Patent Application
20200269262
The present disclosure is directed to compressed air driven devices and more particularly to compressed air driven devices having air exhaust control systems.
Compressed air driven devices are important components in many assembly processes. For example, certain materials utilized in various work processes can contribute to increased explosion risks in some work environments. Similarly, the use of some materials and operating conditions can require modification of one or both of these parameters to mitigate explosion risks. A non-limiting example of this type of situation occurs in paint spraying operations as well as in other mixing and chemical operations. Such operations can produce flammable fumes and/or other suspended flammable material that creates hazards. In response to such hazards, industry has seen an increase in the use of compressed air to drive devices such as rotary disk sprayers in order to atomize paint for application.
However, the total performance of the respective compressed air driven device as well as the life span of such devices can be compromised do to the cooling effects that result from the expansion of the compressed air used to drive such compressed air devices. This can range from condensation of moisture from the surrounding environment to icing severe enough to stop operation of the compressed air device. To address this, in-line heaters are often used to heat the compressed air above the associated dew point.
Due to heater design constraints, in-line heaters are generally placed too far from the device to adequately compensate for the refrigeration effect. This can be due, at least in part, to the fact that the compressed air readily gives up its heat in the path between the inline heater and the application device. This is especially true when the pneumatic device is in an intrinsically safe area and the heater must be placed external to this area for safety reasons.
Robots, and the devices mounted on them, are expensive and must be protected, yet be accessible for service when required. The most common method employed to prevent the contamination of robots and the devices mounted on them from contamination such as paint overspray is to provide a flexible cover of either fabric or plastic. Such covers can do double duty, not only protecting the robot and devices from paint overspray and the like, but also preventing the leakage of air, oil, water, paint, solvent, and the like, from the robot into the paint environment which could negatively impact finish quality.
In certain coating application devices, compressed air is used both to atomize the coating material to be applied and to deliver the coating material to the target substrate. Coating application devices having devices such as bells and guns use compressed air for atomization of the coating material to be applied. The coating application devices also use compressed air as the shaping air that controls the dispensing pattern of the atomized coating material. Ambient air present during paint application operations typically has a relatively high humidity. When the compressed air delivered to the application device falls below the dew point of the ambient air in the booth, the resulting condensation is introduced directly into the paint application process, creating significant quality issues. While covers can assist in addressing the condensation and humidity issues, they cannot eliminate the problem entirely.
Various devices have been proposed that seek to control heat exchange temperature by regulating water temperature delivered to heat exchangers associated with the robot or other device. However, to date, no devices have been proposed that can provide a direct regulation of the actual temperature of the compressed air being employed. While regulation of the temperature of the robot or other device through indirect regulation may eliminate condensation issues under certain circumstances, it is difficult to adequately regulate the temperature of the compressed air itself and to adequately eliminate condensation issues.
Thus, it would be desirable to provide a method, system and coating application device that can regulate temperatures in a coating application environment in a manner that address and eliminates at least a portion of the condensation phenomena. It is also desirable to provide a device that can control and/or regulate the temperature of compressed air employed in applicator devices.
Disclosed is an apparatus for driving a device that includes a compressed air source and a device operable with air supplied from the compressed air source via a compressed air supply line. The device can also include at least one compressed air exhaust port; at least one sensor providing sensor output in communication with the compressed air supply line. The at least one sensor can be located proximate to the exhaust port. The apparatus also includes a heated fluid source for providing a heated fluid proximate to the at least one device operable by the delivered compressed air via a heated fluid supply line as well as a heat exchanger connected to the compressed air supply line and the heated fluid supply line and an electronic controller. The electronic controller is operable on the heat exchanger upon receipt of at least one output form the at least one sensor. The apparatus can also include a process fluid source and a process fluid supply line in communication with the process fluid source. The apparatus can also include at least one process fluid sensor that is in communication with the process fluid supply source and can be located in the process fluid supply line. The at least one at least one sensor provides a process fluid sensor output. The apparatus can conclude a process fluid temperature controller that can receive the process fluid sensor output, the process fluid temperature and provide output to the electronic controller such that the device operable with air supplied from the compressed air source includes at least one outlet in fluid communication with the process fluid supply line, at least one compressed gas outlet driving at least one movable component of the device and at least one compressed gas outlet.
