US3138303A - Pressure gun - Google Patents

Description

June 23, 1964 .1. c. HOVELAND PRESSURE GUN Filed Feb. 15, 1961 INVENTOR JULIAN CLEON HWELAND United States Patent 3,138,303 PRESSURE GUN Julian Cleon Hoveland, North Surrey, British Columbia, Canada, assignor to M. D. Muttart, Edmonton, Alberta,

Canada Filed Feb. 13, 1961, Ser. No. 88,809 1 Claim. (Cl. 222-389) This invention relates to a pressure gun particularly for use in the application of mastic material in corners and cracks, but which may be used for any other desired purpose.

An object of the present invention is the provision of a pressure gun which holds a mastic or similar material to be discharged therefrom by fluid pressure, and which completely prevents the pressure fluid from getting into said material.

In the erection of houses and other buildings, what is known as a dry wall construction is commonly used. Instead of using wet plaster the inside walls are covered by plaster board which comes in large sheets. The cracks and joints between the sheets along the walls and in the corners are filled with a mastic material. Guns for directing the mastic into'these joints have been in use for some time. Such guns consist of a cylinder with a free piston therein which is moved by air under pressure against the mastic to force it out through a discharge nozzle. The prior guns were not entirely satisfactory since it was impossible to keep the pressure air from getting past the piston into the mastic with the result that when the air reached the nozzle, the mastic instead of flowing out evenly and under control, spurted out and spattered all over the wall. In other words, the guns were not reliable.

The present invention overcomes this problem by providing means at the piston for trapping any pressure fluid attempting to move past the piston towards the mastic, and means for directing the trapped fluid out of the gun. As a result, the mastic always flows under control evenly from the gun.

A pressure gun according to the present invention comprises a cylinder closed at the ends thereof, and having a discharge outlet at one end and a pressure fluid inlet at the opposite end. The pressure fluid is usually air, but it may be a liquid, such as water. A piston is slidably mounted in the cylinder and is movable towards the outlet by pressure fluid entering the cylinder through said inlet. This piston has a peripheral wall slidable over the cylinder surface, and, usually, sealing means of the type commonly used for such pistons. Passage means is provided in the piston and opens through and around the peripheral wall thereof, and hose means within the cylinder and communicating with the piston passage means opens out through said cylinder near its inlet end to bring the passage means into communication with the atmosphere outside the cylinder. With this arrangement, the pressure in the passage means is the same as the atmospheric pressure outside the gun so that any pressure fluid moving past the piston flows into the comparatively low pressure area, and travels along the hose means to the outside atmosphere.

The hose means is preferably in the form of a flexible hose, and an important feature of this pressure gun is means therein for maintaining the hose in spiral formation so that said hose does not interfere with the return of the piston when it is desired to refill the gun.

Two forms of the invention are illustrated in the accompanying drawings, in which,

FIGURE 1 is a longitudinal section through a preferred form of pressure gun,

FIGURE 2 is a cross section taken on theline 22 of FIGURE 1,

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FIGURE 3 is a cross section taken on the line 3--3 of FIGURE 1, and

FIGURE 4 is a fragmentary sectional view similar to FIGURE 1, illustrating an alternative form of a pressure gun.

Referring to FIGURES l and 3 of the drawings, 10 is a pressure gun including acylinder 12 of any desired cross sectional shape, usually circular as shown. This cylinder hasend walls 13 and 14 removably mounted therein. In thisexample end walls 13 and 14 fit within the cylinder ends and are removably retained therein respectively by screws 16 and 17. A discharge outlet in the form of a pipe 20 is provided atend wall 14, said pipe extending through and being carried by said wall. A nozzle 21 is connected to the outer end of pipe 20, and has acontrol valve 22 therein which is operated by means of ahandle 23.

A pressure fluid inlet 26 is provided at the opposite end ofcylinder 12, preferably inend wall 13 centrally thereof. Astiff tube 28 extends through inlet 26 and is carried bywall 13. This tube extends a short way into the cylinder, and has a plurality ofapertures 29 therein. A flexible hose 32 extending from a suitable source of fluid under pressure is removably connected to the outer end oftube 28. The fluid for guns of this type is usually air, in which case, the hose extends from a compressor, pressure tank or air bottle.

