WO2004090377A1

WO2004090377A1 - Quasyplanetary gear system

Info

Publication number: WO2004090377A1
Application number: PCT/UA2004/000018
Authority: WO
Inventors: Yuriy M. Lykhovyd; Volodimir V. Skambrychiy; Leonid M. Soroka
Original assignee: Lykhovyd Yuriy M; Skambrychiy Volodimir V; Soroka Leonid M
Priority date: 2003-04-09
Filing date: 2004-03-30
Publication date: 2004-10-21

Abstract

The invention relates to a planetary gear system with non rotatable pinions and multi-pairs teeth meshing with a sun wheel. The offered gear system can be used in machine drives and lift plants for transmission big driving torque. The gear system dimensions is at least two times less than known analogous gear system by other equvally conditions. A gear system comprices a casing, an input shaft, an output shaft, at least three intermediate shafts, a rotatable sun wheel with internal teeth thereon, which connected to said output shaft; a carrier, which connected to said casing and containing on bearings said intermediate shafts, which established eccentric on equal angular distance each of the other therein; eccentric placed pinions, which established on bearings and on eccentric sleeves and having external teeth thereon, said pinions having a peripheral opening therein, which quantity is equal to quantity of said intermediate shafts, which placed in said peripheral opening of all said pinions; edges of said opening touches upon the said intermediate shafts and said eccentric sleeves established on siad input shaft. The said input shaft is established eccentric and being monolith together with one of the said intermediate shaft and heights of said internal and said external teeth being smaller than its thickness.

Description

QUASYPLANETARY GEAR SYSTEM

This invention relates to the gear systems industry. More specifically, it relates to a planetary gear system with non rotatable pinions and their multi-pairs teeth meshing with a sun wheel. The offered gear system can be used in machine drives and in lift plants for transmission of the big driving torque. The gear system dimensions is at least two times less than known analogous gear system by the other equal conditions.

Is known a gear system with multi-pairs teeth meshing that comprises a casing, an input shaft rotatable in said casing, a balance, an eccentric on said input shaft; a pinion on said eccentric for rotation therewith on a bearing; first teeth on said pinion; an internal gear with second teeth thereon, that meshing with said first teeth for rotation of said internal gear by said pinion; and output shaft connected to said internal gear for rotation therewith, said internal gear having at least one tooth more than said pinion for effecting a reduction in rotational speed of said output shaft relative to said input shaft, said first teeth being conjugate to said second teeth, the contact path between said first and second teeth being curved and lying within the crescent-shaped area, and the only contact between said first and second teeth being entirely on one side of a line extending diametrically through the centers of said pinion and said internal gear.

Main problems in such gear system are (i) big pinion establishing eccentricity and (ii) lengthened tooth form, by which the tooth height is 1.6 - 1.75 times greater, than the tooth thickness. The big pinion establishing eccentricity invokes vibrations of the casing. To compensate the vibrations it is need to use a balance with an additional weight. The balance needs additional place in the gear casing. As result it increases the weight of the gear system and dimensions in axial direction.

The before known lengthened tooth form causes second problem - the limited driving torque, transferred of the separate tooth because the tip of side tooth on the pinion contacts with the tooth root of the internal gear and the side tooth in the crescent-shaped area can bend or even can crash by excessive torque forces.

Is known also a gear system with multi-pairs teeth meshing, that comprises a casing, an input shaft, at least three intermediate shafts, that eccentric established on equal angular distance each from the other on bearings in an rotatable carrier, which is connected to output shaft, a non rotary sun wheel with internal tetth thereon, additional toothed wheels, that is established on input shaft and on all intermediate shafts for kinematics connection to four eccentric placed pinions, which established over bearings on eccentric sleeves on all intermediate shafts, moreover the sun wheel having at least one tooth more than the pinion (patent of Russian Federation No. 2011066, int. Kl. F16H 1/32 from 15.04.94.)

The most close to offered technical solution of above mentioned problem is the gear system, that comprises a casing, an input shaft, at least three intermediate shafts, that eccentric established on equal angular distance each from the other on bearings in a non rotary carrier, that connected to the casing, a rotatable sun wheel with external teeth thereon, connected to output shaft, additional toothed wheels, established on input shaft and on all intermediate shafts for kinematics connection to four eccentric placed pinions, which established over bearings and over eccentric sleeves on all intermediate shafts and having external teeth thereon, moreover the sun wheel having at least one tooth more than the pinion (patent of Russian Federation No. 2011067, int. Kl. F16H 1/32 from 15.04.94.).

The known gear systems avoids all kind vibrations without a separate balances, but have to complicate design, large dimensions and do not exclude second problem (ii) at all.

