A phase change system for opening and/or closing intake valves

Abstract

A phase change system for opening and/or closing at least an intake valve in the internal combustion engine of a saddle vehicle. comprising a rocker pivoting around a pivot axis and adapted to transform the rotary motion of a camshaft into a motion for opening/closing at least an intake valve of the engine. and a selecting member adapted to interact with the rocker so that this latter takes different operative configurations to postpone or to advance the opening/closing of the intake valve.

1 . A phase change system for opening and/or closing at least an intake valve in the internal combustion engine of a saddle vehicle, the phase change system comprising:
 a rocker pivoting around a pivot axis and adapted to transform the rotary motion of a camshaft of the engine into a motion for opening/closing at least an intake valve of the engine; and   a selecting member adapted to interact with the rocker so that the rocker takes different operative configurations to postpone or to advance the opening/closing of the intake valve,   and wherein the rocker comprises at least three arms, a first arm articulated around the pivot axis and provided with an area of interaction with the intake valve to allow actuating the valve, and at least a second and a third arm, both articulated around said pivot axis and provided with respective areas of interaction with the camshaft to allow the rocker to move based on the rotation of the camshaft, and wherein the at least three arms respectively define at least a first, a second and a third portion of a sliding channel for said selecting member, so that the selecting member is adapted to slide in this sliding channel so as to take at least two positions, a position adapted to make the first arm and the second arm rotate integrally around the pivot axis, and a position adapted to make the first arm and the third arm rotate integrally around the pivot axis, so that, based on the position taken by the selecting member in the sliding channel, the rocker takes different operative configurations for opening/closing the intake valve, wherein the selecting member comprises at least two axially adjacent pins sliding in the channel and provided with two respective operative ends that always touch each other, respectively at least an engagement pin for engaging the channel portions and at least an extension pin in contact with a pushing body that is at least partially external to said channel, the pushing body being adapted to push the engagement pin by thrusting the extension pin, and wherein the extension pin is adapted to slide in only one channel portion, and wherein the pushing body is a rod slidable parallel to the pivot axis.   
     
     
         2 . The system of  claim 1 , wherein the engagement pin is adapted to engage two channel portions, in particular it is adapted to engage always the first channel portion and, alternatively, the second channel portion or the third channel portion, and the extension pin is adapted to engage only the second channel portion. 
     
     
         3 . The system of  claim 1 , wherein the pushing body is adapted to push the extension pin so as to move it from a first position, wherein the extension pin is spaced from the first arm and the engagement pin contemporaneously engages the first channel portion and the second channel portion, so that the first arm and the second arm rotate integrally, to a second position, wherein the extension pin is closer to the first arm with respect to the first position and the engagement pin is outside the second channel portion and contemporaneously engages the first channel portion and the third channel portion, so that the first arm and the second arm rotate integrally. 
     
     
         4 . The system of  claim 1 , wherein the extension pin has a part projecting outside the second channel portion, this projecting part being adapted to be in contact with the pushing body. 
     
     
         5 . The system of  claim 1 , wherein the engagement pin and the extension pin have different transverse width; wherein the engagement pin has at least a cross section larger than that of the extension pin. 
     
     
         6 . The system of  claim 2 , wherein a pushing device is provided in the third channel portion for pushing the engagement pin towards the second channel portion when the engagement pin engages the third channel portion; the pushing device is being an elastic element acting by compression. 
     
     
         7 . The system of  claim 1 , comprising an actuator for moving the pushing body. 
     
     
         8 . The system of  claim 7 , wherein the actuator comprises an actuating head movable parallel to the pushing body or coaxially with the extension axis of the pushing body. 
     
     
         9 . The system of  claim 7 , wherein the actuator is of electro-mechanical kind. 
     
     
         10 . The system of  claim 1 , comprising at least a hindering device preventing the second arm and the third arm from moving away from the respective cams of the camshaft; the hindering device being a yielding device adapted to keep the arms touching the respective cams; the hindering device being a torsion spring fastened to the first, the second and the third arms. 
     
     
         11 . A single-cylinder internal combustion engine for a saddle vehicle, comprising:
 a cylinder;   a piston sliding in the cylinder;   a drive shaft kinematically connected to the drive shaft;   a distribution comprising at least a intake valve for gas intake in the cylinder, at least an exhaust valve for discharging gas from the cylinder, and a camshaft; and   a phase change system for opening and/or closing the intake valve of one or more  of the previous claims , the phase change system comprising:   a rocker pivoting around a pivot axis and adapted to transform the rotary motion of a camshaft of the engine into a motion for opening/closing at least an intake valve of the engine; and   a selecting member adapted to interact with the rocker so that the rocker takes different operative configurations to postpone or to advance the opening/closing of the intake valve, and wherein the rocker comprises at least three arms, a first arm articulated around the pivot axis and provided with an area of interaction with the intake valve to allow actuating the valve, and at least a second and a third arm, both articulated around said pivot axis and provided with respective areas of interaction with the camshaft to allow the rocker to move based on the rotation of the camshaft, and wherein the at least three arms respectively define at least a first, a second and a third portion of a sliding channel for said selecting member, so that the selecting member is adapted to slide in this sliding channel so as to take at least two positions, a position adapted to make the first arm and the second arm rotate integrally around the pivot axis, and a position adapted to make the first arm and the third arm rotate integrally around the pivot axis, so that, based on the position taken by the selecting member in the sliding channel, the rocker takes different operative configurations for opening/closing the intake valve, wherein that the selecting member comprises at least two axially adjacent pins sliding in the channel and provided with two respective operative ends that always touch each other, respectively at least an engagement pin for engaging the channel portions and at least an extension pin in contact with a pushing body that is at least partially external to said channel, the pushing body being adapted to push the engagement pin by thrusting the extension pin, and wherein the extension pin is adapted to slide in only one channel portion, and wherein the pushing body is a rod slidable parallel to the pivot axis.   
     
     
         12 . A saddle vehicle comprising the single-cylinder internal combustion engine of  claim 11 . 
     
     
         13 . The system of  claim 5 , wherein the second channel portion has a change in cross section defining an end of stroke abutment for the engagement pin.