US2214683A - Hydraulic pump pulsation absorbing device - Google Patents

Description

2 Sheets-Shea? l INVIENTOR 61 o 0 o o 37 p 1940. F. J. SPANG 2,214,683

HYDRAULIC'PUMP PULSATION ABSORBING DEVICE Filed Feb. 6, 1939 2 Sheets-Sheet 2 Patented Sept. 10, 1940 rarest orrlcs HYDRAULIC PUMP PULSATION ABSORBING DEVICE v Ferdinand J. Spang, Butler, Pa.

Application February 6, 1939, Serial No. 254,849

4 Claims.

This invention relates to hydraulic pulsation absorbing devices and more particularly to de-' vices for absorbing the pulsations occasioned by hydraulic pumps operating under relatively high 5" pressures and used for the pumping of highly viscous fluids such as mud laden water used in the hydraulic method of rotary well drilling, and in the pumping of combustible fluids such as crude oil and its liquid derivatives.

In the rotary method of drilling wells, water is loaded with certain types or clay in a finely divided or colloidal'state in order to increase its lubricating value; the clay being in a colloidal state is buoyant resulting in a homogeneous mixture-of clay and water. This mixture becomes highly viscous as the load of clay increases, with the result that it resists flow and builds up considerable back pressure, due to changes in its course of travel's'uch as occur when passing through the valves of the pump, through strainers and around elbows and bends in the conveying line. The pistons of the reciprocating pump consequently tend to develop a considerable pressure differential between the peaks of their acceleration and deceleration movements.

This pressure differential results in a varied flow or pulsation which, with transference of the load from one piston to another, sets up a considerable vibration or hammering in the fluid conveying line. It also causes the torque of the pump crank shaft to fluctuate through a wide range with excessive peaks. It increases the tooth pressure on the gearing and on the main bearings as well ason the crank and connecting rod bearings and causes a wide variation in the stresses of the driving belts or chains.

A hydraulic pump working at low pressure and pumping fluid of low viscosity is readily leveled out or quieted'by the ordinary air chamber which 40 is used-with considerable success in compeneating for the variations in fluid flow due to piston movement, line friction, etc. However, the working pressures of a fluid and its viscosity are increased, the value of. the ordinary air chamber in effecting this leveling, rapidly decreases and the movement of the fluid column within such a chamberfbecomes so limited, that the pump delivery approaches that encountered with an uncushioned or solid fluid discharge column. Thus, for instance, a reciprocating pump having an air chamber oflOOO cubic inches capacity,

when operating at 117.6 pounds absolute pressure will have a working air capacity of cubic inches. If the movement of the piston causes a pressure pulsation of plus-10%, the

(01'. lids-+31) change in volume in the air chamberwill amount to about 11.5 cubic inches. That is, 11.5 cubic inches of fluid will have entered the air chamber during the period of plus pressure genera- 7 tion and will be discharged therefrom by the 5 air pressure and its consequent expansion during the pressure dropping pulsations. If the pump is of the conventional design used in well drilling, that is, a double acting two cylinder type of pump, this will amount to approximately 10 one third of one inch of pump piston travel.

- However, if the working pressure be increased to 614.? pounds absolute, the volume 01' the. effective air in the air chamber. will be. decreased to about 25 cubic inches. tion, the pulsations developed by the movement of the pistons causes an elevation of 10% in the pressure, the volume change within the air chamber will amount to only about 2.25 cubic inches or 3-,, of. an inch of pump piston travel; no 210- 20 count being taken of the viscous condition of the fluid.

It is, therefore, obvious that the ordinary air chamber is of little or no value at such pressures, especially when made of a size within the 25 physical, mechanical and practical limitations placed upon it by reason of field operations.

