US2676844A - Spraying device - Google Patents

Description

J. A. PAASCHE SPRAYING DEVICE Filed Oct. 16, 1953 April 27, 1954 4 'V////// J J 5 3? w z a var/abl Patented Apr. 27, 1954 UNITED STATES PATENT OFFICE SPRAYING DEVICE Jens A. Paasche, Chicago, Ill;

Application October 16, 1953, Serial No. 386,642

2 Claims.

This invention relates to coating apparatus. and more. particularly to manual spraying devices and is a continuation-in-part of my copending application, Serial No. 129,587, filed November 26, 1949.

Thisinvention concerns atomizing devices of the-typein which the container for the material to be sprayed, the atomizing nozzle, and the fluid control mechanism form a unit. In devices of this type the stream of spraying fluid is conducted past the opening of a passage connected to a source of material to be'sprayed whereby to draw fluid into the. fluid'stream to form an atomized mixture: The resultant mixture is directed through a nozzle to the surface to be sprayed or coated. In an apparatus ofthis type diificulty has been encountered heretofore at the beginning and end of the sprayingoperations; At the end of a spraying operationor stroke the. material being sprayed whichiis' in the fluid and nozzle passages tends to accumulate at the mouth of'the nozzle. This material leaks from the nozzle and runs down the side of the spraying apparatus or drops from the end of the spraying nozzle. When the-spraying operation is commenced, thematerial accumulated in the nozzle tends to spit and sputter producing an. undesirable effect on'the surface being sprayed. Any spraying material present in the outlet'passage ofrthe'nezzle also tends todry and solidify, thereby clogging the outlet passagesof the nozzle.

Spraying-apparatus of the type described have heretofore been provided with air vents in the material container. Spilling of material from the container occurs whenever such= apparatus is tilted or tipped during use since the spraying material escapes through the air vent.

The present invention contemplates providing a spraying device of the type described in which the material in the nozzle and spraying passages at the end of the spraying stroke is drawn back into the material container. There also iszprovided a material container which will not leak in the'event that the spraying apparatus is inadvertently tipped or tilted.

Accordingly, it is an important object of the present invention to provide" an improved spraying device of the type described in which material in the nozzle and outlet passages is drawn back into the material container upon interruption of the spraying fluid stream whereby to prevent leakage from' they nozzle: and spitting and sputteringat the beginning of the next spraying stroke;

Another object of the invention is to provide aspraying apparatus oithe type described in which the material container will not leak upon inadvertent' tipping of the spraying apparatus.

A further object of the invention is to provide an improved yet simplified spraying nozzle for spraying apparatus of the type described which is easier to clean and maintain and which will operate at generally lower pressure and air volumes, by the utilization of internal and external atomization of the material.

Still another object of the invention is to provide an improved nozzle structure for spraying devices of the type described which gives a better atomization with lower air pressures.

Various other objects, advantages and features of the invention willbe' apparent from the following specification when taken in connection with the accompanyingdrawings wherein a preferred embodiment is, set vforth for purposes of illustration.

In the drawingwherein like reference numerals refer to like parts throughout:

Figure 1 is aside elevational viewof aspraying apparatus embodying the principles of the present invention according to a preferredembodiment thereof witha portion of the apparatus showing in vertical cross section;

Figure 2 is a partial vertical cross sectional view showing the nozzle and fluid passages of" the device of Figure 1;

Figure 3 is a cross sectional view of the nozzle structure shown in Figure 2 substantially as seen in the-direction of the arrows along the line 3-3 of FigureZ; and

Figure 4 is across. sectional view of the nozzle as seen in the direction of the arrows along the line 4 -4 of Figure 2, andfurther showing a modification wherein thesprayingdevice may be used without the separate nozzle cap.

Referring to the drawing and more particularly to Figure 1 thereof, there is shown one preferred example of a spraying apparatus embodying the principles of the present invention. This spraying apparatus comprises. generally a handle It], a nozzle structure generally designated by the numeral l2, and a container 14 for holding material to be sprayed;

A passage I6 is formed in handle it substantially longitudinally and centrally thereof. One end of passage" l6 extends to the lower end of handle [0 which end of handle it) is threaded as at IE to receive a coupling 20 which is connected to a source (not shown) of motive spraying fluid under pressure. A- strainer 22 is placed at the lower end of passage [6 and is heldin place by a retaining ring- 242 Positioned at the upper end of passage I6 and at the upper end of handle I is a valve assem bly comprising a valve washer 26 and a valve head or closure 28. The valve closure 28 in the position shown, is effective to close the upper end of passage I6 and may be actuated by pressing a knob 36 which is attached to the valve closure 28 by a stem 32. The valve closure 28 is maintained in the upward or closed position by a spring 34 which is positioned between the under side of knob 36 and the handle III. The lower end of spring 34 is pressed against a packing gland 36 and a packing washer 38 which effectively seal the passage surrounding stem 32. This packing arrangement, is necessary to prevent escape of motive fluid when valve closure 28 is open. It will be seen that spring 34 in addition to holding the valve closure 26 in the closed position also aids in keepin the packing gland and washer tightly sealed against the stem 32.

