BACKGROUND OF THE INVENTION

The present invention relates to a liquid paint control device adapted to be mounted in a paint cartridge seat in an air passage of a barrel of a spray gun and to extend to a nozzle arranged at a front end of the barrel. Further, the present invention relates to a spray gun including such a liquid paint control device.

TECHNICAL BACKGROUND

A spray gun generally includes a liquid paint control device, an atomization device, and an air intake control device. The air intake control device is connected to an air tube of an external air compressor for painting. An actuation valve is provided in an air intake pas- sage in a barrel of the spray gun to control intake of compressed air for painting operations along with control of the amount of liquid paint and atomization. However, after use of the spray gun or for replacement of liquid paint, the passage of the liquid paint must be cleaned and the residual liquid paint must be removed, very often by using a solvent, resulting in additional costs for manpower and for the solvent. BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to provide a technical solution for simplifying the cleaning of the spray gun by removing a residual liquid paint under reduced effort and costs.

In order to achieve the above in further objects, according to the present invention, there is provided a liquid paint control device adapted to be mounted in a paint cartridge seat in an air passage of a barrel of a spray gun and to extend to a nozzle arranged at a front end of the barrel, the liquid paint control device comprising: a hollow paint cartridge having a body, said body comprising a front opening and a rear wall, wherein said rear wall is provided with a hole and a paint inlet is defined in said body, a hollow cap portion provided to close the front opening of the paint cartridge, said cap portion including a paint outlet and an air outlet means, and a needle being movable in its lengthwise direction and extending into the paint cartridge through its hole to control opening or closing of the paint outlet of the cap portion by movement.

So, the present invention provides a liquid paint control device which, after use of the spray gun or for replacement of liquid paint, can be easily removed from the spray gun and replaced by a new liquid paint control device which can be rapidly and reliably mounted into the spray gun. A further advantage of the construction according to the present invention is that the liquid paint control device defines a liquid paint path within the hollow paint cartridge from the paint inlet to the paint outlet in the cap portion which closes the front opening of the paint cartridge, wherein the liquid paint path is essentially separated from other elements of the spray gun and in particular from the air passage in the barrel and defines an essentially encapsulated and fluid-tight liquid paint path. So, there is no risk that the air passage and other elements of the spray gun beyond the liquid paint control device are contaminated by liquid paint. After all, the liquid paint control device according to the present invention can be easily used as a disposable liquid paint control device without the need of the use of a solvent or other cleaning agents, resulting in a considerable reduction of costs.

Preferred embodiments and modifications of the present invention are defined in the dependent claims. Preferably, the hole is provided as an axial hole.

According to a further preferred embodiment, the needle extends through the hole in an essentially sealed manner. According to a further preferred embodiment, the paint inlet is adapted to receive a tube of a liquid paint container, preferably in an essentially sealed manner. These measures are advantageous to achieve an effective encapsulation and separation of the liquid paint path from the air passage and other elements of the spray gun.

Preferably, the paint inlet is defined in an upper rear portion of the body of said paint cartridge.

Preferably, the air outlet means comprises a plurality of air outlets.

Preferably, the cap portion further includes a positioning flange extending from an outer periphery thereof. According to a modification of this embodiment, the positioning flange comprises a positioning portion adapted to engage with a positioning portion of a gunpoint formed in a front end of the air passage in the barrel of the spray gun so as to restrain an angular positional relation between the positioning flange of the cap portion and the gunpoint of the spray gun by means of male/female coupling between the positioning portion of the positioning flange of the cap portion and the positioning portion of the gunpoint of the spray gun.

According to a further preferred embodiment, the paint cartridge comprises a guide portion, and the needle includes a needle body having a rear end provided with a needle seat which is guided by said guide portion. The guide portion can protrude from the rear wall of the paint cartridge. According to a further preferred modification, the guide portion can be provided for restricting an angular position of said needle seat. Moreover, the needle seat can include a transfer through-hole adapted to accommodate an actuation pin extending through a guide hole formed in the barrel and the paint cartridge seat of the spray gun and adapted to be moved by a trigger pivotably mounted to the barrel to control forward or rearward movement of the needle. According to a further preferred embodiment, the paint cartridge and the hollow cap portion form an integral unit.

However, in an alternative embodiment, the paint cartridge and the cap portion can form individual elements, too. According to a preferred modification of this embodiment, each of the paint cartridge and the cap portion may comprise a positioning portion so as to restrict an angular positional relation between the paint cartridge and the cap portion by means of male/female coupling between the positioning portions of the paint cartridge and the cap portion.

