US2966895A

US2966895A - Control valves for fluid actuated pumps

Info

Publication number: US2966895A
Application number: US788983A
Authority: US
Inventors: Roy H Deitrickson
Original assignee: Nat Supply Co
Current assignee: National Supply Co
Priority date: 1959-01-26
Filing date: 1959-01-26
Publication date: 1961-01-03
Anticipated expiration: 1978-01-03

Description

Jan. 3, 1961 R. H. DEITRICKSON 2,966,895

CONTROL VALVES FOR FLUID ACTUATED PUMPS Filed Jan. 26, 1959 s Sheets-Sheet 1 A i F151.

INVENTOR. 6 05/ hf Del/ridden Quad AT MRNEY;

Jan. 3, 1961 R. H. DEITRICKSON 2,966,895

CONTROL VALVES F OR FLUID ACTUATED PUMPS 5; i i- BY QMQQL R. H. DEITRICKSON CONTROL VALVES FOR FLUID ACTUATED PUMPS Jan. 3, 1961 3 Sheets-Sheet 3 BYQMJLQQEMH Filed Jan. 26, 1959 United rates Patent Q CONTROL VALVES FOR FLUID ACTUATED PUMPS Roy H. Deitrickson, Allison Park, Pa., assignor to The National Supply Company, Pittsburgh, Pa., a corporation of Ohio Filed Jan. 26, 1959, Ser. No. 788,983

3 marinas. (Cl. 121-123) This invention relates to control valves for fluid operated downwell pumps and is particularly directed to a construction in which the control valve for directing fluid to the space above the engine piston, and for discharging fluid from such space, is carried within the piston.

The control valve of the present invention is utilized in a fluid actuated engine of the type having differential area upper and lower faces so that if the smaller face of the engine piston is exposed to high pressure fluid at all times and the other and larger face of the piston is alternately exposed to high pressure and low pressure fluid reversal of movement of the piston will occur.

The primary object of the invention is to provide a control valve for a downwell pump in which a biasing force tending to hold the valve in one position is derived from a flow of power fluid from a source, across a portion of the valve, to discharge. According to the invention, the valve shifts out of the position to which it is biased by such flow, to a reversed position when such flow ceases.

Another object of the invention is to provide a valve which shifts to a reversed position in one direction in response to the application of power fluid, and to the opposite position in response to the disappearance of a biasing force derived from a flow of power fluid from a source, across a portion of the valve, and to discharge.

Other objects and advantages of the invention will become apparent from the following specification, reference being had to the accompanying drawings, in which:

Figure 1 is a fragmentary and diagrammatic central longitudinal sectional view of a hydraulic engine embodying the present invention, the valve spool portion being shown in elevation; V i V Fig. 2 is a fragmentary longitudinal sectional viewrof the engine with the valve in the down stroke position;

Fig. 3 is a view similar to Fig. 2 with the valve and piston in the position occupied during bottom reversal;

Fig. 4 is a view similar to Fig. 2 with the valve in the upstroke position; and i Fig. 5 is a view similar to Fig. 2 with the valve in the position occupied during top reversal.

The invention consists of a pressure actuated valve carried within the piston of-a fluid operated engine, and reversing its position at the'top and bottom of the stroke of the piston in response to a change in pressure on one or more control surfaces formed on the valve; in one direction of movement of the piston the change in pressure is brought about by the registration of a port with a source of high pressure fluid, but in the other direction of movement the change in pressures is caused by cutting off a previously existing flow of fluid. Thus the valve undergoes a powered reversal at one end of its stroke, and reverses in response to a biasing pressure at the opposite end of the stroke.

When in one position, the valve serves to connect the engine cylinder above the piston with a source of high pressure operating fluid, while in its second position the valve serves to connect this same cylinder space with a lower, or discharge pressure.

