Differential Gear Research Articles

Study on the traction potential and manoeuvrability of wheel-individually driven commercial vehicle concepts

Due to trends such as automation and new drives in commercial vehicle engineering, research is being carried out on drive concepts with individual wheel drives. In the off-road sector, these concepts offer the potential to exceed the manoeuvrability and traction performance of conventional drive trains. Mechanical drive trains are limited in this respect due to their nature (differential gears, etc.). The publication compares a wheel-individually driven commercial vehicle with the wheel formula 6 × 6 with a similar reference vehicle with mechanical drive train in a virtual environment. As a result, the wheel-individually driven concept combines the gradeability of a mechanical drive train with closed differentials with the manoeuvrability of a mechanical drive train with open differentials. The operation strategy for variable torque distribution required for the wheel-individual concept is part of the publication.

ТЕОРЕТИЧЕСКОЕ ОБОСНОВАНИЕ РАЗВОРОТА НА МЕСТЕ ГУСЕНИЧНОГО ТРАКТОРА С ДИФФЕРЕНЦИАЛЬНЫМ МЕХАНИЗМОМ ПОВОРОТА ПРИ НЕЙТРАЛИ В КОРОБКЕ ПЕРЕДАЧ

The paper is dedicated to the operation investigation of the two-flow hydro-mechanical transmission of industrial tractor consisting of a hydro-transformer and a planetary gearbox in a basic flow of power ensuring rectilinear motion, and a hydro-volume gear in the second flow ensuring rotation speed difference of caterpillar tracks, and, accordingly a tractor turn. A turn in place of a track machine is ensured with the differential variable-ratio gear of turning on the basis of a hydro-volume gear. 
 The investigation method – simulation. In the course of investigations there was created a simulator describing adequately a turn in place of a caterpillar with a differential turning gear based on a hydro-volume gear. 
 The solution is carried out in the ALTAIR EMBED programming environment. There are made diagrams of the process of going into a turn in place and a steady-state turn in place. At that there was accepted an assumption that the resistance to rotation of the right and left driving wheels of a tractor is equal as it is impossible to suppose that under caterpillars there can be soil with properties different considerably as the rotation takes place in the same place. 
 The analysis has shown that the left and right sides balance each other at the turn on homogeneous soil. The application of a braking device in a general link of the differential variable-ratio in the turning mechanism is optional. The results can be used for example for the further scientific work in the field of quantitative assessment of skidding during tractor rotation round a gravity center having a substantial influence upon controlled kinematic parameters of a tracked vehicle – an angular velocity of turning in place.

Optimization of flywheel for starter-generator based on the differential electric drive

The article discusses a variant of the implementation of a starter-generator based on a differential planetary gear, in which a flywheel is integrated. The method of its control and the algorithm of operation as a starter-generator are described. The main task in this article is to develop a flywheel and optimize its weight and size parameters, taking into account the requirements for the design of starting equipment for the MTZ-80 tractor. The technical parameters of the D-240 diesel engine and the viscosity-temperature characteristic of the M-8Gz engine oil are given. The calculation of the kinetic energy that must be accumulated in the flywheel to start an internal combustion engine in severe climatic conditions is carried out. The weight and size parameters of the flywheel have been calculated. A mathematical model of a starter with a flywheel is built for showing the processes of starting an internal combustion engine in various conditions and allowing to assess the adequacy of mathematical calculations and conduct a comparative analysis.

Study on manufacturing of special-shaped ends blank for cross wedge rolling without stub bar

Prefabricating blank ends into special shape is the most effective and commonly used method to eliminate end-face cavities for realizing cross-wedge rolling (CWR) without stub bar. A hot rotary shearing forming method based on metal-plastic forming together with its implementing mechanism for the manufacturing of special-shaped ends blank was proposed in this paper. The hot rotary shearing forming method was firstly investigated by finite element simulation, and the forming process of the special-shaped end with the movement of the shear blade is analyzed. Then the implementing mechanism characterized by the combination of a differential elliptical gear train with conjugate cam was designed. To obtain the structural parameters that can make the shear blade move as designed, kinematics model of the mechanism was deduced by analyzing its working principle. Based on the model, a computer-aided analysis program for the hot rotary shearing mechanism, using MATLAB, is developed. Finally, one application example was conducted. The experimental results revealed that the dimension of the special-shaped end blank obtained by this method was close to the designed dimension. The research result verifies the correctness of the kinematic model and the feasibility of the forming method.

