JPH05237790A - Electric robot used in hazardous location - Google Patents

Abstract

PURPOSE: To provide a robot which is used in a hazardous environment, which is compact, and which has a pair of pressurizing chambers for accommodating electric motors. CONSTITUTION: An electric robot incorporates a base 12, an arm assembly 18, and a first and second drive systems respectively incorporating a first and second motors. At least one of the motors is located in the first pressurizing chamber located within the base 12, and at least one of the motors is located in the second pressurizing chamber located within the arm assembly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric drive robot used in a dangerous environment, and more particularly to an electric drive robot operable in an environment containing combustible gas or vapor.

[0002]

BACKGROUND OF THE INVENTION Many paint spray machines have been introduced to paint mass-produced products such as car bodies. Generally, such paint spray machines
There was a limitation in its use in that a human operator had to correct an area that the machine was not good at. Such machines are also only designed to paint in horizontal and / or vertical paths on a reciprocating system. In order to paint an object completely, depth and lateral motions are required if the object's contour is complex. Using the wrist allows the operator to paint and
This is important because it is often required when angling the spray gun to apply paint to complex contoured surfaces.

Many of the prior art paint spray machines include a battery-powered spray gun supplied from a large volume central paint reservoir that attempts to paint most of the exterior surface. Inaccessible areas such as wheel arches, inside trunks and engine compartments, and door edges must be painted by an operator who finds unpainted areas after the car body has undergone an automatic painting process.

Painting machines, including electric painting devices, are disclosed in many prior art patents. These patents include Chapman U.S. Pat.No. 2,858,947, Shelley U.S. Pat. U.S. Pat.No. 4,196,049, Siam U.S. Pat.Nos. 4,398,863 and 4,407,625, Jacot-Desconmbeth et al. U.S. Pat.No. 4,424,472, and Gorman U.S. Pat.
It is No. 4,473. Pollard U.S. Pat.No. 2,213,108,
And No. 2,286,571 both disclose electric robots for paint spraying. Stricker U.S. Pat. No. 4,170,751 also discloses an electrical device associated with a paint spray cobot.

There are many reasons to use spray robots to produce commercial quality paint finishes on mass produced products. Robots are desirable because they can handle harsh paint environments, allow the paint process to consume less energy overall, and improve paint quality, which in turn leads to lower material and labor costs. .. The above advantages are especially important when painting the body of a car, where high production rates are expected and where a relatively short amount of time is used to complete a few paintings rather than one painting. Is.

Spray robots are also used for enamelling and / or powdering surfaces. For example, when applying glassy enamel to a plastic bathtub, many of the same techniques are used as when applying paint to a vehicle body. The robots that have been used for spray painting consist of machines with continuous paths that are comparable to the movements of a human operator. Generally, such robots are educated by having paint specialists teach each robot in a learning mode through the actual painting job.

The average spray booth in the automotive industry has been standardized to have a relatively small width. Such a small width limits the size and movement of robots used in such spray booths. Redesigning the existing spray booth is not cost effective. Conventional paint spray
The use of robots with electric drives is at first glance why small electric robots are more cost effective than small hydraulic robots because the size of robots available in the booth is limited. More desirable. Such costs include installation costs and other operational costs as well as robot costs. However, in paint spraying and other similar uses, it may be advantageous to use hydraulic or pneumatic drives in some circumstances. In such an environment, there is a danger of explosion of the electric motor, so the electric robot must either be explosion resistant or intrinsically safe not to ignite a combustible environment. Hydraulically powered robots generally do not use sufficient electrical energy to ignite an explosive fuel-air mixture.

