Solvent-driven floating piston

Abstract

A system for dispensing paint includes a tank manifold having a paint input valve, a paint output valve, a push valve, and a solvent input / output line. The system also includes a paint can coupled to the can manifold, the paint can including a driven piston and a floating piston that define a paint volume therebetween and a solvent volume between the floating piston and the can manifold. A solvent input / output line is in fluid communication with the solvent volume and the push valve. When the paint output valve is open and the push valve is closed, the driven piston is actuated to push paint from the paint volume through the paint output line, and when the push valve is open, the driven piston pushes the floating piston to push solvent from the solvent volume through the solvent input / output line.

Description

Technical Field

[0001] The present disclosure generally relates to a fluid dispensing system, and more particularly, to a paint dispensing system including a paint tank having a driven piston and a floating piston, wherein a paint volume is defined between the driven piston and the floating piston, wherein actuation of the driven piston first dispenses paint from the paint volume in the paint tank and then dispenses solvent from the solvent volume in the paint tank. Background Art

[0002] A typical painting station for painting the exterior surface of a vehicle body in both continuous conveyor systems and stop station systems includes a spray booth, a plurality of painting robots arranged around it, and an opening / closing robot. These robots can be mounted on the floor, wall, ceiling, or side rails. The painting robot typically includes a spray gun or a rotary applicator for directing atomized paint onto the vehicle body. The spray booth has a complex environment and air handling equipment that processes and exhausts the vapor-laden air in the spray booth and prevents paint vapor from entering the operator passage where people are.

[0003] For a certain type of painting robot and a specific painting operation, a certain color of paint is loaded into a paint tank through a valve and manifold system. The paint tank is in fluid communication with the paint applicator through a hose and valve system. During the painting operation, a piston pushes the paint from the tank through the hose to the applicator for spraying onto the car body or other parts. The paint tank can be located in various locations inside and outside the spray room, including on the arm of the robot. Therefore, the length of the hose connecting the paint tank to the applicator can vary according to the design.

[0004] Vehicle paint is expensive, so every effort needs to be made to limit paint waste. The amount of paint loaded into the paint can for a specific painting job is carefully controlled and metered by software. When the desired amount of paint has been sprayed onto the vehicle body, the can should be empty. However, there is still unused and wasted paint in the hose between the paint can and the applicator, which is expensive. Summary of the invention

[0005] The following discussion discloses and describes a paint dispensing system including a paint applicator and a tank manifold having a paint input valve, a paint output valve, a push valve, and a solvent input / output valve. The system also includes a paint tank coupled to the tank manifold and having a chamber therein, wherein the paint tank includes a driven piston and a floating piston positioned within the chamber and defining a paint volume therebetween. The paint tank also includes: a solvent volume in the chamber and between the floating piston and the tank manifold; a paint input line extending through the floating piston and in fluid communication with the paint volume and the paint input valve; and a paint output line extending through the floating piston and in fluid communication with the paint volume and the paint output valve, wherein the solvent input / output line is in fluid communication with the solvent volume and the push valve. The paint dispensing line is coupled to the applicator and the tank manifold. When the paint output valve is open and the push valve is closed, the slave piston is actuated to push paint from the paint volume through the paint output line and through the paint dispensing line to the applicator, and when the push valve is open, the slave piston pushes the floating piston to push solvent from the solvent volume through the solvent input / output line and pushes paint through the paint dispensing line to the applicator.

[0006] Additional features of the present disclosure will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is an isometric view of the painting robot;

[0008] Figure 2 It is available with Figure 1 A schematic diagram of a type of paint dispensing system for use with a painting robot as shown;

[0009] Figure 3 It is available with Figure 1 A schematic diagram of another type of paint dispensing system for use with the painting robot shown; and

[0010] Figure 4 is an isometric view of a robotic system including a painting robot and a docking station. DETAILED DESCRIPTION

[0011] The following discussion of embodiments of the present disclosure relates to a paint dispensing system including a paint tank having a driven piston and a floating piston defining a paint volume therebetween, wherein actuation of the driven piston first dispenses paint from the paint volume in the tank and then dispenses solvent from the solvent volume in the tank, which is exemplary in nature and is in no way intended to limit the invention or its application or use. For example, although the discussion herein is directed to a paint dispensing system for a painting robot for painting vehicle parts, the paint dispensing system may have application for dispensing other coatings or fluids by other devices for other applications.

