Valve timing control system for internal combustion engine

A control valve for controlling a communication state in a hydraulic passage in a hydraulic unit comprising:

• a cylindrical sleeve constructed and arranged to be insertable into a receiving space of the hydraulic unit, the sleeve defining a space therein, the sleeve having a pair of openings to the sleeve space arranged on a cylindrical outer periphery of the sleeve, each of the pair of openings being elongate in shape and extending circumferentially about the sleeve over an angular range less than 180 degrees;
• a spool movably disposed in the space;
• and
• an actuator arranged to mechanically operate the spool for moving the spool between a position wherein the pair of openings are connected and a position wherein the pair of openings are disconnected,
• wherein the pair of openings are arranged at circumferentially opposite sides of the sleeve and are offset axially from each other such that a length of a portion of the sleeve between the pair of openings prevents leakage between the pair of openings when the spool is in the disconnected position.

A valve timing control system for an internal combustion engine comprising:

• a valve timing varying mechanism having a pressure chamber for varying a valve timing in response to a pressure in the pressure chamber;
• a passage defining member defining a receiving space, the passage defining member also defining a passage connecting the receiving space with the pressure chamber;
• and
• a control valve communicating with the pressure chamber for controlling the pressure in the pressure chamber, the control valve comprising:
• a cylindrical sleeve disposed in the receiving space of the passage defining member, the sleeve defining a space therein, the sleeve having three openings to the sleeve space arranged on a cylindrical outer periphery of the sleeve, each of the openings being elongate in shape and extending circumferentially about the sleeve over an angular range less than 180 degrees, a first opening for connecting the sleeve space to the passage of the passage defining member, a second opening for connecting the sleeve space to a pressure source and a third opening for connecting the sleeve space to a pressure drain;
• a spool movably disposed in the sleeve space;
• and
• an actuator arranged to mechanically operate the spool for moving the spool between a pressurizing position wherein the first opening is connected to the second opening and an exhausting position wherein the first opening is connected to the third opening,
• wherein the first opening is arranged on a circumferentially opposite side of the sleeve from the second opening and the third opening, wherein the first opening is offset axially from the second opening and the third opening and wherein the second opening is offset axially from the third opening such that a first length of a portion of the sleeve between the first and second openings prevents leakage between the first and second openings when the spool is in the exhausting position, such that a second length of a portion of the sleeve between the first and third openings prevents leakage between the first and third openings when the spool is in the pressurizing position.

A valve timing control system for an internal combustion engine comprising:

• a valve timing varying mechanism having an advancing pressure chamber and a retarding pressure chamber for varying a valve timing in response to a pressure difference between the advancing pressure chamber and the retarding pressure chamber;
• a passage defining member defining a receiving space, the passage defining member also defining a first passage connecting the receiving space with the advancing pressure chamber and a second passage connecting the receiving space with the retarding pressure chamber;
• and
• a control valve communicating with the advancing pressure chamber and the retarding pressure chamber for controlling the pressure difference, the control valve comprising:
• a cylindrical sleeve disposed in the receiving space of the passage defining member, the sleeve defining a space therein, the sleeve having four openings to the sleeve space arranged on a cylindrical outer periphery of the sleeve, each of the openings being elongate in shape and extending circumferentially about the sleeve over an angular range less than 180 degrees, a first opening for connecting the sleeve space to the first passage of the passage defining member, second opening for connecting the sleeve space to the second passage of the passage defining member, a third opening for connecting the sleeve space to a pressure source and a fourth opening for connecting the sleeve space to a pressure drain;
• a spool movably disposed in the sleeve space;
• and
• an actuator arranged to mechanically operate the spool for moving the spool between a valve advancing position wherein the first opening is connected to the third opening and the second opening is connected to the fourth opening and a valve retarding position wherein the second opening is connected to third opening and the first opening is connected to the fourth opening,
• wherein the first opening and the second opening are arranged on a circumferentially opposite side of the sleeve from the third opening and the fourth opening, wherein the first opening and the second opening are offset axially from the third opening and the fourth opening, wherein the first opening is offset axially from the second opening, and wherein the third opening is offset axially from the fourth opening such that a first length of a portion of the sleeve between the first and third openings prevents leakage between the first and third openings when the spool is in the valve retarding position, such that a second length of a portion of the sleeve between the second and third openings prevents leakage between the second and third openings when the spool is in the valve advancing position.