Hydraulic circuit for internal combustion engine

Abstract

In a hydraulic circuit including a second oil pump ( 21 ) as a dedicated pump for supplying oil pressure to a VVT ( 23, 24 ), the exhaust side VVT ( 24 ) has a rotor and a return spring for holding the rotor in a most advance angle state in stoppage of an engine. By obtaining driving force of the second oil pump ( 21 ) from an exhaust side camshaft ( 26 ) to which the rotor is connected, it is possible to reduce an increase in a torque required for operating the exhaust side VVT ( 24 ) through energizing force of the return spring.

1 . A hydraulic circuit for an internal combustion engine including a variable valve timing mechanism for varying a rotation phase of at least one of an intake side camshaft and an exhaust side camshaft with respect to a crankshaft of the internal combustion engine, thereby changing a valve timing of at least one of an intake valve and an exhaust valve which are to be opened/closed by the intake side camshaft and the exhaust side camshaft, the hydraulic circuit comprising:
 a first oil pump for supplying oil from an oil pan to a main gallery; and   a second oil pump for supplying the oil to the variable valve timing mechanism,   the variable valve timing mechanism including;   a rotor for being rotated in connection with at least one of the intake side camshaft and the exhaust side camshaft; and   a return spring for energizing to hold the rotor in a maximum phase angle state in stoppage of the internal combustion engine,   driving force of the second oil pump being obtained from the camshaft to which the rotor is connected.   
     
     
         2 . The hydraulic circuit for the internal combustion engine according to  claim 1 , wherein the rotor is connected to the exhaust side camshaft and the driving force of the second oil pump is obtained from the exhaust side camshaft.