Engine boost control for multi-fuel engine
Patent No. US7802562 (titled "Engine boost control for multi-fuel engine") on Jul 31, 2008. The application was issued on Sep 28, 2010.
What is this patent about?
’562 is related to the field of fuel delivery systems for turbocharged or supercharged internal combustion engines. Specifically, it addresses the challenges of managing multiple fuel sources—such as gasoline and high-octane ethanol—to suppress engine knock while maintaining high performance under varying loads.
The underlying idea behind ’562 is to ensure that a direct-injection system always has liquid fuel available for charge cooling, even if the primary high-octane fuel supply is exhausted. By proactively transferring fuel from a secondary tank to the primary direct-injection tank, the system maintains a minimum fluid level that allows the engine to continue utilizing the thermal benefits of direct injection to mitigate knock, rather than reverting entirely to less efficient port injection.
The claims of ’562 focus on a control methodology that dynamically manages the fuel mix and engine pressure. It specifically covers the act of transferring a first fuel blend into a second fuel tank to prevent it from running dry, while simultaneously adjusting the intake air boost levels based on the specific latent heat of vaporization or alcohol concentration of the resulting fuel mixture in that second tank.
In practice, the invention functions as a fail-safe for high-performance tuning. When the high-alcohol fuel (which provides superior cooling) runs low, the system refills that tank with standard gasoline. While this dilutes the alcohol content, the control system compensates by calculating the new latent heat of vaporization and dialing back the turbocharger boost to a level that the new, lower-octane mixture can safely handle without causing engine damage.
This approach differs from prior solutions that simply reduced boost to a minimum baseline once the secondary fuel was gone. Instead of losing all charge-cooling benefits, this system leverages the fact that even standard gasoline provides significant knock resistance when delivered via direct injection rather than port injection. Consequently, the engine can maintain higher boost levels and better torque output than traditional dual-fuel systems by accounting for the specific chemical properties of the blended fuel.
How does this patent fit in bigger picture?
Technical Landscape
In the late 2000s when ’562 was filed, internal combustion engine management was typically implemented using dual-fuel systems that separated high-octane or high-volatility fuels from standard gasoline to manage engine knock under load. At a time when systems commonly relied on discrete fuel paths where one fuel source was dedicated to port injection and another to direct injection, hardware constraints made maintaining engine performance non-trivial once the secondary, knock-suppressing fuel was depleted. In these architectures, the exhaustion of a specific fuel type often necessitated a significant reduction in turbocharger or supercharger boost to protect the engine, as the system lacked a mechanism to dynamically redistribute available fuel stocks to maintain the charge-cooling benefits of direct injection.
Prosecution Position
The disclosed invention represents a technical advancement through an architectural shift in fuel management that enables continuous direct injection even after a primary knock-suppressing fuel is exhausted. By integrating a fuel transfer mechanism between separate tanks, the system prevents the direct injection reservoir from falling below a threshold level, ensuring that the charge-cooling effects of direct injection are maintained using a blended fuel supply. This configuration enables a technical capability where engine boost levels are dynamically adjusted based on the specific latent heat of vaporization or alcohol concentration of the resulting fuel blend. The advancement overcomes the constraint of binary performance degradation by allowing the engine to operate at higher boost levels than would be possible with port injection alone, effectively leveraging the mechanical cooling benefits of direct injection regardless of the specific fuel chemistry available.
Claims
This patent contains 30 claims, including four independent claims numbered 1, 6, 10, and 22. The independent claims focus on methods and systems for managing an internal combustion engine by transferring fuel between two storage tanks to maintain specific fuel levels or concentrations and adjusting intake air boost levels based on the alcohol content or latent heat of vaporization of the fuel delivered to the engine. The dependent claims serve to further define the system by specifying fuel types such as gasoline and ethanol, detailing the use of port and direct fuel injectors, describing sensor feedback mechanisms for monitoring fuel concentrations, and establishing specific control parameters for varying boost levels and fuel transfer thresholds based on engine operating conditions.
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US7802562
- Application Number
- US12184077A
- Filing Date
- Jul 31, 2008
- Publication Date
- Sep 28, 2010
- External Links
- Slate, USPTO , Google Patents