VARIABLE ACTUATOR FOR A VALVE - SOUTH WESTERN IND RES

Title:

VARIABLE ACTUATOR FOR A VALVE

Document Type and Number:

WIPO Patent Application WO/1987/007677

Kind Code:

A1

Abstract:

A valve actuator such as an hydraulic tappet. In one embodiment the tappet comprises a cylinder (16) which defines by means of a central wall (17), upper and lower chambers (18, 19). These have respective pistons (20 and 21). Piston (20) is connected to an actuator rod (13) of a valve (11), whilst piston (21) rides on a cam (23). The central wall is formed with two flow paths (24 and 25). The first allows oil to flow from the chamber (19) to the chamber (18) during upward movement of the piston (21) and hence the cam can cause lifting movement of the piston (20) and opening of the valve (11). As the cam (23) falls away the valve (11) closes under the action of spring (14) which results in downward movement of the upper piston (20). The rate of this return is dictated by the rate at which oil can flow through the passage (25) which can be variably restricted by control element (27). Thus, by adjustment of the control element (27) the rate of closing of the valve (11) can be varied. Other embodiments are described but in each the return movement of the upper piston (20) is variably damped.

Inventors:

CHARLTON STEPHEN JOHN (GB)
BELL DAVID JOHN (GB)
HOWARD PETER CHARLES (GB)
HAINES ANDREW JOHN (GB)
BIRD STUART LAWRENCE (GB)

Application Number:

PCT/GB1987/000411

Publication Date:

December 17, 1987

Filing Date:

June 12, 1987

Export Citation:

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Assignee:

SOUTH WESTERN IND RES (GB)

International Classes:

F01L1/16; F01L9/10; F01L13/00; (IPC1-7): F01L9/02; F01L1/16; F01L31/22

Foreign References:

US3938483A	1976-02-17
DE2057667A1	1972-06-08
FR2252023A5	1975-06-13
DE1250677B
EP0027949A1	1981-05-06

Other References: