Patent ID: 8240278

Claim:
An engine brake comprising: a rocker shaft; a rocker arm pivoting around the rocker shaft; an actuator piston disposed to the rocker arm and selectively protruded therefrom; a stopper disposed to a corresponding position of the actuator piston with a predetermined distance for the rocker arm to open a valve when the actuator piston is protruded; and a hydraulic pressure supply portion fluid-connected to the actuator piston and selectively supplying hydraulic pressure to the actuator piston, wherein the rocker arms are provided as a plurality; wherein the hydraulic pressure supply portion selectively supplies hydraulic pressure to each actuator piston disposed to the plurality of rocker arms; wherein the hydraulic pressure supply portion includes: a solenoid valve selectively opening an oil passage to the actuator piston; a hydraulic pressure control portion that is opened according to hydraulic pressure in the oil passage opened by the solenoid valve; a hydraulic pressure supply line connecting each of the actuator pistons and the hydraulic pressure control portion, a housing connected to the solenoid valve via the oil passage; a supply hole formed to the housing; an exhaust hole formed to the housing; a hydraulic piston that is movably disposed within the housing for selectively supplying hydraulic pressure to the hydraulic pressure supply line via the supply hole or releasing hydraulic pressure of the hydraulic pressure supply line through the exhaust hole according to operations of the solenoid valve; and a hydraulic piston spring elastically biasing the hydraulic piston to open a fluid communication between the supply hole and the exhaust hole in the housing; and wherein the hydraulic piston comprises: protrude portions that close fluid communication between the supply hole and the exhaust hole when the engine brake operates; a recess portion formed between the protrude portions for supplying hydraulic pressure of the oil passage to the supply hole when the engine brake operates; and a chamber formed within the hydraulic piston and fluid-connected to the recess portion to supply hydraulic pressure of the oil passage to the supply hole through the recess portion.