US2665709A

US2665709A - Valve operating mechanism

Info

Publication number: US2665709A
Authority: US
Inventors: Harvey Herbert
Original assignee: United States Steel Corp
Current assignee: United States Steel Corp
Priority date: 1949-02-25
Filing date: 1951-11-28
Publication date: 1954-01-12
Anticipated expiration: 1971-01-12

Description

VALVE OPERATING MECHANISM Original Filed Feb. 25, 1949 3 Sheets-Sheet l INVENTOR. HERBERT HARVEY lbw/5i 4% HIS ATTORNEY Jan. 12, 1954 HARVEY 2,665,709

VALVE OPERATING MECHANISM Original Filed Feb. 25, 1949 5 Sheets-Sheet 2 INVENTOR. HERBERT HARVEY fomzw 44% HIS ATTORNEY Jan. 12, 1954 H. HARVEY 2,665,709

VALVE OPERATING MECHANISM Original Filed Feb. 25, 1949 3 Sheets-Sheet 5 INVENTOR. HERBERT HARVEY HIS ATTORNEY Patented Jan. 12, 1 954 VALVE OPERATING MECHANISM Herbert Harvey, Los Angeles, Calif., assignor to I United States Steel Corporation,

of New Jersey Original application Fe a corporation bruary 25, 1949, Serial No.

78,294. Divided and this application. November 28, 1951, Serial No. 258,709

Claims. (Cl. lea-s) 1 This invention relates to an improved mechanism for operating pilot controlled slide valves in hydraulic circuits, such as fluid pressure actuated pumping units.

The present application is a division of my earlier application Serial No. 78,294, filed February 25, 1949, entitled Fluid Pressure Actuated Pumping Unit."

An object of the present invention is to provide a fluid pressure mechanism for operating a slide valve, which mechanism is of simple construction and consumes a minimum of fluid in its own operation.

A further object is to provide a slide valve operating mechanism in the form of a cylinder and piston housed within a valve body, whereby the piston is motivated in one direction by pressures existing within this valve body, making it necessary to supply operating fluid from an exfternal source to motivate the piston in the other direction only and eliminating stuffing boxes.

' A further object is to provide a slide valve operating mechanism in the form of a piston and cylinder which loses fluid from a hydraulic circuit only when it moves the slide valve in one direction, thereby substantially reducing the volume of fluid which must be replenished to the circuit.

In accomplishing these and other objects of the invention, I haveprovided improved details of structure, a preferred form of which is shown 1 in the accompanying drawings, in which:

Figure l is a schematic view of a hydraulic circuit like that embodied in the pumping unit shown and claimed in my aforesaid earlier application, but simplified by the omission of parts unnecessary for an understanding of the present invention; Figure 2 is a vertical sectional view of the main valve and its operating mechanism em- ,hodying ieatures of the present invention, the parts being in the downstroke position; and

Figure 3 is a vertical sectional view of these same parts taken onthe line III-III of. Figure .2, the parts being in the upstroke position,

Figure 1 shows a pumping unit which comprises a main cylinder [0, a single acting ram [2 reciprocable therein and connected to a sucker rod string l3, a motivating pump 14, a main IQIlIf-Wflfil yalve .1 5, a pilot valve [6,. pressure accumulator tanks l1 and I8 and a reservoir I9. Pump I4 is driven by any suitable drive means, not shown. To produce an upstroke of the ram, the pump M takes in hydraulic fluid from tank 18 via a pipe 20, main valve 15, and a pipe 2| and discharges this fluid via a pipe 22, main valve [5 and a pipe 23 to the lower end of cylinder I0. To produce a downstroke the main valve shifts, as hereinafter explained, so that the motivating pump takes in fluid from cylinder M via pipe 23, main valve l5 and pipe II and discharges this fluid via pipe 22, main valve I5 and pipe 20 to tank I8. Tanks l1 and 18 are in free communlcation with each other through an overflow connection 24. Tank l1 contains air under pressure, which is supplied from any suitable source not shown, and the pressure of which is applied to the fluid in tank l8 via the overflow connection. On the upstroke 01' the ram this pressure supercharges the motivating pump l4, and on the downstroke cushions the ram, which descends gravitationally.

Pilot valve l6 has a shiitable element which can be shifted back and forth by any suitable means at the ends of the. ram strokes.

Pipes

25, 26 and 21 are shown connected to the pilot valve for producing such shifting. In one position the pilot valve directs fluid under pressure from pipe 22, which is connected to the motivating pump discharge, via a pipe 28 to the operating mechanism. for the main valve ii. In its other position the pilot valve relieves this operating mechanism via a pipe 29 which extends to the reservoir 19, A scavenger pump ,38 returns fluid from reservoir l8 to tank [8 via pipes 3| and 32, the latter of which has a check valve 33. Since pilot valves which can function in this fashion are well known, no detailed disclosure is included in the present application, although reference can be made to my aforesaid application fora disclosure of. one exemplary construction of a suitable pilot valve.

In accordance with the present invention, the main valve 15 includes a cylindrical body 34, the upper end of which carries the pilot valve 6. Two opposite side walls of body 34 have

ports

35 and 36, to which the

pipes

22 and 23 respectively are connected (Figure 3). Another side wall has a port 31 to which the pipe 20 is connected. The hottomhas a port .38to which the pipe 2! is connected (Figure 2). The side wall opposite the port 31 has two

ports

39 and 40 adjacent its upper and lower ends connected by a manifold 4| (Figure 2) A piston-type slide 42 is mounted for reciprocable movement in the body 34 and has an upper piston 43 and a lower piston 44.

manifold M with pipe 2| to the pump intake and pipe 22 from the pump discharge communicates with pipe 23 to the main cylinder I to effect an upstroke. The

ports

39 and 40 and manifold 4|. at all times furnish free communication between the upper and lower end portions of the valve body 34, and these ends in both positions of slide 42 are subjected to a positive pressure, derived either from the main cylinder ID on the downstroke or from the tank 18 on the upstroke.