GENERAL DESCRIPTION OF THE INVENTION

The purpose of the offered invention is to provide solutions to the above identified problems in the form of a gear system, in which there is no separate placed balances. The gear system has simple design and teeth with new configuration which can't be bent at all.

Accordingly the invention, that relates to a gear system, it comprises a casing, an input shaft, an output shaft, at least three intermediate shafts that eccentric established on equal angular distance each from the other on bearings in a non rotary carrier, that connected to the casing, a rotatable sun wheel with internal teeth therein, connected to said output shaft, eccentric placed pinions, which established over bearing on eccentric sleeves and having the external teeth thereon, said each pinion having a peripheral opening therein, which quantity being equal to the quantity of said intermediate shafts, which placed in said peripheral openings of the said all pinions, edges of said openings touching upon the said intermediate shafts and said eccentric sleeves are established on said input shaft.

Another object of the invention, that additional comprises second bearings and second eccentric sleeves, established on all said intermediate shafts, toothed wheels, established on all said intermediate shafts, said input shaft established eccentrically and being monolithic together with one of the said intermediate shaft.

Yet another object of the invention is to provide a gear system in which heights of said internal and said external teeth being smaller than their thicknesses.

Yet another object of the invention is to provide a gear system in which said internal teeth being conjugate to said external teeth, the contact path between said internal and external teeth being curved and lying within the crescent-shaped area, and the contact between said internal and said external teeth being on two side of a line extending diametrically through the centers of said pinion and said sun wheel.

Yet another object of the invention is to provide a gear system in which the said toothed wheels established opposite to the said input shaft.

Yet another object of the invention is to provide a gear system which containing two side said pinions and central said pinion, which masse being equal to double masse of the said side pinion.

Yet another object of the invention is to provide a gear system in which said central pinion having a balance.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described hereinafter with reference to the accompanying drawings, which illustrate a preferred embodiment of the invention, and wherein:

FIG. 1 is a schematic view of a gear system in accordance with the first variant of present invention; FIG. 2 is a cross section taken generally along line A-A of FIG. 1 , with parts omitted;

FIG. 3 is a schematic view of gear system in accordance with the second variant of present invention;

FIG.4 is a cross section taken generally along line B-B of FIG. 4, with parts omitted;

FIG. 5 is a kinematics scheme of the tooth motion according to present invention;

FIG. 6 is a schematic view of usual tooth configuration as compared with tooth configuration according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENT

With reference to FIGS. 1 and 2, the basic parts of a gear system in accordance with the present invention are a casing 1 which houses an input shaft 2, output shaft 3, three intermediate shafts 4, a rotatable sun wheel 5 with internal teeth 6 therein, a connected to the casing 1 carrier 7,8, which containing on a bearings 9,10 intermediate shafts 4, which eccentric established on equal angular distance (120°) each from the other therein, eccentric placed pinions 11,12 with external teeth 13 thereon. Pinions 11,12 are established over bearings 14 on eccentric sleeves 15, and are having a peripheral opening 16 therein, which quantity (3) being equal to the quantity of said intermediate shafts 4, which placed in said peripheral opening 16 of the all said pinions 11,12, edges of said opening 16 are touching upon the said intermediate shafts 4 and said eccentric sleeves 15 established on said input shaft 2. The pinion 11 is established with an eccetricty e, the pinion 12 is established with the opposite eccetricity -e. The carrier is defined by a pair of cylindrical sections 7 and 8. The cylindrical sections 7 and casing 1 are interconnected by a plurality of screws 18 (two shown). The cylindrical sections 7 and cylindrical sections 8 are interconnected by a distance sleeve 19 and coupling screw 20. The ball bearings 9 is closed by covers 21. The input shaft 2 is established on ball bearings 22, 23 accordingly in cylindrical sections 7 and 8. The ball bearing 22 is closed by cover 24. The input shaft 2 extends through an oil seal 25 of the cover 24 and an output shaft 3 extends through an oil seal 26 in casing 1. On the section 8 is established a bearing 27 which carries the sun wheel 5. In casing 1 is established bearings 28 in which is rotating a bearing sleeve 29 that interconnects the sun wheel 5 and the output shaft 3.

