Front Fork Damping Control via Sprung-Port Sensor Placement
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Solution Overview
Problem
Existing front fork systems for saddle riding vehicles face challenges in accurately measuring vibrations and adjusting damping forces due to the harsh unsprung vibration environment, which can lead to incorrect sensor readings and inadequate damping performance when sensors and solenoid valves are placed in unsprung portions.
Innovation Solution
The design incorporates a solenoid valve for extension-side damping force adjustment in the piston rod of one fork leg and another for compression-side damping force adjustment on the vehicle body side tube, along with a stroke sensor attached to the fork leg, ensuring both are placed in the sprung portion to improve measurement accuracy and damping control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the detection unit of the stroke sensor or the solenoid valve is disposed in the unsprung portion, then the device complexity is reduced, but the measurement precision and driving accuracy deteriorate due to strong vibrations
Solution Approach 1:
The piston rod serves as an intermediary transmission element that conveys the damping force adjustments from the solenoid valve (located in the sprung portion) to the damper in the unsprung portion, and transmits the detection signals from the stroke sensor to the control unit, thereby isolating sensitive components from vibration while maintaining functional connectivity
Solution Approach 2:
The front fork is divided into sprung and unsprung portions with distinct functional assignments: the sprung portion houses sensitive electronic components (solenoid valve, stroke sensor), while the unsprung portion contains the damper mechanism, allowing each segment to operate in its optimal vibration environment
2Ease of operation
If the solenoid valve and stroke sensor are placed in the unsprung portion, then the ease of operation is improved, but the reliability deteriorates due to incorrect sensor readings and inadequate damping control
Solution Approach 1:
The piston rod acts as a mechanical intermediary that transmits forces and signals between the sprung and unsprung portions, enabling the solenoid valve and stroke sensor to operate reliably in the vibration-free sprung portion while still controlling and monitoring the damper in the unsprung portion
Solution Approach 2:
The patent replaces direct mechanical mounting of electronic components in the unsprung portion with a mechanical transmission system (piston rod) that allows electronic components to be located in the sprung portion, substituting direct mechanical connection with mechanical signal/force transmission
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
This configuration allows for accurate detection and adjustment of damping forces, enhancing ride comfort by ensuring the solenoid valves and sensors operate effectively in a stable vibration environment, thereby improving the overall damping performance of the front fork.
Implementation Method 1
DE 42 44 204 A1 discloses an ultrasonic displacement measurement system for a shock absorber cushioning stroke. The ultrasonic displacement measurement system comprises a permanent magnet fixed to a cylinder of the shock absorber and a magnetostrictive waveguide arranged on an axial bore of a displacement element.
Implementation Method 2
a solenoid valve for extension-side damping force adjustment is provided in the piston rod of the one fork leg
Implementation Method 3
a damper that exerts a damping force
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
A front fork (F) of the present invention has: a cylinder (50) in which a damper (5) of one fork leg (2) is connected to an outer tube (40) on a vehicle body side; a piston rod (51) connected to an inner tube (41) on an axle side; and a piston valve (52) attached to the piston rod (51) and movably inserted into the cylinder (50). A variable throttle (7) for extension-side damping force adjustment is provided in the piston rod (51). A stroke sensor (8) has a detected element (81) attached to the cylinder (50), and a detection unit (80) that is attached to the piston rod (51) and detects a displacement of the detected element (81). A variable throttle (9) for compression-side damping force adjustment is attached to an outer tube (40) on the vehicle body side of another fork leg (3).