Dose piston and solvent dosing for spray applicators

Abstract

The spray applicator is operable between a spray state and a purge state. In the spray state, the applicator discharges a multi-component material formed in a mixing chamber for spray application. In the purge state, the spray applicator discharges compressed air from the mixing chamber as purge air. A control piston controls operation of the spray device between the spray state and the purge state. The dose piston is configured to dose a predetermined volume of solvent into the purge air flow for delivery to the mixing chamber. The dose piston moves within the control piston and in an opposite axial direction from the control piston.

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Application No. 63 / 422,505, filed November 4, 2022, and entitled "Dose Piston and Solvent Dosage for Spray Applicator," the disclosure of which is incorporated herein by reference in its entirety. FIELD OF THE DISCLOSURE The present disclosure relates generally to fluid atomizers. More particularly, the present disclosure relates to multiple component spray applicators. [Background technology]

[0002] Multi-component sprayers are configured to produce and apply coatings, such as spray foam insulation and elastomeric coatings, to substrates. Spray foam insulation is applied to substrates to provide thermal insulation from the environment. Elastomeric coatings can be applied to substrates to protect the surface; an example is a spray-in truck bed liner. For multi-component spraying, two or more base components are mixed within the spray applicator, causing a chemical reaction that forms the multi-component material from the base component material. Multi-component sprayers can emit purge air through the mixing area and spray orifice to remove the fast-setting multi-component material from the sprayer and prevent clogging. Summary of the Invention [Means for solving the problem]

[0003] According to one aspect of the present disclosure, a spraying device includes a sprayer body, a mixing chamber supported by the sprayer body, a purge air passageway extending to an inlet port of the mixing chamber to supply purge air to the mixing chamber, a control piston at least partially disposed within the sprayer body, and a dose piston at least partially disposed within the sprayer body. The control piston is axially actuable between a first control position associated with a purge mode and a second control position associated with a spray mode. In the purge mode, the control piston fluidly disconnects the component flow paths from the mixing chamber. In the spray mode, the control piston fluidly connects the component flow paths to the mixing chamber. The dose piston is actuable between a first dose position associated with releasing purge air from the mixing chamber and a second dose position associated with releasing a multi-component material from the mixing chamber. The dose piston is configured to supply solvent to the purge air passageway when in the second dose position. The dose piston is fluidly connected to the solvent passageway when in the reset position. The control piston shifts along the axis in a first axial direction from a first control position to a second control position. The control piston shifts along a second axial direction opposite the first axial direction from the second control position to the first control position. The dose piston shifts along the first axial direction from the second dose position to the first dose position. And the dose piston shifts along the second axial direction from the first dose position to the second dose position.

[0004] According to another aspect of the present disclosure, a spray device includes a control piston operably connected to a spray valve for actuating the spray device between a spray state and a purge state, and a dose piston carried by the control piston and operable between a first dose position and a second dose position. Spray material is emitted from the spray orifice when the spray device is in the spray state. Purge air is emitted from the spray orifice when the spray device is in the purge state. The dose piston is configured to pick up a predetermined volume of solvent at the second dose position, and the dose piston is configured to dispense the predetermined volume of solvent into the purge air at the first dose position. When the spray device transitions between the spray state and the purge state, the dose piston moves along the actuation axis in a direction opposite to that of the spray piston.

[0005] According to yet another aspect of the present disclosure, a method of spraying includes placing a spray applicator in a spray mode, discharging a multi-component material formed in a mixing chamber by the spray applicator, actuating a control piston in a first axial direction along an actuation axis, and actuating a dose piston in a second axial direction along the actuation axis. In placing the spray applicator in the spray mode, the spray applicator is in the spray mode and the first and second material passages are fluidly connected to the mixing chamber. In discharging the multi-component material, the multi-component material is formed by a first base component material supplied to the mixing chamber through the first material passage and a second base component material supplied to the mixing chamber through the second material passage. Actuating the control piston in the first axial direction along the actuation axis fluidly disconnects the first and second material passages from the mixing chamber and fluidly connects the purge air passage to the mixing chamber, placing the spray applicator in a purge mode. Actuating the dose piston along the actuation axis in a second axial direction causes the dose of solvent picked up from a location within the control piston to be entrained in a purge air stream flowing axially through the dose piston and the control piston, the second axial direction being opposite to the first axial direction.

[0006] According to yet another aspect of the present disclosure, a dose piston for dispensing solvent into a purge air passageway of a multiple-component sprayer includes a dose piston head, a dose piston shaft extending axially from the dose piston head, and a purge air hole formed in the dose piston head and the dose piston shaft and configured to direct purge air from a purge hole inlet formed in the dose piston head to a purge hole outlet formed in the dose piston shaft, the purge hole outlet being formed in a radially outer surface of the dose piston shaft. [Brief explanation of the drawings]

[0007] [Figure 1A] 1 is a simplified block diagram of a spray system. [Figure 1B] 1B is a schematic block diagram of the spray system of FIG. 1A showing the flow path through the spray applicator. [Figure 2A] Isometric view of a spray applicator. [Figure 2B] Exploded isometric view of a spray applicator. [Figure 3A] FIG. 2 is an enlarged partial cross-sectional view of the spray applicator showing the spray applicator in a purged state. [Figure 3B] FIG. 3B is an enlarged partial cross-sectional view of the spray applicator shown in FIG. 3A, showing the spray applicator in a spraying state. [Figure 4A] 4 is a partial enlarged cross-sectional view of the spray applicator taken along line 4-4 of FIG. 2A, showing the spray application in a purged state. [Figure 4B] 4B is an enlarged partial cross-sectional view of the spray applicator shown in FIG. 4A illustrating the spray application in a first transition state. [Figure 4C] FIG. 4B is a partial enlarged cross-sectional view of the spray applicator shown in FIG. 4A, showing the spray application in a spray state. [Figure 5A] 5 is a partial enlarged cross-sectional view of the spray applicator taken along line 5-5 of FIG. 2A, showing the spray application in a spray state. [Figure 5B]5B is a partial enlarged cross-sectional view of the spray applicator shown in FIG. 5A illustrating the spray application in a second transitional state. [Figure 5C] FIG. 5B is a partial enlarged cross-sectional view of the spray applicator shown in FIG. 5A, showing the spray application in a purged state. [Figure 6] FIG. 4 is an enlarged isometric cross-sectional view taken along line 4-4 of FIG. 2A. [Figure 7] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present disclosure relates to a spray applicator for applying a multi-component material to a substrate. The spray applicator includes a mixing chamber configured to receive separate fluids of different first and second component materials that, when mixed together, form the multi-component material. The spray applicator discharges the combined multi-component material from the mixing chamber during a spray mode and discharges purge air from the mixing chamber during a purge mode. First and second purge air flows are supplied to the mixing chamber to purge material residue from the mixing chamber. A solvent is injected into the purge air flow upstream of the mixing chamber and carried to the mixing chamber by the purge air. The solvent assists in removing residue from the multi-component material and away from the mixing chamber. A dose piston controls the dispensing of the solvent into the purge air flow. The dose piston is held by a drive piston that controls movement of a valve member, which controls spraying by the atomizer. The dose piston is decoupled from the drive piston so that the dose piston can move relative to the drive piston.

[0009] FIG. 1A is a schematic block diagram of a spray system 10. FIG. 1B is a schematic block diagram of the spray system 10 showing the flow path through a spray applicator 12. FIGS. 1A and 1B are described together. The spray system 10 includes a spray applicator 12, material supplies 14a and 14b, pumps 16a and 16b, and an air supply 18. The spray applicator 12 includes a body 20, a trigger 22, a spray control assembly 24, a control valve 26, a solvent reservoir 27, a mixing chamber 30, and a spray orifice 32. As shown in FIG. 1B, the spray applicator 12 further includes material passages 34a, 34b, a solvent passage 36, and an air passage 38. The air passage 38 includes a common passage 40, a first passage 42, and a second passage 44.

[0010] The spray system 10 is a system configured to generate a material spray and apply the material spray to a substrate. In some embodiments, the spray system 10 is configured to combine two or more base component materials to generate a multi-component material for application to a substrate. In some embodiments, the spray system 10 is configured to generate spray foam insulation or elastomeric coatings on a substrate, among other spray options.

[0011] Material supplies 14a, 14b store a supply of base component materials prior to spraying. Multi-component materials, such as spray foam or elastomeric coatings, are formed by mixing the base component materials in mixing chamber 30. While spray foam insulation is described herein by way of example, it is understood that the present disclosure is not limited to spray foam applications. For example, fluid supply 14a can store a first base component material, such as a resin, and fluid supply 14b can store a second base component material, such as a catalyst. In some embodiments, a first of the base component materials can be a polyol resin and a second of the base component materials can be an isocyanate. The first and second base component materials are combined in spray applicator 12 (e.g., in mixing chamber 30) and ejected from spray applicator 12 as a spray of multi-component material. Spray applicator 12 generates a spray of multi-component material and applies the multi-component material to a substrate. The spray applicator 12 may alternatively be referred to as a mixer, a mixing manifold, a dispenser, and / or a spray gun, among other options.

[0012] Pump 16a is configured to draw a first base component material from fluid source 14a and move the first base component material downstream to spray applicator 12. Pump 16b is configured to draw a second base component material from fluid source 14b and move the second base component material downstream to spray applicator 12. Pumps 16a, 16b can be controlled by a system controller (not shown). The first base component material flows through material passage 34a in spray applicator 12. The second base component material flows through material passage 34b in spray applicator 12. The first base component material is fluidly separated from the second base component material at a location upstream of mixing chamber 30.

[0013] Air supply 18 is connected to spray applicator 12 and is configured to supply a flow of compressed air to spray applicator 12. Air supply 18 may be any suitable configuration for supplying compressed air to spray applicator 12. For example, air supply 18 may be a compressor, a pressurized tank, or any other configuration suitable for providing a flow of pressurized air. Air supply 18 supplies pressurized air to an air passage through spray applicator 12, which air passage is defined at least in part by air passage 38 through spray applicator 12.

[0014] Pressurized air is initially supplied to the common passageway 40. The first passageway 42 and the second passageway 44 are configured to provide individual streams of pressurized purge air to the mixing chamber 30. The first passageway 42 is configured to supply a first portion of the pressurized purge air to the mixing chamber 30 through the same port in the mixing chamber 30 to which the ingredient passageway 34a provides the first base component material. The second passageway 44 is configured to supply a second portion of the pressurized purge air to the mixing chamber 30 through the same port in the mixing chamber 30 to which the ingredient passageway 34b provides the second base component material. The purge air flows through the mixing chamber 30, picking up the material therein and blowing it out of the mixing chamber 30. The purge air thereby prevents undesired hardening of the material therein.

[0015] The spray applicator 12 is configured to generate and apply a spray of a multi-component material. A body 20 of the spray applicator 12 supports the other components of the spray applicator 12. A control assembly 24 is at least partially disposed within the spray applicator 12. The control assembly 24 is configured to control whether the first and second base component materials flow into the mixing chamber 30 or whether the first and second purge airs flow into the mixing chamber 30. The control assembly 24 allows the first and second component materials to flow into the mixing chamber 30 when the spray applicator 12 is in a spray mode. The control assembly 24 allows the purge air to flow into the mixing chamber 30 when the spray applicator 12 is in a purge mode.