The various features, advantages and other uses of the present apparatus will become more apparent by referring to the following detailed description and drawing in which:
Disclosed herein is control system, apparatus and method that can be employed with one or more various compressed air driven devices to control and/or condition the temperature of the compressed air that is employed in the operation and/or application of material such as paint and the like. Where desired or required, the compressed air temperature control system and method as disclosed herein can be employed with a coating applicator system. The present disclosure is also directed to a compressor air driven applicator device employing an embodiment of the controls system and device as disclosed herein.
It has been found, quite unexpectedly, that regulation of the temperature of compressed air delivered to a compressed air applicator device can provide improvements in the quality of the applied coating material. It has also been found that the method and device as disclosed herein, when employed in systems that include compressed air driven coating material applicators surrounded, at least in part by a protective coat or jacket can provide a climate-controlled robot arm apparatus.
A non-limiting example of a heat-controlled applicator device and system that relies on control of water temperature to the heat exchanger is U.S. Pat. No. 7,322,188 to Cline, the specification of which is incorporated by reference herein in its entirety. Such as system addresses and eliminates certain condensation issues by overheating the compressed air. In such systems, exhaust air is trapped under the protective cover surrounding the applicator. This creates an increase in temperature of the localized ambient air and in the temperature of the shaping air that can influence the temperature of the coating material to be applied. This can result in fluctuations in the viscosity of the coating material. However, if the temperature of the compressed air is not regulated, the environment under the cover as well as the shaping air could be significantly colder than the desired temperature for optimum coating material application.
Various compressor air driven applicator devices can be employed in the method and device as disclosed herein. Non-limiting examples of suitable compressor driven air devices include coating applicator devices such as paint spray devices. The compressor air driven applicator device that can be employed with the controls system and device as disclosed herein can have various configurations, non-limiting examples of which are depicted in
In the non-limiting example depicted in
In the non-limiting exemplary example illustrated in
It is contemplated that multiple systems as disclosed herein can be employed in applications where multiple compressor air driven applicator systems 11, 11′ are positioned in locations such as a paint spray booth or the like. A non-limiting example of such an application is illustrated in
In the system 10 as disclosed herein, it is contemplated that compressed air that is employed in the coating device such as a compressed air drive applicator device can originate from any suitable source. The system 10 can be connected to the compressed air source by any suitable mechanism and can be conveyed to at least one heat exchanger located downstream of the compressed air source to condition the compressed air passing therethrough.
An illustrative embodiment of the system 10 disclosed herein is schematically depicted in
The heat exchange unit 14 employed in the system 10 can be a device in which one or more lines carrying a thermal transfer fluid are in intimate thermal contact with one or more lines carrying compressed air. In various embodiments, it is contemplated that the thermal transfer fluid can be water or suitable organic materials. In various embodiments, it is contemplated that the thermal transfer fluid will be water or the like. As used herein the term “heat exchange unit” should be broadly construed. Various means for heating the compressed air supply could be used without departing from the scope of the present disclosure. It is also considered with in the purview of this disclosure that one or more heat exchange units 14 can be employed. Multiple heat exchange units can be positioned in series or in parallel relative to the compressed air supply line(s). Where desired or required, the at least one suitable heat exchange unit 14 can be mounted on the robotic arm unit 16 of an associated air driven applicator device 11.
The conditioned compressed air stream that is routed to the applicator 11 can serves multiple function. The conditioned compressed air can function to atomize the coating material to be applied in order to produce an atomized coating material stream such as atomized coating material stream 22 schematically depicted in
The system 10 as disclosed herein can be employed with various applicator assemblies that are used in the applicator 20. One non-limiting example of an applicator assembly suitable for use with the system and device disclosed is a rotary atomizer also referred to as a paint bell or a bell applicator. Without being bound to any theory, the bell applicator generally includes major assemblies such as a valve module, a bell cup, a turbine, and a shaping air shroud or ring. In certain rotary bell assemblies, the valve module can include passages for paint, solvent and compressed air as well as valves to control the flow of each of the items into the system for paint delivery as well as for purging and cleaning as desired or required and for management of compressed air to valves, the turbine and to the shaping air shroud.
In certain applicators, the bell cup can be configured as a conical disc that is fixed to the associated robot arm and communicates with the shaft of the turbine. Paint or coating material can be injected into the central rear of the disc to form a thin film at the bottom of the disc. Centrifugal force exerted due to disc rotation can pull the paint towards the edges of the cup where it breaks into atomized droplets.
