Telescopic Fork Leg Sealing via Dynamic Pressure Compensation
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Solution Overview
Problem
Telescopic spring fork legs face challenges in maintaining consistent response to road bumps during dynamic operation due to changing internal pressure, leading to unsatisfactory sealing and increased friction, which affects the vehicle's handling and longevity of the damping fluid.
Innovation Solution
Incorporating a fluid passage between the receiving chamber and receiving space to allow damping fluid to flow out, maintaining constant pressure and reducing the preload on the sealing lip, thereby preventing air ingress and minimizing friction and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the preload of the coil spring is increased to improve sealing performance, then the sealing behavior is improved, but the friction between the sealing lip and the inner tube increases, worsening the responsiveness and wear characteristics
Solution Approach 1:
The patent introduces a dynamic pressure compensation mechanism where the receiving chamber communicates with the gap between inner and outer tubes through fluid passages. This allows the receiving chamber pressure to dynamically adjust during compression and rebound, automatically compensating for pressure changes without requiring increased spring preload, thus maintaining sealing performance while preserving responsiveness.
Solution Approach 2:
The patent changes the pressure parameter in the receiving chamber by providing fluid passages that connect it to the gap space. This allows the pressure in the receiving chamber to vary dynamically with fork leg compression and rebound, compensating for pressure changes that would otherwise require higher sealing lip preload, thereby maintaining low friction while ensuring sealing.
2Reliability
If the preload of the coil spring is increased to improve sealing performance, then the sealing behavior is improved, but the wear characteristics of the sealing lip worsen
Solution Approach 1:
The dynamic pressure compensation mechanism allows the receiving chamber pressure to automatically adjust during operation, maintaining adequate sealing lip preload without requiring permanently high spring tension. This reduces cumulative wear on the sealing lip while maintaining sealing effectiveness throughout the service life.
Solution Approach 2:
The system uses the damping fluid pressure itself to compensate for sealing requirements. The fluid passages allow pressure from the damping fluid to contribute to maintaining sealing lip contact, reducing reliance on high spring preload and thereby reducing wear on the sealing lip during normal operation.
3Reliability
If the preload of the coil spring is increased to improve sealing performance, then the sealing behavior is improved, but the breakaway torque increases, worsening the responsiveness
Solution Approach 1:
The patent changes the pressure parameter in the receiving chamber by providing fluid passages that connect it to the gap space. This allows the pressure in the receiving chamber to vary dynamically, compensating for sealing requirements without requiring high spring preload, thereby maintaining low breakaway torque and good responsiveness.
4Stability of the object's composition
If the internal pressure changes during dynamic operation, then the sealing behavior deteriorates, but providing a fluid passage allows damping fluid to flow out, maintaining constant pressure
Solution Approach 1:
The fluid passages create a feedback mechanism where pressure changes in the receiving chamber during compression and rebound are automatically compensated by fluid flow to and from the gap space. This feedback loop maintains relatively constant pressure conditions, ensuring consistent sealing behavior throughout the dynamic operation cycle.
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 ensures consistent response behavior to road bumps, reduces friction and wear, and extends the lifespan of the damping fluid by maintaining constant internal pressure and reducing the need for frequent fluid changes.
Implementation Method 1
the elastic deformation of the sealing lip due to its contact with the outer circumferential surface of the inner tube
Implementation Method 2
a fluid film formed by the damping fluid, in the form of the fork oil provided in the telescopic fork leg
Implementation Method 3
the fork oil, acting as the damping fluid, is present in the outer tube or stanchion
Implementation Method 4
the friction between the sealing lip and the outer circumferential surface of the moving inner tube or fork tube
Data Source
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AI summary
The invention relates a telescopic suspension fork leg (1, 43), having an inner tube (2) and an outer tube (3) as well as a damping device (7) and a spring device (5), which is arranged within a first chamber (5) formed within the inner tube (2) or outer tube (3) and is supported on a second chamber (6) formed by the damping device (7). The telescopic suspension fork leg (1, 43) is designed to receive a damping fluid, wherein the damping device (7) has a piston (9) supported on a piston rod (8), said piston (9) having an upper and a lower piston surface (10; 11) and being displaceable within a damping tube (13) which is arranged substantially concentrically with respect to the inner tube (2) and which is enclosed by an annular chamber (14) arranged substantially concentrically with respect to the damping tube (13). A gap space (15) is formed between the inner tube (2) and the outer tube (3), and a sliding bushing (28) which radially encloses the inner tube (2) is provided. The telescopic suspension fork leg (1, 43) has a sealing device (24) which radially encloses the inner tube (27) and which has at least one sealing means (25) which is supported on an outer circumferential surface (27) of the inner tube (2), wherein a receiving chamber (37) is provided for receiving damping fluid between the sealing device (24) and the sliding bushing (28), wherein the telescopic suspension fork leg (1, 43) has at least one fluid passage (38) between the receiving chamber (37) and a receiving space (39) provided on the telescopic suspension fork leg.