National Electricity Law NFPA 70, 500th
Article-specified "danger" (ie, first-class Category 1 location)
Electrical equipment located in areas classified as must be placed in pressurized containers or made explosion resistant. If such measures are taken, the peripheral area of the electrical device is no longer classified as a Category 1 location. Rather, only the location adjacent to the closed or explosive resistant container is classified as a Category 1 location of the first class containing concentrations that allow ignition of flammable gases and vapors under normal operating conditions. To pressurize the closed container, combustible gas that sometimes flows into the container by supplying clean air or inert gas to the container with or without continuous flow at sufficient pressure. It is necessary to keep steam out. When the electrical device is energized, the container should be at least 25 pascals (0.1 inch (approximately
Maintaining a pressure of (2.5 mm) of water) substantially eliminates the risk of explosion in "dangerous" environments.

One way to comply with the above criteria is to make containers for devices such as motors explosion resistant. However, using an explosion-proof motor not only increases the cost of the motor, but also increases the weight and size of the robot. Moreover, the use of explosive resistant motors requires the use of explosive resistant motors. Not only are such cables expensive and heavy, they are also inflexible and cumbersome. Such explosive resistant motors and cables also occupy valuable space within or on the robot, as a result, within the paint spray booth.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved electric drive robot for use in hazardous environments. Another object of the present invention is to provide a robot that is relatively compact for use in a hazardous environment and that has a pair of pressure chambers for housing an electric motor therein.

Yet another object of the present invention is to provide a relatively compact and inexpensive electric drive robot for use in hazardous environments. The robot includes a base, an arm assembly, and first and second drive systems having first and second electric motors, respectively, wherein at least one electric motor is located within the base. Located in the pressure chamber and at least one electric motor in a second pressure chamber located inside the arm assembly.

In carrying out the above and other objects of the invention, a base having a first pressurizing chamber within which an electrically driven robot constructed according to the invention is contained and a second inside thereof. And an arm assembly having a pressurizing chamber.
The arm solid is supported for movement on the base at one end thereof. The arm assembly includes a wrist for connecting its opposite end to a fluid ejection tool.
The robot also includes first and second drive systems. The first drive system comprises at least one electric motor arranged in the first pressure chamber to drive the arm assembly. The second drive system comprises at least one electric motor arranged in the second pressure chamber to drive the wrist.

The electric motor preferably comprises a brushless servomotor commonly known as a brushless DC motor or AC servomotor. Moreover,
The robot preferably comprises a cable housed in a pressure line attached to the outer surface of the base.
The cable is electrically connected to the electric motor and adapted to be connected to the robot controller. The conduit fluidly communicates with the first and second pressure chambers.
Therefore, the cable may consist of commonly used cables rather than strong, explosion-proof cables.

The pressurizing means is provided with a pressure regulator for applying a positive pressure to the first and second chambers, and more preferably in the conduit thereof. Electric spray robots made in this way are not only relatively small and lightweight, but also cheaper than hydraulically driven robots. The electric spray robot is also equipped with normally used cables, does not require the use of strong, explosion-proof cables, and does not have the disadvantages associated therewith. The use of a pair of pressure chambers-one of which is located within the arm assembly-reduces the gearing and other mechanisms required therein to provide rotational movement of the drive motor to the arm assembly. To a wrist mechanism attached to the free end of the.

Other advantages of the invention will be appreciated by reference to the accompanying drawings and examples.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a paint made according to the present invention.
A spray robot is shown. The whole of this paint spray robot is shown by the number 10. The robot 10
The base 12 includes an upper base portion 14 and a lower base portion 16. The upper base portion 14 is rotatable with respect to the stationary lower base portion 16. The robot 10 also includes an arm assembly 18, one end of which is pivotally connected to the upper base portion 14 and the other end of which is pivotally connected to an outer arm 22. An inner arm 20 is included. The wrist or wrist mechanism 24 is connected to the free end of the outer arm 22 and preferably comprises a three axis wrist mechanism.
The wrist mechanism 24 is adapted to have a spray tool such as a paint spray gun at its free end.

As explained below, the robot 10 is
With an air system for pressurizing the base 12 and arm assembly 18, there is no need to use an explosion-proof electric motor with an internal spark-free electric motor. Moreover, because the electric motor that drives the wrist mechanism 24 is in the arm assembly 18 rather than in the base 12, less gearing is required to interconnect the electric motor to the wrist mechanism. The second pressure chamber can be located within the inner arm as described herein and, if desired, within the outer arm 22.

