Study On The Meshing Theory, Design And Manufacturing Of External Cycloidal Type Gear Pump

The two meshing rotors are the most important parts in the gear pumps. And in the rotor design, the design of the profile is of the key importance, because the profile of the rotor basically determine the performance of a gear pump. In the future, exploiting new profile and new products will be the direction of the development of gear pumps.The tooth profile of gear pump is involute in general. Though the involute profile is easy to design and manufacture, it also brings the inherent problem of oil trapping. In addition, the meshing of two convex teeth make the relative radius of curvature of the contacting point shorter. When the number of teeth is less than the minimum, involute gears will be undercut.In this paper, a new kind of external cycloidal type gear rotor, which is composed of arcs and their conjugate curves (cycloidal type curves), is designed, by the aid of the modern meshing theory and CAGD. This kind of rotor has a good meshing characteristics and low flux pulse, even eliminate oil trapping. Be free of undercut, the number of teeth can be very small, thus the area between teeth can accordingly be largened more. The special meshing of convex and concave teeth profile makes the relative radius of curvature of the contacting point longer.The meshing characteristic of the cycloidal type gear pump is analyzed theoretically and calculated; furthermore, it is compared with that of the involute. The design principles of the basic geometric parameter are discussed.If rotors are regarded as gears, the method of gears manufacturing can also beused to rotors. At present,types of the cutters commonly include disc-type cutters and gear hobs. In this paper, the disc-type cutter manufacturing cycloidal type gears is designed by applying spacial meshing theory. In power gear transmission, the equation of the basic rack profile must be known in general. It's the equation of the hob and the gear profile that need be deduced. But,in this paper, the equation of rotor profile is known, which is designed according to the requirement. Applied medium conjugate method and medium rack, the question of the complex spacial meshing can be transformed into the question of the parallel-axes meshing. Applied the plane meshing theory, the equations of the medium rack and the hob transverse profile are deduced. In this paper, the equation of the projection of hob helicoid has also been deduced and the projection is compared with the basic rack nomal profile. This design method is easily performed. Furthermore,only involving the plane meshing theory, the result is clear and is easily tested.