As used in the following specification and in the claims, the term hydraulic force covers the summation of hydraulic forces acting at any given time in any one direction. The hydraulic force can be created in either of two ways: first, by exposing equal areas to dflerent and oppositely acting pressures; secondly, by exposing different and opposed areas to the same pressure. It should also be noted that, as used in the following specification, the terms up and down and other forms thereof such as upwardly, downwardly, upstroke and down stroke relate to the orientation of the embodiments described and are not limitations either upon the positions of the parts in other embodiments of the invention or to be interpreted as limiting the invention to such positions or directions.

Reference numerals have not been carried to all of the figures of the drawings except to the extent necessary to explain fully the operative relationship of the parts and the hydraulic forces involved in each of the several positions of the valve occupied during reciprocation of the engine piston.

Engine construction A control valve embodying the invention is intended to be employed witha fluid actuated engine for a downwell pump of the general type that is located at or near the bottom of a well casing fragmentarily indicated in the figures by the reference numeral 20. The casing 20 contains tubing 21 in the usual manner and an annulus 22 between these two conduits may be used for any desired purpose. In illustrating the engine of the downwell pump it will be assumed that the pump itself is of the type well known in the art which discharges its production fluid, that is the crude oil drawn from the formation, either into the annulus 22 above described, or into a pipe or conduit especially adapted for the purpose.

The engine for a downwell pump of this general type has an engine cylinder 23 which carries at its top a fitting 24, including a valve assembly 25 by which power fluid may be taken from the tubing 21 if the pump is of the free type. This arrangement is well known in the art. The engine cylinder 23 is spaced from the interior of the tubing 21 to provide a power fluid annulus 26 which is filled at all times with power oil supplied from the surface through the fitting 24 and valve 25. The annulus 26 is connected through ports 28 at the lower end of the engine cylinder to the interior of the cylinder beneath the engine piston which is designated generally 29.

Below the engine cylinder is a stufling box 30 through which pump piston rod 32 extends to connect the engine and pump pistons in the usual manner. The pump piston is not shown in the drawings. The stufling box 30 separates the engine cylinder, which contains high pressure oil, from a space 33 which represents the power oil discharge space and thus contains low pressure oil.

Within the engine cylinder 23 the engine piston 29 is operated by means of the power fluid supplied from the surface. The piston comprises a close fitting section 34 and a portion of smaller diameter therebelow which is designated 35 in the drawings and which contains the valve parts hereafter described.

Within the piston, a

valve jacket

36, 36a is provided which is formed to cooperate with a spool-type valve the body of which is designated 37. The jacket itself is preferably made in upper and lower parts for ease of assembly and each part is drilled with the various-supplies and exhaust passages hereafter described.

The spool valve 37'is a hollow cylindrical member guided by its various lands for reciprocation within the

jacket

36, 36a. During the down stroke, the valve stands in an upper position, and during the upstroke of the piston 29 the valve stands in a 'lower position. The periphery of the valve is stepped to provide close fitting lands, A, B, C, D and E which serve to separate fluids at various pressures from each other, and to provide differential area shoulders against which pressures can act to move the valve from one position to the other. A differential area shoulder occurs between lands of the valve and represents a step in diameter. Thus, a chamber formed by such lands or shoulders may have, for example, an area greater by .040 square inch on one side than on the other. If such a chamber is filled with oil at 2000 p.s.i., a force of 80 pounds will be set up tending to move the valve in the direction of the larger area land or shoulder.

The engine piston 29 is, as above stated, connected to a pump piston (not shown) by piston rod 32 which is hollow and thus provides a central discharge passage 39. The passage 39 connects to a main discharge port 40 which is at all times below the stuffing box 39 and is diagrammatically indicated in Figs. 1 and 2.

The piston rod 32 is provided with an additional, separate longitudinal passage 41 which terminates in a lateral rod port 42 and which, at its upper end, communicates with a passage 43 in the jacket which, in turn, supplies fluid to an annular space 44 between differential area lands D and E on the valve body. Since land E is made smaller in diameter than land D, the pressure of a fluid introduced into chamber 44 will tend to move the valve body upwardly. Such action will be described in connection with the top reversal of the valve hereinafter. As will also be more fully described hereinafter, the lateral rod port 42 moves temporarily above the stuffing box 30 at the end of the upward stroke of the engine piston with the result that the pressure conditions in

passages

41 and 43 and in chamber 44 change abruptly at this point in the stroke.

