Minimizing Alcohol Use In High Efficiency Alcohol Boosted Gasoline Engines

摘要

A number of systems and methods are disclosed which increase the replenishment interval for anti-knock fluid. This is especially important during activities which require a large amount of anti-knock fluid, such as towing. In some embodiments, the systems and methods are used to reduce anti-knock fluid consumption. For example, changes to engine operation, such as rich operation, spark retarding, upspeeding, and variable valve timing, all serve to reduce the amount of anti-knock fluid required to eliminate knocking. In other embodiments, the composition of the anti-knock fluid is modified, such as by using a higher octane fluid, or through the addition of water to the anti-knock fluid. In other embodiments, the replenishment interval is increased through a larger anti-knock fluid storage capacity. In one embodiment, a three tank system is used where the third tank can be used to store gasoline or anti-knock fluid, depending on the driving conditions.

主权项

1. A spark ignition engine system, where a first fluid is introduced into said engine from a first source and a second fluid is introduced into said engine from a second source and wherein the ratio of said second fluid to said first fluid varies with engine torque so as to prevent knock, comprising: a controller configured to modify the operation of said engine so as to reduce an amount of said second fluid that would otherwise be used over a prolonged period of time, based on a change in vehicle operating condition wherein said change comprises operation at a higher average value of torque over said prolonged period of time.