Fluid dispensing apparatus

Abstract

A fluid dispensing apparatus (100) includes a main dispenser body member (105) having an internal air flow chamber (155). An electric motor (150) is seated within the air flow chamber (155). A removable fluid delivery unit (205) comprises a receptacle (200) and an attached paint nozzle (300). A battery (130) is configured to supply electricity to the electric motor (150), wherein the electric motor (150) is configured to pump air through the air flow chamber (155) into a proximal end of the nozzle (300).

Description

Fluid Dispensing ApparatusField of the Invention

[0001] The present invention relates to apparatus for dispensing fluids, such as for example liquids or aerosols including paint, sealers, primers, lacquers and other flowable substances such as powders.

[0002] In one example application, the present invention relates to apparatus for dispensing paints of the type for example used in industries including automotive, marine, industrial chemicals, wood working and construction. However, it will be appreciated that the apparatus may have applications for painting and surface coati ng / treatment in various fields of technology.Background of the Invention

[0003] Any reference herein to known prior art does not, unless the contrary indication appears, constitute an admission that such prior art is commonly known by those skilled in the art to which the invention relates, at the priority date of this application.

[0004] Aerosol paint (commonly known as spray paint) is paint that comes in a sealed, pressurised can, and is released in an aerosol spray when a valve button is pressed. Spray paint cans are not refillable, and they are discarded once the paint has been used.

[0005] Propellants such as di-methyl ether or a mixture of propane and butane are commonly used in aerosol cans to provide a pressure force to void the contents of the can when the valve or nozzle is activated. However, there are increasing environmental concerns regarding the release of such chemicals and gases into the atmosphere, noting that aerosol paints may release volatile organic compounds and other pollutants (such as formaldehyde, benzene, and lead) to the atmosphere.

[0006] A further problem with aerosol paints is that they are classified as pressurised dangerous goods, which makes them dangerous and costly to transport.

[0007] Aerosol spray cans are commonly used in small scale applications, such as automotive touch-ups. Aerosol cans are not normally used for larger projects, such as entire vehicle bodywork painting, which is normally performed with specialised sprayingequipment. This is primarily due to the limited quality provided by the built in nozzle, which may limit the quality of the paint finish. Furthermore, aerosol spray cans are cost prohibitive when used on large scare applications.

[0008] In contrast to aerosol spray cans, pneumatic spray guns use compressed air or other gases, normally provided by an air compressor (or other source) to mix air with the paint so the paint becomes aerosolised and atomised which assists the paint to be sprayed and applied to a workpiece. Conventional air spray guns require a high amount of pressure.

[0009] Electric and battery powered spray guns have also been more recently developed that use built in electric turbines or liquid impellers to provide the force to pressurise and propel the paint from a reservoir onto the surface to be painted. Such electric and battery powered spray guns are designed for trade or larger scale use and they are typically bulky and much larger than aerosol cans.

[0010] Generally speaking, conventional spray guns, are normally used for larger projects. One aspect of conventional spray gun systems is that the nozzle and the paint pot are permanent components of the gun, and they must be thoroughly cleaned between colours and / or at the end of a paint run, to prevent the nozzle becoming blocked, and to ensure there is no colour contamination with subsequently run colours.

[0011] Whilst the air gun nozzle can typically dispense paint in a more uniform and consistent manner when compared with aerosol cans, there are some inherent drawbacks with existing air spray gun systems.

[0012] Primarily, the cleaning process is time intensive and requires the use of thinners or solvents, which can be environmentally undesirable, difficult to purchase in small quantities and difficult to dispose of.

[0013] Furthermore, the air source, normally in the form of a compressor, provides drawbacks in the form of additional noise and the operator must carefully manage the air hose when moving about the workspace. Similarly, with electric turbine spray guns, the operate must carefully manage the power cable.Summary of the Invention

[0014] In a first aspect the present invention provides a fluid delivery unit for use in fluid dispensing apparatus, the apparatus comprising: a main dispenser body, having an air flow chamber therein;an air discharge port in an end wall of the main dispenser body and through which an airflow can be discharged from the airflow chamber; an airflow generator for generating an airflow stream from the airflow chamber through the discharge port in an airflow stream direction; the fluid delivery unit being adapted to be releasably mountable to the main dispenser body in an installed position, and including: a fluid holding receptacle; a fluid feed passage through which fluid can be discharged from the fluid holding receptacle; a nozzle fixedly secured to the fluid holding receptacle, so as to provide for a unitary structure; the nozzle, including a proximal end, adjacent the discharge port when in the installed position, a distal end, a nozzle outlet and a fluid transfer passage arrangement, which includes an airflow passage in fluid communication with the discharge port,

[0015] the fluid feed passage being in fluid communication with the fluid transfer passage arrangement.

[0016] In certain embodiments the fluid feed passage is in fluid communication with the fluid transfer passage arrangement in a fluid junction region adjacent the proximal end of the nozzle.

