Self-Adapting Hydraulic End Stop for Variable-Load Shock Absorbers
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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 changes in vehicle load conditions, which affects comfort and safety.
Innovation Solution
A hydraulic shock absorber with a sliding valve and delay chamber, equipped with two return springs, automatically adjusts braking by closing or opening fluid outlets based on load conditions, ensuring comfort and safety through adaptive braking dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a manual control system is used to adjust the closing of holes in the end stop, then the braking force can be regulated, but the system cannot automatically adapt to different loads
Solution Approach 1:
The end stop system uses the vehicle's own suspension movement and load-induced pressure changes to automatically control the sliding valve, which in turn automatically adjusts the opening/closing of holes. The system serves itself by using the operational conditions (load variations) as the control input, eliminating the need for external manual control while achieving automatic adaptation to different loads.
Solution Approach 2:
The system establishes a feedback loop where the load condition affects the pressure in the control chamber, which moves the sliding valve to adjust the hole openings, which in turn modifies the braking force, which then affects the suspension movement that generated the original pressure signal. This closed-loop feedback enables automatic adaptation without external control systems.
2Adaptability or versatility
If a slide valve with multiple holes is used to provide flexible braking, then comfort is improved for lightly loaded vehicles, but the system cannot provide sufficient braking force for heavily loaded vehicles
Solution Approach 1:
The end stop system transitions from a static configuration (fixed hole openings) to a dynamic one where the sliding valve continuously adjusts the opening/closing of holes based on real-time load conditions. The system's braking characteristics change dynamically in response to suspension movement and pressure variations, enabling it to provide appropriate braking force whether the vehicle is lightly or heavily loaded.
Solution Approach 2:
The system changes the effective parameters of the end stop by varying which holes are open or closed, and to what extent, based on the load condition. The sliding valve adjusts the effective opening area and flow resistance of the fluid passages, thereby changing the braking force parameter to match the current load, ensuring reliable braking performance across different operating conditions.
3Reliability
If holes in the stop tube are closed to stiffen the end-of-stroke stop for loaded vehicles, then safety is improved, but comfort is reduced due to increased braking force
Solution Approach 1:
The system applies different braking characteristics to different parts of the suspension stroke and different load conditions. Rather than uniformly stiffening the entire end stop, the sliding valve selectively closes specific holes at specific times, creating localized adjustments in braking force. This allows the system to provide enhanced safety when needed (preventing bottoming out under load) while maintaining comfort during normal operation with lighter loads.
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 provides comfortable and controlled braking for lightly loaded vehicles and significant damping for heavily loaded vehicles, ensuring both comfort and road holding by automatically adjusting the braking force based on load changes without external control systems.
Implementation Method 1
The timing chamber presents a leakage flow which strongly brakes the sliding of this slide relative to this piston, so as to obtain a slow dynamic of movement under the effect of the load differences of the two springs
Implementation Method 2
The piston is held axially between a front return spring, which bears against a fixed part of the shock absorber to return it to the rear position, and a rear return spring, which bears against the shock absorber piston to return it to the front position
Implementation Method 3
a hydraulic shock absorber having an end stop... a thrust piston retracting into a stop tube with fluid outlet holes... a sliding valve equipped with a timing chamber having a leakage flow
Data Source
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Figure 5
AI summary
Disclosed is a hydraulic shock absorber comprising a shock absorber piston (6) supporting, in the front, a rod (10) which comprises a stop piston (12) penetrating into an end stop tube (14), and which further comprises, on the front face of the stop piston (12), a first bore (20) comprising an outlet at the rear of the stop piston (12), on the side of the stop piston (12), a second bore (22) comprising an outlet at the rear of the stop piston (12), the shock absorber further comprising a sliding plug (30) which is equipped with a timing chamber (26) and which, in a front position, closes at least one outlet of the bores (20, 22) and, in a rear position, connects said outlets, the plug (30) being located between a front restoring spring (44) and a rear restoring spring (46) resting on the shock absorber piston (6).