According to a second aspect of the present invention, the above object is achieved by a spray gun comprising a barrel, an air passage provided in the barrel, a paint cartridge seat located in the air passage and a nozzle arranged at a front end of the barrel, wherein the liquid paint control device is mounted in said paint cartridge seat and extends to said nozzle.

According to a third aspect of the present invention, there is provided a spray gun comprising a barrel, a handle connected to a rear end of the barrel and located below the barrel, said barrel having an interior in communication with an interior of the handle to form an air passage in the barrel and the handle and further to form a gunpoint in a front end of the barrel, and said handle including an air intake chamber and an air inlet, said air intake chamber being in communication with said air passage, a nozzle mounted to the gunpoint, a liquid paint control device mounted in the barrel and operatively coupled to the nozzle, a trigger pivotably mounted to the barrel, and an impeller provided in the air intake chamber and a, preferably electrical, motor operable to rotate the impeller for driving air into the air intake chamber via the air inlet and for driving the air to flow through the air passage and the nozzle, providing a siphon effect causing a liquid paint in the barrel to spray outward via the nozzle.

Namely, it has been found that with the prior art spray guns the air compressor for painting is expensive and carriage of the air compressor is inconvenient. In order to overcome these drawbacks of the prior art, the present invention according to the third aspect provides an electric spray gun without the need of using an air compressor and an air tube, resulting in a further reduction of costs, saving space, and allowing easy carriage and on- site operation.

Preferred embodiments and modifications are defined in the dependent claims.

Preferably, the air intake chamber is defined in a lower section of the handle and includes a portion having increasing diameters away from an upper section of the handle. The motor and the impeller can be supported in the air intake chamber, and the motor can be connected to a power caught and a power switch.

Preferably, the air inlet is located in a bottom of the air intake chamber, and an air intake element is mounted in the air inlet.

Preferably, an activation switch is arranged at the handle and electrically connected to the motor. The activation switch can be located in a travel path of the trigger and activatible by the trigger to activate the motor for rotating the impeller.

Preferably, a plurality of air guiding plates is provided in the air passage at an interconnection between the barrel and the handle for guiding the air towards the nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a side view of a spray gun using a disposable liquid paint control vice according to a preferred embodiment of the present invention.

Fig. 2 shows a cross-sectional view of the spray gun of Fig. 1 in a non-operational mode with the needle closing a paint outlet of a hollow cap and the interior of a hollow paint cartridge filled by liquid paint.

Fig. 3 shows a perspective view of the spray gun of Fig. 1 , with a nozzle and a liquid paint container removed from the electric spray gun. Fig. 4 shows a front view of the spray gun of Fig. 1 , with the nozzle, the disposable liquid paint control device, and the liquid paint container removed from the spray gun.

Fig. 5 shows a cross-sectional view of the disposable liquid paint control device and of a portion of the spray gun of Fig. 1 , with the spray gun being in its non- operational mode and with the needle closing a paint outlet of a hollow cap and the interior of a hollow paint cartridge filled by liquid paint.

Fig. 6 shows an exploded cross-sectional view of the disposable liquid paint control device and of a portion of the spray gun of Fig. 5.

Fig. 7 shows a perspective view of the disposable liquid paint control device of Fig. 5 in a completely assembled state.

Fig. 8 shows an exploded perspective view of the disposable liquid paint control device of Fig. 5.

Fig. 9 shows an exploded cross-sectional view of the disposable liquid paint control device of Fig. 5.

Fig. 10 shows a view similar to Fig. 2, illustrating operation of the spray gun.

Fig. 1 1 shows a view similar to Fig. 5, but with the spray gun in its operational mode and with the needle in its opening position and, hence, the paint outlet being opened.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

According to a preferred embodiment shown in the enclosed figures, a disposable liquid paint control device 2 is mounted in a spray gun 1 for spraying a liquid paint 51 , as illustrated in Figs. 10 and 1 1 , such as an oil paint or a dye. The spray gun 1 according to the shown preferred embodiment includes a barrel 1 1 and a handle 12 connected to a rear end of the barrel 1 1 and located below the barrel 1 1 according to the orientation of the spray gun 1 as shown in the Figs. 1 to 4 and 10. The barrel 1 1 has an interior in communication with an interior of the handle 12 to form an air passage 14 within the barrel 1 1 and the handle 12 and to further form a gunpoint 13 at a front end of the barrel 1 1 . An air intake chamber 16 is provided within an enlarged lower section of the handle 12 and comprises an air inlet 161 in a bottom thereof defining a lower end of the enlarged lower section of the handle 12. The air intake chamber 16 includes a portion having increasing diameters away from an upper section of the handle 12, and is in communication with the air passage 14 within the handle 12. An air intake plate 162 including a plurality of through-holes or openings is arranged in the air inlet 161 . A plurality of air guiding plates 141 are mounted in the air passage 14 at an interconnection between the barrel 1 1 and the handle 12 for guiding the air towards a nozzle 3 which is provided at a free end of the barrel 1 1.

