Patent Description:
Some fluid delivery systems, such as Spray Polyurethane Foam (SPF) systems are used for applying foam insulation to residential or commercial structures. These systems deliver two or more materials through hoses from a stationary pumping system (e.g., proportioner system) to a fluid gun or spray foam gun used to apply the material to a structure. The proportioner system may be located at a distance from the actual foam application work area and spray foam gun. It would be useful to improve fluid gun delivery systems.

<CIT> discloses a mixer design for a plural component system, <CIT> discloses a foam dispensing gun, and <CIT> discloses a liquid spray dispenser. <CIT> discloses a multi-component fluid nozzle assembly with detachable nozzle spray tip.

<CIT> discloses an ergonomic handle for a fluid applicator spray gun and <CIT> discloses a spray gun handle support and quick release trigger assembly. <CIT> discloses an ergonomic hand tool holder that supports a tool for use.

Certain aspects commensurate in scope with the claimed invention are summarized below.

In a first aspect, a spray gun includes a mix chamber assembly having at least two bores configured to receive a first fluid and a second fluid, and a chamber fluidly coupled to the at least two bores, the chamber configured to mix the first and the second fluid. The spray gun further includes a handle, and a winged extension disposed to contact at least a portion of an operator's back hand when the operator holds the spray gun via the handle. The spray gun further comprises a strap, wherein the winged extension comprises a first opening configured to receive a first end of the strap, and wherein a second end of the strap attaches to a lower portion of the handle. A fluid delivery system comprising the spray gun is also provided.

In a second aspect, a method of manufacturing a spray gun includes manufacturing a mix chamber assembly having at least two bores configured to receive a first fluid and a second fluid, and a chamber fluidly coupled to the at least two bores, the chamber configured to mix the first and the second fluid. The method further includes manufacturing a handle having a winged extension disposed to contact at least a portion of an operator's back hand when the operator holds the spray gun via the handle. The method additionally includes manufacturing a spray gun body, and manufacturing a spray gun head configured to receive the mix chamber. The winged extension comprises a first and a second opening configured to receive a first end of a strap, and wherein the first end of the strap may be inserted into the first opening or into the second opening.

Embodiments of the present disclosure are directed to systems and methods that may improve fluid delivery in impingement systems, including two-part Spray Polyurethane Foam (SPF) systems. Many Spray Polyurethane Foam (SPF) and similar two-component (<NUM>) dispensing systems deliver two fluid components at high pressure to a spray gun or other dispensing device, where the materials undergo impingement mixing in a chamber or nozzle before being ejected from the gun and onto a substrate to form a foam insulation layer or other coating. Impingement mixing relies on the inertia of two or more streams of reactive fluids to initiate a chemical reaction required for creating the foam or coating on the substrate. The efficiency of the impingement mixing process is dependent on many factors, including the pressure and temperature of the fluid streams, the size of the streams, the geometry of the mixing chamber and orifices, and the relative trajectories of the two impinging streams. If the pressure of the impinging component streams may be significantly different, or are outside of certain processing limits, poor mixing of the reactive fluids may occur. This can lead to poor foam or coating quality, irregular or undesirable deposition patterns on the substrate, and/or build-up of material within the gun or dispensing device. In extreme pressure imbalance conditions, one of the component streams can "cross-over" into the orifice of the opposing stream and result in polymerization and hardening of material within the gun or device itself. This results in partial or complete occlusion of one stream, rendering the system unusable. Cross-over is a common failure mode in <NUM> systems, and a means to detect and prevent this occurrence would reduce or eliminate this problem and result in less down-time.

The temperatures of the impinging fluid streams may also be important parameters for controlling the chemical reaction rate and efficiency. If fluid temperatures are too low, the chemical reaction may be incomplete - or may be too slow for the foam or coating material to adhere properly to the target substrate. If they are too high, the reaction may be too fast, resulting in brittle foam or coatings, high amounts of overspray and atomization, or clogging of the gun/dispensing system.

