Study on the Design and Dynamic Simulation of New Type Hy-Vo Silent Chain Transmission
|Course||Mechanical Design and Theory|
|Keywords||Hy-Vo Silent Chain Meshing Design Proper Meshing Conditions Parameters Transfer Principle Common Normal Line Length Wear Resistance Temperature Field Characteristic Dynamic Simulation|
Silent chian is an important mechanism which is u widely sed. Generally, Silent chains have two types: round-pin silent chain and rocker-pin silent chain. The rocker-pin silent chain used to be called as Hy-Vo Silent Chain when the silent sprocket has involute tooth form. The variable pitch characteristic of Hy-Vo Silent Chain can depress chordal action, impact and noise during Silent chain was meshing with the sprocket, as a result the Hy-Vo Silent Chain is widely used for automobile gear box, transmission box, stremship, rolling mill mechanism, industry pump and other high velocity transmission.Supported by National Natural Science Foundation of China’Project“New Hy-Vo Silent Chain meshing mechanism and design method”(50575089), the design method, wear resistance, temperature field characteristic and dynamic simulation of the New type Silent chain have been researched. This New type Silent chain is composed of meshing mechanism and inner-out meshing mechanism with certain ordered arrangement.The meshing design is the key problem as well as the more difficult one for silent chain transmission, the investigation about the meshing desing of silent chain can rarely be found on oversea and domestic literature.Under consulted and analyzed to the internal and external study of silent chain transmission, the meshing mechanism, the variable pitch characteristic of the New Hy-Vo Silent chain was studied by this thesis. The complete meshing design system of the New Hy-Vo Silent chain, the involute sprocket and the sprocket hob under the study for rolling and cutting theory of them, the relation of them was analyzied. The new concept“The proper meshing relations of Hy-Vo Silent chain”was put forward, it means the proper meshing of Hy-Vo Silent Chain with the sprocket can be satisfied even the value of the tooth form angle of the silent chain link is unequal to the value of the pressure angle of the sprocket when the equation p1 cosα1 = p2 cosα2can be ensured. The research result shows that the main design parameters of the New Hy-Vo Silent chain, the sprocket and the hob is able to be directly determinded through the analytic expression with certain harmonious relations when the equation p1 = p2 andα1 =α2are satisfied. When p1≠p2andα1≠α2, the main parameters of the New Hy-Vo Silent chain , the sprocket and the hob can be designed by the above analytic expression which satisfies certain harmonious ralations according to the meshing theory and roll cutting principle of these three between, the related parameter thransformation must be taken. The feasible meshing design method for New Hy-Vo Silent chain has been brought forward and the related meshing design was carried out.The select and design calculated method of the main parameters of the New Hy-Vo Silent chain sprocket has been studied. The main parameters of the sprocket are the tooth number, the modulus (or the pitch), the pressure angle, the pitch circle, the diameter of the addendum and the dedendum, the measured distance over pins of the sprocket and the modification coefficient. The parameters designs of the New Hy-Vo Silent chain are different with the roller chain sprocket and the silent chain sprocket with straight line tooth form for the desing of the pitch circle, the pressure angle, the common normal line length and the modification coefficient of the New Hy-Vo Silent chain. The design method of the common normal line length of the New Hy-Vo Silent chain was put forward that excelled used calculated method of related literature. The new design method not only can be used for the designing standard Hy-Vo Silent Chain sprocket, but also can be used for the designing the New Hy-Vo Silent chain with special configuration which having the unequal valued between the tooth form angle of the Silent chain link and the pressure angle of the sprocket, the pin hole of the silent chain link is not round. This new design method is an important theoretical and practicale results.The variable pitch characteristic of Hy-Vo Silent chain has been paid more attention by oversea and domestic researchers, but the wear resistance is another important characteristic of the Hy-Vo Silent chain has been ignored. This thesis studies the wear resistance of the New Hy-Vo Silent chain based on the calculation and the wear experiment on the test bench about 300 hours. The result shows that a pair of special shape pins of the New Hy-Vo Silent chain alternatively bear the load with rolling friction, which makes the bearing surface pressure of the special-shape pin is lower than the pressure of the roller chain pin and round-pin silent chain, thus makes the new Hy-Vo Silent chain have excellent wear resistance. The destroy styleof the New Hy-Vo Silent chain was obtained through the wear surface morphology SEM analysis of the link and the special shape pin, the wear mechanism of the pin is the compound of the surface fatigue and adhesive wear, the wear mechanism of the inner working surface of the inner-out meshing link and the outer working surface of the out meshing link are the compound of the abrasive wear and the surface fatigue, the outer working surface of the inner-out meshing link is the surface fatigue. The cyclic softening occurred at the surface layer of the pins because