JOINT ARRANGEMENT, ELECTRIC MOTOR AND INDUSTRIAL ACTUATOR

Abstract

A joint arrangement including a drive member rotatable about a rotation axis, the drive member including a drive member press fit surface and a drive member shape lock structure; an attachment portion having an attachment thread; and a driven member including a driven member press fit surface, a driven member shape lock structure and a through hole; wherein the joint arrangement is configured such that the driven member can be rigidly connected to the drive member by means of a press fit between the drive member press fit surface and the driven member press fit surface by threadingly engaging the attachment thread with an attachment member passing through the through hole; and wherein the joint arrangement is configured such that a shape lock is provided between the drive member shape lock structure and the driven member shape lock structure when the driven member is connected to the drive member.

Claims

1. A joint arrangement comprising: a drive member rotatable about a rotation axis, the drive member comprising a drive member press fit surface and a drive member shape lock structure; an attachment portion having an attachment thread; and a driven member comprising a driven member press fit surface, a driven member shape lock structure and a through hole; wherein the joint arrangement is configured such that the driven member can be rigidly connected to the drive member by means of a press fit between the drive member press fit surface and the driven member press fit surface by threadingly engaging the attachment thread with an attachment member passing through the through hole; and wherein the joint arrangement is configured such that a shape lock is provided between the drive member shape lock structure and the driven member shape lock structure when the driven member is connected to the drive member.

2. The joint arrangement according to claim 1, wherein the joint arrangement is configured such that the press fit can be established by rotating the attachment member when threadingly engaging the attachment thread.

3. The joint arrangement according to claim 1, wherein the attachment member comprises an attachment head, and wherein the joint arrangement is configured such that the press fit can be established by pushing the driven member away from the attachment head when the attachment member threadingly engages the attachment thread.

4. The joint arrangement according to claim 1, further comprising the attachment member.

5. The joint arrangement according to claim 1, wherein the driven member further comprises a detachment thread, and wherein the joint arrangement is configured such that the press fit can be released by threadingly engaging the detachment thread with a detachment member.

6. The joint arrangement according to claim 5, wherein the joint arrangement is configured such that the press fit can be released by rotating the detachment member when threadingly engaging the detachment thread.

7. The joint arrangement according to claim 5, wherein the detachment thread is provided in the through hole.

8. The joint arrangement according to claim 5, wherein the detachment thread is larger than the attachment thread.

9. The joint arrangement according to claim 5, further comprising the detachment member.

10. The joint arrangement according to claim 1, wherein the driven member is a pinion.

11. The joint arrangement according to claim 1, wherein the through hole is substantially concentric with the rotation axis when the driven member is connected to the drive member.

12. The joint arrangement according to claim 1, wherein each of the drive member press fit surface and the driven member press fit surface is tapered.

13. The joint arrangement according to claim 1, wherein each of the drive member shape lock structure and the driven member shape lock structure is polygonal.

14. The joint arrangement according to claim 1, wherein each of the drive member press fit surface and the driven member press fit surface is polygonal.

15. The joint arrangement according to claim 1, wherein the drive member shape lock structure is a continuous surface.

16. The joint arrangement according to claim 1, wherein the drive member shape lock structure is constituted by the drive member press fit surface.

17. The joint arrangement according to claim 1, wherein the driven member shape lock structure is a continuous surface.

18. The joint arrangement according to claim 1, wherein the driven member shape lock structure is constituted by the driven member press fit surface.

19. The joint arrangement according to claim 1, wherein the drive member comprises one or more exterior flat surfaces.

20. The joint arrangement according to claim 1, wherein the attachment portion is provided in the drive member.

21. An electric motor comprising a joint arrangement including a drive member rotatable about a rotation axis, the drive member having a drive member press fit surface and a drive member shape lock structure: an attachment portion having an attachment thread; and a driven member comprising a driven member press fit surface, a driven member shape lock structure and a through hole; wherein the joint arrangement is configured such that the driven member can be rigidly connected to the drive member by means of a press fit between the drive member press fit surface and the driven member press fit surface by threadingly engaging the attachment thread with an attachment member passing through the through hole; and wherein the joint arrangement is configured such that a shape lock is provided between the drive member shape lock structure and the driven member shape lock structure when the driven member is connected to the drive member.

