US 3291396 A
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Description (OCR text may contain errors)
Dec. 13, 1966 WALTER SELF-PURGING MIXING AND SPRAYING APPARATUS Filed NOV. 30, 1964 ATTORNEYS United States Patent I 3,291,396 ELF-PURGING MIXING AND SPRAYING APPARATUS John Walter, 32 Fairview Ave, Kitchener, Ontario, Canada Filed Nov. 30, 1964, Ser. No. 414,552 8 Claims. (Cl. 2394l12) This invention relates to mixing and spraying devices and is particularly concerned with a self-purging mixing and spraying apparatus adapted to operation with fluid components varying widely in viscosity.
With the recent development of a family of chemicals which are characterised by foam producing qualities following mixture, there has been proposed several types of spray guns which may be used to simultaneously mix and spray the chemicals. A good number of these spray gun designs have recognized the importance of self-purging or self-cleaning characteristics as to avoid retention within the guns of a mixture of components which might be cured and hardened within the gun as to cause it to seize. An example of the prior designs is the one shown in United States Patent No. 2,890,836 to F. E. Gusmer et al., dated June 16, 1959. While the Gusmer et al. apparatus is capable of self-purgation, it is not capable of working with fluid components of high viscosity. Further, it is not adapted to adjustment of the outlet orifice whereby to render the apparatus capable of completely mixing components varying widely in viscosity.
It is, therefore, an object of this invention to provide a self-purging mixing and spraying apparatus which is particularly adapted to use with fluid components of high viscosity.
It is a further and related object of the invention to provide an apparatus of this type which is adapted to adjustment of the outlet orifice as to achive complete mixing of two components varying widely in viscosity while also being capable of purging itself as its operation is shut down.
These and other objects of the invention are accomplished by providing a mixing and spraying apparatus which is characterised by a plunger which is not only capable of longitudinal reciprocation as is the plunger of the Gusmer et al. device mentioned above but which is also adapted for rotation about its longitudinal axis as to ensure better mixing of the components to be sprayed. The apparatus is further characterised by the use of a component inlet opening and closing device which closes the inlets before the plunger moves forward to close the outlet orifice. This device is also coupled to the plunger in such manner that the rearward movement of the plunger may be adjusted by changing the length of the rearward stroke of the device. By thus adjusting the rearward movement of the plunger, it is possible to gain adjustment of the size of the outlet orifice.
The invention will be more thoroughly understood from the following description of a preferred embodiment thereof as read in conjunction with the accompanying drawings.
In the drawings,
FIG. 1 is a side elevation view mainly in section of a mixing and spraying apparatus in accord with this embodiment of the invention; and
FIG. 2 is a similar sectioned side elevation view of the forward end of the embodiment shown in FIG. I and illustrating a second position of the various moving parts thereof.
Referring to FIG. 1, the illustrated embodiment of the invention essentially consists of a barrel having a longitudinal bore 12 containing a plunger 14 adapted for both reciprocation and rotation and having a conical forward tip 15, an air motor or the like 16 for rotating the plunger, and a piston and cylinder mechanism 18 for effecting reciprocation of the plunger. The apparatus is provided with a handle 20 having a trigger 22 for controlling operation of the piston and cylinder mechanism 18.
Barrel It) might be made of any suitable metal forged or cast to the general shape shown and subsequently machined whereby to accurately" dimension the internal bore 12 and to provide the screw threads 24 and 26. At its forward end, the barrel carries a first collar 28 defining an annular chamber 30 having an annular outlet 32 and an inlet 34. A conduit 36 is fixed to the inlet and is connected at its other end to a source of compressed air so that annular chamber 30 has the function of providing an annular jet or air out orifice 32 to assist in the spraying operation. Collar 28 has the additional function of positioning a conical insert 33 against the forward end of barrel 10. A lock ring 40- is used to hold collar 28 and insert 38 tightly against the barrel through engagement with thread 24. For a purpose explained hereinafter, insert 38 is preferably made of a plastic having low friction producing qualities such as the plastic sold under the trademark Teflon.
