Effect of mesh phasing on the transmission efficiency and dynamic performance of wheel hub planetary gear sets

Abstract

Transmission efficiency and refinement of planetary wheel hub gearing system are key design attributes for heavy and offhighway vehicles. Reduction of power loss, directly leading to the development of new generation ECO-axles requires analysis of gear contacting conditions for lubricated conjunctions to determine frictional performance. This is also affected by gear dynamics, which is a prerequisite for assessment of noise, vibration and harshness performance. Therefore, a combined tribo-dynamic analysis is essential. There is a dearth of such holistic analysis, particularly for the case of wheel hub planetary systems. The paper presents such an analysis, which has not hitherto been reported in literature. The inexorable interplay of transmission efficiency and noise, vibration and harshness refinement is demonstrated. The key attributes of noise, vibration and harshness refinement and transmission efficiency can pose contrary requirements and near-optimal conditions can be highlighted by mesh phasing of gearing contacts, thus alleviating the need for more complex gear teeth modifications entailing prohibitive manufacturing costs.

Theoretical analysis of the vibration modes of the star herringbone gear transmission system

“…Thus, the problem of finding the natural frequency of the system amounts to solving the eigenvalues of the 18 variables in equation (12). There are 18 equations in equations (25) to (36).…”

“…Equations (27) to (31) are equivalent to equation (32). Equation (33) is obtained by substituting È i into equations (9) and (12). The solution of the system vibration mode is first obtained by solving eight frequencies, !…”

“…The following conclusions are first proved before proving this mode. Equations 7to (12) are equivalent when the left and right vibration modes of the herringbone teeth satisfy one of the following two conditions:…”

“…A parametric study was then performed to observe the effects of gear teeth crowning and tip relief with different levels of surface finishing upon the planetary hubs' power loss. They also utilized a holistic analysis method 12 for wheel hub planetary systems and studied the relationships between the transmission efficiency and the noise, vibration, and harshness refinement. Mo et al 13 established a dynamic model for a herringbone planetary transmission system based on the centralized parameters theory and Lagrange method and proposed a method for studying the multi-coupling error, which consists of the eccentric error, tooth profile error, stagger angle, and assembly error.…”

Effect of tooth profile modification on the durability of planetary hub gears

“…Their results indicated that increasing the number of planets makes the generated stresses more sensitive to the carrier pinhole positional error. Fatourehchi et al [14] developed a tribo-dynamic model to investigate the effect of mesh phasing due to manufacturing errors on the planetary system efficiency and NVH refinement. The model was capable of predicting the optimal level of combined efficiency and NVH performance of a planetary system.…”