Valve timing adjustment apparatus for internal combustion engine
The present disclosure provides a valve timing adjustment apparatus for an internal combustion engine. The apparatus includes an anti-rotation mechanism for inhibiting a position change between a rotor and a housing by inhibiting or preventing relative rotation of the rotor to the housing. The anti-rotation mechanism includes: a plurality of locking grooves formed on the ratchet plate with different depths and connected to each other; and a locking pin member having an outer pin elastically disposed in a fitting hole formed in one of the vanes, and an inner pin elastically disposed inside the outer pin. In particular, the inner pin locks the rotor to the housing when the outer pin and the inner pin are sequentially fitted in the locking grooves by torque from the camshaft.
1. A valve timing adjustment apparatus for an internal combustion engine, the valve timing adjustment apparatus comprising:
a housing defining a space with a ratchet plate operatively associated with a crankshaft;
a rotor having a plurality of vanes configured to rotate relative to the housing within a predetermined angle range by a pressure of a working fluid, the rotor disposed in the housing to operate with a camshaft; and
an anti-rotation mechanism configured to inhibit or prevent a positional change between the rotor and the housing by inhibiting or preventing relative rotation of the rotor to the housing,
wherein the anti-rotation mechanism includes:
a plurality of locking grooves formed on the ratchet plate with different depths; and
a locking pin member comprising:
an outer pin elastically disposed in a fitting hole formed in at least one vane of the plurality of vanes, and
an inner pin disposed inside the outer pin and configured to move relative to the outer pin, and lock the rotor to the housing when the outer pin and the inner pin are independently and sequentially fitted in the plurality of locking grooves.
2. The valve timing adjustment apparatus of claim 1 , wherein the plurality of locking grooves includes a large groove having a large diameter and a small groove having a small diameter, wherein the large groove and the small groove form a stepped portion having predetermined depths.
3. The valve timing adjustment apparatus of claim 2 , wherein a width of the stepped portion is double a thickness of the outer pin, and an inner diameter of the small groove is the same as an outer diameter of the outer pin.
4. The valve timing adjustment apparatus of claim 1 , wherein the locking pin member further has an upper cap having a first recession therein and is configured to close a first end of the fitting hole.
5. The valve timing adjustment apparatus of claim 4 , wherein a second recession is formed at a first end of the outer pin, and an outer spring applying elasticity to the plurality of locking grooves is disposed between the second recession and a first end of the upper cap.
6. The valve timing adjustment apparatus of claim 5 , wherein a third recession is formed at a first end of the inner pin, and an inner spring applying elasticity to the plurality of locking grooves is disposed between the third recession and the first recession of the upper cap.
7. The valve timing adjustment apparatus of claim 6 , wherein the locking pin member further has a lower cap being positioned at a second end of the fitting hole, and the lower cap is configured to support an outer side of the outer pin.
8. The valve timing adjustment apparatus of claim 7 , wherein an exhaust hole is additionally formed in the rotor and configured to discharge the working fluid in the plurality of locking grooves when the locking pin member is locked.
9. The valve timing adjustment apparatus of claim 1 , wherein the plurality of vanes includes four vanes.
10. The valve timing adjustment apparatus of claim 9 , wherein a sealing groove is formed in a longitudinal direction of the camshaft at ends of the plurality of vanes that face an inner side of the housing, and a seal is disposed in the sealing groove.