Combined Engine Braking and EEVO Lost Motion Valve Actuation
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Solution Overview
Problem
Existing engine valve actuation systems for heavy-duty diesel engines face challenges in implementing engine braking and early exhaust valve opening (EEVO) efficiently, particularly in terms of adaptability, cost, and durability, with known solutions being complex and costly, and lacking ease of assembly and control over emission-related parameters.
Innovation Solution
A combined engine braking and EEVO lost motion system that includes a braking subsystem and an EEVO lost motion subsystem, utilizing a hydraulically-actuated lost motion element with a piston and check valve in the valve bridge, allowing for flexible control of exhaust valve motion and integration with a dedicated braking cam and rocker arm, enabling both engine braking and EEVO events with improved cost-effectiveness and adaptability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If variable valve actuation systems advance exhaust camshaft timing to open exhaust valves earlier, then exhaust temperatures increase for emissions control, but exhaust valve closing timing is modified adversely affecting residual exhaust gases in the cylinder
Solution Approach 1:
The system divides the valve actuation into separate independent components: a dedicated EEVO cam and rocker arm assembly for early exhaust valve opening, and a separate braking cam and rocker arm assembly for engine braking. This segmentation allows each function to be optimized independently - the EEVO assembly can advance exhaust valve opening timing to increase exhaust temperature for emissions control, while the braking assembly independently controls valve closing timing to manage residual exhaust gases, resolving the contradiction between these two functions.
2Adaptability or versatility
If known VVA systems use hydraulic valvetrain systems and high-speed solenoids to open exhaust valves anywhere in the engine cycle, then flexibility is achieved, but system complexity and cost increase
Solution Approach 1:
The patent extracts the EEVO function from complex hydraulic VVA systems and implements it using a simple mechanical lost motion element with a piston and check valve in the valve bridge. This lost motion mechanism provides the necessary timing flexibility through pure mechanical means, eliminating the need for high-speed solenoids and complex hydraulic control systems, thereby reducing both complexity and cost while maintaining adaptability.
Solution Approach 2:
The patent replaces expensive, complex hydraulic solenoid systems with a simple, inexpensive mechanical lost motion element consisting of a piston, check valve, and valve bridge components. This mechanical solution is cheaper, more durable, and easier to manufacture, while still providing the required flexibility in valve timing control.
3Adaptability or versatility
If lost motion devices are used to facilitate auxiliary valve actuation motions for engine braking and EEVO, then operational flexibility is achieved, but device complexity increases
Solution Approach 1:
The patent merges the EEVO lost motion mechanism with the existing valve bridge structure by integrating the piston and check valve directly into the valve bridge. This integration eliminates the need for separate, complex lost motion devices and combines multiple functions (EEVO actuation, engine braking, and standard valve operation) into a unified, simpler valve train assembly, thereby reducing overall device complexity while maintaining operational flexibility.
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 provides efficient and cost-effective implementation of engine braking and EEVO events, enhancing control over emissions and operating parameters like exhaust temperature, engine load, and torque, while being easier to manufacture and install, particularly in heavy-duty diesel engines.
Implementation Method 1
A lost motion element may include a piston slidably disposed in a bore in the valve bridge. The piston may be biased out of the bore and include an interior chamber open to the central bridge bore and an opening to permit the flow of pressurized hydraulic control fluid received from a swivel foot assembly.
Implementation Method 2
The bridge may include a check valve to prevent flow (and facilitate release) of control fluid.
Data Source
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AI summary
A combined dedicated braking and EE VO lost motion valve actuation systems for internal combustion engines provide subsystems for braking events and EE VO events on one or more cylinders. Various control strategies may utilize braking and EE VO capabilities to module one or more engine parameters, including after treatment temperature and engine load.