Rotary bearings and gearboxes

Abstract

The present invention relates to a rotary bearing (50), particularly for a harmonic drive device, having an outer rotary bearing ring (1b) and an inner rotary bearing ring (1a) arranged in the outer rotary bearing ring, wherein the inner rotary bearing ring (1a) and the outer rotary bearing ring (1b) are each provided with at least one receiving portion (10, 11), through which a rolling element (8) is placed into a rolling bearing between the rotational support surface (7) of the inner rotary bearing ring (1a) and the rotational support surface (9) of the outer rotary bearing ring (1b) through a receiving port formed by the two receiving portions (10, 11) at corresponding positions between the two receiving portions (10, 11), wherein a guide ring (20) for the rolling element (8) is arranged between the receiving port and the rolling element (8) in at least one of the two receiving portions (10, 11).

Description

Technical Field

[0001] This invention relates to a rotary bearing. This invention also relates to a gearbox. Background Technology

[0002] This type of rotary bearing is particularly suitable for providing rotary support for strain wave drives, where the rotary bearing and the strain wave drive constitute a gearbox. Such gearboxes have diverse applications in many technical fields. In particular, they are increasingly used in robotics and prosthetics. One example of this is the Harmonic Drive® transmission, which belongs to the strain wave drive category.

[0003] The drive component, designed as an elliptical wave generator, deforms an externally toothed flexible spline transmission component via ball bearings. This transmission component meshes with an internally toothed, circularly splined wheel in the opposite region of the large elliptical axis. As the wave generator rotates, the large elliptical axis, and consequently the toothed meshing region, shifts. Since the flexible spline of the HarmonicDrive® transmission typically has two fewer teeth than the circular spline, the relative movement between the flexible and circular splines progresses by one tooth during half a rotation of the wave generator and by two teeth during a full rotation. When the circular spline is fixed, the flexible spline rotates as a driven element in the opposite direction to the drive component. Here, the circular spline can be fixedly arranged in a rotating bearing ring.

[0004] To achieve rotational movement between the two components, this strain wave drive is placed on a rotary bearing ring, which is rotatably mounted on it. Here, on one hand, the wheel of the strain wave drive can be arranged torsionally against the rotary bearing ring, with rolling elements positioned between the rotary bearing ring and the rotational support surface of the transmission component, thus ensuring the rotatability of the strain wave drive relative to the rotary bearing ring. On the other hand, the transmission component of the strain wave drive can also be arranged torsionally against the rotary bearing ring, with rolling elements positioned between the rotary bearing ring and the rotational support surface of the wheel, thus also ensuring the rotatability of the strain wave drive relative to the rotary bearing ring.

[0005] AT 129 151 B discloses a single-row or multi-row full complement radial ball bearing. A guide ring with an angular cross-section is mounted or inserted into the inner or outer ring.

[0006] US 1,212,253 A discloses a rotary bearing with two bearing rings and a guide ring for rolling elements.

[0007] CH 38 509 A describes a ball bearing with two concentric rings and a guide ring for rolling elements.

[0008] As disclosed in DE 10 2015 104 308 A1, the rotary bearing of the aforementioned transmission device mounting kit is configured such that the wheel or transmission component and the rotary bearing ring each have at least one receiving portion, through which a rolling element can be introduced into the rolling bearing between the rotary bearing surface of the wheel or transmission component and the rotary bearing ring in the corresponding positions of the two receiving portions relative to each other.

[0009] The drawback of this design is that when the driven part rotates, the rolling elements may fall out of the middle space, thereby impairing the function of the rotary bearing and causing it to seize. Summary of the Invention

[0010] Therefore, the object of the present invention is to improve the aforementioned rotary bearing as follows. Furthermore, an improved gearbox should also be provided.

[0011] In the case of rotary bearings, the aforementioned task is accomplished by rotary bearings according to the invention. Advantageous embodiments of the invention are derived from the description and drawings.

[0012] According to the present invention, a guide ring for the rolling element is arranged in at least one of the two receiving portions between the receiving port and the rolling element.

[0013] This invention is based on the consideration that rolling elements should be absolutely prevented from detaching from the bearing. In particular, replacing a rotating bearing is extremely time-consuming in hard-to-reach installation situations. Furthermore, bearing failure and seizure can lead to dangerous situations.

