Hydraulic Shock Absorber Post-Assembly Liquid Injection
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Solution Overview
Problem
Existing hydraulic shock absorbers face difficulties in injecting operating liquid into the cylinder after assembly, particularly in upright configurations where the cylinder is connected to the wheel side, due to the closed opening on the vehicle body side and the presence of a seal member and free piston, making it challenging to inject the liquid from either the vehicle body or wheel side.
Innovation Solution
The hydraulic shock absorber design includes a first and second injection portion on the piston rod, with the first injection portion located outside the damper stroke range and the second injection portion on the piston side, allowing for easy injection of the operating liquid through gaps formed between these portions and a seal member, enabling liquid to be injected after the cylinder is assembled to the shock absorber body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cylinder is assembled to the shock absorber body after the operating liquid is sealed in the liquid chamber, then the number of components and assembling processes increase, but if the operating liquid is injected after assembly, then injection becomes difficult due to closed openings
Solution Approach 1:
The injection portions are provided on the piston rod before final assembly, allowing the operating liquid to be injected through the rod guide opening after the cylinder is assembled to the shock absorber body. This preliminary preparation of injection pathways enables post-assembly injection without requiring additional components or complex disassembly procedures.
2Reliability
If a seal member is provided on the inner periphery of the rod guide to seal the piston rod, then sealing performance improves, but injection of operating liquid from the vehicle body side becomes difficult
Solution Approach 1:
The injection portions on the piston rod serve as intermediary elements that enable the operating liquid to pass through the sealed rod guide opening. The liquid flows through gaps between the injection portions and the rod guide, allowing injection while maintaining the sealing function of the seal member during normal operation.
3Ease of operation
If the first injection portion is provided outside the damper stroke range, then injection access is improved, but the piston rod structure becomes more complex
Solution Approach 1:
The piston rod is designed with multiple functions: it serves as both the mechanical component for damping operation and as the injection device. The injection portions are integrated into the piston rod structure, allowing the same component to perform both damping and liquid injection functions without requiring separate injection devices.
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 configuration facilitates easy and efficient injection of the operating liquid into the hydraulic shock absorber, reducing the number of components and assembly processes, and allows for effective operation even in upright configurations where traditional injection methods are hindered.
Implementation Method 1
an annular bush fitted in an inner periphery of the rod guide, the bush pivotally supporting the piston rod movably in an axial direction, wherein the piston rod includes a columnar sliding shaft portion contacting slidably with the bush
Implementation Method 2
a seal member contacting slidably with an outer peripheral surface of the sliding shaft portion
Implementation Method 3
a damping valve giving resistance to a flow of the operating fluid passing through the piston passage
Implementation Method 4
in extension/contraction of the piston rod going into/out of the cylinder, the operating liquid in one of the chambers pressurized by the piston passes through the piston passage and moves to the other chamber
Data Source
AI summary
A hydraulic shock absorber includes a cylinder connected to a wheel side, a liquid chamber formed in the cylinder and filled with an operating liquid, an annular rod guide fixed to the cylinder and closing a vehicle body side of the liquid chamber, a piston rod connected to the vehicle body side, penetrating a shaft core part of the rod guide, and going into/out of the cylinder, a piston held by the piston rod and dividing the liquid chamber into an extension-side chamber and a compression-side chamber, and an annular bush fitted in an inner periphery of the rod guide and pivotally supporting the piston rod, movably in an axial direction, in which the piston rod includes a columnar sliding shaft portion in sliding contact with the bush and a first injection portion for injecting the operating liquid provided on a side opposite to the piston of the sliding shaft portion and outside a range of a damper stroke.