US2705663A - Spray gun - Google Patents

Description

April 1955 R. I. GILBREATH SPRAY GUN Filed Aug. 8, 1952 -H H-HH INVENTOR. Robe/"f G/Ibreaf/v BY i764/W A TTOR'NE Y5 United States Patent SPRAY GUN Robert I. Gilbreath,-Burlingame, Calif.

Application August 8, 1952, Serial No. 303,271

1 Claim. (01. 299-150 This invention relates to dispensing devices, and more particularly to a novel form of spray gun which is especially adapted for the spray type dispensing of fluids which congeal at normal temperatures.

It is an object of this invention to provide a spray gun of the stated type embodying novel means for circulating fluids through the gun so as to prevent the congealing of these fluids during periods when the gun is not in operation as a dispenser.

It is a further object of this invention to provide a spray gun of the stated type embodying, in combination with fluid circulation means adapted to prevent congelation of the fluid to be dispensed, a double valve control system, with one of said valves being disposed at the outlet or nozzle end of the gun and being normally operable to control the dispensing of the fluid from the gun, and with the other valve being disposed at the outlet side of the fluid circulation means and being operable when the nozzle valve is removed or disabled to prevent the discharge of fluid from the gun.

A further object of the invention is to provide a spray gun of the stated type comprising, in combination, a fluid circulation system, a dual valve control system, and cylindrical filter means for the fluid disposed between the two control valves and being adapted to have channeled therethrough the fluid which is dispensed from the gun.

Other objects and advantages of the invention will be apparent from the following description taken in conjunction with the drawingforming part of the specification, and in which:

Figure 1 is a view in side elevation of the spray gun of the invention, with the forward, or discharge, end thereof being shown in vertical diametral section;

Figure 2 is a view in section of the forward, or discharge, end of the spray gun showing the valve control system in a condition of operation which is different from that condition of operation illustrated in Figure 1; and

Figure 3 is a view in section taken along lines 3--3 of Figure 1. j

Referring to the drawing, the spray gun indicated generally at comprises: ahandle portion 12; a stock or barrel portion 14; a trigger rod 16 carried for reciprocal movement by stock 14 and yieldingly uged away from stock 14 by spring means, not shown; a trigger l8 pivotally attached at 20 to the barrel of the gun and having a one-Way connection 22 with trigger rod 16; a hand shield 24 in the form of a plate secured to the forward end of the barrel of the gun and through which trigger rod 16 extends; a plurality of elongated bolts 26 serving to mount a head member 28 on plate 24 and also serving as the carrier members for a plurality of cooling fins 30 maintained in spaced apart relation by spacer sleeves 32 disposed on the bolts 26; and a valve stem indicated generally at 34 connected at 36 to trigger rod 16 and extending through packing gland 38 carried by head member 28 and through the head member 28.

Conduits 40 and 42 are secured to the head member 28 in communication with chamber 44 formed in the head member. These conduits, which are connected across a liquid sump and pumping system, not shown, constitute inlet and outlet lines for the circulation through the head member of the liquid to be dispensed from the spray gun.

A union member 46 having a double diametral bore 48 is threadably engaged with the head member 28. Disposed within the larger diametral portion of bore 48 is a cylindrical strainer screen 50 sleeved over a slotted tubular carrier member 52 and held in place on the carrier mem- 2,705,663 Patented Apr. 5, 1955 her in abutting relation with the end flange 54 thereof by an end plug 56 threadably attached to member 52. The valve stem 34 has a sliding fit within a centrally disposed aperture formed in end plug 56. The gun is further provided with a nozzle tip 58 having a centrally disposed fluid discharge passage 60 therethrough. The nozzle tip is provided with a flange 62 at its inner end, and a retainer nut 64 threadably engaged with union 46 secures the flanges 54 and 62 together, with flange 54 being in engagement with the forward end of union member 46.