A body portion 40 is formed integral with and extends laterally from the handle I0. Formed in the body portion 40' is a passage 42, one end of which connects through valve closure 28 to the fluid passage I5. The other end of the fluid passage 42 connects with a passage 44 in the nozzle structure I2. Formed on the end of body portion 49 opposite the handle I0 is a hook 4B.

The nozzle structure I2 comprises a body portion 48 from one end of which extends a tubular member 56 which is adapted to be inserted in the passage 42 of body portion 40 and sealed therein or otherwise firmly connected thereto. The provision of this type of nozzle structure makes possible the use of relatively hard materials which give increased wear with abrasive material and renders the structure replaceable. Passage 44 extends through the tubular member 50 and into the main body portion 48 of nozzle structure I2. Adjacent the center of body portion 48 passage 44 connects with a throat or Venturi section 52 which in turn connects with an outlet nozzle passage 54. When knob 30 is actuated, opening valve closure 28, a passage for motive fluid is provided from the source through passage I6, past valve closure 28, through passages 42 and 44 to the Venturi or throat section 52, and thence to th outlet passage 54. In flowing from passage 44 into throat section 52, the motive fluid will be slightly compressed and its velocity increased.

Upon issuing from the throat section into the enlarged outlet passage 54, the motive fluid will tend to expand, reduce its velocity and thus create an area of reduced pressure at the junction between throat 52 and outlet passage 54.

The outlet passage 54 terminates in a cap 55 which is threadedly attached to body portion 48. One end of a converging passage 51 in cap 55 connects with passage 54 and the other end connects with an elongated slot 59 which produces a Wide fan-shaped spray pattern. The circumference of cap 55 is provided with a hexagonally shaped portion to facilitate removal and application.

A material passage 56 is also formed in the nozzle structure I2. One end of passage 56 opens into passage 54 at the junction of passage 54 and throat section 52. The other end of passage 56 connects through tube 58 to a quantity of material to be sprayed which is held in container I4. The reduced pressure at the junction of throat section 52 and the outlet passage 54 is utilized to draw material from container I4 up and to the main motive fluid stream where it is mixed with the motive fluid and expelled from the outlet passage 54.

Container I4 is attached to the nozzle structure I2 by means of a cover member 60. A screw 62 threadedly attaches the cover 66 to the under side of nozzle structure I2. A cylindrically shaped portion of cover is provided with internal threads as at 64 which cooperate with complementary threads on the container I4 to hold the container and cover in cooperative relationship. A gasket 66 is positioned between the upper lip of container I4 and the under side of cover It to insure a fluid tight connection therebetween. The tube 58 is connected to cover 60 by means of a socket 58 which is connected to tube 58 and threadedly attached to cover 60. It is to be noted that there is no air vent for container I4 or cover I6, the only outlet from container I4 being through the tube 56.

Means is provided in. material passage 56 for controlling the flow of material therethrough. As may be best seen in Figures 3 and 4, an aperture III is formed in the nozzle structure I2 perpendicular to and connecting with the material passage 56. The walls of aperture I'll are threaded to receive a needle valve which comprises a valve closure member I2, a valve stem 14 and a control knob I5. When the valve closur of the needle valve is in the position shown in Figures 3 and the material passage 56 is closed; By withdrawing the valve closure 12 the amount of material flowing through passage 56 can be increased and controlled as desired to feed fluid for narrower or wider pattern spray.

In using the spraying device above described in this specification, the material is applied to the surface to be coated in a plurality of individual strokes or passes. For example, to coat a vertical section the spraying apparatus is positioned at one edge of the section to be coated at a short distance away from the surface. The knob 36 is depressed opening valve closure 28 and allowing the motive fluid to flow from the source through the Venturi section 52 and out of outlet passage 54. The reduced pressure at the junction 52 and passage 54 in cooperation with the higher pressure within container I4 forces the material up through tube 50 and passage 56 into outlet passage 54. When material issues from the nozzle the spray gun is moved towards the other edge of the section to be painted. Upon arriving at the other edge of the section to be painted, knob 36 is released, closing valve closure 28 and stopping the flow of motive fluid to Venturi section 52.

