Output bearing arrangement for an articulated drive, in particular a robotic articulated drive

Description

[0001] The present invention relates to an output bearing arrangement for a joint drive, in particular a robot joint drive, comprising an output shaft, an output bearing arranged on the output shaft with an inner ring for supporting the output shaft, a seal for sealing the joint drive and an output-side joint element, wherein the joint element is axially clamped to the output shaft by means of a clamping device and the clamping device of the joint element also axially clamps the inner ring of the output bearing.

[0002] In the joint drives of robot joints, such as those of a robot arm or robot leg, axial forces, radial forces, and tilting moments must be transmitted from one joint element to the next via a bearing. Simultaneously, the bearing must allow free rotation and the transmission of a torsional moment between the joint elements. Furthermore, the ingress of dust and water into the joint must be prevented, at least to a certain extent.

[0003] Joints, in particular robot joints and bearing arrangements for the joints or robot joints, are already known from the prior art. For example, KR 20170143396 A shows this. Figure 1 a robot joint with a bearing and a seal, wherein the seal is arranged on a sleeve which axially positions the inner bearing ring.

[0004] DE 102005035182 A1 shows in Figure 1A planetary gear for a joint with a bearing 120B and a seal 170, wherein the seal is arranged on a collar 168. The collar positions the inner bearing ring axially.

[0005] US Patent 2012 / 034022 A1 describes a robot arm assembly comprising a first segment, a second segment, a first drive device, a first transmission mechanism, a second drive device, and a second transmission mechanism. The second segment is rotatably connected to the first segment. The second transmission mechanism includes a first bevel gear and a second bevel gear that meshes with the first bevel gear. An output shaft is connected to the second bevel gear and can rotate about a second axis. The output shaft 28 is supported by a bearing 81 and connected to the second bevel gear 784 by screws. The inner ring of the bearing 81 is also clamped over the output shaft. A seal is shown next to the bearing 81.

[0006] DE 36 01 456 A1 discloses a mechanical joint mechanism, in particular a three-axis joint mechanism, for a robot. The joint mechanism comprises a first housing part, a second housing part, and a tool support part. The tool support part is connected to a bevel gear by screws. The bevel gear and the tool support part are rotatably mounted by means of a bearing. The bearing is arranged between the tool support part and the bevel gear. A seal is arranged next to the bearing to prevent contamination of the bearing.

[0007] The object of the present invention is to provide an output bearing arrangement for a joint drive, in particular a robot joint drive, which improves upon the arrangements known from the prior art and in particular enables a compact design.

[0008] The problem is solved by the features of independent claim 1.

[0009] According to the invention, an output bearing arrangement includes a spacer sleeve positioned axially between the inner ring of the output bearing and the joint element. This output bearing arrangement enables a very compact design. Furthermore, the effects of the output bearing fixation allow radial loads, axial loads, tilting moments, and torsional moments to be reliably transmitted within the joint using a single bearing. The joint element can be, in particular, a robot arm, a robot leg, or a component of an exoskeleton. An axial force is thus transmitted from the output-side joint element to the output shaft via the spacer sleeve and the bearing's inner ring. In an embodiment not part of the invention, it would also be conceivable for the spacer sleeve to be an integral part of the joint element.

[0010] In a particularly compact embodiment, only a single output bearing is provided for supporting the output shaft. In this case, both the inner and outer rings of the output bearing are guided radially and axially. Preferably, a crossed roller bearing, a four-point contact bearing, or a double-row angular contact ball bearing is used as the output bearing. The inner ring of the output bearing is preferably arranged axially between the joint element and the output shaft. This achieves the desired axial fixation of the inner ring.

[0011] A simple design can be achieved by providing at least one screw as a clamping device. The inner ring of the robot joint's output bearing is then axially clamped by the same screw(s) that also clamp the joint element axially to the output shaft. Preferably, the screws extend through the joint element and are screwed to the output shaft.

[0012] Advantageously, it is provided that any torque that occurs is completely transmitted to the output shaft by means of a frictional connection via the spacer sleeve and the inner ring of the output bearing.

[0013] In yet another advantageous embodiment, the seal may comprise a sealing element arranged on the spacer sleeve and radially enclosing the spacer sleeve. The outer surface of the spacer sleeve can then be designed as a running surface for the sealing element. Preferably, the sealing element is a dynamic seal. This design allows the axial clamping of the inner ring of the output bearing to be compactly combined with the sealing of the joint and the torsional transmission between the joint elements.

[0014] Advantageously, an additional sealing component can be arranged between the spacer sleeve and the output shaft. A static sealing component, such as an O-ring, can be used here. This results in a simple and reliable design.

[0015] In an advantageous embodiment, it can be provided that the joint element rests on the end face of the output shaft exclusively indirectly or only partially directly.

