Method and apparatus for minimum knock operation of an internal combustion engine on low knock-rated fuel

The method of optimizing the addition of a knock suppressing fluid to a normally, low knock-rated fuel for operating an internal combustion engine with minimum knock which comprises:

• continuously measuring load conditions on said engine over a range of loads normally causing an engine to knock,
• detecting a knock condition in said engine, and
• responsive to the simultaneous presence of knock and an engine load condition within said range injecting an anti-knock fluid into the intake system of said engine in an amount and to an extent dependent upon said engine load condition and only sufficient to suppress said knock below a predetermined level of said detected knock condition.

The method of controlling the periodic addition of small but effective amounts of a knock suppressing fluid to the fuel intake system of an internal combustion engine being operated on a primary fuel having a low knock rating which comprises:

• determining a condition representative of the operating load on said engine to anticipate potential knock thereof when operated on said primary fuel, simultaneously detecting any actual knock condition induced by said operating load, and responsive to the presence of both of said conditions injecting an amount of knock suppressing fluid into said fuel intake system of said engine, said knock suppressing fluid being injected at a rate and in an amount dependent upon said operating load and sufficient only to suppress knock of said engine under said load condition.

The method of operating an internal combustion engine on a low knock-rated fuel with suppressed knock under high knock inducing conditions which comprises:

• continuously measuring load conditions on said engine over at least the range of loads that would normally cause an engine to knock,
• detecting the occurrence of any knock condition of predetermined magnitude in said engine, and
• responsive to the simultaneous presence of said knock condition and said measured engine load condition being within said load range injecting an anti-knock fluid with the low knock-rated fuel and air mixture supplied to said engine, the amount and the extent of such injection being determined by said detected load condition and being sufficient only to suppress said knock condition.