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DE-102024133161-A1 - Wave gear

DE102024133161A1DE 102024133161 A1DE102024133161 A1DE 102024133161A1DE-102024133161-A1

Abstract

A wave gear (1) comprises a flexible toothed gear element (10) and a wave generator (5) for deforming this flexible gear element (10), which includes a rotatable, inherently rigid gear element (6) and rolling elements (8) that roll on a raceway (7) of this rigid gear element (6). The raceway (7) has a circular cross-section, and the different rolling elements (8) rolling on the raceway (7) have different diameters.

Inventors

  • Dominic Balling

Assignees

  • Schaeffler Technologies AG & Co. KG

Dates

Publication Date
20260513
Application Date
20241113

Claims (10)

  1. Wave gear (1), comprising a flexible toothed gear element (10) and a wave generator (5) provided for deforming this flexible gear element (10), which comprises a rotatable, inherently rigid gear element (6) and rolling elements (8) rolling on a raceway (7) of this rigid gear element (6), characterized in that the raceway (7) has a circular cross-section and different rolling elements (8) rolling on the raceway (7) have different diameters.
  2. Wave gear (1) according Claim 1 , characterized in that exactly two rolling elements (8) exist which have the largest diameter of all rolling elements (8), and these two rolling elements (8) are arranged diametrically opposite each other.
  3. Wave gear (1) according Claim 1 or 2 , characterized in that the rolling elements (8) contact an inner surface of the flexible gear element (10).
  4. Wave gear (1) according to one of the Claims 1 until 3 , characterized in that the rolling elements (8) are guided in a cage (9).
  5. Wave gear (1) according to one of the Claims 1 until 4 , characterized in that rollers are provided as rolling elements (8).
  6. Wave gear (1) according Claim 5 , characterized in that the rolling elements (8) are designed as cylindrical rollers.
  7. Wave gear (1) according Claim 5 , characterized in that the rolling elements (8) are designed as barrel rollers.
  8. Wave gear (1) according to one of the Claims 1 until 7 , characterized in that a flexring is provided as a flexible toothed gear element (10).
  9. Wave gear (1) according to one of the Claims 1 until 7 , characterized in that the flexible toothed gear element (10) describes a pot shape.
  10. Wave gear (1) according to one of the Claims 1 until 7 , characterized in that the flexible toothed gear element (10) describes a hat shape.

Description

The invention relates to a wave gear according to the preamble of claim 1, which can be used, for example, as an actuating gear of an electromechanical actuator. A typical wave gear is, for example, made from the DE 10 2019 106 338 B4 known. As in the DE 10 2019 106 338 B4 Depending on its design, a flexible toothed gear element of a wave gear can be, for example, a collar sleeve (i.e., a hat-shaped element) or a cup-shaped element. Similarly, the flexible toothed gear element of a wave gear can be a flex ring (i.e., a sleeve-shaped element without an inwardly or outwardly facing flange). A wave gear, which - like the wave gear after the DE 10 2019 106 338 B4 - has a spring element as a restoring element, for example in the DE 10 2019 119 727 A1 described. The documents US 2013/0316867 A1 and US 2013/0316868 A1 The diagram reveals wave gears with wave generators, each comprising several rollers of varying sizes that deform an elastic, externally toothed gear element. The rollers are individually mounted on a rotatable element of the wave generator, whereby in the case of the US 2013/0316868 A1 the rotation axes of the rollers are inclined relative to the central axis of the aforementioned rotatable element. The inherently elastically deformable gear element of a wave gear, also known as a stress wave gear, is sometimes also referred to as a stress element. An example of this is the following: DE 1 173 759 B referred. The invention is based on the objective of providing a wave gear that is further developed compared to the aforementioned prior art, whereby rational manufacturability with high mechanical precision and good space utilization is sought. This problem is solved according to the invention by a wave gear with the features of claim 1. The wave gear comprises, in a basic concept known per se, a flexible toothed gear element and a wave generator designed for deforming this flexible gear element. The wave generator has a rotatable, inherently rigid gear element and rolling elements that roll on a raceway of this rigid gear element. According to claim 1, the raceway of the inherently rigid gear element has a circular cross-section, wherein different rolling elements rolling on the raceway have different diameters. The circular cross-section of the rotating, rigid gear element significantly simplifies manufacturing compared to gear components with an oval cross-section. Furthermore, a separate inner bearing ring for the shaft generator is not required. Instead, the circular gear element itself acts as a rolling bearing inner ring. According to various possible configurations, there are exactly two rolling elements, which have the largest diameter of all the rolling elements, and these two rolling elements are arranged diametrically opposite each other. This means that during operation of the wave gear, only two circumferential sections of the flexible toothed gear element, which are offset from each other by 180 degrees, engage with the internal teeth of another, non-deformable gear element. Due to the rotation of the aforementioned rigid gear element, which is particularly well-designed as a shaft and permanently deforms the flexible gear element, the engagement areas between the flexible gear element and the internally toothed gear element migrate in the circumferential direction of the various, mutually concentric gear elements. The gear pairing formed by the flexible gear element and the internally toothed gear element thus exhibits partly the characteristics of a running gear and partly the characteristics of a splined gear. In a manner known per se, surfaces of the wave gear subjected to rolling stress can be hardened. These surfaces include the outer circumferential surface of the rotating, rigid gear element, which forms a circular raceway and contacts the differently dimensioned rolling elements, as well as the smooth inner surface of the flexible gear element and the partially meshing teeth of the various gear elements, which differ in their flexibility. Instead of the rolling elements rolling on the inner surface of the flexible gear element, a rolling contact between the rolling elements and the inner surface of a separate ring can also be provided. In such a case, the entire flexible gear element, or at least a section of this gear element provided with external teeth, can be designed around the separate ring should be placed without being firmly attached to it. Regardless of which optional elements are used to deform the flexible gear element with its varying diameters, configurations are also possible in which more than two engagement areas exist, where the teeth of the flexible gear element engage with the internal teeth of a non-deformable gear element. For example, if three or four engagement areas are provided, distributed at angular intervals of 120° or 90° respectively, then three or four rolling elements with maximum diameter are present. To maintain the rolling elements at equal in