The second variant of the gear system on FIGs. 3 and 4 additional comprises toothed wheels 30, established on the all intermediate shafts 4 for kinematic connection to pinions 11,12, second bearings 31 (see FIG.4) and second eccentric sleeves 32, that established on all intermediate shafts 4. The input shaft 2 is established eccentrically and being monolithic together with one of the intermediate shaft 4. Heights of internal 6 and external 13 teeth being smaller than their thicknesses and internal teeth 6 being conjugate to external teeth 13, the contact path 33 between internal 6 and external 13 teeth being curved and lying within the crescent-shaped area 34 (FIG 5), and the contact path 33 (FIG.4) between said internal 6 and said external 13 teeth being entirely on two side of a line 35 extending diametrically through the centers of said pinions 1 1(12) and sun wheel 5. Toothed wheels 32 is established opposite said input shaft 2 and kinematic interconnected by the toothed wheel 34.

The second variant of the gear system on FIG.3 comprises two side pinions 11 and one central pinion 12 which containing a balance 36, which masse being compensate the vibrations. On the section 8 is established a bearing 27 on which is rotating the output shaft 3. In casing 1 is established bearings 28 in which is rotating the sun wheel 5 together with output shaft 3. The sun wheel 5 and the output shaft 3 are interconnected by a toothed coupling.

In operation, the rotation of the input shaft 2 results in a beating motion of the eccentric sleeve 15 on FIG.l . As result the pinions 11,12 are performing the plane-parallel movement without rotation because the carrier 7,8 is connected to the casing 1. The phase of the pinion's motion is opposite to the motion of the pinion 12. The teeth quantity _j of the pinion 11,12 are equally and less of the

teeth quantity ^ of the sun wheel 5 on a value from 1 to 6.

FIG. 5 shows the tip circle 36 of the sun wheel 5 such as the tip circle 37 of the pinion 11. As shown in FIG. 5 the area 38 of overlap between tip circle 37 of the pinion 11 and the tip circle 36 of the sun wheel 5 is crescent-shaped. A line 35 is passing through the gear centers O_j and ^ (of the sun wheel and the

pinion, respectively) and intersects the tip circles 36 and 37 at points a and b respectively. The working depth of the teeth is the distance between the points a and b, respectively. The point b of the pinion tooth tip 13 coincides with the point C of the sun wheel tooth root 6. In operation, the center ^ of the pinion 11

(12) moves on the path, that is a circle with the diameter of 2*e. If the eccentric sleeve 15 is turned on an angle a the pinion center O^ moves to the position

O' 2- The position of the pinion root circle by the turn on an angle a is shown on

FIG.2 as a dotted circle 39. Because the pinion 11(12) don't rotate about the center O^ the each its point moves on the same path on the circle with the same diameter 2*e. The pinion tip point b of the tooth 13 moves to the position b ^r. The root point C of the sun wheel teeth 6 moves to the position C^f, that can be determined from the equation:

In progress of the plane-parallel motion of the pinion 11(12) the tip point b is performing a hypocycloid on a path 32 relate to the root point c of the sun wheel 5. This curve has some bent points in the polar coordinate with beginning in the center O_j.

The bent points coordinates is defined due to the second derivation in polar coordinates and one of them is shown as point b ' on FIG.5.

According to the present invention in first variant of the gear system the bent point b^f of hypocycloid 32 is placed outside the crescent-shaped area 38 as it is shown on FIG.5.

The conjugate tooth profiles of the pinion 11(12) and the sun wheel 5 can be calculated by the methods of conventional gear geometry accordingly the profile of the section C ^f-b ^f.

With clockwise rotation of eccentric sleeve 15 the teeth contact starts at the point a. The contact ends at the point 40 where the contact path 33 intersects the tip circle 37 of the pinion 11. If the eccentric sleeve 15 is rotated counterclockwise, the contact paths 33 are the mirror images of the one shown in FIG.2.

During one turn of the input shaft 2 the pinion 11 runs on the inner teeth of the sun wheel 5 and in the meshing comes exactly Z^ its teeth. Because the

pinion 11 don't rotate, the sun wheel 5 turns on angle that is proportional to the teeth difference Z₂- Z^. As result to turn one time the sun wheel 5 (and

accordingly output shaft 3) its need to turn input shaft 2 more times that is the reduction ratio TV of the present gear system is defined as follows:

N= Z₂/( Z₂ - Z₁),

that allows to get values of N from 10 to 300 by present design of the gear system with an error of less than 0.1%.

In accordance to the kinematic scheme on FIG. 5 the second variant of the gear system on FIGs.3 and 4 corresponds the position of the hypocycloid bent point b ' when it places on the inner edge of the crescent-shaped area 38. In this variant the teeth contact 33 between pinion teeth 13 and sun wheel teeth 6 occurs in two side of a line 35 extending diametrically through the centers of the pinion 11 and sun wheel 5 as shown on FIG.4.