Influence of Shot Peening on Surface Characteristics of Case Hardened SAE9310 Gear Material

The shot peening is the cold working process by which the compressive residual stresses are induced in the component, and that increases surface hardness, which can be helpful to avoid the fatigue failure of the component. Shot peening process is using to improve the fatigue life of the automobile and aerospace components. Effectiveness of the shot peening in surface characteristics can be measured by the Almen Intensity, Surface hardness and Surface roughness. The impact of shot peening on case-hardened differential bevel gear is defined in this study. In the shot peening process, the surface of the gear rammed by the small hardened cut wire shots with high velocity and overlapping indentations are created on the gear surface. Hence, thecharacteristics of surface of the gear can be greatly improved by shot peening. For bevel gears, bending fatigue crack is the major failure mode. This study is discussed to enhance the mechanical and surface properties of SAE9310 bevel gear by using the shot peening process. The optimization of shot peening process is done by including multi-performance characteristics i.e. Intensity, Surface hardness and surface roughness of the bevel gear. The analysis includes air pressure, nozzle distance, shot flow rate, exposure time as process parameters. The main objective of this study to decide the optimized shot peening process parameters for required performance characteristics and most influencing factors on surface layer characteristics. The experiments have been conducted using Taguchi’s L9 orthogonal array design techniques.

Dynamic Modeling and Vibration Characteristics Analysis of Transmission Process for Dual-Motor Coupling Drive System

The dual-motor coupling drive system (DCDS), which is widely used in electric vehicles, has attracted increasing attention due to its high transmission efficiency and economical fuel consumption. Current research has mainly focused on the control scheme of dual motors and has ignored the dynamic characteristics of the asymmetrical transmission structure. This paper presents an investigation of a dynamic model and an analysis method of the transmission process for the DCDS. The entire dynamic model of the DCDS was established by considering the planetary gear, differential bevel gear, and drive shaft with the transfer matrix method (TMM). Then, a detailed theoretical analysis was developed to study the influence of meshing stiffness and excitation source on the dynamic characteristics. Finally, the DCDS experimental platform was utilized to validate the effectiveness of the proposed dynamic model. For susceptibility to low-frequency vibrations, the first four natural frequencies and vibration modes of the DCDS were analyzed through the processing and analysis of acceleration signals. The experimental dynamic responses were generally consistent with the numerically computed results, which demonstrates the effectiveness of the proposed dynamic model with TMM. Furthermore, the proposed dynamic analysis method may be helpful for developing effective control algorithms to suppress vibrations and achieving highly smooth motions for electric vehicles.

Modification and analysis on fatigue study in universal joint of an automobile vehicle

The main task, especially targets at checking out the standard joint at exceptional operating angles and specific materials in order that the time to failure of the accepted joint may be reduced to a degree. The strength generated inside the engine due to the fact the stop result of combustion of gasoline is converted to wheels through the transmission gadget inside the car. This machine in particular encompasses device container, propeller shafts, tremendous joints and differential gears. The stress shaft imparts torque from the engine (Kamal et al., 2011). The screw ups that added on to the energy shaft is especially because of vibration strain, fatigue, bending pressure or maybe the misalignment of the driveshaft. a majority of those defects especially because of the overloading or even repeated extra time use (Hummel and Chassapis 1998). The main result of all these are the pre-mature failure of the drive shaft at the operation times. For almost all the cases, the failure occurs at the area around the universal joints, as the angle difference and the velocity variations occurs in that area.

Effect of Heat Treatment on Toughness and Fatigue Behavior Strength of Steel CK45

The function of the axle drive shaft is to transfer the engine torque from the gearbox or differential gear to the wheels. It must also endure for all dynamic loads resulted from variations in angle or length during driving from contact the vehicle tire with road. Most problems with the axle drive shaft manifest themselves in the form of knocking noises when driving around tight corners, accelerating, or when the suspension is being compressed and extended where the drive shaft becomes weakened and more subject to stress failure due to dynamic torsion, tensile, shear, and compression. This work consists of effect of heat treatment type applied to the steels CK45 on the resulted behavior of the fatigue and toughness and study of these heat treatments on the microstructure and micro-hardness across the specimens depth. Where this heat treatable alloy usually used in drive-shafts in vehicles which exposed to a dynamic loads and the goal is to investigate the best relation between heat treatment and the service conditions. However, microstructural characterization and microhardness measurements revealed that the shaft belongs to medium carbon steel contains ferrite and pearlite, measuring the toughness for four heat treatments to obtain the best case and measuring the fatigue life of quenching case has better life compared to other cases. The oil quenching gives best toughness value of 30 Kj/m2 and the worst value obtained for as received one giving 7 Kj/m2 and the maximum fatigue life under stress of 375 MPa belonged to oil quenching treatment and it was 75000 cycles to failure while the as-received alloy reported 2000 cycles at failure. The S-N curve of the four cases based on Basquin formula with correlation factor (R2) close to one. And the water quenching steel alloy recorded higher curve component to other cases.

