The invention relates generally to spray devices and, more particularly, to the transfer efficiency of spray guns.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
The objective when spraying paint is to maximize the amount of coating material that is deposited on the substrate and minimize the amount that goes into the atmosphere. High volume low pressure (HVLP) and high transfer efficiency (HTE) spray guns have been designed and mandated in many jurisdictions to limit the amount of overspray due to the paint bouncing back off the substrate. However, there is another major reason for overspray that has not been addressed. This is overspray created when the spray gun is triggered, but not pointed at the substrate. This is a common occurrence in the automotive refinishing business. For example, if a painter is painting the hood of a car, the painter should trigger the fluid off at the end of the stroke and trigger the fluid back on for the return stroke. This avoids spraying paint into the air at the end of each stroke. However, the painters find it easier to hold the trigger fully open as they reach the end of the stroke and reverse directions. This practice can lead to significantly higher material costs and significantly higher volatile organic compound (VOC) emissions into the atmosphere.
A spray gun, in one embodiment, is provided with a sensor configured to monitor distance between the spray gun and a target object, and a drive responsive to the sensor, wherein the drive is configured to control a fluid valve of the spray gun based on the distance. A retrofit kit, in another embodiment, is provided with a feedback-controlled system configured to change fluid flow of a spray gun in response to one or more sensed parameters indicative of condition of a target object, a relationship between the spray gun and the target object, or a combination thereof. A spray controller, in a further embodiment, is provided with a control configured to terminate or decrease fluid flow of a spray in response to a first spray stroke away from a target object, and configured to start, continue, or increase fluid flow of the spray in response to a second spray stroke toward the target object. In yet another embodiment, a method of operation is provided for controlling fluid flow in response to feedback associated with a target object. In addition, a tangible medium is provided with instructions stored on the tangible medium, wherein the instructions comprise code configured to terminate or decrease fluid flow of a spray if the spray is not directed toward a target object, and code configured to start, continue, or increase fluid flow of the spray if the spray is directed toward the target object.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
The spray coating gun 12 may be coupled to a variety of supply and control systems, such as the fluid supply 16, an air supply 18, and a control system 20. The control system 20 facilitates control of the fluid and air supplies 16 and 18 and ensures that the spray coating gun 12 provides an acceptable quality spray coating on the target object 14. For example, the control system 20 may include an automation system 22, a positioning system 24, a fluid supply controller 26, an air supply controller 28, a computer system 30, and a user interface 32. The control system 20 also may be coupled to a positioning system 34, which facilitates movement of the target object 14 relative to the spray coating gun 12. Accordingly, the spray coating system 10 may provide a computer-controlled mixture of coating fluid, fluid and air flow rates, and spray pattern. Moreover, the positioning system 34 may include a robotic arm controlled by the control system 20, such that the spray coating gun 12 covers the entire surface of the target object 14 in a uniform and efficient manner.
Based on the sensed parameters 108, the illustrated process 100 proceeds to evaluate whether or not the target object 14 is present within the field of view of the spray coating gun 12 (block 110). If the target 14 is not present (e.g., out of the field of view), then the process 100 responds by turning off (or maintaining an off position of) the valves that control fluid flow through the spray coating gun 12 (block 106). If the target 14 is present (e.g., within the field of view), then the process 100 continues by evaluating whether or not the target object 14 is within an acceptable range (e.g., distance) relative to the spray coating gun 12 (block 112). If the range is not acceptable at block 112, then the process 100 responds by turning off (or maintaining an off position of) the valves that control fluid flow through the spray coating gun 12 (block 106). For example, if the target object 14 is at a distance greater than a maximum distance or less than a minimum distance relative to the spray coating gun 12, then the process 100 does not form a spray coating. In some embodiments, the process 100 may respond by setting off an alarm (e.g., audio and/or visual) to alert the user without terminating the spray.
If the range is acceptable at block 112, then the process 100 responds by turning on (or maintaining an on position of) the valves to create a spray downstream from the spray coating gun 12 (block 114). In turn, the process 100 may adjust the valves and various other controllable features of the spray coating gun 12 based on the sensed parameters (block 116). For example, the process 100 may increase the fluid flow and spray density as the distance increases between the spray coating gun 12 and the target object 14. Similarly, the process 100 may decrease the fluid flow and spray density as the distance decreases between the spray coating gun 12 and the target object 14. The process 100 may vary the liquid flow rate of the coating fluid and also features that control the atomization and shaping of the spray downstream from the spray coating gun 12. For example, the process 100 may adjust the air flow rate to an atomization orifice surrounding a central liquid exit, a plurality air shaping orifices, a pneumatically controlled valve, and so forth. In some embodiments, the process 100 may increase the liquid flow rate in response to a greater stroke velocity of the spray coating gun 12 relative to the target object 14, and decrease the liquid flow rate in response to a lesser stroke velocity of the spray coating gun 12 relative to the target object 14.
