US2985359A - Hand pump - Google Patents

Description

HAND PUMP Abe J. Hanje, Northfield, Ohio, assignor to Robert H. Hunter, Gates Mills, Ohio Filed June 29, 1956, Ser. No. 594,935

1 Claim. (Cl. 230=-190) This invention relates to hand pumps of the type which are mounted in portable burners or torches for the purpose of maintaining the fuel in the tank or reservoir thereof under pressure. The present application is a continuation in part of co-pending application for patent on Instant Flame Torch, filed in the United States Patent Oflice September 23, 1954, Serial Number 457,803, which issued on June 14, 1960 as Patent Number 2,940,674.

Blow torches are commonly constructed with a tank of suitable volume for containing a quantity of fuel and air under pressure. Associated with this tank are the generator or fuel vaporizer, nozzle, valve and burning tube or other means for producing the flame from fuel delivered from the tank under pressure. The hand pump for maintaining air in the fuel tank at the desired pressure may be removably mounted in the filler opening of the tank and in such case the pump preferably is in the form of a unitary structure.

It has been the custom to construct the hand pump with an elongated cylindrical body in which is slideably mounted a manually operated plunger or piston for forcing air under pressure on the down stroke pasta check valve positioned in the air discharge conduit of the pump. The piston of a pump of this type should be provided with suitable packing means for sealing the joint between the side wall of the pump cylinder and the piston. Considerable difficulty has been experienced in constructing the pump piston with a sealing element which eflfectively seals the joint between the piston and the cylinder wall of the pump under all conditions.

Accordingly the principal object of the present invention is to provide a new and improved hand pump of the above type in which the pump piston has a sealing element fioatingly mounted on the main body of this piston and so arranged as to maintain a tight seal between the piston and the wall of the pump cylinder.

Another object of the present invention is to provide a new and improved pump of the above type in which the pump constitutes a closure for the filler opening of a container and has a piston operating handle which forms a hand hold adapted to be operated inone direction to unscrew or otherwise detach the pump from the container and in the other direction to screw or otherwise attach the pump thereto.

Another object of the invention is to provide a new and improved sealing element for the piston of a hand pump.

Another object is to provide a pump piston and sealing element combination in which the sealing element is held captive in an annular groove or channel formed in the piston periphery and shifts axially during the working of the piston in the pump cylinder so as to move into and out of sealing engagement alternately with the opposed walls of the channel, the piston being also formed with passages which allow air to by-pass the sealing element when the latter is in sealing engagement with one of the walls of the channel.

Patented May 23, 1961 iee According to the invention, the sealing element is a molded ring of synthetic plastic material having an L- shaped or V-shaped radial section, the plastic being of the polyethylene type, or polytetrafiuoroethylene, capable of returning to its molded shape relatively slowly compared to rubber after being deformed and having substantially constant physical characteristics over a wide temperature range so that the pump can be used effectively in a torch where the pump is actuated at temperatures as low as -60 F. on starting in the Arctic and as high as about F. during operation in the desert. As a further feature, the plastic sealing element of the character mentioned is waxy orself-lubricating, thus minimizing friction between the piston and the cylinder wall, this being another objective of the invention.

A further object of the invention is to provide a new and improved hand pump of the above type which is simple in construction and reliable and eflicient in operation.

With the foregoing and other objects and advantages in view, the invention consists in the preferred construction and arrangement of the several parts which will be hereinafter fully described and claimed.

For a clearer understanding of the invention and the objects thereof, reference is made to the accompanying drawings. These drawings when used in conjunction with the following description serve to illustrate the invention, its principles and the operation thereof, while the claim indicates the scope thereof.

In the drawings:

Fig. 1 is a fragmentary vertical longitudinal section through a tank such as the sheet metal fuel reservoir of a blow torch showing mounted therein, also in longitudinal section, an air pump constructed in accordance with the present invention, parts being shown in elevation; and 7 Figs. 2, 3 and 4 are enlarged fragmentary vertical sections of the pump piston of Fig. 1 showing the seal. arrangement therefor in various positions.

According to the present invention the new and improved air pump may comprise a cylindrical casing 221 adapted to be arranged coaxially with a filler tube 223 depending into a tank 224.

The upper end of the filler tube 223 is provided with a bushing 225 internally threaded to receive an externally threaded .collar 226 soldered or otherwise hermetically fastened around the pump casing 221 near its upper end.

The collar 226 is provided with an annular groove 227 in which is mounted a gasket 228 arranged to contact a seat 229 formed on the bushing 225 and thereby seal the joint between the pump casing 221 and the filler tube 223.

