Variable Valve Lift Apparatus for V-Type Engine Torque Stability
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Solution Overview
Problem
Existing continuous variable valve lift systems for internal combustion engines face challenges in achieving optimal valve operation across varying engine speeds, particularly in V-type engines, where maintaining symmetric valve profiles to minimize engine torque fluctuation is difficult, leading to increased weight and complexity.
Innovation Solution
A continuously variable valve lift apparatus featuring an input cam, follower, output cam, and control portion with elastic members and a straight line guide, allowing for adjustable valve lift and symmetric valve profiles by offsetting rotation centers and using a ramp section to prevent rapid valve profile changes, enabling operation in V-type engines with reduced weight and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a continuous variable valve lift system is designed to achieve optimal valve operation across varying engine speeds, then valve lift adjustment capability is improved, but device complexity increases
Solution Approach 1:
The valve lift control system is segmented into distinct functional components: an input cam for receiving camshaft rotation, a follower mechanism with pivoting capability, an output cam for valve actuation, and a control portion with a follower supporting portion. This segmentation allows each component to perform its specific function independently, simplifying the overall design while maintaining continuous variable valve lift capability.
Solution Approach 2:
The follower mechanism incorporates a pivoting follower that can dynamically change its angle relative to the camshaft through the follower supporting portion. This dynamic adjustment capability enables continuous variable valve lift without requiring complex electronic control systems, as the mechanical pivoting action directly translates camshaft rotation into variable valve lift amounts.
2Stability of the object's composition
If symmetric valve profiles are maintained in V-type engines to minimize torque fluctuation, then engine stability is improved, but device complexity increases
Solution Approach 1:
The follower supporting portion incorporates an asymmetric design with an offset rotation center that is deliberately positioned away from the camshaft center. This asymmetric offset creates symmetric valve profiles in V-type engines by compensating for the natural asymmetry introduced by the engine's V-configuration, thereby minimizing torque fluctuation while maintaining a relatively simple mechanical structure.
3Productivity
If valve lift operation range is increased to improve engine performance, then engine efficiency is improved, but device complexity increases
Solution Approach 1:
The follower mechanism introduces an additional rotational dimension by allowing the follower to pivot around an offset center in the follower supporting portion. This extra degree of freedom enables the system to achieve a wide valve lift operation range without requiring multiple separate mechanisms, as the pivoting action naturally varies the valve lift amount across a broad range while maintaining mechanical simplicity.
4Stability of the object's composition
If rapid valve profile changes are prevented to ensure smooth operation, then valve operation smoothness is improved, but device complexity increases
Solution Approach 1:
The output cam incorporates a ramp section that is designed beforehand to prevent rapid valve profile changes. This ramp section acts as a cushioning element that gradually transitions the valve from the closed to open position, smoothing out any abrupt movements and ensuring gentle valve operation throughout the lift cycle without requiring additional damping mechanisms.
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 apparatus provides an increased operation range for valve lift with a consistent valve profile across both banks of a V-type engine, minimizing engine torque fluctuation and allowing for efficient adjustment of valve lift, including cylinder deactivation, while maintaining durability and simplicity in design.
Implementation Method 1
A first elastic member may be disposed between the follower and the follower supporting portion, and supply elastic force to the follower so that the follower is biased toward the input cam
Implementation Method 2
A second elastic member may be disposed behind the output cam for supplying elastic force to the output cam so that the output cam is biased toward the follower
Data Source
AI summary
A continuously variable valve lift apparatus includes an input cam disposed to a camshaft and rotating, a follower supporting portion rotatably disposed to the camshaft for changing a relative angle of the follower with respect to the camshaft, a follower that includes a center shaft, is connected with the follower supporting portion via the center shaft, and pivots around the center shaft by receiving rotation movement of the input cam, a straight line guide, an output cam that contacts the follower and reciprocates along the straight line guide, and a valve opening unit that is opened by pushing of the output cam.