Piston Heating System for Compression Ratio Adjustment
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Solution Overview
Problem
Variations in cylinder compression ratios due to manufacturing tolerances and stack-up tolerances in engine components lead to reduced power and fuel efficiency, negatively affecting drivability and engine reliability, particularly in compression ignition engines.
Innovation Solution
A piston heating system that adjusts compression ratios by applying targeted heat to piston assemblies using heaters integrated into the lubrication system, allowing for efficient and reliable compression ratio adjustment, reducing noise, vibration, and harshness (NVH), and improving engine efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanical assembly is used to adjust compression ratio, then compression ratio adaptability is improved, but engine reliability deteriorates due to system complexity and potential malfunction
Solution Approach 1:
The patent replaces the mechanical assembly (Cannata system) with a thermal field-based piston heating system. Heaters are applied to the piston assemblies to thermally expand the pistons, thereby adjusting compression ratio without mechanical movement or complex linkages. This substitution of mechanical action with thermal expansion eliminates the reliability issues associated with mechanical components while maintaining compression ratio adaptability.
Solution Approach 2:
The patent changes the physical state (temperature) of the piston assemblies to achieve compression ratio adjustment. By controlling the temperature of pistons through heating elements, the thermal expansion coefficient of piston material is exploited to change piston dimensions and thus compression ratio. This parameter-based control avoids mechanical complexity while achieving the desired adaptability.
2Ease of manufacture
If manufacturing tolerances and stack-up tolerances are present in engine components, then ease of manufacture is improved, but compression ratio uniformity deteriorates leading to power variations
Solution Approach 1:
The patent implements a feedback control system where compression ratio is measured or estimated for each cylinder, and the piston heating system adjusts heating levels accordingly to compensate for variations caused by manufacturing tolerances. This closed-loop control ensures uniform compression ratios across all cylinders despite variations in component dimensions from normal manufacturing processes.
Solution Approach 2:
The patent applies localized heating to specific piston assemblies based on their individual compression ratio measurements. Each piston can be heated to a different extent to achieve uniform compression ratios across all cylinders, compensating for local variations in manufacturing tolerances and stack-up tolerances without requiring precision manufacturing throughout the entire engine.
3Ease of manufacture
If compression ratio variations exist between cylinders, then ease of manufacture is improved, but engine efficiency and drivability deteriorate due to power and fuel consumption variations
Solution Approach 1:
The patent uses thermal expansion of pistons through heating elements to adjust compression ratios, replacing mechanical adjustment mechanisms. This allows for precise, independent control of each cylinder's compression ratio to optimize engine efficiency and power output, eliminating the trade-off between manufacturing simplicity and performance uniformity.
Solution Approach 2:
The patent makes the compression ratio a dynamic parameter that can be adjusted in real-time based on operating conditions and measured compression ratios. The piston heating system can adapt compression ratios during engine operation to maintain optimal efficiency and power output across varying loads and temperatures, rather than being fixed at manufacturing.
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
The piston heating system stabilizes torque production across cylinders, increases engine efficiency, and enhances reliability and drivability by reducing compression ratio variance and NVH, while maintaining engine performance during low load and cold start conditions.
Implementation Method 1
activating a heater coupled to a lubrication line, the lubrication line including a nozzle directing lubricant to a first piston rod coupled to the first piston and a crankshaft during engine operation
Implementation Method 2
a piston assembly heater can be incorporated into a lubrication system to induce compression ratio adjustment
Implementation Method 3
a heater coupled to a lubrication line, the lubrication line including a nozzle directing lubricant to a first piston rod
Implementation Method 4
operating a piston heating system to apply a targeted amount of heat to a first piston assembly based on the variation between the compression ratios
Data Source
AI summary
Methods and systems are provided for actively heating pistons in combustion chambers to decrease a torque imbalance in an engine. In one example, a method for operation of an engine includes determining a variation between compression ratios in a first combustion chamber and a second combustion chamber and operating a piston heating system to apply a targeted amount of heat to a first piston assembly based on the variation between the compression ratios, the first piston assembly including a first piston positioned within the first combustion chamber.