Barrel 16' is tangentially apertured, preferably at diametrically spaced points, as to provide two inlet orifices 39 and 41 to the internal bore 12. Conduits 42 and 44 are connected to these inlets at one end and are connected at their other ends to sources of the fluid components to be mixed and sprayed. Conduits 42 and 44 are shown in the drawings as extending radially from the barrel. This is done for the sake of clarity and it should be understood that these conduits actually extend from the barrel tangentially. The rear end of the barrel is held tightly against a bearing member 46 by a lock ring 48 with the bearing member being rigidly attached, as by welding or the like, to the forward wall 50 of the piston and cylinder mechanism 18. Bearing 46 is preferably provided with an O-ring 52 for effecting a fluidtight seal against the outer surface of a reciprocating component inlet opening and closing collar 54, hereinafter simply referred to as the collar 54. This collar essentially consists of a tube mounted coaxially about the plunger 14 and bearing against the inside surface of bore 12. As a matter of convenience, collar 54 is made in two parts connected together by threads 56. The main purpose of this two-part construction is to provide a simple method of attaching a washer-like ring 58 to the collar but the collar and the ring 58 could be made as an integral unit.
The rear end 60 of the collar 54 is fixed to a piston 62 contained within the mechanism 18. This piston is provided with an O-ring 64 as to effect an air-tight seal against the inside surface of the cylinder wall 66. In this regard, it will be noted that the forward wall 50 and the rear wall 67 of the mechanism 18 are provided with a pair of apertures 68 and 70 whereby compressed air may be admitted to either side of the piston. In the normal course, i.e. when the apparatus is not in operation, compressed air admitted through inlet 70 urges piston 62 to the left as shown in the drawings, whereby to hold collar 54 and plunger 14 in the positions shown in FIG. 1. Upon actuation of trigger 22, compressed air is admitted through the inlet 68 with inlet 70 acting as an escape opening as to move piston 62 to the right to the position shown in FIG. 2 with the piston carrying the collar and plunger with it. The manner in which the actuation of trigger 22 operates is not actually illustrated in the drawings as this would be obvious to those skilled in the art, it being suflicient to understand that there is provided some means of feeding compressed air to either side of piston 62.
As the mixing and spraying apparatus in accord with this invention is essentially a pneumatic device, motor 16 is preferably pneumatically operated but it will be appreciated that an electrically operated motor would accomplish the desired rotation of plunger 14 equally as well. The pneumatic motor is not shown in detail as its construction is known heretofore, it being sufficient to point out that the out-put shaft 72 is constructed to grip the rear end of the plunger in such a manner that rotation of the plunger is effected with rotation of the output shaft 72 while the plunger is still capable of longitudinal reciprocation with respect to the output shaft 72. Thus, the rear end of the plunger might be splined or it might be formed with a square or hexagonal cross-sectional shape adapted to be received in a socket in the output shaft 72 in a sliding fit. An outlet 74 to motor 16 provides means for coupling the motor to a source of compressed air.
Reference has been made to the fact that both the collar 54 and plunger 14 are moved longitudinally by means of the piston 62. In actual fact, piston 62 is connected directly to only collar 54 so that longitudinal movement of the plunger is effected through engagement of the washer-like ring 58 in a groove 76 in the outside surface of plunger 14 or, more accurately stated, with a groove 76 formed in a tubular bearing 78 which is fixed to the plunger 14 by the screw thread 80. Bearing 78 is also preferably made of Teflon as to ensure slippage between collar 54 and the plunger.
Thus, longitudinal movement of the plunger is effected only when ring 58 engages either the forward shoulder 82 or the rear shoulder 84 of groove 76. By this arrangement, movement of the piston 62 always first effects movement of collar 54 to either fully open or fully close the inlet orifices 39 and 41 before the plunger moves. To illustrate the sequence of events on starting the apparatus, reference is made to FIG. 1. Upon application of pressure to trigger 22, compressed air is forced into' the cylinder on the left-hand side of 'piston 62. As a result, the piston moves to the right carrying collar 54 with it. Immediately the forward face 86 of the collar moves completely past the inlet orifices 39 and 41, the ring 58 bears against shoulder 84 and as the collar continues to follow the piston 62, the plunger is also pulled to the right. The reverse sequence takes place when the apparatus is shut down. Thus, release of pressure on trigger 22 causes compressed air to move into the cylinder on the right-hand side of piston 62 and the piston moves to the left carrying the collar with it. However, no move+ ment of the plunger takes place until the ring 58 bears against the forward shoulder 82 of groove 76 and by proper dimensioning of the groove, the inlet orifices 39 and 41 are completely closed by the collar 54 before the plunger moves forward.
By employing the separate collar 54 to open and close the inlet orifices 39 and 41, it is possible to gain adjustment of the spacing between the conical forward tip of the plunger and the inlet 38. This adjustment is achieved by the use of spacer rings 88 of varying thickness. In this regard, it will be noted that collar 54 is provided with a shoulder 90 which bears against the spacer ring 88 and the thickness of the spacer ring determines the overall length of stroke of the collar 54. Thus, by using a very thick spacer ring 88, the total movement of the collar may be limited to the distance required to fully open the orifices 39 and 41, plus an additional very short movement so that the plunger is moved to the right a distance equivalent to only the additional short movement of the collar. By the same token, use of a very thin spacer ring 88 will gain a large movement of the plunger to the right as to create a large spacing between the conical tip 15 and the insert 38.
