Coaxial gear

Abstract

A coaxial gear (1), includes an axially oriented tooth system (5) with respect to a rotational axis (3) of the coaxial gear (1), a tooth carrier (7) having axially oriented guideways (9), tooth pins (11) received within the guideways (9) for engaging with the tooth system (5), wherein the tooth pins (11) are axially oriented within the guideways (9) by their respective longitudinal axes and are mounted within the guideways (9) in an axially displaceable manner, and a cam disc (15) rotatable about the rotational axis (3) for axially driving the tooth pins (11), wherein a plurality of bearing segments (17) is disposed between the cam disc (15) and the tooth pins (11) for bearing the tooth pins (11), and wherein, on a side facing the tooth pins, the bearing segments (17) have an elevation at least in sections formed as a spherical cap for bearing the respective tooth pin (11).

Claims

1. A coaxial gear (1), comprising an axially oriented tooth system (5) with respect to a rotational axis (3) of the coaxial gear (1), a tooth carrier (7) having axially oriented guideways (9), tooth pins (11) received within the guideways (9) for engaging with the tooth system (5), wherein the tooth pins (11) are axially oriented within the guideways (9) by their respective longitudinal axes and are mounted within the guideways (9) in an axially displaceable manner, and a cam disc (15) rotatable about the rotational axis (3) for axially driving the tooth pins (11), wherein a plurality of bearing segments (17) is disposed between the cam disc (15) and the tooth pins (11) for bearing the tooth pins (11), and wherein, on a side facing the tooth pins, the bearing segments (17) have an elevation (19) formed as a spherical cap for bearing the respective tooth pin (11).

2. The coaxial gear (1) according to claim 1, wherein rolling elements (27) are disposed between the cam disc (15) and the bearing segments (17).

3. The coaxial gear (1) according to claim 2, wherein a center point of the spherical cap coincides with a center of a running surface of the bearing segment.

4. The coaxial gear (1) according to claim 2, wherein the rolling elements are formed as cylindrical rollers.

5. The coaxial gear (1) according to claim 1, wherein the tooth pin (11) on its tooth base on the side of the bearing segment has a recess (21) formed as a concave spherical shape.

6. The coaxial gear (1) according to claim 5, wherein a radius of the spherical cap of the elevation of the bearing segment is different from a sphere radius of the spherical shape of the tooth base of the tooth pin (11).

7. The coaxial gear (1) according to claim 2, wherein the rolling elements are kept in a cage (26), which is suitable to follow a stroke of the cam disc in a permanently elastic manner.

8. The coaxial gear (1) according to claim 1, wherein the bearing segments (17) have spaced side edges each running along a radius.

9. The coaxial gear (1) according to claim 8, wherein the bearing segments have a running surface facing away from the tooth pins, which respectively have introduction chamfers (24) in the area of the edges.

10. The coaxial gear (1) according to claim 1, wherein the tooth pins (11) each have a widened head area (51) as compared to a tooth body of the tooth pins (11).

11. The coaxial gear (1) according to claim 1, wherein the cam disc (15) has a profiling (25) having a variable inclination angle of up to 10° of a vertical line (45) of the profiling towards the rotational axis (3).

12. The coaxial gear (1) according to claim 1, further comprising an anti-twist ring (29) disposed between the tooth pins (11) and the bearing segments (17).

13. The coaxial gear (1) according to claim 12, wherein the tooth pins (11) have a circular tooth body in cross-section, and a non-circular cross-section in an area of a tooth base for engaging with a correspondingly shaped opening in the anti-twist ring (29).

14. The coaxial gear (1) according to claim 12, wherein the anti-twist ring (29) prevents the bearings segments (17) from twisting relative to one another.

15. The coaxial gear (1) according to claim 12, wherein the anti-twist ring (29) comprises lugs in a direction of the cam disc (15) for positionally securing the bearing segments (17).

16. The coaxial gear (1) according to claim 1, wherein the bearing segments (17) are realized as circular ring portions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Hereinafter, the invention will be explained in more detail on the basis of the appended drawings, wherein the Figures show:

(2) FIG. 1 shows a typical embodiment of the coaxial gear in a partially schematic sectional view;

(3) FIG. 2 shows a schematic view of the rolling elements and the cage of the embodiment of FIG. 1;

(4) FIG. 3 shows a schematic view of the bearing segments, the tooth pins and the anti-twist ring of the embodiment of FIG. 1;

(5) FIG. 4 shows a schematic view of the anti-twist ring of FIG. 3;

(6) FIG. 5 shows a schematic view of a bearing segment of FIG. 3;

(7) FIG. 6 shows a further schematic view of a bearing segment of FIG. 3;

(8) FIG. 7 shows a tooth pin of FIG. 3 in a schematic view; and

(9) FIG. 8 shows a further typical embodiment of the coaxial gear in a schematic sectional view.

