Eccentric Gearing

Abstract

The present disclosure relates to an eccentric gearing having a first gearing element, which has a first axis and an outer contour having at least one cam, and having a second gearing element, which has a second axis which is constantly held eccentrically in relation to the first axis. The first gearing element is rotatable relative to the second gearing element, and the second gearing element is supported on the outer contour of the first gearing element such that a rotation of the first gearing element effects a rotation of the second axis of the second gearing element about the first axis. The first gearing element has a number N of cams protruding radially, and uniformly distributed in the circumferential direction, in relation to the first axis. The second gearing element is supported at N+1 contact points of the first gearing element, wherein N is at least two.

Claims

1. Eccentric gearing comprising: a first gearing element, which has a first axis and an outer contour having at least one cam protruding radially in relation to the first axis; a second gearing element, which has a second axis which is constantly held eccentrically in relation to the first axis, wherein the first gearing element is mounted in a rotatable manner about the first axis relative to the second gearing element, and wherein the second gearing element is supported on the outer contour of the first gearing element such that a rotation of the first gearing element about the first axis will effect a rotation of the second axis of the second gearing element about the first axis, and wherein the outer contour of the first gearing element has a number N of cams protruding radially in relation to the first axis, which cams are arranged so as to be distributed uniformly in a circumferential direction in relation to the first axis, wherein the second gearing element is supported at N+1 contact points on the outer contour of the first gearing element, and wherein the number N is at least two.

2. Eccentric gearing according to claim 1, wherein the outer contour of the first gearing element is formed by a closed trochoid with N cycles.

3. Eccentric gearing according to claim 1, wherein the second gearing element comprises: N+1 contact cams which are arranged so as to be uniformly distributed in the circumferential direction in relation to the second axis of the second gearing element and point towards the second axis, wherein the second gearing element is supported on the outer contour of the first gearing element via the contact cams in N+1 contact points.

4. Eccentric gearing according to claim 3, wherein the contact cams comprise, at least in a region where the corresponding contact point can come to rest: a circular contour convex with respect to the second axis.

5. Eccentric gearing according to claim 3, wherein the outer contour of the first gearing element is surrounded by an elastically deformable sleeve which is mounted in a rotatable manner with respect to the first gearing element via a plurality of rolling elements) arranged between the first gearing element and the sleeve, wherein the contact cams abut against an outer circumference of the sleeve in the contact points, so that the second gearing element is supported on the outer contour of the first gearing element indirectly via the contact cams.

6. Eccentric gearing according to claim 1, wherein the eccentric gearing comprises: N+1 rollers mounted to be rotatable at the second gearing element which are arranged so as to be uniformly distributed in the circumferential direction in relation to the second axis of the second gearing element, and roll directly on the outer contour of the first gearing element at the contact points.

7. Eccentric gearing according to claim 6, wherein the second gearing element is composed of a plurality of segments.

8. Eccentric gearing according to claim 1, wherein the number N corresponds to the number two.

9. Eccentric gearing according to claim 1, wherein the second gearing element is a gear rim comprising: a toothing with a first pitch which engages in a toothing of a ring gear with a second pitch, the first pitch being larger than the second pitch.

10. Eccentric gearing according to claim 9, wherein the eccentric gearing comprises: four gear rims arranged one behind each other, which are each supported on the outer contour of the first gearing element at N+1 contact points, wherein the second axes of the two outer gear rims are offset in relation to the first axis of the first gearing element by 180° with respect to the second axes of the two central gear rims.

11. Eccentric gearing according to claim 9, wherein the gear rim is made of steel or ceramics.

12. Eccentric gearing according to claim 1, wherein a rotation of the first gearing element about the first axis will effect a rotation of the second gearing element about the second axis.

13. Eccentric gearing according to claim 1, wherein the second gearing element is configured to be rigid.

14. Eccentric gearing according to claim 2, wherein the second gearing element comprises: N+1 contact cams which are arranged so as to be uniformly distributed in the circumferential direction in relation to the second axis of the second gearing element and point towards the second axis, wherein the second gearing element is supported on the outer contour of the first gearing element via the contact cams in N+1 contact points.

15. Eccentric gearing according to claim 4, wherein the outer contour of the first gearing element is surrounded by an elastically deformable sleeve which is mounted in a rotatable manner with respect to the first gearing element via a plurality of rolling elements arranged between the first gearing element and the sleeve, wherein the contact cams abut against an outer circumference of the sleeve in the contact points, so that the second gearing element is supported on the outer contour of the first gearing element indirectly via the contact cams.

16. Eccentric gearing according to claim 6, wherein the eccentric gearing comprises: N+1 rollers mounted to be rotatable at the second gearing element which are arranged so as to be uniformly distributed in the circumferential direction in relation to the second axis of the second gearing element, and roll directly on the outer contour of the first gearing element at the contact points.

