Nozzle assembly for a liquid spray gun

Abstract

Nozzle assembly (20) for a spray gun comprising: a) a tubular nozzle tube (66) having: i) a nozzle tube passage (58) extending between a nozzle tube inlet (57) and a plurality of nozzle tube outlets (52), through which, a liquid (9) exits the nozzle tube passage (58), and ii) a nozzle tube wall (71) extending up to a downstream end (72) and having an outer surface (75), and b) an air cap (40) comprising a nozzle aperture (70) delimited by a nozzle aperture edge (64), the nozzle aperture edge (64) being arranged radially outward the downstream end (72). Between the nozzle aperture edge (64) and the outer surface (75), an atomizing gas outlet (54) is formed circumferentially around the nozzle tube outlets (52), such that, in use, a pressurized atomizing gas (110) exits through the atomizing gas outlet (54) and atomizes the liquid (9) exiting the nozzle tube outlets (52).

Description

[0001] PA101266W003

[0002] NOZZLE ASSEMBLY FOR A LIQUID SPRAY GUN

[0003] Background of the Invention

[0004] This disclosure relates to liquid spray guns in which a liquid to be sprayed is atomized by a 5 pressurized gas. It relates more specifically to nozzle assemblies for use in such spray guns.

[0005] Spray guns according to the present disclosure are used, for example, in many automotive repair shops to apply liquid paint to surfaces of a vehicle using pressurized air or another pressurized gas. Most of these spray guns have a spray gun body or a gun platform with a trigger and a handle for manual spraying operation, while others are used with robots and are equipped with mechanical or electrical interfaces to allow computer-controlled spraying operation by the robot.

[0006] Spray technology and environmental regulations are trending towards spray guns which utilize lower gas pressures or can be laboratory certified to produce certain levels of paint “transfer efficiency”. A 15 challenge with using lower gas pressures is that an amount of energy available to both draw-out and atomize the liquid paint is reduced. This situation can negatively impact an application speed and a paint finish quality. The challenge is compounded by the fact that paint manufacturers are moving to liquid paint formulations which are water-based and have an increased solids content. These liquid paints tend to have higher viscosities which, at identical gas pressure and gas flow rates, can result in reduced paint flow rates 0 and in the liquid paint being more difficult to atomize. A stronger flow of the atomizing gas can provide for a finer atomization that generates a finer paint spray. However, increasing the pressure of the atomizing gas increases a volume of undesirable high-frequency noises, generally results in lower transfer efficiency, increases consumption of pressurized atomizing gas, and also results in higher operating costs.

[0007] 5 Nozzle assemblies are known from traditional liquid paint spray guns. A nozzle assembly generally comprises a nozzle body having a nozzle outlet through which the liquid to be sprayed exits the nozzle body into outside air. The U.S. patent published as US 4,555,059 A describes a specific traditional liquidatomizing nozzle in which intermixing of air and liquid occurs externally of a nozzle. Two versions of the nozzle are disclosed, each having a tubular body with a generally cylindrical section terminating in a 0 conical nose section. Air under pressure is discharged through radial openings in the cylindrical section and is redirected by a collar surrounding the cylindrical section to form a high velocity stream of air about and along a gradually -tapered outer surface of the nose section. Such high velocity air strips liquid from at least one opening in the nose section to produce an externally -developed air-liquid mixture.

[0008] 5 Brief Summary of the Invention

[0009] In order to save energy and paint during spray paint applications, new nozzle assembly designs are needed which can efficiently utilize a motive force of compressed atomizing gas to both draw-out and atomize liquid paint using lower gas pressures or to consume less of the pressurized gas. In an attempt to address these needs, the present disclosure provides a nozzle assembly for a liquid spray gun for spraying a liquid, the nozzle assembly comprising:

[0010] a) a nozzle body including a tubular nozzle tube having:

[0011] i) an elongated nozzle tube passage, extending lengthwise between a nozzle tube inlet through which, in use, exclusively the liquid enters the nozzle tube, and a plurality of nozzle tube outlets arranged in an outlet surface, through which, in use, exclusively the liquid exits the nozzle tube passage into outside air, wherein the plurality of nozzle tube outlets are fluidically connected with the nozzle tube inlet, wherein the length direction of the nozzle tube passage define an axial direction and a radial direction orthogonal to the axial direction, and

[0012] ii) a nozzle tube wall which extends axially forward up to a downstream end, and which has a radially outer surface for guiding a pressurized atomizing gas, and an opposed radially inner surface delimiting the nozzle tube passage and being, in use, in contact with the liquid, and b) an air cap, connected with the nozzle body in a fixed spatial relation, wherein the air cap comprises a front wall which faces generally in a spray direction and comprises a nozzle aperture delimited by a nozzle aperture edge, the nozzle aperture edge being arranged radially outward from the downstream end of the nozzle tube wall,

[0013] wherein between the nozzle aperture edge and the outer surface of the nozzle tube wall, an atomizing gas outlet is formed circumferentially around the plurality of nozzle tube outlets, such that, in use, the pressurized atomizing gas exits into the outside air through the atomizing gas outlet and atomizes the liquid after the liquid has exited the plurality of nozzle tube outlets.

[0014] In the nozzle assembly according to the present disclosure, the nozzle tube has the elongated nozzle tube passage extending between the nozzle tube inlet and the plurality of nozzle tube outlets. In other words, the nozzle tube includes a single nozzle tube inlet and multiple nozzle tube outlets. By splitting an outlet of the nozzle tube into the plurality of nozzle tube outlets, an effective jet diameter of a liquid stream exiting the nozzle tube is reduced with respect to traditional nozzle assemblies where a single outlet is provided meaning that the liquid stream exits the nozzle tube in a single liquid stream or jet. Conventionally, a jet diameter of the liquid stream exiting the nozzle tube is proportional to an outlet diameter of the nozzle tube, and a surface tension of the liquid holds the jet together under stable conditions. In the nozzle assembly according to the present disclosure, the plurality of nozzle tube outlets dispense the liquid stream in multiple jets, thereby reducing the effective jet diameter. This allows the pressurized atomizing gas exiting through the atomizing gas outlet to more effectively atomize the liquid exiting the plurality of nozzle tube outlets in the form of smaller streams or jets, thereby resulting in energy and cost savings. For clarity, it is noted that certain prior art nozzle assemblies, e.g., the ones disclosed in US patent US 8840043 B2, and Chinese patent publications CN 114713390 A and CN 210875853 U, include internal mixing chambers for atomizing the liquid to be sprayed and the liquid does not exit into outside surrounding air prior to atomization. In such internal mixing chambers, the liquid and the atomizing gas are mixed before they exit together into the outside air. Different from such traditional nozzle assemblies, in the nozzle assembly according to the present disclosure, the liquid exists the nozzle tube passage through the plurality of nozzle tube outlets into the outside air and gets atomized by the pressurized atomizing gas exiting into the outside air through the atomizing gas outlet.

[0015] Additionally, it is noted that in certain prior art nozzle assemblies, no atomizing gas outlet is provided since no pressurized atomizing gas is used for atomization of the liquid. Different from such traditional nozzle assemblies, the nozzle assembly according to the present disclosure comprises the air cap having the nozzle aperture delimited by the nozzle aperture edge. The atomizing gas outlet is formed circumferentially around the plurality of nozzle tube outlets between the nozzle aperture edge and the outer surface of the nozzle tube wall. The pressurized atomizing gas exits into the outside air through the atomizing gas outlet and atomizes the liquid after the liquid has exited the plurality of nozzle tube outlets.

[0016] Moreover, it is noted that in certain prior art nozzle assemblies, e.g., the one disclosed in US patent US 11383254 B2, the atomizing gas outlet is not arranged circularly around the liquid outlet. Different from such traditional nozzle assemblies, the nozzle assembly according to the present disclosure comprises the atomizing gas outlet formed circumferentially around the plurality of nozzle tube outlets.

[0017] Further, it is noted that in certain prior art nozzle assemblies, e.g., the one disclosed in US patent US 4555059 A, the plurality of nozzle tube outlets are arranged away from the downstream end of the nozzle tube wall. Different from such traditional nozzle assemblies, in the nozzle assembly according to the present disclosure, the plurality of nozzle tube outlets are arranged proximal to or at the downstream end of the nozzle tube wall.

[0018] Nozzle assemblies are generally known from traditional liquid paint spray guns. A nozzle assembly generally comprises a nozzle body having a nozzle opening through which the liquid to be sprayed exits the nozzle body into outside air. Specific traditional nozzle bodies are described in PCT patent applications WO 2012 / 109298 Al or WO 2013 / 016474 Al, for example.

[0019] Like in traditional nozzle assemblies, when in use, the nozzle assembly according to the disclosure is generally connected to a barrel (such as to a barrel holding a paint cup) or a body of a spray gun. Liquid is supplied into the nozzle assembly through the barrel or through the spray gun body. A nozzle port on the barrel or on the spray gun body can be engaged with a corresponding matching barrel port on the nozzle assembly, such that the liquid to be sprayed can flow from the barrel or the spray gun body through the nozzle port and the barrel port into the nozzle assembly and - within the nozzle body - to the plurality of nozzle tube outlets where it exits the nozzle body and the spray gun.

[0020] The nozzle assembly according to the present disclosure comprises the nozzle body including the tubular nozzle tube. The nozzle tube has the nozzle tube wall and the elongated nozzle tube passage through which the liquid flows. The elongated nozzle tube passage extends lengthwise between the nozzle tube inlet and the plurality of nozzle tube outlets. At the plurality of nozzle tube outlets, the liquid exits the nozzle body in the spray direction and is atomized close to the plurality of nozzle tube outlets by a flow of the pressurized atomizing gas (“atomizing gas”) to form a spray of minute liquid droplets which propagates through surrounding outside air to eventually hit a surface that is to be coated with the liquid.

[0021] The nozzle assembly according to the present disclosure is for use in spray guns which spray a liquid and atomize the liquid using pressurized gas. Nozzle assemblies for other types of spraying devices, such as spray guns for spraying solids are outside the scope of this disclosure.

[0022] The term “liquid” as used herein refers, inter alia, to liquid paints, such as those comprising pigments or other suspended particles or dyes, to liquid primers, and to liquid clearcoats, liquid lacquers, liquid base coats, or liquid varnishes. A liquid may be coloured or colourless. Liquid paints are, for example, those liquid paints used in auto repair shops to coat surfaces of vehicle parts. Generally, as used herein, the term “liquid” refers to liquid coating materials that can be applied to a surface using a spray gun system including (without limitation) paints, primers, base coats, lacquers, varnishes, and similar paint-like materials, as well as other materials, such as, adhesives, sealers, fillers, putties, abrasive slurries, mold release agents, and foundry dressings which may be applied in atomized form depending on the properties and / or the intended application of the material. A liquid according to the present disclosure may comprise a carrier liquid and solid particles (pigments, powders, granules, etc.) suspended in the carrier liquid.

[0023] As used herein, a substance is considered liquid if its viscosity at 20 °C is lower than about 20000 millipascal-second (mPa.s), particularly if its viscosity at 20 °C is lower than about 2000 mPa.s.

[0024] Most traditional spray guns use pressurized air for atomization of the liquid and shaping of a spray jet. However, other gases and gas mixtures are sometimes used for these purposes. The term “gas”, as used herein, refers to a gas, such as, for example, nitrogen, oxygen, argon, carbon dioxide, or helium, as well as to a mixture of gases, such as air. The use of “air” in conventional technical terms like “air cap” for a component of a spray gun does not preclude the useability of this component with another gas mixture or with another gas. Nozzle assembly according to the present disclosure comprises the nozzle body having the elongated nozzle tube. The nozzle tube has a wall (“nozzle tube wall”), an inlet (“nozzle tube inlet”), outlets (“plurality of nozzle tube outlets”), and a passage (“nozzle tube passage”). The nozzle tube may be a tubular element of any length. The nozzle tube may be, for example, a tubular element of a length of 2 millimeters (mm) or 5 mm or 10 mm. The nozzle tube is elongated, and thereby, extends in a lengthwise direction. The lengthwise direction of the nozzle tube defines an axial direction of the nozzle tube and of the nozzle body. Radial direction is a direction orthogonal to the axial direction.

[0025] The nozzle tube has a cross section in a plane orthogonal to the axial direction between the nozzle tube inlet and the plurality of nozzle tube outlets. The cross section is not particularly limited. The nozzle tube may have, for example, a circular cross section or an elliptical cross section. It may have an irregular (e.g., non-symmetric) cross section in at least a longitudinal section of the elongated nozzle tube. The nozzle tube may have, for example, a cross section which varies in its length direction, such as from a circular to an elliptic cross section.

[0026] In certain embodiments, the tubular nozzle tube is straight, i.e., it is a straight tubular element. In certain embodiments the nozzle tube is a straight tubular element of identical circular cross section along its length. In other embodiments, the nozzle tube is bent or curved. In certain embodiments, the nozzle tube comprises a straight axial section. In some of these embodiments, the straight axial section comprises the plurality of nozzle tube outlets.

