Internal-combustion engines – Charge forming device – Crankcase vapor used with combustible mixture
Reexamination Certificate
2000-06-12
2001-05-22
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Charge forming device
Crankcase vapor used with combustible mixture
Reexamination Certificate
active
06234154
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a positive crankcase ventilation system for an internal combustion engine.
BACKGROUND OF THE INVENTION
During engine operation, combustion gas may leak between the cylinder and its piston rings into the engine crankcase. The leaked combustion gas is referred to as blowby gas and may comprise unburned intake air/fuel mixture, exhaust gas, oil mist, and water vapor.
A positive crankcase ventilation (PCV) system is typically employed to ventilate the crankcase and recirculate the blowby gas to the intake side of the engine for burning the gas in the combustion chamber. The PCV system takes advantage of the negative pressure in the intake to draw the gas out of the crankcase and may utilize a PCV valve to regulate the flow.
A PCV system may be incorporated as a foul air/oil separator in the cam cover of the engine. In the case where design package restraints make it unworkable to package an adequate separator within the cover, the separator may be attached externally to the cover or engine block. An external hose routes the blowby gas to the intake.
In cold environments, a common concern is freezing of the water vapor component of the blowby gas in an external PCV hose and valve. To minimize the risk of freezing, some PCV systems may include a PCV heater, or an extra hot water-carrying hose routed adjacent the PCV hose, or electrically heating or insulating the PCV hose, but these come at a significant cost.
The need exists for a PCV system which is protected from the risk of freezing without adding substantial cost or complexity to the engine.
SUMMARY OF THE INVENTION
The present invention incorporates a PCV system within the engine block and cylinder head castings to minimize the risk of freezing the PCV system.
A foul air/oil separator is cast integral with the engine block, with chambers to allow oil to separate and drain to the crankcase, while not allowing the foul air to bypass portions of the chambers through the oil drain holes. The chambers are positioned adjacent to water jacket passages used to carry engine-warmed coolant away from the engine to maintain the PCV chambers, and therefore the gas therein, above freezing.
As the blowby gas exits the final chamber of the air/oil separator, it may pass through an orifice in the cylinder head gasket to control the flow rate of the gas, without the need for a PCV valve. A passage within the cylinder head delivers the blowby gas to a short hose to the intake manifold, which transports the gas to the intake side of the engine.
This integral PCV system eliminates the expensive need for PCV-specific gas heaters or insulation of PCV hoses to minimize the risk of freezing.
REFERENCES:
patent: 4958613 (1990-09-01), Hiraoki et al.
patent: 5499604 (1996-03-01), Ito et al.
patent: 6044828 (2000-04-01), Matsushita
patent: 6065458 (2000-05-01), Ozeki
General Motors Corporation
Hargitt Laura C.
McMahon Marguerite
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