CN120152791A - Solvent metering and metering pistons for sprayers - Google Patents

Abstract

A sprayer is operable in a spraying state during which the sprayer sprays multi-component material formed within a mixing chamber of the sprayer and a purging state during which the sprayer sprays compressed air from the mixing chamber as purge air. The control piston controls actuation of the injection device between an injection state and a purge state. The dosing piston is configured to dose volumes of solvent into the flow of purge air for portability to the mixing chamber. The dosing piston slides within the control piston and moves in an opposite axial direction to the control piston.

Description

Solvent metering and feeding piston for sprayer

Cross Reference to Related Applications

The present application claims priority from U.S. provisional application serial No. 63/422,505, filed on 4/11/2022, entitled "SOLVENT DOSING AND DOSE PISTON FOR A SPRAY APPLICATOR (solvent metering and metering piston for sprayer"), the disclosure of which is hereby incorporated by reference in its entirety.

Technical Field

The present disclosure relates generally to fluid ejectors. More particularly, the present disclosure relates to multi-component sprayers.

Background

Two-component sprayers are used to be configured to produce and apply coatings to a substrate, such as spray foam insulation and elastomeric coatings. A spray foam insulation material is applied to the substrate to provide an insulating effect against the environment. An elastomeric coating is applied to the substrate to protect a surface, such as a spray truck bed liner. For two-component spraying, two or more base components are mixed within the sprayer to initiate a chemical reaction that forms a two-component material from the base component material. The two-component ejector may eject purge air through the mixing region and the ejector orifice to purge the rapidly solidifying multicomponent material from the ejector to prevent clogging.

Disclosure of Invention

According to one aspect of the disclosure, an injection device includes an injector body, a mixing chamber supported by the injector body, a purge air path extending to an air inlet of the mixing chamber to provide purge air to the mixing chamber, a control piston disposed at least partially within the injector body, and a metering piston disposed at least partially within the injector body. The control piston is actuatable along the axis between a first control position associated with a purge mode in which the control piston fluidly disconnects the component flow path from the mixing chamber and a second control position associated with an injection mode in which the control piston fluidly connects the component flow path to the mixing chamber. The dosing piston is actuatable between a first dosing position associated with ejecting the purge air from the mixing chamber and a second dosing position associated with ejecting the multi-component material from the mixing chamber, the dosing piston being configured to provide solvent to the purge air path when in the second dosing position, the dosing piston being fluidly connected to the solvent passageway when in the reset position. The control piston is displaced in a first axial direction along the axis from a first control position to a second control position, the control piston is displaced in a second axial direction opposite the first axial direction from the second control position to the first control position, the dosing piston is displaced in the first axial direction from the second dosing position to the first dosing position, and the dosing piston is displaced in the second axial direction from the first dosing position to the second dosing position.

According to another aspect of the invention, an injection device includes a control piston operatively connected to an injection valve such that the injection device is actuated between an injection state and a purge state, wherein injection material is ejected from an injection orifice when the injection device is in the injection state and purge air is ejected from the injection orifice when the injection device is in the purge state, and a dosing piston carried by the control piston and actuatable between a first dosing position and a second dosing position, wherein the dosing piston is configured to draw a volume of solvent in the second dosing position and the dosing piston is configured to dose the volume of solvent into the purge air in the first dosing position, wherein the dosing piston moves in an opposite direction to the injection piston along an actuation axis when the injection device is switched between the injection state and the purge state.

According to yet another aspect of the invention, a spray method includes placing a sprayer in a spray mode, wherein with the sprayer in the spray mode, a first material path and a second material path are fluidly connected to a mixing chamber, spraying a multi-component material formed within the mixing chamber through the sprayer, the multi-component material being composed of a first base component material provided to the mixing chamber through the first material path and a second base component material provided to the mixing chamber through the second material path, actuating a control piston in a first axial direction along an actuation axis to fluidly disconnect the first material path and the second material path from the mixing chamber and fluidly connect a purge air path to the mixing chamber, thereby placing the sprayer in the purge mode, and actuating a dosing piston in a second axial direction along the actuation axis to clamp a dose of solvent drawn from a position within the control piston into a purge air flow flowing axially through the dosing piston and the control piston to be carried by the purge air flow to the mixing chamber, the second axial direction being opposite to the first axial direction.

According to yet another aspect of the present invention, a dosing piston for dosing solvent into a purge air path of a multicomponent injector includes a dosing piston head, a dosing piston shaft extending from the dosing piston head along an axis, and a purge air orifice formed within the dosing piston head and the dosing piston shaft, the purge air orifice configured to route purge air from a purge orifice inlet formed in the dosing piston head to a purge orifice outlet formed in the dosing piston shaft, wherein the purge orifice outlet is formed in a radially outer surface of the dosing piston shaft.

Drawings

FIG. 1A is a schematic block diagram of an injection system.

FIG. 1B is a schematic block diagram of the spray system of FIG. 1A showing the flow path through the sprayer.

Fig. 2A is an isometric view of the sprayer.

Fig. 2B is an isometric exploded view of the sprayer.

Fig. 3A is an enlarged cross-sectional view of a portion of the sprayer, showing the sprayer in a purged state.

Fig. 3B is an enlarged cross-sectional view of a portion of the sprayer shown in fig. 3A, showing the sprayer in a spray condition.

FIG. 4A is an enlarged cross-sectional view of a portion of the sprayer taken along line 4-4 in FIG. 2A, showing the sprayer in a purged state.

Fig. 4B is an enlarged cross-sectional view of a portion of the sprayer shown in fig. 4A, showing the sprayer in a first, converted state.

Fig. 4C is an enlarged cross-sectional view of a portion of the sprayer shown in fig. 4A, showing the sprayer in a spray condition.

FIG. 5A is an enlarged cross-sectional view of a portion of the sprayer taken along line 5-5 of FIG. 2A showing the sprayer in a spray condition.

Fig. 5B is an enlarged cross-sectional view of a portion of the sprayer shown in fig. 5A, showing the sprayer in a second transition state.

Fig. 5C is an enlarged cross-sectional view of the sprayer section shown in fig. 5A, showing the sprayer in a purged state.

Fig. 6 is an enlarged isometric cross-sectional view taken along line 4-4 in fig. 2A.

Fig. 7 is a cross-sectional view of the dosing piston.

Detailed Description

The present disclosure relates to a sprayer for applying a multi-component material to a substrate. The sprayer includes a mixing chamber configured to receive different streams of first and second base component materials that are mixed together to form a multi-component material. The sprayer ejects the combined multi-component material from the mixing chamber in an ejection mode and ejects purge air from the mixing chamber in a purge mode. First and second purge air streams are provided to the mixing chamber to purge material residues in the mixing chamber. Solvent is injected into the flow of purge air upstream of the mixing chamber to be carried by the purge air to the mixing chamber. The solvent helps to clean the multi-component material out of the mixing chamber and remove residue from the multi-component material. The dosing piston controls the dosing of solvent in the purge air stream. The dosing piston is retained by a drive piston which controls movement of a valve member which controls injection by the injector. The dosing piston is disconnected from the drive piston such that the dosing piston can move relative to the drive piston.

Fig. 1A is a schematic block diagram of an injection system 10. FIG. 1B is a schematic block diagram of spray system 10 showing the flow path through sprayer 12. Fig. 1A and 1B will be discussed together. The spray system 10 includes a sprayer 12, material supplies 14a and 14b, pumps 16a and 16b, and an air supply 18. The sprayer 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 sprayer 12 also includes a material path 34a, a material path 34B, a solvent path 36, and an air path 38. The air path 38 includes a common passage 40, a first passage 42, and a second passage 44.

The spray system 10 is a system for generating and applying a spray of material to a substrate. In some examples, spray system 10 is configured to combine two or more base component materials to produce a multi-component material for application to a substrate. In some examples, the spray system 10 is configured to produce and apply a spray foam insulation or elastomeric coating to a substrate, as well as other spray options.

The material supplies 14a and 14b are used to store a supply of base component material prior to spraying. The multi-component material is formed by mixing the base component materials within the mixing chamber 30, such as a spray foam or elastomeric coating. The spray foam insulation is discussed herein as an example, but it should be understood that the present disclosure is not limited to spray foam applications. For example, fluid supply 14a may store a first base component material, such as a resin, and fluid supply 14b may store a second base component material, such as a catalyst. In some examples, a first one of the base component materials may be a polyol resin and a second one of the base component materials may be an isocyanate. The first base component material and the second base component material are combined at the sprayer 12 (e.g., within the mixing chamber 30) and emitted from the sprayer 12 in the form of a spray of the multi-component material. The sprayer 12 produces a spray of the multi-component material and applies the multi-component material to a substrate. The sprayer 12 may also be referred to as a mixer, mixing manifold, dispenser, and/or spray gun, among other options.

The pump 16a is configured to draw the first base component material from the fluid supply 14a and deliver it downstream to the sprayer 12. The pump 16b is configured to draw the second base component material from the fluid supply 14b and deliver it downstream to the sprayer 12. Pumps 16a and 16b may be controlled by a system controller (not shown). The first base component material flows through a material path 34a in the sprayer 12. The second base component material flows through a material path 34b in the sprayer 12. The first base component material is fluidly isolated from the second base component material at a location upstream of the mixing chamber 30.

An air supply 18 is connected to the sprayer 12 and is configured to provide a flow of compressed air to the sprayer 12. The air supply 18 may take any suitable configuration for providing compressed air to the sprayer 12. For example, air supply 18 may be a compressor, a pressurized tank, or any other suitable configuration that provides a pressurized flow of air. The air supply 18 provides pressurized air to a pneumatic path through the sprayer 12 that is at least partially made up of an air path 38 through the sprayer 12.

Pressurized air is initially provided to the common passage 40. The first and second passages 42, 44 are configured to provide separate pressurized flow of purge air to the mixing chamber 30. The first passageway 42 is configured to provide a first portion of pressurized purge air to the mixing chamber 30 through the same port in the mixing chamber 30 that the material path 34a provides the first base component material. The second passage 44 is configured to provide a second portion of the pressurized purge air to the mixing chamber 30 through the same port in the mixing chamber 30 that provides the second base component material as the material path 34 b. Purge air flows through the mixing chamber 30 to draw material within the mixing chamber 30 and blow the material out of the mixing chamber 30. The purge air thereby prevents undesirable curing of the materials within the mixing chamber 30.

The sprayer 12 is configured to produce and apply a multi-component material. The body 20 of the sprayer 12 supports other components of the sprayer 12. The control assembly 24 is at least partially disposed within the sprayer 12. The control assembly 24 is configured to control whether the first base component material and the second base component material flow to the mixing chamber 30 or whether the first purge air and the second purge air flow to the mixing chamber 30. The control assembly 24 allows the first component material and the second component material to flow to the mixing chamber 30 when the sprayer 12 is in the spray mode. The control assembly 24 allows purge air to flow to the mixing chamber 30 with the sprayer 12 in a purge mode.