A coupler provided as a bushing 18 is formed at the outer surface of the barrel 1 1 and includes a coupling hole 1 . The coupling hole 17 is in communication with a hollow paint cartridge seat 15 which is provided within the barrel 1 1 and adapted to partly accommodate the liquid paint control device 2. A guide hole 152 extends from one side to the other side of the barrel 1 1 and also extends through the paint cartridge seat 15 and two lateral connecting portions 151 on both sides of the paint cartridge seat 15.

The liquid paint control device 2 is mounted in the barrel 1 1 and received in the paint cartridge seat 15 within the air passage 14 and positioned between a nozzle 3 and the paint cartridge seat 15. The liquid paint control device 2 includes a hollow plastic paint cartridge 21 having a body 21 1 . Said body 21 1 includes a front opening 212, a rear end wall 213, and an axial hole 214. In an upper rear portion of the body 21 1 is defined a paint inlet 215 which is in line with the coupling hole 17 of the bushing 18 at the outer side of the barrel when the liquid paint control device 2 is inserted in the paint cartridge seat 15, so that the paint cartridge 21 can be filled by liquid paint 51 as shown in the Figs. 2 and 5.

A hollow plastic cap 22 is mounted to seal the front opening 212 of the paint cartridge 21 . The cap 22 includes a paint outlet 221 and a plurality of guiding ribs 226 on an inner periphery thereof. The cap 22 further includes a positioning flange 222, which extends from an outer periphery thereof and is positioned between the nozzle 3 and the gunpoint 13 of the barrel 1 1 , as well as a plurality of air outlets 224. The liquid paint control device 2 further includes a plastic needle 23 comprising a needle body 231 . A needle seat 232 is fixed to a rear end of the needle body 231 and includes a transverse through-hole 233. Further provided is a guide portion 217 in which the needle seat 232 is movably accommodated and guided, wherein the guide portion 217 protrudes from the rear end wall 213 of the paint cartridge 21. The needle body 231 extends through the axial hole 214 in an essentially sealed manner and further through the paint cartridge 21 towards the paint outlet 221 of the cap 22 so as to control opening or closing of the paint outlet 221 of the cap 22 through movement of the needle seat 232.

The nozzle 3 includes a central hole 31 and a plurality of apertures 32 in a front outer portion thereof. The apertures 32 are in communication with the air passage 14. The nozzle 3 further includes a coupling section 33 having an internal thread which engages with an outer thread on an outer periphery of the gunpoint 13 of the barrel 1 1 .

A trigger 4 is pivotably arranged at the barrel 1 1 so as to be movable relative to the barrel 1 1. The trigger 4 comprises a forked upper end portion located on both sides of the barrel 1 1. A pin 41 extends through the forked upper end portion of the trigger 4 into the barrel 1 1 so as to allow a pivotable movement of the trigger 4 relative to the barrel 1 1 . Moreover, an actuation pin 42 extends through the guide hole 152 of the barrel 1 1 and further through the through-hole 233 of the needle seat 232 wherein the guide portion 217 movably guiding the needle seat 232 defines a certain angular position of the needle seat 232 so that the actuating pin 42 can reliably extend through the through-hole 233. The trigger 4 is biased by a spring 43 attached to a lower end portion of the barrel 1 1. When not in use, the trigger 4 is biased forward by the spring 43 so as to be spaced from the handle 12.

Whereas according to the embodiment shown in the figures the needle seat 232 is arranged at the rear end of the needle body 231 and formed as a block having an essentially rectangular cross section and the guide portion 217 protruding from the rear end wall 213 of the paint cartridge 21 includes an opening having a corresponding rectangular cross section, according to an alternative embodiment not shown the needle seat is formed by a portion of the needle body 231 and further comprises a guide rail protruding from and extending along said portion of the needle body 231 , and the guide portion includes an opening adapted to movable accommodate said portion of the needle body 231 and comprises a cross section corresponding to that of the needle body 231 with a recess for accommodating said guide rail.

A liquid paint container 5 is provided as an exchangeable reservoir for storing a liquid paint therein, and is to be mounted upside down on the spray gun 1 . The liquid paint container 5 comprises a tube 52 protruding from its lid which closes the liquid paint container 5, wherein the tube 52 defines an outlet for taking liquid paint out of the liquid paint container 5. For mounting the liquid paint container 5 on the spray gun 1 , the tube 52 is inserted through the coupling hole 17 in the barrel 1 1 into the paint inlet 215 of the paint cartridge 21 of the liquid paint control device 2 so as to allow liquid paint 51 to flow from the liquid paint container 5 into the paint cartridge 21 and to fill the interior of the paint cartridge 21 of the liquid paint control device 2 as shown in Figs. 2 and 5. After use when the liquid paint container 5 has been emptied, it can be discarded.

