NOZZLE BODY FOR A LIQUID SPRAY GUN

Abstract

 Nozzle body (1) for a liquid spray gun comprising a tubular nozzle tube (66), comprising
a) a nozzle tube passage (58), extending between a nozzle tube inlet and a nozzle tube outlet (52), through which the liquid exits the nozzle tube passage (58), and
b) a nozzle tube wall (71) having a radially outer surface (75).
The outer surface (75) of the nozzle tube wall (71) is operable to form, in conjunction with a surface of an air cap, an atomizing gas outlet arranged circumferentially around the nozzle tube outlet (52), such that the pressurized atomizing gas (110) exits into outside air (93) through the atomizing gas outlet and atomizes the liquid.
The outer surface (75) of the nozzle tube wall (71) is oriented or shaped to direct at least a portion of the pressurized atomizing gas (110) exiting the atomizing gas outlet angularly away from the spray axis (200).

Description

[0001] This disclosure relates to liquid spray guns in which a liquid to be sprayed is atomized by a pressurized gas. It relates more specifically to nozzle bodies for use in such spray guns, to nozzle assemblies comprising such nozzle bodies, and to machine-readable media having data stored thereon which represent models of such nozzle bodies or nozzle assemblies.

[0002] 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.

[0003] 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 challenge with using lower gas pressures is that the amount of energy available to both draw-out and atomize the liquid paint is reduced. This situation can negatively impact the application speed and 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 and in the liquid paint being more difficult to atomize. A stronger flow of atomizing gas can provide for a finer atomization that generates a finer paint spray. However, increasing the pressure of the atomizing gas increases the volume of undesirable high-frequency noises, generally results in lower transfer efficiency, increases consumption of pressurized atomizing gas, and results in higher operating costs.

[0004] The U.S. patent application published as US 2020/0030831 A1 attempts to address these issues and suggests a spray gun with fluid tip comprising an air cap and a paint nozzle, wherein the air cap comprises an inner surface and the paint nozzle comprises an outer surface, the inner and outer surfaces defining sides of an air channel and being defined by contours, each contour terminating to form an air channel outlet for discharging an air jet proximal a paint nozzle outlet of the paint nozzle. The contours are configured to provide a velocity profile across the air channel outlet of an air flow through the air channel in which velocities of air radially closer to the paint nozzle outlet are substantially higher than velocities radially further from the paint nozzle outlet.

[0005] In order to save energy and paint during spray paint applications, new spray gun designs are needed which can efficiently utilize the 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.

[0006] In an attempt to address these needs the present disclosure provides a nozzle body for a liquid spray gun for spraying a liquid, the nozzle body comprising a tubular nozzle tube, comprising

a) an elongated nozzle tube passage, extending lengthwise between a nozzle tube inlet through which, in use, liquid enters the nozzle tube, and a nozzle tube outlet, through which, in use, the liquid exits the nozzle tube passage into outside air in a spray direction, wherein the length direction of the nozzle tube passage defines axial directions and radial directions orthogonal to the axial directions,

b) a nozzle tube wall having a radially outer surface and an opposed radially inner surface delimiting the nozzle tube passage and being, in use, in contact with the liquid,

wherein the spray direction through a centroid of the cross section of the nozzle tube outlet defines a spray axis, wherein the nozzle tube outlet is arranged around, and comprises, the spray axis, wherein the outer surface of the nozzle tube wall is operable to form, in conjunction with a surface of an air cap, when the air cap is connected directly or indirectly with the nozzle body, an atomizing gas outlet arranged circumferentially around the nozzle tube outlet, such that the pressurized atomizing gas exits into outside air through the atomizing gas outlet and atomizes the liquid after the liquid has exited the nozzle tube outlet, characterized in that the outer surface of the nozzle tube wall is oriented or shaped to direct at least a portion of the pressurized atomizing gas exiting the atomizing gas outlet angularly away from the spray axis.

[0007] In a nozzle body according to the present disclosure the outer surface directs atomizing gas emanating from the annular atomizing gas outlet angularly away from the spray axis. Within this angularly-outward directed flow of atomizing gas the pressure at the nozzle tube outlet is lower than it is in traditional geometries in which 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 passage and increases the liquid (e.g. paint) flow rate, although the consumption of pressurized gas is unchanged with respect to the traditional nozzle bodies. To obtain a liquid flow rate similar to those obtained with traditional nozzle bodies, the pressure and/or volume of the pressurized atomizing gas can be reduced in spray guns featuring a nozzle body according to the present disclosure. This may result in energy and cost savings. A lower pressure of the atomizing gas may also result in less generation of high-frequency noise or in lower volume of high-frequency noise during spraying operations, which reduces occupational noise exposure and associated health risks for human operators.

[0008] For clarity it is noted that in certain prior art spray guns and with certain prior art nozzle bodies the trajectory of atomizing air is sometimes also directed angularly away from the spray axis after the atomizing air, initially directed towards the spray axis, has crossed the spray axis. In those prior art devices, however, the atomizing air is not directed away from the spray axis at the very time of the atomizing air exiting the atomizing air outlet, and it is not directed away from the spray axis in the immediate vicinity of the atomizing air outlet. Different from such traditional spray guns and traditional nozzle bodies, in spray guns and with nozzle bodies according to the present disclosure the atomizing gas is directed away from the spray axis at the moment of exiting the atomizing gas outlet, and the atomizing gas is directed away from the spray axis in the immediate vicinity of the atomizing gas outlet.

[0009] Nozzle bodies are generally known from traditional liquid paint spray guns. A nozzle body generally comprises a nozzle 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 A1 or WO 2013/016474 A1, for example.

[0010] Like in traditional nozzle bodies, when in use, a nozzle body according to the disclosure is generally connected to a barrel (such as to a barrel holding a paint cup) or the body of a spray gun. Liquid is supplied into the nozzle body 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 body, so 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 body and - within the nozzle body - to the nozzle tube outlet where it exits the nozzle body and the spray gun.

[0011] A nozzle body according to the present disclosure comprises a nozzle tube having a wall, an inlet, an outlet, and a passage through which the liquid flows from the inlet to the outlet. At the nozzle tube outlet the liquid exits the nozzle body in a spray direction and is atomized close to the nozzle tube outlet by a flow of pressurized gas ("atomizing gas") to form a spray of minute liquid droplets which propagates through surrounding air to eventually hit a surface that is to be coated with the liquid.

[0012] The nozzle bodies according to the present disclosure are for use in spray guns which spray a liquid and atomize the liquid using pressurized gas. Nozzle bodies and nozzle body assemblies for other types of spraying devices, such as electrostatic spray guns or spray guns for spraying solids are outside the scope of this disclosure.

[0013] 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, "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.

[0014] As used herein, a substance is considered liquid if its viscosity at 20 °C is lower than about 20000 mPa.s, particularly if its viscosity at 20 °C is lower than about 2000 mPa.s.

[0015] Most traditional spray guns use pressurized air for atomization of the liquid and shaping of the 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.

[0016] Nozzle bodies according to the present disclosure comprise an elongated nozzle tube having a wall ("nozzle tube wall"), an inlet ("nozzle tube inlet"), an outlet ("nozzle tube outlet") and a passage ("nozzle tube passage"). A nozzle tube may be a tubular element of any length. It may be, for example, a tubular element of a length of 2 millimeters (mm) or 5 mm or 10 mm.

[0017] The nozzle tube is elongated and thereby extends in a length direction. The length direction of the nozzle tube defines axial directions of the nozzle tube and of the nozzle body. Radial directions are directions orthogonal to the axial directions.

[0018] The nozzle tube may have a cross section. 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.

[0019] 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 nozzle tube outlet.

[0020] The nozzle tube is tubular. "Tubular" refers to the 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.

[0021] 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.

[0022] The nozzle tube comprises a nozzle tube passage which extends between the nozzle tube inlet and the nozzle tube outlet for conducting the liquid from the nozzle tub inlet to the nozzle tube outlet. The nozzle tube inlet is a first end of the nozzle tube passage. The nozzle tube outlet is a second end of the nozzle tube passage, opposite to the first end.