Most material suppliers of <NUM> systems provide "target" pressures and temperatures of the fluid materials that should produce good output. In certain SPF systems, pressures and temperatures of both fluids at or near the spray gun are not known. Instead, pressure is measured at or near the fluid pumps, and used to control the pressure of the two materials at that location only. These pumps are at a significant distance from the spray gun, which is connected to the pumps via a hydraulic hose. Due to hose geometry, hose length, flow rates, and fluid properties, an unknown pressure drop will occur over the length of the hose. As a result, the actual pressure of the two fluids at or near the spray gun are unknown, uncontrolled, and possibly unequal. In addition, most SPF employ "yoked" piston pumps, driven by a single actuator. The actuator is either an electric motor or a hydraulic or pneumatic piston. Systems that use yoked pumps inherently lack the ability to provide independent pressure control of the two fluids.

In most SPF systems, the temperatures of both fluid streams are measured and controlled with independent heating systems as part of the proportioning (proportioner) system. The proportioner is typically contained in a truck or trailer at the job site, but outside of the structure that is being insulated. In most systems, one fluid stream contains an electronic temperature sensor within the hose and in contact with the fluid material. This temperature sensor is used to control heating elements within the hose structure for both materials, which is required to prevent or reduce cooling of the fluid between the proportioner and the spray gun.

In certain embodiments, the techniques described herein provide for spray gun embodiments that include improved impingement techniques via introduction of fluid into non-tangential channels leading to an impingement chamber. The spray gun embodiments may further include an air capless gun that does not include an air cap mechanism that would be used to shape or to direct the flow of air through the gun, for example, to clean the gun, as further described below. The air capless gun may include less components than an air cap gun, thus providing for ease of maintenance and lowering cost of manufacture. The spray gun may also include "wings" disposed on the gun to conformably fit onto a user's hand. The wings may be suitable for spreading a gun weight over a larger area of the user's hand. Accordingly, the spray gun may be more easily and comfortably operated by the user.

The techniques described herein also provide for control over the pressures between two or more hoses to minimize their difference at/near a gun (e.g., spray gun). The control may derive or otherwise obtain a desired difference between pressure at/near the gun. The desired pressure difference may be zero, may be some other user input value, and/or may be a derived value. The derived value, for example, may be derived via a controller so that the derived value pressure difference may improve, for example, impingement mixing at the gun, and may be provided by modeling in a test bench the mixing at various pressure differences, via simulation (e.g., fluid modeling simulation), and so on.

It may be useful to describe a system that may apply improved control for impingement mixing as described herein. Accordingly and turning now to <FIG>, the figure is a block diagram illustrating an embodiment of a spray application system <NUM> that may include one or more liquid pumps <NUM>, <NUM>. The spray application system <NUM> may be suitable for mixing and dispensing a variety of chemicals, such as a chemicals used in applying spray foam insulation. In the depicted embodiment, chemical compounds A and B may be stored in tanks <NUM> and <NUM>, respectively. The tanks <NUM> and <NUM> may be fluidly coupled to the pumps <NUM> and <NUM> via conduits or hoses <NUM> and <NUM>. It is to be understood that while the depicted embodiment for the spray application system <NUM> shows two compounds used for mixing and spraying, other embodiments may use a single compound or <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or more compounds. The pumps <NUM> and <NUM> may be independently controlled.

During operations of the spray application system <NUM>, the pumps <NUM>, <NUM> may be mechanically powered by motors <NUM>, <NUM>, respectively. In a preferred embodiment, the motors may be electric motors. However, internal combustion engines (e.g., diesel engines), pneumatic motors, or a combination thereof. Motor controllers <NUM> and <NUM> may be used to provide for motor start/stop, loading, and control based on signals transmitted, for example, from the processor <NUM>. The motor <NUM> may be of the same type or of a different type from the motor <NUM>. Likewise, the pump <NUM> may be of the same type or of different type from the pump <NUM>. Indeed, the techniques described herein may be used with multiple pumps <NUM>, <NUM>, and multiple motors <NUM>, <NUM>, which may be of different types.