Down stroke Figure 2 of the drawings shows the valve in the position occupied while the engine piston is making a down stroke. Fluid is supplied from the power fluid annulus 26 through one or more main supply ports 28 below the engine piston. These ports are never cut off during operation, and the lower end of the power cylinder is constantly filled with high pressure power oil. Power oil is taken around the lower piston section 35 to a supply port Si in the side wall of the piston to a chamber 51 in the valve jacket, through an annular passage formed between lands A and B on the valve body, which passage is designated 52, through a port 53 in the valve jacket to an upwardly extending passage 54 which communicates with the cylinder space above the engine piston. Since the top of the engine piston has a greater efiective area than the lower side thereof, due to the presence of the piston rod, the piston will move downwardly .if the pressure times the area of the upper face is greater than the pressure times the area of the lower face.

During the down stroke of the piston the lateral rod port 41 in the wall of the piston rod 32 is below the stuffing box fill and is thus exposed to oil at discharge pressure.

The differential area shoulders formed on the valve spool result in the following areas which are subject either to power oil or discharge pressures and which result in moving the valve from one position to the other:

The valve of the present invention is biased to stand in its upper position during the down stroke by a pressure which occurs in chamber 56 between lands C and D. This chamber is connected to the central discharge or exhaust passage 39 of the valve by a restricted central port 57 and is supplied with oil from a larger jacket passage 58 which, in turn, receives oil from a passage 59 in the side of the piston. It will be seen that the flow of oil from the cylinder space around the piston thus passes directly to discharge whenever

passages

59, 58 and 57 are open and that this flow of oil bypasses the engine cylinder completely. Thus chamber 56 is constantly filled with oil at a pressure between the power oil and discharge pressures until its supply port 58 is cut off. Port 58 is made considerably larger than the discharge port 37 so that a positive pressure, well above the exhaust pressure, will act constantly in this chamber. Thus the upper wall or step of the chamber will act to hold the valve upwardly but as soon as the

supply ports

58 and 59 are cut off the contents of the chamber will bleed to discharge pressure and the biasing force that existed on the bottom shoulder of land C will disappear.

Bottom reversal To cause the bottom reversal of the valve, the cylinder wall 23 is provided with a land 60 in line with the path of movement of supply port 59 as indicated in Fig. 3. When port 59 registers with the land 60 the supply of power oil flowing into the chamber 56 is cut off and the chamber commences to bleed down to the exhaust pressure through port 57. If it is found that this bleed flow through port 57 is not sufficiently rapid to accomplish the reversal of the valve in a desired time, the flow may be supplemented by opening a secondary discharge port 62 in the valve body to a lateral port 63 connected to a longitudinal passage in the jacket. The longitudinal passage is designated 64 in Fig. 3 and connects directly with the interior of the chamber 56. Thus, when the valve starts to reverse, the reversing movement will continue at a rather slow pace until port 62 is opened when the reversal will be quickly completed. Thus, provision is made for a rapid reduction in the biasing force that was holding the valve in its upper position during the down stroke, and the pressure of the power oil above the valve and in chamber 51 will predominate to cause the bottom reversal movement.

The reversal of the valve continues until its lower position is attained which corresponds to the position desired for the valve during the upstroke, which position is shown in Fig. 4.

Upstroke As previously noted the upstroke of the piston is caused by the pressure of power oil on its lower face from supply ports 28 at the same time that the top of the piston is subjected only to the pressure of the discharge, the top cylinder space being opened to discharge by the opening of port 53 directly to the hollow interior of the spool valve and the main discharge passage 39. Oil then fiows from the top of the cylinder through port 53, through the central discharge passage 39 and outwardly through the lateral piston rod ports 40 at the bottom thereof.

The valve is biased to stand in the lower position by reason of the small shoulder that occurs by the difference in diameter between lands A and B. Thus power oil is constantly present in the chamber 52 above land B and this picture, acting downwardly, holds the valve in its lower position during the entire upstroke. The remaining chambers around the valve, between the lands, are all subjected to exhaust pressure at this time.

