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Tonal noise due to gears is one of the fundamental noise problems in a gearbox. Gear tooth deflections generate dynamic forces that lead to unwanted load fluctuations, thus noise. Different factors that are considered to control this noise, some to mention like proper gear macro design, microgeometry corrections, and housing compliance. However, identifying the appropriate variable as a measure of contribution to the overall response helps in getting more accurate remedial solutions. Some outputs to track are different harmonic components of TE, temperature effects, components of forces, rim compliance and friction. For evaluation, usually, the amplitudes of individual harmonics of transmission error are related to the respective orders of the noise levels assuming it as one of the primary excitation parameters of gear noise.

Simple planetary gears are widely used in automobile industry due to their compact design and high power density. A simple planetary gear set consists of a Sun gear, Ring gear, Planets and Carrier which houses planet gears. Mounting of planet pinions on carrier is through pins which is supported on needle roller bearings. A process called staking is used to assemble the pinion pins on to the carrier. Pinion pins have a staking region which after assembly expands outward into staking groove on the carrier to prevent axial movement of the pins. Design of the groove plays a vital role for the fixation of planet pins and robustness a carrier. Planetary carrier staking grooves are designed to meet pinion pin retention and strength targets.

Planetary gear set is one of the most commonly used gear systems in automotive industry as they cater to high power density requirements. A simple planetary gear set consists of a sun gear, ring gear, planets and carrier which houses planet gears. Efficiency of a transmission is dependent upon performance of gear sets involved in power transfer to a great extent. Structural rigidity of a planetary carrier is critical in a planetary gear set as its deflection may alter the load distribution of gears in mesh causing durability and noise issues. Limited studies exist based on geometrical parameters of a carrier which would help a designer in selecting the dimensions at an early stage. In this study, an end to end automated FEA process based on DOE and optimization in Isight is developed. The method incorporates a workflow allowing for an update of carrier geometry, FE model setup, analysis job submission and post-processing of results.

In an automotive transmission system, gear mesh misalignment implies the shift in the position of the meshing surfaces. Misalignment at the mesh results in non-uniform load distribution leading to gear failure, increased noise and thus affects the transmission performance. In general, misalignment along the line of action (MLOA) of 0-5 mrad is common in the gear meshes of automotive transmissions. Major factors contributing to mesh misalignment are deflections of various elastic components in the transmission like shaft, gear web, bearing, housing etc. Contribution from other factors include clearance between the components, temperature gradient and manufacturing process limitations. Different approaches for compensating gear mesh misalignment involves control over the above factors at design and manufacturing stages. This paper focuses on three different approaches for compensating MLOA in the design stage.

Scuffing is an instantaneous failure which occurs when the meshed gear flanks undergo adhesive wear under extreme operating temperatures at medium- or high-speed conditions. It is one of the common failures in transmission gears, which tend to operate under long-duty cycle hours. The tip and the root regions often experience higher contact pressures because of the loading and surface curvature. These higher pressures, coupled with higher sliding velocities and heat generation, make the tip and root regions in the gear susceptible to scuffing. Gear geometry, material composition and lubricant properties influence scuffing. A balanced gear tooth design with lower sliding velocities is often chosen as an approach to avoid scuffing. However, in the current scenarios of transmissions with high power density requirements, achieving a balanced gear tooth design is rare. Lubricants with higher viscosity avoid scuffing, but have adverse effects on the transmission efficiency.