Patent ID: 7530222

Claim:
A hydraulic assembly adapted for use with an engine exhaust flow control valve, said hydraulic assembly comprising: a hydraulic actuator for positioning the control valve; said hydraulic actuator having an inlet passage for supplying hydraulic fluid to a side of said hydraulic actuator and a drain for draining said hydraulic fluid from said hydraulic actuator side, a hydraulic circuit, connected to said hydraulic actuator, arranged for supplying hydraulic fluid to said inlet passage; a poppet type hydraulic valve, operably coupled to said hydraulic actuator, said poppet type hydraulic valve having an internal chamber and a slidably mounted pin to plug and unplug a metered hole formed in a valve seat of said poppet valve, said valve seat being arranged between said inlet passage and said drain such that unplugging and plugging said metered hole opens and closes said internal chamber to control communication of said hydraulic fluid from said inlet passage to said drain via said internal chamber, and wherein said hydraulic actuator comprises a spring return piston disposed in a cylinder, said cylinder comprising a cylinder body and a longitudinal bore extending therethrough having a first section and a second section, wherein said piston is slidable in said second section of said longitudinal bore and wherein said poppet valve is engaged to said cylinder body such that at least part of the internal chamber is accommodated within said first section of said longitudinal bore to leave a space between said valve seat and said piston to define a control chamber communicating with said inlet passage, and wherein said inlet passage extends through a side wall of said cylinder in fluid communication with said control chamber of said cylinder, wherein said drain extends through said cylinder side wall in fluid communication with said internal chamber and wherein said metering hole intercommunicates said internal chamber and said control chamber to control communication of hydraulic fluid from the control chamber to the drain; whereby, when the hydraulic assembly is in use, the pressure of hydraulic fluid acting on said side of said hydraulic actuator is adjustable by substantially unplugging and plugging said metering hole thereby to control movement of said actuator and, in turn, a movement of said control valve.