[0027] The nozzle tube is tubular. The term "tubular " generally refers to a shape of a tube, as is common, such as, for example, a cylindrical tube, such as a straight tube having a circular cross section, a curved tube such as an S-shaped tube, or a deformed tube. A tube is considered herein to be hollow and to comprise a tube wall. In a deformed tube, the tube wall has an irregular shape or an irregular cross section. The nozzle tube may be connected, e.g., at the nozzle tube inlet, to a paint-conducting element for conducting the liquid to the nozzle tube.

[0028] The nozzle tube comprises the nozzle tube passage which extends between the nozzle tube inlet and the plurality of nozzle tube outlets for conducting the liquid from the nozzle tube inlet to the plurality of nozzle tube outlets. The nozzle tube inlet is a first end of the nozzle tube passage. The plurality of nozzle tube outlets are a second end of the nozzle tube passage, opposite to the first end.

[0029] The nozzle tube passage has a cross section in a plane orthogonal to the axial direction. The cross section may not be particularly limited. The nozzle tube passage may have, for example, a circular cross section or an elliptical cross section or an irregularly shaped cross section. In certain embodiments, the nozzle tube inlet may have, for example, a circular cross section, or an elliptical cross section, or an irregularly shaped cross section.

[0030] In certain embodiments, the nozzle tube passage is straight between nozzle tube inlet and the plurality of nozzle tube outlets. In certain embodiments, the nozzle tube passage is a straight cylindrical space of identical circular cross section along its length. In certain embodiments, the nozzle tube passage comprises a straight axial section. In some of these embodiments, the straight axial section comprises the plurality of nozzle tube outlets. In other embodiments, the nozzle tube passage is curved. In some of these embodiments, the nozzle tube passage comprises a curved section and a straight section. The straight section may comprise the plurality of nozzle tube outlets.

[0031] The nozzle tube comprises the nozzle tube wall. The nozzle tube wall may extend generally lengthwise in an axial direction up to a downstream end. It may extend to the plurality of nozzle tube outlets. In certain embodiments, the nozzle tube wall may axially extend further from the plurality of nozzle tube outlets with respect to the spray direction. The nozzle tube wall may separate the nozzle tube passage from a space outside the nozzle tube, such as from an atomizing gas passage.

[0032] The nozzle tube wall has a thickness. The thickness may be defined by the extension of the nozzle tube wall in the radial direction. The thickness of the nozzle tube wall may vary along the length of the nozzle tube. Alternatively, the thickness of the nozzle tube wall may be constant along the length of the nozzle tube.

[0033] The nozzle tube wall has a cross section, e.g., a cross section of a circular or elliptical annular shape. The shape of the cross section of the nozzle tube wall may vary along the length of the nozzle tube. Alternatively, the shape of the cross section of the nozzle tube wall may be equal along the length of the nozzle tube.

[0034] The choice of material or materials of the nozzle tube wall is not particularly limited. The material coming into contact with the liquid may be selected to be chemically compatible with the liquid to be sprayed, e.g., chemically inert with respect to the liquid. In certain embodiments, the nozzle tube wall is made of, or comprises, a polymeric material, or a metal. Polymeric material can generally be molded or cast or otherwise formed to a high degree of precision at reasonable cost to form the nozzle tube and the nozzle tube wall. Metal is a versatile material which can be machined, metal injection molded, cast or otherwise formed to a high degree of precision at reasonable cost to form the nozzle tube and the nozzle tube wall. Within the group of polymeric material and the group of metallic materials, a number of suitable materials are known to have chemical properties that don’t react chemically with typical liquids, and thereby can be used over extended periods of time, making polymeric and metal materials versatile substances for manufacturing nozzle bodies and nozzle tube walls according to the present disclosure.

[0035] The nozzle tube wall comprises a radially inner surface and an opposed radially outer surface. The inner surface and the outer surface are separated by a thickness of the nozzle tube wall. The inner surface is oriented radially inward and faces the nozzle tube passage. It delimits the nozzle tube passage. In use, the liquid, conducted by the nozzle tube passage, is in contact with the inner surface of the nozzle tube wall.

[0036] The radially outer surface is generally arranged opposite to the radially inner surface and radially outward from the inner surface. The outer surface is oriented radially outward and faces radially away from the nozzle tube passage. In certain embodiments, the outer surface is concentric with the inner surface.

[0037] In use, the outer surface not only delimits the nozzle tube wall and the nozzle tube, but can also delimit, in conjunction with another element, e.g., an element of an air cap as explained below, an atomizing gas passage. In some of such embodiments, the outer surface is in contact with an atomizing gas conducted through the atomizing gas passage towards an atomizing gas outlet, arranged circumferentially around the nozzle tube wall at the plurality of nozzle tube outlets.

[0038] Radially inwards of the outer surface is the nozzle tube wall and the nozzle tube passage, while the atomizing gas passage is radially outwards of the outer surface. In such embodiments, the nozzle tube wall is arranged radially between the nozzle tube passage and the atomizing gas passage. The nozzle tube wall separates the nozzle tube passage from the atomizing gas passage.

[0039] In certain embodiments, the outer surface of the nozzle tube wall has a circular cross section. A circular cross section of the outer surface is particularly cost-effective to manufacture at a high precision of symmetry (roundness), e.g., on a turning lathe. The precise circular symmetry may help provide a circular symmetric jet of the atomizing gas and in consequence a more even and more effective atomization of the liquid a short distance downstream from the nozzle tube outlet.

[0040] The nozzle tube inlet may be shaped such as to be connectable, directly or indirectly, to a liquid nozzle port on a barrel of a spray gun body. A direct connection is a connection in which the nozzle tube inlet is in surface contact with the liquid nozzle port, whereas an indirect connection is a connection in which an intermediate element connects the nozzle tube inlet with the liquid nozzle port. A connection of the nozzle tube inlet to the liquid nozzle port on the barrel would allow liquid to flow from the barrel or from the spray gun body, as the case may be, into the nozzle body and through the nozzle tube passage to the plurality of nozzle tube outlets where it exits the nozzle body into outside air and is atomized by the atomizing gas. The plurality of nozzle tube outlets are apertures in the nozzle tube through which the liquid exits the nozzle tube (and the nozzle body) and enters the surrounding air. The plurality of nozzle tube outlets are located at the most downstream extent of the nozzle tube passage. Further, the plurality of nozzle tube outlets are located radially within or within the downstream end of the nozzle tube wall. The plurality of nozzle tube outlets are arranged in an outlet surface. In certain embodiments, the outlet surface may be a geometrically flat surface, i.e., the outlet surface may be an outlet plane. The plurality of nozzle tube outlets are disposed in such an outlet plane. However, in certain embodiments, the outlet surface may be non-planar. For example, the outlet surface may be domed, tapered (inward or outward), concave / convex, or irregular. In certain embodiments, the outlet surface may be curved or at least partially curved. In such embodiments, the curvature of the outlet surface may determine a curvature of each nozzle tube outlet in the outlet surface.

[0041] In certain embodiments, the downstream end of the nozzle tube wall is arranged in the outlet surface. In such embodiments, the plurality of nozzle tube outlets and the downstream end of the nozzle tube wall are arranged along a same plane, i.e., the outlet surface. Alternatively, in certain embodiments, the downstream end of the nozzle tube wall is arranged downstream from the outlet surface. In such embodiments, the liquid may exit the plurality of nozzle tube outlets upstream of the downstream end of the nozzle tube wall.

[0042] The plurality of nozzle tube outlets are fluidically connected with the nozzle tube inlet. Thus, in use, the liquid entering the nozzle tube inlet passes through the nozzle tube passage to the plurality of nozzle tube outlets and exits through the plurality of nozzle tube outlets. Each nozzle tube outlet of the plurality of nozzle tube outlets is disposed at one end of the nozzle tube passage and is delimited, in the radial direction, by the nozzle tube wall which extends up to the downstream end. Each nozzle tube outlet may be in the form of an orifice in the nozzle body circumferentially delimited by the nozzle tube wall. In certain embodiments, each nozzle tube outlet may be delimited by a forwardmost (in the spray direction) terminal edge of the outer surface of the nozzle tube wall. In certain embodiments, the plurality of nozzle tube outlets have an identical shape and an identical size.

[0043] Each nozzle tube outlet of the plurality of nozzle tube outlets has a cross section. The cross section of each nozzle tube outlet may have any suitable shape, including a circular shape, an elliptic shape, a square shape, a rectangular shape, a polygonal shape, a star shape, or an irregular shape. In certain embodiments, at least one nozzle tube outlet of the plurality of nozzle tube outlets has a circular cross section in the outlet surface. The circular cross section may allow the at least one nozzle tube outlet to efficiently deliver the liquid by mitigating friction or fluid flow losses. The cross section of each nozzle tube outlet of the plurality of nozzle tube outlets determines a cross section of the flow of liquid as it exits the nozzle tube and enters the surrounding air, before the liquid is atomized to form minute droplets. The plurality of nozzle tube outlets of the nozzle tube divides a flow of the liquid from the nozzle tube inlet into multiple smaller liquid jets as the liquid exits through the plurality of nozzle tube outlets. This may reduce an effective diameter of the liquid jet exiting the nozzle tube as compared to a single larger outlet, thereby allowing the liquid to be more effectively atomized by the atomizing gas as the liquid enters the surrounding air.

[0044] In the outlet surface, a cross section of at least one nozzle tube outlet of the plurality of nozzle tube outlets has an area of between 0.15 square millimeters and 1.2 square millimeters. A smaller area of the cross section may restrict the flow of the liquid through the plurality of nozzle tube outlets. Thus, it may create greater back pressure within the nozzle tube passage. This may be challenging to supply the necessary liquid flow rates with higher viscosity liquids. In contrast, a greater area of the cross section may mitigate the advantageous effect of generation of multiple smaller liquid streams. The preferred area of the cross section may be chosen based on parameters, such as a desired liquid flow rate and an atomization quality, to help obtain an acceptable balance between these effects.

[0045] In certain embodiments, in the outlet surface, the cross sections of the plurality of nozzle tube outlets may be symmetric about a center point or a center of the plurality of nozzle tube outlets (i.e., a centroid of the plurality of nozzle tube outlets). In the embodiments where the plurality of nozzle tube outlets is identical in shape and size and the nozzle tube has a circular cross section in the outlet surface, the centroid of the plurality of nozzle tube outlets may coincide with a geometric center of the nozzle tube in the outlet surface. However, in other embodiments, the cross section of one or more nozzle tube outlets may be different due to irregular shape, e.g., a shape exhibiting no symmetry.

[0046] In order to define the center point or the center of the plurality of nozzle tube outlets in a most general manner, the commonly known notion of a “centroid” is applied. A centroid of a plane figure is commonly known to be an arithmetic mean position of all the points in the surface of the figure. The centroid is therefore the centre point of the plane figure. Thus, the centroid of the plurality of nozzle tube outlets is the arithmetic mean position of the cross sections of the plurality of nozzle tube outlets in the outlet surface. In certain embodiments where the outlet surface is a planar surface, the centroid of the plurality of nozzle tube outlets may lie on the outlet surface. In certain embodiments where the outlet surface is a non-planar surface, the centroid of the plurality of nozzle tube outlets may not necessarily lie on the outlet surface.

[0047] In certain embodiments, the liquid exits the nozzle tube at the plurality of nozzle tube outlets into the outside air in the spray direction. In certain embodiments, the spray direction passes through the centroid of the plurality of nozzle tube outlets. The spray direction may be parallel to a flight direction of the liquid flow at the very position where the liquid exits each nozzle tube outlet.

[0048] In certain embodiments, in use, the liquid exits the plurality of nozzle tube outlets into the outside air in directions oriented within an angle of 45 degrees (°) from the axial direction. In certain embodiments, the liquid exits the plurality of nozzle tube outlets into the outside air in directions oriented within an angle of 30° from the axial direction. In some embodiments, in use, the liquid exits the plurality of nozzle tube outlets into the outside air in the axial direction.

[0049] It should be noted that the liquid may exit the plurality of nozzle tube outlets in multiple directions with respect to the axial direction. For example, in certain embodiments, at least a portion of the liquid may exit the plurality of nozzle tube outlets into the outside air in directions oriented within an angle of 45 degrees (°) from the axial direction, and at least another portion of the liquid may exit the plurality of nozzle tube outlets into the outside air in the axial direction.

[0050] The spray direction is generally determined by an orientation of a terminal portion of the nozzle tube passage, i.e., the portion closest to the plurality of nozzle tube outlets. The spray direction through the centroid of the plurality of nozzle tube outlets defines a spray axis. In certain embodiments where the cross sections of the plurality of nozzle tube outlets are symmetric about the centroid, the spray axis passes through the centroid. In certain embodiments, the spray axis is defined as an axial direction through the centroid of the plurality of nozzle tube outlets. The axial direction is defined by the length direction of the nozzle tube passage. Where the nozzle tube passage is not straight, its length direction is the direction passing through the centroid of the nozzle tube inlet and the centroid of the plurality of nozzle tube outlets.