[0023] The nozzle tube passage may have a cross section. 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.

[0024] In certain embodiments the nozzle tube passage is straight between nozzle tube inlet and nozzle tube outlet. 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 nozzle tube outlet.

[0025] 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 nozzle tube outlet.

[0026] The nozzle tube has a nozzle tube wall. The wall may extend generally lengthwise in axial directions. It may extend to the nozzle tube outlet. The nozzle tube wall may separate the nozzle tube passage from a space outside the nozzle tube, such as from an atomizing gas passage.

[0027] The nozzle tube wall may have a thickness. The thickness may be defined by the extension of the nozzle tube wall in radial directions. 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.

[0028] The nozzle tube wall may have 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.

[0029] 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 of the nozzle body according to the present disclosure 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 suitably for directing pressurized atomizing gas angularly away from the spray axis. 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 suitably for directing pressurized atomizing gas angularly away from the spray axis. 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.

[0030] 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.

[0031] 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.

[0032] 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 atomizing gas conducted through the atomizing gas passage towards an atomizing gas outlet, arranged circumferentially around the nozzle tube wall at the nozzle tube outlet.

[0033] 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.

[0034] The frontmost axial portion of the outer surface of the nozzle tube wall is a portion which generally has a strong impact on the direction of the pressurized atomizing gas as it exits the atomizing gas outlet. It may thus be advantageous for this frontmost portion to be oriented or shaped to direct at least a portion of the pressurized atomizing gas exiting the atomizing gas outlet angularly away from the spray axis. This frontmost portion of the outer surface of the nozzle tube wall is the portion at the nozzle tube outlet. Therefore, in certain embodiments, the outer surface of the nozzle tube wall at the nozzle tube outlet is oriented or shaped to direct at least a portion of the pressurized atomizing gas exiting the atomizing gas outlet angularly away from the spray axis.

[0035] In the context of these geometric considerations, it is noted that the forward end of the outer surface of the nozzle tube wall may not be a perfect edge. On a small scale, this forward end may have an inconsistent shape, recesses, protrusions, or a chamfers, such as may be required for a reliable manufacturing process of the nozzle tube or unavoidable in industrial production processes. Such imperfections or chamfers of axial extensions of 0.4 mm or less, whatever their orientation or shape, are not considered suitable to considerably affect the flow of atomizing gas in the desired way. Such unavoidable inconsistencies or indispensable chamfers at the forward end of the outer surface of the nozzle tube wall are thus not considered portions of the outer surface of the nozzle tube wall at the nozzle tube outlet herein.

[0036] 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 a liquid nozzle port on a 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 nozzle tube outlet where it exits the nozzle body into outside air and is atomized by atomizing gas.

[0037] The nozzle tube outlet is an aperture in the nozzle tube through which the liquid exits the nozzle tube (and the nozzle body) and enters the surrounding air. The nozzle tube outlet is one end of the nozzle tube passage and is delimited, in radial directions, by the nozzle tube wall which extends up to the nozzle tube outlet.

[0038] The nozzle tube outlet may have a cross section. The cross section of the nozzle tube outlet determines the cross section of the flow of liquid as it exits the nozzle tube and enters surrounding air, before the liquid is atomized to form minute droplets. Although in most embodiments the cross section of the nozzle tube outlet has a circular shape, it may have, in other embodiments, have other shapes like, for example, an elliptic shape, a square shape, a rectangular shape, a polygonal shape, or a star shape.

[0039] The nozzle tube outlet may be an orifice in the nozzle body circumferentially delimited by a forwardmost (in the spray direction) terminal edge of the inner surface of the nozzle tube wall.

[0040] A cross section of the nozzle tube outlet may be symmetric about a center point or a center of the nozzle tube outlet. The cross section of the nozzle tube outlet may be rotationally symmetric or axially symmetric about a center point or a center of the nozzle tube outlet. The cross section of the nozzle tube outlet may be of an irregular shape, e.g. a shape exhibiting no symmetry.

[0041] In order to define a center point or a center of the nozzle tube outlet in a most general manner, the commonly known notion of a "centroid" is applied. A centroid of a plane figure, such as of the cross section of the nozzle tube outlet perpendicular to the spray direction, is commonly known to be the arithmetic mean position of all the points in the surface of the figure. In geometry, one often assumes uniform mass density, in which case the center of mass of the plane figure coincides with the centroid. Informally, the centroid can be understood as the point at which a cutout of the shape of the plane figure (with uniformly distributed mass) would be perfectly balanced on the tip of a pin.

[0042] The liquid exits the nozzle tube at the nozzle tube outlet into outside air in a spray direction. The spray direction is thus the flight direction of the liquid flow at the very position where the liquid exits the nozzle tube passage. This position is a position at the nozzle tube outlet, i.e. in the most forward portion of the nozzle tube wall in the vicinity of the nozzle tube outlet. Depending on the circumstances, further downstream the liquid flow may not have a well-defined flight direction any more. The definition of the "spray direction" herein is therefore based on the direction of the liquid flow at the very position where the liquid exits the nozzle tube passage.

[0043] The spray direction is generally determined by the orientation of a terminal portion of the nozzle tube passage, i.e. the portion closest to the nozzle tube outlet. The spray direction through the centroid of the cross section of nozzle tube outlet defines a spray axis. The spray axis thus always passes through the centroid. In most embodiments the spray axis is an axial direction. Axial directions are 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 nozzle tube outlet.

[0044] The nozzle tube outlet is arranged around, and comprises, the spray axis. In preferred embodiments the nozzle tube outlet has a circular cross section, i.e. a cross section of a circular disc, centered around the spray axis. As opposed to nozzle tube outlets having an annular cross section, the nozzle tube outlet of a nozzle body according to the present disclosure comprises the spray axis. In such nozzle tube outlets liquid exits the nozzle tube passage through the nozzle tube outlet at the position of the spray axis. This geometry may help in obtaining a jet of liquid that has a smaller diameter and can thereby provide a more consistent spray pattern. Also, the resulting jet of liquid has a smaller external surface than, for example, a jet forming a hollow cylindrical curtain. A smaller external surface reduces evaporation of the liquid.

[0045] A short distance downstream from where the liquid exits the nozzle tube passage through the nozzle tube outlet, the jet of liquid is atomized by a flow of atomizing gas. Different from the geometry of atomizing gas flows in traditional nozzle bodies, the nozzle bodies according to this disclosure direct at least a portion of the atomizing gas angularly away from the spray axis. This "divergent" atomizing gas may not impinge directly on the jet of liquid emanating from the nozzle tube outlet. Instead, the divergent atomizing gas creates a larger volume of reduced pressure, located immediately in front of, i.e. downstream from, the nozzle tube outlet. In certain configurations I 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.

[0046] 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 A1, 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. 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. Certain air caps are provided with air horns having shaping air apertures to direct so-called shaping gas from opposite directions towards a jet of atomized liquid in order to shape the spray jet into a desired pattern. An air cap and a nozzle body may be integrated to form an integrated air cap/nozzle body, as in the European patent EP 2736651 B1, for example.

[0047] When an 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 nozzle tube outlet. The atomizing gas outlet may be formed between a surface of the air cap and the outer surface of the nozzle tube wall at the nozzle tube outlet, i.e. the outer surface of a terminal end of the nozzle tube.

[0048] A circumferential arrangement of the atomizing gas outlet around the nozzle tube outlet is not limited to a circular circumferential arrangement, but includes, for example, elliptic circumferential arrangements, square or rectangular or other polygonal circumferential arrangements, star-shaped 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.

[0049] 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 nozzle tube outlet. This helps ensure proper atomization of the liquid.

