Phase varying apparatus for automobile engine

Abstract

PROBLEMS TO BE SOLVED To provide an oil film for permitting transmission of torque between a clutch case and a rotary drum. MEANS FOR SOLVING THE PROBLEMS A phase-varying apparatus for an automobile engine for varying the valve timing of intake and exhaust valves by moving an intermediate member ( 30 ) to cause a relative rotation between an outer cylinder ( 10 ) and an inner cylinder ( 20 ). The apparatus includes a circular rotary drum ( 44 ) connected to the intermediate member ( 30 ) and an electromagnetic clutch ( 42 ) for generating a braking force that acts on the rotary drum 44 . The electromagnetic clutch 42 has an annular clutch case ( 60 ) arranged to face the rotary drum ( 44 ) and an electromagnetic coil 62 for generating the braking force when energized. Grooves ( 66 ) and ( 67 ) are formed in the end face ( 63 a ) of the inner circumferential wall ( 63 ) and in the end face ( 64 a ) of the outer circumferential wall ( 64 ) of the clutch case ( 60 ) such that a torque is transmitted between the rotary drum ( 44 ) and the clutch case ( 60 ) via the oil film formed in and round the grooves ( 66 and 67 ). REPRESENTATIVE FIGURE FIG. 1

1 . A phase-varying apparatus for use with an automobile engine, including: an outer cylinder subjected to the rotational motion of the crankshaft of the engine; an inner cylinder connected to the camshaft for opening and closing the intake and exhaust valves of the engine and rotatable relative to the outer cylinder; and an intermediate member, disposed between the outer and inner cylinders, for transmitting the rotational motion of the outer cylinder to the inner cylinder, the intermediate member moveable in the axial direction thereof to cause a relative rotation of inner cylinder relative to the outer cylinder to thereby vary the valve timing of the intake and exhaust valves, the phase-varying apparatus characterized in that:
 the phase-varying apparatus comprises:
 an annular rotary drum coaxially disposed around the inner cylinder and connected to the intermediate member, and 
 an electromagnetic clutch for controlling the braking force to be exerted to the rotary drum in accord with the driving condition of the engine; 
   the electromagnetic clutch has
 an annular clutch case arranged to face the rotary drum, and 
 an electromagnetic coil for generating a braking force that acts on the rotary drum when energized so as to move the clutch case towards the rotary drum; and 
   a multiplicity of grooves are formed in at least one of the opposing faces of the rotary drum and the clutch case, for establishing engine oil passages to form an oil film in and around the grooves in such a way that the oil film transmits a torque between the rotary drum and the clutch case.   
     
     
         2 . The phase-varying apparatus according to  claim 1 , wherein:
 the annular clutch case has an outer and an inner circumferential wall together forming a C-shape transverse cross section and a circular groove between the outer and inner circumferential walls, the circular groove adapted to accommodate therein the electromagnetic coil and facing the rotary drum,   the grooves are formed in one end of the outer circumferential wall facing the rotary drum;   a gap is formed between the inner circumferential wall of the clutch case and the rotary drum; and   the rotary drum and the clutch case transmits torque to each other via the oil film formed in and around the grooves.