[0012] Figure 1 is an isometric view of a painting robot 10 mounted to a fixed base mount 12, wherein the robot 10 is intended to represent any painting robot suitable for the purposes discussed herein. A turntable or robot base 14 is rotatably mounted to the mount 12. An inner arm 18 is rotatably coupled to the base 14 by a joint 20, an outer arm 22 is rotatably coupled to the inner arm 18 by a joint 24, and a wrist member 26 is rotatably coupled to the outer arm 22 by a joint 28. An applicator 30 is fixedly attached to the wrist member 26 at an angle suitable for the paint application, wherein a paint spray 32 is shown as being ejected from the applicator 30.

[0013] Figure 2 It is available with Figure 1 Schematic block diagram of a paint dispensing system 50 for use with the painting robot 10 shown. It should be noted that although the discussion herein is directed to a painting robot that paints, for example, a car body, the paint dispensing system 50 may have applications for dispensing other coatings or fluids by other means for other applications. The system 50 includes a dispensing subsystem 52 and an applicator 54, such as the applicator 30, such as a rotary sprayer having a trigger valve 58, which are connected by a paint dispensing line 56. The dispensing subsystem 52 may be mounted to the outer arm 22 of the robot 10 (see FIG. 1 ). Figure 1 ), where the coating source 64, solvent source 72 and solvent source 144 will be located at another location and perpendicular to the subsystem 52. The applicator 54 will be part of the end effector on the robot 10 and located in the spray chamber.

[0014] The dispensing subsystem 52 includes a paint manifold 60 having a plurality of color valves 62 that are selectively opened to obtain paint from a plurality of paint sources 64 and provide the paint to an isolated line 68. The paint manifold 60 also includes a solvent valve 70 that is selectively opened to provide solvent from a solvent source 72 on the isolated line 68. The paint manifold 60 also includes a dump valve 74 for releasing solvent and air from the dispensing subsystem 52 to a dump outlet 78. The paint manifold 60 includes a vacuum valve 76 that is coupled to a vacuum source for evacuating air from the channels before the channels are filled with paint.

[0015] The dispensing subsystem 52 also includes a tank manifold 80 having a paint tank 82 attached thereto, wherein the tank 82 includes a chamber 84. The tank 82 also includes a driven piston 86 and a floating piston 88, which define a paint volume 92 therebetween in the chamber 84, and when the tank 82 is loaded with paint, the paint volume holds a predetermined volume of paint. The driven piston 86 can be motor-driven, pneumatically driven, fluid-driven, etc. A solvent volume 94 is disposed in the chamber 84 and between the floating piston 88 and the manifold 80, which holds a certain volume of solvent, as will be discussed in detail below. The paint input line 100 allows the volume 92 to be filled with paint from the isolation line 68 through the paint input valve 102, and the paint output line 104 allows paint to be dispensed from the paint volume 92 through the paint outlet valve 106 into the paint dispensing line 56 by movement of the piston 86, wherein the lines 100 and 104 are rigidly attached to the floating piston 88. When the paint volume 92 is empty or nearly empty, the solvent input / output line 110 allows the volume 94 to be filled with solvent through the push valve 112, and allows the solvent in the volume 94 to be pushed into the paint dispensing line 56 to push the paint therein into the applicator 54, wherein the slave piston 86 pushes the floating piston 88 to force the solvent out of the volume 94. As the volume 94 is filled with solvent through the line 110, air is removed therefrom through the vent line 114 and the vent valve 116, and then through the isolation line 68 to the dump outlet 78. A pair of valves 120 and 122 in manifold 80 allow various lines in manifold 80 to be cleaned and dried with a solvent, as will be described in further detail below.

[0016] The distribution subsystem 52 also includes a clean manifold 130 having valves 132, 134 and 136, which are connected to valves 120 and 122 in the manifold 80 through an isolation line 138. Valve 134 is a vacuum valve, which is used to extract air from the pipeline before filling the paint. A solvent source 144 provides solvent to the manifold 130 through valve 136. An air source 148 provides dry air to the manifold 130 through valve 132. The paint tank 82 and the applicator 54 are under high voltage, and the paint manifold 60 and the clean manifold 130 are grounded by a fluid supply device during the painting operation. Therefore, the tank 82 must be electrically isolated from the paint manifold 60 and the clean manifold 130 to prevent ground faults. Therefore, during the painting operation, the isolation lines 68 and 138 are empty and clean to provide electrical insulation.

