Engine Torque Regulation via Exhaust Pressure Limits
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Solution Overview
Problem
Existing engine brake systems in heavy vehicles face issues with excessively high exhaust gas pressures during engine brake application, leading to potential engine and component damage, and delayed driver torque responsiveness due to delayed torque request to manage pressure peaks.
Innovation Solution
A method and system for regulating the actual output variables of an internal combustion engine by generating a maximum reference value based on exhaust system physical variables, such as exhaust gas pressure and turbocharger rotational speed, to limit torque and fuel injection, ensuring component protection and preventing excessive exhaust gas streams, allowing simultaneous operation of the engine brake and accelerator pedal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the driver's torque request is delayed to avoid rapid rise of exhaust gas pressure, then exhaust gas pressure peaks are reduced, but the responsiveness of the internal combustion engine is adversely affected
Solution Approach 1:
The control system performs preliminary action by proactively limiting the reference variable (torque request) based on predicted exhaust gas pressure conditions. Instead of waiting for pressure peaks to occur and then delaying response, the system calculates safe torque limits in advance using a characteristics map that correlates engine operating parameters with maximum permissible torque values, thereby preventing excessive pressure buildup while maintaining responsive driver input handling.
Solution Approach 2:
The system implements feedback by continuously monitoring actual engine operating parameters (rotational speed, torque, fuel injection quantity) and using this information to dynamically adjust the maximum permissible reference variable through the characteristics map. This closed-loop feedback mechanism ensures that torque limitations are adaptively applied based on real-time engine state, preventing exhaust gas pressure peaks while preserving engine responsiveness within safe operating boundaries.
2Reliability
If the torque request is limited to prevent excessive exhaust gas pressure, then component protection is improved, but driving comfort deteriorates due to deviation from requested torque
Solution Approach 1:
The system applies parameter changes by dynamically adjusting the reference variable (torque request) based on engine operating conditions. The characteristics map defines maximum permissible torque values as a function of actual engine parameters (rotational speed, fuel injection quantity), allowing the system to modify torque delivery smoothly and adaptively. This ensures component protection through torque limitation while minimizing disruption to driver intent by maintaining torque within safe but still effective ranges.
3Power
If a throttle valve or variable turbine geometry is used to increase exhaust gas backpressure for engine brake function, then engine braking capability is improved, but risk of exhaust system damage increases due to excessively high pressure peaks
Solution Approach 1:
The control system performs preliminary action by establishing maximum permissible torque limits before engine brake activation or during brake application. The characteristics map pre-defines safe operating boundaries that prevent torque requests which would cause excessive exhaust gas pressure buildup. This proactive limitation prevents damage to throttle valves, seals, and turbocharger components while maintaining engine braking capability through controlled backpressure increase.
Data Source
AI summary
A method for regulating an actual output variable of an internal combustion engine to a reference variable. A maximum value for the reference variable is generated as a function of at least one physical variable in the exhaust system of the internal combustion engine and the reference variable is limited to this maximum value.