Eccentric gear with rotationally symmetrical transmission elements

Abstract

The invention relates to an eccentric gear comprising: a shaft which is rotatable about an axis of rotation and has at least one eccentric portion with a central eccentric axis which is arranged at an acute angle to the axis of rotation and intersects the axis of rotation at a point "O1"; a planet which is mounted on the eccentric portion so as to be rotatable about the eccentric axis, wherein this planet has planet toothing; a first gear part having a first toothing which is in meshing connection with the planetary toothing at a first engagement point via rotationally symmetrical transmission elements; and a second gear part having a second toothing which is in meshing connection with the planetary toothing at a second engagement point via rotationally symmetrical transmission elements, characterised in that the rotatable shaft has an additional second eccentric portion with a second eccentric axis which has an angle to the axis of rotation which is half as large and has the same sign as the angle of the first eccentric axis such that the three axes intersect at precisely one point "O1", the centre of rotation, and a two-part cage is mounted on this second eccentric portion, which cage has a first cage part and a second cage part such that the transmission elements are received between the two cage parts with little or no play, which elements run in the same number with the trochoidal rolling channels introduced in the planet and roll simultaneously in the trochoidal rolling channels of the first gear part and in the trochoidal rolling channels of the second gear part diametrically opposite the point "O1".

Description

[0001] Eccentric gear with rotationally symmetrical transmission elements

[0002] The present invention relates to an eccentric gear.

[0003] State of the art

[0004] The most important goals in gear development include reducing manufacturing costs and increasing efficiency and power density. For example, in planetary gears, various planetary types are being investigated, and various rotationally symmetrical transmission elements are being used instead of teeth.

[0005] An eccentric gear is known from patent specification DE 199 07 912 A1, which has an eccentric that is arranged at an angle around the axis of rotation and which rotatably accommodates a planet. The planet meshes with the planetary gearing both with the stationary part of the gear and at the same time with the output. This design therefore consists of a fixed gear, a planet and a rotatable output gear - tricycle gear. The disadvantage of this solution is that the type of gearing, whether involute, cycloid, circular arc or other similar gearing, requires a three-dimensional design, which on the one hand leads to high manufacturing costs and on the other hand to relatively low efficiency.

[0006] Another design of a three-wheel transmission is known from DE 11 2016 002 380 T5. Here, the problem of planetary gearing was circumvented by using two independent gears, one meshing with the fixed gear and the second with the output gear.

[0007] A proposal was described early on in US 1 748 907 A in which the planet meshes with the fixed gear but then transmits the power to the output via a wave-shaped groove using balls as transmission elements.

[0008] In the publications WO 2007 / 094 693 A1, AT 508 205 B1, DE 10 2014 001 263 A1 and US 9 863 480 B2, a planetary gear running on an angular eccentric with two independent rows of magnets arranged on one or both sides are also used as transmission elements.

[0009] Attempts were also made early on to replace involute gearing, which operates with a high degree of sliding friction, with a transmission element geometry based on rolling friction. This is described in US 594 110 A for parallel and non-parallel axes. A similar solution is described in DE 10 2012 220 260 A1. In the first case, this creates sliding friction in the axes of the rollers, while in the second case, sliding friction is created at least on one gear due to forced guidance.

[0010] DE 10 2014 208 418 A1 describes a solution in which rollers are also used as transmission elements, which move along tooth flanks in a more or less controlled manner.

[0011] US Patent No. 1,867,492 describes the cycloidal gearing solution, which uses rollers as transmission elements to achieve the mechanical conversion of torque and speed. This solution has proven successful, but only at a certain minimum reduction ratio, and it requires some form of mass balancing.

[0012] The publication DE 11 2017 001 685 T5 describes a solution in which balls act as transmission elements in wave-shaped transmission grooves in an eccentric drive element and then convert the mechanical variables via wave-shaped transmission grooves in a centric output element. However, the solution presented here results in a large degree of relative movement between the transmission elements and the transmission grooves, resulting in low efficiency.

[0013] The printed document EP 1 757 841 B1 describes a type of gear in which the transmission elements are balls which, independently of one another, carry out a spatial, oscillating movement whose shape depends on the shape of the guide curves used. The transmission elements designed as balls are always located where the curve of the input element intersects the curve of the output element. This results in transmission elements, as in a cycloidal gear, which are clamped between two flanks and cause the output to move relative to the input. A disadvantage of this solution is the occurrence of alternating pressure and play states in the transmission elements due to the lack of a ball cage.

