GEARBOX

Abstract

A gearbox (1), in particular coaxial gearbox, includes a ring gear having an internal toothing (3); a tooth carrier (5) having guides (7) which are aligned radially in terms of a rotation axis of the gearbox; teeth (9) which, for engaging with the internal toothing (3), are received in the guides (7), wherein the teeth (9) are mounted in the guides (7) displaceable in the direction of their longitudinal axis (11) relative to the tooth carrier (5); and a cam disk (13) which is rotatable about the rotation axis and is operatively connected to the teeth (9); wherein the teeth (9) have in each case a tooth flank (17) which is at least partially curved along a width curve (51) extending over a width (41) of the tooth flank (17).

Claims

1. A gearbox (1), comprising a ring gear having an internal toothing (3); a tooth carrier (5) having guides (7) which are aligned radially in terms of a rotation axis of the gearbox; teeth (9) which, for engaging with the internal toothing (3), are received in the guides (7), wherein the teeth (9) are mounted in the guides (7) displaceable in the direction of their longitudinal axis (11) relative to the tooth carrier (5); and a cam disk (13) which is rotatable about the rotation axis and is operatively connected to the teeth (9); wherein the teeth (9) have in each case a tooth flank (17) which is at least partially curved along a width curve (51) extending over a width (41) of the tooth flank (17).

2. The gearbox (1) according to claim 1, wherein the tooth flank (17) has two peripheral regions (49) along the width curve (51) over the width (41) of the tooth flank (17), and a central region (47) between the two peripheral regions (49), wherein the tooth flank (17) in at least one peripheral region of the two peripheral regions (49) is recessed inward in relation to the central region (47).

3. The gearbox (1) according to claim 2, wherein the at least one peripheral region is recessed in a direction perpendicular to the tooth flank by at most 1% of a maximum width of the tooth flank (17) in relation to the central region (47).

4. The gearbox (1) according to claim 2, wherein the width curve (51) is curved in at least one peripheral region of the two peripheral regions (49), and is straight in the central region (47) of the tooth flank (17).

5. The gearbox (1) according to claim 2, wherein the two peripheral regions (49) comprise in each case at least 10% and/or at most 40% of the width (41) of the tooth flank (17).

6. The gearbox (1) according to claim 1, wherein the width curve (51) extends symmetrically in terms of a center of the width (41) of the tooth flank (17).

7. The gearbox (1) according to claim 1, wherein the teeth (9) comprise in each case one additional tooth flank, wherein the additional tooth flank is mirror-symmetrical to the tooth flank (17).

8. The gearbox (1) according to claim 1, wherein a curved part of the width curve (51) corresponds to a logarithmic function or to a radius correction.

9. The gearbox (1) according to claim 1, wherein the width curve (51) extends on the tooth flank (17) and in a section plane perpendicular to the tooth flank.

10. The gearbox (1) according to claim 1, wherein the tooth flanks of the teeth (9) are formed by grinding.

11. The gearbox (1) according to claim 1, wherein a longitudinal curve (55) extending on the tooth flank (17) and perpendicularly to the width (41) of the tooth flank (17) is at least partially curved.

12. A gearbox (1), comprising a ring gear having an internal toothing (3); a tooth carrier (5) having guides (7) which are aligned radially in terms of a rotation axis of the gearbox; teeth (9) which, for engaging with the internal toothing (3), are received in the guides (7), wherein the teeth (9) are mounted in the guides (7) displaceable in the direction of their longitudinal axis (11) relative to the tooth carrier (5); and a cam disk (13) which is rotatable about the rotation axis and is operatively connected to the teeth (9); wherein the teeth (9) have in each case a tooth head (15), wherein a tooth head width curve (53) extending along the tooth head (15) and over a tooth width (43) of the tooth (9) is at least partially curved in the direction of the longitudinal axis of the tooth.

13. The gearbox (1) according to claim 12, wherein a curved part of the tooth head width curve (51) extends in the form of a logarithmic function or of a radius.