. The collar 226 should be mounted on the casing 221 near its upper end so that the lower end of the pump will be disposed in suitable spaced relation above the bottom 230 of the tank 224.

The cylindrical casing 221 is closed at its upper end by a circular disk 231 suitably secured in place and having a central square or other non-circular aperture 232 therethrough accommodating a correspondingly shaped piston rod 233 having an operating handle 234 fixed to its upper end.

Breather holes 235 through the top disc 231 or clearance around the piston rod 233 allow air to enter the chamber 236 within the casing 221 above the plunger or piston 237, mounted on the lower threaded portion of the rod 233. a

The piston 237 is formed of a pair of separate'members, including an upper circular disc 238 threadedly mounted on the rod 233, and a lower circular disc 239 having an upstanding hub 240 threadedly mounted on 3 the rod 233, the upper end of said hub bearing against the underside of the upper disc 23% to thereby maintain the two discs in predetermined spaced apart relationship. A jamnut 2 41 mounted on the rod 233 above the upper disc 238 and turned down tight thereagainst,

tact with the wall of the pump cylinder during reciprocatory movements of the piston therein.

On the other hand the diameter of the lower piston disc 239 is considerably less than the diameter of the upper disc 238 so that'its periphery 243 is spaced a considerable distance from the cylindrical wall of the pump in the provision of an annular clearance space that accommodates the skirt of the sealing element.

The construction and arrangement of the parts is such that the piston 237 is formed with an annular groove of considerable area to provide a channel 244 having a substantially vertically disposed inner annular wall 245 and opposed upper and lower walls 246 and 247 which extend outwardly from the inner wall 245 to the outer peripheral edges 242 and 243 respectively of the piston body.

The walls 245, 246 and 247 of the channel 244 thus define an annular space of rectangular cross section. It will also be noted that the construction and arrangement of the parts of the piston 23-7 is such that the piston includes an intermediate cylindrical portion defined by the hub 24' and rims at each end defined by the upper and lower discs 238 and 239.

A sealing element 251 in the form of a cup washer which is angle shaped in radial section is mounted on the piston 237 between the upper disc 238 and the lower disc 239. The sealing element 251 is provided centrally there- 'of with a circular opening 252 which receives the hub 240.

The opening 252 has a diameter greater than the diameter of the hub 240 to provide an annular clearance or passage for air and so that'the sealing element 251'is freely movable lengthwise of said hub from a position in which the main body of said sealing element bears against the underside of the upper disc 238' when the piston 237 is moving down in the manner shown in Fig. 2, to another position in which the main body of the sealing element bears against the upper side of the lower disc 239 when the piston 237 is moving up in the manner shown in Fig. 3.

The periphery of the element 251 is provided with a downturned circular .flange 253 which provides an annular surface arranged to bear yieldingly against the wall 'of the pump casing 221 to seal the joint between the piston and said casing.

The lower disc 239 is provided with a plurality of holes and passages 254.

The sealing element 251 through its axial shifting in the channel 244 with the up and down reciprocatory movements of the piston 237, operates as a valve. During downward movements of the piston 237 as represented in Fig. 2, the sealing element 251 rests sealingly against the wall 246 of the upper disc 2'38 and its flange 253 also makes an effective completely circular seal with the wall of the pump casing 221. Thus downward movement of the piston compresses air below it in the chamber 255 of the pump.

During upward movement of the piston 237, the sealing element 251 rests against the lower disc 239. A by-pass is thus opened through the holes and passages 254, the annular clearance space around the hub 240, which is in communication with said holes and passages in the manner shown in Fig. 3, and the clearancebetween the periphery of the upper disc 238 and the inside wall of the pump casing 221. A fresh charge of air'may thus flow down into the chamber 255 below the piston 237 from the chamber 236 above the piston which is in communication with the atmosphere through the ports provided by the breather holes 235 in the top 231.

A coiled helical spring 256 may be provided in the piston chamber 236 for the purpose of cushioning the upward movements of the piston 237 within the pump casing 221. The spring 256 encircles the piston rod 233 and is of relatively short length. Normally the spring 256 has one end resting on the top of the piston 237. When the piston is in the lower portion of the pump casing 221 as shown in Fig. 1, the upper end of'the spring 256 will be spaced a considerable distance from the top 231 of the pump. When the piston 237 is moved upwardly the spring 256 willbe carried upwardly by the piston until the upper end of the spring contacts the underside of the top 23-1, whereupon the spring will be compressed and the upward movement of the piston within the pump casing .221 will be arrested.

