Disk Valve Flatness Control in Hydraulic Cylinder Apparatus
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Solution Overview
Problem
Conventional hydraulic shock absorbers face issues with unstable damping force characteristics due to degradation in disk valve flatness caused by seal member contraction during manufacturing, leading to fluid leakage and difficulty in achieving low damping forces at low piston speeds.
Innovation Solution
A cylinder apparatus with a disk valve having an annular elastic seal member fixed to one side, where the seal member's extension is fixed to the other side, reducing variations in flatness and allowing for stable damping force control through a pilot-type valve mechanism with adjustable pressure settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a set load is applied to the disk valve to ensure close contact with the valve seat, then sealing performance is improved, but valve-opening pressure increases making it difficult to achieve low damping force
Solution Approach 1:
The disk valve is pre-deflected in the valve-closing direction during assembly to ensure close contact with the valve seat before operation. This preliminary action maintains sealing reliability without requiring continuous application of set load during operation, thereby reducing the valve-opening pressure compared to conventional designs that maintain constant preload.
2Ease of manufacture
If the seal member is fixed to the disk valve body by conventional methods, then the seal member may contract during manufacturing, but this causes deflection of the disk valve body degrading flatness
Solution Approach 1:
A dedicated seal member fixing portion is introduced as an intermediary structure between the seal member and the disk valve body. This fixing portion provides a stable mounting surface that prevents contraction-induced deflection of the disk valve body while maintaining ease of seal member installation and fixation.
3Ease of manufacture
If the disk valve flatness is degraded, then manufacturing becomes easier, but fluid leakage occurs resulting in unstable damping force characteristics
Solution Approach 1:
The disk valve is pre-deflected during assembly to ensure optimal contact with the valve seat before the shock absorber enters service. This preliminary positioning ensures reliable sealing and stable damping force characteristics from the start, eliminating the need for field adjustments while maintaining manufacturing simplicity.
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 enables stable damping force characteristics across a wide range of piston speeds, including low speeds, by maintaining disk valve flatness and adjusting valve-opening pressures, thus meeting the demand for 'soft' damping force settings without the need for preload, ensuring efficient operation and reduced fluid leakage.
Implementation Method 1
a ring-shaped seal member made of an elastic material, e.g. rubber
Implementation Method 2
The pressure in the back-pressure chamber is applied to the disk valve in the direction for closing the disk valve
Data Source
AI summary
In response to extension and compression of a piston rod, a piston slidingly moves in a cylinder, causing a flow of hydraulic oil. The hydraulic oil flow is controlled by a disk valve to generate a damping force. An elastic seal member fixed to the rear side of the disk valve is fitted to a recess in a pilot body to form a pilot chamber. The valve-opening operation of the disk valve is controlled by the pressure in the pilot chamber. The elastic seal member has an extension extended and fixed to the front side of the disk valve. Thus, forces acting on the rear and front sides of the disk valve due to shrinkage of the elastic seal member during fixing process balance and cancel each other out. Accordingly, it is possible to prevent warping of the disk valve and to obtain stable damping force characteristics.