Hydraulic End Stop Tube With Self-Adapting Shock Absorber Braking

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Solution Overview

Problem

Existing hydraulic shock absorbers for motor vehicles lack an automatic mechanism to adapt to varying loads, leading to inadequate braking performance during different loading conditions, which affects safety and comfort.

Innovation Solution

A hydraulic shock absorber design featuring a piston sliding in an inner tube with a stop piston and a plug system, controlled by dual return springs, which automatically adjusts the opening and closing of holes in the stop tube to provide adaptive braking based on load conditions, ensuring comfort and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a manual control system is used to adjust the closing of holes in the end stop, then the level of braking can be adjusted, but the system cannot automatically adapt to different loads

Engineering Contradiction:
Improveadaptability to different loadsVSAvoidcomplexity of control system
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The end stop system automatically adjusts its braking characteristics based on load conditions without external control. The slider moves passively in response to pressure differential between chambers, self-regulating the opening/closing of holes in the stop tube according to the actual load on the shock absorber.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system uses hydraulic pressure differential between the front chamber and rear main volume to control the position of the slider. The pressure difference drives the slider to appropriate positions, automatically adjusting fluid flow through holes in the stop tube based on load conditions.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Productivity

If a slider with slow dynamics is used in the end stop, then comfort is maintained for lightly loaded vehicles, but inadequate braking performance occurs for heavily loaded vehicles

Engineering Contradiction:
Improvebraking performanceVSAvoidadaptability to load conditions
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The slider's dynamics are made adaptive rather than fixed. The slider responds dynamically to pressure differential - moving slowly for comfort during light loads, but capable of faster response when pressure differential increases under heavy loads, ensuring adequate braking performance across all conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the effective damping parameters by moving the slider to different positions in the stop tube. This adjusts which holes are open or closed, changing the fluid flow characteristics and braking force to match the current load condition.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If holes in the stop tube are closed to provide strong braking for loaded vehicles, then safety is improved, but the system loses flexibility for lightly loaded vehicles

Engineering Contradiction:
ImprovesafetyVSAvoidflexibility of end stop
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The hole closure is dynamic rather than fixed. Holes in the stop tube are opened or closed based on the slider position, which is determined by real-time pressure differential. This provides strong braking (closed holes) when needed for safety under heavy loads, while maintaining flexibility (open holes) for comfort under light loads.

Inventive Principle:
Principle #15Dynamics

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 design achieves self-adaptive passive adjustment of the limit stop, providing optimal braking performance across varying loads, maintaining comfort and road holding through progressive braking, without the need for external control systems.

Implementation Method 1

a front return spring arranged in the front chamber, resting on the bottom of the shock absorber to return it to a rear position, and a rear return spring bearing on the shock absorber piston to return it to a forward position

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

this plug comprising a main bearing surface on the stop tube closing in the rear position of the rear holes of the tube and in the front position of the front holes of the tube

Methodology Applied
Scientific EffectFluid pressure: Pressure Increase

Implementation Method 3

a stop piston entering an end-of-travel stop tube having holes which slow down the fluid exiting from this stop tube

Methodology Applied
Scientific EffectHydraulic damping: Viscous Damping

Data Source

PatentEP3942196B1Fluid damper featuring a self-adapting end stop with a chamber ahead of a slider
Publication Date: 2023.04.12 STELLANTIS AUTO SAS
  • EP3942196B1 patent drawingFigure 1~3
  • EP3942196B1 patent drawingFigure 4~6

AI summary

Disclosed is a hydraulic shock absorber comprising a shock absorber piston (6) which slides in an inner tube (4) and receives, at the front, a rod (10) comprising, at its end, a stop piston (12) that penetrates into an end stop tube (14) having bores (22, 24) that decelerate the fluid exiting said tube (14), the shock absorber comprising a plug (30) which closes a front chamber (40) having a leakage flow rate and which is retained axially between a front restoring spring (44) resting on the shock absorber base (16) in order to return the plug to a rear position, and a rear restoring spring (46) resting on the shock absorber piston (6) in order to return the plug to a front position, the plug (30) comprising a main bearing surface (38) on the stop tube (14), said main bearing surface (38) closing, in the rear position, rear bores in the tube (22) and, in the front position, front bores in the tube (24).