Precessional cycloidal gear reducer

Abstract

FIELD: mechanical engineering.SUBSTANCE: precessional cycloidal gear reducer comprises a housing with a cover, a fixed central gear wheel secured to the housing, an input shaft having a section with an inclined eccentric cylindrical surface located between its cylindrical sections coaxial with the housing, a movable central gear wheel mounted via a bearing at the end of the input shaft and rigidly connected to the output shaft mounted on a bearing support coaxially located in the cover, a two-crown satellite mounted on bearings on a section of the input shaft with an inclined eccentric cylindrical surface with pinions uniformly spaced along the circumferences on the rims, interacting with the teeth of the fixed and movable central gears having the shape of a bicycle sprocket. The number of pinions on the right ring is one unit greater than the number of teeth on the fixed central gear, the number of pinions on the left ring is one unit greater than the pinions on the right ring and the number of teeth on the central movable gear. The centre of precession is located at the centre of mass of the gearbox.EFFECT: simplified design and manufacturing procedure of the gearbox, as well as a low level of dynamics of the reduction mechanism and smoothness of its operation.3 cl, 3 dwg

Description

[0001] Field of technology to which the invention relates

[0002] The invention relates to drive technology, in particular to gearbox engineering, and can be used in various fields of mechanical engineering and instrument making.

[0003] Technology Level

[0004] A precession reduction mechanism of an agricultural winch is known (magazine "Science and Technology", No. 1, 2023. UDC 621.833 "Stages of development of a precession reduction mechanism for an electric drive of an agricultural winch". Authors: D.Sc. (Eng.), Professor Skoibeda A.T., D.Sc. (Eng.), Professor Gromiko P.N., Engineer Goncharov P.S., pp. 2-12, Figs. 3, 4), comprising a drum; a fixed main shaft with an inclined eccentric cylindrical surface; an input link; a satellite wheel; rollers, a movable central gear; a fixed central gear; a pulley.

[0005] The input link is driven by a pulley. Due to the inclined eccentric cylindrical surface of the input link and the satellite wheel mounted on said surface via bearings, the right-hand conical roller ends, evenly spaced around the perimeter in the satellite wheel's axial bores, interact with the outer central gear, which is rigidly attached to the stationary main shaft. As a result of this interaction, the wheel, in addition to oscillating motion, also experiences rotation about its axis. The left-hand conical roller ends, which perform the aforementioned oscillating and rotating motions, interact with the teeth of the outer central gear, which is rigidly attached to the drum.The result of such interaction is the rotation of the outer central gear wheel together with the drum at an angular velocity that is determined by the ratio of the number of rollers and the number of teeth of the outer central gear wheels.

[0006] The disadvantages of the precession reduction mechanism of the agricultural winch are:

[0007] - the impossibility of implementing large gear ratios, due to the fact that its kinematic scheme uses the same number of tapered rollers in the second and third links (in both satellite crowns);

[0008] - high dynamism due to the fact that the center of precession is located at a significant distance from the center of mass of the satellite.

[0009] A precessing gearbox of a multi-turn angle sensor (encoder) is known (Pakhomov S.N. Internal bevel gearing / / Modern engineering and technology, 2016, No. 2 URL: https: / / technology.snauka.ru / 2016 / 02 / 9468), comprising a housing with a cover, an input shaft mounted on bearing supports in fixed and movable central gears with external teeth of internal bevel gearing and having a section with an inclined eccentric cylindrical surface located between cylindrical sections coaxial with the housing, a two-crown satellite mounted by means of bearings on a section of the input shaft with an inclined eccentric cylindrical surface. On the right rim of the satellite there are teeth of internal bevel gearing, interacting with the external teeth of the internal bevel gearing of a fixed gear wheel fixed to the housing.The number of teeth on the right satellite ring is one unit greater than the number of teeth on the fixed central gear. The movable central gear is mounted on the output shaft and rests on the input shaft via a bearing and, together with the output shaft, on the cover. The left satellite ring has internal bevel gear teeth that interact with the external internal bevel gear teeth of the movable gear. The number of teeth on the left satellite ring is one unit greater than the number of teeth on the right satellite ring and the number of teeth on the movable central gear. The center of mass of precession is located at the center of mass of the gearbox. This solution was selected as a prototype.

[0010] The disadvantage of the encoder gearbox design is that, while it has high efficiency and the ability to implement large gear ratios with smaller dimensions than traditional gear mechanisms, the implementation of precessing planetary mechanisms of this type is associated with technological difficulties in the manufacture of internal bevel gears and, accordingly, with a relatively high cost.

[0011] The essence of the claimed invention

[0012] The technical problem that the claimed invention is aimed at solving and the technical result achieved consist in simplifying the design of a reducing precession mechanism while maintaining the possibility of implementing large gear ratios, ensuring low dynamics and smooth operation of the gearbox.