The process 100 continues to sense the parameters and control the fluid flow as indicated by blocks 104-116 until the gun is disengaged (block 118). If the spray coating gun 12 is not disengaged at block 118, then the process 100 continues in a closed loop by returning to block 104. Otherwise, if the spray coating gun 12 is disengaged at block 118, then the process 100 proceeds to cure/dry the coating applied over the desired surface (block 120). If an additional coating (e.g., same or different coating) is desired by the user at query block 122, then process 100 proceeds through blocks 104-120 to provide another coating of fluid. If the user does not desire an additional coating at query block 122, then process 100 is finished at block 124.
The body 202 of the spray coating gun 12 includes a variety of controls and supply mechanisms for the spray tip assembly 200. As illustrated, the body 202 includes a fluid delivery assembly 226 having a fluid passage 228 extending from a fluid inlet coupling 230 to the fluid delivery tip assembly 204. The fluid delivery assembly 226 also comprises a fluid valve assembly 232 to control fluid flow through the fluid passage 228 and to the fluid delivery tip assembly 204. The illustrated fluid valve assembly 232 has a needle valve 234 extending movably through the body 202 between the fluid delivery tip assembly 204 and a fluid valve adjuster 236. The fluid valve adjuster 236 is rotatably adjustable against a spring 238 disposed between a rear section 240 of the needle valve 234 and an internal portion 242 of the fluid valve adjuster 236. The needle valve 234 is also coupled to a trigger 244, such that the needle valve 234 may be moved inwardly away from the fluid delivery tip assembly 204 as the trigger 244 is rotated counter clockwise about a pivot joint 246. However, any suitable inwardly or outwardly openable valve assembly may be used within the scope of the present technique. The fluid valve assembly 232 also may include a variety of packing and seal assemblies, such as packing assembly 248, disposed between the needle valve 234 and the body 202.
An air supply assembly 250 is also disposed in the body 202 to facilitate atomization at the spray formation assembly 208. The illustrated air supply assembly 250 extends from an air inlet coupling 252 to the air atomization cap 210 via air passages 254 and 256. The air supply assembly 250 also includes a variety of seal assemblies, air valve assemblies, and air valve adjusters to maintain and regulate the air pressure and flow through the spray coating gun 12. For example, the illustrated air supply assembly 250 includes an air valve assembly 258 coupled to the trigger 244, such that rotation of the trigger 244 about the pivot joint 246 opens the air valve assembly 258 to allow air flow from the air passage 254 to the air passage 256. The air supply assembly 250 also includes an air valve adjustor 260 coupled to a needle 262, such that the needle 262 is movable via rotation of the air valve adjustor 260 to regulate the air flow to the air atomization cap 210. As illustrated, the trigger 244 is coupled to both the fluid valve assembly 232 and the air valve assembly 258, such that fluid and air simultaneously flow to the spray tip assembly 200 as the trigger 244 is pulled toward a handle 264 of the body 202. Once engaged, the spray coating gun 12 produces an atomized spray with a desired spray pattern and droplet distribution. As further illustrated, an air conduit 266 is coupled to the air inlet coupling 252 and a fluid conduit 268 is coupled to the fluid inlet coupling 230.
In this particular embodiment, the rate of fluid flow delivered from the fluid delivery assembly 226 may be adjusted based on one or more sensed parameters (e.g., distance, velocity, acceleration, angle, direction, etc.) between the spray coating gun 12 and the target object 14. The parameters between the spray coating gun 12 and the target object 14 may be determined by way of a sensor 280 attached to the spray coating gun 12 directly behind the spray tip assembly 200 and on the body 202 of the spray coating gun 12. The position of the sensor 280 behind the spray tip assembly 200 and on the body 202 of the spray coating gun 12 enables removal of the spray tip assembly 200 without disturbing the placement of the sensor 280. The sensor 280 may be capable of sensing the presence or absence of the target object 14. More specifically, the sensor 280 may be configured to monitor distance, velocity, acceleration, angle, direction, or a combination thereof, between the spray coating gun 12 and the target object 14. The sensor 280 may be of any type including, but not limited to, laser, infrared, photoelectric, optical, fiber optic, electromagnetic or electrostatic, microwave, capacitive, piezoelectric, and ultrasonic sensors.
