Telescopic Fork Travel Sensing Inside the Piston Rod
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Solution Overview
Problem
Existing telescopic fork systems for motorcycles, especially off-road sports motorcycles, face challenges in protecting sensor devices from damage and interference, such as contamination, dust, stones, and engine vibrations, which can affect signal quality and damping behavior.
Innovation Solution
The telescopic fork system incorporates a path measurement device with a magnetic operational sensor device located inside the piston rod of the telescopic dampers' fork, protected from external influences. This configuration includes a magnetic device, such as a ring magnet, radially defined or surrounding the sensor device, allowing for three-dimensional magnetic field recording and effective travel measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sensor module is arranged on the outside of the outer tube, then the sensor device is easily accessible and simple to install, but the sensor device is exposed to damage from stones, dust, rain, and engine vibrations
Solution Approach 1:
The sensor device is nested inside the hollow piston rod, which serves as a protective housing. The piston rod acts as an inner container within the larger fork assembly, protecting the sensor from external damage while maintaining a compact structure. This nesting approach resolves the contradiction by providing both protection and accessibility.
Solution Approach 2:
The hollow piston rod serves as an intermediary structure between the sensor device and the external environment. It mediates the conflict by providing a protected pathway and housing for the sensor, shielding it from stones, dust, rain, and vibrations while still allowing the sensor to function properly through controlled openings.
2Ease of operation
If the sensor module is arranged on the outside of the outer tube, then the sensor device is easily accessible, but signal quality is affected by engine vibrations and external interference
Solution Approach 1:
The sensor device is nested within the hollow piston rod, creating an isolated environment that shields sensitive electronic components from engine vibrations and external electromagnetic interference. This nested configuration maintains signal integrity while keeping the sensor integrated into the fork assembly.
3Reliability
If the sensor device is protected inside the piston rod, then the sensor is protected from damage and interference, but the arrangement becomes more complex and space-constrained
Solution Approach 1:
The hollow piston rod serves multiple functions simultaneously: it acts as a structural component of the fork, provides a protective housing for the sensor device, and serves as a mounting structure for the magnet. This multi-functionality reduces overall device complexity by eliminating the need for separate protective housings and mounting brackets.
Solution Approach 2:
The protective housing, mounting structure, and structural fork component are merged into a single hollow piston rod assembly. This consolidation simplifies the overall device architecture while providing comprehensive protection and support for the sensor device.
4Measurement precision
If the magnet device is radially spaced from the sensor device, then three-dimensional magnetic field recording is enabled for accurate travel measurement, but the device requires more internal space and precise positioning
Solution Approach 1:
The measurement system transitions from linear or planar sensing to three-dimensional magnetic field sensing. By utilizing the radial spacing between the magnet and sensor, the system captures magnetic field variations in multiple dimensions, enabling precise travel measurement through spatial field analysis rather than simple linear displacement.
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 design effectively protects the sensor device from contamination and vibrations, ensuring reliable signal quality and improved damping behavior by accurately measuring travel and relative speed, thereby enhancing the motorcycle's suspension performance.
Implementation Method 1
the displacement measuring device has a magnet-operative sensor device arranged in an interior of the piston rod and at least one magnet device radially spaced from the sensor device
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A telescopic spring fork (1) is provided with two telescopic fork legs (2), each of which is provided with an outer tube (7) having an axial longitudinal extent and an inner tube (8) having an axial longitudinal extent that is axially displaceable relative to it in the direction of the axial longitudinal extent, wherein one telescopic fork leg (2) is a telescopic spring fork leg (3) provided with a spring device (10) and the other telescopic fork leg (2) is a telescopic damper fork leg (4) provided with a damper device (22) and having a piston (25) arranged on a piston rod (24), and the telescopic spring fork (1) is provided with a displacement measuring device (25) which is configured to detect the distance traveled by the axial displacement of the inner tube (8) relative to the outer tube (7).wherein the displacement measuring device (25) comprises a magnetooperative sensor device (27) arranged in an interior (26) of the piston rod (24) and at least one magnet device (28) radially spaced from the sensor device (27).