[0016] Control valve 26 is at least partially disposed within spray applicator 12. Control valve 26 is operatively connected to control assembly 24 and operates control assembly 24 between a spray mode and a purge mode, as described in more detail below. Control valve 26 is configured to move pressurized air to control actuation of a piston in control assembly 24, as described in more detail below.

[0017] The mixing chamber 30 is disposed at the downstream end of the material passages 34a, 34b, the first passage 42, and the second passage 44. A spray orifice 32 is formed within the mixing chamber 30. When the spray applicator 12 is in a spray mode, the mixing chamber 30 receives first and second base-component materials from the material passages 34a, 34b. The base materials interact within the bores of the mixing chamber 30 to form a multi-component material within the mixing chamber 30, and a spray of the multi-component material is emitted through the spray orifice 32. When the spray applicator 12 is in a purge mode, the mixing chamber 30 receives first and second purge air flows and emits purge air through the spray orifice 32. The purge air is configured to remove residue from within the mixing chamber 30, prevent the multi-component material from hardening within the mixing chamber 30, and prevent clogging of the spray orifice 32.

[0018] The trigger 22 is attached to the spray applicator 12 and is configured to control spraying by the spray applicator 12. The trigger 22 is configured to be actuated to transition the spray applicator 12 between a spray mode, in which a multi-component material is formed and discharged, and a purge mode, in which purge air is discharged. A user can actuate the trigger 22 to shift the spray valve 24 to the spray state, thereby fluidly connecting the material passages 34a, 34b with the mixing chamber 30 and fluidly isolating the first passage 42 and second passage 44 from the mixing chamber 30. The base component materials are combined in the mixing chamber 30 to form the multi-component material that is discharged from the spray orifice 32.

[0019] The user releases trigger 22 to shift spray valve 24 to the purge state, thereby fluidly isolating material passageways 34a, 34b from mixing chamber 30 and fluidly connecting first passageway 42 and second passageway 44 to mixing chamber 30. A purge air portion flows through first passageway 42 and second passageway 44 into mixing chamber 30 and is discharged through spray orifice 32. It is understood that trigger 22 can be of any configuration suitable for activating and terminating spraying by spray applicator 12. While spray applicator 12 is described as a manual spray gun configured to be held and operated by a user, it is understood that other embodiments of spray applicator 12 can be automatic, such that spray applicator 12 does not include a manually operated trigger 22 or handle.

[0020] The solvent reservoir 27 stores a supply of solvent that is intermittently supplied to the mixing chamber 30 during operation. The solvent assists in cleaning the mixing chamber 30 when the spray applicator 12 is in a purge mode. For example, the solvent can slow a reaction process, inhibiting curing, and dissolve uncured multi-component materials. The solvent reservoir 27 can be located within the spray applicator 12, such as within the handle of the spray applicator 12. The solvent reservoir 27 contains the solvent. In some embodiments, the solvent reservoir 27 can be formed as a cartridge that can be removed and replaced as a single unit. The solvent passage 36 extends downstream from the solvent reservoir 27 to the air passage 38. In the illustrated embodiment, the solvent passage 36 extends to the second passage 44. The solvent passage 36 can be considered to extend to the mixing chamber 30 such that a portion of the second passage 44 defines both the air passage 38 and the solvent passage 36.

[0021] In some embodiments, the spray applicator 12 is configured to supply solvent to the mixing chamber 30 via the second passageway 44 but not via the first passageway 42. Supplying the solvent only via the second passageway 44 prevents the solvent from mixing with the base component material supplied via the material passageway 34a at a location upstream of the mixing chamber 30. For example, material passageway 34b can be configured to supply a resin-based component material to the mixing chamber 30, while material passageway 34a can be configured to supply an isocyanate-based component material. Isocyanates are moisture-sensitive and can harden when exposed to liquids, such as solvents. The hardened isocyanates form crystals that can damage or scratch the soft seals and clog the passages that pass through the spray applicator 12. Flowing the solvent into the mixing chamber 30 through the same port as the resin inhibits mixing of the solvent and isocyanate within the spray applicator 12 at a location upstream of the mixing chamber 30. However, it is understood that not all embodiments are limited to supplying the solvent via a single air passageway. For example, some embodiments of the spray applicator 12 may include a solvent passage 36 that intersects with the air passage 38 at a location upstream of the intersection between the first passage 42 and the second passage 44 such that the solvent is conveyed through both the first passage 42 and the second passage 44.

[0022] During operation, a user actuates trigger 22 to transition spray applicator 12 between spray mode and purge mode. Trigger 22 is operatively associated with control valve 26 to activate control valve 26, thereby causing spraying by spray applicator 12. In some embodiments, control valve 26 directs compressed air from air source 18 to control assembly 24 to drive control assembly 24 between a position associated with spray mode and a position associated with purge mode. For example, control valve 26 can direct compressed air through a first internal passage within spray applicator 12 to displace control piston 84 of control assembly 24, displacing control piston 84 from a respective first position associated with spray mode to a respective second position associated with purge mode. Control valve 26 can then be shifted, such as by a user releasing trigger 22, to direct compressed air through a second internal passage within spray applicator 12 to displace control piston 84 and dose piston 86 of control assembly 24 from their respective second positions to their respective first positions.

[0023] The spray applicator 12 is initially in a purge mode such that the first passageway 42 and the second passageway 44 are fluidly connected to the mixing chamber 30 and the spray applicator 12 emits purge air through the spray orifice 32. A user actuates the trigger 22 to transition the spray valve assembly 24 to a first position associated with the spray mode. With the spray valve assembly 24 in the first position, the material passageways 34a, 34b are fluidly connected to the mixing chamber 30, while the first passageway 42 and the second passageway 44 are fluidly isolated from the mixing chamber 30. The first and second base-component materials flow into the mixing chamber 30 and mix within the mixing chamber 30 to form a multi-component material. The multi-component material is then emitted through the spray orifice 32.

[0024] The spray valve 24 remains in the spray state until the user releases the trigger 22. When the trigger 22 is released, the control valve 26 shifts to direct pressurized air to the spray valve assembly 24, shifting the spray valve assembly 24 to a second position associated with the purge mode. With the spray valve assembly 24 in the second position, the material passages 34a, 34b are fluidly isolated from the mixing chamber 30, and the air passage 38 is fluidly connected to the mixing chamber 30. More specifically, the first passage 42 and the second passage 44 are each fluidly connected to the mixing chamber 30. Pressurized air flows from both the first passage 42 and the second passage 44 into the mixing chamber 30 and is discharged through the spray orifice 32. A portion of the second purge air carries solvent from the solvent reservoir 27 into the mixing chamber 30. The solvent dissolves any multi-component material in the mixing chamber 30 to prevent hardening and clogging. In some embodiments, the solvent is supplied only through the second passageway 44, preventing contact between the solvent and the first base component material supplied through the material passageway 34a at a location upstream of the mixing chamber 30.

[0025] Figure 2A is an isometric view of the spray applicator 12. Figure 2B is an exploded isometric view of the spray applicator 12. Figures 2A and 2B are described together. The spray applicator 12 includes a body 20, a trigger 22, a spray valve 24, a solvent cartridge 28, a mixing chamber 30, a spray orifice 32, a cover 48, a material manifold 50, and an air receiver 52. The body 20 includes a support housing 54, a fluid cartridge 56, a retaining cap 58, and a handle 60. Shuttles 62a, 62b of the control assembly 24 are shown. The material manifold 50 includes a base component inlet 64a and a base component inlet 64b.

[0026] The body 20 supports the other components of the spray applicator 12. The body 20 can be formed as a unitary component or as multiple components secured together. In the illustrated embodiment, a support housing 54 supports and at least partially encloses the spray valve 24 and control valve 26 components. A fluid cartridge 56 is removably attachable to the support housing 54. A handle 60 extends from the support housing 54. A user can grasp the handle 60 to operate and orient the spray applicator 12. The handle 60 can, in some embodiments, accommodate other components of the spray applicator 12, such as the solvent cartridge 28. An exhaust port can be formed through the handle 60 for venting air from the spray valve 24. A trigger 22 can be supported by and connected to the body 20. More specifically, the trigger 22 is connected to the support housing 54 in the illustrated embodiment. The trigger 22 is configured to control spraying by the spray applicator 12.

[0027] The control assembly 24 is supported by the spray applicator 12. In the illustrated embodiment, the control assembly 24 is at least partially disposed within the support housing 54. The control assembly 24 includes shuttles 62a, 62b that protrude from the support housing 54 into the fluid cartridge 56. In the illustrated embodiment, the shuttles 62a, 62b form the fluid control components of the spray applicator 12. The shuttles 62a, 62b are configured to shift axially relative to a spray axis SA to transition the spray applicator 12 between a spray mode and a purge mode. The spray axis SA may be coaxial with the actuation axis AA (FIGS. 4A-5C).

[0028] A fluid cartridge 56 is mountable to the support housing 54. The fluid cartridge 56 can be connected to the support housing 54 in any desired manner. For example, the fluid cartridge 56 can be connected to the support housing 54 by interface threads, among other options.

[0029] A cover 48 extends at least partially around the fluid cartridge 56. In the illustrated embodiment, the cover 48 covers the interface between the fluid cartridge 56 and the support housing 54. The cover 48 can be connected to at least one of the support housing 54 and the fluid cartridge 56. A retaining cap 58 is attached to the fluid cartridge 56. The retaining cap 58 is configured to secure the internal components within the spray applicator 12, such as by securing the mixing chamber 30 within the cavity 68. However, it will be understood that the mixing chamber 30 can be secured to the body 20 in any suitable manner.

[0030] Material manifold 50 is attachable to spray applicator 12 and configured to supply first and second base component materials to fluid cartridge 56. Material manifold 50 is attached to support housing 54 by fasteners 69, although it will be understood that other connection types are possible. Base component inlet 64a is a connection piece configured to connect to a hose or other fluid line to receive the first base component material from a first material source (e.g., fluid supply 14a (FIGS. 1A and 1B)). Base component inlet 64b is a connection piece configured to connect to a hose or other fluid line to receive the second base component material from a second material source (e.g., fluid supply 14b (FIGS. 1A and 1B)).

[0031] An air receiver 52 is attached to the spray applicator 12 and provides a location for compressed air to enter the spray applicator 12. In the illustrated embodiment, the air receiver 52 is attached to the rear end of a support housing 54, and the fluid cartridge 56 is attached to the front end of the support housing 54. The air receiver 52 is a connection piece configured to connect to a hose, pipe, tube, or other air line to receive pressurized air from an air source, such as air supply 18 (FIGS. 1A and 1B).

[0032] A solvent cartridge 28 is mountable to the spray applicator 12. In the illustrated embodiment, the solvent cartridge 28 forms the solvent reservoir 27 of the spray applicator 12. In the illustrated embodiment, the solvent cartridge 28 is configured to be mounted within the handle 60.

