US2932285A - Air motor for a coating material pump - Google Patents

Description

D. J. PEEPS AIR MOTOR FOR A COATING MATERIAL PUMP 3 Sheets-Sheet 1 April 12,1960

Original Filed April 20, 1956 INVENTOR.

BY 1751mm JPEEFE'.

A TTORNE Y ing my invention with the pump special material drum;

- assembly 2,932,2ss Moron son A COATING MATERTAL PUMP Donald J. Peeps, Rossf'ord, Ohio, assignor to The De Vilhiss Company, Toledo, Ghio, a corporation of Qhio 6 Claims. (Cl. 12l-164) This invention relates to an air motor for a reciprocating pump for delivering coating materials and similar liquid compositions under constant, regulatable pressure and continuous flow and is a division of application 579,648, filed April 20, 1956, now Patent 2,895,421, issued July 21, 1957. More particularly, it relates to an air motor driven pump capable of handling material of high viscosity in substantial volume and under considerable pressure.

Due to pigments in coating materials as well'as their high viscosity much diliiculty has been experienced with pumps for dispensing such products. Sealing elements have been inclined to deteriorate rapidly causing leaks which lower the pressure and the volume of the coating material being delivered. The consequent shut-down for repairs may disrupt the production schedule and therethrough add extra costs. Abrasive action upon valves and valve seats also have frequently put them out of commission with resultant failure of the pump-and interruption of operations while replacement of parts is being made. I

Also, earlier pump designs did not have valve mechanism fully capable of conveying high viscosity coating materials at satisfactory rates. Another reason pumps available heretofor proved inadequate is that the power deveioped by the air motors was less than that r'equiredto build up the necessary fluid pressure for certain operations.

A principal object of this invention is to provide a pump which alleviates the aforementioned difficulties and shortcomings. v

More specifically, vide pumping unit are an object of my invention is to v vertically stream lined and areconnected by a common piston rod.

Another obiect of: my invention is the provision ofan internal valve mechanism for the air motor which is sturdy and quick acting.

Another object is the provision of a pump having an easily separable airfmotor and a coupling casting between the air motor and the pump unit serving secondarily as an air manifold.

These and other object and advantages of the invention will become apparent upon perusal ofthe following description and referring to thedrawings in which:

an elevation of a pump assembly embodyattached to a cover of a Figure l is Figure 2 is a plan view of the embodiment of Figure l; Figure 3 is "a vertical section of the air motor of the pump embodied in Figure 1", s V v Figure 4 is an enlarged vertical section of the valve and associated parts of the air motor; Figure 5 is a horizontal section taken on the of Figure 3; I

Figure 6 is an enlarged elevation of one of the valve line 5--5 stems; I a V Figure 7 is a similar view of the retainer of the exhaust valve O-ring's;

a compact pump in which the air motor and the v 70 ciprocably suspended in tubing projects through f. Figure 8 is an enlarged vertical section of the unit;

Figure 9 is astill further enlarged horizontal section taken on the line 99 of Figure 8;

Figure 10 is an elevation with parts broken away of the portion of the pump unit in the area adjacent to the line 9-9 of Figure 8; and

Figure 11 is a vertical section of a drain plug and its plastic sealing ring.

Referring to the drawings in more detail, the pump embodying this invention has an air motor 1 fixed upon the coupling casting 2 which in turn is fitted to the top of the pump unit 3. The pump assembly is supported upon the lid 4 to which it is secured by bolts 5. The lid 4 fits loosely over a special form of material drum 6.

As shown in Figures 1 and 2 coating material is drawn from the drum 6 'nection 9 on the side of and hence to nipple 10 leading to a fluid regulator 12. From the regulator which has a pressure reporting gauge 13 the coating material proceeds through a shut oil valve 14 and a flexible hose 15 to a manually operated spray gun 16.

An air supply hose 20 is fastened to the inlet nipple 21 of an air manifold 22 within the wall of the coupling casting 2. Air for operation of the air motor 1 passes from air manifold 22 into regulator 23 and through hose 24 to the air inlet opening 25 of the air motor. Upon regulater 23 are mounted a pressure gauge 28 and a safety valve 29.