[0051] In certain embodiments, the centroid of the plurality of nozzle tube outlets in the outlet surface is located outside of any nozzle tube outlet of the plurality of nozzle tube outlets. In such embodiments, no nozzle tube outlet of the plurality of nozzle tube outlets is located on the spray axis.

[0052] In certain embodiments, all nozzle tube outlets of the plurality of nozzle tube outlets have an identical shape and an identical size. This may allow the nozzle body to dispense the liquid evenly through the plurality of nozzle tube outlets. The identical shape of the plurality of nozzle tube outlets provides that the plurality of nozzle tube outlets are symmetric about the spray axis and the identical size of the plurality of nozzle tube outlets provides that the liquid exits uniformly through each nozzle tube outlet.

[0053] In certain embodiments, each nozzle tube outlet of the plurality of nozzle tube outlets is formed at a downstream end of an outlet channel through an outlet wall. The outlet channel is an intermediate channel between the nozzle tube passage and the plurality of nozzle tube outlets disposed at the outlet surface. Thus, in use, the outlet channel conducts the liquid from the nozzle tube passage to the plurality of nozzle tube outlets. In certain embodiments, the nozzle tube passage transitions from a circular crosssection to multiple flow passages, i.e., the outlet channels.

[0054] In certain embodiments, the outlet channel is radially delimited by a channel wall extending axially from a channel wall rear end to a channel wall front end arranged in the outlet surface. More precisely, the channel wall extends from the inner surface of the nozzle tube wall to the outlet surface. In certain embodiments where the downstream end of the nozzle tube wall is arranged in the outlet surface, the channel wall front end is disposed adjacent the forward end of the outer surface of the nozzle tube wall.

[0055] The outlet channel may have a cross section. The cross section may not be particularly limited. The outlet channel may have, for example, a circular cross section, or an elliptical cross section, or an irregularly shaped cross section. In certain embodiments, the channel wall of the outlet channel is disposed parallel to the spray axis. In such embodiments, the channel wall of the outlet channel is parallel to the axial direction. Further, the outlet channel is straight between the channel wall rear end to the channel wall front end. In certain embodiments the outlet channel is a straight cylindrical space of identical circular cross section along its length.

[0056] In certain embodiments, the outlet channel comprises a straight axial section and the straight axial section comprises the corresponding nozzle tube outlet. In certain embodiments, the outlet channel comprises a frustoconical section. In certain embodiments, the outlet channel comprises a combination of the straight axial section and the frustoconical section.

[0057] In certain embodiments, the channel wall of the outlet channel is inclined obliquely with respect to the spray axis. In certain embodiments, the outlet channel upstream from at least one nozzle tube outlet of the plurality of nozzle tube outlets has a diverging axial section in which a cross section of the outlet channel increases towards the outlet surface. In the diverging axial section, the cross section of the outlet channel increases towards the outlet surface. Therefore, a cross sectional area of the outlet channel at the channel wall front end is greater than a cross sectional area of the outlet channel at the channel wall rear end. Further, the channel wall rear end is radially inward of the channel wall front end with respect to the spray axis. In alternative embodiments, the cross section of the outlet channel may increase towards the outlet surface or remain constant for a certain portion of the diverging axial section.

[0058] In certain embodiments, a surface of the diverging axial section guides and directs at least a portion of the liquid received from the nozzle tube passage radially away from the spray axis in thin layers towards the atomizing gas outlet arranged circumferentially around the nozzle tube wall adjacent the plurality of nozzle tube outlets. This allows the liquid to be sheared off at the plurality of nozzle tube outlets and atomized by a flow of the pressurized atomizing gas, thereby enhancing an efficiency of formation of a spray of minute liquid droplets which propagates through the surrounding air to eventually hit a surface that is to be coated with the liquid. The diverging axial section of the outlet channel of the at least one nozzle tube outlet biases the liquid towards the atomizing gas outlet, thereby increasing an interaction between the atomizing gas and the liquid resulting in improved atomization. The surface of the diverging axial section may easily allow the liquid to flow radially outward from the channel wall rear end to the channel wall front end.

[0059] To obtain good spray results the diverging axial section may be adapted in response to, for example, a desired liquid flow rate, a desired spray jet geometry, to a viscosity or temperature or solid content of the liquid to be sprayed, to ambient air temperature, or to other parameters.

[0060] In certain embodiments, the plurality of nozzle tube outlets may be arranged around the spray axis. Further, in certain embodiments, the plurality of nozzle tube outlets may be symmetrically arranged about the spray axis. It should be noted that the total number of nozzle tube outlets in the plurality of nozzle tube outlets is not limited to any number. In certain embodiments, three, four, five, six, seven or eight nozzle tube outlets of the plurality of nozzle tube outlets are arranged in the outlet surface.

[0061] In certain embodiments, the plurality of nozzle tube outlets may be arranged around the spray axis in a plurality of segments, such that the outlet channel of each nozzle tube outlet may form part of an axial section of the nozzle tube passage. In certain embodiments, the axial sections corresponding to the plurality of segments may be symmetrically arranged around the spray axis. The plurality of segments may include straight or rounded comers for manufacturing purposes.

[0062] In certain embodiments, three, four, five, six, seven or eight nozzle tube outlets of the plurality of nozzle tube outlets are arranged, in the outlet surface, symmetrically about a spray center as wedge-shaped segments combining, in the outlet surface, to form a circle centered about the spray center. In certain embodiments, the spray center is coincident with the centroid of the plurality of nozzle tube outlets. In such embodiments, each nozzle tube outlet has a wedge-shaped cross section, i.e., a cross section in the shape of a sector of a circular disc. An included angle of the sector of the circular disc may be acute, obtuse, or 90 degrees (°). A geometric center of the wedge-shaped segments of the plurality of nozzle tube outlets, i.e., the spray center, is centered on the spray axis.

[0063] In certain embodiments where each nozzle tube outlet is arranged as the wedge-shaped segment, the outlet channel of each nozzle tube outlet may form a part of a cylindrical axial section. In other words, the outlet channels of the plurality of nozzle tube outlets are formed by dividing the cylindrical axial section into a plurality of sections arranged symmetrically about the spray axis. These sections may include straight or rounded comers for manufacturing purposes.

[0064] In certain embodiments where each nozzle tube outlet is arranged as the wedge-shaped segment, the outlet channel of each nozzle tube outlet may form a part of a frustoconical axial section. In other words, the outlet channels of the plurality of nozzle tube outlets are formed by dividing the frustoconical axial section into a plurality of sections arranged symmetrically about the spray axis. These sections may include straight or rounded comers for manufacturing purposes.

[0065] In certain embodiments, in the outlet surface, a cross section of at least one nozzle tube outlet, or each nozzle tube outlet of the plurality of nozzle tube outlets, is delimited by a perimeter line comprising at least a curved line segment and a straight line segment. For example, in the outlet surface, the curved line segment and one or more straight line segments form the wedge-shaped segment of the at least one nozzle tube outlet.

[0066] Each two adjacent nozzle tube outlets of the three, four, five, six, seven or eight nozzle tube outlets are separated by a respective stmt of a plurality of stmts. The term “stmt” in general refers to a beam rod or a bar. Each stmt is disposed between two adjacent nozzle tube outlets. Thus, the number of nozzle tube outlets in the plurality of nozzle tube outlets can be determined by a number of the stmts. In other words, the plurality of stmts divide an outlet of the nozzle tube into the plurality of nozzle tube outlets. In certain embodiments, the plurality of stmts meet at the spray center. In certain embodiments, the plurality of stmts are integrally formed with the nozzle body.

[0067] In certain embodiments where the plurality of nozzle tube outlets are arranged as wedge-shaped segments of the cylindrical axial section, a volume of the outlet channels of the plurality of outlets and a volume of the plurality of stmts together form a volume of the cylindrical axial section. Similarly, in certain embodiments where the plurality of nozzle tube outlets are arranged as wedge-shaped segments of the frustoconical axial section, the volume of the outlet channels of the plurality of outlets and the volume of the plurality of stmts together form a volume of the frustoconical axial section.

[0068] In certain embodiments, each stmt of the plurality of stmts extends, in an axial direction, by 3 millimeters or less. Such a dimension of each stmt of the plurality of stmts in the axial direction is considered suitable based on a necessary liquid flow rate of the liquid through the plurality of nozzle tube outlets and manufacturing requirements of each stmt. In certain embodiments, each stmt extends in the axial direction by at least 0.12 millimeters. Preferably, each stmt extends in the axial direction by 0.38 millimeters. In certain embodiments, each stmt of the plurality of stmts extends, in the radial direction, by 3 millimeters or less with respect to the spray axis. In certain embodiments, where the nozzle tube has a circular cross section in the outlet surface, a length of each stmt in the radial direction is determined by a diameter of the inner surface of the nozzle tube wall. In certain embodiments, each stmt extends in the radial direction by at least 0.25 millimeters. Preferably, each stmt extends in the radial direction by 1 millimeter.

[0069] In certain embodiments, a width of each stmt of the plurality of stmts in the outlet surface is 3 millimeters or less. A larger width of each stmt in the outlet surface may obstruct the flow of the liquid. Therefore, an optimal width of each stmt may be determined based on desirable flow characteristics of the liquid, and structural or geometrical requirements of each stmt. In certain embodiments, the width of each stmt is at least 0.12 millimeters. Preferably, the width of each stmt is 0.29 millimeters.

[0070] In certain embodiments, the plurality of stmts are comprised in a stmt assembly, the stmt assembly being formed as a single piece. The stmt assembly and at least one other portion of the nozzle body are formed as separate pieces. The at least one other portion of the nozzle body may form a main portion of the nozzle body, and the stmt assembly may be coupled to the at least one other portion of the nozzle body. This may allow the stmt assembly and the nozzle body to be manufactured or produced separately.

[0071] Optionally the stmt assembly is capable of being attached to the at least one other portion of the nozzle body, such as by welding, interference fit, over molding, or insert molding. In such embodiments, the stmt assembly, which may be manufactured separately, can be assembled with the at least one other portion of the nozzle body by aligning a geometric center of the stmt assembly with a center of the at least one other portion of the nozzle body, thereby forming the plurality of nozzle tube outlets in the outlet surface. The stmt assembly is fixedly coupled (e.g., via welding or press fit) to the at least one other portion of the nozzle body to restrict a movement of the stmt assembly with respect to the at least one other portion of the nozzle body.

[0072] In certain embodiments, a short distance downstream from where the liquid exits the nozzle tube passage through the plurality of nozzle tube outlets, the jet of liquid is atomized by a flow of the atomizing gas. In certain embodiments, in the nozzle assembly according to the present disclosure, the outer surface of the nozzle tube wall directs at least a portion of the atomizing gas emanating from the annular atomizing gas outlet angularly away from the spray axis. The atomizing gas outlet is formed circumferentially around the plurality of nozzle tube outlets. Specifically, the outer surface of the nozzle tube wall adjacent the atomizing gas outlet is oriented or shaped to direct at least a portion of the pressurized atomizing gas exiting through the atomizing gas outlet into the outside air angularly away from the spray axis. Within this angularly -outward directed flow of the atomizing gas, a pressure at the plurality of nozzle tube outlets is lower than it is in traditional geometries in which the atomizing gas flows in directions along the spray axis or towards the spray axis. The lower pressure at the nozzle tube draws more liquid from the nozzle tube passage and increases the liquid (e.g., a paint) flow rate, although the consumption of the pressurized atomizing gas is unchanged with respect to the traditional nozzle assemblies. To obtain a liquid flow rate similar to those obtained with traditional nozzle assemblies, a pressure and / or a volume of the pressurized atomizing gas can be reduced in spray guns featuring the nozzle assembly according to the present disclosure. This may result in energy and cost savings. The lower pressure of the atomizing gas may also mitigate high-frequency noise during spraying operations, which reduces occupational noise exposure and associated health risks for human operators.

[0073] In certain embodiments, the outer surface of the nozzle tube wall has a cylindrical surface portion, its symmetry axis being coaxial with the spray axis, The outer surface includes a diverging portion in the vicinity of the plurality of nozzle tube outlets (i.e., at the forward end portion of the nozzle tube). In its diverging portion, the outer surface of the nozzle tube wall may have a diameter increasing linearly with decreasing axial distance from the plurality of nozzle tube outlets. In a longitudinal section through a center of the nozzle tube passage, a contour of the outer surface of the nozzle tube wall in the diverging portion may be a straight line ascending with decreasing axial distance to the plurality of nozzle tube outlets. In some embodiments the outer surface of the nozzle tube wall may have, in its diverging portion, a diameter increasing exponentially, polynomically, parabolically or hyperbolically with decreasing axial distance to the plurality of nozzle tube outlets. In other embodiments, in a longitudinal section through the center of the nozzle tube passage, a contour of the outer surface of the nozzle tube wall in the diverging portion may be a section of a circle or a section of an ellipse.

