Variable Hydraulic Rebound Stop for Shock Absorbers
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Solution Overview
Problem
Conventional hydraulic rebound stops in shock absorbers provide constant additional damping at the end of travel, which does not meet market expectations, and require a rubber cushion to prevent metal-to-metal contact, adding complexity and components.
Innovation Solution
A hydraulic shock absorber with a variable hydraulic rebound stop (HRS) that adjusts damping levels by varying fluid output through a changing cross-sectional fluid exit means, eliminating the need for a cushion-type device by ensuring fluid is trapped and preventing internal metal-to-metal contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional hydraulic rebound stop with a rubber cushion is used to prevent metal-to-metal contact at full extension, then reliability is improved, but device complexity increases due to additional components
Solution Approach 1:
The invention extracts and eliminates the rubber cushion component from the shock absorber system. Instead of using a separate cushion element to prevent metal-to-metal contact, the design relies on the hydraulic rebound stop mechanism itself to provide the necessary damping and contact prevention through fluid pressure alone.
Solution Approach 2:
The hydraulic rebound stop is designed to perform multiple functions: it provides end-of-travel damping during normal operation and simultaneously prevents metal-to-metal contact at full extension. This multi-functionality eliminates the need for a separate rubber cushion component while maintaining reliability.
2Reliability
If a rubber cushion is added to prevent metal-to-metal contact, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The invention removes the rubber cushion component entirely, reducing the number of parts that need to be manufactured, inventoried, and assembled. This extraction of unnecessary components directly reduces manufacturing costs while maintaining the reliability function through the hydraulic mechanism.
3Device complexity
If a constant damping rate is provided by the hydraulic rebound stop, then simplicity is maintained, but adaptability decreases as it does not meet market expectations for variable damping
Solution Approach 1:
The invention transitions from a static, constant damping rate to a dynamic, variable damping rate. The damping rate automatically adjusts based on the piston position and fluid pressure conditions, allowing the system to adapt to different operating conditions and meet market expectations for variable damping performance.
Solution Approach 2:
The damping rate is made variable by changing the effective orifice area through which fluid flows. As the piston approaches full extension, the orifice area changes, causing the damping rate to increase automatically. This parameter change enables adaptive damping without adding complex control mechanisms.
4Reliability
If a rubber cushion is used to prevent metal-to-metal contact, then reliability is improved, but assembly complexity increases
Solution Approach 1:
The invention eliminates the rubber cushion component, thereby removing the assembly steps required to install and position the cushion within the shock absorber. This simplification of the component list directly reduces assembly complexity and improves ease of manufacture.
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 a tunable and continuous increase in damping during the HRS-damping phase, simplifying manufacturing and assembly, improving reliability, and reducing costs by eliminating the need for additional components.
Implementation Method 1
the damping rate provided by the shock absorber becomes higher at the extreme ends of the rebound and compression strokes. The additional damping provided at the extreme ends prevent an abrupt halt of the piston rod travel
Implementation Method 2
When the shock absorber is in the extension mode and approaching the Full Extension position, the HRS-piston enters into the HRS-tube via the HRS-tube-in to put under pressure the fluid between the extension extremity of the HRS-tube and the HRS-piston
Data Source
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AI summary
A hydraulic shock absorber comprising a main tube divided, by a piston-rod extending through the extension chamber. The shock absorber is further provided with a hydraulic rebound stop, called HRS fixed in the extension chamber and comprising a HRS-tube restricting the main tube, bottom and an entry. The HRS also has HRS-piston freely slidably mounted on the rod and having a diameter adjusted to the HRS-tube and being provided with at least one fluid-passage substantially axially oriented. The axial displacements of the HRS-piston are limited between a Rebound-stop and a HRS-ring, both fixed to the rod. The fluid-passage is open to a flow of fluid when in abutment against the HRS-ring and being sealed when in abutment against the Rebound-stop. The HRS is further provided with at least one fluid-passage connecting the HRS-chamber to the extension chamber and providing to the fluid a way-out for an exiting flow generating a HRS-damping which is tunable and varies as the HRS-piston penetrates the HRS-tube, their relative position determining the size of the way-out.