Engine Compression Braking Control for Vibration and Noise
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Solution Overview
Problem
Multi-cylinder reciprocating piston internal combustion engines experience abnormal vibration and noise during engine compression braking due to differences in cylinder-specific components, leading to undesirable levels that affect vehicle comfort and longevity.
Innovation Solution
An electronic control unit acquires operating data on in-cylinder pressure, engine rotation speed, noise, and vibration, and adjusts the intake air throttle to prevent or alleviate abnormal engine compression braking operations by generating intake actuator commands based on feedback-loop control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If engine compression braking is implemented using cylinder-specific components, then the engine can slow down the vehicle and reduce brake wear, but differences in manufacturing tolerances between cylinders lead to abnormal vibration and noise
Solution Approach 1:
The patent merges the control of all cylinders into a single global parameter (intake air throttle position) rather than controlling each cylinder independently. This combines the cylinder-specific components' effects into a unified control approach, eliminating the vibration and noise caused by inter-cylinder differences while maintaining compression braking functionality.
Solution Approach 2:
The intake air throttle is used for multiple purposes: normal engine operation and compression braking control. By making this single component serve both functions, the patent avoids the need for separate cylinder-specific control mechanisms, thereby eliminating the source of abnormal vibrations and noises.
2Power
If cylinder valves are opened to allow compressed gases out during compression braking, then piston acceleration is prevented, but abnormal vibration and noise occur due to cylinder-to-cylinder variations
Solution Approach 1:
Instead of controlling gas release in each cylinder separately, the patent merges all cylinder operations under a single global parameter (intake air throttle). This unified approach ensures synchronized operation across all cylinders, preventing the abnormal vibrations and noises that arise from inter-cylinder variations.
Solution Approach 2:
The patent changes the control parameter from individual cylinder valve timing to a global intake air throttle position. This parameter change allows control of the compression braking effect across all cylinders simultaneously, maintaining the necessary power effect while eliminating the harmful vibrations caused by parameter variations between cylinders.
3Speed
If exhaust gases are allowed into the cylinder during compression braking, then piston speed is reduced, but cylinder-specific component differences cause abnormal vibration and noise
Solution Approach 1:
The patent merges the control of exhaust gas intake across all cylinders into a single global parameter (intake air throttle). This ensures that all cylinders experience the same exhaust gas pressure conditions simultaneously, preventing the abnormal vibrations and noises caused by timing differences between cylinders.
Solution Approach 2:
By using a global intake air throttle to control exhaust gas pressure, the patent creates equipotential conditions across all cylinders. Each cylinder experiences the same exhaust gas pressure and timing, eliminating the potential differences that lead to abnormal vibrations and noises during compression braking.
Data Source
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AI summary
The invention relates to a method for controlling an engine compression braking mode of an engine arrangement (20), wherein the method comprises acquiring, during an engine compression braking mode, with one or more sensors (90), operating data representative of at least one engine operating parameter (ERS; ERA) in the list of: - in-cylinder pressure, and/or - engine rotation speed (ERS) and/or acceleration (ERA), and/or - noise and/or vibration generated by the engine arrangement (20) in the engine compression braking mode, and wherein, upon determination of an occurrence of an abnormal engine compression braking operation by the electronic control unit (100), the method comprises adjusting the degree of closing of the intake air throttle (50) by the intake actuator (52) according to the intake actuator setting commands. The invention also relates to an electronic control unit, a computer program, an engine arrangement and/or a heavy-duty vehicle embodying and/or implementing such method.