In addition to the above, it is a well known fact that where hydrocarbon fluids such as crude petroleum and its liquid derivative are pumped 30 under high pressure, or, where other fluids being 1 pumped contain even minute quantities of such fluids, the air within the air chamber is consumed by the chemical reaction which takes place when air and such hydrocarbon fluids are 35 confined together and under high pressure. From the above, it is apparent that the pump pulsations such as encountered in the rotary drilling of oil wells cannot be absorbed by the utilization of such an air chamber and that some 40 mechanical means is necessary.

I gamaware that various types of what might be called". mechanical shock absorbers have been su gested and made use of for absorbing the shock due to the sudden release or stoppage of 45 hydraulic fluids in the mechanical operation of hydraulic presses, hydraulic elevators and other similar devices. These shock absorbers however are intended for periodic operation only and because of their construction are entirely unsuit- 50 able for use as a pump pulsation absorbing device which must operate in sequence with each piston movement; frequently as often as times per minute.

An object of this invention is to produce an 55 If under this condi- 15 improved device for absorbing the hydraulic pulsations occasioned by a reciprocating pump, operating at relatively high pressures upon such materials as mud laden water used in the rotary method of well drilling and in the pumping of crude oil and its liquid derivatives.

Another object is to produce a device for absorbing hydraulic pump pulsations in which there is a considerable volumetric change in the receiving chamber as related to pump capacity and pulsation pressure change.

Another object is to produce an improved hydraulic pump pulsation absorbing device of the internally packed type.

A still further object is to produce an internally packed hydraulic pump pulsation absorbing device in which the cylinder within which such internal packing operates is readily removable and economically replaceable.

A still further object is to produce a device of this character in which the working parts are cooled and lubricated.

A still further object is to produce a device of this character which embodies a mechanical stop for so limiting the stroke of the piston of the device as to prevent damage to the yieldable pressure resisting means when the pump pressure exceeds a predetermined safety point.

A still further object is to produce a device of this character in which a spaced guide maintains, under all conditions, the piston and the yieldable pressure resisting elements in proper alignment with the cylinder within which the piston operates.

A still further object is to produce, in a device of this character, a combined air and hydraulic means for arresting the pistons travel whereby hammering of the piston is prevented when the device is being operated near its low pressure capacity.

A still further object is to produce a device of this character embodying a strainer for preventing foreign materials and pump parts from passing into the fluid conveying line.

A still further object is to produce a hydraulicv pulsation absorbing device which is simple in construction, economical to manufacture, readily reparable and efiicient in operation.

These, as well as other objects which will be apparent to those skilled in this particular art, I attain by means of the device described in the specification and illustrated in the drawings accompanying and forming part of this application and in which:

Figure 1 is a view in sectional elevation, of a device embodying this invention;

Fig. 2 is a top plan view of said device;

Fig. 3 is a side elevational view of the device of Fig. 1 looking toward the left side of said figure;

Fig. 4 is a perspective view of the piston assembly which enters into the make-up of the device;

Fig. 5 is a detail view in sectional elevation of said piston assembly;

Fig. 6 is a perspective view of the removable cylinder of the device;

Fig. '7 is a perspective View of the clamping ring used in. holding the removable cylinder in place; and

Fig. 8 is a perspective view of a modified form of removable cylinder which may be used in the device.

The pulsation absorbing device of this invention is provided with a housing separated into 1 lower and upper parts numbered H) and. I respectively, and which are provided with cooperating flanges l2 and I3 which by means of bolts M are secured tog-ether; a thin annular packing l5 being interposed between the adjacent faces of said flanges to prevent leakage.

Lower housing part I0 is so shaped as to in effect provide two connected chambers I6 and I1, and these chambers, constitute a fluid transmission chamber, which by means of inlet [8, is adapted to be placed in communication with the outlet of the reciprocating pump which produces the. pulsations to be absorbed; a flange!!! being provided; by means of which the device is to be secured to the valve chamber of said pump.

Chamber I6 at its opposite ends is provided with flanged openings to which flanges 20 and 2| are fitted and to which they are held in place by means of studs 22 and nuts 23. Leakage is prevented by means of gaskets 24-24.

