Flexible transmission element

Abstract

A flexible transmission element (1) which can be used, in particular in a harmonic drive (9) and which includes a sleeve-shaped, outer toothed section (3) and a flange (4) connected to this section (3), the outer toothing (8) of the sleeve-shaped section (3) is sheet metal toothing formed in a die.

Claims

1. A method for producing a flexible transmission element, comprising the following steps: preparing an unprocessed part, which has a sleeve-shaped section with a radially inwardly directed thicker section and a thinner base section axially adjacent to the thicker section, pressing material located in the thicker section radially outwardly into an inner-toothed die, and forming outer toothing of the transmission element only in the thicker section.

2. The method according to claim 1, wherein the material of the thicker section is pressed into the die exclusively from an inside of the unprocessed part until reaching a final contour of the outer toothing.

3. The method according to claim 1, further comprising forming a smooth, cylindrical inner contour of the sleeve-shaped section by forcing the material of the thicker section outwardly.

4. A method for producing a flexible transmission element, comprising the following steps: preparing an unprocessed part, which has a sleeve-shaped section with a radially inwardly directed thicker section, forming the unprocessed part having the thicker section with an increased thickness compared to a base band thickness of a sheet metal band, by deep drawing, pressing material located in the thicker section radially outwardly into an inner-toothed die, and forming outer toothing of the transmission element.

5. The method according to claim 2, further comprising forming a flange connected to the sleeve-shaped section, and forming openings in the flange by non-cutting processing.

6. The method according to claim 4, further comprising forming a flange connected to the sleeve-shaped section, and forming openings in the flange by non-cutting processing.

7. The method according to claim 4, wherein the material of the thicker section is pressed into the die exclusively from an inside of the unprocessed part until reaching a final contour of the outer toothing.

8. The method according to claim 4, further comprising forming a smooth, cylindrical inner contour of the sleeve-shaped section by forcing the material of the thicker section outwardly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An embodiment of the invention is explained below in more detail with reference to a drawing. Shown herein are:

(2) FIG. 1 an unprocessed part provided for producing a flexible transmission element,

(3) FIG. 2 a cross section through the unprocessed part according to FIG. 1,

(4) FIG. 3 a detail of the unprocessed part according to FIG. 1,

(5) FIG. 4 a flexible transmission element produced from the unprocessed part in a view analogous to FIG. 1,

(6) FIG. 5 the transmission element according to FIG. 4 in a cross section analogous to FIG. 2,

(7) FIG. 6 the flexible transmission in perspective view, and

(8) FIG. 7 a harmonic drive with the flexible transmission element.

DETAILED DESCRIPTION

(9) FIGS. 1 to 3 show an unprocessed part 2 that is formed as a sheet metal part and shows the base part for producing a flexible transmission element designated with 1 according to FIGS. 4 to 6. Just like the final transmission element 1, the unprocessed part 2 already has the shape of a hat with a cylindrical sleeve section 3 and a flange 4 directed radially outwardly from this section.

(10) A radially inwardly directed material buildup 5, also called thicker section for short, is located on the end side of the unprocessed part 2 facing away from the flange 4. The outer periphery of the sleeve-shaped section 3, called sleeve section for short, is, in contrast, apart from a transition region to the flange 4, completely cylindrical, that is, has no steps or other changes in the diameter. The smooth, cylindrical sleeve section 3 is inserted into a not-shown die, whose inner periphery is also cylindrical to a large degree in one possible construction. In the same section of the die in which the sleeve section 3 has the material buildup 5 on the inner side, there is a tooth structure in the die that contacts the smooth outer surface of the sleeve section 3.

(11) Then a radially outwardly acting pressure is exerted on the thicker section 5 by a tool that can rotate relative to the unprocessed part 2. This leads to a continuous displacement of the material of the thicker section 5 into the tooth structure of the die.

(12) As a result of this shaping process, outer toothing designated with 8 is formed on the lateral surface of the sleeve section 3. The inner wall of the sleeve section 3 of the flexible transmission element 1 finished in this way is, in contrast, cylindrical. The pressing of the toothing 8 in the die from the inner side of the unprocessed part 2 leads to an enhanced load carrying capacity of the outer toothing 8. The tooth structure of the die is reproduced completely in the outer toothing 8 of the transmission element 1.

(13) The flange 4 of the transmission element 1 has, like the sleeve section 3, an elastic flexibility. The elastic flexibility of the flange 4 is promoted by elongated, curved cut-outs 6 that are distributed uniformly around the periphery of the flange 4. Each cut-out 6, in general also called opening, is located essentially radially inside of a fastener opening 7 that can also be produced, for example, by stamping just like each cut-out 6. The two ends of each cut-out 6 are made wider; the associated fastener opening 7 is located centrally between the two ends of the cut-out 6, wherein, viewed in the radial direction of the flange 4, there is an overlap between the ends of the cut-out 6 and the fastener opening 7. The flexible transmission element 1 thus also has, for tilting loads, a significant elastic flexibility, wherein there is simultaneously a high stiffness in the circumferential direction.

(14) The installation situation of the flexible transmission element 1, that is, the outer toothed collar sleeve, is shown in FIG. 7. The flexible transmission element 1 is a component of a harmonic drive that is designated with 9 and is used as a control gear in a motor vehicle.

(15) With screws 10 that each pass through a fastener opening 7, the flexible transmission element 1 is fastened to a housing 11 that is not allocated to the harmonic drive 9. When the harmonic drive 9 is operating, the sleeve section 3 is continuously deformed by a harmonic generator 12 that has an elliptical inner ring 13, an outer ring 14, and roller bodies 15, namely balls, rolling between the inner ring 13 and the outer ring 14. The outer ring 14 adapting continuously to the elliptical shape of the inner ring 13 is arranged radially directly within the outer toothing 8 of the flexible transmission element. The outer toothing 8 engages two diametrically opposite positions in inner toothing 16 of an inherently rigid driven ring gear 17 of the harmonic drive 9. A slightly different number of teeth of the inner toothing 16 on one side and the outer toothing 8 on the other side ensures that for one complete revolution of the inner ring 13, the driven ring gear 17 is rotated slightly relative to the flexible transmission element 1 and thus also relative to the housing 11. The driven ring gear 17 is connected locked in rotation to a shaft 19, that is, driven shaft, namely eccentric shaft or camshaft, by a stop washer 18. The common rotational axis of the shaft 19 and the harmonic drive 9 that corresponds to the center axis of the flexible transmission element 1, is designated with R.

LIST OF REFERENCE SYMBOLS

(16) 1 Flexible transmission element 2 Unprocessed part 3 Sleeve section 4 Flange 5 Material buildup, thicker section 6 Cut-out 7 Fastener opening 8 Outer toothing 9 Harmonic drive 10 Screw 11 Housing 12 Harmonic generator 13 Inner ring 14 Outer ring 15 Roller body 16 Inner toothing 17 Driven ring gear 18 Stop washer 19 Shaft R Rotational axis, center axis