The pumps <NUM>, <NUM> provide for hydrodynamic forces suitable for moving the compounds A, B into a spray gun system <NUM>. More specifically, compound A may traverse the pump <NUM> through conduit <NUM> and then through a heated conduit <NUM> into the spray gun system <NUM> to be mixed via impingement with compound B. Likewise, compound B may traverse pump <NUM> through conduit <NUM> and then through a heated conduit <NUM> into the spray gun system <NUM> to be mixed via impingement with compound A. To heat the heated conduits <NUM>, <NUM>, a heating system <NUM> may be provided. The heating system <NUM> may provide for thermal energy, such as a heated fluid, suitable for pre-heating the compounds A and B before mixing and spraying and for heating the compounds A and B during mixing and spraying.

The spray gun system <NUM> may include a mixing chamber to mix the compounds A and B. For spray foam insulation applications, the compound A may include isocyanates while the compound B may include polyols, flame retardants, blowing agents, amine or metal catalysts, surfactants, and other chemicals. When mixed, an exothermic chemical reaction occurs and a foam <NUM> is sprayed onto a target. The foam then provides for insulative properties at various thermal resistance (i.e., R-values) based on the chemicals found in the compounds A and B.

Control for the spray application system <NUM> may be provided by a control system <NUM>. The control system <NUM> may include an industrial controller, and thus include a memory <NUM> and a processor <NUM>. The processor <NUM> may include multiple microprocessors, one or more "general-purpose" microprocessors, one or more special-purpose microprocessors, one or more application specific integrated circuits (ASICS), and/or one or more reduced instruction set (RISC) processors, or some combination thereof. The memory <NUM> may include a volatile memory, such as random access memory (RAM), and/or a nonvolatile memory, such as ROM, a hard drive, a memory card, a memory stick (e.g., USB stick) and so on. The memory <NUM> may include computer programs or instructions executable by the processor <NUM> and suitable for controlling the spray application system <NUM>. The memory <NUM> may further include computer programs or instructions executable by the processor <NUM> and suitable for detecting pump <NUM>, <NUM> slip and for providing ratio control actions to continue providing as desired ratio (e.g., <NUM>:<NUM>) for compounds A and B in the presence of slip, as further described below.

The control system <NUM> may be communicatively coupled to one or more sensors <NUM> and operatively coupled to one or more actuators <NUM>. The sensors <NUM> may include pressure sensors, flow sensors, temperature sensors, chemical composition sensors, speed (e.g., rotary speed, linear speed) sensors, electric measurement sensors (e.g., voltage, amperage, resistance, capacitance, inductance), level (e.g., fluid level) sensors, limit switches, and so on. The actuators <NUM> may include valves, actuatable switches (e.g., solenoids), positioners, heating elements, and so on.

A user or users may interface with the control system <NUM> via an input/output (I/O) system <NUM>, which may include touchscreens, displays, keyboards, mice, augmented reality/virtual reality systems, as well as tablets, smartphones, notebooks, and so on. A user may input desired pressures, flow rates, temperatures, ratio between compound A and compound B (e.g., <NUM>:<NUM>), alarm thresholds (e.g., threshold fluid levels of compound A, B in tanks <NUM>, <NUM>), and so on. The user may then spray via the spray gun system <NUM> and the control system <NUM> may use the processor <NUM> to execute one or more programs stored in the memory <NUM> suitable for sensing system <NUM> conditions via the sensors <NUM> and for adjusting various parameters of the system <NUM> via the actuators <NUM> based on the user inputs. The I/O system <NUM> may then display several of the sensed conditions as well as the adjusted parameters. Certain components of the spray application system <NUM> may be included in or interface with a proportioning system <NUM>. The proportioning system <NUM> may "proportion" or deliver the compounds A, B at a specified ratio (e.g., <NUM>:<NUM>) to achieve the spray <NUM>. In this manner, the user(s) may mix and spray chemicals, such as compounds A and B, to provide for certain coatings, such as insulative spray foam.