[0033] During operation, a first base component material is supplied to the spray applicator 12 at the base component inlet 64a, a second base component material is supplied to the spray applicator 12 at the base component inlet 64b, and compressed air is supplied to the spray applicator 12 at the air receiver 52. The spray valve 24 controls the flow of the base component materials and compressed purge air into the mixing chamber 30. The trigger 22 controls the actuation of the control assembly 24 to place the spray applicator 12 in a spray state and a purge state. With the control assembly 24 in a first position associated with the spray mode, the first and second base component materials flow into and mix in the mixing chamber 30, and the resulting multi-component material is discharged through the spray orifice 32. When the spray applicator 12 is in the spray state, the shuttles 62a, 62b prevent the purge air from entering the interior of the mixing chamber 30. With the control assembly 24 in a second position associated with the purge mode, the purge air portion flows into and mixes with the interior of the mixing chamber 30, and the resulting combination of air and solvent is expelled through the spray orifice 32. When the spray applicator 12 is in the purge mode, the shuttles 62a, 62b prevent the first and second base component materials from flowing into the interior of the mixing chamber 30.

[0034] Figure 3A is a partially enlarged cross-sectional view of the spray applicator 12 in a purging state. Figure 3B is a partially enlarged cross-sectional view of the spray applicator 12 shown in Figure 3A in a spraying state. Figures 3A and 3B are described together. The body 20, mixing chamber 30, spray orifice 32, cover 48, and seal cartridges 66a, 66b of the spray applicator 12 are shown. The support housing 54, fluid cartridge 56, and retaining cap 58 of the body 20 are shown. The shuttles 62a, 62b of the control assembly 24 are shown. The mixing chamber 30 includes the spray orifice 32, inlet ports 68a, 68b, and a mixing hole 70.

[0035] The spray applicator 12 is configured to receive separate flows of first and second base component materials BCMa, BCMb and to emit a multiple component material PCM formed by mixing the first and second base component materials in the mixing chamber 30. The body 20 supports the other components of the spray applicator 12.

[0036] Shuttles 62a, 62b are operatively connected to control piston 84 (FIGS. 3A-5) of control assembly 24, which is moved by control piston 84. Control piston 84 and shuttles 62a, 62b are considered to form control assembly 24. In some embodiments, shuttles 62a, 62b are normally in the position shown in FIG. 3A such that spray applicator 12 is in purge mode and releases purge air. When shuttles 62a, 62b are shifted along first axial direction AD1 to the position shown in FIG. 3B, they place spray applicator 12 in spray mode. When shuttles 62a, 62b are shifted along second axial direction AD2 to the position shown in FIG. 3A, they return spray applicator 12 to purge mode.

[0037] The seal cartridges 66a, 66b are disposed within the fluid holes 72a, 72b, respectively. The fluid holes 72a, 72b are formed within the fluid cartridge 56. The heads 74a, 74b of the shuttles 62a, 62b, in conjunction with the seal cartridges 66a, 66b, respectively, control the flow of base component material and purge air into the mixing chamber 30. The mixing chamber 30 is disposed within the cavity 68. The inlet ports 68a, 68b extend through the mixing chamber 30 to a mixing hole 70. The mixing hole 70 may be disposed coaxially with the spray axis SA. The mixing hole 70 extends to the spray orifice 32.

[0038] In operation, the spray applicator 12 is placed in a spray mode to generate and expel the multiple-component material PCM from the spray orifice 32. The spray applicator 12 is then placed in a purge mode to expel compressed air CA as purge air from the spray orifice 32. To place the spray applicator 12 in the spray mode, a user presses the trigger 22, which causes the control valve 26 to direct drive air to a chamber within which the head of the control piston 84 is located. The drive air exerts a force on the control piston 84 to displace the movable part of the control assembly 24 in a first axial direction AD1 to the position shown in FIG. 3B.

[0039] When the shuttles 62a, 62b are in a position associated with the spray state shown in FIG. 3B , the heads 74a, 74b of the shuttles 62a, 62b are disposed on first axial sides of the inlet ports 68a, 68b and seal against the seal cartridges 66a, 66b. For example, the heads 74a, 74b may be in direct contact with the bodies of the seal cartridges 66a, 66b or with seal members (e.g., elastomeric seal members such as O-rings) supported by the seal cartridges 66a, 66b or supported by the heads 74a, 74b. The interfaces between the heads 74a, 74b and the seal cartridges 66a, 66b fluidly separate the first and second purge air streams from the mixing chamber 30, while the first and second base component material streams are fluidly connected to the mixing chamber 30. In some embodiments, the second purge air portion is formed by a portion of the drive air that displaces the control piston 84, as described in more detail below. When the spray applicator 12 is in the purge mode, a portion of the second purge air is prevented from flowing downstream from the chamber within which the head of the control piston 84 is located. Thus, although the head 74b of the shuttle 62b is positioned to block the flow of purge air, with the spray applicator 12 in the spray mode, no purge air may be present in the portion of the second passageway 44 adjacent the head 74b.

[0040] The first base component material flows through seal cartridge 66a and enters mixing chamber 30 through inlet port 68a. The second base component material flows through seal cartridge 66b and enters mixing chamber 30 through inlet port 68b. The first and second base component materials interact within mixing hole 70 to form a multi-component material that is discharged through spray orifice 32.

[0041] When the trigger is released (e.g., the user releases trigger 22), spray applicator 12 transitions from spray mode to purge mode, as shown in FIG. 3A. Control valve 26 changes position to direct drive air into the chamber so that the head of control piston 84 is positioned opposite the head of control piston 84 from the air that moves control piston 84 into spray mode. The drive air exerts a force on control piston 84, displacing the moving part of control assembly 24 along second axial direction AD2, placing spray applicator 12 in purge mode.

[0042] When the shuttles 62a, 62b are in the position shown in FIG. 3A, the heads 74a, 74b are positioned on a second axial side of the inlet ports 68a, 68b opposite the first axial side and seal against the seal cartridges 66a, 66b. For example, the heads 74a, 74b can be in direct contact with the body of the seal cartridges 66a, 66b or with a seal member (e.g., an elastomeric seal member such as an O-ring) supported by the seal cartridges 66a, 66b or supported by the heads 74a, 74b. The interface between the heads 74a, 74b and the seal cartridges 66a, 66b fluidly connects the first and second purge air streams with the mixing chamber 30, while the flows of the first and second base component materials BCMa, BCMb are fluidly isolated from the mixing chamber 30. The first purge air portion flows through the seal cartridge 66a and enters the mixing chamber 30 through the inlet port 68a. The second pneumatic purge portion, containing entrained solvent SV, flows through seal cartridge 66b and enters mixing chamber 30 through inlet port 68b. The first and second pneumatic purge portions interact within mixing hole 70 and are discharged through spray orifice 32.

[0043] Both the first base component material and the first purge air portion flow through a common portion of seal cartridge 66a and through inlet port 68a. Thus, seal cartridge 66a and inlet port 68a define portions of both material passage 34a (FIG. 1B) and first passage 42 (FIG. 1B). Both the second base component material and the second purge air portion flow through a common portion of seal cartridge 66b and inlet port 68b. Thus, seal cartridge 66b and inlet port 68b define portions of both material passage 34b (FIG. 1B) and second passage 44 (FIG. 1B).

[0044] In the illustrated embodiment, the solvent is carried into the mixing chamber 30 by the second purge air portion. The first purge air portion is fluidly separated from the solvent at a location upstream of the mixing chamber 30. In the illustrated embodiment, the first and second purge air portions are supplied from the same source of compressed air upstream of the spray applicator 12 (e.g., from the air supply 18) and from the same supply passageway within the spray applicator 12 (e.g., common passageway 40 (FIG. 1B)). Air pressure is balanced across the first and second purge air portions to prevent the first purge air portion from flowing across inlet port 68b and to prevent the second purge air portion from flowing across inlet port 68a. The balanced pressure prevents the solvent carried by the second purge air portion from flowing into or upstream from inlet port 68a, such as into the seal cartridge 66a or other portions of the material passageway 34a or first passageway 42.

[0045] FIG. 4A is a partial enlarged cross-sectional view of spray applicator 12 taken along line 4-4 in FIG. 2A, showing spray applicator 12 in a purging state. FIG. 4B is a partial enlarged cross-sectional view of spray applicator 12 shown in FIG. 4A, showing spray applicator 12 in a first transition state. FIG. 4C is a partial enlarged cross-sectional view of spray applicator 12 shown in FIG. 4A, showing spray applicator 12 in a spraying state. FIG. 5A is a partial enlarged cross-sectional view of spray applicator 12 taken along line 5-5 in FIG. 2A, showing spray applicator 12 in a spraying state. FIG. 5B is a partial enlarged cross-sectional view of spray applicator 12 shown in FIG. 5A, showing spray applicator 12 in a second transition state. FIG. 5C is a partial enlarged cross-sectional view of spray applicator 12 shown in FIG. 5A, showing spray applicator 12 in a purging state. FIGS. 4A through 5C will be described together.

[0046] Shown are the body 20, control piston 84, dose piston 86 and spray lock 88 of the spray applicator 12. Shown are the support housing 54 of the body 20, piston bore 82 and feed groove 90. Shown is the second passage 44 of the air passage 38.

[0047] Shown are the control piston head 92, control piston shaft 94, and shaft seals 96a, 96b of the control piston 84. The control piston head 92 includes axial side 98a, axial side 98b, a dose head chamber 100, and displacement passages 102a, 102b. The control piston shaft 94 includes a shaft bore 104, a solvent groove 106, a solvent passage 108, a retention groove 110, and a dosing groove 112. Shown are the dose piston head 114, dose piston shaft 116, purge air bore 118, head seal 120, and dosing seals 122a-122c of the dose piston 86. The dose piston shaft 116 includes a transfer groove 124.

[0048] The control piston 84 and the dose piston 86 are coaxially disposed on an actuation axis AA. The control piston 84 is configured to reciprocate between a first control position associated with the release of purge air and a second control position associated with the release of the multi-component material. The dose piston 86 is configured to reciprocate between a first dose position associated with the dose of solvent into the purge air and a second dose position associated with picking up solvent from the solvent passage 36. The dose piston 86 moves relative to the control piston 84 between the first and second dose positions. The control piston 84 is shown in the first control position in FIGS. 4A, 4B, and 5C. The control piston 84 is shown in the second control position in FIGS. 4C, 5A, and 5B. The dose piston 86 is shown in the first dose position in FIGS. 4A, 5B, and 5C. The dose piston 86 is shown in the second dose position in FIGS. 4B, 4C, and 5A.

[0049] The control piston 84 is configured to control spraying by the spray applicator 12. The control piston 84 can form part of the sprayer control assembly 24. The shuttles 62a, 62b are actuated by the control piston 84 to move between a first position associated with the purge mode (first position shown in FIG. 3A) and a second position associated with the spray mode (second position shown in FIG. 3B). The control piston 84 is connected to the shuttles 62a, 62b (best seen in FIGS. 3A and 3B) and axially displaces the shuttles 62a, 62b to actuate the spray applicator 12 between the spray mode and the purge mode. In some embodiments, the control piston 84 is directly connected to the shuttles 62a, 62b. The body 20 at least partially defines the drive chamber 76. The body 20 defines various flow passages that form the air passage 38 of the spray applicator 12. The body 20 defines various flow passages of the solvent passage 36 of the spray applicator 12.