The rotation of input shaft 2 on FIG.3 is transmitted directly to one of the intermediate shafts 4 and to the rest of the intermediate shafts 4 over the toothed wheels 30,34 and they all are rotating synchronuos (together with eccentric sleeves 15 and 32). The synchronuos rotating of intermediate shafts 4 results in a simultaneous affect of the sleeves 15 and 32 on the pinion 11 in three or more its areas that quantity depends from the quantity of intermediate shafts 4. Pinions 11,12 are performing the plane-parallel motion without rotation. The motion of the pinion 11 is opposite phased to the motion of pinion 12. With clockwise rotation of the input shaft 2 the teeth contact of the pinion 11(12) and sun wheel 5 starts at the point 41, intersects the segment a-b and ends at the point 41 where the contact path 33 intersects the tip circle 37 of the pinion 11. If the eccentric sleeve 15 is rotated counterclockwise, the contact paths 33 are the mirror images of the one shown in FIGs.4 and 5.

The advantage of present invention is their simply design. So in the first version on FIG.1 there are no eccentric sleeves and bearings on all intermediate shafts 4. In the second variant on FIG.2 the gear system don't comprises constructive parts (input shaft, bearings ect.) in axial area of the gear system that allows to reduce radial distance between intermediate shafts 4 and accordingly dimensions of the gear system. The establishing of toothed wheels opposite to the input shaft allows to hide their in a hollow output shaft 3 and to do the radial dimensions of the gear system almost the same as the diameter of the output shaft 3 . The main advantage of the offered gear system consists in depending the tooth bending resistance from tooth thickness. For offered teeth configuration the value of bending resistance W_s is determined as follows:

W_s = BS²/6,

where H - is value of tooth width and S - value of tooth thickness.

In case of multi-pair meshing the effort of rotation moment F is shared between all teeth conjugate in crescent-shaped area. In accordance to above shown expression bending strain σ can be determined from the equation:

<5 = Fr/n*6/(BS²), where n - quantity of teeth-pairs that are multaneously meshing in crescent-shaped area; r <\ is a factor that reflects an irregularity of the effort sharing between n teeth. In case the cutting k time more teeth of lengthened configuration in the same crescent-shaped area with a small modulus (FIG.6) the thickness s' of all such teeth will be accordingly k time smaller, that is s^,=s/k. Their value of bending resistance W'_s can be determined from the equation:

W'_s = BS²/(6k²)

In such conditions the same driving moment effort F is shared between n *k teeth-pairs and value of their bending strain s ^f can be determined from the equation:

σ' = Fr/(nk) *6k²/(B$²)=kσ. When to reduce the above expression on k can get the depending between σ and σ that is bending strain of small modulus gearing is k time greater than bending strain in a big modulus gearing of the offered configuration.

Claims

We claim:

1. A gear system, that comprises a casing (1), an input shaft (2), an output shaft (3), at least three intermediate shafts (4), that eccentric established on equal angular distance each from the other on bearings (9, 10) in a non rotary carrier (7,8), that connected to the casing, a rotatable sun wheel (5) with internal teeth (6) thereon, which connected to said output shaft (3); eccentric placed pinions (11,12) , which established over bearings (14) on eccentric sleeves (15) and having external teeth (13) thereon, which d i ffe r s so, that each said pinion (1 1 ,12) having a peripheral opening (16) therein, which quantity being equal to quantity of said intermediate shafts, which placed in said peripheral opening of the all said pinions; edges of said openings touching upon the said intermediate shafts and said eccentric sleeves (15) established on said input shaft (2).

2. A gear system according to claim 1, that additional comprises second bearing (31) and second eccentric sleeves (32), established on said intermediate shafts (4), a toothed gear (30), established on intermediate shafts (4) for connection to said pinions (1 1 ,12), which d i ffe r s so, that said input shaft (2) established eccentric and being monolith together with one of the said intermediate shaft (4).

3. A gear system according to claims 1 or 2, which d i ffe r s so, that heights of said internal (6) and said external (13) teeth being smaller than their thicknesses.

4. A gear system according to claims from 1 to 3, in which said internal teeth (6) being conjugate to said external teeth (13), the contact path (33) between said internal (6) and external (13) teeth being curved and lying within the crescent-shaped area (38), which d i ffe r s so, that contact between said internal (6) and said external (13) teeth being in two side of a line (35) extending diametrically through the centers of said pinion (11) and said sun wheel (5).

5. A gear system according to claims from 2 to 4, which differs so, that said toothed gears (30) established opposite to the said input shaft (2).

6. A gear system according to claims from 2 to 4, which differs so, that there being two said side pinions (11) and one said central pinion (12), which masse being equal to double masse of said side pinion (11).

7. A gear system according to claim 6 which differs so, that said central pinion (12) containing a balance (36).