US2548807A

US2548807A - Pneumatic type pulsator

Info

Publication number: US2548807A
Application number: US756260A
Authority: US
Inventors: Morgan Myles; Nicholas T Werthessen
Original assignee: Worcester Foundation for Biomedical Research
Current assignee: Worcester Foundation for Biomedical Research
Priority date: 1947-06-21
Filing date: 1947-06-21
Publication date: 1951-04-10
Anticipated expiration: 1968-04-10

Description

April 1951 M. MORGAN ET AL 2,548,807

PNEUMATIC TYPE PULSATOR' Filed June 21, 1947 2 Sheets-Sheet l Compressed 67 7 4/ Air IN VEN TORS MYLES MORGAN NICHOLAS .7. M ERrHEssE/v ATTORNE April 1951 M. MORGAN ETAL 2,548,807

PNEUMATIC TYPE PULSATOR Filed June 21, 1947 I 2 Sheets-Sheet 2 [NI-"EN TORS NYLEs MORGAN Ngcg HoLas 77 WERTHESSEN ATTOfF/V Patented Apr. 10, 1951 PNEUMATIC TYPE PULSATOR Myles Morgan, Worcester, and Nicholas T. Werthessen, Sherborn, Mass, assignors to Worcester Foundation for Experimental Biology, Shrewsbury, Mass., a corporation of Massachusetts Application June 21, 1947, Serial No. 756,260

Claims. 1

This invention relates to pulsators, and more particularly to apparatus for supplying a pulsating gas pressure to the surface of a liquid within a surge chamber, so that the liquid may be pumped in a desired manner.

Very difiicult problems are involved in the construction of pumps for use with certain liquids.

For example, corrosive liquids may attack metal parts and greatly reduce their useful life. Liquids which carry abrasive particles in suspension may cause excessive wear on the parts of the pump. Still other liquids must be maintained in a sterile condition and hence must be prevented from coming contact with unsterilized parts. Furthermore, in many cases it is important to adjust and control the pressure of the liquid delivered by the pump and the rate of liquid flow, and this requirement greatly complicates the problem.

It is accordingly one object of the invention to provide a comparatively simple, inexpensive and dependable pulsator which will be capable of supplying a pulsating gas pressure of desired characteristics for use in pumping certain liquids of a difficult nature, such as corrosive liquids, abrasive-bearing liquids, or sterile liquids.

It is a further object of the invention to provide a pulsator for use as part of a liquid-pumping apparatus and so constructed that not only the pressure of the liquid delivered but also the rate of the liquid flow can be readily adjusted and controlled.

With these and other objects in view, as will be apparant to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawing illustrating one embodiment of the invention, and in which like reference numerals indicate like parts,

Fig. l is an elevation of a pumping apparatus, with certain parts broken away for clearness of illustration;

Fig. 2 is a section taken-on the line 2-2 of Fi Fig. 3 is a section taken on the line 33 of Fi Fig. 4 is a section taken on the line 4- of Fig. 1;

Fig. 5 is an enlarged sectional view of a valve forming a part of the apparatus shown in Fig. 1; and

Fig. 6. is a fragmentary view similar to Fig. 1 bu showing a modified construction.

Referring now to Fig. 1, the embodiment illustrated comprises a suction or supply pipe it leading to a check valve II having a valve member l2, a connecting pipe I4 leading from the check valve I l to a second check valve l5 having a valve member I6, and a pressure or delivery pipe 18 leading from the check valve IE to a place of use or delivery. Each of these check valves will open to permit upward flow of liquid therethrough, and close to prevent downward flow of liquid therethrough. The two check valves are connected in series by the intermediate pipe it which in turn is connected by a branch pipe it to a surge chamber 2%. These various'parts are made of a material suitable for use with the particular liquid to be handled. In many cases they may; be made of glass. This will withstand contact with most liquids, it can readily be sterilized if necessary, and because of its transparency it permits the operator to ascertain by visual inspection the quantity of liquid in the surge chamber 2| In order to bring-about the'desired flow of liquid from the supply pipe It to the delivery pipe l8, there is provided apulsator which is constructed and arranged alternately to increase and to decrease the pressure effective on the liquid within the surge chamber 29. For this purpose there is provided an expansible chamber com prising an upright cylinder 22 and a conduit 23 connecting the lower end of the cylinder to the chamber 28. Trunnions 24 project from opposite sides of the cylinder and are carried in a bracket 26 which is vertically slidable in a guideway 21 formed on a frame member 28.. This frame member also carries a bearing 38- for a vertical screw 3! which is threaded through the bracket 26. lower end of the screw so that the screw may be easily rotated to adjust the bracket 25 and the cylinder zzvertically. The conduit '23 is preferably made of rubber or other flexible materialin order to permit movement ofthe cylinder;

cylinder, the conduit 23 and the chamber 20." This is brought about by meansof a generally horizontal lever 31 one end of which is pivotally connected by a pin 33 to a pair of blocks 39, these blocks being slidable in vertical guide slots Al formed in the frame member 28. The upper end of the piston rod 35 is pivotally connected to.