[0014] As is now recognized, the rolling elements can be prevented from falling off by means of a guide ring, which restricts the movement of the rolling elements toward the receiving port in the axial direction.

[0015] The rotary bearing is preferably designed as a four-point bearing. Four-point bearings can be very compact and can absorb high overturning moments in addition to pure axial and radial forces. This is particularly advantageous for the support of the strain wave drive device described herein.

[0016] Advantageously, a sealing ring, particularly a radial shaft seal ring, is arranged in at least one of the two containers, preventing axial movement of the guide ring toward the receiving port. In some applications, used lubricant may migrate within the transmission, for example, reaching the rotating bearings and penetrating the bearing clearances present therein. When necessary, the bearing clearances can be sealed by means of an external radial shaft seal ring to prevent the ingress of unwanted material or leakage of rolling bearing grease. Simultaneously, the radial shaft seal ring can axially support the guide ring.

[0017] Preferably, an expansion ring is provided in at least one of the two receiving sections, which can prevent the guide ring from moving axially toward the receiving port. This makes it possible to achieve a simple and cost-effective axial fixation of the guide ring using standard machine parts.

[0018] According to the invention, the guide ring is implemented in the form of a screw with external threads that engage with internal threads formed in an outer rotating bearing ring.

[0019] In a design that does not conform to this invention, the guide ring is axially fixed to the outer diameter of the outer bearing ring by compressive stress (interference). In this cost-effective fixation, there is no need to manufacture threads, grooves, or the like.

[0020] The guide ring is preferably made of plastic or steel. Production using plastic is particularly cost-effective.

[0021] In one embodiment that does not conform to the present invention, the guide ring and the flat seal are integrated. In this configuration, the separate component of the seal can be omitted, and the manufacturing process of the rotary bearing is simplified. For example, the metal ring used as the guide ring can be integrated into the flat seal, which is constructed as an elastomer.

[0022] Regarding the gearbox, the above task is accomplished by a gearbox having an expansion ring arranged in at least one of the two receiving sections, which prevents the guide ring from moving axially toward the receiving port.

[0023] Here, the term "gearbox" preferably refers to an open or closed housing in which transmission components (gears) are supported on shafts with bearings or seals.

[0024] Advantageously, the wheel or circular spline forms an outer rotary bearing ring. This results in a compact gearbox that can be used in a variety of applications.

[0025] In a preferred embodiment, the inner rotary bearing ring is designed as a clutch wheel with internal teeth having the same number of teeth as the external teeth of the transmission component, wherein the internal teeth of the clutch wheel mesh with the external teeth of the transmission component. This transmission device structure allows for a very compact axial configuration. Attached Figure Description

[0026] Further objectives, advantages, features, and applications of the present invention will become apparent from the following description of embodiments with the aid of the accompanying drawings. Here, all the features described and / or illustrated, either alone or in any meaningful combination, constitute the subject matter of the invention.

[0027] In the attached image:

[0028] Figure 1A first preferred embodiment of the rotary bearing forming a gearbox of the present invention is shown in cross-sectional view, having a strain wave transmission device supported therein;

[0029] Figure 2 A second preferred embodiment of the gearbox of the present invention is shown in cross-sectional view;

[0030] Figure 3 A third preferred embodiment of the gearbox of the present invention is shown in cross-sectional view;

[0031] Figure 4 A fourth preferred embodiment of the gearbox of the present invention is shown in cross-sectional view;

[0032] Figure 5 A fifth preferred embodiment of the gearbox of the present invention is shown in cross-sectional view; and

[0033] Figure 6 A sixth preferred embodiment of the gearbox of the present invention is shown in cross-sectional view.

[0034] In all the drawings, the same parts are labeled with the same reference numerals. Detailed Implementation

[0035] exist Figure 1 The cross-sectional view shows an embodiment of the rotary bearing 50 of the present invention in an assembled state and a strain wave transmission device 40 mounted therein, which together constitute a gearbox 70. Here, a transmission component 4 designed as a flexible spline is mounted on a drive component 2 designed as an elliptical wave generator, which is preferably supported on a hollow shaft, wherein the transmission component 4 is also elliptical in shape by the elliptical drive component 2. The external teeth 3 of the elliptical-shaped transmission component 4 mesh with the internal teeth 5 of a wheel 6 designed as a circular spline in the opposite region of the large elliptical axis.

