Valve timing control apparatus and internal combustion engine

Abstract

Valve timing control apparatus includes a driving rotary member driven by an engine; a driven rotary member arranged to rotate relative to the driving rotary member and adapted to rotate a camshaft of the engine; and a hydraulic control section to rotate the driven rotary member relative to the driving rotary member hydraulically. A lock mechanism is arranged to be brought, in accordance with a hydraulic pressure supplied from the hydraulic control section, from a lock state to prevent relative rotation of the driven rotary member relative to the driving rotary member, to an unlock state to allow the relative rotation, through an standby state to prepare for the unlock state without allowing the relative rotation of the driven rotary member relative to the driving rotary member.

1 . A valve timing control apparatus for an internal combustion engine, comprising: 
 a driving rotary member adapted to be driven by the engine;    a driven rotary member arranged to rotate relative to the driving rotary member and adapted to rotate a camshaft of the engine;    a hydraulic control section to rotate the driven rotary member relative to the driving rotary member hydraulically; and    a lock mechanism arranged to be brought, in accordance with a hydraulic pressure supplied from the hydraulic control section, from a lock state to prevent relative rotation of the driven rotary member relative to the driving rotary member, to an unlock state to allow the relative rotation of the driven rotary member relative to the driving rotary member, through an standby state to prepare for the unlock state without allowing the relative rotation of the driven rotary member relative to the driving rotary member.    
   
   
       2 . The valve timing control apparatus as claimed in  claim 1 , 
 wherein the driven rotary member is arranged to rotate relative to the driving rotary member in an advance direction when a fluid pressure is supplied to an advance pressure chamber, and in a retard direction when a fluid pressure is supplied to a retard pressure chamber;    wherein the hydraulic control section is configured to first supply the fluid pressure to a first chamber which is one of the advance and retard pressure chambers in an engine starting operation, and then to supply the fluid pressure to a second chamber which is the other of the advance and retard chambers; and    wherein the lock mechanism is arranged to shift from the lock state to the unlock state when the fluid pressure in the second chamber increases.    
   
   
       3 . The valve timing control apparatus as claimed in  claim 2 , wherein the lock mechanism is held in the lock state in the engine starting operation, and shifted to the standby state before the lock mechanism is shifted to the unlock state with an increase of the fluid pressure in the second chamber.  
   
   
       4 . The valve timing control apparatus as claimed in  claim 2 , wherein the lock mechanism is held in the lock state in the engine starting operation, and shifted to the standby state when an engine speed increases.  
   
   
       5 . The valve timing control apparatus as claimed in  claim 2 , wherein the lock mechanism is allowed to shift from the lock state to the standby state by an increase in an air pressure in one of the advance and retard chambers, but prevented from being shifted to the unlock state by the air pressure.  
   
   
       6 . The valve timing control apparatus as claimed in  claim 2 , wherein the lock mechanism is shifted from the lock state to the standby state in accordance with the fluid pressure in the first chamber.  
   
   
       7 . The valve timing control apparatus as claimed in  claim 2 , wherein the lock mechanism includes a movable lock member arranged to move forwards when the fluid pressure in the second chamber is low, and to move backwards when the fluid pressure in the second chamber is increased; and an abutting portion arranged to abut against the movable lock member when the movable lock member is moved forwards and thereby to prevent the relative rotation of the driven rotary member relative to the driving rotary member; and an abutment area in which the movable lock member abuts on the abutting portion to prevent the relative rotation between the driving and driven rotary members is reduced when the lock mechanism is brought from the lock state to the standby state, but the abutting area remains greater than zero in the standby state.  
   
   
       8 . The valve timing control apparatus as claimed in  claim 7 , wherein the lock mechanism further includes a bias member to bias the movable lock member forwards toward the abutting portion.  
   
   
       9 . The valve timing control apparatus as claimed in  claim 7 , wherein a length of the abutment of the movable lock member against the abutting portion, as measured along an imaginary line along which the movable lock member moves forwards and backwards is reduced when the lock mechanism is brought from the lock state to the standby state.  
   
   
       10 . The valve timing control apparatus as claimed in  claim 9 , wherein the movable lock member abuts against the abutting portion so that the abutting portion limits movement of the movable lock member in a direction substantially perpendicular to the imaginary line along which the movable lock member moves forwards and backwards.  
   
   
       11 . The valve timing control apparatus as claimed in  claim 9 , wherein the length of the abutment of the movable lock member against the abutting portion is equal to or smaller than 1 mm when the lock mechanism is in the standby state.  
   
   
       12 . The valve timing control apparatus as claimed in  claim 9 , wherein the length of the abutment of the movable lock member against the abutting portion is equal to or smaller than 0.2 mm when the lock mechanism is in the standby state.  
   
   
       13 . The valve timing control apparatus as claimed in  claim 7 , wherein the abutting portion is stationary relative to a first rotary member which is one of the driving and driven rotary members, and the movable lock member is mounted in a second rotary member which is the other of the driving and driven rotary members.  
   
