Cylinder head cavity ventilation for camless engine

Abstract

An engine assembly may include an engine structure, intake and exhaust valves, hydraulically actuated valve lift mechanisms, and a valvetrain ventilation line. The engine structure may define a combustion chamber, intake and exhaust ports in communication with the combustion chamber, a crankcase, and a valvetrain chamber isolated from the crankcase. The intake valve may be located in the intake port and the exhaust valve may be located in the exhaust port. The hydraulically actuated valve lift mechanisms may be supported on the engine structure within the valvetrain chamber and engaged with the intake and exhaust valves. The valvetrain ventilation line may be in communication with the valvetrain chamber and may provide communication between the valvetrain chamber and the intake port.

What is claimed is: 
     
         1 . An engine assembly comprising:
 an engine structure defining a combustion chamber, intake and exhaust ports in communication with the combustion chamber, a crankcase, and a valvetrain chamber isolated from the crankcase;   an intake valve located in the intake port;   an exhaust valve located in the exhaust port;   hydraulically actuated valve lift mechanisms supported on the engine structure within the valvetrain chamber and engaged with the intake and exhaust valves; and   a valvetrain ventilation line in communication with the valvetrain chamber and providing communication between the valvetrain chamber and the intake port.   
     
     
         2 . The engine assembly of  claim 1 , further comprising an intake manifold in communication with the intake port, the valvetrain ventilation line providing communication between the valvetrain chamber and the intake port through the intake manifold. 
     
     
         3 . The engine assembly of  claim 1 , further comprising a crankcase ventilation system in communication with the crankcase and the intake port. 
     
     
         4 . The engine assembly of  claim 3 , further comprising an intake manifold in communication with the intake port, the valvetrain ventilation line providing communication between the valvetrain chamber and the intake port through the intake manifold and the crankcase ventilation system providing communication between the crankcase and the intake port through the intake manifold. 
     
     
         5 . The engine assembly of  claim 1 , further comprising a fresh air line in communication with the valvetrain chamber and a fresh air source. 
     
     
         6 . The engine assembly of  claim 1 , wherein the engine structure includes a cylinder head and a valve cover fixed to the cylinder head to define the valvetrain chamber with the hydraulically actuated valve lift mechanisms supported on the cylinder head within the valvetrain chamber. 
     
     
         7 . The engine assembly of  claim 6 , wherein the valve cover defines a vent port coupled to the valvetrain ventilation line and providing communication between the valvetrain chamber and the intake port. 
     
     
         8 . The engine assembly of  claim 7 , wherein the valve cover defines an air inlet port in communication with a fresh air supply and providing communication between the valvetrain chamber and the fresh air supply. 
     
     
         9 . The engine assembly of  claim 7 , further comprising a fluid separation mechanism located at the vent port and adapted to separate hydraulic fluid from an air flow exiting the valvetrain chamber. 
     
     
         10 . The engine assembly of  claim 7 , further comprising a pressure regulator valve coupled to the valve cover and adapted open and vent the valvetrain chamber when a predetermined pressure is reached within the valvetrain chamber relative to atmospheric pressure. 
     
     
         11 . The engine assembly of  claim 7 , further comprising a crankcase ventilation system, the engine structure including an engine block coupled to the cylinder head and defining the crankcase with the crankcase ventilation system coupled to the engine block and in communication with the crankcase and the intake port. 
     
     
         12 . The engine assembly of  claim 1 , wherein the crankcase contains engine oil and the hydraulically actuated valve lift mechanisms are in communication with a pressurized hydraulic fluid that is different than the engine oil. 
     
     
         13 . An engine assembly comprising:
 an engine block defining a combustion chamber and a crankcase;   a cylinder head coupled to the engine block and defining intake and exhaust ports in communication with the combustion chamber;   a valve cover coupled to the cylinder head, the cylinder head and the valve cover defining a valvetrain chamber isolated from the crankcase;   an intake valve located in the intake port;   an exhaust valve located in the exhaust port;   hydraulically actuated valve lift mechanisms supported on the cylinder head within the valvetrain chamber and engaged with the intake and exhaust valves;   a crankcase ventilation system in communication with the crankcase and providing communication between the crankcase and the intake port; and   a valvetrain ventilation system in communication with the valvetrain chamber and providing communication between the valvetrain chamber and the intake port.   
     
     
         14 . The engine assembly of  claim 13 , wherein the crankcase and the valvetrain chamber are each in communication with a fresh air supply. 
     
     
         15 . The engine assembly of  claim 13 , further comprising an intake manifold coupled to the cylinder head and in communication with the intake port and a fresh air supply, the crankcase ventilation system and the valvetrain ventilation system with the crankcase ventilation system and the valvetrain ventilation system each being in communication with the intake port via the intake manifold. 
     
     
         16 . The engine assembly of  claim 13 , wherein the crankcase ventilation system is coupled to the engine block. 
     
     
         17 . The engine assembly of  claim 13 , wherein the valve cover defines a vent port providing communication between the valvetrain chamber and the intake port. 
     
     
         18 . The engine assembly of  claim 17 , wherein the valvetrain ventilation system includes a fluid separation mechanism located at the vent port and adapted to separate hydraulic fluid from an air flow exiting the valvetrain chamber. 
     
     
         19 . The engine assembly of  claim 17 , wherein the valvetrain ventilation system includes a pressure regulator valve coupled to the valve cover and adapted open and vent the valvetrain chamber when a predetermined pressure is reached within the valvetrain chamber relative to atmospheric pressure. 
     
     
         20 . The engine assembly of  claim 13 , wherein the crankcase contains engine oil and the hydraulically actuated valve lift mechanisms are in communication with a pressurized hydraulic fluid that is different than the engine oil.