Variable Valve Mechanism Helix Angle Cylinder Cutoff
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Solution Overview
Problem
Conventional variable valve mechanisms cannot adapt to cylinder cutoff operations where some cylinders are deactivated, as they uniformly change valve lifts across all cylinders.
Innovation Solution
A variable valve mechanism with swing members having different helix angles for helical splines, allowing the control shaft to displace between normal and cylinder cutoff positions to selectively deactivate certain cylinders, enabling operation switching between normal and cylinder cutoff modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the control shaft displaces all slider gears uniformly to change valve lifts, then the valve lift adjustment is simple and unified, but the mechanism cannot adapt to cylinder cutoff operations where specific cylinders need to be deactivated
Solution Approach 1:
The patent applies local quality by giving each swing member a different helix angle for its helical splines. Specifically, swing members for cylinders to be deactivated have helix angles that cause the valve lift to become zero at the cylinder cutoff position, while swing members for active cylinders maintain their normal valve lift characteristics. This localized differentiation enables selective cylinder deactivation without requiring complex additional mechanisms.
Solution Approach 2:
The patent utilizes parameter changes by varying the helix angle parameter of the helical splines across different swing members. The helix angle serves as a design parameter that determines the valve lift characteristics at different control shaft positions. By pre-setting different helix angles during manufacturing, the system achieves adaptive cylinder cutoff functionality through a simple uniform displacement of the control shaft.
2Ease of manufacture
If all swing members have the same helix angle, then the manufacturing and assembly are simplified, but the mechanism lacks the ability to selectively deactivate specific cylinders
Solution Approach 1:
The patent implements local quality by differentiating the helix angle parameter for swing members based on their assigned cylinder's operational status. Swing members for cylinders subject to cutoff have distinctly different helix angles compared to those for continuously active cylinders. This localized parameter differentiation enables the system to achieve cylinder cutoff capability while maintaining relatively simple manufacturing processes for each individual swing member type.
3Productivity
If the mechanism uniformly adjusts all valves, then the control system is simple, but it cannot improve fuel economy through selective cylinder deactivation
Solution Approach 1:
The patent employs parameter changes by incorporating different helix angle values into the helical splines of swing members. This parameter variation is established during the design and manufacturing phase, allowing the mechanism to inherently provide different valve lift characteristics for different cylinders. When the control shaft is displaced to the cylinder cutoff position, the varied helix angles automatically produce zero valve lift for designated cylinders while maintaining normal operation for active cylinders, thereby enabling fuel economy improvement through selective deactivation.
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
Enables efficient operation switching between normal and cylinder cutoff modes, improving fuel economy by varying valve lifts based on engine characteristics, rather than simply deactivating non-operational cylinders.
Implementation Method 1
a slider gear that meshes with the input member and the output member via helical splines
Data Source
AI summary
A variable valve mechanism of an internal combustion engine includes a plurality of swing members and a variable device that displaces a control shaft to displace a plurality of slider gears of the swing members at a time, thereby changing valve lifts of the plurality of swing members at a time by meshing of helical splines. The swing members include a first swing member for a predetermined cylinder of a plurality of cylinders and a second swing member for a cylinder other than the predetermined cylinder, and a helix angle of the helical splines varies between the first and the second swing members. The variable device displaces the control shaft to a predetermined normal position to perform a normal operation, and displaces the control shaft to a predetermined cylinder cutoff position to perform a cylinder cutoff operation in which the second swing member does not drive a valve.