Patent ID: 8602000

Claim:
An engine brake unit, comprising: a rocker arm having a first space defined in a valve-pressing portion thereof, wherein the first space communicates with a supply passage, through which engine brake oil is introduced; a stopper fixedly provided above the first space of the rocker arm in a predetermined distance; an actuator located inside the first space and having a pressure piston, wherein the pressure piston is selectively raised by hydraulic pressure of the engine brake oil to butt against the stopper, thereby pressing a portion of the rocker arm downwards; wherein the rocker arm further includes: a discharge passage connected to the first space; and a control valve located in a second space defined in the rocker arm and selectively opening the discharge passage to discharge the engine brake oil which is introduced into the first space; wherein the actuator comprises: the pressure piston having a storage therein; a main elastic member elastically biasing the pressure piston towards a first passage connecting the supply passage with the first space; a check ball disposed onto an entrance of the first passage in the storage of the pressure piston; and a sub-elastic member disposed in the storage of the pressure piston and elastically biasing the check ball towards the entrance of the first space to open or close the entrance of the first space according to the hydraulic pressure supplied to the first passage.