[0017] In certain embodiments the fluid transfer passage arrangement is unobstructed from the junction region to the nozzle outlet.

[0018] In certain embodiments the fluid transfer passage arrangement is configured, so as to draw fluid from the fluid holding receptacle into the fluid transfer passage arrangement in response to the travel of the airflow stream through the nozzle airflow passage.

[0019] In certain embodiments the nozzle airflow passage, includes a reduced pressure zone in which a low pressure is produced relative to upstream of the reduced pressure zone as a result of the airflow stream as it travels along the airflow passage, the fluid feed passage being in fluid communication with the reduced pressure zone.

[0020] In certain embodiments the airflow passage has a cross-sectional dimension in the reduced pressure zone, which is less than the cross-sectional dimension of the airflow passage upstream thereof.

[0021] In certain embodiments the fluid transfer arrangement includes a fluid transfer passage which is in fluid communication with the fluid feed passage.

[0022] In certain embodiments the airflow passage and the fluid transfer passage are provided by a common passageway configured to transfer the airflow stream and flow from the fluid receptacle via the fluid feed passage towards the nozzle outlet.

[0023] In certain embodiments the reduced pressure zone is provided by a venturi within the airflow passage.

[0024] In certain embodiments the fluid transfer passage and airflow passage are separate passageways along their length, the passageways at least in part tapering towards the distal end at which the passages are in fluid communication in a mixing region which provides for the low pressure zone.

[0025] In certain embodiments the nozzle comprises an elongated body having an outer sidewall with a longitudinal axis extending between the ends.

[0026] In certain embodiments the fluid feed passage extends through the sidewall of the nozzle body, so as to be in fluid communication with the fluid transverse arrangement.

[0027] In certain embodiments the unit including a valve disposed within the fluid feed passage and operable to open and close the fluid feed passage.

[0028] In certain embodiments the valve comprises a valve head disposed within the fluid, feed passage and a valve stem which extends from the fluid feed passage.

[0029] In a second aspect the present invention provides fluid dispensing apparatus, comprising: a main dispenser body, having an air flow chamber therein; an air discharge port in an end wall of the main body and through which an airflow can be discharged from the airflow chamber; an airflow generator for generating an airflow stream from the airflow chamber through the discharge port in an airflow stream direction; the apparatus further comprising: a fluid delivery unit as described above which is releasably mountable to the main body in an installed position.

[0030] In certain embodiments the nozzle, when in the installed position is disposed wholly externally of the airflow chamber.

[0031] In certain embodiments the airflow chamber has an internal wall which tapers towards the discharge port.

[0032] In certain embodiments the longitudinal axis is substantially aligned with the airflow stream from the discharge port and the airflow generator.

[0033] In certain embodiments the main dispenser body includes a mounting arrangement for releasably mounting the fluid delivery unit to the main body.

[0034] In certain embodiments the mounting arrangement includes a trough shaped support member which extends from the end wall of the main body adjacent the discharge port and terminates at an outer end, the support member being shaped so as to receive a complementary shaped portion of the nozzle body therein, the mounting arrangement further including a recessed retaining member configured to overlie the nozzle body, when in the installed position and a locking member configured to releasably hold the support member and retaining member together.

[0035] In certain embodiments the apparatus includes an actuator for activating the airflow generator.

[0036] In certain embodiments the actuator further controls the opening and closing of the fluid feed passage.

[0037] In certain embodiments the actuator is operable so as to control the speed of the airflow generator.

[0038] In certain embodiments the actuator comprises a trigger member moveable between an initial position and an activating position.

[0039] In certain embodiments the apparatus includes a valve disposed within the fluid feed passage and is operable to open and close the fluid feed passage

[0040] In certain embodiments the valve comprises a valve head disposed withing the fluid feed passage and a valve stem which extends from the fluid feed passage.

[0041] In certain embodiments the trigger member is adapted to engage the valve stem.

[0042] In certain embodiments the valve stem extends through the nozzle and through an aperture in trough shaped support member.

[0043] In certain embodiments the valve stem has an outer end which is in engagement with the actuator.

[0044] In certain embodiments the outer side wall of the nozzle body has a tapering cross-section such that an external cross-section nozzle body decreases toward nozzle outlet.

[0045] In certain embodiments the nozzle includes an air pressure sensitive valve configured to open when the speed of the airflow generated by the airflow generator exceeds a predetermined threshold.

[0046] In a third aspect, the present invention provides a fluid dispensing apparatus including: a body member having an internal air flow chamber; an electric motor seated within the air flow chamber; a removable fluid assembly comprising a fluid holding receptacle and an attached nozzle; a battery or power source configured to supply electricity to the electric motor; wherein the electric motor is configured to pump air through the air flow chamber into a proximal end of the nozzle.