[0016] In yet another embodiment, the output shaft may have a central elevation on its end face, the joint element rests against the central elevation of the output shaft and against the spacer sleeve, and at least two screws are arranged along the circumference of the output shaft. The central elevation is preferably cylindrical and may, for example, be designed such that the end face of the output shaft is slightly recessed at its edges, i.e., in an annular shape, for example by 0.2 mm. By screwing the joint element to the output shaft, the spacer sleeve is pressed against the output bearing, thus securing the output bearing.

[0017] Good torque transmission and even load distribution can be achieved by transmitting the torque both via the spacer sleeve and via the central rise of the output shaft, preferably about 40-60% of the torque being transmitted via the spacer sleeve and about 40-60% of the torque being transmitted via the central rise of the output shaft, and particularly preferably about 50% of the torque being transmitted via the spacer sleeve and about 50% of the torque being transmitted via the central rise of the output shaft.

[0018] In an alternative embodiment, the spacer sleeve can project axially beyond an end face of the output shaft, the joint element rests against the spacer sleeve, and at least two screws are arranged along the circumference of the output shaft. The joint element thus rests only against the spacer sleeve; a central support in the center of the joint element is absent. This allows the joint element to flex towards the center or longitudinal axis of the output shaft, similar to a beam. This preloads the connection and reduces the risk of the screw loosening during operation of the joint.

[0019] The risk of the bolt loosening during operation of the joint can be further reduced if the spacer sleeve projects axially beyond an end face of the output shaft, the joint element rests against the spacer sleeve, and at least one bolt is located in the center of the joint element. Here, too, the joint element rests only against the spacer sleeve. This causes the joint element to deflect towards the center of the output shaft, i.e., in the direction of the output shaft's longitudinal axis. This creates an even longer bending beam, which further preloads the connection, thus reducing the risk of the bolt loosening during operation.

[0020] To ensure secure attachment of the spacer sleeve to the output shaft, it may also be provided that the spacer sleeve is additionally pressed, glued or screwed onto the output shaft.

[0021] A stable design can be achieved by using a steel spacer sleeve.

[0022] Preferably, the sealing element is made of rubber. Since the spacer sleeve is made of steel, there is little abrasion from friction against the rubber seal.

[0023] A reliable seal can be achieved by having the sealing element rest on the spacer sleeve with two axially spaced-apart bearing areas. Preferably, these bearing areas are designed as annular regions around the circumference of the spacer sleeve.

[0024] In yet another advantageous embodiment, the output shaft can be made of steel. This also enables a stable design.

[0025] Exemplary embodiments of the present invention are explained in more detail below with reference to the drawings.

[0026] They show: Figure 1: Section through an output bearing arrangement according to the invention; Figure 2: Output bearing arrangement made of Figure 1 without a joint element; Figure 3: further embodiment of the output bearing arrangement according to the invention; Figure 4: further embodiment of the output bearing arrangement according to the invention; and Figure 5: further embodiment of the output bearing arrangement according to the invention.

[0027] In the following explanations, identical parts are designated by the same reference numerals. If a figure contains reference numerals that are not further explained in the corresponding figure description, reference is made to preceding or subsequent figure descriptions.

[0028] Figure 1Figure 1 shows a section through an output bearing arrangement 10 according to the invention. The output bearing arrangement 10 comprises an output shaft 1 and a joint element 2 clamped to the output shaft 1 by means of a clamping device. The clamping device is preferably in the form of at least one screw 3. The joint element 2 is thus screwed to the output shaft 1 by means of the at least one screw 3. The output shaft 1 is rotatably mounted by means of an output bearing 7. Preferably, the output shaft 1 is mounted by means of a single rolling bearing, for example, a crossed roller bearing, a four-point contact bearing, or a double-row angular contact ball bearing. In this case, both the inner ring 7.1 and the outer ring 7.2 of the output bearing 7 must be guided radially and axially. For this purpose, a spacer sleeve 5 is arranged axially between the inner ring 7.1 of the output bearing 7 and the joint element 2.The inner ring 7.1 of the output bearing 7 is clamped or clamped to the output shaft 1 via the spacer sleeve 5 by means of the joint element 2 and the screw(s) 3. Thus, an axial force can be transmitted from the output-side joint element 2 to the output shaft 1 via the spacer sleeve 5 and the inner bearing ring 7. Alternatively, it would also be possible to clamp the inner bearing ring directly to the output shaft via the joint element. In an alternative solution, not part of the invention, it would also be conceivable for the spacer sleeve to be integrally formed with the joint element. A sealing element 6 is arranged on the spacer sleeve 5, radially enclosing the spacer sleeve 5 and sealing the bearing interface. The sealing element 6 preferably has two bearing areas 18 with which it rests on the spacer sleeve 5. The bearing areas 18 are preferably designed as annular regions.The outer surface of the spacer sleeve 5 is thus designed as a running surface for the dynamic sealing element 6. The spacer sleeve 5 projects axially in the direction of the joint element 2 beyond the end face 11 of the output shaft 1. As a result, the joint element 2 bears against both the spacer sleeve 5 and at least a portion of the output shaft 1. A further sealing component 4 is arranged between the spacer sleeve 5 and the output shaft 1. For this purpose, a groove 12 is provided in the spacer sleeve 5 in which the further sealing component 4 is arranged. The further sealing component 4 is preferably designed as an O-ring. Torsion between the output shaft 1 and the joint element 2 is prevented by friction between the joint element 2 and the output shaft 1, and also by friction between the joint element 2 and the spacer sleeve 5, the spacer sleeve 5 and the inner ring 7.1 of the output bearing 7, and the inner ring 7.The output bearing 7 and the output shaft 1 transmit the load. Thus, the following functions can be advantageously and compactly performed with a minimal number of components: fixing the output bearing 7, sealing the joint or the output bearing assembly 10 by means of a dynamic sealing element 6, and transmitting the torsional moment. Due to the fixing action of the output bearing 7, radial loads, axial loads, tilting moments, and torsional moments can be reliably transmitted in the joint with a single bearing.

