Valve timing adjustment device

A valve timing adjustment device that is configured to be installed in a drive force transmission path for transmitting a drive force from a drive shaft to a driven shaft of an internal combustion engine and is configured to adjust a valve timing of a valve that is driven to open and close by the driven shaft, wherein one of the drive shaft and the driven shaft is defined as a first shaft while the other one of the drive shaft and the driven shaft is defined as a second shaft, the valve timing adjustment device comprising:

• a housing that is configured to be rotated synchronously with the first shaft, wherein the housing is configured to be fitted to an end portion of the second shaft and is configured to be rotatably supported by the second shaft;
• a vane rotor that is configured to be fixed to the end portion of the second shaft and includes a vane that partitions an inside space of the housing into a primary hydraulic chamber and a secondary hydraulic chamber while the primary hydraulic chamber is located on one side of the vane in a circumferential direction, and the secondary hydraulic chamber is located on the other side of the vane in the circumferential direction, wherein the vane rotor is configured to be rotated relative to the housing depending on a pressure of hydraulic oil supplied from a hydraulic oil supply source to the primary hydraulic chamber and a pressure of the hydraulic oil supplied from the hydraulic oil supply source to the secondary hydraulic chamber;
• a sleeve that includes:
• a sleeve tube;
• a sleeve bottom that closes an end portion of the sleeve tube;
• an inside space that is formed at an inside of the sleeve tube;
• a supply port that is communicated with the hydraulic oil supply source;
• a primary control port that is communicated with the primary hydraulic chamber;
• and
• a secondary control port that is communicated with the secondary hydraulic chamber;
• and
• a spool that includes:
• a spool tube that is installed at the inside space of the sleeve and is configured to reciprocate in an axial direction of the spool;
• a spool cover that closes an end portion of the spool tube;
• a pressure accumulation space that is formed at an inside of the spool tube;
• a supply passage that is configured to connect between the pressure accumulation space and the supply port;
• and
• a control passage that is configured to connect between the pressure accumulation space and the primary control port or the secondary control port, wherein:
• the spool forms a variable volume space between the spool and the sleeve bottom while the variable volume space is a space, a volume of which is variable;
• the sleeve includes a breathing hole that communicates between the variable volume space and an atmosphere and is located at an outside of the inside space of the sleeve;
• the spool further includes a recycle passage that is configured to connect between the pressure accumulation space and the primary control port or the secondary control port;
• and
• the valve timing adjustment device further comprises a recycle check valve that is placed at the inside of the spool, wherein the recycle check valve is configured to enable a flow of the hydraulic oil from the recycle passage toward the pressure accumulation space and is configured to limit a flow of the hydraulic oil from the pressure accumulation space toward the recycle passage.

A valve timing adjustment device that is configured to be installed in a drive force transmission path for transmitting a drive force from a drive shaft to a driven shaft of an internal combustion engine and is configured to adjust a valve timing of a valve that is driven to open and close by the driven shaft, wherein one of the drive shaft and the driven shaft is defined as a first shaft while the other one of the drive shaft and the driven shaft is defined as a second shaft, the valve timing adjustment device comprising:

• a housing that is configured to be rotated synchronously with the first shaft, wherein the housing is configured to be fitted to an end portion of the second shaft and is configured to be rotatably supported by the second shaft;
• a vane rotor that is configured to be fixed to the end portion of the second shaft and includes a vane that partitions an inside space of the housing into a primary hydraulic chamber and a secondary hydraulic chamber while the primary hydraulic chamber is located on one side of the vane in a circumferential direction, and the secondary hydraulic chamber is located on the other side of the vane in the circumferential direction, wherein the vane rotor is configured to be rotated relative to the housing depending on a pressure of hydraulic oil supplied from a hydraulic oil supply source to the primary hydraulic chamber and a pressure of the hydraulic oil supplied from the hydraulic oil supply source to the secondary hydraulic chamber;
• a sleeve that includes:
• a sleeve tube;
• a sleeve bottom that closes an end portion of the sleeve tube;
• an inside space that is formed at an inside of the sleeve tube;
• a supply port that is communicated with the hydraulic oil supply source;
• a primary control port that is communicated with the primary hydraulic chamber;
• and
• a secondary control port that is communicated with the secondary hydraulic chamber;
• and
• a spool that includes:
• a spool tube that is installed at the inside space of the sleeve and is configured to reciprocate in an axial direction of the spool;
• a spool cover that closes an end portion of the spool tube;
• a pressure accumulation space that is formed at an inside of the spool tube;
• a supply passage that is configured to connect between the pressure accumulation space and the supply port;
• and
• a control passage that is configured to connect between the pressure accumulation space and the primary control port or the secondary control port, wherein:
• the spool forms a variable volume space between the spool and the sleeve bottom while the variable volume space is a space, a volume of which is variable;
• the sleeve includes a breathing hole that communicates between the variable volume space and an atmosphere and is located at an outside of the inside space of the sleeve;
• the sleeve further includes a drain port that is communicated with an outside of the valve timing adjustment device;
• the spool further includes a drain passage that is configured to connect between the primary control port or the secondary control port and the drain port;
• and
• the drain port is formed integrally with the breathing hole.