Electric robot for use in a hazardous location

• US 4,984,745 A
• Filed: 06/20/1989
• Issued: 01/15/1991
• Est. Priority Date: 01/22/1985
• Status: Expired due to Term

• Current Assignee: Fanuc Robotics America Incorporated (Fanuc Corporation)
• Original Assignee: GMF Robotics Corporation
• Inventors: Akeel, Hadi A., Malarz, Antoni J.
• Primary Examiner(s): Spar, Robert J.
• Assistant Examiner(s): Underwood, Donald W.
• Application Number:
  US07/370,123
• Time in Patent Office: 574 Days
• Field of Search: 414/4, 414/8, 414/730, 414/735, 414/744.1, 414/744.6, 414/744.7, 901/15, 901/23, 901/24, 901/38, 901/43, 901/49, 310/88, 239/587
• US Class Current: 239/587.2
• CPC Class Codes: B05B 13/0431 with spray heads moved by robots or articulated arms, e.g. for applying liquid or other fluent material to 3D-surfaces B05B13/0436, B05B13/0442, B05B13/0447, B05B13/0463 take precedence
• CPC Class Codes: B25J 19/0029 arranged within the different robot elements
• CPC Class Codes: B25J 19/0079 using an internal pressure system
• CPC Class Codes: Y10T 74/20311 including power cable or connector

Abstract

A multi-axis electric spraying robot adapted for use in a hazardous environment includes a base having a first pressurized compartment and an arm assembly having a second pressurized compartment in which compartments electric motors are respectively located. The arm assembly is supported for movement on the base at one end thereof. The arm assembly includes a wrist adapted for connecting the opposite end of the arm assembly with a spraying tool. One electric motor is provided to drive each axis. The compartments are pressurized to prevent flammable gases or vapors from entering the first and second compartments during operation of the robot.

Claims

1. An electrically driven robot adapted for use in a hazardous environment, comprising:

a base having a first hollow-base section and also having a second hollow-base section mounted for rotational movement on the first base section, and a circular seal that extends between the first and second base sections to cooperate therewith in defining an airtight first compartment;

a first drive mechanism including at least one electric motor received within the airtight first compartment;

an arm assembly including an inner arm mounted for movement on the base and an outer arm mounted for movement on the inner arm, said arm assembly being driven by the first drive mechanism to move the inner and outer arms, and one of said arms of the arm assembly having an airtight second compartment fluidly communicated with the airtight first compartment of the base;

a second drive mechanism including at least one electric motor within the second compartment defined by the arm assembly;

a wrist mechanism mounted on the outer arm of the arm assembly and driven by the second drive mechanism;

a cable bundle extending to the first hollow-base section and into the airtight first compartment of the base and having at least one cable connected to the first drive mechanism to operate the electric motor thereof, and said cable bundle including at least one other cable that extends through the circular seal of the base and from the airtight first compartment of the base into the airtight second compartment of the arm assembly and being connected to the second drive mechanism to operate the electric motor thereof;

a pressurized gas supply that feeds pressurized gas into the airtight first compartment of the base and thence into the airtight second compartment of the arm assembly to provide pressurized gas that surrounds the electric motors and the cables of the cable bundle within the compartments, whereby the robot is capable of operating in the hazardous environment; and

communicating means for fluidly communicating the first and second compartments, said pressurized gas supply feeding pressurized gas through said communicating means and into the second compartment.

2. The robot of claim 1 wherein the other cable of the cable bundle extends through said communicating means and into the second compartment.

3. An electrically driven robot adapted for use in a hazardous environment, comprising:

a base having a first hollow-base section and also having a second hollow-base section mounted for rotational movement on the first base section, and a circular seal that extends between the first and second base sections to cooperate therewith in defining an airtight first compartment;

a first drive mechanism including at least one electric motor received within the airtight first compartment;

an arm assembly including an inner arm mounted for movement on the base and an outer arm mounted for movement on the inner arm, said arm assembly being driven by the first drive mechanism to move the inner and outer arms, and one of said arms of the arm assembly having an airtight second compartment;

a second drive mechanism including at least one electric motor within the second compartment defined by the arm assembly;

a wrist mechanism mounted on the outer arm of the arm assembly and driven by the second drive mechanism;

a cable bundle extending to the first hollow-base section and into the airtight first compartment of the base and having at least one cable connected to the first drive mechanism to operate the electric motor thereof, and said cable bundle including at least one other cable that extends through the circular seal of the base and from the airtight first compartment of the base into the airtight second compartment of the arm assembly and being connected to the second drive mechanism to operate the electric motor thereof;

a pressurized gas supply that feeds pressurized gas into the airtight first compartment of the base and thence into the airtight second compartment of the arm assembly to provide pressurized gas that surrounds the electric motors and the cables of the cable bundle whereby the robot is capable of operating in the hazardous environment; and

communicating means for fluidly communicating the first and second compartments, said pressurized gas supply feeding pressurized gas through said communicating means and into the second compartment.

