The Optimal Design And Simulation Of Impulse Stepless Speed Variation

Continuously variable transmission (Abbr. CVT),is a transmission gearing, which can make the rotational speed of output axle change continuously between max and min. generally speaking, according to transmission medium, CVT is classified as mechanical type, hydraulic type, and electric type. For many strong points, Mechanical CVT has more and more developed gradually domestically and abroad. The advantages include simple structure, easy repairing, low price, and efficient transmission, and general application, good steady and satisfactory function. Especially some Mechanical CVT has unchangeable power in wide range, which doesn't reach by electric and hydraulic CVT. It is mainly composed of friction type, chain type, belt type, impulse type. Compared with the friction CVT, the mechanical impulse CVT have simple structure, high reliability, continuous changing speed, general application and so on .Its principle chiefly uses connecting rod(or cam) as the impulse generator such as crank-link type. Crank-link type can make uniform motion of input axle change into reciprocating swing of waving-link, and then by single super-clutch, the reciprocating swing of waving-link transmits single impulse rotating motion. We accomplish continuously variable transmission, by using structure of change speed. The structure can change dimension proportion between links and accomplish continuous change of swinging angle and average swinging speed. If there is a group of crank-link (single), output angular velocity of intermittent impulse rotating motion is unsteady. To obtain continuous and steady output, we should equip some even dispersed links. Three-phase parallel crank-rocker impulse CVT is produced on the basis of three-phase side-rocker impulse CVT. There are three crank-rockers between driving spindle and output axle. They paralleled scatter at parallel plane. In the working process, their motion is replace one after one. As result output angular velocity become steadier. In this paper, we study the crank-rocker type CVT on the basis of the impulse CVT. The biggest pressure angle, pulsation ratio of angular velocity, abrupt change of angular acceleration of output swing link is all reduced largely. We put forward using SIMULINK toolbox in MATLAB, the kinetic simulation model can be established, considering acceleration vector loop equations and then the kinetic and dynamic characteristics of the mechanism can be easily discussed and we optimize parameter structure. ⅠIntroduction In the chapter, we introduce the development condition and application of CVT in broad and home, and analyze the characters and work principles of the mechanical type, hydraulic type, and electric type CVT, and classify Mechanical CVT according to the transmissionprinciples, then we synthesize the merits and demerits of all types, and raise the trend of Mechanical CVT: nonfiction, efficiently transmitting power, speed change steadily, long span, easy made. Ⅱ: the motion simulation of impulse CVT To analysis the kinetic characteristics of impulse CVT and provide design basis of improving the CVT, we analysis the motion. The function parameter that can measure the kinetic characteristics includes: pulsation ratio of angular velocity, abrupt change of angular acceleration, the relations between pulsation ratio of angular velocity, phase and governor place. To reduce these parameter, in the paper we simulate the kinetic by using SIMULINK in MATLAB. To simulate the kinetic, we should know geometry characteristics in advance. The figure is flow chart of the kinetic simulation. The flow chart describes the simulation step and flow of SIMULINK toolbox in MATLAB. There are many striking distinguish between kinetic simulation and traditional kinetic in compute calculation. Based on acceleration, we use SIMULINK numerical integral to calculate speed and displacement. Firstly, speed equation and acceleration equation are obtained by differential analysis on the structure position equation. At Kinetic Simulation flow chartsame time, we calculate the pressure angle of mechanism. According to kinetic equation, we obtain the kinetic parameters which crank rotates a circuit and the kinetic regular of mechanism. Ш: Optimal design of impulse CVT In order to calculate easily, we use the no dimensional size. The length of crank is one; the others are the ratio of the crank length. This calculation doesn't influent the function of whole mechanism. In designing process, we determined designing variable, objective function and restrain condition. At a presupposition of satisfying restrain condition, we select primary math, then optimize them. After optimizing, the math of objective function is lower than the math before optimizing obviously, and the biggest pressure angle is reduced largely. And the regulated range of crank's permit is expanded and the regulated range of transmission's speed is expanded. Therefore the mechanism after optimization can ran more stably, with less impact to bearings and higher machine efficiency. The chapter gives the main conclusion obtained in this paper on these work: 1) the angular velocity of the output swing-link DE changes steadily between 120 angles and 240 angles. The changed range is the work range of each phase parallel crank-rocker mechanism. 2) When the distance of AC is reduced, the rotational speed of output axle changes continuously. And the pulsation ratio of angular velocity is reduced; abrupt change of angular acceleration is raised. 3) after optimizing, the sum which is the angular velocity of the output swing-link DE and abrupt change of angular acceleration is lower than the math before optimizing obviously, and the biggest pressure angle is reduced largely. The mechanism after optimization...