[0047] In certain embodiments the nozzle has a nozzle inlet in fluid communication with the internal air flow chamber and a nozzle outlet, and the fluid holding receptacle is connected to the nozzle between the nozzle inlet and the nozzle outlet.

[0048] in certain embodiments the nozzle has an internal passage that is at least partially conically tapering to a reduced cross-sectional area toward the nozzle outlet.

[0049] in certain embodiments the internal passage is defined by a central passage and a separate radially outer passage, the central passage being in fluid communication with the fluid holding receptacle and the radially outer passage being in fluid communication with the air flow chamber, the central passage and the radially outer passage converging at or near the nozzle outlet.

[0050] in certain embodiments the internal passage includes a venturi configured to create an area of low pressure to draw fluid out of the fluid holding receptacle.

[0051] In certain embodiments a fluid feed passage extends from the fluid handling receptacle to a portion of the internal passage at or near a portion of the venturi having a smallest cross-sectional area.

[0052] In certain embodiments the nozzle includes a valve configured to control fluid flow from the fluid holding receptacle into the nozzle.

[0053] in certain embodiments the body member includes a semi-tubular channel adapted to engage with a semi-tubular collar to define an enclosed cylindrical section sized to receive an outer portion of the nozzle.

[0054] in certain embodiments the apparatus further comprises a locking nut having an internally threaded portion configured to engage with external threads located on each of the semi-tubular channel and the semi-tubular collar.

[0055] In certain embodiments radially outer surface of the nozzle has a tapering cross-section such that an external diameter of the nozzle decreases toward the nozzle tip.

[0056] In certain embodiments the locking nut is configured to engage the radially outer surface of the nozzle to urge the nozzle toward the body member when the locking nut is tightened.

[0057] In certain embodiments the apparatus comprises a trigger configured to operate both: the electric motor; and a valve which is in fluid communication with the fluid holding receptacle.

[0058] In certain embodiments the trigger is a variable position sensitive trigger.

[0059] In certain embodiments the nozzle includes an air pressure sensitive valve configured to open when the motor speed exceeds a predetermined threshold.

[0060] In a third aspect, the present invention provides a removable assembly which preferably comprises a fluid holding receptacle and an attached paint nozzle,wherein the nozzle has a nozzle inlet and a nozzle outlet, and the fluid holding is connected to the nozzle between the nozzle inlet and the nozzle outlet.

[0061] In certain embodiments the nozzle has an internal conically tapering passage that reduces in cross sectional area between the nozzle inlet and the nozzle outlet.

[0062] In certain embodiments the nozzle includes a valve configured to control fluid flow through the nozzle outlet.

[0063] In certain embodiments an air and fluid feed tube extends between the internal conically tapering passage and the fluid holding receptacle.In a fourth aspect, the present invention provides a method of assembling a fluid dispensing apparatus, the method including the following steps: obtaining a removable fluid delivers unit comprising a fluid holding receptacle and an attached paint nozzle; locating the nozzle adjacent to an outlet of an air flow chamber extending within a body portion of the apparatus; and hermetically securing the nozzle to the body portion so that a fluid flow path extends from the air flow chamber into the nozzle.Brief Description of the Drawings

[0064] The present invention will become more fully understood from the following detailed description of preferred but non-limiting embodiments thereof, described in connection with the accompanying drawings, wherein:Figure 1 is a side view of a first embodiment of apparatus according to the invention;Figure 2 is a cross-sectional side view of the apparatus of Figure 1 ;Figure 2A is a detail of part of the apparatus shown in Figure 2;Figure 3 is a bottom perspective view of the part of the apparatus shown in Figure 1 ;Figure 4 is a side view of the part of the apparatus shown in Figure 3;Figure 5 is an exploded perspective view of the apparatus shown in of Figure 1 ;Figure 6 is a side view of the part of the apparatus shown in Figure 3;Figure 7 is a bottom, front perspective view of the part of the apparatus shown in Figure 3;Figure 8 is a bottom, rear perspective view of the part of the apparatus shown in Figure 3;Figure 9 is a side view of a second embodiment of apparatus according to the invention;Figure 10 is a cross-sectional side view of the apparatus shown in of Figure 9;Figure 10B is a detail of part of the apparatus shown in Figure 10; andFigure 11 is a side view of part of the apparatus shown in Figure 9.Detailed Description of Preferred Embodiments

[0065] Two embodiments of an apparatus 100 are depicted in the drawings. A first embodiment is shown in Figures 1 to 8, and a second embodiment is shown in Figures 9 to 11.

[0066] The apparatus will hereinafter be described in the context of a paint dispenser It will be appreciated however that it that it may be used for dispensing any industrial liquid intended for example for spraying, such as sealers, primers, lacquers and other flowable substances.

[0067] The apparatus 100 comprises two main parts namely a main dispenser body part 105 and a fluid delivery unit 205. The apparatus 100 is provided in a spray gun format with the main dispenser body 105 including a hand grip portion 110 and a trigger 120 which may for example be position sensitive. This permits the main body 105 to be ergonomically held and operated in one hand.

