Valve assembly and method for high temperature engines

A valve assembly for controlling communication with a chamber in an engine, comprising a valve body having an inlet and outlet ports, a valve seat surrounding one of the ports, a pivotally mounted lever arm that extends into the valve body and is split lengthwise into a relatively stiff section and a relatively flexible section, a valve member connected to the relatively stiff section of the lever arm within the valve body, an actuator connected to the lever arm outside the valve body for moving the valve member between open and closed positions relative to the valve seat, a bypass port opening through the valve member, and a pilot valve plug connected to the relatively flexible section of the lever arm for movement between open and closed positions relative to the bypass port to allow gas to bypass the valve member and thereby reduce the pressure against which the valve member must be moved.

A valve assembly in an external combustion engine having a compression cylinder, an expansion cylinder, pistons for varying the volumes of the compression and expansion cylinders, and an external heat exchanger in which working fluid from the compression cylinder is heated to a high temperature and pressure for delivery to the expansion cylinder, comprising:

• a valve body with an inlet port in communication with the heat exchanger and an outlet port in communication with the expansion cylinder, a valve seat surrounding the outlet port, a pivotally mounted lever arm extending into the valve body between the inlet and outlet ports, a valve member connected to the lever arm near the valve seat, and an actuator connected to the lever arm outside the valve body for moving the valve member between open and closed positions relative to the valve seat.

A method of controlling flow of high temperature, high pressure gases, comprising the steps of:

• introducing high temperature, high pressure gases into a chamber through an inlet port, controlling discharge of the high temperature, high pressure gases from the chamber through an outlet port with a valve member movable within the chamber between open and closed positions relative to a valve seat surrounding the outlet port, and moving the valve member between the open and closed positions from outside the chamber, away from the high temperature, high pressure gases, with an actuator arm of low thermal conductivity which extends into the chamber and is connected to the valve member within the chamber.

A valve assembly, comprising a body having an internal chamber with inlet and outlet ports through which hot gases flow, a valve seat which is fabricated of a material capable of withstanding temperatures on the order of 1000° K-1800° K and has a sealing surface surrounding one of the ports, a pivotally mounted lever arm of low thermal conductivity extending into the chamber for movement about a first axis perpendicular to the lever arm, a valve member which is fabricated of a material capable of withstanding temperatures on the order of 1000° K-1800° K and is connected to the lever arm within the chamber for pivotal movement about the axis of the lever arm and about an axis perpendicular to the lever arm and parallel to the sealing surface, and an actuator connected to the lever arm outside the valve body, away from the hot gases, for pivoting the lever arm about the first axis to move the valve member within the chamber between open and closed positions relative to the valve seat.