Suspension Unit Damping Shock Loads
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Solution Overview
Problem
The existing suspension unit for tracked vehicles experiences significant impact when piston and piston rod reach end positions, leading to a weight penalty in design to withstand such impacts.
Innovation Solution
Incorporation of damping means, including variable volume chambers and restrictors, to control fluid flow and decelerate the movement of piston and piston rod towards end positions, reducing shock loads by using apertures in connecting rods to manage fluid flow between chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the piston and piston rod are designed to withstand substantial impact at end positions, then the unit can operate without damping means, but the weight of the unit increases significantly
Solution Approach 1:
The patent applies beforehand cushioning by incorporating damping means (damping chambers and restrictors) that actively reduce the impact velocity of the piston and piston rod before they reach the end positions. The damping chambers filled with fluid and restricted flow paths create resistance that decelerates the moving components, cushioning the impact before it occurs. This allows the structural components to be designed for normal operating loads rather than extreme impact loads, significantly reducing weight while still protecting the unit from damage.
2Weight of moving object
If damping means is added to reduce impact, then the weight penalty is reduced, but the device complexity increases
Solution Approach 1:
The patent merges the damping function with the existing piston rod structure by making the piston rod hollow and incorporating damping chambers within it. The connecting rod also incorporates restrictors with apertures that serve dual purposes: connecting the damping chambers and controlling fluid flow. This integration of damping components into existing structural elements adds the necessary damping function while minimizing the increase in overall device complexity.
3Speed
If the piston and piston rod move quickly to end positions, then the suspension response is faster, but the impact shock load increases
Solution Approach 1:
The patent introduces fluid as an intermediary medium between the moving piston/piston rod and the end positions. The fluid in the damping chambers, flowing through restricted apertures, acts as a mediator that resists the rapid movement of components. This fluid intermediary creates a controllable deceleration force that reduces shock loads while still allowing the suspension to respond quickly to terrain variations, balancing speed and impact reduction.
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 damping mechanism effectively reduces shock loads by decelerating the movement of piston and piston rod, minimizing impact and weight penalties, ensuring smoother operation and reduced structural demands.
Implementation Method 1
a restrictor which controls the flow rate of fluid into or out of the chamber
Implementation Method 2
The piston slidable within the cylinder may be biased relatively to the piston rod towards the extended end position by gas pressure acting on the secondary piston
Implementation Method 3
The spring chamber on the other side of the partition may contain gas under pressure to exert a resilient force, through the oil, on the piston
Data Source
AI summary
A suspension unit, for example for a track-laying vehicle, comprises an oil-filled cylinder within which a piston, connected to a piston rod, is provided. The cylinder 4 is oil-filled, and communicates with an upper region of a spring chamber, the lower region 46 of which contains gas under pressure. The piston rod has a hollow interior filled with gas under pressure. The piston is connected by a connecting rod to a secondary piston which is slidable within the piston rod. On rebound the piston rod and the piston move relatively to each other between a retracted end position and an extended end position. During this movement and the return movement, oil is transferred, by way of apertures between damping chambers which serve to damp the relative movement of the piston and the piston rod so avoiding shock loading at the end positions of the movement.