A crank 32 is mounted on. the

A T piston 34 is provided withinthe cylinder 22, and a piston rod 35 extends upwardly from the piston the lever 31, near the pin 38, by means of a pin 42. The other end of the lever is pivotally connected by means of a pin 43 to the upper end of a rod 45. The lower end of this rod is attached to the crank pin 46 of a crank shaft 41, this shaft being supported in a bearing 48 and rotated at a desired speed by suitable motor or other means (not shown). The lever 31 is provided intermediate its length with a longitudinally extending slot 50 having a block slidable therein. This block is pivotally supported on a pin 52 carried by a bracket 54, and the bracket is slidably mounted in a horizontal guideway 55 formed by a frame member 56. This frame member car ries a bearing 58 for a horizontal screw 59 which is threaded through the bracket 54. A crank 69 is mounted on one end of the screw 59 so that the screw can be easily rotated to adjust the bracket 54 and the pin 52 horizontally. The pin 52 forms a fulcrum for the lever, and by adjusting the position of this fulcrum the operator may vary the length of the stroke of the piston 34.

The operation of the apparatus as so far described will now be apparent. The revolving crank shaft 41, acting through the rod 45, will rock the lever 31 about its fulcrum 52, thus alternately raising and lowering the piston 34. At each downward stroke of the piston, the air confined within the lower portion of the cylinder 22, the conduit 23, and the chamber 20 will be compressed, thereby increasing the pressure on the liquid within the chamber 20. Consequently some of the liquid will be forced upwardly through the check valve l5 and the delivery pipe l8, while the check valve H remains closed. At each upward stroke of the piston, the volume of the confined air will be increased until a sub-atmospheric pressure or partial vacuum is obtained, whereupon liquid will be drawn upwardly through the supply pipe Ill and the check valve ll into the chamber 20, while the check valve l5 remains closed. Thus there will be a pulsating flow of liquid upwardly through the pipes l 0 and I8, and none of this liquid will come into contact with the cylinder 22 or the piston 34. By turning the crank 32 the operator can raise or lower the cylinder 22, thereby varying the distance between the lower end of the cylinder and the piston without changing the length of the piston stroke. By turning the crank 60 he can vary the length of the piston stroke without changing the position of the cylinder. These two adjustments make it possible for the operator to obtain any desired combination of vacuum and pressure, as may be required to match the resistance to liquid flow in the pipes in and 18, thereby preventing appreciable variations in the quantity or level of liquid in the chamber 20.

There will ordinarily be a slight leakage of air upwardly past the piston 34 as it approaches its lower limit of travel, which will tend to reduce the weight of the air being acted upon by the piston and to change the pressure conditions throughout the cycle. In order to prevent any such change, we provide means to admit additional air to the cylinder automatically in the amounts required to make up for leakage and to maintain predetermined pressure conditions. Two arrangements of apparatus for accomplishing this result are shown and will now be described. 1

In Fig. 1 there is illustrated a conduit 62 which leads from a suitable supply of compressed air to the lower end of the cylinder 22, a portion 63 of this conduit being constructed of rubber or other flexible material to permit movement of the cylinder. Along the conduit 62, and in the order mentioned with relation to the direction of flow, there are provided a shut-ofi valve 65, a pressure reducing and regulating valve 66, a branch provided with a shut-off valve 61, a branch provided with a pressure gauge 69, a shut-off valve 10, and a make-up valve ll. As shown in Fig. 5, the make-up valve H comprises a poppet-type valve member 73 having a stem 14 which extends downwardly through a stuffing box 15 and carries a button H on its lower end. A coiled compression spring 18 biases the valve member 13 toward its closed position. As indicated in Fig. 1, this makeup valve H is located directly above the lever 31 and in such a position that the right hand end of the lever will strike the button 11 and open the valve for an instant as this end of the lever reaches its uppermost position. At this time the piston 34 will be at its lowermost position, and the air within the cylinder 22 will be at its maximum pressure. Normally, the valve 55 and III will be open, and the valve 61 will be closed. The regulating valve 66 will be adjusted to maintain an air pressure anterior to the make-up valve ll corresponding to the pressure desired within the cylinder 22 when the piston reaches the end of its downward or compression stroke. Consequently, if any air has escaped past the piston, the valve H will admit just enough air at each cycle to make up for this loss. The valve 61 is used merely to allow some air to escape from the conduit 62 as may be necessary or desirable when adjusting the regulating valve 65 for the required pressure. The pressure will of course be indicated by the gauge 69.