[0068] The fluid delivery unit 205 is mountable to the main dispenser body 105 in an installed position and includes a fluid holding receptacle 200 and a nozzle 300.

[0069] The receptacle 200 is provided within a pre-mixed ready to use consumable, single use unit 205 comprising the receptacle 200 and an attached nozzle 300. When a user purchases a receptacle 200 from a vendor such as a paint vendor, the receptacle 200 is provided with the nozzle 300 already attached. As such, the apparatus 100 does not have a permanent and reusable nozzle, and a new nozzle 300 is used with each newreceptacle 200. This significantly reduces the risk of paint contamination across successive jobs, and reduces cleaning time.

[0070] After the contents of the receptacle 200 have been dispensed, the entire paint unit 205 can be discarded and / or recycled. However, it will be appreciated that in some embodiments, the nozzle 300 may be reusable after cleaning, or returned to the manufacturer for cleaning and subsequent reuse.

[0071] As best illustrated in figures 2 and 2A the main dispenser body 105 has an air flow chamber 155 therein, an air discharge port 107 in an end wall 109 of the main dispenser body 105 through which an airflow can be discharged from the airflow chamber 155. An airflow generator 145 for generating an airflow stream from the airflow chamber 155 through the discharge port 107 in an airflow stream direction is located within the chamber 155. As shown the end wall 109 has an internal wall 111 which tapers towards the discharge port 107. The airflow generator may be in the form of an impeller 158 driven by motor 150.

[0072] The fluid delivery unit 205 is releasably mountable to the main dispenser body 105 in an installed position, and includes a fluid holding receptacle 200, a fluid feed passage 337 through which fluid, in the example embodiment described is paint can be discharged from the fluid holding receptacle 200. The nozzle 300 is fixedly secured to the fluid holding receptacle 200, so as to provide for a unitary structure. As shown in figures 3 and 4 the nozzle 300, includes a proximal end 302, adjacent the discharge port 107 when in the installed position, a distal end 304, and a nozzle outlet 320. A fluid transfer passage arrangement 375, which includes an airflow passage 376 is in fluid communication with the discharge port 107. The fluid feed passage 337 is in fluid communication with the fluid transfer passage arrangement 375.

[0073] As shown the nozzle 300, when in the installed position is disposed wholly externally of the airflow chamber 155 and main dispenser body 105. The fluid feed passage 337 is in fluid communication with the fluid transfer passage arrangement 375 at a fluid junction region 377 adjacent the proximal end 302 of the nozzle 300. As is apparent the fluid transfer passage arrangement 375 is unobstructed from the junction region 377 to the nozzle outlet 320.

[0074] The fluid transfer passage arrangement 375 is configured, so as to draw fluid from the paint holding receptacle 200 into the fluid transfer passage arrangement 375 in response to the flow of the airflow stream through the nozzle airflow passage 376. In theembodiment of figures 1 to 8 the fluid transfer passage arrangement 375 comprises a single passage which provides for the airflow passage 376 and a fluid transfer passage 380.

[0075] The nozzle airflow passage 376, includes a reduced pressure zone 334 in which a low pressure is produced relative to upstream of the reduced pressure zone 334 as a result of the airflow stream as it travels along the airflow passage 376, the fluid feed passage 337 being in fluid communication with the reduced pressure zone 334. The airflow passage 376 has a cross-sectional dimension in the reduced in the reduced pressure zone 334, which is less than the cross-sectional dimension of the airflow passage 376 upstream thereof. As shown in figure 2A the reduced pressure zone is provided by a venturi 360.

[0076] The nozzle 300 comprises an elongated body 311 having an outer sidewall312 with a longitudinal axis X-X extending between the ends 302, 304. The fluid feed passage 377 extends through the sidewall 312 of the nozzle body 311 , so as to be in fluid communication with the fluid transverse arrangement 375. The longitudinal axis X-X is substantially aligned with the airflow stream from the discharge port 107 and the airflow generator 145.

[0077] As best illustrated in figure 5 the main dispenser body 105 includes a mounting arrangement 160 for releasably mounting the paint delivery unit 205 to the main body. The mounting arrangement 160 includes a trough shaped support member 166 which extends from the end wall 109 of the main body 105 adjacent the discharge port 107 and terminates at an outer end 167, the support member 166 being shaped so as to receive a complementary shaped portion of the nozzle body 311 therein, the mounting arrangement further including a recessed retaining member 175 configured to overlie the nozzle body 311 , when in the installed position and a locking member 340 configured to releasably hold the support member 160 and retaining member 175 together.

[0078] The apparatus further includes an actuator 118 for activating the airflow generator 145. The actuator 118 further controls the opening and closing of the fluid feed passage 337. The actuator 118 is operable so as to control the speed of the airflow generator 145. The actuator 118 comprises a trigger member 120 moveable between an initial position and an activating position.