Flange 2! is threaded as shown at 25 for connection to the fluid conveying line. Flange 20 is -bored out as at 26 to receive the end of a tubular strainer or screen 21. This flange is also threaded, as at 28, so that a safety valve can be connected to chamber [6 for the purpose of protecting the pump against damaging back pressures. Strainer or screenl 21 extends lengthwise of chamber 16 and terminates just short of flange 2| so that all fluid entering chamber M5 by way of inlet I8 has to pass through the strainer before passing to the line.

Chamber I! is cylindrical and near its top is provided with an inwardly extending annular flange 29 which forms a support shoulder for a removable cylinder 30. This cylinder is provided with an outwardly extending annular flange 3| which cooperates with flange 29 in supporting the removable cylinder in place; a gasket 32 being interposed between said flanges to prevent leakage.

Removable cylinder (which is open at both ends) is of such length that its bottom extends to the bottom. of chamber ll and its top 33 a distance above the top of upper part ill of the housing. This cylinder is preferably made of wear-resisting material and adjacent its top is provided with an external pulling groove 34 to which a hook or bar may be attached for the purpose of removing the cylinder when desired. The cylinder is. securely held in place by means of a clamping. ring 35 which is secured to flange ID by cap screws 36. Clamping ring 35 at its outer edge is provided with an upstanding annular flange 31 and interiorly of this with raised seats 38 for the heads of said cap screws.

The upper inner edge of annular flange 3'! is beveled'as shown at 39 and the outside diameter of said flange is less than the inside diameter of that part of housing part I! which surrounds the same; thus providing an annular space between the housing wall and said flange which leads to a drain opening 40, normally closed by a threaded plug 4|.

A piston which is mounted for reciprocation within cylinder 30 is yieldingly urged toward the outer end of said cylinder, therefore toward chamber l6, by a number of nested springs which are housed by the upper part II of the housing.

The piston properis numbered 42 and forms part of the unitary device of Figs. 4 and 5. This device, beside the piston proper, includes a piston carrier 43 and a sleeve 44 which connects the piston proper and said carrier. These parts are welded into a unitary structure by welds 45 and 46.

' ferential groove 58 and the inner wall of cylinder 39.

A'tubular guide rod 41 extends through/accutral: opening 48 in the top of piston carrier 45 and hasits'l'owe'r: end located within a recess '49 drill-ed for its reception in piston 42. Guide rod 41 fitstightly within said recess and is integrally connected to the piston carrier by a ring of inlaid weld metal 59 which is deposited within a groove formed by a beveled upper face "of the carrier "which surrounds the guide rod; The

guide rod is closed at its upper end by a screw threaded plug 52; The guide rod, when the pis-' ton assembly is in its lowermostv position, extends through a combined bearing and seal formed of- Babbitt or some other suitable metal located in the top of the housing. Welds. 45, 46 and 50 se'althe: points between piston 42, sleeve .44; piston carrier 43 and tubular guide rod: 41.

Sleeve'44 near'its lower end is provided with a series of fluid passages or holes 54 and in the same plane with these, a series of fluid passages or holes 55'are drilled through the tubular guide It will be seen that this construction provides two fluid and liquid-tight chambers above the level of said holes 54 and 55 within the unitary reciprocating device, comprising piston 42, piston carrier 43, sleeve rodj one numbered 56 and one numbered 51.

Piston 42, as shown in the drawings, is formed with an upper disk-like portion having a sliding fit within cylinder 30, and a downwardly dependingcentral portion, which near is bottom, is provided with. a circumferential groove 58. 7

'An annular packingmember 59 made from yieldable wear-resisting material, preferably rubber or rubber-like "material, surrounds the depending. central portion of the piston and is held in place'by a dished annularretaining member 59 'whichin'turn is held in place by a split retaining ring 6! which is snapped into circum- Retaining member 60 is of slightly less external diameter than packing member 55! and therefore, that portion of the low'erface of said packing member which extends beyond the outer periphery of the retaining member forms an annular lip 55a which is directly exposed to .the pressure of the fluid within chamber l5.