The effect of planetary gear/star gear on the transmission efficiency of closed differential double helical gear train

The research of transmission efficiency is of great significance for reducing energy consumption and improving the performance of the device. Researchers have done a lot of work on the calculation of transmission efficiency. However, in the present research work, the quantity of planetary gear/star gear is usually not considered and only a planetary gear/star gear is adopted in the gear transmission efficiency. In practice, in order to increase the stiffness and load capacity of gear train, a plurality of planetary gear/star gears is adopted. The closed differential double helical gear train has been widely used in many fields, such as the main reducer of aircraft engine, lifting mechanism, and the power transmission system of marine ships. Therefore, in this paper, the closed differential double helical gear train is taken as the research object and the effect of planetary gear/star gear on the transmission efficiency is analyzed. Firstly, according to the structure of closed differential double helical gear train, related kinematic analysis is given. Secondly, a graph representation is used to characterize the closed differential double helical gear train. According to the theory of virtual power, the power flow direction of closed differential double helical gear train is determined and the value of split power is obtained. According to the input and output values described in graph representation of closed differential double helical gear train, the formula of transmission efficiency is derived and the effects of planetary gear/star gear on transmission efficiency are analyzed. Finally, an illustrative example shows that compared with the theoretical value, the difference considering the effect of planetary gear/star gear on the transmission efficiency of closed differential double helical gear train is two percentage points.

A Differential Electric Drive for Electric Vehicles with an Independent Power Supply

In this paper, we consider the effectiveness of using a twin-engine electric drive from the point of view of acceleration dynamics and energy efficiency. To take into account the acceleration time of the electric vehicle and the energy consumed during the transition process, evaluation criterion G was introduced. By a “twin-engine system” is meant a system of electric drive of a wheel pair through two independent mechanical channels: the first is a “high-torque” channel implemented through the use of a gearbox with a high gear ratio, and the second is a “high-speed” channel implemented through the use of a gearbox with a low gear ratio or without a gearbox at all. The summation of power is carried out by means of a differential gear. We performed mathematical modeling of the operation of such a system. Asynchronous electric drives with vector control, which operate in the torque source mode, are used as electromechanical converters. An algorithm and a system for distributing torque between two channels are developed. The gear ratio of the “high-torque” channel gearbox was optimized by the criterion of G minimum. A quantitative comparison and analysis of transient acceleration processes in single- and twin-engine systems were performed based on the example of a 30-kW electric race car. It is concluded that it is effective to use a twin engine system for specific types of electric vehicles.

Dynamic Characteristics of Encased Differential Gear Train with Journal Bearing

Taking the marine encased differential gear train as an example, the relationship between the journal bearing parameters and the meshing force of the transmission system is analyzed. In this paper, the dynamic model of the encased differential gear train with journal bearing is established considering the factors of time-varying meshing stiffness and comprehensive transmission error. In this dynamic model, four stiffnesses and four damping coefficients are applied to characterize the asymmetry and interaction of the oil film stiffness and damping of planet bearing. The system responses are calculated by the Fourier series numerical algorithm. The results show that the introduction of journal bearing in encased differential gear train can contribute to gearbox vibration reduction. Moreover, the planet bearing parameters (e.g., clearance-to-radius ratio and eccentricity ratio) of the differential stage affect the meshing forces of both the differential and encased stages. In addition, the influence of the planet bearing parameters of the encased stage on the meshing force of the encased stage is more obvious than that of the differential stage. This work may develop a theoretical analysis framework for the design and manufacture of marine transmission systems in the future.

Topology Optimization of Spiral Bevel Gear for Differential

The Spiral Bevel gear used in differential should be enough stiff to resist the vibrations and stresses encountered during its operation. The gear must also have sufficient strength to bear the bending stresses occurring in the differential assembly in its course of operation. This research is typically focused in designing a differential gear with least weight and minimal stresses. The model of the gear is designed in the Solidworks version 2015 while its analysis is carried in ANSYS 14.5. The number of parameters and levels involved in designing are more; the number of probable models is too many. To choose the optimal parameter among the list of choices, TAGUCHI method along with Finite Element Analysis (FEA) is used. By application of TAGUCHI method, not only the time required to design all the probable models is reduced, but also the time required to analyze all the models is cut down. Orthogonal Array has been incorporated to change the parameters necessary for reducing the weight of the gear. To get the best possible model of gear, FEA is then performed on the designed models. This process not only saves production time, but also prevents material wastage and production cost.

