Lost Motion Variable Valve Actuation Dry Start Circuit
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Solution Overview
Problem
Existing VVA lost motion systems face challenges such as delayed full function after engine dry start, complex installation processes, excessive friction and wear in push tube interfaces, and inadequate control of valve closing velocity.
Innovation Solution
The proposed system includes a dry start hydraulic circuit for quick filling of lost motion VVA components, a modular and compact packaging design for easy installation, a stable master piston/push tube interface with enhanced lubrication and reduced side loading, and a self-adjusting valve catch (SAVC) to control valve closing velocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional VVA lost motion systems are used, then variable valve actuation functionality is achieved, but full function is delayed after engine dry start due to hydraulic fluid drainage
Solution Approach 1:
The patent implements a preliminary action by providing a dedicated hydraulic fluid reservoir that is pre-filled with hydraulic fluid before engine operation. This reservoir ensures that hydraulic fluid is immediately available to the VVA lost motion system upon engine restart, eliminating the delay that would otherwise occur while the system waits for fluid to drain back from other components during engine warm-up.
2Adaptability or versatility
If complex VVA lost motion systems are implemented, then advanced valve actuation control is achieved, but installation complexity and friction wear increase
Solution Approach 1:
The patent applies segmentation by dividing the VVA lost motion system into distinct functional modules: a hydraulic fluid reservoir, a master piston assembly, a slave piston assembly, and a valve train. This modular segmentation allows each component to be independently manufactured, assembled, and installed, reducing overall installation complexity while maintaining the advanced valve actuation control capabilities provided by the complete system.
3Ease of operation
If push tube interfaces are used in lost motion systems, then motion transfer is achieved, but excessive friction and wear occur
Solution Approach 1:
The patent introduces hydraulic fluid as an intermediary substance between the push tube and piston surfaces. This hydraulic fluid film acts as a lubricant that reduces direct metal-to-metal contact, thereby minimizing friction and wear at the push tube interfaces while still allowing effective motion transfer from the push tube to the piston assemblies.
4Adaptability or versatility
If valve closing velocity is not controlled, then lost motion functionality is maintained, but valve train damage risk increases
Solution Approach 1:
The patent implements a feedback mechanism through the hydraulic circuitry that monitors and responds to valve closing conditions. The hydraulic fluid pressure and flow characteristics provide feedback that automatically regulates valve closing velocity, preventing excessive speeds that could damage the valve train while maintaining the lost motion functionality needed for advanced valve actuation control.
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 system enables rapid attainment of full function after engine dry start, simplifies installation, reduces friction and wear, and effectively controls valve closing velocity, thereby improving the reliability and efficiency of VVA assemblies.
Implementation Method 1
a dry start hydraulic circuit cooperating with the master piston chamber for supplying working fluid to the master piston chamber during an engine start cycle
Implementation Method 2
systems for controlling the velocity of valve train components in lost motion systems, such as self-adjusting valve catches in master/slave piston components
Implementation Method 3
Lost motion is a term applied to a class of technical solutions in which the valve motion governed by a cam profile may be modified with a variable length mechanical, hydraulic or other linkage in the valve train
Data Source
AI summary
A compact, modular, lost motion variable valve actuation assembly includes a dry start hydraulic circuit to enable quick priming of a lost motion master-slave circuit from a dry start reservoir to the master piston chamber during engine start. Motion of the master piston on engine startup may draw in fluid from the dry start hydraulic circuit. The dry start components may be integrated into a compact modular rocker shaft pedestal package suitable for retrofit on existing engine head assemblies. The master piston may include a push tube interface that includes a deep push tube cavity and lubrication capabilities in the master piston that provides for improved wear, stability, easy installation and alignment. The slave piston may be provided with a valve catch to reduce valve closing velocity during cycles involving lost-motion.