The outer peripheral surface of packing member 59 is of frusto-conical form and because of this an annular space 52 is provided between it This space decreasesv inwidth from the top of the packing member 59 to its bottom at which point the packing member 59 bears snugly against the inner surface of removable cylinder 30 and since lip 590. of the packing member is directly exposed to the hydraulic pressure, said pressure forces said lip into sealing engagement with the inner wall of cylinder at.

The piston carrier 43 is provided with a de pending annular flange 53, an upstanding annular flange 64 and a surface 55 which. connects the outer peripheral surfaces of said flanges and parallels surface 39 of flange 3'! of locking ring 35. Thelower flat surface 55 of the piston carrier (whenpiston42 is in its lowermost position) contacts with the top 35 of removable cylinder 3G. The top of cylinder 39 therefore serves as a limiting stop and determines the travel of the piston; assembly toward chamber I6. Cylinder 3!! at its top is notched as at 5m to provide a restricted passage for the'liquid which is trapped below the piston carrier as it approaches the limit of downward movement. As will be .1 seen 44 and the tubular guide from Fig. 1, when the piston carrier has reached its lowermost position, escape of liquid is also permitted through the space between the outer periphery of the piston carrier and upstanding flange 31 of locking ring 35. v

The outer diameter of flange 64 is made somewhat less than the internal diameter of the lower portion Ila of part i I of the housing in order to permit free flow of liquid past the piston carrier during its reciprocations.

The, upper face of the piston carrier interiorly of annular flange 64 is provided with annular spring seats 69, ill and H; the upper surface of weld metal 50 also serves as an additional spring seat. These seats as will be seen, are arranged in stepped relation and graduated in width to serve as supports for the lower ends of compression springs 12,13, 14 and 15.

The under surface of top llb of housing part H is provided with an annular seat 16 for the upper end of spring 12 and an annular seat 11 for the upper end of spring '13. An annular member 18 which is loosely mounted on tubular guide rod 51 is formed with a seat '59 for the upper end of spring 14 and a seat8ll for the upper end of spring 15. These opposed seats maintain the springs in'proper relative position.

The upward movementof the piston assembly is limited by an annular shoulder 8| located at the top of part i la of housing part H; a change in the diameter of the housing occurring at the part forming said shoulder.

Water fed into the housing through opening 82 and is discharged from the housing through oppositely positioned opening 83; these openings which are threaded to receive water inlet and discharge connecting lines thus determine the water level in the upper part I! of the housing, which part constitutes a water container and cover for the springs nested therein. This water serves to cool the springs which develop heat due to the alternating fibre stresses to which they are subjected during operation of the device and also lubricates and cools flexible packing element 58 and the upper portion of the removable cylinder 30. It will be apparent that when the device is at rest, the. space between the outer surface of flexible packing member 59 and the inner surface of cylinder 35 (above the lowermost edge or lip 59a of flexible packing member 59) is filled with water.

When the device is at rest, chambers 56 and 51, located respectively within sleeve 44 and tubular guide rod 4'! also contain water to a point slightly above the tops of openings 54 in said sleeve and 55 in said guide rod, thus trapping the air in said chambers 56 and 51.

As the piston assembly is moved upward b hydraulic pressure and against the stress of the nested springs (which form a yieldable movement-resisting device), water flows past the piston carrier. As the piston assembly is moved downward by the pressure of the springs, the piston carrier will move freely through the water until its flange 63 begins to pass the upper edge of flange 37. These flanges, in cooperation, act as a flow restrictor in that they restrict the flow of water between them. Further downward movement of the piston carrier forces part of the water over the top and part down into cylinder it. Some of this water passes through chamber 56 and into chamber 51 through openings 55 in the guide rod and compresses the trapped air in these two chambers. As the pressure of this til) trapped air increases, it restricts the flow of water and slows down the movement of the pitson carrier, with the result that the piston carrier tends to lose its momentum as it comes to rest on top of the cylinder 30 without hammering or injury to either member.

