The geometry and strength of KHV-type internal planetary gear trains with a modified original contour of a satellite

Internal planetary gear trains with close numbers of wheel teeth (KHV-type gears) enable large ratio in a single stage along with high efficiency, low weight and small dimensions. That is why there is a particularly urgent need to improve the design of such mechanisms. The load capacity of KHV-type planetary gears is limited by the flexural strength of satellite teeth; therefore, it is important to improve the flexural strength of teeth and gear durability as a whole by reducing the tooth shape factor. For this purpose, it is proposed to form tooth profiles by a tool whose generating contour is a modified standard contour. This makes it possible to reduce the tooth dedendum and increase the radius of curvature of the transition curve. The equations of geometrical synthesis of internal planetary gears are formulated to determine the radii of gear teeth and the pressure angle under the assumption that the teeth do not interfere and the mechanism is not seized. The flexural strength of these non-standard satellite teeth is estimated by the finite element method. The values of the shape factor are determined. New designs of KHV-type gears with roller and hinge mechanisms are presented. The numerical analysis of planetary gears showed that the fabrication of satellite teeth by the tool with a modified generating contour under the rational geometrical synthesis can improve the gear strength by 15–20 %.

References

[1] Singh A., Kahraman A., LigataH. Internal gear strains and load sharing in planetary transmissions: Model and experiments. Journal of Mechanical Design, Transactions of the ASME, 2008, no. 130(7), pp. 0726021–07260210. Doi: 10.1115/1.2890110.

[2] Timofeev G.A., Samoilova M.V. Geometro-kinematicheskoe issledovanie kombinirovannogo planetarno-volnovogo mekhanizma [Geometric-Kinematic Study of Combined Planetary-Wave Mechanism] . Ves tnik MGTU im. N.E. Baumana. Ser. Mashinostroenie [Herald of the Bauman Moscow State Technical University. Ser.Mechanical Engineering]. 2012, no. 1, pp. 70—80.

[3] Lopat in B.A. , Poluektov E.A. , Khaus tov S.A. Formirovanie vnutrennego priblizhennogo zatsepleniia tsilindrokonicheskikh peredach [Formation of internal engagement approximate hel ical-bevel gear ] . Ves tnik IuUrGU. Ser. Mashinostroenie [Herald SUSU. Ser. Mechanical Engineering]. 2011, no. 17, pp. 39—48.

[4] Ivanov A.S., ErmolaevM.M., Krikunov D.E.,Miroshnik A.A., Rudnev S.K., Chirkin A.V. Konstruktivnye ispolneniia planetarno-tsevochnykh reduktorov dlia vysokotochnykh slediashchikh privodov [Structural variations of planetary lantern wheel gear sets for high-precision follower actuators]. Vestnik mashinostroeniia [Russian Engineering Research]. 2013, no. 3, pp. 9—11.

[5] Plekhanov F.I., Molchanov S.M., Sukhorukov V.G. Planetarnaia peredacha [Planetary gear]. Patent RF no. 2445529 RF, MPK F16H1/32, 2010.

[6] Plekhanov F.I., Perminov L.P. Planetarnaia peredacha [Planetary gear]. Patent RF no. 2475662, MPK F16H1/32, 2011.

[7] Plekhanov F.I. Vliianie geometrii zatsepleniia koles planetarnoi peredachi tipa K-H-V na pokazateli ee prochnosti [Influence of interlocking gear wheel geometry of K-H-V type planetary gear arrangement on strength factors]. Vestnik mashinostroeniia [Russian Engineering Research]. 2013, no. 3, pp. 16—20.

[8] Kahraman A., Ligata H., Singh A. Influence of ring gear rim thickness on planetary gear set behavior. Journal of Mechanical Design, 2010, vol. 132, issue 2, pp. 0210021–0210028.

[9] Singh A. Epicyclic load sharing map — development and validation. Mechanism and Machine Theory, 2011, vol. 46, issue 5, pp. 632–646.