22. An industrial actuator comprising a joint arrangement including a drive member rotatable about a rotation axis, the drive member having a drive member press fit surface and a drive member shape lock structure: an attachment portion having an attachment thread; and a driven member comprising a driven member press fit surface, a driven member shape lock structure and a through hole; wherein the joint arrangement is configured such that the driven member can be rigidly connected to the drive member by means of a press fit between the drive member press fit surface and the driven member press fit surface by threadingly engaging the attachment thread with an attachment member passing through the through hole; and wherein the joint arrangement is configured such that a shape lock is provided between the drive member shape lock structure and the driven member shape lock structure when the driven member is connected to the drive member or an electric motor comprising a joint arrangement including a drive member rotatable about a rotation axis, the drive member comprising a drive member press fit surface and a drive member shape lock structure; an attachment portion having an attachment thread; and a driven member comprising a driven member press fit surface, a driven member shape lock structure and a through hole; wherein the joint arrangement is configured such that the driven member can be rigidly connected to drive member by means of a press fit between the drive member press fit surface and the driven member press fit surface by threadingly engaging the attachment thread with an attachment member passing through the through hole; and wherein the joint arrangement is configured such that a shape lock is provided between the drive member shape lock structure and the driven member shape lock structure when the driven member is connected to the drive member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Further details, advantages and aspects of the present disclosure will become apparent from the following embodiments taken in conjunction with the drawings, wherein:

[0057] FIG. 1: schematically represents a side view of an industrial robot comprising an electric motor and a joint arrangement;

[0058] FIG. 2: schematically represents a side view of the electric motor and the joint arrangement;

[0059] FIG. 3: schematically represents a perspective side view of the joint arrangement in a disconnected state;

[0060] FIG. 4: schematically represents a perspective front view of a drive member of the joint arrangement;

[0061] FIG. 5: schematically represents a front view of the drive member;

[0062] FIG. 6: schematically represents a cross-sectional side view of the drive member;

[0063] FIG. 7: schematically represents a perspective front view of a driven member of the joint arrangement;

[0064] FIG. 8: schematically represents a front view of the driven member;

[0065] FIG. 9: schematically represents a cross-sectional side view of the driven member;

[0066] FIG. 10: schematically represents a cross-sectional side view of the joint arrangement during connection of the driven member to the drive member by means of an attachment member;

[0067] FIG. 11: schematically represents a cross-sectional side view of the joint arrangement during disconnection of the driven member from the drive member by means of a detachment member;

[0068] FIG. 12: schematically represents a perspective side view of a further example of a joint arrangement in a disconnected state;

[0069] FIG. 13: schematically represents a cross-sectional side view of the joint arrangement in FIG. 12;

[0070] FIG. 14: schematically represents a perspective side view of the joint arrangement in FIGS. 12 and 13 in a connected state; and

[0071] FIG. 15: schematically represents a cross-sectional side view of the joint arrangement in FIG. 14.

DETAILED DESCRIPTION

[0072] In the following, a joint arrangement comprising a drive member and a driven member, an electric motor comprising a joint arrangement, and an industrial actuator comprising a joint arrangement, will be described. The same or similar reference numerals will be used to denote the same or similar structural features.

[0073] FIG. 1 schematically represents a side view of an industrial robot 10. The industrial robot 10 is one example of an industrial actuator. The industrial robot 10 of this specific example comprises a base 12, a first link 14a rotatable relative to the base 12 at a first axis, a second link 14b rotatable relative to the first link 14a at a second axis, a third link 14c rotatable relative to the second link 14b at a third axis, a fourth link 14d rotatable relative to the third link 14c at a fourth axis, a fifth link 4e rotatable relative to the fourth link 14d at a fifth axis, a sixth link 14f rotatable relative to the fifth link 4e at a sixth axis, and an end effector 16 connected to the sixth link 14f. The industrial robot 10 of this example thus comprises six degrees of freedom.

[0074] The industrial robot 10 comprises a plurality of electric motors for driving the axes. FIG. 1 shows an electric motor 18 of the industrial robot 10 for driving the second axis. The industrial robot 10 further comprises a joint arrangement 20.

