Discrete Lost Motion Valve Actuation for Variable Timing and Lift
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Solution Overview
Problem
Existing valve actuation systems in internal combustion engines face challenges in adjusting valve timing and lift to optimize performance across varying operating conditions due to the use of fixed profile cams, which limits flexibility and increases cost, packaging, and size constraints.
Innovation Solution
A discrete lost motion device is introduced, comprising a housing and a plunger controllable between rigid and unlocked states, supported by adjacent valve train components, allowing for flexible adjustment of valve actuation motions through hydraulic control, and enabling rotation and pivoting configurations to accommodate various engine operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed profile cams are used for valve actuation, then the valve actuation system is simple and reliable, but the ability to adjust valve timing and lift is limited
Solution Approach 1:
The valve train system is segmented into modular components: fixed profile cams provide base motion, while discrete lost motion devices are inserted at specific locations in the valve train linkage to provide variable motion adjustment. This segmentation allows the system to maintain simplicity where fixed cams work while adding adjustability only where needed through modular lost motion devices.
Solution Approach 2:
Lost motion devices serve as intermediary elements inserted between the cam and valve components. These devices mediate between the fixed cam profile and the valve actuation requirements, allowing the fixed cam to provide reliable base motion while the intermediary lost motion device provides the necessary variable timing and lift adjustment capability.
2Productivity
If variable valve actuation is implemented to optimize performance, then engine performance and fuel economy improve, but cost and packaging constraints increase
Solution Approach 1:
The lost motion devices are designed as relatively simple, discrete components that can be manufactured cost-effectively and replaced if needed. Rather than implementing complex expensive variable valve actuation systems throughout the entire valve train, discrete lost motion devices provide the necessary variability at minimal cost, allowing performance optimization without excessive manufacturing burden.
Solution Approach 2:
Variable valve actuation capability is applied locally rather than uniformly throughout the entire valve train. Lost motion devices are strategically positioned at specific locations where timing and lift adjustment are most beneficial, allowing performance optimization in critical areas while maintaining simplicity elsewhere, thereby reducing overall cost and packaging requirements.
3Adaptability or versatility
If lost motion devices are used to adjust valve actuation, then valve timing and lift can be varied, but the device complexity increases
Solution Approach 1:
The lost motion devices incorporate dynamic elements that allow transition between different operational states. The devices can dynamically adjust between conveying full cam motion to the valve and absorbing portions of the cam motion, providing variable valve timing and lift control. This dynamic capability enables adaptability without requiring entirely complex variable geometry mechanisms throughout the valve train.
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 provides a cost-effective and space-efficient mechanism for adjusting valve timing and lift, enhancing engine performance, fuel economy, and reducing emissions by allowing for dynamic control of valve actuation motions.
Implementation Method 1
controllable between a first state in which the plunger is rigidly maintained relative to the housing and a second state in which the plunger is permitted to reciprocate relative to the housing
Data Source
AI summary
A valve actuation system comprises a first arm having a first arm contact surface and operatively connected to a valve actuation motion. A second arm having a second arm contact surface is operatively connected to the at least one engine valve. A discrete lost motion device is provided that is controllable between a first, motion conveying state and a second, motion absorbing state. The discrete lost motion devices comprises a plunger contact surface and a housing contact surface. The housing contact surface is configured to engage one of the first or second arm contact surfaces, and the plunger contact surface is configured to engage another of the first and the second arm contact surfaces. The first and second arm contact surfaces, the housing contact surface and the first plunger contact surface are configured to support the discrete lost motion device between the first arm and the second arm.