The control valve 26 is at least partially disposed within the sprayer 12. The control valve 26 is operatively connected to the control assembly 24 to actuate the control assembly 24 between a spray mode and a purge mode, as will be discussed in more detail below. Control valve 26 is configured to direct pressurized air to control actuation of a piston of control assembly 24, as will be discussed in more detail below.

The mixing chamber 30 is disposed at the downstream ends of the material paths 34a, 34b, the first channel 42 and the second channel 44. The mixing chamber 30 has injection orifices 32 formed therein. With the sprayer 12 in the spray mode, the mixing chamber 30 receives the first and second base component materials from the material paths 34a, 34b, the base materials interact within the bore 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. With the sprayer 12 in the purge mode, the mixing chamber 30 receives the first and second purge air streams and ejects the purge air through the spray orifice 32. The purge air is configured to purge residues from within the mixing chamber 30 to prevent solidification of the multi-component material within the mixing chamber 30 and to prevent clogging of the spray orifices 32.

A trigger 22 is attached to the sprayer 12 and is used to control the spray from the sprayer 12. The trigger 22 is configured to be actuated to switch between an injection mode (during which a two-component material is formed and ejected) and a purge mode (during which purge air is ejected). The user may actuate trigger 22 to displace injection valve 24 to an injection state, thereby fluidly connecting material paths 34a, 34b with mixing chamber 30 and fluidly disconnecting first and second passages 42, 44 from mixing chamber 30. The base component materials combine within the mixing chamber 30 to form a two-component material that is ejected from the ejection orifice 32.

The user releases trigger 22 to displace injection valve 24 to the purge state, thereby fluidly disconnecting material paths 34a, 34b from mixing chamber 30 and fluidly connecting first and second passages 42, 44 with mixing chamber 30. The purge air partially flows through the first and second passages 42, 44 into the mixing chamber 30 and out of the injection orifices 32. It will be appreciated that the trigger 22 may take any configuration suitable for activating and deactivating the spray from the sprayer 12. While the sprayer 12 is described as a manual spray gun configured to be held and manipulated by a user, it is understood that other examples of the sprayer 12 may be automatic such that the sprayer 12 does not include a manually actuated trigger 22 or handle.

The solvent reservoir 27 stores solvent that is intermittently supplied to the mixing chamber 30 throughout the operation. The solvent assists in cleaning the mixing chamber 30 using the sprayer 12 in the purge mode. For example, the solvent may slow the reaction process to inhibit curing and may dissolve the uncured multicomponent material. The solvent reservoir 27 may be provided within the sprayer 12, for example, within the handle of the sprayer 12. The solvent reservoir 27 contains a solvent. In some examples, the solvent reservoir 27 may be formed as a cartridge that may be removed and replaced as a single unit. The solvent path 36 extends downstream from the solvent reservoir 27 to an air path 38. In the example shown, the solvent path 36 extends to the second channel 44. The solvent path 36 may be considered to extend to the mixing chamber 30 such that a portion of the second channel 44 defines both the air path 38 and the solvent path 36.

In some examples, the configuration of the sprayer 12 is such that solvent is supplied to the mixing chamber 30 via the second channel 44 instead of the first channel 42. Supplying solvent only through the second channel 44 prevents mixing of the solvent with the base component material provided through the material path 34a at a location upstream of the mixing chamber 30. For example, material path 34b may be configured to provide a resin base component material to mixing chamber 30, while material path 34a may be configured to provide an isocyanate base component material. Isocyanates are moisture sensitive and cure when contacted by liquids (e.g., solvents). The cured isocyanate may form crystals that may cause scratches or other damage to the soft seal and blockage of the path of the sprayer 12. Solvent is flowed into the mixing chamber 30 through the same port as the resin, preventing the solvent and isocyanate from mixing in the sprayer 12 at a location upstream of the mixing chamber 30. However, it is understood that not all examples are limited to supplying solvent through a single air channel. For example, some examples of the sprayer 12 may include a solvent path 36, the solvent path 36 intersecting the air path 38 at a location upstream of the intersection of the first and second channels 42, 44 such that solvent passes through both the first and second channels 42, 44.

During operation, a user actuates the trigger 22 to transition the sprayer 12 between the spray mode and the purge mode. The trigger 22 is operably associated with a control valve 26 to cause the sprayer 12 to spray by actuating the control valve 26. In some examples, the control valve 26 directs compressed air from the air supply 18 to the control assembly 24, thereby driving the control assembly 24 to transition between positions associated with the injection mode and the purge mode. For example, control valve 26 may direct compressed air through a first internal path within sprayer 12 to displace control piston 84 of control assembly 24 and to displace control piston 84 from a respective first position associated with the injection mode to a respective second position associated with the purge mode. Control valve 26 may then be shifted in position (e.g., due to a user releasing trigger 22) to direct compressed air through a second internal path within sprayer 12 to move control piston 84 and metering piston 86 of control assembly 24 from the respective second positions to the respective first positions.

The sprayer 12 is initially in the purge mode such that the first and second passages 42, 44 are fluidly connected with the mixing chamber 30 and the sprayer 12 emits purge air through the spray orifice 32. The user actuates trigger 22 to transition injection valve assembly 24 to the first position associated with the injection mode. With injection valve assembly 24 in the first position, material paths 34a, 34b are fluidly connected to mixing chamber 30, while first and second passages 42, 44 are fluidly disconnected from mixing chamber 30. The first base component material and the second base component material flow into the mixing chamber 30 and mix within the mixing chamber 30 to form a multi-component material. The multi-component material is ejected from the ejection orifice 32.

Injection valve 24 is maintained in the injection state until the user releases trigger 22. Upon release of trigger 22, control valve 26 is displaced to direct pressurized air to injection valve assembly 24 to displace injection valve assembly 24 to a second position associated with the purge mode. With injection valve assembly 24 in the second position, material paths 34a and 34b are fluidly disconnected from mixing chamber 30, and air path 38 is fluidly connected with mixing chamber 30. More specifically, each of the first and second channels 42, 44 is in fluid connection with the mixing chamber 30. Pressurized air flows from the first and second passages 42, 44 into the mixing chamber 30 and is ejected through the ejection orifice 32. The second purge air portion carries solvent from the solvent reservoir 27 to the mixing chamber 30. The solvent may dissolve any multi-component material within the mixing chamber 30 to prevent hardening and clogging thereof. In some examples, solvent is provided only through the second channel 44 to prevent the solvent from contacting the first base component material provided through the material path 34a at a location upstream of the mixing chamber 30.

Fig. 2A is an isometric view of sprayer 12. Fig. 2B is an isometric exploded view of the sprayer 12. Fig. 2A and 2B will be discussed together. The sprayer 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 cap 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. The shuttles 62a and 62b of the control assembly 24 are shown. The material manifold 50 includes a base component inlet 64a and a base component inlet 64b.

The body 20 supports other components of the sprayer 12. The body 20 may be formed as a unitary component, or as multiple components that are secured together. In the example shown, a support housing 54 supports and at least partially encloses components of injection valve 24 and control valve 26. The fluid cartridge 56 can be removably mounted to the support housing 54. A handle 60 extends from the support housing 54. A user may grasp handle 60 to manipulate and orient sprayer 12. In some examples, the handle 60 may house other components of the sprayer 12, such as the solvent cartridge 28. An exhaust port may be formed through handle 60 to exhaust air from injection valve 24. The trigger 22 is supported by the body 20 and is connected to the body 20. More specifically, in the example shown, the trigger 22 is connected to the support housing 54. The trigger 22 is configured to control the spray of the sprayer 12.

The control assembly 24 is supported by the sprayer 12. In the example shown, the control assembly 24 is at least partially disposed within the support housing 54. The control assembly 24 includes shuttles 62a, 62b, the shuttles 62a, 62b projecting from the support housing 54 and into the fluid cartridge 56. In the illustrated example, the shuttles 62a, 62b constitute the flow control members of the sprayer 12. The shuttles 62a, 62b are configured to be axially displaced relative to the injection axis SA to transition the sprayer 12 between the injection mode and the purge mode. The injection axis SA may be coaxial with the actuation axis A-A (FIGS. 4A through 5C).

The fluid cartridge 56 can be mounted to the support housing 54. The fluid cartridge 56 may be connected to the support housing 54 in any desired manner. For example, the fluid cartridge 56 may be coupled to the support housing 54 by mating threads, among other options.

The cover 48 extends at least partially around the fluid cartridge 56. In the example shown, the cover 48 covers the interface between the fluid cartridge 56 and the support housing 54. The cover 48 may be coupled to the support housing 54 and/or the fluid cartridge 56. A retaining cap 58 is attached to the fluid cartridge 56. The retaining cap 58 is configured to secure internal components within the sprayer 12, such as by securing the mixing chamber 30 within the cavity 68. However, it will be appreciated that the mixing chamber 30 may be secured to the body 20 in any suitable manner.

The material manifold 50 is mountable to the sprayer 12 and is configured to provide a first base component material and a second base component material to the fluid cartridge 56. The material manifold 50 is mounted to the support housing 54 by fasteners 69, but it will be appreciated that other connection types are possible. Base component inlet 64a is a fitting configured to connect to a hose or other fluid line to receive a first base component material from a first material source, such as fluid supply 14a (fig. 1A and 1B). Base component inlet 64B is a fitting configured to connect to a hose or other fluid line to receive a second base component material from a second material source, such as fluid supply 14B (fig. 1A and 1B).

An air receiver 52 is mounted to the sprayer 12 and provides a location for compressed air to enter the sprayer 12. In the example shown, the air receiver 52 is mounted at the rear end of the support housing 54, while the fluid cartridge 56 is mounted at the front end of the support housing 54. The air receiver 52 is an accessory configured to be connected to a hose, pipe, tube, or other air line to receive pressurized air from an air source, such as the air supply 18 (fig. 1A and 1B).

The solvent cartridge 28 can be mounted to the sprayer 12. In the example shown, the solvent cartridge 28 forms a solvent reservoir 27 of the sprayer 12. In the illustrated example, the solvent cartridge 28 is configured to be mounted within the handle 60.

