The Design Of Gears Of Variable Ratio Differential Of Slip Resistance

Noncircular bevel gears are the major parts of the variable ratio differential, and have its peculiar transmission characteristics in kinematics, dynamics, compared with ordinary bevel gear. They can realize the request for some specific transmission. Noncircular bevel gears can realize the variable ratio transmission of the cross axle , and satisfy the request for variable ratio transmission in some structures, especially some automatic structures. They can also realize various kinds of complicated and special movement, such as swinging , shaking and intermittence ,etc. They can also obtain better transmission performance and have characteristic of compact structure, accurate , reliable , steady transmission, the easy dynamic equilibrium. But because its design and manufacture is very complicated, there is not a ripe design theory and method for noncircular bevel gear at present. Therefore its application and popularization are restricted greatly .This thesis has explained the movement relation between the semi-axis gear and planet gear to the differential mechanism, the movement of the planet's influence on the distributing relation of the torque between two semi-axis gear , and the course that noncircular semi-axis gear and planet gear realize differential and locking up function automatically.As the theory foundation of the design of noncircular bevel gear , it explain the judgement of the protrusion of noncircular gear, the verification condition of pressure angle, contact ratio, the verification condition of root cut and tip cut of teeth in allusion to noncircular gear of concave , and the design method of tooth profile of noncircular gear directly according to principle of normal line of tooth profile.According to the function request for the variable ratio differential mechanism of slip resistance, establish the relation of transmission ratio between the noncircular semi-axis gear and planet gear. This thesis mainly study on the modeling method of the pitch curve on spherical surface, and the algorithm of how to transform the pitch curve on spherical surface into equivalent plane pitch curve, according to the geodesic curvature of the pitch curve on spherical surface. It also explain the design method of equivalent teeth profile of noncircular pitch curve directly according to principle of normal line of tooth profile or analogue simulation of the gear -slotting cutter generating the profile , wrapping up equivalent tooth curve. According to the relationship between the curve of tooth profile on the spherical surface and the curve of plane equivalent tooth profile, this thesis also study on the algorithms of how to transform the curve of plane equivalent involute tooth profile into the curve of involute tooth profile on spherical surface, introducing osculating plane as a medium.It also study on the solution of the intersect point between the curve of teeth and the root curve of teeth, and between the curve of teeth and the top curve of teeth separately. It organize the curve of left profile and right profile of teeth, the root curve of teeth, and the top curve of teeth to form the whole curve of outside profile of the noncircular bevel gear. File the data of the whole curve of outside profile of noncircular bevel gear into the three-dimensional modelling software of UG, and set up the solid model of noncircular gear by the method of swept.