[0075] FIG. 2 schematically represents a side view of the electric motor 18 and the joint arrangement 20. The joint arrangement 20 of this example comprises a drive shaft 22 and a pinion 24. The drive shaft 22 is one example of a drive member. The pinion 24 is arranged to drive a gearbox (not shown) of the second axis. The pinion 24 is one example of a driven member. The drive shaft 22 is here constituted by an output shaft of the electric motor 18. In FIG. 2, the pinion 24 is rigidly connected to the drive shaft 22 for common rotation about a rotation axis 26. The drive shaft 22 and the pinion 24 thereby form a joint.

[0076] The joint arrangement 20 of this example further comprises an attachment screw 28. The attachment screw 28 is one example of an attachment member.

[0077] The attachment screw 28 comprises an attachment head 30 at a proximal end (to the right in FIG. 2) and an attachment member thread 32 at a distal end (to the left in FIG. 2).

[0078] The joint arrangement 20 of this example further comprises a detachment screw 34. The detachment screw 34 is one example of a detachment member. The detachment screw 34 comprises a detachment head 36 at a proximal end, an end portion 38 at a distal end, and a detachment member thread 40 between the detachment head 36 and the end portion 38. The end portion 38 of this example is cylindrical.

[0079] FIG. 3 schematically represents a perspective side view of the joint arrangement 20. In FIG. 3, the pinion 24 is disconnected from the drive shaft 22. The drive shaft 22 is female and the pinion 24 is male.

[0080] The drive shaft 22 comprises a drive shaft press fit surface 42. The drive shaft press fit surface 42 is one example of a drive member press fit surface. The drive shaft press fit surface 42 forms a hole.

[0081] The pinion 24 comprises a pinion press fit surface 44. The pinion press fit surface 44 is one example of a driven member press fit surface.

[0082] The drive shaft press fit surface 42 and the pinion press fit surface 44 are configured to form a press fit to connect the pinion 24 to the drive shaft 22. Each of the drive shaft press fit surface 42 and the pinion press fit surface 44 is continuous.

[0083] The drive shaft 22 further comprises a drive shaft shape lock structure 46. In this example, the drive shaft shape lock structure 46 is constituted by the drive shaft press fit surface 42. The drive shaft shape lock structure 46 is one example of a drive member shape lock structure.

[0084] The pinion 24 further comprises a pinion shape lock structure 48. In this example, the pinion shape lock structure 48 is constituted by the pinion press fit surface 44. The pinion shape lock structure 48 is one example of a driven member shape lock structure. The drive shaft shape lock structure 46 and the pinion shape lock structure 48 are configured to form a shape lock when the pinion 24 is connected to the drive shaft 22. Each of the drive shaft shape lock structure 46 and the pinion shape lock structure 48 has a polygonal cross section.

[0085] The pinion 24 further comprises a through hole 50. The through hole 50 is concentric with the rotation axis 26 when the pinion 24 is connected to the drive shaft 22.

[0086] FIG. 4 schematically represents a perspective front view of the drive shaft 22, FIG. 5 schematically represents a front view of the drive shaft 22, and FIG. 6 schematically represents a cross-sectional side view of the drive shaft 22. With collective reference to FIGS. 4 to 6, the drive shaft shape lock structure 46 is generally triangular with rounded edges. Both the drive shaft press fit surface 42 and the drive shaft shape lock structure 46 are provided in a proximal end of the drive shaft 22. The drive shaft press fit surface 42 has a uniform cross-section along its length.

[0087] The drive shaft 22 of this example further comprises an attachment hole 52. The attachment hole 52 is provided in an attachment portion 54 of the drive shaft 22. The attachment hole 52 is substantially centered along a length of the drive shaft 22. The attachment hole 52 is a blind hole that opens into the hole provided by the drive shaft press fit surface 42. The attachment hole 52 comprises an attachment thread 56. The attachment thread 56 is an interior thread.

[0088] FIG. 7 schematically represents a perspective front view of a pinion 24 of the joint arrangement 20, FIG. 8 schematically represents a front view of the pinion 24, and FIG. 9 schematically represents a cross-sectional side view of the pinion 24. With collective reference to FIGS. 7 to 9, the pinion shape lock structure 48 is generally triangular with rounded edges. Both the pinion press fit surface 44 and the pinion shape lock structure 48 are provided in a distal end of the pinion 24. The pinion press fit surface 44 has a uniform cross-section along its length.

