Design principle and modeling method of asymmetric involute internal helical gears

2018 ◽  
Vol 233 (1) ◽  
pp. 244-255 ◽  
Author(s):  
Mo Shuai ◽  
Ma Shuai ◽  
Jin Guoguang ◽  
Gong Jiabei ◽  
Zhang Ting ◽  
...  
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Planetary Gear ◽  
High Strength ◽  
Spur Gear ◽  
Low Noise ◽  
Gear Transmission ◽  
Contact Ratio ◽  
Transmission Systems ◽  
Helical Gears

In the field of mechanical engineering, involute helical gears are widely used. Compared with the involute spur gear, helical gears have a high bearing strength, more smooth transmission, less impact and less noise. The internal gear pairs have the features of large transmission ratio, low vibration, low noise and low wear and hence are widely used in planetary gear transmission systems. In order to meet the requirements of high strength, high speed of the modern gear transmission systems, a new type of asymmetric involute internal helical gears is designed based on conventional involute gears. This paper discusses the gear shaper cutter modeling for machining this new gear, analyzes the formation principle of asymmetric tooth profile and establishes a three-dimensional modeling by SolidWorks. Through MATLAB simulation, pressure angle, tooth number, coefficient of displacement and contact ratio of conventional and asymmetric gear are compared and analyzed. Using ANSYS, two types of gears are compared on strength in order to demonstrate superiority of asymmetric tooth and further study about the asymmetric internal helical gears.

Design of a non circular gear Mechanism with Twice Unequal Amplitude Transmission Ratio

2022 ◽  
pp. 1-13
Author(s):  
Jiangang Liu ◽  
Zhipeng Tong ◽  
Yu Gao-hong ◽  
Xiong Zhao ◽  
Haili Zhou
Keyword(s):  
High Speed ◽  
Planetary Gear ◽  
Tooth Profile ◽  
Gear Transmission ◽  
Gear Train ◽  
Transmission Ratio ◽  
High Speed Camera ◽  
Contact Ratio ◽  
Ratio Curve ◽  
Amplitude Transmission

Abstract This study proposes a new non–circular gear transmission mechanism with an involute–cycloid composite tooth profile to realize the twice unequal amplitude transmission (In a complete rotation cycle of gear transmission, instantaneous transmission ratio has twice fluctuations obvious with unequal amplitude) of non–circular gears. The twice unequal amplitude transmission ratio curve was designed based on Fourier and polynomial functions, the change law of the Fourier coefficient on the instantaneous transmission ratio(In non-circular gear transmission, the transmission ratio changes with time, and the transmission ratio of non-circular gear should be instantaneous transmission ratio) was analyzed, and the pressure angle and contact ratio of the involute–cycloid composite tooth profile was calculated. The involute–cycloid composite tooth profile non–circular gear was machined by WEDM technology, while its meshing experiment was performed using high-speed camera technology. The results demonstrate that the instantaneous transmission ratio curve value obtained via the high-speed camera experiment was consistent with the simulation value of virtual software. Furthermore, the involute–cycloid composite tooth profile was applied in the seedling pickup mechanism of non–circular gear planetary gear train. The possibility of the application of the involute–cycloid composite tooth profile in the seedling pickup mechanism was verified by comparing the consistency of the theoretical and simulated seedling picking trajectory.

Design of High Speed Gears, Low Load Gears for Minimizing Gear Whine Noise

2013 ◽  
Author(s):  
Rodney Glover
Keyword(s):  
High Speed ◽  
Sliding Friction ◽  
Transmission Error ◽  
Spur Gear ◽  
Low Noise ◽  
Spur Gears ◽  
Contact Ratio ◽  
Low Load ◽  
Gear Manufacturing ◽  
The Cost