The operating mechanism of the present invention includes a cylinder 45 housed within the upper portion of the valve body 34, being illustrated as integral with the top wall thereof. The upper end of the valve slide 42 carries a piston rod 46 and a piston 41, the latter being reciprocable in cylinder 45. The bottom or inner wall -of said cylinder contains an opening 48 of somewhat larger diameter than piston rod 46. Consequently the pressure in the upper part of the valve body is at all times applied to the bottom or inner side vof piston 41 and tends to push this .piston and the valve slide 42 upwardly to the downstroke position shown in Figure 2.

The pilot valve [6 has ports 49 which communicate with the upper end of cylinder 45. When the shiftable element of the pilot valve is in the downstroke position, ports 48 are relieved to pipe 29 and reservoir [9. Consequently pressure on the bottom of piston 41 moves this piston and the valve slide upwardly. When the shiftable element of the pilot valve is in the upstroke position, ports 49 receive pressure from the discharge of the motivating pump i4 via pipe 28. This pressure is greater than that within the valve body; consequently this pressure forces the piston 41 and the valve slide downwardly. It is seen that the pressures on the top of piston 43 and on the bottom of piston 44 substantially balance each other, but the small differential, which is due to the greater effective area of the latter, merely assists the pressure applied to the bottom of piston 41.

To cushion the movement of piston 41 and valve slide 42, the piston rod 46 carries lower and upper collars 58 and 52a which are adapted .to fit rather closely within the opening 48, although the fit is not fluid-tight. Near the ends .of the stroke of piston 41 one of these collars :enters the opening 48 and produces a dash-pot effect, which decelerates and cushions the movement. The lower end of cylinder 45 can have a depending annular flange SI and piston rod 46 can have an additional collar 52 which fits within said flange to furnish additional cushioning on upward movement of the piston.

From the foregoing description it is seen that the main valve slide 42 moves upwardly under the influence of pressure which always exists within the main valve body 34. It is necessary to supply pressure from an outside source only to move the main valve slide downwardly. It is necessary to relieve the main valve operating mechanism only as the slide moves upwardly. Thus only the upward movement loses fluid from the main circuit to the reservoir I9, and the scavenger pump 38 needs to return a minimum of fluid to the tank I8. At the same time the need for stuffing box connections to the main valve and its operating mechanism is completely eliminated.

While I have shown and described only a single embodiment of the invention, it is apparent that modifications may arise. Therefore, I do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.

I claim:

1. The combination with a four-way slide valve which includes a cylindrical body having ports in its walls, a slide reciprocable in said body and having two positions providing different communication among said ports, and means furnishing free communication between the opposite end portions of said body, said end portions bein adapted to be Subjected to a positive pressure in both positions of said slide, of an operating mechanism comprising a cylinder housed within one end portion of said body and fixed to the end wall thereof, a piston reciprocable in said cylinder, a piston rod attached to said piston and to said slide, said cylinder having an inner end wall which has a passage larger than the cross section of said piston rod and through which said piston rod extends, said passage furnishing free communication for subjecting the inner face of said piston to the pressure within the end portions of said body, and means for applying pressure to and relieving said cylinder on the other side of said piston.

2. The combination with a four-way slide valve which includes a cylindrical body having at least three ports in its side walls and a port in one end wall, a slide reciprocable in said body and having two positions providing different communication among said ports, and ports and a mani fold furnishing free communication between the opposite end portions of said body, said end portions being adapted to be subjected to a positive pressure in both positions of said slide, of an operating mechanism comprising a cylinder housed within the end portion of said body opposite the end wall which has the port and fixed to the end wall, a piston reciprocable in said cylinder, a piston rod attached to said piston and to said slide, said cylinder having an inner end wall which has a passage larger than the cross section of said piston rod and through which said piston rod extends, said passage furnishing free communication for subjecting the inner face of said piston to the pressure within the end portions of said body and means fixed to the end of said body for applying pressure to and relieving said cylinder on the other side of said piston.

3. A combination as defined in claim 2 in which the operating means also comprises means for cushioning the movement of said piston near the ends of its strokes.

4. A combination as defined in claim 2 in which said piston rod has spaced apart collars adjacent said piston and said slide, which collars are adapted to be received in the passage in the inner end wall of said cylinder for cushioning movement of said piston near the ends of its strokes.

5. The combination with a four-way slide valve which includes a cylindrical body having ports in its walls, a slide reciprocable in said body and having two positions providing different com- 5 munication among said ports, and means furnit-hing free communication between opposite end portions of said body, of an operating mechanism comprising a cylinder housed Within one end portion of said body and fixed to the end wall thereof, a piston reciprocable in said cylinder, a piston rod afiixed at one of its ends to said piston and at its other end to said slide so that movement of said piston in either direction moves said slide correspondingly, the face of said piston which is directed toward said slide being always exposed to the pressure existing within the end portions of said body, means for applying a posi- References Cited in the file of this patent UNITED STATES PATENTS Name Date Delaney Feb. 19, 1935 Richardson July 16, 1940 Number