[0050] The width of the atomizing gas outlet is not particularly limited. Width is the extension of the atomizing gas outlet in radial directions in the plane of the nozzle tube outlet. In certain configurations, the width is the radial distance in the plane of the nozzle tube outlet from the outer surface of the nozzle body to the nozzle aperture edge. The atomizing gas outlet may have a width of between 0.01 millimetre (mm) and 5.00 mm, for example. Preferably, the atomizing gas outlet has a width of between 0.1 millimetre (mm) and 1.00 mm. 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 gas and the liquid to be atomized. In contrast, a narrower atomizing gas outlet lets less gas pass through but it may flow at a higher velocity and thereby increase the shear stress between the 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.

[0051] The atomizing gas outlet may be circumferentially arranged around the nozzle tube outlet at a certain radial distance from the nozzle tube outlet. This radial distance may be the thickness of the nozzle tube wall at the terminal end of the nozzle tube, i.e. at the nozzle tube outlet. The radial distance, at the nozzle tube outlet, between the nozzle tube outlet and the atomizing gas outlet may be between 0.01 mm and 5 mm, preferably it is between 0.1 mm and 1 mm. Since the gas exit velocity is often highest at the atomizing gas outlet and decays moving downstream, there can be benefits to placing the nozzle tube outlet as close as practically possible to the gas outlet. One way to do so is by minimizing the radial distance between the nozzle tube outlet and atomizing gas outlet. Generally, a greater radial distance results in less efficient extraction and atomization of the liquid. Conversely, a smaller radial distance may cause the nozzle tube wall to be quite thin at the nozzle tube outlet, introducing the risk of inconsistencies and damage.

[0052] The nozzle tube outlet may be arranged in a geometrical plane, such as a plane orthogonal to the spray axis or orthogonal to the axial directions. The atomizing gas outlet may be arranged in the same geometric plane as nozzle tube outlet, or it may be recessed or protruding from the plane of the nozzle tube outlet by up to 5 mm.

[0053] The outer surface of the nozzle tube wall is also operable to form, in conjunction with a surface of an air cap when the air cap is connected directly or indirectly with the nozzle body, an atomizing gas passage for conducting a pressurized atomizing gas toward the atomizing gas outlet. The pressurized atomizing gas can thus exit the atomizing gas passage into outside air at the atomizing gas outlet and can atomize the liquid after the liquid has exited the nozzle tube outlet.

[0054] 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 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.

[0055] A suitable air cap may be connected with the nozzle body according to the present disclosure directly or indirectly. 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.

[0056] A nozzle body as described herein, in conjunction with an air cap, can form a nozzle assembly. In a 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 an 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.

[0057] In certain of these nozzle assemblies the nozzle assembly comprises a nozzle body as described herein and an 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 a nozzle aperture edge, and wherein 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.

[0058] 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.

[0059] 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.

[0060] The front wall may form a nozzle aperture in which the forward end of the nozzle tube may be arranged or through which the forward end of the nozzle tube protrudes outwardly. The edge delimiting the nozzle aperture in the front wall is referred to as nozzle aperture edge herein. When 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 nozzle tube outlet. In the plane of the nozzle tube outlet, 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 radial direction. The gap may form the atomizing gas outlet described herein. The atomizing gas outlet is arranged circumferentially around the nozzle tube outlet, such that the pressurized atomizing gas exits into outside air through the atomizing gas outlet and atomizes the liquid after the liquid has exited the nozzle tube outlet.

[0061] In nozzle bodies and nozzle assemblies described herein a first portion of the atomizing gas, when exiting the atomizing gas outlet, is directed angularly away from the spray axis by the orientation or shape of the outer surface of the nozzle tube wall. In nozzle assemblies as described in the preceding paragraphs, the air cap can help, via a suitably shaped or suitably oriented nozzle aperture edge, to direct a further, second portion of the atomizing gas angularly away from the spray axis. This may enhance the liquid extraction and liquid atomization provided by the direction of the first portion of atomizing gas away from the spray axis even further. The improved atomization may alternatively allow to reduce the atomizing gas pressure which can help reduce the generation of high-frequency noise to which human operators are exposed.

[0062] Hence in certain embodiments of the nozzle assemblies described above the nozzle aperture edge is oriented or shaped to direct at least a portion of the pressurized atomizing gas exiting the atomizing gas outlet angularly away from the spray axis. The nozzle aperture edge may, for example, be inclined radially outwardly with respect to the spray axis, such as to form a diverging conical surface. In other words, the nozzle aperture edge may have a larger diameter (or enclose a larger area) at a downstream axial position than it does at an axial position further upstream. The outward inclination draws a portion of the atomizing gas away from the spray axis via aerodynamic effects, for example.

[0063] 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 bodies 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.

[0064] In order to get closer to a symmetric jet of liquid, in certain embodiments of the nozzle assemblies described herein the nozzle tube outlet, the nozzle tube wall, the nozzle aperture edge, and the atomizing gas outlet are each of rotationally symmetric shape and arranged concentrically with respect to the spray axis.

[0065] 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. After a spraying operation only the barrel and the nozzle body need to be cleaned from 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 an air cap and a nozzle body. A further function of a barrel is to conduct pressurized 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. A barrel may comprise separate ducts for atomizing gas and shaping gas. In some embodiments, the barrel and the nozzle body are integrally formed as a single component.

[0066] Nozzle assemblies comprising an air cap and a nozzle body according to the present disclosure have been described above. Nozzle bodies according to the present disclosure 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 a 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 the shape and orientation of the atomizing gas outlet constant, which is formed between a portion of the air cap (e.g. its nozzle aperture edge) and a portion of the nozzle body (its 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.

[0067] Therefore, in certain embodiments of the nozzle assemblies described herein the nozzle assembly further comprises a barrel having a liquid port connector for directly or indirectly connecting a liquid reservoir to the barrel, wherein the air cap is connected with the barrel, and the nozzle body is connected with the barrel, such that the air cap is connected with the nozzle body in a fixed spatial relation.

[0068] An atomizing gas outlet may be formed by a portion of the nozzle tube and a portion of an air cap. Specifically, the outer surface of the nozzle tube wall, at the nozzle tube outlet or at an axial position further upstream, is operable to form, in conjunction with a surface of an air cap when the air cap is connected directly or indirectly with the nozzle body, an atomizing gas passage and an atomizing gas outlet, at which the atomizing gas exits the atomizing gas passage into outside air and atomizes liquid after the liquid has exited the nozzle tube outlet.

[0069] Where an atomizing gas outlet is formed by the outer surface of the nozzle tube wall and a surface of an air cap, pressurized atomizing gas can exit an atomizing gas passage into outside air at the atomizing gas outlet. This atomizing gas atomizes the liquid shortly after the liquid exits the nozzle tube outlet. The atomizing gas outlet is arranged circumferentially around the nozzle tube outlet.

[0070] The atomizing gas outlet can be formed by cooperation between the nozzle body according to the present disclosure and an air cap once the air cap is connected with the nozzle body. The air cap may comprise an aperture (preferably in its front wall) in which the nozzle tube outlet is arranged or from which the nozzle tube protrudes forward in the spray direction. The aperture in the air cap is preferably centered about the spray axis and is radially-outwardly delimited by an aperture-delimiting surface, and the atomizing gas outlet is formed by the nozzle tube wall of the nozzle body and the aperture-delimiting surface of the air cap. More precisely, the atomizing gas outlet is formed by the outer surface of the nozzle tube wall at the nozzle tube outlet (i.e. the forwardmost portion of the outer surface of the nozzle tube wall) and the aperture-delimiting surface of the air cap. In such embodiments the atomizing gas outlet is an annular aperture between the nozzle tube wall and the aperture-delimiting surface of the air cap.

[0071] Alternatively, the atomizing gas outlet may be formed by the nozzle body alone. In such embodiments the atomizing gas outlet is formed without requiring an air cap or another element to form the atomizing gas outlet.

[0072] The atomizing gas outlet may be a ring-shaped, i.e. annular, atomizing gas outlet. It may be arranged concentric with the nozzle tube outlet. It may be arranged centered about the spray axis. The nozzle tube outlet and the atomizing gas outlet may be arranged concentrically with each other and centered about the spray axis. The atomizing gas outlet may be arranged concentrically around the nozzle tube outlet, wherein the atomizing gas outlet and the atomizing gas outlet are arranged centered about the spray axis.

