to control the flow rate of working fluid between compression and rebound chambers, allowing the damping force to adjust according to the frequency during extension and compression processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a single flow path is used to maintain constant damping characteristics at high, medium, and low speeds, then the damping force remains stable across speeds, but the ride quality deteriorates because the damping force cannot be lowered at low speeds to improve comfort
Solution Approach 1:
The single flow path is divided into multiple flow paths: a first flow path for low-speed operation and a second flow path for high-speed operation. This segmentation allows the shock absorber to provide different damping characteristics at different speeds, maintaining stability at high speeds while reducing damping force at low speeds to improve ride quality.
Solution Approach 2:
The valve assembly dynamically switches between different flow paths based on operating conditions. A valve body with movable components adjusts the flow resistance dynamically, allowing the system to adapt damping force to speed variations, thereby improving ride quality without sacrificing high-speed stability.
2Device complexity
If the damping force changes only in response to piston speed changes, then the shock absorber operates simply, but the ride quality deteriorates because it cannot satisfy both ride quality and stability adjustments simultaneously
Solution Approach 1:
Different sections of the valve assembly have different functions: the first valve controls low-speed damping characteristics while the second valve controls high-speed characteristics. This local differentiation allows the system to be adaptive to various road conditions while maintaining reasonable structural simplicity.
Solution Approach 2:
The system changes flow resistance parameters based on operating conditions by using adjustable valve openings and flow path configurations. This allows the damping force to adapt to different road conditions through parameter variation rather than complete structural redesign.
3Ease of manufacture
If a single flow path with constant damping characteristics is used, then the manufacturing is simple, but the performance deteriorates because the damping force cannot vary with frequency to optimize ride quality
Solution Approach 1:
The valve assembly is segmented into multiple independent valve components and flow paths, each responsible for specific frequency ranges. This modular segmentation maintains manufacturing simplicity while enabling frequency-sensitive performance through the combination of multiple standardized components.
Solution Approach 2:
The valve assembly components are designed to serve multiple functions: the same valve structure handles both low-speed and high-speed flow control, and the flow paths can operate in different configurations depending on operating conditions, reducing the need for specialized components for each 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
The solution effectively generates a damping force that varies with frequency and speed, improving ride quality and stability by maintaining high damping at low frequencies and reducing it at high frequencies, thus optimizing vehicle performance across different speed and road conditions.
Implementation Method 1
a piston inlet disk interposed between the piston pilot housing and the pilot valve. Further, the piston pilot chamber is configured to communicate with the piston inlet flow path via the piston inlet disk so that an inflow flow rate of working fluid introduced into the piston pilot chamber during the extension process is relatively limited compared to an inflow flow rate of working fluid introduced into the piston main chamber, selectively depending on the frequency.
Implementation Method 2
a pilot valve coupled to the piston rod to cover the piston pilot chamber and configured to press the piston main valve to close the piston main chamber when pressure in the piston pilot chamber increases above a predetermined pressure.
Implementation Method 3
The shock absorber is also called a damper and is operated by the vibration of the vehicle in response to road conditions. In this case, a damping force generated by the shock absorber varies depending on an operating speed of the shock absorber, i.e., fast or slow operation.
Data Source
AI summary
A piston valve assembly of a frequency sensitive shock absorber includes a piston valve main body mounted on the piston rod and having a piston inlet flow path formed therein in communication with a rebound chamber, a piston main retainer having a piston main chamber formed therein in communication with the piston inlet flow path, a piston main valve configured to open and close the piston main chamber, a piston pilot housing coupled to the piston rod between the piston main valve and the piston valve main body and having a piston pilot chamber formed therein in communication with the piston inlet flow path, and a pilot valve configured to cover the piston pilot chamber and press the piston main valve to close the piston main chamber when pressure in the piston pilot chamber increases above a predetermined pressure.