It is this adjustment of the spacing between the conical tip and insert 38 which adapts the apparatus to gain thorough mixing between any two components which vary widely in viscosity. It has been found that with spraying devices known heretofore, which have no means for adjusting this spacing, while it may be possible to gain reasonable mixing of two components which have viscosities of the same order, poor mixing results when using a first component of high viscosity and a second component of low viscosity. In the apparatus of this invention two components of widely differing viscosity can be thoroughly mixed by reducing the spacing between the forward tip of the rotor and insert 38 as to increase the milling effect on the components as they pass through the outlet orifice.
In addition to the above described feature, the apparatus in accord with the invention is particularly adapted to mixing and spraying fluid components of high viscosity due to the use of a plunger which rotates. With the combination of the tangential introduction of the com onents (which step, by itself, has been employed in prior spraying devices) and the rotation of the plunger, there is gained thorough mixing of the components even if they possess high density and viscosity. Thus, it has been found that the apparatus can be used to effectively mix and spray fluid components having densities as high as 15 to 20 pounds per square foot and viscosities as high as 5000 centipoise. The apparatus has the further advantage in that it employs a device other than the plunger itself for closing the component inlets. This device (collar 54) not only gains particularly good selfpurging of the apparatus but also provides means whereby the outlet orifice may be adjusted with the resultant adaptability to the mixing of components varying widely in viscosity.
What I claim as my invention is:
1. A self-purging mixing and spraying apparatus comprising an elongated barrel having a longitudinal internal bore terminating at one end in a conical outlet, a plunger received in said bore and mounted for longitudinal reciprocation and rotation about its axis, a conical forward tip carried at one end of said plunger and adapted to seal the bore outlet by engaging the inside surface of said outlet, means for rotating said plunger, means for reciprocating said plunger, a first inlet through the wall of said barrel adapted to receive a first conduit for feeding a first fluid component to said bore, and a second inlet through the wall of said bore adapted to receive a second conduit for feeding a second fiuid component to said bore.
2. An apparatus as claimed in claim 1 in which said means for rotating said plunger comprises a pneumatic motor having an out-put shaft connected to the end of said plunger remote from said forward tip in such a manner as to permit axial relative movement between said plunger and said output shaft.
3. An apparatus as claimed in claim 2 in which said means for reciprocating said plunger comprises an air piston and cylinder mechanism fixed to and between said barrel and said motor with the piston being mounted coaxially about said plunger, a sliding collar fixed to said piston and also coaxially mounted on said plunger for longitudinal movement therewith, ring means carried on the inside of said collar, a groove in the outside surface of said plunger whereby said ring means engages the shoulders of said groove as to move said plunger with said collar, and means for introducing compressed air to either side of said piston.
4. An apparatus as claimed in claim 3 in which said collar includes an annular forward extent adapted to close and open said inlets, said groove and ring means being dimensioned and located to cause opening and closing of said inlets before movement of said plunger takes place. i
5. An apparatus as claimed in claim 4 in which said collar further includes a length of stroke determining shoulder, said apparatus further including a spacer ring coaxially mounted about said collar at the end of said bore remote from the bore outlet, said collar shoulder being adapted to bear against said spacer ring when said collar is retracted away from said bore outlet, said spacer ring being replaceable by rings of varying sizes whereby the maximum rearward movement of said collar away from said bore outlet may be adjustable.
6. An apparatus as claimed in claim 5 in which said apparatus further includes a plastic conical insert in the conical outlet of said bore in which the plastic is of a type having low friction producing qualities.
7. An apparatus as claimed in claim 6 further including an annular chamber positioned around the bore outlet, means for introducing compressed air into said chamber, said chamber having an annular forward outlet extending around the final outlet of said bore whereby compressed air may be introduced into the mixed components emerg- References Cited by the Examiner UNITED STATES PATENTS 1,369,520 2/1921 Day 239-412 2,788,337 4/ 1957 Preiswerk et al 239-428 2,890,836 6/1959 Gusmer et al. 239428 2,970,773 2/1961 Keryluk et al. 239-442 3,053,457 9/ 1962 Trumbull et al 239-142 3,132,808 5/1964 Ott 239142 EVERETT W. KIRBY, Primary Examiner.