[0073] The atomizing gas outlet may have an annular shape, such as an annular shape centered about the spray axis. It may be radially-inwardly delimited by a surface of the nozzle body (e.g. by the outer surface of the nozzle tube wall at the nozzle tube outlet). It may be radially-outwardly delimited by a surface of the air cap (e.g. by an aperture-delimiting surface delimiting an aperture in a front wall of the air cap). The annular shape may be formed for a full 360° angle around the spray axis or alternatively for one or more segments of fractions of a 360° angle around the spray axis.

[0074] In nozzle bodies according to the present disclosure the outer surface of the nozzle tube wall is oriented or shaped to direct at least a portion of the atomizing gas exiting the atomizing gas outlet angularly away from the spray axis. A direction away from the spray axis is also referred to as a "divergent" direction herein, and the property of being directed away from the spray axis as "diverging" or "divergent".

[0075] 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, and a diverging portion in the vicinity of the nozzle tube outlet (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 to the nozzle tube outlet. 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 straight line ascending with decreasing axial distance to the nozzle tube outlet. 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 nozzle tube outlet.

[0076] 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.

[0077] In certain embodiments the outer surface of the nozzle tube wall comprises a ramped axial section, such as a ramped axial section at the nozzle tube outlet, for directing at least a portion of the pressurized atomizing gas exiting the atomizing gas outlet angularly away from the spray axis. The term "ramped" refers herein to the representation of the outer surface in a longitudinal section of the nozzle body through the spray axis, where a line representing the "ramped" axial section of the outer surface is inclined with respect to the spray axis. Through the inclined orientation, the outer surface can direct at least a portion of the pressurized atomizing gas exiting the atomizing gas outlet angularly away from the spray axis.

[0078] The ramped axial section may be located at the nozzle tube outlet or upstream from the nozzle tube outlet. If located upstream from the nozzle tube outlet, it must be close enough to the nozzle tube outlet to still direct at least a portion of the pressurized atomizing gas exiting the atomizing gas outlet angularly away from the spray axis.

[0079] A ramped axial section may have an axial extension of 0.5 millimetres or more, or of 1.0 mm or more. Ramped axial sections of this length are considered suitable to affect the flow of atomizing gas in the desired way.

[0080] A ramped axial section can be easy to manufacture and directs the compressed atomizing gas over an extended axial distance, namely along the length of the ramped section, into a direction that is oriented angularly away from the spray axis. This in turn may help generate a consistent volume of lower pressure in front of the nozzle tube outlet, resulting in increase of the liquid (e.g. paint) flow rate and/or reduced consumption of pressurized atomizing gas and/or reduction of high-frequency noise.

[0081] In certain embodiments of the nozzle body according to the present disclosure the ramped axial section forms a ramp angle (α) with the spray axis, wherein the ramp angle (α) is between 0.5° and 45°. The ramp angle α of the outer surface of the nozzle tube wall determines to a large degree the angle between the velocity of portions of the atomizing gas exiting the atomizing gas outlet and the spray axis. Where the atomizing gas exits the atomizing gas outlet at an angle smaller than 0.5° with respect to the spray axis, the liquid flow rate is not significantly larger than whee traditional nozzle bodies are used. Where the atomizing gas exits the atomizing gas outlet at an angle greater than 45° with respect to the spray axis, the volume of reduced pressure in front of the nozzle tube outlet is deemed spread out too far to have a significant desirable effect on liquid flow rate, consumption of atomizing gas and noise.

[0082] A ramp angle is a simple means to control the direction of the atomizing gas velocity vector at the nozzle tube outlet. A positive ramp angle α will impart a radial component to the velocity vector, making the velocity vector point angularly away from the spray axis. A ramp angle of between 0.5° and 45° brings about movement of the atomizing gas at a corresponding angle relative to the spray axis. This range of angles of movement of the atomizing gas is considered suitable in many scenarios to bring about the benefit in terms of reduced compressed gas consumption, higher liquid flow rate, and/or reduced hissing noise described above.

[0083] Circumferential positions are considered positions on a closed path extending, e.g. in a plane orthogonal to the spray axis, a full 360° angle around the spray axis and at some (varying or fixed) distance of the spray axis. Where the closed path is a circle, circumferential positions are positions on that circle. Relative to a reference radius, a circumferential position may be a position at a certain angle.

[0084] In most scenarios it is typically desired to obtain a homogenous atomization. Therefore, in many embodiments the ramp angle mentioned above, at a certain axial position, is equal at all circumferential positions of the outer surface of the nozzle tube wall. In certain embodiments, however, the ramp angle at a first circumferential position of the outer surface of the nozzle tube wall is different from the ramp angle at a second circumferential position of the outer surface of the nozzle tube wall.

[0085] At one axial position, different ramp angles of the nozzle tube wall in different circumferential positions will result in pressurized atomizing gas being directed away from the spray axis at different angles. This may be beneficial in scenarios in which it is desired to impart certain geometric properties to the jet of atomized liquid or to cause inhomogeneous atomization.

[0086] In certain embodiments, and independent from any specific contour in a longitudinal sectional view, the outer surface of the nozzle tube wall in the diverging portion may be rotationally symmetric about the spray axis. In certain embodiments, and independent from any specific contour in a longitudinal sectional view, the outer surface of the nozzle tube wall at the nozzle tube outlet is rotationally symmetric about the spray axis.

[0087] In certain embodiments the outer surface of the nozzle tube wall comprises a gas-directing portion for directing at least a portion of the pressurized atomizing gas exiting the atomizing gas outlet angularly away from the spray axis, and wherein the gas-directing portion has the shape of the radially-outer surface of a truncated cone. A truncated cone is also referred to as "frustum" in mathematics. A truncated cone defines a symmetry axis. Radial directions of the truncated cone are directions orthogonal to the symmetry axis. The axial end portion of the truncated cone shape having a larger radial extension may be located downstream, in the spray direction, from the axial end portion of the truncated cone shape having a smaller radial extension.

[0088] The shape of a truncated cone can be simple and cost-effective to manufacture at a high surface quality on a turning lathe or in molding. A high surface quality implies a smooth surface which helps obtain a consistent flow of atomizing gas. Through its shape the cone shaped gas-directing portion of the nozzle tube wall imparts a consistent velocity component, directed angularly away from the spray axis, to pressurized atomizing gas flowing along the outer surface of the nozzle tube wall and its gas-directing portion.

[0089] The axial position at which the liquid exits the nozzle tube passage into outside air is the axial position "at the nozzle tube outlet", as used herein. As the nozzle tube wall delimits the nozzle tube passage which ends at the nozzle tube outlet, this axial position is the axial position at which the nozzle tube wall (and the nozzle tube) ends. In other words, the nozzle tube wall extends axially up to the nozzle tube outlet. Also the outer surface of the nozzle tube wall ends at the nozzle tube outlet.

[0090] In a cross section taken in a plane orthogonal to the spray axis at that axial position, i.e. at the nozzle tube outlet, the outer surface of the nozzle tube wall may be circular in cross section. It may alternatively be of a different cross section.

[0091] A circular cross section of the outer surface of the nozzle tube wall 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 atomizing gas and in consequence a more even and more effective atomization of the liquid a short distance downstream from the nozzle tube outlet. This can be advantageous and desirable in certain scenarios. The circular cross section may be interrupted by minor structural elements that may, for example, help maintain a fixed spatial relation and an even distance between the outer surface of the nozzle tube wall and an air cap that forms, in conjunction with the nozzle tube wall, the atomizing gas outlet.

[0092] Where the outer surface of the nozzle tube wall at the nozzle tube outlet is circular in cross section taken in a plane orthogonal to the spray axis, the outer surface at the nozzle tube outlet may extend circumferentially for a full 360° angle. A full 360° angle is deemed to relate to an uninterrupted circular shape. An uninterrupted circular shape of the outer surface of the nozzle tube wall at the nozzle tube outlet (i.e. at the end of the nozzle tube wall) is particularly cost-effective to manufacture at a high precision of symmetry (roundness), e.g. on a turning lathe. The uninterrupted 360° circular symmetry may help provide a circular symmetric jet of atomizing gas and consequently a more even and more effective atomization of the liquid a short distance downstream from the nozzle tube outlet. This can be advantageous and desirable in certain scenarios.

