Valve timing control apparatus

A valve timing control apparatus comprising:

• a driving rotation member synchronously rotating with a crankshaft of an internal combustion engine;
• a driven rotation member coaxially arranged with the driving rotation member and synchronously rotating with a camshaft for opening and closing a valve of the internal combustion engine;
• an advance angle chamber defined by the driving rotation member and the driven rotation member, the advance angle chamber displacing a rotation phase of the driven rotation member relative to the driving rotation member in an advance angle direction when the hydraulic fluid is supplied to the advance angle chamber;
• a retard angle chamber defined by the driving rotation member and the driven rotation member, the retard angle chamber displacing the rotation phase of the driven rotation member relative to the driving rotation member in a retard angle direction when the hydraulic fluid is supplied to the retard angle chamber;
• an advance angle oil passage through which the hydraulic fluid is supplied to or discharged from the advance angle chamber;
• a retard angle oil passage through which the hydraulic fluid is supplied to or discharged from the retard angle chamber;
• an oil pump supplying the hydraulic fluid to the advance angle oil passage and the retard angle oil passage;
• a passage switching valve switching a position thereof between a first position, in which an output portion of the oil pump communicates with the advance angle oil passage, and a second position, in which the output portion of the oil pump communicates with the retard angle oil passage;
• a drain mechanism provided between the passage switching valve and at least one of the advance angle chamber and the retard angle chamber for accelerating discharge of the hydraulic fluid from one of the advance angle chamber and the retard angle chamber when the hydraulic fluid is supplied to the other of the advance angle chamber and the retard angle chamber;
• wherein the drain mechanism includes a retard angle oil passage drain mechanism which is provided between the retard angle chamber and the passage switching valve and accelerates the discharge of the hydraulic fluid from the retard angle oil passage when the hydraulic fluid is supplied to the advance angle chamber through the advance angle oil passage by the oil pump, and the drain mechanism further includes an advance angle oil passage drain mechanism which is provided between the advance angle chamber and the passage switching valve and accelerates the discharge of the hydraulic fluid from the advance angle oil passage when the hydraulic fluid is supplied to the retard angle chamber through the retard angle oil passage by the oil pump;
• wherein the advance angle oil passage drain mechanism has an advance angle drain valve which is switched between an advance angle drainage position in which the hydraulic fluid is discharged from the advance angle oil passage and an advance angle non-drainage position in which the hydraulic fluid is prevented from being discharged from the advance angle oil passage, and the advance angle drain valve is switched from the advance angle drainage position to the advance angle non-drainage position when the hydraulic fluid pressure of the advance angle oil passage exceeds a first predetermined value, wherein the retard angle oil passage drain mechanism has a retard angle drain valve which is switched between a retard angle drainage position in which the hydraulic fluid is discharged from the retard angle oil passage and a retard angle non-drainage position in which the hydraulic fluid is prevented from being discharged from the retard angle oil passage, and the retard angle drain valve is switched from the retard angle drainage position to the retard angle non-drainage position when the hydraulic fluid pressure of the retard angle oil passage exceeds a second predetermined value;
• and
• wherein the retard angle oil passage drain mechanism further includes a retard angle auxiliary valve discharging the hydraulic fluid in the retard angle chamber through the retard angle oil passage and the retard angle drain valve when the hydraulic fluid pressure in the advance angle oil passage exceeds a third predetermined value, and the advance angle oil passage drain mechanism further includes an advance angle auxiliary valve discharging the hydraulic fluid in the advance angle oil chamber through the advance angle oil passage and the advance angle drain valve when the hydraulic fluid pressure in the retard angle oil passage exceeds a fourth predetermined value.

A valve timing control apparatus comprising:

• a driving rotation member synchronously rotating with a crankshaft of an internal combustion engine;
• a driven rotation member coaxially arranged with the driving rotation member and synchronously rotating with a camshaft for opening and closing a valve of the internal combustion engine;
• an advance angle chamber defined by the driving rotation member and the driven rotation member, the advance angle chamber displacing a rotation phase of the driven rotation member relative to the driving rotation member in an advance angle direction when the hydraulic fluid is supplied to the advance angle chamber;
• a retard angle chamber defined by the driving rotation member and the driven rotation member, the retard angle chamber displacing the rotation phase of the driven rotation member relative to the driving rotation member in a retard angle direction when the hydraulic fluid is supplied to the retard angle chamber;
• an advance angle oil passage through which the hydraulic fluid is supplied to or discharged from the advance angle chamber;
• a retard angle oil passage through which the hydraulic fluid is supplied to or discharged from the retard angle chamber;
• an oil pump supplying the hydraulic fluid to the advance angle oil passage and the retard angle oil passage;
• a passage switching valve switching a position thereof between a first position, in which an output portion of the oil pump communicates with the advance angle oil passage, and a second position, in which the output portion of the oil pump communicates with the retard angle oil passage;
• and
• a drain mechanism between the passage switching valve and at least one of the advance angle chamber and the retard angle chamber to release the hydraulic fluid from one of the advance angle chamber and the retard angle chamber to an atmosphere without passing the passage switching valve when the hydraulic fluid is supplied to the other of the advance angle chamber and the retard angle chamber.