[0014] In the publications US 1 277 193 A, US 3 590 659 A, US 4 620 456 A and US 4 620 457 A, up to the publications GB 2 085 994 A, US 4 960 003 A, US 4 829 851 A, US 4 643 047 A, US 5 312 306 A, US 5 443 428 A, RU 2 272 196 C2, EP 1 462 677 A1 and others, roller gears or ball gears, i.e. gears in which the transmission elements are balls or rollers, are described. What they all have in common is that they provide cylindrical or spherical grooves in the shape of trochoids with the same or similar pitch radius in a stationary, driving, and output gear section. The transmission elements run in these grooves and are located at the intersection points of the cams. This creates constraints between the three gear sections, which, with a continuous input rotary motion, achieve a not exactly continuous rotary motion at the output. XU, Lizhong; SONG, Wentao; LI, Ran: Two-step sine movable tooth drive.In: Advances in Mechanical Engineering, Vol. 9, 2017, No. 6, pp. 1-9 - ISSN 1687-8140 (E); 1687-8132 (P). DOI: 10.1177 / 1687814017712414. URL: https: / / journals.sage-pub.com / doc / pdf / 10.1177 / 1687814017712414?Download=true [accessed on 2024-03-11]. This type of transmission has gained increased attention due to the development of modern manufacturing machines, as these transmissions can largely replace the sliding friction of classic gear transmissions with rolling friction of the transmission elements. It should be noted that with a single planet, a single ring of orbiting elements, and with a double planet, i.e. with two rings of orbiting elements, the reduction can be adjusted as required.Some of the proposed solutions do not use cages, others use cages to partially guide the rotating elements, which has a detrimental effect on the constancy of the output speed, on the vibration behavior and on the wear of transmission elements and their orbits.

[0015] Further designs are known from the publications DE 10 2008 001 490 A1, US 3 385 135 A, and DE 197 14 528 A1. Object of the invention

[0016] In order to improve the constancy of the output speed, the smooth running and the wear of gearboxes with rolling transmission elements, according to the preamble of claim 1, it is proposed to use a multi-part cage for the transmission elements, which, according to the invention, is controlled in a similar way to the planet, so that it keeps the transmission elements in the optimal paths calculated in theory, regardless of the level of the pressure conditions that prevail between the transmission elements and their raceways and the speed at which the gearbox is operated.

[0017] Description

[0018] An advantageous design of the transmission 1 according to the invention consists of an axis of rotation 2 along which the rotatable shaft 3 extends, which is rotatably mounted in the transmission part 1 13 via the bearing 1 31 and with the transmission part 2 15 via the bearing 3 33. The transmission part 2 15 is mounted in the transmission part 1 13 via the bearing 2 32. A first eccentric section 4 is mounted on the shaft 3 at an angle 0 6 with its axis 5, and a second eccentric section 9 is mounted at an angle 1 11 with its axis 10. The axes 2, 5 and 10 intersect at the kinematic center "01" 12 of the transmission. The planet 7 is mounted radially on the first eccentric section 4 via the bearing 20 and axially via the bearing 21. On the second eccentric section 9, the cage parts 17 and 18 are supported radially and axially via the bearings 22.In the kinematic center "01" 12 lies the coordinate system in which the guide curves 34, 35 and 36 are defined, according to which the rolling channels 14 in the first gear part, 16 in the second gear part and 24 in the planet 7 are introduced and on which guide curves 34, 35 and 36 the transmission elements 19 move.The cage parts 17 and 18 are designed in such a way that they accommodate the transmission elements 19 between them so that they can rotate freely and with little play along the equator, so that due to the rotational movement forced on the cage parts 17 and 18 by the shaft 3 and the free rotational movement for the cage parts 17 and 18 around the axis 10 of the second eccentric section 9, the transmission elements 19 are supported in the rolling channels 14, on the transmission surfaces 27 or 28 - depending on the direction of rotation of the shaft 3 - of the first gear part 13 and in the rolling channels 24, on the transmission surfaces 25 or 26 - depending on the direction of rotation of the shaft 3 - of the planet 7 and move in a rolling manner exactly along the guide curve 34 in the first gear part 13 and along the guide curves 36 for the rolling channels 24 in the planet 7. The forces generated by the dimensionally preloaded transmission elements 19 and the forces generated by the output torque, F. N, the reaction torque from the planetary gear 7 is introduced into the first gear part 13. Accordingly, the rotary motion is transmitted by the transmission elements 19 in the rolling channels 16, to the transmission surfaces 29 or 30—depending on the direction of rotation of the shaft 3—of the second gear part 15.