[0017] The various valves and devices described above are appropriately controlled to provide the following operations. When the paint volume 92 is filled with paint, the solvent volume 94 is filled with solvent, and the paint process is ready to proceed, the slave piston 86 is actuated and the valve 106 is appropriately controlled to distribute the paint into the paint pipeline 56 to be sprayed onto the vehicle body by the applicator 54. The push valve 112 is closed and the floating piston 88 does not move. When the paint volume 92 is close to empty, the valve 106 is closed, and the push valve 112 is pneumatically actuated, for example, by software control, wherein the valve opening time point can be based on the torque sensed by the slave piston 86, the pressure in the tank 82, the properties of the paint and the solvent, the paint flow rate, the required total amount of paint and / or other process parameters. The control of the push valve 112 is adjustable and can be directly input or obtained from a lookup table. When the push valve 112 is opened, the floating piston 88 is pushed downward by the slave piston 86 so that the solvent is distributed into the paint pipeline 56 to push the paint in the pipeline 56 into the applicator 54. As piston 88 moves downward, lines 100 and 104 move through suitable seals into manifold 80. When solvent volume 94 becomes empty, most of the paint dispensing lines 56 are filled with solvent, and the painting operation stops.

[0018] In one possible configuration, after completing the above-mentioned dispensing sequence, the dispensing subsystem 52 begins to prepare for the next coating operation. The driven piston 86 is withdrawn a small amount upward from the floating piston 88. The solvent is pushed into the solvent volume 94 from the solvent source 144 through valves 136, 122 and 112, and the air is flushed out from the solvent volume 94 to the pour outlet 78 through the cleaning valve 116. The pour outlet 78 is closed, and the solvent from the source 144 fills the solvent volume 94. After the solvent volume 94 is filled, the solvent from the source 144 and the air from the source 148 are used to clean the paint volume 92, and finally come out from the pour outlet 78. Then the paint volume 92 and the isolation line 68 are dried. Vacuum is drawn from the isolation line 68 and the paint volume 92 to remove the air before filling the volume 92 with paint. Then, the volume 92 is filled with paint from a paint source 64. The excess paint in isolation line 68 is then pushed into paint volume 92 by the solvent from solvent source 72. Paint line 56 is then filled with solvent from volume 92, and isolation lines 68 and 138 are cleaned and dried.

[0019] The construction of coating tank 82 provides many advantages.Isolated coating and solvent volume 92 and 94 are controlled by a single drive device, such as a ball screw and a motor.Because coating volume 92 and solvent volume 94 are located on opposite sides of floating piston 88 in the same tank 82, equal and opposite forces are applied to piston 88, and the pressure in volume 92 and 94 is similar.Solvent push valve 112 can be pneumatically actuated based on the I / O from controller.Open push valve 112 and start solvent push sequence time point can be based on the pressure in tank 82, driven piston motor torque, tank position, flow rate, the coating used and the property of solvent, required coating total amount or any other parameter to adjust.Therefore, the actuation of valve 112 is not limited to opening based on position only.Push valve 112 can be opened before piston 86 and 88 collide, thereby allowing floating piston 88 to start moving before contacting with driven piston 86. The push valve 112 can be accessed without removing the tank 82 or removing the slave piston 86 from the manifold 80. The push valve 112 can be easily accessed and maintained from the outside of the manifold 80. Since the floating piston 88 is connected to the tank manifold 80, it only travels the distance required to push the paint dispensing pipeline 56 to the applicator 54, which is less than 10 mm instead of hundreds of millimeters. The solvent volume 94 is static while dispensing paint from the paint volume 92 until the push valve 112 opens. The inlet and outlet of the solvent volume 94 are static, and therefore there is no hose or pipe connection that must be bent or flexed inside the chamber 84 and move the entire stroke of the tank 82.

[0020] Various other designs of dispensing subsystems may be used in conjunction with tank manifold 80 and coating tanks 82 . Figure 3It includes Figure 1 Schematic block diagram of a paint dispensing system 150 of a dispensing subsystem 152 used with the painting robot 10 shown, wherein the same elements as the system 50 have the same reference numerals. In this embodiment, the cleaning manifold 130 is removed, and the paint line flushing valve 158 is connected to the applicator 54. The pipeline 156 brings the solvent to the applicator 54 to clean the paint line 56, and finally passes through the dump isolation line 170. The design of the paint manifold 60 is slightly different from the dispensing system 52. In particular, the second solvent source 160 is connected to the paint manifold 60 through the valve 162, and the air source 164 is connected to the paint manifold 60 through the valve 166. The operation of the tank manifold 80 and the paint tank 82 is substantially the same as the paint dispensing system 50 described above; however, the tank manifold 80 has a dump outlet attached to it through the dump isolation line 170 to allow the paint line 56 to be flushed without sending the paint out of the applicator trigger valve 168.

