Supercharger pressure ratio and temperature limiting scheme to protect hardware

A system, comprising:

• an engine having positive valve overlap in at least some boosted conditions;
• a supercharger coupled to the engine;
• a supercharger bypass having a vacuum actuated bypass valve;
• a throttle upstream of the supercharger;
• and
• a controller with instructions that when executed operate the engine with boosted intake pressure via the supercharger and with supercharger bypass operation limited by the vacuum actuated bypass valve being unable to be adjusted due to limited vacuum, and in response to an estimated supercharger outlet temperature being greater than a first threshold, increasing a blow through air passing from an engine intake to an engine exhaust without combustion in a cylinder of the engine due to engine intake and exhaust valves having positive valve overlap without limiting engine airflow via the throttle, and then, in response to the estimated supercharger outlet temperature being greater than a second, higher threshold, limiting engine airflow.

A system, comprising:

• an engine having positive valve overlap in at least some boosted conditions;
• a supercharger driven from a crankshaft of the engine;
• a supercharger bypass having a vacuum actuated bypass valve;
• a throttle upstream of the supercharger;
• a temperature sensor coupled upstream of the throttle;
• and
• a controller with instructions that when executed operate the engine with boosted intake pressure via the supercharger and with supercharger bypass operation limited by the vacuum actuated bypass valve being unable to be adjusted due to limited vacuum, and in response to an estimated supercharger outlet temperature being greater than a first threshold, increasing a blow through air passing from an engine intake to an engine exhaust without combustion in a cylinder of the engine due to engine intake and exhaust valves having positive valve overlap without limiting engine airflow via the throttle, and then, in response to the estimated supercharger outlet temperature being greater than a second, higher threshold, limiting engine airflow, the estimated supercharger outlet temperature determined based on the temperature sensor and operating conditions.