Front Fork Throttle Flow Path for Stable Damping Response
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Solution Overview
Problem
The existing front fork design in JP-A No. 2002-161940 suffers from instability in damping force response due to air reservoirs in the annular gap chamber, leading to delayed damping force generation and increased risk of oil leakage, especially when high damping forces are required.
Innovation Solution
Incorporation of check valves and throttle flow paths in the piston and partition wall to control oil flow between oil chambers, along with volumetric capacity compensating flow paths and annular check valves to stabilize damping forces and enhance sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the inner tube extends and retracts with respect to the outer tube, then the annular gap chamber extends and retracts, but air is compressed in the annular gap chamber causing unstable damping force and response delay
Solution Approach 1:
The patent extracts and removes air from the annular gap chamber by providing a communication passage that connects the annular gap chamber to the lower oil chamber, allowing air to be bled out and replaced with oil, thereby eliminating the air compression problem that causes unstable damping force
Solution Approach 2:
The patent introduces oil as an intermediary substance that fills the annular gap chamber through the communication passage, replacing air and preventing compression, thus stabilizing the damping force response
2Force
If high damping forces are required, then the compression side damping force is set higher, but oil leakage increases due to high pressure applied to seal members
Solution Approach 1:
The patent introduces a throttle flow path as an intermediary flow control mechanism between the lower oil chamber and the annular gap chamber, regulating oil flow to provide damping force without requiring excessive pressure that would compromise seal integrity
Solution Approach 2:
The patent changes the flow resistance parameter by providing a throttle flow path with controlled opening, allowing high damping force to be achieved through flow restriction rather than pressure increase, thereby maintaining sealing performance
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
Stabilizes damping force generation by preventing air compression in the annular gap chamber, reduces oil leakage risk, and allows for adjustable damping force settings without increasing seal member pressure resistance, thus improving overall performance and reliability.
Implementation Method 1
a check valve which allows an inflow of the oil form the oil reservoir chamber in the upper portion of the partition wall portion to the oil chamber in the outer periphery of the hollow pipe in the compression stroke, and may inhibit an outflow of the oil from the oil chamber in the outer periphery of the hollow pipe to the oil reservoir chamber in the upper portion of the partition wall portion in the extension stroke
Implementation Method 2
a damping force caused by a passage resistance generated in the hole, is generated
Implementation Method 3
a spring load adjusting means (30) is provided in a center portion of the cap bolt (23)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In a front fork (10), a throttle flow path (70) is provided between a hole (61) which is provided in an inner tube (12) and is communicated with an annular gap chamber (60), and a lower oil chamber (25B) in an outer periphery of a hollow pipe (22).