Variable Valve Actuation and Exhaust Restriction for Engine Braking
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Solution Overview
Problem
Internal combustion engines with fixed cam profiles lack the ability to variably adjust intake and exhaust valve timing and lift, limiting their performance, fuel efficiency, and emission reduction capabilities, especially during engine braking and exhaust gas recirculation operations.
Innovation Solution
A system combining a variable valve actuation (VVA) system and an exhaust gas restriction device, controlled by an engine control module, which adjusts engine valve actuation and exhaust gas flow based on real-time engine operating parameters such as speed, load, and manifold pressure to optimize engine performance and braking power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed cam profiles are used for valve actuation, then the engine structure is simple and easy to manufacture, but the valve timing and lift cannot be adjusted, limiting engine performance and fuel efficiency
Solution Approach 1:
The patent applies variable valve actuation mechanisms that enable dynamic adjustment of valve timing and lift based on engine operating conditions. The system transitions from fixed cam profiles to dynamically adjustable valve actuation, allowing the engine to optimize performance across different operating modes including compression-release braking and exhaust gas recirculation.
Solution Approach 2:
The variable valve actuation system provides multi-functionality by enabling the same valve train to perform multiple functions: positive power generation, compression-release engine braking, bleeder engine braking, and exhaust gas recirculation. This universal system replaces the need for separate fixed cam profiles for different operating modes.
2Force
If exhaust valves are actuated for engine braking operation, then braking power is increased, but exhaust gas flow restriction is required which increases exhaust manifold pressure
Solution Approach 1:
The system dynamically adjusts exhaust valve timing and duration based on the desired braking power level. By precisely controlling when and how long exhaust valves remain open during compression-release braking, the system optimizes the balance between generating braking force and managing exhaust manifold pressure buildup.
Solution Approach 2:
The variable valve actuation system incorporates feedback control to monitor engine operating conditions and exhaust manifold pressure, adjusting valve actuation timing and duration to achieve target braking forces while preventing excessive pressure buildup in the exhaust system.
3Object-generated harmful factors
If exhaust gas recirculation is used to reduce NOx emissions, then combustion temperature is lowered, but valve actuation timing must be precisely controlled
Solution Approach 1:
The variable valve actuation system dynamically adjusts intake and exhaust valve timing to precisely control exhaust gas recirculation rates. By varying valve timing based on operating conditions, the system achieves optimal EGR levels for NOx reduction while maintaining combustion stability and power output.
4Productivity
If variable valve actuation system is implemented, then engine performance and fuel efficiency are improved, but the system complexity and cost increase
Solution Approach 1:
The variable valve actuation system is designed to provide multiple engine functions through a single integrated mechanism, including positive power, compression-release braking, bleeder braking, and exhaust gas recirculation. This multi-functional approach improves engine efficiency across all operating modes while limiting the increase in system complexity compared to having separate systems for each function.
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 enhances engine performance by varying valve timing and lift, reducing NOx emissions, and increasing braking power by controlling exhaust gas recirculation and back pressure, thereby improving fuel efficiency and vehicle control.
Implementation Method 1
an exhaust gas restriction device for restricting the flow of exhaust gas out of an exhaust manifold
Implementation Method 2
a variable valve actuation system for actuating an engine valve to control gas flow between a cylinder and an engine manifold
Implementation Method 3
determining one or more engine operating parameters selected from the group consisting of engine speed, engine load, exhaust manifold pressure, and vehicle speed
Data Source
AI summary
An internal combustion engine that includes both a variable valve actuation system and an exhaust restriction system to provide engine braking are disclosed. Variable valve actuation and exhaust gas restriction are carried out in response to one or more engine parameters such as engine speed, engine load, vehicle speed, and/or manifold temperature and pressure. Variable valve actuation and exhaust gas restriction may be controlled to provide selective engine performance during positive power operation and/or during engine braking operation.