DEVICE FOR MEASURING A TORQUE AND STRAIN WAVE GEARING COMPRISING SUCH A DEVICE

Abstract

A device for measuring a torque of a strain wave gearing includes a component (01, 02), on which the torque is applied, an electrically insulating insulation layer (06) arranged on the component (01, 02) and a deformation-sensitive measurement layer (04) arranged on the insulation layer (06). A strain wave gearing for a robot arm has such a device for measuring a torque.

Claims

1. A device for measuring a torque of a strain wave gearing, the device comprising: a flexible spline for receiving the torque; an electrically insulating insulation layer arranged on the flexible spline; and a deformation-sensitive measurement layer arranged on the electrically insulating insulation layer.

2. The device according to claim 1, wherein the flexible spline is part of a robot arm or a robot arm joint of a robotics system.

3. The device according to claim 1, further comprising a protective layer on the deformation-sensitive measurement layer.

4. The device according to claim 3, wherein the protective layer is organic.

5. The device according to claim 3, wherein a total thickness of a sequence of layers applied to the flexible spline, consisting of the deformation-sensitive measurement layer, the electrically insulating insulation layer and the protective layer, is less than 200 μm.

6. The device according to claim 1, wherein the electrically insulating insulation layer consists of one or more oxide layers and/or a carbon coating.

7. The device according to claim 1, wherein a total thickness of a sequence of layers applied to the flexible spline, consisting of the deformation-sensitive measurement layer and the electrically insulating insulation layer, is less than 20 μm.

8. The device according to claim 1, further comprising further components are arranged on the flexible spline.

9. A strain wave gearing for a robot arm, comprising: the device for measuring a torque according to claim 1; a drive shaft; a wave generator having an inner ring and an outer ring; and an internally toothed ring gear, the flexible spline being an externally toothed flexible spline, wherein the externally toothed flexible spline and the internally toothed ring gear are arranged coaxial with respect to each other such that toothings of the externally toothed flexible spline mesh with toothings of the internally toothed ring gear, and wherein the inner ring is positioned on the drive shaft such that the drive shaft drives and deforms the externally toothed flexible spline.

10. The device according to claim 3, wherein the protective layer is inorganic.

11. A method of producing a device for measuring a torque of a strain wave gearing, the method comprising: providing a flexible spline reconfigured for receiving a torque input; depositing an electrically insulating insulation layer directly on the flexible spline; and applying a deformation-sensitive measurement layer directly on the electrically insulating insulation layer.

12. The method as recited in claim 11 wherein the depositing is performed by physical vapor deposition or chemical assisted physical vapor deposition.

13. The method as recited in claim 11 wherein the electrically insulating insulation layer is aluminum oxide and/or wollastonite.

14. The method as recited in claim 11 wherein the deformation-sensitive measurement layer consists of metal or an alloy.

15. The method as recited in claim 11 further comprising structuring the deformation-sensitive measurement layer into a striped pattern.

16. The method as recited in claim 15 wherein the striped pattern includes stripes in an angular range between 35° and 55° with respect to a longitudinal axis of the flexible spine.

17. The method as recited in claim 15 wherein the structuring of the deformation-sensitive measurement layer into the striped pattern is performed by laser structuring or by etching after the applying of the deformation-sensitive measurement layer directly on the electrically insulating insulation layer.

18. A device for measuring a torque of a strain wave gearing, the device comprising: a flexible spline, the flexible spline including a disk and a cylindrical component adjoining the disk, the cylindrical component including a torque input section configured for receiving the torque; an electrically insulating insulation layer arranged on the cylindrical component offset from the torque input section; and a deformation-sensitive measurement layer arranged on the electrically insulating insulation layer.

19. The device as recited in claim 18 wherein the deformation-sensitive measurement layer consists of metal or an alloy structured into a striped pattern including numerous meanders and non-curved sections forming stripes, axes of the stripes of the structure being inclined with respect to a longitudinal axis of the flexible spine.

20. The device as recited in claim 19 wherein the stripes are inclined in an angular range between 35° and 55° with respect to the longitudinal axis of the flexible spine.

Description

BRIEF SUMMARY OF THE DRAWINGS

[0030] Further advantages and details of the present disclosure arise from the following description of preferred embodiments with reference to the attached drawing. In the figures:

[0031] FIG. 1 shows a side view and a detailed view of a first embodiment of a device according to the present disclosure;

[0032] FIG. 2 shows a sectional view and a detailed view of the device shown in FIG. 1;

[0033] FIG. 3 shows a plan view of a second embodiment of the device;

[0034] FIG. 4 shows a side view of the device shown in FIG. 3;

[0035] FIG. 5 shows a sectional view and a detailed view of the side view of the device shown in FIG. 4.