The main purpose of the supercharger timing gears is to keep the rotors from contacting each other. They are often lightly loaded and designed for low noise. As timing gears, they have by definition a ratio of 1.0. Furthermore, the timing gears are presently spur gears due to the cost of assembling helical gears onto the rotor shafts without allowing timing errors between the rotors. The original timing gear designs were spur gears with contact ratios slightly above 2.0. A major NVH issue has been gear whine noise, because most applications are in luxury vehicles and are evaluated with the hood open and the engine at idle. In this operating condition, the background noise is very low and any tonal gear whine noise is audible. The first effort was to push the gear manufacturing quality to the limits of modern grinding capability. In order to further reduce gear whine noise, the designs have evolved to finer pitch gearing with a contact ratio over 3.0 to reduce transmission error. Micro-geometries were optimized for low transmission error (TE) at low load. OSU Gear Lab’s RMC and LDP became primary tools in optimizing the gear designs for minimum TE. An important factor when increasing the contact ratio is to not increase the sliding friction significantly to keep the fixed oil sump temperature from increasing too much and cause wear issues in operation. Typically, the new high contact ratio spur gear designs in production have reduced the gear whine levels by more than 6 dB and have had very few noise complaints.

Influence of the backlash generated by tooth accumulated wear on dynamic behavior of compound planetary gear set

2016 ◽  
Vol 231 (11) ◽  
pp. 2025-2041 ◽  
Author(s):  
Shijing Wu ◽  
Haibo Zhang ◽  
Xiaosun Wang ◽  
Zeming Peng ◽  
Kangkang Yang ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Dynamic Model ◽  
Dynamic Behavior ◽  
Planetary Gear ◽  
Tooth Wear ◽  
Transmission Error ◽  
Gear Transmission ◽  
Tooth Surface ◽  
Contact Ratio ◽  
The Impact

Backlash is a key internal excitation on the dynamic response of planetary gear transmission. After the gear transmission running for a long time under load torque, due to tooth wear accumulation, the backlash between the tooth surface of two mating gears increases, which results in a larger and irregular backlash. However, the increasing backlash generated by tooth accumulated wear is generally neglected in lots of dynamics analysis for epicyclic gear trains. In order to investigate the impact of backlash generated by tooth accumulated wear on dynamic behavior of compound planetary gear set, in this work, first a static tooth surface wear prediction model is incorporated with a dynamic iteration methodology to get the increasing backlash generated by tooth accumulated wear for one pair of mating teeth under the condition that contact ratio equals to one. Then in order to introduce the tooth accumulated wear into dynamic model of compound planetary gear set, the backlash excitation generated by tooth accumulated wear for each meshing pair in compound planetary gear set is given under the condition that contact ratio equals to one and does not equal to one. Last, in order to investigate the impact of the increasing backlash generated by tooth accumulated wear on dynamic response of compound planetary gear set, a nonlinear lumped-parameter dynamic model of compound planetary gear set is employed to describe the dynamic relationships of gear transmission under the internal excitations generated by worn profile, meshing stiffness, transmission error, and backlash. The results indicate that the introduction of the increasing backlash generated by tooth accumulated wear makes a significant influence on the bifurcation and chaotic characteristics, dynamic response in time domain, and load sharing behavior of compound planetary gear set.

Gear transmission error outside the normal path of contact due to corner and top contact

1999 ◽  
Vol 213 (4) ◽  
pp. 389-400 ◽  
Author(s):  
R. G. Munro ◽  
L Morrish ◽  
D Palmer
Keyword(s):  
Dynamic Test ◽  
Theoretical Models ◽  
Transmission Error ◽  
Helical Gear ◽  
Gear Transmission ◽  
The Novel ◽  
Transmission Systems ◽  
Helical Gears ◽  
Tooth Stiffness ◽  
Top Contact

This paper is devoted to a phenomenon known as corner contact, or contact outside the normal path of contact, which can occur in spur and helical gear transmission systems under certain conditions. In this case, a change in position of the driven gear with respect to its theoretical position takes place, thus inducing a transmission error referred to here as the transmission error outside the normal path of contact (TEo.p.c). The paper deals with spur gears only, but the results are directly applicable to helical gears. It systematizes previous knowledge on this subject, suggests some further developments of the theory and introduces the novel phenomenon of top contact. The theoretical results are compared with experimental measurements using a single flank tester and a back-to-back dynamic test rig for spur and helical gears, and they are in good agreement. Convenient approximate equations for calculation of TEo.p.c suggested here are important for analysis of experimental data collected in the form of Harris maps. This will make possible the calculation of tooth stiffness values needed for use in theoretical models for spur and helical gear transmission systems.