The valve stem 34 is provided at its forward end with a needle point 66 adapted to seat, when retainer nut 64 is in full threaded engagement with union member 46, in the inner end of the nozzle tip passage 60, thus serving to valve off this passage, while the stem is further provided with a conically shaped portion 68 adapted, when the retainer nut 64 is backed off of union member 46, as shown in Figure 2, to seat within the smaller diametral portion of bore 48 of the union member, thus shutting off communication between chamber 44 of head member 28 and bore 48 of the union member.

The spray gun described is specifically for use with fluids which have to be maintained at elevated temperatures in order to avoid congelation. For example, the material handled by this gun has been a wax-like substance which is sprayed on metals, concrete, and the like to serve as an anti-corrosion and anti-erosion protective covering. This material must be maintained at temperatures within the range of 300400 F. during application. The material is thus constantly circulated through the conduits 40 and 42 and chamber 44 from and to a suitable source of the hot material by means, such as a pump. When it is desired to dispense the material through the nozzle tip 58, the trigger 18 is pulled back to withdraw the needle point 64 of the valve stem from its seated position within passage 60 of the nozzle tip. While the trigger is maintained in its rearward position against the counter action of the spring, not shown, some of the material circulating within and through chamber 44 passes into the bore 48 of the union member 46, through the screen 50 and the tubular carrier member 52, and out the nozzle passage 60. Upon release of the trigger 18 of the valve element 66 seals the passage 60.

During normal operation of the spray gun with material of the type described, it frequently becomes necessary to remove and clean the strainer screen. The subject gun embodies means for simple and quick removal of the screen without requiring a cessation of circulation of the hot material through the conduits 40 and 42 and chamber 44. As the retainer nut 64 is backed off the union member 46 at the outset of the operation of removing the nut and the nozzle tip 58 in order to remove the screen for cleaning, the valve stem, due to the action of its compression spring, forces and follows the nozzle tip outwardly to the point where valve element 68 of the stem seats within bore 48. The circulation chamber 44 is thus sealed oft" from the discharge end of the gun. After the screen has been removed and. cleaned, it is reinserted within the bore 48; the nozzle 58 is placed in following relation to the screen; and the retainer nut is turned all the way down on the union member 46, thus causing valve element 66 to seat within the nozzle tip and causing the valve stem 34 to be moved yieldingly rearwardly to unseat valve element 68.

While a specific embodiment of the invention has been shown and described, it is to be understood that all substantial equivalents of this embodiment are within the spirit and scope of the invention.

What I claim is:

A spray gun comprising a head member having a chamber defined therein, a union member connected to said head member and having an axial passageway therethrough communicating with said chamber, a valve seat defined in said union member at the chamber end of said passageway, a nozzle disposed at the other end of said union member having a discharge passageway therethrough in axial alignment with said union member passageway, a valve seat defined in said nozzle at the inlet end of its discharge passageway, a valve stem slidably disposed in said head member extending through said chamber and said union member passageway in axial alignment with said passageways, spring means yieldingly urging said stem in the direction of said nozzle, said stem having terminal and intermediately disposed valving elements adapted to engage, respectively, said nozzle valve seat and said union member valve seat, adjustable coupling means connecting said nozzle to said union member operable when moved outwardly with respect to said union member to cause said spring means to move said stem and engage said intermediately disposed valving element with said union member valve seat and operable when moved inwardly with respect to said union member to disengage said intermediately disposed element from said seat While maintaining said terminal valving element in engagement with said nozzle seat, means for moving said valve stem away from said nozzle, and inlet and outlet conduits connected to said head member and operable to deliver fluid to and receive fluid from said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,625,635 Willners Apr. 19, 1927 1,716,195 Stockstrom June 4, 1929 1,763,687 Chadwick June 17, 1930 1,788,810 Tittemore Jan. 13, 1931 1,825,864 Harter Oct. 6, 1931 1,979,179 Taylor Oct. 30, 1934 2,396,449 Wahlin Mar. 12, 1946 2,576,534 Pasche Nov. 27, 1951 2,595,639 Chmura May 6, 1952

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