Atomizing air for the spray gun leaves manifold 22 from the left hand outlet entering pressure regulator 30. The gauge 31 shows the pressure established by regulatube locating and .tor 30. A flexible hose 34 carries the atomizing air from the shut oif valve 32 gun 16. V p

A valve 37 is fastened to the other branch of coating material T connection 9. When desired for agitation or cleaning purposes this valve is opened to permit return flow of the coating material drawn up by thepump back to the drum 6 by way of tubing 38. The end of the an opening 39 in lid 4.

, A supporting ring 42 at the top of air motor cap 43 is provided for raising or lowering the pump assembly by means of a block and tackle. This is useful when becomes empty and is to be replaced with one carrying a fresh supply of coating material.

In Figures 3 through 7 the interior structure of the air motor is depicted. As shown, the air cylinder 46 is closed at its upper end by the cap 43. The casting 47 threaded to the lower end of the cylinder has an axial opening 48 for the tubular lower piston 49. The piston 49 is guided in the cylindrical bearing 50, a depending member of reducing diameter fixed to casting 47. A packing 51 of U shape is held around piston 49 in an annular chamber between the adjoining ends of casting 47 and its threadedly joined bearing member 50. A ported bushing 54 is threaded into the lower end of piston 47 and connects the piston to shaft 55 serving as a common piston rod or *drive shaft between the air motor and the pump unit.

At the upper end of lower piston 49 is closure 56 with an integral upwardly projecting nipple portion 57. Firmly threaded upon the nipple 57 is upper piston 66. An axial bore 61 in this piston forms with the nipple an air'passage communicating with the interior of lower piston 49. A packing ring 62 of U form in a peripheral groove 63 in upper piston seals the piston against the inner surface of cylinder 46.

Two vertical air passages 64 and 65 extend through piston 60 on opposite sides of the axial bore 61. Rethese passages are valve stems 66 and 67. The lower ends of the valve stems protrude attached to regulator 30 to the spray by the pump and delivered to a T cona drum,

3 below piston 60 where they are rigidly secured by nuts 70 to a valve carrier annulus 71.

The annulus 71 is held by the nuts 70 against flanges he flanges rest in shallow circular recesses 74 and 75 on the upper sur- The valve stems annulus 71 and valve carrier 80 compose valving unit 87 movable as one piece.

A spring 88 rests upon annular shoulder 89 within end air cylinder 46. When assembly 90, com- The supporting ring 42 at the top of the air motor is an eye bolt This seats O-ring valve 82 forces O-ring valve elements 76 and 77 away from their of th the cylindrical projection 103.

A cylindrical pump casing 108 is supported by the head member 102 to which it is threadedly joined over a ball check valve 130.

is slowly introduced to the air 87 in the position illustrated in Figure reach through holes the threaded connections between 108. The holes and the plugs and sleeve the flanged heads of the plugs and recesses in vertically 121 on the sleeve 116. The plugs have of a hexagon cross section so that an wrench may be used for screwing the said member is hollow to provide a chamber 129 for a A bushing 131 retains the valve in the chamber and has an axial passage 133 flaring at its upper end to serveas a seat for the check valve. A spring 134 inclines the valve to its seating position.

Between a shoulder end of member 128 a of the casing 108, derived sign, the bung hole need be no larger than two inches in diameter.

1 -The' air supply hose 20 is then connected to the inlet 21 of the air manifold formed in the wall of the coupling of coating material to the the valve 14 attached to knob of regulator 23. of air cylinder 46 from 64 and Y65 and thereby reaches above as well as below upper piston 60. This equal pressure on both sides of its action. This restricts the effective force of the air lower piston 49. 1

through passages foot valve 111 is then forced by the 147, of which plunger leather 138 is a wardly through passages his material is then stationary As this annular space has no more than half the capacity of the full cylin- 108 below plunger 147 the displaced material is forced to a height double its original The downward stroke of plunger 147 is terminated and its return upward initiated when the air valving unit 87 carried by upper air piston 60 strikes spring'88 and is .mil