In operation, a first base component material is provided to the sprayer 12 through the base component inlet 64a, a second base component material is provided to the sprayer 12 through the base component inlet 64b, and compressed air is provided to the sprayer 12 through the air receiver 52. Injection valve 24 controls the flow of base component material and compressed purge air to mixing chamber 30. Trigger 22 controls actuation of control assembly 24 to place sprayer 12 in a spray condition and a purge condition. With the control assembly 24 in the first position associated with the spray pattern, the first base component material and the second base component material flow into and mix within the mixing chamber 30, and the resulting multi-component material is sprayed through the spray orifice 32. When the sprayer 12 is in the spray condition, the shuttles 62a and 62b block the flow of purge air into the mixing chamber 30. With the control assembly 24 in the second position associated with the purge mode, a portion of the purge air flows into and mixes in the mixing chamber 30, and the resulting combination of air and solvent is ejected through the ejection orifice 32. The shuttles 62a, 62b prevent the first and second base component materials from flowing into the mixing chamber 30 when the sprayer 12 is in the purge mode with the sprayer 12 in the purge mode.

Fig. 3A is an enlarged cross-sectional view of a portion of sprayer 12 in a purged state. Fig. 3B is an enlarged cross-sectional view of a portion of the sprayer 12 shown in fig. 3A in a spray condition. Fig. 3A and 3B are discussed together. The body 20, mixing chamber 30, spray orifice 32, cap 48, and seal cartridges 66a, 66b of the sprayer 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. Mixing chamber 30 includes injection orifice 32, air inlets 68a, 68b, and mixing holes 70.

The sprayer 12 is configured to receive separate streams of the first base component material BCMa and the second base component material BCMb and to spray out a multi-component material PCM formed by mixing the first and second base component materials within the mixing chamber 30. The body 20 supports other components of the sprayer 12.

The shuttles 62a, 62b are operatively connected to a control piston 84 (fig. 3A-5) of the control assembly 24 for movement by the control piston 84. The control piston 84 and shuttles 62a, 62b may be considered to form the control assembly 24. In some examples, the shuttles 62a, 62b are generally in the position shown in fig. 3A such that the sprayer 12 is in a purge mode and emits purge air. The shuttles 62a, 62B are displaced in the first axial direction AD1 to the position shown in FIG. 3B to place the sprayer 12 in the spray mode. The shuttles 62a, 62b are displaced in the second axial direction AD2 to the position shown in FIG. 3A to reset the sprayer 12 in the purge mode.

Seal cartridges 66a, 66b are disposed within fluid bores 72a, 72b, respectively. Fluid apertures 72a, 72b are formed in the fluid barrel 56. The heads 74a, 74b of the shuttles 62a, 62b interface with the seal cartridges 66a, 66b, respectively, to control the flow of the base component material and purge air to the mixing chamber 30. The mixing chamber 30 is disposed within the cavity 68. The air inlets 68a, 68b extend through the mixing chamber 30 to the mixing holes 70. The mixing bore 70 may be disposed coaxially with the injection axis SA. The mixing bore 70 extends to the injection orifice 32.

During operation, the sprayer 12 is placed in an injection mode to generate and spray the multi-component material PCM from the injection orifice 32, and the sprayer 12 is placed in a purge mode to spray the compressed air CA from the injection orifice 32 as purge air. To place sprayer 12 in the spray mode, the user depresses trigger 22, thereby causing control valve 26 to route drive air to the chamber in which the head of control piston 84 is located. The drive air applies a force to control piston 84 to move the moving part of control assembly 24 in first axial direction AD1 and to the position shown in FIG. 3B.

With the shuttles 62a, 62B in the positions associated with the injection conditions shown in fig. 3B, the heads 74a, 74B of the shuttles 62a, 62B are disposed on the first axial sides of the air inlets 68a, 68B and are in sealing engagement with the seal barrels 66a, 66B. For example, the heads 74a, 74b may interface directly with the body of the seal cartridge 66a, 66b, or with seals (e.g., elastomeric sealing members, such as o-rings) supported by the seal cartridge 66a, 66b or the heads 74a, 74 b. The interface between the heads 74a, 74b and the seal cartridges 66a, 66b fluidly isolates 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 examples, the second purge air portion is formed by the portion of the drive air that drives the displacement of the control piston 84, as discussed in more detail below. With the sprayer 12 in the purge mode, the second purge air portion is prevented from downstream flow out of the mixing chamber in which the head of the control piston 84 is disposed. Thus, while the head 74b of the shuttle 62b is positioned to inhibit the flow of purge air, the portion of the second channel 44 adjacent the head 74b may be free of purge air when the sprayer 12 is in the spray mode.

The first base component material flows through the seal cartridge 66a and into the mixing chamber 30 through the air inlet 68 a. The second base component material flows through the seal cartridge 66b and into the mixing chamber 30 through the air inlet 68 b. The first base component material and the second base component material interact within the mixing bore 70 to form a two-component material that is ejected through the ejection orifice 32.

The sprayer 12 is deactivated (e.g., the user releases the trigger 22) to transition the sprayer 12 from the spray mode to the purge mode shown in fig. 3A. Control valve 26 displaces position to direct drive air into the chamber in which the head of control piston 84 is disposed, but on the opposite side of the head of control piston 84, i.e., the side opposite the air that displaces control piston 84 to the injection mode. The drive air applies a force to the control piston 84 to move the moving parts of the control assembly 24 in the second axial direction AD2, thereby causing the sprayer 12 to enter the purge mode.

With the shuttles 62a, 62b in the position shown in fig. 3A, the heads 74a, 74b are disposed on the second axial side (opposite the first axial side) of the air inlets 68a, 68b and are in sealing engagement with the seal barrels 66a, 66 b. For example, the heads 74a, 74b may interface directly with the body of the seal cartridge 66a, 66b, or with a sealing member (e.g., an elastomeric sealing member, such as an o-ring) supported by the seal cartridge 66a, 66b or by the heads 74a, 74 b. 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 into the mixing chamber 30 through the air inlet 68 a. A second portion of the pneumatic purge air (including entrained solvent SV) flows through the seal cartridge 66b and into the mixing chamber 30 through the air inlet 68 b. The first portion of pneumatic purge air and the second portion of pneumatic purge air interact within the mixing bore 70 and are ejected through the ejection orifice 32.

Both the first base component material and the first purge air portion flow through the common portion of the seal cartridge 66a and the air inlet 68a. Thus, the seal cartridge 66a and the air inlet 68a define portions of both the material path 34a (fig. 1B) and the first channel 42 (fig. 1B). Both the second base component material and the second purge air portion flow through the common portion of the seal cartridge 66b and the air inlet 68b. Thus, the seal cartridge 66B and the air inlet 68B define portions of both the material path 34B (fig. 1B) and the second channel 44 (fig. 1B).

In the example shown, the solvent is carried by the second purge air portion to the mixing chamber 30. The first purge air portion is fluidly isolated from the solvent at a location upstream of the mixing chamber 30. In the illustrated example, the sources of the first and second purge air portions are from the same compressed air supply upstream of the sprayer 12 (e.g., from the air supply 18), and from the same supply path within the sprayer 12 (e.g., the common passage 40 (fig. 1B)). The pneumatic pressure across the first and second purge air portions is balanced such that the first purge air portion is prevented from crossing and flowing through the inlet 68b and such that the second purge air portion is prevented from crossing and flowing through the inlet 68a. The equalized pressure prevents solvent carried by the second purge air portion from flowing toward the inlet 68a and upstream of the inlet 68a, such as into the seal cartridge 66a or other portions of the material path 34a or the first passageway 42.

Fig. 4A is an enlarged cross-sectional view of a portion of the sprayer 12 taken along line 4-4 of fig. 2A, showing the sprayer 12 in a purged state. Fig. 4B is an enlarged cross-sectional view of a portion of the sprayer 12 shown in fig. 4A, showing the sprayer 12 in a first, converted state. Fig. 4C is an enlarged cross-sectional view of a portion of the sprayer 12 shown in fig. 4A, showing the sprayer 12 in a spray condition. Fig. 5A is an enlarged cross-sectional view of a portion of sprayer 12 taken along line 5-5 of fig. 2A, showing sprayer 12 in a spray condition. Fig. 5B is an enlarged cross-sectional view of a portion of the sprayer 12 shown in fig. 5A, showing the sprayer 12 in a second, transitional state. Fig. 5C is an enlarged cross-sectional view of a portion of the sprayer 12 shown in fig. 5A, showing the sprayer 12 in a purged state. Fig. 4A to 5C will be discussed together.

The body 20 of the sprayer 12, the control piston 84, the dosing piston 86, and the spray lock 88 are shown. The support housing 54, piston bore 82 and supply slot 90 of the body 20 are shown. A second passage 44 of the air path 38 is also shown.

Control piston head 92, control piston shaft 94, and shaft seals 96a, 96b of control piston 84 are shown. The control piston head 92 includes an axial side 98a, an axial side 98b, a metering head chamber 100, and displacement passages 102a, 102b. The control piston shaft 94 includes a shaft bore 104, a solvent tank 106, a solvent passage 108, a holding tank 110, and a metering tank 112. Metering piston head 114, metering piston shaft 116, purge air bore 118, head seal 120, and metering seals 122 a-122 c of metering piston 86 are shown. Dosing piston shaft 116 includes a bearing groove 124.

The control piston 84 and dosing piston 86 are coaxially disposed on the actuation axis A-A. The control piston 84 is configured to reciprocate between a first control position associated with the purge air ejection and a second control position associated with the multi-component material ejection. Dosing piston 86 is configured to reciprocate between a first dosing position associated with dosing solvent into the purge air and a second dosing position associated with drawing solvent from solvent path 36. Dosing piston 86 moves relative to control piston 84 between a first dosing position and a second dosing position. Control piston 84 is shown in a first control position in fig. 4A, 4B, and 5C. Control piston 84 is shown in a second control position in fig. 4C, 5A, 5B. The dosing piston 86 is shown in the first dosing position in fig. 4A, 5B, 5C. The dosing piston 86 is shown in the second dosing position in fig. 4B, 4C, 5A.

Control piston 84 is configured to control the spray from sprayer 12. Control piston 84 may form a component of injector 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 injection mode (second position shown in fig. 3B). The control piston 84 is coupled to the shuttles 62a, 62B (as shown in fig. 3A and 3B) to axially move the shuttles 62a, 62B to actuate the sprayer 12 to switch between the spray mode and the purge mode. In some examples, the control piston 84 is directly connected to the shuttles 62a, 62b. The body 20 at least partially defines a drive chamber 76. The body 20 defines various ones of the flow paths that form the air path 38 of the sprayer 12. The body 20 defines various ones of the flow paths of the solvent path 36 of the sprayer 12.

The drive chamber 76 is at least partially formed in the body 20. Inlet passages 78a, 78b are formed in the body 20. The inlet passages 78a, 78b allow compressed air to enter the drive chamber 76. The inlet passages 78a, 78b are provided on opposite axial sides of the control piston head 92. The inlet passage 78a is associated with a first subchamber 80 of the drive chamber 76, the first subchamber 80a being defined in part by an axial side 98a of the control piston 84. The inlet passage 78b is associated with a second subchamber 80b of the drive chamber 76, the second subchamber 80b being defined in part by an axial side 98b of the control piston 84. The control piston 84 may interface 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 A-A. A piston bore 82 is formed in the body 20. A control piston 84 is at least partially disposed within the piston bore 82. The control piston 84 may interface 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 A-A.