In Fig. 6 there is shown a modified construction for supplying make-up air to the cylinder 22. In this embodiment there is provided a Marriot tube comprising a vertically elongated receptacle 80, preferably of glass, containing a body 8| of water or other suitable liquid and closed at its upper end by a rubber stopper 82. A tube 84 extends downwardly through the stopper and into the water 8|, the upper end of this tube being open to the atmosphere. A tube 85 extends downwardly through the stopper and into the air space above the surface of the water 8|, the outer end of this tube being connected through a check valve 81 and a conduit 83 to the lower end of the cylinder 22. The check valve includes a valve member 89 which will close automatically to prevent air flow in a direction toward the receptacle 8%. The conduit 88 is formed of rubber or other flexible material to permit movements of the cylinder. Water may be added to the receptacle from an elevated tank 9| which is connected to the lower end of the receptacle by a rubber tube 92 provided with a shut-01f clamp 93, and water may be withdrawn from the receptacle through a rubber tube 94 provided with a shut-off clamp 95. The height of the water BI above the lower end of the tube 84 should be such as'to create a pressure head which will correspond to the degree of vacuum desired in the cylinder 22 when the piston reaches the top of its stroke. If any leakage occurs upwardly past the piston 34 during the pressure part of the cycle, this will reduce the weight of the air within the cylinder and thereby tend to increase the vacuum which will be attained as the piston reaches the top of its stroke. In such case however, upon even the slightest increase in this vacuum beyond the desired value, air will flow through the tube 84, upwardly through the body of water BI, and thence through the check valve 81 and the conduit 88 to the cylinder 22 to replace the air which has escaped. During the pressure portion of each cycle, the check valve 81 will prevent reverse flow of air.

It will be apparent that the invention provides a relatively simple pulsator which is capable of supplying a pulsating gas pressure and controlling the maximum and minimum values of such pressure in a far more satisfactory manner than any mechanism heretofore known.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

1. An apparatus for supplying a pulsating gas pressure to the surface of liquid within a surge chamber connected to a conduit intermediate two check valves, the said apparatus comprising two relatively reciprocable elements forming an expansible chamber containinggas, means to reciprocate one of said elements relative to the other element and thus alternately compress and expand the gas, means to adjust the length of stroke of the reciprocating element, and independently operable means to effeet a relative adjustment in the positions of the said other element and the path of the reciprocating element.

2. An apparatus for supplying a pulsating gas pressure to the surface of liquid within a surge chamber connected to a conduit intermediate two check valves, the said apparatus comprising two relatively reciprocable elements forming an expansible chamber containing gas, means to reciprocate one of said elements relative to the other element and thus alternately compress and expand the gas, means to adjust the length of stroke of the reciprocating element, and independently operable means to effect an adjustment in the position of the said other element and thereby vary its position relative to the path of the reciprocating element.

3. An apparatus for supplying a pulsating gas pressure to the surface of liquid within a surge chamber connected to a conduit intermediate two check valves, the said apparatus comprising a cylinder containing gas, a piston reciprocable in the cylinder, means to reciprocate the piston and thus alternately compress and expand the gas, means to adjust the length of stroke of the piston, and independently operable means to adjust the position of the cylinder relative to the path of the piston.

4. An apparatus for supplying a pulsating gas pressure to the surface of liquid within a surge chamber connected to a conduit intermediate two check valves, the said apparatus comprising two relatively reciprocable elements forming an expansible chamber containing gas, a lever, a fulcrum for the lever, means to rock the lever about the fulcrum, means connecting the lever to one of the said elements to reciprocate the same relatively to the other element and thus alternately compress and expand the gas, means to adjust the position of the fulcrum along the lever and thereby change the length of stroke of the reciprocating element, and independently operable means to adjust the position of the said other element relative to the path of the reciprocating element.

5. An apparatus for supplying a pulsating gas pressure to the surface of liquid within a surge chamber connected to a conduit intermediate two check valves, the said apparatus comprising a cylinder containing gas, a piston reciprocable in the cylinder, a lever, a fulcrum for the lever, means to rock the lever about the fulcrum, guide means to prevent longitudinal movement of the lever, a rod connecting the lever to the piston to reciprocate the same and thus alternately compress and expand the gas, means to adjust the position of the fulcrum along the lever and thereby change the length of stroke of the piston, and independently operable means to adjust the position of the cylinder in a direction longitudinal thereof.

MYLES MORGAN. NICHOLAS T. WERTHESSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 558,766 Blood Apr. 21, 1896 1,025,554 Williams May 7,1912 1,408,440 Burton Mar. 7, 1922 1,686,109 Stuckey Oct. 2, 1928 1,998,616 Hamilton Apr. 23, 1935 2,254,539 Mattox Sept. 2, 1941 2,398,520 Clements Apr. 16, 1946 2,437,821 Hughes Mar. 16, 1948 FOREIGN PATENTS Number Country Date 12,523 Great Britain May 21, 1914