[0019] A further advantageous arrangement of the gear according to the invention is used to achieve a higher reduction ratio. The gear 37 constructed in this way consists of an axis of rotation 38 along which the rotatable shaft 39 extends, which is rotatably mounted in the gear part 1 50 via the bearing 1 66 and with the gear part 2 52 via the bearing 3 68. The gear part 2 52 is mounted in the gear part 1 50 via the bearing 2 67. A first eccentric section 40 is mounted on the shaft 39 at an angle 0 42 to its axis 41, and a second eccentric section 46 is mounted at an angle 1 48 to its axis 47. The axes 38, 41 and 47 intersect at the kinematic center “02” 49 of the gear 37. On the first eccentric section 40, the double planet 43 is mounted radially via bearing 59 and axially via bearings 60. The planet 43 has two sets of rolling channels with the transmission surfaces 64 and 65 on either side of its equator.On the second eccentric section 46, the three-part cage 17, 18 and 54 is mounted radially and axially via the bearings 61. The transmission elements 58 are arranged in two sets, spaced from and at a distance from the equator of the three-part cage 17, 18 and 54, between the cage parts 17 and 54 as well as 18 and 54, so that they can rotate freely and with little to no play. Their number and distance from the equator correspond to the rolling channels provided in the planet 43. In the kinematic center "02" 49 lies the coordinate system in which the guide curves in the first gear part 50, the second gear part 52 and the planet 43 are defined, according to which the rolling channels in the first gear part 50, the second gear part 52 and the planet 43 are introduced and on which guide curves the transmission elements 58 move.

[0020] Description of the attached drawings:

[0021] Fig. 1 shows the transmission according to the invention according to claim 1 in longitudinal section;

[0022] Fig. 2 shows the section AA marked in Fig. 1 through the transmission elements of the transmission according to the invention

[0023] Fig. 3 shows the section BB marked in Fig. 2 in the direction of the rotation axis of a transmission element. Fig. 4 shows the section CC marked in Fig. 3, through which

[0024] Rotation axis of a transmission element

[0025] Fig. 5 shows an exploded view of the transmission according to the invention from Fig. 1

[0026] Fig. 6 shows the kinematic model of a gearbox from the state of the art

[0027] Fig. 7 shows the kinematic model of the transmission according to the invention

[0028] Fig. 8 shows the arrangement of the trochoids of the first gear part, the planet and the second gear part, at a certain time - the transmission elements are shown in a reduced size here

[0029] Fig. 9 shows a longitudinal section through the transmission according to the invention with double planetary gear and one output

[0030] Fig. 10 shows a longitudinal section through the transmission according to the invention with double planetary gear and two outputs

[0031] Fig. 11 shows a half section of a bevel gear for deriving a trochoid

[0032] Fig. 12 shows the transmission according to the invention as a variant with a radial drive.

[0033] List of reference symbols

[0034] 1 Gearbox according to the invention

[0035] 2 axis of rotation

[0036] 3 Rotating shaft

[0037] 4 First eccentric section

[0038] 5 First eccentric axis

[0039] 6 Angle of the first eccentric section

[0040] 7 Planet

[0041] 8 Planetary gearing Second eccentric section Second eccentric axis Angle of the second eccentric section Intersection of the two eccentric axes: "01" First gear part

[0042] Rolling channels for the transmission elements in the first gear part Second gear part

[0043] Rolling channels for the transmission elements in the second transmission part

[0044] First cage part, guided according to the invention Second cage part, guided according to the invention Transmission element

[0045] Radial bearing of the planet Axial bearing of the planet Radial-axial bearing of the cage parts Contact surfaces on the cage parts for the transmission elements Rolling channels in the planet

[0046] First transmission surfaces in the planetary gear Second transmission surfaces in the planetary gear First transmission surfaces in the first gear section Second transmission surfaces in the first gear section First transmission surfaces in the second gear section Second transmission surface in the second gear section Bearing 1 Bearing 2 Bearing 3 Guide curve in the first gear section Guide curve in the second gear section Guide curves in the planetary gear

[0047] Inventive gear with double planetary axis of rotation

[0048] Rotating shaft

[0049] First eccentric section

[0050] First eccentric axis

[0051] Angle of the first eccentric section

[0052] Double Planet

[0053] First planetary gearing

[0054] Second planetary gearing

[0055] Second eccentric section

[0056] Second eccentric axis

[0057] Angle of the second eccentric section

[0058] Intersection of the two eccentric axes: "02"