tween vertically split portions crement of coating material drawn past areaees moved upwardl in respect to the iston. This inipels O-ring valve elements 76 and 77 to their seats on the underside of piston 60 interrupting the flow of air through passages 64 and 65 to the upper side of piston 60. At the same time the valve carrier plate 80 having raised away from piston 60, O-ring valve 82 has moved from its seat on annular ridge 84 permitting the compressed air above the piston to flow down axial bore 61 to the interior of piston 49. Thisair is vented to the atmosphere by traveling through the ported bushing 54 at the bottom of lower piston 49 and into the interior of casing 2 from which it escapes through the saw cuts be 98 and 1051 at the top and bottom respectively of the coupling casing 2. These separate restricted outlets from the interior hamber of the casting cooperate with the chamber in substantially silencing the staccato discharge of theexhaust air. With the compressed air above the upperpiston 60 thus dissipated the force of the compressed air is appliedonly to the underside of this piston. As the area of the upper piston 60 is slightly more than twice-that of the lower piston 49 the piston assembly 90 is then driven upwardly with at least the same power utilized in its downward thrust. In view of the weight and friction involved in the up stroke it is desirable that somewhat greater force be exerted in order that the net pumping power of the up and down strokes be approximately equal.

As the drive shaft 55 is pulled-upwardly another ininto the lowerportion of caslng 108 by the rising plunger 147.

The coating material of the firstincrement the plunger is impelled into; chamber".151 pump head member102 and hence into and T connection 9. At the start of the pump the spray gun is held open the coating material now above Within-the outlet nipple 153 the operation of in order that air in line from the container to the gun may be expelled. With the line thus unblocked the coating material advances from T connection 9 through regulator 12 and hose 15 to the gun.

The coating material discharge rate from the spray gun may be measured by letting the material flow unatomized, into a small container of known capacity and recording the filling time. As the discharge rate is proportional to the air pressure actuating the air motor it may be varied by adjustment of air regulator 23.

With the use of a single spray gun a fluid pressure regulator such as 12 is not ordinarily required. When two .or more spray guns are being supplied by the same pump some fluctuations in pressure may occur. These are usually not of sufficient magnitude to be objectionable in the application of waterproofing, structural and mill paints. However, when several spray guns are operating from a single pump and are utilized in high quality production finishing, maintenance of exact material pressure is important and the use of a regulator for each spray gun is advisable.

As piston assembly 9% reaches the limit of its up stroke the valving unit 87 is thrust downwardly in respect to the piston assembly by the meeting of spring 94 with the top of valve carrier plate 36. This restores the elements to the position presented in Figure 3 with O-ring valve 82 on its seat closing entry to the venting bore 61 and O- ring valve elements 76 and'77 depressed below their seats leaving passages 64 and 65 open. Again upper piston 64) has air on both sides and becomes ineffective and air pressure upon lower piston 49 forces the piston assembly and the drive shaft 55 downwardly for a start of the second pumping cycle. As long as coating material is being consumed the reciprocations of the air motor and pump elements automatically continue.

With cessation of the spraying operation the dead pressure of the coating material in the system instantly brings the pump to a stop as there is no space into which additional material may be forced and the material itself foot valve 111 to the open status reversal of the piston assembly ample dimensions of is practically rianasrnpressibie. At the time time the desiredpressu're is maintained on the coating material as Static air pressure under the selected regulated pressure continues to exert moving force'on the air piston assembly.

In the particular embodiment selected for illustration the net efiec'tive air istonarea 'is tw'ce' the net effec ti'v'e area of the pumping plunger 147 and the pump piston 124. Accordingly, if the air pressure admitted to the air motor is set at 'twentypounds, the coating mate'- rial is dispensed under a pressure approaching forty pounds. However, friction naturally diminishes the ratio when the material pressure is measured at the spray gun, particularly when long stretches of hose and hose of limited diameter are-involved.

Features of the invention it is wished to emphasize particularly include the valving mechanism ofthe air motor. The solid, integral valving unit 87 comprising the valve element carrier annulus 71, the valve stems 66 and 67, and the valve carrier plate 80, moves as one piece with no looseness between the parts. This assures no wearing contact between the elements and maintains their correct relative positions. It leaves no question in regard of O-ring valve 82 when o-ring' elements 76 and 77 are closed on the up stroke or of the reverse condition on the down stroke.

