Improvement of roller chain sprocket tooth profile

The improvement of roller chain sprocket tooth profile - 2019 08 - 19 0 introduction roller chain drive is considered to be one of the most effective form of power transmission of mechanical system, it has the basic characteristics of the constant ratio, therefore, it is widely used in car engines for timing mechanism and oil pit system. This kind of system noise and vibration problems remains, because of faster, lighter, and higher quality is essential for today's car. Due to its polygon effect and mesh, roller chain drive generally applicable to the slower speed transmission collision, the dynamic characteristics of roller chain for a large amount of experimental study and theoretical study of roller chain drive improvements. Between the chain and sprocket meshing process usually is a conjugate, which leads to the polygonal action and the meshing impact in the process of meshing. Polygon action refers to the pitch line alternately chain sprocket pitch circle is tangential or secant, chain pitch line moved up and down continuously, the instantaneous transmission ratio between drive and driven sprocket is variable. These features can result in uneven chain speed, horizontal and vertical longitudinal vibration, noise and meshing impact, damage to the transmission of synchronicity and uniformity, so that the application of roller chain drive is limited by low speed. However, it is necessary to develop conjugate function or approximate conjugate function, a new kind of tooth shape, to reduce the number of roller chain polygon effect and impact, because the timing mechanism in automotive engine transmission speed can be increased to 7000 - 8000 r/min. Only special design of roller chain to achieve conjugate effect, we try to through the modification of sprocket approximate conjugate action. In this article, in order to improve the operating performance, in theory, developed a new kind of sprocket tooth profile of roller chain at high speed. Sprocket tooth profile can ensure the sprocket meshing between sprocket and chain roller is a kind of approximate conjugate function, engine timing mechanism multi-body dynamics model of the intake and exhaust sprocket set up. Then, this paper proposes a for sprocket tooth profile of asymmetric modifying methods to analyze the dynamic characteristics of asymmetric improvement sprocket. 1 roller chain study 1. 1 roller chain meshing mechanism as a result of the action of polygon, the center line of the roller chain of alternately is sprocket pitch circle are tangent or secant. The center line of the chain of periodic changes directly affect the chain speed of driving chain and instantaneous angular velocity. In order to reduce the speed of change, it is necessary to ensure that a pitching Angle of pitch circle arc length is equal to the pitch of chain and chain or ensure that at any given moment of moving distance is equal to the arc length of pitch was turning. 1. 2 will chain modeling analysis of roller chain and its model for power system, and developed software, the Lagrange multiplier method is adopted to solve the dynamic problem. In the software, all the parameters in model are set according to the actual chain drive system. Dynamic characteristic of the chain can be analyzed, such as the meshing impact, the load fluctuation of valve CAM chain and sprocket wheel friction and collision, friction between chain and tensioner, friction and collision within the fixed guide rail and pre-tightening force of tensioner. 1. Three roller chain, the dynamic behavior of the especially in high speed roller chain and sprocket meshing impact can be created. Transient peak in chain began to mesh wheel exists wallop. Impact vibration is one of the main sources of noise exist in timing chain transmission mechanism. It could lead to a chain of tensile and fatigue. 2 conclusions proposed a new sprocket tooth shape, can effectively reduce the dynamic effect of chain transmission and meshing impact. This revised traditional involute tooth profile. It can ensure mobile distance chain at any point is equal to the rotation of pitch circle arc length, and tight side roller center line and the sprocket pitch circle tangent. New toothed roller can gradually and sprocket meshing impact between rollers and sprockets. Established the engine intake and exhaust sprocket chain timing mechanism of multibody dynamics model. Tight side connecting rod and the meshing impact between sprocket, chain and gear friction between the two CAM shaft connecting rod connecting rod swings. The analysis results show that the new tooth profile sprocket meshing impact under different rotational speed and friction force decreases obviously. According to the characteristics of the unidirectional transmission sprocket drive mechanism, sprocket asymmetric tooth profile is proposed. Discusses the changes and acquire the method of asymmetric tooth profile. The dynamic characteristics of asymmetric toothed sprocket analysis showed that the friction between the apparent link and driving part is reduced, the chain tension, improve chain fluctuation and camshaft speed fluctuations.