Valve timing adjusting apparatus

Abstract

A valve timing adjusting apparatus includes a driving-side rotor, a driven-side rotor, and a directional control valve. The driven-side rotor is rotated in the advance direction when the advance and retard output ports communicate with the intake port and the retard drain port respectively, and the advance and retard output ports are disconnected from the advance drain port. The driven-side rotor is rotated in the retard direction when the advance and retard output ports communicate with the advance drain port and the intake port respectively, and the advance and retard output ports are disconnected from the retard drain port. A relay passage is provided at an exterior of the directional control valve for communication with the advance and retard drain ports. The drain relay passage closes the advance and retard drain ports relative to the exterior.

1 . A valve timing adjusting apparatus for adjusting valve timing of a valve that is opened and closed by a camshaft through torque transmission from a crankshaft of an internal combustion engine, the valve timing adjusting apparatus comprising:
 a driving-side rotor that is rotatable synchronously with the crankshaft;   a driven-side rotor that is rotatable synchronously with the camshaft, wherein:
 the driven-side rotor and the driving-side rotor define therebetween an advance chamber and a retard chamber arranged one after another in a rotational direction, and 
 when working fluid is supplied to the advance chamber or the retard chamber, the driven-side rotor is rotated relative to the driving-side rotor in an advance direction or a retard direction; 
   a control unit that controls supply of working fluid to the advance chamber and the retard chamber, wherein,   the control unit includes a directional control valve, an advance communication passage, an advance check valve, a retard communication passage, a retard check valve, and a drain relay passage;   the directional control valve includes:
 an intake port, through which the directional control valve receives working fluid from an external fluid input source; 
 an advance output port, through which the directional control valve outputs working fluid to the advance chamber; 
 a retard output port, through which the directional control valve outputs working fluid to the retard chamber; 
 an advance drain port, through which the directional control valve drains working fluid; and 
 a retard drain port, through which the directional control valve drains working fluid; 
   the driven-side rotor is rotated relative to the driving-side rotor in the advance direction when the followings are satisfied:
 the directional control valve provides communication between the advance output port and the intake port; 
 the directional control valve provides communication between the retard output port and the retard drain port; and 
 the directional control valve disconnects the advance output port and the retard output port from the advance drain port; 
   the driven-side rotor is rotated relative to the driving-side rotor in the retard direction when the followings are satisfied;
 the directional control valve provides communication between the advance output port and the advance drain port; 
 the directional control valve provides communication between the retard output port and the intake port; and 
 the directional control valve disconnects the advance output port and the retard output port from the retard drain port; 
   the advance communication passage is provided at an exterior of the directional control valve and is communicated with the advance drain port and the intake port;   the advance communication passage closes the advance drain port and the intake port relative to the exterior of the directional control valve;   the advance check valve is provided in the advance communication passage;   the advance check valve allows working fluid to flow from the advance drain port toward the intake port and limits working fluid from flowing from the intake port toward the advance drain port;   the retard communication passage is provided at the exterior of the directional control valve and is communicated with the retard drain port and the intake port,   the retard communication passage closes the retard drain port and the intake port relative to the exterior of the directional control valve,   the retard check valve is provided in the retard communication passage;   the retard check valve allows working fluid to flow from the retard drain port toward the intake port and limits working fluid from flowing from the intake port toward the retard drain port;   the drain relay passage is provided at the exterior of the directional control valve and is communicated with the advance drain port and the retard drain port; and   the drain relay passage closes the advance drain port and the retard drain port relative to the exterior of the directional control valve.   
   
   
       2 . The valve timing adjusting apparatus according to  claim 1 , wherein;
 the control unit further includes:
 an input communication passage that is provided at the exterior of the directional control valve, wherein the input communication passage provides communication between the fluid input source and the intake port and closes the fluid input source and the intake port relative to the exterior of the directional control valve; and 
 an input check valve that is provided in the input communication passage, wherein the input check valve allows working fluid to flow from the fluid input source toward the intake port and limits working fluid from flowing from the intake port toward the fluid input source; and 
   the advance communication passage and the retard communication passage are communicated with the intake port through a part of the input communication passage, the part being positioned between the input check valve and the directional control valve.   
   
   
       3 . The valve timing adjusting apparatus according to  claim 1 , wherein:
 the directional control valve further includes a spool and an actuator;   the spool is reciprocably displaceable between an advance position and a retard position;   when the spool is at the advance position, the followings are satisfied:
 the spool provides communication between the advance output port and the intake port; 
 the spool provides communication between the retard output port and the retard drain port; and 
 the spool disconnects the advance output port and the retard output port from the advance drain port; 
   when the spool is at the retard position, the followings are satisfied:
 the spool provides communication between the advance output port and the advance drain port; 
 the spool provides communication between the retard output port and the intake port; and 
 the spool disconnects the advance output port and the retard output port from the retard drain port; 
   the actuator displaces the spool to the advance position in order to rotate the driven-side rotor relative to the driving-side rotor in the advance direction; and   the actuator displaces the spool to the retard position in order to rotate the driven-side rotor relative to the driving-side rotor in the retard direction.