Compressor Outlet Temperature Control for Turbocharger Coking Prevention
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Solution Overview
Problem
The maximum permitted compressor outlet temperature in boosted diesel engines is often a limiting factor due to compressor coking, restricting boost pressure and power delivery, especially since fixed temperature limits are unnecessary for most passenger car users operating conditions.
Innovation Solution
A method to vary the maximum permitted compressor outlet temperature based on a function of compressor outlet temperature and operating time, allowing the compressor to operate at higher temperatures initially to maximize efficiency and boost pressure, while reducing the temperature when the compressor ages to prevent coking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed maximum compressor outlet temperature limit is applied to prevent coking, then compressor reliability is improved, but engine power and efficiency are restricted
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed temperature limit to a dynamic temperature limit that varies with compressor operating time. The control system continuously adjusts the maximum permitted compressor outlet temperature based on how long the compressor has been operating, allowing higher temperatures during early operation when coking risk is lower, and progressively reducing the limit as operating time increases. This dynamic adjustment resolves the contradiction by enabling higher power output during periods when the compressor is less susceptible to coking, while maintaining reliability over the long term.
Solution Approach 2:
The patent implements parameter changes by modifying the temperature limit parameter based on compressor operating time. Instead of maintaining a constant temperature threshold, the system changes the permissible temperature parameter dynamically - allowing higher temperatures initially and progressively lowering the threshold as the compressor accumulates operating hours. This parameter adaptation enables the system to optimize between power output and reliability by adjusting the temperature parameter according to the compressor's age and coking susceptibility.
2Productivity
If the compressor operates at higher temperatures to maximize boost pressure, then engine efficiency is improved, but coking occurs reducing compressor performance
Solution Approach 1:
The patent applies preliminary action by proactively managing the temperature limit based on predicted coking risk associated with compressor age. Rather than waiting for coking to occur and then reducing temperatures, the system预先 (in advance) adjusts the maximum permitted temperature according to operating time, preventing coking before it significantly impacts performance. This allows the compressor to operate at higher temperatures during early life when it can tolerate them, maximizing efficiency while preventing the harmful effects of coking.
Solution Approach 2:
The patent implements skipping by allowing the compressor to rapidly operate at higher temperatures during early operation phases when coking is not yet a concern, effectively 'skipping' over the period where high temperatures would be harmful. The system rushes through the early operational phase with elevated temperature permits, extracting maximum efficiency during the period when the compressor is most capable of handling high temperatures, before transitioning to more conservative limits.
3Duration of action of stationary object
If a lower maximum compressor outlet temperature is maintained to prevent coking, then compressor durability is improved, but boost pressure and power delivery are restricted
Solution Approach 1:
The patent applies dynamics by implementing a time-varying temperature limit that evolves with compressor operating time. The system dynamically transitions from higher permitted temperatures during early operation to lower temperatures as the compressor ages, optimizing the balance between durability and power delivery at different stages of the compressor's life cycle. This dynamic approach allows the system to extract maximum power during periods when the compressor can tolerate higher temperatures while progressively prioritizing durability.
Solution Approach 2:
The patent implements parameter changes by adjusting the maximum temperature parameter as a function of operating time. The control system modifies the temperature threshold parameter based on how long the compressor has been in service, allowing higher temperatures when durability is less concerned and lowering the parameter as accumulated operating time increases. This parameter adaptation enables the system to optimize power delivery during early operation while progressively enhancing durability protection.
Data Source
AI summary
A method for controlling a compressor of a turbocharger is disclosed. In one example, the method comprises varying a maximum permitted compressor outlet temperature based upon a function of compressor outlet temperature and operating time, and controlling the operation of the compressor so that the maximum permitted compressor outlet temperature is not exceeded. In this way a higher boost pressure can safely be used during the early life of the compressor but excessive coking of the compressor with a resultant loss of efficiency later in the life of the compressor is reduced.