[0021] For the above discussion, fluid sources, specifically a paint source and a solvent source, are connected to the robot 10. In an alternative embodiment, other techniques may be used to provide the paint and solvent. Figure 4 1 is an isometric view of a robot system 180 including a robot 182 and a docking station 184 that receives various fluids on fluid supply lines 186 from suitable sources, wherein like elements as the robot 10 are indicated by like reference numerals. In this embodiment, the robot 182 includes a dispensing subsystem 188 that does not include a paint manifold as described above, where a paint manifold of the type discussed above would be located on the docking station 184, and thus the isolation line 68 is removed. The robot 182 is assembled and configured to dock to the docking station 184 so that paint and solvent can be provided to the tank manifold 80 located on the robot 182.

[0022] The foregoing discussion discloses and describes only exemplary embodiments of the present disclosure. Those skilled in the art will readily recognize from this discussion and from the accompanying drawings and claims that various changes, modifications and variations may be made therein without departing from the spirit and scope of the present disclosure as defined in the appended claims.

Claims

1. A system for dispensing a fluid, the system comprising: a tank manifold including fluid input valves, fluid output valves, push valves, and solvent input / output lines; as well as a fluid tank coupled to the tank manifold and having a chamber therein, the fluid tank including a slave piston and a floating piston, the slave piston and the floating piston being positioned within the chamber and defining a fluid volume therebetween, the fluid tank further comprising: a solvent volume in the chamber and between the floating piston and the tank manifold; a fluid input line extending through the floating piston and in fluid communication with the fluid volume and the fluid input valve; and a fluid output line extending through the floating piston and in fluid communication with the fluid volume and the fluid output valve, wherein the solvent input / output line is in fluid communication with the solvent volume and the push valve, and wherein, when the fluid output valve is open and the push valve is closed, the slave piston is actuated to push fluid from the fluid volume through the fluid output line, and when the push valve is open, the slave piston pushes the floating piston to push solvent from the solvent volume through the solvent input / output line.

2. The system of claim 1 further comprising a fluid applicator and a fluid distribution line coupled to the fluid applicator and the tank manifold, wherein When the slave piston is actuated to push fluid from the fluid volume, the fluid is pushed through the fluid dispensing line to the fluid applicator, and when the slave piston is actuated to push the floating piston and push solvent from the solvent volume to the fluid applicator, the fluid is pushed through the fluid dispensing line to the fluid applicator.

3. The system according to claim 1, wherein: The fluid input line and the fluid output line are rigidly coupled to the floating piston, and wherein the fluid input line and the fluid output line are pushed into the tank manifold when the floating piston is pushed by the driven piston.

4. The system according to claim 1, wherein: The tank manifold further includes a vent valve and a vent line in fluid communication with the solvent volume, and wherein the vent line and vent valve allow air to be removed from the solvent volume as the solvent volume is filled with solvent via the solvent input / output line.

5. The system according to claim 1, further comprising: fluid supply manifold; a plurality of different fluid sources coupled to the fluid supply manifold; an isolation line coupled to the fluid supply manifold and the tank manifold; and a solvent source coupled to the fluid supply manifold, the fluid supply manifold including a plurality of valves controlled to provide solvent from the solvent source and to provide fluid to the tank manifold.

6. The system according to claim 5, wherein: When the fluid tank is dispensing the fluid, the isolation line is empty to electrically isolate the fluid supply manifold from the tank manifold.

7. The system according to claim 1, wherein: The push valve is actively controlled by software and has a valve opening time point based on one or more of the following: torque sensed by the slave piston, tank position, properties of the fluid and solvent, fluid flow rate, dispensing pressure, and total amount of fluid required.

8. The system according to claim 1, wherein: The system also includes a vacuum source in fluid communication with the fluid volume for drawing air from the fluid volume.