A control piston head 92 is disposed within the drive chamber 76. The control piston head 92 divides the drive chamber 76 into a subchamber 80a and a separate subchamber 80b. Subchambers 80a and 80b are fluidly isolated from each other by control piston head 92. The drive chamber 76 defines a range of axial displacement of the control piston 84. The drive chamber 76 defines an axial travel of the control piston 84 relative to the body 20. Control piston 84 may travel within axial range R1. Between the injection and purge conditions, the travel length of control piston 84 may be L1.

The axial side 98a of the control piston head 92 is oriented in the second axial direction AD2 and the axial side 98b of the control piston head 92 is oriented in 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. Axial sides 98a and 98b are exposed to compressed air within subchambers 80a and 80b, respectively, such that the compressed air acts on axial sides 98a or 98b to drive the displacement of control piston 84. The compressed air provided to subchamber 80a acts on axial side 98a to move control piston 84 in first axial direction AD1. The compressed air provided to subchamber 80b acts on axial side 98b to displace control piston 84 in second axial direction AD 2.

A metering head chamber 100 is formed within the control piston head 92. The dosing piston head 114 is disposed within and retained within the dosing head chamber 100. The dosing head chamber 100 defines the axial displacement range of the dosing piston 86. Dosing head chamber 100 defines the axial distance dosing piston 86 may travel relative to control piston 84. Dosing piston 86 travels within axial range R2. Dosing piston 86 may travel a length L2 between the injection state and the purge state.

Displacement passages 102a, 102b are formed through the control piston head 92 and extend to the metering head chamber 100. The displacement channels 102a, 102b are flow channels configured to provide compressed air to the metering head chamber 100. The compressed air provided to the dosing head chamber 100 is configured to actuate the dosing piston 86 along an actuation axis A-A.

The displacement passage 102a includes an inlet through the axial side 98a of the control piston head 92 and an outlet to the metering head chamber 100. The displacement channel 102a is fluidly connected to the subchamber 80a and meters into the head chamber 100. The displacement channel 102a is configured to receive air at a first axial side of the dosing piston head 114 and output air into the dosing head chamber 100 at a second axial side of the dosing piston head 114. The displacement channel 102a extends axially around the metering head seal 120 to introduce compressed air into the metering head chamber 100, the metering head chamber 100 being on an opposite side of the metering head seal 120 from which the displacement channel 102a receives air. The compressed air supplied to the dosing head chamber 100 through the displacement channel 102a is configured to move the dosing piston 86 in the second axial direction AD 2. The displacement channels 102a provide flow paths through the control piston head 92 that allow compressed air to enter the dosing head chamber 100 on the axial side of the dosing piston head 114 oriented in the first axial direction AD 1. The displacement channel 102a is configured to introduce compressed air into the dosing head chamber 100 to drive the dosing piston 86 in the second axial direction AD2 from the first dosing position to the second dosing position. The displacement channel 102a comprises an inlet oriented in the axial direction (in the example shown, the second axial direction AD 2), and an outlet oriented radially into the metering head chamber 100. The displacement channel 102a redirects the flow direction of the compressed air so that the compressed air is radially output to the metering head chamber 100.

The displacement passage 102b includes an inlet through the axial side 98b of the control piston head 92 and an outlet to the metering head chamber 100. The displacement channel 102b is fluidly connected to the subchamber 80b and metered into the head chamber 100. The displacement channel 102b is configured to receive air on a second axial side of the dosing piston head 114 and output air into the dosing head chamber 100 on a first axial side of the dosing piston head 114. The displacement channel 102b extends axially around the metering head seal 120 to introduce compressed air into the metering head chamber 100, the metering head chamber 100 being on the opposite side of the displacement channel 102b from the side of the metering head seal 120 that receives air. The compressed air supplied to the dosing head chamber 100 through the displacement channel 102b is configured to move the dosing piston 86 in the first axial direction AD 1. The displacement channels 102a provide flow paths through the control piston head 92 that allow compressed air to enter the dosing head chamber 100 on the axial side of the dosing piston head 114 oriented in the second axial direction AD 2. The displacement channel 102b is configured to introduce compressed air into the dosing head chamber 100 to drive the dosing piston 86 in the second axial direction AD2 from the second dosing position to the first dosing position. The compressed air provided through the displacement passage 102b may form at least a portion of the purge air of the sprayer 12. Compressed air provided through displacement channel 102b may flow through purge air orifice 118 metered into piston 86 and downstream to entrain solvent and carry it to mixing chamber 30.

The supply slot 90 extends into the main body 20. A supply slot 90 extends radially outwardly from the piston bore 82 relative to the actuation axis A-A. The supply slot 90 may extend completely around the actuation axis A-A. The supply groove 90 may be formed as an annular groove. In the example shown, the supply tank 90 is formed as a ring for holding a volume of solvent. The supply tank 90 forms part of a solvent circuit and is fluidly connected to a solvent source (e.g., solvent cartridge 28). In the example shown, the supply tank 90 is fluidly connected to a solvent source throughout operation. With control piston 84 extending into piston bore 82, supply tank 90 may be considered to form a solvent supply chamber that provides solvent for entrainment in the purge air.

A control piston shaft 94 extends from the control piston head 92. The control piston shaft 94 extends into a piston bore 82 formed in the body 20. The control piston shaft 94 extends from the control piston head 92 in the first axial direction AD 1. The control piston shaft 94 may be cylindrical and the piston bore 82 may be cylindrical. Shaft seals 96a and 96b are provided on the control piston shaft 94. Throughout operation, the shaft seal 96a and the shaft seal 96b are disposed on opposite axial sides of a solvent tank 106 formed in the body 20. As control piston 84 reciprocates within piston bore 82, shaft seal 96a and shaft seal 96b engage and sealingly engage body 20 throughout the operation. The shaft seals 96a and 96b prevent solvent from leaking axially beyond either shaft seal 96a, 96b between the control piston shaft 94 and the body 20. In the illustrated example, each shaft seal 96a, 96b is disposed within a seal groove formed on an outer radial surface of the control piston shaft 94. The shaft seals 96a, 96b may take any suitable configuration for providing a fluid seal between the control piston shaft 94 and the body 20, such as elastomeric seals. For example, the shaft seals 96a, 96b may be formed as o-rings, among other options. In the example shown, the shaft seals 96a, 96b are formed as dynamic seals that slide axially relative to the body 20 when the sprayer 12 is actuated between the spray and purge conditions.

A solvent groove 106 is formed on an outer radial surface of the control piston shaft 94. A solvent tank 106 is axially disposed between the shaft seals 96a, 96 b. The solvent groove 106 is axially disposed between the seal grooves holding the shaft seals 96a, 96 b. The solvent groove 106 is formed as a depression on the outer surface of the control piston shaft 94. The solvent tank 106 may extend annularly. The solvent tank 106 may extend completely around the control piston shaft 94. The solvent tank 106 may extend completely circumferentially about the actuation axis A-A. The solvent tank 106 is configured to hold a volume of solvent between the body 20 and the control piston shaft 94 for rapid supply to the holding tank 110.

In the example shown, the body 20 partially defines a solvent chamber. The solvent chamber is formed by the body 20 and the control piston 84. The solvent chamber includes a supply tank 90, a solvent tank 106, and an axial passage therebetween. The length of the axial passage varies throughout operation as the control piston 84 reciprocates relative to the body 20. The supply tank 90 may also be referred to as a body tank. Solvent tank 106 may also be referred to as a piston tank.

A solvent passage 108 extends through the body of control piston 84 between a retaining groove 110 and the exterior of control piston 84. In the example shown, the solvent channel 108 extends radially between the solvent tank 106 and the holding tank 110. An outer radial opening of the solvent passage 108 is formed through an 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 an inner radial surface of the control piston shaft 94. The inner radial opening may also be referred to as a solvent outlet. In the example shown, the solvent outlet is formed in the holding tank 110. The solvent passages 108 form flow paths that allow 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 channel 108 forms a flow path for the solvent to flow between the solvent tank 106 and the holding tank 110.

The control piston shaft 94 has a retaining groove 110 formed therein. The retaining groove 110 extends radially outwardly from the shaft bore 104 relative to the actuation axis AA. The retaining groove 110 may extend completely around the actuation axis AA. The holding groove 110 may be formed as an annular groove. In the example shown, the holding groove 110 is formed as a ring for holding a volume of solvent. The holding tank 110 forms part of the solvent path 36 and is fluidly connected to a solvent source (e.g., the solvent cartridge 28). The holding tank 110 may be fluidly connected to the solvent reservoir 27 throughout operation of the sprayer 12. The solvent reservoir 27 may be pressurized such that the pressurized solvent is fluidly connected to the supply tank 90, the solvent tank 106, the solvent channel 108, and the holding tank 110 throughout operation.

Metering piston 86 is at least partially disposed within control piston 84. In the example shown, the dosing piston 86 is disposed entirely within the control piston 84. In the example shown, metering piston 86 does not extend axially outward from control piston 84. Metering piston 86 is supported by control piston 84. Dosing piston 86 is movable relative to control piston 84. Thus, control piston 84 may be considered to carry metering piston 86, but is not connected to metering piston 86.

A dosing piston head 114 is disposed within the dosing head chamber 100. A dosing piston shaft 116 extends from the dosing piston head 114. The dosing piston shaft 116 extends into the shaft bore 104 formed in the control piston 84. Dosing piston shaft 116 is configured to slide axially within shaft bore 104 relative to control piston 84. In some examples, the shaft bore 104 may extend entirely axially through the control piston shaft 94. The dosing piston shaft 116 extends from the dosing piston head 114 in the first axial direction AD 1. Thus, the dosing piston shaft 116 and the control piston shaft 94 extend in the same axial direction from the dosing piston head 114 and the control piston head 92, respectively. The dosing piston shaft 116 slides within the shaft bore 104 but is not fixed to the shaft bore 104 to allow the dosing piston shaft 116 to move relative to the control piston shaft 94. The dosing piston 86 may interface with the control piston shaft 94 within the shaft bore 104 such that the shaft bore 104 is aligned with the dosing piston 86 for movement along the actuation axis A-A.