[0074] This “divergent” atomizing gas may not impinge directly on the jet of liquid emanating from the plurality of nozzle tube outlets. Instead, the divergent atomizing gas creates a larger volume of reduced pressure, located immediately in front of, i.e., downstream from, the plurality of nozzle tube outlets. In certain configurations, the divergence of the atomizing gas can also enhance turbulence in front of the volume of reduced pressure. Without wishing to be bound by this theory, the inventors believe that this stronger turbulence helps obtain a more effective atomization of the liquid, while the larger volume of reduced pressure helps increase the liquid flow rate.

[0075] The flow direction of the atomizing gas may be determined by the orientation and / or shape of the outer surface of the nozzle tube wall alone, or in conjunction with another surface of the nozzle body. In many known spray gun designs, however, such as in certain ones shown in the international patent application published as WO 2012 / 109298 Al, the flow direction of the atomizing gas is determined by the orientation and / or shape of the outer surface of the nozzle tube wall and an orientation and / or shape of a surface of an air cap.

[0076] Air caps are generally known from many existing spray guns: an air cap is an element directly or indirectly attached to the barrel or to the body of the spray gun and directs pressurized gas in suitable directions for atomizing the liquid jet and for shaping the jet of minute droplets of atomized liquid. Where two elements are connected without intermediate elements and in surface contact with each other, they are considered to be “directly connected” herein. Where two elements are connected with each other via an intermediate element, whether in surface contact with each other or not, they are considered to be “indirectly connected” herein.

[0077] In certain embodiments of nozzle assemblies according to the present disclosure, the air cap comprises two air horns arranged opposite to each other relative to the spray axis and comprising shaping air apertures to direct a shaping gas from opposite directions towards the jet of atomized liquid in order to shape the spray jet into a desired pattern. The air cap and the nozzle body may be integrated to form an integrated air cap / nozzle body, as in the European patent EP 2736651 B 1, for example.

[0078] When the air cap is connected directly or indirectly with the nozzle body, the outer surface of the nozzle tube wall is operable to form, in conjunction with a surface of the air cap, an atomizing gas outlet arranged circumferentially around the plurality of nozzle tube outlets. The atomizing gas outlet may be formed between a surface of the air cap and the outer surface of the nozzle tube wall adjacent to the plurality of nozzle tube outlets, i.e., the outer surface of a terminal end of the nozzle tube. In certain embodiments, the atomizing gas outlet has an annular shape, centered about the spray axis, and arranged such as to encircle the plurality of nozzle tube outlets.

[0079] A circumferential arrangement of the atomizing gas outlet around the plurality of nozzle tube outlets is not limited to a circular circumferential arrangement, but includes, for example, elliptic circumferential arrangements, square or rectangular or other polygonal circumferential arrangements, starshaped circumferential arrangements, and circumferential arrangements of irregular shape. The atomizing gas outlet may have an annular shape, a circular shape, an elliptic shape, a square or a rectangular or another polygonal shape, a star shape, or an irregular shape. Although the shape of the circumferential arrangement is not particularly limited, it is preferred that the atomizing gas outlet forms essentially a full circumference (of whatever shape) around the plurality of nozzle tube outlets. This helps ensure proper atomization of the liquid.

[0080] A width of the atomizing gas outlet is not particularly limited. The width of the atomizing gas outlet is the extension of the atomizing gas outlet in the radial direction. In certain embodiments, the width is the extension of the atomizing gas outlet in the radial direction in the outlet surface of the plurality of nozzle tube outlets. In such configurations, the width is the radial distance in the outlet surface of the plurality of nozzle tube outlets from the outer surface of the nozzle body to a nozzle aperture edge.

[0081] At a given atomizing gas pressure, a wider atomizing gas outlet will result in lower gas speed, and hence, a reduced shear stress / velocity gradient between the atomizing gas and the liquid to be atomized. In contrast, a narrower atomizing gas outlet allows less atomizing gas to pass through, but it may flow at a higher velocity, and thereby increases the shear stress between the atomizing gas and the liquid. The preferred widths are chosen amongst a large set of design parameters (desired air consumption, desired liquid flow rate, atomization quality, etc.) to help obtain an acceptable balance between these effects.

[0082] The atomizing gas outlet may be circumferentially arranged around the plurality of nozzle tube outlets at a certain radial distance from the plurality of nozzle tube outlets. This radial distance may be the thickness of the nozzle tube wall at the terminal end of the nozzle tube. Since a gas exit velocity is often highest at the atomizing gas outlet and decays moving downstream, there can be benefits to placing the plurality of nozzle tube outlets as close as practically possible to the atomizing gas outlet. One way to do so is by minimizing the radial distance between the plurality of nozzle tube outlets and atomizing gas outlet. Generally, a greater radial distance results in less efficient extraction and atomization of the liquid.

[0083] Conversely, a smaller radial distance may cause the nozzle tube wall to be quite thin at the plurality of nozzle tube outlets, introducing the risk of inconsistencies and damage.

[0084] The atomizing gas outlet may be a ring-shaped, i.e., annular, atomizing gas outlet. The atomizing gas outlet may be arranged concentric with the centroid of plurality of nozzle tube outlets. The atomizing gas outlet may be arranged centered about the spray axis. The plurality of nozzle tube outlets and the atomizing gas outlet may be arranged concentrically with each other and centered about the spray axis.

[0085] The plurality of nozzle tube outlets are arranged in the outlet surface, such as a plane orthogonal to the spray axis or orthogonal to the axial direction. In certain embodiments, the atomizing gas outlet may be arranged in the same geometric plane as the plurality of nozzle tube outlets, or it may be recessed or protruding from the plane of the plurality of nozzle tube outlets.

[0086] The outer surface of the nozzle tube wall is also operable to form, in conjunction with a surface of the air cap when the air cap is connected directly or indirectly with the nozzle body, an atomizing gas passage for conducting the pressurized atomizing gas toward the atomizing gas outlet. The pressurized atomizing gas can thus exit the atomizing gas passage into the outside air at the atomizing gas outlet and can atomize the liquid after the liquid has exited the plurality of nozzle tube outlets. A first portion of the atomizing gas passage may thus be formed by a surface of the air cap, while a second portion of the atomizing gas passage may be formed by the outer surface of the nozzle tube wall. Before the air cap is connected with the nozzle body, the atomizing gas passage does thus not exist, or is incomplete because it is not properly delimited so that the pressurized atomizing gas is not conducted toward the atomizing gas outlet. However, in the absence of an air cap the outer surface of the nozzle tube wall is suitable (suitably shaped, suitably arranged, with a suitable surface structure) to form a portion of the atomizing gas passage, once a suitable air cap is connected.

[0087] The nozzle body, in conjunction with the air cap, forms the nozzle assembly as described herein. In the nozzle assembly or otherwise, the air cap may be connected with the nozzle body in a fixed spatial relation. The fixed spatial relation can help keep the shape of the atomizing gas outlet formed between a portion of the air cap and the nozzle tube wall constant. The nozzle assembly may be attachable to a platform of a spray gun, such as by attachment of the nozzle body to the spray gun platform or by attachment of the air cap to the spray gun platform or both.

[0088] In certain of these nozzle assemblies, the nozzle assembly comprises the nozzle body as described herein and the air cap, connected with the nozzle body in a fixed spatial relation, wherein the air cap comprises a front wall facing generally in the spray direction and comprising a nozzle aperture delimited by the nozzle aperture edge. The nozzle tube is arranged in, or protrudes outwardly through, the nozzle aperture, such that the atomizing gas outlet is formed between the nozzle aperture edge and the nozzle tube wall. An edge delimiting the nozzle aperture in the front wall is referred to as nozzle aperture edge herein. In certain embodiments, the nozzle aperture edge is arranged in the outlet surface or upstream from the outlet surface. Further, the nozzle aperture edge is arranged radially outward from the downstream end of the nozzle tube wall.

[0089] Such a nozzle assembly is also advantageous in that the radially inner delimitation of the atomizing gas outlet is formed by the nozzle tube wall and the radially outer delimitation of the atomizing gas outlet is formed by the nozzle aperture edge. A nozzle body directing a portion of the atomizing gas angularly away from the spray axis at a specific angle can thereby be used with air caps of different geometries. This, in turn, allows for geometric variations of the atomizing gas outlet, e.g., of its width or its orientation, just by utilizing different air caps, and without having to change the nozzle body.

[0090] The front wall of the air cap is an outer wall of the air cap which comprises a front surface facing generally forward, i.e., facing generally in the spray direction. The front surface is generally in contact with the outside air. The front wall may be a wall of the air cap of which a portion may be arranged between opposite air horns, if such air horns are present. The front wall may form the nozzle aperture in which the downstream end (or the forward end) of the nozzle tube may be arranged or through which the downstream end of the nozzle tube protrudes outwardly. In use, the air cap including its front wall is arranged centered about the spray axis. The nozzle aperture may be arranged centered about the spray axis and concentric with the centroid of the plurality of nozzle tube outlets. In the plane of the plurality of nozzle tube outlets, a gap between the nozzle tube and the nozzle aperture edge may exist. The gap may extend circumferentially to form a circle. A width of the gap extends in the radial direction. The gap may form the atomizing gas outlet described herein. The atomizing gas outlet is arranged circumferentially around the plurality of nozzle tube outlets, such that the pressurized atomizing gas exits into the outside air through the atomizing gas outlet and atomizes the liquid after the liquid has exited the plurality of nozzle tube outlets.

[0091] For an evenly covered target surface, it is often desired to obtain a jet of liquid spray which is perfectly rotationally symmetric with respect to the spray axis. In order to get close to a symmetric jet of liquid, in certain embodiments of the nozzle assemblies described herein, the nozzle tube outlet and / or the nozzle tube wall are of rotationally symmetric shape and are arranged concentrically with each other, such as centered on the spray axis. Similarly, the entire air cap and / or the nozzle aperture edge may be of rotationally symmetric shape and may be arranged concentrically with each other, such as centered on a symmetry axis of the air cap.

[0092] Certain liquid spray guns have a barrel attached to the spray gun platform through which the to-be-sprayed liquid flows from an external container into the spray gun. Therefore, after a spraying operation, only the barrel and the nozzle body need to be cleaned from the liquid, not the spray gun platform. A rear portion of the barrel is attached to the spray gun platform, while its front portion often serves to attach the air cap and the nozzle body. A further function of the barrel is to conduct the pressurized atomizing gas from the spray gun platform to the atomizing gas outlet and potentially towards a shaping gas outlet (e.g., in air horns) at the front portion of the spray gun. The barrel may comprise separate ducts for the atomizing gas and the shaping gas. In some embodiments, the barrel and the nozzle body are integrally formed as a single component.

[0093] Nozzle assemblies comprising the air cap and the nozzle body according to the present disclosure have been described above. Nozzle bodies can be, in use, connected to a spray gun body, but alternatively to a barrel which is attached to the spray gun body. Also, an air cap can be connected to the spray gun body, but it can alternatively be connected to a barrel which is attached to the spray gun body. Where the air cap and the nozzle body are each connected to the barrel, these connections to the barrel may help establish and maintain a fixed spatial relation between the nozzle body and the air cap. This fixed spatial relation helps maintain a constant shape and an orientation of the atomizing gas outlet, which is formed between a portion of the air cap (e.g., its nozzle aperture edge) and a portion of the nozzle body (e.g., the nozzle tube wall). Maintaining the shape and orientation of the atomizing gas outlet helps keep the jet of atomized liquid in a consistent, fixed geometry, and contributes to an atomization which is constant over time.

[0094] In certain embodiments of the nozzle assemblies described herein, the nozzle assembly further comprises an atomizer base. In many spray guns and nozzle assemblies, a single component called ''atomizer" conducts atomizing gas towards the atomizing gas outlet and the liquid to the nozzle tube outlet. The atomizer base when assembled with the nozzle body is referred to herein as an atomizer. The atomizer base is a rearward portion of the atomizer and comprises means for attaching the atomizer to the barrel or to a spray gun platform. In certain embodiments, the nozzle body may be integrally formed with the atomizer base.

[0095] The atomizer base comprises a plurality of atomizing gas channels for conducting the pressurized atomizing gas to the atomizing gas outlet. The atomizing gas channels allow the pressurized atomizing gas to be delivered from the barrel to the atomizing gas outlet. Additionally, the atomizer base further comprises a liquid aperture (or a barrel port as described above) for conducting the liquid into the nozzle body. The atomizer base is secured to the nozzle body such that the liquid can flow through the liquid aperture into the nozzle tube inlet.

[0096] The nozzle body and the atomizer base of certain atomizers can be manufactured separately and later be attached to each other to form the atomizer. Separate manufacturing may be advantageous, as large portions of a typical atomizer, and in particular the atomizer base, do not require extreme manufacturing precision to function properly. The performance of the nozzle body, however, is highly sensitive to mechanical tolerances and imperfections. By separating the manufacturing of the nozzle body from the manufacturing of the atomizer base, much tighter manufacturing controls can be applied to the manufacturing of the nozzle body than to the manufacturing of the atomizer base. Thereby, the nozzle body can be manufactured at a higher degree of precision in terms of its physical dimensions, surface smoothness, material homogeneity, etc. This can result in the nozzle bodies having a much higher degree of precision than the atomizer bases. The high degree of mechanical precision also enables manufacturing of complex nozzle body designs, potentially even down to a microscopic scale.

