EGR Valve Control for Injection Valve Cooling in Engine Braking
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Solution Overview
Problem
High temperatures in the combustion chambers during engine braking operations can damage injection valves in internal combustion engines, and existing methods to cool them, such as fuel injection, may not be sufficient or cost-effective.
Innovation Solution
The EGR valve of the exhaust gas recirculation device is opened in a defined manner based on engine operating parameters like rotational speed and injection nozzle temperature to reduce critical temperatures at the injection valves, with the option to adjust opening degrees and timing for optimal braking performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fuel is injected to cool the injection valves during engine braking operation, then the temperature of the injection valves is reduced, but additional structural costs and complexity are incurred
Solution Approach 1:
The system uses the engine's own exhaust gas recirculation infrastructure to cool the injection valves, rather than introducing a separate cooling system. The EGR valve and existing exhaust gas flow serve the dual purpose of emissions control and thermal management of injection components.
Solution Approach 2:
The exhaust gas recirculation system performs multiple functions: it controls nitrogen oxide emissions during normal operation and serves as a cooling mechanism for injection valves during engine braking operation, eliminating the need for dedicated cooling infrastructure.
2Temperature
If the EGR valve is opened during engine braking operation, then the temperature at the injection valves is reduced, but the engine braking performance is slightly reduced
Solution Approach 1:
The EGR valve is opened to a controlled extent rather than fully, providing just enough exhaust gas flow to cool the injection valves while maintaining acceptable braking performance. The opening degree is optimized to achieve the minimum necessary cooling effect.
Solution Approach 2:
The EGR valve opening during engine braking is applied periodically or in controlled intervals rather than continuously, allowing the system to balance cooling requirements with braking performance needs based on real-time temperature conditions.
3Power
If the EGR valve is opened in dependence upon rotational speed, then the braking performance is optimized for different speed ranges, but the control complexity increases
Solution Approach 1:
The control system adjusts the EGR valve opening degree based on changes in rotational speed parameter, creating different operating characteristics for different speed ranges. This allows optimization of braking performance without requiring complex mechanical adjustments.
Solution Approach 2:
The control device uses rotational speed feedback to automatically adjust the EGR valve position, maintaining optimal braking performance across varying operating conditions without requiring manual intervention or complex mechanical linkages.
4Temperature
If the EGR valve is opened based on injection nozzle temperature, then the injection valves are protected from overheating, but the response time and control precision requirements increase
Solution Approach 1:
The system replaces complex mechanical temperature sensing and response mechanisms with electronic control based on measured temperature parameters, allowing for precise threshold-based control of the EGR valve opening.
Solution Approach 2:
The control system uses relatively simple temperature sensors and electronic control logic rather than expensive, high-precision measurement systems, achieving adequate protection by triggering EGR valve opening at predetermined temperature thresholds.
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 method effectively prevents overheating at the injection valves without additional structural costs, allowing for easy retrofitting of existing engines by modifying the control device software, while maintaining or reducing engine braking performance as needed.
Implementation Method 1
the EGR [exhaust gas recirculation] valve of the exhaust gas recirculation device is more or less opened in a defined and/or predetermined manner
Implementation Method 2
consequently the critical temperatures at the injection valves can be avoided
Implementation Method 3
it is possible without additional structural costs to counteract any overheating in particular of the injection valves
Data Source
AI summary
A method and a device for controlling the engine braking operation in internal combustion engines for motor vehicles, wherein the internal combustion engine is operated with direct injection of fuel and a controllable brake flap is provided in the exhaust gas system for retaining exhaust gases in the engine braking operation, and moreover has an exhaust gas recirculation device having an EGR valve that is arranged upstream of the brake flap and a recirculation line that connects the exhaust gas system to the intake system of the internal combustion engine and during the driving operation controls a defined quantity of recirculated exhaust gas with respect to the combustion air. To avoid critical excessive temperatures at the injection valves, in the engine braking operation (MB), the EGR valve (13) is more or less opened in dependence upon operating parameters (n, TE) of the internal combustion engine (1).