of the friction heat, however, the special configuration (the clearance between the pin and the link pin hole is bigger than the other Hy-Vo Silent Chains) gets more efficient lubricating and coolling for transmission that can reduce the action of the cyclic softening.The real time temperature of the New Hy-Vo Silent chain was tested by Infrared Ray temperature meter. The flash temperature of the friction surface of the link and pins were calculated based on the Blok flash temperature method for the certain meshing location. The results show that the flash temperature of the pins are higher than the link on the meshing, but there are little difference on the steady temperature between the pin and the link after the transmission system get the temperature balance. The special configuration can improve the lubricating and the coolling conditions.The special phenomenon has been found in the bench test of the New Hy-Vo Silent Chain, that is the slack span raised when the sprocket speed up to certain value. This phenomenon did not appear at the bench test of the roller chain and the round-pin Silnet Chains under the same sprocket speed. This special phenomenon relates to the‘upswept angle’and the centrifugal force of the Hy-Vo Silent Chain. However, the centrifugal force is not the main reason witch caused this phenomenon. The arrangement slack span is at upside and the tight span is at the underside of the chain also can meet the transmission requirement because the New Hy-Vo Silent Chains has the‘slack span raised’characteristic, and the interference between the slack span and the sprocket tooth for the wear-elongation were not happen. The New Hy-Vo Silent Chain can be used at broader field than other type chains.The dynamic meshing process of the New Hy-Vo Silent chian was simulated. The virtual prototype model of the meshing between the New Hy-Vo Silent chains with the sprocket was built on the mathematics model which was desing by this thesis. The chordal action, impact force characteristic of the meshing location and the contact force at contact point between eatch plate and pin and between a pair of pins were studied.The new meshing design method of the meshing system of the New Hy-Vo Silnet chain, sprocket and the hob not only has important theoretic value but also has practical value. These parts of the results have been succeeded to guide the design and manufacture of the three type Hy-Vo Silnet chain with the independent intellectual property rights at the certain HangZhou chain corporation, one of them have passed the province identify and others have passed the normal check and been accepted by the main-machine factory. The engine test and automation running test results show the meshing design method are provided by this thesis is available and practicable, the research results of this thesis promoted the progress of related industry, have advanced the innovation capacities of enterprise and have gotten the remarkable economic and social benefits. It has been applied in the industry.At present, the similar researches have not been found.The major contributions of the work presented in this thesis are listed as follows:The new concept“Proper meshing conditions of Hy-Vo Silent chain”was brought forward under the analysis of the rolling and cutting theory between Hy-Vo Silent chain, sprocket and hob. It is the key to ensure the proper meshing of the New Hy-Vo Silent chain with the sprocket and the high transmission efficiency and low noise. The used design mechod and formula can not to guide the proper design of the special type Hy-Vo Silent Chain, especially for proper meshing requirement for the New Hy-Vo Silent with the unequal value between the link tooth form angle unequal and the pressure angle of the sprocket. The complete meshing system of the New Hy-Vo Silent chain, the sprocket and the hob was built up with the certain harmonious relations between three taken into consideration. The parameters transfer principle of Hy-Vo Silent chain has been firstly put forward that is the innovative contribution to the mechanical design theory.Having developed the used design and calculated method of the Hy-Vo Silent chain sprocket common normal line length, the new formula has been put forward, it is not only can able to calculate the standard Hy-Vo Silent Chain but also can be used to caulculate the special configuration, like as the link pin hole is long-round replaced the round form, or the value of the link tooth form is unequal to the valued of the pressure angle of the sprocket.The wear resistance of the New Hy-Vo Silent chain was firstly studied. The wear mechanism of the New Hy-Vo Silent chain was obtained by the SEM analysis of the link and pin, the research has important value to guide the improvement of the wear resistance of the silent chain.The temperature field of the silent chain was studied, the real time measure of the temperature and the flash temperature calculation of the pins and the link friction surface shows that the flash and steady temperature distribution characteristic of silent chain system, which could guide the friction, the wear resistance design and the lubrication design.The virtual prototype of meshing system which include driving sprocket, driven sprocket and the New Hy-Vo Silent chain was built up based on the multi-body dynamic theory, the meshing process of New Hy-Vo Silent chain was simulated on the multi-contact dynamic simulation technology, the research get the useful analysis method to the study of the contact force between link and sprocket, link and pins, pin and pin.