FR2473359A1 - Spray gun for hot paint - has electric element embedded in metal block to heat air and paint before they reach spraying head - Google Patents

Abstract

The spraying gun has an air inlet in the handle and the air flows through valve and into a cylindrical chamber mounted above the gun barrel. A second cylinder inside the cylinder encloses a block of metal with a number of narrow passageways separated by thin walls. Electric heating elements are embedded in the metal block and heat the air as it flows through the passageways. The air emerges through a central nozzle in the spraying head. The paint is drawn in through holes and flows through passageways around the block so that it is also heated. The heated paint emerges through nozzles in the head and is atomised by the central jet of air.

Description

 the main known devices are in the form of a pistol with more or less defined forms or even poorly studied when, with delicate handling, the demanding cleaning necessities as much inside as outside the numerous joints often subject to leaks dBes particularly to thinners sometimes ooroeifs.

 On the other hand, this type of apparatus, although using a valid technique with regard to "the simultaneous heating of the product and of the atomizing air", it is from this logically reliable process that the difficulties begin. feasibility, maintenance, aesthetics and mainly safety dfles to work in ailisu to see orplosive, when to their system of regulation of the active temples comprising a bimetal h cantact, in front necessarily In addition explosion-proof. It is for these reasons that this type of device is only known at the project stage in the public domain and is practically impracticable. the temperature differences dds to the times of repetitive switching on and off of the resistances created an irregular heating curve in a sawtooth fashion, therefore negative to the operating ban since the heating (simultaneous of the air and the product) subsists at the diluent dosing operation.

the devices currently in service are in the form of a special tank peddling a resistance conditioned by a lamella thermostat, or more precise, electronic thermostats, this principle insofar as it approaches the desired goal retains several drawbacks, the main ones of which are listed below:
temperature losses, due to the spraying air which is not heated, this acting as a beam cooler, the temperature of the product should be raised more than necessary at the risk of modifying the characteristics of the product used.

If a conventional spray gun is used without heating the product, it is preferable to heat the room and regulate the temperature. This process, which is very dependent on climatic conditions, implies the use for each case, of such or such diluent with the risk of a bad interpretation. On the other hand, the addition of the diluent in large proportions increases the harmful fumes. so the wire applicable to each pass remains thin and requires many passes.

 the new paints currently on the market called "polyurethane paints" diluted to 200 are even more harmful, dangerous, even explosive and impose a much greater air mixing in order to expel the harmful fog outside. the spraying air pressure being 5 bar, it goes against the desired goal which is the energy saving and the disinution of pollution.

 The gun which is the subject of the present invention pereet to overcome large numbers of drawbacks and, in addition, offers certain equipment and adaptations which tend to increase its efficiency and to decrease the specialization required today.

Eg heating of the air and by extension that of the product near the outlet nozzle guarantees the maintenance of the temperature up to the surface to be treated. fl in some cases removes the diluent, making harmful fumes almost insignificant.

1l allows de7slviri.ur at a lower overpressure in the cabin, it gives the possibility of reducing the interior atmosphere by the fact of a significant dimintion of the fog. the reduction in the air flow reduces the fouling of the purifier, therefore less maintenance and pollution. The air pressure required for the application with the heat gun is much lower than traditional means, so less dust is raised, less risk of deterioration of the parts already treated. the paint tension being faster and better, the so-called "dust-free" time is therefore shorter. the paint particles form the projection beam having the same fineness as a paint treated beforehand with thinner, suitable for such or such climatic condition, in order to obtain an identical result, the particle having undergone a dilution by leaving the beam d application is more volatile, a particle of paint leaving the fields of the heated beam cools, hardens significantly reducing its time of suspension in the air. On the other hand, the lower pressure required for the formation of the spray beam confirms this thesis.

The spray gun which is the subject of the invention comprises three means of supplying paint in the first case, the gravity tank is fixed horizontally by means of the retractable segment, comprising a locking system. The second supply means is the suction pot maintained by means of an adaptation also serving to connect the supply pipe to the pressure pot, various other characteristics of the invention will moreover emerge from the detailed description which follows
Embodiments of the subject of the invention are presented, by way of nonlimiting example, in the accompanying drawings.

Figure 1 is a plan of the m7nrt pistol of the gravity pot.

 Figure 2 shows the device fitted with the suction pot.

Figure 3 is a rear view of the device supplied by a tube connecting the pressure pot.

 Figure 4 is a side view of the gun and the retractable electronic thermostat in the butt.

 Figure 5 is a sectional view of the hot air generator part.

 Figure 6 is an enlarged life of the trigger joint operating on the needle and the air valve.

 FIG. 7 is a plunging view in horizontal section of the needle valve, air valve, and needle adjustment assembly.

 FIG. 8 is an enlarged plunging view of the needle operating mode, of the air valve relative to the trigger 2.

 Figure 9 is a side sectional view of the entire apparatus.