5. The robot of claim 3 or claim 4 further comprising a pressure detecting means for detecting the pressure within the first and second compartments to provide a signal upon the detected pressure dropping below an acceptable range above atmospheric pressure.

6. The robot of claim 3 or claim 4 wherein the other cable of the cable bundle extends through said communicating means and into the second compartment.

4. An electrically driven robot adapted for use in a hazardous environment, comprising:

a base defining an airtight first compartment;

a first drive mechanism including at least one electric motor received within the airtight first compartment;

an arm assembly mounted for movement on the base, and driven by the first drive mechanism, the arm assembly having an airtight second compartment fluidly communicated with the airtight first compartment of the base;

a second drive mechanism including at least one electric motor within the second compartment defined by the arm assembly;

a wrist mechanism mounted on the arm assembly and driven by the second drive mechanism;

a conduit extending to the base and communicated with the first compartment;

a cable bundle extending from a robot controller, through the conduit, and into the airtight first compartment of the base, the cable bundle having at least one cable connected to the first drive mechanism to operate the electric motor thereof, and said cable bundle including at least one other cable that extends from the airtight first compartment of the base into the airtight second compartment of the arm assembly and being connected to the second drive mechanism to operate the electric motor thereof; and

a pressurized gas supply that feeds pressurized gas into the airtight first compartment of the base and thence into the conduit and the airtight second compartment of the arm assembly to provide pressurized gas that surrounds the electric motors and the cables of the cable bundle;

sealing means that cooperates with the base and the arm assembly in defining the airtight first and second compartments to maintain the pressurized gas surrounding the electric motors and cables whereby the robot is capable of operating in the hazardous environment; and

communicating means for fluidly communicating the first and second compartments, said pressurized gas supply feeding pressurized gas through said communicating means and into the second compartment.

7. A compact, lightweight electrically driven robot adapted for use in a hazardous environment and to be controlled from outside said hazardous environment, comprising:

a base defining an airtight first compartment;

a first drive mechanism including at least one non-explosion-proof electric motor received within the airtight first compartment;

an arm assembly mounted for movement relative to the base, and driven by the first drive mechanism, the arm assembly having an airtight second compartment;

a second drive mechanism including at least one non-explosion-proof electric motor within the second compartment defined by the arm assembly;

a wrist mechanism mounted on the arm assembly and driven by the second drive mechanism;

a cable conduit extending from outside said hazardous environment to the airtight first compartment;

a plurality of non-explosion-proof cables housed within said cable conduit extending into said air tight first compartment, at least one of said cables being flexible and connected to the first drive mechanism to operate the electric motor thereof, and at least another of said cables being flexible and extending from the airtight first compartment of the base to the airtight second compartment of the arm assembly and being connected to the second drive mechanism to operate the electric motor thereof;

said non-explosion-proof cables being sufficiently flexible to accommodate the movement of said arm assembly relative to the base;

a pressurized gas supply for feeding pressurized gas into the airtight compartments and into said cable conduit to provide pressurized gas that surrounds the electric motors in their respective compartments and the cables housed in the cable conduit;

sealing means cooperating between the base, the arm assembly and the cable conduit to maintain the compartments airtight and the pressurized gas surrounding the non-explosion-proof electric motors and cables whereby the robot is capable of operating in the hazardous environment; and

communicating means fluidly communicating the first and second compartments, said pressurized gas supply feeding sufficient pressurized gas through said communicating means to prevent gases from said hazardous environment from entering said compartments and said cable conduit, whereby to obviate the need that said electric motors and said cables be explosion-proof so that the robot may be compact and lightweight.

8. The electrically driven robot of claim 7 wherein said non-explosion-proof cables extend within their respective compartments to the connections with their respective motors.

9. The electrically driven robot of claim 8 wherein the base includes relatively movable sections and said cables are further sufficiently flexible to be formed into a ribbon bent along a relatively small radius of curvature so that the ribbon may flex when said sections are moving relatively.

10. The electrically driven robot of claim 7 wherein said non-explosion-proof motors are non-sparking brushless servo motors.

11. The electrically driven robot of claim 9 wherein the electric motor within the second compartment is smaller than the electric motor within the first compartment so that the robot can be compact and easily balanced.

16. The robot of claim 7 wherein the gas supply is attached to one of said compartments.

23. The robot of claim 7 wherein said wrist mechanism is adapted for connecting with a fluid delivery tool such as a paint spray gun.

