Pilot-Valve Shock Absorber for Soft-Hard Damping Control
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Solution Overview
Problem
The existing damping valve systems face complexity in structure and difficulty in reducing soft side damping force characteristics, which hinders the improvement of vehicle riding comfort due to a constant flow path area of the main valve's orifice, leading to limited adjustment capabilities.
Innovation Solution
A shock absorber design incorporating a pilot chamber, introduction passage, and control valve with a first orifice that always communicates, a parallel first passage, and a check valve that opens at a predetermined differential pressure, allowing for adjustable damping force generation by varying the valve opening pressure and flow path areas, thereby enhancing riding comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a constant flow path area orifice is used in the main valve, then the structure is simple, but the soft side damping force characteristic cannot be reduced, limiting riding comfort improvement
Solution Approach 1:
The single orifice is segmented into multiple orifices with different flow path areas. The pilot valve system divides the damping control into multiple stages, allowing the main valve to have a larger orifice area while still achieving soft side damping reduction through the pilot valve's controlled fluid flow to the actuator chamber.
Solution Approach 2:
The system transitions from a static constant flow path area orifice to a dynamic system where the pilot valve can vary the effective flow area by controlling fluid pressure to the actuator chamber. This allows the damping force to be dynamically adjusted based on piston velocity and direction, enabling both soft side and hard side damping control.
2Object-affected harmful factors
If the main valve is opened in two stages, then valve vibration is reduced and sound vibration performance is improved, but the structure becomes complex
Solution Approach 1:
The pilot valve acts as an intermediary device that controls the main valve's opening process. By using fluid pressure transmitted through the pilot passage to the actuator chamber, the pilot valve enables two-stage opening of the main valve without requiring complex mechanical linkages or multiple main valve components, thus reducing overall structural complexity while achieving vibration reduction.
3Strength
If a larger orifice area is used in the main valve, then hard side damping force is increased for stability, but soft side damping force cannot be reduced for comfort
Solution Approach 1:
The system uses different orifice areas in specific locations: a larger orifice area in the main valve for hard side damping and support, and smaller orifices in the pilot valve for soft side damping control. The pilot valve's smaller orifices create higher pressure drops that can reduce damping force during soft side operation, while the main valve's larger orifice ensures sufficient damping during hard side compression events.
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 allows for improved vehicle riding comfort by reducing damping force in soft side characteristics and increasing damping force in hard side characteristics, smoothing the change in damping force characteristics and reducing valve vibration, thus enhancing both comfort and stability.
Implementation Method 1
a first orifice 131 that always communicates
Implementation Method 2
a first check valve 117 that is opened at a predetermined differential pressure and allows a flow toward the control valve 68 through the first passage 133
Implementation Method 3
a control valve 68 provided in the pilot passage
Implementation Method 4
a main valve 32 that generates a damping force by controlling a flow of the fluid generated by sliding of the piston 5 in the cylinder 2
Data Source
AI summary
A shock absorber includes: a cylinder; a piston slidably inserted into the cylinder; a piston rod connected to the piston and extending outside the cylinder; a main valve that generates a damping force; a pilot chamber that applies pressure to the main valve; an introduction passage that introduces the fluid into the pilot chamber; a pilot passage that communicates the pilot chamber and a downstream side of the main valve with each other; and a control valve provided in the pilot passage. In an upstream side of the pilot passage from the control valve, the pilot passage is provided with a first orifice, a first passage provided in parallel with the first orifice, a first check valve that is opened at a predetermined differential pressure and allows a flow toward the control valve through the first passage, and a second orifice.