The spray gun 1 further includes an electrical motor 6 which is arranged within the air intake chamber 16 in the enlarged lower section of the handle 12. The motor 6 comprises a shaft coupled to an impeller 61 which is arranged so as to be rotatable in the lower end of the enlarged lower section of the handle 12 adjacent to the air intake plate 16. The electrical motor 6 is connected to a power cable 62 for supplying the motor 6 with electrical power from an external electrical source, and to a power switch 63 for switching on and off the motor 6. An activation switch 64 is provided at the handle 12 adjacent to the trigger 4 and electrically connected to the motor 6. The activation switch 64 is located in a travel path of the trigger 4 and activatable by the trigger 4 when the trigger 4 engages with the activation switch 64. Due to such an activation of the activation switch 64 the motor 6 is switched on by the activation switch 64 so as to rotatably drive the impeller 61.

Figs. 2 and 5 show the spray gun 1 not in use, wherein the spring 43 biases the trigger 4 forward and away from the handle 12 and the activation switch 64 into a resting position shown, so that the activation switch 64 is in an off position cutting off power supply to the motor 6 and, thus, switching off the motor 6. When the trigger 4 is biased forward into its resting position by the spring 43, the actuation pin 42 pushes the needle seat 232 towards the paint cartridge 21 so that the needle 23 is moved forward to a position closing and sealing the paint outlet 221 of the cap 22 preventing the liquid paint 51 from escaping from the paint cartridge 21 through the paint outlet 221 . Figs. 10 and 1 1 show the spray gun 1 in operation wherein the trigger 4 is pulled by a user's finger (not shown) in a rearward direction towards the handle 12 so as to engage with the activation switch 64. Due to the pulling of the trigger 4, the actuation pin 42 draws the needle seat 232 away from the paint cartridge 21 so that the needle 23 is moved in a rearward direction and, hence, opens the paint outlet 221 of the cap 22. Due to the engagement with the trigger 4, the activation switch 64 is activated so as to supply electrical power to the motor 6. As a result, the motor 6 drives the impeller 61 to rotate so that air is drawn through the air inlet 161 into the handle 12 and caused to flow through the air passage 14, through the air outlet 224 of the cap 22 and through the apertures 32 of the nozzle 3 providing a siphon effect causing the liquid paint 51 to be discharged from the nozzle 3 in spray form.

After the use of the spray gun 1 or in case of a replacement of liquid paint 51 , the nozzle 3 and the liquid paint container 5 are removed. After the actuating pin 42 is disengaged or released from the through-hole 233 of the needle seat 232, the liquid paint control device 2 (including the paint cartridge 21 , the cap 22 and the needle 23) can be pulled out of the paint cartridge seat 15 of the barrel 1 1 via the gunpoint 13. Then, a new liquid paint control device 2 can be inserted into the paint cartridge seat 15, and the actuating pin 42, the nozzle 3 and the liquid paint container 5 can be rapidly mounted to the barrel 1 1 again for a new spraying operation. The used liquid paint control device 2 can be directly discarded or recycled, so that the liquid paint control device 2 according to the presently described preferred embodiment can be utilized as a disposable liquid paint control device.

The gunpoint 13 of the barrel 1 1 comprises a positioning portion 131 formed as a recess, and the positioning flange 222 of the cap 22 of the liquid paint control device 2 comprises a positioning portion 223 formed as a small protrusion to be engagable with the positioning portion 131. So, when the liquid paint control device 2 is mounted in the paint cartridge seat 15 of the barrel 1 1 , an angular positional relation between the gunpoint 13 and the positioning flange 222 is defined by means of a male/female coupling between both these positioning portions 131 , 223.

The paint cartridge 21 and the cap 22 may form an integral unit. However, alternatively the paint cartridge 21 and the cap 22 may form individual, separate elements as it is the case in the embodiment shown in the enclosed figures. Moreover, in this embodiment, the paint cartridge 21 comprises a positioning portion 216 formed as a recess, and the cap 22 comprises a positioning portion 225 formed as a protrusion adapted to engage with the positioning portion 216. When the cap 22 is mounted to the paint cartridge 21 for closing its front opening 212, an angular positional relation between the paint cartridge 21 and the cap 22 is defined by means of a male/female coupling between both these positioning portions 216, 225.