US3495779A - Electrostatic spray gun - Google Patents

Description

Feb. 17, 1970 c), RENNER ETAL 3,495,779

ELECTROSTATIC SPRAY GUN 2 Sheets-Sheet 1 Filed April 29, 1968 nver ztors I l os gchleggl Feb. 17, 1970 2 Sheets-Sheet 2 Filed April 29, 1968 United States Patent i 3,495,779 ELECTROSTATIC SPRAY GUN Otto Renner, Neu Isenburg, and Alois Schlegel, Frankfurt am Main, Germany, assignors to Licentia Patent- Verwaltungs-G.m.b.H., Frankfurt am Main, Germany Filed Apr. 29, 1968, Ser. No. 724,764 Claims priority, application Germany, Apr. 28, 1967, L 56,376, L 56,377; Apr. 29, 1967, L 56,405 Int. Cl. B05b 5/02, 7/02 US. Cl. 239-15 10 Claims ABSTRACT OF THE DISCLOSURE A spray gun whose reservoir is closed off by a closure plate which carries a spray component as well as connectors that connect the spray component to a high-voltage line. The spray gun is connectible to a high-voltage source which is turned on by way of mechanical transmission which is actuated by an actuator located in the handle of the spray gun.

BACKGROUND OF THE INVENTION The present invention relates to an electrostatic spray gun having a reservoir for the material to be sprayed, a spray component and a handle, which parts are capable of being assembled into a piece of equipment which itself is connectible to an external high-voltage source.

More particularly, the present invention relates to an improvement of conventional spray guns and has as its particular object to provide a practical spray gun which meets existing safety requirements. Conventional spray guns are normally equipped with a stationary or a rotating spray electrode. In spray guns having a rotating electrode, the material which is to be sprayed is under pressure and is piped to the spray electrode from an external reservoir. In other types of conventional spray guns, the material to be sprayed is conducted to the spray electrode by means of compressed air.

In some types of conventional spray guns, a driving element is switched on so as to start tthe spraying operation. This driving element can. be a motor which rotates an atomizer disc or which opens a compressed air conduit for supplying coating material to the atomizer device. Other circuit elements are provided for connecting the atomizer to the high voltage which is needed to produce the electric field. Such spray guns often have to have both high-voltage as well as low-voltage potentials applied to them, and this will at times produce difiicult insulating problems.

There exist still other types of spray guns which are so constructed that the reservoir for the material to be sprayed is attachable to the body of the gun, either from the top or from the bottom. Spray guns of this type require a special closure device so as to prevent the material from reaching the electrode after tthe spray gun has been turned 01f.

BRIEF DESCRIPTION OF THE INVENTION It is, therefore, the primary object of the present invention to provide a spray gun which is of simpler construction and more reliable in operation than heretofore known spray guns, and, with this object in view, the present invention resides in a spray gun in which the reservoir for the material to be sprayed has, at one end, a closure 3,495,779 Patented Feb. 17, 1970 plate which carries both the spray component and a connecting element by means of which the high voltage 'is applied to the spray gun and wherein the high voltage is switched on by means of an actuator which is located in the handle of the spray gun, there being a mechanical transmission element between the actuator and the source of high-voltage potential.

According to another feature of the present invention, suspension means are provided near the front end of the reservoir so that when the spray gun is not used, it can be hung up in such a way that no material will flow out of the reservoir through the spray component.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a side elevational view of a spray gun according to the present invention, the: front part of the spray electrode being shown in section.

FIGURE 2 is a side view of a suspended spray gun.

FIGURE 3 shows the actuating mechanism of a spray gun according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and first to FIGURES l and 2, the same show a spray gun having a reservoir 1 which contains the material to be sprayed, this reservoir being connected to a handle 2. Below the reservoir 1 is a closed channel 3 which may, for example, be joined to the handle and have a U-shaped cross section, there being a high-voltage electrical line 4 extending through this channel almost as far as the front end of the reservoir 1. The front end of the reservoir is itself open but is closed off by a closure plate 5 which is positioned so as tightly to close the front end. The closure plate 5 carries a spray component 7, the same having a tubular supply extension 6 which extends into the interior of the reservoir 1. The spray component is connected via a conductor 8 to a plugtype connector 9 which is likewise arranged in the closure "plate 5. When the parts. are assembled. and in operative condition, the front end of line 4 and the connector 9 are electrically connected to each other.