[0013] The technical result is achieved due to the fact that in the claimed precession planetary-pinion gear reducer, comprising a housing with a cover, a stationary central gear wheel with external teeth, secured to the housing, an input shaft mounted on bearings in the stationary and movable central gear wheels with external teeth, having a section with an inclined eccentric cylindrical surface, located between its cylindrical sections coaxial with the housing, a movable central gear wheel, mounted through one of the above-mentioned bearings on the cylindrical end of the input shaft located inside the housing and rigidly connected to the output shaft mounted on a bearing support coaxially located in the cover, a two-crown satellite mounted on bearings on a section of the input shaft with an inclined eccentric cylindrical surface with engagement elements uniformly spaced along the circumferences on the right and left crowns,interacting with the teeth of the fixed and movable central gear wheels, respectively, wherein the number of engagement elements on the right ring is one unit greater than the number of teeth of the fixed central gear wheel, the number of engagement elements on the left ring is one unit greater than the number of engagement elements on the right ring and the number of teeth on the central movable gear wheel, and the center of precession is located in the center of mass of the gearbox, in contrast to the prototype, the movable and fixed central gear wheels have the shape of a bicycle sprocket, and pinions are used as engagement elements in the satellite.

[0014] The pinions of a double-crown satellite can have a conical or cylindrical shape, in which case the depressions in the gears will be made at an angle equal to the precession angle.

[0015] The design of the movable and fixed central gears in the form of a bicycle sprocket, and the engagement elements in the double-crown planet gear in the form of pinions, simplifies the gearbox design while maintaining the ability to achieve high gear ratios. This design ensures low dynamic performance and smooth operation, thanks to the location of the precession center at the gearbox's center of mass. This simplifies the manufacturing process and, consequently, reduces manufacturing costs. To achieve high gear ratios, improve accuracy, and ensure a consistent gear ratio, the gearbox uses a gearing with a difference of one interacting engagement element (gear tooth, pinion), which averages out the errors of individual engagement elements due to a large overlap coefficient.

[0016] The reaction forces in the gearbox from external moments are located on opposite sides of the center of mass. The location of the center of precession at the gearbox's center of mass ensures minimal mechanical losses, smooth gearbox operation, and reduced vibration and noise levels.

[0017] Brief description of drawings

[0018] Fig. 1 shows a structural diagram of the claimed precession reduction mechanism; Fig. 2 is a general view of the precession planetary-pinion reducer with bevel pinions in section. Fig. 3 is a general view of the planetary-pinion reducer with cylindrical pinions in section.

[0019] Implementation of the invention

[0020] The precession planetary pinion gearbox comprises a housing 10 with an oil seal 17 installed therein, a fixed central gear wheel 7 with external teeth, secured to the housing 10 using screws 18 with spring washers 19, an input shaft 3 containing an inclined eccentric cylindrical surface located between its cylindrical sections coaxial with the housing 10, installed in the fixed gear wheel 7 through a bearing 12 and a movable central gear wheel 6 through a bearing 13.

[0021] A two-crown satellite 4, consisting of a two-crown ring and pinions (rollers) 5 placed on its rims, is mounted on a section of the input shaft 3 with an inclined eccentric cylindrical surface through bearings 2 with a spacer 8 between them and is secured with the help of a spring ring 15.

[0022] The movable and fixed central gears 6 and 7 are shaped like a bicycle sprocket.

[0023] On the right and left crowns of the satellite 4, the pinions 5 are located uniformly along the circumference and interact with the teeth of the fixed central gear wheel 7 and the movable central gear wheel 6, respectively, fixed on the housing 10, wherein the number of pinions on the right crown is one unit greater than the number of teeth of the fixed central gear wheel, the number of pinions on the left crown is one unit greater than the number of pinions on the right crown.

[0024] The movable central gear wheel 6 is mounted on the output shaft 1 with support on the cylindrical end of the input shaft 3 located inside the housing 10 through the bearing 13 and on the cover 11 through the bearing 14 coaxially mounted in it. The number of teeth on the central movable gear wheel 6 is one less than the number of pinions of the left rim of the satellite 4.

[0025] Cover 11 with bearing 14 and seal 16 and sealing ring 9 installed on it, is secured to body 10 using screws 20 with spring washers 21.

[0026] The pinions 5 of the two-crown satellite 4 can have a conical or cylindrical shape, in which the depressions in the central gears 6 and 7 will be made at an angle equal to the precession angle.

[0027] The center of mass of the assembly, consisting of satellite 4, bearings 2, spacer 8, spring ring 15, is located in the center of precession of the section of input shaft 3 with an inclined eccentric cylindrical surface.

