Patent ID: 8893673

Claim:
A tubular valve for adjusting the compression ratio of a variable compression ratio engine comprising a crankcase ( 100 ) accommodating a double-acting hydraulic control actuating cylinder ( 8 ) which comprises an upper chamber ( 121 ) and a lower chamber ( 122 ), both filled with a hydraulic fluid, and at least one actuating cylinder piston ( 13 ) connected to a control rack ( 7 ), said tubular valve comprising: at least one straight tube ( 401 ) capable of a longitudinal translational movement in a valve casing ( 402 ) comprising a low-pressure chamber ( 403 ) placed in communication with a pressure accumulator ( 251 ) by at least one duct ( 404 ), and a high-pressure chamber ( 405 ) placed in communication with one or other of the upper ( 121 ) or lower ( 122 ) chambers of the control actuating cylinder ( 8 ) by at least one duct ( 406 ), said at least one straight tube ( 401 ) comprising a first end ( 407 ) opening into said low-pressure chamber ( 403 ) and a second end ( 408 ) opening into said high-pressure chamber ( 405 ), said second end ( 408 ) being able to come into contact with at least one shut-off surface ( 412 ) secured to said valve casing ( 402 ) in such a way as to seal said second end as tightly as possible, said at least one straight tube ( 401 ) being kept in contact with the at least one shut-off surface ( 412 ) by at least one nonreturn and shut-off spring ( 427 ); sealing means ( 409 ) for sealing between the external surface of said at least one straight tube ( 401 ) and the valve casing ( 402 ) isolating the high-pressure chamber ( 405 ) from the low-pressure chamber ( 403 ), said sealing means ( 409 ) consisting of a nonreturn tube ( 425 ) inside which the at least one straight tube ( 401 ) is held, the at least one straight tube ( 401 ) being capable of moving longitudinally in the nonreturn tube ( 425 ), while said nonreturn tube ( 425 ) can move longitudinally with respect to the valve casing ( 402 ), said at least one straight tube ( 401 ) with said nonreturn tube ( 425 ) creating a seal, said nonreturn tube ( 425 ) comprising a first end ( 426 ) which is furthest from the at least one shut-off surface ( 412 ) of the at least one straight tube ( 401 ) which is kept in contact by the at least one nonreturn and shut-off spring ( 427 ) with a nonreturn seat ( 428 ) formed in the valve casing ( 402 ) so as to prevent the hydraulic fluid from passing from the high-pressure chamber ( 405 ) to the low-pressure chamber ( 403 ), but allow said hydraulic fluid to pass from the low-pressure chamber ( 403 ) to the high-pressure chamber ( 405 ); and at least one electric actuator ( 450 ) capable of applying to the at least one straight tube ( 401 ) a force that opposes that produced by the at least one nonreturn and shut-off spring ( 427 ), said force being enough to separate the at least one straight tube ( 401 ) from the at least one shut-off surface ( 412 ) when electric current is passing through said at least one electric actuator.