Preferably the sealing element 251 should be made of one of the well-known'synthetic plastic materials 'of'the type characterized by having a memory; that is to say, a material which when deformed from its molded or normally unstressed shape recovers such shape relatively slowly as compared to rubber and like elastomers. A suitable material, for example, is a plastic having a surface which feels waxy to the touch like polytetrafluoroethylene, which in addition to its other characteristics provides a self-lubricating sealing element.

Since the sealing element recovers its shape very slowly the present invention provides an arrangement which allows the sealing element 251 to expand to such shape during periods of rest or inactivity. In its normal or unstressed molded shape (Fig. 4) the sealing element 251 has an outside diameter slightly in excess of the diameter of the internal cylindrical surface of the pump casing 221, so that the sealing element 251 is snugly embraced by the cylindrical wall of the casing 221 during the working of the pump. A suitable differential of diameters is about inch in a pump having an internal casing diameter of approximately one inch.

The lower portion ofthe side wall of the pump casing 221 is tapered or flared outwardly,as indicated at257, Figs. 1 and 4, so that the lower end of said casing has an internal diameter somewhat greater than the diameter of the main body of the casing or is otherwise provided with an increased diameter normalizing chamber portion to receive the sealing element when the pump is inactive.

The bottom of the pump casing 221 has a closure 261 provided with a discharge opening 262, threaded to receive a tubular extension 263 in which is fitted a one-way valve device 264 of conventional construction, such as an outwardly opening ball check arranged to allow flow from the lower piston chamber 255 into the tank 224, but to prevent reverse flow.

The outlet end of the tubular extension 26 3 has-a tube 265 connected thereto, said tube extending upwardly, into the tank 224 and terminating at a point considerably above the level of fuel therein indicated by the broken lines 266 in Fig. 1. Thisarrangement eliminates the pos .sibility of fuel being driven back into the pump in the event that a leak should develop at the valve 264, since the tube 265 will conduct air back into the pump rather than fuel. Thus the possibility of contamination of the sealing element 251 with fuel and likewise the possibility of fuel being driven out of the tank through the pump are eliminated.

The normal unstressed contour of the sealing element 251 is shown in Fig. 4 wherein it will be noted that the peripheral flange 253 thereof extends outwardly at an oblique angle with respect'to the main body of the sealing element. Due to the physical characteristics of the synthetic material used in constructing the sealing element 251 when the piston 237 is operated in an upward direction from the lower'end of the pump casing 221, since the lower peripheral edgeof the sealing element'251 has a diameter greater than the internal diameter of .the casing 221 a considerable drag will occur, so that the sealing element 251 shifts downwardly from its contact with the underside of the upper piston disc 238 to contact with the upper side of the lower piston disc 239. Continued upward travel of the piston 237 within the pump casing 221 causes the peripheral flange 253 to be contracted and to assume the position shown in Fig. 3 in which a continuous line contact seal is effected with the wall of the pump casing 221. Thus, due to the tendency of the sealing element material to assume the larger diameter which it has in its normal unstressed condition, said sealing element will effectively seal the joint between the piston 237 and the wall of the pump casing 221 during operation of the pump.

When the pump piston has been in operation to supply air under pressure to the tank 224, the pumping action is terminated with the pump positioned in the bottom of the casing 221. Fig. 1 shows the sealing element after pumping action with its periphery not yet expanded to its normal full diameter. Since the sealing element 251 recovers its shape very slowly, when the piston 237 first enters the enlarged lower portion of the chamber 255, the periphery 253' of said sealing element may be spaced from the casing wall in the manner shown in Fig. 1. The reason for positioning the piston in the lower end of the pump casing during periods of inactivity is to allow the sealing element 251 to expand to its normal unstressed shape, Fig. 4. In this way an increased sealing action can be provided between the piston and the wall of the casing 221 by allowing the sealing element to recover or normalize during periods of rest or inactivity of the pump. The efliciency of the device is thereby increased.

It has been found in actual practice that synthetic plastic materials of the character herein referred to increase the life of the pump to a marked degree, since the wearing properties of such materials are considerably greater than those of other materials heretofore used as piston packings for similar use. Since such synthetics are relatively inert to and unaffected by the hydrocarbon liquid fuels commonly used in blow torches, the present invention is especially useful in pumps for such devices.