As shown in FIG.
It is intended for use in hazardous surroundings or environments, such as the interior of a paint spray booth having a wall shown at 6. The lower base portions 16 are horizontally and adjustably mounted such that the jack assemblies are respectively located in the lower corners of the lower base portion 16 as best shown in FIG.

The area within the paint spray booth has a sufficient concentration of combustible gas or vapor in the air, and its location is at the risk level specified by Article 500 of NFPA 70, which is the National Electricity Act. To be done. In such an environment, the explosive solvent-air mixture contained therein is highly flammable in nature, thus creating the risk of explosion or fire.

The robot power and control signals are provided by a cable (not shown), which extends from the robot roller, outside the paint spray booth. The pressure line 30 contains a cable,
It is attached to the lower base portion 16. The lower base portion 16 is adapted to be connected to the pressurizing conduit 30 by an adapter plate 34, and the adapter plate 3
4 is further attached to the front housing plate 36 of the lower base 16 by bolts 32. The cable contained within conduit 30 extends through a passage 38 extending through front wall 36 and is electrically coupled to terminal strip 40 as shown in FIG.

The adapter plate 34 is provided in the air inflow passage 4
2 which is in fluid communication with an air inflow tube 44 which extends through the paint spray booth wall 26 to provide relatively clean air and Active gas flows into the lower base portion 16 from around the paint spray booth. After flowing through the air inlet passage 42, the air flows through the pipe 46,
6 is fluidly connected to a pressure regulator 48. The adjuster 48 is attached to the inner wall 50 of the lower base portion 16. The inner wall 50 defines an inner chamber 59 of the lower base portion 16.

The pressure regulator 46 ensures that the air pressure is within the first chamber 52 within the lower base portion 16 for a predetermined limit. Included in this first chamber is a low pressure switch 54, which indicates that the pressure in the first chamber 52 is below the pressure that the pressure regulator 48 is trying to maintain. Is. The pressure switch 54 is
A tube 56 connects the unpressurized chamber 59 with a connector 58 as a means of approaching the reference ambient pressure level. The pressure switch 54 is also connected to the robot controller 28 by a cable (not shown) to provide the alarm signal, indicating that the robot must be stopped because the pressure in the first chamber is low. ..

The pair of umbrella-shaped holes 60 also includes the first chamber 52 and the inner wall 5.
It is provided between the inner chamber 59 and the inner chamber 59 of 0, and reduces the excess pressure generated by the pressure regulator 48 above the maximum predetermined limit value. The umbrella hole 60 transmits excess pressure from the first chamber 52 to the inner chamber 59. The first chamber 52 is provided with an opening 64 formed in the upper wall of the lower base portion 16,
It fluidly communicates with a second chamber 62 formed in the upper base portion 14. The opening 64 is aligned with the opening 66 formed in the drive plate 68 disposed between the upper base portion 14 and the lower base portion 16. Further, the opening 66 is aligned with the opening 76 formed in the collar member 72, and the collar member 72 is attached to the drive plate 68 by a mounting bolt 74 as shown in FIG. There is. The circular seal 78 is the collar member 72.
And between the lower wall of the upper base portion 14 and
The chamber 52 that relatively rotates between the collar member 72, the attachment plate 68 thereof, and the upper base portion 14 is sealed.

An orienting means or mechanism, shown at 80, is attached and secured to the collar member 72 and supports a plurality of commonly used cables. This cable 82
Are electrically connected to the terminal strip 40 in the lower chamber 52. As shown in FIGS. 4 to 6,
The cable 82 is relatively flexible, and the cable 82 can be formed into a ribbon shape that can be bent along a relatively small radius of curvature. The cable is so flexible that it allows the collar member 72 to bend its ribbon like shape during relative rotation between the directing mechanism 80 and the upper base portion 14.