DETAILED DESCRIPTION

[0036] FIG. 1 shows a side view and a detailed view of a first embodiment of a device according to the present disclosure. The device represents a flexible spline usable in a strain wave gearing, wherein the flexible spline consists of a disk 01 and a cylindrical component 02 axially adjoining the disk. Preferably, the flexible spline is made of steel. The cylindrical component 02 or sleeve is arranged on the inner diameter of the disk 01. The cylindrical component 02 has an external toothing 03 on its section facing away from the disk 01. A deformation-sensitive measurement layer 04 in the form of a strain gauge, in particular in the form of a Sensotect strain gauge, is arranged on the section of the outer circumference of the cylindrical component 02 facing the disk 01. An insulating insulation layer 06 is formed between the base material of the cylindrical component 02 and the deformation-sensitive measurement layer 04. A torque of the strain wave gearing is determined by means of the deformation-sensitive measurement layer 04. The measurement layer preferably has a structuring which forms a striped pattern.

[0037] Furthermore, a detailed view of the deformation-sensitive measurement layer 04 is shown in FIG. 1. In the example shown, the formed structure of the measurement layer 04 runs in numerous meanders, the axes of the non-curved sections of the structure being inclined to the cylinder axis of the component 02.

[0038] One of the advantages of the device according to the present disclosure is that it is designed to save installation space.

[0039] FIG. 2 shows a sectional view of the flexible spline shown in FIG. 1 with the disk 01 and the cylindrical component 02. In a detailed view of FIG. 2, the sequence of layers of the device is shown. On the cylindrical component 02, which is made of steel, the insulation layer 06 is applied, on which the deformation-sensitive measurement layer 04 and a protective layer 07 arranged thereon are applied. The deformation-sensitive measurement layer 04 is a structured NiCr functional layer.

[0040] FIG. 3 shows a plan view of a further embodiment of the device. Differing from the device shown in FIG. 1, here the disk 01 has the deformation-sensitive measurement layer 04. No deformation-sensitive measurement layer is formed on the outer circumference of the cylindrical component 02. The individual components of the deformation-sensitive measurement layer 04 are circumferentially distributed on the disk 01. The device is designed here as a collar sleeve.

[0041] FIG. 4 shows a side view of the collar sleeve shown in FIG. 3. Since the deformation-sensitive measurement layer 04 is formed on the disk 01, the measurement layer on the outer circumference of the cylindrical component 02 is missing. In the area of the cylindrical component 02 facing away from the disk 01, the toothing 03 is also formed on the outer circumference.

[0042] FIG. 5 shows a sectional view of the side view of the device shown in FIG. 4. Furthermore, FIG. 5 shows a detailed view of the sequence of layers of the disk 01. The insulation layer 06, preferably consisting of Al.sub.2O.sub.3, is arranged on the steel disk 01. The deformation-sensitive measurement layer 04 with a protective layer 07 located thereon is arranged on the insulation layer 06. Contact layers 08 for making electrical contact are located between the individual deformation-sensitive measurement layers 04.

[0043] FIG. 6 schematically shows a strain wave gearing 10 according to the present disclosure comprises a device 12 for measuring a torque according to the device described with respect to FIG. 1. Further, the strain wave gearing 10 comprises a drive shaft 14, a wave generator 16 which may be a rolling bearing with a non-circular, e.g., elliptical, inner ring 18 and a deformable outer ring 20, a ring gear 22, and an elastic sleeve in the form of the flexible spline 01, 02. The flexible spline 01, 02 exhibits external toothing 03 and the ring gear 22 exhibits internal toothing 22a. The flexible spline 01, 02 and ring gear 22 are arranged coaxially to each other so that the gear teeth 03, 22a mesh with one another. The inner ring 18 of the wave generator 16 is positioned on the drive shaft so that it drives the component. Device 12 may be part of a robot arm or a robot arm joint 24 of a robotics system 26.

LIST OF REFERENCE SYMBOLS

[0044] 01 Disk [0045] 02 Cylindrical component [0046] 03 External toothing [0047] 04 Deformation-sensitive measurement layer [0048] 06 Insulation layer [0049] 07 Protective layer [0050] 08 Contact layer [0051] 10 Strain wave gearing [0052] 12 Device for measuring torque [0053] 14 Draft shaft [0054] 16 Wave generator [0055] 18 Inner ring [0056] 20 Outer ring [0057] 22 Ring gear [0058] 22a Internal toothing [0059] 24 Robot arm joint [0060] 26 Robotics system