[0059] First transmission part

[0060] Running surfaces of the transmission elements in the first transmission part

[0061] Second transmission part

[0062] Running surfaces of the transmission elements in the second transmission part

[0063] Middle cage part, guided according to the invention over the transmission elements

[0064] Starting surface of the first set of transmission elements on the first cage part

[0065] Starting surface of the first set of transmission elements on the middle cage part

[0066] First set of transmission elements

[0067] Second set of transmission elements

[0068] Radial bearing of the planet

[0069] Axial bearing of the planet

[0070] Radial-axial bearing of the double cage

[0071] Contact surfaces of the transmission elements of the first set in the cage Contact surface of the first set of transmission elements on the second cage part

[0072] Transmission surfaces of the first set of transmission elements in the planet

[0073] Transmission surfaces of the second set of transmission elements in the planet

[0074] Warehouse 1

[0075] Camp 2

[0076] Camp 3

[0077] Inventive gearbox with double planetary gear and two output parts

[0078] Third transmission part

[0079] Transmission surfaces of the first set of transmission elements in the third transmission part

[0080] Camp 4

[0081] Cage in usual design and function in the state of the art

[0082] Path line or guide curve of the transmission elements in the first gear part

[0083] Path line or guide curve of the transmission elements in the second transmission part

[0084] A selected point on the selected tooth of gear 1

[0085] The tooth flank of the selected tooth

[0086] A selected tooth of gear 1

[0087] Bevel gear 1

[0088] Bevel gear 2

[0089] Bevel gear

[0090] Parting plane between gear part 1 and gear part 2

[0091] Pitch circle of the transmission elements

[0092] Inventive gear with radial drive Drive direction 86 Housing, first gear part

[0093] 87 Output, second transmission part

[0094] 88 drive with planet

[0095] 89 Drive element, here gearing

[0096] 90 Drive shaft bearing

[0097] 91 Output shaft bearing

[0098] 92 Planet, outer

[0099] 93 Radial bearing of the planet

[0100] 94 Axial bearing of the planet

[0101] 95 Transmission element

[0102] 96 Two-part cage, guided according to the invention

[0103] 97 Axial-radial bearing of the cage parts

[0104] 98 rolling channels in the first gear section

[0105] 99 rolling channels in the second gear section

[0106] 100 drainage channels in the planet

[0107] Cited publications

[0108] Dl. DE 199 07 912 Al

[0109] D2. DE 11 2016 002 380 T5

[0110] D3. US 1 748 907 A

[0111] D4. WO 2007 / 094 693 Al

[0112] D5. AT 508 205 Bl

[0113] D6. DE 10 2014 001 263 A

[0114] D7. US 9 863 480 B2

[0115] D8. US 594 110 A

[0116] D9. DE 10 2012 220 260 Al

[0117] DIO. DE 10 2014 208 418 Al

[0118] Dll. US 1 867 492 A

[0119] D12. DE 11 2017 001 685 T5

[0120] D13. EP 1 757 841 Bl

[0121] D14. US 1 277 193 A D15. US 3 590 659 A

[0122] D16. US 4 620 456 A

[0123] D17. US 4 620 457 A

[0124] D18. GB 2 085 994 A

[0125] D19. US 4 960 003 A

[0126] D20. US 4 829 851 A

[0127] D21. US 4 643 047 A

[0128] D22. US 5 312 306 A

[0129] D23. US 5 443 428 A

[0130] D24. RU 2 272 196 C2

[0131] D25. EP 1 462 677 Al

[0132] D26. Xu, Lizhong; Song, Wentao; Li, Ran: Two-step sine movable tooth drive. In: Advances in Mechanical Engineering, Bd. 9, 2017, H6,S. 1-9.- ISSN 1687-8140 (E) ; 1687-8132 (P) . DOI : 10.1177 / 1687814017712414. URL : https : / / journ ls . sagepub . com / doi / pdf / 10.1177 / 1687814017712414 ? down- load=true [abgerufen am 2024-03-11]

