Patent ID: 7204212
Filing Date: 2007-04-17
Classification: F01L

Abstract:
1. An apparatus for hydraulically actuating a gas exchange valve, the apparatus comprising: a fluid source coupled with a fluid reservoir, the fluid source operable to provide a a low-pressure, substantially constant flow of fluid; at least one actuator cylinder coupled with the fluid source, the actuator cylinder containing an actuator piston therein coupled to the gas exchange valve, the actuator piston operable to slide within the actuator cylinder upon application of pressure from the fluid applied thereto from the source for actuating the gas exchange valve; a fluid supply line coupled between the fluid source and the actuator cylinder; a pressure sensor connected to the fluid supply line; a controller that inputs a signal from the pressure sensor, the controller controls the application of fluid to the actuator cylinder such that the pressure in the cylinder begins to rise to operate the actuator piston to open the gas exchange valve from a seated position, the controller monitors a pressure of the fluid to provide feedback about the operation of the gas exchange valve, and uses the monitored pressure of the fluid for variable motion control of the gas exchange valve; and an inlet device disposed before the actuator cylinder, the inlet device having at least two operable stages, wherein when switched by the controller to operate in a first stage, the inlet device allows low-pressure fluid from the fluid source to freely pass through the inlet device, and when switched by the controller to operate in a second stage, the inlet device directs the low-pressure fluid to the actuator cylinder such that the low-pressure fluid is applied to the actuator cylinder to operate the actuator piston to open the gas exchange valve from the seated position.