[0050] The drive chamber 76 is at least partially formed within the body 20. Inlet passages 78a, 78b are formed within the body 20. The inlet passages 78a, 78b introduce compressed air into the drive chamber 76. The inlet passages 78a, 78b are disposed on opposite axial sides of the control piston head 92. The inlet passage 78a is associated with a first sub-chamber 80a of the drive chamber 76 that is partially defined by an axial side 98a of the control piston 84. The inlet passage 78b is associated with a second sub-chamber 80b of the drive chamber 76 that is partially defined by an axial side 98b of the control piston 84. The control piston 84 is movable with the body 20 within the drive chamber 76 such that the body 20 is aligned with the control piston 84 for movement along the actuation axis AA. The piston bore 82 is formed within the body 20. The control piston 84 is at least partially disposed within the piston bore 82. A control piston 84 may be associated with the body 20 within the piston bore 82 such that the piston bore 82 is aligned with the control piston 84 for movement along the actuation axis AA.

[0051] The control piston head 92 is disposed within the drive chamber 76. The control piston head 92 divides the drive chamber 76 into a sub-chamber 80a and a separate sub-chamber 80b. The sub-chambers 80a, 80b are fluidly separated from one another by the control piston head 92. The drive chamber 76 defines an axial displacement range for the control piston 84. The drive chamber 76 defines the axial distance that the control piston 84 can move relative to the body 20. The control piston 84 can move within an axial range R1. The control piston 84 can move a length L1 between a spray state and a purge state.

[0052] The axial side 98a of the control piston head 92 faces the second axial direction AD2, and the axial side 98b of the control piston head 92 faces the first axial direction AD1. The axial side 98a is exposed to the subchamber 80a and at least partially defines the subchamber 80a. The axial side 98b is exposed to the subchamber 80b and at least partially defines the subchamber 80b. The axial side 98a and the axial side 98b are exposed to the compressed air in the subchambers 80a and 80b, respectively. As a result, the compressed air acts on the axial side 98a or the axial side 98b to drive the displacement of the control piston 84. The compressed air supplied to the subchamber 80a acts on the axial side 98a to displace the control piston 84 in the first axial direction AD1. The compressed air supplied to the subchamber 80b acts on the axial side 98b to displace the control piston 84 in the second axial direction AD2.

[0053] A dose head chamber 100 is formed within the control piston head 92. A dose piston head 114 is disposed within and retained within the dose head chamber 100. The dose head chamber 100 defines an axial displacement range for the dose piston 86. The dose head chamber 100 defines the axial distance that the dose piston 86 can move relative to the control piston 84. The dose piston 86 can move within an axial range R2. The dose piston 86 can move a length L2 between a spray state and a purge state.

[0054] Displacement passages 102a, 102b are formed through the control piston head 92 and extend to the dose head chamber 100. The displacement passages 102a, 102b are flow paths configured to supply compressed air to the dose head chamber 100. The compressed air supplied to the dose head chamber 100 is configured to actuate the dose piston 86 along an actuation axis AA.

[0055] The displacement passage 102a includes an inlet through the axial side 98a of the control piston head 92 and an outlet to the dose head chamber 100. The displacement passage 102a is fluidly connected to the subchamber 80a and the dose head chamber 100. The displacement passage 102a is configured to receive air at a first axial side of the dose piston head 114 and output air into the dose head chamber 100 at a second axial side of the dose piston head 114. The displacement passage 102a extends axially around the dose head seal 120 to introduce compressed air into the dose head chamber 100 opposite the dose head seal 120, from which the displacement passage 102a receives air. Compressed air supplied through the displacement passage 102a to the dose head chamber 100 is configured to displace the dose piston 86 in the second axial direction AD2. The displacement passage 102a provides a flow path through the control piston head 92. The control piston head 92 directs compressed air to the dose head chamber 100 on the axial side of the dose piston head 114 oriented in the first axial direction AD1. The displacement passage 102a is configured to introduce compressed air into the dose head chamber 100 to drive the dose piston 86 along the second axial direction AD2 from the first dose position to the second dose position. The displacement passage 102a includes an inlet oriented axially along the second axial direction AD2 in the illustrated embodiment and an outlet oriented radially into the dose head chamber 100. The displacement passage 102a redirects the flow direction of the compressed air to output the compressed air radially into the dose head chamber 100.

[0056] The displacement passage 102b includes an inlet through the axial side 98b of the control piston head 92 and an outlet into the dose head chamber 100. The displacement passage 102b is fluidly connected to the subchamber 80b and the dose head chamber 100. The displacement passage 102b is configured to receive air at a second axial side of the dose piston head 114 and to output air into the dose head chamber 100 at a first axial side of the dose piston head 114. The displacement passage 102b extends axially around the dose head seal 120 to introduce compressed air into the dose head chamber 100 opposite the dose head seal 120, from which the displacement passage 102b receives air. The compressed air supplied to the dose head chamber 100 through the displacement passage 102b is configured to displace the dose piston 86 in a first axial direction AD1. Displacement passage 102a provides a flow path through control piston head 92 for compressed air to enter dose head chamber 100 on the axial side of dose piston head 114 oriented in second axial direction AD2. Displacement passage 102b is configured to introduce compressed air into dose head chamber 100 to drive dose piston 86 along second axial direction AD2 from the second dose position to the first dose position. The compressed air supplied through displacement passage 102b can form at least a portion of the purge air for spray applicator 12. The compressed air supplied through displacement passage 102b can flow downstream through purge air holes 118 in dose piston 86 to entrain and carry solvent to mixing chamber 30.

[0057] The feed groove 90 extends into the body 20. The feed groove 90 extends radially outward from the piston bore 82 relative to the actuation axis AA. The feed groove 90 may extend substantially about the actuation axis AA. The feed groove 90 may be formed as an annular groove. In the illustrated embodiment, the feed groove 90 may be formed as a ring for holding a predetermined volume of solvent. The feed groove 90 forms part of a solvent circuit and is fluidly connected to a solvent source (e.g., solvent cartridge 28). In the illustrated embodiment, the feed groove 90 is fluidly connected to the solvent source during operation. When the control piston 84 extends into the piston bore 82, the feed groove 90 may be considered to form a solvent supply chamber that supplies solvent for uptake in the purge air.

[0058] The control piston shaft 94 extends from the control piston head 92. The control piston shaft 94 extends into the piston bore 82 formed in the body 20. The control piston shaft 94 extends from the control piston head 92 along a first axial direction AD1. The control piston shaft 94 may be cylindrical, and the piston bore 82 may be cylindrical. Shaft seals 96a and 96b are disposed adjacent to the control piston shaft 94. The shaft seals 96a and 96b are disposed axially on either side of a solvent groove 106 formed in the body 20 during operation. The shaft seals 96a and 96b engage and seal against the body 20 during operation as the control piston 84 reciprocates within the piston bore 82. The shaft seals 96a and 96b prevent solvent from leaking axially past either shaft seal 96a, 96b between the control piston shaft 94 and the body 20. In the illustrated embodiment, each shaft seal 96 a, 96 b is disposed within a seal groove formed in the radially outer surface of the control piston shaft 94. The shaft seals 96 a, 96 b may be of any configuration suitable for providing a fluid seal between the control piston shaft 94 and the body 20, such as an elastomeric seal. For example, the shaft seals 96 a, 96 b may be formed as O-rings, among other options. In the illustrated embodiment, the shaft seals 96 a, 96 b are formed as dynamic seals that slide axially relative to the body 20 when the spray applicator 12 operates between the spray state and the purge state.

[0059] The solvent groove 106 is formed in the radially outer surface of the control piston shaft 94. The solvent groove 106 is axially disposed between the shaft seals 96a, 96b. The solvent groove 106 is axially disposed between the seal grooves that retain the shaft seals 96a, 96b. The solvent groove 106 is formed as a recess in the outer surface of the control piston shaft 94. The solvent groove 106 can extend annularly. The solvent groove 106 can extend completely around the control piston shaft 94. The solvent groove 106 can extend completely circumferentially around the actuation axis AA. The solvent groove 106 is configured to retain a predetermined amount of solvent between the body 20 and the control piston shaft 94 for rapid delivery to the retention groove 110.

[0060] The solvent chamber is partially defined by the body 20 in the illustrated embodiment. The solvent chamber is formed by the body 20 and the control piston 84. The solvent chamber includes a feed groove 90, a solvent groove 106, and an axial passage therebetween. The length of the axial passage changes during operation as the control piston 84 reciprocates relative to the body 20. The feed groove 90 may also be referred to as a body groove. The solvent groove 106 may also be referred to as a piston groove.

[0061] The solvent passage 108 extends through the body of the control piston 84 between the retaining groove 110 and the exterior of the control piston 84. In the illustrated embodiment, the solvent passage 108 extends radially between the solvent groove 106 and the retaining groove 110. An outer radial opening of the solvent passage 108 is formed through the outer surface of the control piston shaft 94. The outer radial opening may also be referred to as a solvent inlet. An inner radial opening of the solvent passage 108 is formed through the inner radial surface of the control piston shaft 94. The inner radial opening may also be referred to as a solvent outlet. In the illustrated embodiment, the solvent outlet is formed within the retaining groove 110. The solvent passage 108 defines a flow path that allows solvent to flow from the exterior of the control piston 84 through the control piston shaft 94 to the interior of the control piston 84. Specifically, the solvent passage 108 defines a flow path for solvent to flow between the solvent groove 106 and the retaining groove 110.

[0062] A retention groove 110 is formed in the control piston shaft 94. The retention groove 110 extends radially outward from the shaft bore 104 relative to the actuation axis AA. The retention groove 110 can extend completely around the actuation axis AA. The retention groove 110 can be formed as an annular groove. In the illustrated embodiment, the retention groove 110 is formed as a ring for retaining a predetermined volume of solvent. The retention groove 110 forms part of the solvent passage 36 and is fluidly connected to a solvent source (e.g., solvent cartridge 28). The retention groove 110 can be fluidly connected to the solvent reservoir 27 during operation of the spray applicator 12. The solvent reservoir 27 can be pressurized, and the pressurized solvent is fluidly connected to the supply groove 90, the solvent groove 106, the solvent passage 108, and the retention groove 110 during operation.

[0063] The dose piston 86 is at least partially disposed within the control piston 84. In the illustrated embodiment, the dose piston 86 is disposed completely within the control piston 84. In the illustrated embodiment, the dose piston 86 does not extend axially outward from the control piston 84. The dose piston 86 is supported by the control piston 84. The dose piston 86 is movable relative to the control piston 84. Thus, the control piston 84 can be considered to carry the dose piston 86 without being connected to it.

[0064] A dose piston head 114 is disposed within the dose head chamber 100. A dose piston shaft 116 extends from the dose piston head 114. The dose piston shaft 116 extends into a shaft bore 104 formed in the control piston 84. The dose piston shaft 116 is configured to slide axially within the shaft bore 104 relative to the control piston 84. The shaft bore 104 may, in some embodiments, extend completely axially through the control piston shaft 94. The dose piston shaft 116 extends from the dose piston head 114 along a first axial direction AD1. Thus, the dose piston shaft 116 and the control piston shaft 94 extend from the dose piston head 114 and the control piston head 92, respectively, along the same axial direction. The dose piston shaft 116 moves within the shaft bore 104 but is not fixed to the shaft bore 104, allowing the dose piston shaft 116 to move relative to the control piston shaft 94. The dose piston 86 is movable with the control piston shaft 94 within a shaft bore 104 such that the shaft bore 104 is aligned with the dose piston 86 for movement along the actuation axis AA.