[0097] The separate manufacturing of the nozzle body and the atomizer base and their subsequent attachment to each other at a later stage can bring other advantages. The nozzle body and the atomizer base may be manufactured from different materials, such as from different polymeric materials or different metal materials, which may allow to reduce a cost of raw material. The nozzle body and the atomizer base may be manufactured at the same time in simultaneous processes, thus saving time in manufacturing. Another potential advantage is that a modular atomizer concept can be applied: a selected one out of various different types of nozzle bodies (each having a different nozzle tube outlet shape and thereby providing a different atomization characteristic, for example) can be attached to a same single type of atomizer base. Many different types of atomizers can thus be made using the same atomizer base, bringing down cost for stockkeeping and manufacturing of the atomizer base. A large variety of intricate and complex nozzle body designs may thus be manufactured quickly and cost effectively before being joined with a standardized atomizer base.

[0098] Nozzle assemblies according to the present disclosure can be manufactured in traditional manufacturing processes like, for example, machining or molding. They may also be created via additive manufacturing processes using a 3D printer.

[0099] Brief Description of the Drawings

[0100] The invention will now be described in more detail with reference to the following Figures exemplifying particular embodiments of the invention:

[0101] Fig. 1 Exploded perspective view of a liquid spray gun comprising the nozzle assembly according to the present disclosure;

[0102] Fig. 2 Perspective view of a nozzle body of the nozzle assembly, attached to a barrel;

[0103] Fig. 3 Perspective view of the nozzle assembly comprising the nozzle body and the barrel of Figure 2;

[0104] Fig. 4 Longitudinal sectional view of the nozzle assembly of Figure 3;

[0105] Fig. 5 Longitudinal sectional view of a forward portion of the nozzle body of Figures 1-4, comprising a plurality of nozzle tube outlets;

[0106] Fig. 6 Front view of the plurality of nozzle tube outlets of the nozzle body of Figures 1-5; Fig. 7 Perspective view of the nozzle body of Figures 1-6;

[0107] Fig. 8 Exploded perspective view of the nozzle body of Figures 1-7 and a strut assembly; Fig. 9 Longitudinal sectional view of respective forward portions of the nozzle body and an air cap of the nozzle assembly of Figures 3 and 4;

[0108] Fig. 10 Perspective view of the nozzle body, according to another embodiment of the present disclosure;

[0109] Fig. 11 Longitudinal sectional view of a forward portion of the nozzle body of Figure 10, comprising the plurality of nozzle tube outlets;

[0110] Figs. 12-15 Perspective views of the nozzle body, according to different embodiments of the present disclosure;

[0111] Fig. 16 Longitudinal sectional view of a forward portion of the nozzle body of Figure 12; Fig. 17 Perspective view of an atomizer base assembled with the nozzle body of the nozzle assembly of Figures 1-4; and

[0112] Fig. 18 Perspective view of the nozzle assembly comprising the nozzle body of Figures 5-7, with some components not shown.

[0113] Detailed Description of the Invention

[0114] Figure 1 is an exploded perspective view of one illustrative embodiment of a liquid spray gun 10 comprising a nozzle assembly 20 as described herein for spraying a liquid 9. The spray gun 10 is a handheld spray gun. The spray gun 10 has a variety of components including a liquid spray gun platform 21 and the nozzle assembly 20 that is - preferably releasably - attached to the spray gun platform 21 at a barrel interface 11. The nozzle assembly 20 provides features that control movement of both the liquid 9 to be sprayed (a liquid paint, for example) and a pressurized atomizing gas (air, for example) used for atomizing the liquid as described herein.

[0115] In some embodiments, the nozzle assembly 20 is disposable and can be thrown away after use (although in some instances it may be reused). If disposed after use, cleaning of the nozzle assembly 20, in some embodiments, can be avoided and the spray gun platform 21 can be conveniently reused, e.g., by attaching a different nozzle assembly 20 connected to the same or a different liquid container. Connection of the nozzle assembly 20 to the barrel interface 11 of the spray gun platform 21 may be achieved by any suitable technique. For example, connection structures on the nozzle assembly 20 may cooperate (e.g., mechanically interlock) with engaging members Ila and 1 lb at the barrel interface 11 to retain the nozzle assembly 20 on the spray gun platform 21.

[0116] The spray gun platform 21 depicted in Figure 1 defines a variety of cavities that, taken together, form passages that deliver the pressurized atomizing gas to the nozzle assembly 20. Among other features, the spray gun platform 21 includes a fitting 12 through which gas supply passages in the spray gun platform 21 can be connected to a gas source (not shown). The gas source supplies the pressurized atomizing gas to the spray gun platform 21 at greater than atmospheric pressure.

[0117] A needle passage is also provided in the spray gun platform 21 to allow a needle 14 to pass into the nozzle assembly 20 attached to the barrel interface 11. Control over both a gas flow and a liquid flow through the spray gun 10, in the depicted embodiment, is provided by a trigger 15 that is pivotally engaged to the spray gun platform 21 by a retaining pin 16a and a clip 16b. The needle 14 extends through the nozzle assembly 20. The trigger 15 is preferably biased to an inoperative position in which the needle 14 closes a liquid nozzle opening in the nozzle assembly 20 and also closes a gas supply valve 17. When the trigger 15 is depressed, the needle 14 is retracted to a position in which its tapered front end 14a allows the liquid 9 to flow through the liquid nozzle opening in the nozzle assembly 20. At the same time, the gas supply valve 17 also opens to deliver the pressurized atomizing gas to the nozzle assembly 20 through the gas supply passages in the spray gun platform 21.

[0118] The gas and liquid flow may be further controlled by a fan gas control assembly 18a which controls a gas delivered to a fan gas passage outlet 19a and to an atomizing gas outlet 19b from a gas supply manifold in the spray gun platform 21, and an atomizing gas control assembly 18b which restricts how far the trigger 15 may be depressed, and thereby, limits the total flow of the atomizing gas and the liquid 9. In particular, the atomizing gas control assembly 18b controls the atomizing gas / liquid stream emanating from the nozzle assembly 20, and the fan gas control assembly 18a controls a gas flow to air horns (if provided) of the nozzle assembly 20. The air horns may be used to adjust a spray pattern geometry.

[0119] The nozzle assembly 20 includes a barrel 30, an air cap 40 attached to the barrel 30, and a first nozzle body 1 attached to a nozzle port on the barrel 30. The first nozzle body 1 may be a separate element as shown in Figure 1, or may form, in conjunction with the air cap 40, an integrated air cap / nozzle body. The term “first nozzle body 1” is interchangeably used herein as “nozzle body 1”.

[0120] Figure 2 illustrates, in a perspective view, the nozzle body 1 of the nozzle assembly 20 according to the present disclosure as it is attached to the barrel 30, which in turn is to be attached at its rear portion 38 to the spray gun platform 21 at the barrel interface 11 shown in Figure 1. The barrel 30 includes a liquid inlet 73 through which the liquid 9 is conducted into the barrel 30 and toward the nozzle body 1. A liquid port connector 74 at the end of the liquid inlet 73 is formed as an engaging structure via which a liquid container (not shown), such as a liquid paint cup, may be connected to the barrel 30.

[0121] The liquid 9 can flow from the liquid container through the liquid inlet 73 and a liquid passage within the barrel 30 into a nozzle tube passage 58 (see Figure 4) of the nozzle body 1. The liquid 9 is dispensed through a plurality of nozzle tube outlets 52 (clearly visible in Figures 5-7) in a front of the nozzle body 1 and exits the nozzle tube passage 58 into outside air 93 in a spray direction 300 along a spray axis 200 which passes through a center of the plurality of nozzle tube outlets 52. A shape of the nozzle body 1 is rotationally symmetric about the spray axis 200.

[0122] The barrel 30 and the nozzle body 1 are shown before the air cap 40 (shown in Figure 1) is arranged over a front portion 36 of the barrel 30. The nozzle assembly 20 further comprises an atomizer base 22 disposed between the nozzle body 1 and the barrel 30. In some embodiments, the atomizer base 22 can be a separate component coupled to the barrel 30. The atomizer base 22 comprises a plurality of atomizing gas channels 23 for conducting a pressurized atomizing gas 110, such that the pressurized atomizing gas 110 flows through the barrel 30 toward the plurality of nozzle tube outlets 52. In some embodiments, the atomizer base 22 and the nozzle body 1 are formed as separate components. The nozzle body 1 is coupled to the atomizer base 22 in a fluid-tight manner.

[0123] Once a suitable air cap 40 is mounted over the front portion 36 and the nozzle body 1, an inner surface of the air cap 40 and an outer surface 75 of the nozzle body 1 cooperate to form an atomizing gas passage 33 (see Figure 4) for conducting the pressurized atomizing gas 110 from the plurality of atomizing gas channels 23 towards an atomizing gas outlet 54 (see Figure 3) arranged circumferentially around the plurality of nozzle tube outlets 52. The plurality of atomizing gas channels 23 conduct the pressurized atomizing gas 110 to the atomizing gas outlet 54.

[0124] Figure 3 illustrates, in a perspective view, the barrel 30 with the air cap 40 mounted over the barrel 30, together forming the nozzle assembly 20. Referring to Figures 2 and 3, the outer surface 75 of the nozzle body 1 at the plurality of nozzle tube outlets 52 (clearly visible in Figures 5-7) forms a first portion of a delimiting surface of the atomizing gas passage 33 (see Figure 4) for conducting the pressurized atomizing gas 110 towards the annular atomizing gas outlet 54 arranged circumferentially around the plurality of nozzle tube outlets 52, such that the atomizing gas 110 exits the atomizing gas passage 33 into the outside air 93 at the atomizing gas outlet 54 and atomizes the liquid 9 after the liquid 9 has exited the plurality of nozzle tube outlets 52. The atomizing gas outlet 54 has an annular shape. Further, the atomizing gas outlet 54 is centered about the spray axis 200 and arranged such as to encircle the plurality of nozzle tube outlets 52.

[0125] In the illustrated embodiment of Figure 3, the air cap 40 comprises two air horns 43a, 43b, arranged radially opposite to each other. However, in alternative embodiments, the air cap 40 may comprise more than two air horns. So-called shaping gas 32 exits the air horns 43a, 43b through two shaping gas apertures 46 on each of the air horns 43a, 43b. The shaping gas apertures 46 are disposed downstream from the atomizing gas outlet 54 with respect to the spray direction 300. The shaping gas apertures 46 on the air horns 43a, 43b are located on opposite sides of the spray axis 200, such that shaping gas 32 flowing through the barrel 30 under greater than atmospheric pressure is directed against opposite sides of a jet of atomized liquid exiting the nozzle assembly 20 into the outside air 93 in the spray direction 300. The forces exerted by the shaping gas 32 can be used to change a shape of the jet of the atomized liquid to form a desired spray pattern (e.g., circular, elliptical, etc.).

[0126] Figure 4 is a longitudinal sectional view of the nozzle assembly 20 of Figure 3 according to the present disclosure. The nozzle body 1 of the nozzle assembly 20 comprises a tubular nozzle tube 66 having a nozzle tube wall 71 which, in this embodiment, has the shape of a funnel narrowing towards the plurality of nozzle tube outlets 52. The nozzle tube wall 71 extends axially forward up to a downstream end 72. The nozzle tube 66 includes the elongated nozzle tube passage 58, extending lengthwise between a nozzle tube inlet 57 and the plurality of nozzle tube outlets 52. In use, exclusively the liquid 9 enters the nozzle tube 66 through the nozzle tube inlet 57. In some embodiments, the nozzle tube inlet 57 may have a circular cross section. The plurality of nozzle tube outlets 52 are fluidically connected with the nozzle tube inlet 57. The plurality of nozzle tube outlets 52 are located at the most downstream extent of the nozzle tube passage 58. Further, the plurality of nozzle tube outlets 52 are located radially within or within the downstream end 72 of the nozzle tube wall 71.

[0127] The liquid 9 to be sprayed flows through the liquid inlet 73, through the barrel 30, and passes from the nozzle tube inlet 57, through the elongated nozzle tube passage 58, to the plurality of nozzle tube outlets 52 through which, in use, exclusively the liquid 9 exits the nozzle tube passage 58 into the outside air 93 in the spray direction 300 along the spray axis 200. The length direction of the nozzle tube passage 58 defines an axial direction 220 and a radial direction 210 orthogonal to the axial direction 220. The spray direction 300 is the axial direction 220.

[0128] The liquid 9 may flow through the nozzle tube passage 58 with a liquid pressure of less than 50 pounds per square inch (psi) [345 kPa], and preferably less than 5 psi [35kPa]. In some other embodiments, the liquid pressure of the liquid 9 in the nozzle tube passage 58 is not more than a hydrostatic pressure of the liquid 9 in an attached liquid container (not shown).

[0129] The rear portion 38 of barrel 30 can be attached to the spray gun platform 21 at the barrel interface 11 (shown in Figure 1), such that the spray gun platform 21 and the nozzle assembly 20 together form a complete spray gun 10.