17. Eccentric gearing according to claim 7, wherein the number N corresponds to the number two.

18. Eccentric gearing according to claim 17, wherein the second gearing element is a gear rim comprising: a toothing with a first pitch which engages in a toothing of a ring gear with a second pitch, the first pitch being larger than the second pitch.

19. Eccentric gearing according to claim 10, wherein the gear rim is made of steel or ceramics.

20. Eccentric gearing according to claim 19, wherein a rotation of the first gearing element about the first axis will effect a rotation of the second gearing element about the second axis.

Description

[0027] Embodiments of the present invention will be illustrated more in detail below with reference to drawings.

[0028] In the drawings:

[0029] FIG. 1 shows a perspective longitudinal section through an eccentric gearing according to the invention according to first exemplified embodiment,

[0030] FIG. 2 shows a partially sectional perspective view of an eccentric gearing according to the invention according to a second embodiment,

[0031] FIG. 3 shows a further perspective view of the eccentric gearing according to the invention of FIG. 2 in a partially opened state,

[0032] FIG. 4 shows a view of the eccentric gearing of FIG. 3 parallel to its axis,

[0033] FIG. 5 shows the view of FIG. 4 with an opened roller bearing between the first gearing element and the elastically deformable sleeve,

[0034] FIG. 6 shows the view of FIG. 4 with a first gearing element rotated about 30° with respect to the original position shown in FIG. 4,

[0035] FIG. 7 shows the view of FIG. 4 with a first gearing element rotated about 60° with respect to the original position shown in FIG. 4,

[0036] FIG. 8 shows the view of FIG. 4 with a first gearing element rotated about 90° with respect to the original position shown in FIG. 4,

[0037] FIG. 9 shows the view of FIG. 4 with a first gearing element rotated about 120° with respect to the original position shown in FIG. 4,

[0038] FIG. 10 shows the view of FIG. 4 with a first gearing element rotated about 150° with respect to the original position shown in FIG. 4,

[0039] FIG. 11 shows the view of FIG. 4 with a first gearing element rotated about 180° with respect to the original position shown in FIG. 4,

[0040] FIG. 12 shows a perspective longitudinal section through an eccentric gearing according to the invention according to a third exemplified embodiment,

[0041] FIG. 13 shows a perspective detailed view of a possible second gearing element of the eccentric gearing according to the invention of FIG. 12, and

[0042] FIG. 14 shows a perspective detailed view of the second gearing element of the eccentric gearing according to the invention of FIG. 12.

[0043] In the following illustrations, equal parts are designated by equal reference numerals. If a figure contains reference numerals which are not explicitly discussed in the pertaining description of the figures, reference is made to previous or following descriptions of the figures.

[0044] FIG. 1 shows an eccentric gearing 1 according to the invention according to a first embodiment of the present invention. The inner hollow shaft 2 forms, in this eccentric gearing, the input shaft and simultaneously a first gearing element in the sense of the present invention. It comprises a first axis 3 which is arranged concentrically to the shaft 15 and mounted in a rotatable manner with respect to the shaft 15. The shaft 15 forms the output shaft of the gearing and is itself mounted in a rotatable manner with respect to a housing 18 of the eccentric gearing 1 according to the invention. The shaft 15 simultaneously serves as a support of altogether four gear rims 6.1, 6.2, 6.3 and 6.4 which are in entraining engagement with the first gearing element 2 and each comprise an external toothing engaging in an internal toothing of a corresponding ring gear 14 connected to the housing. The shaft 15 serving as a support to this end comprises altogether six pins 16 arranged so as to be uniformly distributed in the circumferential direction, and which are received in corresponding bores 17 (see FIG. 3) of the gear rims 6.1 to 6.4.

[0045] The functioning of the eccentric gearing shown in FIG. 1 corresponds to the second embodiment shown in FIGS. 2 to 11 which principally only differs from the first embodiment in that the teeth of the internal toothing of the ring gear 14 are formed by cylindrical bolts 19 (see in particular FIGS. 2 and 3), the external toothing of the four gear rims 6.1 to 6.4 being formed by a closed trochoid. In the first and second embodiments, the eccentric gearing according to the invention is therefore embodied as a cycloidal gearing. For the sake of good order, it is pointed out that only every second to third tooth of the internal toothing of the ring gear 14 is actually realised. For the further illustration of the invention, the second embodiment is considered below.