The spray component 7 which is carried by the closure plate 5 is designed so that it can readily be plugged into the plate, as a result of which any one spray component is easily exchangeable for another. This, in turn, allows the same spray gun to be used in conjunction with spray components of diiferent sizes, so that the gun can be used to spray work pieces of varying sizes. For example, for work pieces having large surface areas, the spray component will be appropriately wide.

In order to allow the feed of material to the spray component to be regulated, the extension 6 is designed to be able to receive restrictors 10 of different sizes, these restrictors being insertable into orifices in the extension so that the cross section of the path through which material is supplied can be varied and the sensitivity of the spraying operation can be adjusted. Moreover, the restrictors 10 allow the spray component. to be adapted to various viscosities, depending on the material being sprayed.

For practical reasons, the spray components are made of insulating material. In order to stabilize the spraying operation, a free surface 12 is arranged between the head of the spray component 7 and the edge 11 from which the material leaves the spray component.

The spray gun further includes a hook-shaped suspension device 13 which is arranged on the reservoir at the front end and near the closure plate 5. This suspension 13 is provided with a passage 14 through which the interior of the reservoir is vented to atmosphere, so as to allow the pressure within the reservoir to be equalized. The suspension device is adapted to be hooked into a hook or other suitable carrier 15 which may be attached to a wall or ceiling.

After the spraying operation, the operator will hang up the spray gun by hooking the suspension device 13 into the carrier 15. Inasmuch as the suspension device 13 and the spray component 7 are both located near the front end of the spray gun, the latter will, when hung up, auto matically assume a position such as is shown in FIGURE 2 in which the material in the reservoir is prevented from flowing out of the reservoir by way of the spray component 7.

The venting passage 14 is needed in order to allow additional material to be fed to the reservoir during the spraying operation. If desired, the passage 14 can be so dimensioned as to allow the reservoir 1 to be refilled through this passage, so that it is unnecessary to remove the closure plate 5 and the spray component 7 in order to refill the reservoir.

In practice, the spray gun can be refilled by means of a conventional dispenser which discharges a dosed amount of material whenever an outlet valve is actuated, so that by placing the valve into the passage 14 and by pushing the spray gun upwardly against the valve (or by using the suspension device 13 to push upwardly on a valve and by allowing the forthcoming material to flow into the passage 14), the spray gun can be easily and quickly filled with the desired amount of material. In this way, the interruptions to the spraying operation can be kept to a minimum.

Referring now to FIGURE 3, the same shows the manner in which the electricity is supplied to the spray gun. Thus, FIGURE 3 shows a cable 115 which includes, within a common sheath, a high-voltage line 16 and a mechanical transmission 17, which may, for example, be in the form of a tube. One end of cable 11 is introduced into the spray gun through the handle 2, the other end of the cable being connected to a portable high-voltage source 18. Arranged in the handle 2 of the spray gun is an actuator 20, behind which there is located a balloon-like end portion of the tube 17, so that when the actuator 20 is pulled backsomewhat in the manner of a trigger-a pressure pulse is transmitted through the tube 17 so as to switch on the high-voltage source 18, as will be explained below. The tube 17 may also serve to hold the grounded conductor (not shown).

The high-voltage line 16 and the tube 17 are connected to the portable high-voltage source 188 by means of screw or p1ug- type connectors 21, 22, these connectors being preferably so designed as to prevent wrong connections, i.e., so as to prevent the line 16 from being connected to the connector intended for the tube 17 and vice versa. The electrical terminal 23 of the source 18 is arranged within the casing of this source and is contacted by the end of the line 16. The end 24 of tube 17 is connected to a pressure-responsive electric switch 25, so that the pressure pulse produced upon actuation of the actuator 20 causes this switch 25 to close the high-voltage circuit leading to the terminal 23. This, then, means that the highvoltage line 16 can be energized only if both it and the tube 17 are properly connected to the external source 18.

