Device for actuating a valve of an internal combustion engine

Abstract

The invention relates to a cam actuator ( 2 ) for actuating at least one valve ( 3 ) slidably mounted in a mounting ( 1 ), the device comprising a tappet ( 8 ) which is to be mounted on a free end of a stem ( 3 a ) of the valve and which is mobile relative to the mounting ( 1 ); and a resilient return means ( 9 ) for the tappet, which to urge the tappet ( 8 ) against the cam ( 2 ), characterised in that the device comprises an electromagnetic locking means including an electromagnetic actuator ( 22 ) having a coil ( 24 ), preferably outside the tappet ( 8 ), and at least one pin ( 12 ) subjected to the magnetic field of the actuator ( 22 ), such that supplying power to the coil ( 24 ) causes the selective movement of the pin ( 12 ) between a locked position, in which the tappet ( 8 ) is translatably linked to the valve ( 3 ), and an unlocked position, in which the tappet ( 8 ) freely slides on the stem ( 3 a ) of the valve.

1 . A device for actuating by a cam at least one valve slidably mounted in a support, the device comprising:
 a tappet mounted at a free end of a stem of the valve and mobile relative to the support:   return spring means for the tappet adapted to cause the tappet to bear against the cam; and   electromagnetic locking means including an electromagnetic actuator, the actuator comprising a coil external to the tappet, and at least one pin subjected to the magnetic field of the actuator so that energization of the coil drives selective movement of the pin between a locked position in which the tappet is coupled to the valve so as to move in translation therewith, and an unlocked position in which the tappet slides freely on the valve stem.   
     
     
         2 . The device as claimed in  claim 1 , wherein the tappet includes an opening designed to receive slidably the valve and the pin is configured to slide perpendicularly to the valve between an activation position in which the pin projects into the opening to constrain the tappet to move in translation with the valve, and a deactivation position in which the pin is retracted from the opening to allow the tappet to slide freely on the valve stem ( 3   a,    103   a ), the electromagnetic actuator being configured to move the pin selectively between the activation position and the deactivation position. 
     
     
         3 . The device as claimed in  claim 1 , wherein the pin is totally integrated into the tappet. 
     
     
         4 . The device as claimed in  claim 2 , wherein, in the activation position, the pin is received in a housing in a sleeve coupled to the valve. 
     
     
         5 . The device as claimed in  claim 2 , wherein, in the activation position, the pin bears on one end of the valve stem in order to lock the tappet to the valve. 
     
     
         6 . The device as claimed in  claim 5 , wherein the pin includes a flat designed to bear on the end of the valve stem. 
     
     
         7 . The device as claimed in  claim 1 , wherein said magnetic coil of the electromagnetic actuator is designed to extend perpendicularly to the valve so that the axial component of the magnetic field generated moves the pin. 
     
     
         8 . The device as claimed in  claim 1 , wherein said magnetic coil of the electromagnetic actuator is designed to extend parallel to the valve so that the radial component of the magnetic field generated moves the pin. 
     
     
         9 . The device as claimed in  claim 7 , further comprising a plurality of pins. 
     
     
         10 . The device as claimed in  claim 9 , wherein the locking means include two diametrally opposite pins sliding in opposite directions to lock or unlock the tappet. 
     
     
         11 . The device as claimed in  claim 9 , wherein each pin has a respective electromagnetic actuator.