The shortdistance of travel of the valves eiiects quick 90 as it reaches the end Contributing to this fast action are the air passages 64 and 65 which perfiow of air to the top side of the upper of each stroke.

mit unimpeded ,jpiston'. Assisting the easy airflow are the. wide proportions of the valves and theirface g The valving unit is not only guided by the square cross contact with their seats.

sections of valy'e Stern' 66 and 67 wardly proieetingnip le Special importance is given the functions and structure of the coupling casting 2. Its cylindrical ends insertable in the air motor and pump unit, to which it is tied by easily removable cross bolts 97 and 104, assures axial but-also. byrt'heup- 57 on closure 56'.

alignment while also permitting quick disassembly. For

removal of the air motor the upper bolt 97 is withdrawn and the air motor is raised to expose the connection between shaft and lower air piston 49. Flats on adjoining areas of these parts are wrench engageable for unscrewing the connection.

The interior of casting 2 and the slots between the split portions 98 and in its side wall serve as a final path for the air exhausted from above the upper piston 60. The size of the chamber within the casting 2 and the two separate restricted slot outlets act to muiile the pulsating noise of the air exhaust. Built integrally in the casting is theair manifold 22 for distributing the supply of compressed air to operate the air motor and for atomizing the coating material discharged by the spray gun. An air line oiler should be placed in the air line to the air motor. This may be fastened directly to the air inlet of the air motor. While important from a practical standpoint, it is not considered an essential element of the invention.

While I have illustrated and described a single form of my invention, it is to be understood that various modifications, may be made therein without departing from the spirit of the invention and the range of the following claims.

What I claim is: I

1. In an air motor, a vertically reciprocable piston assembly, said assembly including an upper piston and a lower piston of reduced diameter attached to the upper piston, a vertically reciprocable valving unit carried by the upper piston and coaxial therewith, said valving unit including a valve carrier plate above the upper piston, a valve carrier annulus below the upper piston, and valve stems extending through the upper piston between the annulus and the plate and being rigidly attached to the annulus and plate, means supplying compressed air be- 4. -An air motor according to claim 1 in which there tween the upper piston and the lower piston, air passages are bearing surfaces in the air passages vertically guiding through the upper piston in which the valve stems recipthe valve stems of the rigid valving unit, and an axially rocate, valve elements on the annulus constructed to seat located nipple connection between the upper and lower around the lower ends of the passages, means forming an 5 pistons has vertically guiding contact with the axial bore air exhaust passage from the top side of the upper piston of the carrier annulus of the rigid valving unit axially down through the upper piston and the lower .An air motor having an upright cylinder, a piston piston, and a valve on the underside'of the plate disposed within t e cylinder adapted for vertical reciprocation, to close the inlet of the exhaust passage, and means movsaid piston having an axial bore, a tubular mounting ing the valve unit upwardly in respect to the piston ascasting for the air motor attached to the lower end of sembly to seat the valve elements carried by the annulus, the cylinder, said casting defining a large, generally enand to unseat the valve carried by the plate at the limit closed inner chamber, means providing an air exhaust of downward travel of the piston assembly, whereby, with passage from the cylinder to the chamber, said means inthe valve elements seated, the compressed air supplied cluding the axial bore of the piston, and means forming between the upper and lower pisto'ns acts on the upper a restricted outlet fro'm the chamber to the atmosphere,

limit of downward travel of the piston assembly and air leaving the cylinder. means moving the valving unit downwardly in respect to 6. An air motor according to claim 5 in which there the piston assembly to unseat the valve elements carried is an air supply line leading to the cylinder and an air y the n and seat the valve carried y the Plate manifold in the wall of the tubular casting constituting a at the limit of upward travel of the pistonassembly, portion f said i supply line,

compressed air to the upper side of the upper piston, the References Cited in the file of this patent compressed air supplied between the upper and lower UNITED STATES PATENTS pistons acts upon the lower piston to drive the piston assembly downwardly from the limit of upward travel of 1,115,704 Manes 3, 914 h piston assemb1y 1,941,222 Pew et al. Dec. 26, 19 33 2. An air motor according to claim 1 in which fiat 2,050,180 Davis V- 1 36 surfaces constitute the seats for the valve elements and 2,277,641 Hamel Mall 1942 the valve, and the latter are O-rings with due side only 2,578,102 P 6! 51 exposed to form an annular seating face. 2,672,101 Shlelds Mar. 16, 1954 3. An air motor according to claim 1 in which the FOREIGN PATENT 474,099 Great Britain Oct. 20, 1937

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