Variable compression ratio engine tubular control valve

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.