[0093] In other embodiments, however, the outer surface may not be rotationally symmetric. In certain of these embodiments, in a first angular location measured around the spray axis, the outer surface of the nozzle tube wall may direct atomizing gas angularly away from the spray axis at a first angle. In a second angular location measured around the spray axis, the outer surface of the nozzle tube wall may direct atomizing gas angularly away from the spray axis at a second, larger angle. The second angular location may be spaced from the first angular location by an angle of 90°, 60° or 45°, for example.

[0094] In a third angular location measured around the spray axis, the outer surface of the nozzle tube wall may direct atomizing gas angularly away from the spray axis at the first angle. The third angular location may be spaced from the first angular location by an angle of 180°, 120°, or 90°, for example.

[0095] As the atomizing gas - or at least a portion of it - exits the atomizing gas outlet, it is directed angularly away from the spray axis by the suitably shaped or oriented outer surface of the nozzle tube wall. The angle at which the atomizing gas is directed away from the spray axis (also referred to as "divergence angle" herein) may be the same angle in all angular positions around the spray axis. In such a scenario the atomizing gas may form a diverging conical shape (interrupted or not when going around the spray axis in circumferential directions).

[0096] To obtain good spray results the diverging conical shape may be adapted in response to, for example, a desired paint flow rate, a desired spray jet geometry, to the viscosity or temperature or solid content of the liquid to be sprayed, to ambient air temperature, or to other parameters. To obtain a desired second divergence angle, a first nozzle body providing a first divergence angle to the atomizing gas may be replaced by a second nozzle body providing a second divergence angle to the atomizing gas.

[0097] In certain embodiments the divergence angle varies with angular positions around the spray axis. To illustrate this, in a scenario where the spray axis is oriented horizontally, the divergence angle may be larger in a vertically upward angular position around the horizontal spray axis ("12 o'clock angular position") and smaller in a vertically downward angular position around the horizontal spray axis ("6 o'clock angular position").

[0098] Nozzle bodies according to the present disclosure are operable to form a portion of an atomizing gas passage. Nozzle bodies according to the present disclosure are operable to form a portion of an atomizing gas outlet which is arranged circumferentially around the nozzle tube outlet. Where the atomizing gas outlet has an annular shape the atomizing gas emanating from the atomizing gas outlet may form a divergent gas curtain. Where the atomizing gas outlet has an annular shape and is centered about the spray axis, the atomizing gas emanating from the atomizing gas outlet may form a divergent gas curtain centered about the spray axis. Where the atomizing gas exits the atomizing gas outlet, the divergent gas curtain may extend for a full 360° circle around the spray axis, forming a divergent continuous gas curtain. Alternatively, the divergent gas curtain may extend for one or more respective angular sections of a full 360° circle around the spray axis, such as two angular sections of a 90° angle each.

[0099] In certain embodiments the outer surface of the nozzle tube wall is oriented or shaped to direct at least a portion of the pressurized atomizing gas exiting the atomizing gas outlet angularly away from the spray axis at an angle of between 0.5° and 45°. As stated above, where the atomizing gas exits the atomizing gas outlet at an angle smaller than 0.5° with respect to the spray axis, liquid flow rate is not significantly larger than where traditional nozzle bodies are used. Where the atomizing gas exits the atomizing gas outlet at an angle greater than 45° with respect to the spray axis, the volume of reduced pressure in front of the nozzle tube outlet is deemed spread out too far to have a significant desirable effect on liquid flow rate, consumption of atomizing gas and noise. In certain of these embodiments the outer surface of the nozzle tube wall is oriented or shaped to direct at least a portion of the pressurized atomizing gas exiting the atomizing gas outlet angularly away from the spray axis at an angle of between 5° and 15°. The desired effects of higher liquid flow rate and/or reduced consumption of pressurized atomizing air and/or less high-frequency noise are more prominent in the angular range of 5° to 15°.

[0100] The nozzle bodies according to the present disclosure can be connected to a spray gun platform, directly or via their connection to a barrel connected to the spray gun platform, to form a liquid spray gun which directs at least a portion of the pressurized atomizing gas exiting the atomizing gas outlet angularly away from the spray axis. This angular direction away from the spray axis more effectively utilizes the motive force of compressed atomizing gas to both draw-out and atomize the liquid using lower gas pressures. Alternatively, the effect can be used to consume less of the pressurized atomizing gas but still maintain a comparable liquid flow rate achieved by traditional (non-angled) geometries.

[0101] The present disclosure therefore also provides a liquid spray gun for spraying a liquid, comprising a nozzle body as described herein, or a nozzle assembly as described herein.

[0102] Nozzle bodies 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. Digital data describing the nozzle body may be stored on a machine-readable medium and may be sent to the 3D printer by digital processors such that the 3D printer "prints" the nozzle body.

[0103] The present disclosure thus also provides a non-transitory machine-readable medium having data stored thereon representing a three-dimensional model of a nozzle body as described herein or of a nozzle assembly as described herein, the data being formatted to be accessed by one or more digital processors interfacing with a 3D printer, wherein the one or more digital processor(s) is/are operable to cause the 3D printer to manufacture the nozzle body or the nozzle assembly, respectively.

[0104] The invention will now be described in more detail with reference to the following Figures exemplifying particular embodiments of the invention:

Fig. 1

Exploded perspective view of a spray gun comprising a first nozzle body according to the present disclosure;

Fig. 2

Perspective view of the first nozzle body, attached to a barrel;

Fig. 3

Perspective view of a spray head assembly comprising the first nozzle body and the barrel of Figure 2;

Fig. 4

Longitudinal sectional view of the spray head assembly of Figure 3;

Fig. 5

Longitudinal sectional view of a forward portion of the first nozzle body of Figures 1-4;

Fig. 6

Longitudinal sectional view of respective forward portions of the first nozzle body and of the air cap of the spray head assembly of Figures 3 and 4;

Fig. 7

Longitudinal sectional view of respective forward portions of the first nozzle body and of an alternative air cap of a spray head assembly;

Fig. 8A

Atomizing gas pressure diagram of a traditional nozzle body;

Fig. 8B

Atomizing gas pressure diagram of a nozzle body according to the present disclosure, and

Fig. 9

Diagram illustrating liquid flow rates for traditional nozzle bodies versus liquid flow rates for nozzle bodies according to the present disclosure.

[0105] Figure 1 is an exploded perspective view of one illustrative embodiment of a liquid spray gun comprising a nozzle body as described herein. The liquid spray gun has a variety of components including a liquid spray gun platform 10 and a spray head assembly 20 that is - preferably releasably - attached to the liquid spray gun platform 10 at a barrel interface 11. The spray head assembly 20 provides features that control movement of both the liquid to be sprayed (a liquid paint, for example) and the atomizing gas (air, for example) used to atomize the liquid as described herein. In some embodiments, the spray head 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 spray head assembly 20 in some embodiments can be avoided and the spray gun can be conveniently changed over by, e.g., attaching a different spray head assembly 20 connected to the same or a different liquid container. Connection of the spray head assembly 20 to the barrel interface 11 of the spray gun platform 10 may be achieved by any suitable technique. For example, connection structures on the spray head assembly 20 may cooperate (e.g., mechanically interlock) with openings 11a and 11b at the barrel interface 11 to retain the spray head assembly 20 on the spray gun platform 10.

[0106] The spray gun platform 10 depicted in Figure 1 defines a variety of cavities that, taken together, form the passages that deliver gas to the spray head assembly 20.