As mentioned earlier, the pumps <NUM>, <NUM> may be independently controlled. The system <NUM> improves control by having:.

To improve on the current systems, system <NUM> may use pressure and temperature sensing at or near the spray gun, and the use of these sensing signals to control independent pump actuators and heating systems. In turn, this level of independent control, based on pressure, flows, and/or temperature at or near the spray gun, results in improved control of impingement mixing within the spray gun.

In our approach, independent pressure sensors located at or near the spray gun (in the hoses <NUM>, <NUM>, in the outlet of the pumps <NUM>, <NUM>) may transmit pressure signals to the proportioner <NUM>, where they are used in the pump actuator control system (e.g. control system <NUM>) to achieve the desired output at the spray gun <NUM>. The control system <NUM> can be configured to achieve independent pressure control in the two materials at or near the gun, or to minimize or to eliminate the pressure differences between the two materials at or near the gun. In addition, the pressure control algorithm can be configured to provide better equalization and control of impingement momentums of the two streams at or near the gun. Momentum equalization control can be important if/when there are known differences between the two fluids or orifice geometries that affect impingement stream momentums (e.g. fluid density of the two materials, orifice size of the two sides within the gun, etc.). An example of momentum equalization control would be to minimize the differences between "pseudo momentum" parameters MA and MB at a desired PA or PB (A or B fluid pressure) <MAT> <MAT>.

Independent pressure sensors <NUM> located in the vicinity of the spray gun that communicate signals from the vicinity of the spray gun to a Proportioning unit located outside of the spray area. The Proportioning unit controls a pump or pumps in a manner to minimize the pressure differences between the independent pressure sensors <NUM> located in the vicinity of the spray gun. These pressure sensors <NUM> can be within the gun, attached to portions of hoses, hose couplings or fittings for the two hoses, or within a fluid manifold structure near the gun that has independent inlet and outlet fluid passages for the two materials, and or pump <NUM>, <NUM> outlets.

Independent pressure sensors <NUM> located in the vicinity of the spray gun that communicate signals from the vicinity of the spray gun to a proportioning unit located outside of the spray area. The proportioning system <NUM> controls a pump or pumps in a manner to minimize the momentum differences between the two impinging streams of fluid within the gun mix chamber by controlling pressures of the two streams to calculated levels that include other known fluid and geometric parameters that differ between the two fluid streams. The pressure sensors <NUM> can be within the gun, attached to hose couplings or fittings for the two hoses, or within a fluid manifold structure near the gun that has independent inlet and outlet fluid passages for the two materials.

Independent temperature sensors <NUM> located in the vicinity of the spray gun that communicate signals from the vicinity of the spray gun to a proportioning unit located outside of the spray area. The Proportioning system <NUM> controls the temperature of the fluids independently to achieve desired temperatures at the spay gun. These temperature sensors <NUM> can be within the gun, attached to hose couplings or fittings for the two hoses (as well as in or around hoses), or within a fluid manifold structure near the gun that has independent inlet and outlet fluid passages for the two materials. Sensors on or near the gun and on or near fluid conduits (e.g., sensors <NUM>, <NUM>), such as fluid conduits <NUM>, <NUM>, may communicate with the control system <NUM> via wired means. For example, the conduits <NUM><NUM> may transmit electrical signals and/or electrical power in addition to working as fluid conduits. For example, the conduits <NUM>, <NUM> may be smart hoses that include conductive elements embedded in the hoses. It is to be understood that the sensors, e.g., sensors <NUM>, <NUM> may also communicate via wireless means (e.g., Wi-Fi, Bluetooth, mesh networks, and so on).

