Patent ID: 8544432

Claim:
A variable valve actuation apparatus of an internal combustion engine configured to vary an operating characteristic of an engine valve permanently biased in a direction closing of the engine valve by a valve spring, by changing an angular position of a second member relative to a first member, comprising: an electric motor in which a state of rotation of the electric motor is controlled responsively to a control signal; an eccentric rotation member configured to rotate eccentrically with respect to a center of rotation of an output shaft of the electric motor by torque transmitted from the electric motor; an inner peripheral meshing member integrally connected to one of the first and second members and having an internal toothed portion formed on its inner periphery; a plurality of rolling elements rotatably installed on an outer peripheral surface of the eccentric rotation member and circumferentially arranged substantially at regular intervals, and configured such that a meshing point of the plurality of rolling elements with the inner peripheral meshing member circumferentially shifts by eccentric rotary motion of the eccentric rotation member; and a cage integrally connected to the other member of the first and second members and having a plurality of lugs for circumferentially partitioning the respective rolling elements, while permitting a radial displacement of each of the rolling elements, wherein, depending on a dimension of a clearance space between the outer peripheral surface of the eccentric rotation member and the inner peripheral meshing member, either one of a plurality of rolling-element sets, each having a different rolling-element outside diameter, is selected, and then the rolling elements of the selected rolling-element set are installed on the outer peripheral surface of the eccentric rotation member, and wherein either one of a radial clearance C 1 between an outer peripheral surface of a specified one of the rolling elements, interleaved and deeply engaged in a space defined between the outer e periheral surface of the eccentric rotation member and an inner face of the internal toothed portion of the inner peripheral meshing member, positioned in an eccentric direction of the eccentric rotation member whose geometric center is displaced from the center of rotation of the motor output shaft and the inner face of the internal toothed portion of the inner peripheral meshing member and a radial clearance C 2 between the outer peripheral surface of the specified one of the rolling elements, interleaved and deeply engaged in the space defined between the outer peripheral surface of the eccentric rotation member and the inner face of the internal toothed portion of the inner peripheral meshing member, positioned in the eccentric direction of the eccentric rotation member and the outer peripheral surface of the eccentric rotation member, is set to a given clearance, ranging from 10 μm to 40 μm.