14. The gearbox (1) according to claim 12, wherein the tooth head (15) in a peripheral region of the tooth (9) is recessed by at least 0.02% and/or at most 2% of the tooth width in relation to a maximum height of the tooth head (15) in the direction of the longitudinal axis (11) of the tooth (9), wherein the tooth head (15) has the maximum height in a central region (47) of the tooth head (15) in terms of the tooth width (43).

15. The gearbox (1) according to claim 12, wherein the tooth head has two peripheral regions along the tooth head width curve over the tooth width of the tooth, and a central region between the two peripheral regions, wherein the tooth head in at least one peripheral region of the two peripheral regions is recessed inward in relation to the central region.

16. The gearbox (1) according to claim 15, wherein the tooth head width curve is curved in at least one peripheral region of the two peripheral regions, and is straight in the central region.

17. The gearbox (1) according to claim 15, wherein the two peripheral regions of the tooth head comprise in each case at least 10% and/or at most 40% of the tooth width.

18. A tooth (9) for a gearbox (1) according to claim 12, wherein the tooth (9) has a tooth flank (17) which is at least partially curved along a width curve (51) extending over a width (41) of the tooth flank (17); and/or wherein the tooth (9) has a tooth head (15), wherein a tooth head width curve (53) extending along the tooth head (15) and over a tooth width (43) of the tooth (9) is at least partially curved in the direction of the longitudinal axis of the tooth (9).

19. A method (100) for producing a tooth (9) for a gearbox (1) according to claim 12, comprising the following steps: providing a tooth blank of the tooth (9); and producing a tooth flank (17) of the tooth (9), wherein the tooth flank (17) is produced so as to be at least partially curved along a width curve (51) extending over a width (41) of the tooth flank (17), and/or producing a tooth head (15) of the tooth (9), wherein a tooth head width curve (53) extending along the tooth head (15) and over a tooth width (43) of the tooth (9) is produced so as to be at least partially curved, in the direction of the longitudinal axis of the tooth (9).

20. The method (100) according to claim 19, wherein producing the tooth flank (17) comprises grinding of the tooth blank, comprising the following steps: actuating a grinding disk in the direction of a longitudinal axis of the tooth blank; and varying the actuation of the grinding disk in the direction of the longitudinal axis of the tooth blank as a function of the position of the grinding disk along the width of the tooth flank (17).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The invention will be explained in more detail hereunder by means of the appended drawings. In the figures:

[0048] FIG. 1 shows a fragment of an embodiment of a typical gearbox in a schematic sectional view;

[0049] FIG. 2 a tooth of a typical embodiment in a schematic view;

[0050] FIG. 3 shows the tooth of FIG. 2 in a lateral view;

[0051] FIG. 4 shows a graph which illustrates the profile of a correction value dy(x) for a tooth flank in a peripheral region of the tooth flank, wherein the zero point of the graphs is in the center of the width of the tooth flank; and

[0052] FIG. 5 shows a flow chart of a method for producing a tooth according to a typical embodiment.

DETAILED DESCRIPTION

[0053] In the following text, typical embodiments of the invention will be described on the basis of the figures, the invention not being restricted to the exemplary embodiments, but rather the scope of the invention being defined by way of the claims. In the description of the embodiments, the same reference signs are used in some circumstances for identical or similar parts in different figures and for different embodiments. Features which have already been described in conjunction with other figures are in part not described again for the sake of clarity. For the sake of clarity, in some cases not all the respective features are provided with a reference sign, for example the teeth (reference sign 9 in FIG. 1).

[0054] A fragment of a typical embodiment of a gearbox 1 is illustrated in a schematic sectional view (radial section) in FIG. 1. FIG. 1 shows the gearbox 1 having teeth 9 which are received so as to be displaceable in guides 7 of a tooth carrier 5. The teeth 9 are typically designed according to embodiments described herein. The tooth carrier 5 is disposed between an internal toothing 3 of a ring gear 4 and a cam disk 13. In FIG. 1, the guides 7 are radially aligned, and the teeth 9 are mounted so as to be radially displaceable in the guides 7. In particular, the teeth 9 are displaceable along their respective longitudinal axis 11. The teeth 9 can be radially displaced for engagement with an internal toothing 3 of the ring gear 4.