In practice, the tube-type connection can be replaced by any other suitable type of mechanical connection.

The connector 22 is grounded, by way of lead 26, with the common ground connection 27 of the highwoltage source, there being a plug or other connector 28 by means of which the source 18 can be connected to the usual domestic or industrial source of electrical energy of, for example, 110 v. or 220 v. In this way, the grounded conductor sheathed by the tube 17 will unquestionably be grounded, so that there is no danger that the spray gun will be used without the handle being properly grounded.

It will thus be seen that, in accordance with the present invention, there is provided a spray gun which is of simple construction, in that one and the same structural component, namely, the closure plate is used to close off the reservoir and electrically to connect the spray component to the high-voltage line. It is thus simple to exchange one spray component for another. Moreover, thanks to the suspension device arranged at the front end of the reservoir, the spray gun will always be upwardly inclined when it is not in use, so that no special closure means are needed to prevent the loss of material when the spray gun is hung up. Furthermore, thanks to the provision of the cable containing the electrical line as well as the mechanical means by which the electrical line is energized, a fail-safe arrangement is provided in that the spray gun can not be energized unless the handle is properly grounded.

It will be understood that the above description of the present invention is susceptible to various modifications, change sand adaptations.

We claim:

1. An electrostatic spray gun connectible to an external high-voltage source and comprising, in combination:

(a) a reservoir which is open at the front;

(b) a closure plate closing said front end of said reservoir;

(c) a spray component carried by said closure plate;

(d) a handle connected to said reservoir;

(e) an electrical line extending through said handle, one end of said line terminating near said front end of said reservoir and the other end of said line being connectible to an external high-voltage source; and

(f) means carried by said closure plate for establishing electrical connection between said one end of said electrical line and said spray component; and

(g) actuator means having an actuator arranged in said handle and mechanical transmission means having one end connected to said actuator, the other end of said transmission means being connectible to the high-voltage source for controlling the same, whereupon, upon the actuation of said actuator, a high voltage may be applied from the high-voltage source to said spray component.

2. A spray gun as defined in claim 1 wherein said means (f) comprise a connector plug for engaging said one end of said electrical line.

3. A spray gun as defined in claim 1 wherein said bandle includes a channel-shaped portion extending along said reservoir, said electrical line extending through said channel-shaped portion.

4. A spray gun as defined in claim 1 wherein said spray component is removably mounted on said closure plate, thereby to allow any one spray component to b exchanged for another.

5. A spray gun as defined in claim 1 wherein said spray component comprises a tubular supply extension and means for varying the cross section of the path through which material is supplied to the spray component.

6. A spray gun as defined in claim 1 wherein said spray component is made of insulating material and has a free surface whose edge constitutes the spraying edge.

7. A spray gun as defined in claim 1 further comprising suspension means arranged at said front end of said reservoir.

8. A spray gun as defined in claim 7 wherein said suspension means has a passage communicating with the interior of said reservoir for venting the same.

9. A spray gun as defined in claim 8 wherein said passage is dimensioned to allow the same to be used as a refill passage.

10. A spray gun as defined in claim 9 wherein, for pur- 5 6 poses of refilling said reservoir, there is introduced into 3,008,645 11/1961 Morel et al. 23915 said passage an outlet valve of a material dispenser which, 3,039,696 6/1962 Point et a1. 239-15 upon actuation of said outlet valve, dispenses a dosed 3,048,498 8/1962 Iuvinall et al. 23915 quantity of material. 3,093,309 6/1963 Watanabe 23915 References Cited 5 EVERETT W. KIRBY, Primary Examiner UNITED STATES PATENTS CL XR. 2,826,513 3/ 1958 Blanchard 2393 239 3, 302, 375

2,914,221 11/1959 Rosenthal 239-15

Images