Turning to <FIG>, the figure illustrates a process <NUM> that may be used to implement certain of the techniques described herein. The process <NUM> may be implemented as computer code or instructions executable via, for example, the processor <NUM>. It is to be noted that the blocks of the process <NUM> may be executed in any order or concurrently (e.g., in parallel with each other). In the depicted example, the process <NUM> may first sense or control pressures. For example, pressure sensors <NUM> located at or near the spray gun, in the hoses (or hose fittings) <NUM>, <NUM>, in the outlet of the pumps <NUM>, <NUM>, may transmit pressure signals to the processor <NUM>. The processor <NUM> may then independently control pressure of the A and B compound (and/or any other two or more fluids) to minimize or to eliminate the pressure differences between the two (or more) materials at or near the gun <NUM>, as described above, e.g., by adjusting pump rates, temperatures, flows, and so on, to arrive at equal pressures between A and B compounds.

The process <NUM> may also measure and/or control temperature (block <NUM>). For example, temperature sensors <NUM> may be used to derive temperatures at or near the gun, at or near hoses, at our near pumps (e.g., pump outlets). The temperatures may then be used, for example via ideal gas law so that pressure x volume = n (moles) x R (gas constant) x Temperature (in Kelvins). Again, independent control of temperatures of the hoses, of the tanks (e.g., compound A and/or compound B tanks), and/or gun temperatures may be used to provide for equal pressure of fluids entering the gun. It is also to be noted that flow rates may be sensed, along with temperatures and/or pressures, to result in equal pressures of fluid being delivered to the gun <NUM>.

Turning to <FIG>, the figure is a side perspective view of an embodiment of the spray gun system <NUM>. In the depicted embodiment, spray gun system <NUM> may include a gun body <NUM> and a gun handle <NUM>. In certain embodiments, a winged extension member <NUM> may be disposed between the gun body <NUM> and the gun handle <NUM>. The winged extension member <NUM> may be used, for example, to improve weight distribution of the spray gun system <NUM> when being held by a user. That is, the winged extension member <NUM> may conformably fit on a top surface of a thumb, top surface of an index finger, top surface of webbing between the thumb and index finger, and top surface of a portion of the back of the user's hand, and thus increase a contact area between the spray gun system <NUM> and the user's hand. It is to be noted that the winged extension member <NUM> may be a component of the gun handle <NUM>, the gun body <NUM>, or a combination thereof. Likewise, the winged extension member <NUM> may be an independent component. The winged extension member <NUM> may also be provided in various sizes, e.g., small, medium, large, extra-large, to more conformably fit a variety of hand sizes. The winged extension member <NUM> may be sized so as to completely cover the user's hand when viewed from above, or to only partially cover the user's hand. The winged extension member <NUM> may have a side-to-side dimension (e.g., distance between a left edge of the winged extension member <NUM> and a right edge) of between <NUM> and <NUM>, equivalently between <NUM>-<NUM> inches.

The spray gun system <NUM> may also include a strap <NUM> which may aid in maintaining a firmer contact between he spray gun system <NUM> as well as in adding further surface area for carrying the spray gun <NUM>. The strap <NUM> may be manufactured of a variety of materials, including fabrics (e.g., nylon), leather, plastics, rubber, or a combination thereof. The strap <NUM> may attach to the winged extension member <NUM> via openings <NUM>, <NUM> and to a bottom portion of the spray gun system <NUM> via an attachment member <NUM>. The strap <NUM> may be repositioned for right hand or right hand use, for example, by attaching the strap to right opening <NUM> or to left opening <NUM>. The strap <NUM> may also be removable so that the spray gun system <NUM> may be used without the strap <NUM>. As shown, the spray gun system <NUM> enable ambidextrous use. That is, the spray gun system <NUM> may be held by either of the right hand or the left hand.

In use, the operator would mechanically couple the hoses <NUM>, <NUM> with the spray gun system <NUM>, for example, by using hose couples, such as quick detach hose couplers, such as a left coupler <NUM>. When the hoses <NUM> and <NUM> are attached to the spray gun <NUM>, the operator may then exert finger pressure on a trigger <NUM>, which in turn may enable the flow of fluid A from tank <NUM> and B from tank <NUM> into the spray gun system <NUM>. The fluids A and B may then be mixed in an impingement chamber, as further described below, and the mixed fluid may then be sprayed onto a desired target area.