[0055] The cam disk 13 in the gearbox 1 of FIG. 1 serves as a drive element of the gearbox 1. The cam disk 13 has a profiling in the circumferential direction of the cam disk 13. In FIG. 1, the profiling has a profile with two elevations over the circumference so that respectively opposite teeth 9 engage to the greatest extent and to equal depths in the internal toothing 3. In additional embodiments, the cam disk can have only one elevation or more than two elevations.

[0056] In the exemplary embodiment of FIG. 1, the rotation axis (not shown) of the cam disk 13 extends perpendicularly to the image plane of FIG. 1. In terms of the rotation axis of the cam disk 13, the cam disk 13 is disposed radially within the teeth 9, and the internal toothing 3 of the ring gear 4 is disposed radially outside the teeth 9 in terms of the rotation axis of the cam disk 13. In such a configuration, the drive output is acquired on the ring gear 4 or on the tooth carrier 5, wherein the respective other element is fixedly established. In additional embodiments, the drive of the gearbox can take place by way of the ring gear, or by way of the tooth carrier, and the drive output can take place by way of the cam disk.

[0057] The gearbox 1 comprises a segmented mounting for the teeth 9. The segmented mounting comprises pivoting segments 25 which have in each case a round tooth bearing face 26 on the side that faces the tooth 9. The tooth bearing face 26 forms a bead on which a tooth base 33 of a tooth 9 is disposed, said tooth base 33 being provided on a radially inner end of the tooth 9. Conjointly with a corresponding clearance in the tooth base 33 of the respective tooth 9, the bead prevents the tooth 9 from sliding out of position relative to the pivoting segment 25. The pivoting segments 25 are mounted on the cam disk 13 by way of rolling members 23, these being needle rollers in FIG. 1.

[0058] In FIG. 1, a tooth 9 comprises in each case two tooth flanks, in particular a tooth flank 17 and an additional tooth flank 18, which converge in the longitudinal direction of the tooth 9 toward a tooth head 15 of the tooth 9. The tooth flanks and the tooth head 15, on a radially outer end of the tooth 9, are provided to engage with the internal toothing 3. Between the tooth flanks and the tooth base 33 of the tooth 9, the tooth 9 has a tooth body 19 which is displaceably mounted in a guide 7 of the tooth carrier 4.

[0059] FIG. 2 shows a schematic view of a tooth 9 according to a typical embodiment. The tooth 9 is embodied as a single tooth, in particular as a round tooth. The tooth 9 comprises in particular a tooth flank 17, an additional tooth flank 18 and a tooth head 15 which is provided between the tooth flanks. The tooth head 15 is designed with a head radius between the tooth flanks. The tooth flank 17 and the additional tooth flank 18 are formed symmetrical in terms of a plane that comprises the longitudinal axis 11 (y-direction) of the tooth 9 and extends parallel to a tooth width 43 (x-direction) of the tooth 9. In a typical gearbox 1, the tooth width 43 of the tooth 9 is aligned parallel to the rotation axis of the gearbox 1, and the longitudinal axis 11 is aligned radially in terms of the rotation axis.

[0060] The tooth flank 17 has two peripheral regions 49 in the direction of the width 41 of the tooth flank 17, and a central region 47 between the two peripheral regions 49. FIG. 3 shows the tooth 9 in a lateral view. The tooth flank 17 is in particular designed so as to be symmetrical in terms of a centric longitudinal curve 55 of the tooth flank 17. The tooth flank 17 extends so as to be at least partially curved along a width curve 51 over the width 41 of the tooth flank 17. In FIGS. 2 and 3, the tooth flank 17 in the peripheral regions 49 extends so as to be curved in the direction of the width 41 of the tooth flank 17, as is explained hereunder in the context of FIG. 4, for example. In particular, the tooth flank 17 has in the peripheral regions 49 a correction in the form of a recess of the tooth flank 17 toward the inside in relation to the central region 47 of the tooth flank 17. The width curve 51 extends so as to be straight in the central region 47. In additional typical embodiments, the width curve can be embodied so as to be curved over the entire width of the tooth flank. The tooth flank in FIGS. 2 and 3 is designed so as to be curved, in particular in the form of a logarithmic spiral, along the longitudinal curve 55.