[0065] The dosing seals 122a-122c are disposed on the dose piston shaft 116. The dosing seals 122a-122c are radially disposed between the dose piston shaft 116 and the control piston shaft 94. The dosing seals 122a-122c engage the inner radial surface of the control piston shaft 94, which defines the shaft bore 104, to prevent solvent from leaking axially between the dose piston 86 and the control piston 84. In the illustrated embodiment, each dosing seal 122a-122c is disposed in a seal groove formed on the outer radial surface of the dose piston shaft 116. The dosing seals 122a-122c can be of any suitable configuration, such as an elastomeric seal, to provide a fluid seal between the dose piston shaft 116 and the control piston shaft 94. For example, the dosing seals 122a-122c can be formed as O-rings, among other options. In the illustrated embodiment, the dosing seals 122a-122c are formed as dynamic seals that slide axially against the control piston 84 as the dose piston 86 is actuated to move relative to the control piston 84 along the axis AA.

[0066] The dosing seal 122a is disposed at a first axial position on the dose piston shaft 116. The dosing seal 122b is disposed at a second axial position on the dose piston shaft 116. The dosing seal 122c is disposed at a third axial position on the dose piston shaft 116. The first position is axially located between the dose piston head 114 and the second axial position. The dosing seal 122a is disposed such that the dosing seal 122a is located on a first axial side of the retention groove 110 during operation. The dosing seal 122a is disposed such that the dosing seal 122a contacts and seals against the control piston shaft 94 during operation, as will be explained in more detail below.

[0067] Dosing seal 122b is axially disposed between dosing seal 122a and dosing seal 122c. Dosing seal 122b can be considered to form a middle seal between dosing seals 122a-122c, while dosing seals 122a and 122c form end seals between dosing seals 122a-122c. Dosing seal 122b is configured to contact the control piston shaft 94 during a portion of the reciprocating motion of the dose piston 86. Dosing seal 122b is configured to interface with a portion of the control piston shaft 94 located on the opposite axial side of the retention groove 110 from dosing seal 122a. Dosing seal 122b interfaces with the control piston shaft 94 when the spray applicator 12 is in purge mode. Dosing seal 122b, which interfaces with the control piston shaft 94, fluidly separates the retention groove 110 from the dosing groove 112. The dosing seal 122b thereby fluidly separates the solvent passage 36 and the air passage 38 when the dosing seal 122b is engaged with the control piston shaft 94. The dosing seal 122b engages with a portion of the control piston shaft 94 that is spaced from the retention groove 110 in the first axial direction AD1.

[0068] The dosing seal 122b does not interact with the control piston shaft 94 throughout operation. With the spray applicator 12 in the spray state, the dosing seal 122b disengages from the control piston shaft 94 and is positioned to radially overlap the retaining groove 110 such that a radial line extending from the actuation axis AA extends through both the dosing seal 122b and the retaining groove 110. With the dosing seal 122b disengaged from the control piston shaft 94, it fluidly connects the retaining groove 110 to the transfer groove 124. With the dosing seal 122b disengaged from the control piston shaft 94, it fluidly connects the transfer groove 124 to the solvent passage 36, allowing solvent to flow to and enter the transfer groove 124.

[0069] The dosing seal 122c is disposed at the end of the dose piston shaft 116 opposite the dose piston head 114. The dosing seal 122c forms a distal seal for the dose piston 86. The dosing seal 122c is spaced apart from the dosing seals 122a and 122b along the first axial direction AD1. The dosing seal 122c is disposed on the axial side of the transfer groove 124 opposite the dosing seal 122b. The dosing seal 122c is configured to interface with a portion of the control piston shaft 94 on the opposite axial side of the retention groove 110 from the dose piston head 114. The dosing seal 122c can interface with the same portion of the control piston shaft 94 as the dosing seal 122b. The dosing seal 122c interfaces with the control piston shaft 94 when the spray applicator 12 is in the spray mode. A dosing seal 122c, which interfaces with the control piston shaft 94, fluidly separates the retention groove 110 from the dosing groove 112. The dosing seal 122c thereby fluidly separates the solvent passageway 36 and the air passageway 38.

[0070] The dosing seal 122c does not interact with the control piston 84 throughout operation. The dosing seal 122c disengages from the control piston shaft 94 and is disposed within the dosing groove 112 when the spray applicator 12 is in purge mode. The dosing seal 122c disengaged from the control piston shaft 94 fluidly connects the delivery groove 124 to the dosing groove 112. The dosing seal 122c disengaged from the control piston shaft 94 fluidly connects the delivery groove 124 to the air passage 38 so that solvent can flow into and be entrained in the purge air flowing through the air passage 38.

[0071] Dosing seals 122a-122c are configured to fluidly isolate retention groove 110 from the pneumatic passageway of spray applicator 12. Dosing seal 122a maintains contact with control piston shaft 94 during operation to prevent solvent from flowing between control piston shaft 94 and dose piston shaft 116 along second axial direction AD2. One or both of dosing seals 122b, 122c are engaged with control piston shaft 94 during operation.

[0072] The dosing groove 112 is fluidly isolated from the retention groove 110 during operation. In the illustrated embodiment, the dosing groove 112 is fluidly isolated from the retention groove 110 by a dynamic sealing interface between the dose piston 86 and the control piston 84. The dynamic sealing interface fluidly separates the solvent passageway 36 and the air passageway 38 of the spray applicator 12. Specifically, the dosing groove 112 is fluidly isolated from the retention groove 110 by dosing seals 122 b, 122 c. The dosing seals 122 b, 122 c are positioned along the dose piston shaft 116 such that at least one of the dosing seals 122 b, 122 c contacts the control piston shaft 94 during operation. The dynamic sealing interface prevents solvent from flowing between the control piston shaft 94 and the dose piston shaft 116 along the first axial direction AD1. As the dose piston 86 shifts along the first axial direction AD1, the dose seal 122b engages the control piston shaft 94 before the dose seal 122c disengages from the control piston shaft 94. As the dose piston 86 shifts along the second axial direction AD2, the dose seal 122c engages the control piston shaft 94 before the dose seal 122b disengages from the control piston shaft 94.

[0073] The transfer groove 124 is formed on the dose piston 86. Specifically, the transfer groove 124 is formed on the dose piston shaft 116. The transfer groove 124 extends radially inward into the dose piston shaft 116. The transfer groove 124 is formed as a recess in the dose piston shaft 116. The transfer groove 124 is axially disposed between the dosing seal 122b and the dosing seal 122c. The transfer groove 124 can be considered to be axially bracketed by the dosing seals 122b, 122c. The transfer groove 124 can be formed as an annular groove around the dose piston shaft 116. The transfer groove 124 can extend completely around the actuation axis AA. The transfer groove 124 is configured to pick up a predetermined dose volume of solvent from the retaining groove 110 and transfer the solvent to the dosing groove 112. The solvent is then entrained in the purge air flowing through the air passage 38 (eg, entrained in the second purge air portion through the second passage 44) and carried by the purge air to the mixing chamber 30.

[0074] The purge air hole 118 extends axially within the dose piston 86. In the illustrated embodiment, the purge air hole 118 extends axially completely through the dose piston 86. The purge air hole 118 extends axially between a purge hole inlet 126 and a purge hole outlet 128. The purge air hole 118 defines a purge passageway through the dose piston 86, through which purge air flows to entrain solvent and carry it to the mixing chamber 30. The purge hole inlet 126 is formed in the dose piston head 114. The purge hole inlet 126 is oriented axially along the second axial direction AD2. The purge hole outlet 128 is formed in the dose piston shaft 116. The purge hole outlet 128 is oriented axially along the first axial direction AD1. The purge air hole 118 forms part of the air passageway 38 of the spray applicator 12. Purge air hole 118 is in fluid communication with displacement passage 102b and, therefore, sub-chamber 80b. Purge air hole 118 is configured to receive compressed air from sub-chamber 80b, which flows through purge air hole 118 and is output through purge hole outlet 128 to shaft hole 104.

[0075] In the illustrated embodiment, the purge air holes 118 are formed by a series of holes whose diameters gradually decrease as the purge air holes 118 extend along the first axial direction AD1. The purge hole inlets 126 have a larger diameter than the purge hole outlets 128 in the illustrated embodiment. As the diameter of the purge air holes 118 decreases, the velocity of the purge air flowing through the purge air holes 118 increases. The purge hole outlets 128 increase in diameter and open into the larger diameter shaft bore 104, specifically into the portion of the shaft bore 104 where the dosing groove 112 is formed. In some embodiments, the purge air outlets 128 form a seat for an air flow control valve, such as a valve ball, to prevent backflow through the purge air holes 118. The purge hole outlets 128 opening into the larger diameter shaft bore 104 promote turbulence, entraining solvent in the purge air.

[0076] The spray lock 88 interfaces with the control piston 84. The spray lock 88 is actuable between an unlocked state and a locked state (shown in FIG. 5C). When the spray lock 88 is in the unlocked state, the control piston 84 can reciprocate along the actuation axis AA to move the shuttles 62a, 62b and place the spray applicator 12 in the purge state. When the spray lock 88 is in the locked state, the control piston 84 is held in a first control position associated with the purge state. When the spray lock 88 is locked, the control piston 84 is prevented from moving along the first axial direction AD1. The spray lock 88 maintains the control piston 84 in the first control position to prevent a user from inadvertently actuating the spray applicator 12 to the spray state and causing the release of the multiple-component material. The spray lock 88 thereby forms a safety device that prevents actuation to the spray state even when an air pressure source is connected to the spray applicator 12 and actuated to supply compressed air to the spray applicator 12.

[0077] The lock knob 130 is connected to the receiver 132 such that the lock knob 130 can rotate the receiver 132 about a lock axis, which in the illustrated embodiment is coaxial with the actuation axis AA. In the illustrated embodiment, the spray lock 88, the control piston 84, and the dose piston 86 are each linearly aligned coaxially on the actuation axis AA. A retainer 134 is connected to the control piston 84. In the illustrated embodiment, the retainer 134 is partially disposed within a chamber formed in the control piston head 92 of the control piston 84. The retainer 134 extends axially outward from the axial side 98a of the control piston head 92. A pneumatic seal is formed between the retainer 134 and the control piston 84, for example, by an elastomeric seal radially disposed between the retainer 134 and the control piston head 92. The retainer 134 can at least partially define the dose head chamber 100. The retainer 134 may be secured to the control piston 84 in any desired manner, such as by a clip or ring that snaps into a groove in the control piston 84 .

[0078] A retainer 134 interfaces with the receiver 132. In the illustrated embodiment, a retainer shaft 136 extends into the receiver bore 138. A bar 140 interfaces with the receiver 132 within one or more slots in the receiver 132. The bar 140 extends through the retainer shaft 136. The retainer 134 is able to move axially relative to the receiver 132 when the spray lock 88 is in the unlocked state. The retainer 134 is prevented from moving axially relative to the receiver 132 when the spray lock 88 is in the locked state. Rotating the lock knob 130 displaces the bar 140 within the slot in the receiver 132, drawing the control piston 84 to the first control position. In the illustrated embodiment, the locking knob 130 rotates the receiver 132, which retracts the retainer 134 along the second axial direction AD2 via the bar 140, and the retainer 134 then retracts the control piston 84 along the second axial direction AD2 to the first control position.