For example, once the distance between the spray coating gun 12 and the target object 14 is determined, the sensor 280 may communicate this distance to a programmable logic controller (PLC) or other automated input/output arrangement. The logic controller 282 may reside either on the spray coating gun 12 or at a remote location to the spray coating gun 12. The logic controller 282 may determine, based on the distance between the spray coating gun 12 and the target object 14, whether the fluid flow rate delivered from the fluid delivery assembly 226 should be adjusted. For instance, if the distance between the spray coating gun 12 and the target object 14 cannot be determined (e.g., no presence detected), the fluid flow rate delivered from the fluid delivery assembly 226 may be stopped until such time that the distance between the spray coating gun 12 and target object 14 can be determined. In addition, the fluid flow rate delivered from the fluid delivery assembly 226 may be varied based on the distance between the spray coating gun 12 and the target object 14. For instance, if the distance between the spray coating gun 12 and the target object 14 decreases, the fluid flow rate delivered from the fluid delivery assembly 226 may be decreased. Similarly, if the distance between the spray coating gun 12 and the target object 14 increases (e.g., within a suitable range while the target object 14 is within a field of view of the spray coating gun 12), the fluid flow rate delivered from the fluid delivery assembly 226 may be increased. In either case, the automatic flow control may be subject to limits, e.g., upper and lower, in both the flow rates and distances for outputting a spray. In other words, if the spray coating gun 12 is either too close or too distant from the target object 14, then the sensor 280 feedback may trigger an automatic shutoff, an alarm, a delayed shutoff, or another suitable corrective action in response.
The fluid flow rate delivered from the fluid delivery assembly 226 may be varied by communicating with a drive 284 located within the internal portion 242 of the fluid valve adjuster 236. The drive 284 may be actuated to counteract the inward movement of the needle valve 234 away from the fluid delivery tip assembly 204. In addition, it may be desirable to actuate the drive 284 without disturbing the position of the trigger 244. In one embodiment, the needle valve 234 and the drive 284 may be configured such that the drive 284 causes the fluid valve assembly 232 to move toward the fluid delivery tip assembly 204 without moving the needle valve 234. For example, the needle valve 234 may be configured to allow the drive 284 to slide coaxially through the needle valve 234 when the drive 284 is actuated. This could be accomplished using a mechanism within the needle valve 234 which allows an inner portion of the needle valve 234 to separate from an outer portion of the needle valve 234. The outer portion of the needle valve 234 would stay in position while the inner portion of the needle valve 234 moves coaxially with the drive 284. In such an embodiment, the trigger 244 would not experience the force exerted by the drive 284. Therefore, the user would not be aware when the drive 284 overrides the user's depression of the trigger 244. It should be noted that this particular embodiment for actuating the drive 284 and for maintaining the position of the trigger 244 while actuating the drive 284 is merely illustrative and should not be construed as limiting. Other embodiments for carrying out these general objectives may be implemented. It should also be noted that the drive 284 may be an electronic drive, pneumatic drive, hydraulic drive, or any combination thereof.
The body 302 of the spray coating gun 12 includes a variety of controls and supply mechanisms for the spray tip assembly 300. As illustrated, the body 302 includes a fluid delivery assembly 326 having a fluid passage 328 extending from a fluid inlet coupling 330 to the fluid delivery tip assembly 304. The fluid delivery assembly 326 also comprises a fluid valve assembly 332 to control fluid flow through the fluid passage 328 and to the fluid delivery tip assembly 304. The illustrated fluid valve assembly 332 has a needle valve 334 extending movably through the body 302 between the fluid delivery tip assembly 304 and a fluid valve adjuster 336. The fluid valve adjuster 336 is rotatably adjustable against a spring 338 disposed between a rear section 340 of the needle valve 334 and an internal portion 342 of the fluid valve adjuster 336. The needle valve 334 is also coupled to a trigger 344, such that the needle valve 334 may be moved inwardly away from the fluid delivery tip assembly 304 as the trigger 344 is rotated counter clockwise about a pivot joint 346. However, any suitable inwardly or outwardly openable valve assembly may be used within the scope of the present technique. The fluid valve assembly 332 also may include a variety of packing and seal assemblies, such as packing assembly 348, disposed between the needle valve 334 and the body 302.
An air supply assembly 350 is also disposed in the body 302 to facilitate atomization at the spray formation assembly 308. The illustrated air supply assembly 350 extends from an air inlet coupling 352 to the air atomization cap 310 via air passages 354 and 356. The air supply assembly 350 also includes a variety of seal assemblies, air valve assemblies, and air valve adjusters to maintain and regulate the air pressure and flow through the spray coating gun 12. For example, the illustrated air supply assembly 350 includes an air valve assembly 358 coupled to the trigger 344, such that rotation of the trigger 344 about the pivot joint 346 opens the air valve assembly 358 to allow air flow from the air passage 354 to the air passage 356. The air supply assembly 350 also includes an air valve adjustor 360 to regulate the air flow to the air atomization cap 310. As illustrated, the trigger 344 is coupled to both the fluid valve assembly 332 and the air valve assembly 358, such that fluid and air simultaneously flow to the spray tip assembly 300 as the trigger 344 is pulled toward a handle 364 of the body 302. Once engaged, the spray coating gun 12 produces an atomized spray with a desired spray pattern and droplet distribution.