Each cable 82 includes three smaller cables 84 included therein. Two small cables 84 are used for each electric drive motor 86 of the electric drive system mounted inside the upper chamber 62. One small cable 84 supplies the power signal and the other small cable 84 supplies the control signal. The drive motor 86 moves the upper chamber 62
3 are arranged, and one is arranged for each of the rotation axes of the arm assembly 18. The drive motor preferably comprises a sparkless brushless servomotor, as is commonly known as an AC servomotor or a brushless DC motor.

The two cables 82 are routed and fixed so as to reach the inside of the third pressurizing chamber 88 contained in the inner arm 20, as shown in FIGS. 6 and 7. ing. The cable runs from the second pressure chamber 62 to the inner arm 2
No. 0 outside wall 92 and through the opening formed in the outside wall of the upper base portion 14 to the third pressurizing chamber 88. The cables 82 are electrically connected to the electric motors 94 mounted in the third chamber 88, respectively.
A more detailed description of the particular construction and operation of the ribbon of cable 82 is "Atlantic Docket Number P-306, filed on the same date as this application," Improved Cable Routing and Fixing "with the same assignee. Robot with Law
It has been filed in a US patent application entitled "With Improved Cable Routing and Clamping)."

A drive shaft 96 of the motor 94 extends through an inner wall 98 that limits the pressure chamber 88, and is drivingly engaged with each timing belt 100. The timing belt 100 is further operatively connected via a hollow coaxial drive tube to gear devices for driving the separate shafts of the three shaft wrist mechanism 24, respectively.

[0028]

EFFECTS OF THE INVENTION Several purification holes (not shown) are provided in the chambers 52, 6
A combustible gas or vapor that is provided on the inner wall that limits 2, 88, each chamber being provided with clean air or an inert gas with sufficient flow and pressure to contaminate all chambers. Is reduced to an acceptable and safe concentration. The pressure regulator 48 is provided with a manual bypass to allow this purging action when needed.

Moreover, in order to maintain the positive pressure inside the chambers 52, 62, 88 without excessive flow of air,
Appropriate seals may be provided between the various moving and non-moving parts of the robot. By adopting the above configuration, it is possible to use a relatively small and inexpensive electric robot in a dangerous environment such as that found in a conventional paint spray booth. Pressurization chamber 52, 6
2 and 88 are in fluid communication with each other to prevent flammable gases and vapors from entering the chamber containing the electrical device containing the electric drive motor.

By providing the pressure chamber 88 within the arm assembly 18, the number of inter-gear devices for driving the various axes of the wrist device 24 is significantly reduced. Furthermore, the need for a relatively heavy and high quality explosion resistant motor mounted either within the robot 10 or on its exterior surface by using various non-sparking motors in the pressurized chamber. There is no sex. By using an electric motor that does not generate sparks in the pressure chamber, the cable that supplies the power signal and control signal to the electric motor may be a commonly used cable, which is expensive and relatively Another advantage is that it does not have to be a strong, non-flexible, explosion-proof cable.

Although the invention has been described descriptively, it is to be understood that the terminology used has the property of describing, rather than limiting. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. Therefore, it is to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically described.

[Brief description of drawings]

FIG. 1 is a perspective view of an electric spray robot according to the present invention.

FIG. 2 is a side elevational view of a lower base portion of the robot of FIG.

3 is a side elevational view of the lower portion of FIG. 2 showing the various components included therein.

FIG. 4 is a side elevational view of various cables of the robot, showing the outer housing structure of the robot in phantom.

5 is an enlarged view of a portion of FIG. 4, showing a sealing mechanism between the upper and lower portions of the base.

FIG. 6 is a plan view of the cable of FIG. 4 showing other various elements of the robot by chain lines.

FIG. 7 is a plan view of the inner arm of the robot.