Metering seals 122a-122c are disposed on metering piston shaft 116. Metering seals 122a-122c are disposed radially between metering piston shaft 116 and control piston shaft 94. Metering seals 122a-122c engage an inner radial surface of control piston shaft 94 defining shaft bore 104 to prevent axial leakage of solvent between metering piston 86 and control piston 84. In the example shown, each metering seal 122a-122c is disposed within a seal groove formed on an outer radial surface of metering piston shaft 116. Metering seals 122a-122c may take any suitable configuration for fluid-tight sealing between metering piston shaft 116 and control piston shaft 94, such as elastomeric seals. For example, the dosing seals 122a-122c may be formed as o-rings, among other options. In the example shown, metering seals 122a-122c are formed as dynamic seals that slide axially relative to control piston 84 as metering piston 86 is actuated along axis A-A and moves relative to control piston 84.

Metering seal 122a is disposed at a first axial position of metering piston shaft 116. The dosing seal AD is disposed at a second axial position of the dosing piston shaft 116. Metering seal 122c is disposed at a third axial position of metering piston shaft 116. The first position is axially disposed between the dosing piston head 114 and the second axial position. The metering seal 122a is positioned such that the metering seal 122a is located on a first axial side of the retention groove 110 throughout operation. The metering seal 122a is positioned such that the metering seal 122a contacts and seals against the control piston shaft 94 throughout operation, as discussed in more detail below.

Metering seal 122b is axially located between metering seal 122a and metering seal 122 c. Metering seal 122b may be considered an intermediate seal of metering seals 122 a-122 c, while metering seals 122a, 122c form end seals of metering seals 122 a-122 c. Metering seal 122b is configured to contact control piston shaft 94 during the portion of the reciprocating motion of metering piston 86. Metering seal 122b is configured to interface with a portion of control piston shaft 94 disposed on an axially opposite side of retaining groove 110 from metering seal 122 a. With the sprayer 12 in the purge mode, the metering seal 122b interfaces with the control piston shaft 94. Metering seal 122b, which interfaces with control piston shaft 94, fluidly isolates holding tank 110 from metering tank 112. When metering seal 122b is engaged with control piston shaft 94, metering seal 122b thereby fluidly isolates solvent path 36 from air path 38. Metering seal 122b engages a portion of control piston shaft 94 that is spaced apart from retaining groove 110 in first axial direction AD 1.

Throughout this operation, the metering seal 122b does not interface with the control piston shaft 94. Metering seal 122b is disengaged from control piston shaft 94 and is disposed in radial overlap with retaining groove 110 such that a radial line extending from actuation axis A-A extends through both metering seal 122b and retaining groove 110 with sprayer 12 in the spray condition. Metering seal 122b, which is disengaged from control piston shaft 94, fluidly connects retaining groove 110 with carrier groove 124. Metering seal 122b, which is disengaged from control piston shaft 94, fluidly connects carrier groove 124 with solvent path 36 so that solvent may flow into and into carrier groove 124.

Metering seal 122c is located at an end of metering piston shaft 116 opposite metering piston head 114. Metering seal 122c forms a distal seal for metering piston 86. Metering seal 122c is spaced apart from metering seal 122a and metering seal 122b in first axial direction AD 1. Metering seal 122c is disposed on an axial side of carrier groove 124 opposite metering seal 122 b. Metering seal 122c is configured to interface with a portion of control piston shaft 94 (located on an axial side of retaining groove 110 opposite metering piston head 114). Metering seal 122c may interface with the same portion of control piston shaft 94 as metering seal 122 b. With the sprayer 12 in the spray mode, the metering seal 122c interfaces with the control piston shaft 94. Metering seal 122c, which interfaces with control piston shaft 94, fluidly isolates holding tank 110 from metering tank 112. Metering seal 122c thereby fluidly isolates solvent path 36 from air path 38.

Throughout this operation, metering seal 122c does not interface with control piston 84. With the sprayer 12 in the purge mode, the metering seal 122c is disengaged from the control piston shaft 94 and disposed within the metering slot 112. Metering seal 122c, which is disengaged from control piston shaft 94, fluidly connects carrier groove 124 with metering groove 112. The metering seal 122c, which is disengaged from the control piston shaft 94, fluidly connects the carrier groove 124 with the air path 38 such that solvent can flow to and be entrained in the purge air flowing through the air path 38.

Metering seals 122 a-122 c are configured to fluidly isolate holding tank 110 from the pneumatic path of sprayer 12. The dosing seal 122a maintains contact with the control piston shaft 94 throughout operation to prevent solvent flow in the second axial direction AD2 between the control piston shaft 94 and the dosing piston shaft 116. One or both of the dosing seals 122b, 122c are engaged with the control piston shaft 94 throughout operation.

Throughout operation, metering tank 112 is fluidly isolated from holding tank 110. In the example shown, metering slot 112 is fluidly isolated from retaining slot 110 by a dynamic sealing interface between metering piston 86 and control piston 84. This dynamic sealing interface fluidly isolates the air path 38 and the solvent path 36 of the sprayer 12. Specifically, metering slot 112 is fluidly isolated from holding slot 110 by metering seals 122b, 122 c. The dosing seals 122b, 122c are positioned along the dosing piston shaft 116 such that at least one of the dosing seals 122b, 122c is in contact with the control piston shaft 94 throughout operation. The dynamic sealing interface prevents solvent flow in the first axial direction AD1 between the control piston shaft 94 and the dosing piston shaft 116. When dosing piston 86 is displaced in first axial direction AD1, dosing seal 122b engages control piston shaft 94 before dosing seal 122c disengages control piston shaft 94. When dosing piston 86 is displaced in second axial direction AD2, dosing seal 122c engages control piston shaft 94 before dosing seal 122b disengages control piston shaft 94.

A bearing groove 124 is formed in the dosing piston 86. Specifically, the bearing groove 124 is formed on the dosing piston shaft 116. The bearing groove 124 extends radially inward into the metering piston shaft 116. The bearing groove 124 is formed as a recess that meters into the piston shaft 116. The carrier groove 124 is axially disposed between the dosing seal 122b and the dosing seal 122 c. The bearing groove 124 may be considered to be axially supported by the metering seals 122b, 122 c. The carrier groove 124 may be formed as an annular groove around the dosing piston shaft 116. The bearing groove 124 may extend completely around the actuation axis A-A. The carrier tank 124 is configured to draw a dose volume of solvent from the holding tank 110 and transfer the solvent to the metering tank 112. The solvent is then entrained within the purge air flowing through the air path 38 (e.g., entrained in the second purge air portion passing through the second passage 44) and carried by the purge air to the mixing chamber 30.

The purge air bore 118 extends axially within the metering piston 86. In the example shown, the purge air bore 118 extends completely axially through the dosing piston 86. The purge air bore 118 extends axially between a purge bore inlet 126 and a purge bore outlet 128. The purge air holes 118 define a purge passage through which the purge air entrains solvent and carries it to the mixing chamber 30, which is metered into the piston 86. A purge orifice inlet 126 is formed in the metering piston head 114. The purge hole inlet 126 is axially oriented in the second axial direction AD 2. A purge orifice outlet 128 is formed in the metering piston shaft 116. The purge hole outlet 128 is axially oriented in a first axial direction AD 1. The purge air holes 118 form part of the air path 38 of the sprayer 12. Purge air aperture 118 is in fluid communication with displacement channel 102b and, thus, subchamber 80 b. The purge air aperture 118 is configured to receive compressed air from the subchamber 80b, and the compressed air flows through the purge air aperture 118 and out into the axial bore 104 through the purge aperture outlet 128.

In the illustrated example, the purge air aperture 118 is comprised of a series of apertures that gradually decrease in diameter as the purge air aperture 118 extends in the first axial direction AD 1. In the example shown, the purge hole inlet 126 is larger in diameter than the purge hole outlet 128. The reduced diameter of the purge air holes 118 increases the velocity of the purge air flowing through the purge air holes 118. The purge orifice outlet 128 increases in diameter and opens into the larger diameter axial bore 104, specifically into the portion of the axial bore 104 formed for metering into the slot 112. In some examples, the purge air outlet 128 forms a valve seat of the air flow control valve, such as a valve seat on which a valve ball seats, to prevent backflow through the purge air bore 118. The purge orifice outlet 128, which opens into the larger diameter shaft bore 104, promotes turbulence, thereby entraining solvent in the purge air.

Injection lock 88 interfaces with control piston 84. Spray lock 88 is actuatable between an unlocked state and a locked state (as shown in fig. 5C). With the spray lock 88 in the unlocked state, the control piston 84 is able to reciprocate along the actuation axis A-A, thereby switching the shuttles 62a and 62b and placing the sprayer 12 in the purge state. With injection lock 88 in the locked state, control piston 84 is maintained in a first control position associated with the purge state. With injection lock 88 in the locked state, control piston 84 is prevented from being displaced in first axial direction AD 1. Spray lock 88 maintains control piston 84 in the first control position to prevent a user from inadvertently actuating sprayer 12 to a spray condition and causing the multi-component material to be sprayed. The spray lock 88 thus forms a safety device that prevents actuation to a spray condition even when a pneumatic supply is connected to the sprayer 12 and activated to provide compressed air to the sprayer 12.

The locking knob 130 is connected to the receiver 132 such that the locking knob 130 can rotate the receiver 132 about the locking axis. In the example shown, the locking axis is arranged coaxially with the actuation axis A-A. In the illustrated example, each of injection lock 88, control piston 84, and metering piston 86 are coaxially aligned with actuation axis A-A. The retainer 134 is connected to the control piston 84. In the example shown, the retainers 134 are partially disposed within a cavity formed in the control piston head 92 of the control piston 84. The retainers 134 extend axially outwardly from the axial side 98a of the control piston head 92. A pneumatic seal is formed between retainer 134 and control piston 84, such as by an elastomeric seal disposed radially between retainer 134 and control piston head 92. The retainers 134 may at least partially define the dosing head chamber 100. The retainers 134 may be secured to the control piston 84 in any desired manner, such as by rings or clips that snap into grooves in the control piston 84.

The retainers 134 interface with the receivers 132. In the illustrated example, the retainer shaft 136 extends into the receiver bore 138. The stem 140 interfaces with the receptacle 132 within one or more slots of the receptacle 132. The rod 140 extends through the retainer shaft 136. With the spray lock 88 in the unlocked state, the retainer 134 may be axially movable relative to the receiver 132. With the spray lock 88 in the locked condition, the retainer 134 is prevented from moving axially relative to the receiver 132. Rotating the locking knob 130 moves the rod 140 within the slot of the receiver 132, thereby pulling the control piston 84 to the first control position. In the example shown, locking knob 130 rotates receiver 132, receiver 132 pulls retainer 134 in second axial direction AD2 via rod 140, and retainer 134 pulls control piston 84 in second axial direction AD2 to the first control position.