[0036] Wheel 6 has the largest axial extension of all components in the gearbox 70. In the embodiment described herein, the drive component 2 is designed as an elliptical wave generator. The elastic transmission component 4 is designed as a flexible spline, which is mounted on the transmission component 2 via ball bearings 16 having a plurality of balls 17. Due to the elasticity in its outer tooth region 3, the transmission component 4 also undergoes elliptical deformation due to the elliptical shape of the drive component 2.

[0037] Because the elastic transmission component 4 has external teeth 3 and undergoes elliptical deformation, these external teeth 3 mesh with the internal teeth 5 of the circular spline wheel 6 in the region of the large elliptical axis. The wheel 6 has an inner surface formed as a rotary support surface 9, which corresponds to the outer surface of the rotary support surface 7 formed as an inner rotary bearing ring 1a. The rotary bearing ring 1a has internal teeth with the same number of teeth as the transmission component 4, thus functioning as a clutch (or coupling device) (without speed reduction).

[0038] Here, a rolling bearing is arranged between the two rotating support surfaces 7 and 9 of the wheel 6 and the inner rotating bearing ring 1a. The rolling bearing has a plurality of rolling elements 8, wherein the rotating support surfaces 7 and 9 of the wheel 6 and the inner rotating bearing ring 1a are formed as raceways 12 for the rolling elements 8 of the rolling bearing. The wheel 6 is the outer rotating bearing ring 1b of the rotating bearing 50.

[0039] To achieve a very narrow and compact design of the gearbox 70, a receiving portion 10 is provided in the rotational support surface 7 of the wheel 6 or the outer rotary bearing ring 1b, and a receiving portion 11 is provided in the rotational support surface 9 of the inner rotary bearing ring 1a. Here, the two receiving portions 10 and 11 correspond to each other, such that they are oriented accordingly to form a shape-fitting receiving of the rolling element 8, forming a feed channel 24 with a receiving port 22. The shape-fitting receiving of the rolling element 8 allows the rolling bearing between the wheel 6 and the rotary bearing ring 1 to be filled with the rolling element 8 through the feed channel 24, thereby enabling the wheel 6 to be supported relative to the rotary bearing ring 1a without clearance and allowing the rotary bearing ring 1a and the wheel 6 to rotate relative to each other. In this position, the transmission component 4, designed as a flexible spline, can now be driven by the drive component 2, designed as a wave generator, thereby causing relative movement between the wheel 6 and the transmission component 2. In this example, the rolling element 8 is constructed as a ball.

[0040] The flexible spline or transmission component 4 engages with the wheel 6 or circular spline and also with the clutch wheel 13 (or coupling wheel) or dynamic spline, wherein the clutch wheel is identical to the rotary bearing ring 1a and has internal teeth. The number of teeth on the internal teeth of the clutch wheel 13 is the same as the number of teeth on the external teeth 3 of the transmission component 4. In this way, the clutch wheel 13 functions as a clutch (or coupling device) without deceleration.

[0041] The components of gearbox 70, namely the inner rotary bearing ring 1a, the drive component 2, the transmission component 4, and the wheel 6, are arranged coaxially around the central longitudinal axis 15 of gearbox 70. Through the shape-fitting design of the wheel 6 and the rolling elements 8 and receiving portions 10 and 11 of the inner rotary bearing ring 1a, a very compact and narrow gearbox 70 in the axial direction can now be provided. This is particularly useful in applications where very little installation space is available to achieve rotary motion, especially in many applications such as robotics and prosthetics, where simple assembly of gearbox 70 can be achieved.

[0042] The rotary bearing 50 is optimized for high reliability and lifespan. To prevent the rolling elements 8 from falling out of the feed channel 24 or the receiving sections 10, 11, a guide ring 20 is arranged in the receiving section 10 of the rotary bearing ring 1b. According to... Figure 5 and Figure 6 The implementation schemes of the rotary bearings also include receiving parts 10 and 11 respectively.

[0043] Guide ring 20, receiving section 10, 11 and feeding channel 24 are in Figure 1 The figure is shown in enlarged view 80. A radial shaft seal 21 is arranged in the feed channel 24 between the guide ring 20 and the receiving port 22 in the axial direction, which can prevent axial movement of the guide ring 20 in the direction of the receiving port 22. The guide ring 20 has an annular, axially extending protrusion 41 that contacts the rolling element 8. The protrusion 41 preferably has a small contact surface that contacts the rolling element 8 during operation so as to minimize the friction between the guide ring 20 and the rolling element 8.