The air pump features herein described are especially designed to form parts of burners or torches for liquid hydrocarbon fuels adapted to be used in extremely cold climates, such as Arctic regions where the operators must wear gloves and other protective coverings when out of doors. For this reason the air pump should be capable of being readily detached from the burner tank for filling of the latter and then applied thereto by an operator having gloved hands. With this in mind, the piston rod is formed of square bar stock so as to be non-rotatable with respect to the pump casing, and a relatively large operating handle or knob 234 is fixedly mounted on the outer end of the piston rod to provide a readily accessible hand hold by which the pump can be quickly turned as a unit to either unscrew it from the tank of the burner or screw it into the burner tank. It will be understood that since the piston rod is square for substantially its entire length, the pump can be removed from the burner or applied thereto when the piston is in any position within the pump casing.

From the foregoing, it will be seen that the present invention provides a new and improved hand pump for portable burners or torches. The pump is readily adapted for use with burners or torches of difierent sizes and shapes. The invention disclosed will adequately accomplish the functions for which it has been designed and in an economical manner and its simplicity, accuracy and ease of operation are such as to provide a relatively inexpensive device considering what it will accomplish.

What I claim and desire to secure by Letters Patent of the United States of America is:

In a reciprocating pump, elongated tubular casing means having an internal wall of circular section includ- 6 ing a cylindrically surfaced main wall portion defining a relatively long working chamber and at one end of the latter an outwardly flared tapered surface wall portion defining a relatively short expansion chamber of circular section, the expansion chamber being continuous, axially aligned with, and of generally greater diameter than the main working chamber, a rod and means guiding the rod in the casing for axial reciprocation, a piston assembly on the rod for actuation thereby, the piston assembly comprising a body having an upper circular disc of slightly less diameter than said main wall and, axially spaced therefrom in the provision of an annular groove open toward the casing wall, a lower circular disc of considerably less diameter than the upper disc, an annular sealing element disposed in said groove and about the piston body, said sealing element being of synthetic plastic material having a memory such that it returns slowly by inherent resiliency to its normal shape upon being re leased after deformation, said sealing element in its unstressed condition being generally cup shaped and having a circular peripheral edge of greater diameter than the cylindrical main wall portion, the casing means including a closure at its distal end constituting a stop limiting the pumping stroke of the rod and piston assembly, the rod being adapted to move the piston assembly toward and into the expansion chamber across the curved surface of the connecting wall portion at the end of a pumping stroke to position the periphery of the plastic sealing element in the expansion chamber in unconfined condition by reason of the greater diameter of the expansion chamber relative to the main working chamber, the axial thickness of the sealing element being less than the axial dimension of the annular groove of the piston body to permit axial shifting of such element on and relative to the body, the permitted shifting of the sealing element being greater than the clearance between such element and the casing closure at the pumping stroke limit to permit the sealing element to bottom against such closure, the periphery of the unconfined sealing element expanding solely through inherent resiliency of such sealing element from the diameter to which the periphery is confined in movement of the piston assembly through the working chamber to a diameter greater than that of the working chamber, the sealing element being of shape retaining stiffness and formed with a central opening, the wall of such opening being separated from the piston body by an annular clearance permitting relative lateral shifting of such element and being located laterally in the casing substantially solely by engagement between the sealing element periphery and the casing expansion chamber wall surface, the rod, at the beginning of a suction stroke, being adapted by engagement of the lower disc against the sealing element to draw the latter from the expansion chamber into the working chamber with the piston body being centered in the working chamber by the upper disc and the sealing element being centered in such chamber independently of the body by peripheral engagement of the sealing element against the casing wall, and the lower disc supporting the sealing element against axial deformation during a suction stroke over "a circular area considerably less in diameter than the circular area of support provided for the sealing element by the upper disc during a working stroke to distribute deformation of the sealing element during such suction stroke centering thereof.

References Cited in the file of this patent UNITED STATES PATENTS 686,939 Horn Nov. 19, 1901 1,178,122 Andrews Apr. 4, 1916 1,2A5,165 Tharp et a1 Nov. 6, 1917 1,376,863 Drew May 3, 1921 1,379,492 Wagner May 24, 1921 1,431,355 Andrews Oct. 10, 1922 (Other references on following page) I UNITED STATES PATENTS Wepplo May 7, 1929 Brown Nov. 1,1932 Seyforth Sept. 17, 1935 Brandt Jan.3,1939 5 De Frees July 8,1941 Huthsing Sept. 23, 1941 Byers et a1 July 17, 1951 Hudson et a1 May'14, 1957 Anderson Sept. 23, 1958 FOREIGN PATENTS Germany May 31, 1929 France Aug. 7, 1924 France Ian. 21, 1953

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