While injection lock 88 may secure control piston 84 in a position associated with a purge condition, injection lock 88 may not be able to fixedly meter into piston 86. When control piston 84 is fixed in the first control position, dosing piston 86 is free to reciprocate relative to control piston 84 along actuation axis A-A. The injection lock 88 does not interface with the dosing piston 86. The retainer 134 is not connected to the dosing piston 86. In some examples, the retainers 134 define the extent of axial movement of the dosing piston 86, but the retainers 134 do lock the position of the dosing piston 86 relative to the control piston 84.

Dosing piston 86 is movable relative to control piston 84, allowing dosing piston 86 to actuate between a first dosing position and a second dosing position, while control piston 84 remains stationary. Thus, the user need not actuate the sprayer 12 to the spray condition, and only trigger and deactivate the sprayer 12 to meter solvent into the purge air.

During operation, the sprayer 12 is initially in a purge state with the control piston 84 in the first control position and the dosing piston 86 in the first dosing position. The initial state of the sprayer 12 is shown in fig. 4A and 5C. The shuttles 62a, 62b may be directly connected to the control piston head 92 (e.g., by interfacing threads therebetween) and positioned to fluidly connect the purge air path with the mixing chamber 30. Purge air flows through the mixing chamber 30 and is ejected through the ejection orifice 32. Compressed air is initially directed to subchamber 80b to bias control piston 84 in second axial direction AD 2. The compressed air acts on the axial side 98b of the control piston head 92 and exerts a driving force on the control piston head 92 in the first axial direction AD 2. The compressed air may maintain the control piston 84 in the first control position. A portion of this compressed air flows through the inlet passage 78b and into the metering head chamber 100.

A portion of the compressed air entering subchamber 80b flows to and through displacement passages 102b formed in control piston head 92. Compressed air flows through the displacement channel 102b to the dosing head chamber 100 and applies a force to the dosing piston head 114. The compressed air biases the dosing piston 86 in the first axial direction AD1, thereby driving the dosing piston 86 to and maintaining the first dosing position. The displacement channels 102b provide flow paths through the control piston head 92 that allow compressed air to enter the dosing head chamber 100 on the axial side of the dosing piston head 114 oriented in the second axial direction AD 2. With the sprayer 12 in the purged state, compressed air acts on opposite axial sides of the control piston 84 and metering 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 metering piston 86 oriented in the second axial direction AD 2. With the sprayer 12 in the purged state, the compressed air biases the control piston 84 in the second axial direction AD2 and biases the metering piston 86 in the first axial direction AD 1.

The compressed air flows from a first axial side of the drive head seal 120 to a second opposite axial side of the drive head seal 120. With the sprayer 12 in the purged state, the compressed air flows on opposite axial sides of the drive head seal 120. Compressed air flows within control piston 84 and on opposite axial sides of drive head seal 120.

The compressed air biases the dosing piston 86 in the first axial direction AD1 and flows through the purge air bore 118 via the dosing piston 86. The compressed air flowing through the metering piston 86 forms at least a portion of the purge air flowing to the mixing chamber 30. In some examples, the compressed air flowing through the metering piston 86 forms at least a portion of the second purge air portion. In some examples, all of the purge air is metered into the purge air orifice 118 in the piston 86. The compressed air flows downstream through the metering piston 86 and the shaft bore 104 and ultimately to the mixing chamber 30. A purge valve may be provided in the pneumatic path between the dosing piston 86 and the mixing chamber 30 to prevent back flow of purge air to the dosing piston 86. The purge valve maintains pneumatic pressure in the downstream portion of the pneumatic path to provide a rapid reaction and flow of purge air to and through the mixing chamber 30 when the sprayer 12 is actuated to the purge state.

The user actuates the trigger 22 to cause the sprayer 12 to spray. Fig. 4A-4C illustrate the control piston 84 and dosing piston 86 being displaced from a position associated with the purge mode to a position associated with the injection mode. The initial positions of control piston 84 and dosing piston 86 are shown in fig. 4A. Control piston 84 is in the first control position and dosing piston 86 is in the first dosing position. User actuation of trigger 22 displaces control valve 26 to direct compressed air to inlet passage 78a and to cease compressed air flow to inlet passage 78b. The control valve 26 fluidly connects the inlet passage 78b to the exhaust of the sprayer 12. Compressed air enters subchamber 80a through inlet passage 78a and acts on axial side 98a of control piston head 92 and biases control piston 84 in first axial direction AD 1. The compressed air displaces the control piston 84 in the first axial direction AD1 and displaces the dosing piston 86 in the second axial direction AD 2. A portion of the compressed air flowing into the subchamber 80a flows through the displacement passages 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 metering head chamber 100. Compressed air enters the dosing head chamber 100 and biases the dosing piston 86 in the second axial direction AD 2. The displacement channels 102a provide flow paths through the control piston head 92 that allow compressed air to enter the dosing head chamber 100 on the axial side of the dosing piston head 114 oriented in the first axial direction AD 1. The compressed air flows within control piston 84 and toward retaining groove 110. With the sprayer 12 in and switched to the spray condition, the compressed air acts on opposite axial sides of the control piston 84 and metering 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 metering piston 86 oriented in the first axial direction AD 1.

Fig. 4B shows the injector in a first switching state. For ease of illustration, FIG. 4B shows metering piston 86 and control piston 84 in positions associated with opposite states. It will be appreciated that during operation, compressed air acts on both the control piston 84 and the dosing piston 86. Thus, while metering piston 86 and control piston 84 are shown in the positions associated with opposite states (control piston 84 in the first control position and metering piston 86 in the second metering position) in FIG. 4B, it is understood that metering piston 86 and control piston 84 move together between these states.

The control piston 84 moves in the first axial direction AD1 to displace the shuttles 62a, 62b and fluidly connect the base component material stream with the mixing chamber 30. The compressed air also moves the dosing piston 86 relative to the control piston 84. When the control piston 84 is displaced in the first axial direction AD1, the dosing piston 86 is displaced in the second axial direction AD 2. When the sprayer 12 is switched to the spraying state, the dosing piston 86 moves in an opposite axial direction to the control piston 84.

In the example shown, dosing piston 86 moves relative to control piston 84 and in an opposite direction from control piston 84, but dosing piston 86 moves relative to body 20 of sprayer 12 in the same axial direction as control piston 84 as sprayer 12 transitions between the spray and purge conditions. For example, length L1 (which is the displacement distance of control piston 84 relative to body 20) is greater than length L2 (which is the displacement distance of metering piston 86 relative to control piston 84) such that control piston 84 is displaced a greater axial distance along actuation axis A-A than metering piston 86. Thus, dosing piston 86 is displaced relative to body 20 in axial direction AD1 between a first dosing position and a second dosing position, while dosing piston 86 is moved relative to control piston 84 in an opposite second axial direction AD 2.

Dosing piston 86 is displaced in a second axial direction AD2 relative to control piston 84 such that dosing seal 122b is disengaged from control piston 84 and dosing seal 122c is engaged with control piston 84. The bearing groove 124 is fluidly connected to the holding groove 110. The solvent flows into and into the carrying tank 124.

The sprayer 12 is shown in the spray position in fig. 4C. The compressed air biases the control piston 84 in the first axial direction AD1 and biases the dosing piston 86 in the second axial direction AD 2. The metering head seal 120 fluidly isolates the compressed air provided through the displacement channel 102a from the purge air bore 118 through the metering piston 86. The dosing head seal 120 separates the dosing head chamber 100 into a dosing chamber 101b and a reset chamber 101a. Air supplied to the reset chamber 101a drives the dosing piston 86 in the second axial direction AD2 to fluidly connect the bearing groove 124 with the holding groove 110. The air supplied to the dosing chamber 101b drives the dosing piston 86 in the first axial direction AD1 to fluidly connect the carrier groove 124 with the dosing groove 112. The same air flow metered into the piston 86 is driven in the first axial direction AD1 through the purge air path defined by the purge air aperture 118, thereby entraining solvent. Thus, the same air that drives the dosing piston 86 may also draw in solvent and carry it to the mixing chamber 30 to flush the mixing chamber 30.

To stop spraying, the user releases the trigger 22. Upon release of the trigger 22, the sprayer 12 is actuated to a purge state. Fig. 5A-5C illustrate the process of controlling piston 84 and dosing piston 86 to shift from a position associated with the injection mode to a position associated with the purge mode. Control piston 84 and dosing piston 86 are initially in the positions shown in fig. 5A. Control piston 84 is in the second control position and dosing piston 86 is in the second dosing position. Releasing the trigger 22 allows the control valve 26 to shift state such that the control valve 26 directs compressed air to the inlet passage 78b and fluidly connects the inlet passage 78a with the exhaust of the sprayer 12. The compressed air flows into subchamber 80b through inlet aperture 78 b. The compressed air flowing through the intake port 78b acts on the axial side 98b of the control piston head 92 to bias the control piston 84 in the second axial direction AD 2. The compressed air displaces the control piston 84 in the second axial direction AD2 to displace the control piston 84 from the second control position shown in fig. 5A to the first control position shown in fig. 5C.

The compressed air provided to subchamber 80b flows through displacement passage 102b and toward metering head chamber 100. The compressed air flowing through the displacement channel 102b acts on the dosing piston head 114 to bias the dosing piston 86 in the first axial direction AD 1. The compressed air displaces the dosing piston 86 relative to the control piston 84. When control piston 84 is displaced in second axial direction AD2, dosing piston 86 is displaced in first axial direction AD 1. When the sprayer 12 transitions from the purge state to the spray state, the dosing piston 86 moves in an opposite axial direction from the control piston 84.

In the example shown, dosing piston 86 moves relative to control piston 84 and in a direction opposite control piston 84, but dosing piston 86 is displaced relative to body 20 in the same axial direction as control piston 84.

Fig. 5B shows the sprayer 12 in a second transition state. It will be appreciated that during operation, compressed air acts on both the control piston 84 and the dosing piston 86. Thus, while metering piston 86 and control piston 84 are shown in FIG. 5B in positions associated with opposite states, it is understood that metering piston 86 and control piston 84 are actuated together between these states. For ease of illustration, FIG. 3B shows metering piston 86 and control piston 84 in positions associated with opposite states. Metering piston 86 is in a first metering position associated with the purge air injection and control piston 84 is in a second control position associated with the multicomponent material injection. The compressed air continues to act on control piston 84 and dosing piston 86 to drive control piston 84 and dosing piston 86 to the position shown in fig. 5C.

Compressed air flowing through displacement channel 102b and into metering head chamber 100 is fluidly connected to purge air bore 118 by metering piston 86. A portion of this compressed air flows through the purge air holes 118 and is ejected through the purge hole outlets 128 and into the shaft bore 104. The compressed air flows downstream through the shaft bore 104 and, in some examples, through a flow path in the body 20 to the mixing chamber 30 for ejection as purge air.