[0079] The spray lock 88 can lock the control piston 84 in a position associated with the purge state, but the spray lock 88 does not lock the dose piston 86. The dose piston 86 is free to reciprocate along the actuation axis AA relative to the control piston 84, while the control piston 84 is fixed in the first control position. The spray lock 88 does not interface with the dose piston 86. The retainer 134 is not connected to the dose piston 86. In some embodiments, the retainer 134 defines the range of axial movement of the dose piston 86, but the retainer 134 locks the position of the dose piston 86 relative to the control piston 84.

[0080] A dose piston 86 that is movable relative to the control piston 84 allows the dose piston 86 to actuate between a first dose position and a second dose position, while the control piston 84 remains stationary. Thus, a user can dispense solvent into the purged air by triggering and releasing the trigger of the spray applicator 12 without actuating the spray applicator 12 to a spray state.

[0081] During operation, the spray applicator 12 is initially in a purge state, with the control piston 84 in the first control position and the dose piston 86 in the first dose position. The initial state of the spray applicator 12 is shown in FIGS. 4A and 5C. The shuttles 62a, 62b may be directly connected to the control piston head 92 (e.g., by connecting threads therebetween) and are arranged to fluidly connect the purge air passage to the mixing chamber 30. The purge air flows through the mixing chamber 30 and is discharged through the spray orifice 32. Compressed air is initially directed into the sub-chamber 80b to urge the control piston 84 in the second axial direction AD2. The compressed air acts on the axial side 98b of the control piston head 92, exerting a driving force on the control piston head 92 in the first axial direction AD2. The compressed air can maintain the control piston 84 in the first control position. A portion of the compressed air flows through the inlet passage 78b into the dose head chamber 100.

[0082] A portion of the compressed air entering sub-chamber 80b flows into and through a displacement passage 102b formed in the control piston head 92. The compressed air flows through the displacement passage 102b into the dose head chamber 100, exerting a force on the dose piston head 114. The compressed air urges the dose piston 86 along the first axial direction AD1, driving the dose piston 86 and maintaining it in the first dose position. The displacement passage 102b provides a flow path through the control piston head 92. The control piston head 92 receives compressed air in the dose head chamber 100 on the axial side of the dose piston head 114 oriented in the second axial direction AD2. When the spray applicator 12 is in a purging state, the compressed air acts on both axial sides of the control piston 84 and the dose piston 86. The compressed air acts on the side of the control piston 84 oriented in the first axial direction AD1 and on the side of the dose piston 86 oriented in the second axial direction AD2. When the spray applicator 12 is in a purging state, the compressed air urges the control piston 84 along the second axial direction AD2 and urges the dose piston 86 along the first axial direction AD1.

[0083] Compressed air flows from a first axial side of drive head seal 120 to an opposite second axial side of drive head seal 120. Compressed air flows on the opposite axial side of drive head seal 120 when spray applicator 12 is in a purging state. Compressed air flows inside control piston 84 on both axial sides of drive head seal 120.

[0084] The compressed air urges the dose piston 86 along the first axial direction AD1 and also flows through the dose piston 86 through the purge air holes 118. The compressed air flowing through the dose piston 86 forms at least a portion of the purge air flowing to the mixing chamber 30. In some embodiments, the compressed air flowing through the dose piston 86 forms at least a portion of the second purge air portion. In some embodiments, all of the purge air flows through the purge air holes 118 in the dose piston 86. The compressed air flows downstream through the dose piston 86 and the shaft holes 104 to the mixing chamber 30. A purge valve can be disposed in the air passage between the dose piston 86 and the mixing chamber 30 to prevent backflow of purge air into the dose piston 86. The purge valve maintains air pressure in the downstream portion of the air pressure passage to provide a rapid response to and flow of purge air through the mixing chamber 30 when the spray applicator 12 is actuated to a purge state.

[0085] The user actuates the trigger 22 to cause spraying by the spray applicator 12. The shifting of the control piston 84 and the dose piston 86 from the position associated with the purge mode to the position associated with the spray mode is shown in FIGS. 4A through 4C. The control piston 84 and the dose piston 86 are initially in the positions shown in FIG. 4A. The control piston 84 is in the first control position, and the dose piston 86 is in the first dose position. The user-actuated trigger 22 shifts the control valve 26 to direct compressed air into the inlet passage 78a and stop the flow of compressed air into the inlet passage 78b. The control valve 26 fluidly connects the inlet passage 78b to the exhaust port of the spray applicator 12. The compressed air enters the subchamber 80a through the inlet passage 78a and acts against the axial side 98a of the control piston head 92, urging the control piston 84 along the first axial direction AD1. The compressed air displaces the control piston 84 in the first axial direction AD1 and displaces the dose piston 86 in the second axial direction AD2. A portion of the compressed air flowing into the subchamber 80a flows through a displacement passage 102a formed in the control piston head 92. The displacement passage 102a includes an inlet through the axial side 98a of the control piston head 92 and an outlet to the dose head chamber 100. The compressed air enters the dose head chamber 100 and urges the dose piston 86 along the second axial direction AD2. The displacement passage 102a provides a flow path through the control piston head 92. The control piston head 92 directs the compressed air into the dose head chamber 100 at the axial side of the dose piston head 114 oriented in the first axial direction AD1. The compressed air flows into a retaining groove 110 within the control piston 84. When the spray applicator 12 is in the spray state and transitioning to the spray state, the compressed air acts on both axial sides of the control piston 84 and the dose piston 86. The compressed air acts on the side of the control piston 84 oriented in the second axial direction AD2 and on the side of the dose piston 86 oriented in the first axial direction AD1.

[0086] Figure 4B shows the spray applicator in a first transition state. For purposes of illustration, Figure 4B shows the dose piston 86 and the control piston 84 in positions associated with opposite states. It is understood that during operation, compressed air acts on the control piston 84 and the dose piston 86 simultaneously. Thus, although the dose piston 86 and the control piston 84 are shown in Figure 4B in positions associated with opposite states (control piston 84 in the first control position and dose piston 86 in the second dose position), it is understood that the dose piston 86 and the control piston 84 move together between states.

[0087] The control piston 84 moves in a first axial direction AD1 to shift the shuttles 62a, 62b and fluidly connect the flow of base component material with the mixing chamber 30. The compressed air also displaces the dose piston 86 relative to the control piston 84. As the control piston 84 shifts along the first axial direction AD1, the dose piston 86 shifts along a second axial direction AD2. As the spray applicator 12 transitions to the spray state, the dose piston 86 moves in the opposite axial direction from the control piston 84.

[0088] In the illustrated embodiment, the dose piston 86 moves in the opposite direction relative to the control piston 84, but the dose piston 86 displaces in the same axial direction relative to the body 20 of the spray applicator 12 as the control piston 84 when the spray applicator 12 transitions between the spray and purge states. For example, length L1, which is the displacement distance of the control piston 84 relative to the body 20, is greater than length L2, which is the displacement distance of the dose piston 86 relative to the control piston 84. As a result, the control piston 84 shifts a greater axial distance along the actuation axis AA than the dose piston 86. Thus, the dose piston 86 shifts along an axial direction AD1 relative to the body 20 between the first and second dose positions, while the dose piston 86 displaces relative to the control piston 84 along an opposite, second axial direction AD2.

[0089] The dose piston 86 shifts in the second axial direction AD2 relative to the control piston 84, causing the dose seal 122b to disengage from the control piston 84 and the dose seal 122c to engage with the control piston 84. The delivery groove 124 is fluidly connected to the retention groove 110. The solvent flows into the delivery groove 124.

[0090] The spray applicator 12 is shown in a spraying state in FIG. 4C. Compressed air urges the control piston 84 in a first axial direction AD1 and urges the dose piston 86 in a second axial direction AD2. The dose head seal 120 fluidly separates the compressed air supplied through the displacement passage 102a from the purge air hole 118 through the dose piston 86. The dose head seal 120 divides the dose head chamber 100 into a dose chamber 101b and a reset chamber 101a. Air supplied to the reset chamber 101a drives the dose piston 86 in the second axial direction AD2, fluidly connecting the transfer groove 124 to the holding groove 110. Air supplied to the dose chamber 101b drives the dose piston 86 in the first axial direction AD1, fluidly connecting the transfer groove 124 to the dosing groove 112. The same air that drives the dose piston 86 in the first axial direction AD1 flows through the purge air passage defined by the purge air holes 118, picking up solvent. Thus, the same air that drives the dose piston 86 can also pick up and carry solvent into the mixing chamber 30 for flushing the mixing chamber 30.

[0091] To stop spraying, the user releases the trigger 22. When the trigger 22 is released, the spray applicator 12 is actuated to the purge state. The shifting of the control piston 84 and the dose piston 86 from the position associated with the spray mode to the position associated with the purge mode is shown in FIGS. 5A through 5C. The control piston 84 and the dose piston 86 are initially in the position shown in FIG. 5A. The control piston 84 is in the second control position, and the dose piston 86 is in the second dose position. Releasing the trigger 22 shifts the control valve 26 to a state in which it directs compressed air into the inlet passage 78b and fluidly connects the inlet passage 78a with the exhaust of the spray applicator 12. The compressed air enters the subchamber 80b through the inlet hole 78b. The compressed air flowing through the inlet hole 78b acts on the axial side 98b of the control piston head 92, urging the control piston 84 in the second axial direction AD2. The compressed air displaces the control piston 84 in the second axial direction AD2, moving the control piston 84 from the second control position shown in FIG. 5A to the first control position shown in FIG. 5C.

[0092] Compressed air supplied to sub-chamber 80b flows through displacement passage 102b to dose head chamber 100. The compressed air flowing through displacement passage 102b acts on dose piston head 114, urging dose piston 86 in a first axial direction AD1. The compressed air displaces dose piston 86 relative to control piston 84. As control piston 84 shifts in a second axial direction AD2, dose piston 86 shifts in the first axial direction AD1. As spray applicator 12 transitions from the spray state to the purge state, dose piston 86 moves in the opposite axial direction from control piston 84.

[0093] In the illustrated embodiment, the dose piston 86 moves relative to the control piston 84 in the opposite direction to the control piston 84 , but the dose piston 86 displaces in the same axial direction relative to the body 20 as the control piston 84 .

[0094] FIG. 5B shows the spray applicator 12 in a second transitional state. It is understood that during operation, compressed air acts simultaneously on the control piston 84 and the dose piston 86. Thus, while the dose piston 86 and the control piston 84 are shown in FIG. 5B in positions associated with opposite states, it is understood that the dose piston 86 and the control piston 84 operate together between states. For purposes of illustration, FIG. 3B shows the dose piston 86 and the control piston 84 in positions associated with opposite states. The dose piston 86 is shown in a first dose position associated with the release of purge air, while the control piston 84 is shown in a second control position associated with the release of the multi-component material. Compressed air continues to act on the control piston 84 and the dose piston 86, driving the control piston 84 and the dose piston 86 to the positions shown in FIG. 5C.

