Cylinder Valve Assembly Lost Motion Mechanism for Engine Durability
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Solution Overview
Problem
Existing cylinder deactivation systems in large displacement internal combustion engines face challenges with high valve seating velocities, leading to engine durability problems, especially when deactivating valve lift profiles during engine braking.
Innovation Solution
An auxiliary valve motion system that employs an intrinsic mechanical fail-safe cylinder deactivation method, where the disconnection of the outer plunger from the valve bridge is permitted only when the rocker arm is in a released condition, avoiding sudden and uncontrolled valve closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If hydraulic lash adjusting elements or lost motion assemblies are used to deactivate valve lifts, then fuel consumption is improved and thermal management is achieved, but valve seating velocity becomes excessively high causing engine durability problems
Solution Approach 1:
The cam profile includes a controlled return portion that gradually returns the valve to its closed position after deactivation, preventing sudden valve closure and excessive seating velocities. This preliminary controlled action ensures the valve closes smoothly rather than impacting its seat abruptly
Solution Approach 2:
The cam profile geometry is modified to include a controlled return portion with specific angular extent (e.g., 30-60 degrees), changing the temporal and spatial parameters of valve closure. This parameter change transforms the abrupt closure into a controlled, gradual return motion
2Power
If valve lift profiles are deactivated during engine braking without crank angle synchronization, then engine braking efficiency is improved, but valve seating velocity becomes extreme causing durability issues
Solution Approach 1:
The cam profile is designed with a controlled return portion that is predetermined during manufacturing, eliminating the need for real-time electronic synchronization. The geometry itself ensures that when deactivation occurs, the valve will naturally return to closed position through the controlled return portion rather than closing abruptly
Solution Approach 2:
The mechanical cam profile design inherently provides the controlled return function without requiring external control systems. The cam geometry automatically ensures safe valve closure behavior regardless of when deactivation is triggered, making the system self-regulating
3Reliability
If electronic synchronization systems are used to control lost motion assembly activation, then valve seating velocity is controlled, but device complexity and cost increase
Solution Approach 1:
The invention replaces electronic control systems with a purely mechanical solution embedded in the cam profile. The controlled return portion is a physical feature of the cam that passively ensures safe valve closure, eliminating sensors, actuators, and control electronics
Solution Approach 2:
The synchronization function is extracted from the control system and embedded directly into the cam profile geometry. Rather than using an external electronic system to synchronize valve closure, the cam profile itself contains the synchronization information in its physical shape
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
This solution effectively prevents high valve seating velocities and ensures engine durability by naturally synchronizing the lost motion activation within one revolution of the camshaft, eliminating the need for electronic synchronization.
Implementation Method 1
The outer plunger spring may bias the outer plunger upward in the central opening of the valve bridge. The inner plunger spring may bias the inner plunger upward in outer plunger bore.
Implementation Method 2
When hydraulic oil is pressurized through the rocker arm, the inner plunger is pushed downwards, therefore, its recess permits the one or more wedge lock pins or balls to decouple or unlock the outer plunger from the valve bridge body.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A system for operating a cylinder valve assembly for an internal combustion engine comprising a main event motion source configured to provide main event valve motions to the valve assembly, a main rocker arm operatively connected to the main event motion source, in such a way to assume an active condition at main event and a released condition, a lost motion assembly (LMA) operatively associated to the valve assembly (VB), wherein the lost motion assembly includes a locking element (LE), wherein the locking element is arranged to assume a locking condition with a first portion disposed in a corresponding seat (LES) of the valve assembly wherein the outer plunger includes a first duct (LD) to convey a hydraulic medium, arranged to pressurize the seat (LES) and wherein the lost motion assembly is realized such that sliding force exerted on the locking element by the corresponding seat pressurization exceeds frictions developed between the locking element and the corresponding seat only when the rocker arm is in released condition