9. The system according to claim 1, wherein: The fluid is paint and the system is part of a painting robot.

10. A robot system comprising a painting robot and a paint dispensing system, the paint dispensing system comprising: paint applicators; tank manifold, including paint input valves, paint output valves, push valves, and solvent input / output lines; a paint tank coupled to the tank manifold and having a chamber therein, the paint tank including a driven piston and a floating piston, the driven piston and the floating piston being positioned within the chamber and defining a paint volume therebetween, the paint tank further comprising: a solvent volume in the chamber and between the floating piston and the tank manifold; a paint input line extending through the floating piston and in fluid communication with the paint volume and the paint input valve; and a paint output line extending through the floating piston and in fluid communication with the paint volume and the paint output valve, wherein the solvent input / output line is in fluid communication with the solvent volume and the push valve; and a paint dispensing line coupled to the paint applicator and the tank manifold, wherein when the paint output valve is open and the push valve is closed, the slave piston is actuated to push paint from the paint volume through the paint output line and through the paint dispensing line to the paint applicator, and when the push valve is open, the slave piston pushes the floating piston to push solvent from the solvent volume through the solvent input / output line and through the paint dispensing line to the paint applicator.

11. The robot system according to claim 10, wherein: The paint input line and the paint output line are rigidly coupled to the floating piston, and wherein when the floating piston is pushed by the driven piston, the paint input line and the paint output line are pushed into the tank manifold.

12. The robot system according to claim 10, wherein: The tank manifold further includes a vent valve and a vent line in fluid communication with the solvent volume, and wherein the vent line and vent valve allow air to be removed from the solvent volume as the solvent volume is filled with solvent via the solvent input / output line.

13. The robot system according to claim 11, wherein: The paint dispensing system also includes a paint manifold; a plurality of paint sources of different colors coupled to the paint manifold; a paint isolation line coupled to the paint manifold and the tank manifold; and a first solvent source coupled to the paint manifold, the paint manifold including a plurality of valves controlled to provide solvent from the first solvent source and to provide paint to the tank manifold.

14. The robot system according to claim 13, wherein: The paint dispensing system also includes a purge manifold, a purge isolation line coupled to the tank manifold and the purge manifold, and a second solvent source coupled to the purge manifold, the purge manifold including a plurality of valves configured to provide solvent from the second solvent source to the solvent volume.

15. The robot system according to claim 14, wherein: The plurality of valves in the cleaning manifold are also configured to deliver solvent for cleaning the paint dispensing lines and the paint isolation lines.

16. The robot system according to claim 14, wherein: When the paint tank is dispensing paint, the isolation line is empty to electrically isolate the paint manifold and the purge manifold from the tank manifold.

17. The robotic system of claim 10, further comprising a docking station and a plurality of different fluid sources providing fluid to the docking station, the docking station being operably coupled to the paint dispensing system to provide paint and solvent to the paint dispensing system.

18. The robot system according to claim 10, wherein: The paint dispensing system also includes a vacuum source in fluid communication with the paint volume for drawing air from the paint volume.

19. The robot system according to claim 10, wherein: The push valve is actively controlled by software and has a valve opening time point based on one or more of the following: torque sensed by the slave piston, tank position, properties of paint and solvent, fluid flow rate, dispensing pressure, and total amount of paint required.

20. A system for dispensing a coating, the system comprising: tank manifold, including paint input valves, paint output valves, push valves, and solvent input / output lines; a paint tank coupled to the tank manifold and having a chamber therein, the paint tank including a driven piston and a floating piston, the driven piston and the floating piston being positioned within the chamber and defining a paint volume therebetween, the paint tank further comprising: a solvent volume in the chamber and between the floating piston and the tank manifold; a paint input line extending through the floating piston and in fluid communication with the paint volume and the paint input valve; and a paint output line extending through the floating piston and in fluid communication with the paint volume and the paint output valve, wherein the solvent input / output line is in fluid communication with the solvent volume and the push valve, and wherein when the paint output valve is open and the push valve is closed, the driven piston is actuated to push paint from the paint volume through the paint output line, and when the push valve is open, the driven piston pushes the floating piston to push solvent from the solvent volume through the solvent input / output line; and A paint applicator and a paint distribution line coupled to the paint applicator and the tank manifold, wherein when the slave piston is actuated to push paint from the paint volume, paint is pushed through the paint distribution line to the paint applicator, and when the slave piston is actuated to push the floating piston and push solvent from the solvent volume, paint is pushed through the paint distribution line to the paint applicator.

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