Valve timing adjusting apparatus

Abstract

A valve timing adjusting apparatus for an internal combustion engine having a bearing includes a camshaft, a housing, a vane rotor, a control valve, and a fastening member. The fastening member is mounted on an axial end portion of the camshaft on a side of the vane rotor opposite from the bearing. The vane rotor is coaxially fastened to the camshaft between the fastening member and a step portion, which is provided to the camshaft on a side of the bearing. A sleeve of the control valve is coaxially received in an axial hole of the camshaft, which opens at an end surface of the end portion of the camshaft. Each of the advance output port and the retard output port is communicated with a corresponding one of the advance chamber and the retard chamber through the camshaft.

1 . A valve timing adjusting apparatus for an internal combustion engine having a bearing, wherein the valve timing adjusting apparatus adjusts valve timing of a valve based on torque transmitted from a crankshaft, the valve timing adjusting apparatus comprising:
 a camshaft that is supported by the bearing of the internal combustion engine, wherein:
 the camshaft opens and closes the valve based on the torque transmitted from the crankshaft; 
 the camshaft has an end portion that extends in an axial direction from the bearing; 
 the camshaft includes a step portion on a side of the bearing toward the end portion of the camshaft; and 
 the camshaft defines an axial hole therein that opens at an end surface of the end portion of the camshaft; 
   a housing that is rotatable synchronously with the crankshaft;   a vane rotor that is rotatable synchronously with the camshaft, which extends through the vane rotor, wherein:
 the vane rotor defines an advance chamber and a retard chamber in the housing; 
 the vane rotor is rotatable relative to the housing in an advance direction when working fluid is supplied to the advance chamber; and 
 the vane rotor is rotatable relative to the housing in a retard direction when working fluid is supplied to the retard chamber; 
   a control valve that is received in the axial hole of the camshaft and includes a spool and a sleeve, wherein:
 the spool is slidably received in the sleeve; 
 the sleeve is coaxially received in the axial hole and is stationarily provided; 
 the sleeve includes:
 an input port, through which working fluid flows into the sleeve; 
 an advance output port, through which working fluid flows into the advance chamber; and 
 a retard output port, through which working fluid flows into the retard chamber; and 
 
 the control valve displaces the spool to control communication between the input port and the advance output port and to control communication between the input port and the retard output port; and 
   a fastening member that is mounted on the end portion of the camshaft on a side of the vane rotor opposite from the bearing and the step portion, wherein:   the vane rotor is coaxially fastened to the camshaft in a state, where the vane rotor is held between the fastening member and the step portion;   working fluid flows into the input port through the camshaft; and   each of the advance output port and the retard output port is communicated with a corresponding one of the advance chamber and the retard chamber through the camshaft.   
   
   
       2 . The valve timing adjusting apparatus according to  claim 1 , wherein:
 the camshaft defines a camshaft passage therein that is communicated with the input port such that working fluid flows through the camshaft passage into the input port;   the camshaft further includes a plurality of passages therein; and   each of the advance output port and the retard output port is communicated with a corresponding one of the advance chamber and the retard chamber through a corresponding one of the plurality of passages of the camshaft.   
   
   
       3 . The valve timing adjusting apparatus according to  claim 1 , wherein:
 the vane rotor has an end surface that faces toward the bearing; and   the sleeve extends beyond the end surface of the vane rotor toward the bearing in the axial hole.   
   
   
       4 . The valve timing adjusting apparatus according to  claim 1 , wherein:
 the input port receives working fluid through the bearing and the camshaft.   
   
   
       5 . The valve timing adjusting apparatus according to  claim 4 , wherein:
 the bearing defines a bearing passage therein;   the camshaft defines a camshaft passage therein that is communicated with the input port; and   the input port receives working fluid through the bearing passage of the bearing and the camshaft passage of the camshaft.   
   
   
       6 . The valve timing adjusting apparatus according to  claim 1 , wherein:
 the vane rotor has an end surface that faces toward the bearing;   the sleeve includes:
 a first drain port that is communicated through the camshaft to a first space positioned on a side of the end surface of the vane rotor toward the bearing, the working fluid being discharged to the first space through the first drain port and the camshaft; and 
 a second drain port that is communicated through the camshaft to a second space positioned on a side of the end portion of the camshaft opposite from the bearing, the working fluid being discharged to the second space through the second drain port and the camshaft; 
   the control valve displaces the spool to control communication between the input port and each of the advance output port and the retard output port, and to control communication between (a) each of the advance output port and the retard output port and (b) a corresponding one of the first drain port and the second drain port;   the vane rotor is rotated relative to the housing in the advance direction when the followings are satisfied:
 working fluid is supplied to the advance chamber; and 
 working fluid is discharged from the retard chamber; and 
   the vane rotor is rotated relative to the housing in the retard direction when the followings are satisfied:
 working fluid is supplied to the retard chamber; and 
 working fluid is discharged from the advance chamber. 
   
   
   
       7 . The valve timing adjusting apparatus according to  claim 6 , wherein:
 the camshaft defines a first drain passage and a second drain passage therein;   working fluid is discharged to the first space through the first drain port and the first drain passage; and   working fluid is discharged to the second space through the second drain port and the second drain passage.   
   
   
       8 . The valve timing adjusting apparatus according to  claim 1 , wherein:
 the sleeve and the axial hole define therebetween a clearance in a radial direction.   
   
   
       9 . The valve timing adjusting apparatus according to  claim 8 , further comprising:
 an annular sealing member that is mounted on an outer peripheral surface of the sleeve such that the annular sealing member is slidable with the axial hole, wherein the annular sealing member seals between the input port, the advance output port, and the retard output port of the sleeve.   
   
   
       10 . The valve timing adjusting apparatus according to  claim 1 , further comprising:
 a check valve that is provided on a side of the bearing toward the spool, wherein:   the check valve allows working fluid to flow in a direction from the bearing toward the spool; and   the check valve limits working fluid from flowing in a direction from the spool toward the bearing.   
   
   
       11 . The valve timing adjusting apparatus according to  claim 10 , wherein:
 the spool defines therein an inner passage that is communicated with the input port; and   the check valve is provided inside the inner passage.   
   
   
       12 . The valve timing adjusting apparatus according to  claim 1 , wherein:
 the fastening member is a threaded member that defines an internal threaded hole therein; and   the internal threaded hole is threadably engaged with the end portion of the camshaft.