[0107] Among other features, the spray gun platform 10 includes a fitting 12 such that the gas supply passages in the spray gun platform 10 can be connected to a gas source (not shown) that supplies gas to the spray gun platform 10 at greater than atmospheric pressure. A needle passage is also provided in the spray gun platform 10 to allow a needle 14 to pass into a spray head assembly 20 attached to the barrel interface 11. Control over both gas flow and liquid flow through the liquid spray gun is, in the depicted embodiment, provided by a trigger 15 that is pivotally engaged to the spray gun platform 10 by a retaining pin 16a and clip 16b. The needle 14 extends through the spray head assembly 20. The trigger 15 is preferably biased to the inoperative position in which needle 14 closes the liquid nozzle opening in the spray head assembly 20 and also closes a gas supply valve 17. When the trigger 15 is depressed, needle 14 is retracted to a position in which its tapered front end 14a allows liquid to flow through liquid nozzle tube outlet in the spray head assembly 20. At the same time, gas supply valve 17 also opens to deliver gas to the spray head assembly 20 from the passages in the spray gun platform 10. Gas and liquid flow may be further controlled by a fan gas control assembly 18a which controls gas delivered to a fan gas passage outlet 19a and to atomizing gas outlet 19b from the gas supply manifold in the platform 10, and atomizing gas control assembly 18b which restricts how far the trigger 15 may be depressed and thereby limits the total flow of gas and paint. In particular, the control assembly 18b controls the atomizing gas/liquid stream emanating from the spray head assembly 20, and control assembly 18a controls gas flow to the air horns (if provided) of the spray head assembly 20 to adjust the spray pattern geometry.

[0108] The spray head assembly 20 includes a barrel 30, an air cap 40 attached to the barrel 30, and a nozzle body 1 according to the present disclosure, attached to a nozzle port on the barrel 30. The 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.

[0109] Figure 2 illustrates, in a perspective view, the nozzle body 1 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 liquid spray gun platform 10 at the barrel interface 11.

[0110] The barrel 30 has a liquid inlet 73 through which the liquid 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 a connector structure via which a liquid container (not shown), such as a liquid paint cup, can be connected to the barrel 30. The liquid can flow from the liquid container through the liquid inlet 73 and a liquid passage in the barrel 30 into a nozzle tube passage of the nozzle body 1. The liquid is sprayed through a circular nozzle tube outlet 52 in the front of the nozzle body 1 and exits the nozzle tube passage into outside air in a spray direction 300 along a spray axis 200 which passes through the center of the nozzle tube outlet 52. The shape of the nozzle body 1 is rotationally symmetric about the spray axis 200.

[0111] The barrel 30 and the nozzle body 1 are shown before an air cap 40 is arranged over the front portion 36 of the barrel 30, so that an atomizing gas passage 33 in the barrel 30 is visible through which pressurized atomizing gas flows through the barrel 30 toward the nozzle tube outlet 52.

[0112] 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 for conducting pressurized atomizing gas towards an atomizing gas outlet 54 (see Figure 3) arranged circumferentially around the nozzle tube outlet 52.

[0113] Figure 3 illustrates, in a perspective view, the barrel 30 and the nozzle body 1 of Figures 1 and 2 with an air cap 40 mounted over them, together forming the spray head assembly 20. The outer surface 75 of the nozzle body 1 at the nozzle tube outlet 52 forms a first portion of a delimiting surface of an atomizing gas passage 33 for conducting pressurized atomizing gas towards an annular atomizing gas outlet 54 arranged circumferentially around the nozzle tube outlet 52, such that the atomizing gas exits the atomizing gas passage 33 into outside air at the atomizing gas outlet 54 and atomizes liquid after the liquid has exited the nozzle tube outlet 52.

[0114] The air cap 40 comprises two air horns 43a, 43b, arranged opposite to each other. So-called shaping gas 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 on the air horns 43a, 43b are located on opposite sides of the spray axis 200 such that shaping gas flowing through the barrel 30 under greater than atmospheric pressure is directed against opposite sides of a jet of atomized liquid exiting the nozzle tube outlet 52 into outside air in the spray direction 300. The forces exerted by the shaping gas can be used to change the shape of the jet of atomized liquid to form a desired spray pattern (e.g., circular, elliptical, etc.).

[0115] Figure 4 is a longitudinal sectional view of the spray head assembly 20 of Figure 3, which comprises the nozzle body 1 according to the present disclosure. The nozzle body 1 comprises a nozzle tube 66 having a nozzle tube wall 71 which, in this embodiment, has the shape of a funnel narrowing towards the nozzle tube outlet 52. The liquid to be sprayed flows through the liquid inlet 73, through the barrel 30 and passes, from a nozzle tube inlet 57, through an elongated nozzle tube passage 58 to the nozzle tube outlet 52 through which, in use, the liquid exits the nozzle Tube passage 58 into outside air in the spray direction 300 along the spray axis 200. The length direction of the nozzle tube passage 58 defines axial directions 220 and radial directions 210 orthogonal to the axial directions 220. The spray direction 300 is an axial direction 220.

[0116] The rear portion 38 of barrel 30 can be attached to the liquid spray gun platform 10 at the barrel interface 11, as shown in Figure 1, so that the spray gun platform 10 and the spray head assembly 20 form a complete liquid spray gun.

[0117] Once connected with the nozzle body 1, the air cap 40 is rotationally symmetric about the spray axis 200. It has a front wall 60 which forms a circular nozzle aperture delimited by a nozzle aperture edge 64. In this embodiment the forward end of the nozzle tube 66 is arranged in the nozzle aperture delimited by the nozzle aperture edge 64 of the front wall 60 such that the nozzle tube outlet 52 is almost flush with the front surface 62 of the air cap 40 which faces generally in the spray direction 300.

[0118] 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 radially outer surface 75 of the nozzle tube wall 71. The atomizing gas outlet 54 therefore has an annular shape and is arranged circumferentially around the nozzle tube outlet 52.

[0119] 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 tubular nozzle tube 66, which in turn comprises the elongated nozzle tube passage 58, extending lengthwise between a nozzle tube inlet 57 (not visible in Figure 5) through which, in use, liquid enters the nozzle tube 66, and the nozzle tube outlet 52, through which, in use, the liquid exits the nozzle tube passage 58 into outside air 93 in the spray direction 300. The nozzle tube outlet 52 defines the precise axial position (indicated by a plane 330 of the nozzle tube outlet 52) at which the liquid exits the nozzle tube passage 58 into outside air 93. The length direction of the nozzle tube passage 58 defines axial directions 220 and radial directions 210 orthogonal to the axial directions 220. In the embodiment of Figure 5, the nozzle tube 66 is rotationally symmetric about a tube symmetry axis 230, so that the length direction of the nozzle tube passage 58 and the spray direction 300 are both parallel to the tube symmetry axis 230, and the spray axis 200 and the tube symmetry axis 230 are identical. In the embodiment of Figure 5, a terminal section 159 of the nozzle tube passage 58 (i.e. the axial section 159 in the vicinity of the nozzle tube outlet 52) has a cylindrical shape, i.e. it has a circular cross section which is constant in axial directions 220 along its length.

[0120] The nozzle tube 66 also comprises the nozzle tube wall 71 which comprises the radially outer surface 75 and the opposed radially inner surface 76. The inner surface 76 delimits the nozzle tube passage 58 and is in contact with the liquid when the nozzle body 1 and the spray gun to which it is mounted are in use.

[0121] The spray direction 300 through a centroid 310 of the cross section of the nozzle tube outlet 52 defines the spray axis 200. The cross section of the nozzle tube outlet 52 has the shape of a circular disc. The nozzle tube outlet 52 is arranged around, and comprises, the spray axis 200. It comprises the spray axis 200, because at the centroid 310 liquid exits the nozzle tube outlet 52. The liquid exits the nozzle tube outlet 52 in a well-defined direction (the spray direction 300). Turbulence introduces irregular velocities into the liquid only a short time after the liquid has exited the nozzle tube outlet 52 and only at positions somewhat downstream from the plane 330 of the nozzle tube outlet 52.

