Application of modal and harmonic analysis to predict the automotive transmission vibration at an early stage of design

Introduction (problem statement and relevance). The need to increase the operating speeds and input torque of automobile transmissions because of their vibration is becoming a more and more urgent problem.The purpose of the study was to substantiate the applicability of harmonic analysis, which makes it possible to determine the actual values of vibration values during a steady oscillatory process, for the initial assessment of the gearbox vibration activity.Methodology and research methods. The calculation of the gearbox vibration activity was carried out by modal and harmonic analyses, implemented by the finite element method, and followed by the experimental study of gearbox vibration on a test bench.Scientific novelty and results. The presented experimental and calculated results of the research show that the difference between the experimental and calculated values is no more than 4.2%. This proves the possibility of applying modal and harmonic analysis to predict the gearbox vibration state at an early stage of product design at the stand.Practical significance. The given calculation algorithm makes it possible to predict, with a sufficient degree of accuracy, the vibration of the gearbox before the manufacture of a prototype in experimental production.

Vibrational Monitoring of Nested Planetary Geartrain with Unground Pinion

The nested planetary gear train, which has two integrated single-stage planetary gearsets, is one of the newly developed compound gear train that has been successfully applied to the automobile transmissions. In the current study, a certain type of gear fault in the nested gear train, ungrounded pinion, is investigated using a non-destructive approach monitoring its vibration levels. A novel experimental test stand with open and vertical setup has been designed to collect the vibrational data by mounting the accelerometer directly to the gear clutches. Each of the two layers of the compound gear was tested separately. The measured vibrational data were processed with several signal processing techniques, which includes (a) frequency spectrum analysis, (b) time synchronous averaging (TSA) and (c) modulation sideband analysis. The experimental results show that the existence of the ungrounded pinion can be identified with the frequency spectrum analysis of the vibrational data. In addition, the modulation sidebands are also modeled using a modified version of the traditional technique of physical signal modeling. It is shown that the relative phase of the planet and the meshing vibration strength changed by the unground gear is the critical factor for determining the modulation sideband behavior. In addition, the location of the ungrounded pinion can also be determined by the time history processed by TSA.

Controllability of a Singular Hybrid System

We consider the linear hybrid system with constant coefficients that is not resolved with respect to the derivative of the continuous component of the unknown function. In Russian literature such systems are also called discrete-continuous. Hybrid systems usually appear as mathematical models of a various technical processes. For example, they describe digital control and switching systems, heating and cooling systems, the functioning of a automobile transmissions, dynamical systems with collisions or Coulomb friction, and many others. There are many papers devoted to the qualitative theory of such systems, but most of them deal with nonsingular cases in various directions. The analysis of the note is essentially based on the methodology for studying singular systems of ordinary differential equations and is carried out under the assumptions of the existence of an equivalent structural form. This structural form is equivalent to the nominal system in the sense of solutions, and the operator which transformes the investigated system into the structural form possesses the left inverse operator. The finding of the structural form is constructive and do not use a change of variables. In addition the problem of consistency of the initial data is solved automatically. Necessary and sufficient conditions for R–controllability (controllability in the reachable set) of the hybrid systems are obtained.

Research on Automobile Transmission Comprehensive Performance Test Experiment Equipment

Automobile transmission is a very important part of automobile, and the comprehensive experimental Testing Bed of automobile transmission has realized the comprehensive performance test of four kinds of types’ automobile transmissions. This text has recommended design, operation principle, characteristic and how to realize the system of comprehensive experimental testing Bed of automobile transmission. This testing Bed adopts electromechanical unify principle. It realizes four manual transmission being changed into given and stock automatically. Meanwhile it adopts Labview software as the developing testing Bed, realizing be controlled frequency conversion speed regulator, Step-servo motor, magnetic particle loader, clutch, etc. by computer at the same time. This testing Bed also measures torque, rotational speed in real-time on input axle and output axle of the transmission.

A Way to Improve the Accuracy of Hobbed Involute Gears

Involute gears are widely used in the design of machines and mechanisms. Performance of gear transmissions, e.g., performance of automobile transmissions, strongly depends upon the accuracy of gears of which the transmission is comprised. The higher the gear accuracy, the higher performance of the gear transmission observed. An increase of accuracy of involute gears reduces vibration of the transmission, and causes lower noise excitation. A significant amount of gears for the needs of the automotive industry is manufactured by hobbing. Reported in this paper is a way to improve the accuracy of hobbed involute gears that requires an appropriate alteration of design parameters of the hob to be applied. The required correction of design parameters of the hob can be computed on the premises of in-depth analysis of kinematic geometry of meshing of the hob and of the work gear, i.e., of design parameters of the hob, as well as an analysis of kinematics of meshing of the gear work and of the hob. An analytical approach for computation of the required alterations in design parameters of the involute hob is reported in the paper. Using commercial software MathCAD/Scientific, numerous computer codes are developed for performing the necessary computations. A numerical example of computation is presented. The reported results of research are ready to put into production.

Efficiency of Non-Circular Spur Gears

Continuously variable mechanical transmissions employing non-circular spur gears are presently being developed. Such devices are expected to be as efficient in terms of friction losses as common standard automobile transmissions. Tests were carried out using a specially designed power-circulating gear test apparatus to compare meshing losses for non-circular and circular spur gears. Based on these tests it has been found that non-circular spur gears operated at 0.5 rpm and 250 to 750 rpm have losses at the mesh equal to those of similar sized circular spur gears tested under the same conditions.