THE SELECTION OF OPTIMAL REVERSIBLE TWO-SPEED PLANETARY GEAR TRAINS FOR MACHINE TOOL GEARBOXES

The application of multi-criteria optimization to two-carrier two-speed planetary gear trains is outlined in this paper. In order to determine the mathematical model of multi-criteria optimization variables, the objective functions and conditions must be determined first. Two-carrier two-speed planetary gear trains with brakes on coupled shafts are analyzed in this paper. The mathematical model covers the determination of the set of the Pareto optimal solutions as well as the method for selecting an optimal solution from this set. A numerical example is provided to illustrate the procedure in which the optimal two-speed planetary gear train is selected and defined by design parameters

Identification and proposed control of helicopter transmission noise at the source

Helicopter cabin interiors require noise treatment which is expensive and adds weight. The gears inside the main power transmission are major sources of cabin noise. Work conducted by the NASA Lewis Research Center in measuring cabin interior noise and in relating the noise spectrum to the gear vibration of the Army OH-58 helicopter is described. Flight test data indicate that the planetary gear train is a major source of cabin noise and that other low frequency sources are present that could dominate the cabin noise. Companion vibration measurements were made in a transmission test stand, revealing that the single largest contributor to the transmission vibration was the spiral bevel gear mesh. The current understanding of the nature and causes of gear and transmission noise is discussed. It is believed that the kinematical errors of the gear mesh have a strong influence on that noise. The completed NASA/Army sponsored research that applies to transmission noise reduction is summarized. The continuing research program is also reviewed

Multi-Objective Optimization of Planetary Gearbox with Adaptive Hybrid Particle Swarm Differential Evolution Algorithm

This paper considers the problem of constrained multi-objective non-linear optimization of planetary gearbox based on hybrid metaheuristic algorithm. Optimal design of planetary gear trains requires simultaneous minimization of multiple conflicting objectives, such as gearbox volume, center distance, contact ratio, power loss, etc. In this regard, the theoretical formulation and numerical procedure for the calculation of the planetary gearbox power efficiency has been developed. To successfully solve the stated constrained multi-objective optimization problem, in this paper a hybrid algorithm between particle swarm optimization and differential evolution algorithms has been proposed and applied to considered problem. Here, the mutation operators from the differential evolution algorithm have been incorporated into the velocity update equation of the particle swarm optimization algorithm, with the adaptive population spacing parameter employed to select the appropriate mutation operator for the current optimization condition. It has been shown that the proposed algorithm successfully obtains the solutions of the non-convex Pareto set, and reveals key insights in reducing the weight, improving efficiency and preventing premature failure of gears. Compared to other well-known algorithms, the numerical simulation results indicate that the proposed algorithm shows improved optimization performance in terms of the quality of the obtained Pareto solutions

Multi-Objective Optimization of Planetary Gearbox with Adaptive Hybrid Particle Swarm Differential Evolution Algorithm

This paper considers the problem of constrained multi-objective non-linear optimization of planetary gearbox based on hybrid metaheuristic algorithm. Optimal design of planetary gear trains requires simultaneous minimization of multiple conflicting objectives, such as gearbox volume, center distance, contact ratio, power loss, etc. In this regard, the theoretical formulation and numerical procedure for the calculation of the planetary gearbox power efficiency has been developed. To successfully solve the stated constrained multi-objective optimization problem, in this paper a hybrid algorithm between particle swarm optimization and differential evolution algorithms has been proposed and applied to considered problem. Here, the mutation operators from the differential evolution algorithm have been incorporated into the velocity update equation of the particle swarm optimization algorithm, with the adaptive population spacing parameter employed to select the appropriate mutation operator for the current optimization condition. It has been shown that the proposed algorithm successfully obtains the solutions of the non-convex Pareto set, and reveals key insights in reducing the weight, improving efficiency and preventing premature failure of gears. Compared to other well-known algorithms, the numerical simulation results indicate that the proposed algorithm shows improved optimization performance in terms of the quality of the obtained Pareto solutions

THE TORQUE METHOD USED FOR STUDYING COUPLED TWO-CARRIER PLANETARY GEAR TRAINS

Using the torque method, one can determine not only the speed ratios in complex compound planetary gear trains, but also the magnitude and direction of internal power flows and thus the efficiency. A brief description of the torque method is given in this paper. As an example, a two-carrier compound planetary gear train connected in series was studied. Some more specific and difficult cases of application of this clear and simple method are reviewed a planetary gear train with two degrees of freedom and a self-locking planetary gear train

Kinematic Operating Modes of Two-Speed Two-Carrier Planetary Gear Trains with Four External Shafts

Two-speed planetary gear trains with four external shafts, composed of two simple planetary gear trains, are considered in this paper. The labelling system of these trains is defined and all possible variants are determined. Planetary gear trains are divided into three different design groups, and characteristics of trains of each group are given. Possible power flows through the train at both gears for every group are described. An example of determining the function of transmission ratios of two-speed planetary gear trains by means of the torque method is shown. By research of kinematic schemes (design concepts) all train variants which can be created with an input and an output shaft on opposite sides of the train are identified, as well as those train variants where the aforementioned is not possible and their power input has to be placed between the brakes. All train variants where ideal torque ratios influence a change in the operating mode within the same gear are identified. A review of kinematic operating modes (reduction, multiplication, rotational direction of the output in relation to the input shaft) of all possible variants of the considered trains is given

Multi-objective optimisation for battery electric vehicle powertrain topologies

Electric vehicles are becoming more popular in the market. To be competitive, manufacturers need to produce vehicles with a low energy consumption, a good range and an acceptable driving performance. These are dependent on the choice of components and the topology in which they are used. In a conventional gasoline vehicle, the powertrain topology is constrained to a few well-understood layouts; these typically consist of a single engine driving one axle or both axles through a multi-ratio gearbox. With electric vehicles, there is more flexibility, and the design space is relatively unexplored. In this paper, we evaluate several different topologies as follows: a traditional topology using a single electric motor driving a single axle with a fixed gear ratio; a topology using separate motors for the front axle and the rear axle, each with its own fixed gear ratio; a topology using in-wheel motors on a single axle; a four-wheel-drive topology using in-wheel motors on both axes. Multi-objective optimisation techniques are used to find the optimal component sizing for a given requirement set and to investigate the trade-offs between the energy consumption, the powertrain cost and the acceleration performance. The paper concludes with a discussion of the relative merits of the different topologies and their applicability to real-world passenger cars

Power transmission systems: from traditional to magnetic gearboxes

L'abstract è presente nell'allegato / the abstract is in the attachmen