[0079] The apparatus includes a valve 330 disposed within the fluid feed passage 337 which is operable to open and close the fluid feed passage 337. The valve 330comprises a valve head 331 disposed within the fluid feed passage 337 and a valve stem 335 which extends from the fluid feed passage 337. The trigger member 120 includes a projection 121 which is adapted to engage the valve stem 335.

[0080] The valve stem 335 extends through the nozzle 300 and through an aperture 168 in trough shaped support member 165. The valve stem 335 has an outer end which is in engagement with the actuator.

[0081] The outer end wall of the nozzle body has a tapering cross-section such that an external cross-section nozzle body decreases toward nozzle outlet.

[0082] The nozzle includes an air pressure sensitive valve configured to open when the speed of the airflow generated by the airflow generator exceeds a predetermined threshold.

[0083] The apparatus 100 includes one or more batteries 130 for powering the electric motor 150 as described below. In the embodiment depicted, there are four batteries 130 shown within the grip portion 110. However, it will be appreciated that other combinations of batteries 130 may be used. For example, a single proprietary battery may be used.

[0084] Whilst the batteries 130 are depicted within the grip portion 110, it will be appreciated that the batteries 130 may alternatively be housed elsewhere within the spray gun 100.

[0085] The batteries 130 may be rechargeable and / or replaceable. For example, the batteries 130 may be housed in a removable cartridge enabling the cartridge (not shown) to be swapped out for recharging, to minimise downtime by cycling two or more like cartridges.

[0086] The batteries 130 are in electric communication with a control unit 185 which controls the power delivery to the motor 150. When the operator actuates the position sensitive trigger 120, the control unit 155 switches on the variable voltage DC power supply to the electric motor 150. The position sensitive trigger 120 enables the operator to control the motor speed between high and low rotational speeds, and intermediate speeds. This may be used to alter the paint spraying properties.

[0087] In addition, the position sensitive trigger 120 is mechanically associated with the valve 330 which seals and / or opens the receptacle 200. As shown in Figure 3, thevalve 330 is comprises a stem 335 which extends away from an underside of the receptacle 200.

[0088] As the trigger 120 is depressed, the stem 335 is moved upwardly, and the valve 330 is opened. The valve 330 is spring biased toward a closed position, and automatically closes when the operator releases the trigger 120. The further the trigger 120 is depressed, the more the valve 330 is opened.

[0089] The relationship between both the valve 330 and the motor speed, due to their mutual operation by the trigger 120 results in the paint volume increasing as the motor rotational speed increases.

[0090] The valve is seated in a passage 337 which extends between the receptacle 200 and the nozzle 300.

[0091] The electric motor 150 is an ultra-high RPM brushless variable speed DC motor capable of rotating at high speeds up to 100,000 rpm in order to generate significantly increased down-stream air pressure.

[0092] At the rear of the main dispenser body is an air inlet 170, best seen in Figures 1 and 2. The air inlet 170 has a filter and / or perforated screen to protect the impellor blades of the impeller 158 and the electric motor 150, and to reduce the likelihood of particulate matter or other contaminants being mixed with the paint.

[0093] The electric motor 150 is housed in the airflow chamber 155 which tapers to a reduced cross-section toward the nozzle 300. As shown in Figure 1 , the airflow chamber 155 has a largest cross-sectional area at or near the electric motor 150, to permit the air to move around he motor 150, and the airflow chamber 155 gradually tapers into a venturi 360 with a smallest cross-sectional area located at or near the interface where the valve stem 335 is seated in the passage 335.

[0094] The airflow chamber 155 is fluidly coupled to the upstream end of the nozzle 300. Coupling may be achieved by a taper-seal, male and female threads, a bayonet fitting, an abutting seal with a rubber gasket, or another hermetic coupling configured to prevent leakage of the pressurised air or paint.

[0095] As depicted in Figure 1 , the fluid flow passage within the nozzle 300 reduces at the venturi 360 from the proximal nozzle inlet, in the form of the interface 310 with the airflow chamber 155 toward the distal nozzle outlet 320. The nozzle outlet 320 may be sized to optimise the specific spray requirements of for example the particular paint can200 to which it is attached. For example, a water-based paint pot 200 may be supplied with a smaller nozzle outlet 320, whilst a more viscous enamel-based paint may be supplied with a larger diameter nozzle outlet 320. The nozzle 300 includes a hollow chamber located downstream of the venturi 360.

[0096] Different types of tip sizes can be used to achieve different spray patterns and different levels of atomization.

[0097] As mentioned earlier, the trigger 120 may be a variable position sensitive trigger. The position sensitive trigger control allows the user to modulate the variable speed motor 150 and the valve 330 to control working pressures between 140kpa (20psi) and 550kpa. (80psi) This will allow for adjustment for variable work conditions, different paint product viscosities and variable spray patterns.