Dosing piston 86 is displaced in first axial direction AD1 such that dosing seal 122b is engaged with control piston 84 and dosing seal 122c is disengaged from control piston 84. The carrier groove 124 is fluidly connected to the dosing groove 112 and fluidly disconnected from the holding groove 110. The carrier groove 124 is fluidly connected to the flow of purge air through the metering piston 86 and the axial bore 104. The carrier slot 124 carries a dose volume of solvent within the carrier slot 124 and between the holding slot 110 and the dosing slot 112. The solvent within the carrying tank 124 is entrained in the air flow passing through the purge air holes 118 and the shaft bore 104 and carried downstream by the purge air to the mixing chamber 30.

The control piston 84 moves in the second axial direction AD2 and is displaced to the first control position. The shuttles 62a, 62b are driven in the second axial direction AD2 to fluidly disconnect the flow of component material from the mixing chamber 30 and to fluidly connect the flow of purge air with the mixing chamber 30. The compressed air drives the displacement of the control piston 84 and the dosing piston 86 such that not only the control piston 84 is placed in the first control position but also the dosing piston 86 is placed in the first dosing position, as shown in fig. 5C.

As described above, injection lock 88 may be placed in a locked state to maintain control piston 84 in the first control position. With the control piston 84 locked in the first control position, the dosing piston 86 may still be actuated to dose volumes of solvent into the mixing chamber 30, thereby facilitating thorough cleaning of the mixing chamber 30.

With control piston 84 locked in the first position, sprayer 12 may be triggered to cause actuation between the states shown in fig. 4B and 5C. Control piston 84 is maintained in the first control position. The trigger 22 is pulled to route compressed air through the air inlet aperture 78a to the subchamber 80a. The compressed air flows through the displacement channel 102a and drives the dosing piston 86 in the second axial direction AD2 into the second dosing position. Injection lock 88 prevents axial movement of control piston 84. With metering piston 86 in the second metering position, carrier groove 124 is fluidly connected to holding groove 110 to receive solvent.

Deactivating the sprayer 12 stops the supply of compressed air to the subchamber 80a and, conversely, directs the compressed air to the subchamber 80b. Compressed air enters the subchamber through the inlet holes 78 b. A portion of the compressed air flows through the displacement channel 102b and toward the metering head chamber 100. The compressed air drives the dosing piston 86 in the first axial direction AD1 into the first dosing position. The carrier groove 124 is fluidly isolated from the holding groove 110 and fluidly connected to the dosing groove 112 and to a portion of the shaft bore 104 downstream of the dosing piston. Compressed air from the metering head chamber 100 flows through the purge air orifice 118 and downstream to entrain the solvent dose and carry it to the mixing chamber. The user may continue to trigger and deactivate the sprayer 12 to provide additional doses of solvent downstream to the mixing chamber 30 to clean the mixing chamber 30.

The sprayer 12 has significant advantages. The metering piston 86 provides discrete doses of solvent for entrainment in the purge air and transfer to the mixing chamber 30. Metering piston 86 is carried by and slides within control piston 84, reducing the size of body 20 as compared to a configuration in which metering piston 86 and control piston 84 are carried separately. Metering piston 86 is disconnected from control piston 84 such that metering piston 86 may move relative to control piston 84 even when control piston 84 is locked in position relative to body 20. The dosing piston 86 both carries the dose of solvent and defines a purge air orifice 118 through which purge air is delivered, thereby simplifying the configuration of injecting solvent into the purge air stream.

Fig. 6 is an isometric cross-sectional view showing a portion of the sprayer 12. The body 20 of the sprayer 12, the control valve 26, the handle 60, the trigger 22, the air fitting 52, the control piston 84, the dosing piston 86, and the spray lock 88 are shown. The supply slot 90 and piston bore 82 of the body 20 are shown.

Control piston head 92, control piston shaft 94, and shaft seals 96a, 96b of control piston 84 are shown. The control piston head 92 includes an axial side 98a, an axial side 98b, a metering 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 tank 106, a solvent passage 108, a holding tank 110, and a metering tank 112. Metering piston head 114, metering piston shaft 116, purge air bore 118, metering head seal 120, and metering seals 122 a-122 c of metering piston 86 are shown. Dosing piston shaft 116 includes a bearing groove 124.

Control piston 84 is configured to reciprocate along actuation axis A-A between a first control position associated with the purge air spray and a second control position associated with the multi-component material spray. Control piston 84 is shown in the second control position in fig. 6. Dosing piston 86 is configured to reciprocate between a first dosing position associated with dosing solvent into the purge air and a second dosing position associated with drawing solvent from solvent path 36. The dosing piston 86 is shown in a second dosing position in fig. 6. Dosing piston 86 moves relative to control piston 84 between a first dosing position and a second dosing position.

Control piston 84 is configured to reciprocate along actuation axis A-A between a first control position and a second control position. As shown, the control piston head 92 includes a cylindrical outer surface disposed within the cylindrical surface of the body 20 defining the drive chamber 76. A control piston shaft 94 extends from the control piston head 92 and into the piston bore 82 in the body 20. In the example shown, 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 A-A.

Metering piston 86 is disposed coaxially with control piston 84 on actuation axis A-A. The dosing piston head 114 is disposed within the dosing slot 112 and is configured to reciprocate within the dosing slot 112. A dosing piston shaft 116 extends axially from the dosing piston head 114. The dosing piston shaft 116 extends into and reciprocates within the shaft bore 104 formed in the control piston shaft 94. The dosing piston shaft 116 is arranged coaxially with the control piston shaft 94. Metering piston 86 is disconnected from control piston 84, but is carried by control piston 84 such that metering piston 86 is movable relative to control piston 84.

Fig. 7 is a sectional view of dosing piston 86'. Metering piston 86 'is substantially similar to metering piston 86, except that metering piston 86' is configured to output purge air in a direction away from axis A-A, rather than along axis A-A. Metering piston 86' includes a metering piston head 114, a metering piston shaft 116', a purge air bore 118', and metering seal grooves 123 a-123 c. The dosing piston shaft 116' includes a bearing groove 124. The purge air orifice 118 'includes a purge orifice inlet 126, a purge orifice outlet 128', and an outlet orifice 142.

The dosing piston head 114 is arranged at an axial end of a dosing piston shaft 116'. A dosing piston shaft 116' extends from the dosing piston head 114. Dosing piston shaft 116' is configured to extend into shaft bore 104 formed within control piston 84. Dosing piston shaft 116' is configured to slide axially within shaft bore 104 and relative to control piston 84. The dosing piston shaft 116' extends from the dosing piston head 114 in the first axial direction AD 1. The dosing piston shaft 116 'is configured to slide within the shaft bore 104, but is not fixed to the shaft bore 104, to allow the dosing piston shaft 116' to move relative to the control piston shaft 94. The dosing piston 86 'may interface with the control piston shaft 94 within the shaft bore 104 such that the shaft bore 104 is aligned with the dosing piston 86' for movement along the actuation axis A-A.

Metering seal grooves 123a to 123c are formed on the metering piston shaft 116'. Metering seal grooves 123 a-123 c are configured to receive metering seals 122 a-122 c, respectively. Metering seal grooves 123 a-123 c are arrayed along and about metering piston shaft 116'.

The dosing seal groove 123a is disposed at a first axial groove location on the dosing piston shaft 116'. The dosing seal groove 123b is provided at a second axial groove position on the dosing piston shaft 116'. The dosing seal groove 123c is provided at a third axial groove location on the dosing piston shaft 116'. The first axial slot position is axially disposed between the metering piston head 114 and the second axial slot position. The second axial slot position is axially disposed between the first axial slot position and the third axial slot position.

A bearing groove 124 is formed in the dosing piston 86'. Specifically, the bearing groove 124 is formed on the dosing piston shaft 116'. The carrier groove 124 extends radially inward into the metering piston shaft 116'. The bearing slots 124 do not extend to the purge air holes 118 'or intersect the purge air holes 118'. The bearing groove 124 is formed as a recess that meters into the piston shaft 116'. The carrier groove 124 is axially disposed between the dosing seal groove 123b and the dosing seal groove 123 c. The bearing groove 124 may be considered to be axially supported by the metering seal grooves 123b, 123 c. The carrier groove 124 may be formed as an annular groove extending completely around the dosing piston shaft 116'. The bearing groove 124 may extend completely around the actuation axis A-A. The carrier tank 124 is configured to draw a dose volume of solvent from the holding tank 110 and transfer the solvent to the metering tank 112. The solvent is then entrained in the purge air flowing through the air path 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.

The purge air bore 118 'extends axially within the metering piston 86'. In the example shown, the purge air bore 118 'does not extend entirely axially through the dosing piston 86'. In the example shown, the axial end of the dosing piston shaft 116' opposite the dosing piston head 114 is closed. The purge air holes 118' extend axially between the purge hole inlet 126 and the outlet orifice 142' and radially to the purge air outlet 128'. The purge air holes 118 'define a purge passage through which purge air flows to entrain solvent and carry it to the mixing chamber 30, metered into the piston 86'. A purge orifice inlet 126 is formed in the metering piston head 114. The purge hole inlet 126 is axially oriented in the second axial direction AD 2. A purge orifice outlet 128 'is formed in the metering piston shaft 116'. The purge hole outlet 128' is oriented radially outwardly away from the axis A-A. The purge air holes 118' form part of the air path 38 of the sprayer 12. Purge air aperture 118' is in fluid communication with displacement channel 102b and thus subchamber 80 b. The purge air aperture 118' is configured to receive compressed air from the subchamber 80b, and the compressed air flows through the purge air aperture 118' and out through the purge aperture outlet 128' to the shaft aperture 104.

In the illustrated example, the outlet orifice 142 forms a downstream portion of the purge air bore 118'. The outlet orifice 142 extends away from the axis A-A rather than along the axis A-A. The outlet orifice 142 extends radially outwardly from an axial portion of the purge air bore 118 'to an exterior of the metering piston shaft 116'. The outlet orifice 142 extends between an axial portion of the purge air bore 118 'and the purge air outlet 128'. The outlet orifice 142 extends transversely to the axis A-A. The outlet orifice 142 is configured to direct purge air radially outward of the metering piston shaft 116 'rather than through the axial end of the metering piston shaft 116'.

In the example shown, the outlet orifice 142 is formed as a transverse bore through the metering piston shaft 116'. Two outlet orifices 142 are shown disposed on opposite sides of the axis A-A 180 degrees apart from each other. However, it should be understood that not all examples are so limited. In the example shown, the dosing piston 86 'includes a plurality of purge air outlets 128'. However, it is to be understood that not all examples are so limited. For example, the dosing piston 86' may include a single purge air outlet 128', two purge air outlets 128', three purge air outlets 128', or any number of purge air outlets 128'.

