Many internal combustion engines include turbochargers, or superchargers configured to force more air mass into an engine's intake manifold and combustion chamber by compressing intake air with a compressor driven by a turbine disposed to capture energy from the flow of the engine exhaust gas. However, the compression of the intake air tends to heat it which tends to reduce the density of this charge air. It is known to use a charge air cooler to compensate for heating caused by supercharging. Charge air coolers may be used with gasoline engines and with diesel engines.
Smaller displacement turbo charged engines may be used in bigger vehicles to improve fuel economy. The hot compressed air from a compressor becomes cooler in a charge air cooler (CAC) to minimize spark retard. With hot humid air moisture may condense out in a charge air cooler if it is cooled below the dew point. It has been measured that on a humid day some engines can condense enough water to form a puddle in the bottom of the charge air cooler outlet tank while cruising at 70 mph for 60 min. One measurement showed a rate of puddle accumulation of 120 cc/60 min. In addition, if a driver goes into wide open pedal for, only 1 to 2 seconds, and then backs off the accelerator, a puddle in the end tank may form or grow rapidly. The engine can misfire if a big puddle is ingested at once during hard acceleration. For example, misfire has been shown to occur for water ingestion rates of greater than 20 cc/sec. This is not acceptable because the engine will not provide the power demanded. In addition, if the fuel injectors of the misfiring cylinders continue to inject fuel, the catalytic converter brick substrate can melt down from excessive heat.
Embodiments in accordance with the present disclosure may be used to prevent water condensation, and also to prevent water ingestion at rates high enough to cause misfire.
Embodiments may provide a drain tube at a location in the charge air cooler outlet tank where condensation may have a tendency to collect, and where the water condensate may puddle up. Embodiments may arrange an expansion chamber in line with the drain tube to collect the water. The expansion chamber may act as a water agitator to slow down the puddle ingestion into the engine through the drain tube. In addition, a valve may be disposed at an inlet to provide an agitating jet of the intake air to the water in the chamber. In this way, the valve may aid in atomizing the water into the intake air stream before it is passed through the intake manifold and into the combustion chamber. In this way, the condensate from the charge air cooler will be directed to the intact manifold of the engine in a controlled and measured way. In this way the engine will then be much less likely to misfire due to water ingestion.
Embodiments may provide a misfire prevention water agitator system and method. The system may include a boosted engine having a charge air cooler downstream of the compressor and having an air intake passage with a throttle between an intake manifold and the charge air cooler. The system may also include a line coupled in parallel with the air intake passage between the intake manifold and the charge air cooler, the line coupled to the intake manifold downstream of the throttle, the line including an agitator mounted within 45 degrees of vertical.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.