Apiston 35 is slidably mounted incylinder 12 and has aperipheral wall 36 which is slidable over theinner surface 37 of said cylinder. Piston 35 is provided withstandard sealing cups 39 and 40 on itsopposite ends 41 and 42 slidably to engagecylinder wall 37. The piston divides the cylinder into amaterial chamber 46 and apressure chamber 47, the respective'sizes of which vary during movement of the piston.Material chamber 46 is at the outlet 20 end of the cylinder, whilepressure chamber 47 is at the inlet 26 end of said cylinder. Fluid underpressure entering chamber 47 from hose 32 movespiston 35 against material inchamber 46 to force said material through outlet 20 and nozzle 21 whenvalve 22 is open.

Passage means 50 is provided inpiston 35 which opens through and around theperipheral wall 36 thereof. In this example, the passage means includes agroove 52 inwall 36 extending around the piston and opening out- Wardly therefrom, and at least onepassage 53 extending inwardly from said groove towards the centre of the piston and opening out at 54 through theend 42 thereof. Although a groove is preferred, a plurality of holes may be provided instead ofgroove 52, said holes opening out from theperipheral wall 36.

Hose means is provided withincylinder 12 communicating with passage means 50 and opening out through the cylinder near theinlet end 13 thereof. This hose means is preferably in the form of aflexible hose 58 which is connected to theend 54 ofpassage 53 ofpiston 35. This hose is wound in a spiral, indicated at 60, and opens out throughend wall 13 at 61. Although thehose 58 does not have to be wound in a spiral, it is preferably so Wound so that whenpiston 35 is moved towardsend wall 13, the hose will not interfere with this action or be caught and perhaps damaged. Furthermore, it is highly desirable to provide means for maintaininghose 58 in its spiral formation. This is accomplished in a very simple manner by a stiffflexible wire 64 connected to and extending along the hose in a spiral. The simplest way to attain the desired results is to extendwire 64 through the hose as shown. Whenhose 58 andwire 64 are wound intospiral 60, they remain in that formation as a result of the stiifness of the wire. If desired, one end of wire '2 a; 64 may be anchored to prevent it from being displaced from the hose, as indicated at 66 in FIGURE 1.

Hose 58 keepsgroove 52 andpassage 53 of the passage means 50 ofpiston 35 in communication with the atmosphere outsidecylinder 12. As fluid under pressure is directed by hose 32 intochamber 47 of the gun, the piston is moved against the material inchamber 46 to keep it under pressure. Thus, whenvalve 22 is opened, the material flows through nozzle 21. The fluid ofchamber 47, usually air, attempts to move pastpiston 35 intochamber 46. However,groove 52 provides a comparatively low pressure area so that any such fluid, taking the path of least resistance, flows into the groove, alonghose 58 and out of the gun. Therefore, the piston passage means andhose 58 prevents any of the pressure fluid from reachingchamber 46.

Whenchamber 46 is empty,piston 35 is moved back towardsend wall 13 to enable the chamber to be filled again. The spiral formation ofhose 58 prevents said hose from getting in the way or being damaged during this action. Thestifl wire 64 ensures the hose remaining in its spiral configuration without interfering with the operation of the hose or the movement ofpiston 35.

FIGURE 4 illustrates an alternative pressure gun a in which the hose means is in the form of atelescopic tube 72 connected at 73 to the outer end of passage 53a of piston 35a.Telescopic tube 72 opens out at 75 throughend wall 13a of cylinder 12a. Otherwise,gun 10a is constructed in the same manner asgun 10.

Whengun 10a is in operation, it functions in the same way asgun 10, but as piston a is moved away from and towardscylinder end 13a,telescopic tube 72 respectively lengthens and shortens accordingly.

What I claim as my invention is:

In a pressure gun including a cylinder closed at its ends with a discharge outlet at one end and a fluid inlet at its opposite end and a piston having a peripheral wall and mounted slidably in the cylinder to be moved by a pressure fluid forced into the cylinder at the fluid inlet, a low pressure area in the piston opening out therefrom around the peripheral wall of the piston and spirally wound hose means positioned in the cylinder between the fluid inlet and the piston and connected to the low pressure area of the piston at its one end and opening out through the end of the cylinder near the fluid inlet to maintain the low pressure area of the piston in constant communication with the atmosphere outside the cylinder, such low pressure area being adapted to trap any pressure fluid moving past the piston and to direct such trapped fluid to the hose means.

References Cited in the file of this patent UNITED STATES PATENTS 2,811,950 Entz Nov. 5, 1957 2,918,903 Geyer Dec. 29, 1959 2,966,887 Arnold Jan. 3, 1961 3,074,437 Mercier Jan. 22, 1963

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