[0044] The radial shaft seal, designed as a radial shaft seal ring, is supported radially on the shoulder 43 inside the outer bearing ring 1b and is opposed to and sealed with a sealing edge 45 on the side of the inner bearing ring 6 designed as a sealing surface 44.

[0045] In this way, the guide ring 20 holds the rolling element 8 in the annular gap 23 and prevents the rolling element from falling out of the feed channel 24 even if the rotary bearing 50 is moved or rotated, so that the rolling element 8 will not fall out of the annular cavity 23 even if the feed channel 24 is oriented vertically downward. The guide ring 20 is preferably made of plastic (inexpensive) or also of steel.

[0046] Figure 2-4 The gearboxes 70 shown differ from each other only in the design type of the guide rings 20 or the receiving parts 10, 11 and the components arranged therein.

[0047] exist Figure 2Another preferred embodiment of the gearbox 70 is shown, which has a rotary bearing 50 and a strain wave transmission device 40. In this embodiment, an expansion ring 25 is arranged in the receiving portion 10. The expansion ring 25 is arranged in the radially outer region of the radial groove 26 of the wheel 6 and is therefore fixed radially and axially. The expansion ring prevents the guide ring 20 from moving toward the receiving port 22. The guide ring 20 is preferably made of plastic or steel. A radial shaft seal 21 is also present in this embodiment.

[0048] exist Figure 3 Another preferred embodiment of the gearbox 70 with a rotary bearing 50 and a strain wave drive 40 is shown. In this embodiment, the guide ring 20, preferably made of steel, is constructed in a helical shape with an external thread 27 that engages with a corresponding internal thread 28 in the wheel 6.

[0049] exist Figure 4 Another preferred embodiment of the gearbox mounting kit 70 is shown, which has a rotary bearing 50 and a strain-wave gearbox 40. The guide ring 20 is preferably made of plastic, but may also be made of steel, and is axially fixed to the outer diameter of the wheel 6 by press fit or interference fit. Adhesive bonding of the guide ring is also possible.

[0050] Figure 5 Another preferred embodiment of the gearbox 70 is shown, which has a rotary bearing 50 and a strain wave drive 40 having a wheel 6 or a circular spline configured as an internal gear, the latter overlapping and regionally meshing with the external teeth 3 of the transmission component 4 or the flexible spline in the region of its internal teeth 5.

[0051] The transmission component 4 is torsionally connected to the outer swivel bearing ring 1b of the swivel bearing 50, which rotatably supports the transmission component 4 and the wheel 6. The inner swivel bearing ring 1a of the swivel bearing 50 is torsionally connected to the circular spline / wheel 6.

[0052] The transmission component 4 is elliptically deformed by the elliptical drive component 2. The elliptically deformed transmission component 4 has its external teeth 3 meshing with the internal teeth 5 of the wheel 6, which is designed as a circular spline, in the opposite region of the large elliptical axis. In the embodiment described herein, the drive component 2 is designed as an elliptical wave generator. The elastic, flexible spline-constructed transmission component 4 is mounted on the drive component 2 via ball bearings 16 having multiple balls 17. Due to the elasticity in the region of its external teeth 3, the transmission component 4 also deforms elliptically due to the elliptical shape of the drive component 2.

[0053] In this embodiment, the guide ring 20 is designed or integrated into the inner seal or flat seal. The flat seal and the guide ring 20 are formed as a single component or integrally constructed. In this embodiment, the guide ring 20 is preferably formed of a composite material, which is preferably composed of an elastomer and plastic / steel.

[0054] exist Figure 6 Another preferred embodiment of the gearbox 70 with a rotary bearing 50 and a strain wave drive 40 is shown, which is consistent with... Figure 5 The illustrated implementation differs only in the design of the guide ring. Here, only one guide ring 20 is provided, without dynamic sealing. The guide ring 20 can be implemented as a pure plastic ring, or it can be made of a composite material of elastomer and plastic / steel, thus also serving as a static O-ring seal between the rotary bearing ring 1b and the transmission component 4.