[0029] Figure 2 shows the initial storage arrangement 10 from Fig. 1without the joint element. The output shaft 1 has a central elevation 13 on its end face 11. Preferably, the central elevation 13 is cylindrical and is designed such that the output shaft 1 is slightly recessed along its circumference, for example by 0.2 mm. In this recessed area, bores 14 are formed in the output shaft 1. The screws with which the joint element is screwed to the output shaft 1 are received in these bores 14. In addition, at least one hole 15 extending from the end face 11 can be formed in the output shaft 1. A pin 16, which serves to fix the joint element to the output shaft 1, is received in this hole 15. The spacer sleeve 5 is preferably made of steel, and the output shaft 1 is preferably made of aluminum. The spacer sleeve 5 can additionally be pressed, glued, or screwed onto the output shaft 1.It would also be conceivable for the spacer sleeve and the output shaft to be made of the same material, in particular steel. The sealing element 6 is preferably made of rubber and runs on the spacer sleeve 5. If the spacer sleeve 5 is made of steel, less abrasion occurs due to friction against the rubber seal than, for example, on an aluminum component. The spacer sleeve 5 projects slightly beyond the end face 11 of the output shaft 1 in the axial direction, i.e., in the direction of the longitudinal axis L of the output shaft 1.

[0030] The ring element 8 is preferably screwed into the bearing cap 9 via a fine thread and secures the upper part, i.e. the outer ring 7.2 of the output bearing 7.

[0031] In the Figure 3, 4 and 5 Various embodiments for attaching the joint element 2 to the output shaft 1 are now described.

[0032] In Figure 3A first embodiment for attaching the joint element 2 to the output shaft 1 is shown. The output shaft 1 has the central protrusion 13 described above, against which the joint element 2 rests with a central portion. In addition, the spacer sleeve 5 projects axially in the direction of the longitudinal axis L of the output shaft 1 beyond the end face 11 of the output shaft 1. The joint element 2 therefore also rests against the spacer sleeve 5, for example with an outer portion. For this purpose, a shoulder 17 can be formed in the spacer element 2. The screws 3, which clamp the joint element 2 axially to the output shaft 1, are arranged along the circumference of the output shaft 1. In this embodiment, part of the torque is transmitted from the joint element 2 to the spacer sleeve 5, and another part of the torque is transmitted from the joint element 2 to the central protrusion 13 of the output shaft 1.Preferably, it can be provided that approximately 40-60% of the torque occurring is transmitted via the spacer sleeve 5 and approximately 40-60% of the torque occurring is transmitted via the central rise 13 of the output shaft 1, and particularly preferably approximately 50% of the torque occurring is transmitted via the spacer sleeve 5 and approximately 50% of the torque occurring is transmitted via the central rise 13 of the output shaft 1.

[0033] Figure 4Figure 1 shows another embodiment for attaching the joint element 2 to the output shaft 1. In this case, no raised section is formed on the end face of the output shaft 1. The joint element 2 thus rests only against the spacer sleeve 5. A central support in the center of the joint element 2 is absent. Here, too, a shoulder 17 can be formed in the joint element 2, with which the joint element 2 rests against the spacer sleeve 5. The bores 14 are formed along the circumference in the output shaft 1, so that the screws 3 are also arranged along the circumference of the output shaft 1. Thus, the joint element 2 can bend towards the center of the output shaft 1 like a bending beam. This design of the joint element 2 as a bending beam preloads the screw connection and reduces the risk of the screw connection loosening during operation of the joint.