[0130] Once connected with the nozzle body 1, the air cap 40 is in fixed spatial relation with the nozzle body 1. Further, the air cap 40 is rotationally symmetric about the spray axis 200. The air cap 40 comprises a front wall 60 which faces generally in the spray direction 300. The front wall 60 forms a circular nozzle aperture 70 delimited by a nozzle aperture edge 64. The nozzle aperture edge 64 is arranged radially outward from the downstream end 72 of the nozzle tube wall 71. In this embodiment, the downstream end 72 of the nozzle tube wall 71 of the nozzle tube 66 is arranged in the nozzle aperture 70 delimited by the nozzle aperture edge 64 of the front wall 60, such that the plurality of nozzle tube outlets 52 are almost flush with a front surface 62 of the air cap 40 which faces generally in the spray direction 300.

[0131] The atomizing gas outlet 54 is formed between the nozzle aperture edge 64 of the front wall 60 of the air cap 40 and the outer surface 75 of the nozzle tube wall 71 circumferentially around the plurality of nozzle tube outlets 52. An inner surface of the air cap 40 and the outer surface 75 of the nozzle tube wall 71 cooperate to form the atomizing gas passage 33 for conducting the pressurized atomizing gas 110 towards the atomizing gas outlet 54. The atomizing gas outlet 54 therefore has an annular shape and is arranged circumferentially around the plurality of nozzle tube outlets 52.

[0132] Figure 5 is a longitudinal sectional view of a forward portion of the nozzle body 1 of Figure 4. The nozzle body 1 comprises the nozzle tube 66, which in turn comprises the elongated nozzle tube passage 58, extending lengthwise between the nozzle tube inlet 57 (shown in Figure 4) through which, in use, the liquid 9 enters the nozzle tube 66, and the plurality of nozzle tube outlets 52 arranged in an outlet surface 330, through which, in use, the liquid 9 exits the nozzle tube passage 58 into the outside air 93 in the spray direction 300. The geometric shape of each nozzle tube outlet 52 shown in Figure 5 is just an example, and many other geometries can be used that would still yield the advantageous effect of the invention.

[0133] The plurality of nozzle tube outlets 52 define the precise axial position (indicated by the outlet surface 330) at which the liquid 9 exits the nozzle tube passage 58 into the outside air 93. Each nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 is formed at a downstream end of an outlet channel 84 through an outlet wall 85. The outlet wall 85 is a terminal portion of the nozzle tube wall 71. The outlet channel 84 is an intermediate channel between the nozzle tube passage 58 and the plurality of nozzle tube outlets 52 disposed in the outlet surface 330. In use, the outlet channel 84 conducts the liquid 9 from the nozzle tube passage 58 to the plurality of nozzle tube outlets 52.

[0134] In the illustrated embodiment of Figure 5, the outlet surface 330 is a planar surface or a flat surface. However, in some other embodiments, the outlet surface 330 may be non-planar. For example, the outlet surface 330 may be domed, tapered (inward or outward), concave / convex, or irregular.

[0135] In the embodiment of Figure 5, the nozzle tube 66 is rotationally symmetric about the spray axis 200, such that the length direction of the nozzle tube passage 58 and the spray direction 300 are both parallel to the spray axis 200. The nozzle tube 66 also comprises the nozzle tube wall 71 which comprises the radially outer surface 75 and an opposed radially inner surface 76. The inner surface 76 delimits the nozzle tube passage 58 and is in contact with the liquid 9 when the nozzle body 1 and the spray gun 10 (shown in Figure 1) to which it is mounted are in use. In the illustrated embodiment of Figure 5, the downstream end 72 of the nozzle tube wall 71 is arranged in the outlet surface 330.

[0136] The spray axis 200 is defined in an axial direction through a centroid 310 of the plurality of nozzle tube outlets 52. A direction through the centroid 310 of the plurality of nozzle tube outlets 52 along the spray axis 200 away from the nozzle body 1 defines the spray direction 300. The plurality of nozzle tube outlets 52 are arranged around the spray axis 200. In the illustrated embodiment, the centroid 310 of the plurality of nozzle tube outlets 52 lies on the outlet surface 330 since the outlet surface 330 is a planar surface. However, in other embodiments where the outlet surface 330 is a non-planar surface, the centroid 310 of the plurality of nozzle tube outlets 52 may not necessarily lie on the outlet surface 330.

[0137] In some embodiments, in use, the liquid 9 exits the plurality of nozzle tube outlets 52 along the spray direction 300, i.e., parallel to the axial direction 220. In some embodiments, in use, the liquid 9 exits the plurality of nozzle tube outlets 52 into the outside air 93 in directions oriented within an angle of 45 degrees (°) from the axial direction 220. It should be noted that the liquid 9 may exit the plurality of nozzle tube outlets 52 in multiple directions with respect to the axial direction 220. For example, in certain embodiments, at least a portion of the liquid 9 may exit the plurality of nozzle tube outlets 52 into the outside air 93 in directions oriented within an angle of 45° from the axial direction 220, and at least another portion of the liquid 9 may exit the plurality of nozzle tube outlets 52 into the outside air 93 in the axial direction 220. Turbulence may introduce irregular velocities into the liquid 9 only a short time after the liquid 9 has exited the plurality of nozzle tube outlets 52 and only at positions somewhat downstream from the outlet surface 330 of the plurality of nozzle tube outlets 52.

[0138] Figure 6 is a front view of the plurality of nozzle tube outlets 52. The outlet surface 330 (shown in Figure 5) is the plane of the paper. The geometric shape of each nozzle tube outlet 52 shown in Figure 6 is just an example, and many other geometries can be used that would still yield the advantageous effect of the invention. In the illustrated embodiment of Figure 6, in the outlet surface 330, all nozzle tube outlets 52 of the plurality of nozzle tube outlets 52 have an identical shape and an identical size. However, in alternative embodiments, the one or more nozzle tube outlets 52 of the plurality of nozzle tube outlets 52 may be non-identical.

[0139] A center point or a center of the plurality of nozzle tube outlets 52 is referred to herein as the centroid 310. The centroid 310 of the plurality of nozzle tube outlets 52 is an arithmetic mean position of cross sections of the plurality of nozzle tube outlets 52 in the outlet surface 330. In the illustrated embodiment of Figure 6, the centroid 310 of the plurality of nozzle tube outlets 52 in the outlet surface 330 is located outside of any nozzle tube outlet 52 of the plurality of nozzle tube outlets 52.

[0140] In the outlet surface 330, a cross section of at least one nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 has an area of between 0.15 square millimeters and 1.2 square millimeters. The preferred area of the cross section may be chosen based on parameters, such as a desired liquid flow rate, atomization quality, etc.

[0141] In the outlet surface 330, a cross section of at least one nozzle tube outlet 52, or each nozzle tube outlet 52 of the plurality of nozzle tube outlets 52, is delimited by a perimeter line 77 comprising at least a curved line segment 78 and a straight line segment 79. The perimeter line 77 defines a shape of the at least one nozzle tube outlet 52 in the outlet surface 330.

[0142] Generally, three, four, five, six, seven or eight or more nozzle tube outlets 52 of the plurality of nozzle tube outlets 52 may be arranged, in the outlet surface 330, symmetrically about a spray center 320 as wedge-shaped segments combining, in the outlet surface 330, to form a circle centered about the spray center 320. In the exemplary embodiment of Figure 6, six nozzle tube outlets 52 of the plurality of nozzle tube outlets 52 are arranged in the outlet surface 330 symmetrically about the spray center 320. In the illustrated embodiment of Figure 6, the spray center 320 coincides with the centroid 310 of the plurality of nozzle tube outlets 52. Further, the spray center 320 is disposed in the outlet surface 330.

[0143] In the outlet surface 330, the wedge-shaped segments have a cross section in the shape of a sector of a circular disc. An included angle of the sector of the circular disc can be acute, obtuse, or 90 degrees (°). A geometric center of the wedge-shaped segments of the plurality of nozzle tube outlets 52, i.e., the spray center 320, is centered on the spray axis 200 shown in Figure 5.

[0144] Each two adjacent nozzle tube outlets 52 of the three, four, five, six, seven or eight nozzle tube outlets 52 are separated by a respective strut 80 of a plurality of struts 80. The plurality of struts 80 meet at the spray center 320. The plurality of struts 80 form the plurality of nozzle tube outlets 52 in the outlet surface 330. In the outlet surface 330, each strut 80 extends from the spray center 320 to a radially outermost edge of the corresponding adjacent nozzle tube outlets 52. In the illustrated embodiment of Figure 6, each strut 80 of the plurality of struts 80 is straight. However, in alternative embodiments, one or more struts 80 of the plurality of struts 80 can be curved, or at least partially curved. In some embodiments, the plurality of struts 80 are integrally formed with the nozzle body 1.

[0145] In some embodiments, the plurality of struts 80 are comprised in a strut assembly 82. Further, the strut assembly 82 is formed as a single piece. For example, the strut assembly 82 is a single-piece component integrally formed with the plurality of struts 80. In the illustrated embodiment, the strut assembly 82 and at least one other portion 83 of the nozzle body 1 are integrally formed as a single piece component. In some embodiments, the at least one other portion 83 of the nozzle body 1 may be a main portion of the nozzle body 1.

[0146] Figure 7 is a detailed perspective view of the plurality of nozzle tube outlets 52 of the nozzle body 1 of Figures 1-6. The geometric shape of each nozzle tube outlet 52 shown in Figure 7 is just an example, and many other geometries can be used that would still yield the advantageous effect of the invention. In the illustrated embodiment of Figure 7, each strut 80 of the plurality of struts 80 extends, in the axial direction 220, by 3 millimeters or less. In certain embodiments, each strut 80 extends in the axial direction 220 by 2.5 millimeters, or 2 millimeters, or 1.5 millimeters, or 1 millimeter, or by 0.5 millimeters. In certain embodiments, each strut 80 extends in the axial direction 220 by at least 0.12 millimeters.

[0147] Preferably, each strut 80 extends in the axial direction 220 by 0.38 millimeters.

[0148] In certain embodiments, each strut 80 extends by 3 millimeters or less in the radial direction 210 with respect to the spray axis 200, as measured in the outlet surface 330. In certain embodiments, each strut 80 extends, in the outlet surface 330, in the radial direction 210 by 2.5 millimeters, or 2 millimeters, or 1.5 millimeters, or 1 millimeter, or by 0.5 millimeters. In certain embodiments, each strut 80 extends, in the outlet surface 330, in the radial direction 210 by at least 0.25 millimeters. Preferably, each strut extends in the radial direction 210 by 1 millimeter.

[0149] In certain embodiments, a width 96 of each strut 80 in the outlet surface 330 is 3 millimeters or less. In certain embodiments, the width 96 of each strut 80 in the outlet surface 330 is 2.5 millimeters, or 2 millimeters, or 1.5 millimeters, or 1 millimeter, or 0.5 millimeters. In certain embodiments, the width 96 of each strut 80 is at least 0.12 millimeters. Preferably, the width 96 of each strut is 0.29 millimeters.

[0150] Each nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 is formed at a downstream end of the outlet channel 84 through the outlet wall 85. In the illustrated embodiment of Figure 7, the outlet channel 84 is radially delimited by a channel wall 86 extending axially from a channel wall rear end 87 to a channel wall front end 88 arranged in the outlet surface 330. The channel wall rear end 87 is a upstream end of the channel wall 86 and the channel wall front end 88 is a downstream end of the channel wall 86. “Upstream” refers to a position located in a direction opposite to the spray direction 300.

[0151] The outlet channel 84 upstream from at least one nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 has a diverging axial section 89 in which a cross section of the outlet channel 84 increases towards the outlet surface 330. A cross sectional area of the outlet channel 84 at the channel wall front end 88 is greater than a cross sectional area of the outlet channel 84 at the channel wall rear end 87. A surface of the diverging axial section 89 guides and directs the liquid 9 received from the nozzle tube passage 58 (shown in Figure 5) radially away from the spray axis 200 in thin layers towards a radially outermost portion of the corresponding nozzle tube outlet 52.

[0152] Figure 8 is a detailed exploded perspective view of the nozzle body 1 of Figures 1-7 and the strut assembly 82, according to an embodiment of the present disclosure. In the illustrated embodiment of Figure 8, the strut assembly 82 and the at least one other portion 83 of the nozzle body 1 are formed as separate pieces. Thus, the strut assembly 82 and at least one other portion 83 of the nozzle body 1 are manufactured separately. Optionally the strut assembly 82 can be attached to the at least one other portion 83 of the nozzle body 1, such as by welding, interference fit, over molding, or insert molding. Other suitable fabrication techniques may also be employed for joining the strut assembly 82 with the at least one other portion 83 of the nozzle body 1.

[0153] Figure 9 is a further longitudinal sectional view of the forward portion of the nozzle body 1 of Figures 4-8 and a forward portion of the air cap 40 (shown in Figure 4). The geometric shape of each nozzle tube outlet 52 shown in Figure 9 is just an example, and many other geometries can be used that would still yield the advantageous effect of the invention.