12. The method of electrically driving a plurality of relatively movable robot parts to manipulate said robot parts in a hazardous environment comprising the steps of:

providing a substantially airtight compartment in more than one of said robot parts so that such airtight compartments are movable relative to each other;

locating a lightweight non-explosion-proof motor for driving one of said robot parts in the airtight compartment next closest to the robot part being driven;

supplying electrical power to said motor from a power source outside said hazardous environment by means of flexible, lightweight non-explosion-proof wiring so that said wiring can flex when said robot parts are moving relatively;

housing said wiring in a substantially airtight conduit from said power source outside said hazardous environment which is in fluid flow communication with the airtight compartment in which said motor is located; and

supplying sufficient non-ignitable gas to said compartment and said conduit from a gas source outside said hazardous environment at a pressure above the pressure of said hazardous environment to compensate for any leakage from said compartment and prevent the entrance of gases from said hazardous environment to said compartment and said conduit while the non-ignitable gas being supplied surrounds the motor in said compartment and the wiring at said conduit, whereby to obviate the need that said motor and said wiring be heavy and explosion-proof so that the robot parts may be compact, lightweight and easily balanced.

13. The method of claim 12 wherein the supply of non-ignitable gas is sufficient in cooperation with the housing of said wiring in said conduit to facilitate the pressurization of said conduit from said power source wherever it houses said wiring.

14. A robot assembly comprising:

a base defining a substantially airtight first compartment;

an enclosure defining a substantially airtight second compartment and mounted for rotational movement on the base;

an arm assembly mounted for rotational movement on the enclosure and defining at least one substantially airtight compartment wherein the airtight compartments are successively mounted for rotational movement relative to each other and fluid communication therebetween;

a set of drive mechanisms, each set including at least one electric motor received in one or more of said compartments for effecting rotational movement of one compartment relative to another;

a conduit extending to the base and communicated to the first compartment;

a cable bundle extending from a robot controller, through the conduit and into the airtight first compartment of the base, the cable bundle having at least one cable connected to each set of drive mechanisms to operate the electric motor therein, and said cable bundle including at least one other cable that extends from the airtight first compartment of the base into the airtight second compartment and to each compartment in the arm assembly for connection to the drive mechanism to operate the electric motor thereof;

communicating means for fluidly communicating the first and second compartments, and the second and the at least one compartment of the arm assembly successively; and

a pressurized gas supply that feeds pressurized gas into the airtight first compartment of the base and thence into the conduit and the airtight second compartment of the enclosure and to the at least one compartment of the arm assembly.

17. The robot of claims 7 or 14 including a pressure sensing device for sensing pressure in said compartments and providing a signal when the pressure falls below a predetermined level.

18. The robot of claim 17 wherein said device comprises a pressure switch and wherein said switch is adapted to be coupled to a controller of the robot to provide said signal.

19. The robot of claims 7 or 14 wherein said pressurized gas supply includes a pressure regulator for regulating the pressure in at least one of the compartments.

20. The robot of claim 19 wherein the pressure regulator regulates said pressure to a positive pressure of at least 25 pascals.

21. The robot of claims 7 or 14 wherein the base is stationary.

22. The robot of claim 14 wherein the cable bundle is comprised of non-explosion-proof cables.

15. An industrial robot for use in an atmosphere containing an inflammable or explosive gas, comprising:

a stationary base unit having therein a first airtight chamber;

a rotatable body unit rotatably connected to said stationary base unit for rotation about a first axis and having therein a second airtight chamber which is fluidly communicated with said first airtight chamber;

an inner arm rotatably connected to said rotatable body unit for rotation about a second axis perpendicular to said first axis and having therein a third airtight chamber which is fluidly communicated with said second airtight chamber;

communicating means for fluidly communicating the first, second and third compartments;

an outer arm rotatably connected to said inner arm for rotation about a third axis parallel to said second axis and for supporting thereon a three-axis wrist assembly;

a first group of three electric drive motors, for driving said rotatable robot body unit, said inner arm and said outer arm, respectively, said electric drive motors being located in said second airtight chamber;

a second group of three electric drive motors, for driving said wrist assembly, said second group of electric drive motors being located in said third airtight chamber;

a first group of electric cables connected to said first group of three electric motors in said second airtight chamber and extending from the interior of said second airtight chamber through at least a portion of said communicating means into a fixed conduit fixedly connected to said stationary base unit;

a second group of electric cables connected to said second group of three electric motors in said third airtight chambers and extending from the interior of said third airtight chamber through at least a portion of said communicating means into said fixed conduit; and

an air supply conduit connected to said stationary base unit for supplying pressurized air to said first airtight chamber and through at least a portion of said communicating means to said second and third airtight chambers to maintain the interior of said airtight chambers at a predetermined pressure higher than atmospheric pressure outside said airtight chambers and thus prevent seepage of said inflammable or explosive gas into said airtight chambers.