[0098] For example, the following pressures may be generated in the paint pot 200:100 kPa to 140 kPa: Airbrushing, touch-up, shading, and thin finish materials;140 kPa to 170 kPa: solvent based lacquers;240 to 310 kPa: average spraying range for sealing and top coating;Up to 350 kPa: water-based lacquers.

[0099] The nozzle 300 has a pin-hole air inlet to avoid the receptacle developing a negative pressure. This inlet is connected to the tube 220 which is designed to avoid product leakage during transport or use, irrespective of the orientation of the pot 200.

[0100] As described earlier and referring to Figure 5, the mounting arrangement 160 includes a support member 166 in the form of a semi-tubular channel. An external underside of the channel 166 has a partially threaded portion 170. The retaining member is in the form of a semi-tubular collar 175 is configured to abut against the semi-tubular channel 165 to define an enclosed cylindrical section 180. The enclosed cylindrical section 180 has an internal diameter configured to clamp an outer tubular portion of the nozzle 300. Once the enclosed cylindrical section 180 is seated around the nozzle 300, a locking member 340 in the form of a nut can be applied to secure the nozzle 300 within the enclosed cylindrical section 180.

[0101] As shown in Figure 2, the radially external surface of the nozzle 300 which is closest to the nozzle outlet 320 is tapered, so that tightening the locking nut 340 urgesthe nozzle 300 and receptacle 200 to move axially toward the motor 150, until a hermetic seal is achieved between the nozzle 300 inlet 310 and the air flow chamber 155.

[0102] The locking nut 340 is depicted as a round tapering and truncated conical member, and the internal surface is also partially tapering.

[0103] In an alternative arrangement, the external surface may alternatively be provided with a pair of parallel machined faces for engagement with a spanner, or hexagonal faces. Alternatively, it may have a knurled surface texture for improved hand grip.

[0104] The locking nut 340 and the semi-tubular channel 165 and semi-tubular collar 175 allow the paint assembly 210 to be quickly secured to the spray gun 100 or removed from the spray gun 100.

[0105] The operation of the apparatus 100 will now be described. When a user wishes to spray paint or apply another surface finish to a component, the desired paint or finish is selected, and it is supplied in a pot 200 with an integral, pre-attached nozzle 300.

[0106] The nozzle 300 is fitted to the apparatus 100 by securing the semi-tubular channel 165 to the semi-tubular collar 175 and securing by fastening the locking nut 340.

[0107] When the trigger 120 is pulled, the motor 150 spins the output shaft which is coupled to a fan impellor 170. The fan impellor 170 and motor 150 together define an air pump and the fan impellor 170 draws air into the air inlet 160. When the motor 150 begins spinning, actuation of the trigger also opens the valve 330, permitting the fluid to exit from the pot 200. The tube 220 extending upwardly inside the pot 200 allows air to enter the pot 200 to offset the volume occupied by the dispensed paint. This permits the paint to flow freely when the valve 330 is open.

[0108] The air passes through the airflow chamber 155 and into the nozzle 300. The venturi 360 causes the air to accelerate. The increased air velocity in the venturi 360 creates an area of low pressure and draws the paint out of the pot 200.

[0109] The valve 330 may be delayed in opening such that it remains closed until the motor 150 and impellor fan blade 170 speed ramps up to a predetermined RPM. This has the effect of regulating the starting spray pressure, so it starts with a spray not a dribble, resulting in improved spray consistency.

[0110] A second embodiment of the apparatus 100 is depicted in figure 9 to 11. Only the points of difference will be described in detail.

[0111] The fluid transfer passage arrangement 375, includes a separate fluid transfer passage 380, which is in fluid communication with the paint feed passage 337, the fluid transfer passage 380 and the airflow passage 376, at least in part tapering towards the distal end 304 at which the passages are in fluid communication in a mixing region 382 defining the low-pressure zone 378.

[0112] As depicted in Figures 9 and 10, the fluid flow passage within the nozzle 300 is conical and tapers from a maximum diameter at the proximal nozzle inlet, in the form of the interface 310 with the airflow chamber 155 toward a minimum diameter at the distal nozzle outlet 320. The nozzle outlet 320 may be sized to optimise the specific spray requirements of the particular paint can 200 to which it is attached. For example, a waterbased paint pot 200 may be supplied with a smaller nozzle outlet 320, whilst a more viscous enamel-based paint may be supplied with a larger diameter nozzle outlet 320.

[0113] Referring to figure 10, the nozzle 300 the fluid transfer passage is a central passage 380, which tapers conically toward the nozzle outlet 320. The central passage 380 is in fluid communication with the valve 330. The nozzle 300 also includes a radially outer air flow passage 385 which is disposed annually around the central passage 380. When the air flow from the motor 150 passes through the radially outer passage 385, at the nozzle outlet 320 the air exiting from the radially outer passage 385 creates a suction force to draw the paint out of the pot 200 through the central passage 380. When the motor 100 is operated at a higher rotational speed, the suction force increases.

