Valve train with variable valve actuation

Abstract

A valve train assembly includes valves having a valve stem; a main camshaft having main cams corresponding to the valves; main rocker arms corresponding to the valves; an auxiliary cam arranged on the main camshaft; at an auxiliary cam follower following the auxiliary cam, the auxiliary cam follower being movably arranged on a main rocker arm between a first and second position; and a latch on a main rocker arm for locking the auxiliary cam follower in the first position. A rotatable control rod controlling the latch is between the first and the second positions. The control rod includes a transmission element configured to convert torque in the control rod into a control force to control movement of the latch.

1 : A valve train assembly comprising:
 a plurality of valves each having a valve stem;   at least one main camshaft with a plurality of main cams, at least one main cam corresponding to each of the valves;   a plurality of main rocker arms, each of the main rocker arms corresponding to one of the valves and having a valve stem actuation portion, a pivot axis parallel to the at least one main cam shaft and a main cam follower for following the corresponding one of the main cams, wherein the valve stem actuation portion, the pivot axis and the main cam follower are arranged along a length of a corresponding one of the main rocker arms and at a distance from each other;   at least one auxiliary cam arranged on the at least one main camshaft;   at least one auxiliary cam follower for each of the at least one auxiliary cam and for following the at least one auxiliary cam, wherein the respective at least one auxiliary cam follower is movably arranged on one of the main rocker arms between a first position and a second position;   a latch arranged on a respective one of the main rocker arms for locking the at least one auxiliary cam follower in the first position, and   at least one rotatable control rod for controlling the respective latch between the first position and the second position, and   wherein the at least one control rod comprises for the respective latch a transmission element, the transmission element configured to convert torque in the at least one control rod into a control force tangential to the at least one control rod to control movement of the latch between the first and second position.   
     
     
         2 : The valve train assembly according to  claim 1 ,
 wherein the transmission element is an elongate element arranged with one end to the at least one control rod, and   wherein an other end of the elongate element engages the latch.   
     
     
         3 : The valve train assembly according to  claim 2 ,
 wherein a substantially U-shaped or R-shaped leaf spring is arranged between the other end of the elongate element and the latch, and   wherein the leaf spring is arranged with one free end to the latch.   
     
     
         4 : The valve train assembly according to  claim 1 , further comprising a camshaft carrier for accommodating the at least one main camshaft,
 wherein the transmission element comprises a control cam arranged on the at least one control rod and a curved leaf spring arranged between the control cam and the latch, and   wherein one free end of the curved spring leaf is arranged to the camshaft carrier.   
     
     
         5 : The valve train assembly according to  claim 4 ,
 wherein the curved leaf spring is substantially C-shaped,   wherein the control cam engages on the curved leaf spring at a distance from the attachment of the one free end to the camshaft carrier, and   wherein the other free end of the curved leaf spring engages the latch.   
     
     
         6 : The valve train assembly according to  claim 4 ,
 wherein the curved leaf spring is bent from a M-shaped starting shape,   wherein the leaf spring comprises a bridge portion from which three legs extend parallel to each other,   wherein two outer legs of the three legs are arranged to the camshaft carrier, and   wherein the free end of a middle leg of the three legs engages the latch.   
     
     
         7 : The valve train assembly according to  claim 6 , wherein the two outer legs of the curved leaf spring extend on opposite sides of the control cam. 
     
     
         8 : The valve train assembly according to  claim 6 , wherein the two outer legs are provided with U-shaped free ends. 
     
     
         9 : The valve train assembly according to  claim 1 ,
 wherein the at least one control rod is rotatable between two angles, and   wherein the at least one control rod is provided with bends to accommodate components of a cylinder head on which the valve train assembly is to be mounted.   
     
     
         10 : The valve train assembly according to  claim 1 ,
 wherein the latch comprises a pin movable in a length of a corresponding one of the main rocker arms,   wherein one end of the pin is engagable on an auxiliary rocker arm, and   wherein the pin is arranged with its other end in contact with the transmission element.   
     
     
         11 : A system comprising a cylinder head for a combustion engine and the valve train assembly according to  claim 1 , wherein the valve train assembly is mounted on the cylinder head. 
     
     
         12 : The system according to  claim 11 , further comprising an actuator arranged on a side of the cylinder head, the actuator being coupled to the at least one control rod for rotating the at least one control rod. 
     
     
         13 : The system according to  claim 12 , wherein the actuator is coupled to an end of the at least one control rod. 
     
     
         14 : The system according to  claim 12 , wherein the actuator is coupled to a midsection of the at least one control rod via a worm drive. 
     
     
         15 . The system according to  claim 12 , wherein the actuator is an electric motor.