System for reverse crankcase ventilation during boosted engine operation

Abstract

The invention relates to a system for reverse crankcase ventilation during boosted engine operation. Positive crankcase ventilation (PCV) systems have been employed on naturally-aspirated engines for over half a century. The gases in the crankcase exit the engine into the engine intake due to the slightly elevated pressure in the crankcase. Flow is controlled via a PCV valve in a PCV duct. In pressure-charged engines, PCV flow stops when pressure in the intake exceeds that of the crankcase. Such stagnation leads to sludging and deposit formation. According to an embodiment of the disclosure, reverse flow through the system is allowed by installing a second PCV valve in parallel with the normally-provided PCV valve, with the second PCV valve allowing an opposite direction of flow. Oil separators are provided on both PCV ducts to and from the engine to remove oil from blowby gases for flow in either direction.

Description

technical field [0001] The present disclosure relates to venting the engine crankcase during engine boost operation. Background technique [0002] Reciprocating internal combustion engines use piston rings so that the high-pressure combustion gases in the cylinders cannot easily leak into the crankcase. In a properly assembled piston-liner system, a small fraction of less than 1% of gas does leak out of the combustion chamber through the piston rings and ring gaps. These gases are combustion products of partial combustion and contain unburned fuel as well as reaction components of the partially burned fuel mixed with air. The first emission control measure applied to vehicle internal combustion engines in the 1960s was the positive crankcase ventilation (PCV) system, which is commonly used today. [0003] As shown in FIG. 1 , an engine system 100 with a PCV system is shown as a naturally aspirated engine 102 . The engine 102 has: a cylinder head 104 with a rocker cover (n...

AI Technical Summary

Problems solved by technology

Sludge is a problem in itself and causes varnish and deposits to form on engine components such as on the back of poppet valves, thereby reducing engine exhaust suction (performance) and acting as a thermal insulator for valves, causing them to overheat and / or or engine knock

In addition, the unburned fuel in the blow-by gas dilutes the oil, thereby impairing the lubricating properties of the oil

Blow-by gas containing oil enters the engine and can cause deposit problems in the engine and cause phosphorus in the oil additive to contaminate the catalyst, so reverse flow is not allowed

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