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, and incorporating lost motion devices is constrained by space and cost considerations.
Innovation Solution
A discrete lost motion device is implemented as a separate component within the valve train, supported by adjoining components and controlled between locked and unlocked states via hydraulic fluid, allowing flexible adjustment of valve actuation motions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed profile cams are used to provide valve actuation forces, then the valve actuation system is simple and reliable, but it is difficult to adjust valve timing and lift to optimize performance for various operating conditions
Solution Approach 1:
The valve train system is segmented into modular components: fixed profile cams provide base motion, while separate lost motion devices (variable length linkages) are inserted between the cam and valve to provide adjustable motion modification. This segmentation allows the system to maintain simplicity of fixed cams while adding adaptability through modular lost motion components that can be independently controlled.
Solution Approach 2:
The lost motion devices transform the static fixed profile cam system into a dynamic system where the effective cam profile can be changed in real-time. By controlling the lost motion devices to vary their length or engagement state, the system dynamically adjusts valve timing and lift characteristics without changing the physical cam geometry, enabling optimization for different operating conditions.
2Adaptability or versatility
If lost motion devices are incorporated into the valve train to adjust valve timing and lift, then adaptability is improved, but space requirements and manufacturing costs increase
Solution Approach 1:
The lost motion devices are designed to nest within existing valve train component spaces. The variable length linkages are positioned to utilize the available clearance between the cam, rocker arm, and valve assembly, effectively using otherwise wasted space. This nesting approach allows incorporation of adaptive functionality without significantly increasing the overall valve train footprint.
Solution Approach 2:
Instead of increasing the linear dimensions of valve train components, the lost motion devices utilize the vertical dimension and angular relationships in the valve train mechanism. By controlling the effective length and pivot points of the lost motion linkages, the system achieves adaptive valve timing and lift without requiring additional horizontal or lateral space in the engine compartment.
3Adaptability or versatility
If lost motion devices are incorporated into the valve train to adjust valve timing and lift, then adaptability is improved, but manufacturing costs increase
Solution Approach 1:
The motion adjustment functionality is extracted from the traditional cam design and placed into separate lost motion devices. This extraction allows the fixed profile cams to remain simple and inexpensive to manufacture, while the adaptive functionality is provided by independent lost motion components that can be produced using standard linkage and actuator manufacturing processes, potentially reducing overall system cost compared to complex variable geometry cams.
Solution Approach 2:
The lost motion devices are designed as universal components that can be applied to multiple valve positions and engine configurations. The same basic lost motion linkage design can control both intake and exhaust valves, and can be adapted to different cam profiles and valve train architectures, spreading manufacturing costs across multiple applications and reducing per-unit cost through economies of scale.
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 enables efficient and adaptable valve actuation systems that optimize performance by varying valve timing and lift, addressing space and cost constraints while maintaining robust operation.
Implementation Method 1
controlled between locked and unlocked states via hydraulic fluid
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.