[0133] D27. DE 10 2008 001 490 Al

[0134] D28. US 3 385 135 A

[0135] D29. DE 197 14 528 Al

Claims

Patent claims 1. Eccentric gear with a shaft (3) rotatable about a rotational axis (2), which has at least one eccentric section (4) with a central eccentric axis (5) which is arranged at an acute angle (6) to the rotational axis (2) and intersects the rotational axis (2) at a point "01" (12), a planet (7) which is mounted on the eccentric section (4) so as to be rotatable about the eccentric axis (5), wherein the planet (7) has a planetary toothing (8), a first gear part (13) with a first toothing which is in meshing connection with the planetary toothing (8) at a first engagement point via rotationally symmetrical transmission elements (19), and a second gear part (15) with a second toothing which is in meshing connection with the planetary toothing (8) at a second engagement point via rotationally symmetrical transmission elements (19), wherein the transmission surfaces of the gears in the first and second gear parts are manufactured in such a way,by the trochoid, which is created when the pitch circle of the planet rolls over the pitch circle of the gear part according to a constant transmission ratio, being run over with a profile that is the same or similar to the transmission element and thereby removing material from the gear part, so that the transmission elements between the planet and the gear parts perform a rolling movement and that the transmission surfaces created due to the trochoids are only partially retained in the material of the gear parts, whereas the transmission surfaces created by the planetary trochoids in the planet are completely incorporated in the material of the planet, characterized in that that the rotatable shaft (3) has an additional second eccentric section (9) with a central second eccentric axis (10), which has an angle (11) to the axis of rotation (2) that is half as large and has the same sign as the angle (6) of the first eccentric axis (5), so that the three axes (2), (5) and (10) intersect at exactly one point "01" (12), the center of rotation, and on this second eccentric section (9) a two-part cage (17 and 18) is mounted, which has a first cage part (17) and a second cage part (18), so that the transmission elements are accommodated between the two cage parts with little to no play, which transmission elements are arranged in the same number as the planetary (7) introduced trochoidal rolling channels (24) and simultaneously carry out a pure rolling movement in the trochoidal rolling channels (14) of the first gear part (13) and in the trochoidal rolling channels (16) of the second gear part (15) diametrically opposite to the point "01" (12).

2. Eccentric gear according to claim 1, characterized in that a two-part cage (17 and 18) is provided, which is mounted on the drive shaft via its own eccentric section, which receives the transmission elements (19) in a ring shape along its equator.

3. Eccentric gear according to claim 1, characterized in that the transmission elements (19) are arranged in a three-part cage (17, 18 and 54) in two planes parallel to the equatorial plane of the cage and spaced apart from the equatorial plane.

4. Eccentric gear according to one of claims 1 to 3, characterized in that the transmission elements (19) are designed as balls and the profiles of the rolling channels (14, 16 and 24) are shaped with a corresponding osculation to the balls.

5. Eccentric gear according to one of claims 1 to 3, characterized in that the transmission elements (19) are torus-shaped.

6. Eccentric gear according to one of claims 1 to 5, characterized in that the rolling channels (14, 16 and 24) in the region of the reversal points in the extreme angular positions of the planet (7) are cleared in such a way that no radial and axial constrained positions arise.

7. Eccentric gear according to one of claims 1 to 6, characterized in that the trochoids used to produce the rolling channels (14, 16 and 24) in the gear parts (13, 15) and the planet (7) as well as the path line of the transmission elements (19) correspond exactly to that path line (74, 34) of a selected point (76) on the tooth flank of a tooth (77) of one gear (79) opposite the other (80) in an equivalent bevel gear (81) with an involute or similar toothing.

8. Eccentric gear according to one of claims 1 to 6, characterized in that the trochoids used to produce the rolling channels (14, 16 and 24) in the gear parts (13, 15) and the planet (7) as well as the path line of the transmission elements (19) correspond exactly to the path line of a point (76) in the center of the tooth width of a tooth (77), on the pitch circle of one gear (79) opposite the other (80) in an equivalent bevel gear (81) with an involute or similar toothing.

9. Eccentric gear according to one of claims 1 to 6, characterized in that the rolling channels (14, 16 and 24) in the gear parts (13, 15) and the planet (7) as well as the path line of the transmission elements (19) used trochoid corresponds exactly to the path line of a selected point (76) in the volume of a tooth (77) of one gear (79) compared to the other (80) in an equivalent bevel gear (81) with an involute or similar toothing.

10. Eccentric gear according to one of claims 1 to 6, characterized in that the trochoids used to produce the rolling channels (14, 16 and 24) in the gear parts (13, 15) and the planet (7) as well as the path line of the transmission elements correspond exactly to the path line of a selected point (76) outside the volume of a tooth (77) of one gear (79) compared to the other (80) in an equivalent bevel gear (81) with an involute or similar toothing.

11. Eccentric gear according to one of claims 1 to 10, characterized in that a variant according to the invention (84) is designed so that the drive takes place from the radial direction (85), from the outside and thus the two eccentric areas act outside the transmission elements (95), while maintaining the position of the eccentric axes.

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