[0089] The through hole 50 comprises a detachment thread 58. The detachment thread 58 is thus an interior thread. The detachment thread 58 extends through the entire through hole 50. The detachment thread 58 is larger than the attachment thread 56.

[0090] FIG. 10 schematically represents a cross-sectional side view of the joint arrangement 20 during connection of the pinion 24 to the drive shaft 22. A user can manually connect the pinion 24 to the drive shaft 22 in the field, i.e. when the electric motor 18 comprising the drive shaft 22 is already mounted to the industrial robot 10.

[0091] In order to rigidly connect the pinion 24 to the drive shaft 22, a user may first rotationally align the pinion shape lock structure 48 and the drive shaft shape lock structure 46 and push the pinion 24 slightly into the drive shaft 22. The user may then insert the attachment screw 28 through the through hole 50 and thread the attachment member thread 32 into the attachment thread 56. When moving the attachment member thread 32 through the through hole 50, the attachment member thread 32 does not interfere with the detachment thread 58. As shown in FIG. 10, the attachment screw 28 is coaxial with the rotation axis 26 when the attachment member thread 32 engages the attachment thread 56.

[0092] Once the attachment head 30 abuts the proximal end of the pinion 24, further rotation of the attachment screw 28, e.g. by means of a torque wrench, will cause a press fit to be established between the pinion press fit surface 44 and the drive shaft press fit surface 42 since the attachment head 30 pushes the pinion 24 into the drive shaft 22. In this way, the pinion 24 becomes rigidly press fitted to the drive shaft 22 by threadingly engaging the attachment thread 56 with the attachment member thread 32 and by rotating the attachment screw 28. At the same time, i.e. when the triangular pinion shape lock structure 48 enters into the triangular drive shaft shape lock structure 46, a shape lock is established between the pinion 24 and the drive shaft 22.

[0093] When screwing the attachment screw 28 into the attachment thread 56, the user may apply a counter torque to the drive shaft 22, for example by holding the drive shaft 22 by hand or with a tool. Alternatively, or in addition, a brake in the electric motor 18 may be applied to provide a counter torque.

[0094] The attachment screw 28 may be left in engagement with the attachment thread 56. In this case, forces from the drive shaft 22 may be transmitted to the pinion 24 also via the threaded engagement between the attachment screw 28 and the attachment thread 56. Alternatively, the attachment screw 28 may be removed by screwing the attachment screw 28 in an opposite direction out from the attachment thread 56.

[0095] The joint comprising the pinion 24 connected to the drive shaft 22 is backlash free due to the press fit between the pinion press fit surface 44 and the drive shaft press fit surface 42. Should the press fit fail, the shape lock formed by the drive shaft shape lock structure 46 and the pinion shape lock structure 48 prevents relative rotational movements between the drive shaft 22 and the pinion 24. The shape lock enables the press fit force to be lower in comparison with a joint not comprising a shape lock. That is, a smaller safety margin may be provided for the press fit of the joint. This also enables a length of the drive shaft press fit surface 42 and the pinion press fit surface 44 to be made relatively short along the rotation axis 26, thus contributing to a compact design of the joint. As shown in FIG. 10, the drive shaft press fit surface 42 and the pinion press fit surface 44 are kept relatively short. In this way, the pinion 24 can be pressed together with the drive shaft 22 in a simple way, e.g. by using a torque wrench.

[0096] The field attachable joint also provides a “cleaner” motor module. That is, since the customer can attach the pinion 24 to the drive shaft 22 in the field, a design interface can be provided between the pinion 24 and the drive shaft 22 of the electric motor 18, instead of an interface provided between the pinion 24 and the gearbox. This contributes to an improved modular design. The design interface may for example specify a torque to be transmitted.

[0097] FIG. 11 schematically represents a cross-sectional side view of the joint arrangement 20 during disconnection of the pinion 24 from the drive shaft 22. A user can also manually disconnect the pinion 24 from the drive shaft 22 in the field.

[0098] In order to disconnect the pinion 24 from the drive shaft 22, the user may disconnect the attachment screw 28 from the attachment thread 56 (if this has not been done previously). The user may then insert the detachment screw 34 into the through hole 50 and thread the detachment member thread 40 into the detachment thread 58. As shown in Fig. ii, the detachment screw 34 is coaxial with the rotation axis 26 when the detachment member thread 40 engages the detachment thread 58. The end portion 38 does not interfere with the attachment thread 56 when entering the attachment hole 52.