The water within housing part II does not interfere with movements of the piston carrier when its flange 63 is above flange 33 of the locking ring, but when flange 63 begins to movebelow the top of flange 37, movement of the piston carrier is effected by the water trapped below the same since its means of escape is restricted. The act of compressing the air within chambers 56 and 51 also assists in preventing any destructive hammering.

As the fluid being pumped enters chamber. I6 (which chamber as above pointed out serves as a transmission chamber between the pump and line) it exerts an upward pressure against piston 42, and exposed lip 59a of flexible packing 59 is tightly sealed against the inner wall of cylinder 3B. This upward pressure forces the piston and its carrier upward against the stress of the nested springs until the resistance of said springs equals the hydraulic fluid pressure. At this point of balance, the piston comes to rest. Any subsequent change in fluid pressure causes the piston to quickly moveto a new position of balance.

Thus, as each piston of the hydraulic pump approaches the end of its fluid flow accelerating stroke and the viscous fluid resists the acceleration due thereto, the pressure between the pump chamber and the outlet of chamber it; increases,

thus developing a greater force against piston 42. This results in a greater yielding of the nested springs, permitting the piston to move upward and this in turn increases the volume of fluid within chambers l6 and II.

After each piston passes its point of fluid flow acceleration the pressure between the valve of .the hydraulic pump chamber and the outlet to chamber l6 decreases, thuslessening the force against piston 42, with the result that the nested springs force piston 42 downward, thus compensating for the decrease in fluid flow due to present piston deceleration. The fluid, therefore, is expelled from chamber l6 into the fluid line at a fairly uniform rate. The uniformity of flow, however, is somewhat dependent upon the smooth operation of the pistons, valves and other elements of the hydraulic pump. It will be noted, however, that when one of the valves of the pump leaks or sticks, the shock due to the change of rate of fluid delivery, will be corrected, or evened out by movement of piston 42. Any shock to the pump elements, or the pump driving mechanism, as well as to the fluid feeding line will also be eliminated to aconsiderable degree.

Liquid entering space 62 from above collects there and as the piston moves upward, this liquid acts as a lubricant and helps the flexible packing to slide freely; the cylinder wall being not only lubricated but cooled by such liquid.

When the device is to be stored or when use thereof is to be discontinued, it is preferable, especially in cold climates, to drain the same. By removing plug 4|, and disconnecting the water inlet and outlet lines, the water may be drained from the spring cover or housing I I, and by attaching an air hose to the top of the tubular guide rod 4'! all of the water remaining within the device below drain opening 40 can be expelled through said drain opening. The water within chambers 56 and 51 is expelled through openings 54 and 55 in the walls of these chambers by way of the space between sleeve 44 and cylinder 30. able cylinder 30 permits this Water to pass into the space between anchoring ring 35 and the: piston carrier from which it is discharged by way of the annular opening or space between these members.

The upper part II of the housing is provided with opposed crane hooks 84 in order that the device may be lifted and shifted from one position to another by means of a crane.

In Figure 8, I have shown a modified form of removable cylinder and it will be seen that in this form, that portion of the cylinder which is exposed in chamber I! is provided with outwardly extending heat radiating ribs or fins 85. When this modified form of cylinder is used, the diameter of chamber l 1 will have to be increased and a slight change will have to be made in the housing part It! to accommodate annular flange 3 la of the cylinder which is of somewhat greater;

diameter than flange 3| of cylinder 30.