Three-Dimensional CFD Analysis of Meshing Losses in a Spur Gear Pair

2018 ◽  
Author(s):  
T. Fondelli ◽  
D. Massini ◽  
A. Andreini ◽  
B. Facchini ◽  
F. Leonardi
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Spur Gear ◽  
Computational Domain ◽  
Gear Pair ◽  
Transient Pressure ◽  
Numerical Effort ◽  
Free Environment

The reduction of fluid-dynamic losses in high speed gearing systems is nowadays increasing importance in the design of innovative aircraft propulsion systems, which are particularly focused on improving the propulsive efficiency. Main sources of fluid-dynamic losses in high speed gearing systems are windage losses, inertial losses resulting by impinging oil jets used for jet lubrication and the losses related to the compression and the subsequent expansion of the fluid trapped between gears teeth. The numerical study of the latter is particularly challenging since it faces high speed multiphase flows interacting with moving surfaces, but it paramount for improving knowledge of the fluid behavior in such regions. The current work aims to analyze trapping losses in a gear pair by means of three-dimensional CFD simulations. In order to reduce the numerical effort, an approach for restricting computational domain was defined, thus only a portion of the gear pair geometry was discretized. Transient calculations of a gear pair rotating in an oil-free environment were performed, in the context of conventional eddy viscosity models. Results were compared with experimental data from the open literature in terms of transient pressure within a tooth space, achieving a good agreement. Finally, a strategy for meshing losses calculation was developed and results as a function of rotational speed were discussed.

Low excitation spur gears with variable tip diameter

2021 ◽  
Vol 263 (5) ◽  
pp. 1275-1285
Author(s):  
Joshua Götz ◽  
Sebastian Sepp ◽  
Michael Otto ◽  
Karsten Stahl
Keyword(s):  
Transmission Error ◽  
Spur Gear ◽  
Low Noise ◽  
Spur Gears ◽  
Mesh Stiffness ◽  
Helical Gears ◽  
Axial Forces ◽  
Tooth Width ◽  
Drive Trains ◽  
Static Transmission Error

One important source of noise in drive trains are transmissions. In numerous applications, it is necessary to use helical instead of spur gear stages due to increased noise requirements. Besides a superior excitation behaviour, helical gears also show additional disadvantageous effects (e.g. axial forces and tilting moments), which have to be taken into account in the design process. Thus, a low noise spur gear stage could simplify design and meet the requirements of modern mechanical drive trains. The authors explore the possibility of combining the low noise properties of helical gears with the advantageous mechanical properties of spur gears by using spur gears with variable tip diameter along the tooth width. This allows the adjustment of the total length of active lines of action at the beginning and end of contact and acts as a mesh stiffness modification. For this reason, several spur gear designs are experimentally investigated and compared with regard to their excitation behaviour. The experiments are performed on a back-to-back test rig and include quasi-static transmission error measurements under load as well as dynamic torsional vibration measurements. The results show a significant improvement of the excitation behaviour for spur gears with variable tip diameter.

scholarly journals Lubricated Loaded Tooth Contact Analysis and Non-Newtonian Thermoelastohydrodynamics of High-Performance Spur Gear Transmission Systems

Lubricants ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 20 ◽  
Author(s):  
Gajarajan Sivayogan ◽  
Ramin Rahmani ◽  
Homer Rahnejat
Keyword(s):  
High Speed ◽  
High Performance ◽  
Spur Gear ◽  
Contact Analysis ◽  
Operating Conditions ◽  
Tooth Contact Analysis ◽  
Transmission Systems ◽  
Tooth Contact ◽  
Contact Kinematics ◽  
Loaded Tooth Contact Analysis

Energy efficiency and functional reliability are the two key requirements in the design of high-performance transmissions. Therefore, a representative analysis replicating real operating conditions is essential. This paper presents the thermoelastohydrodynamic lubrication (TEHL) of meshing spur gear teeth of high-performance racing transmission systems, where high generated contact pressures and lubricant shear lead to non-Newtonian traction. The determination of the input contact geometry of meshing pairs as well as contact kinematics are essential steps for representative TEHL. These are incorporated in the current analysis through the use of Lubricated Loaded Tooth Contact Analysis (LLTCA), which is far more realistic than the traditional Tooth Contact Analysis (TCA). In addition, the effects of lubricant and flash surface temperature rise of contacting pairs, leading to the thermal thinning of lubricant, are taken into account using a thermal network model. Furthermore, high-speed contact kinematics lead to shear thinning of the lubricant and reduce the film thickness under non-Newtonian traction. This comprehensive approach based on established TEHL analysis, particularly including the effect of LLTCA on the TEHL of spur gears, has not hitherto been reported in literature.

