Robot joint and method for sealing a joint gap of a robot joint

1. A system comprising:

a robot having at least one robot joint, wherein the robot joint includes a first part and a second part arranged to have a relative movement in between, and a joint gap spacing the first part and the second part from each other, wherein the robot joint includes an inflatable seal accommodated in the joint gap to provide a fluid-tight sealing of the joint,

a control unit,

a valve arrangement, and

a tube arrangement fluidly connected to a source of pressurized fluid and to the inflatable seal, wherein the control unit is programmed to pressurize the inflatable seal by means of the valve arrangement and the tube arrangement such that the inflatable seal expands in an axial direction towards the second part to seal the joint gap between the first part and the second part,

and

wherein the control unit is configure to control the valve arrangement to pressurize the inflatable seal in synchronization with the robot operation, such that the inflatable seal is pressurized to a predetermined low pressure when the robot is working, and to a predetermined high pressure when the robot is exposed to high pressure wash down and/or is shut down, wherein the predetermined high pressure is higher than the predetermined low pressure.

2. The system according to claim 1 , wherein the joint gap is annular.

3. The system according to claim 1 , wherein the inflatable seal is annular.

4. The system according to claim 1 , wherein the first part and/or the second part has a structure designed to force the inflatable seal to expand in the axial direction towards the second part when inflating the inflatable seal.

5. The system according to claim 4 , wherein the first part comprises a first axially extending structure delimiting the inflatable seal against an exterior of the robot joint, and a second axially extending structure, the first axially extending structure and the second axially extending structure delimiting a space where the inflatable seal is accommodated, and wherein the first axially extending structure and the second axially extending structure are designed to force the inflatable seal to expand in the axial direction towards the second part when inflating the inflatable seal.

6. The system according to claim 4 , wherein the structure is designed to prevent radial expansion of the inflatable seal.

7. The system according to claim 1 , wherein the inflatable seal is attached to the first part.

8. The system according to claim 1 , wherein the robot comprises a plurality of robot joints, wherein the inflatable seals are fluidly connected in series by means of the tube arrangement.

9. The system according to claim 1 , wherein the relative movement occurs between surfaces that are axial or at least have axial direction components.

10. A method for sealing a joint gap of a robot joint of a robot, wherein the robot joint comprises a first part and a second part with a relative movement in between, and the joint gap spaces the first part and the second part from each other, the robot joint further including an inflatable seal accommodated in the joint gap to provide a fluid-tight sealing of the joint, wherein the method comprises:

pressurizing the inflatable seal such that the inflatable seal expands in an axial direction towards the second part to seal the joint gap between the first part and the second part;

wherein said pressurizing the inflatable seal includes:

pressurizing the inflatable seal to a predetermined low pressure when the robot is working, and

pressurizing the inflatable seal to a predetermined high pressure when the robot is not working and/or is exposed to wash down;

wherein the predetermined high pressure is higher than the predetermined low pressure.

11. The method according to claim 10 ,

wherein said pressurizing the inflatable seal is synchronized with a robot operation.

12. The method according to claim 10 , wherein the step of pressurizing the inflatable seal such that the inflatable seal expands comprises pressurizing an annular inflatable seal.

13. The method according to claim 10 , further comprising: forcing the inflatable seal to expand in the axial direction towards the second part when the inflatable seal is pressurized.

14. The method according to claim 13 , further comprising: preventing radial expansion of the inflatable seal.

15. The method according to claim 13 , further comprising: delimiting the inflatable seal against an exterior of the robot joint via a first axially extending structure of the first part, wherein the first axially extending structure and a second axially extending structure of the first part delimit a space where the inflatable seal is accommodated, and wherein the first axially extending structure and the second axially extending structure are designed to force the inflatable seal to expand in the axial direction towards the second part when pressurizing the inflatable seal.

16. The method according to claim 10 , wherein the step of pressurizing the inflatable seal such that the inflatable seal expands to seal the joint gap comprises pressurizing the inflatable seal to seal an annular joint gap.

17. The method according to claim 10 , wherein the step of pressurizing the inflatable seal such that the inflatable seal expands comprises pressurizing the inflatable seal while attached to the first part.

18. The method according to claim 10 , further comprising: initiating the relative movement of the first part and the second part along surfaces that are axial or that at least have axial direction components.