[0034] Figure 5Figure 1 shows another embodiment for attaching the joint element 2 to the output shaft 1. In this embodiment as well, the output shaft 1 does not have a central protrusion on its end face. The joint element 2 again rests only against the spacer sleeve 5. For this purpose, the joint element 2 has a shoulder 17 with which it rests against the spacer sleeve 5. At least one bore 14 is formed centrally in the output shaft 1, for example, located on the longitudinal axis L of the output shaft 1. Thus, the screw 3 is arranged in the center of the joint element 2. It can also be provided that several screws are arranged in the center of the joint element and thus several bores are formed in the center of the output shaft. In this embodiment, the joint element 2 provides a [missing information - likely a specific feature or feature] compared to the embodiment shown in Figure 2. Fig. 4A longer bending beam is formed, which increases the preload on the screw connection between the joint element 2 and the output shaft 1, thereby further reducing the risk of the screw connection between the joint element 2 and the output shaft 1 loosening during operation of the joint. Reference symbol list

[0035] 1 Output shaft 2 Joint element 3 Screw 4 Sealing component 5 Spacer sleeve 6 Sealing element 7 Output bearing 7.1 Inner ring output bearing 7.2 Outer ring output bearing 8 Ring element 9 Bearing cover 10 Output bearing assembly 11 End face output shaft 12 Groove 13 Central raised section 14 Bore 15 Hole 16 Pin 17 Shoulder 18 Contact area L Longitudinal axis output shaft

Claims

1. Output bearing arrangement (10) for an articulated drive, in particular a robot articulated drive, comprising an output shaft (1), an output bearing (7) arranged on the output shaft (1) with an inner ring (7.1) for supporting the output shaft (1), a seal for sealing the articulated drive and an output-side joint element (2), whereby the joint element (2) is axially clamped to the output shaft (1) by means of a clamping device and the clamping device of the joint element (2) also axially clamps the inner ring (7.1) of the output bearing (7), characterized in that a spacer sleeve (5) is arranged in the axial direction (L) between the inner ring (7.1) of the output bearing (7) and the joint element (2).

2. Output bearing arrangement (10) according to claim 1, characterized in that a single output bearing (7) is provided for supporting the output shaft (1).

3. Output bearing arrangement (10) according to claim 1 or 2, characterized in that at least one screw (3) is provided as a clamping device.

4. Output bearing arrangement (10) according to at least one of claims 1 to 3, characterized in that the seal comprises a sealing element (6) arranged on the spacer sleeve (5) and radially enclosing the spacer sleeve (5).

5. Output bearing arrangement (10) according to at least one of claims 1 to 4, characterized in that a further sealing component (4) is arranged between the spacer sleeve (5) and the output shaft (1).

6. Output bearing arrangement (10) according to at least one of claims 1 to 5, characterized in that the output shaft (1) has a central elevation (13) on its end face (11), the joint element (2) rests on the central elevation (13) of the output shaft (1) and on the spacer sleeve (5), and at least two screws (3) are arranged along the circumference of the output shaft (1).

7. Output bearing arrangement (10) according to claim 6, characterized in that a torque occurring is transmitted both via the spacer sleeve (5) and via the central elevation (13) of the output shaft (1), wherein preferably about 40-60% of the torque occurring is transmitted via the spacer sleeve (5) and about 40-60% of the torque occurring is transmitted via the central elevation (13) of the output shaft (1), and particularly preferably about 50% of the torque occurring is transmitted via the spacer sleeve (5) and about 50% of the torque occurring is transmitted via the central elevation (13) of the output shaft (1).

8. Output bearing arrangement (10) according to at least one of claims 1 to 5, characterized in that the spacer sleeve (5) projects in axial direction (L) over an end face (11) of the output shaft (1), the joint element (2) rests against the spacer sleeve (5) and at least two screws (3) are arranged along the circumference of the output shaft (1).

9. Output bearing arrangement (10) according to at least one of claims 1 to 5, characterized in that the spacer sleeve (5) projects in axial direction (L) over an end face (11) of the output shaft (1), the joint element (2) rests against the spacer sleeve (5) and at least one screw (3) is arranged in the center of the joint element (2).

10. Output bearing arrangement (10) according to at least one of claims 1 to 9, characterized in that the spacer sleeve (5) is additionally pressed or glued or screwed onto the output shaft (1).

11. Output bearing arrangement (10) according to at least one of claims 1 to 10, characterized in that the spacer sleeve (5) is made of steel.

12. Output bearing arrangement (10) according to at least one of claims 4 to 11, characterized in that the sealing element (6) is made of rubber.

13. Output bearing arrangement (10) according to at least one of claims 4 to 12, characterized in that the sealing element (6) rests on the spacer sleeve (5) with two axially spaced support areas (18).

14. Output bearing arrangement (10) according to at least one of claims 1 to 13, characterized in that the output shaft (1) is made of steel.