   
       14 . The valve timing control apparatus as claimed in  claim 7 , wherein the abutting portion is a portion of a movable abutting member mounted movably in a first rotary member which is one of the driving and driven rotary members, and the movable lock member is mounted movably in a second rotary member which is the other of the driving and driven rotary members.  
   
   
       15 . The valve timing control apparatus as claimed in  claim 14 , wherein the movable abutting member is arranged to move forwards toward the movable lock member and backwards away from the movable lock member; the lock mechanism is in the lock state when the movable lock member is projected forwards and the movable abutting member is projected forwards; the lock mechanism is in the unlock state when the movable lock member is retracted backwards and the movable abutting member is retracted backwards; and the lock mechanism is in the standby state when the movable lock member is projected forwards and the movable abutting member is retracted backwards.  
   
   
       16 . The valve timing control apparatus as claimed in  claim 15 , wherein the lock mechanism further includes a second bias member to bias the movable abutting member forwards toward the movable lock member.  
   
   
       17 . The valve timing control apparatus as claimed in  claim 15 , wherein the movable lock member is held in the standby state even if the movable abutting member is moved backwards to a backward limit position to which a backward movement of the movable abutting member is limited.  
   
   
       18 . The valve timing control apparatus as claimed in  claim 15 , wherein the movable abutting member is moved backwards away from the movable lock member in accordance with the fluid pressure in the first chamber to which the fluid pressure is first supplied in the engine starting operation.  
   
   
       19 . The valve timing control apparatus as claimed in  claim 18 , wherein the movable abutting member includes a step shoulder surface arranged to receive the fluid pressure in the first chamber and thereby to be retracted backwards away from the movable lock member in accordance with the fluid pressure in the first chamber.  
   
   
       20 . The valve timing control apparatus as claimed in  claim 7 , wherein the abutting portion includes a lock recess arranged to receive a forward end portion of the movable lock member.  
   
   
       21 . The valve timing control apparatus as claimed in  claim 2 , wherein the driven rotary member includes a vane projecting radially outwards and separating the advance fluid pressure chamber and the retard fluid pressure chamber; and the driving rotary member enclosing the driven rotary member and defining the advance and retard fluid pressure chambers between the driving rotary member and the driven rotary member.  
   
   
       22 . The valve timing control apparatus as claimed in  claim 7 , wherein the movable lock member is arranged to move radially around an axis of the driven rotary member.  
   
   
       23 . The valve timing control apparatus as claimed in  claim 7 , wherein the movable lock member is arranged to move axially along an axis of the driven rotary member.  
   
   
       24 . The valve timing control apparatus as claimed in  claim 7 , wherein the lock mechanism includes a retracting section to guide the movable lock member and the abutting portion into the lock state by retracting at least one of the movable lock member and the abutting portion.  
   
   
       25 . The valve timing control apparatus as claimed in  claim 24 , wherein the retracting section includes a tapered surface formed in one of the movable lock member and the abutting portion.  
   
   
       26 . The valve timing control apparatus as claimed in  claim 2 , wherein the hydraulic control section includes a control valve to control the fluid pressures in the advance and retard pressure chambers; and a controller to control the control valve to first supply the fluid pressure to the first chamber which is one of the advance and retard pressure chambers at the time of a start of the engine, and then to supply the fluid pressure to the second chamber which is the other of the advance and retard chambers.  
   
   
       27 . An internal combustion engine comprising: 
 a crankshaft;    a camshaft;    a valve timing control rotary mechanism including, 
 a driving rotary member driven by the crankshaft of the engine, and  
 a driven rotary member) which is arranged to be driven by the driving rotary member and to drive the camshaft, and which is arranged to rotate relative to the driving rotary member to alter a rotational position of the driven rotary member relative to the driving rotary member;  
   a hydraulic section to rotate the driven rotary member relative to the driving rotary member in an advance direction by an advance fluid pressure in an advance pressure chamber and in a retard direction by a retard fluid pressure in a retard pressure chamber;    a control section to control the hydraulic section to supply a fluid pressure selectively to the advance pressure chamber or the retard pressure chamber in accordance with an engine operating condition, and to perform an engine starting operation by first supplying the fluid pressure to a first chamber which is one of the advance and retard pressure chambers, and then supplying the fluid pressure a second chamber which is the other of the advance and retard pressure chambers; and    a lock mechanism arranged to prevent relative rotation of the driven rotary member relative to the driving rotary member when the lock mechanism is in a lock state, and to allow the relative rotation of the driven rotary member when in an unlock state, the lock mechanism being set in the lock state at a time of an engine start and then brought to the unlock state in accordance with the fluid pressure in the second chamber after the engine start,    the lock mechanism being further arranged to be set, before the unlock state is reached, to a standby state preparing for the unlock state while preventing the relative rotation of the driven rotary member relative to the driving rotary member.