Motorcycle Power Valve Hitless Control Upgrade
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The Yamaha Power Valve System (YPVS) in off-road motorcycles experiences a hesitation followed by a surge of power as the adjustable exhaust port control rod is rotated from a valve closed position to a valve open position due to the combined force of the three valves and governor linkage, leading to a 'HIT' problem that no amount of tuning or available products can resolve.
Innovation Solution
A hitless power valve system upgrade kit is introduced, featuring a closing fork with forked arms and two torsion springs that bias the center adjustable exhaust valve to an open position, overcoming the open spring bias and eliminating resistance on the governor, allowing smooth operation without hesitation or surging by changing the connection between the main center power valve and the control rod.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the original YPVS design with closed-center valve bias is used, then low RPM torque is improved, but hesitation and power surging occur during valve transition
Solution Approach 1:
The patent inverts the spring bias direction from the original design. Instead of the spring biasing the center valve closed (original YPVS), the modified spring biases the center valve open. This inversion changes the valve transition characteristics, allowing smooth opening without hesitation while maintaining the beneficial low RPM torque characteristics of the closed-valve configuration.
Solution Approach 2:
The patent modifies the spring parameter (bias direction) to change the valve operation characteristics. By changing the spring bias from closed-position to open-position, the system achieves smooth valve transition without the hesitation and power surging that occurred in the original design, while preserving the desired torque characteristics.
2Power
If the center valve is spring biased closed in the original YPVS, then low RPM torque is maximized, but resistance on the governor linkage causes hesitation
Solution Approach 1:
The patent inverts the spring bias direction to eliminate the harmful resistance force on the governor linkage. By biasing the center valve open instead of closed, the spring force assists rather than resists the governor linkage during valve transition, eliminating hesitation while maintaining low RPM torque through the forked arm mechanism.
Solution Approach 2:
The patent converts the potentially harmful resistance force into a beneficial assisting force. The spring that originally created resistance and hesitation during valve opening is reconfigured to provide assisting force, smoothening the transition while the forked arms maintain the necessary valve control for optimal torque production.
3Power
If tuning adjustments are made to the original YPVS, then power delivery can be optimized, but the fundamental HIT problem cannot be resolved
Solution Approach 1:
The patent applies a fundamental design inversion rather than incremental tuning adjustments. By reversing the spring bias direction and reconfiguring the linkage with forked arms, the system eliminates the root cause of the HIT problem, providing consistent and reliable power delivery across all RPM ranges without the limitations of tuning adjustments.
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 upgrade kit ensures smooth and linear engine operation throughout the RPM range, eliminating the 'HIT' problem and increasing torque at lower RPMs, with the engine producing consistent power without hesitation or surging.
Implementation Method 1
Two torsion springs mountable by sliding over the adjustable exhaust port control rod on either side of a closing fork mounting bolt secures the closing fork to the adjustable exhaust port control rod. Each torsion spring has a first extended leg stoppable by a surface of an engine and a second leg stoppable by a transverse post of the center adjustable exhaust valve. Both of the two torsion springs cause a spring bias of the center adjustable exhaust valve to a center valve open position.
Data Source
AI summary
A closing fork and open spring bias of a center power valve for a hitless control of an adjustable exhaust port 2-stroke motorcycle engine includes a closing fork which includes a flat plate that extends into two substantially parallel flat closing fork arms. An internal closing fork base section cylindrical wall accepts a shaft inserted there through. Each torsion spring of two torsion springs has a first extended leg including an approximately 90-degree bend about where the first extended leg extends out from a spring body of each torsion spring and a second leg extending straight out of a body of each torsion spring. Each of the torsion springs is a mirror of each other where the first extended leg extends from a different side. An upgrade kit and a method to convert a power valve system 2-stroke motorcycle engine to a hitless operation are also described.