FIG. 10 is a bottom view of the butt, of the thermostat adjustment wheel, of the air and sector supply,
Figure 11 is a sectional view of the paint supply device.

FIG. 12 is a demonstration of the direction of channeling of the product around the body of the generator.

Figure 13 shows different views of the stick in insulating material.

 Figures 14 to 22 "5" show different views of the main element of the hot air generator.

 Figure 23 is a side sectional view of the closing system of the retractable segment.

 Figure 24 shows the rear view of the closure system.

Figure 25 is an exploded view of the closure system.

 Figure 26 is the overview of the closure system and its segment.

 Figure 27 shows the reign assembly of the product flow.

 Figure 28 is the exploded view of the product flow control system.

 the first basis is the temperature of the air, with the aim of providing precise information relating to the rapidity of the passage of the air in the duct 48, in the event of the air passage being stopped the detector 35 placed at a short distance part of the wall of the chimney 48 immediately receives the overheating information and the tension in order to reduce the intensity of the resistances, the detector fixed on the product duct 34 in order to associate to a certain extent the temperature of the product to that of the air by means of the detector 35, the main purpose of the generator being the heating of the air and by extension that of the product.

 the connozion of the pressurized air inlet tube 15 and the mains supply cable 16 being ensured, the positioning of the knob 18 acting on the potentiometer of the electronic thermostat 21 energizing the resistors 54 in FIG. 15. 22 of the generator at the "peak" degree corresponds to the index of the dial 18, the detector 35 located in the chimney 48 transmits the information to the thermostat 21 limiting at will the intensity to the resistors 54. A first press on the trigger 2 comprising a clevis 30 transmitting the movement to the axis 23 of the valve 43, the space of which contained between the clevis 30 and the shoulder are of the needle 24. The clevis 30 coming to bear on the shoulder 33 of the needle 24, parallel to this movement, the cap 30 in FIG. 8 driving back the area 23 secured to the air opening valve 43, thereby producing the air passase in pipes 83 supplying the diffuser.

 Bbr the same effect, the tube 46 containing pressurized air terminating in the compartment 63 in FIG. 16 comprising fins, the air then passes through the corridor 49 terminating in a second compartment 52 also comprising a group of fins. A partition 50 separating the lower compartments from the upper compartments in FIG. 17. "A sealed inspection hatch 59 giving access to the resistors 54, the wires of which pass through the orifice 60. the inspection hatch 59 attached to the wall 10 of the dome" of the generator "comprising at its base a gasket 25. The dome 10 is fixed by the screw 26. the hatch 59 having as a second dimension the separation between the heating compartments. At the upper end of the compartment 52 is located in the partition 50 the orifice 56 transmitting the passage of air in the compartment 64 giving access to the corridor 53 ending in the fourth compartment 55 also comprising reheating fins.

 At the upper end of this last compartment 55 an orifice 58 is arranged in the second partition 51 FIGS. 19 and 22 transmitting to the fifth compartment 57 accessing the chimney 48, in which is the detector 35 giving access to the valve chamber 43 "formed by the sealed bearing 28", the valve in the open position frees the passage leading to the diffuser 4 and to the refinement of the jet ao comprising interchangeable and adjustable nozzles 32. The air regulation of the refinement is obtained by a valve 3 placed on the conduit 83 in FIG. 7.

 A second pressure exerted on the trigger 2, the cap 30 being in abutment on the shoulder 33 of the needle 24 the latter against the action of the spring 79 exerts a recoil movement releasing the outlet orifice of the nozzle 45.

 the product contained in the reservoir 11 enters the tube 37 integrally with the dome of insulating material 36 covering the generator, the closing and sealing of which are ensured by the segment 8 comprising a clamping system in figure 23. The product enters the dome 36 comprising a circular milling 40 the end of which opens at its upper part into a circular space 39.

The product having already undergone a first reheating, enters the tube 34 transmitting the product to the projector whose jet is adjustable by the graduated dial 7, the sealing of the needle is ensured by the sealed bearing 29 whose seal 41 is adjustable by screwing at will from the bearing 29. the main part of the apparatus is the base of the generator 2 receiving the block 22 containing the resistors 54, an intermediate seal 38 serving as a seal and thermal insulator. Ia second part 5 of the base 27 is intended to receive and fix the diffuser, consisting of a screwed support 42 receiving the refinement of the jet 20 having a rotation of a quarter turn "according to the operations" vertical or horizontal, this device in insulating material comprises two nozzles 32 at variable angle according to the desired setting, the orientable nozzles are held by the supports 31. Ia calibrated nozzle 45 forming with its screwed support 4 the entire diffuser. The flow adjustment system comprises a support 75 "screwed onto the base 27" in which slides in rotation by one turn an axis 77 on which is screwed a stud 76 sliding in an elicoidal detail a spring 79 compressed by a stop 80 and maintained by a circlip 81.