The upstroke of the piston continues until the piston is arrested in the usual manner and the top reversal of the valve takes place.

Top reversal The position of the valve and piston rod during top reversal is shown in Fig. 5.

The top reversal of the valve is caused by the lower rod ports 42 running above the stuffing box 30 and thus communicating directly with power oil above the stufling box entering the cylinder space through the main supply passages 28. High pressure oil then enters the longitudinal rod passage 41 and the jacket passage 43 to fill chamber 44 between lands D and E. Since land E is smaller than land D, the presence of power oil in the chamber 44 will press upwardly on the valve and will force it to move in an upward direction to assume the position desired for the downstroke of the piston. The movement of the valve continues upwardly, and before the rod port 42 is closed, the down stroke will have started. The down stroke will continue as described above.

In the form of the invention shown, the top reversal of the valve is caused by the rod port 42 running above the stufiing box 30 and thus accepting oil at high pressure. Various other means of accomplishing this top reversal may be used.

While the invention has been disclosed in conjunction with a specific form and disposition of the parts, it should be expressly understood that numerous modifications and changes therein may be made without departing from the scope of the appended claims.

What I claim is:

1. In a hydraulic engine having a cylinder, a source of power fluid, means forming a discharge passage, and a piston slidable in said cylinder, a reversing valve comprising, in combination, a slidable cylindrical valve body, a passageway controlled by said valve body and open when said valve body is in a first position for connecting one end of said cylinder to said source, said valve body when in a second position closing said passageway, a chamber around said valve body in constant communication with said discharge passage, said communication being through a restricted orifice, a port connecting said chamber to said source when said valve stands in its first position, said port being larger than said restricted orifice whereby a biasing pressure exists in said chamber when said port is open tending to hold said valve in its first position, and means operable at the end of the stroke of said piston to close said port, whereby said chamber bleeds to discharge pressure and said valve moves to its second, reversed position.

2. In a hydraulic engine having a cylinder, a source of power fluid, means forming a discharge passage, and a piston slidable in said cylinder, a reversing valve comprising, in combination, a slidable cylindrical valve body,

a passageway controlled by said valve body and open when said valve body is in a first position for connecting one end of said cylinder to said discharge passage, a chamber around said valve body having difierential area walls, means to connect said chamber to said source to impose a pressure in said chamber, said difierential area walls acting to hold said valve body in its first position, and means operable at the end of the stroke of said piston to impose an opposite pressure on said valve body to overcome said first pressure and to move said valve body to a reversed position in which said end of said cylinder is connected to said source.

3. In a hydraulic engine having a cylinder, 21 source of power fluid, means forming a discharge passage, and piston slidable in said cylinder, a reversing valve comprising, in combination, a slidable cylindrical valve body, a passageway controlled by said valve body and open when said valve body is in a first position for connecting one end of said cylinder to said source, said valve body when in a second position closing said passageway and simultaneously establishing a connection between said one end of said cylinder and said discharge passage, a first chamber around said valve body in constant communication with said discharge passage, said communication being through a restricted orifice, a port connecting said chamber to said source when said valve stands in its first position, said port being larger than said restricted orifice whereby a biasing pressure exists in said chamber when said port is open tending to hold said valve in its first position, means operable at the end of the stroke of said piston in a first direction to close said port, whereby said chamber bleeds to discharge pressure and said valve moves to its second, reversed position, and a second chamber around said valve body having differential area walls, means to connect said second chamber tosaid source to impose a pressure in said chamber, said differential area walls acting to hold said valve body in its second position, and means operable at the end of the stroke of said piston in a second direction to impose an opposite pressure on said valve body to overcome the pressure in said second chamber and to move said valve body to its first position in which said end of said cylinder is connected to said source.

References Cited in the file of this patent UNITED STATES PATENTS 1,907,951 Gage May 9, 1933 2,682,257 Deitrickson June 29, 1954 2,851,013 Doughton Sept. 9, 1958 2,870,749 Deitrickson Jan. 27, 1959