The turbine can be configured as a high-speed air motor that rotates the bell cup at speeds at suitable to atomize the accumulated paint particles. Rotational speed can vary depending upon parameters including, but not limited to, the physical properties of the paint or coating material, the cup diameter, the degree of atomization desired and the like. In certain applications, rotational speeds between 10,000 rpm and 70,000 rpm may be employed.
The shaping air shroud or shaping air ring that produces shaping air stream 24 can be configured as a ring with a plurality of small passages such as pin holes positioned to permit outward air flow out the front of the atomizer at a location outside the bell cup diameter in order to control the size of the spray pattern produced. In general, as more air is pushed through the shaping air shroud, the atomized paint will be shaped into a smaller pattern.
In addition to the air associated with the atomized paint or coating material and the shaping air stream 24, a portion of the conditioned air also powers the turbine of the applicator. After powering the turbine, this portion of the conditioned air exits as exhaust gas. The exhaust air produced by the turbine exits from the turbine at a suitable exhaust port such as at muffler 26. In certain embodiments of system 10 as disclosed herein, the exhaust port such as muffler 26 can be located within the interior area defined by cover C. It is to be understood that the system 10 can include one or more exhaust paths and that the system 10 can include one or more other exhaust path(s) instead of or in addition to the muffler 26. The exhaust gas such as that produced by the turbine or other suitable applicator mechanism can be conveyed to the suitable exhaust port by means of one or more conduits such as conduit 28.
The system 10 as disclosed herein can also include includes at least one feedback sensor 30 that can be positioned proximate to the one or more conditioned compressed air exhaust path(s) such as muffler 26. The at least one feedback sensor 30 can be configured to monitor one or more parameters associated with the exhaust gas and convey data regarding the parameters monitored. In certain embodiments, at least one feedback sensor can be positioned so as to monitor temperature conditions within cover C. As depicted in
The data developed from the at least one feedback sensor 30 can be conveyed to a suitable controller such as an electronic controller 32 by any suitable means. In certain embodiments, the system 10 as disclosed herein can also include suitable relays and wiring 32 to communicate data and outputs generated by the at least one feedback sensor 30 to a suitable electronic controller 34. The electronic controller 34 that is employed in the system 10 receive the data generated from the at least one feedback sensor 30. The electronic controller 34 can also include suitable command logic to exert over mechanisms in order to control of the temperature of compressed air circulating in the system 10.
In embodiments of the system such as that depicted in
The coating material to be applied can be a suitable fluid material that is supplied from a suitable supply source. In certain embodiments, it is contemplated that the coating material to be applied will have passed through a suitable temperature control system heat exchanger 40 prior to entry into material supply tubing 36. The at least one coating material temperature sensor 38 may one be of any common industrial type including, but not limited to, RTD, thermocouple, thermistor, IR detector, etc. The at least one temperature sensor 38 is in electronic communication with a suitable coating material temperature controller 42 by any suitable means including but not limited to hard wiring 44, Bluetooth and the like.
It is contemplated that the at least one coating material temperature sensor 38 can be associated with the coating material path in the material supply tubing 36 or in a thermal conditioning fluid path that may be associated with the thermal control system 40. Where the system includes more than one coating material temperature sensor, it is contemplated that coating material temperature sensors can be positioned in contact with the coating material path, the thermal conditioning fluid path or both. The measured coating material temperature value can be communicated to the coating material temperature controller 42 either continuously or at desired intervals.
In the system 10 as disclosed, coating material temperature data communicated to the coating temperature controller 42 can be evaluated against a coating set point programmed into the coating material temperature controller 42. This coating material set point, together with the measured coating material temperature data can be communicated to the air temperature controller 34 via a communications link 46. Non-limiting examples o a suitable communication link can include various communications platforms such as 4-20 mA, 1-5 VDC, 010 VDC, etc., or digital like RS-485, Ethernet, DeviceNet, CAN Bus, etc.