[0055] List of reference numerals

[0056] 1a Inner rotating bearing ring

[0057] 1b External rotating bearing ring

[0058] 2. Drive components

[0059] 3. External teeth

[0060] 4. Transmission components

[0061] 5. Internal teeth

[0062] 6 wheels

[0063] 7 Rotating support surface

[0064] 8 Rolling elements

[0065] 9 Rotating support surface

[0066] 10 Receiving Section

[0067] 11 Receiving Department

[0068] 13. Clutch wheel

[0069] 15. Central Axis

[0070] 16 ball bearings

[0071] 17 balls

[0072] 20 guide rings

[0073] 21 Radial shaft seal

[0074] 22 Receiver Port

[0075] 23 Annular gap

[0076] 24 Feeding Channel

[0077] 25. Increase Circle

[0078] 26 slots

[0079] 27 External thread

[0080] 28 internal thread

[0081] 40 Strain Wave Transmission Device

[0082] 41. Protrusion

[0083] 43. Protruding shoulder

[0084] 44 Sealing surface

[0085] 45 Sealing edge

[0086] 50 Rotary Bearing

[0087] 70 Gearbox.

Claims

1. A rotary bearing (50), particularly for a harmonic drive device, having an outer rotary bearing ring (1b) and an inner rotary bearing ring (1a) disposed therein, wherein the inner rotary bearing ring (1a) and the outer rotary bearing ring (1b) each have at least one receiving portion (10, 11), through which a rolling element (8) can be inserted into a rolling bearing between the rotational bearing surface (7) of the inner rotary bearing ring (1a) and the rotational bearing surface (9) of the outer rotary bearing ring (1b) at corresponding positions between the two receiving portions (10, 11) via a receiving port (22) formed by the two receiving portions (10, 11). Its characteristics are, exist At least one of the two receiving parts (10, 11) has a guide ring (20) for the rolling element (8) arranged between the receiving port and the rolling element (8). The guide ring (20) has an annular, axially extending protrusion (41) that contacts the rolling element (8). The protrusion (41) has a small contact surface that contacts the rolling element (8) during operation so that the friction between the guide ring (20) and the rolling element (8) is minimized.

2. The rotary bearing (50) according to claim 1, wherein, A sealing ring, particularly a radial axial sealing ring (21), is arranged in at least one of the two receiving parts (10, 11) to prevent the guide ring (20) from axially moving toward the receiving port (22).

3. The rotary bearing (50) according to claim 1, wherein, An expansion ring (25) is arranged in at least one of the two receiving parts (10, 11) to prevent the guide ring (20) from moving axially toward the receiving port (22).

4. The rotary bearing (50) according to claim 1, wherein, The guide ring (20) is implemented in the form of a screw with an external thread (27) that engages with an internal thread (28) formed in the outer rotary bearing ring (1b).

5. The rotary bearing (50) according to claim 1, wherein, The guide ring (20) is axially fixed on the outer diameter in the outer rotating bearing ring (1b) by press fitting.

6. The rotary bearing (50) according to any one of claims 1 to 5, wherein, The guide ring (20) is made of plastic or steel.

7. The rotary bearing (50) according to claim 1, wherein, The guide ring (20) is integrated with the flat seal.

8. The rotary bearing (50) according to claim 1, wherein, In the at least one receiving part (10, 11), only a guide ring (20) is arranged and no separate seal is arranged.

9. A gearbox (70) comprising a rotary bearing (50) according to any one of the preceding claims and a strain wave transmission device (40) supported therein, the strain wave transmission device having a drive component (2), a resilient transmission component (4) having external teeth (3), and a wheel (6) having internal teeth (5), wherein, The transmission component (4) can be inserted into the drive component (2) and can be deformed elliptically by the drive component (2) such that the external teeth (3) of the transmission component (4) can mesh with the internal teeth (5) of the wheel (6) in the opposite region of the large elliptical axis.

10. The gearbox (70) according to claim 9, wherein, The wheel (6) forms an outer rotating bearing ring (1b).

11. The gearbox (70) according to claim 9 or 10, wherein, The inner rotating bearing ring (1a) is formed as a clutch wheel (13) having an internal toothed portion having the same number of teeth as the external toothed portion (3) of the transmission component (4), wherein the internal toothed portion of the clutch wheel (13) meshes with the external toothed portion (3) of the transmission component (4).

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