Cam for actuating a valve mechanism of an internal combustion engine

Abstract

Cam for actuating a valve mechanism of an internal combustion engine, having a cam base circle ( 33 ), a main cam region ( 32 ) and a pre-cam region ( 31 ), which is formed between the cam base circle ( 33 ) and main cam region and directly precedes a rising section ( 32 a ) of the main cam region ( 32 ), wherein the pre-cam region ( 31 ) has a profile which effects an increase in the cam lift speed followed by a decrease in the cam lift speed followed by a further increase in the cam lift speed.

1 . A cam for actuating a valve mechanism of an internal combustion engine, having a cam base circle ( 33 ), a main cam region ( 32 ) and a pre-cam region ( 31 ), which is formed between the cam base circle ( 33 ) and main cam region ( 32 ) and directly precedes a rising section ( 32   a ) of the main cam region ( 32 ), wherein the pre-cam region ( 31 ) has a profile which effects an increase in the cam lift speed followed by a decrease in the cam lift speed followed by a further increase in the cam lift speed.  
   
   
       2 . A cam of  claim 1 , wherein the pre-cam region ( 31 ) has a profile comprising a first section ( 1 ) for providing a progressive, substantially linear increase in a cam lift speed, a second section ( 2 ), which follows the first section ( 1 ), for providing a decrease in the cam lift speed, a third section ( 3 ), which follows the second section ( 2 ), for providing a substantially constant cam lift speed, and a forth section ( 4 ), which follows the third section ( 3 ), for providing a further increase in the cam speed.  
   
   
       3 . A cam of  claim 2 , wherein the cam lift speed reached in the third section ( 3 ) of the pre-cam region ( 31 ) defines a value which is acceptable for engine valve opening.  
   
   
       4 . A cam, of  claim 2 , wherein the second section ( 2 ) of the pre-cam region ( 31 ) substantially comprises a linear decrease in the cam lift speed.  
   
   
       5 . A cam of  claim 1 , wherein the profile of the pre-cam region ( 31 ) is provided in a cam region extending over an angle range α, where α is 0.1° to 40°.  
   
   
       6 . A valve mechanism for actuating an engine valve, by a cam of  claim 1 .  
   
   
       7 . A valve mechanism of  claim 6 , characterized by an HVA valve designed as a reverse spring valve.  
   
   
       8 . A valve mechanism of  claim 7 , characterized by an HVA valve designed as a freeball valve.  
   
   
       9 . A valve arrangement for an internal combustion engine having an intake valve and an exhaust valve, wherein the intake valve and/or the exhaust valve can be actuated by a valve mechanism of  claim 6.