DETAILED DESCRIPTION

(10) In the following, typical embodiments of the invention will be described on the basis of the Figures, with the invention not being restricted to the exemplary embodiments, the scope of the invention being rather determined by the claims.

(11) In the description of the embodiments, identical reference numerals for identical or similar parts are possibly used in various Figures and for various embodiments. In part, features already described in conjunction with other Figures are not mentioned or described repeatedly for reasons of clarity. For the purpose of clarity, partially not all of the respective features, for example the bearing segments or the tooth pins, are provided with a reference numeral.

(12) In FIG. 1, a section of a typical embodiment of the invention is illustrated in a schematic sectional view. FIG. 1 shows a part of a coaxial gear 1 having a tooth system 5 oriented with respect to a rotational axis 3 of the coaxial gear 1. The tooth system 5 is realized as a tooth system of a crown wheel 18 revolving about the rotational axis 3. The crown wheel 18 is connected to a housing 31 of the coaxial gear 1 in a rotationally fixed manner.

(13) The coaxial gear 1 comprises a tooth carrier 7, which is provided on an output shaft 34. The output shaft 34 is mounted on the housing 31 via a first bearing 33 to be rotatable about the rotational axis 3. The tooth carrier has axially oriented guideways 9, in each of which tooth pins 11 are accommodated. The tooth pins 11 are mounted along their respective longitudinal axes 13 within the guideways 9 to be axially displaceable with respect to the rotational axis 3.

(14) The tooth pins each comprise a tooth head oriented for engaging with the tooth system 5, and a tooth base protruding from the guideway 9 of the respective tooth pin 11 and being mounted on a bearing segment 17. A tooth pin 11 furthermore comprises a tooth body between the tooth base and the tooth head, with the tooth body being at least in part accommodated within the guideway 9 of the tooth pin 11.

(15) The tooth base of the tooth pin 11 having a recess 21 is mounted on a partially spherical cap-shaped elevation 19 of the bearing segment 17.

(16) The bearing segments 17 each are mounted with a running surface 23 on their side facing away from the tooth pins on a roller bearing having rolling elements 27, which bearing is in turn mounted on a profiling 25 of a cam disc 15 of the coaxial gear 1. Of the roller bearing in FIG. 1 substantially a web of the cage 26 for the rolling elements 27 (these are partially obscured) can be seen in a cut. The rolling elements 27 are realized as needle rollers. In further embodiments, the rolling elements may be realized as cylinder rollers.

(17) In FIG. 2, the cage 26 having the rolling elements 27 is again illustrated for better clarity. Like the anti-twist ring 29, the cage is made of permanently elastic plastics.

(18) The cam disc 15 is provided on a drive shaft 36. The drive shaft 36 is mounted via a second bearing 35 rotatable about the rotational axis 3 on the tooth carrier 7 and thus indirectly on the housing 31 as well. The cam disc 15 is mounted via an axial bearing 32 by needle rollers with respect to the housing 31.

(19) The profiling 25 of the embodiment of FIG. 1 is realized to be revolving around the rotational axis 3 and has two axial elevations in the direction of the tooth pins 11.

(20) The profiling 25 has a variable inclination angle in the radial direction (straight line 45 in FIG. 1) to the rotational axis 3. The inclination angle designates the radially oriented proportion of the angle of a straight line perpendicular to the profiling at one point, which is the profiling vertical line 46, with respect to the rotational axis 3 of the coaxial gear.

(21) In typical embodiments, the profiling rises and falls circumferentially in the axial direction, wherein the top surface or the profiling tilts radially to the inside and to the outside. The profiling typically tilts radially inwards at the elevations, into which the teeth of the tooth system are pushed in. The profiling tilts radially to the outside in particular between the elevations, when the teeth are pulled out from the tooth system. In typical embodiments, there is a a continuous transition of the inclination angle in between in each case.

(22) In FIG. 3, the bearing segments 17, the anti-twist ring 29, and the tooth pins 11 without tooth carriers and other components are shown for better clarity. The bearing segments are non-displaceable relative to the anti-twist ring 29, whereby they are prevented from twisting by inner lugs 28 and outer lugs 30 of the anti-twist ring 29.