[0095] Compressed air flowing through displacement passage 102b into dose head chamber 100 is fluidly connected to purge air port 118 via dose piston 86. A portion of the compressed air is discharged through purge air port 118 and through purge port outlet 128 into shaft bore 104. The compressed air flows downstream through shaft bore 104 and, in some embodiments, through a flow path within body 20 to mixing chamber 30 for discharge as purge air.

[0096] The dose piston 86 shifts in the first axial direction AD1 such that the dose seal 122b engages the control piston 84 and the dose seal 122c disengages from the control piston 84. The transfer groove 124 is fluidly connected to the dosing groove 112 and fluidly disconnected from the retaining groove 110. The transfer groove 124 is fluidly connected to the dose piston 86 and the flow of purge air through the shaft bore 104. The transfer groove 124 transfers the dose volume of solvent within the transfer groove 124 and between the retaining groove 110 and the dosing groove 112. The solvent in the transfer groove 124 is entrained in the air flow through the purge air hole 118 and the shaft bore 104 and is carried downstream by the purge air to the mixing chamber 30.

[0097] The control piston 84 is displaced in the second axial direction AD2 to shift to the first control position. The shuttles 62a, 62b are driven in the second axial direction AD2 to fluidly disconnect the component material flow from the mixing chamber 30 and fluidly connect the purge air flow to the mixing chamber 30. The compressed air drives the displacement of the control piston 84 and the dose piston 86 until the control piston 84 is positioned in the first control position and the dose piston 86 is positioned in the first dope position, as shown in FIG. 5C.

[0098] As described above, the spray lock 88 can be placed in a locked state to maintain the control piston 84 in the first control position. With the control piston 84 locked in the first control position, the dose piston 86 can still be actuated to dispense a predetermined volume of solvent into the mixing chamber 30, facilitating thorough cleaning of the mixing chamber 30.

[0099] With the control piston 84 locked in the first position, the spray applicator 12 can be triggered to actuate between the states shown in Figures 4B and 5C. The control piston 84 is maintained in the first control position. The trigger 22 is pulled, delivering compressed air through the inlet hole 78a to the subchamber 80a. The compressed air flows through the displacement passage 102a and drives the dose piston 86 in the second axial direction AD2 to the second dose position. The spray lock 88 prevents axial movement of the control piston 84. With the dose piston 86 in the second dose position, the delivery groove 124 is fluidly connected to the retention groove 110 to receive the solvent.

[0100] When the spray applicator 12 is detriggered, it stops supplying compressed air to subchamber 80a and instead directs compressed air to subchamber 80b. The compressed air enters the subchamber through inlet hole 78b. A portion of the compressed air flows through displacement passage 102b to dose head chamber 100. The compressed air drives dose piston 86 in the first axial direction AD1 to the first dose position. Transfer groove 124 is fluidly isolated from retention groove 110 and fluidly connected to dosing groove 112 and the downstream portion of shaft bore 104 of the dose piston. Compressed air from dose head chamber 100 flows downstream through purge air hole 118, picking up the dose of solvent and carrying it to the mixing chamber. The user continues to trigger and de-trigger the spray applicator 12, delivering additional doses of solvent downstream to mixing chamber 30 to clean it.

[0101] The spray applicator 12 provides significant advantages. The dose piston 86 delivers a discrete dose of solvent for entrainment in the purge air and transfer to the mixing chamber 30. The dose piston 86 is carried by and rides within the control piston 84, reducing the size of the body 20 compared to an arrangement in which the dose piston 86 is carried separately from the control piston 84. Because the dose piston 86 is decoupled from the control piston 84, the dose piston 86 can move relative to the control piston 84 even when the control piston 84 is in a locked position relative to the body 20. The dose piston 86 both carries a dose of solvent and defines a purge air hole 118 through which purge air is delivered, simplifying the configuration of solvent injection into the purge air stream.

[0102] 6 is an isometric cross-sectional view of a portion of spray applicator 12. Shown are body 20, control valve 26, handle 60, trigger 22, connecting piece 52, control piston 84, dose piston 86, and spray lock 88 of spray applicator 12. Feed groove 90 and piston bore 82 in body 20 are shown.

[0103] Shown are the control piston head 92, control piston shaft 94, and shaft seals 96a, 96b of the control piston 84. The control piston head 92 includes an axial side 98a, an axial side 98b, a dose head chamber 100, and displacement passages 102a, 102b (only displacement passage 102a is shown in FIG. 6). The control piston shaft 94 includes a shaft bore 104, a solvent groove 106, a solvent passage 108, a retention groove 110, and a dosing groove 112. Shown are the dose piston head 114, dose piston shaft 116, a purge air bore 118, a dose head seal 120, and dose seals 122a-122c of the dose piston 86. The dose piston shaft 116 includes a transfer groove 124.

[0104] The control piston 84 is configured to reciprocate along an actuation axis AA between a first control position associated with the release of purge air and a second control position associated with the release of the multi-component material. The control piston 84 is shown in the second control position in FIG. 6. The dose piston 86 is configured to reciprocate between a first dose position associated with the dispensing of solvent into the purge air and a second dose position associated with the picking up of solvent from the solvent passage 36. The dose piston 86 is shown in the second dose position in FIG. 6. The dose piston 86 moves relative to the control piston 84 between the first dose position and the second dose position.

[0105] The control piston 84 is configured to reciprocate between a first control position and a second control position along an actuation axis AA. As shown, the control piston head 92 includes a cylindrical outer surface disposed within the cylindrical surface of the body 20 that defines the drive chamber 76. The control piston shaft 94 extends from the control piston head 92 into the piston bore 82 in the body 20. In the illustrated embodiment, the control piston shaft 94 is cylindrical and the piston bore 82 is also cylindrical. The control piston shaft 94 and the piston bore 82 are coaxially disposed on the actuation axis AA.

[0106] The dose piston 86 is disposed coaxially with the control piston 84 on the actuation axis AA. The dose piston head 114 is disposed in the dosing groove 112 and is configured to reciprocate therein. A dose piston shaft 116 extends axially from the dose piston head 114. The dose piston shaft 116 extends into a shaft bore 104 formed in the control piston shaft 94 and reciprocates therein. The dose piston shaft 116 is disposed coaxially with the control piston shaft 94. The dose piston 86 is decoupled from the control piston 84 but is carried by the control piston 84 such that the dose piston 86 is movable relative to the control piston 84.

[0107] 7 is a cross-sectional view of the dose piston 86'. The dose piston 86' is substantially similar to the dose piston 86, except that the dose piston 86' is configured to output purge air away from the axis AA rather than along the axis AA. The dose piston 86' includes a dose piston head 114, a dose piston shaft 116', a purge air hole 118', and dose seal grooves 123a-123c. The dose piston shaft 116' includes a transfer groove 124. The purge air hole 118' includes a purge hole inlet 126, a purge hole outlet 128', and an outlet hole 142.

[0108] The dose piston head 114 is disposed at the axial end of the dose piston shaft 116′. The dose piston shaft 116′ extends from the dose piston head 114. The dose piston shaft 116′ is configured to extend into a shaft bore 104 formed in the control piston 84. The dose piston shaft 116′ is configured to slide axially within the shaft bore 104 relative to the control piston 84. The dose piston shaft 116′ extends from the dose piston head 114 in a first axial direction AD1. The dose piston shaft 116′ is configured to move within the shaft bore 104 but is not fixed to the shaft bore 104, allowing the dose piston shaft 116′ to move relative to the control piston shaft 94. The dose piston 86′ interfaces with the control piston shaft 94 within the shaft bore 104, such that the shaft bore 104 is aligned with the dose piston 86′ for movement along the actuation axis AA.

[0109] Dose seal grooves 123a-123c are formed on the dose piston shaft 116'. The dose seal grooves 123a-123c are configured to receive the dosing seals 122a-122c, respectively. The dose seal grooves 123a-123c are arranged along and about the dose piston shaft 116'.

[0110] The dose seal groove 123a is located at a first axial groove position on the dose piston shaft 116'. The dose seal groove 123b is located at a second axial groove position on the dose piston shaft 116'. The dose seal groove 123c is located at a third axial groove position on the dose piston shaft 116'. The first groove position is axially located between the dose piston head 114 and the second axial groove position. The second groove position is axially located between the first groove position and the third groove position.

[0111] The transfer groove 124 is formed on the dose piston 86'. Specifically, the transfer groove 124 is formed on the dose piston shaft 116'. The transfer groove 124 extends radially inward into the dose piston shaft 116'. The transfer groove 124 does not extend to or intersect with the purge air holes 118'. The transfer groove 124 is formed as a recess in the dose piston shaft 116'. The transfer groove 124 is axially disposed between the dose seal groove 123b and the dose seal groove 123c. The transfer groove 124 can be considered to be axially bounded by the dose seal grooves 123b, 123c. The transfer groove 124 can be formed as an annular groove extending completely around the dose piston shaft 116'. The transfer groove 124 can extend completely around the actuation axis AA. The delivery groove 124 is configured to pick up a dosage volume of solvent from the holding groove 110 and transfer the solvent to the dosing groove 112. The solvent is then entrained in the purge air flowing through the air passage 38 (e.g., entrained in the second purge air portion through the second passage 44) and carried by the purge air to the mixing chamber 30.

[0112] The purge air hole 118' extends axially within the dose piston 86'. In the illustrated embodiment, the purge air hole 118' does not extend axially completely through the dose piston 86'. In the illustrated embodiment, the axial end of the dose piston shaft 116' opposite the dose piston head 114 is closed. The purge air hole 118' extends axially between the purge hole inlet 126 to an outlet hole 142' and radially to a purge air outlet 128'. The purge air hole 118' defines a purge passage through the dose piston 86'. Purge air flows through the dose piston 86', picking up solvent and carrying it to the mixing chamber 30. The purge hole inlet 126 is formed in the dose piston head 114. The purge hole inlet 126 is axially oriented in a second axial direction AD2. A purge hole outlet 128' is formed in the dose piston shaft 116'. The purge hole outlet 128' is directed radially outward away from the axis AA. The purge air hole 118' forms part of the air passage 38 of the spray applicator 12. The purge air hole 118' is in fluid communication with the displacement passage 102b and, therefore, with the sub-chamber 80b. The purge air hole 118' is configured to receive compressed air from the sub-chamber 80b, which flows through the purge air hole 118' and is output to the shaft bore 104 through the purge hole outlet 128'.

[0113] The outlet holes 142 form downstream portions of the purge air holes 118' in the illustrated embodiment. The outlet holes 142 extend away from the axis AA, rather than along the axis AA. The outlet holes 142 extend radially outward from the axial portion of the purge air holes 118' to the exterior of the dose piston shaft 116'. The outlet holes 142 extend between the axial portion of the purge air holes 118' and the purge air outlet 128'. The outlet holes 142 extend transversely to the axis AA. The outlet holes 142 are configured to direct purge air radially outward of the dose piston shaft 116' rather than through the axial end of the dose piston shaft 116'.

[0114] In the illustrated embodiment, the outlet holes 142 are formed as cross holes through the dose piston shaft 116'. The two illustrated outlet holes 142 are located 180 degrees apart on opposite sides of the axis AA. However, it will be understood that not all embodiments are so limited. In the illustrated embodiment, the dose piston 86' includes multiple purge air outlets 128'. However, it will be understood that not all embodiments are so limited. For example, the dose piston 86' can include a single purge air outlet 128', two purge air outlets 128', three purge air outlets 128', or any desired number of purge air outlets 128'.