[0122] The outer surface 75 of the nozzle tube wall 71 is operable to form, in conjunction with a surface of a suitable air cap 40 (not shown) when the air cap 40 is connected directly or indirectly with the nozzle body 1, an atomizing gas outlet 54 (see Figure 6) arranged circumferentially around the nozzle tube outlet 52, such that pressurized atomizing gas 110 exits into outside air 93 through the atomizing gas outlet 54 and atomizes the liquid after the liquid has exited the nozzle tube outlet 52.

[0123] The outer surface 75 of the nozzle tube wall 71 at the nozzle tube outlet 52 (i.e. in a nozzle tube outlet plane 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 from the spray axis 200. In the embodiment of Figure 5 the outer surface 75 of the nozzle tube wall 71 at the nozzle tube outlet 52 appears "ramped" in the longitudinal sectional view. The ramp angle α (alpha) may be considered the divergence angle α of the ramped axial section 77, measured in the nozzle tube outlet plane 330 against the spray axis 200. In a longitudinal sectional view of the nozzle body 1, taken through the spray axis 200, the ramp angle α can usually be easily visualized and measured. The ramped axial section 77 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 liquid flowing in the spray direction 300. Due to the rotational symmetry of the nozzle body 1, the ramped axial section 77 in the sectional view of Figure 5 corresponds to a conical axial section 77 of the outer surface 75 of the nozzle tube wall 71 at the nozzle tube outlet 52, where the larger-diameter end of the conical axial section 77 is located at the axial position of the nozzle tube outlet 52 (i.e. in the nozzle tube outlet plane 330), and where the smaller-diameter end of the conical axial section 77 is located upstream from the nozzle tube outlet 52. "Upstream" refers to a position located in a direction opposite to the spray direction 300.

[0124] The outer surface 75 of the nozzle tube wall 71 may exhibit curvature discontinuities (e.g. steps, corners, etc.) as shown in Figure 5. 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.

[0125] In the embodiment of Figure 5 the ramped axial section 77 diverges from spray axis 200 and from the spray direction 300 by an angle α of about 20°, in the longitudinal sectional view of Figure 5. By virtue of that ramped axial section 77, some of the atomizing gas 110 has a velocity vector, at the nozzle tube outlet 52 (i.e. in the nozzle tube outlet plane 330), which is directed angularly away from the spray axis 200 and from the spray direction 300 by an angle of about 20°. This diverging flow of atomizing gas 110 causes the pressure of outside air at the nozzle tube outlet 52 to be lower than in traditional nozzle geometries in which atomizing gas flows in directions parallel to the spray axis 200 or towards the spray axis 200. In the embodiment of Figure 5 the lower pressure at the nozzle tube outlet 52 draws more liquid from the nozzle passage 58 and increases the liquid flow rate, compared to traditional nozzle bodies, assuming identical pressure of the supplied pressurized atomizing gas.

[0126] In the embodiment of Figure 5 the ramped axial section 77 appears as a straight line in the longitudinal sectional view, relating to a constant divergence angle α (alpha) over the axial length of the ramped axial section 77. It is contemplated that in alternative embodiments the ramped axial section 77 may be a curved line in the longitudinal sectional view, relating to an increasing divergence angle α (alpha) over the axial length of the ramped axial section 77 from a rearward, upstream portion towards the nozzle tube outlet plane 330. The divergence angle of the outer surface 75 of the nozzle tube wall 71, measured against the spray axis 200, is larger at the nozzle tube outlet 52 (that is, in the nozzle tube outlet plane 330) than further rearward, i.e. at an axial position further upstream. The divergence angle α, however, is considered the divergence angle in the plane of the nozzle tube outlet 52, i.e. in the nozzle tube outlet plane 330. The divergence angle can be determined in a longitudinal sectional view, taken through the spray axis 200, of the nozzle tube wall 71. It is also the nozzle tube outlet plane 330 (and not an axial position further rearward or further upstream) in which the shape or orientation of the outer surface 75 of the nozzle tube wall 71 directs a portion of the atomizing gas 110 exiting the atomizing gas outlet 54 angularly away from the spray axis 200.

[0127] Figure 6 is a further longitudinal sectional view of a forward portion of the nozzle body 1 of Figures 4 and 5 and a forward portion of the air cap 40 shown in Figure 4.

[0128] The air cap 40 is rotationally symmetric about the spray axis 200. It is connected with the nozzle body 1 via a barrel 30 (not shown), 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 a nozzle aperture edge 64 and radially-inwardly delimited by the nozzle tube wall 71 at the nozzle tube outlet 52.

[0129] The air cap 40 has a front wall 60 which forms a circular nozzle aperture delimited by the circular nozzle aperture edge 64. The forward end of the nozzle tube 66 is arranged in the nozzle aperture of the front wall 60 such that the nozzle tube outlet 52 protrudes forward, in the spray direction 300, by a small distance from the front surface 62 of the air cap 40.

[0130] 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. The atomizing gas outlet 54 therefore has an annular shape and is arranged circumferentially around the nozzle tube outlet 52.

[0131] In the embodiment of Figure 6 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 77 of the outer surface 75 of the nozzle tube wall 71) angularly away from the spray axis 200 and thus to cause the pressure of outside air at the nozzle tube outlet 52 to be lower than in traditional nozzle geometries in which the atomizing gas flows in directions parallel to the spray axis 200 or towards the spray axis 200, and in which no portion of the atomizing gas 110 flows angularly away from the spray axis 200.

[0132] Figure 7 is a longitudinal sectional view of a forward portion of the nozzle body 1 of Figures 4 to 6, connected with an alternative, second air cap 41. The second air cap 41 is identical with the first air cap 40 of Figures 4 to 6, except that its nozzle aperture edge 64 is oriented and shaped to direct a portion of the pressurized atomizing gas 110 exiting the atomizing gas outlet 54 angularly away from the spray axis 200. The nozzle aperture edge 64 is rotationally symmetric relative to the spray axis 200, but in the longitudinal sectional view of Figure 7 it is not parallel to the spray axis 200 and to the spray direction 300, but it is ramped. The surface of the nozzle aperture edge 64 thus forms a conical surface, centered about the spray axis 200 and opening up in the spray direction 300.

[0133] Compared to the first air cap 40 of Figure 6, the conically shaped nozzle aperture edge 64 of the second air cap 41 of Figure 7 helps direct more pressurized atomizing gas 110 angularly away from the spray axis 200. It thereby causes the pressure of outside air at the nozzle tube outlet 52 to be even lower and helps to extract more liquid from the nozzle tube passage 58 while the amount of pressurized atomizing gas 110 remains the same.

[0134] Figures 8a and 8b show in longitudinal sectional views pressure distributions in front of respective nozzle tube outlets 52 as they were simulated by the inventors of the present disclosure using a Computational Fluid Dynamics (CFD) software package called FLUENT (available from ANSYS Inc., Canonsburg, PA, U.S.A.). Areas of pressure lower than atmospheric pressure ("low-pressure zones") are located within the low-pressure boundary 237 in front of the respective nozzle tube outlet 52.

[0135] The pressure diagram of Figure 8A illustrates a pressure distribution obtained, in a simulation, with a traditional nozzle body 99, in conjunction with an air cap 40, which does not direct any portion of the pressurized atomizing gas exiting the atomizing gas outlet 54 angularly away from the spray axis 200. The low-pressure boundary 237 extends downstream from the nozzle tube outlet 52 by a certain distance and reaches its maximum axial distance from the plane of the nozzle tube outlet 52 at a certain radial distance from the spray axis 200, resulting in two "bumps" in the sectional view of Figure 8A.

[0136] Figure 8B illustrates a pressure distribution obtained, in a simulation under otherwise identical conditions, with a nozzle body 1 according to the present disclosure which directs a portion of the pressurized atomizing gas 110 exiting the atomizing gas outlet 54 angularly away from the spray axis 200 via the shape and orientation of the outer surface 75 of the nozzle tube wall 71 at the axial position of the nozzle tube outlet 52.