[0154] The air cap 40 is rotationally symmetric about the spray axis 200. It is connected with the nozzle body 1 via a barrel 30 (shown in Figures 1-4), to which both the nozzle body 1 and the air cap 40 are connected, in a fixed spatial relation, such that the atomizing gas outlet 54 is radially -outwardly delimited by the nozzle aperture edge 64 and radially -inwardly delimited by the nozzle tube wall 71 adjacent the plurality of nozzle tube outlets 52.

[0155] The air cap 40 has the front wall 60 which forms the nozzle aperture 70 delimited by the nozzle aperture edge 64. The forward end of the nozzle tube 66 is arranged in the nozzle aperture 70 of the front wall 60, such that the plurality of nozzle tube outlets 52 protrudes forward, in the spray direction 300, by a small distance from the front surface 62 of the air cap 40. Thus, in the illustrated embodiments of Figure 9, the nozzle aperture edge 64 is arranged upstream from the outlet surface 330. However, in alternative embodiments, the nozzle aperture edge 64 can also be arranged in the outlet surface 330. In such embodiments, the nozzle aperture edge 64 is aligned and coplanar with the plurality of nozzle tube outlets 52.

[0156] The outer surface 75 of the nozzle tube wall 71 guides the pressurized atomizing gas 110 towards the atomizing gas outlet 54. The outer surface 75 of the nozzle tube wall 71 may exhibit curvature discontinuities (e.g. steps, comers, etc.) as shown in Figure 9. It is contemplated that, in some alternative embodiments, the outer surface 75 may have a continuous curvature, such as a circular, parabolic, or hyperbolic curvature, for example.

[0157] The outer surface 75 of the nozzle tube wall 71 is operable to form, in conjunction with a surface of the air cap 40 when the air cap 40 is connected directly or indirectly with the nozzle body 1, the atomizing gas outlet 54 arranged circumferentially around the plurality of nozzle tube outlets 52, such that, in use, the pressurized atomizing gas 110 exits into the outside air 93 through the atomizing gas outlet 54 and atomizes the liquid 9 after the liquid 9 has exited the plurality of nozzle tube outlets 52. Specifically, the atomizing gas outlet 54 is formed between the nozzle aperture edge 64 of the front wall 60 and the radially outer surface 75 of the nozzle tube wall 71 adjacent the plurality of nozzle tube outlets 52. The atomizing gas outlet 54 therefore has an annular shape and is arranged circumferentially around the plurality of nozzle tube outlets 52.

[0158] The liquid 9 that passes through the nozzle tube passage 58 exits through the plurality of nozzle tube outlets 52. A surface of the diverging axial section 89 of the channel wall 86 of at least one nozzle tube outlet 52 allows at least a portion of the liquid 9 received from the nozzle tube passage 58 to flow radially outward from the channel wall rear end 87 to the channel wall front end 88. The surface of the diverging axial section 89 guides and directs the liquid 9 received from the nozzle tube passage 58 radially away from the spray axis 200 towards the atomizing gas outlet 54 arranged circumferentially around the nozzle tube wall 71 adjacent the plurality of nozzle tube outlets 52. This allows the liquid 9 to be directed closer to the pressurized atomizing gas 110, such that the liquid 9 is sheared off at the plurality of nozzle tube outlets 52 and atomized by the flow of the pressurized atomizing gas 110. The diverging axial section 89 of the outlet channel 84 biases the liquid 9 towards the atomizing gas 110, thereby increasing an interaction between the atomizing gas 110 and the liquid 9 resulting in improved atomization. In other words, the channel wall 86 is preferentially skewed towards the outer surface 75 of the nozzle tube wall 71.

[0159] It should be noted that some portion of the liquid 9 may still exit through the plurality of nozzle tube outlets 52 in the spray direction 300. This portion of the liquid 9 shall still be atomized by the pressurized atomizing gas 110 exiting through the atomizing gas outlet 54 into the outside air 93.

[0160] The outer surface 75 of the nozzle tube wall 71 at the nozzle tube outlet 52 (i.e., in the outlet surface 330) is oriented radially outwardly to direct at least a portion of the pressurized atomizing gas 110 exiting the atomizing gas outlet 54 angularly away or “diverging” from the spray axis 200. This diverging flow of the atomizing gas 110 causes a pressure of the outside air 93 at the plurality of nozzle tube outlets 52 to be lower than in traditional nozzle geometries in which an atomizing gas flows in directions parallel to the spray axis 200 or towards the spray axis 200. In the embodiment of Figure 9, the lower pressure at the plurality of nozzle tube outlets 52 draws more liquid 9 from the nozzle tube passage 58 and increases a flow rate of the liquid 9, compared to traditional nozzle assemblies, assuming identical pressure of the supplied pressurized atomizing gas 110.

[0161] In the embodiment of Figure 9, the outer surface 75 of the nozzle tube wall 71 at the nozzle tube outlet 52 appears “ramped” in the longitudinal sectional view. This section is referred to herein as a ramped axial section 90. The ramped axial section 90 provides the flow of pressurized atomizing gas 110 with a radial velocity component angularly away from the spray axis 200 and angularly away from the jet of the liquid 9 flowing in the spray direction 300. Due to the rotational symmetry of the nozzle body 1 about the spray axis 200, the ramped axial section 90 in the sectional view of Figure 9 corresponds to a conical axial section of the outer surface 75 of the nozzle tube wall 71 adjacent the plurality of nozzle tube outlets 52, where a larger-diameter end of the conical axial section is located at the axial position of the plurality of nozzle tube outlets 52 (i.e., in the outlet surface 330), and a smaller-diameter end of the conical axial section is located upstream from the plurality of nozzle tube outlets 52. “Upstream” refers to a position located in a direction opposite to the spray direction 300. In the embodiment of Figure 9, the ramped axial section 90 appears as a straight line in the longitudinal sectional view. It is contemplated that, in alternative embodiments, the ramped axial section 90 may be a curved line in the longitudinal sectional view.

[0162] In the embodiment of Figure 9, a cylindrical surface 68 extends axially rearward / upstream from the nozzle aperture edge 64. This cylindrical surface 68 directs a portion of the pressurized atomizing gas 110 exiting the atomizing gas outlet 54 in a direction parallel to the spray axis 200. This geometry still permits other portions of the atomizing gas 110 to be directed (e.g., by the ramped axial section 90 of the outer surface 75 of the nozzle tube wall 71) angularly away from the spray axis 200. This may allow the pressure of the outside air 93 at the plurality of nozzle tube outlets 52 to be lower than in traditional nozzle geometries in which no portion of the atomizing gas 110 flows angularly away from the spray axis 200.

[0163] Figures 10 illustrates a detailed perspective view of a second nozzle body 2, according to another embodiment of the present disclosure. Figure 11 is a longitudinal sectional view of a forward portion of the second nozzle body 2 of Figure 10. The second nozzle body 2 is similar to the first nozzle body 1 of Figures 1-9 and similar reference numerals are used to indicate same or similar components, and only differences between the embodiments are discussed hereinafter in detail. The geometric shape of each nozzle tube outlet 52 shown in Figures 10 and 11 is just an example, and many other geometries can be used that would still yield the advantageous effect of the invention. The term “second nozzle body 2” is interchangeably used herein as “the nozzle body 2”.

[0164] In the illustrated embodiment of Figures 10 and 11, the outlet surface 330 (shown in Figure 11) is curved or dome shaped. Alternatively, the outlet surface 330 may be tapered or conical shaped with outward tapered or inward tapered surface. All nozzle tube outlets 52 of the plurality of nozzle tube outlets 52 have an identical shape and an identical size in the outlet surface 330. Further, six nozzle tube outlets 52 of the plurality of nozzle tube outlets 52 are arranged in the outlet surface 330 symmetrically about the spray center 320. The plurality of nozzle tube outlets 52 are separated by the plurality of struts 80. The plurality of struts 80 meet at the spray center 320. Each stmt 80 of the plurality of struts 80 is at least partially curved. In the exemplary embodiment of Figures 10 and 11, the plurality of nozzle tube outlets 52 are arranged in the outlet surface 330. Each nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 is formed at a downstream end of the outlet channel 84 through the outlet wall 85. In use, the outlet channel 84 conducts the liquid 9 from the nozzle tube passage 58 to the plurality of nozzle tube outlets 52. The outlet channel 84 is radially delimited by the channel wall 86 extending axially from the channel wall rear end 87 to the channel wall front end 88 arranged in the outlet surface 330. The outlet channel 84 upstream from at least one nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 has the diverging axial section 89 in which the cross section of the outlet channel 84 increases towards the outlet surface 330.

[0165] Figure 12 illustrates a detailed perspective view of a third nozzle body 3, according to another embodiment of the present disclosure. The third nozzle body 3 is similar to the first nozzle body 1 of Figures 1-9 and similar reference numerals are used to indicate same or similar components, and only differences between the embodiments are discussed hereinafter in detail. The geometric shape of each nozzle tube outlet 52 shown in Figure 12 is just an example, and many other geometries can be used that would still yield the advantageous effect of the invention. The term “third nozzle body 3” is interchangeably used herein as “the nozzle body 3”.

[0166] In the illustrated embodiment of Figure 12, the nozzle body 3 comprises the tubular nozzle tube 66 with the plurality of nozzle tube outlets 52 through which, in use, the liquid 9 exits into the outside air 93. A cross sectional shape of each nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 is polygonal with four sides. However, in alternative embodiments, other polygonal shapes may also be utilized.

[0167] In the illustrated embodiment of Figure 12, in the outlet surface 330 orthogonal to the spray axis 200, each two adjacent nozzle tube outlets 52 of the plurality of nozzle tube outlets 52 are separated by a respective strut 97 of a plurality of struts 97. The plurality of struts 97 meet at a central portion 98. Each nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 protrude radially outward from the central portion 98.

[0168] In the outlet surface 330, the plurality of struts 97 are evenly distributed around the central portion 98 or the spray axis 200. In the illustrated embodiment of Figure 12, the plurality of struts 97 include six struts 97, and therefore, a difference in an angular position of two adjacent struts 97 is 60 degrees.

[0169] Similarly, in the outlet surface 330, the plurality of nozzle tube outlets 52 are evenly distributed around the central portion 98 or the spray axis 200. In the illustrated embodiment of Figure 12, the plurality of nozzle tube outlets 52 include six nozzle tube outlets 52.

[0170] In the outlet surface 330, the outer surface 75 of the nozzle tube wall 71 forms a plurality of recesses 94 receding radially inward towards the spray axis 200. In the outlet surface 330, the plurality of recesses 94 are evenly distributed around the central portion 98 or the spray axis 200, such that each recess 94 of the plurality of recesses 94 is located angularly between a respective two adjacent nozzle tube outlets 52 of the plurality of nozzle tube outlets 52. In the illustrated embodiment of Figure 12, the plurality of recesses 94 include six recesses 97. In use, the atomizing gas 110 exits into the outside air 93 through the plurality of recesses 94 when the air cap 40 is connected with the nozzle body 3 in a fixed spatial relation, as shown, for example, in Figure 4.

[0171] The plurality of recesses 94 are located at forward ends of respective grooves 95 which extend forward in the spray direction 300 from a rearward position up to the plurality of recesses 94 in the outlet surface 330, such that each groove 95 extends forward in the spray direction 300 from the rearward position to the respective recess 94 in the outlet surface 330. When the air cap 40 (shown in Figures 1-4) is connected and the liquid spray gun 10 (shown in Figure 1) is used, the pressurized atomizing gas 110 flows forward through the grooves 95 to the plurality of recesses 94 where it exits into the outside air 93 and atomizes the liquid 9 after the liquid 9 has exited the plurality of nozzle tube outlets 52.

[0172] In the illustrated embodiment of Figure 12, each nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 is formed at a downstream end of the outlet channel 84 through the outlet wall 85. The outlet channel 84 is radially delimited by the channel wall 86 extending axially from the channel wall rear end 87 to the channel wall front end 88 arranged in the outlet surface 330. The outlet channel 84 upstream from at least one nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 has the diverging axial section 89 in which a cross section of the outlet channel 84 increases towards the outlet surface 330. In other words, a cross sectional area of the outlet channel 84 at the channel wall front end 88 is greater than a cross sectional area of the outlet channel 84 at the channel wall rear end 87. Further, the channel wall 86 is inclined obliquely with respect to the spray axis 200.

[0173] Figure 13 illustrates a detailed perspective view of a fourth nozzle body 4, according to another embodiment of the present disclosure. The fourth nozzle body 4 is similar to the first nozzle body 1 of Figures 1-9 and similar reference numerals are used to indicate same or similar components, and only differences between the embodiments are discussed hereinafter in detail. The geometric shape of each nozzle tube outlet 52 shown in Figure 13 is just an example, and many other geometries can be used that would still yield the advantageous effect of the invention. The term “fourth nozzle body 4” is interchangeably used herein as “the nozzle body 4”.

