Bicycle Dropper Post Locking Spring Cartridge
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Solution Overview
Problem
Existing dropper post locking spring cartridges require excessive force to open the piston valve, especially when the seat is loaded, and can lead to unintended seat post compression due to air entering the oil-only chamber, resulting in a spongy feel and potential damage or injury.
Innovation Solution
A dropper post assembly with a locking spring cartridge featuring an axially extending cylinder with a piston, a first chamber containing oil only, and a second chamber containing a combination of oil and gas, where the cartridge is configured to maintain consistent actuation force regardless of load and resist movement until a predetermined overload force is applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a locking spring cartridge with oil-only chamber is used, then the seat post maintains rigidity under load, but excessive force is required to open the piston valve
Solution Approach 1:
The hydraulic chamber is segmented into two separate chambers: a first chamber containing only oil for maintaining rigidity, and a second chamber containing a combination of oil and gas for reducing actuation force. This segmentation allows each chamber to serve its specific function independently, resolving the contradiction between rigidity and ease of operation.
Solution Approach 2:
Different local qualities are assigned to different chambers: the first chamber has oil-only composition for high rigidity and load-bearing capability, while the second chamber has oil-gas mixture for compressibility and reduced actuation force. This local differentiation allows the system to simultaneously achieve both rigidity where needed and ease of operation where required.
2Object-affected harmful factors
If air enters the oil-only chamber, then the seat post becomes compressible providing cushioning, but this leads to spongy feel and potential damage or injury
Solution Approach 1:
A second chamber containing a compressible gas-oil mixture acts as an intermediary between the rigid oil-only first chamber and external overload forces. This intermediary chamber absorbs excess energy during overload events, protecting the rigid first chamber from damage while preventing direct air contamination that would cause spongy feel.
Solution Approach 2:
The system incorporates beforehand cushioning by designing a dedicated second chamber with compressible gas mixture that can absorb overload energy before it reaches the rigid first chamber. This pre-configured cushioning mechanism protects the system during overload events without compromising the stability and responsiveness of the main hydraulic system.
3Reliability
If the piston valve is designed to resist movement under normal loads, then the seat post remains stable, but excessive force is needed to actuate the valve during operation
Solution Approach 1:
The valve system is segmented into two functional zones corresponding to the two chambers: the first chamber maintains stability and prevents unintended movement under normal loads, while the second chamber with compressible gas mixture facilitates easier valve actuation during intentional operation, resolving the contradiction between stability and ease of operation.
Solution Approach 2:
The system changes physical parameters by using different fluid compositions in different chambers: the first chamber uses incompressible oil for stability, while the second chamber uses compressible gas-oil mixture that reduces the force required for valve actuation, allowing both stability and ease of operation to be achieved through parameter differentiation.
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 reduces the actuation force required to operate the dropper post, maintains rigidity under normal loads, and provides a cushioning effect during overload situations, enhancing rider safety and post durability.
Implementation Method 1
a second chamber containing a combination of oil and gas, where the cartridge is configured to maintain consistent actuation force regardless of load
Implementation Method 2
a first chamber containing oil only... the cartridge configured so that moving the inner tube toward the retracted position expands the first chamber
Data Source
AI summary
A dropper post assembly for supporting a bicycle seat may include an outer tube extending along a post axis and an inner tube configured to be axially slidable within the outer tube by a travel distance that is at least 200 mm between a retracted and an extended position. A spring cartridge may have an unlocked configuration in which the spring cartridge exerts an extension force (FE) on the inner tube that biases the inner tube toward the extended position, and a locked configuration in which the spring cartridge is operable to generate a degassing force (FD) of between about 90 lbs and about 140 lbs to resist movement of the inner tube toward the retracted configuration.