<FIG> is a rear perspective view illustrating an embodiment of the spray gun system <NUM>. In the depicted embodiment, the winged extension member <NUM> is shown as including curved bottom portions <NUM>. The curved bottom portions <NUM> may ergonomically enhance comfort and conformability of the winged extension member <NUM> to the thumb, index finger, and back hand portions when the spray gun system <NUM> is held by the user. Other ergonomic features may include palm swells <NUM>, and/or the use of the strap <NUM>. Also shown is the left coupler <NUM> and a right coupler <NUM> used to connect (e.g., quick connect) hoses <NUM> and <NUM>.

<FIG> is a front perspective view showing an embodiment of the spray gun system <NUM>. In the depicted embodiment, the left coupler <NUM> and the right coupler <NUM> are shown disposed over the winged extension member <NUM>. Accordingly, hoses <NUM> and <NUM> may be carried above the user's hand, enhancing comfort during spray operations. The operator may position the strap <NUM> for a specific hand, e.g., left hand or right hand. The user may additionally adjust the strap <NUM> to fit his or her specific hand size, including adjustment for use when wearing gloves.

The operator may attach hoses <NUM> and <NUM> to the spray gun system <NUM> via the hose couplers m and <NUM>. The user may then carry the spray gun system <NUM> to a desired area for use, and apply pressure (e.g., finger pressure) onto the trigger <NUM>. The trigger <NUM> may then result in compound A and compound B being injected into a mix chamber of the spray gun system <NUM>, which may then mix compound A and B and the mixed fluid may then exit the spray gun system <NUM> via a mix tip <NUM>. In certain embodiments, compound A and compound B may be controlled to enter at the same pressure. That is, a pressure for compound A may be equal to a pressure for compound B when compounds A and B are entering the spray gun system <NUM> via the hose couplers <NUM> and <NUM>. The pressure of compound A and B being equal at the spray gun system <NUM>, for example equal pressures at a mixing chamber of the spray gun system <NUM> may result in improved mixing and delivery of, for example, foam insulation via the spray gun system <NUM>.

<FIG> is a schematic side view of a front portion of an embodiment of the spray gun system <NUM> showing a mix chamber assembly <NUM> when the trigger <NUM> is in a "resting" position. In the depicted embodiment, the spray gun <NUM> does not include an air cap. That is, air caps are used in other spray guns to direct the flow of air, either for aiding in mixing fluid and/or for providing fluid flow that cleans (e.g., ancillary clean-off air) certain portions of the spray gun. The spray gun system <NUM> embodiment shown in <FIG> does not include an air cap. Instead, the mixing chamber assembly <NUM> receives two fluids via the hose couplers <NUM> and <NUM> during activation of the trigger <NUM>, the mixing chamber assembly <NUM> then mixes the fluids, and expels the now mixed fluid through the mix tip <NUM>. More specifically, the mixing chamber assembly <NUM> may include two lateral bores, such as a bore <NUM>, leading into a chamber <NUM>. Fluid may enter through the two bores to be mixed in the chamber <NUM>.

Any clean-off air also flows into the mixing chamber assembly <NUM> and exits out through the mix tip <NUM>. Also shown is a mix tip retainer member <NUM> used to retain the mix tip <NUM> on a font portion of the spray gun system <NUM>. A mix tip retainer guide assembly <NUM> is also shown, which is used to position the mix tip retainer member <NUM> at the front portion of the spray gun system <NUM>. An O-ring or seal <NUM> may prevent unwanted fluid escaping through an interface between the mix tip retainer member <NUM> and the mix tip retainer guide assembly <NUM>.

