Exhaust Brake Failure Detection and Sequential Activation Control
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Solution Overview
Problem
Combined exhaust and compression release engine braking systems experience high system loading on the valve train during transient events, leading to potential damage due to excessive peak forces applied to valve train components.
Innovation Solution
A controller in the internal combustion engine activates the exhaust braking subsystem and determines if parameters such as backpressure and boost pressure meet thresholds, activating the compression release braking subsystem only after a period allowing increased backpressure to develop, thereby minimizing high loads on the valve train, and optionally operating in a reduced braking power mode if failure is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If both compression release and exhaust engine brake subsystems are activated simultaneously, then substantial braking power is achieved, but excessively high loads are applied to the valve train components
Solution Approach 1:
The exhaust brake subsystem is activated first to establish increased backpressure in the exhaust system before the compression release brake subsystem is activated. This preliminary action creates a favorable pressure environment that reduces the transient peak forces on the valve train when both systems operate together.
Solution Approach 2:
The system uses sequential activation with a time delay between the two brake subsystems. The exhaust brake operates in an initial period to build backpressure, then the compression release brake is activated in a subsequent period, creating a periodic operational pattern that avoids simultaneous peak loading.
2Productivity
If the exhaust brake subsystem fails to restrict exhaust flow, then braking power is reduced, but continued operation without detection may cause further damage
Solution Approach 1:
A sensor monitors the actual exhaust backpressure and provides feedback to the controller. The controller compares the measured backpressure against expected values and activates the compression release brake only when the exhaust brake is confirmed to be functioning properly, ensuring reliable operation and preventing damage from undetected failures.
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 approach reduces the risk of damage to the valve train by minimizing the period of excessively high loads and allows for continued operation with reduced braking power if the exhaust braking subsystem fails, ensuring safer and more reliable engine braking.
Implementation Method 1
an exhaust brake uses exhaust back pressure within the engine to significantly increase braking power by restricting the flow of exhaust gases and increasing back pressure inside the engine
Implementation Method 2
a compression release type brake takes the load off the standard service brake by turning the internal combustion engine into a power-absorbing air compressor using a compression-release mechanism. When a compression release type brake is activated, the exhaust valves of one or more unfueled cylinders are opened near the top of the compression stroke. This releases the highly compressed air through the exhaust system
Data Source
AI summary
A controller of an internal combustion engine receives a request to activate an exhaust brake subsystem and, in response thereto, activates the exhaust braking subsystem. The controller thereafter determines that at least one parameter of the exhaust system, an intake subsystem or both compares unfavorably with at least one threshold. When the at least one parameter compares unfavorably with the at least one threshold, the controller determines that the exhaust braking subsystem has failed. In embodiments, the determination that the at least one parameter compares unfavorably with the at least one threshold comprises a determination that backpressure in the exhaust system is lower than a backpressure threshold and/or a determination that boost pressure in the intake subsystem is higher than a threshold.