From the above, it will be seen that I have provided a removable or replaceable cylinder made of hardened wear-resisting material and a piston packing of semi-cup or self-sealing form which automatically sucks the lubricating fluid into place around it from its open or non-pressure end. ioning device'which will prevent hammering when operating near low pressure range and a limiting stop to prevent damage to the yieldable movement-resisting means. The tubular guide rod with its bearing in the top of the housing which is distintly located with relation to the piston keeps the piston assembly in alignment..

It will also be noted that I havefprovided water cooling for the yieldable movement-resistingv device as well as for the cylinder which generates It will also be seen that I provide a cush- Vent opening 30a. in the top of removconsiderable heat due to working friction between it and the yieldable piston packing.

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

1. In a' hydraulic pump pulsation absorbing device, a housing having a fluid transmission chamber therein adapted to be connected to the outlet of a reciprocating pump and a second chamber having an inlet and an outlet for cool-" ing liquid, a cylinder removablymounted within the housing and having its ends open to said 1 chambers, a piston mounted for reciprocation within said cylinder and carrying a yieldable packing expansible by the direct hydraulic pressure within said transmission chamber, a car-.

rier for said piston connected thereto and located within said second chamber, a guide rod rigidly connected to said piston and said carrier and extending through a bearing located in the top of said second chamber, a series of nested compression springs surrounding said guide rod for yieldingly resisting movement of said piston and. carrier away from said transmission chamber and means utilizing trapped liquid for retarding the movement of said piston'carrier as it ap-' proaches the limit of its stroke when moving toward said fluid transmission chamber.

2. In a device of the character described,a fluid transmission chamber, a spring chamber above said transmission chamber having a liquid inlet and a liquid outlet, and which serves as a reservoir for cooling liquid, a cylinder located be tween said chambers and in open communication therewith, a piston mounted for reciprocation within said cylinder and carrying a resilient expansible packing, and spring means within said spring chamber for urging said piston toward said fluid transmission chamber in opposition to the pressure of the fluid therein; said cylinder above said piston being in open communication with said spring chamber whereby liquid from said spring chamber keeps the inner cylinder wall and said packing continuously lubricated.

3. In a device of the character described, a fluid transmission chamber, a spring chamber above said transmission chamber having an inlet for liquid and an outlet and serving as a reservoir for cooling liquid, a cylinder connecting said chambers, a piston mounted for reciprocation within said cylinder and provided with an expansible packing, a spring support located within said spring chamber above said cylinder, connected to and movable with said piston and having a materially greater diameter than said piston, and a helical spring of materially greater diameter than said piston located within said spring chamber and between the top thereof and said spring support and adapted to urge said piston toward said transmission chamber against the fluid pressure therein; the construction and arrangement being such that liquid from said spring chamber flows into said cylinder and into contact with said packing whereby said packing is lubricated.

4. In a device of the character described, a fluid transmission chamber adapted to be connected to the outlet of a reciprocating pump, a spring chamber located above said transmission chamber, having a liquid inlet and a liquid outlet and serving as a reservoir for cooling liquid, a cylinder located between said chambers and having its ends open thereto, a piston mounted for reciprocation within said cylinder and carrying a packing of such form as to be expanded by direct hydraulic pressure within said transmission chamber, a spring support member located Within said spring chamber and of materially greater diameter than said cylinder, means connecting said piston and said spring support member whereby said piston and said member move in unison, and a helical spring located between theupper end of the spring chamber and said spring support member and having a materially greater diameter than said piston; the construction and arrangement being such that liquid from said spring chamber flows into said cylinder and into contact with said packing whereby said packing is lubricated.

FERDINAND J. SPANG.

- CERTIFICATE OF CORRECTION. Patent No. 2,214, 685. September 10, 191m.

' FERDINAND J. SPANG.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, line 52, for "near is" read --near its; page 14., second column, line 56, for "distintly" read -distantly and that the said Letters Patent should be read with this correction therein that the same ma conform to the record of the case in the Patent Office.

Signed and sealed this 15th day of October, A. D. 191w.

' Henry Van Arsdale, (Seal) Acting Commissioner of Patents.-

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