Variable valve actuation apparatus of internal combustion engine
View Patent ↗A variable valve actuation apparatus includes a lock pin slidably disposed in a slide bore formed in a rotor of a vane rotor, a retaining hole formed in an inner face of a sprocket, and a lock-hole structural member fixed and press-fitted into the retaining hole and configured to form the lock hole. The retaining hole is formed at the innermost peripheral side of the sprocket so as to face a central support bore of the sprocket. The inner end face of a large-diameter bore of the retaining hole is formed as a flat surface, whereas the outer end face of a lock-hole structural section of the lock-hole structural member is formed as a planar section. The lock-hole structural member is precisely positioned in its rotation direction by abutment between the flat inner end face and the planar outer end face.
1. A variable valve actuation apparatus of an internal combustion engine, comprising:
a driving rotary member adapted to be driven by a crankshaft of the engine and configured to define therein a working-fluid chamber;
a vane rotor adapted to be fixedly connected to a camshaft and configured to partition the working-fluid chamber into a phase-advance hydraulic chamber and a phase-retard hydraulic chamber and configured to relatively rotate in either one of a phase-advance direction and a phase-retard direction with respect to the driving rotary member by selectively supplying working fluid to one of the phase-advance hydraulic chamber and the phase-retard hydraulic chamber and draining working fluid from the other of the phase-advance hydraulic chamber and the phase-retard hydraulic chamber;
a slide bore formed in the vane rotor as an axial through hole extending along an axial direction of the camshaft;
a lock member slidably disposed in the slide bore;
a retaining hole formed in an inner face of the driving rotary member so as to face the working-fluid chamber; and
a lock-hole structural member fixed into the retaining hole and configured to form a lock hole with which a tip of the lock member is brought into engagement when the vane rotor has relatively rotated to a predetermined angular position with respect to the driving rotary member,
wherein a flat surface is formed along a given part of an inner peripheral surface of the retaining hole, and
wherein a planar section is formed along a given part of an outer peripheral surface of the lock-hole structural member, the planar section being configured to abut the flat surface of the retaining hole.
2. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 1 , wherein:
the retaining hole comprises a large-diameter bore formed to face the working-fluid chamber and a small-diameter bore formed in a bottom face of the large-diameter bore; and
the lock-hole structural member comprises a lock-hole structural section configured to be retained in the large-diameter bore and having the lock hole formed in a top end of the lock-hole structural section, and a press-fit section protruding from a bottom of the lock-hole structural section and configured to be press-fitted into the small-diameter bore.
3. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 2 , wherein:
the planar section is formed on an outer peripheral surface of the lock-hole structural section, and the flat surface of the retaining hole is formed on an inner peripheral surface opposed to the outer peripheral surface of the lock-hole structural section, the planar section being arranged along the flat surface and brought into abutment with the flat surface.
4. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 3 , wherein:
the lock-hole structural section of the lock-hole structural member is retained in the large-diameter bore of the retaining hole.
5. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 2 , wherein:
the press-fit section is press-fitted into the small-diameter bore by movement of the planar section into the large-diameter bore along the flat surface, when fixing the lock-hole structural member into the retaining hole.
6. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 2 , wherein:
a chamfered portion is formed at an edge of the planar section of the outer peripheral surface of the lock-hole structural member, facing the press-fit section.
7. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 6 , wherein:
a depth of the large-diameter bore is dimensioned to be greater than an axial length of the lock-hole structural member from an uppermost end of the chamfered portion to a lowermost end of an effective press-fit part of the press-fit section.
8. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 1 , wherein:
the vane rotor comprises a substantially cylindrical-hollow rotor and a plurality of radially-protruding vanes formed on an outer periphery of the vane rotor; and
the driving rotary member has a support bore into which the rotor is rotatably inserted, and a radially inside end of the retaining hole is formed as an inside opening end opened into the support bore of the driving rotary member.
9. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 1 , wherein:
a radial dimension of the lock-hole structural member in a radial direction of the driving rotary member is dimensioned to be less than a circumferential dimension of the lock-hole structural member in a circumferential direction of the driving rotary member.
10. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 1 , wherein:
the lock hole is formed into a circumferentially-elongated elliptic shape.
11. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 1 , wherein:
the lock hole is formed as a stepped hole having a plurality of bottom faces configured to lower stepwise.
12. A variable valve actuation apparatus of an internal combustion engine, comprising:
a driving rotary member adapted to be driven by a crankshaft of the engine and configured to define therein a working-fluid chamber;
a vane rotor adapted to be fixedly connected to a camshaft and configured to partition the working-fluid chamber into a phase-advance hydraulic chamber and a phase-retard hydraulic chamber and configured to relatively rotate in either one of a phase-advance direction and a phase-retard direction with respect to the driving rotary member by selectively supplying working fluid to one of the phase-advance hydraulic chamber and the phase-retard hydraulic chamber and draining working fluid from the other of the phase-advance hydraulic chamber and the phase-retard hydraulic chamber;
a slide bore formed in the vane rotor as an axial through hole extending along an axial direction of the camshaft;
a lock member slidably disposed in the slide bore;
a stepped recessed portion formed in an inner face of the driving rotary member so as to face the working-fluid chamber; and
a lock-hole structural member fixed into the stepped recessed portion and configured to form a lock hole with which a tip of the lock member is brought into engagement when the vane rotor has relatively rotated to a predetermined angular position with respect to the driving rotary member,
wherein a flat surface is formed along a given part of an inner peripheral surface of the stepped recessed portion, and
wherein a planar section is formed along a given part of an outer peripheral surface of the lock-hole structural member, the planar section being configured to abut the flat surface of the stepped recessed portion.
13. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 1 , wherein:
the driving rotary member has a rear cover whose outer periphery is formed with a sprocket gear, and a support bore is formed in the rear cover as an axial through hole into which a rotor of the vane rotor is rotatably inserted; and
the retaining hole is formed at an inner peripheral side of the rear cover, facing the support bore, and a radially inside end of the retaining hole is formed as an inside opening end opened into the support bore of the driving rotary member.
14. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 1 , wherein:
the retaining hole comprises a large-diameter bore formed to face the working-fluid chamber and a small-diameter bore formed in a substantially center of a bottom face of the large-diameter bore; and
the lock-hole structural member comprises a lock-hole structural section configured to be retained in the large-diameter bore and having the lock hole formed in a top end of the lock-hole structural section, and a press-fit section protruding from a bottom of the lock-hole structural section and configured to be press-fitted into the small-diameter bore.
15. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 14 , wherein:
the planar section comprises two planar sections formed as both outside faces of the lock-hole structural member, and the flat surface comprises two flat surfaces formed as both inside faces of the retaining hole, opposed to the both outside faces, the two planar sections being arranged along the flat surfaces and brought into abutment with the flat surfaces respectively.
16. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 15 , wherein:
the press-fit section is press-fitted into the small-diameter bore by movement of the two planar sections into the large-diameter bore along the respective flat surfaces, when fixing the lock-hole structural member into the retaining hole.
17. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 16 , wherein:
the both outside faces are formed as width across flats on the outer peripheral surface of the lock-hole structural member, whereas the both inside faces are formed as two opposing inside faces on the inner peripheral surface of the retaining hole and configured to abut the respective width across flats of the lock-hole structural member.
18. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 15 , wherein:
a depth of the small-diameter bore of the retaining hole is dimensioned to be greater than an axial length of the press-fit section of the lock-hole structural member.
19. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 18 , wherein:
a tapered guide surface is formed at an edge of an inner circumference between the large-diameter bore and the small-diameter bore of the retaining hole.
20. The variable valve actuation apparatus of an internal combustion engine, as recited in claim 15 , wherein:
a thickness between an outer peripheral surface of the lock-hole structural section and an inner peripheral surface of the lock hole is dimensioned such that a radially inside part of the lock-hole structural member, opposed to a radially outside part of the lock-hole structural member along which the planar section is formed, is thicker than the radially outside part of the lock-hole structural member.