Application of Non-Circular Planetary Gear Mechanism in the Gear Pump

2012 ◽  
Vol 591-593 ◽  
pp. 2139-2142
Author(s):  
Hong Ding
Keyword(s):  
Pressure Fluctuations ◽  
Hydraulic Drive ◽  
Planetary Gear ◽  
Low Noise ◽  
Gear Transmission ◽  
Gear Pump ◽  
Flow Ripple ◽  
Large Pressure ◽  
Gear Pumps ◽  
Gear Mechanism

Gear pump is the most commonly used hydraulic component in hydraulic drive system.Volumetric efficiency of the traditional gear pump is low, big flow ripple causes large pressure fluctuations, makes pipes and valves vibration, noisy. The imbalance pressure on gear pump’s gears, shafts and bearings and the large radial load limits its pressure increased. Planetary gear transmission compared with ordinary gear transmission, it has many unique advantages. So the writer on the basis of the combination of proposed non-circular planetary gear pumps and gear pump works discussed the structure and working principle of the pump. The non-circular planetary gear pump with many advantages such as big flow, uniform flow, low noise and so on. It can be widely used in various hydraulic transmission systems.

scholarly journals Numerical Simulation of Gear Heat Distribution in Meshing Process Based on Thermal-structural Coupling

2019 ◽  
Vol 2 (2) ◽  
Author(s):  
Peixiang Xu
Keyword(s):  
Heat Conduction ◽  
High Speed ◽  
Element Model ◽  
Simulation Method ◽  
Spur Gear ◽  
Gear Transmission ◽  
Heat Distribution ◽  
Heavy Load ◽  
Structural Coupling ◽  
Meshing Process

The thermal balance state of high-speed and heavy-load gear transmission system has an important influence on the performance and failure of gear transmission and the design of gear lubrication system. Excessive surface temperature of gear teeth is the main cause of gluing failure of gear contact surface. To investigate the gear heat distribution in meshing process and discuss the effect of thermal conduction on heat distribution,a finite element model of spur gear is presented in the paper which can represent general involute spur gears. And a simulation approach is use to calculate gear heat distribution in meshing process. By comparing with theoretical calculation, the correctness of the simulation method is verified, and the heat distribution of spur gear under the condition of heat conduction is further analyzed. The difference between the calculation results with heat conduction and without heat conduction is compared. The research has certain reference significance for dry gear hobbing and the same type of thermal-structural coupling analysis.

Variable-Grain Optimization Design of High-Speed Transmission Helical Gear

2011 ◽  
Vol 346 ◽  
pp. 179-183
Author(s):  
Fu Qiang Zhao ◽  
Tie Wang ◽  
Rui Liang Zhang ◽  
Yu Juan Li ◽  
Jun Shen
Keyword(s):  
High Speed ◽  
Optimization Design ◽  
Optimal Solution ◽  
Objective Evaluation ◽  
Friction Torque ◽  
Evaluation Index System ◽  
Coarse Grained ◽  
Contact Ratio ◽  
Helical Gears ◽  
Multi Objective

A variable-grain strategy is proposed to solve the complicated problem of optimization design on high-speed transmission helical gears with multiple objectives and restrictions. Based on the theory of gear meshing noise and the superiority criteria, a multi-objective evaluation index system is brought forward which gives consideration to the increase of the contact ratio and the decrease of the noise generated by the slide ratio of the tooth flank meshing and the mutation of friction torque, and then the variable-grain multi-objective optimization models of high-speed helical gears are established. The coarse-grained model is utilized in the early design to efficiently determine the direction to the optimal solution. Then the grain is refined and the fine-grained model can be utilized to acquire the optimal result.

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