[0115] The purge air outlet 128' is axially disposed between the dose seal groove 123c and the axial end of the dose piston shaft 116' opposite the dose piston head 114. The purge air outlet 128' is axially disposed between the transfer groove 124 and the axial end of the dose piston shaft 116' opposite the dose piston head 114. The purge air outlet 128' is configured to emit purge air having a radial velocity component as the purge air as it exits the dose piston 86'. Providing a radial velocity component improves solvent entrapment in the purge air and improves purging of material from the mixing chamber 30. As the purge air exits the purge air outlet 128', it can enter directly into the dosing groove 112 and impinge on surfaces defining the dosing groove 112. In some embodiments, the purge air is directed perpendicular to the axis AA. In some embodiments, the exit holes 142 are angled so that the purge air has both radial and axial velocity components.

[0116] In the illustrated embodiment, the purge air holes 118' are formed by a series of holes that gradually decrease in diameter as the purge air holes 118' extend in the first axial direction AD1, and an outlet hole 142' that extends radially outward from the dose piston shaft 116'. The purge hole inlets 126 have a larger diameter than the purge hole outlets 128' in the illustrated embodiment. The decreasing diameter of the purge air holes 118' increases the velocity of the purge air flowing through the purge air holes 118'. The radially oriented purge hole outlets 128' promote impingement of the purge air against the inner surface of the control piston shaft 94, which creates turbulence and entrains solvent within the purge air.

[0117] While the present invention has been described with reference to exemplary embodiments, it will be recognized by those skilled in the art that various modifications may be made and equivalents may be substituted for the elements without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is not intended that the invention be limited to the particular embodiments disclosed, but rather that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. 1. A spray device comprising: A sprayer body; a mixing chamber supported by the atomizer body; a purge air passageway extending to an inlet port of the mixing chamber for supplying purge air to the mixing chamber; a control piston at least partially disposed within the sprayer body, the control piston actuable along an axis between a first control position and a second control position, the first control position being associated with a purge mode in which the control piston fluidly isolates component flow paths from the mixing chamber, and the second control position being associated with a spray mode in which the control piston fluidly connects component flow paths to the mixing chamber; a dose piston at least partially disposed within the sprayer body, the dose piston actuable between a first dose position and a second dose position, the first dose position being a position associated with the release of purge air from the mixing chamber, the dose piston configured to supply solvent to a purge air passage when in the second dose position, the second dose position being a position associated with the release of multiple component material from the mixing chamber, the dose piston fluidly connected to a solvent passage when in a reset position; Equipped with the control piston shifts along an axis in a first axial direction from the first control position to the second control position, the control piston shifts along a second axial direction opposite the first axial direction from the second control position to the first control position, the dose piston shifts along the first axial direction from the second dose position to the first dose position, and the dose piston shifts along the second axial direction from the first dose position to the second dose position.

2. 10. The atomizing device of claim 1, wherein the dose piston is at least partially disposed within the control piston.

3. 3. The atomizing device of claim 2, wherein the dose piston is disposed entirely within the control piston.

4. 4. A spray device according to claim 1, wherein a dose piston head of the dose piston is arranged within a control piston head of the control piston.

5. 4. The spray device of claim 1, wherein the solvent passage comprises at least one passage formed in the control piston.

6. 6. The spray device of claim 5, wherein the at least one passageway extends through a control piston shaft of the control piston.

7. 7. The atomizing device of claim 6, wherein the control piston further comprises a solvent groove extending into an outer surface of the control piston shaft, the inlet of the at least one passageway being at least partially disposed within the solvent groove.

8. 8. The atomizing device of claim 7, wherein the solvent groove extends completely annularly around the control piston shaft.

9. a control piston head of the control piston dividing a drive chamber within the atomizer body into a first sub-chamber and a second sub-chamber; a dose piston head of the dose piston dividing a dose head chamber within the spray piston into a dose chamber and a reset chamber; a first displacement passageway formed through the control piston, the first displacement passageway in fluid communication with the first subchamber and the reset chamber; 2. The atomizer of claim 1, wherein a second displacement passage is formed through the control piston, the second displacement passage providing fluid communication with the second subchamber and the dose chamber.

10. 10. The spray device of claim 9, wherein the inlet of the first displacement passage is formed through a first axial side of the control piston head and the inlet of the second displacement passage is formed through a second axial side of the spray piston head.

11. 11. The atomizing device of claim 9, wherein the dose piston includes a purge passage extending therethrough, the purge passage being in fluid communication with the dose chamber and configured to form at least a portion of the purge air passage.

12. The atomizing device of claim 11 , wherein the purge passage includes an axially oriented purge air outlet.

13. The atomizing device of claim 11 , wherein the purge passage includes a radially oriented purge air outlet.

14. 11. A spray device according to claim 9 or 10, wherein the dose piston includes a dose piston shaft extending axially from the dose piston head, the end of the dose piston shaft opposite the dose piston head being closed.

15. a first displacement passage formed through a control piston head of the control piston; 2. The spray device of claim 1, wherein the first displacement passage supplies a motive fluid from a chamber on a first axial side of the control piston head to a chamber on a second axial side of the dose piston head, the first axial side of the control piston head being oriented along the axis in a first axial direction, and the second axial side of the dose piston head being oriented along the axis in a second axial direction, the first axial direction being opposite to the first axial direction.

16. further comprising a second displacement passage formed through the control piston head; 16. The spray device of claim 15, wherein a second displacement passage supplies motive fluid from a chamber on a second axial side of the control piston head to a chamber on the first axial side of the dose piston head, the second axial side of the control piston head being oriented in the second axial direction and the first axial side of the dose piston head being oriented in the first axial direction.

17. 17. The atomizer of any one of claims 1-3, 9, 10, 15 and 16, wherein the dose piston includes a purge passage extending therethrough, the purge passage providing purge air to the purge air passage.

18. 18. The atomizing device of claim 17, wherein the purge passage is configured to output the purge air axially.

19. 18. The atomizing device of claim 17, wherein the purge passage is configured to output the purge air radially.

20. a control piston shaft of the control piston at least partially disposed within a piston bore in the atomizer body; Atomization device according to any one of claims 1 to 3, 9, 10, 15 and 16, wherein a dose piston shaft of the dose piston is at least partially disposed within a shaft bore in the control piston shaft.

21. 21. The spray device of claim 20, wherein the piston bore is coaxial with the shaft bore.

22. 21. The spray device of claim 20, wherein at least a portion of the purge air passage is formed within the shaft bore.

23. 21. The spray device of claim 20, wherein a retention groove is formed in a surface of the control piston shaft that defines the shaft bore, the retention groove being fluidly connected to a solvent source.

24. Further, a conveying groove is formed on the outer side of the dose piston shaft, 24. The spray device of claim 23, wherein the transfer groove is fluidly connected to the retaining groove when the spray device is in the spray mode, and the transfer groove is fluidly disconnected from the retaining groove when the spray device is in the purge mode.

25. 25. The spray device of claim 24, wherein the conveying groove is axially arranged between a first dosing seal carried by the dose piston shaft and a second dosing seal carried by the dose piston shaft.

26. 26. The spray device according to claim 25, wherein the conveying groove is axially arranged between a third dosing seal supported by the dose piston shaft and the second dosing seal.

27. the second dosing seal sealingly engages the surface of the control piston shaft when the dose piston is in the second dose position; the first dosing seal is disengaged from the surface of the control piston shaft when the dose piston is in the second dose position; the second dosing seal is disengaged from the surface of the control piston shaft when the dose piston is in the first dose position; 26. The atomizer of claim 25, wherein the first dosing seal sealingly engages the surface of the control piston shaft when the dose piston is in the first dose position.

28. the control piston is configured to move a first distance relative to the sprayer housing between the first control position and the second control position; the dose piston is configured to move a second distance relative to the atomizer housing between the first dose position and the second dose position; The spray device of any one of claims 1 to 3, 9, 10, 15 and 16, wherein the first distance is greater than the second distance.

29. 30. The spray device of claim 28, wherein the dose piston is configured to move a third distance relative to the control piston between the first dose position and the second dose position, the third distance being less than the first distance and greater than the second distance.

30. further comprising a spray lock associated with the control piston, the spray lock being actuable between a locked state and an unlocked state, wherein in the locked state the spray lock holds the control piston in a first control position, and in the unlocked state the control piston is movable to the second control position; The spray device according to any one of claims 1 to 3, 9, 10, 15 and 16, wherein the dose piston is movable between the first dose position and the second dose position when the spray lock is in a locked state.

31. 17. The spraying device of any one of claims 1-3, 9, 10, 15 and 16, further comprising a trigger carried by the sprayer body, the trigger operatively connected to an air control valve to direct pressurized air to actuate the control piston.

32. The spray device of any one of claims 1-3, 9, 10, 15 and 16, further comprising a handle extending from the sprayer body.

33. a control piston operatively connected to the spray valve for actuating the spray device between a spray state and a purge state, wherein spray material is discharged from a spray orifice when the spray device is in the spray state, and purge air is discharged from the spray orifice when the spray device is in the purge state; a dose piston carried by the control piston and operable between a first dose position and a second dose position, the dose piston configured to pick up a volume of solvent at the second dose position and the dose piston configured to dispense the volume of solvent into purge air at the first dose position; Equipped with The atomizer, wherein the dose piston moves along an actuation axis in an opposite direction from the spray piston when the atomizer transitions between the spray state and the purge state.

34. 34. The spray device of claim 33, wherein the dose piston is actuable relative to the control piston along the actuation axis independent of the control piston shifting along the actuation axis.

35. 35. The spray device of claim 33, wherein when the spray device is actuated from the spray state to the purge state, the dose piston shifts a first distance along the actuation axis relative to the control piston and the dose piston shifts a second distance along the actuation axis relative to the sprayer body in which the control piston is disposed, the first distance being greater than the second distance.

36. A spraying method comprising: placing a spray applicator in a spray mode, wherein a first material passage and a second material passage are fluidly connected to a mixing chamber when the spray applicator is in the spray mode; Discharging a multi-component material formed by a first base component material and a second base component material into the mixing chamber with the spray applicator, the first base component material being supplied to the mixing chamber through the first material passage and the second base component material being supplied to the mixing chamber through the second material passage; actuating a control piston in a first axial direction along an actuation axis to fluidly isolate the first material passage and the second material passage from the mixing chamber and to fluidly connect a purge air passage to the mixing chamber, thereby placing the spray applicator in a purge mode; actuating a dose piston in a second axial direction along an actuation axis to entrain a dose of solvent picked up from a location within the control piston into a purge air stream flowing axially through the dose piston and the control piston and carried by the purge air stream to the mixing chamber; wherein the second axial direction is opposite to the first axial direction.

37. 1. A dose piston for dispensing a solvent into a purge air passage of a multiple component atomizer, comprising: a dose piston head; a dose piston shaft extending from the dose piston head along an axis; a purge air hole formed in the dose piston head and the dose piston shaft, the purge air hole being configured to direct purge air from a purge hole inlet formed in the dose piston head to a purge hole outlet formed in the dose piston shaft; Equipped with The dose piston shaft, wherein the purge hole outlet is formed in a radially outer surface of the dose piston shaft.

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