[0061] The tooth head 15 likewise has a recess in relation to the central region 47 in the peripheral regions 49. The recess in the peripheral regions 49 here is formed in the direction of the longitudinal axis 11 of the tooth 9, so that the profile of the tooth head 15, in particular the height of the tooth head 15 in the direction of the longitudinal axis 11, descends proceeding from the center of the tooth 9 toward the periphery of the tooth head 15. The recess on the tooth head 15 corresponds in terms of its shape to the correction of the tooth flank 17. In particular, a tooth head width curve 53 extending in the direction of the tooth width 43 extends so as to be curved in the peripheral regions 49, in particular in the form of a logarithmic function. In additional typical embodiments, the tooth head width curve can be embodied so as to be curved over the entire width of the tooth flank.

[0062] FIG. 4 shows a graph 400 which describes a logarithmic function according to the formula (1) described herein. The logarithmic function describes in particular correction values dy(x) for the actuation of a grinding disk in the y-direction for producing the tooth flank 17 of the tooth 9 illustrated in FIGS. 2 and 3. In particular, the x-direction and y-direction of the graph 400 correspond to the orthogonal x, y, z-coordinate system illustrated in FIGS. 2 and 3. The graph 400 here shows the correction values for x-positions only for half a tooth width 45 (cf. FIG. 3). The zero point of the graph 400 is in the center of the tooth width 43. The tooth 9 has a tooth width 43 of 10.5 mm, for example. As is illustrated in FIG. 4, the tooth flank 17 has the correction in a peripheral region from x.sub.start=2.7 mm to the periphery of the tooth flank at x.sub.ende=5.25 mm. The peripheral region comprises approximately 25% of the tooth width 43 of the tooth 9. In the production of the tooth flank 17, a grinding disk is actuated closer to the tooth blank as a function of the x-position by the correction value dy(x), so as to produce a recess of the tooth flank 17 and of the tooth head 15 in the form of a logarithmic function along the width 41 of the tooth flank 17. The tooth head width curve 53 produced as a result likewise corresponds to the logarithmic function illustrated.

[0063] FIG. 5 shows a flow chart of a typical method 100 for producing a tooth 9 for a gearbox 1. At block 110, the method 100 comprises providing a tooth blank, in particular a cylindrical tooth blank, for producing a round tooth with two tooth flanks by discontinuous profile grinding.

[0064] At block 120, the method 100 comprises producing a tooth flank 17 of the tooth 9, wherein the tooth flank 17 is produced so as to be at least partially curved along a width curve 51 extending over a width 41 of the tooth flank 17. A profiled grinding disk which represents the profile of the tooth flank 17 and of the tooth head 15 is used for producing the tooth flank 17. At block 120, the profiled grinding disk is actuated in the y-direction, whereby the actuation is varied by a correction value as a function of the position of the grinding disk along the tooth width 43 (x-direction), for example by a correction value dy(x) according to formula (1), or as is illustrated in FIG. 4. Conjointly with the correction of the tooth flank 17, the tooth head 15 is also produced with a corresponding recess along a tooth head width curve 53 of the tooth head 15.

[0065] At block 130, the method 100 comprises producing an additional tooth flank 18 of the tooth 9. In particular, the tooth blank and the grinding disk are rotated by 180 relative to one another about the longitudinal axis 11 (y-direction) of the tooth 9. The additional tooth flank 18 is produced by means of profile grinding, using the grinding disk in a manner analogous to the tooth flank 17. When used in a gearbox 1, a tooth 9 produced in such a manner can in particular display less wear during the running-in phase of the gearbox.