[0137] A comparison of Figure 8B with Figure 8A shows that the low-pressure zone generated by a nozzle body 1 according to the present invention (Figure 8B) is considerably larger in size than the low-pressure zone generated by the traditional nozzle body 99 (Figure 8A), at otherwise identical conditions. The larger size of the low-pressure zone encircled by the low-pressure boundary 237 in the inventive nozzle body 1 contributes to a more effective extraction of liquid from the nozzle tube passage 58 and an increased liquid (e.g. paint) flow rate, compared with traditional nozzle bodies 99, without increasing the consumption of pressurized atomizing gas.

[0138] Where a nozzle body 1 according to the present disclosure with its higher liquid flow rate is used in a spray gun, the pressure and/or volume of the pressurized atomizing gas can be reduced to obtain a lower liquid flow rate similar to those liquid flow rates obtained with traditional nozzle bodies 99. This reduction in atomizing gas pressure and/or volume may result in energy and cost savings. The reduction in atomizing gas pressure typically also results in less high-frequency noise or in lower volume of high-frequency noise during spraying operations, which reduces health risks for human spray gun operators. Also, where a nozzle body 1 according to the present disclosure is used, less overspray has been observed, resulting in an increased transfer efficiency.

[0139] Figure 9 is an x-y diagram illustrating liquid flow rates through the nozzle tube outlet for certain nozzle bodies according to the present disclosure and liquid flow rates for certain traditional nozzle bodies. The ramp angle α (alpha) explained above, e.g. in the context of Figure 5, is shown on the x-axis, while the y-axis shows a computed paint flow rate in gram per second (g/s) for nozzle bodies having different ramp angles. The paint flow rates in the diagram are simulated paint flow rates, simulated using computational fluid dynamics simulation software. Except for the ramp angle, all other parameters have been kept unchanged.

[0140] As explained in the context of Figure 5, a ramped axial section 77 of the outer surface 75 of the nozzle tube wall 71 at the nozzle tube outlet 52 provides the flow of pressurized atomizing gas 110 with a radial velocity component angularly away from the spray axis 200.

[0141] The diagram of Figure 9 shows that paint flow rates for nozzle bodies in which the outer surface of the nozzle tube wall has respective ramp angles of 5° and 10° are considerably higher than for traditional nozzle bodies in which the outer surface of the nozzle tube wall has no ramp, i.e. in which the ramp angle is 0°.

Claims

1. Nozzle body (1) for a liquid spray gun for spraying a liquid, the nozzle body (1) comprising a tubular nozzle tube (66), comprising

a) an elongated nozzle tube passage (58), extending lengthwise between a nozzle tube inlet (57) through which, in use, liquid enters the nozzle tube (66), and a nozzle tube outlet (52), through which, in use, the liquid exits the nozzle tube passage (58) into outside air (93) in a spray direction (300),
wherein the length direction of the nozzle tube passage (58) defines axial directions (220) and radial directions (210) orthogonal to the axial directions,

b) a nozzle tube wall (71) having a radially outer surface (75) and an opposed radially inner surface (76) delimiting the nozzle tube passage (58) and being, in use, in contact with the liquid,

wherein the spray direction (300) through a centroid (310) of the cross section of the nozzle tube outlet (52) defines a spray axis (200), wherein the nozzle tube outlet (52) is arranged around, and comprises, the spray axis (200),

wherein the outer surface (75) of the nozzle tube wall (71) is operable to form, in conjunction with a surface (64) of an air cap (40, 41) when the air cap (40, 41) is connected directly or indirectly with the nozzle body (1), an atomizing gas outlet (54) arranged circumferentially around the nozzle tube outlet (52), such that the pressurized atomizing gas (110) exits into outside air (93) through the atomizing gas outlet (54) and atomizes the liquid after the liquid has exited the nozzle tube outlet (52),

characterized in that the outer surface (75) of the nozzle tube wall (71) is oriented or shaped to direct at least a portion of the pressurized atomizing gas (110) exiting the atomizing gas outlet (54) angularly away from the spray axis (200).

2. Nozzle body (1) according to claim 1, wherein the outer surface (75) of the nozzle tube wall (71) is oriented or shaped to direct at least a portion of the pressurized atomizing gas (110) exiting the atomizing gas outlet (54) angularly away from the spray axis (200) at an angle (α) of between 0.5° and 45°.

3. Nozzle body (1) according to claim 1 or claim 2, wherein the outer surface (75) of the nozzle tube wall (71) comprises a ramped axial section (77), such as a ramped axial section (77) at the nozzle tube outlet (52), for directing at least a portion of the pressurized atomizing gas (110) exiting the atomizing gas outlet (54) angularly away from the spray axis (200).

4. Nozzle body (1) according to claim 3, wherein the ramped axial section (77) forms a ramp angle (α) with the spray axis (200), and wherein the ramp angle (α) is between 0.5° and 45°.

5. Nozzle body according to any one of claims 3-4, wherein the ramp angle (α) at a first circumferential position of the outer surface (75) of the nozzle tube wall (71) is different from the ramp angle (α) at a second circumferential position of the outer surface (75) of the nozzle tube wall (71).

6. Nozzle body (1) according to any one of the preceding claims, wherein the outer surface (75) of the nozzle tube wall (71) comprises a gas-directing portion (77) for directing at least a portion of the pressurized atomizing gas (110) exiting the atomizing gas outlet (54) angularly away from the spray axis (200), and wherein the gas-directing portion (77) has the shape of the radially-outer surface of a truncated cone.

7. Nozzle body (1) according to any one of the preceding claims, wherein the outer surface (75) of the nozzle tube wall (71) at the nozzle tube outlet (52) is circular in cross section, taken in a plane orthogonal to the spray axis (200).

8. Nozzle body (1) according to claim 6, wherein the outer surface (75) of the nozzle tube wall (71) at the nozzle tube outlet (52) extends circumferentially for a full 360° angle.

9. Nozzle body (1) according to any one of the preceding claims, wherein the outer surface (75) of the nozzle tube wall (71) at the nozzle tube outlet (52) is oriented or shaped to direct at least a portion of the pressurized atomizing gas (110) exiting the atomizing gas outlet (54) angularly away from the spray axis (200).

10. Nozzle assembly (20) comprising a nozzle body (1) according to any one of the preceding claims and an air cap (40), connected with the nozzle body (1) in a fixed spatial relation,

wherein the air cap (40) comprises a front wall (60) facing generally in the spray direction (300) and comprising a nozzle aperture delimited by a nozzle aperture edge (64),

and wherein the nozzle tube (66) is arranged in, or protrudes outwardly through, the nozzle aperture, such that the atomizing gas outlet (54) is formed between the nozzle aperture edge (64) and the nozzle tube wall (71).

11. Nozzle assembly (20) according to claim 10, wherein the nozzle aperture edge (64) is oriented or shaped to direct at least a portion of the pressurized atomizing gas (110) exiting the atomizing gas outlet (54) angularly away from the spray axis (200).

12. Nozzle assembly (20) according to any one of claims 10-11, wherein the nozzle tube outlet (52), the nozzle tube wall (71), the nozzle aperture edge (64), and the atomizing gas outlet (54) are each of rotationally symmetric shape and arranged concentrically with respect to the spray axis (200).

13. Nozzle assembly (20) according to any one of claims 10-12, further comprising a barrel (30) having a liquid port connector (74) for directly or indirectly connecting a liquid reservoir to the barrel (30), wherein the air cap (40) is connected with the barrel (30) and the nozzle body (1) is connected with the barrel (30), such that the air cap (40) is connected with the nozzle body (1) in a fixed spatial relation.

14. Liquid spray gun for spraying a liquid, comprising a nozzle body (1) according to any one of claims 1-9, or a nozzle assembly (20) according to any one of claims 10-13.

15. Non-transitory machine-readable medium having data stored thereon representing a three-dimensional model of a nozzle body (1) according to any one of claims 1-9 or of a nozzle assembly (20) according to any one of claims 10-13, the data being formatted to be accessed by one or more digital processors interfacing with a 3D printer, wherein the one or more digital processor(s) is/are operable to cause the 3D printer to manufacture the nozzle body (1) according to any one of claims 1-9 or the nozzle assembly (20) according to claims 10-13.

Drawing