TECHNICAL FIELD

The present disclosure relates to a valve timing adjustment device.

BACKGROUND

There is known a valve timing adjustment device that is 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 adjusts a valve timing of valves that are driven to open and close by the driven shaft.

In a case where the valve timing adjustment device is a hydraulic type, the valve timing adjustment device includes: a housing that is rotated synchronously with one of the drive shaft and the driven shaft; and a vane rotor that is fixed to an end portion of the other one of the drive shaft and the driven shaft. The valve timing adjustment device rotates the vane rotor in a retarding direction or an advancing direction by supplying hydraulic oil to retard chambers or advance chambers defined by the vane rotor in the inside of the housing. The hydraulic oil to be supplied to the retard chambers and the advance chambers is controlled by a hydraulic oil control valve.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

According to the present disclosure, there is provided a valve timing adjustment device configured to adjust a valve timing of a valve of an internal combustion engine. The valve timing adjustment device includes a phase shifter and a hydraulic oil controller. The phase shifter includes a retard chamber and an advance chamber. The hydraulic oil controller is configured to control a flow of hydraulic oil supplied to the retard chamber and the advance chamber by controlling the hydraulic oil flowing in a retard supply oil passage, which connects between a hydraulic oil supply source and the retard chamber, and the hydraulic oil flowing in an advance supply oil passage, which connects between the hydraulic oil supply source and the advance chamber. The hydraulic oil controller includes a drain port, a partition, a recycle oil passage and a drain flow restrictor. The drain port is connected to an oil discharge portion that is configured to store the hydraulic oil discharged from the retard chamber or the advance chamber. The partition is configured to partition between a drain oil passage and a corresponding one of the retard supply oil passage and the advance supply oil passage. The drain oil passage connects between the oil discharge portion and a corresponding one of the retard chamber and the advance chamber. The recycle oil passage connects between: a portion of the drain oil passage located between the partition and the drain port; and the retard supply oil passage or the advance supply oil passage. The drain flow restrictor is formed in the drain oil passage at a location between the partition and the drain port. A passage cross-sectional area of the drain flow restrictor is smaller than a smallest passage cross-sectional area of the recycle oil passage and is constant.