<FIG> shows the mixing chamber assembly <NUM> when the trigger <NUM> is pressed. More specifically, <FIG> is a schematic side view of a front portion of an embodiment of the spray gun system <NUM> showing the mix chamber assembly <NUM> in a "spray" position. In the depicted embodiment, the trigger <NUM> has been pressed to cause a movement rearward of the mix chamber assembly <NUM> and interconnected mix tip retainer member <NUM> and mix tip <NUM>. The mix tip retainer guide assembly <NUM> remains in place. As the mix chamber assembly <NUM> moves rearward away from the mix tip retainer guide assembly <NUM>, two fluids enter into the mix chamber assembly <NUM> via the hose couplers <NUM> and <NUM>. The fluids may then mix in the mix chamber assembly <NUM> via bores such as the bore <NUM> to be mixed in the chamber <NUM> and then to be subsequently sprayed outwardly from the mix tip <NUM>. In some embodiments, a Zerk or grease fitting <NUM> may be used to insert a grease or other compound into the mix chamber assembly <NUM>, for example, for temporary storage of the spray gun system <NUM>. The grease may subsequently be expelled by adding air into the mix chamber assembly <NUM>, and spray operations may then resume.

<FIG> is a front view showing an embodiment of the mix chamber assembly <NUM> showing two lateral bores <NUM>, <NUM> leading into the chamber <NUM>. In the depicted embodiment, both of the lateral bores <NUM>, <NUM>, enter the chamber <NUM> inside of and away from tangent. That is, the lateral bores <NUM> and <NUM> enter the chamber <NUM> inside of tangent lines <NUM> and <NUM> respectively. Fluid, such as compounds A and B, may enter through the lateral bores <NUM>, <NUM>, and then mix inside of the chamber <NUM>. As mentioned earlier, pressures of fluid entering the lateral bores <NUM> and <NUM> may be equal. That is, if compound A enters via lateral bore <NUM> and compound B enters via lateral bore <NUM>, pressures at lateral bores <NUM> and <NUM> may be the same. The fluids may then exit the chamber along the X-axis into the mix tip <NUM> and out of the spray gun <NUM> into a desired spray area.

<FIG> is a perspective view depicting an embodiment of a threaded mix chamber assembly <NUM> and a mix tip <NUM>. In the depicted embodiment, the threaded mix chamber assembly <NUM> and a mix tip <NUM> may not use a mix tip retainer member <NUM>, thus providing for a simpler design with less component parts. Further, replacing the mix tip <NUM> may be more efficiently performed by unscrewing the mix tip <NUM>, for example by using a wrench via a head portion <NUM> of mix tip <NUM> to remove the mix tip <NUM>. Various mix tips <NUM> may be provided, for example, having different sizes for an opening <NUM>. The opening <NUM> may be suitable for spraying various types of compound mixes and/or spray patterns.

The mix tip <NUM> may be inserted via an opening (e.g., grooved opening) <NUM> of the threaded mix chamber assembly <NUM>. Threaded portions <NUM> may then engage grooves in the threaded mix chamber assembly <NUM> to secure the mix tip <NUM> in place. As the trigger <NUM> is depressed, fluid may enter via bores, such a bore <NUM>, to be mixed in a chamber of the threaded mix chamber assembly <NUM>. Fluid may then exit the chamber into the mix tip <NUM> to be sprayed outwardly from the opening <NUM>.

Claim 1:
A spray gun (<NUM>), comprising:
a mix chamber assembly (<NUM>, <NUM>) having at least two bores (<NUM>, <NUM>) configured to receive a first fluid and a second fluid, and a chamber (<NUM>) fluidly coupled to the at least two bores (<NUM>, <NUM>), the chamber (<NUM>) configured to mix the first and the second fluid;
a handle (<NUM>); and
a winged extension (<NUM>) disposed to contact at least a portion of an operator's back hand when the operator holds the spray gun via the handle (<NUM>),
characterized in that the spray gun (<NUM>) comprises a strap (<NUM>), wherein the winged extension (<NUM>) comprises a first opening (<NUM>) configured to receive a first end of the strap (<NUM>), and wherein a second end of the strap (<NUM>) attaches to a lower portion of the handle (<NUM>).