[Explanation of symbols]

 10 Paint Spray Robot 12 Base 14 Upper Base Part 16 Lower Base Part 18 Arm Assembly 20 Inner Arm 22 Outer Arm 24 Wrist 28 Robot Controller 48 Pressure Regulator 52 First Chamber 62 Second Chamber 86 Drive Motor 82 normal use cable 94 electric motor

Claims (3)

[Claims] 1. A compact and lightweight electric drive robot (10) used in a dangerous environment and controlled from outside the dangerous environment, the robot comprising a base (12) and a base (12). An arm assembly (18) supported for movement over said base (12)
And the arm assembly (18) forms a plurality of substantially enclosed chambers (52, 62, 88) including a first chamber (62) and a second chamber (88) that are relatively movable, and further A robot is provided with at least one electric motor (86) contained in the first chamber (62) and at least one electric motor (94) contained in the second chamber (88). A cable (82) extending from the outside and connected to each of the motors (86, 94) in the first chamber (62) and the second chamber (88) to operate the motors (86, 94). A means for forming first and second openings (90) in the base (12) and the arm assembly (18); and including the first and second openings (90), Relative movement of the first chamber (62) and the second chamber (88) Means for maintaining a substantially sealed communication between the first chamber (62) and the second chamber (88), and a means for maintaining a pressure in the dangerous environment at a pressure higher than the dangerous environment. Concentration of dangerous gas from an external gas source through the opening (90) into the chambers (62, 88) sufficient to enter the chambers (62, 88) by purification. Is continuously reduced to the permissible level and the chambers (62, 88) are maintained at a pressure above the hazardous environment to prevent inflow of the hazardous gas, and the chamber (6
2,88) and pressurizing means for compensating for any leakage through the opening (90), said first so that said motors (86,94) are non-explosion resistant and lightweight. When the chamber (62) and the second chamber (88) move relative to each other, both in the first chamber (62) and the second chamber (88), and in the first and second openings. In the section (90), the maintenance means (48) for automatically maintaining the pressure within a permissible range equal to or higher than the pressure of the dangerous environment, and the first and second openings are aligned and communicate with each other. Said means for flexibly directing said cable between said chambers through said aligned first and second openings, and said cable being non-explosive resistant, and To maintain the said when the cable bends so that it is flexible Robot, characterized by maintaining the pressure in the first and second opening means has the alignment. 2. A lightweight non-explosion resistant electric motor in at least one chamber of the part of the robot being driven electrically connects a plurality of segmented robot parts relatively movable in a hazardous environment. Driving the compartments of the robot so that the compartments are substantially sealed when the parts of the robot are movable relative to each other, and an inert gas is applied to the compartments with sufficient flow and pressure through the compartments. And providing a purging hole for the chamber to reduce the concentration of any hazardous gas that contaminates the chamber to an acceptable level, and a gas source external to the hazardous environment at a pressure above the pressure of the hazardous environment. Supply sufficient inert gas from the chamber to continuously reduce the concentration of dangerous gas polluting the chamber to an acceptable level by purification through the purification hole, and to a pressure above the hazardous environment. Previous A chamber is maintained to prevent the ingress of the hazardous gas, and when the supplied inert gas surrounds the motor in the chamber, compensates for any leakage from the chamber and the purging holes, thereby A method comprising removing the requirement that the motor be heavy and explosive resistant so that parts of the robot are compact and lightweight. 3. Power is supplied from a power source external to the hazardous environment to the motor by a flexible, lightweight, non-explosion resistant wire such that the wire bends when parts of the robot move relative to each other. Supplying, accommodating the wire in a substantially sealed conduit from the power source external to the hazardous environment in fluid communication with the enclosed chamber in which the motor is located, a gas above the pressure of the hazardous environment Supplying sufficient inert gas from a source to the conduit to prevent the inflow of gas from the hazardous environment into the conduit when the inert gas being supplied surrounds the wire in the conduit; 3. The method of claim 2 comprising removing the requirement that the wires be heavy and explosion resistant so that parts of the robot are more compact and lightweight.