Mechanical and Empirical Parameter Design on a Multi-wound Differential Pulley Winch for a Wall-Climbing Robot

This paper proposes a novel multi-wound differential pulley winch (MWDPW) component for assisting the ascending/descending operations of a wall climbing robot. The robotic platform enabling rope access in dangerous environments (ROPE RIDE) climbs vertical walls using a rope and embedded winch. The original winch installed on the ROPE RIDE was a single wound winch, which had problems such as rope slip, velocity ripple during descending motion, resulting the bad cleaning performance and unstable motion on the wall. These problems are mainly due to the concentration of traction force on the rope because a small portion of the winch pulley holds the entire weight of the robot. Therefore, we have developed a new winch, MWDPW, by using multi-wound differential traction pulley and pressure rollers to solve the traction force concentration problem by distributing the traction force along the entire wrapping angle. Compared to other multi-wound winches, the MWDPW has the special feature of a differential gear and pressure roller to distribute the traction force and minimize the rope slip. The tension of the MWDPW is analyzed using the basic capstan equation, and empirical results to minimize the rope slip are presented by varying design parameters such as the winding method and presence of the pressure rollers. We expect the proposed mechanism to improve the safety of a wall-climbing robot for wall-cleaning operations.

ДИНАМІЧНА МОДЕЛЬ ПРИСТРОЮ ДЛЯ КЕРУВАННЯ ЗМІНАМИ ШВИДКОСТІ ІЗ ЗУБЧАСТИМ ДИФЕРЕНЦІАЛОМ І ЗАМКНУТОЮ ГІДРОСИСТЕМОЮ ЧЕРЕЗ ВОДИЛО

The purpose of the study is to build a dynamic model of the speed change device including a differential gear and a closed-loop hydraulic system, where the driving link is a sun gear driven by an electric motor, while a closed-loop hydraulic system is connected to the carrier and can change its speed due to changes in system’s throughput, the ability of the fluid to move across the hydraulic system, so that the necessary law of motion on the driven link - the ring gear can be obtained. The analysis of recent publications has revealed that the research of new speed control devices with a differential gear and a closed-loop hydraulic system through the carrier pays much attention to their structure, principle of operation, and the change in speed, that has been confirmed by analytical and graphical dependences. In addition, energy efficiency and self-braking of such devices has been studied by determining the coefficient of performance efficiency. The dynamics of such devices is waiting to be resolved. It will allow us to develop methods to reduce the impact of dynamic loads on the mechanical drives of machines when changing speed. The article proposes a mathematical model of the movement of a mechanical system for new devices for changing the speed using a differential gear with a closed-loop hydraulic system through the carrier. For this purpose, the equation of dynamics by the Lagrange method of the second kind has been used and the equation of kinetic energy of the system has been formed. Since there is a relationship between the speeds of all links in the differential gear, the expression for the kinetic energy of the system has been described by the speed of the driving and driven links, i.e., by the speed of the sun gear and the ring gear. The result of solving the Lagrange equation in partial derivatives is a system of two differential equations with unknown derivatives of the velocities of the sun gear and the ring gear. The obtained results are the basis for further computer simulation and quantitative analysis to assess the performance of such devices and select the necessary closed-loop hydraulic system to control speed changes. Based on the dynamic model, it is possible to compose and solve the equations of dynamics for typical cases of changes in the torque resistance: long-term shock, short-term shock and significant overload, up to the stop of the machine.

Dynamic research of elementary differential gear with elastic links

Many research works are devoted for study of static and dynamic parameters of planetary gears of various designs. A number of dynamic problems can be solve accurately enough without taking into account the elasticity of loaded elements. In calculations of mining machines transmissions dynamic processes must be considered gear flexibility as is much more than flexibility of large diameter and small length shafts. In this article are considered possibilities and features of research of dynamic phenomena that take a place in planetary mechanisms of mining machine transmissions. For this purpose planetary mechanisms are presented as elastic mechanical systems. For research the dynamic model of elementary differential mechanism with taking into account the link elasticity is used. For this purpose the differential gear presented as equivalent planetary row with inertialess planetary carrier. Main links of such mechanism have inertia moments determined by known formulas. The equivalent dynamic model of elementary differential gear is presented as three-mass branched system. Moments of elasticity, occurring in mechanical constraints of system, are determined. Equations of movement for each of the masses give the linear homogeneous differential equation system or free oscillations equation system of mechanism. This system is representable as linear algebraic equation system. Particular solutions of inhomogeneous differential equation system are of practical interest, as they permit to make the analysis of the effect of external loads, acting on the mechanism. Operator solution method application will give particular solutions of linear inhomogeneous differential equations. Received systems will allow solving many dynamic tasks of elastic mechanical systems: character change and maximum values of mechanism links dynamic loads, periods and frequencies of oscillations, conditions of the resonant state of the mechanical system.

