A pinion starter drive for an internal combustion engine is provided. The pinion starter drive includes a drive pinion and a starter gear. At least one tooth of the drive pinion has a drive actual profile, and at least one tooth of the starter gear has a starter actual profile. A sum of at least one discrete value of a deviation of the drive actual profile from a drive target profile in the drive pinion tooth root region and at least one discrete value of a deviation of the starter actual profile from a starter target profile in the starter gear tooth tip region is less than 0. A method of manufacture of a pinion starter drive includes selecting a drive pinion and a starter gear from a plurality of gears having a deviation sum less than zero.

A synchronous drive sprocket includes a generally annular body and a central axis extending through the generally annular body. The central axis defines circumferential, axial, and radial directions. The generally annular body has a peripheral edge and a plurality of recesses extending radially inward from the peripheral edge. The plurality of recesses define a plurality of circumferentially spaced teeth configured to receive mating teeth of a synchronous drive belt. Each tooth has an upper bearing surface and a notch extending radially inward from the peripheral edge of the tooth. Each notch is axially positioned such that the plurality of notches align with each other to collectively define a groove within the plurality of teeth. The groove extends circumferentially around at least a majority of the generally annular body and having a substantially continuous profile.

An object of the present invention is to provide a sprocket that mitigates the impact of tension fluctuations resulting from load torque changes, suppresses noise and vibration, ensures stable chain behavior, prevents sprocket durability loss and the generation of harmonics during rotation, along with a chain drive system. Tooth roots between adjacent teeth of the sprocket include those with a radial deviation from a root circle of a standard tooth profile, set within a predetermined numerical range corresponding to a tooth pitch. A phase variation pattern is created by changing a root radius in accordance with an angular position. The phase variation pattern has a waveform with an amplitude varied within a range of ( 1/7)Amax, where Amax represents a maximum amplitude. The chain drive system includes a plurality of sprockets and a chain passed over the sprockets, at least one of them being the above-described sprocket.

The present disclosure relates to a process for machining a gear workpiece (100) comprising a plurality of tooth spaces (6), each of which is defined by two tooth flanks (5.1, 5.2); in said process, a gear tooth-forming tool (1) is used in order to provide at least one subset of all the tooth flanks (5.1, 5.2) with a non-periodically distributed modification of the flank geometry.

An object of the present invention is to provide a sprocket that mitigates the impact of tension fluctuations resulting from load torque changes, suppresses noise and vibration, ensures stable chain behavior, prevents sprocket durability loss and the generation of harmonics during rotation, along with a chain drive system. Tooth roots between adjacent teeth of the sprocket include those with a radial deviation from a root circle of a standard tooth profile, set within a predetermined numerical range corresponding to a tooth pitch. A phase variation pattern is created by changing a root radius in accordance with an angular position. The phase variation pattern has a waveform with an amplitude varied within a range of (1/7)Amax, where Amax represents a maximum amplitude. The chain drive system includes a plurality of sprockets and a chain passed over the sprockets, at least one of them being the above-described sprocket.

A synchronous drive sprocket includes a generally annular body and a central axis extending through the generally annular body. The central axis defines circumferential, axial, and radial directions. The generally annular body has a peripheral edge and a plurality of recesses extending radially inward from the peripheral edge. The plurality of recesses define a plurality of circumferentially spaced teeth configured to receive mating teeth of a synchronous drive belt. Each tooth has an upper bearing surface and a notch extending radially inward from the peripheral edge of the tooth. Each notch is axially positioned such that the plurality of notches align with each other to collectively define a groove within the plurality of teeth. The groove extends circumferentially around at least a majority of the generally annular body and having a substantially continuous profile.

A pinion starter drive for an internal combustion engine is provided. The pinion starter drive includes a drive pinion and a starter gear. At least one tooth of the drive pinion has a drive actual profile, and at least one tooth of the starter gear has a starter actual profile. A sum of at least one discrete value of a deviation of the drive actual profile from a drive target profile in the drive pinion tooth root region and at least one discrete value of a deviation of the starter actual profile from a starter target profile in the starter gear tooth tip region is less than 0. A method of manufacture of a pinion starter drive includes selecting a drive pinion and a starter gear from a plurality of gears having a deviation sum less than zero.

A gear of a gear device includes a plurality of teeth having tooth surfaces. The tooth surfaces are shaped such that contact length ratios of three or more of the teeth are outside a predetermined range centered on an average value of the contact length ratios of all of the teeth, where the contact length ratio is obtained by dividing a contact length of a tooth contact face by a diagonal length of a plane of action.