Lost Motion Valve Control for Compressive Force Transmission
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Solution Overview
Problem
Existing valve control systems in internal combustion engines face challenges in withstanding high forces during engine braking, particularly due to shear and torque components, which can lead to mechanical failure under harsh engine conditions.
Innovation Solution
A valve control system that applies purely compressive forces, using a valve lifter design with latch pins and a lost motion mechanism, which allows the system to operate robustly by transmitting compressive forces effectively, thereby overcoming the forces required to open the exhaust valve during engine braking without failing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional valve control system is used during engine braking, then the valve can be opened, but the system is prone to mechanical failure due to high shear and torque forces
Solution Approach 1:
The valve control system is divided into separate functional components: a cam mechanism for generating motion, a lost motion mechanism for absorbing excess movement, and a valve actuation system. This segmentation allows each component to handle specific forces independently, with the lost motion mechanism isolating shear and torque forces from the valve control elements, thereby improving reliability during engine braking.
Solution Approach 2:
The lost motion mechanism acts as an intermediary between the cam-driven linkage and the valve actuator. It absorbs and isolates the harmful shear and torque forces generated during engine braking, allowing the valve control system to operate under more favorable purely compressive loading conditions while still achieving the required valve opening motion.
2Strength
If purely compressive forces are applied in the valve control system, then durability is improved, but the mechanism complexity increases
Solution Approach 1:
The system employs a dynamic lost motion mechanism that automatically adjusts its state based on operating conditions. During normal operation, the mechanism engages to provide purely compressive force transmission. During engine braking events, the lost motion mechanism allows controlled relative movement to absorb shear and torque, then returns to its original position, providing adaptive force management without requiring a completely separate system for different operating modes.
Data Source
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AI summary
There is described a valve control device (113) for use in an internal combustion engine, the engine comprising an engine valve (101) and a camshaft having a cam profile (117) comprising a first lift profile. The valve control device comprises a first body (201) and a second body (203). The device is configurable in a first configuration and a second configuration. When the device is in the first configuration relative movement between said first body and second body caused when the first lift profile engages a cam engagement surface inhibits a valve actuating linkage from actuating the engine valve. The device further comprises means which when the device is in the second configuration prevents relative movement between said first and second bodies when the first lift profile engages the cam engagement surface to enable the valve actuating linkage to actuate the engine valve. When the device is in the second configuration, said means is arranged such that substantially all of the force exerted thereon as the valve is actuated is compressive.