The system 10 as disclosed herein also includes a thermal transfer fluid loop that communicates between the heat exchanger 14 and the electronic controller 34 to regulate and control the temperature of the compressor air passing through the system 10. As depicted in
The thermal transfer fluid loop can also include at least one thermal transfer fluid circulating pump 58. In the embodiment depicted din
The coating material temperature setpoint can be programmed into the coating temperature controller 42 by any suitable means. This setpoint can communicated to the electronic controller 34 of the air temperature control system via any common communication platform as at reference numeral 46. This set point is adopted by the electronic controller 34 as the air temperature setpoint and as the setpoint of the thermal transfer fluid circulated by pump 58 through heat exchanger 14. This value is manipulated to bring the exhaust temperature, as measured by the feedback sensor 30 to the coating material setpoint temperature. In this manner, exhaust air exiting muffler 26 and shaping air 24. This assures that the exhaust air exiting muffler 26 and shaping air 24 are held at the same temperature as the coating material delivered to the applicator via conduit 36 and applied to the part (not shown).
Without being bound to any theory, it is believed that controlling and coordinating the temperature of the coating material, shaping air, robot arm environment and delivery system components to provide a consistent temperature independent of changes in ambient temperature resulting from variations from day-to-night and season-to-season, the viscosity of the coating will be consistent and repeatable and the quality of the finish can be maintained.
In order to further appreciate the system and device as disclosed herein, temperature readings associated with application of a representative clear coat material using a typical applicator system such as that illustrated schematically in
In line heater output is recorded as 105° F. Trace 1 shows the clearcoat temperature entering the paint spray booth and Trace 2 shows the clearcoat temperature as it enters the bell associated with the applicator unit. The ambient temperature value of the booth is recorded in Trace 3 is the booth ambient temperature value. Clearcoat temperature as it enters the booth is recorded as increasing toward 80° F. at time stamp 7:15 A. This is a full 25° F. below the in-line heater output of 105° F., and a good demonstration of why inline heaters located outside the booth are ineffective.
The clearcoat material that is delivered to the bell illustrated in Trace 2 tracked the incoming temperature with an offset of about 2.5° F. This would normally be attributed to the influence of booth ambient temperature on the coating material as it travels along the arm of the robot to the point of application.
When painting was stopped for a break at about 7:20 A, the paint was left sitting stationary in the system, the clearcoat material at the booth wall (Trace 1) temperature experiences temperature loss, nearly reaching booth ambient (Trace 3) by the end of the break B1. The clearcoat material at the bell inlet (Trace 2) however, continued to lose temperature, falling a full 2° F. below the booth ambient temperature (Trace 3) by the end of the break B1. This “sub-cooling” phenomena cannot be the result of booth ambient air. Therefore, it must originate from another source having a temperature below the temperature listed above. One such colder source is found in the exhaust air that is shown in the graph of
If it is known at all, it is generally misinterpreted as booth ambient influence (Trace 3). When the lines were purged to restart painting at about 7:50 A, R1, the temperature of the clearcoat material into the booth (Trace 1) and the temperature of the clearcoat material at the bell inlet (Trace 2) come together and after which the bell inlet temperature (Trace 2) stays between the clearcoat inlet (Trace 1) and booth ambient (Trace 3) temperature over the next two hours of runtime. Considering that the clearcoat is flowing through Teflon tubing, which provides some level of insulation, and also factoring in the short dwell time in that tubing during continuous paint cycles, it is clear that the temperature differential (ΔT) between the clearcoat inlet temperature (Trace 1) and the booth ambient temperature (Trace 3) is insufficient to produce this drop in temperature.
From the perspective of process control and finish quality repeatability, the influence of this refrigerated air is not consistent. As shown in
These variations were virtually invisible to the line operators and process engineers responsible for maintaining consistent process outcomes, which can make it very hard to identify them as the source of finish quality issues. This is especially true in this example depicted in
In contrast, if the paint system is equipped with a temperature control system that is overheating, then the environment under the cover, and the shaping air, will be warmer than desired, and the opposite of the effect shown in
Without being bound to any theory, it is believed that the system and device as disclosed herein provides for a coating material application device that measures the exhaust air temperature and controls the air inlet temperature to match the exhaust air to the coating temperature setpoint in which the controls function as a slave to the coating temperature control system to assure that coating temperature, shaping air, and the contained environment under the robot cover are all controlled at the same temperature independent of changes in ambient related to morning-to-night and season-to-season variations.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.
The present application is a U.S. Non-Provisional Utility Application claiming priority to U.S. Provisional Application 62/810,596 filed Feb. 26, 2019, the specification of which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62810596 | Feb 2019 | US |
