Valvetrain Latch Assembly for Engine Braking and Torque Reduction
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Solution Overview
Problem
Existing combustion machinery designs face challenges in achieving fuel savings and energy efficiency due to packaging constraints and critical shifts in variable valve actuation systems, particularly in terms of actuator installations and starting torque.
Innovation Solution
A latch assembly integrated into the valvetrain, comprising a stationary housing with a plunger cavity and a controllable upper latch member, allows for selective locking and unlocking of the plunger, enabling decompression engine braking and other variable valve actuation techniques like early or late valve events, reducing starting torque and shutdown shake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If variable valve actuation is implemented to achieve fuel savings and energy efficiency, then energy efficiency is improved, but packaging constraints and actuator installation complexity increase
Solution Approach 1:
The latch assembly merges the valve retention function and the variable valve actuation function into a single integrated mechanism. The same latch assembly that holds the valve during operation also enables controlled valve opening/closing events, eliminating the need for separate actuators and reducing packaging complexity while maintaining energy efficiency benefits
Solution Approach 2:
The latch assembly serves multiple functions: it retains the valve during normal operation, enables controlled valve opening/closing events, and facilitates decompression engine braking. This multi-functionality reduces the overall system complexity and eliminates the need for additional dedicated actuators for each function
2Device complexity
If traditional valve actuation mechanisms are used, then packaging is simplified, but fuel savings and energy efficiency are reduced
Solution Approach 1:
The latch assembly combines multiple functions into one mechanism, allowing the system to achieve variable valve actuation benefits without requiring multiple separate actuators that would complicate packaging. The single latch assembly handles valve retention, controlled opening/closing, and decompression braking functions
3Use of energy by moving object
If decompression engine braking is implemented, then energy efficiency is improved, but starting torque increases
Solution Approach 1:
The latch assembly dynamically transitions between locked and unlocked states based on operational requirements. During normal operation, it remains locked to maintain valve closure; during decompression braking events, it unlocks to allow controlled valve opening. This dynamic behavior enables energy efficiency improvements through selective decompression events while the system can also remain in locked state during starting conditions to maintain necessary torque
Data Source
AI summary
A latch assembly and valvetrain therewith can comprise a stationary housing comprising a plunger cavity, a plunger in the plunger cavity, and a controllable upper latch member. The plunger can comprise a control end, a plunger body, a spigot body and a spigot end. The controllable upper latch member can be configured to selectively act on the control end and can be configured to switch between locking the plunger from moving along a first axis and unlocking the plunger to slide in the plunger cavity along the first axis. A slidable transverse latch member or rotatable upper castellation body can act as the controllable upper latch member. While a valve bridge and rocker arm can be movable, the housing for the latch assembly can be stationary.