Shock Absorber Damping Valve With Pilot Pressure Bypass
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Solution Overview
Problem
Existing fluid pressure dampers require manual part changes to adjust damping characteristics, and solenoid valves are exposed to high working fluid pressures, necessitating protection.
Innovation Solution
A fluid pressure dumper with a damping unit that includes a damping valve with variable resistance, a bypass passage with a solenoid valve to control pilot pressure, and relief valves to protect the solenoid valve from high pressures, allowing adjustment without part changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a solenoid valve is used to control pilot pressure for adjusting damping characteristics, then damping characteristics can be adjusted without part changes, but the solenoid valve is exposed to high pressure working fluid
Solution Approach 1:
A pilot pressure passage is introduced as an intermediary channel to guide a portion of the working fluid to the pilot pressure chamber of the damping valve. This mediator allows the solenoid valve to control damping characteristics indirectly through pilot pressure rather than directly exposing it to the full high pressure working fluid flow
Solution Approach 2:
The pilot pressure control function is extracted from the main high pressure working fluid path. By separating the pilot pressure supply into a dedicated passage that bypasses the main damping valve, the solenoid valve operates on a controlled portion of the fluid rather than the full high pressure stream
2Reliability
If the solenoid valve is protected from high pressure, then the valve reliability improves, but the system complexity increases with additional passages and components
Solution Approach 1:
The bypass passage serves multiple functions: it guides working fluid to the pilot pressure chamber for solenoid control, protects the solenoid valve from excessive pressure, and enables damping characteristic adjustment. This multi-functionality reduces the need for separate dedicated components for each function
Solution Approach 2:
The pilot pressure passage is integrated into the existing damping valve structure, combining the pressure control function with the damping mechanism. The bypass passage merges with the fluid flow path at strategic points, eliminating the need for completely separate protection systems
3Productivity
If damping characteristics are adjusted by changing the orifice plug, then the damping force can be modified, but parts must be disassembled and reassembled
Solution Approach 1:
The mechanical adjustment method of physically changing orifice plugs is replaced with a controllable valve system. The solenoid valve provides adjustable damping characteristics through electromagnetic control, eliminating the need for mechanical disassembly and reassembly of parts
Solution Approach 2:
The damping characteristics transition from fixed (requiring physical part changes) to dynamically adjustable. The damping valve can be repositioned or its opening adjusted in real-time through solenoid control, allowing continuous or discrete damping modifications without mechanical intervention
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 adjustable damping characteristics while safeguarding the solenoid valve, enhancing convenience and reliability by controlling damping based on vehicle conditions.
Implementation Method 1
a first restrictor portion configured to impart resistance to the flow of the working fluid guided to the solenoid valve from the first pressure chamber through the bypass passage
Implementation Method 2
a first relief valve configured to open when a pressure in the bypass passage reaches a predetermined relief pressure to release the pressure in the bypass passage to the second pressure chamber through the fluid passage
Implementation Method 3
a damping valve provided in the fluid passage, the damping valve being configured to impart variable resistance to the flow of the working fluid passing therethrough depending on positions
Implementation Method 4
a solenoid valve provided in the bypass passage, the solenoid valve being configured to guide a part of the working fluid in the bypass passage to the damping valve as a pilot pressure
Data Source
AI summary
A damping unit of a shock absorber has: a damping valve provided in a second fluid passage, the damping valve being configured to impart variable resistance to a flow of working oil passing therethrough depending on positions; a bypass passage connected to the second fluid passage so as to bypass the damping valve; a solenoid valve configured to control the flow of the working oil in the bypass passage guided to the damping valve as a pilot pressure for switching the positions of the damping valve; a bottom-side restrictor portion configured to impart resistance to the flow of the working oil guided from the second fluid passage to the solenoid valve; and a rod-side relief valve configured to release the pressure in the bypass passage to a rod side chamber through the second fluid passage.