[0174] In the illustrated embodiment of Figure 13, the nozzle body 4 comprises the tubular nozzle tube 66 with the plurality of nozzle tube outlets 52 though which, in use, the liquid 9 exits into the outside air 93. Each nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 has a circular cross section in the outlet surface 330. In the illustrated embodiment of Figure 13, six nozzle tube outlets 52 are arranged circularly around a central nozzle tube outlet 52. The spray axis 200 passes through the central nozzle tube outlet 52.

[0175] Each nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 is formed at a downstream end of the outlet channel 84 through the outlet wall 85. The outlet channel 84 is radially delimited by the channel wall 86 extending axially from the channel wall rear end 87 to the channel wall front end 88 arranged in the outlet surface 330. The outlet channel 84 upstream from at least one nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 has the diverging axial section 89 in which a cross section of the outlet channel 84 increases towards the outlet surface 330. In other words, a cross sectional area of the outlet channel 84 at the channel wall front end 88 is greater than a cross sectional area of the outlet channel 84 at the channel wall rear end 87. Further, the channel wall 86 is inclined obliquely with respect to the spray axis 200.

[0176] Figure 14 illustrates a detailed perspective view of a fifth nozzle body 5, according to another embodiment of the present disclosure. The fifth nozzle body 5 is similar to the first nozzle body 1 of Figures 1-9 and similar reference numerals are used to indicate same or similar components, and only differences between the embodiments are discussed hereinafter in detail. The geometric shape of each nozzle tube outlet 52 shown in Figure 14 is just an example, and many other geometries can be used that would still yield the advantageous effect of the invention. The term “fifth nozzle body 5” is interchangeably used herein as “the nozzle body 5”.

[0177] In the illustrated embodiment of Figure 14, the nozzle body 5 comprises the tubular nozzle tube 66 with the plurality of nozzle tube outlets 52 though which, in use, the liquid 9 exits into the outside air 93. Each nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 has a circular cross section in the outlet surface 330. Six nozzle tube outlets 52 are arranged circularly around a central nozzle tube outlet 52. The spray axis 200 passes through the central nozzle tube outlet 52. As compared to the plurality of nozzle tube outlets 52 of Figure 13, each nozzle tube outlet 52 of Figure 14 does not include the diverging axial section 89 (shown in Figure 13). In other words, a channel wall of an outlet channel of each nozzle tube outlet 52 is generally aligned with the spray axis 200.

[0178] Figure 15 illustrates a detailed perspective view of a sixth nozzle body 6, according to another embodiment of the present disclosure. The sixth nozzle body 5 is similar to the first nozzle body 1 of Figures 1-9 and similar reference numerals are used to indicate same or similar components, and only differences between the embodiments are discussed hereinafter in detail. The geometric shape of each nozzle tube outlet 52 shown in Figure 15 is just an example, and many other geometries can be used that would still yield the advantageous effect of the invention. The term “sixth nozzle body 6” is interchangeably used herein as “the nozzle body 6”. In the illustrated embodiment of Figure 15, the nozzle body 6 comprises the tubular nozzle tube 66 with the plurality of nozzle tube outlets 52 though which, in use, the liquid 9 exits into the outside air 93. Each nozzle tube outlet 52 of the plurality of nozzle tube outlets 52 has an oval cross section in the outlet surface 330 (see Figure 14). In other words, a cross section of each nozzle tube outlet 52 of Figure 15 is elongated in the outlet surface 330 (and not circular) as compared to the plurality of nozzle tube outlets 52 of Figures 13 and 14. The plurality of nozzle tube outlets 52 are symmetrically arranged about the spray axis 200. Specifically, the plurality of nozzle tube outlets 52 are arranged in a circle around the spray axis 200.

[0179] Figure 16 is a longitudinal sectional view of a forward portion of the nozzle body 6 of Figure 15. Referring to Figures 15 and 16, in the illustrated embodiment, the downstream end 72 of the nozzle tube wall 71 is arranged downstream from the outlet surface 330. In other words, the plurality of nozzle tube outlets 52 are disposed upstream from the downstream end 72 of the nozzle tube wall 71. Thus, as compared to the plurality of nozzle tube outlets 52 of Figures 13 and 14, the plurality of nozzle tube outlets 52 of Figures 15 and 16 are arranged upstream from the downstream end 72 of the nozzle tube wall 71.

[0180] It should be noted that each of the various nozzle bodies 1, 2, 3, 4, 5, 6 described above and shown in the various figures can be combined with a barrel (e.g., the barrel 30 shown in Figures 1-4) and an air cap (e.g., the air cap 40 shown in Figures 1, 3, 4 and 9) to form a nozzle assembly (e.g., the nozzle assembly 20 shown in Figures 1, 3 and 4).

[0181] Figure 17 illustrates, in a perspective view, the first nozzle body 1 according to the present disclosure as it is attached to the atomizer base 22, which in turn is to be attached to the barrel 30 at its front portion 36 (as shown in Figures 1-4), or may be attached directly to a spray gun body. In some embodiments, the atomizer base 22 is a separate component coupled to the nozzle body 1.

[0182] The atomizer base 22 comprises the plurality of atomizing gas channels 23 for conducting the pressurized atomizing gas 110 (shown in Figure 9), such that the pressurized atomizing gas 110 flows through the barrel 30 toward the plurality of nozzle tube outlets 52. The nozzle body 1 is coupled to the atomizer base 22 in a fluid-tight manner. The atomizer base 22 further comprises a liquid aperture 92 for conducting the liquid 9 into the nozzle body 1. The atomizer base 22 is secured to the nozzle body 1, such that the liquid 9 can flow through the liquid aperture 92 into the nozzle tube inlet 57 (shown in Figure 4). The geometric shape of each nozzle tube outlet 52 shown in Figure 17 is just an example, and many other geometries can be used that would still yield the advantageous effect of the invention. Figure 18 illustrates, in a perspective view, a nozzle assembly 400, with some components not shown. For example, an air cap of the nozzle assembly 400 is not shown for illustrative and descriptive purposes. In some embodiments, the nozzle body 1 of the present disclosure may also be used with other types of nozzle assemblies, such as the nozzle assembly 400. The nozzle assembly 400 comprises an atomizer 24, such as an atomizer with the atomizer base 22 (shown Figures 2 and 14). The nozzle body 1 can be coupled to the atomizer 24 in a fluid-tight manner or formed integrally with the atomizer 24. The nozzle assembly 400 can be fluidly coupled to a container 25 that encloses a liquid (e.g., a paint) to be sprayed. The atomizer 24 dispenses a pressurized atomizing gas that atomizes the liquid after the liquid has exited the nozzle body 1.

Claims

CLAIMS1. Nozzle assembly (20) for a liquid spray gun (10) for spraying a liquid (9), the nozzle assembly (20) comprising:a) a nozzle body (1, 2, 3, 4, 5, 6) including a tubular nozzle tube (66) having:i) an elongated nozzle tube passage (58), extending lengthwise between a nozzle tube inlet (57) through which, in use, exclusively the liquid (9) enters the nozzle tube (66), and a plurality of nozzle tube outlets (52) arranged in an outlet surface (330), through which, in use, exclusively the liquid exits the nozzle tube passage (58) into outside air (93), wherein the plurality of nozzle tube outlets (52) are fluidically connected with the nozzle tube inlet (57), wherein the length direction of the nozzle tube passage (58) defines an axial direction (220) and a radial direction (210) orthogonal to the axial direction (220), andii) a nozzle tube wall (71) which extends axially forward up to a downstream end (72), and which has a radially outer surface (75) for guiding a pressurized atomizing gas (110), and an opposed radially inner surface (76) delimiting the nozzle tube passage (58) and being, in use, in contact with the liquid (9), andb) an air cap (40), connected with the nozzle body (1, 2, 3, 4, 5, 6) in a fixed spatial relation, wherein the air cap (40) comprises a front wall (60) which faces generally in a spray direction (300) and comprises a nozzle aperture (70) delimited by a nozzle aperture edge (64), the nozzle aperture edge (64) being arranged radially outward from the downstream end (72) of the nozzle tube wall (71), wherein between the nozzle aperture edge (64) and the outer surface (75) of the nozzle tube wall (71), an atomizing gas outlet (54) is formed circumferentially around the plurality of nozzle tube outlets (52), such that, in use, the pressurized atomizing gas (110) exits into the outside air (93) through the atomizing gas outlet (54) and atomizes the liquid (9) after the liquid (9) has exited the plurality of nozzle tube outlets (52).

2. Nozzle assembly (20) according to claim 1, wherein the nozzle aperture edge (64) is arranged in the outlet surface (330) or upstream from the outlet surface (330).

3. Nozzle assembly (20) according to any one of claims 1-2, wherein each nozzle tube outlet (52) of the plurality of nozzle tube outlets (52) is formed at a downstream end of an outlet channel (84) through an outlet wall (85), wherein the outlet channel (84) is radially delimited by a channel wall (86) extending axially from a channel wall rear end (87) to a channel wall front end (88) arranged in the outlet surface (330), and wherein the outlet channel (84) upstream from at least one nozzle tube outlet (52) of the plurality of nozzle tube outlets (52) has a diverging axial section (89) in which a cross section of theoutlet channel (84) increases towards the outlet surface (330).

4. Nozzle assembly (20) according to any one of claims 1-3, wherein at least one nozzle tube outlet (52) of the plurality of nozzle tube outlets (52) has a circular cross section in the outlet surface (330).

5. Nozzle assembly (20) according to any one of claims 1-4, wherein three, four, five, six, seven or eight nozzle tube outlets (52) of the plurality of nozzle tube outlets (52) are arranged, in the outlet surface (330), symmetrically about a spray center (320) as wedge-shaped segments combining, in the outlet surface (330), to form a circle centered about the spray center (320), wherein each two adjacent nozzle tube outlets (52) of the three, four, five, six, seven or eight nozzle tube outlets (52) are separated by a respective strut (80) of a plurality of struts(80), and wherein the plurality of struts (80) meet at the spray center (320).

6. Nozzle assembly (20) according to claim 5, wherein each strut (80) of the plurality of struts (80) extends, in an axial direction, by 3 millimeters or less.

7. Nozzle assembly (20) according to claim 5 or claim 6, wherein the plurality of struts (80) are comprised in a strut assembly (82), the strut assembly (80) being formed as a single piece, wherein the strut assembly (82) and at least one other portion (83) of the nozzle body (1, 2, 3, 4, 5, 6) are formed as separate pieces, and wherein optionally the strut assembly (82) is attached to the at least one other portion (83) of the nozzle body (1, 2, 3, 4, 5, 6), such as by welding or by a press-fit.

8. Nozzle assembly (20) according to any one of claims 1-7, wherein, in the outlet surface (330), a cross section of at least one nozzle tube outlet (52) of the plurality of nozzle tube outlets (52) has an area of between 0.15 square millimeters and 1.2 square millimeters.

9. Nozzle assembly (20) according to any one of claims 1-8, wherein the downstream end (72) of the nozzle tube wall (71) is arranged in the outlet surface (330) or downstream from the outlet surface (330).

10. Nozzle assembly (20) according to any one of claims 1-9, wherein a spray axis (200) is defined as an axial direction through a centroid (310) of the plurality of nozzle tube outlets (52), and wherein the outer surface (75) of the nozzle tube wall (71) at the atomizing gas outlet (54) is oriented or shaped to direct at least a portion of the pressurized atomizing gas (110) exiting through the atomizing gas outlet (54) into the outside air (93) angularly away from the spray axis (200).

11. Nozzle assembly (20) according to any one of claims 1-10, wherein a centroid (310) of the plurality of nozzle tube outlets (52) in the outlet surface (330) is located outside of any nozzle tube outlet (52) of the plurality of nozzle tube outlets (52).

12. Nozzle assembly (20) according to any one of claims 1-11, wherein, in the outlet surface (330), a cross section of at least one nozzle tube outlet (52), or each nozzle tube outlet (52) of the plurality of nozzle tube outlets (52), is delimited by a perimeter line (77) comprising at least a curved line segment (78) and a straight line segment (79).

13. Nozzle assembly (20) according to any one of claims 1-12, further comprises an atomizer base (22) comprising:a) a plurality of atomizing gas channels (23) for conducting pressurized atomizing gas (110) to the atomizing gas outlet (54), andb) a liquid aperture (92) for conducting the liquid into the nozzle body (1, 2, 3, 4, 5, 6), wherein the atomizer base (22) is secured to the nozzle body (1, 2, 3, 4, 5, 6), such that the liquid (9) can flow through the liquid aperture (92) into the nozzle tube inlet (57), and wherein, optionally, the atomizer base (22) and the nozzle body (1, 2, 3, 4, 5, 6) are formed as separate components.

14. Nozzle assembly (20) according to any one of claims 1-13, wherein a spray axis (200) is defined as an axial direction through a centroid (310) of the plurality of nozzle tube outlets (52), and wherein the atomizing gas outlet (54) has an annular shape, centered about the spray axis (200), and arranged such as to encircle the plurality of nozzle tube outlets (52).

15. A liquid spray gun (10) for spraying a liquid (9), the liquid spray gun (10) comprising the nozzle assembly (20) according to any one of claims 1-14.

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