Since there is no air vent opening into container I4 the pressure within container I4 will be reduced by operating the spraying device. For this reason as soon as knob 3 is released. the differential in pressure between atmospheric pressure and the pressure within container I4 will cause a flow of air into container I4 that will carry any excess material in outlet passage 54 and material passage 56 back into container I4 through tube 58. It is seen therefore that no leakage will occur at the end of the coating stroke. Likewise when knob 36 is again depressed to begin a new stroke, there will be no material in passages 54 and 56 to cause spitting or sputtering.

Since air is drawn in through passages 54 and 56 when knob 30 is released, the pressure within container I4 will be restored before the beginning of the next coating stroke. For this reason no Vent is required for container I4 and hence there can be no spilling or loss of material by inadvertently tipping the spraying device while in operation. It is seen therefore that operation will be cleaner and neater and a saving in the material being sprayed will be achieved.

The material issuing from passage 56 will be atomized in the low pressure area at the junction of passage 54 and throughout section 52 and simultaneously thoroughly mixed with the stream of motive fluid. The resultant mixture will again be atomized upon issuing from outlet passage 54. A high degree of atomization is therefore obtained for a given air pressure and it is therefore possible to obtain a satisfactory atomization at a relatively low air pressure. However, it is understood that in many instances for certain jobs and with certain air pressures available the spraying apparatus may be modified as shown in Fig. 4 by eliminating cap 55. By providing a valve in the material passage 56 the quantity of material being sprayed can be accurately controlled yet a uniform degree of atomization will be obtained since the amount of motive fluid remains constant.

The present invention provides a nozzle structure of simple and economical construction which is easy to keep clean, which saves materialbeing sprayed and which Will operate at substantially lower air volume and pressures.

It is obvious that various changes may be made in the specific embodiments set forth without departing from the spirit and scope of the invention. The invention is therefore accordingly not to be limited to the particular embodiments shown and described and only as indicated in the following claims.

The invention is hereby claimed as follows:

1. A short-stroke spray gun comprising a body structure having a motive fluid passage adapted to be connected to a source of motive fluid under pressure, saidrmotive fluid passage extendign to the delivery end of the body structure and including a Venturi section'communicating with an outlet passage of larger but limited crosssection, a material passage formed in said body structure and in communication with said outlet passage at a point spaced inwardly from the delivery end thereof and adjacent the issuing end of said Venturi section, a closure member on said body structure and adapted to receive and close a container for the material to be sprayed, a nozzle at the delivery end of said body structure and including a spray issuing passage reduced relative to the delivery end of said outlet passage, a tube carried by said body structure in communication with said material passage and adapted to extend into the container, said tube providing the sole and only path of air communication with the interior of the container from the nozzle, outlet passage and material passage and thereby operating to direct material to be sprayed into said material passage and thence through said outlet passage and nozzle passage upon the rapid traverse of motive fluid through the Venturi section and the outlet and nozzle passages for a limited length of time, and further operating upon cessation of such traverse of motive fluid to direct residual material from the nozzle, outlet and material passages back into the container under the influence of reduced pressure created in the container during the limited traverse of motive fluid, whereby to prevent dripping of material from the nozzle and to maintain the nozzle, outlet and material passages in cleansed condition.

2. A short-stroke spray gun comprising a body structure having a motive fluid passage adapted to be connected to a source of motive fluid under pressure, said motive fluid passage extending to the delivery end of the body structure and including a Venturi section communicating with an outlet passage of larger but limited cross-section, a material passage formed in said body structure and in communication with said outlet passage at a point spaced inwardly from the delivery end thereof and adjacent the issuing end of said Venturi section, a closure member on said body structure and adapted to receive and close a container for the material to be sprayed, a tube carried by said body structure in communication with said material passage and adapted to extend into the container, said tube providing the sole and only path of air communication with the interior of the container from the outlet passage and material passage and thereby operating to direct material to be sprayed into said material passage and thence through said outlet passage upon the rapid traverse of motive fluid through the Venturi section and the outlet passage for a limited length of time, and further operating upon cessation of such traverse of motive fluid to direct residual material from the outlet and material passages back into the container under the influence of reduced pressure created in the container during the limited traverse of motive fluid, whereby to prevent dripping of material from the outlet passage and to maintain the outlet and material passages in cleansed condition.

References Cited in the flle of this patent V UNITED STATES PATENTS Number Name Date 1,051,069 Bohme Jan. 21, 1913 1,501,432 Bleakley July 15, 1924 1,793,383 Adams "Feb. 17, 1931 1,806,784 Breuer May 26, 1931 1,950,796 Hilgerink Mar. 13, 1934 2,368,536 Gersmehl Jan. 30, 1945

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