[0046] In FIG. 3 and the following FIGS. 4 to 11, the front part of the support 15 is removed, so that there is an unobstructed view onto the interior of the gearing. As in particular FIGS. 3 and 4 show, the external toothing of the gear rims 6.1 to 6.4 comprises one tooth less than the internal toothing of the ring gear 14, as it is common with cycloidal gearings. The axes of the four gear rims are constantly kept eccentrically in relation to the axis 3 of the first gearing element 2. In the present invention, however, this is not achieved by a simple eccentric. In FIG. 5, one can see that the first gearing element comprises, in the region of the gear rims, an outer contour 4 with two cams 5 protruding radially and arranged offset with respect to each other by 180°. The outer contour 4 of the first gearing element results by an epitrochoid with two cycles. Each one of the four gear rims 6.1 to 6.4 has an inner contour with altogether three contact cams 8 arranged so as to be uniformly distributed in the circumferential direction and facing inwards. Between the outer contour 4 of the first gearing element 2 and the inner contour of each gear rim, an elastically deformable sleeve 9 is arranged which is mounted in a rotatable manner with respect to the first gearing element via a plurality of rolling elements 10 arranged between the first gearing element and the sleeve, and which, during the rotation of the first gearing element 2, deforms like a flex spline of a harmonic drive gearing. The elastically deformable sleeve 9 thus constantly adopts the shape of the outer contour 4 of the first gearing element 2 (extended in parallel). The contact cams 8 of each gear rim abut against the outer circumference of the sleeve 9 at the three contact points 7, so that the gear rims 6.1 to 6.4 are indirectly supported via the contact cams 8 on the outer contour 4 of the first gearing element 2. A rotation of the first gearing element 2 about the first axis 3 thus leads to a rotation of the gear rims 6.1, 6.2, 6.3, 6.4, that means of the second gearing element, about the axes of the four gear rims 6.1, 6.2, 6.3, 6.4, that means of the second axes, and thus also to a rotation of the second axes about the first axis 3.

[0047] FIGS. 6 to 11 show the view of FIG. 4, wherein the first gearing element 2 has been rotated stepwise about 30° each with respect to the position shown in the respective preceding figure. FIG. 11 thus shows a position of the first gearing element 2 rotated about 180° with respect to the original position. With reference to the marking point 20 on a tooth of the external toothing of the first gear rim 6.1, one can clearly see that the first gear rim 6.1 is rotatably offset by one tooth of the internal toothing of the ring gear 14 in the process. The gear rim 6.1 here undergoes a swaying movement which is translated, via the engagement between the bores 17 of the gear rim and the pin 16 of the support 15, into a continuous rotary motion of the support 15.

[0048] In the shown embodiment, the axes of the two outer gear rims 6.1 and 6.4 are offset in relation to the axis 3 of the first gearing element 2 with respect to the axes of the two inner gear rims 6.2 and 6.3 by 180°. The two outer gear rims and the two inner gear rims each operate synchronously. For this reason, in FIGS. 4 to 11, only the gear rims 6.1 and 6.2 can be seen.

[0049] In the embodiment in FIGS. 2 to 11, the four gear rims 6.1 to 6.4 each form a second gearing element 6 in the sense of the present application. The gear rims 6.1 to 6.4 are rigid, i. e. the gear rims 6.1 to 6.4 are not deformed by the first gearing element. FIGS. 12 to 14 show a third embodiment of the present invention wherein the four gear rims are replaced by one single gear rim 6. As FIG. 14 and the alternative embodiment in FIG. 13 show, the gear rim is composed of a plurality of segments 12 and 13 permitting a design free of unbalances. Reference numeral 21 designates the axis of the gear rim 6. At the gear rim 6, altogether six rollers 11 mounted in a rotatable manner are attached which are arranged so as to be uniformly distributed in the circumferential direction in relation to the axis 21 and roll at altogether six contact points directly on the outer contour 4 of the first gearing element shown in FIG. 12. In this embodiment, too, the gear rim 6 is rigid and therefore does not undergo any deformation in case of a contact of the contact points on the outer contour 4 of the first gearing element. In this embodiment, the outer contour 4 of the first gearing element 2 therefore comprises altogether five cams arranged so as to be uniformly distributed in the circumferential direction. Here, too, a rotation of the first gearing element 2 about the first axis leads to a rotation of the gear rim 6, i. e. the second gearing element, about the axis 21 of the gear rim 6, i. e. about the second axis, and thereby also to a rotation of the second axis 21 about the first axis 3.

[0050] In the shown exemplary embodiments, every second gearing element comprises exactly N+1 contact points, wherein N is the number of cams of the first gearing element protruding radially in relation to the first axis.

LIST OF REFERENCE NUMERALS

[0051] 1 eccentric gearing

[0052] 2 first gearing element

[0053] 3 first axis

[0054] 4 outer contour

[0055] 3 cam

[0056] 6 second gearing element

[0057] 6.1 gear rim

[0058] 6.2 gear rim

[0059] 6.3 gear rim

[0060] 6.4 gear rim

[0061] 7 contact point

[0062] 8 contact cam

[0063] 9 elastically deformable sleeve

[0064] 10 rolling element

[0065] 11 roller

[0066] 12 segment

[0067] 13 segment

[0068] 14 ring gear

[0069] 15 support

[0070] 16 pin

[0071] 17 bore

[0072] 18 housing

[0073] 19 cylindrical bolt

[0074] 20 marking point

[0075] 21 second axis

[0076] N number