 The closing, fixing and sealing system consists of a segment 8 comprising at its ends suitable hooks 74, receiving two jaws, one of which is fixed but adjustable by means of the screw 69 (comprising a pad SaOrtisseur 70 made of flexible material ), the screw 69 can be used for adjusting the tightening, disassembly and reassembly of the segment 8. The second jaw 67 is movable and comprises a caster 73 mie by a lever 65 comprising a cam 74 held by a pin 72 fixed in the housing 68 Sh lowering the lever 65 by a quarter of a turn, the cam 74 rotating on the wheel 73 actuates the jaw 67 having the effect of tightening the segment 8 FIG. 26 shows the system in the closed or tight position.

 Figure 13, butt in insulating material side view, rear view, and top view which has at its upper part, the four holes 84 for fixing the generator an inlet of pressurized air 46 the passage of the control and tension wires 60 , the screws 85 serving to fix the generator

Claims (11)

RESELL ICAT IONS 1 - Gun allowing the spraying of generally viscous cold surface treatment products of the comports type; lt a generator for simultaneous heating of the air and of the product placed above the projection device, controlled by a trigger and maintained by a stock 1, characterized in that the generator is of cylindrical shape on which is interchangeably interlocking a dome-shaped element 36 connecting to a product supply means, a furnished space defined between the external faces lateral and upper side of the heater and the lateral and upper internal faces of the dome 36 allowing the passage and the heating of the product towards a tube 34 to bring the product to the spraying device. 2 - Pistol according to claim I characterized in that the dome is integral with a reservoir 6 of insulating material of the gravity type product, a connecting conduit being provided between the reservoir and the internal lateral face of the dome.  3 - Pistol according to claim I characterized in that the means for feeding the dome (36) is a boss located on the outer side wall of said dome (Figure 11) having a vertical bore opening at its lower and upper parts , an oblique conduit 40 connecting the said bore to the interior base of the blow let36) which can simultaneously receive the supply supports from a lower reservoir, from a reservoir situated above the said vertical bore, or from a tube 37 connected by a flexible tube 14 to various devices. 4 - Pistol according to one of the preceding claims characterized in that the movable fixing of said feed hub according to the desired positioning and the sealing of the dome 36 on the generator is ensured by a retractable segment 8 actuated by a mechanism compression (Figure 23) or by extending the central screw 26. 5 - Pistol according to claim; characterized in that the butt 1  in insulating material comprises a cavity fitted containing the air supply tube 46 and the electronic circuit 21 for controlling the voltage of one or more resistors contained in the generator, and an adjustment potentiometer 18 disposed at the base of said butt 1. 6 - Gun according to one of the preceding claims, characterized in that the tube 34 for passing the heated products to the spray device is fixed and insulated inside a thermal synthesis chimney 48 inside which is arranged a detector 35 of the electronic thermostat fixed on said tube 34. 7 - Pistol according to one of the preceding claims characterized in that the detector 35 fixed in the thermal synthesis chimney 48 undergoes in at least one of its functions, the influence of the air conditioning, in whole or in part, by thermal radiation from the walls of said chimney 48 or by its support, the hot product supply tube 34. 8 - Gun according to one of the preceding claims, characterized in that the projection device comprises a diffuser 4 and a refining device 20 independent of each other, the latter comprising nozzles that are not changeable and adjustable by means tabs moving on synchronism marks.  9 - Pistol according to one of the preceding claims, characterized in that the trigger 2 comprises a horizontal valve 30 actuating an axis 23 e air supply valve 43 and an axis 24 of needle needle both arranged on a horizontal plane, and that said trigger is only held by the needle rod 24 and a spring 44.  10 - Pistol according to claim 1 characterized in that the product heating generator consists of a compartmentalized core 22 comprising fins 55 serving as a thermal transmitter to the air passing between said fins contained in the compartments formed by the partitions horizontal and a dome 10 resting on a base 27 of the projection device by a central fixing screw 26, a groove comprising a seal 25 ensured the tightness.  U - Gun according to one of the preceding claims, characterized in that the recoil at will of the needle 24 is conditioned by a device with rapid and precise adjustment, comprising a graduated wheel (7, FIG. 28) modulating the adjustment over one revolution, said graduated dial 7 secured to the axis 77 by means of the screw 76 sliding in the helical detail 78 allowing the needle rod 24 to be abutted in the bottom of the cavity of the axis 77, the stop sliding 80 against the action of a spring 79 coming to bear on the shoulder 33 of the needle 24.  12 - Pistol according to one of the preceding claims characterized in that in the sealed closure system of the dome the segment 8 is supported in a circular groove arranged in a support made of insulating material 12, a wedge on steel 88 making up the solution of continuity of said segment comprising at its ends hooks 74 of shapes designed to receive the two compression jaws 71 and 67, including the 71 comprising an adjusting screw 69 and an intermediate shim 70, the 67 composting a movement wheel 73 obe by a stop boss 74 arranged in the mass of the quarter-turn lever 65 fixed by an axis 72 to the support box 68.