In the illustrated embodiment of
Similar to the embodiment of
For example, once the distance between the spray coating gun 12 and the target object 14 is determined, the sensor 380 may communicate this distance to a programmable logic controller (PLC) or other automated input/output arrangement. The logic controller 382 may reside either on the spray coating gun 12 or at a remote location to the spray coating gun 12. The logic controller 382 may determine, based on the distance between the spray coating gun 12 and the target object 14, whether the fluid flow rate delivered from the fluid delivery assembly 326 should be adjusted. For instance, if the distance between the spray coating gun 12 and the target object 14 cannot be determined (e.g., no presence detected), the fluid flow rate delivered from the fluid delivery assembly 326 may be stopped until such time that the distance between the spray coating gun 12 and target object 14 can be determined. In addition, the fluid flow rate delivered from the fluid delivery assembly 326 may be varied based on the distance between the spray coating gun 12 and the target object 14. For instance, if the distance between the spray coating gun 12 and the target object 14 decreases, the fluid flow rate delivered from the fluid delivery assembly 326 may be decreased. Similarly, if the distance between the spray coating gun 12 and the target object 14 increases (e.g., within a suitable range while the target object 14 is within a field of view of the spray coating gun 12), the fluid flow rate delivered from the fluid delivery assembly 326 may be increased. In either case, the automatic flow control may be subject to limits, e.g., upper and lower, in both the flow rates and distances for outputting a spray. In other words, if the spray coating gun 12 is either too close or too distant from the target object 14, then the sensor 380 feedback may trigger an automatic shutoff, an alarm, a delayed shutoff, or another suitable corrective action in response.
The fluid flow rate delivered from the fluid delivery assembly 326 may be varied by communicating with a drive 384 located within the internal portion 342 of the fluid valve adjuster 336. The drive 384 may be actuated to counteract the inward movement of the needle valve 334 away from the fluid delivery tip assembly 304. In addition, it may be desirable to actuate the drive 384 without disturbing the position of the trigger 344. In one embodiment, the needle valve 334 and the drive 384 may be configured such that the drive 384 causes the fluid valve assembly 332 to move toward the fluid delivery tip assembly 304 without moving the needle valve 334. For example, the needle valve 334 may be configured to allow the drive 384 to slide coaxially through the needle valve 334 when the drive 384 is actuated. This could be accomplished using a mechanism within the needle valve 334 which allows an inner portion of the needle valve 334 to separate from an outer portion of the needle valve 334. The outer portion of the needle valve 334 would stay in position while the inner portion of the needle valve 334 moves coaxially with the drive 384. In such an embodiment, the trigger 344 would not experience the force exerted by the drive 384. Therefore, the user would not be aware when the drive 384 overrides the user's depression of the trigger 344. It should be noted that this particular embodiment for actuating the drive 384 and for maintaining the position of the trigger 344 while actuating the drive 384 is merely illustrative and should not be construed as limiting. Other embodiments for carrying out these general objectives may be implemented. It should also be noted that the drive 384 may be an electronic drive, pneumatic drive, hydraulic drive, or any combination thereof.
In certain embodiments, the sensor 280, drive 284, and associated logic controller 282 of
In some embodiments, one or more sensors may be mounted to the head, body, handle, hoses, or a combination thereof, of the spray gun. For example, these sensors may be mounted via clamps, Velcro, adhesives, epoxy, screws, ties, or a combination thereof. Again, these sensors may be wired sensors, wireless sensors, or a combination thereof. Furthermore, the sensors may be configured to sense position, distance, velocity, acceleration, angle, surface temperature, surface morphology, surface wetness, or a combination thereof, of the target object relative to the spray gun. These sensed parameters may be used by an on-board controller to adjust operation of the spray gun. The on-board controller may include a processor, memory, and code disposed on the processor. The on-board controller alternatively may include a programmable logic controller (PLC) or another suitable controller. Similar to the sensors, the on-board controller may be mounted to the head, body, handle, hoses, or a combination thereof, of the spray gun. For example, the on-board controller may be mounted via clamps, Velcro, adhesives, epoxy, screws, ties, or a combination thereof. The controller, in turn, is configured to control operation of one or more valves (e.g., liquid valve, air valve, or both) to adjust an operational state (e.g., on or off), flow rate, or a combination thereof, of the spray gun. Again, the valves may include a pneumatic valve, a hydraulic valve, a motorized valve, a solenoid type valve, or another suitable feedback controllable valve. In each of the disclosed embodiments, the closed loop control provided by the sensors and controlled valves enables more efficient transfer of a coating fluid onto a target object, thereby reducing waste (e.g., into the air) and improving the quality of the coating applied to the target object.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.