[0099] Once the end portion 38 abuts the bottom of the attachment hole 52, further rotation of the detachment screw 34, e.g. by means of a torque wrench, will cause the press fit between the pinion press fit surface 44 and the drive shaft press fit surface 42 to be released. In this way, the pinion 24 can be released from the drive shaft 22 by threadingly engaging the detachment thread 58 with the detachment member thread 40 and by rotating the detachment screw 34.

[0100] When screwing the detachment screw 34 into the detachment thread 58, the user may apply a counter torque to the drive shaft 22, for example by holding the drive shaft 22 by hand or with a tool. Alternatively, or in addition, a brake in the electric motor 18 may be applied to provide a counter torque.

[0101] A user can thus mount and dismount the pinion 24 to and from the drive shaft 22 in the field in a simple and safe manner by only carrying a torque wrench, the attachment screw 28 and the detachment screw 34. The pinion 24 of this example is thus both field attachable and field detachable. This enables a reduction of spare parts. For example, instead of ordering a particular combination of a pinion 24 and a drive shaft 22, or a particular combination of a pinion 24 and an electric motor 18 comprising the drive shaft 22, only the pinion 24 or only the drive shaft 22 may be ordered by a customer.

[0102] FIG. 12 schematically represents a perspective side view of a further example of a joint arrangement 20, and FIG. 13 schematically represents a cross-sectional side view of the joint arrangement 20 in FIG. 12. With collective reference to FIGS. 12 and 13, mainly differences with respect to FIGS. 1 to 11 will be described.

[0103] In FIGS. 12 and 13, each of the drive shaft press fit surface 42 and the pinion press fit surface 44 is conical. Moreover, the drive shaft shape lock structure 46 and the pinion shape lock structure 48 is discontinuous in relation to the drive shaft press fit surface 42 and the pinion press fit surface 44, respectively. The drive shaft shape lock structure 46 is proximal of the drive shaft press fit surface 42. The pinion shape lock structure 48 is proximal of the pinion press fit surface 44. The shape lock of this example may therefore be said to be an external shape lock.

[0104] The drive shaft shape lock structure 46 of this example comprises two flat surfaces, each parallel with the rotation axis 26. Correspondingly, the pinion shape lock structure 48 of this example comprises two flat surfaces, each parallel with the rotation axis 26.

[0105] The drive shaft 22 comprises two exterior flat surfaces 60 (only one is visible in FIG. 12). The exterior flat surfaces 60 facilitate the application of a counter torque during attachment or detachment of the pinion 24, for example by application of pliers to the exterior flat surfaces 60.

[0106] The pinion 24 of this example also comprises a step 62 in the through hole 50. The detachment thread 58 is provided distally of the step 62. The through hole 50 is larger proximal of the step 62 than distal of the step 62.

[0107] FIG. 14 schematically represents a perspective side view of the joint arrangement 20 in FIGS. 12 and 13, and FIG. 15 schematically represents a cross-sectional side view of the joint arrangement 20 in FIG. 14. With collective reference to FIGS. 14 and 15, the pinion 24 has been connected to the drive shaft 22 by means of the attachment screw 28 in the same way as described in connection with FIG. 10. When the pinion 24 is connected to the drive shaft 22 as shown in FIGS. 14 and 15, the press fit between the drive shaft press fit surface 42 and the pinion press fit surface 44 provides a backlash free joint. In addition, the shape lock between the drive shaft shape lock structure 46 and the pinion shape lock structure 48 prevents relative rotational movements between the drive shaft 22 and the pinion 24 should the press fit fail.

[0108] The pinion 24 may be disconnected from the drive shaft 22 by means of the detachment screw 34 in the same way as described in connection with FIG. 11. Thus, also the joint arrangement 20 of this example is field attachable and field detachable.

[0109] While the present disclosure has been described with reference to exemplary embodiments, it will be appreciated that the present invention is not limited to what has been described above. For example, it will be appreciated that the dimensions of the parts may be varied as needed. Accordingly, it is intended that the present invention may be limited only by the scope of the claims appended hereto.