[0114] With reference to Figure 10, the conical tapering of both of the central passage 380 and the radially outer passage 385 toward the nozzle 300 creates increased air speed and hence higher suction forces to draw the paint from the pot 200.

[0115] The spray gun 100 may have a gauge to indicate the air pressure within the pot 200.

[0116] Advantageously, the paint can or pot 200 and nozzle 300 are disposable. This obviates the need to clean the nozzle 300 and pot 200 with hazardous solvents, which are required for conventional spray guns, and this also removes the risk of paint contamination from one batch to the next.

[0117] Advantageously, the spray gun 100 obviates the need for the operator to manage an air or power cable which can result in air / power line snags and reduces work productivity and quality.

[0118] Throughout the drawings, like numerals are used to identify similar features, except where expressly otherwise indicated.

[0119] The reference numerals in the claims do not in any way limit the scope of the respective claims.

[0120] In the forgoing description of preferred embodiments, specific terminology has been used for the sake of clarity. However, the invention is not intended to be limited to the specific terms used, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as “front” and “rear”, “inner” and “outer”, “above”, “below”, “upper” and “lower” and the like are used for convenience to provide reference points and are not to be construed as limiting terms.

[0121] Where ever it is used, the word “comprising” is to be understood in its “open” sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the sense of “consisting only of”. A corresponding meaning is to be attributed to the corresponding words “comprise”, “comprised” and “comprises” where they appear.Table of PartsFluid Dispensing Apparatus 100Main Dispenser Body 105Air Discharge Port 107End Wall 109Internal Wall 111Airflow Chamber 155Airflow Generator 145Actuator 118Trigger Member 120Projection 121Motor 150Impeller 158Hand Grip Portion 110Batteries 130Control Unit 185Air Inlet 170Fluid Delivery Unit 205Fluid Holding Receptacle 200Fluid Feed Passage 337Nozzle 300Proximal End 302Distal End 304Nozzle Outlet 320Fluid T ransfer Passage Arrangement 375Air Flow Passage 376Junction Region 377Elongated Body 311Outer Side Wall 312Longitudinal Axis X-XFluid Transfer Passage 380Venturi 360Interface 310Pin Hole Air Inlet 220Valve 330Valve Head 331Valve Seat 332Valve Stem 335Spring 333Mixing Region 382Mounting Arrangement 160Support Member 166Outer End 167Retaining Member 175Locking Member 340Reduced Pressure Zone 334Aperture 168

Claims

Claims:

1. A fluid delivery unit for use in fluid dispensing apparatus (100), the apparatus comprising: a main dispenser body (105), having an air flow chamber (155) therein; an air discharge port (107) in an end wall (109) of the main dispenser body (105) and through which an airflow can be discharged from the airflow chamber (155); an airflow generator (145) for generating an airflow stream from the airflow chamber (155) through the discharge port (107) in an airflow stream direction; the fluid delivery unit (205) being adapted to be releasably mountable to the main dispenser body (105) in an installed position, and including: a fluid holding receptacle (200); a fluid feed passage (337) through which fluid can be discharged from the fluid holding receptacle (200); a nozzle (300) fixedly secured to the fluid holding receptacle (200), so as to provide for a unitary structure; the nozzle (300), including a proximal end (302), adjacent the discharge port (107) when in the installed position, a distal end (304), a nozzle outlet (320) and a fluid transfer passage arrangement (375), which includes an airflow passage (376) in fluid communication with the discharge port (107), the fluid feed passage (337) being in fluid communication with the fluid transfer passage arrangement (375).

2. The fluid delivery unit according to claim 1 wherein the fluid feed passage (337) is in fluid communication with the fluid transfer passage arrangement (375) in a fluid junction region (377) adjacent the proximal end (302) of the nozzle (300).

3. The fluid delivery unit according to claim 2 wherein the fluid transfer passage arrangement (375) is unobstructed from the junction region (377) to the nozzle outlet (320).

4. The fluid delivery unit, according to claim 3 wherein the fluid transfer passage arrangement (375) is configured, so as to draw fluid from the fluid holding receptacle (200) through the fluid feed passage (337) into the fluid transfer passage arrangement (375) in response to the travel of the airflow stream through the nozzle airflow passage (376).

5. The fluid delivery unit, according to any one of claims 1 to 4 wherein the nozzle airflow passage (376), includes a reduced pressure zone (378) in which a low pressure is produced relative to upstream of the reduced pressure zone (378) as a result of the airflow stream as it travels along the airflow passage (376), the fluid feed passage (337) being in fluid communication with the reduced pressure zone (378).

6. The fluid delivery unit, according to claim 5 wherein the airflow passage (376) has a cross-sectional dimension in the reduced pressure zone (378), which is less than the cross-sectional dimension of the airflow passage (376) upstream thereof.

