Variable cam phaser for automobile engine

Abstract

The invention provides a variable cam phaser for an automobile engine, equipped with a self-locking mechanism which is simpler in structure, cost effective, and easy to manufacture. The self-locking mechanism includes: a eccentric circular members ( 12 ) integral with the camshaft ( 6 ) and a support groove ( 15 ) for supporting the eccentric circular members from the both sides thereof at positions offset from the camshaft axis towards the eccentric cam center; a lock plate integrally held with the control rotor by means of a coupling mechanism; and a cylindrical portion belonging to the drive rotor in which the lock plate is inscribed. The self-locking mechanism prevents an unexpected change in the phase angle caused by an external disturbing toque transmitted to the camshaft via the crankshaft of the engine.

1 . A variable cam phaser for an automobile engine including:
 a drive rotor driven by the crankshaft of the engine;   a control rotor;   a camshaft coaxial with the drive rotor and adapted to rotatably support the drive rotor;   a torque means for providing the control rotor with a torque for rotating the control rotor relative to the drive rotor;   a phase angle varying mechanism for varying the relative phase angle between the drive rotor and the control rotor in accord with the relative rotation of the control rotor relative to the drive rotor;   and a self-locking mechanism mounted in the phase varying mechanism for preventing a phase change from occurring between the drive rotor and the camshaft caused by an unexpected cam torque appearing on the camshaft, the variable cam phaser characterized in that the self-locking mechanism comprises:
 an eccentric circular cam integral with the camshaft; and 
   a lock plate having
 a support groove for supporting, at positions further offset from the camshaft axis in the direction (referred to as eccentric direction) from the camshaft axis towards the cam center of the eccentric circular cam, the periphery of the eccentric circular cam from both sides thereof, 
 a coupling mechanism for transmitting the relative rotational torque from the control rotor to the eccentric circular cam, and 
   a cylindrical body formed integral with the drive rotor and circumscribing the periphery of the lock plate.   
     
     
         2 . The variable cam phaser according to  claim 1 , wherein
 the support groove extends in a radial direction of the lock plate;   the eccentric circular cam is provided on the outer periphery thereof with a lock plate bush; and   the lock plate bush has on the opposite sides of the outer periphery thereof a pair of flat faces spaced apart across the line of eccentric direction and supported by the support groove.   
     
     
         3 . The variable cam phaser according to  claim 2 , wherein the lock plate is divided into two parts by a pair of slits each extending from the support groove to the periphery of the lock plate. 
     
     
         4 . The variable cam phaser according to  claim 3 , wherein one of the two slits may be provided with urging means for providing a force to widen that slit. 
     
     
         5 . The variable cam phaser according to  claim 2 , wherein
 the lock plate is provided with two slits extending from the support groove to the periphery of the lock plate; and   the radius of curvatures of the lock plate on the opposite sides thereof across the line of eccentric direction are slightly larger than the inner radius of the cylinder circumscribing the lock-plate.   
     
     
         6 . The variable cam phaser according to  claim 4 , wherein the lock plate bush is divided into two parts by a pair of slits. 
     
     
         7 . The variable cam phaser according to  claim 3 , wherein
 the flat faces of the lock plate bush are a pair of stepped faces projecting to the right and left to the line of eccentric direction; and   the stepped faces are offset in the eccentric direction away from the cam center towards the eccentric axis of the cam center.   
     
     
         8 . The variable cam phaser according to  claim 3 , wherein
 the coupling mechanism consists of coupling members each engaging with one of paired coupling holes formed in the control rotor and with one of paired coupling holes formed in the rock plate; and   a minute clearance is provided between each coupling member and an associated coupling hole of either the control rotor or the lock plate.   
     
     
         9 . The variable cam phaser according to  claim 5 , wherein the lock plate bush is divided into two parts by a pair of slits. 
     
     
         10 . The variable cam phaser according to  claim 4 , wherein
 the flat faces of the lock plate bush are a pair of stepped faces projecting to the right and left to the line of eccentric direction; and the stepped faces are offset in the eccentric direction away from the cam center towards the eccentric axis of the cam center.   
     
     
         11 . The variable cam phaser according to  claim 5 , wherein
 the flat faces of the lock plate bush are a pair of stepped faces projecting to the right and left to the line of eccentric direction; and the stepped faces are offset in the eccentric direction away from the cam center towards the eccentric axis of the cam center.   
     
     
         12 . The variable cam phaser according to  claim 6 , wherein
 the flat faces of the lock plate bush are a pair of stepped faces projecting to the right and left to the line of eccentric direction; and the stepped faces are offset in the eccentric direction away from the cam center towards the eccentric axis of the cam center.   
     
     
         13 . The variable cam phaser according to  claim 4 , wherein
 the coupling mechanism consists of coupling members each engaging with one of paired coupling holes formed in the control rotor and with one of paired coupling holes formed in the rock plate; and   a minute clearance is provided between each coupling member and an associated coupling hole of either the control rotor or the lock plate.   
     
     
         14 . The variable cam phaser according to  claim 5 , wherein
 the coupling mechanism consists of coupling members each engaging with one of paired coupling holes formed in the control rotor and with one of paired coupling holes formed in the rock plate; and   a minute clearance is provided between each coupling member and an associated coupling hole of either the control rotor or the lock plate.   
     
     
         15 . The variable cam phaser according to  claim 6 , wherein
 the coupling mechanism consists of coupling members each engaging with one of paired coupling holes formed in the control rotor and with one of paired coupling holes formed in the rock plate; and   a minute clearance is provided between each coupling member and an associated coupling hole of either the control rotor or the lock plate.   
     
     
         16 . The variable cam phaser according to  claim 7 , wherein
 the coupling mechanism consists of coupling members each engaging with one of paired coupling holes formed in the control rotor and with one of paired coupling holes formed in the rock plate; and   a minute clearance is provided between each coupling member and an associated coupling hole of either the control rotor or the lock plate.