(23) In each case one of the inner lugs 28 supports a respective inner edge of a bearing segment 17 with respect to a radially inwards displacement. The radially outer corners 41 (see FIG. 5 and FIG. 6) of the bearing segments 17 are each flattened so as to be in engagement with the outer lugs 30 which are triangular in cross-section, so that a radially outwards movement and twisting are prevented in each case. Thereby, one of the outer lugs 30 is in engagement with two bearing segments 17 in each case.

(24) Further details of the bearing segments 17, the anti-twist ring 29, and the tooth pins 11 will be explained in conjunction with the further FIGS. 4 to 7.

(25) The anti-twist ring 29 is schematically illustrated in FIG. 4. The anti-twist ring has the inner lugs 28 and the outer lugs 30. Moreover, the anti-twist ring 29 has in each case an opening 38 for each of the tooth pins 11 (see FIG. 3, for example). At their radially outer sides, the openings 38 have a molding 39, which is straight in sections and protrudes into the otherwise circular ring-shaped cross-section of the opening 38. Each of the moldings 39 interacts respectively with a flattening of a tooth pin 11 (see FIG. 7).

(26) In embodiments, an engagement with the correspondingly shaped opening having the molding may be performed by means of a non-circular cross-section of the tooth pin in the area of the tooth base, so that an anti-twist protection of the tooth pin about its longitudinal axis is achieved.

(27) In FIG. 5 and FIG. 6, a bearing segment 17 is in each case schematically shown from “below” (FIG. 5) and from “above” (FIG. 6). The flattened radially outer corners 41 are each disposed between a radially outer edge of a bearing segment 17 and one of the two edges pointing into the direction of revolution, and serve for engaging with the outer lugs 30 of the anti-twist ring.

(28) As shown in FIG. 5, introduction chamfers 24 are present on the edges pointing in the direction of revolution in each case on the side of the running surface 23, which, by means of a rounded transition, facilitate an arrival of the rolling elements below the bearing segments 17.

(29) In FIG. 6, the elevation 19 having the spherical cap-shaped portion is shown, which is disposed to be approximately central of the bearing segment 17. The edges pointing in the direction of revolution are not realized at a right angle to the other two edges, but are straight in the radial direction after having been inserted into the anti-twist ring. Due to the circular ring-shaped arrangement originating as a result of this, the bearing segments 17 can cover a largest possible surface and contribute to the running smoothness of the rolling elements.

(30) In FIG. 7, a tooth pin 11 is schematically shown in an inclination view. The tooth pin 11 has a concave recess 21 on the tooth base, and a widened head area 51 having a plurality of teeth 52. By means of the widened head area 51, several teeth 52 are brought into engagement with the crown wheel 18, so that high torque can be transmitted via the teeth. Moreover, the flattening 53 in the area of the tooth base can be recognized in FIG. 7, by means of which twisting of the tooth pin 11 is prevented by engaging with the molding in a respective opening of the anti-twist ring.

(31) FIG. 8 shows a coaxial gear 201, which is similar to the coaxial gear 1 shown in FIG. 1, therefore only differentiating parts will be explained here. For a better visibility the anti-twist ring 29 is not shown in FIG. 8.

(32) The coaxial gear 201 of FIG. 8 comprises a setting element 216, which rests axially on an abutment bearing pot 218.

(33) The abutment bearing pot 218 has a through opening for bushing of an input shaft 115, which is fixed to the cam disc 15.

(34) In contrast to the embodiment of FIG. 1, the embodiment of FIG. 8 shows cam disc 15 and input shaft 115 being two pieces, not integral.

(35) In contrast to the embodiment of FIG. 1, the embodiment of FIG. 8 uses a deep groove ball bearing 235 as a second bearing 35.

(36) On its outer circumference the abutment bearing pot 218 rests on an inner surface of a housing 131, which has a cylindrical form, and can be axially displaced along the housing 131. The ring shaped setting element 216 rests on the bottom of the abutment bearing pot 218 and serves for bearing of the rolling bodies 54, which are bearing the cam disc 15.

(37) The abutment bearing pot 218 in turn is axially supported by a positioning nut 220, which can be moved axially by screwing into the housing 131, and is therefore adjustable in relation to a tooth carrier or an input shaft.

(38) By axial adjustment of the positioning inside the housing the components of the coaxial gear, like setting element, abutment port, teeth, bearing segments, cam disc, rolling bodies, housing, tooth carrier or the toothing systems need not to be specially selected in regard to their axial thickness, to adjust a backlash of the coaxial gear.