The purge air outlet 128 'is axially disposed between the metering seal slot 123c and an axial end of the metering piston shaft 116' (opposite the metering piston head 114). The purge air outlet 128 'is axially disposed between the bearing groove 124 and an axial end of the dosing piston shaft 116' (opposite the dosing piston head 114). The purge air outlet 128 'is configured to eject purge air having a radial velocity component as the purge air is ejected from the metering piston 86'. Providing a radial velocity component may improve entrainment of solvent in the purge air, thereby improving the effectiveness of purging material from the mixing chamber 30. The purge air may enter the metering tank 112 directly and impinge upon the surfaces defining the metering tank 112 as the purge air is ejected from the purge air outlet 128'. In some examples, the direction of the purge air is orthogonal to the axis A-A. In some examples, the outlet orifice 142 is inclined such that the purge air has both a radial velocity component and an axial velocity component.

In the illustrated example, the purge air bore 118 'is formed from a series of bores that progressively decrease in diameter as the purge air bore 118' extends in the first axial direction AD1 and then radially along the outlet orifice 142 'to the exterior of the dosing piston shaft 116'. In the example shown, the purge hole inlet 126 is larger in diameter than the purge hole outlet 128'. The reduced diameter of the purge air holes 118 'increases the velocity of the purge air flowing through the purge air holes 118'. The purge orifice outlet 128' is radially oriented to encourage purge air to impinge on the interior surface of the control piston shaft 94, which creates turbulence to entrain solvent in the purge air.

While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof 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 intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims (37)

1. A spraying device, comprising: Injector body; a mixing chamber, the mixing chamber being supported by the injector body; a purge air path extending to an air inlet of the mixing chamber to provide purge air to the mixing chamber; A control piston at least partially disposed in the injector body, the control piston being actuatable along an axis between the following positions: a first control position associated with a purge mode in which the control piston fluidly disconnects a component flow path from the mixing chamber; and a second control position associated with a spray mode in which the control piston fluidly connects the component flow path to the mixing chamber; and a metering piston disposed at least partially within the injector body, the metering piston being actuatable between: a first metering position associated with ejecting purge air from the mixing chamber, the metering piston being configured to provide solvent to the purge air path when in a second metering position; and a second metering position associated with ejecting a multi-component material from the mixing chamber, the metering piston being fluidly connected to a solvent passage when in the reset position; wherein the control piston is displaced from the first control position to the second control position in a first axial direction along the axis, the control piston is displaced from the second control position to the first control position in a second axial direction opposite to the first axial direction, the metering piston is displaced from the second metering position to the first metering position in the first axial direction, and the metering piston is displaced from the first metering position to the second metering position in the second axial direction. 2 . The injection device according to claim 1 , wherein the metering piston is arranged at least partially within the control piston. 3 . The injection device according to claim 2 , wherein the metering piston is arranged completely within the control piston. 4 . The injection device according to claim 1 , wherein a metering piston head of the metering piston is arranged within a control piston head of the control piston. 5 . 5. The spray device of any one of claims 1 to 4, wherein the solvent path comprises at least one channel formed in the control piston. 6 . The injection device according to claim 5 , wherein the at least one channel extends through a control piston shaft of the control piston. 7. The injection device according to claim 6, wherein the control piston further comprises: A solvent groove extends into the outer surface of the control piston shaft, wherein the inlet of the at least one passage is at least partially disposed in the solvent groove. 8. The spray device according to claim 7, wherein the solvent groove extends completely annularly around the control piston shaft. 9. The spraying device according to claim 1, wherein: The control piston head of the control piston divides the drive chamber in the injector body into a first sub-chamber and a second sub-chamber; The metering piston head of the metering piston divides the metering head chamber in the injection piston into a metering chamber and a reset chamber; A first displacement channel is formed by the control piston, wherein the first displacement channel is in fluid communication with the first sub-chamber and the reset chamber; A second displacement channel is formed by the control piston, which is in fluid communication with the second subchamber and the metering chamber. 10. The injection device according to claim 9, wherein an inlet of the first displacement channel is formed by a first axial side of the control piston head, and an inlet of the second displacement channel is formed by a second axial side of the injection piston head. 11. The spray device of any one of claims 9 and 10, wherein the metering piston includes a purge passage extending therethrough, the purge passage being in fluid communication with the metering chamber and being configured to form at least a portion of the purge air path. 12. The spray device of claim 11, wherein the purge passage includes an axially oriented purge air outlet. 13. The spray device of claim 11, wherein the purge passage includes a radially oriented purge air outlet. 14. The spray device according to any one of claims 9 to 11 and 13, wherein the metering piston comprises a metering piston shaft extending axially from the metering piston head, and wherein the end of the metering piston shaft opposite to the metering piston head is closed. 15. The spraying device according to claim 1, further comprising: A first displacement channel is formed through the control piston head of the control piston, and the first displacement channel provides 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 metering piston head, the first axial side of the control piston head being oriented in a first axial direction along the axis, and the second axial side of the metering piston head being oriented in a second axial direction along the axis, the first axial direction being opposite to the first axial direction. 16. The spraying device according to claim 15, further comprising: A second displacement channel is formed by the control piston head, and the second displacement channel provides the motive fluid from the chamber on the second axial side of the control piston head to the chamber on the first axial side of the metering piston head, the second axial side of the control piston head is oriented in the second axial direction, and the first axial side of the metering piston head is oriented in the first axial direction. 17. The spray device of any one of claims 1 to 10, 15 and 16, wherein the metering piston includes a purge passage extending therethrough, the purge passage providing purge air to the purge air path. 18. The spray device of claim 17, wherein the purge passage is configured to output the purge air axially. 19. The spray device of claim 17, wherein the purge passage is configured to radially output the purge air. 20. The spraying device according to any one of claims 1 to 5, 9 to 13 and 15 to 19, wherein: A control piston shaft of the control piston is at least partially disposed in a piston bore in the injector body; and The metering piston shaft of the metering piston is arranged at least partially in a shaft bore in the control piston shaft. 21. The spray device of claim 20, wherein the piston bore is coaxial with the shaft bore. 22. The spray device of any one of claims 20 and 21, wherein at least a portion of the purge air path is formed in the shaft bore. 23. The spray device according to any one of claims 20 to 22, wherein a retaining groove is formed in a surface of the control piston shaft defining the shaft hole, the retaining groove being fluidly connected to a solvent source. 24. The spraying device according to claim 23, further comprising: A load bearing groove is formed on the exterior of the metering piston shaft, wherein in the spray mode, the load bearing groove is fluidly connected to the holding groove of the spray device, and in the purge mode, the load bearing groove is fluidly disconnected from the holding groove of the spray device. 25. The spray device of claim 24, wherein the load bearing groove is disposed axially between a first metering seal supported by the metering piston shaft and a second metering seal supported by the metering piston shaft. 26 . The spray device of claim 25 , wherein the load bearing groove is axially disposed between a third metering seal supported by the metering piston shaft and the second metering seal. 27. The spraying device according to claim 25 or 26, wherein: the second metering seal sealingly engaging the surface of the control piston shaft with the metering piston in the second metering position; the first metering seal being disengaged from the surface of the control piston shaft when the metering piston is in the second metering position; the second metering seal disengaging from the surface of the control piston shaft when the metering piston is in the first metering position; and The first dosing seal sealingly engages the surface of the control piston shaft with the dosing piston in the first dosing position. 28. The spraying device according to any one of claims 1 to 27, wherein: the control piston being configured to travel a first distance relative to the injection housing between the first control position and the second control position; The metering piston is configured to travel a second distance relative to the injection housing between the first metering position and the second metering position; and The first distance is greater than the second distance. 29. The spray device of claim 28, wherein the metering piston is configured to travel a third distance relative to the control piston between the first metering position and the second metering position, the third distance being less than the first distance and greater than the second distance. 30. The spraying device according to any one of claims 1 to 29, further comprising: an injection lock docked with the control piston, the injection lock being actuatable between a locked state and an unlocked state, in which the injection lock retains the control piston in the first control position and in which the control piston can move to the second control position; Therein, the metering piston is movable between the first metering position and the second metering position when the injection lock is in the locked state. 31. The spraying device according to any one of claims 1 to 30, further comprising: A trigger is supported by the injector body and operatively connected to an air control valve for directing pressurized air to control actuation of the control piston. 32. The spraying device according to any one of claims 1 to 31, further comprising: A handle extends from the sprayer body. 33. A spraying device comprising: a control piston operatively connected to the injection valve to actuate the injection device between an injection state and a purge state, wherein when the injection device is in the injection state, injection material is ejected from an injection orifice, and when the injection device is in the purge state, purge air is ejected from the injection orifice; and a metering piston carried by the control piston and actuatable between a first metering position and a second metering position, wherein the metering piston is configured to draw up a volume of solvent in the second metering position and the metering piston is configured to meter the volume of solvent into the purge air in the first metering position; Therein, when the injection device is switched between the injection state and the purge state, the metering piston moves along the actuation axis in a direction opposite to the injection piston. 34. The spray device of claim 33, wherein the metering piston is actuatable relative to the control piston along the actuation axis independently of displacement of the control piston along the actuation axis. 35. The injection device according to any one of claims 33 and 34, wherein, when the injection device is actuated from the injection state to the purge state, the metering piston is displaced a first distance along the actuation axis relative to the control piston, the metering piston is displaced a second distance along the actuation axis relative to an injection body in which the control piston is arranged, and the first distance is greater than the second distance. 36. A method of spraying, the method comprising: placing the sprayer in a spray mode, wherein when the sprayer is in the spray mode, a first material path and a second material path are fluidly connected to a mixing chamber; spraying the multi-component material formed in the mixing chamber through the sprayer, the multi-component material being formed by a first base component material supplied to the mixing chamber through the first material path and a second base component material supplied to the mixing chamber through the second material path; actuating a control piston in a first axial direction along an actuation axis to fluidly disconnect the first material path and the second material path from the mixing chamber and fluidly connect a purge air path to the mixing chamber to place the sprayer in a purge mode; and The metering piston is actuated in a second axial direction along the actuation axis to entrain a dose of solvent drawn from a position within the control piston into a purge air flow axially flowing through the metering piston and the control piston to be carried by the purge air flow to the mixing chamber, the second axial direction being opposite to the first axial direction. 37. A metering piston for metering a solvent into a purge air path of a multi-component injector, the metering piston comprising: Metering into the piston head; a metering piston shaft extending along an axis from the metering piston head; and a purge air hole formed in the metering piston head and the metering piston shaft, the purge air hole being configured to route purge air from a purge hole inlet formed in the metering piston head to a purge hole outlet formed in the metering piston shaft, wherein the purge hole outlet is formed on a radially outer surface of the metering piston shaft.