[0028] The geometric dimensions of sprockets 6 and 7 and satellite 4 are determined in accordance with GOST 591-69 "Sprockets for roller and sleeve drive chains. Methods for calculating and constructing the tooth profile and tool", GOST 13568-97 "Roller and sleeve drive chains. General specifications", GOST 21834-87 "High-strength and precision roller drive chains. Specifications" on the basis of the gear ratio of the reducer adopted as the initial data, and the pitch of the sprocket teeth and the pinion pinion teeth selected from GOST standards, as well as the pinion diameter.

[0029] The precession planetary gear reducer operates as follows (Fig. 2).

[0030] Input shaft 3 is driven by a drive or by hand using a handle. Due to the presence of a section of input shaft 3 with an inclined eccentric cylindrical surface and a two-crowned satellite 4 located on it by means of bearings 2 with a spacer 8, the cantilever ends of the "right" pinions 5, located uniformly around the circumference in the holes of the right crown of the satellite 4, interact with the central gear wheel 7, rigidly fixed to the housing 10. As a result of the said interaction, the satellite 4, along with an oscillatory motion, also experiences rotation about its axis. The ends of the "left" pinions 5, located uniformly around the circumference in the holes of the left crown of the satellite 4, performing the above-mentioned oscillatory and rotational movements, interact with the external teeth of the movable central gear wheel 6, rigidly connected to the output shaft 1.The result of such interaction is the rotation of the central gear wheel 6 together with the output shaft 1 with an angular velocity that is determined by the ratio of the number of pinions 5 installed on the right and left crowns of the satellite 4 and the number of external teeth of the central gear wheels 6, 7.

[0031] To improve accuracy and ensure a consistent gear ratio, a planetary pinion gearbox uses a gear engagement with a difference of one interacting element (gear tooth, pinion), which averages out the errors of individual elements due to a large overlap coefficient. With relatively small dimensions, large gear ratios are achieved, which are determined by the formula:

[0032] i = Z2⋅Z4 / (Z2⋅Z4- Z1⋅Z3),

[0033] where

[0034] Z1- number of teeth of fixed central gear 7;

[0035] Z2= (Z1+ 1) - the number of pinions 5, installed on the right crown of the satellite 4;

[0036] Z3= (Z2+ 1) - the number of pinions 5, installed on the left crown of the satellite 4;

[0037] Z4= (Z3- 1) - the number of teeth of the movable central gear wheel 6, rigidly connected to the output shaft 1.

[0038] The reactions of forces in the gearbox from external moments are located on different sides of the center of mass of the assembly, including the satellite 4, bearings 2, and the elements of their assembly: spacer 8, spring ring 15. To ensure minimal values ​​of mechanical losses, ensure smooth operation of the gearbox, reduce the level of vibration and noise, the center of precession of the gearbox must be located in the center of mass (Fig. 1).

[0039] To eliminate interference between the pinions of the satellite 4 and the teeth of the central gear wheels - sprockets during the operation of the gearbox, the zones of their unfavorable contacts are removed by cutting the tops of the sprocket teeth to the required diameter.

[0040] The technical result achieved consists in simplifying the design of the planetary-pinion gear reducer, simplifying the technology of its manufacture and, accordingly, reducing the cost, ensuring a low level of dynamism of the reduction mechanism and smoothness of its operation, due to the location of the precession center in the center of mass of the gear reducer.

Claims

1. A precession planetary pinion gear reducer comprising a housing with a cover, a fixed central gear wheel with external teeth secured to the housing, an input shaft mounted on bearings in the fixed and movable central gear wheels with external teeth, having a section with an inclined eccentric cylindrical surface located between its cylindrical sections coaxial with the housing, a movable central gear wheel mounted through one of the above-mentioned bearings on the cylindrical end of the input shaft located inside the housing and rigidly connected to the output shaft mounted on a bearing support coaxially located in the cover, a two-crown satellite mounted on bearings on a section of the input shaft with an inclined eccentric cylindrical surface with engagement elements uniformly spaced along the circumferences on the right and left crowns, interacting with the teeth of the fixed and movable central gear wheels,accordingly, the number of engagement elements on the right ring is one unit greater than the number of teeth on the fixed central gear wheel, the number of engagement elements on the left ring is one unit greater than the number of engagement elements on the right ring and the number of teeth on the central movable gear wheel, and the center of precession is located in the center of mass of the gearbox, characterized in that the movable and fixed central gear wheels have the shape of a bicycle sprocket, and pinions are used as engagement elements in the two-ring satellite.

2. A precession planetary-pinion gearbox according to paragraph 1, characterized in that the pinions of the two-crown satellite have a conical shape.

3. A precession planetary-pinion gearbox according to paragraph 1, characterized in that the pinions of the two-crown satellite have a cylindrical shape, and the depressions in the gear wheels are made at an angle equal to the precession angle.

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