7. The fluid delivery unit according to any one of claims 1 to 6 wherein the fluid transfer arrangement includes a fluid transfer passage (380) which is in fluid communication with the fluid feed passage (337).

8. The fluid delivery unit according to claim 7 wherein the airflow passage (376) and the fluid transfer passage (380) are provided by a common passageway configured to transfer the airflow stream and flow from the fluid receptacle via the fluid feed passage towards the nozzle outlet.

9. The fluid delivery unit according claim 8 wherein the reduced pressure zone (376) is provided by a venturi (360) within the airflow passage (376).

10. The fluid delivery unit according to claim 7 wherein the fluid transfer passage (380) and airflow passage (376) are repeated passageways along their length, the passageways at least in part tapering towards the distal end at which the passages are in fluid communication in a mixing region (382) which provides forthe low pressure zone (375).

11. The fluid delivery unit according to any one of claims 1 to 10 wherein the nozzle (300) comprises an elongated body (311) having an outer sidewall (312) with a longitudinal axis (X-X) extending between the ends (302, 304).

12. The fluid delivery unit according to claim 11 wherein the fluid feed passage (337) extends through the sidewall (312) of the nozzle body (311), so as to be in fluid communication with the fluid transverse arrangement (375).

13. The fluid delivery unit, according to any one of claims 1 to 9 including a valve (330) disposed within the fluid feed passage (337) and operable to open and close the fluid feed passage (337).

14. The fluid delivery unit, according to claim 10, wherein the valve (330) comprises a valve head (334) disposed within the fluid, feed passage (337) and a valve stem (335) which extends from the fluid feed passage (337).

15. A fluid dispensing apparatus (100), comprising: a main dispenser body (105), having an air flow chamber (155) therein; an air discharge port (107) in an end wall (109) of the main dispenser body (105) and through which an airflow can be discharged from the airflow chamber (155); an airflow generator (145) for generating an airflow stream from the airflow chamber (155) through the discharge port (107) in an airflow stream direction; the apparatus further comprising: a fluid delivery unit (205) according to any one of claims 1 to 14, the unit being releasably mountable to the main dispenser body (105) in an installed position.

16. The fluid dispensing apparatus according to claim 15 wherein the nozzle (300), when in the installed position is disposed wholly externally of the airflow chamber (155).

17. The fluid dispensing apparatus according to claim 15 or claim 16 wherein the airflow chamber (155) has an internal wall (111) which tapers towards the discharge port (107).

18. The fluid dispensing apparatus, according to claim 17 when appended to claim 7 or claim 8, wherein the longitudinal axis (X-X) is substantially aligned with the airflow stream from the discharge port (107) and the airflow generator (145).

19. The fluid dispensing apparatus according to any one of claims 15 to 18 wherein the main dispenser body (105) includes a mounting arrangement (160) for releasably mounting the fluid delivery unit (205) to the main dispenser body (105).

20. The fluid dispensing apparatus according to claim 19 wherein the mounting arrangement (160) includes a trough shaped support member (165) which extends from the end wall (109) of the main dispenser body (105) adjacent the discharge port (107) and terminates at an outer end (167), the support member (165) being shaped so as to receive a complementary shaped portion of the nozzle body (311) therein, the mounting arrangement further including a recessed retaining member (175) configured to overlie the nozzle body (311), when in the installed position and a locking member (340) configured to releasably hold the support member (160) and retaining member (175) together.

21. The fluid dispensing passage, according to any one of the claims 15 to 20, including an actuator (118) for activating the airflow generator (145).

22. The fluid dispensing apparatus, according to claim 21 wherein the actuator (118) further controls the opening and closing of the fluid feed passage (337).

23. The fluid dispensing apparatus, according to claim 21 or claim 22, wherein the actuator (118) is operable so as to control the speed of the airflow generator (145).

24. The fluid dispensing apparatus, according to claim 23, wherein the actuator (118) comprises a trigger member (120) movable between an initial position and an activating position.

25. The fluid dispensing apparatus, according to any one of claims 15 to 24 including a valve (330) disposed within the fluid feed passage (337) and is operable to open and close the fluid feed passage (337).

26. The fluid dispensing passage, according to claim 25, wherein the valve (330) comprises a valve head (334) disposed within the fluid, feed passage (337) and a valve stem (335) which extends from the fluid feed passage (337).

27. The fluid dispensing device according to claim 25 wherein the trigger member (120) is adapted to engage the valve stem (335).

28. The fluid dispensing apparatus according to claim 27 when appended to any one of claim 13 wherein the valve stem (335) extends through the nozzle (300) and through an aperture in trough shaped support member (165).

29. The fluid dispensing apparatus according to claim 28 wherein the valve stem (335) has an outer end which is in engagement with the actuator.

30. The fluid dispensing apparatus of claim 29, wherein the outer side wall of the nozzle body has a tapering cross-section such that an external cross-section nozzle body decreases toward nozzle outlet.

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