Analysis and Research of Friction and Wear Mechanism Based on Different Types of Dynamic Load

For sliding friction pairs formed by differential gears and gaskets, it is necessary to study the friction performance under the coupling of multiple working conditions (impact, vibration and alternating load). For example, it is of great significance to study the performance of sliding friction pair in the rear axle differential of truck and the friction and wear performance of the internal parts of aircraft and ships under the coupling condition of multiple working conditions, so as to obtain longer service life and excellent performance by improving the friction performance. The ball-disc pairs were experimentally built to simulate the friction and wear mechanism of materials under different types of dynamic loads. Under the condition of non-polluting white oil lubrication, increased the contact ratio of the pair, and made the pair reach the experimental state of no dynamic pressure lubrication, selected different types of dynamic loads (step load, damped harmonic excitation load (DHE), Short-term high load) loading method. During the experiment, force sensors and online visual ferromagnetic sensors were used to monitor friction and wear rate signals in real time, and TR200 profilometer and scanning electron microscope were used to observe and study friction characteristics. The results show that a reasonable step load can improve the friction and wear state of the ball-disk pair during the running-in period and reduce the peak wear of the surface contact portion of the pair of materials. The main wear form of the experimental pair under constant load and step load for plastic flow and squeezing deformation, the fatigue of the surface material is caused by the high frequency fluctuating load of DHE. Therefore, it is concluded that the step load has an effect on improving the friction and wear performance of the mating pair, and the DHE load has a damage effect on the mating pair.

Identification Method of Moment of Inertia for Dynamic Modelling of Differential Planetary Gear Train

Identification Method of Moment of Inertia for Dynamic Modelling of Differential Planetary Gear Train

Highly Repeatable Rope Winch Design With Multiple Windings and Differential Gear Mechanism

This paper presents a rope winch with high position repeatability using a differential gear mechanism. This winch is easy to apply to existing buildings using synthetic fiber ropes, which are generally used by building exterior maintenance workers, and can be widely utilized as a winch of a gondola or climbing robot. Multiple pulleys are used to achieve high payloads, and differential gear mechanisms are used to distribute the torque across each pulley evenly. Uniform torque distribution minimizes slipping on each pulley, which reduces the power loss due to friction. This is proven through an analysis using the capstan equation and an experiment on a test bench. In addition, a criterion for the position repeatability of the winch is designed, and its results show that one pressure roller achieves optimal performance when the roller at the free end is pressed to 37 N. Extensive experiments were carried out on the final model of the winch, and position repeatability of under 50 mm deviation per 10 m was achieved through stable torque distribution under various payloads.

Dynamic analysis of elementary differential gear with rigid links

At present the machine dynamics investigations are conducted in the next directions: dynamic processes research in special machines; research of the machines which links are solids; research of mechanisms representing a combinations of a solids and elastic systems. In this paper the elementary differential gear with rigid links dynamics is investigated. A number of dynamic problems can be solved accurately enough without taking into account the loaded element elasticity. Research of dynamic processes of one degree of freedom mechanisms are quite fully published in scientific literature, which cannot be said about mechanisms that have two degrees of freedom. In this paper are compiled and solved the movement equations for differential mechanism with two degrees of freedom. Mechanism has two degrees of mobility, therefore, the position of all its links is determined by two generalized coordinates. The mechanism movement is described by two Lagrange equations of II kind. Rotation angles of the drive and driven shafts are taken as generalized coordinates. System of differential equations of the second order relativ generalized coordinates is compiled. All coefficients of this system can be calculated in advance. Joint solution of equations of the system makes it possible to determine the angular accelerations of the two main links. Equations for determining angular velocities and angular accelerations of drive and driven shafts are recieved.

Dynamic model of speed control through ring gears in a device with a multistage gear differentials and closed-loop hydraulic systems

The dynamic processes in the device for speed control with multistage gear differential and closed-loop hydraulic systems through ring gears have been studied for case when the leading link is the sun gear of the first stage, and the driven is a carrier of the last stage. For such a device, the equation of kinetic energy has been compiled and the dynamics equations have been obtained by the Lagrange method, which have been solved. The obtained results are the basis for further computer simulation on and quantitative analysis to assess the performance of such devices and select the necessary closed-loop hydraulic systems to control speed changes.